Bidirectional Buck-Boost DC-DC Power Conversion

The bidirectional Buck-Boost DC-DC converter is a power electronics conversion topology capable of both step-up and step-down voltage operations, commonly employed in battery charging/discharging systems and energy recovery applications. Its core advantage lies in achieving bidirectional energy flow through a single circuit, typically implemented using an H-bridge configuration with four switching devices (such as MOSFETs or IGBTs), coupled with inductors and capacitors for voltage transformation.

In pulse charging/discharging applications, the converter requires rapid operational mode switching. During charging, it operates in Buck (step-down) mode, transferring energy from the high-voltage side to the low-voltage side; during discharging, it switches to Boost (step-up) mode with reverse energy flow. The switching period Ts=1e-4 seconds (equivalent to 10kHz frequency) must balance switching losses against dynamic response—higher frequencies reduce inductor size but increase switching losses. Code implementation typically involves timer-interrupt driven PWM generation with dead-time compensation to prevent shoot-through.

Key control strategies include: Closed-loop control: Implements dual-loop voltage and current regulation using PI controllers to ensure stability during charge/discharge cycles Mode transition: Utilizes PWM signal algorithms for swift Buck/Boost mode switching, incorporating soft-start techniques to avoid voltage spikes during transitions Synchronous rectification: Employs MOSFET body diodes with complementary switching patterns to reduce conduction losses

This design is particularly suitable for supercapacitor or battery systems where pulsed operating conditions demand millisecond-level response capabilities. Practical implementations must address engineering considerations like inductor saturation current limits and precise switching device drive timing, often managed through protection algorithms and gate driver IC configurations.