Output quality improvement for single-phase inverter in V2G system

Abstract

In vehicle-to-grid (V2G) applications, a voltage source inverter (VSI) directly connects to a residential load or grid for DC/AC conversion and power flow control. In VSI, dead-time is employed to prevent the breakdown of switching devices, however, the introduction of dead-time leads to distortions of output voltage and current in both stand-alone and grid-tie modes. For the case of a power factor of 1, by analyzing the dead-time effect of digital-controlled double-frequency sinusoidal pulse width modulation, a compensation amount is proposed to introduce in the modulation signals, the value of which is half of the delay register that generates a dead-time of t_d. Moreover, considering the phase delay caused by hardware and software filtering in sampling, the grid-tie mode control strategy based on dead-time compensation is further proposed, which introduces the grid voltage as a feedforward signal. A 3.5 kW V2G experimental prototype is built and tested to verify the feasibility of the proposed strategies. The simulation and experimental results show that the proposed methods are effective for both modes, which improve the output distortion for different dead-time without additional hardware circuits.