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The conventional DC-link type quasi-Z-source inverter has been known as a buck–boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the voltage gain of the inverter. As a result, the component voltage rating of the inverter is significantly reduced, which is demonstrated through some comparisons between the proposed topology and others. A discontinuous pulse width modulation (DPWM) scheme is proposed to control the inverter, which reduces the number of commutations compared to the traditional strategy. Under this approach, the insertion of a shoot-through state does not cause any extra commutations compared to the conventional voltage-source inverter. Details about control implementation, steady-state analysis, and design guidelines are also presented in this paper. Simulation and a laboratory prototype have been built to test the proposed inverter. Both buck and boost operations of the proposed inverter are implemented to validate the performance of the inverter. [ABSTRACT FROM AUTHOR]

Electric vehicles are regarded as a significant way to mitigate the global energy crisis and the environmental pollution problem. Motor control is a very important part for electric vehicles. As for hardware, a motor controller usually has components such as a power module, microprocessor unit, IGBT driver, sensors, and resolver-to-digital convertor. As for software, a field-oriented control (FOC) with space vector pulse width modulation (SVPWM) is a popular method, while model predictive control (MPC) has recently shown great potential in motor drives. In this paper, both FOC and MPC are discussed and the performances are compared based on experiments. As the implementation is on a digital processor, the discretization and normalization are addressed, and the flux observer and speed estimation are discussed. Some practical issues for implementation are also talked about, such as field weakening control, overmodulation, etc. This paper focuses on how to implement the improved motor control for electric vehicles as industrial applications. The steady-state torque performances of this motor controller are verified by motor test-bench experiments. MPC shows as good performance as FOC in these experiments. [ABSTRACT FROM AUTHOR]

A full-bridge diode-clamped multilevel LLC resonant converter suitable for power conversion systems that use high input voltage, such as railway vehicles, is proposed in this paper. In order to eliminate the voltage deviations of the capacitors connected in series to the high voltage input DC link, a novel modulation strategy referred to as multi-neighboring reference vector discontinuous pulse-width modulation (MNRV DPWM) is proposed. Unlike the existing two-level resonant converter that varies the operating frequency to hold the output voltage constant, the proposed multilevel resonant converter modulates the amplitude of the fundamental wave input to a resonance tank while fixing the operating frequency at the resonance point. Therefore, the design of passive elements becomes easier, and stable operation is possible over a wide operating range with only one power conversion stage. In this paper, the control algorithm and operation characteristics of the newly proposed full-bridge diode-clamped four-level LLC resonant converter are analyzed in detail and design guidelines are presented. The feasibility of the proposed converter is verified through a simulation and an experiment with a prototype converter. [ABSTRACT FROM AUTHOR]

In this paper, we introduce analog nonvolatile random access memory cells for neuromorphic computing. The analog memory cell MoS 2 channel is designed based on the simulation model including Fowler–Nordheim tunneling through a charge-trapping stack, trapping process, and transfer characteristics to describe a full write/read circle. 2D channel materials provide scaling to higher densities as well as preeminent modulation of the conductance by the accumulated space charge from the oxide trapping layer. In this paper, the main parameters affecting the distribution of memory states and their total number are considered. The dependence of memory state distribution on channel doping concentration and the number of layers is given. In addition, how the nonlinearity of memory state distribution can be overcome by variation of operating conditions and by applying pulse width modulation to the bottom gate voltage is also shown. [ABSTRACT FROM AUTHOR]

This paper discusses the dynamic interaction of multi active power filters (APFs) paralleled with a weak power grid. In order to analyze the dynamic interaction from multi APFs, the output impedance of an APF is solved. The influences of both circuit and control parameters on the output impedance are analyzed. Based on the output impedance of an APF, the dynamic influences of an APF on the other APF connected to the weak grid are discussed. As shown in this paper, the stability of an APF is improved with an increased output filter inductance and some control parameters to reduce its bandwidth. The proposed analysis methods can be used not only for multi APFs but also for the other multi-inverters connected to a weak grid. Experimental tests are carried out using two paralleled three-phase 10-kVA inverters to confirm the validity of the theoretical analysis. [ABSTRACT FROM PUBLISHER]

In recent years, a Multilevel Inverter (MLI) topology is highly preferred in the various renewable energy applications for converting power due to their merits. In this paper, a three-phase inverter has been designed for grid-connected applications using Proportional Integral (PI) current controller scheme. To generate a sequence, the Level shift (LS) and Phase Shift (PS) Pulse Width Modulation (PWM) methodologies are adapted. This topology has been designed with two stages: the DC-DC conversion stage and DC-AC conversion stage. The DC-DC conversion stage is used to enrich input DC voltage which is obtained from the solar PV array. The PI current controller has been designed to regulate the grid current with park transformation. The performances of the inverter have been examined in terms of Total Harmonic Distortion (THD) using different PWM techniques and also investigated with existing research works. The developed results are verified using MATLAB/ Simulink. [ABSTRACT FROM AUTHOR]

The randomized pulse width modulation techniques are used to reduce electromagnetic interference in power converters by spreading the harmonic energy. Thus, a wider spectrum with lower amplitudes is obtained. Based on the pulse width modulation signal parameters, three main randomized techniques are achieved: the random carrier frequency modulation, the random pulse width modulation and the random pulse position modulation. This paper presents a short review of the different implementation methods. Then, a detailed implementation of the three considered random techniques using Atmega328p microcontroller is detailed. Finally, an analysis of the experimental conducted electromagnetic noise taken from a boost converter is discussed. These results prove that the random carrier frequency modulation approach is completely better than other techniques in terms of electromagnetic noise reduction. [ABSTRACT FROM AUTHOR]

