An efficient dc/dc converter is needed as the interface between a low-voltage fuel cell source and a high-voltage bus for inverter operation. In this paper, a three-phase transformerisolated dc/dc converter utilizing phase-shift (PS) modulation is proposed. The converter must be able to boost the voltage significantly and operate at current levels above 240 A on the source side. Key features of the proposed converter include reduced transformer turns ratio by a factor of two while maintaining the same output voltage, reduced size of passive components including output filter and input dc bus capacitor using three-phase interleaving, eliminated inductor current ripple at PS angles above 120 • , and achieved soft switching over a wide load range without auxiliary circuitry. The proposed converter has been analyzed, simulated, and implemented in hardware. An efficiency of above 96% was achieved using the prototype unit. Experimental results were used to verify all designs and analyses.

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A h f i u c f 4 u l t i p h m c interleaving technology allows signiticant reduction on current ripple and fdter &E, and thus is well meived in power electronics industry. Conventional interleaved control signals are generated by multiple RC timing circuits, which are synchronized externally to obtain pbme shift between two adjacent pb= kcaugc of the variation of RC component values, the unbalance between phases is unavoidable. In this paper, the use of digital FIFO circuit as E phase-shifter is proposed. It inherently benefits from the advnntnge of digital circuit accuracy and stability, and snvea a lot of efforts on synchronizing multiple timing signnl sources. The principle of such phase-shifter is explained, and the method of applying FIFO phase-shifter for converter interluved control is depicted. A design example is shown for 1 fphase &leg converter control. The hardware test and experimental results verify the effcctiventa of such digital FIFO circuit in the power converter controller design. Keywonkphamshifi; mliiphuw, "W!er, dddc c o n w , rhree-phme interlemd Jorgen Arendt Jenscn, "Implementation of Ultrasound TimedomainCmss-eorrelation Blood Velocity Estimator", IEEE TrmLFoctioru an

An efficient dc/dc converter is needed as the interface between a low-voltage fuel cell source and a high-voltage bus for inverter operation. In this paper, a three-phase transformerisolated dc/dc converter utilizing phase-shift (PS) modulation is proposed. The converter must be able to boost the voltage significantly and operate at current levels above 240 A on the source side. Key features of the proposed converter include reduced transformer turns ratio by a factor of two while maintaining the same output voltage, reduced size of passive components including output filter and input dc bus capacitor using three-phase interleaving, eliminated inductor current ripple at PS angles above 120 • , and achieved soft switching over a wide load range without auxiliary circuitry. The proposed converter has been analyzed, simulated, and implemented in hardware. An efficiency of above 96% was achieved using the prototype unit. Experimental results were used to verify all designs and analyses.