1,359 results
Search Results
52. A Z-Source-Derived Coupled-Inductor-Based High Voltage Gain Microinverter.
- Author
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Surapaneni, Ravi K. and Das, Pritam
- Subjects
ELECTRIC inverters ,DIRECT currents ,ELECTRIC potential ,ELECTRIC inductors ,IMPEDANCE parameters (Computer networks) ,PHOTOVOLTAIC effect - Abstract
Microinverters require high voltage gain capability for interfacing the low dc voltage output of photovoltaic (PV) module to single-phase ac grid. A two-stage nonisolated inverter is proposed in this paper, with a first boost stage and a second traditional pulse width modulated grid-tied inverter stage. The proposed boost stage consists of a coupled inductor added with a voltage multiplier to achieve the required high voltage gain at high efficiency and to operate over a wide input voltage range. Among the coupled inductor topologies, adding a clamp circuit is a common solution to limit the voltage spike caused by leakage inductance. In the proposed converter, the resonance between the coupled inductor and voltage multiplier is used to address the issue of voltage spike, thereby reducing both component count and device voltage stress. Detailed analysis and design procedure of the proposed converter is presented in this paper. Experimental results of a 250-W microinverter are presented to validate the proposed converter. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
53. Reduced Multilevel Converter: A Novel Multilevel Converter With a Reduced Number of Active Switches.
- Author
-
Norambuena, Margarita, Kouro, Samir, Dieckerhoff, Sibylle, and Rodriguez, Jose
- Subjects
DC-AC converters ,ELECTRIC current converters ,POWER electronics ,ELECTRIC power supplies to apparatus ,INDUSTRIAL electronics - Abstract
This paper presents a new multilevel converter topology based on a variable or multilevel dc-link stage. This stage is shared by all inverter output phases, thus increasing the number of output voltage levels while reducing the overall number of active devices compared to traditional topologies; therefore, it is called a reduced multilevel converter (RMC). The converter is not capable of reducing the blocking voltage of the devices; hence, unlike other multilevel converters aimed at medium-voltage applications, this converter is interesting for low-voltage- and high-power-quality-demanding applications such as photovoltaic inverters, wind energy conversion systems, and uninterruptible power supplies. The main novelty behind the proposed concept is the basic dc cell used to generate the variable dc-link voltage, which includes a controlled path through the floating capacitors to provide the necessary degree of control to enable a shared multilevel dc link for all the output phases of the converter. The dc cells are connected in a multicell structure to increase the number of levels of the converter. A five-level version of the RMC topology is briefly compared to other five-level converters such as the five-level active neutral-point-clamped converter and the five-level flying capacitor converter. This paper presents the structure of the new topology with its operating principle, switching states, main characteristics, and experimental validation using finite-control-set model-predictive control. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
54. Mitigation of Current Distortion in a Three-Phase Microinverter With Phase Skipping Using a Synchronous Sampling DC-Link Voltage Control.
- Author
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Tayebi, S. Milad and Batarseh, Issa
- Subjects
BUS conductors (Electricity) ,CAPACITORS ,VOLTAGE-frequency converters ,ELECTRIC capacity ,PHOTOVOLTAIC power generation - Abstract
To improve light load efficiency, a three-phase photovoltaic (PV)-based microinverter may operate in single-phase, two-phase or three-phase mode depending on the available input power. Therefore, its dc-link capacitor may be subjected to large peak-to-peak voltage ripple when operating in phase skipping mode. This paper determines the minimum value of the dc-link capacitor by allowing the maximum acceptable voltage ripple on the dc link. This allows for the use of film capacitors instead of electrolytic capacitors in order to improve the microinverter reliability. Unfortunately, higher dc-link voltage ripple introduces harmonic distortion on the inverter output current waveform if it is not compensated for by the dc-link voltage controller. This paper proposes a simple synchronous control method to regulate the dc-link voltage with the presence of large voltage ripple. The dc-link voltage controller is synchronized with the phase-locked loop and samples the average value of dc-link voltage without introducing unwanted harmonics into the voltage sense path. Experimental results were obtained from a 300-W three-phase half-bridge microinverter prototype to verify the proposed dc-link voltage control performance. Inverter output current total harmonic distortion of 1.6% was achieved even though the dc-link peak-to-peak voltage ripple reached as high as 87 V with 219-V split dc-link voltage. Dynamic response is fast enough to easily track the most extreme ramp change in input PV power. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
55. Efficiency of a CVT-Operated EVT Experimentally Evaluated Against Half-Toroidal and Push-Belt CVTs.
- Author
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Druant, Joachim, Vansompel, Hendrik, De Belie, Frederik, and Sergeant, Peter
- Subjects
CONTINUOUSLY variable transmission ,ELECTRIC motors ,ELECTRIC power ,ELECTRIC inverters ,NUMERICAL analysis - Abstract
This paper describes how an electrical variable transmission (EVT) can be used as an alternative for mechanical continuously variable transmission (CVT) systems. An EVT is an electromagnetic power split device having two mechanical and two electrical ports. The speed ratio between both mechanical ports (rotors) can be varied in a continuously variable way, so that this machine can be used as an electromagnetic alternative for the mechanical push-belt and half-toroidal CVT. Its operating principle is based on splitting the power into an electromagnetic direct path and an electrical path involving two inverters connected back to back. Its potential use as a CVT is investigated by comparing experimental data against toroidal and belt CVT data from literature having comparable power ratings. To this end, measurements are performed on a prototype \text120-kW permanent magnet EVT. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
56. New Half-Bridge and Full-Bridge Topologies for a Switched-Boost Inverter With Continuous Input Current.
- Author
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Asl, Elias Shokati, Babaei, Ebrahim, Sabahi, Mehran, Hasan Babayi Nozadian, Mohsen, and Cecati, Carlo
- Subjects
ELECTRIC inverters ,ELECTRIC currents ,ELECTRIC potential ,AUTOMATIC control systems ,NUMERICAL analysis - Abstract
In this paper, new half-bridge and full-bridge topologies for a switched-boost inverter are proposed. These topologies have a high boost factor in comparison with conventional types. In addition, the proposed topologies have continuous input current and can generate zero-voltage level in output. In this paper, the operation of the proposed inverters in different operating modes is analyzed. Then, the values of inductors and capacitors are designed. Moreover, the used switching pattern and its logical diagram are introduced. A comprehensive comparison between the proposed and conventional topologies in terms of the boost factor, the number of elements, and the efficiency shows the good features of the proposed inverters. Finally, to verify correct operation of the proposed topologies and derived equations, simulation and experimental results are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
57. A Novel Carrier-Based Hybrid PWM Technique for Minimization of Line Current Ripple in Two Parallel Interleaved Two-Level VSIs.
