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Under severe fault conditions in the distribution system, not only input voltages but also input impedances must be considered as unbalanced. This paper presents a new control method for input-output harmonic elimination of the pulsewidth-modulation (PWM) boost-type rectifier under conditions of both unbalanced input voltages and unbalanced input impedances. The range of imbalance in both input voltages and input impedances, for which the proposed method is valid, is analyzed in detail. An analytical approach for complete harmonic elimination shows that PWM boost-type rectifier can operate at unity power factor under extremely unbalanced operating conditions resulting in a smooth (constant) power flow from ac to dc side. Based on the analyses in open-loop configuration, a feedforward control method is proposed. Elimination of harmonics at ac and dc side of the converter affects the cost of dc link capacitor and ac side filter. The proposed method is very useful when the PWM boost-type rectifier is subject to extreme imbalance due to severe fault conditions in the power system. In addition, by using the proposed method, the PWM boost-type rectifier can be operated from the single-phase supply in cases where three-phase source is not available. Simulation results show excellent response and stable operation of the PWM boost-type rectifier under the proposed control algorithm. Experimental and simulation results are in excellent agreement. Index Terms--Harmonic elimination, pulsewidth-modulation (PWM) boost-type rectifier, unbalanced input voltages and impedances, unity power factor.

This paper presents a fully integrated CMOS analog front end for a passive 900-MHz radio-frequency identification (RFID) transponder. The power supply in this front end is generated from the received RF electromagnetic energy by using an RF-dc voltage rectifier. In order to improve the compatibility with standard CMOS technology, Schottky diodes in conventional RF-dc rectifiers are replaced by diode-connected MOS transistors with zero threshold. Meanwhile, theoretical analyses for the proposed rectifier are provided and verified by both simulation and measurement results. The design considerations of the pulsewidth-modulation (PWM) demodulator and the backscatter modulator in the front end are also discussed for low-power applications. The proposed front end is implemented in a 0.35-[micro]m 2P4M CMOS technology. The whole chip occupies a die area of 490 x 780/[micro][m.sup.2] and consumes only 2.1 [micro]W in reading mode under a self-generated 1.5-V supply voltage. The measurement results show that the proposed rectifier can properly operate with a -14.7-dBm input RF power at a power conversion efficiency of 13.0%. In the proposed RFID applications, this sensitivity corresponds to 10.88-m communication distance at 4-W equivalent isotropically radiated power from a reader base station. Index Terms--Backscatter modulation, charge pump, low power, low voltage, pulsewidth modulation (PWM), radio-frequency identification (RFID), rectifier, RF--dc, zero-threshold.

This paper presents a new CMOS integrated analog front-end circuit for 13.56-MHz radio-frequency identification tags. The proposed analog front end consists of a novel CMOS rectified voltage multiplier, a voltage regulator, and a new frequency-shift keying (FSK) demodulator. The proposed single-stage rectifier employing only a PMOS/NMOS pass transistor, an inverter, and one capacitor gets minimal active area and enhances the power conversion efficiency. Moreover, a new technique is used in the proposed FSK demodulator, which includes the data recovery circuit, the multiplexer, the shift register, the phase frequency detector, and the charge-pump circuit. The analog front end has been fabricated in a CMOS 0.35-[micro]m 2P4M technology. The demodulator circuit supports a data rate of 10 kb/s to 1 Mb/s. The power consumption is as low as 0.96 mW, and the chip area without pads is only 0.74 mm x 0.43 mm. Experimental results show that the proposed analog front end works well and confirms the theoretical analysis. Index Terms--Frequency-shift keying (FSK) demodulator, radio-frequency identification (RFID), rectifier, regulator, voltage multiplier.

