A resonant supplied cascaded H-Bridge Cell for a Series Hybrid Cascaded H-Bridge Converter used as a Power Hardware in the Loop Emulator

This paper presents a resonant LLC DC/DC-converter supplied Cascaded H-Bridge (CHB) cell for the use in a Series Hybrid Cascaded H-Bridge (SH-CHB) converter. The SH-CHB converter, which consists of CHB-cells with a dv/dt-filter and series-connected Linear Power Amplifiers (LPA), is briefly introduced and the requirements for the CHB-cells are discussed. The LLC circuit is designed for a resonance frequency of 60-70 kHz. The CHB-cells have a maximum output current of 70 A and can provide an output voltage of +/- 30 V. The resulting maximum output power is 2.1 kVA. All passive components of the resonant LLC DC/DC-converter supplied CHB-cells are PCB integrated. For the control and communication, a FPGA board is developed and a new switching frequency adaption algorithm as well as a novel start-up control strategy for the resonant LLC circuit is implemented.