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In this paper, a single-inductor dual-output (SIDO) dc–dc converter is proposed. The significant feature of the proposed converter is feeding a constant power load in low-voltage side (LVS) port, where even feeding a variable load at LVS does not have any cross regulation to high-voltage side port with the desired approximation. Magnificently, both merits are obtained in open-loop manner, which is an outstanding characteristic in comparison with that of the existed converters. In this paper, soft commutation and soft switching of switches and diodes are investigated along with the aforementioned main novelty. Moreover, detailed theoretical analyses of the proposed SIDO dc–dc converter in continuous conduction mode are presented besides the comparisons with some other structures. Finally, theoretical analyses are verified through a 1500 W experimental prototype results. [ABSTRACT FROM AUTHOR]

In this paper, a new nonisolated high step-down dc–dc converter with ultrahigh step-down conversion ratio is proposed. Advantages of the proposed converter are high step-down ratio, extended duty cycle, reduced switching losses by a converter operation under zero-voltage switching (ZVS) conditions, reduced reverse reco-very losses of diodes by achieved zero-current switching turn-off condition, and reduced voltage spikes by the inherent active-clamping structure of the converter. In this converter, series capacitors and coupled inductors have been used in power path to achieve the low voltage gain and extended duty cycle. By the inherent active-clamping structure of the proposed converter, the leakage inductance energy is totally recovered in the output; therefore, the high voltage spike across the semiconductor devices is suppressed. The switches of the proposed converter can operate under ZVS conditions, which cause reduced switching losses and improved efficiency. In this paper, the converter operating modes are discussed, and a prototype circuit is implemented. Experimental results are presented to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of nonisolated boost dc–dc converters based on voltage-lift technique is proposed. In comparison with conventional nonisolated boost dc–dc converters, the proposed converter generates higher voltage gain. In this paper, the relations between voltage and current of all elements in continuous conduction mode and discontinuous conduction mode are calculated as well as voltage gain in each mode. Then, the critical inductance and stress of switch current are extracted. Finally, the validity of given theories is examined by using the experimental results. [ABSTRACT FROM PUBLISHER]

This paper proposes an analytical design procedure for the LLCL and the LCCL filters for grid integration of high-power voltage-source converters. The low switching frequency and stringent limits on grid-injected harmonics in high-power applications lead to large smoothing filters. In order to reduce the size and weight, high-order filters are already proposed and wise design procedures with the main goal of minimizing the overall filter size are being suggested. In this paper, the parameters of the LLCL and the LCCL filters are designed in the per-unit system to satisfy the requirements on the injected grid current and at the same time minimize the overall filter size through minimizing the total energy stored in the filter components. The experimental results of a downscaled laboratory prototype with a low switching frequency prove the effectiveness of the proposed design procedure. [ABSTRACT FROM PUBLISHER]

This paper proposes two coupled-inductors-based Z-source networks, called the modified series and tapped switched-coupled-inductors quasi-Z-source networks (mSSCL-qZSN and mTSCL-qZSN, respectively). These networks offer high voltage gains with less-than-unity winding turn ratios $(n < {\text{1)}}$ , resulting in a reduced inductive element size. Other advantages include a less number of active components and their lower ratings and a higher efficiency. In addition, a lower magnetic core size is required for the proposed ZSNs due to the lower peak magnetizing current. The performance principles and detailed comparative analysis are provided and confirmed through experiments on a 200-W dc–dc converter. [ABSTRACT FROM AUTHOR]