This paper proposes a novel and simple direct power control (DPC) scheme of a three-phase pulsewidth-modulated rectifier without the use of a predefined switching table. The converter switching state selection is based on fuzzy logic rules, using the instantaneous active and reactive power tracking errors as fuzzy logic variables. The basic idea of fuzzy rules synthesis is based on the knowledge of the instantaneous variation of active and reactive power. According to the input fuzzy variables and in a specific moment, the best switching state of the converter is chosen to restrict the instantaneous active and reactive power tracking errors simultaneously, for maintaining the dc-bus voltage close to the reference value and guarantying the unity-power-factor operation. The main advantages of the proposed DPC scheme, compared to the classical one, are that it is not necessary to use hysteresis comparators, and smooth control of active and reactive power is obtained during all sectors. Finally, the developed DPC was tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance, and verify the validity of the proposed DPC scheme which is much better than the classical DPC. Index Terms--Direct power control (DPC), fuzzy logic control, instantaneous active and reactive power, pulsewidth-modulated (PWM) rectifier, switching table, unity power factor (UPF).

Grid-connected unity-power-factor converters based on one-cycle control (OCC) do not require the service of phase-locked loop or any other synchronization circuits for interfacing with the utility. As a result, these schemes are becoming increasingly popular. However, as the power handled by the converter increases, the power factor deteriorates. To understand quantitatively the cause of poor power factor while negotiating high power loads, large signal models for these schemes are developed. Having understood the cause for poor power factor operation, a modified-OCC-based converter is proposed. This scheme has high power factor while supplying high power loads. Detailed simulation studies are carried out to verify the efficacy of the scheme. In order to confirm the viability of the scheme, detailed experimental studies are carried out on a 3-kW laboratory prototype. Index Terms--AC-DC power conversion, one-cycle controller, power-factor correction, single- and three-phase rectifier.

Synchronous rectification (SR) is mandatory to achieve good efficiencies with low output voltages. If a transformer is driven asymmetrically without dead times, the self-driven SR (SDSR) is a very interesting solution. However, if the transformer is driven symmetrically, the synchronous rectifiers are off during the dead times, and as a consequence, the efficiency is lowered. This paper deals with the optimization of an SDSR system that keeps the rectifiers on even during the dead times. The input voltage is tracked, and the information is used to adapt the gate to the source voltage of the synchronous rectifiers and improve the efficiency. The system has been implemented in a prototype, and the results have been compared with the ones obtained in the same prototype without SDSR. Index Terms--Self-driven, synchronous rectification (SR).

An active current injection network for a three-phase rectifier is proposed. The proposed circuit uses three bidirectional switches operating at low frequency and a half-bridge inverter operating at high frequency. It also uses an inductor in order to make the Current modulation. Because only 3.7% of the total power delivered to the load is processed by the injection network, the proposed converter offers high efficiency, and not only a high power factor is obtained but also the total harmonic distortion is reduced. Operation, analysis, simulation, and experimental results are shown in this paper. Index Terms--Current injection, high power factor, rectifiers, three-phase.

A single-phase boost rectifier system with conventional low-bandwidth voltage loop exhibits poor dynamic response. A simple method is presented to improve the dynamic response of the rectifier without affecting its steady-state performance. A fast voltage controller is used to improve the dynamic response of the rectifier. The increased low-frequency ripple at the output of the voltage controller is filtered out using a new filter. Design methodology for the voltage loop is presented. The filter is simple enough for analog and digital implementations. Low input current distortion, fast voltage-loop response, and improved dynamic response against line and load disturbances are demonstrated experimentally on a 300-W digitally controlled boost rectifier operating at a switching frequency of 100 kHz. Index Terms--AC-DC power conversion, boost rectifier, current control, digital control, dynamic response.

A new phase-shifted full-bridge converter with a voltage-doubler-type rectifier for a high-efficiency power-sustaining module of a plasma display panel is proposed in this paper. The proposed converter employs a voltage-doubler rectifier without an output inductor. Since it does not have an output inductor, the voltage stresses of the rectifier diodes can be clamped at the output voltage level. Thus, since no dissipative resistor-capacitor snubber for rectifier diodes is needed, high-efficiency low-noise output voltage can be realized. Due to the elimination of the large output inductor, it features simpler structure, lower cost, smaller mass, and lighter weight. Furthermore, the proposed converter has wide zero-voltage-switching ranges of lagging leg switches with low current stresses of the primary power switches by using the magnetizing current. In addition, the resonance between the leakage inductor of the transformer and the rectifier capacitors can reduce the current stresses of the rectifier diodes and conduction losses. In this paper, the operational principles, analysis, design considerations, and experimental results are presented. Index Terms--Phase-shifted full-bridge (PSFB) converter, plasma display panel (PDP), voltage-doubler-type rectifier.