The focus of this paper is the control of a reusable launch vehicle at exoatmospheric flight conditions, in the presence of actuator effectiveness uncertainty. Since during exoatmospheric flight, dynamic pressure is nonexistent, aerodynamic control surfaces cannot be used. Under these conditions, reaction control jet actuators can provide the necessary thrust to control the vehicle. Reaction control jets have only 2 states, namely, on and off, and continuous control inputs can be implemented with the help of pulse width modulation, which is also employed in this paper. A continuous controller is designed in the outer loop and a control allocator is used to distribute the total control input among redundant actuators, whose effectiveness are assumed to be unknown. The unknown actuator effectiveness is addressed with the help of an adaptive control allocator. A representative model of a reusable launch vehicle equipped with reaction control jets is used to demonstrate the effectiveness of the overall control scheme. [ABSTRACT FROM AUTHOR]

This paper proposes a WECS based on a back to back diode-clamped multilevel inverter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. DFIG performance is compared using these technologies for different wind speed under normal operation condition. The proposed approach shows that the DCMLI systems generate a nearly sinusoidal voltage with reduced total harmonic distortion (THD) thus upgrading the power quality of that produced by DFIG. As SPWM and THIPWM MLI are most common usage techniques in research, we applied them in the system to discuss a comparison of using those techniques to determine the number of levels that achieve the IEEE 519 criteria of THD which is less than 5% for both techniques (5th level for SPWM and 4th level for THIPWM) in all operation wind speed. Compared with simple PWM, and THIPWM have many advantages as lower THD, minimal number of switching to decrease switching losses and the output fundamental voltage is increased. Lastly, the paper investigates the variation of the frequency of induced rotor voltage and the active power flow due to the wind speed change when the rotor speed changes from super-synchronous to sub-synchronous speeds. [ABSTRACT FROM AUTHOR]

The paper deals with the application of fuzzy logic in the current-based model reference adaptive system (CB-MRAS) for sensorless induction motor drives using direct torque control with pulse-width modulation. The stability analysis of the selected observer is described in the first part. Fuzzy logic is used to adjust the parameters of proportional–integral (PI) adaption algorithm of the CB-MRAS observer. The description of a laboratory workplace with an induction motor drive and load system is presented in the third part. Comparisons of conventional PI and fuzzy logic-based adaptation algorithms are shown in the paper. The theoretical assumptions of the sensorless induction motor drive are confirmed by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

The development of wide band-gap semiconductor devices is rapidly promoting the development of power electronics technology, especially in high frequency (HF) power converter region. A category of HF power converter is switch-mode power amplifier (PA). This paper focuses on the implementation of a multiphase dc–dc PA with high bandwidth and high power rate. When naturally sampled phase-shifted carrier modulation is implemented in the practical digital control system to control this HF power converter, the pulsewidth error problem caused by limited domain frequency of control chip becomes much severer. As a result, dc voltage component of each phase becomes different under several conditions, leading to current imbalance among phase inductors. This paper analyzes this problem and proposes a sensorless control method to solve it, based on the injection of random sequence in reference wave. A four-phase prototype employing GaN devices is fabricated, switching at 1 MHz. Current imbalance and effectiveness of the proposed control method are verified by experimental results. The prototype is capable of uniformly amplifying sine signal within 200 kHz and a 350 kHz bandwidth random signal, with peak output power up to 810 W. [ABSTRACT FROM AUTHOR]

This paper improves the position sensorless drive by sensing actual machine phase voltages. A high-bandwidth phase voltage measurement is developed for pulsewidth modulation (PWM) voltage inverters. On the basis, the actual phase voltage is obtained based on the digital integration of PWM voltage using the capture modulator in existing drive microcontrollers (MCU's). Comparing to existing phase voltage measurement, no separated A/D converter and communication hardware are required because PWM pulses are directly measured using MCUs. However, for standard machines without neutral points, only line-to-line ac PWM voltages can be measured for the phase voltage reconstruction. Since the capture based on transistor-transistor logic (TTL) logics receives only digital signals, a preprocess circuit to convert ac PWM line voltages to equivalent digital signals is proposed. This paper clearly explains the voltage sensing hardware using MCU capture modulator. According to experimental results, a 150-MHz sampling rate for phase voltage measurement is achieved based on the proposed capture-based voltage measurement. Although the physical limitation of back electromotive force estimation still appears, the proposed phase voltage measurement substantially enhances the sensorless drive performance at low speed. [ABSTRACT FROM AUTHOR]

Metallic joints are created in multivariable gas metal arc welding process by maintaining a balance between the quantum of heat generated and the feeding rate of electrode metal to the weld gap. The wire feeding control is often independently handled. The wire feeder unit should be simple, low cost, and capable of producing accurate speed. Arc welding controllers are often kept in clumsy conditions and the wire feeder unit is located close to the welder, could be much away from the controller. To reduce interconnections, separate sensing element for speed feedback should be avoided. Due to their negligible electrical and mechanical time constant, the pancake-type permanent magnet dc motor is suitable for wire feeding, where sensing of back electromotive force (EMF) for feedback is easy. When high frequency pulsewidth modulation (PWM) controller is used, the sensing of back EMF gets complicated. This paper explores the constraints on the choice of PWM frequency along with its maximum pulsewidth for different types of dc motors. It further elaborates comparatively on the choice of suitable control function for generating accurate speed control of wire feeding using back EMF as feedback. Finally, this paper also details the experimental results using the proposed control function. [ABSTRACT FROM AUTHOR]

