Digital Control and Phase Governing of Interleaved Multistage Hybrid Boost Capacitor Charger for Improved Efficiency and Power Density

This paper introduces a digitally controlled multiphase multistage hybrid boost converter (MMHBC) for high voltage capacitor charging applications. Rapid capacitor charging control approach is presented, and topological variations to improve efficiency are examined. The controller provides tight output current regulation, while maintaining real-time current balancing capabilities for superior thermal distribution and converter efficiency. The MMHBC is capable of rapid capacitor bank charging to high voltage by forcing maximum output current at the first stage, which translates into maximal output power during the whole charging period. The controller includes a system governor unit which facilitates additional control aspects for multiphase operation such as phase shedding, soft-start mechanism, and system protection. SMPS operation, rapid capacitor charging, and topological improvements are validated experimentally on a four-phase 12V-to-300V multiphase prototype with a maximum output power of 250W and power density of 2.5kW/Liter.