A Dual-Peak Current Control Strategy and Implementation for Four-Switch Buck-Boost Converter

The four-switch buck-boost (FSBB) converter is ideal for scenarios such as distributed power supply in data centers and low-voltage DC-DC in electric vehicles as a voltage regulator, because it is easy to achieve zero-voltage switch (ZVS) and has both boost and buck capabilities. In order to avoid complex real-time calculations or the need for large data storage, to realize wide input, and full load range ZVS a dual-peak current control strategy is proposed. This strategy associates two peak points of the inductor current by introducing input and output voltage to achieve the boosting and bucking. Further, the working principle of the strategy is analyzed and the RMS value of the inductor current is optimized to improve the efficiency. And the case of inductor current not being reset is analyzed and set limits to ensure the inductor current can be reset at constant frequency. The strategy can be realized by high-speed comparators as well as low-delay logic gates, thus saving the storage and computational resources of the controller. Finally, a 300 W prototype with an input voltage range of 36-60 V and an output voltage of 48 V is built to verify the correctness of the strategy.