- Author
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Shukla, Kapil, Malyala, Varun, and Maheshwari, Ramkrishan
- Subjects
PULSE width modulation transformers ,VOLTAGE regulators ,ELECTRIC currents ,ELECTRIC inverters ,EXPERIMENTS - Abstract
A novel hybrid pulse width modulation (PWM) technique is proposed in this paper for two parallel interleaved, two-level, three-phase voltage source inverters (VSIs). The two parallel interleaved VSIs are analyzed as a three-level (3L) inverter. A 3L inverter provides minimum line current ripple when nearest three voltage vectors are applied. In this paper, a novel carrier-based PWM technique is developed that ensures the application of nearest voltage vectors, keeping average circulating current to zero over a switching period. For carrier-based implementation of the proposed PWM, generalized common-mode (CM) offsets are derived in terms of maximum and minimum values of reference signals. Each 3L space-vector sector is divided into seven subsectors. For each subsector, a CM offset is calculated, addition of which to reference signals ensures the minimum line current ripple and zero average circulating current. Simulation and experimental results are provided to validate the proposed technique. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
58. Analysis and Stabilization of a Smart Transformer-Fed Grid.
- Author
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Zou, Zhi-Xiang, Liserre, Marco, and Buticchi, Giampaolo
- Subjects
DAMPING (Mechanics) ,ELECTRON tube grids ,TRANSFORMER magnetic circuits ,SOLID-state phase transformations ,STABILITY (Mechanics) - Abstract
The stability of the grid-connected inverters adopted in distributed energy resources (DERs) highly depends on the characteristics of the grid impedance. Hence, various active damping methods and adaptive control algorithms have been proposed for the control of the grid inverters. Differently from those existing solutions, this paper proposes to use a smart transformer (ST) to shape the grid impedance to interact with the controllers of local inverters, aiming at improving the stability of the local controllers as well as the overall grid. A main advantage of this solution is that it offers a pervasive service to all the available DERs, reducing the cost and design effort of the local controllers. Three active damping methods are presented in this paper and the implementation issues in the ST LV-side voltage controller are given. Moreover, the design criteria of the active damping methods considering the control performance of ST and the stability requirements of local DERs are presented. Analysis and experiments are carried out to verify the effectiveness of the proposed solution. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
59. Comparison of SiC Voltage Source Inverters Using Synchronous Rectification and Freewheeling Diode.
- Author
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Yin, Shan, Liu, Yitao, Liu, Yong, Tseng, King Jet, Pou, Josep, and Simanjorang, Rejeki
- Subjects
ELECTRIC potential ,CONVERTERS (Electronics) ,CONDUCTION electrons ,DIODES ,ELECTRIC inverters - Abstract
For power converters with inductive loads, a freewheeling path is needed for the current due to reactive power. The
MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiCMOSFET exhibits a high voltage drop. Hence, an antiparallel SiC Schottky diode is normally implemented to eliminate its conduction. However, the external SiC Schottky diode is not fully utilized as it only works during the dead time. In this paper, the hard-switching SR is investigated in an SiC three-phase inverter and compared with a conventional inverter using freewheeling diode (FWD). An improved power loss model for the two inverters has been developed. It is found that the inverter using SR has higher efficiency due to the smaller switching loss. A 7-kW prototype of SiC three-phase inverter is built, which achieves a peak efficiency of 98.8% ($\pm$ 0.15%) and 98.5% ($\pm$ 0.15%) at 40 kHz using SR and FWD, respectively. This paper confirms that the SiCMOSFET is an ideal candidate for the SR. [ABSTRACT FROM PUBLISHER]- Published
- 2018
- Full Text
- View/download PDF
60. DC–DC MMC for HVdc Grid Interface of Utility-Scale Photovoltaic Conversion Systems.
- Author
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Rojas, Christian A., Kouro, Samir, Perez, Marcelo A., and Echeverria, Javier
- Subjects
PHOTOVOLTAIC power systems ,ELECTRIC transformers ,HIGH-voltage direct current transmission ,MAXIMUM power point trackers ,CONVERTERS (Electronics) - Abstract
This paper explores a utility-scale photovoltaic (PV) plant configuration based on a dc–dc stage interfaced directly to a modular multilevel converter (MMC) used for an HVdc power station. Since PV systems are dc by nature, the proposed solution has several advantages, such as full dc operation and step-up transformers avoidance with modular and reliable configuration. The contributions of this paper are the experimental validation of the proposed utility-scale configuration, while the conventional modulation stage has been further enhanced by including an adaptive phase-shifted modulation allowing improved voltage and current waveforms injected to dc grid under unbalanced power string operation. The enhanced performance is obtained by reducing the carrier frequency component of the converter voltage, generating an improved voltage ripple. Finally, experimental validation during steady-state and dynamic operation are presented to illustrate the behavior of the dc–dc MMC converter managed by the proposed modulation and control scheme. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
61. Performance Evaluation of the Single-Phase Split-Source Inverter Using an Alternative DC?AC Configuration.
- Author
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Abdelhakim, Ahmed, Mattavelli, Paolo, Davari, Pooya, and Blaabjerg, Frede
- Subjects
RENEWABLE energy sources ,QUASIPARTICLES ,SINGLE-stage accelerators ,ELECTRIC power conversion ,ELECTRONIC modulation - Abstract
This paper investigates and evaluates the performance of a single-phase split-source inverter (SSI), where an alternative unidirectional dc–ac configuration is used. Such configuration is utilized in order to use two common-cathode diodes in a single device instead of using two separate diodes, resulting in minimum parasitic inductance in the commutation paths. In this paper, the analysis and modulation of the single-phase SSI using this alternative configuration is discussed, and the analysis of the low-frequency component in the dc side is introduced. Moreover, the features behind employing the triangular, the trailing-edge sawtooth, and the leading-edge sawtooth carriers with the single-phase SSI are discussed, and the differences among these carriers are highlighted. In order to highlight the performance of the proposed SSI, a comparative study is conducted with the two-stage architecture and the single-phase quasi-Z-source inverter (qZSI). The introduced analysis is enhanced with simulation results using MATLAB/PLECS models, where a 1-kVA single-phase SSI is designed and simulated. Finally, the designed 1-kVA single-phase SSI is implemented experimentally and tested at different operating points, i.e., at different voltage gains, and a maximum efficiency of $95.5\%$ is obtained. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
62. The Power Quality Forecasting Model for Off-Grid System Supported by Multiobjective Optimization.
- Author
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Vantuch, Tomas, Misak, Stanislav, Jezowicz, Tomas, Burianek, Tomas, and Snasel, Vaclav
- Subjects
ELECTRIC power system control ,PARAMETER estimation ,GRID energy storage ,MACHINE learning ,PREDICTION models - Abstract
Measurement and control of electric power quality (PQ) parameters in off-grid systems has played an important role in recent years. The purpose is to detect or forecast the presence of PQ parameter disturbances to be able to suppress or to avoid their negative effects on the power grid and appliances. This paper focuses on several PQ parameters in off-grid systems and it defines three evaluation criteria that are supposed to estimate the performance of a new forecasting model combining all the involved PQ parameters. These criteria are based on common statistical evaluations of computational models from the machine learning field of study. The studied PQ parameters are voltage, power frequency, total harmonic distortion, and flicker severity. The approach presented in this paper also applies a machine learning based model of random decision forest for PQ forecasting. The database applied in this task contains real off-grid data from long-term one-minute measurements. The hyperparameters of the model are optimized by multiobjective optimization toward the defined evaluation criteria. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
63. Leakage Current Mitigation in Photovoltaic String Inverter Using Predictive Control With Fixed Average Switching Frequency.
