G.H. Rim

Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter using transformer auxiliary winding

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high power (>1 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz IGBT based experimental circuit.

Zero-voltage-transition isolated PWM boost converter for single stage power factor correction

A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented. A simple auxiliary circuit added in the secondary rectifier side provides zero-voltage-switching (ZVS) condition to all semiconductor devices without increasing additional device voltage and current stresses. The proposed converter gives both input power factor correction and direct conversion from AC line to DC output, which leads to high efficiency and high power density conversion. Operation principle, analysis, and features of the proposed converter are presented and verified by the computer simulation and experimental results from a 1.5 kW, 80 kHz laboratory prototype.

An improved zero voltage and zero current switching full bridge PWM converter with secondary active clamp

An improved zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to solve the problems of the previously presented ZVZCS-FB-PWM converter with secondary active clamp such as narrow ZVS range of leading-leg switches. By adding an auxiliary inductor in between the leading-leg and separated input source voltages, the ZVS of leading leg switches can be extended to the whole line and load ranges, which eliminates unwanted hard switching of clamp switch and simplifies its control. The principle of operation is explained and analyzed. The features and design considerations of the proposed converter are also illustrated and verified on a 3 kW, 100 kHz IGBT based experimental circuit.

A choppingless converter for switched reluctance motor with unity power factor and sinusoidal input current

This paper describes a new converter topology for switched reluctance motor drives. The new topology consists of a pair of boost-buck power converters and a machine converter. The boost converter lets the system deliver sinusoidal input current and enhances the DC source voltage having the capability of fast current rise/decay of the stator windings. It also provides DC voltage regulation. The buck converter is used to regulate the DC source voltage responding to the motor speed variations. The wide pre-voltage regulation by the two power conversion stages eliminates the high voltage-choppings to control the stator winding currents. This enables the machine-drive converter to work in single pulse-current mode, hence, removing the switching losses.<<ETX>>

Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter with low output current ripple

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter with low output current ripple is presented. A simple auxiliary circuit added in the secondary provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches, as well as reducing the output current ripple (ideally zero ripple). The auxiliary circuit includes neither lossy components nor additional active switches which are demerits of the previously presented ZVZCS converters. Many advantages including simple circuit topology, high efficiency, low cost and low current ripple make the new converter attractive for high performance high power (>1 kW) applications. The principle of operation, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz IGBT based experimental circuit.

A 12 kW switching mode power supply with free input-voltage

Phase-controlled AC to DC power conversion has the disadvantages of low power factor and harmonic pollution on the utility side, particularly in the case where DC voltage regulation is required. This paper presents a 12 kW switching mode power supply for a telecom power system. The scheme employs a buck-type power converter in the front-end resulting in high input power factor and less harmonics to the utility. A two-loop controller with a feedback and a feedforward loop is used to minimize the effects of the rectified ripple voltages and to improve the system dynamics. Since it also has a very wide input-voltage range, it can be directly applied for both the input systems of AC 220 V and 380 V.<<ETX>>

A 100 kVA power conditioner for three-phase four-wire emergency generators

A 100 kVA power conditioner for three-phase four wire emergency generators is presented to compensate current harmonics and asymmetries caused by nonlinear and/or unbalanced loads. Three-phase voltage type converter with split-dc-capacitor is adopted as the power circuit and a new direct source current control method is suggested, which simplifies the controller. The proposed power conditioner shapes the generator current sinusoidally inphase with the voltage and allows the generator to supply maximum power even to single phase loads. An IGBT based 100 kVA prototype with the controller realized with a DSP (TMS320C32) is built and tested to verify the performance of the power conditioner.

Novel zero-voltage-transition isolated PWM boost converter for single stage power factor correction

A novel zero-voltage-transition (ZVT) isolated PWM boost power converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT power converter. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices (two active switches are required for the previous ZVT converter). This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 kHz laboratory prototype.

Wireless parallel operation of high voltage DC power supply using steady-state estimation

This paper presents an improved droop method, which minimizes the voltage droop of a parallel-connected power supply. Conventionally, the droop method has been used to achieve a simple structure and no-interconnections among power sources. However, it has a trade-off between output voltage regulation and load sharing accuracy. In this paper, the droop is minimized with a current and droop gain control using steady-state estimation. The proposed method can achieve both good voltage regulation and good load sharing. A design example of two 10 kV, 100 mA parallel modules are made and tested to verify the proposed current sharing method.