Optimized Modulation for the Four-Switch Buck–Boost Converter With Reduced Current Ripple

The Four-Switch Buck-Boost (FSBB) converter is a widely used topology due to its bidirectional capability and wide operating voltage range in applications such as battery chargers, photovoltaic applications, or smart grids. This paper proposes an improved modulation strategy that reduces the average inductor current, like other state-of-the-art strategies, while also minimizing the inductor's current ripple and the maximum current during the buck-boost operating mode. The objective is to minimize core power losses and reduce conduction power losses in the transistors, thereby improving overall efficiency. To demonstrate this, a state-of-the-art reference modulation strategy is first analyzed. Next, modifications are suggested to obtain the improved strategy, and both are analytically compared. Finally, both modulations are implemented and experimentally validated.