This paper presents and analyzes experimental results of a new discrete multiloop nonlinear control scheme, applied to a 1.5-kW laboratory prototype of a three-phase/level/switch boost-type Vienna rectifier. As for most split dc-bus voltage switched-mode rectifiers, the proposed control technique aims to ensure ac line currents shaping, output dc-bus voltage regulatioand dc load unbalance compensation. The proposed technique is based on the dq nonlinear averaged model of the converter. To cancel the inherent nonlinearity of the converter, an input-to-output transform is applied to both inner and outer loops, thus linearizing the system and allowing the application of conventional linear pole placement method for controller tuning. The rectifier performance, during both nominal and severe operating conditions, are then evaluated in real-time using the dSPACE DS 1104 controller board, supported by a Matlab/Simulink Real-Time Workshop environment. Index Terms--High power factor, low ac current total harmonic distortion (THD), nonlinear systems, real-time control, threephase/switch/level rectifier.

An improved zero-voltage and zero-current-switching (ZVZCS) full bridge dc--dc converter is proposed based on phase shift control. With an auxiliary center tapped rectifier at the secondary side, an auxiliary voltage source is applied to reset the primary current of the transformer winding. Therefore, zero-voltage switching for the leading leg switches and zero-current switching for the lagging leg switches can be achieved, respectively, without any increase of current and voltage stresses. Since the primary current in the circulating interval for the phase shift full bridge converter is eliminated, the conduction loss in primary switches is reduced. A 1 kW prototype is made to verify the theoretical analysis. Index Terms--Full bridge, low stress, zero-voltage and zero-current-switching (ZVZCS).

A single-stage single-switch power factor correction (PFC) flyback converter with a synchronous rectifier (SR) is proposed for improving power factor and efficiency. Using a variable switching-frequency controller, this converter is continuously operated with a reduced turn-on switching loss at the boundary of the continuous conduction mode and discontinuous conduction mode (DCM). The proposed PFC circuit provides relatively low dc-link voltage in the universal line voltage, and also complies with Standard IEC 61000-3-2 Class D limits. In addition, a new driving circuit as the voltage driven-synchronous rectifier is proposed to achieve high efficiency. In particular, since a driving signal is generated according to the voltage polarity, the SR driving circuit can easily be used in DCM applications. The proposed PFC circuit and SR driving circuit in the flyback converter with the reduced switching loss are analyzed in detail and optimized for high performance. Experimental results for a 19 V/90 W adapter at the variable switching-frequency of 30~70 kHz were obtained to show the performance of the proposed converter. Index Terms--Power factor correction (PFC), single-stage single-switch converter, variable switching-frequency control, voltage-driven synchronous rectifier (SR).

In this paper, a large-signal modeling technique has been developed for a three-phase, three-level Vienna rectifier operating in continuous conduction mode. The considered circuit is a fifth-order system with time-varying variables on the ac side. This model is first established in the direct abe reference frame using the state space averaging technique, then modified through an abc/dqo transform and adequate duty cycle alteration to avoid time-dependency. The system stability in a closed loop, using a multiloop PI-based control scheme, is proved by the convergence of the phase plane trajectories to the nominal point for any initial condition. These curves are drawn as ac line peak currents as a function of total output dc voltage. The different relationships governing the system inputs/outputs are verified not only for the nominal operating point, but also for a wide operation range. The accuracy of the proposed model is verified on a 1.5-kW experimental prototype controlled by the DS-1104 board of dSPACE. The converter large signal behavior is experimentally analyzed using output time domain responses toward different input variations. Significantly high accordance between the experimental results and the theoretical model, implemented with SIMULINK/Matlab, is verified. Index Terms--High power factor, large-signal modeling, low ac current total harmonic distortion (THD), phase plane curves, three-phase/switch/level rectifier, time response analysis.

