Analysis and Comparison of Inductor Current Characteristics for Non-Inverting Buck-Boost Converter With Four-Mode Modulation

The non-inverting buck-boost (NIBB) converter is a non-isolated converter with bidirectional step-up and step-down capabilities. To realize the continuous regulation of output voltage, four-mode modulation is preferred. However, there are various pulse position allocation strategies, and their differences are rarely discussed. In this article, four different pulse width modulation (PWM) methods are introduced. Then, their effects on the characteristics of inductor current are discussed, including average value, ripple value and root-mean-square (RMS) value. Analytical solutions are given and compared to guide the converter design and inspire future research. Finally, the analysis and comparison are verified on a 200V, 400W output prototype. Experimental results show that there is about 0.2% efficiency difference when using different modulation methods.