Primary-Side ZVS PWM Resonant Converter With Near-Zero-Ripple Input Current and High Efficiency for Fuel Cell Applications

In fuel cell applications, numerous prior researches have concentrated on current-fed type pulsewidth modulation (PWM) resonant dc-dc converters to achieve a low input current ripple and high efficiency. However, conventional approaches still cause a non-negligible input current ripple in practice due to two factors. The first factor is roll-off and tolerance of inductance according to the instantaneous current. The second factor is desynchronized drain-source voltage transitions during the dead time. This article proposes a new primary-side zero-voltage switching (ZVS) PWM resonant dc-dc converter for fuel cell applications. The proposed converter with a novel synchronous rectifier modulation solves the aforementioned two factors that cause input current ripple. Besides, in the process of input current ripple improvement, the primary-side switches can also achieve the ZVS, so switching losses are also reduced. Therefore, the proposed converter can achieve near-zero-ripple input current and high efficiency. Its effectiveness is verified by 600 W prototypes with 35-45 V input and 380 V output conditions.