Analysis of dual-carrier modulator for bidirectional noninverting buck-boost converter

A pulse-width modulation modulator for a noninverting bidirectional buck-boost converter is analyzed and a corresponding average-mode current controller design is revealed. The main feature of the modulator is the ability to create switching sequences for both converter legs without requiring any information regarding either operation mode or the direction of power flow. The modulator receives a control signal generated by the current controller, and a triangular carrier and generates driving signals with two different duty cycles, allowing tight control of the inductor current throughout the entire operating range. The underlying circuitry is thus relatively simple; moreover, the proposed method greatly simplifies the outer loop controller design. The revealed findings are supported by simulations and experiments.