A Multi-Frequency PCCM ZVS Modulation Scheme for Optimizing Overall Efficiency of Four-Switch Buck-Boost Converter With Wide Input and Output Voltage Ranges

The pseudo-continuous conduction mode (PCCM) zero-voltage-switching (ZVS) modulation scheme is widely used in the four-switch buck-boost (FSBB) converter to achieve high efficiency and voltage step-up/step-down without modulation mode transition. There are two degrees of modulation freedom in the PCCM ZVS modulation scheme. The previous schemes typically only optimize one of them to reduce root mean square (rms) inductor current, which results in relatively lower efficiency in the condition when the difference between input voltage and output voltage is large. In this article, a multi-frequency PCCM ZVS modulation scheme is proposed for the FSBB converter with wide input and output voltage ranges. By optimizing both of the two degrees of modulation freedom to reduce rms inductor current, the heavy-load efficiency can be effectively improved when the difference between input voltage and output voltage is large. Thus, the overall efficiency of the FSBB converter can be optimized. A 1500-W FSBB prototype with input and output voltage ranges of 200-400V is built to verify the proposed modulation scheme.

Automated summary

A multi-frequency pseudo-continuous conduction mode zero-voltage-switching modulation scheme is proposed in this article for the four-switch buck-boost converter. It effectively improves the heavy-load efficiency when the difference between input voltage and output voltage is large, thereby optimizing the overall efficiency.