High reliability and fault-tolerant operation capability are the application requirements of electric vehicles(EVs). In case of the drive system suffering from inter-turn short-circuit (ITSC) fault, it is necessary to avoid the aggravation of the fault and ensure the normal output performance, this paper proposed a torque ripple minimization control strategy for ITSC fault based on the open-winding (OW) five phase fault tolerant fractional slot concentrated winding interior permanent magnet (FTFSCW-IPM) motor drive system with common DC bus. Once the ITSC fault is detected, the fault phase is active open-circuit (OC) (null the current of the normal part in the fault phase) and connected to a voltage sensor. In this way, the torque ripple minimization control strategy can deal with the OC fault and ITSC fault. For the OC fault, the equal amplitude phase current modulation strategy is adopted based on the carrier-based pulse width modulation (CPWM). For the ITSC fault, this paper proposed a feedforward compensation approach to eliminate the influence of the short-circuit loop current. The novelty of the proposed method is that the compensation can be real-time estimated using the zero-sequence voltage (ZSV) and zero-sequence current (ZSC), even the ITSC level changes. Simulation and experimental results demonstrate the effectiveness and feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

This paper characterizes the sampling effect in digital sinusoidal pulse width modulation (SPWM) of voltage source inverter (VSI). The time-domain analysis presented in this paper establishes the relation between the fundamental frequency, carrier frequency, and the sampling frequency at different modulation indices of the SPWM. The analysis investigates the effect of sampling frequency of the digital controller on the output of the VSI. It is shown that the low-frequency harmonic components appear in the frequency spectrum of the VSI output voltage due to sampling. As a result, the output current of digitally controlled VSI is stepped in nature. The double Fourier integral solution of the switched waveform for inner and outer integral limits has been used to derive the expression. The integral solution is obtained using Jacobi-Anger expansions. The generalized results developed in this paper are useful to investigate the sampling effect in high switching frequency DSPWM. The proposed sampling effect has been analyzed for SPWM of single-phase H-bridge inverter. The analytical results are verified using simulation and experimental results. The experimental results have been obtained with the use of field-programmable gate array (FPGA) as a digital controller. [ABSTRACT FROM PUBLISHER]

A drive train system (DTS) powered by an ideal voltage source and driving a permanent-magnet synchronous motor (PMSM) is discussed in this paper. A two-level three-phase voltage source inverter is used as a means of power conditioning. This converter is not equipped with any harmonic filters on neither the ac nor the dc side. The mechanical part of the DTS is modeled as a double oscillator according to a drive train in an electric vehicle (EV). Various inverter modulation schemes are applied, namely, a single-phase hysteresis scheme, two-space vector-based hysteresis control schemes, for one, a stator aligned hysteresis and for another, a rotor aligned hysteresis, a modulation scheme based on pulsewidth modulation (PWM), such as sinusoidal modulation (including zero-sequence components) and space-vector pulsewidth modulation (SVPWM). The hysteresis-based pulsing methods are nondeterministic and build a current controller in their structure by nature. The other pulsing methods are deterministic due to their underlying PWM and require a separate control unit. The influence of these modulation schemes on the performance of the DTS is determined by assessing the level of inverter generated harmonics flowing to the PMSM and to the tires [downforce, (mechanical part)] as well as the resulting switching frequency (electrical part). The simulated results presented in the paper indicate that the pulsing frequency can be reduced by means of the hysteresis controller. In addition, the dispersion of the harmonic energy of the inverter generated spectrum partly compensate the absence of filters. [ABSTRACT FROM PUBLISHER]

This paper investigates a method to increase fuel economy of motors for an electric vehicle (EV) traction system. The low-torque region of an EV motor is frequently used in everyday urban driving and in fuel economy measurement. Pulsewidth modulation (PWM) carrier harmonic iron loss accounts for a high percentage of total loss for EV motors in this region. This paper reveals the relationship between phase current and carrier harmonic iron loss for a permanent-magnet synchronous motor (PMSM) in the low-torque region. Thus, a novel carrier harmonic loss reduction technique is proposed and applied to two sets of three-phase windings for a concentrated winding PMSM. The loss is successfully reduced in a 70-kW EV motor as well as a two-dimensional finite-element method (2-D-FEM) calculation. The efficiency of the developed motor is calculated and compared with that of a conventional motor in the JC08 mode driving cycle. [ABSTRACT FROM PUBLISHER]

This paper presents an improved dc-link voltage balancing algorithm for a three-level neutral-point-clamped inverter by considering phase current direction. Detailed studies on the effects of change in load current direction on the dc-link capacitor voltages are presented. A maximum value of power factor is numerically derived, above which it affects the capacitor voltage balancing capability. Compared with the previously presented research work, the inputs to the space-vector pulsewidth-modulation block are the three phase currents and the difference between the two capacitor voltages. Depending on the states of the two dc-link capacitor voltages and phase current direction, redundant voltage vector sequences are selected. The selected vectors keep the capacitor voltage deviations within 5% of the total dc-link voltage. Two zero switching vectors (i.e., PPP and NNN) are also removed from all subsectors of the earlier proposed strategy, which one used to produce higher common-mode voltages. Detailed simulation and experimental results are presented in this paper for a 6.0-kW surface permanent-magnet synchronous machine. Both the simulation and experimental results show the required performance of the proposed system. [ABSTRACT FROM AUTHOR]

