Duplex Pulse Frequency Modulation Mode Controlled Series Resonant High Voltage converter for X-Ray Power Generator

Enhui Chu,Koki Ogura,Serguei Moisseev,Atsushi Okuno,Mutsuo Nakaoka 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.<br/>

Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter

Chu, Enhui,Bao, Jianqun,Song, Qi,Zhang, Yang,Xie, Haolin,Chen, Zhifang,Zhou, Yue The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.

Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter

Enhui Chu,Jianqun Bao,Qi Song,Yang Zhang,Haolin Xie,Zhifang Chen,Yue Zhou 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.

Auxiliary resonant commutated pole soft‑switching inverter with simple topology

Enhui Chu,Tianyu Zhang,Zhiyong Wang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.2

To address the complex topology of auxiliary resonant commutated pole inverters and the large current stress of auxiliary switches, this paper proposes an auxiliary resonant commutated pole soft-switching inverter with a simple topology. The proposed inverter not only reduces the current stress of the auxiliary switches and the loss caused by the reactive energy conversion in the circuit but also simplifies the topology of the auxiliary commutated circuit, reduces the cost of the inverter, and improves the reliability of the inverter. The inverter is suitable for small and medium power applications. Under the proposed modulation strategy, the operation principle of the inverter, the conditions of soft-switching realization, and the optimal parameter design method are analyzed in detail according to the equivalent circuit diagrams in different operating modes. Finally, a 10-kW, 16-kHz prototype is fabricated using insulated gate bipolar transistors (IGBT) as switches, and the effectiveness of this inverter is verified through experiments.

Zero-Current-Switching in Full-Bridge DC-DC Converters Based on Activity Auxiliary Circuit

Enhui Chu,Ping Lu,Chang Xu,Jianqun Bao 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

Zero-Current-Switching in Full-Bridge DC-DC Converters Based on Activity Auxiliary Circuit

Chu, Enhui,Lu, Ping,Xu, Chang,Bao, Jianqun The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

Analysis and implementation of passive soft switching snubber for PWM inverters

Enhui Chu,Zhiyong Wang,Yunjing Kang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.1

To realize a three-phase soft-switching inverter with a simple structure, low cost, and easy modularization, this paper proposes a novel three-phase passive soft-switching inverter, which realizes soft-switching of the switches in the inverter through energy consumption of the auxiliary snubber circuit. When compared with the traditional passive soft-switching inverter, it avoids the use of transformers, coupled inductors, and bulk electrolyte capacitors. Thus, it has a small size, a high power density, and is suitable for integration. Its three single phases are independent of each other, which makes it easy for the inverter to apply various control strategies. This study chooses a single-phase circuit, and investigates the operating principle, soft-switching implementation characteristics, and parameter design methods of the novel passive soft-switching inverter under various operation modes. Finally, a 10 kW/16 kHz prototype is made using an IGBT as a switch, and experiments are conducted to confirm the validity of the inverter.