Analysis of Model Predictive Control for Three-Phase PWM Rectifier Without Grid Voltage Sensors

In a three-phase PWM rectifier, the grid voltage sensor makes the whole system more complex and costly. In order to reduce the control system cost and improve the input current quality of the PWM rectifier in case of unbalanced grid voltage, a third-order generalized integrator (TOGI) based grid voltage sensor technique is combined with model predictive control (MPC), a positive and negative sequence calculator (PNSC) is used to separate the positive and negative sequences of the virtual flux, the compensation power required for the reference current is calculated, and then the switching state is determined by MPC after the reference current is derived. The proposed method is simulated and validated in simulation platform under balanced and unbalanced grid voltage conditions, and compared with a rectifier system with a grid voltage sensor. The simulation results show that the grid voltage sensor technology based on TOGI can eliminate the influence of high harmonics of the input current on the voltage observation, accurately estimate the grid voltage, and the power compensation greatly reduces the influence of unbalanced grid voltage on the input current waveform.