This paper proposes a two-degree-of-freedom (2DoF) interleaving scheme based on phase-disposition (PD) PWM for minimizing the high-frequency zero-sequence circulating current (ZSCC) in modular interleaved three-level converters. The method incorporates an internal interleaving by phase-shifting the carriers in each individual converter, and an external interleaving by phase-shifting the carriers of the different converters. A general harmonic distribution analysis which is valid for all types of voltage source converters is carried out to simplify the evaluation of the proposed method. A comprehensive evaluation of the proposed method shows that the PD-2DoF interleaving scheme produces the lowest ZSCC maximum value as compared to existing approaches. Moreover, it can achieve comparable performances as existing methods do in terms of output quality and common mode voltage magnitude, showing a great potential for practical implementation. Simulation and experimental results are obtained to demonstrate the performance of the proposed method. Generalization of the 2DoF interleaving scheme to high-level converter is also discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a new carrier-based modulation strategy for symmetrical cascaded multilevel converters denominated phase disposition with sorting (PDS). It deals with the issue of irregular distribution of PWM signals and power for each converter cell that occurs when using the conventional phase disposition (PD) modulation. Although some alternatives have been proposed in the literature for overcoming these problems, most of them do not consider operation of the converter under fault conditions on the power cells. Therefore, one of the contributions of the proposed PDS modulation strategy is the ability to evenly distribute the pulse signals for the converter semiconductor switches, resulting in the same power being processed by all cells, maintaining the good quality of the synthesized output voltages, even with faults in one or more power cells. In addition, it allows implementation in commercial digital signal processors, not requiring additional hardware. The good performance of the proposed modulation strategy is validated through experimental results for a three-phase symmetrical cascaded multilevel converter with three cells per phase, considering normal and faulty conditions on the power cells. [ABSTRACT FROM AUTHOR]

Unipolar-pulsewidth modulation (UP-PWM) inverter takes advantages of high power efficiency and small output chokes which is widely used in the industry. However, UP-PWM inverters cannot be used in parallel operation due to a current unbalance problem. This paper studies the current unbalance problem of paralleled UP-PWM inverters with common dc bus and ac bus. First, the problem of unbalanced inductor current is defined and analyzed. Second, a technique to eliminate unbalanced currents is proposed. The proposed current balancing technique only requires one more current sensor in an inverter module rather than changing converter topology or modulation method, which makes it possible to apply UP-PWM inverters in parallel-operation while keeping the advantages of unipolar switching. The proposed current balancing method is verified by both simulation and hardware experiment. Experimental verification is performed on two 1 kW, 400 V input, and 120 V/60 Hz output prototypes, which shows a good agreement to the analytical study. [ABSTRACT FROM AUTHOR]

This paper suggests a design of pulsewidth modulation series-resonant converter (PWM SRC) for magnetron power supplies. The goal of this design is to make the PWM SRC have a wide output voltage maintaining mode 3 operation that shows good switching characteristics. To keep the mode 3 operation, a systematic design is required because the design is related to various parameters, such as resonant tank, transformer turns-ratio, magnetizing inductance, and duty-ratio. To establish the design procedure, converter analysis is performed related to the steady-state operation, input–output relationship, and critical design conditions, and several design equations are derived based on the analysis. Based on the design procedure, a PWM SRC with parallel-input-series-output-connected transformer has been designed for magnetron power supplies and verified. [ABSTRACT FROM AUTHOR]

The neutral-point voltage-balancing control is a critical issue of a neutral-point-clamped converter. The conventional control strategy is to inject the specific zero-sequence voltage to regulate the redundant vector, but it is unacceptable to the three-phase four-wire system. This paper provides a neutral-point voltage-balancing control by the dipolar modulation, and the control freedom of the zero-sequence voltage is flexible. Therefore, the proposed method is suitable for both three-phase three-wire and three-phase four-wire systems. Besides, the proposed method improves the control dynamic in a reactive power system. The proposed neutral-point voltage-balancing control is verified by the mathematical analysis and experimental results. The control dynamic, power loss estimation, and the output current performance are analyzed in this paper. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to study the dynamics of a permanent magnet direct current (PMDC) brushed motor while two crucial space-domain effects, namely, slotting effect and commutation phenomenon are taken into account. Semi-analytical dynamic time-domain PMDC brushed motor model inclusive of these space-domain effects is used to analyze and investigate the dynamics. Pulse width modulation operated discontinuous current PMDC brushed motor drive with steady duty cycle is employed to acquire the bifurcation patterns. The chaotic nature due to slotting effect and commutation is identified from the bifurcation patterns and reported. It also has to be admired that such nonlinear dynamical behavior with the same set of parameters at similar operating condition has not been observed when a conventional PMDC brushed motor dynamic model is considered. These space-domain effects, namely, slotting effect and commutation also have a prominent impact to make some time-domain states of a PMDC brushed motor drive chaotic. The role of slotting effect and commutation phenomenon to analyze the chaos over time-domain state variables of the PMDC brushed motor drive is investigated and validated experimentally in this paper. [ABSTRACT FROM PUBLISHER]

Real-time frequency agility is one of the key limitations of current all-digital transmitters (ADTs). In this paper, to address this problem, an ADT based on direct-RF generation is proposed and implemented in a field-programmable gate array (FPGA). To achieve this, the pulse encoding is performed after the digital upconversion, which presents challenges in the pulse encoder implementation. However, the proposed design considerably improves the frequency agility when compared with current state-of-the-art approaches. Two different pulse encoders were designed in this paper, one is based on pulsewidth modulation (PWM) and the other on delta–sigma modulation ( \mathrm \Delta \Sigma \textM ). These units are implemented with high parallelization to achieve the required equivalent sampling rates. The proposed design enables the implementation of all-digital RF transmitters in FPGA with a widely tunable carrier frequency. In this paper, a variation from 0.1 up to 6 GHz of carrier frequency, with a maximum frequency resolution of 1.5625 MHz, is demonstrated. Measurement results in terms of signal-to-noise ratio (SNR) and error-vector magnitude are presented and discussed. In the case of the PWM, maximum SNRs of 39 and 36 dB were obtained for a 5 and 10 MBd of symbol rates (SRs). In the case of \mathrm \Delta \Sigma \textM , maximum SNRs of 38 and 35 dB were obtained for 20 and 40 MBd of the SR. [ABSTRACT FROM PUBLISHER]

