Leading-edge modulation voltage-mode control with flux unbalance correction for push-pull converter

This paper presents a leading-edge modulation voltage-mode control scheme for a 3 kW, 96 V battery-backed-up DC-DC converter with 400 V/ 800 V output, which is developed to power a half-bridge inverter in an on-line sinewave UPS system. A new circuit scheme is proposed to implement pulse-by-pulse current limit and flux unbalance correction functions with a leading-edge modulation voltage-mode PWM control IC, TL598. Design considerations for implementing voltage control loop for this application and experimental results are also presented.