Method and system for eliminating three-phase rectifier harmonic waves based on repetitive control

Abstract

The invention discloses a method and system for eliminating three-phase rectifier harmonic waves based on repetitive control. The method comprises the steps that a first PI controller model and a repetitive controller model provided with a compensator and added with an attenuation link in a feedback loop are established, wherein the compensator is a PI controller model; three-phase current of a PWM rectifier is obtained, and coordinates are converted into current id and iq; the current id and the given value id* are input to the first PI controller model and the repetitive controller model after being subtracted, and a first value and a second value are respectively output; the current iq and the given value iq* are input to the first PI controller model and the repetitive controller model after being subtracted, and a third value and a fourth value are respectively output; the first value, the second value and harmonic disturbance are superposed to produce Ud; the third value, the fourth value and harmonic disturbance are superimposed to generate Uq; Ud and Uq coordinates are transformed into Ualpha and Ubeta; pulse modulation is conducted on the Ualpha and Ubeta, and the Ualpha and Ubeta are transmitted to a three-phase PWM rectifier IGBT switch tube. The system has very good inhibiting capacity and can reduce the dependence on models.

Description

technical field [0001] The invention relates to a method for eliminating harmonics, in particular to a method and system for eliminating harmonics of three-phase rectification based on repetitive control. Background technique [0002] With the rapid development of society, electric energy plays an increasingly important role in industrial and agricultural production and people's daily life. However, at the same time, power electronic converters, such as frequency converters and high-frequency switches, are closely related to the production and life of the country. Various converter devices such as power supply and inverter power supply have brought a large amount of reactive power and serious harmonic pollution to the power grid in a wide range of applications. With the development of power electronics technology, a PWM rectifier with grid-side current close to sine wave, power factor approximately 1, stable DC-side output voltage, strong anti-load disturbance capability and...

AI Technical Summary

Problems solved by technology

Theoretically, the current loop adopts the traditional PI controller to realize current regulation without static difference. In the steady state, the phase current waveform of the grid side of the three-phase PWM rectifier should be a sine wave with the same phase as the phase voltage of the grid. However, due to the traditional control algorithm and Due to the switching characteristics of the power switch tube and the influence of the dead zone effect, the steady-state accuracy of the AC side current is not high, and the sine degree of the obtained current waveform is not good, and the harmonics are large

The three-phase PWM rectifier is a half-bridge circuit, which will encounter a dead zone problem during the control process. This is caused by the characteristics of the switch tube. There is a certain delay in the turn-on and turn-off process of the switch tube. short

In order to reduce harmonics, the usual method is to use a specific harmonic elimination method, but it is impossible to eliminate all frequencies that are integer multiples of the fundamental frequency

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