This paper presents an interleaved current-driven phase-shift full-bridge converter for plug-in hybrid electric vehicle (PHEV) applications. In the proposed converter, soft switching of the active switches can be realized for a wide range of operating conditions by using a simple auxiliary circuit. Due to the current-driven nature of secondary rectifiers, the proposed converter is able to eliminate the voltage spikes across the output diodes and provides smooth commutations for the secondary rectifiers. Thus, diodes with lower breakdown voltage rate and lower forward voltage drop can be used to further improve the efficiency. All the passive magnetic components are integrated into the main transformer. The numbers of the output diodes are minimized because of the voltage doubler rectifier configuration. The input filtering requirements, as well as the current stresses of the switch devices, are also significantly reduced owing to the interleaving approach. Therefore, the proposed converter would be a good candidate for PHEV applications. The steady-state operation and relevant analysis results of the proposed converter are presented. Experimental results obtained from a 2-kW prototype with a peak efficiency of 97.4% validate feasibility of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper proposes a multilevel flying capacitor dc/dc boost converter (FCBC) with a small capacitance of the flying capacitor for the reduction of converter size. In this paper, the design methods for the boost inductor and the flying capacitor in the n-level FCBC are principally and experimentally confirmed. Furthermore, the boost inductor is designed based on maximum product of voltage-time, regardless the number of level. Meanwhile, the minimum capacitance of the flying capacitor is designed based on the maximum switching device voltage stress, regardless of the output voltage ripple influences. Moreover, the achieved maximum efficiency of the designed three-level FCBC is 98.5% at the output power of 1 kW. Finally, the effectiveness of small capacitances of the flying capacitor in the three-level and five-level FCBCs is analyzed. The characteristics of the distorted voltage across the input voltage source and the boost inductor, and the distorted current to the output side (output capacitor and load) are investigated with several capacitances of the flying capacitors in the three-level and five-level FCBCs. As a result, it is experimentally confirmed that the distorted voltage is drastically reduced by increasing the number of level. Besides, the distorted current is almost the same although the number of level is increased. Therefore, based on the experimental results, it is shown that small capacitance of the flying capacitor can be used in the n-level FCBC without compromising the stability of converter operation. [ABSTRACT FROM PUBLISHER]

Impedance networks have been already investigated in various literature with the main goals of increasing the attainable voltage gain and reducing the components number. Recently, coupled inductors found popularity because they let converters with lower weight and cost. It seems that coupled inductances are a proper answer to the increasing voltage gain while keeping down the components number. This paper proposes a novel impedance network circuit based on three coupled inductors with a Δ connection. The proposed Δ-source converter offers smaller magnetizing current and winding losses compared to the successful Y-source circuit. Moreover, with the Δ-connected three coupled inductors, the adverse effect of leakage inductance on the converter performance is significantly reduced. The effectiveness of the proposed structure is analytically proved. The theoretical achievements over the conventional Y-source structure are confirmed through extensive simulations and experiments. [ABSTRACT FROM PUBLISHER]

A simple current-feed single-switch forward resonant converter with secondary diode-clamping is proposed for low-power high-density bus converter applications in this paper. The quasi-zero-voltage-switching turn-on and quasi-zero-current-switching (ZCS) turn-off for switch are both achieved. Due to the quasi-ZCS turn-off , the high voltage spike in traditional single forward converter with a reset winding is much reduced. A small diode connected to the output capacitor is utilized to clamp the voltage stress of the switches. The operating principle of the proposed converter is analyzed and a MHz 66 W 24 V-to-12 V prototype with all Si devices is built up. Experimental results show good soft-switching features, and the prototype achieves 95.3% peak efficiency with 270 W/in3 power density. [ABSTRACT FROM PUBLISHER]

In this paper, a new common inductor current sharing method is proposed for a multiphase LLC resonant converter for high-power applications. Automatic current sharing is achieved by using a common resonant inductor connecting the resonant inductors in each LLC phase in parallel. The current sharing performance of the proposed method is evaluated under first harmonic approximation (FHA) assumption. The proposed method can automatically share the primary resonant current and the load current for all phases without any additional circuit and control strategy. A 600-W two-phase LLC converter prototype based on the proposed method is built to verify the feasibility. Excellent current sharing performance (less than 0.5% current sharing error at full load) has been achieved. [ABSTRACT FROM PUBLISHER]