- Author
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Rojas, Christian A., Aguirre, Matias, Kouro, Samir, Geyer, Tobias, and Gutierrez, Eduardo
- Subjects
PHOTOVOLTAIC power systems ,STRAY currents ,ELECTRIC inverters ,PREDICTIVE control systems ,VOLTAGE control - Abstract
This paper proposes and validates model predictive control as an alternative control strategy for H-bridgeneutral-point-clamped (H-NPC) converters for single-phase grid-tied string photovoltaic (PV) systems. The presented control scheme achieves good quality current waveforms with unity power factor, dc-link voltage control, and neutral-point voltage minimization. Furthermore, the predictive controller has been further enhanced by including an average device switching frequency restriction and a $dv/dt$ mitigation. The main contribution of this paper is the avoidance of the potential leakage current due to parasitic capacitance of the PV modules by using a predictive model based control technique instead of modulated schemes and eliminating high-frequency common-mode voltage components. Experimental results during steady state and dynamic operation are presented to illustrate the behavior of the H-NPC converter commanded by the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
64. Modeling and Resonance Control of Modular Three-Level Shunt Active Power Filter.
- Author
-
Feng, Ling and Wang, Yong
- Subjects
ELECTRIC filters ,ELECTRIC circuits ,ELECTRIC networks ,ELECTRICAL harmonics ,ELECTRIC waves - Abstract
Compared with the conventional central shunt active power filter (SAPF), modular designed SAPF can track the harmonics more precisely and quickly with a compact and expandable structure, which makes it a better solution for harmonic mitigation. But there are very few paper discussed about the modeling and parallel resonance issues of modular SAPF parallel system. This paper provides a modeling of three-level SAPF, aiming to guide the modular design and research the parallel resonance control method. First, a simplified modular three-level SAPF modeling is proposed based on averaging impedance modeling and small signal linearization techniques. Then, the coupling issues between modules are researched, and a self-adaptive active damping method is proposed to suppress the system resonance. Based on the modeling results, an improved three-level SAPF module topology is proposed to construct the modular system. The theoretical analysis and experimental results verify that the module topology improvement together with the damping strategy can promise the compensating bandwidth, reliability, and fast, precise harmonics tracking ability. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
65. Study of Passivity-Based Decoupling Control of T-NPC PV Grid-Connected Inverter.
- Author
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Wang, Jiuhe, Mu, Xiaobin, and Li, Qing-Kui
- Subjects
PASSIVITY (Engineering) ,PASSIVE components ,PHOTOVOLTAIC effect ,ELECTRIC power distribution grids ,SMART power grids - Abstract
For the purpose of improving the performances of T-type neutral point clamped (T-NPC) photovoltaic (PV) grid-connected inverter under large grid, a passivity-based decoupling control scheme is proposed in this paper. First, the Euler–Lagrange (EL) mathematical model of a T-NPC PV grid-connected inverter with an LC filter is built based on the power circuit and operating principles. Second, with this EL mathematical model and passivity of the inverter, the passivity-based controller is designed by the damping injecting method. Third, by adopting a proportional integral regulator to directly control direct current (dc) voltage, together with passivity-based indirect control, better performances of the dc voltage control can be further obtained. With the proposed passivity-based controller, the PV grid-connected inverter can achieve both dynamic current decoupling under the synchronous rotating dq coordinate and dc side voltage dynamic decoupling, which can improve the quality of the current connected into the power grid. The passivity-based PV grid-connected inverter is with strong robustness against parameters perturbations of resistors and attenuating the influence of delay in the inverter. Moreover, the passivity-based decoupling control scheme proposed in this paper for the T-NPC PV grid-connected inverter has a simple structure, and is easily debugged and realized in engineering. Experimental results under 10-kW prototype show that the proposed control scheme is effective. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
66. Power Decoupling Method for Single-Phase H-Bridge Inverters With No Additional Power Electronics.
- Author
-
Serban, Ioan
- Subjects
ELECTRIC inverters ,SINGLE-phase flow ,POWER semiconductors ,PULSATION (Electronics) ,CAPACITORS - Abstract
An active method for double-frequency power ripple decoupling in single-phase inverters is presented in this paper, exhibiting the main advantage of not using additional power semiconductors besides the H-bridge. The proposed method requires only two capacitors placed between the midpoint and one end of each inverter leg. An original control solution of the inverter ensures the power ripple transfer toward the two decoupling capacitors without affecting the inverter output voltage. The simple design makes the proposed solution easy to adapt for single-phase inverters in H-bridge configuration. This paper focuses on the autonomous operation mode of the inverter, detailing its operating principle and the control analysis. The system performances, including the impact of the decoupling circuit on the inverter efficiency, are assessed by means of experimental results. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
67. Dead-Time Effect Compensation Based on Additional Phase Current Measurements.
- Author
-
Lewicki, Arkadiusz
- Subjects
IDEAL sources (Electric circuits) ,ELECTRIC circuits ,PERFORMANCE of analog-to-digital converters ,PULSE width modulation transformers ,ELECTRIC inverters - Abstract
This paper proposes a new method of dead-time effect compensation. The proposed solution is based on additional phase current measurements realized by analog-to-digital converters. These measurements are carried out at the time instants specified by a pulsewidth-modulation (PWM) strategy. This makes it possible to estimate inverter currents at the commutation instants and, finally, to estimate the voltage error caused by dead time. This voltage error is compensated during the next switching period by modification of a reference voltage. The proposed solution can be used to compensate the voltage error in multilevel multiphase voltage source inverters. The experimental research studies were carried out on three-phase two-level and three-level neutral-point-clamped inverters supplying 55- and 160-kW motors, respectively. The results of the experimental investigations are presented in this paper. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
68. Adding Inverter Fault Detection to Model-Based Predictive Control for Flying-Capacitor Inverters.
- Author
-
Druant, Joachim, Vyncke, Thomas, De Belie, Frederik, Sergeant, Peter, and Melkebeek, Jan
- Subjects
ELECTRIC inverters ,POWER electronics ,INDUCTION machinery ,ALGORITHMS ,COMPUTER simulation - Abstract
As inverters are often used in critical applications, reliability is an important issue. In particular, the power electronic switches and gate drivers, the most essential components of the inverter, are vulnerable parts in real live operation. Therefore, this paper focuses on open-switch fault detection for multilevel inverters. When a single-switch open-circuit fault occurs in one of the power electronic switches, the algorithm can detect the fault and the switch that is causing it. The detection is worked out for both a linear resistive inductive load and an induction motor. The proposed algorithm is an extension of an already available finite-set model-based predictive control algorithm. Therefore, no extra hardware or measurements are required. This paper also discusses a suggested method for reconfiguration after fault detection. Computer simulation and experimental verifications validate the proposed methods. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
69. Current-Balancing Technique for Interleaved Voltage Source Inverters With Magnetically Coupled Legs Connected in Parallel.
- Author
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Capella, Gabriel J., Pou, Josep, Ceballos, Salvador, Zaragoza, Jordi, and Agelidis, Vassilios G.
- Subjects
CODING theory ,PULSE width modulation transformers ,PULSE width modulation inverters ,ELECTRIC inductors ,ELECTRIC inductance - Abstract
Connecting legs in parallel in a voltage source inverter is a way to increase the output current and, thus, its rated power. The connection can be made using either coupled or uncoupled inductors, and achieving an even contribution to the output current from all the legs is a crucial issue. Circulating currents produce additional losses and stress to the power devices of the converter. Therefore, they should be controlled and minimized. An efficient technique to attain such balance when coupled inductors are used is presented in this paper. The proposed technique can also be used when the inductors are uncoupled, since it is a particular case where the coupling coefficients are zero. This technique does not include proportional–integral controllers and does not require any parameter tuning either. The exact control action needed to reach current balance is straightforwardly calculated and applied. Experimental results are shown in this paper to verify the efficiency of the proposed balancing method. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
70. A Quad Two-Level Inverter Configuration for Four-Pole Induction-Motor Drive with Single DC Link.
- Author
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N., Kiran Kumar and Sivakumar, K.
- Subjects
ELECTRIC inverters ,INDUCTION motors ,PULSE width modulation ,ELECTRICAL harmonics ,ELECTRONIC modulation - Abstract
A multilevel inverter topology for a four-pole induction-motor drive is presented in this paper, which is constructed using the induction-motor stator winding arrangement. A single dc source with a less magnitude when compared with conventional five-level inverter topologies is used in this topology. Therefore, power balancing issues (which are major challenges in conventional multilevel inverters) are minimized. As this configuration uses a single dc source, it provides a path for zero-sequence currents because of the zero-sequence voltages present in the output, which will flow through the motor phase winding and power electronic switches. To minimize these zero-sequence currents, sine–triangle pulsewidth modulation (SPWM) is used, which will shift the lower order harmonics near to switching frequency in the linear modulation region. However, in the case of overmodulation, harmonic voltages will be introduced close to the fundamental frequency. In this regard, a modified SPWM technique is proposed in this paper to operate the drive in the overmodulation region up to the modulation index of 2/\!\surd3. The proposed quad two-level inverter topology is experimentally verified with a laboratory prototype on a four-pole 5-hp induction motor. Experimental results show the effectiveness of the proposed topology in the complete linear modulation region and the overmodulation region. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
71. Analytical Method for Pattern Generation in Five-Level Cascaded H-Bridge Inverter Using Selective Harmonic Elimination.
