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Multioutput converters with single input source are currently studied as an alternative to conventional dc–dc topologies in order to improve power density in low-power multiload applications. This paper reviews three different ways in which a boost topology can be customized to supply multiple outputs. The first way uses a charge-sharing approach using individual switches to distribute inductor energy to different capacitors. The second method of creating a multiport converter (MPC) combines two converters with similar front end to generate two outputs using only one controlled switch. Using this method, a boost converter can be combined with single–ended primary–inductor converter (SEPIC), Cuk, and current source converter topologies. The third method uses time multiplexing of switches to produce two regulated ports and is referred to as switched-boost action. This method uses relatively less number of switches and allows regulation and control of all the outputs. Practical utility of switched-boost action based MPC is reported in this paper. This switched-boost MPC is applied to a renewable power converter system to interface a solar panel, a battery, and home loads to produce a 12-V and a 48-V bus. The 12-V bus is interfaced to battery and capable of optimally charging the battery in constant current–constant voltage (CC-CV) mode. The converter is demonstrated to operate with solar panel as it supplies a 12-V battery and a 48-V load bus. When the solar power is not available, the converter automatically goes into a mode in which the 12-V battery supplies the loads on the 48-V bus. [ABSTRACT FROM AUTHOR]

Finite state model predictive control (MPC) has been recently applied to several converter topologies, as it can provide many advantages over other MPC techniques. The advantages of MPC include fast dynamics, multitarget control capability, and relatively easy implementation on digital control platforms. However, its inherent variable switching frequency and lower steady-state waveform quality with respect to standard control, which includes an appropriate modulation technique, represent a limitation to its applicability. Modulated model predictive control (M2 PC) combines all the advantages of MPC with the fixed switching frequency characteristic of pulse-width modulation algorithms. The work presented in this paper focuses on the indirect matrix converter (IMC), where the tight coupling between rectifier stage and inverter stage has to be taken into account in the M2PC design. This paper proposes an M2PC solution, suitable for IMC, with a switching pattern that emulates the desired waveform quality features of space vector modulation for matrix converters. The switching sequences of the rectifier stage and inverter stage are rearranged in order to always achieve zero-current switching on the rectifier stage, thus simplifying the current commutation strategy. [ABSTRACT FROM AUTHOR]

A modular quasi-resonant bidirectional dc–dc converter composed of half-bridge gallium nitride modules (HBGM) with reduced switch voltage stress is proposed in this paper. By using an auxiliary capacitor, a resonant circuit is formed to shape the current and voltage so that zero-voltage switching at turn-on instant is achieved. Since the switching loss dominates the power losses in a high-frequency dc–dc converter, the soft-switching performance leads to a noticeable reduction in the total loss; so, the operating temperature will decrease, and consequently, size of the heatsink will be reduced. The proposed circuit takes advantage of enhancement-mode gallium nitride (eGaN) switches regarding their small on-resistance RDS(on), low gate charge, and fast switching speed to improve both efficiency and power density. The main performance issue of adopting GaN switches in a bidirectional dc–dc converter is the high voltage stress of GaN devices, which is handled by connecting the HBGM in the active-clamped stacked configuration, as well as optimizing printed circuit board layout design. Finally, a 1 kW, 600 V laboratory prototype operating at 100 kHz is implemented to validate the proposed concept. [ABSTRACT FROM AUTHOR]

Usually, the high-gain high-efficiency dc–dc converters consist of many passive components, which increases the order of the system. As the order increases, system modeling and control become more complex. Thus, there is a need for the simplification of the small signal modeling process of such converters. This paper presents a generalized small signal model and equivalent circuit for an $n$ th-order coupled-inductor-based high-voltage gain converters (CIHVGC) that can be conveniently used for the control design. The state variable representation of a generalized coupled inductor with p windings is included. A simplified step by step procedure to obtain small signal model using visual inspection is presented. Analysis is included and verified using simulations and experiments for the output voltage regulation of high-voltage gain converters. The usefulness and versatility of the proposed model is verified with three examples of high gain converters belonging to the CIHVGC family. All the analytical, simulation, and experimental details of this paper are presented. [ABSTRACT FROM AUTHOR]

The switched shunting resistor circuit is a classical and practical passive equalization scheme that nevertheless suffers from the voltage imbalance after the charging process. It results from the discrepancy of the shunting resistor and the physical characteristics of supercapacitor (SC) cells. In this paper, the distributed voltage equalization control strategies with the proportional-integral (PI) observer for the switched shunting resistor circuit are analyzed and compared. First, the charging and equalizing system is modeled as the switched system and the system observability is proved. The decentralized control and consensus control are analyzed and their shortages are presented. Then, the leader–follower cooperative control is proposed to improve the charging time while keeping the equalization performance. Meanwhile, the PI observer is designed to estimate the internal capacitance voltage of an SC precisely to avoid the effect of equal series resistance. The control convergence is proved by using the Lyapunov stability and switched system theory. The experimental results show that the proposed method has much superiority and wide applicability than the existing methods for equalizing voltages of SCs. [ABSTRACT FROM AUTHOR]