Space vector pulsewidth modulation (PWM) schemes for the active front end of a high-power drive normally produce low-order and suborder harmonics due to the low switching frequency and the drifting of synchronization between the PWM waveform and the rectifier input frequency. To provide a synchronized PWM and achieve the best harmonic performance, different space vector sequences suitable for a current-source converter are investigated in this paper. Details on how to achieve the waveform symmetries with a minimum switching frequency for each sequence are discussed. A thorough comparison of the harmonic performance of different space vector sequences is carried out. An optimum space vector modulation method by switching between two best sequences is proposed to achieve the best line-current total harmonic distortion with reduced switching losses. In addition, two synchronization methods, namely a PWM frame regulation method and a direct digital phase-locked loop synchronization method, are proposed. Both methods are equally effective in providing tight synchronization of the PWM waveform with the rectifier input frequency. The work has been verified in simulation and experiment. Index Terms--Current-source drive, current-source rectifier (CSR), digital phase-locked loop (DPLL), high-power converter, space vector pulsewidth modulation (SVPWM), synchronized PWM.

A buck-boost-type unity power factor rectifier is proposed in this paper. The main advantage of the proposed rectifier over the conventional buck-boost type is that it can perform input power factor correction (PFC) over a wider voltage conversion range. With a single switch, a fast well-regulated output voltage is achieved with a zero-current switch at turn-on. Moreover, the switch voltage stress is independent of converter load variation. The proposed converter is well suited for universal offline PFC applications for a low power range (< 150 W). The feasibility of the converter is confirmed with results obtained from a computer simulation and from an experimental prototype. Index Terms--Low harmonic rectifier, power factor correction (PFC), single-stage single-switch rectifier, unity power factor (UPF).

The digital control of a three-phase three-switch buck-type rectifier system is analyzed in this paper. Three main sources of time delays in the control loop can be identified for the implementation on a digital signal processor (DSP): 1) the delay time due to the sampling of the control quantities; 2) the one due to the calculation time of the DSP; and 3) the one due to the sample-and-hold function of the pulsewidth modulator. Using the buck-type system as an example, the influence of the time delay on the stability of the inner current control loop is discussed, and two prediction methods for time-delay compensation, i.e., a linear prediction and the Smith prediction, are comparatively evaluated. The control performance and the effect of the delay times and the prediction methods are shown by simulation results and through measurements on a 5-kW prototype. Index Terms--Digital control, prediction techniques, pulsewidth modulation (PWM) rectifier, time-delay compensation.

This paper deals with sensorless vector-controlled induction motor drives that are fed by a frequency converter that is equipped with a diode front-end rectifier. A small dc-link capacitance is used, which makes it possible to replace the electrolytic capacitors with film capacitors. The natural frequency of the dc link is chosen to be considerably higher than six times the mains frequency but lower than the switching frequency. A recently proposed sensorless controller can be exploited; only minor modifications for small capacitances are needed. The simulation and experimental results of a 2.2-kW drive that is equipped with a capacitance of only 24 [micro]F demonstrate operation in a wide speed range. Index Terms--Control, dc link, film capacitors, sensorless.

In this paper, a new low-frequency predictive current control is proposed for a single-phase cascaded H-bridge multilevel rectifier. The control method has been fully investigated with theoretical analysis, simulation, and experiments on a laboratory prototype with five series-connected H-bridges. However, the analysis and technique are valid for any general N-level structure. The simulations and experimental results presented demonstrate the excellent performance of the predictive control in terms of ac current waveform quality, power factor, and reduced switching frequency of each bridge, in comparison to traditional control schemes. Index Terms--Active rectifiers, multilevel converters, predictive control, pulsewidth modulation (PWM).