- Author
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Buccella, Concettina, Cecati, Carlo, Cimoroni, Maria Gabriella, and Razi, Kaveh
- Subjects
HARMONIC analysis (Mathematics) ,SWITCHING circuits ,ELECTRONIC modulation ,DIGITAL signal processing ,FIELD programmable gate arrays - Abstract
This paper proposes an analytical procedure for computation of all pairs of valid switching angles used in pattern generation in five-level H-bridge cascaded inverters. The proposed procedure eliminates harmonic components from inverter output voltage and, for each harmonic, returns the exact boundaries of all valid modulation index intervals. Due to its simple mathematical formulation, it can be easily implemented in real time using a digital signal processor or a field-programmable gate array. In this paper, after a detailed description of the method, simulation and experimental results demonstrate the high quality of achievable results. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
72. Modeling, Impedance Design, and Efficiency Analysis of Quasi- $Z$ Source Module in Cascaded Multilevel Photovoltaic Power System.
- Author
-
Sun, Dongsen, Ge, Baoming, Yan, Xingyu, Bi, Daqiang, Zhang, Hao, Liu, Yushan, Abu-Rub, Haitham, Ben-Brahim, Lazhar, and Peng, Fang Zheng
- Subjects
CASCADED counters ,ELECTRIC inverters ,PHOTOVOLTAIC power systems ,ELECTRIC power production ,HARMONIC motion - Abstract
The quasi- $Z$ source (qZS) cascaded multilevel inverter (CMI) (qZS-CMI) presents attractive advantages in application to photovoltaic (PV) power system. Each PV panel connects to an H-bridge qZS inverter (qZSI) to form a power generation module. The distributed maximum power point tracking and all modules' dc-link peak voltage balance can be achieved. However, it is the same with the conventional CMI that the second-harmonic ( $2\omega$) voltage and current ripples exist in each qZSI module. It is crucial for a qZS-CMI to design the reasonable qZS network parameters to limit the ripples within a desired range. This paper proposes an analytic model to accurately calculate the $2\omega$ voltage and current ripples of each qZSI module. A qZS impedance design method based on the built model is proposed to limit the $2\omega$ ripples of dc-link voltage and inductor current. Simulated and experimental results through using the designed 1.5-kW prototype validate the proposed analytic model and the design method. Furthermore, this paper analyzes all of the operating states for a qZSI module and calculates the power loss. The measured efficiency from the prototype verifies the theoretical calculation, and the qZS-CMI-based grid-tie PV power system is tested in practical. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
73. Automatic Parameter Identification of Inverter-Fed Induction Motors at Standstill.
- Author
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Carraro, Matteo and Zigliotto, Mauro
- Subjects
FINITE element method ,AUTOMOBILE engines ,MICROPROCESSORS ,INDUCTION motors ,ALGORITHMS - Abstract
As a step toward the self-commissioning of the next generation of ac drives, this work deals with an automatic procedure for the identification of the inverse-\Gamma equivalent circuit of inverter-fed induction motors (IM) at standstill. The algorithm, cut out for the modern microprocessors combines different test signals with the aim of extracting and mapping the magnetic model nonlinearity. As a key feature, the procedure uses the existing inverter as a precise voltage probe to get the complete parameter set usually required by the advanced control of ac drives. The theoretical investigations are supported by experimental results and are reported in the paper. A distinguishing characteristic of the proposed method among the other existing solutions is the accuracy of the results confirmed by the comparison with finite-element analysis tools and tailored to the laboratory IM prototypes. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
74. ILC-Based Voltage Compensation Method for PMSM Sensorless Control Considering Inverter Nonlinearity and Sampling Current DC Bias.
- Author
-
Wang, Yangrui, Xu, Yongxiang, and Zou, Jibin
- Subjects
ITERATIVE learning control ,SYNCHRONOUS electric motors ,ELECTRIC potential ,ONLINE algorithms ,HARMONIC distortion (Physics) ,PULSE width modulation transformers - Abstract
Inverter nonlinearity and sampling current dc bias can cause harmonic distortion of estimated back electromotive forces (EMFs), and therefore results in position estimation error and degrades control performance of model-based sensorless techniques of permanent-magnet synchronous motors, especially in low speed region. In this paper, the effects of inverter nonlinearity and sampling current dc bias on back EMF estimation are analyzed. A voltage feedforward compensation method based on an iterative learning control (ILC) algorithm is proposed and it is used to eliminate the harmonics of estimated back EMFs and position estimation error, so as to improve the performance of sensorless control. Compensated voltages at different rotor positions are calculated online by the ILC algorithm and stored in a lookup table. The method does not depend on current polarity and inverter model. And it is simple and easy to implement. The effectiveness of the proposed compensation method is verified by experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
75. Fault Detection and Identification Scheme for Dual-Inverter Fed OEWIM Drive.
- Author
-
Yang, Shuying, Sun, Xiaohan, Ma, Mingyao, Zhang, Xing, and Chang, Liuchen
- Subjects
FAULT-tolerant control systems ,FAULT diagnosis ,SIGNAL processing ,INDUCTION motors ,MAINTENANCE ,IDENTIFICATION ,PULSE width modulation transformers - Abstract
Dual-inverter configuration has been attracting increasing attention, especially in motor drives, for its advantages in fault tolerance, multilevel modulation effect, dc voltage utilization, etc. However, its switch fault diagnosis is difficult due to the symmetry of the two sub-inverters. A signal processing approach is proposed in this paper to detect the switch open-circuit fault occurrence and further identify the specific faulty switch, benefiting maintenance and fault-tolerant operation. In this scheme, the faulty phase and the faulty switch pair, consisting of the faulty switch and the switch on its diagonal, are identified using the stator phase currents average values. Following that, the bridge of the faulty phase is forced into a unipolar mode by artificially turning off one switch in the healthy pair continuously. Through properly controlling the duty ratios of the other switches in this bridge, the faulty switch is allowed to be further identified from the faulty pair by analyzing the behavior of the induced current in this phase. This approach is independent of either the speed or the voltage information. The effectiveness is validated through experiments on a sensorless controlled open-end winding induction motor drive. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
76. Optimal Tracking With Disturbance Rejection of Voltage Source Inverters.
- Author
-
Teng, Jiaxin, Gao, Weinan, Czarkowski, Dariusz, and Jiang, Zhong-Ping
- Subjects
IDEAL sources (Electric circuits) ,VOLTAGE regulators ,VOLTAGE control ,PULSE width modulation transformers - Abstract
This paper presents a novel voltage regulator design methodology for a three-phase voltage source inverter with uncertain load dynamics. Different from existing literature, the load is treated as a dynamic uncertainty and a robust optimal state-feedback controller is proposed through the integration of optimal output regulation theory and backstepping method. To avoid sensing the inductor current, an output-feedback control scheme is developed as well. Stability of the inverter–load system is rigorously analyzed via the small-gain techniques. It is ensured that the tracking error asymptotically converges to zero through both the proposed state-feedback and output-feedback controllers. A standard proportional resonant controller is also designed for the purpose of comparison. It is shown that the proposed controller has inherent robustness and does not require retuning with different applications. The controller design method is generalized for grid-tie applications, since the grid can be regarded as a stable load system. Simulations and experimental results show the effectiveness of the control approaches. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