Parallel ac-link universal power converters are a relatively new class of power converters that can be configured as dc–dc, dc–ac, ac–dc, and ac–ac. These converters are extensions of a buck–boost converter in which the current of the inductor is alternating and the input and output can have any number of phases with any forms, voltage amplitude, or frequency. By placing a small capacitor in parallel with the link inductor, all the switches can benefit from soft switching. The main limitation of the parallel ac-link universal power converter is its large number of switches. A three-phase ac–ac configuration requires 24 unidirectional switches. This paper proposes two topologies based on the parallel ac-link universal power converters that significantly reduce the number of switches. One of the proposed topologies reduces the number of switches in a three-phase ac–ac configuration to 16. The other topology reduces the number of switches to 10. The latter can offer galvanic isolation with only a single-phase high-frequency transformer. This paper presents the principles of the operation of the proposed topologies and evaluates them through simulation and experiments. [ABSTRACT FROM AUTHOR]

This paper proposes a vector control strategy for independent control of two permanent-magnet synchronous motors (PMSMs) using a single four-leg inverter (4LI). An expanded two-arm modulation to obtain a balanced three-phase output voltage is described. This paper also proposes a method to compensate for the fluctuations in the neutral point voltage of two split capacitors in the dc link. The experimental results show that independent speed and position control of two PMSMs can be achieved using a single 4LI with the proposed vector control method. [ABSTRACT FROM AUTHOR]

The European approach underlines the equipment integrity for the safety against electrical hazards “giving collective protective measures priority over individual protective measures” and promotes passive measures against the electric shock that assists to prevent the arc flash hazard. The International Electrotechnical Commission/European Standards (IEC-EN) passive measures are based on the international protection (IP) code, safety procedures, medium voltage (MV) isolator switches with three statuses, MV switchboards tested against internal arcs, and forms of separation for MV-low voltage switchgears. This paper suggests a tentative criterion prospecting a reference value of the arc current to adopt in the protection coordination design. [ABSTRACT FROM AUTHOR]

This paper presents a single-stage light-emitting diode (LED) driver based on a bridgeless power factor correction (PFC) converter and a half-bridge CLCL resonant converter for street lighting applications. The proposed single-stage topology integrates the PFC converter and the CLCL resonant converter by sharing active power switches. The bridgeless PFC converter adopts two buck–boost circuits operating in discontinuous-conduction mode to achieve input-current shaping. It uses two diodes instead of a rectifier bridge to reduce the power loss caused by the diodes. Owing to its superior soft-switching characteristics, the CLCL resonant converter is used. The proposed LED driver has superior features, such as high efficiency, near unity power factor, low total harmonic distortion, and relatively few diodes. A 100-W lab prototype is successfully implemented, and the experimental results verify the effectiveness and feasibility of the proposed LED driver. [ABSTRACT FROM AUTHOR]

In recent years, a three-level T-type inverter has attracted considerable attention due to its advantages, such as simple structure and higher efficiency. However, the reliability of a three-level T-type inverter is particularly important as increased power switches are used. Therefore, a fault-tolerant three-level T-type inverter is proposed in this paper. Fault diagnosis and fault-tolerant control strategies for power switches both in half-bridge and neutral-point bridge are investigated. Under fault-tolerant operation, redundant fourth-leg is used to balance neutral-point voltage and the low-frequency voltage oscillation is eliminated completely. The fault ride-through capability and high-quality output waveforms can be obtained. The effectiveness of the proposed inverter topology and control methods is validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

A method for the seamless transition of three-phase inverters switched between grid-tied and stand-alone modes of operation is presented in this paper. In this method, only the inverter current and voltage sensors are utilized, and no control over the grid-side static transfer switch is needed. The presented method contains two strategies for grid-tied-to-stand-alone and stand-alone-to-grid-tied transitions. In the stand-alone-to-grid-tied transition strategy, a novel algorithm is presented for estimating the grid angle nearly instantaneously, which allows the three-phase inverter to respond very quickly if the grid and point-of-common-coupling voltages are out of phase. This fast response allows the inverter to effectively eliminate the transient overcurrent that would normally occur if it was connected to the grid without first being synchronized. The fast response also allows the inverter to return to normal operation very quickly after such an event. The strategy for the seamless transition from grid-tied to stand-alone mode is also presented. These strategies have been verified through experiments, and the results are presented in this paper. [ABSTRACT FROM PUBLISHER]

This paper deals with the dimensioning of the capacitors in modular multilevel converters based on analytical equations. Considered design parameters are the (periodic) energy fluctuation, the admissible ripple voltage, and the demand in control reserve. Design examples complete this paper. [ABSTRACT FROM PUBLISHER]

This paper proposes and investigates a multilevel ac six-phase motor drive. The system is composed of five isolated three-leg voltage source inverters feeding the open-end windings of an asymmetrical six-phase induction motor (SPIM), which is adequate to generate multilevel voltages for high-power systems with voltage rating restrictions. A simple space vector pulse-width modulation (PWM) based on three similar individual planes and its implementation by means of equivalent level-shifted PWM are presented. A space vector pattern with a high number of voltage vectors redundancies is obtained. These redundancies and the application sequence of the voltage vectors are selected to minimize the amount of changes in the switching states and to decrease the harmonic distortion of the generated voltages. The vector pattern of this optimal modulation is obtained by analyzing only one plane and applied in the same way to the three planes as if they were independent. The developed PWM techniques have low computational complexity and are suitable for low-cost hardware implementations. Simulation results are used to compare the proposed topology with a conventional configuration in terms of harmonic distortion and semiconductor losses. Experimental results demonstrate the feasibility of the proposed drive system. [ABSTRACT FROM AUTHOR]