The modular multilevel converter (MMC) with nearest level modulation (NLM) is widely used in the high voltage applications for low switching frequency and easy implementation. Existing literature has not provided a complete submodule (SM) fault ride-through scheme for MMC with NLM. In this paper, a strategy including fault detection, localization, redundancy, and recovery is proposed to ensure continuous operation of MMC under IGBT open-circuit faults conditions. It only requires a few hardware and software resources. The features of MMC and SMs with three types of failures are studied, respectively. Based on these, the fault detection method is proposed by using a simple hardware circuit, thus high computation complexity is avoided. Since current fault localization schemes are limited to MMC with carrier phase shifted pulse width modulation, this paper further proposes a strategy for MMC with NLM to locate the faulty SM and identify the fault type. After this, the fault redundancy and the proposed fault recovery method are applied to eliminate the fault and then exit the failure state. Therefore, the ability of SM fault ride-through can be realized. Analysis of failure characteristics are verified in simulation. Experimental results based on a single-phase MMC prototype with 11 SMs per arm are presented to demonstrate the validity of the proposed fault ride-through strategy. [ABSTRACT FROM AUTHOR]

Servomotors have already been around for some decades and they are extremely popular among roboticists due to their simple control technique, reliability and low-cost. They are usually controlled by using Pulse Width Modulation (PWM) and this paper aims to keep the idea of simplicity and low-cost, while introducing a new control technique: Pulse Frequency Modulation (PFM). The objective of this paper is to focus on our development of a low-cost servomotor controller which will allow the research community to use them with PFM. A low-cost commercial servomotor is used as the base system for the development: a small PCB that fits inside the case and allocates all the electronic components to control the motor has been designed to replace the original. The potentiometer is retained as the feedback sensor and a microcontroller is responsible for controlling the position of the motor. The paper compares the performance of a PWM and a PFM controlled servomotor. The comparison shows that the servomotor with our controller achieves a faster mechanism for switching targets and a lower latency. This controller can be used with neuromorphic systems to remove the conversion from events to PWM. [ABSTRACT FROM AUTHOR]

This paper presents a new all-digital transceiver architecture fully integrated into a single field-programmable gate array chip. Both the radio frequency (RF) receiver and the transmitter were entirely implemented using a digital datapath from the baseband up to the RF stage without the use of conventional analog-to-digital converter, digital-to-analog converter, or analog mixer. The transmitter chain uses delta-sigma modulation and digital upconversion to produce a two-level RF output signal. The receiver uses a high-speed comparator and pulsewidth modulation to convert the RF signal into a single-bit data stream, which is digitally filtered and then downconverted. Both the transmitter and the receiver are agile with flexible carrier frequency, bandwidth, and modulation capabilities. The transceiver error vector magnitude and the signal-to-noise ratio figures of merit were analyzed in a point-to-point transmission to evaluate the transmitter’s performance. The results show the feasibility of this approach as a more flexible alternative to common radio architectures. [ABSTRACT FROM PUBLISHER]

The disadvantage of finite control set-model predictive control (FCS-MPC) is that the switching frequency is variable and relies on the sampling time and operating point. This paper describes how to implement a new algorithm to achieve a fixed-switching frequency functionality for the FCS-MPC. The used approach combines the FCS-MPC with the SVPWM, resulting in the calculation of dwell times and the selection of the best two active vectors for the next sample interval. These dwell times have a significant impact on FCS-MPC performance during transient and steady-state conditions, and their values are determined using various mathematical models. To solve the problem of the fixed-switching frequency with lower harmonics distortion compared to the conventional modulated MPC (M 2 PC), an ANN-based trained network is proposed to calculate the duty-cycle of the applied vectors and thus the dwell time in the next sampling interval. The ANN network receives the cost functions of the two active vectors and the zero vector from the M 2 PC control algorithm and determines the optimal duty-cycle for each vector based on a proper tuning. In this way, three goals are achieved, the first goal is that the algorithm explicitly obtains a fixed-switching frequency, and secondly, the cost is as simple as the conventional M 2 PC. Finally, the feature of including objectives and non-linearity is still applicable. The paper's case study used the two level voltage source inverter (2L-VSI) for uninterruptible power supply (UPS) applications. The results based on MATLAB/Simulink revealed that the ANN-M 2 PC has retained all FCS-MPC features in addition to operating at a fixed-switching frequency, while the power quality is significantly enhanced. [ABSTRACT FROM AUTHOR]

This paper presents a method for switching reduction in cascaded H-bridge converters. Given the wide applicability of this topology, it would be especially desirable to increase its efficiency with switching losses reduction techniques. Since this type of converter requires voltage balancing methods, several modulation methods consider the possibility of combining the balancing and switching reduction goals together. In this paper, a previously disclosed optimization-based balance method was modified further to consider the switching losses in its objective function. Each commutation was penalized in proportion to the phase current and the module voltage, thus avoiding commutations that would produce the most losses but tolerating low-losses commutations. The structure of the original method was maintained so that the algorithm could be applied with minimal change. The results show that it is possible to reduce the switching up to 14% without any noticeable drawback and up to 22% at the cost of a greater DC-link ripple. It is also possible to selectively reduce the effective switching frequency of only some modules, making it significantly low. This extends the adaptability of the converter, possibly allowing hybrid converters with modules of different transistor technologies. [ABSTRACT FROM AUTHOR]