77. An Effective Sliding Mode Control Design for a Grid-Connected PUC7 Multilevel Inverter.
- Author
-
Makhamreh, Hamza, Trabelsi, Mohamed, Kukrer, Osman, and Abu-Rub, Haitham
- Subjects
SLIDING mode control ,ELECTRIC inverters ,COST functions ,PULSE width modulation transformers ,ONLINE algorithms ,SAMPLING errors - Abstract
This paper proposes an effective sliding mode controller (SMC) for a grid-connected 7-level packed U-cell (PUC7) inverter. The aim is to design a simple controller that deals effectively with the complex control problem of the PUC7 inverter (multiobjective control problem). The selection of the control actions is achieved according to the system state error at every sampling time, regardless of the previous values, which makes the control technique model-independent. The control algorithm evaluates online two cost functions (one for each state error), which are derived on the basis of sliding mode theory, and it selects the optimal control input in order to satisfy the reaching conditions of the two cost functions. Compared with the existing solutions, the proposed SMC technique ensures lower average switching frequency by tuning the hysteresis bandwidth of the capacitor-voltage error. The fast implementation, needless of gains tuning, and simple design procedure are the main features of the proposed algorithm. Simulation and experimental results are presented to prove the effectiveness of the proposed technique in controlling the PUC7 inverter with high dynamic performance and robustness against disturbances and parameters mismatch. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
78. Disturbance Injection Based Decentralized Identification of Accidental Islanding.
- Author
-
Murugesan, Suman and Murali, Venkatakirthiga
- Subjects
QUALITY factor ,DYNAMIC loads ,PHASE-locked loops - Abstract
Unplanned islanding is intended to be identified due to the adverse effects on personnel and electrical equipment. In this paper, an active islanding identification technique is proposed based on disturbance injection through q-axis controller and an investigation technique, which incorporates measurement of mean of absolute frequency variation of the voltage signal passed through band-pass filter. The proposed technique is proven to be robust, offering decentralized islanding identification and being applicable to dynamic loading scenario, identifies island formation with zero nondetection zone for all the loads of quality factor $ (Q_{f}) \leq$ 2.5, and does not destabilize the system on postislanding. The islanding identification time is $ < $ 180 ms for all the loads of $ Q_{f} \leq$ 2.5, which is applicable to various international standards. The MATLAB2017b/Simulink platform is utilized to validate the efficacy of the proposed methodology. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
79. Design and Implementation of New Multilevel Inverter Topology for Trinary Sequence Using Unipolar Pulsewidth Modulation.
- Author
-
Prabaharan, Natarajan, Salam, Zainal, Cecati, Carlo, and Palanisamy, Kaliannan
- Subjects
PULSE width modulation - Abstract
This paper proposes a new multilevel inverter (MLI) topology that utilizes trinary sequence for the dc sources. It gives maximum output voltage level with minimum dc source and switch count when compared to other sequences, such as symmetric, natural, binary, and quasi-linear. This is due to the fact that the trinary sequence generates of all additive and subtractive combinations of input dc levels in the output voltage waveform. The concept is implemented on a 9-level asymmetric MLI using only four active devices. Multicarrier unipolar pulsewidth modulation technique is adopted to create the switching pulses. Theoretical calculation of total harmonic distortion in both voltage and current waveforms has been performed using asymptotic time domain formula. These values are compared with simulation and experimental values for different modulation indices. Power loss calculation for proposed topology is discussed with appropriate mathematical equations. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
80. An Improved Rotating Restart Method for a Sensorless Permanent Magnet Synchronous Motor Drive System Using Repetitive Zero Voltage Vectors.
- Author
-
Seo, Dong-Woo, Bak, Yeongsu, and Lee, Kyo-Beum
- Subjects
PERMANENT magnet motors ,ELECTRIC potential ,SHORT-circuit currents - Abstract
This paper presents an improved rotating restart method for a sensorless permanent magnet synchronous motor (PMSM) drive system using repetitive zero voltage vectors. To restart the sensorless PMSM drive system, a method for estimating initial rotor position and speed is required due to the absence of sensors such as encoders and resolvers. The rotor position and speed can be estimated using the short-circuit current vectors generated by applying zero voltage vectors. However, the estimated rotor position and speed can be inaccurate. The inaccurate rotor position that causes the current is distorted by the back-electromotive force of the PMSM, and it is impossible to precisely control the system. Therefore, an improved rotating restart method for the sensorless PMSM drive system using repetitive zero voltage vectors is proposed. The effectiveness of the proposed method is verified through simulation and experimental results using a 5-kW PMSM drive system. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
81. A Robust Field-Weakening Approach for Direct Torque and Flux Controlled Reluctance Synchronous Motors With Extended Constant Power Speed Region.
- Author
-
Zhang, Xinan, Foo, Gilbert Hock Beng, and Rahman, Muhammed Faz
- Subjects
RELUCTANCE motors ,SYNCHRONOUS electric motors ,TORQUE control ,TORQUE ,HIGHER order transitions ,SPEED ,STATORS - Abstract
This paper proposes a new robust field-weakening approach for reluctance synchronous motors regulated by direct torque and flux control. Compared to the existing direct torque and flux control based field-weakening methods that cannot achieve maximized DC-link voltage utilization and are parameter dependent, the proposed approach contributes to improve the field-weakening performance of reluctance synchronous motor in two aspects. First, it extends the constant power speed range through autonomous stator flux reference adjustment, which maximizes the dc-link voltage utilization. Smooth transition between the maximum torque per ampere trajectory and field-weakening trajectory is also realized. Second, it enhances the parameter robustness of drives in very high-speed region by employing a torque reference adjustment scheme. This effectively avoids the instability of drives caused by machine parameter variations. The proposed approach is verified experimentally on a laboratory setup. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
82. Single-Cycle-Lag Compensator-Based Active Damping for Digitally Controlled LCL/LLCL-Type Grid-Connected Inverters.
- Author
-
Miao, Zheyu, Yao, Wenxi, and Lu, Zhengyu
- Subjects
PULSE width modulation ,ELECTRIC inductance ,POSITIVE systems - Abstract
The control delay weakens the active damping (AD) performance of digitally controlled LCL/LLCL-type grid-connected inverters (GCIs). The equivalent virtual impedance paralleled with the filter branch explains the effect of the capacitor-current-feedback AD. However, the virtual impedance appears capacitive or even negative due to the delay, which significantly weakens the effectiveness of AD. This paper proposes a single-cycle-lag compensator (SCLC) to eliminate the adverse effects caused by the control delay. The method retains effectiveness in applications with high resonant frequency or large control delay. It keeps system a positive equivalent resistance with a high equivalent inductance. The positive equivalent resistance leads to positive damping effect, while the high equivalent inductance causing little resonant frequency deviation can be neglected. Moreover, the effect of the impedance variation that causes the resonant frequency deviation is analyzed and the restrictions of the proposed method are discussed. By optimizing the LCL/LLCL filter parameters, the adaptability of the SCLC to the grid impedance variation can be further improved. With the SCLC, the LCL/LLCL-type GCIs achieve better steady-state and dynamic performances. Finally, experimental results are presented to verify the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