This paper presents multilevel ac–dc single-phase power conversion cells for applications in which the regenerative operation is either not required or prohibited. The ac primary power source is a single phase from a permanent magnet generator or from an electrical grid. The cells are composed of two h-bridges in cascade: 1) an unidirectional high-voltage h-bridge with two controlled switches; and 2) two power diodes, processing the active power, and a low-voltage h-bridge with four controlled switches and a floating capacitor. These cells can be part of multiphase systems, in which it is required one cell for each phase. Some examples of application for three-phase systems are given, exploring different ways of connection between the single-phase cells. Simulation and experimental results regarding the proposed cells and conventional h-bridge based ac–dc converters are shown for validation and comparison purposes. [ABSTRACT FROM PUBLISHER]

This paper presents a case study of a medium-voltage three-phase capacitor bank (CB) energization, based on an unsynchronized switching scheme using three independent pole vacuum switches simultaneously commanded. The motivations are cost reduction and simplification of the switching scheme. The maximum current and voltage peaks during transients caused by connection of CB with three independent pole switches or a three-phase mechanically coupled switch are compared. A probabilistic assessment for the overcurrents and overvoltages based on Monte Carlo simulation is also performed. The obtained results show that three single-phase unsynchronized switches could be used in a CB, with good transitory response. [ABSTRACT FROM PUBLISHER]

In order to solve the problems caused by the pulsating current ripple of switching-mode power converters, a passive pulsating ripple canceling circuit (PPRCC) is proposed in this paper. The features of the proposed PPRCC include simple, modular structure, and high degree of design flexibility. By integrating the proposed PPRCC, an input current ripple-free flyback-type converter is adopted and analyzed as an example because of its comprehensive utilization in small power rating commercial products. In addition, the switch voltage spike of flyback converter can be suppressed by integrating the proposed PPRCC without using snubbers, it turns out that the efficiency can be further improved. The corresponding operating principle, steady-state analysis, and zero ripple design criteria of the proposed PPRCC are provided. Finally, a 100 W laboratory prototype is constructed to verify the effectiveness of the proposed principle. Experimental results show that the resulting peak-to-peak input current ripple is reduced by 96% and nearly 0.5% and 1.7% improvement in efficiency can be achieved by the proposed PPRCC, at 80 W and 100 W load conditions, respectively. [ABSTRACT FROM PUBLISHER]

Common-mode voltage (CMV) in voltage-source inverters (VSIs) has been well defined and is frequently referred to in the literature. While often referred to, there is no real consistency with respect to how the CMV properties of an individual modulation scheme are evaluated, lacking tools to assess the relative merits or disadvantages of a certain topology or modification of a control scheme. The way that it is analyzed is still mostly a matter of the different authors' foci. In this paper, we propose a metric for the analysis of the CMV, aiming to fill the aforementioned gap. Thereby, the CMV in VSIs is quantified by the number of possible levels and the step sizes between different levels, as well as the respective frequencies of occurrence. The first two are given by the number of levels and the number of phases of the inverter. Depending on the modulation (control) schemes, all possibly available levels or a few of these levels are present in the CMV. We illustrate the use of the tool by applying it to thoroughly study the CMV properties intrinsic to the topologies of multilevel multiphase single- as well as double-ended diode-clamped VSI drive systems. As part of this analysis, we uncover new relationships concerning the existence of zero CMV level. Furthermore, we exemplarily apply the developed tool to the assessment of the CMV properties of selected pulse width modulation (PWM) control schemes and translate the findings into an interpretation of the endangerment of a given drive to suffer damage from inverter-induced bearing currents. The theoretical findings are supported by measurements. This paper also reviews the literature on CMV in multilevel multiphase VSI systems. With the proposed metric in mind, the CMV being mostly discussed as an element of different foci becomes even clearer, confirming again the need for the development of such a tool. [ABSTRACT FROM AUTHOR]

Starting of an induction motor is a process that creates many challenging problems for the motor and operations of the power system. The induction motor can be damaged, characteristics can be changed, and performances of the motor can be worsened. Having a significantly higher starting current than the rated current can produce mechanical and thermal stress on the motor and the loads. High-voltage fluctuations, dips, and sags can occur in electrical power systems associated with the motor. Many different methods have been developed to address particular induction motor starting problems associated with motor size and the stability of the connected network. A soft starter is a relatively new device and is used for smooth start of induction motors, particularly medium voltage motors, and adds flexibility in the operation and the interoperability. It is an integration of complex power control apparatus for reducing starting current in a medium voltage solid state soft starter. Electrical transients during switching ON and OFF processes are a major concern for the silicon controlled rectifiers (SCRs), current rise rate during switching ON—di/dt, and over voltages during switching OFF—dv/dt. During the transient process, the currents rise and di/dt passing through the SCRs can damage them. This paper is focused on identification of parameters of the transient process, protection, and limitation of di/dt by inserting an inductor in the soft starter circuit to limit di/dt to a safe level. Mathematical analyses for the purposes of the SCR protection and measurements are presented. [ABSTRACT FROM AUTHOR]

