A virtual-flux-linkage model predictive control of single-phase PWM rectifier based on harmonic compensation

In order to reduce the hardware cost of the pulse width modulation(PWM) rectifier and improve the system reliability, one option is to eliminate the AC side voltage sensor. The virtual flux linkage is mostly adopted in the control algorithm of PWM rectifier without line voltage sensors. Accurate observation of the grid side voltage flux is the key to the high performance control of PWM rectifier. Firstly, in view of the phase shift problem of the traditional flux observer based on the first-order low-pass filter, an improved flux linkage observation method based on the second-order low-pass filter is proposed. This method can effectively eliminate the integral initial value and phase offset in the flux observer, and improve the accuracy of the flux observer. Secondly, in order to solve the problem that model predictive control cannot suppress the low-order harmonics in the grid-side current of single-phase PWM rectifier, a model prediction control strategy based on multiple harmonic compensation is proposed. Finally, the experimental results show that the proposed algorithm effectively solves the problem of phase shift of traditional flux observer, suppresses the low-order harmonics of the grid-side current, and improves the current quality of the PWM rectifier. © 2020, Harbin University of Science and Technology Publication. All right reserved.