Single-phase power factor correction (PFC) ac–dc converters are widely used in the industry for ac–dc power conversion from single phase ac-mains to an isolated output dc voltage. Typically, for high-power applications, such converters use an ac–dc boost input converter followed by a dc–dc full-bridge converter. A new ac–dc single-stage high-power universal PFC ac input full-bridge, pulse-width modulated converter is proposed in this paper. The converter can operate with an excellent input power factor, continuous input and output currents, and a non-excessive intermediate dc bus voltage and has reduced number of semiconductor devices thus presenting a cost-effective novel solution for such applications. In this paper, the operation of the proposed converter is explained, a steady-state analysis of its operation is performed, and the results of the analysis are used to develop a procedure for its design. The operation of the proposed converter is confirmed with results obtained from an experimental prototype. [ABSTRACT FROM PUBLISHER]

During the design phase of a modular multilevel converter (MMC), an accurate loss evaluation of the submodule (SM) plays an important role. In this paper, a method based on the analytical description of the MMC key waveforms that allows to directly obtain the average semiconductor and capacitor losses that each SM will experience is introduced, under different operating conditions or control schemes. To verify the proposed concept, the results are compared with the losses obtained from a switched model with closed-loop control, where the analytical MMC key waveforms are approached in steady state. The proposed method provides a great flexibility and a significant reduction of the simulation/computational time otherwise needed to evaluate SM losses under various operating conditions. [ABSTRACT FROM PUBLISHER]

A novel isolated dc–dc converter is proposed, using the T-Type topology with zero voltage switching and pulse width modulated with a capacitive output filter. It uses four switches, two of which are subjected to the input voltage, and the other two to half the input voltage. All switches commutate under zero voltage over a wide load range. The proposed converter has the following features: (a) symmetrical operation of the isolation transformer, (b) modulation by pulse width with constant frequency, (c) zero voltage switching, and (d) three-level voltage applied to the primary winding of the transformer. Theoretical analysis, design example, and experimental data for a 2 kW, 400 VDC input, 400 VDC output, and 50 kHz switching frequency laboratory prototype, working in two operating points are included in this paper. The measured efficiency was 95% at 950 W. [ABSTRACT FROM AUTHOR]

In this paper for power factor correction (PFC), a modified Landsman converter is introduced. The application is targeted for high-brightness (HB) projection application with brightness control for HB red–green–blue (HB-RGB) light-emitting diode (LED). A pulse-width modulation (PWM) technique is used for intensity control to achieve brightness control of the LED driver. The proposed PFC converter is used to feed a dual output flyback dc–dc converter that supplies power to the forced cooling unit and the LED module with galvanic isolation. The brightness control of LED is performed by synchronous buck converter. The modified Landsman converter operates in discontinuous output inductor current mode for PFC at universal ac mains. A prototype of the proposed LED driver is experimentally verified. The performance of proposed driver is evaluated at full and light-load condition for universal ac mains (90–265 V) over a full range of brightness. The power quality parameters are found within the acceptable limits of harmonic standard IEC 61000-3-2 for universal ac mains. [ABSTRACT FROM PUBLISHER]

A new low-power single-stage ac-dc converter is proposed in the paper. The outstanding feature of the converter is that it can operate with a sinusoidal input current and a low primary-side dc bus voltage that is much less variable than that found in other single-stage converters. The operation of the converter is discussed in the paper and its various modes of operation are explained in detail. An analysis of the converter's steady-state characteristics is performed and the results are used in the design of the converter. Experimental results obtained from a prototype converter are also presented. [ABSTRACT FROM AUTHOR]