This paper is concerned with the study of a single-phase boost-type three-level rectifier. The converter is supposed to present high input power factor, low current harmonics, low total harmonic distortion, and simple control scheme. In order to minimize switching losses, a passive nondissipative snubber is associated with the aforementioned converter. The theoretical analysis, design procedure, and analytical results regarding a 1.2-kW prototype are presented to validate the proposal. Index Terms--Power-factor correction (PFC), soft switching, three-level rectifiers.

This paper presents a single-phase soft-switched high power factor (PF) Sheppard-Taylor rectifier suitable for applications requiring low-voltage and high-current output. The proposed rectifier is designed to operate at discontinuous capacitor voltage mode. The Sheppard-Taylor converter in this mode of operation provides zero-voltage turnoff switching, as well as natural input PF correction over a wide range of input voltage, which makes the converter suitable for universal input applications. Due to its simplified control circuitry and reduced switch current stress, this converter presents better efficiency and higher reliability. In addition, the presented converter features continuous input-output currents, which result in low electromagnetic interference emission. Principle of operation, theoretical analysis, and experimental results from a laboratory prototype rated at 45 W/ 10 Vdc output voltage are presented. The measured efficiency and total harmonic distortion of the input line current were 85% and 3.2%, respectively. The input current harmonics meet the EN61000-3-2 Class D requirements. Index Terms--Current harmonics, discontinuous conduction mode (DCM), electromagnetic interference (EMI), power factor correction (PFC), power supplies, rectifier, zero-voltage switching (ZVS).

A three-phase buck + boost pulsewidth modulation (PWM) rectifier with a three-switch buck-type rectifier input stage and an integrated dc/dc boost converter output stage, and a three-phase boost + buck PWM rectifier system formed by series connection of a boost-type rectifier input stage (Vienna Rectifier) and a dc/dc buck converter output stage are presented and comparatively evaluated. Both systems are characterized by sinusoidal input current and wide output voltage control range. The comparison is for 6 kW rated output power at 400 Vrms line-to-line input and variable output voltage 200 V,..., 600 V and identifies the buck + boost approach as significantly superior regarding the overall efficiency, the volume and weight of the passive power components, and the overall system complexity. Index Terms--System efficiency, three phase pulsewidth modulation (PWM) rectifiers, wide output voltage range.

Current sharing among inductors is an important issue in both isolated and nonisolated dc-dc converters. In this paper, average current sharing is in-depth modeled and analyzed for both interleaved multiphase buck converters and isolated current-doubler dc-dc converters. The features and comparison of various current-sharing techniques used in isolated and nonisolated dc-dc converters are presented, and the corresponding design guidelines are provided based on the theoretical analysis. The analysis reveals that the state-of-the-art current-sharing technique for multiphase buck converters cannot be directly applied to isolated currentdoubler rectifier (CDR) dc-dc converters to achieve balanced inductor currents. Passive and active current-sharing methods are proposed for isolated current-doubler dc-dc converters to balance two inductor currents. Experimental results are presented to verify the modeling analysis and the proposed current-sharing techniques for CDRs in isolated dc-dc converters. Index Terms--Converter, current doubler, current sharing, dc-dc, interleaving, rectifier, synchronous rectifier.

Parallel operation of three-phase power-factor-corrected (PFC) rectifiers is a critical issue for high-power applications, since it extends the power range to a much higher level and allows modular design. The technical challenges are current sharing and circulating current control among the modules. This paper studies these phenomena within two paralleled rectifiers and proposes a new current-sharing method based on One-Cycle Control (OCC) with vector operation and bipolar operation. With some minor additions to the original OCC circuit and a simple add-on communication path among the individual modules, the input current is shared and the circulating current is limited, while the OCC advantages, such as constant switching frequency, no multipliers, and simple circuitry, are preserved. Two OCC PFC rectifiers of 2.5 kW each were built and tied together using the proposed parallel operation method. Experiments have demonstrated the simplicity and the effectiveness of this method. Index Terms--Circulating current, current sharing, one-cycle control (OCC), parallel rectifier, power factor correction (PFC), vector operation.

