An isolated ultra-low distortion inverter based on the differential output structure with wide soft-switching load range

For the conventional PWM inverter based upon the H-bridge, voltage distortion due to the dead-time effect is hard to attenuate or correct by the LC low pass filter or the feedback compensation. An isolated inverter based on the differential output structure is proposed in this paper to eliminate the dead-time effect. The proposed circuit includes two phase-shift full bridges (PSFB) which share a common leg on the primary side and adopts the full-wave synchronous rectifier on the secondary side. Zero voltage switching (ZVS) performance can be realized for all the primary switches in the whole load range with suitable control of the secondary switches. And the secondary synchronous switches can achieve the zero current switching on (ZCS-on) performance. Moreover, the output voltage distortion can be improved greatly since the inherent duty losses of the PSFBs can be neutralized on the differential output AC voltage. Additionally, the high-frequency isolated topology can match the different input and output voltage levels. Finally, a simulation platform and a 100V-input 20V-output prototype are built to demonstrate the correctness of the proposed inverter.