Interleaved series input parallel output forward converter with simplified voltage balancing control

The interleaved multilevel DC-DC converters have advantages of low voltage stress of the switches and diodes and reduction of filter size. Particularly series input parallel output (ISOP) configuration is well suited for high output voltage and large output current application. While multilevel topology offers many new features, it also necessitates a balance control of the input capacitors. The paper discusses design of the ISOP DC-DC converter with independent capacitor voltage balancing. The paper describes the operating principles of the balancing circuit, analyzes the fundamental relationships, introduces with control principles and experimental results based on a 3 kW prototype with 600 V input voltage and 30 V 100A output.