Jung-Goo Cho

Novel zero-voltage and zero-current-switching full-bridge PWM converter using a simple auxiliary circuit

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulsewidth modulation converter is presented to simplify the circuits of the previously presented ZVSCS converters. A simple auxiliary circuit, which consists of one small capacitor and two small diodes, is added in the secondary to provide ZVZCS conditions to primary switches, as well as to clamp secondary rectifier voltage. The additional clamp circuit for the secondary rectifier is not necessary. The auxiliary circuit includes neither lossy components nor additional active switches, which makes the proposed converter efficient and cost effective. The principle of operation, features, and design considerations are illustrated and verified on a 2.5 kW 100 kHz insulated-gate-bipolar-transistor-based experimental circuit.

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

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (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 (>2 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz insulated gate bipolar transistor (IGBT) based experimental circuit.

Novel zero-voltage-transition PWM multiphase converters

Novel zero-voltage-transition (ZVT) pulse-width-modulation (PWM) multiphase converters are presented. To construct a ZVT multiphase converter in a conventional way, it is necessary to add the auxiliary circuits with as many number of phases. In the proposed converter, only one auxiliary circuit provides the zero-voltage switching (ZVS) for main switches and diodes of all phases. So, the new converters are cost effective and attractive for high-performance and high power-density conversion applications. Operation, features, and characteristics of the two-phase buck converter are illustrated and verified on a 4-kW 100-kHz insulated gate bipolar transistor (IGBT)-based (a MOSFET for the auxiliary switch) experimental circuit.

Novel zero-voltage-transition current-fed full-bridge PWM converter for single-stage power factor correction

A novel zero-voltage-transition (ZVT) current-fed full-bridge pulsewidth modulation (PWM) power converter for single-stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter. A simple auxiliary circuit which includes only one active switch provides a 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 a simplified control circuit compared 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 power converter are presented and verified by the experimental results from a 1.5 kW 100 kHz laboratory prototype.

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.

Reduced conduction loss zero-voltage-transition power factor correction converter with low cost

A new low conduction loss low-cost zero-voltage-transition (ZVT) power factor correction converter (PFC) is presented. The conventional PFC, which consists of a bridge diode rectifier and a boost converter (one active switch), always has three semiconductor conduction drops. The two-switch-type PFC, which was presented recently, reduces conduction loss by reducing one conduction drop, but the cost is increased because of one additional switch. The proposed PFC reduces conduction loss with one switch. Conduction loss reduction is a little bit less than that of the two-switch type, but it is achieved with low cost. Operation, features, and characteristics are comparatively illustrated and verified by the experimental results from a 2.5-kW 100-kHz laboratory prototype.

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.

Novel zero voltage transition PWM multi-phase converters

New zero voltage transition (ZVT) PWM multi-phase power converters are presented. To construct a ZVT multi-phase power converter in a conventional way, it is necessary to add auxiliary circuits-as many as the number of phases. In the proposed power converter, only one auxiliary circuit provides the zero voltage switching (ZVS) for main switches and diodes of all phases. So, the new power converters are cost effective and attractive for high performance and high power density conversion applications. Operation, features and characteristics of a two-phase buck power converter are illustrated and verified on a 4 kW, 100 kHz IGBT based (MOSFET for the auxiliary switch) experimental circuit.

A new integrated controller based 100 kVA mobile engine generator for single/three phase distribution line backup

A new integrated controller based mobile engine generator is presented to back up not only three-phase but also a single-phase distribution line. The conventional three phase engine generators for emergency power back up consist of diesel engine, generator and controller and usually back up three-phase power only. In the proposed engine generator, a generator conditioner is included to compensate phase current unbalance, which allows backup of a single-phase line. In addition, an AVR (auto voltage regulator) controller and a governor controller and a generator conditioner controller are integrated with single DSP (digital signal processor) control board to reduce cost and increase reliability. The generator conditioner shapes the generator currents sinusoidally in phase with generator voltages for any kind of load. The generator can be synchronized with the distribution power line and released without any power interruption or voltage spike since the load current is gradually changed from the distribution line to the generator, or vice versa. A 100 kVA engine-generator system is equipped on a 3.5 ton truck and the integrated controller is realized with TMS320C32PCMA. Experimental results for single and three-phase power back up at several load conditions are presented to verify the performance of the proposed mobile generator system.

High power factor three phase rectifier for high power density AC/DC conversion applications

The conventional three-phase rectifier with bulky LC output filter has been widely used in the industry because of its distinctive advantages over the active power factor correction rectifier such as simple circuit, high reliability and low cost. Over 0.9 power factor can be achieved, which is acceptable in most industry applications. This rectifier, however, is not easy to use for high power density applications since the LC filter is bulky and heavy. To solve this problem, a new simple rectifier is presented in this paper. By eliminating the bulky LC filter from the conventional diode rectifier without losing most of the advantages of the conventional rectifier, very high power density power conversion with high power factor can be achieved. Its operating principle and design considerations are illustrated and verified by PSpice simulation and experimental results from a prototype of 3.3 kW rectifier followed by 100 kHz zero voltage switching full bridge PWM power converter.