In a phase-shifting, zero voltage switching full-bridge converter, the two legs of the full-bridge are switched with two square waves whose phase shift is modulated by the converter’s control loop and the resulting square wave is fed into the primary of the transforms that provides primary-secondary isolation and voltage scaling. Parasitic resonance between the capacitance of the transistors and the transformer’s leakage inductance is exploited to ensure a soft turn-on – ideally zero voltage switching (ZVS) - for all four switches in the primary. To also extend the ZVS range at light loads, a resonance inductor is introduced in series with the primary winding of the transformer.
ZVS helps reduce switching losses and stress in addition to removing the need for primary snubbers. It also enables higher switching frequencies which helps in the design of converters with higher efficiency and power density, making this converter well suited for high-power (> 600 W), high-frequency applications.
ST offers a range of advanced digital controllers, rectifiers and power MOSFETs with improved reverse recovery time of their intrinsic diode. Our high-performance STM32 microcontrollers with an extended range of dedicated peripherals including high-resolution PWM timers and high-speed ADCs together with our hardware and software evaluation and development tools as well as reference designs enable developers to fully exploit the benefits of full-bridge phase-shift ZVS converters.