In this paper, current collapse phenomena and thermal effects in normally-off and normally-on GaN HEMTs are investigated. The experimental results show that a high-off-state voltage and high-switched drain current at high junction temperature cause an increase of the on-state resistance ${{\rm{R}}_{{\rm{DSON}}}}$. Varying the switching frequency from 50 to 400 kHz, an increase of the on-state resistance is further observed for both types of GaN devices. It is evident from these experiments that the number of switching transients significantly influences the increase of the RDSON, suggesting that this increase is due to a current collapse in GaN HEMTs. A detailed comparison of the evaluated R DSON between GaN transistors and the high-speed CoolMOS-C7 transistor is presented. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of the independent drive characteristics of two three-phase induction motors (IMs) fed by a four-leg inverter (FLI). The FLI is a single inverter that can drive two three-phase ac motors independently. The inverter consists of four legs and two capacitors connected in a series. The U and V phases of both motors are connected in each leg, respectively, whereas the W phase of both motors is connected in the neutral point of two-sprit capacitors. The pulsewidth modulation technique in three-phase voltage source inverter is not directly applicable for the FLI because only two phases must be modulated. Then, this paper also analyzes about the neutral point potential of two-sprit capacitors and inverter output voltage. Next, the modulation technique in the FLI is also shown. The experimental results demonstrate the characteristics of two IM independent drives and the validity of those analytic results. [ABSTRACT FROM AUTHOR]

Over the past decade, the direct methanol fuel cell (DMFC) has been considered as a potential candidate of power sources for portable electronics due to its high energy density and environmental friendly operation. However, the use of diluted fuel loading and active fuel mixer/pump limits the DMFC's efficiency and operating time dramatically. The disadvantages become more severe in microscale DMFCs which require high conversion efficiency within a small physical space to meet the strict working specifications. In this paper, a low-power micro fuel supplier with programmable concentration regulation was designed and fabricated by using microelectromechanical system technology. The prototype adopted surface-tension pumping as the primary driving force to deliver fuel at zero power consumption. In addition, a well-arranged microfluidic capillary network was used to regulate the fuel concentration. A pulse-power actuated bubbler switch was embedded in the capillary network to achieve the liquid flow control dynamically and to adjust the fuel concentration for micro-DMFC ( \muDMFC) reaction. Both electrolysis and thermal bubble actuations were investigated in this paper for their effective operations in the prototype. The advantage of precise and low-power fuel regulation within a compact system volume makes the proposed fuel delivery subsystem a suitable candidate for future on-chip \muDMFC development. [ABSTRACT FROM AUTHOR]

The conventional current-source inverter has two major problems: unidirectional power flow and voltage boost operation, which make it impossible to be used in many applications, such as hybrid electric vehicles and general-purpose variable-speed motor drives. Z-source inverters (ZSIs) can solve both problems. Quasi-ZSIs (qZSIs) were recently proposed as an important improvement to traditional ZSIs. Besides the advantages inherited from ZSIs, qZSIs also have several of their own merits. This paper presents a comprehensive study on the new features of current-fed qZSI, including the advantageous buck–boost function, improved reliability, reduced passive component ratings, and unique regeneration capability. The current-fed qZSIs are bidirectional with an additional diode, unlike the voltage-fed ZSI that needs a switch to achieve bidirectional power flow. A modified space vector pulse-width-modulation method is proposed, and the available operating regions for motoring and regeneration operation are analyzed in this paper. Since the current-fed qZSI has the same operation as the current-fed ZSI, many results of this paper are also applicable to the current-fed ZSI. A reverse-blocking insulated-gate bipolar-transistor-based current-fed qZSI prototype was developed in the laboratory. Simulation and experimental results are shown to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

In this paper, a new design methodology for low-voltage electromagnetic energy harvesting systems consisting of a microgenerator and power processing circuit is introduced. In the first section of this paper, a simple topology for a resonance-based electromagnetic generator is presented. The microgenerator is capable of producing a voltage of a few hundred millivolts. Since traditional two-stage power conversion schemes cannot be used for such a low ac voltage, a suitable single-stage ac–dc converter is utilized for power processing. The converter boosts the low ac voltage to a nominal dc voltage required by electronic devices. As a part of integrated design, the coil of the microgenerator is fabricated such that it can be utilized both for electromagnetic induction and power processing. Such an arrangement improves efficiency and makes the system compact. The converter is controlled to regulate the output voltage under varying input or load conditions. Simulation and experimental results are presented to validate the operation of the proposed converter with a low-voltage microgenerator. [ABSTRACT FROM PUBLISHER]

A digital dead-beat current controller for voltage source converters is presented in this paper. The control structure is specified in a digital hardware description language, synthesized, and deployed on a field-programmable gate array chip. By updating, with negligible computation delay, the duty cycle twice in a switching period, the reference current error is nulled in half a modulation period, so that the controller's small-signal bandwidth is maximized. In addition, due to a simple transient detection circuit, the large-signal response delay is reduced to a small fraction of the modulation period, which is determined by the chosen current signal oversampling rate. The controller can effectively support different voltage-source inverter applications, such as active filters, uninterruptible power supplies, microgrid distributed energy resource controllers, and dc–dc converter applications, including interface converters for renewable energy sources, laboratory battery chargers, and electronic welding machines. [ABSTRACT FROM AUTHOR]