Multilevel inverters are a new class of dc-ac converters designed for high-power medium voltage and power applications as they work at high switching frequencies and in renewable applications by avoiding stresses like dv/dt and has low harmonic distortion in their output voltage. In variable speed drives and power generation systems, the use of multilevel inverters is obligatory. To estimate the switching positions in inverter configuration with low harmonic distortion value, a fast sequential optimization algorithm has been established. For harmonic reduction in multilevel inverter design, a hybrid optimization technique combining Firefly and the Genetic algorithm was used. In several real-time systems and for solving complex engineering problems, optimization approaches are gaining popularity. Based on Grey Wolf Optimization (GWO), this research paper proposes a novel multilevel inverter architecture. The GWO algorithm is based on the natural leadership hierarchy and hunting mechanism of grey wolves (Canis lupus). The Grey Wolf Optimizer (GWO) algorithm is used to find the best switching angles for a cascaded multilevel inverter in order to eliminate some high order harmonics while sustaining the desired fundamental voltage. The proposed inverter has 15 stages, and the circuit’s unique feature includes a limited switching device. This proposed method comprises, MOSFET-based switches well as three DC sources in the main circuit. The switching parameters of the inverter topology are tuned using GWO in this methodology. The THD value of the proposed system is reduced to 6.629% compared to that of Multilevel Inverter using Genetic Algorithm, standalone power supply, Firefly assisted Genetic Algorithm, hybrid APSO algorithm, DC voltage regulation and FPGA. A few simulation studies have been included in this paper to affirm the capability of the hybrid topologies with various condition parameters, dynamic changes, and modulation indexes. [ABSTRACT FROM AUTHOR]

Cascaded H-bridge inverters, which belong to strongly nonlinear time-varying system with complex dynamics, have been widely used in high-voltage and high-power engineering fields. In this paper, a carrier phase-shifted sinusoidal pulse-width modulation cascaded H-bridge inverter is taken as an example with piecewise analysis to establish the discrete iterative mathematical model. Furthermore, the nonlinear dynamic behavior of this inverter system is investigated using folding diagrams, spectrum diagrams, bifurcation diagrams, Lyapunov exponents, etc. We find that this inverter can exhibit multiperiod bifurcation, tangential bifurcation and paroxysmal chaos within certain ranges of control coefficients and other circuit parameters, which will influence the system's stability seriously. On the basis of this discovery, the sinusoidal time-delay feedback control method is proposed. The difference between the load current of the controlled object and its own delay is used to form a feedback term, which is then fed into the sine function and proportional link to obtain the control term. Moreover, the Jacobian matrix of this feedback inverter system is derived, and the constraints on the feedback control coefficient are obtained based on the Jury criterion. Simulation results have verified the effectiveness of such a sinusoidal time-delay feedback control method, which can improve the stability and anti-interference of the system. The research can be used to provide some reference and guidance for the circuit design, debugging and control of cascaded H-bridge inverters. [ABSTRACT FROM AUTHOR]

In PMSM drive systems, sensor-less vector control of permanent magnet synchronous motors (PMSM) over the entire speed range poses considerable challenges. Through the design and simulation of the sensor-less vector control system of PMSM, this paper proposes a novel method for sensor-less field-oriented control (FOC) for PMSM applications. To solve this intricate control problem, FOC combines gh-reference frame space vector pulse width modulation (SVPWM) with cubature Kalman filter (CKF). Implementing CKF to estimate rotor position and speed accurately provides the basis for this sensor-less control technique. Furthermore, the integrated control system using gh-SVPWM aims to reduce controller board computing resources utilization while minimizing torque ripple and stator current harmonic distortion. The effectiveness of CKF-based sensor-less FOC integrated with gh-SVPWM is verified in various operating environments using an extensive simulation and experimental framework, confirming its potential to enhance PMSM driving performance and efficiency in different applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel jitter reduction technique for a voltage-controlled ring oscillator (VCRO). This technique is helpful in employing VCRO-based circuits like Analog to Digital Converter (ADC), Phase Locked Loop (PLL) and time-based circuits whose performance is severely degraded by high jitter. In the proposed technique, the jitter is extracted using Excess Phase Discrimination (EPD) block and is transformed into Pulse Width Modulated (PWM) signal, which is then fed into the Phase Compensator (PC) block. This block reduces the jitter by about half its value after enabling the Single Ended Injection Locking (SEIL). The proposed work is designed in SCL 180 nm CMOS technology at 1.8 V supply. On enabling the proposed circuit, the Root Mean Square (RMS) jitter reduces from 5.94 to 2.58 ps (about 56%) for VCRO running at 58 MHz and consumes a total power of 375.84 μ W. The overall performance of the proposed circuit does not vary much in the post-layout simulations, hence demonstrating the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

In this paper, a photovoltaic (PV) microinverter capable of operating in both island mode and grid-connected mode by means of a reconfigurable control scheme is proposed. The main advantage of control reconfiguration is that in grid-connected mode, the microinverter works as a current source in phase with the grid voltage, injecting power to the grid. This is the operation mode of most commercial grid-connected PV microinverters. The idea is to provide those microinverters with the additional functionality of working in island mode without changing their control algorithms for grid-connected mode, which were developed and refined over time. It is proposed that in island mode, the microinverter control is reconfigured to work as a voltage source using droop schemes. These schemes consist in implementing P/Q strategies in the inverters, in order to properly share the power delivered to the loads. The aim of the paper is to show that the proposed control reconfiguration is possible without dangerous transients for the microinverter or the loads. Simulation and experimental results on an 180-W PV microinverter are provided to show the feasibility of the proposed control strategy. [ABSTRACT FROM PUBLISHER]

High current qualities and high efficiencies are always two important characteristics for power converters. However, it is challenging to achieve the two targets simultaneously. In this paper, the dead‐time‐effect elimination pulse‐width‐modulation (PWM) for improving current qualities and the discontinuous PWM (DPWM) for reducing switching losses are combined, proposing a double‐modulation‐wave DPWM. An additional modulation wave is added, whose amplitude is adjusted according to the current polarity. By utilizing the added drive pulses in the current freewheeling stage, the proposed double‐modulation‐wave DPWM successfully reduces the dependence on the current polarities. The overmodulation phenomenon brought by the added modulation wave is analysed, which is proved to be negligible for achieving the maximum modulation index of 1.15. Finally, the effectiveness of the proposed double‐modulation‐wave DPWM is experimentally verified at a switching frequency of 40 kHz. [ABSTRACT FROM AUTHOR]

