The design of an input series output parallel (ISOP) partial power processing (PPP) converter with the benefits of high efficiency, ZVS across a wide load range, and simple control is presented for automotive energy storage applications. To operate with a secondary side current of 208 A rms at 1 MHz, 80 oC ambient temperature the converter uses a hybrid-flex PCB stack up to minimize board thermal resistance. Traditional FR4 is compared to hybrid-flex and a 20 oC peak temperature reduction was observed when using hybrid-flex. 1 MHz, 5 kW matrix transformer design and transformer via current sharing design rules are also presented. The design rules increased via utilization from 50% in a traditional layout to 100% with the proposed procedure. Due to the automotive application, the converter is mounted to a chassis for cooling and all major components can only be on the top of the board. The final converter achieves a peak efficiency of 98.5% at 5 kW output with a power density of 150 W/in3.
