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The conventional high-frequency phase-shifted zero-voltage-switching (ZVS) full-bridge dc/dc converter has a disadvantage, in that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, rms current stress, conduction losses of the transformer and switching devices are increased. To alleviate this problem, this paper proposes an improved zero-voltage zero-current switching (ZVZCS) phase-shifted full-bridge (FB) dc/dc converter with a modified energy-recovery snubber (ERS) attached at the secondary side of transformer. Also, the small signal model of the proposed ZVZCS FB dc/dc converter is derived by incorporating the effects introduced by a transformer leakage inductance and an ERS to achieve ZVZCS. Both analysis and experiment are performed to verify the proposed topology by implementing a 7-kW (120 Vdc, 58 A) 30-kHz insulated-gate-bipolar-transistor-based experimental circuit Index Terms--Energy-recovery snubber, full-bridge (FB) dc/dc converter, small-signal modeling, zero-voltage switching (ZVS), zero-voltage zero-current switching (ZVZCS).

A new technique of reducing torque ripples in inverter-fed brushless dc motor (BDCM) drives is proposed. The proposed technique reduces torque ripple components by controlling switching angles of the inverter. The simulation and experimental results indicate that the proposed technique can reduce the torque ripples significantly and improve the performance of the system. Index Terms - Brushless dc motor, torque ripples.

In designing interface circuits to a battery, often the battery is assumed to be a simple voltage source. However, the battery itself has internal parameters. This means that the internal parameters of the battery models need to be considered for the interface design. Several electrical battery models are presented. Then, using the electrical battery models, the analysis and the design of the interface circuit are described. The analysis and experimental results show that the electrical battery model which reflects battery characteristics has to be used for the optimal design of the interface circuit. Finally, the analysis results indicate that the required size of the condenser filter can be smaller with battery power supplies than with other power supplies, such as bridge-type ac source dc power supplies.