Open-end winding five-phase induction motor (OeW-5PIM) configuration is used in industrial applications, where minimization in the total harmonic currents and high reliability are needed. The majority of the literature on OeW-5PIM topology discusses field-oriented control and direct torque control in addition to other robust control techniques such as the backstepping approach. This paper focuses on the mathematical and experimental approaches of backstepping control (BSC) and rotor-flux-oriented control (RFOC) for an OeW-5PIM topology. The space vector pulse width modulation (SVPWM) strategy is associated with the suggested control techniques to improve the dynamic performance (i.e., reducing ripple, fixed switching frequency, etc.) of the studied motor. Furthermore, the RFOC-SVPWM and BSC-SVPWM are comprehensively compared using experimental implementation under various situations such as load torque, open-phase fault, and high/low-speed operation. [ABSTRACT FROM AUTHOR]

This paper presents a novel DQ-based multicarrier pulse width modulation PWM for a single-phase, three-level PV-powered grid-connected F-type inverter. The main control objective in the proposed inverter is to regulate the grid current with low total harmonic distortion and load power components compensation. Despite the F-type inverter's advanced advantages, there are only a few works addressing the control issue in the literature yet. The proposed control and switching methods aim to achieve both DC-side voltage balance and the lowest switching losses. The proposed scheme has been designed based on a modified multicarrier PWM switching algorithm. Consequently, the proposed control method is able to satisfy the requirements of DC-side voltage balance and achieve lower switching losses. A further advantage of the proposed control and switching methods is that they retain the main advantage of the F-Type inverter, which is that only 25% of the power switches are exposed to full DC voltage. This is an important advantage since it reduces the overall cost of the inverter and improves its reliability. Overall, the proposed modified multicarrier PWM switching algorithm appears to be a promising approach for controlling the F-Type inverter, offering improved performance and efficiency compared to other control methods. The theoretical model was verified through simulation using MATLAB/Simulink. According to the simulation results, the grid current and dc capacitor voltages are successfully managed in all operational situations. [ABSTRACT FROM AUTHOR]

The growing utilization of single-phase pulse width modulation (PWM) rectifiers in various applications has spurred interest in detecting and monitoring faults in these devices. In particular, voltage and current sensors play a crucial role in the control loop of these rectifiers. However, sensor faults can significantly affect the converter's performance and availability. This paper introduces a novel and efficient method for detecting and decoupling sensor faults in single-phase PWM rectifiers. The proposed method utilizes residual generation and incorporates an extended filter within the rectifier. Unlike conventional filters, the presented fault detection and isolation (FDI) method effectively eliminates the influence of disturbances on the residual signal. This feature helps prevent false alarms in the monitored system, ensuring reliable fault detection. To evaluate the effectiveness of the approach, hardware-in-the-loop and simulation tests were conducted. The results from these tests provide substantial evidence supporting the efficacy of the proposed method. The hardware-in-the-loop experiments involved real-world implementation, validating the practicality and reliability of the approach. Meanwhile, simulation tests allowed for a comprehensive analysis of system behavior and performance under various fault scenarios. The findings demonstrate the rapid and dependable nature of the proposed method for detecting and decoupling sensor faults in single-phase PWM rectifiers. By effectively mitigating the impact of disturbances on the residual signal, false alarms are minimized, ensuring accurate fault detection. The experimental validation highlights the practical applicability and effectiveness of the proposed approach, making it a valuable contribution to fault detection in single-phase PWM rectifiers. [ABSTRACT FROM AUTHOR]

Introduction. The advantages of a high-power quality waveform and a high voltage capability of multilevel inverters have made them increasingly popular in recent years. These inverters reduce harmonic distortion and improve the voltage output. Realistically speaking, as the number of voltage levels increases, so does the quality of the multilevel output-voltage waveform. When it comes to industrial power converters, these inverters are by far the most critical. Novelty. Multilevel cascade inverters can be used to convert multiple direct current sources into one direct current. These inverters have been getting a lot of attention recently for high-power applications. A cascade H-bridge multilevel inverter controller is proposed in this paper. A change in the pulse width of selective pulse width modulation modulates the output of the multilevel cascade inverter. Purpose. The total harmonic distortion can be reduced by using filters on controllers like PI and fuzzy logic controllers. Methods. The proposed topology is implemented with MATLAB/Simulink, using gating pulses and pulse width modulation methodology and fuzzy logic controllers. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage and number of DC sources are analyzed with conventional topologies. Practical value. The proposed topology has been very supportive for implementing photovoltaic based multilevel inverter, which is connected to large demand in grid and industry. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present our research into the reduction of vibrations in induction motors. The use of power inverters results in the generation of electrical harmonics, which increase the level of the mechanical vibrations of electrical machines. To reduce these harmonics, we present a discontinuous pulse-width modulation (PWM) control strategy based on carrier-wave modulation applied to multilevel inverters. Using the proposed modulation technique, the amplitude of the electrical harmonics is reduced, as compared to other conventional techniques. These current harmonics produce the MMF (magnetomotive force) harmonics in the air gap, which are one of the main sources of vibrations. The control strategy makes it possible to vary the electrical spectrum at the output of a multilevel inverter by modifying a control parameter of the carrier wave in the PWM, thus avoiding the natural frequencies of mechanical resonance. The proposed technique also has the feature of attenuating the total harmonics distortion of the voltage of the multilevel inverters, as well as the achievement of a higher RMS value of the output voltage for the same DC level. Laboratory results for an induction motor with different modulation strategies, applied in a multilevel inverter and compared to the strategy presented, are attached. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model of 255 kW grid-connected solar photovoltaic (SPV) system. To study the performance characteristics of the grid-connected SPV system, a new hybrid adaptive grasshopper optimization algorithm with the recurrent neural network (AGO-RNN) control technique was implemented. Furthermore, the power quality at the point of common coupling (PCC) has been studied using the conventional (PSO) and proposed AGO-RNN controllers. The characteristics of the PV system were analyzed under varying environmental (variable irradiance and temperature) conditions considering 3 different cases such as (i) standard test conditions (STC), (ii) variable radiation with constant temperature, and (iii) variable radiation with variable temperature. For each case, the total harmonic distortion (THD) has been calculated using the proposed AGO-RNN control technique, and the results were compared with particle swarm optimization (PSO) technique. The 255 kW PV model is initially developed and connected to a three-level NPC inverter, an MPPT-based perturbation and observation algorithm. Later, the PV model is controlled by an AGO-RNN pulse width modulation (PWM) controller and is then integrated to the main grid at PCC. The main advantage of this technique is exploiting the separate DC-DC converter between the SPV module and the inverter. Finally, the proposed grid-connected SPV system was simulated on MATLAB for analyzing the performance of the system based on its I-V and P-V characteristics, inverter voltage, grid power, gird voltage, grid current, power factor, and THD under different environmental conditions. The simulation results demonstrate that the current magnitude and THD of the SPVGC system are improved with the cutting-edge AGO-RNN controller compared to PSO in all three different scenarios, and this value is less than 1.6%, which is within the permitted limits of IEC 61727 standards. [ABSTRACT FROM AUTHOR]

