Performance Optimization in Phase Shifted Full Bridge Converter Using Parallel Loop Shaping Technique

Phase-shifted Full-Bridge (PSFB) DC-DC converters are highly regarded for medium to high voltage and high power applications due to their ability to minimize switching and conduction losses. By utilizing Zero Voltage Switching (ZVS) through phase-shifted Pulse Width Modulation (PWM), these converters achieve significant reductions in switching losses during transitions, which enhances overall efficiency. The effective duty cycle in PSFB converters is crucial, as it directly influences the output voltage and power transfer capabilities. By carefully adjusting the phase shift between the switches, operators can optimize performance to maintain stable output voltages, even amid variations in input voltage, output current, or reference voltage. However, the non-minimum phase behavior of PSFB converters presents challenges for traditional control methods like Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) controllers, which may lead to stability issues. This paper proposes an effective control strategy to address these non-minimum phase characteristics by introducing a parallel control strategy, that integrates Voltage Mode Control (VMC) and Current Mode Control (CMC), enhanced by Type II and Type III compensators. VMC dynamically adjusts the duty cycle to regulate the output voltage, ensuring precise voltage control. Simultaneously, CMC improves transient response and provides overcurrent protection by continuously monitoring and regulating the output current. The Type II compensator enhances the steady-state response, while the Type III compensator improves transient performance and stability. This dual-mode control approach ensures optimal performance, stability, and responsiveness of the PSFB converter across diverse operating conditions, making it well-suited for demanding applications.