Abstract: In order to solve low accuracy regulating, high harmonic in the common AC regulator and improving equipment quality of power supply, the paper adopt AC chopping technique to design a new generation regulator with advantages of no-contact, no-leave and low harmonic etc. Refer to four-step commutation of matrix converter based on current direction, it can solve open over-voltage problem in AC chopper commutation. In addition, the current direction detection circuit was designed to guarantee correctness. Simulation and experiment results show that the regulator with this control mode is safe and reliable ,low harmonic, fast and accurate response.