In this paper, a built-in voltage gain extension cell is proposed to give a universal topology derivation on next-generation high step-up converters for large voltage gain conversion systems. Several improved single-switch high step-up converters with built-in transformer voltage multiplier cell are derived with some advantageous performance, which includes extremely large voltage conversion ratio, minimized power device voltage stress, effective diode reverse-recovery alleviation, and soft-switching operation. The turns ratio of the built-in transformer can be employed as another design freedom to extend the voltage gain, which shows great design flexibility. Compared with their active clamp counterpart, only one MOSFET is required to simplify the circuit configuration and improve the system reliability. The over resonance frequency and the below resonance frequency operation modes are studied to explore the circuit performance, and the key parameter design criterion is provided to show a valuable guidance for future industrial applications. Finally, the experimental results from a 500 W 36-380 V prototype are provided to validate the effectiveness of the main contributions in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a novel high step-up dc–dc converter with a multicoupled inductor (MCI) and voltage multiplier is proposed for a sustainable energy system. The combinatorial employment of these components significantly extends the voltage boostability and reduces the voltage stress of the main switches. The special structure of branch cross coupling makes the two branches of current autobalance. Meanwhile, the utilization of MCIs makes the most of the magnetic core to further improve the power density. The diode reverse-recovery problem is alleviated because its current falling rate is controlled by the leakage inductance of the MCI. Moreover, the voltage spike of the main switches at their turn-off is clamped by a clamp capacitor. The interleaved operation results in the cancelation of the input current and output voltage. Next, the operating principle and performance of the converter are discussed in detail. Finally, a prototype circuit with 1-kW output power is implemented to verify the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a simple control method of the half-bridge (HB) LLC converter with one additional switch and capacitor in the primary side is proposed for wide-input-voltage applications with the hold-up time conditions. At nominal input, since the proposed method enables the HB LLC converter to operate with large transformer magnetizing inductance, it can reduce the conduction and switch turn-off losses in the primary side, which makes it highly efficient. On the other hand, during the hold-up time, since the proposed method increases the resonant capacitance by turning on one additional switch, the HB LLC converter can obtain high-voltage gain. To confirm the validity of the HB LLC converter with the proposed method, a 325–385 V input and 56 V/350 W output laboratory prototype is built and tested. [ABSTRACT FROM PUBLISHER]

In this paper, an integrated double buck–boost (IDBB) converter is proposed as a high-power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design methodology is proposed. It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used. In this way, the converter mean time between failures can be made as high as that of the solid-state lamp. A design example for a 70-W converter supplied from a 230 V/50 Hz mains for street lighting applications is shown. Finally, experimental results from a laboratory prototype are also presented. [ABSTRACT FROM AUTHOR]

This paper presents an efficient single-switch boost-dual-input flyback power factor correction (PFC) converter. To achieve a high power factor, a boost PFC cell operating in discontinuous conduction mode is presented. A dual-input flyback dc–dc module, which consists of parallel primary windings and serial secondary windings, operating in critical conduction mode is introduced for galvanic isolation and valley-switching operation. In addition, the proposed converter features high efficiency because the input power is equally divided, and some power is directly transferred to the load by the dual-input flyback dc–dc module. The remaining power is stored in dc-bus capacitors, and it is closely related to the holdup time. Moreover, the currents in the leakage inductors are absorbed by the dc-bus capacitors through a snubber diode, and they are reprocessed by the dual-input flyback dc–dc module. Consequently, the peak voltage in the MOSFET drain is clamped, and the total power conversion efficiency is improved. To verify the performance of the proposed converter, the operating principles, steady-state analysis, and experimental results from a 48 V, 100 W prototype are presented. [ABSTRACT FROM PUBLISHER]

This paper presents a novel microinverter for a single-phase grid-connected photovoltaic (PV) system. The proposed microinverter consists of a step-up dc–dc converter using an active-clamp circuit with a series-resonant voltage doubler and a high-efficiency inverter with single-switch-modulation step-down converters. The active-clamp circuit provides zero-voltage switching (ZVS) turn-on, recycles the energy stored in the leakage inductance of the transformer, and limits switch voltage stress. Moreover, to remove the reverse-recovery problem of the rectifier diodes, a series-resonant voltage doubler is used. Thus, this whole process provides high efficiency. To improve efficiency and reliability in the proposed inverter, only a single switch is modulated at the switching frequency without a shoot-through problem. A modified controller is also adopted to achieve fast output control. Thus, the proposed PV microinverter has the structure to minimize power losses. The experimental results show a maximum efficiency of 96.2% for a 400-W microinverter. [ABSTRACT FROM PUBLISHER]