The architecture of a mission critical power system has to be designed with structures that allow the simultaneous operation of multiple sources (architecture efficiency). Opportunely organized, the business continuity management will project its program and take actions on the sources. Complete control of the system is necessary for all operating occurrences in an electrical power system. Complexity requires that “safe sets” of operating procedures have to be identified, selected, and authorized, as adopting the Parise program. A Human Competent Reaction has to guarantee the operation efficiency as providing decision-making in emergency statuses. The paper deals with a sample case of a system with multiple sources applying the micro approach of the “flock” logic that consists in managing exclusively the adjacencies of each node. The adoption of mechanical locking tools assists the switching procedures. [ABSTRACT FROM AUTHOR]

An application-oriented integration concept for a half-bridge switch assembly has been developed based on the latest generation 70- \mu\m-thin insulated gate bipolar transistors and diodes, which are rated at 600 V/200 A. This paper addresses the design and reliability of the assembly, with a fully bondwireless approach using cylindrical copper bumps. Advanced numerical structural simulation techniques are also applied to assess the influence of interconnect characteristics (material, size, and shape) and try to determine an optimum solution for reducing the stress and creep strain development in the solder joint. Preliminary experimental tests of the power module are also carried out at different switching frequency and loads to prove the validity of the proposed solution in terms of electromagnetic performance. [ABSTRACT FROM AUTHOR]

This paper proposes an offline single-stage light-emitting diode (LED) driver based on a novel approach to reduce low-frequency ripple in LED arrays supplied from mains, while assuring high input power factor (PF). The proposal employs a series resonant dc–dc converter integrated into a bridgeless boost power factor correction (PFC) stage. The resonant stage works to reduce the low-frequency ripple transmitted from the output of the PFC stage to the LEDs with only small power losses. This solution achieves three main goals: 1) reduction of the bulk capacitance used at the dc bus, allowing for the use of long-life film capacitors; 2) increase in the overall efficiency of the LED driver owing to the low switching and conduction losses in the shared switching network; and 3) assuring high input PF. Experimental results of a driver without electrolytic capacitors for a 100-W street lighting LED luminaire are presented, showing overall efficiency in excess of 92%, input PF greater than 0.97, and line current harmonic content in compliance with the IEC 61000-3-2 standard. [ABSTRACT FROM AUTHOR]

The paper focuses on the active balance of modular hybrid asymmetrical cascade multilevel drives. It investigates special configurations where the high-voltage cell can be operated at low-switching frequency, while correcting the energy imbalances of the low-voltage cells. Among these, it proposes to use configurations with no more than two types of cells and switching devices for modularity. It proposes a high-dynamic performance active balance scheme that decouples the correction of the different imbalances. This allows fast control of the load, while maximizing the inverter voltage use, which results in a higher energy efficiency. An optimal feedback is proposed to correct phase imbalances through the control of the common mode of the low-voltage cells. The effectiveness of the proposed concepts is validated experimentally on a multilevel drive. [ABSTRACT FROM AUTHOR]

This paper presents a new nonisolated buck/boost-type multilevel dc–dc converter suitable for high-power and medium/high-voltage application. The main features of the proposed topology are as follows: low voltage across the semiconductors, low switching losses, and reduced volume of the output filter. The theoretical analysis is carried out for a five-level bidirectional structure of the proposed converter, operating in Buck mode. The proposed topology presents some capacitors, and their voltage must be balanced for proper operation of the converter. Thus, a capacitor voltage balancing active control using a feedforward technique is proposed and analyzed in detail. In order to validate the theoretical analysis, a prototype with 10 kW output power capability, 1.3 kV to 800 V input-to-output voltage, and 20 kHz of switching frequency was built and experimented. The results attest the advantages of the new dc–dc topology, as well as the new capacitor voltage control technique. [ABSTRACT FROM AUTHOR]

This paper proposes a real-time hybrid fuzzy bang–bang (BB) controller with switching function, in order to implement a full nonlinear control law. The controller consists of a fuzzy-BB controller in parallel with a BB controller while the system is in operation. In order to circumvent the shortcomings of fuzzy-BB and BB-based controllers, a hybrid fuzzy-BB controller is proposed, in which the output can be either the outputs of the two, i.e., the fuzzy-BB or BB units that are being switched as per the absolute error signal. Normally, the BB controller operates in general; the fuzzy-BB controller is activated when the drive system experiences oscillatory behavior. The choice between the fuzzy-BB and BB controllers is based on a set of simple if–then rules; the overshoot and the oscillatory behavior have to be detected by the absolute errors. Trajectory tracking of nonlinear motor drives in position mode serves as a test bed for the control law, and a real-time experiment allows for the assessment of its practical applicability. The hybrid fuzzy-BB controller has been implemented on hardware with a dSPACE digital signal processor, and it is observed that the performance of the controlled brushless dc motor drive with the hybrid fuzzy-BB controller is assuring. Noticeably, experimental results demonstrate that the proposed controller is capable of significantly cultivating the motor performance under random disturbance and different loading conditions. [ABSTRACT FROM PUBLISHER]

