Dual comparison one cycle control for single phase bi-directional power converters

In this paper a modification to dual comparison one cycle control is proposed which enables bi-directional power flow in single phase grid connected converters. Advantages of dual comparison one cycle control when compared to conventional one cycle control is that it does not give any steady state dc offset, no light load instability and unipolar pwm without having to sense the grid voltage. Modification to dual comparison one cycle control is the addition of a fictitious current term which is generated, using a band pass filter, from the gating signal of one of the active devices. Quality factor of the band pass filter is shown to impact the total harmonic distortion in current, fundamental displacement angle and steady state dc offset. Optimal value of Q-factor along with a dc offset controller gives a superior performance. Detailed simulation and experimental studies are carried to validate the proposed control and the high performance that can be obtained.