An energy regenerative passive snubber for transformer isolated converters is proposed. The snubber is implemented on the transformer's primary and secondary windings. The proposed snubber significantly reduces the voltage spike across the switch caused by the transformer's primary inductance upon switch turn-off and facilitates the fast ramping up of the transformer secondary current. In addition, the proposed snubber provides lossless zero voltage turn off and zero current turn on conditions for the power switch. Experimental example of a flyback converter has shown measured efficiency exceeding 90%. This paper describes the principle of operation and presents approximate theoretical analysis and design guidelines of the proposed snubber. Simulation and experimental results are also reported. The proposed energy regenerating snubber is best suited for flyback and SEPIC converters and can also be adapted to other transformer isolated topologies. [ABSTRACT FROM AUTHOR]

In this paper, the built-in transformer voltage multiplier cell is inserted into each phase of the conventional interleaved boost converter to provide additional control freedom for the voltage gain extension without extreme duty cycle. The voltage multiplier cell is only composed of the built-in transformer windings, diodes and small capacitors. And additional active switches are not required to simplify the circuit configuration. Furthermore, the switch voltage stress and the diode peak current are also minimized due to the built-in transformer voltage multiplier cells to improve the conversion efficiency. Moreover, there is no reverse-recovery problem for the clamp diodes and the reverse-recovery current for the regenerative and output diodes are controlled by the leakage inductance of the built-in transformer to reduce the relative losses. In addition, the switch turn-off voltage spikes are suppressed effectively by the ingenious and inherent passive clamp scheme and zero current switch (ZCS) turn-on is realized for the switches, which can enhance the power device reliability. Finally, a 40 V-input 380 V-output 1 kW prototype is built to demonstrate the clear advantages of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a single-phase high step-up converter is proposed, designed not only to boost the relatively low photovoltaic (PV) voltage to a high bus voltage with high efficiency, but also to offer a neutral point terminal for the half-bridge-based inverters. First and foremost, two symmetrical high step-up converters are combined and integrated to derive an improved converter with neutral point terminal, which is strongly expected for the half-bridge-based inverters. Secondly, the voltage gain of the converter is extended and the narrow turn-off period is avoided by using the coupled inductor multiplier. Furthermore, the coupled inductor multiplier reduces the voltage stress of all the power devices. As a result, the low voltage-rated power devices can be employed to minimize the conduction losses. More importantly, all the active switches work in the zero-voltage-switching condition, which reduces the switching losses effectively. All these factors improve the circuit performance in the high step-up applications, especially for the half-bridge based PV inverter systems. Finally, the experimental results from a 500 W, 48 -760 V prototype at 100 kHz switching frequency are provided to verify the effectiveness of the proposed converter. The highest efficiency of the prototype is 96.5% and the efficiency is over 94% in a wide load range. [ABSTRACT FROM AUTHOR]

The interleaving technique is necessary for LLC resonant converters to achieve high power level. The advantages include expanded power capacity, lower output ripple current, and higher light-load efficiency by using phase shedding. However, conventional frequency-controlled LLC converters will lose regulation in individual phases if all the phases are operating at the same switching frequency, causing load sharing problem. Existing load sharing solutions for interleaved LLC converters all have limitations. In this paper, a switch-controlled capacitor (SCC) modulated LLC converter (SCC-LLC) is presented to solve the load-sharing problem. With constant switching frequency, interleaving and phase shedding can be achieved. A 600-W, two-phase interleaved constant frequency SCC-LLC prototype is built to verify the feasibility and demonstrate the advantages. [ABSTRACT FROM AUTHOR]