83. Determination of Stray Inductance of Low-Inductive Laminated Planar Multiport Busbars Using Vector Synthesis Method.
- Author
-
Lu, Binxian, Pickert, Volker, Hu, Junzhu, Wu, Haimeng, Naayagi, R. T., Kang, Wei, and Liao, Sizhuo
- Subjects
ELECTRIC inductance ,BUS conductors (Electricity) ,CAPACITOR switching ,POWER capacitors ,HARBOR management ,ELECTROMAGNETIC interference - Abstract
Laminated busbars connect capacitors with switching power modules, and they are designed to have low stray inductance to minimize electromagnetic interference. Attempts to accurately measure the stray inductance of these busbars have not been successful. The challenge lies with the capacitors, as they excite the busbar producing their individual stray inductances. These individual stray inductances cannot be arithmetically averaged to establish the total stray inductance that applies when all the capacitors excite the busbar at the same time. It is also not possible to measure the stray inductance by simultaneous excitation of each capacitor port using impedance analyzers. This paper presents a solution to the above dilemma. A vector synthesis method is proposed, whereby the individual stray inductance from each capacitor port is measured using an impedance analyzer. Each stray inductance is then mapped into an xyz frame with a distinct direction. This mapping exercise allows the data to be vectored. The total stray inductance is then the sum of all the vectors. The effectiveness of the proposed method is demonstrated on a busbar designed for H-bridge inverters by comparing the simulation and practical results. The absolute error of the total stray inductance between the simulation and the proposed method is 0.48 nH. The proposed method improves the accuracy by 14.9% compared to the conventional technique in measuring stray inductances. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
84. A Novel Virtual Space Vector Modulation With Reduced Common-Mode Voltage and Eliminated Neutral Point Voltage Oscillation for Neutral Point Clamped Three-Level Inverter.
- Author
-
Jiang, Weidong, Wang, Peidong, Ma, Mingna, Wang, Jinping, Li, Jinsong, Li, Laibao, and Chen, Kewei
- Subjects
PULSE width modulation transformers ,VECTOR spaces ,ELECTRIC potential ,VOLTAGE control ,OSCILLATIONS ,PULSE width modulation - Abstract
This paper briefly reviews the common-mode voltage (CMV) and neutral point (NP) voltage for neutral point clamped three-level inverter (NPC TLI). Then, the space vector pulsewidth modulation (SVPWM) and traditional virtual SVPWM (VSVPWM) are discussed in terms of these two issues, revealing the drawbacks in reducing CMV or eliminating NP voltage oscillation. A novel virtual space vector modulation, named as RCMV_VSVPWM, is proposed in this paper to reduce CMV and eliminate NP voltage oscillation for NPC TLI. By selecting vectors with lower CMVs, a set of novel virtual voltage vectors are generated. The highlight of the method is zero average NP current in one control cycle and lower CMV. Furthermore, the active NP voltage control suitable for RCMV_VSVPWM is presented and evaluated. The corresponding experimental results are given, which are well-consistent with theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
85. Inverter Side RL Filter Precise Design for Motor Overvoltage Mitigation in SiC-Based Drives.
- Author
-
Ruffo, Riccardo, Guglielmi, Paolo, and Armando, Eric
- Subjects
OVERVOLTAGE ,ELECTRIC inverters ,ELECTRIC machinery ,POWER semiconductor switches ,FILTERS & filtration ,ELECTRIC machines ,VARIABLE speed drives - Abstract
This paper investigates the use of resistor–inductor (RL) filters for motor overvoltage issues caused by cables connecting inverters to electric machines. Using existing filter design formulae and fixing the desired peak motor voltage, an RL filter is designed for a 15-kW industrial drive. This filter is used with a Silicon IGBT inverter and a matching between the design targets and the experimental results are found. Using the same filter with an SiC MOSFET inverter, a detrimental effect in overvoltage mitigation task is found. From simulations, it is noticed that combination of filter resistor parasitic inductance and high $dv/dt$ causes unpredicted additional high-frequency motor overvoltages. These phenomena require higher filter inductance values with respect to the standard one, thus previous filter design formulae cannot be used. New design formulae, valid when inverters with high $dv/dt$ are used, are proposed and experimentally validated. Interestingly, using the proposed formulae, it is discovered that the best filter resistance is not equal to the characteristic impedance of the cable. A design guideline that permits to optimally design the RL filter without simulation tool, considering the resistor parasitic inductance and the inverter $dv/dt$ is finally proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
86. A 5-Level Inverter Scheme Using Single DC Link With Reduced Number of Floating Capacitors and Switches for Open-End IM Drives.
- Author
-
Majumder, Mriganka Ghosh, Yadav, Apurv Kumar, Gopakumar, K., R, Krishna Raj, Loganathan, Umanand, and Franquelo, Leopoldo Garcia
- Subjects
CAPACITOR switching ,POWER semiconductor switches ,ELECTRIC current rectifiers ,PULSE width modulation transformers ,POWER capacitors ,INDUCTION machinery ,CAPACITORS - Abstract
This paper presents a 5-level inverter topology for open-end induction motor drives by using a single dc source. The open stator windings of the drive are supplied with a 3-level flying capacitor inverter from one end and capacitor-fed 2-level inverter from another end. The voltage ratio of the dc link to the capacitor in 2-level inverter is maintained at 4:1 ratio to generate five-level voltage output. The capacitor in 2-level inverter is balanced by the switching redundant vector combinations from both the inverters while the floating capacitors in the 3-level inverter are balanced by using redundant switching states. The proposed topology gives 5-level operation with less number of floating capacitors and power semiconductor switches compared to other existing topologies. Also, the balancing of the capacitors is independent of load power factor and modulation index. Further, the generalization of the proposed dual inverter scheme for any n-level inverter is also included in this paper. The experimental results and required analysis are also presented to validate the inverter scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
87. LQR Control of Single-Phase Grid-Tied PUC5 Inverter With LCL Filter.
- Author
-
Arab, Naima, Vahedi, Hani, and Al-Haddad, Kamal
- Subjects
PULSE width modulation transformers ,HARMONIC distortion (Physics) ,RENEWABLE energy sources ,VOLTAGE control ,FILTERS & filtration - Abstract
This paper presents the current control design procedure of a single-phase grid-tied five-level packed U-cell inverter (PUC5) with an LCL output filter. The PUC5 inverter is used as an interface of renewable energy sources, such as solar applications. The LCL filter is calculated according to the grid-tied operation and converter ratings. An optimal controller, based on a linear quadratic regulator with integral action, is designed to inject a sinusoidal current with low harmonic distortion at unity power factor. For that design, the PUC5 inverter is modelled in the D–Q frame. The sensorless voltage control is incorporated into the switching technique to balance the PUC5 capacitor voltage and generate a five-level waveform at the output. Experimental tests are performed on a laboratory benchmark to confirm the theoretical design. The results prove the efficiency and accuracy of the adopted control strategy in a steady state and under transients of grid current, grid inductance, ac and dc voltage amplitudes. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
88. A Constant-Current Transmission Converter for Semi-airborne Transient Electromagnetic Surveying.
- Author
-
Geng, Zhi, Liu, Lihua, Li, Jutao, Liu, Fubo, Zhang, Qimao, Liu, Xiaojun, and Fang, Guangyou
- Subjects
ELECTRIC transients ,ELECTRIC network topology ,SIGNAL-to-noise ratio ,ADAPTIVE control systems ,SURVEYING (Engineering) ,TRANSMITTERS (Communication) ,TRANSIENT analysis - Abstract
In complex terrain, semi-airborne transient electromagnetic surveying can effectively solve the detailed exploration problems to replace ground manual operation. This method has the advantages of high efficiency, deep exploration depth, and high signal-to-noise ratio. As the core component of the system, the constant-current transmission converter determines the primary field source of the surveying system. High-accurate and stable-output electromagnetic transmission technology is the key issues of the surveying equipment development. In this paper, the converter circuit topology is designed in detail and a novel model reference adaptive proportional-integral control algorithm is put forward. The rising overshoot of current is eliminated and falling edge is linear. Finally, the 20-kW high-power transmitting instrument has been completed and used for field experiments. A large number of experimental results show that the transmitting instrument can achieve high-power constant-current emission, stable output, and good dynamic performance. And the steady-state accuracy is better than the traditional transmitter. The converter successfully improved the semi-airborne transient electromagnetic system detection capability and achieved satisfactory results in field experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