This paper describes the analysis, design, and construction of an ozonizer based on a single-switch resonant converter (SSRC). The main contribution of the work is the removal of the transformer from the SSRC, resulting in much smaller footprint and higher efficiency. High voltage (up to 4.0 \kVp - p) is achieved using a resonant tank, which comprises of an LC circuit combined with the chamber's equivalent circuit components. Despite the absence of the transformer, the topology is able to generate sufficiently high voltage to initiate and sustain the formation of micro-discharges. Geometrically, the chamber is constructed as a planar type, using muscovite mica as dielectric. The main advantage of using mica is its availability in thin sheet (less than 1 mm), which then allows for the lowering of the initiation voltage. To validate the analysis and design, an experimental prototype of the ozonizer is build. It is found that the ozonizer draws very little power, i.e., less than 8 W with very high ozone yield (over 120 g/kWh at 1.0 L/min). The maximum measured efficiency is 75%. The proposed ozonizer is fed from a low voltage power source (up to 40 V dc) and hence its suitability for a wide range of portable applications. [ABSTRACT FROM PUBLISHER]

This paper presents single- to three-phase dc-link converters with a reduced number of controlled switches for either usual or reduced currents in switches of the rectifier. A suitable model and a control strategy, including a synchronization approach, are developed to obtain the maximum dc-link voltage utilization. Such a synchronization method, associated with the pulse-width-modulated generation signal, forces the input current to have the same phase angle as the input voltage. The main advantage of the proposed converters along with the synchronization method is the reduction of the zero-crossing distortion normally caused by the use of diodes. Simulated and experimental results are presented to confirm the validity of the theoretical expectations. [ABSTRACT FROM PUBLISHER]

A variety of clean-energy systems, such as electric and hybrid vehicles or wind-power sources, can appreciably benefit from motors or generators directly connected to the mechanical part of the system. This paper describes the development and experimental investigation of two radically different low-speed permanent-magnet ac machines: a multilayer-winding synchronous machine and a switched-flux machine. The study allows an in-depth comparison of these divergent concepts from the viewpoint of practical applications in the clean-energy infrastructure. [ABSTRACT FROM AUTHOR]

A variable-frequency drive (VFD) having a 440-V front-end current source rectifier (CSR) interface to a voltage source inverter (VSI) feeding a Permanent-Magnet Axial-flux Air Core motor combination is a solution for low-horsepower pump and fan control that is both power dense and compatible with a shipboard environment. This paper describes the control and power platforms for the CSR/VSI and provides experimental results for a 250-V 3.3-kW system. Power density and efficiency comparisons are made between equivalent CSR/VSI- and voltage-source-conversion-based VFDs to demonstrate that the CSR/VSI-based VFD is more power dense. [ABSTRACT FROM AUTHOR]

The common-mode voltage (CMV) is known to be a source of electromagnetic interference, and it is potentially dangerous for the machine windings' insulation and bearings. CMV has been analyzed for three-phase machines supplied by voltage-source inverters, showing that modified pulsewidth modulation and model predictive control (MPC) techniques can significantly reduce the CMV at the expense of increased current distortion. This paper analyzes the CMV for five-phase drives and proposes a modified MPC strategy that accounts for the CMV reduction. The MPC can adjust the weights of the cost function to find a good balance between CMV reduction and low current distortion. The MPC strategy is experimentally tested showing how the CMV can be effectively reduced, thus improving the multiphase drive performance. [ABSTRACT FROM AUTHOR]

The advancement in power electronics has made the use of any number of phases in ac machines possible since with the inverter, any number of phase voltages can be realized as long as the corresponding inverter exists. To supply multiphase drives requires multiphase voltage source inverters (VSIs) whose output voltages depend very much on the methods of generating the pulses to turn on and turn off the inverter devices appropriately. This paper presents an analytical technique for the determination of the expressions for the modulation signals used in the carrier-based sinusoidal and generalized discontinuous pulse width modulation schemes for two-level, five-phase voltage source converters. These expressions can be used for both balanced and unbalanced phase voltages generated by any two-level multiphase inverter, in generating the required reference signals appropriately. An example of a five-phase VSI is presented to illustrate the strategy. Simulation and experimental results are presented in which a close examination shows that both results are similar for the balanced and unbalanced load voltage cases. [ABSTRACT FROM AUTHOR]

A new system for switching electrical power using microelectromechanical systems (MEMS) is presented. The heart of the system utilizes custom-designed MEMS switching device arrays that are able to conduct current more efficiently and can open orders of magnitude faster than traditional macroscopic mechanical relays. Up to now, MEMS switches have been recognized for their ability to switch very quickly due to their low mass but have only been used to carry and switch very low currents at extremely low voltage. However, recent developments have enabled suppression of the arc that normally occurs when the MEMS switch is opened while current is flowing. The combination of the arc suppression with the MEMS switch arrays designed for this purpose enables a breakthrough increase in current and voltage handling capability. The resultant technology has been scaled to handle many amperes of current and switch hundreds of volts. Such current and voltage handling capability deliver improved energy efficiency and the capacity to handle fault current levels that are encountered in typical ac or dc power systems. Fault current interruption takes place in less than 10 \mu\s, almost regardless of the prospective fault current magnitude. The properties of the MEMS switch arrays allow the switching mechanism to operate at temperatures in excess of 200 ^\circ\C. The switches also have a vibration tolerance in excess of 1000 G. The combination of fast MEMS switching speed, optimized current and voltage handling capacity of the switch arrays, the arc suppression circuitry, and optimized sensing and control enables a single sensing, control, and switching system to operate in a small fraction of a millisecond. This paper will present the basic physics of the MEMS switches together with recent advances that enable the technology. Some illustrative examples of the ways that the devices may be used to provide protection and control within electrical systems will also be presented. [ABSTRACT FROM AUTHOR]