In this paper, the concept of built-in transformer voltage doubler cell is derived to generate an improved interleaved high step-up converter for distributed photovoltaic generation applications. The proposed built-in transformer voltage doubler cell is composed of three transformer windings, two voltage doubler diodes, and two voltage doubler capacitors. The voltage doubler capacitors are charged and discharged alternatively to double the voltage gain. The switch duty cycle and the transformer turns ratio can be employed as two controllable freedoms to lift the voltage ratio flexibly. The power device voltage stress can also be reduced to improve the circuit performance. Furthermore, the active clamp scheme is adopted to recycle the leakage energy, absorb the switch turn-off voltage spikes, and achieve zero-voltage switching (ZVS) operation for all active switches. Meanwhile, the diode reverse-recovery problem is alleviated by the leakage inductance of the built-in transformer. All these factors benefit the circuit performance improvements in the high step-up and large current applications. Finally, a 1-kW prototype with 40-380 V conversion is built and tested to demonstrate the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper presents a high step-down tranformerless single-stage single-switch ac/dc converter suitable for universal line applications (90-270 Vrms) . The topology integrates a buck-type power-factor correction (PFC) cell with a buck-boost dc/dc cell and part of the input power is coupled to the output directly after the first power processing. With this direct power transfer feature and sharing capacitor voltages, the converter is able to achieve efficient power conversion, high power factor, low voltage stress on intermediate bus (less than 130 V) and low output voltage without a high step-down transformer. The absence of transformer reduces the component counts and cost of the converter. Unlike most of the boost-type PFC cell, the main switch of the proposed converter only handles the peak inductor current of dc/dc cell rather than the superposition of both inductor currents. Detailed analysis and design procedures of the proposed circuit are given and verified by experimental results. [ABSTRACT FROM AUTHOR]

In this paper, A single-phase improved active clamp coupled-inductor-based converter with extended voltage doubler cell is proposed for large-voltage conversion ratio applications. The secondary winding of the coupled inductor is inserted into the half-wave voltage doubler cell to extend the voltage gain dramatically and decrease the switch voltage stress effectively. By combining the coupled inductor and voltage doubler cell structure, the disadvantage of the potential resonance between the leakage inductance and the diode stray capacitor is cancelled, and the unexpected high pulsed current in the voltage doubler cell is decreased due to the inherent leakage inductance of the coupled inductor. Meanwhile, the active clamp scheme is employed to recycle the leakage energy, suppress the switch turn-off voltage spikes, and implement zero-voltage-switching turn-on operation. In addition, there is only one magnetic component in the proposed converter and the coupled inductor operates not only as a filter inductor, but also as a transformer when the main switch is in the ON state, which reduces the volume of the magnetic core and improves the power density of the converter. A 500 W prototype operating at 100 kHz with 48 V input and 380 V output is built to verify the analysis. The maximum efficiency of the prototype is nearly 97% and the efficiency is higher than 96% over a wide load range. [ABSTRACT FROM AUTHOR]

A soft-switching single-ended primary inductor converter (SEPIC) is presented in this paper. An auxiliary switch and a clamp capacitor are connected. A coupled inductor and an auxiliary inductor are utilized to obtain ripple-free input current and achieve zero-voltage-switching (ZVS) operation of the main and auxiliary switches. The voltage multiplier technique and active clamp technique are applied to the conventional SEPIC converter to increase the voltage gain, reduce the voltage stresses of the power switches and diode. Moreover, by utilizing the resonance between the resonant inductor and the capacitor in the voltage multiplier circuit, the zero-current-switching operation of the output diode is achieved and its reverse-recovery loss is significantly reduced. The proposed converter achieves high efficiency due to soft-switching commutations of the power semiconductor devices. The presented theoretical analysis is verified by a prototype of 100 kHz and 80 W converter. Also, the measured efficiency of the proposed converter has reached a value of 94.8% at the maximum output power. [ABSTRACT FROM AUTHOR]

