Improved Capacitor Energy Balance Control Strategy for Three-Port Rectifier With Low-Frequency Pulse Load Frequency Drop

Low-frequency pulse loads pose new challenges to the reliability of power supply systems. The unfixed pulse frequency makes it difficult to maintain a constant output voltage of the converter and places higher demands on the dynamic performance of the converter. The traditional one-stage energy balance control method has improved the dynamic performance, however, it cannot solve the overshoot problem caused by overcharging of power decoupling capacitor voltage. A segmented capacitor energy balance control method based on a three-port rectifier is proposed for the sudden drop of pulse load frequency. Based on the idea of traditional energy balance, a pulse advance detection link is introduced to solve the voltage overshoot problem of decoupling capacitor. When the pulse frequency decreases, the decoupling voltage is maintained constant to prevent voltage overshoot. When the pulse starts, the active current of rectifier is made to go through a rise and fall process to achieve capacitor energy balance by the second stage. Through the two step control, the voltage ripple of the decoupling capacitor and dynamic adjustment time can be reduced simultaneously. Finally, a three-port rectifier prototype was built. The effectiveness and feasibility of the proposed control method are verified through the comparative experiments.