This paper presents the development and implementation of a new and practical fuzzy switching position controller for process industry control. Compatible with the structure of a bang–bang controller, a two-input fuzzy switching position controller with five rules is proposed. The idea is based on constructing a fuzzy switching control law which is functionally analogous to a traditional bang–bang controller. Fuzzy logic rules are used to enable an improved version of the conventional bang–bang control. The objective is to replace the conventional bang–bang controller with the proposed fuzzy switching position controller. A modified three-stage bang–bang controller is also designed and implemented. This controller is tested under the same conditions as that of the proposed fuzzy switching position controller, and its performance is used as a basis of comparison by which both controllers are measured. Both controllers are implemented in real time, using the position control of a brushless dc motor drive found in the majority of these new robotic devices. A test bed was built and tested in the laboratory using a collection of tools that include both off-the-shelf hardware (dSPACE DSP DS1104) and software (MATLAB/Simulink). Experimental results show that the fuzzy switching position controller produces adequate control performance, particularly in handling nonlinearities and external disturbances. The efficacy of the fuzzy switching position controller is demonstrated by its positive results, practicality, and feasibility in the process industry sector, when compared with a modified traditional bang–bang controller. [ABSTRACT FROM AUTHOR]

This paper presents a simple dynamic overmodulation method to obtain a fast dynamic torque response in direct torque control (DTC) of induction machines with constant-switching-frequency controller. A fast dynamic torque response can be obtained by switching only the most optimized voltage vector during torque dynamic condition. The optimized voltage vector can be identified by comparing the rate of change of torque produced between applications of two possible active voltage vectors, according to the flux position. The selection of the optimized voltage vector can be simply implemented by modifying the flux error status before it is being fed to the lookup table. It will be shown that the proposed switching strategy facilitates the DTC to perform under six-step mode to achieve the fastest dynamic torque response. The effectiveness of the proposed dynamic overmodulation to obtain the fast torque response is verified with some experimental results. [ABSTRACT FROM AUTHOR]

This paper investigates the operation of space-vector-based hysteresis current control in the synchronous reference frame (SRF) for grid-connected voltage source converters. The space-vector-based approach allows for the systematic application of zero-voltage vectors and prevents high switching frequencies caused by phase interaction. The average switching frequency can be minimized by always selecting the zero-voltage vector that is closest to the previous switching state. Implementation in the SRF ensures a simple structure based on two three-level hysteresis comparators and a switching table that fits well into the traditional structure of vector-oriented current control. For operation in a grid-connected converter with an LCL filter, the current references to the hysteresis controllers are given by a dc-link voltage controller and an active damping mechanism for suppressing filter oscillations. Results from simulations and laboratory experiments are presented to illustrate the features of the investigated approach compared to traditional phase-current hysteresis controllers. [ABSTRACT FROM AUTHOR]

This paper presents a three-phase pulsewidth modulation (PWM) technique for brushless dc motor (BLDCM) drives to reduce the commutation torque ripple. As compared to previous approaches, the presented technique does not require any torque observer and calculation of commutation time which may be sensitive to motor parameters and may require more calculation time. The commutation time for the presented technique is determined by a detection circuit which consists of simple comparator circuit. The experimental results derived from a field programmable gate array based controlled BLDCM drive show that the commutation current ripple can be significantly reduced by the presented PWM technique. [ABSTRACT FROM PUBLISHER]

This paper demonstrates improved performance of a three-phase voltage source inverter (VSI) when digital multisampled space vector modulation is used. The modulator and the inverter controller are implemented entirely using a field-programmable gate array platform, thus achieving increased bandwidth with respect to a typical digital signal processor or microprocessor-based controller. Increased controller bandwidth results in lower output voltage harmonic distortion in the frequency range above the fundamental and below the switching frequency. Experimental validation is presented together with the analysis carried out using a state space model of a VSI with an output LC filter. [ABSTRACT FROM AUTHOR]

Digital average current controllers for boost power factor correctors (PFCs) are usually designed for continuous conduction mode (CCM). However, discontinuous conduction mode (DCM) appears in the inductor current near the zero crossings of the input current at light loads, resulting in input current distortion. It is caused by inaccurate average current values obtained in DCM and by the linear CCM PFC controller that is unable to ensure input current shaping in DCM whereby the converter exhibits nonlinear characteristic. This paper proposes a simple digital DCM control scheme that is achieved with minimal changes to the CCM average current control structure. It is mathematically and computationally simple. The result of all arithmetic operations in the proposed current control loop to obtain the desired control output can be achieved in a single clock cycle, whereas other DCM control schemes require multiple clock cycles. Good input current shaping is achieved in both CCM and DCM with the proposed CCM–DCM digital controller. [ABSTRACT FROM AUTHOR]