A modular multilevel converter‐based high voltage direct current (MMC‐HVDC) system involves a large number of cascading submodules (SMs). The failure of SMs may critically degrade the system performance. Therefore, several redundant SMs can be incorporated and reasonably controlled to ensure the system reliable and continuous operation even if certain SMs fail. This paper proposes a semi‐hot redundant method for MMC‐HVDC systems. In the proposed strategy, when the system operates normally, the redundant SMs are controlled in a lower voltage range. These SMs do not require frequent charging and discharging, which decreases the switching loss. When ordinary SMs fail, the faulty SMs are bypassed and the corresponding number of redundant SMs can be promptly recharged to the rated voltage to replace the faulty SMs. The semi‐hot reserved SMs can shorten the transient process of faulty SMs replacement, and in this process, the absence of faulty SMs does not considerably influence the system. Thus, the original control and modulation strategies of the system do not need to be modified when several SMs fail. The performance of the proposed method is compared with those of the existing methods, and its validity is demonstrated through a small‐scale experimental prototype. [ABSTRACT FROM AUTHOR]

This paper presents the energy savings achieved by using a particular three-phase permanent-magnet motor drive control strategy in an elevator application. The proposed control methodology, based on a particular variable-amplitude variable-frequency voltage control pattern technique implemented in a permanent-magnet motor, is compared to a standard induction motor elevator case. By adopting appropriate simultaneous changes in the amplitude and frequency of the motor voltage, high speeds can be attained in conjunction with smooth starting and stopping actions involving a reduced supply current during the respective movement of the elevator. In addition, this method exhibits a high power factor with a good driving quality. The control technique introduced achieves the levelling-off of the floor and the group movement of the system using in the programmable memory a speed pattern that is generated targeting proportionality to the position of the lift. In that respect, significant energy savings can be obtained, which, depending on the type of motor implemented, can be up to 30% compared to the conventional techniques. These improvements can be attained with the appropriate handling of the applied pulse width modulation techniques. Various simulated and experimental results are given, illustrating the respective energy savings achieved with the proposed methodology. [ABSTRACT FROM AUTHOR]

To improve the static performance, dynamic performance, and current balance of a current-source PWM rectifier with multi-modules, a comprehensive control method with passivity-based control and current balance control is proposed in this paper. Current balance control, which is based on AC voltage sequencing, has the advantages of being easy to implement and not being limited by the number of modules. Mathematical modelling, controller design, and simulation verification were conducted successively, and the results show that the comprehensive control method has a low current impact and high power quality. At the same time, module currents are well balanced, even under external disturbance, when using current balance control. [ABSTRACT FROM AUTHOR]

Flywheels are nowadays a solution for the dynamic charging of electric vehicles since they act as transient energy storage. The need for a top efficient reversible power converter for the flywheel system is crucial to assure high dynamic performance. The paper presents the design of a 50 kW highly efficient reversible three-phase DC–AC inverter involving the most recent silicon carbide metal oxide semiconductor field effect transistors, and its experimental validation on a home-made emulator. Highest efficiency in reversible mode, compactness, and thermal enhancement are the targeted objectives that have been achieved. The power converter prototype evaluated on an original pulse width modulation testing-bench is able to emulate the working of the flywheel system. High frequency pulse width modulation switching, speed cycle operating, and thermal losses are evaluated. In addition, an efficiency above 99% for the converter has been attained, enabling robust functioning of the flywheel system emulator to perform specific charging profiles for electric vehicles. [ABSTRACT FROM AUTHOR]

Maintaining safe and efficient operation in a single-phase pulse width modulation (PWM) rectifier that employs current sensors relies heavily on accurate sensor readings. However, several factors such as environmental conditions, aging, or damage can lead to sensor faults. Therefore, it is imperative to implement robust fault detection methods to ensure reliable system operation. The use of unknown input observer techniques is one such method that involves analyzing the differences between actual and estimated states to detect and identify faults in the system. This paper presents the development of a fault detection method that employs an unknown input observer with high sensitivity to faults and disturbance rejection to achieve robust fault detection. The method involves modeling the system as a state-space model and designing an observer to estimate the system's state variables based on input and output measurements. The deviations between the actual and estimated states are then analyzed to detect and identify sensor faults, without the need for additional hardware, making it a cost-effective solution. Hardware-in-the-loop tests confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]