Modified Modulation Signals for GaN-E-HEMTs based HERIC Inverter to Improve Reverse Conduction Performance

This paper presents an application of modified PWM signals to enhance the efficiency of GaN HEMTs based HERIC inverter. Although application of GaN switches might increases the power density and overall efficiency of inverters due to the structure of GaN HEMTs, reverse conduction losses are increased during the second and fourth quadrant operation of the inverter. Hence, control of the inverter requires modifications to tackle additional losses introduced by GaN switches. Conventional PWM signals were designed to suppress the leakage current by keeping the voltage level constant at the switching nodes in all operating modes. However, modified PWM signals not only suppress the leakage current but also reduce the reverse conduction losses in GaN HEMTs. In this paper, proposed theory is validated by simulations based on spice models provided by the manufacturer of switches on LTspice. Simulation results validated the proposed solution and reported almost 50% reduction in reverse conduction losses. Practical prototype based on GaN HEMTs was also designed and tested. This study aids understanding the effect of the reverse losses on the device behavior and overall efficiency of the inverter.