This paper analyzes the effects of parasitic capacitances in the series connection of insulated-gate bipolar transistors (IGBTs) on their voltage sharing. These parasitics exist naturally due to gate driver interconnects and power circuit physical architecture. Two solutions, which can be combined, are proposed to minimize these effects in order to achieve a better voltage balancing. The first one is based on gate driver self-powering technique. The second one is based on a vertical structure assembly of IGBTs connected in series. The performance offered by these two complementary solutions is investigated and validated on a series connection of three IGBTs in a chopper converter. Both simulation and experimental results show the effectiveness of our approaches. [ABSTRACT FROM AUTHOR]

Switching transients associated with circuit breakers have been observed for many years. Recently, this phenomenon has been attributed to a significant number of transformer failures involving primary circuit-breaker switching. These transformer failures had common contributing factors such as the following: 1) primary vacuum or SF-6 breaker; 2) short cable or bus connection to transformer; and 3) application involving dry-type or cast-coil transformers and some liquid-filled ones. This paper will review these recent transformer failures due to primary circuit-breaker switching transients to show the severity of damage caused by the voltage surge and discuss the common contributing factors. Next, switching transient simulations in the electromagnetic transients program will give case studies which illustrate how breaker characteristics of current chopping and restrike combine with critical circuit characteristics to cause transformer failure. Design and installation considerations will be addressed, particularly the challenges of retrofitting a snubber to an existing facility with limited space. Finally, several techniques and equipment that have proven to successfully mitigate the breaker switching transients will be presented, including surge arresters, surge capacitors, snubbers, and these in combination. [ABSTRACT FROM PUBLISHER]

This paper presents a novel application of half-bridge series–parallel resonant converter (HBSPRC) for dc source and secondary battery interface. The converter practically eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger circuit. Moreover, operation above resonance is preferred, because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. The proposed battery charger circuit has few components and low-energy conversion loss, which enhance the system's overall efficiency. Circuit operation modes are determined from the conduction profiles. Operating equations and an operating theory are also developed. Experimental results based on a 12-V 48-Ah battery charger are proposed to validate the analysis and to demonstrate the performance of the proposed approach. The maximum charging efficiency of the proposed topology during the overall charging period is 93.98%. Satisfactory performance is obtained from the measured results. [ABSTRACT FROM AUTHOR]

A multifunction circuit is presented herein and applied to a synchronously rectified flyback converter, with the circuit not only playing the role of an LC snubber but also detecting the zero crossing of the current to reduce switching loss and feeding the peripheral circuit. Hence, such a converter has high efficiency all over the operating range and, together with one front-end power-factor-correction ac–dc converter, is applied to feeding a LED streetlight. In this paper, the basic operating principles of the proposed topology are first illustrated in detail, and second, some simulated and experimental results are provided to demonstrate the effectiveness of the proposed topology. [ABSTRACT FROM AUTHOR]

This paper proposes a new voltage trajectory control for the field-weakening operation of induction motor drives. The presented method does not require a lookup table and reduces the parameter sensitivity. Moreover, the dc-link voltage utilization can be extended such that the voltage can reach the hexagon trajectory of the space vector of the voltage. The difference between the switching period and the summation of active switching times for inverter pulsewidth modulation control is used for field-weakening control. As the summation of the active switching times is less than its switching period, constant torque is retained. In contrast, the field-weakening control is considered. Smooth and automatic transition between two field-weakening regions can be achieved by the calculated q-axis current subjected to the voltage, current, and maximum pullout torque constraints. Experimental and simulation results will be presented to fully support the claims. [ABSTRACT FROM AUTHOR]

This paper proposes a novel complete electronic ballast for low-wattage metal halide (LWMH) lamps. The lamp driver is based on the integration of a flyback power factor correction (PFC) input stage and a buck–boost inverter stage. The resulting circuit supplies the lamps with a high-frequency (HF) square current waveform, operating from the mains facility. The main feature of the proposed ballast is that through an adequate integration of the stages, the circuit operates with only one controlled switch. This switch is shared by the active PFC input stage, by the output HF inverter stage, as well as by the igniter. The control of the ballast is carried out by adjusting the maximum current through the switch and by fixing the duty ratio. Thus, the resulting output characteristic is suitable for a proper operation of these discharge lamps, including ignition, warm-up stage, and steady-state operation. The obtained HF square waveforms in the lamp avoid the apparition of acoustic resonances. A complete prototype has been built and tested, and experimental results are shown. [ABSTRACT FROM AUTHOR]

This paper presents a quasi-resonant technique for multilevel modular switched-capacitor dc–dc converter (MMSCC) to achieve zero-current switching (ZCS) without increasing cost and sacrificing reliability. This ZCS-MMSCC employs stray inductance distributed in the circuit as the resonant inductor to resonate with the capacitor and provide low dv/dt and di/dt switching transition for the device. The ZCS-MMSCC does not utilize any additional components to achieve ZCS and meanwhile solves the current and voltage spike problem during the switching transition, thus leading to reliable and high-efficiency advantages over traditional MMSCC. Furthermore, the ZCS-MMSCC reduces the capacitance needed in the circuit to attain high efficiency. In this case, the bulky capacitor bank with high capacitance in a traditional MMSCC to reduce voltage difference and achieve high efficiency is no longer necessary. A 150-W four-level ZCS-MMSCC prototype has been built. Simulation and experimental results are given to demonstrate the validity and features of the proposed soft-switching switched-capacitor circuit. [ABSTRACT FROM PUBLISHER]