Tightly regulated dual-output half-bridge converter using PFM-APWM hybrid control method

The conventional dual-output converter requires secondary side post regulator (SSPR) and/or additional circuitries to tightly regulate each output voltage. However, those dual-output methods can induce high cost and low power density. In this paper, a hybrid control method combining a pulse frequency modulation (PFM) and an asymmetrical pulse width modulation (APWM) is proposed to obtain tightly regulated output voltages using only output voltage sensors. The operational principles of the proposed hybrid control algorithm will be introduced and analyzed to derive its design methodology. The improved voltage regulation performance will be verified using simulation and experimental results with a 190 W prototype converter.