Connecting three-phase rectifier systems in parallel shows many advantages as compared to a single rectifier system with higher output power, such as higher reliability, smaller current and voltage ripple components, lower filtering effort, or higher system bandwidth. However, current unbalance or circulating currents can occur for modular design. In this paper, the parallel connection of two three-phase three-switch bucktype unity-power-factor pulsewidth-modulation rectifier systems is experimentally investigated for a 10-kW digital-signalprocessor-controlled prototype. A space vector modulation scheme is employed showing all the advantages of an interleaved operation. Three control schemes for active dc-link current balancing are described employing an additional free-wheeling state that allows to influence the rate of change of the dc-link currents and can therefore be used for dc-link current balancing. The control schemes differ concerning control action and additional switching losses. Simulation and experimental results confirm the theoretical considerations: The dc-link current-balancing capability of the different control methods is compared, and the influence of the additional free-wheeling state on switching losses and operation behavior is investigated. The most advantageous control method, which employs a hysteresis controller and shows limited switching losses, is selected. The analysis of the mains behavior shows an improvement as compared to a single rectifier operation. Index Terms--Buck rectifier, circulating current, current balancing, parallel three-phase rectifiers, power factor correction, pulsewidth modulation (PWM).

This paper presents an improved analysis of a novel Programmable Power-factor-corrected-Based Hybrid Muitipulse Power Rectifier (PFC-HMPR) for utility interface of power electronic converters. The proposed hybrid multipuise rectifier is composed of an ordinary three-phase six-pulse diode-bridge rectifier (Graetz bridge) with a parallel connection of single-phase switched converters in each three-phase rectifier leg. In this paper, the authors present a complete discussion about the controlled rectifiers' power contribution and also a complete analysis concerning the total harmonic distortion of current that can be achieved when the proposed converter operates as a conventional 12-pulse rectifier. The mathematical analysis presented in this paper corroborate, with detailed equations, the experimental results of two 6-kW prototypes implemented in a laboratory. Index Terms--AC motor drives, high power drives for trolley-bus systems, high power factor three-phase rectifiers, multipulse rectifiers, tractions applications, 12-pulse rectifiers.

This paper calculates and compares the efficiency and loss distribution in the three most popular state-of-the-art types of large motor drive systems: 1) current-source drive with active front-end rectifier; 2) current-source drive with 18-pulse thyristor rectifier; and 3) three-level voltage-source drive with 12-pulse/24-pulse diode rectifier. For converter systems with efficiencies better than 90%, it is suggested to calculate or measure the losses of all the components separately and add them up to calculate the total efficiency. A simple and accurate method of calculating switching losses for a current-source and voltage-source converter is proposed. Through the calculation and simulation of each loss factor such as switching losses, conduction losses, and snubber and filter losses, the three-level voltage-source drive system has been found to have the highest efficiency of 98.77% under the rated load of 1.6 MW. Index Terms--AC motor drives, multilevel systems, pulsewidth-modulated inverters, solid-state rectifiers.

In this paper, an efficient current distortion suppression method for six-pulse bridge rectifiers is presented, whereby high-quality waveforms at both ends of the rectifier are possible. The methodology involves accurate shaping of the dc current by using two forced commutated switches. It is demonstrated, theoretically and experimentally, that this action on the dc side is reflected back on the ac side, and as a result, perfect sinusoidal input currents are achieved. In addition, ripple-free voltages and currents are obtained on the dc side by using electrolytic capacitors and smoothing reactors. Rectifying and inverting operations are possible with a simple control circuit, which is also able to both track rapid load variations and overcome failures more efficiently than other modern alternatives. Selected theoretical results are presented, which are fully validated in a laboratory prototype. Index Terms--Power quality, power systems harmonics, rectifiers.

