Secondary-side Phase-shift Control Research Articles

Full-bridge resonant converter with hybrid control for wide input voltage range applications

This paper proposes a hybrid control strategy for a full-bridge resonant converter. In the applications with a wide input voltage, a resonant converter with variable frequency control (VFC) has to modulate the converter operating in a wide switching frequency range to satisfy gain requirements, which results in some problems such as difficulty in optimizing the design of magnetic components, increased power loss and deteriorated electromagnetic interference. By use of VFC, primary-side phase shift control and secondary-side phase shift control, the frequency variable range can be greatly reduced and the conversion efficiency can be increased, which make the converter appropriate for a wide input voltage range. With this hybrid control strategy, the converter can automatically convert to the corresponding control mode according to variations of the input voltage and load, which has a good transient performance. The working principle, gain characteristics and design considerations of a hybrid controlled CLL resonant converter are introduced in detail. Experimental results are shown to demonstrate its validity and feasibility.

High-frequency full-bridge isolated DC–DC converter for fuel cell power generation systems

The paper presents high-frequency isolated soft-switching DC–DC converter for generating regulated high output voltage from fuel cell power modules using secondary-side phase-shift control to eliminate idling and circulating currents. The converter topology incorporates high-frequency center tap transformer with secondary-side phase-shift soft-switching control. Parasitic capacitors of the switching devices and the transformer leakage inductance are utilized to achieve zero-voltage switching (ZVS) in the primary side of the high-frequency transformer. Therefore, no extra resonant components are required for ZVS in the proposed converter. The inherent soft-switching capability allows high power density, efficient power conversion, and compact packaging. A prototype rated at 6.5 kW is proposed and simulated in PSIM software for validation purposes. The outcomes are very encouraging and confirm the wide range voltage control and soft-switching operation of proposed phase-shift converter.

Secondary-Side Phase-Shift-Controlled Dual-Transformer-Based Asymmetrical Dual-Bridge Converter With Wide Voltage Gain

A novel dual-transformer-based asymmetrical dual-bridge (DT-ADB) converter with secondary-side phase-shift control strategy is proposed. The primary side of the DT-ADB converter is a fully active full bridge, and the secondary side is a semiactive bridge comprising of one active leg and two passive legs. The current and power of the two transformers in the converter are shared automatically by adopting primary-side-series and secondary-side-parallel configuration, and the turns ratio of the transformer is reduced by employing two transformers. The high-frequency-link inductor is reduced because the voltage applied on the inductor is reduced compared to previous converters, and hence the efficiency and power density can be improved. Zero-voltage turn-on of all the active switches and zero-current turn-off of all the diodes are achieved in a wide operation range. Furthermore, the turn-off losses of the secondary-side active switches are reduced because only half of the output current flows through the switches. Moreover, the proposed topology offers several other advantages including continuous output current and smaller output filter requirement. The operation principle is analyzed and experimental results are provided to verify the effectiveness and advantages of the proposed converter.

Secondary-Side-Regulated Soft-Switching Full-Bridge Three-Port Converter Based on Bridgeless Boost Rectifier and Bidirectional Converter For Multiple Energy Interface

A systematic method for deriving soft-switching three-port converters (TPCs), which can interface multiple energy, is proposed in this paper. Novel full-bridge (FB) TPCs featuring single-stage power conversion, reduced conduction loss, and low-voltage stress are derived. Two nonisolated bidirectional power ports and one isolated unidirectional load port are provided by integrating an interleaved bidirectional Buck/Boost converter and a bridgeless Boost rectifier via a high-frequency transformer. The switching bridges on the primary side are shared; hence, the number of active switches is reduced. Primary-side pulse width modulation and secondary-side phase shift control strategy are employed to provide two control freedoms. Voltage and power regulations over two of the three power ports are achieved. Furthermore, the current/voltage ripples on the primary-side power ports are reduced due to the interleaving operation. Zero-voltage switching and zero-current switching are realized for the active switches and diodes, respectively. A typical FB-TPC with voltage-doubler rectifier developed by the proposed method is analyzed in detail. Operation principles, control strategy, and characteristics of the FB-TPC are presented. Experiments have been carried out to demonstrate the feasibility and effectiveness of the proposed topology derivation method.

Secondary-Side Phase-Shift-Controlled ZVS DC/DC Converter With Wide Voltage Gain for High Input Voltage Applications

In this paper, a soft-switching dc/dc converter with secondary-side phase-shift control strategy is proposed to improve the conversion efficiency and minimize the primary switch voltage stress in the high input voltage applications. Zero-voltage-switching performance is achieved for both the primary- and secondary-side power devices in a wide load range to reduce the switching losses due to the secondary-side phase-shift control scheme. Furthermore, compared with the conventional phase-shift control mechanism, the circulating current at the freewheeling stage is effectively suppressed as well to minimize the conduction losses. Moreover, the voltage stress of the primary switches is only half of the input voltage by employing the improved three-level structure, which makes the low-voltage rated power devices available to improve the circuit performance. In addition, the converter can work in the buck, balance, and boost modes to achieve a relatively wide input voltage range, which is an expected advantage for the communication power system to minimize the electrolytic capacitors with an acceptable hold-up time. The operation principle is analyzed and experimental results of a 1-kW 100-kHz prototype are provided to verify the effectiveness and the advantages of the proposed converter.