A predictive control method for constant frequency current of single-phase pwm rectifier

Abstract

The invention discloses a single-phase PWM rectifier fixed-frequency current prediction control method. The control method comprises the following steps of selecting three switch states in one sampling period, wherein the switch states include an effective switch state and two zero switch states, and action time of the two zero switch states is the same so as to achieve fixed-frequency control; listing and writing a discretization equation of a circuit as a prediction model of an input current according to the action time of each switch state in one sampling period; deriving the time by usinga target function and making a derivative be 0 to obtain the optimal action time of different effective switch states, and then obtaining the action time of the zero switch states; and substituting arelated parameter into the target function, and selecting the effective switch state which makes a target function value be minimum as the effective switch state of a next period. As the three switchstates are selected in one sampling period, a switch frequency of a switch tube can be ensured to be constant, a harmonic component in the input current can be effectively reduced, and operation performance of the system is improved.

Description

technical field [0001] The invention relates to the technical field of single-phase PWM rectifier control, in particular to a single-phase PWM rectifier fixed-frequency current prediction control method. Background technique [0002] With the increasingly serious energy crisis and environmental problems, the research of new energy technology has received more and more attention. In small and medium power applications, single-phase PWM rectifiers are widely used. Model predictive control has the advantages of simple control structure and fast dynamic response, but it also has problems such as unstable switching frequency, large amount of calculation, and high harmonic content of grid-side current. [0003] At present, the fixed frequency predictive control of single-phase PWM rectifier has fixed frequency predictive power control, but this method has a large amount of calculation, complex control, and there is only one zero switching state in one sampling period, and the low...

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Problems solved by technology

Model predictive control has the advantages of simple control structure and fast dynamic response, but there are also problems such as unstable switching frequency, large amount of calculation, and high harmonic content of grid-side current.

[0003] At present, the fixed-frequency predictive control of single-phase PWM rectifiers has fixed-frequency predictive power control, but this method has a large amount of calculation and complex control, and there is only one zero-switching state in one sampling period, and the switching frequency is low, which leads to unsatisfactory harmonic suppression.

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