In this paper, a new zero-current switching pulse width modulation forward converter is introduced using a new switching algorithm for the auxiliary circuit. In the proposed converter, transformer core is reset through a resonance, and thus, reset winding is not required which is the main advantage of this converter over existing zero-current switching forward converters. The simple auxiliary circuit of this converter is just composed of an auxiliary switch and a capacitor that provides zero-current switching for the main switch and also resets the transformer core. Furthermore, the proposed auxiliary circuit uses the leakage inductance of the transformer for the resonant inductor and does not require any additional inductor which is another advantage of the proposed converter over conventional zero-current switching forward converters. Also, the auxiliary switch is soft switched. The proposed converter is analyzed and design procedure of the auxiliary circuit is discussed. The presented experimental results confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

A novel winding-coupled bidirectional dc/dc converter with zero-voltage-switching (ZVS) performance is proposed in this paper. In the low-voltage side, the parallel configuration is employed to share the large current and reduce the current ripple. In the high-voltage side, the series structure is adopted to sustain the high bus voltage and achieve large voltage ratio conversion. There are only two coupled inductors in the proposed interleaved bidirectional converter and their secondary windings are in series to serve as winding-coupled inductors. Furthermore, the two winding-coupled inductors can be integrated into a magnetic core to reduce the passive component numbers and improve the power density. Moreover, ZVS soft-switching operation is implemented for all the power switches to minimize the switching losses by introducing the active clamp scheme. In addition, the pulsewidth modulation plus phase-shift control strategy is employed to reduce the power MOSFET peak current and diminish the circulating losses. The duty cycle is applied to balance the voltages of both sides. The phase-shift angle is introduced to realize the power flow regulation. This decoupling control strategy is advantageous for bidirectional dc/dc conversion to realize high efficiency. Finally, a 1-kW prototype is built to verify the effectiveness of the proposed circuit. [ABSTRACT FROM AUTHOR]

Capacitor charging power supply (CCPS) is a developed technology that utilizes resonant converters topology for high power applications. This paper proposes new a capacitor charging power supply using leg-rotation control method within a phase-shifted PWM full-bridge dc/dc converter. The capacitor charging power supply was connected in series to increase output voltage. Also, the proposed system is designed with soft switching techniques in order to achieve high efficiency, and a leg-rotation control method was used to reduce the heat generated from the IGBTs. The operation of the converter and design methodology will be described. A simplified model of a high-voltage high-frequency transformer is given and the structure is designed to decrease high-voltage stress. The validity of the proposed system is then verified by experimental results. The performance test of the capacitor charging power supply was carried out with a 2 μF capacitive load with a 20 kV output voltage. [ABSTRACT FROM AUTHOR]

This paper presents operational data and parameters of the newest generation of polyphase resonant high voltage converter modulator (HVCM) as developed and delivered to the KAERI 100 MeV "PEFP" accelerator. The KAERI design realizes improvements from the SNS and SLAC designs. The present KAERI system operates two parallel THALES TH2089F 350 MHz klystrons with total power draw of 50 amperes at 105 kV. An additional 3 klystron system operating at 105 kV and 75 A is also being considered for the high energy sections of this accelerator. In these systems, to improve the IGBT switching performance, the HVCMs will be fitted with artificial zero-voltage-switching (ZVS) networks at turn-off. This new method of artificial ZVS should result in a 6 fold reduction of IGBT switching losses. This will improve the HCVM conversion efficiency to better than 95% at full average power, which is 500 kW for the 2 klystron system and 750 kW for the 3 klystron system. The artificial ZVS is accomplished by placing a soft switching capacitor network across the resonant boost transformer primary winding. This low loss snubber circuit reduces the dv/dt across the IGBTs at turn-off. As the transformer input busswork is extremely low inductance (<10 nH), the single network acts like it is across each IGBT collector-emitter terminal of the 4 transistor H-bridge switching network. We will review these topological improvements and the overall system as delivered to the KAERI accelerator with details of the installed operational results. [ABSTRACT FROM AUTHOR]