89. A Family of Low-Spike High-Efficiency Y-Source Inverters.
- Author
-
Liu, Hongpeng, Li, Yuhao, Zhou, Zichao, Wang, Wei, and Xu, Dianguo
- Subjects
FAMILIES ,ELECTRIC potential ,CAPACITORS ,LEAKAGE ,DIODES - Abstract
In this paper, many impedance-source inverters with coupled inductors have been investigated to obtain a high step-up boost ratio. However, the leakage inductors in these topologies induce great voltage spikes at the dc link, which will increase the voltage stress of switches. Thus, the power level of inverters is limited. Furthermore, the efficiency of the inverters can be degraded by the losses associated with leakage inductors. To address abovementioned issues, this paper proposes a family of low-spike high-efficiency Y-source inverters. The proposed inverters have the ability of eliminating voltage spikes at the dc link and recycling the leakage energy via the additional diode and capacitor. In order to show the excellent characteristics of the proposed topologies, this paper compares the performances of the proposed inverters and the improved-Y-source inverter in many aspects. Simulation and experimental results have verified the abilities of the proposed inverters. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
90. Sensorless Low Switching Frequency Explicit Model Predictive Control of Induction Machines Fed by Neutral Point Clamped Inverter.
- Author
-
Jofre, Matias, Llor, Ana M., and Silva, Cesar A.
- Subjects
TORQUE control ,PREDICTION models ,VARIABLE speed drives ,INDUCTION machinery ,MACHINING ,PULSE width modulation - Abstract
This paper proposes an explicit predictive current control scheme implemented with a low carrier frequency pulsewidth modulation (PWM) on an induction machine fed by a three-level neutral point clamped inverter. The PWM carrier and the main current sampling frequency are both set to 1 kHz, resulting in a 500 Hz average switching frequency per device, which is very suitable for large drive applications. The explicit predictive control is introduced to optimize the available bandwidth provided by such a low sampling frequency, maximizing the dynamic performance. The strategy has been tested in a 2.2-kW induction motor experimental prototype. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
91. An Intelligent Time-Adaptive Data-Driven Method for Sensor Fault Diagnosis in Induction Motor Drive System.
- Author
-
Gou, Bin, Xu, Yan, Xia, Yang, Wilson, Gary, and Liu, Shuyong
- Subjects
FAULT diagnosis ,INDUCTION machinery ,MOTOR drives (Electric motors) ,INDUCTION motors ,FAULT location (Engineering) ,DETECTORS ,MACHINE learning - Abstract
Three-phase pulsewidth modulation inverter fed induction motor drive system is widely applied in high power drive applications. Sensor faults are very common in the drive system, which, once occur, might result in degraded system performance or even system shutdown. In order to rapidly and accurately diagnose the sensor faults, this paper proposes an intelligent time-adaptive data-driven method to identify the fault location and fault type of sensors in the drive system. An emerging machine learning technology named extreme learning machine (ELM) is applied to learn the sensor fault dataset; an ensemble ELM classifier is then designed to improve diagnostic accuracy, based on which a time-adaptive fault diagnosis process is proposed to achieve a high and balanced diagnostic accuracy and speed. As a data-driven method, the proposed method only employs the phase current, dc-link voltage, and speed signals as the inputs to the ensemble ELM classifiers and requires no additional sensors and other hardware. Simulated and experimental tests show that the proposed method can rapidly and accurately detect the fault sensor location and identify offset fault, stuck fault, and noise faults with an average diagnostic accuracy of 98% and the average decision time of 10 ms after the fault occurs. Moreover, such diagnosis method is robust to the fluctuation of catenary voltage and dc-link voltage, fault severity, and variation of model parameters, speed, and load. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
92. Second Harmonic Current Reduction for a Battery-Driven Grid Interface With Three-Phase Dual Active Bridge DC–DC Converter.
- Author
-
Wang, Deqiang, Nahid-Mobarakeh, Babak, and Emadi, Ali
- Subjects
BATTERY storage plants ,MARINE terminals ,CASCADE converters ,BUILDING performance - Abstract
Two-stage isolated battery-driven grid interface (IBDGI) with front-end three-phase dual active bridge (DAB) dc–dc converter is promising to be applied in the residential battery energy storage system for supporting photovoltaic (PV) integration, load shifting, and backup power purposes. However, the second harmonic current (SHC) caused by the pulsating power of the downstream single-phase inverter will increase the battery's degradation and the component stress of the front-end converter. In this paper, a reduction method is proposed for the IBDGI with three-phase DAB converter using a load current feedforward control. The proposed idea is to incorporate virtual impedance to the output impedance of the front-end converter. The easy-to-be-implemented method does not need to modify the original voltage closed-loop controller but suppress SHC while keeping good dynamic performance. As the first step, the small-signal model of the three-phase DAB converter is provided. The parameter sensitivity analysis is proposed to demonstrate that the SHC can be well-suppressed within $\pm \text{20}\%$ parameter error of the feedforward control. Finally, a 1 kW experiment setup is built to verify the performance of the proposed SHC reduction method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
93. Lyapunov-Based Model Predictive Control of a PUC7 Grid-Connected Multilevel Inverter.
- Author
-
Makhamreh, Hamza, Kukrer, Osman, Sleiman, Mohammad, and Al-Haddad, Kamal
- Subjects
LYAPUNOV functions ,ELECTRIC controllers ,ELECTRIC inverters ,COEFFICIENTS (Statistics) ,SIMULATION methods & models - Abstract
In this paper, a new Lyapunov-based model predictive controller is proposed for a 7-level packed U-cell (PUC7) grid-connected inverter. A cost function of the proposed model predictive controller is designed from the system stability point of view, inspired by the Lyapunov control theory. The proposed controller eliminates the need for gains that are associated with cost function coefficients, as seen in classical model predictive control based controllers. Therefore, the control design problem is significantly simplified. In addition, the average switching frequency is also reduced, as shown in both simulation and experimental results, leading to a reduction in switching losses. Simulation and experimental tests, on a PUC7 lab prototype, demonstrate the excellent performance of the proposed control system, in terms of high disturbance rejection, robustness to parameter mismatches, and fast dynamic response. Such features qualify the proposed control strategy as a good candidate for grid-tied applications. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
94. Analysis of the Medium-Frequency Oscillation Issue in a Medium-Voltage High-Power Wind Energy Conversion System.
- Author
-
Zhang, Yonglei, Yuan, Xibo, and Wu, Xiaojie
- Subjects
WIND turbines ,ELECTRIC potential ,POWER density ,ELECTRIC transformers ,ELECTRIC inverters - Abstract
One promising solution for future large wind turbine power conversion is to use medium-voltage power conversion systems for high efficiency and high power-density, e.g., by using a cascaded structure presented in this paper. However, a medium-frequency (MF) oscillation issue was observed while testing the experimental prototype of the above system. Given the complex multivariable coupling models of the multiwinding transformer and multiple inverters, conventional single-variable theories are not suitable. Therefore, this paper presents a new decoupling analysis method. Using a proposed linear transformation matrix, the output currents of multiple inverters can be transformed to a summation (grid) current and difference currents, where the former is the summation of inverter currents and the latter are the differences between currents of any two inverters. This transformation has enabled the use of single-variable theories, e.g., Bode diagram to analyze the summation current and difference current separately. It was found that the MF oscillation issue is caused by the equivalent impedance of the summation current being much larger than that of the difference current. Specifically, using small controller parameters cannot ensure the grid current quality and using large parameters may cause oscillation in the difference current. The proposed method can provide guidelines to design the parameters of current regulators and filters in multiple-inverter systems. Experimental results of a downscaled wind energy conversion system are presented to verify the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
