Enhui Chu

Novel Zero-Voltage and Zero-Current Switching (ZVZCS) PWM Three-Level DC/DC Converter Using Output Coupled Inductor

In this paper, a novel zero-voltage and zero-current switching (ZVZCS) pulsewidth modulation (PWM) half-bridge (HB) three-level (TL) dc/dc converter is proposed. Compared with traditional ZVZCS PWM TL dc/dc converters, this converter does not include auxiliary resonant circuits. It can achieve zero-voltage switching (ZVS) for the leading switches and approximate ZCS for the lagging switches with the aid of the transformer parasitic inductance, snubber capacitors, and tapped-inductor-type smoothing filter. This converter can reduce the voltage and current spikes of the power switches as well as the primary circulating current loss effectively. The operation principle of the novel converter and the soft-switching implementation condition are analyzed according to equivalent circuits under different stages. Besides, the effects of the tapped-inductor turns ratio on the current stress of the power switches and the output voltage characteristic under open-loop control scheme are discussed. The validity and features of the proposed converter are demonstrated by simulation results and experimental results via a 6-40 kHz prototype using the fast switching insulated gate bipolar transistor (IGBT).

Analysis and Implementation of A Passive Lossless Soft-Switching Snubber for PWM Inverters

In this paper, a passive lossless snubber circuit for pulse width modulation (PWM) inverters is proposed to achieve soft-switching purpose without extra switch or additional control circuitry. This passive lossless soft-switching snubber employs an inductor/capacitor snubber structure for each switching device in an inverter to achieve passive zero-current turn ON and zero-voltage turn OFF. Furthermore, inductors coupled closely on a single core are used to losslessly recover snubber energy to the input in the proposed snubber. In addition, freewheeling of output phase current of inverters can be realized via energy storage components of the snubber during the dead time to reduce the effect of dead time. The distortion ratio of the output phase current in low output frequency is also reduced. All components in the snubber circuit are passive, and thus have a better price/performance ratio than their active counterparts. The proposed snubber has been incorporated into a 14-kW PWM inverter. Experimental results are given to demonstrate the validity and features of the snubber.

Research on a Novel Modulation Strategy for Auxiliary Resonant Commutated Pole Inverter With the Smallest Loss in Auxiliary Commutation Circuits

Aiming at overcoming the problem that the auxiliary commutation circuit (ACC) of auxiliary resonant commutated pole (ARCP) inverters has a high loss in commutation processes, this paper presents a novel modulation strategy based on an improved ARCP inverter. In comparison with the original modulation strategy, this modulation strategy can not only realize soft-switching for all switches, but also avoid the superposition of resonance current and load current at commutation moments in ACCs and make the maximum current through ACCs approximately equal to load current in commutation processes. So the circulating current loss in ACCs and the current peak stress of auxiliary switches can be effectively reduced. According to the equivalent circuit in different operation modes under this modulation strategy, this paper analyses the operation principle, soft-switching implementation condition, and optimal parameter design procedure of the improved ARCP inverter. Finally, the novel modulation strategy is applied to a 10 kW 16 kHz improved ARCP inverter prototype with insulated gate bipolar transistor-based switches. Experimental results are given to demonstrate the validity and features of the inverter under the novel modulation strategy.

Research on A Novel Modulation Strategy for Double Auxiliary Resonant Commutated Pole Soft-switching Inverter With the Shunt Dead Time

Aimed at the problem that the auxiliary commutation circuit (ACC) of auxiliary resonant commutated pole (ARCP) inverters has a high loss in commutation processes, this paper presents a novel modulation strategy with shunt dead time based on a double ARCP (DARCP) inverter. In comparison with the original modulation strategy, this modulation strategy cannot only achieve soft switching for all switches, but also avoid the superposition of resonance current and load current at commutation moments in double ACCs (DACCs) and make the maximum current through DACCs approximately equal to load current in commutation processes. So, the circulating current loss in DACCs and the current stress of auxiliary switches can be effectively reduced. According to the equivalent circuits in different operation modes under the novel modulation strategy, this paper analyzes the operation principle, soft-switching implementation condition, and optimal parameter design procedure of the DARCP inverter. Finally, a 10-kW-16-kHz DARCP inverter prototype with insulated gate bipolar transistor-based switches is built. Experimental results are given to demonstrate the validity and features of the DARCP inverter under the novel modulation strategy.

A Novel Soft-Switching Converter with Passive Auxiliary Resonant Commutation

A novel soft-switching converter with passive auxiliary resonant commutation is presented in this chapter. Soft-switching of the switch can be achieved by using passive auxiliary resonant network. It is very attractive for high power application where IGBT (insulted gate bipolar transistor) is predominantly used as the power switch. Its operation principle is analyzed through its application to the boost converter. The condition of soft switching and the design considerations is analyzed in detail. The novel soft-switching cell can be also used in other basic dc-dc converter. A 5kW, 20kHz prototype which uses IGBT has been made. The effectiveness of the proposed converter is confirmed by the simulation and experimental results.

A Research on a Double Auxiliary Resonant Commutated Pole Soft-Switching Inverter

Aiming at overcoming the problem that the auxiliary switches in an improved auxiliary resonant communicated pole inverter may not realize zero-voltage turning off in practical application if there are parasitic inductors in the wiring process, this paper proposes a novel double auxiliary resonant commutated pole inverter. In novel topology, auxiliary capacitance and auxiliary switch are in parallel. This structure avoids the influence of parasitic inductors in the wire, and ensures the auxiliary switch to realize zero-voltage turning off reliably. The novel topology not only inherits all advantages of the improved auxiliary resonant communicated pole inverter, but also improves its reliability. Therefore the novel topology is more suitable for high power occasion.