Three-loop Control Strategy of High Power Harmonic Voltage Generator Based on FFT

Voltage feedback control of the inverter, such as dual-loop control with voltage outer loop and current inner loop, the deadbeat control, RMS control and so on, can’t eliminate the steady-state error of the harmonic. In order to solve the above problems, this paper proposes a three-loop control strategy based on FFT. On the basis of the dual-loop control system with good dynamic performance, the FFT outer loop is added, which controls the real part and the imaginary part of each harmonic respectively in spectrum to eliminate the static error. The simulation results and experimental results show that the control algorithm not only has high dynamic performance, but also can eliminate the harmonic tracking error.