95. Emerging Power Quality Problems and State-of-the-Art Solutions.
- Author
-
Khadkikar, Vinod, Xu, Dianguo, and Cecati, Carlo
- Subjects
RENEWABLE energy sources ,ELECTRIC potential measurement ,SMART power grids - Abstract
The papers in this special section are devoted to the topic of solutions for power quality management. Although the power quality problems, such as, reactive and harmonic currents, distortion and fluctuations in the supply voltage, are not new to power system and power electronics researchers, the ever changing landscapes in the power generation and distribution systems have given rise to additional power quality challenges. The growing interest in the smart grid concepts, vehicle to grid operation, inverter based large scale photovoltaic (PV) and wind integration, distributed generators (DGs) as ancillary service provider, multilevel inverters for high power applications and so on is making the power quality aspects more prevalent. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
96. Effect of the Power Cable on Data Transmission Over a Pulsewidth-Modulated Network.
- Author
-
Mannah, Marc Anthony, Ginot, Nicolas, and Batard, Christophe
- Subjects
CARRIER transmission on electric lines ,DATA transmission systems ,ELECTRIC inverters ,PULSE width modulation ,POWER transmission ,ELECTRIC cables - Abstract
Power line communication (PLC) technology has proved itself in the last decade as an interesting solution for data transmission and communication in domestic application. Lately, this technology has been considered as a potential solution for monitoring and diagnosis of a motor-fed inverter setup. Information issued from sensors would be sent via power cables back to the controller despite the harsh environment and the switching of the inverter. This paper discusses the use of PLC technology over a pulsewidth modulation network by underlining the effect of the power cable length and the inverter switching on communication. A new approach based on the measurement of scattering parameters is used for this purpose, and the effect of the cable length is analyzed. It is shown that, for long distances, the PLC technology may not be effective, and hence, it is not possible to use power cables for communication. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
97. A Comparative Study of Synchronous Current Control Schemes Based on FCS-MPC and PI-PWM for a Two-Motor Three-Phase Drive.
- Author
-
Lim, Chee-Shen, Levi, Emil, Jones, Martin, Rahim, Nasrudin Abd., and Hew, Wooi-Ping
- Subjects
MOTOR drives (Electric motors) ,ELECTRIC inverters ,PULSE width modulation ,VOLTAGE control ,ELECTRONIC control ,PREDICTIVE control systems ,VECTOR control - Abstract
A two-motor drive, supplied by a five-leg inverter, is considered in this paper. The independent control of machines with full dc-bus voltage utilization is typically achieved using an existing pulsewidth modulation (PWM) technique in conjunction with field-oriented control, based on PI current control. However, model predictive control (MPC), based on a finite number of control inputs [finite-control-set MPC (FCS-MPC)], does not utilize a pulsewidth modulator. This paper introduces three FCS-MPC schemes for synchronous current control in this drive system. The first scheme uses all of the available switching states. The second and third schemes are aimed at reducing the computational burden and utilize a reduced set of voltage vectors and a duty ratio partitioning principle, respectively. Steady-state and transient performances are analyzed and compared both against each other and with respect to the field-oriented control based on PI controllers and PWM. All analyses are experimental and use the same experimental rig and test conditions. Comparison of the predictive schemes leads to the conclusion that the first two schemes have the fastest transient response. The third scheme has a much smaller current ripple while achieving perfect control decoupling between the machines and is of low computational complexity. Nevertheless, at approximately the same switching loss, the PI-PWM control yields the lowest current ripple but with slower electrical transient response. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
98. Synchronverters With Better Stability Due to Virtual Inductors, Virtual Capacitors, and Anti-Windup.
- Author
-
Natarajan, Vivek and Weiss, George
- Subjects
ELECTRIC inverter design & construction ,SYNCHRONOUS electric machinery ,ELECTRIC power system stability ,ELECTRIC current regulators ,CAPACITORS - Abstract
Synchronverters are inverters that mimic the behavior of synchronous generators. In this paper, we propose five modifications to the synchronverter algorithm from the paper “Synchronverters: Inverters that mimic synchronous generators,” (IEEE Trans. Ind. Electron., vol. 58, no. 4, pp. 1259–1267, Apr. 2011), to improve its stability and performance. These modifications are implemented in software and do not require any changes in the inverter hardware. The first two modifications concern the control of the virtual field current in the synchronverter so that it is more robust to faults. We prove the stability of the grid-connected synchronverter with this improved field current controller. The third modification is to increase the effective size of the filter inductors virtually. This is motivated using results from the stability analysis of a constant field current synchronous generator connected to an ac power grid and also by practical considerations. Simulations and experiments show that this leads to a much better response to changes in grid frequency, voltage, or to imbalance in the grid. The fourth modification is to change the formula for the (virtual) nominal active mechanical torque to take into account the (virtual) losses in the output impedance of the converter. This makes the tracking of the desired active power much more accurate. The fifth modification is to introduce virtual capacitors in series with the inverter outputs to filter spurious dc components from the current supplied to the grid. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
99. An Improved DTC Technique for Low-Speed Operation of a Five-Phase Induction Motor.
- Author
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Payami, Saifullah and Behera, Ranjan Kumar
- Subjects
TORQUE control ,INDUCTION motors ,ELECTRIC switchgear ,STATORS ,ELECTRIC inverters ,HYSTERESIS - Abstract
In this paper, an improved direct torque control (DTC) technique of a two-level inverter-fed five-phase induction motor (FPIM) drive for low-speed operation is presented. The operation of the FPIM with distributed winding requires the elimination of third-harmonic voltage, which, if not taken care of, would generate distorted stator current. For this, the concept of virtual vectors (VVs) is utilized. Before selecting the VVs for the DTC operation, a theoretical analysis is carried out to find the effects of these VVs on the torque and flux response of the FPIM under different speed and loading conditions. It is found that the rotor speed plays a crucial role in the selection of VVs. A particular VV has different effects on the torque change as speed varies. This analysis helps in the selection of VVs, hysteresis torque bandwidth, flux bandwidth, and efficient formation of sectors. Furthermore, in this paper, the performance of the FPIM during low-speed operation is improved by avoiding the demagnetization of the stator flux. To achieve this, a new modified lookup table is proposed. Superiority of the proposed method over the reported approaches is illustrated by experimental results. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
100. Control of a Grid-Forming Inverter Based on Sliding-Mode and Mixed H_2/H_\infty Control.
- Author
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Li, Zhongwen, Zang, Chuanzhi, Zeng, Peng, Yu, Haibin, Li, Shuhui, and Bian, Jing
- Subjects
ELECTRIC inverters ,MICROGRIDS ,VOLTAGE control ,SLIDING mode control ,HARMONIC distortion (Physics) - Abstract
A grid-forming inverter (GFI) is an important component for the operation of an islanded microgrid. Its purpose, similar to a conventional slack bus generator, is to build up a reference voltage for other distributed generating units in the microgrid. Usually, a nested-loop proportional plus integral (PI) control structure is employed to control a GFI in a dq reference frame. However, conventional PI-based nested-loop control method has a deteriorative performance under parameter variations. In this paper, a novel nested-loop control strategy is proposed for control of a GFI system containing an {LC} output filter and loads. The proposed method does not require a precise model for the inverter system and can better deal with uncertainties and {LC}$ filter resonance without using any passive or active damping mechanisms. It utilizes a sliding-mode control in the inner current loop and a mixed {H_2}/{H_\infty } optimal control in the outer voltage loop, which provides the advantages of constant switching frequency, low total harmonic distortion, robustness against parameters variations, and fast transient response. The simulation and hardware experiments presented in this paper demonstrate the proposed controller's improved transient and steady-state performance in various key criteria, over conventional PI-based nested-loop control strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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