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This paper suggests a design of pulsewidth modulation series-resonant converter (PWM SRC) for magnetron power supplies. The goal of this design is to make the PWM SRC have a wide output voltage maintaining mode 3 operation that shows good switching characteristics. To keep the mode 3 operation, a systematic design is required because the design is related to various parameters, such as resonant tank, transformer turns-ratio, magnetizing inductance, and duty-ratio. To establish the design procedure, converter analysis is performed related to the steady-state operation, input–output relationship, and critical design conditions, and several design equations are derived based on the analysis. Based on the design procedure, a PWM SRC with parallel-input-series-output-connected transformer has been designed for magnetron power supplies and verified. [ABSTRACT FROM AUTHOR]

This paper suggests a hybrid pulsewidth-modulation (PWM) dc/dc converter for an electric vehicle (EV) on-board charger (OBC). It is composed of a full-bridge (FB) converter and a resonant converter with secondary resonance tank (SRT). They are coupled in a single transformer so that any power distribution problem that causes a size increase in the transformer can be solved. Dual power flow of the proposed charger provides an increase in charger gain and a reduction of turn-off voltage spikes of the rectifying diodes caused by transformer leakage inductance and diode junction capacitance. These characteristics help reduce diode loss and remove dissipative snubber circuitry. In addition, this structure has the additional advantage of output inductor size due to the reduction of voltage variation applied to the inductor. The feasibility of the proposed charger is verified with a 6.6-kW prototype implemented by a design procedure. [ABSTRACT FROM PUBLISHER]

This paper suggests another candidate for a dc/dc converter in an electric vehicle onboard charger. Maintaining topological characteristics similar to those of conventional resonant converters, it is operated with a constant frequency PWM for charging control. Since the converter uses a secondary resonant tank, soft-switching and resonant operations can be separated. A practical design procedure is suggested to guarantee the normal operation, and the feasibility of the PWM SRT converter is verified with a 6.6-kW prototype charger designed by the procedure. [ABSTRACT FROM PUBLISHER]

This paper suggests a two-stage isolated/bidirectional dc/dc converter with hybrid-switching technique. High-frequency bidirectional resonant converter with a fixed gain can reduce the bulky transformer size by minimizing Insulated Gate Bipolar Junction Transistor (IGBT) turn-off loss due to tail current, and it forms bidirectional power flow without any control operation. Pulsewidth-modulation nonisolated converter takes in charge of bidirectional control, and its serious turn-off switching loss is alleviated using MOSFET-assisted hybrid-switching structure. The proposed scheme provides low switching loss and removes snubber circuitry so a high efficiency and a high power density can be obtained in high-voltage/high-power bidirectional applications. [ABSTRACT FROM PUBLISHER]

This paper suggests an isolated dc/dc converter using an unregulated LLC converter for fuel cell applications. The LLC converter operates as an isolated voltage amplifier with a constant voltage gain, and a nonisolated converter installed in the input stage regulates the output voltage under a wide variation of fuel cell stack voltage. By separating the functions, the unregulated LLC converter can be operated at an optimal switching condition, and the high-frequency operation of 300 kHz can be accomplished without introducing an excessive switching loss. The prototype converter with a 1-kW design (Vin = 24 \sim 48\ \V/Vo = 400\ \V) shows an efficiency of above 90.2% under a 24-V input and full load conditions. [ABSTRACT FROM AUTHOR]

This letter suggests a two-stage isolated/bidirectional dc/dc converter with three bridges. Two bridges are used for electrical isolation and constant gain, and the bidirectional control is accomplished through only a single bridge. RMS currents in the high-voltage source and link capacitor can be alleviated by capacitor division and synchronizing operation of both stages. This structure provides a simple control scheme and removes snubber circuitry, so a high efficiency can be obtained under a high switching frequency regardless of operational modes. [ABSTRACT FROM AUTHOR]