This paper presents a new practical formula to calculate the critical value of interphase reactor (IPR) in a six-phase diode rectifier with tap-changer. In addition, a mathematical model of the double-tap IPR has been established by equivalent circuit method. Simulation and experimental results verify the validity of the formula and mathematical model. On the basis of the above achievements, a simple and effective approach is provided to design the IPR and to analyze the performance of the whole system. Index Terms--Critical formula, interphase reactor, mathematical model, six-phase diode rectifier, tap-changer.

A new multiple-coupled inductor (MCI) is proposed for good cross regulation among low output voltages, high power density, and reduced converter volume. Moreover, a current doubler rectifier and a self-driven synchronous rectifier are presented to achieve high efficiency. The structure of the MCI is composed of four windings on a common core, and has the properties of a current doubler and good cross regulation. A dc-dc half-bridge converter using the proposed MCI is analyzed and designed for 40-W low output voltages (3.3, 4.5 V). This converter is very suitable for high current and low voltage applications. It is shown via experimental results that efficiency of over 90 % and cross regulation of about 5 % are achieved. Index Terms--Cross regulation, current doubler rectifier, multiple-coupled inductor (MCI), synchronous rectifier.

A mathematical model of two-mass vibratory conveying system with electromagnetic vibratory actuator (EVA) and possible ways of their optimal control by using power converter is presented in this paper. Vibratory conveyors are commonly used in industry to carry a wide variety of particulate and granular materials. Application of electromagnetic vibratory drive combined with power converters provides flexibility during work. The use of a silicon-controlled rectifier (SCR) implies a phase angle control, which is very easy, but with many disadvantages (fixed frequency which is imposed by ac mains supply, poor power factor, mechanical retuning, etc.). Switching converters overcomes these disadvantages. Only then, driving for EVA does not depend on mains frequency. As well as amplitude and duration of excitation force tuning, it is also possible to tune its frequency. Consequently, complicated mechanical tuning is eliminated and seeking resonant frequency is provided. Previously mentioned facts motivated phase angle control and switch mode control behavior research for electromagnetic vibratory drives. Simulation and experimental results and their comparisons are exposed in this paper. The simulation model and results are given in the program package PSPICE. Experimental results are recorded on implemented control systems for SCR and transistor power converters. Partial results concerning the resonant frequency seeking process with transistor converter are also exposed. Index Terms--AC-DC power conversion, actuators, conveyors, current control, phase control, resonance, silicon-controlled rectifier (SCR), switching circuits.

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching (ZVS) in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved because of the following reasons: 1) the circulating current for the soft switching flows only through the auxiliary circuit; 2) a minimum number of switching devices are involved in the circulating current path; and 3) the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM-switch model is used to predict the system performance. A prototype rated at 1 kW, operating at 60 kHz, with an input alternating current voltage of 220 [V.sub.rms] and an output voltage of 400 [V.sub.dc], has been implemented in laboratory. An efficiency of 98.3% and a power factor over 0.99 have been measured. Analysis, design, and the control circuitry are also presented in this paper. Index Terms--Rectifier, state-space averaging approach, zero-current switching (ZCS).

This paper proposes a new three-phase diode rectifier that actively shapes the input current by means of two direct current dc-dc converters operating at continuous conduction mode. The proposed approach draws sinusoidal input current at unity power factor and has output voltage regulation capability. The size and weight of the magnetic devices is reduced since a low-kilovolt-ampere three-phase autotransformer is incorporated and dc outputs of two bridges are directly connected without using low-frequency interphase transformers (IPTs). Index Terms--Active waveshaping, autotransformer, diode rectifier, harmonic mitigation, three-phase power-factor correction.

Current-source rectifiers (CSRs) constitute a commonly used topology in high-power applications, featuring several advantages such as regeneration capability and high-quality currents. This paper presents a simple predictive control scheme for a CSR. The main achievements of the control scheme presented here are the simplicity in controlling the dc-link current and the generation of currents with unity displacement power factor. Experimental results are presented to validate the proposed control principle. Index Terms--AC-DC power conversion, current control, current-source rectifier (CSR).