Model predication control method of three-phase PWM (pulse width modulation) rectifier under unbalanced voltage

Abstract

The invention discloses a model predication control method of a three-phase PWM (pulse width modulation) rectifier under unbalanced voltage. The technical scheme mainly includes that the model predication control method of three-phase PWM rectifier under unbalanced voltage includes: negating input active power and input reactive power which are obtained by computation, enabling negated values to pass through proportional resonant controllers, obtaining second harmonic compensation voltages under a two-phase rotating coordinate system by means of compensating voltage computation, then obtaining second harmonic compensation voltages under a two-phase static coordinate system by means of reverse Park transformation, compensating the second harmonic compensation voltages under the two-phase static coordinate system into output voltage subjected to traditional model predication control, enabling voltage vectors with the minimum absolute values, which are differences of current given values and current predication values, to serve as optimal voltage vectors by value function selection, and using the optimal voltage vectors as switching signals for controlling power devices. The model predication control method of the three-phase PWM rectifier under unbalanced voltage is capable of effectively inhibiting second harmonic fluctuation of input power of the rectifier under the condition of unbalanced power grid voltage, and is simple in control structure, short in system delay and capable of simultaneously eliminating secondary pulses of input active power and input reactive power of the system.

Description

technical field [0001] The invention relates to a control method of a voltage-type PWM rectifier, which belongs to the control field of electric power electronic power conversion devices, in particular to a model predictive control method of a three-phase PWM rectifier under unbalanced voltage. Background technique [0002] With the rapid development of microprocessor technology and the deepening of related research, model predictive control has shown great advantages in the application of power electronics and motor drives. Model predictive control is a control algorithm that predicts the future response of the controlled object based on a mathematical model. The algorithm includes a value function defined in terms of control objectives. By minimizing the cost function, the algorithm predicts the best voltage vector in each sampling period as the action vector in the next period, and the algorithm loops once in each sampling period. The all-digital control method of powe...

AI Technical Summary

Problems solved by technology

Since the model predictive control adopts the loop optimization and direct output variable frequency control method, although the transient response speed of the system is excellent, its sampling frequency is high, and the operation performance is obviously affected by the system delay.

When the control algorithm is relatively complex and the amount of calculation is large, the calculation process will generate a large delay, which will affect the dynamic response speed and control quality of the system.

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