An Improved Voltage Sensorless Model Predictive Direct Power Control for Vienna Rectifier

The control system design of Vienna rectifier is inseparable from the parameters of grid voltage, which will increase the cost and complexity when using voltage sensors. Therefore, this paper proposes a grid voltage sensorless model predictive control strategy for Vienna rectifier. Firstly, the virtual flux mathematical model of Vienna rectifier is established to estimate the grid voltage. Due to the mathematical model contains integral operation, the integrator is modified to a second-order low-pass filter (LPF) by solving the problems of integral initial value and dc bias to improve the observation effect. Then, the given values of active power and reactive power of the system are obtained through the outer loop. Lastly, combined with direct power and model predictive control (DPMPC), it can quickly find the switch sequence of tracking target. A simplified vector selection is also used to the system to reduce the computational complexity. Thus, it is verified the correctness of the theoretical analysis, and the results shows that the proposed model predictive direct power control has good steady-state and dynamic performance.