PWM (Pulse-Width Modulation) rectifier controlling method and PWM rectifier

Abstract

The embodiment of the invention provides a PWM (Pulse-Width Modulation) rectifier controlling method and a PWM rectifier. The PWM rectifier controlling method is a passivity control method based on repeated control and compensation, and comprises the following steps: a control law of the PWM rectifier based on the interconnection and damping configuration of port controlled dissipation Hamilton models is obtained with a Lagrange-Charpy integral method; and a composite controller including repeated control and passive control is used as a controller of the PWM rectifier, and the passive control is compensated by the repeated control according to the control law so as to suppress periodic interference. According to the embodiment of the invention, PWM rectification of a unit power factor can be realized, and at the same time the harmonic interference of a power grid is better suppressed under the condition of not detecting load harmonic current so as to improve power quality. Compared with the conventional PWM rectifier, the PWM rectifier disclosed by the invention has the functions of harmonic suppression and reactive compensation under the condition of not increasing hardware cost.

Description

technical field [0001] The present invention relates to the technical field of power systems, in particular to a PWM (Pulse Width Modulation, pulse width modulation) rectifier control method and a PWM rectifier. Background technique [0002] An ideal power system continuously provides users with stable and reliable power with a standard sine wave of rated voltage and constant frequency (50Hz or 60Hz). With the development of industrial technology and the needs of production, especially the development of power electronics technology in recent decades, most of the electric energy provided by the power system is provided to electrical equipment after secondary conversion by power electronics technology, so that the power It has been more fully utilized, greatly improving the efficiency and comfort of human production and life. However, the nonlinearity and time-varying nature of power electronic equipment make the voltage waveform of the power system seriously distorted, whic...

AI Technical Summary

Problems solved by technology

In the power occasions of several kilowatts to hundreds of kilowatts widely used in the industry, the PWM rectifier has the following advantages: it has small harmonic current on the AC side, unit power factor, bidirectional energy flow, and can realize constant voltage and current control. Attention, now it has begun to be applied in some occasions, but the traditional PWM rectifier also has the following disadvantages: the rectifier and its load can only be equivalent to a linear load through control, and the current flowing into the PWM rectifier is guaranteed to have a unit power factor. Harmonic problems caused by other nonlinear loads cannot be suppressed; the single function leads to its low cost performance, which hinders its wide-scale application

However, this method uses a low-pass filter in the harmonic extraction process, which will cause a certain delay in the detected harmonic reference signal and affect the compensation effect.

[0006] (2) Reference harmonic current tracking problem

Since the compensation object of the active power filter is reactive power and harmonic current ranging from one to multiple times, it is necessary for the controller to have sufficient current bandwidth, and at the same time, the dynamic changes of various nonlinear power electronic loads in the power system are difficult to predict , resulting in the order and size of the harmonic current that the active filter needs to compensate is erratic. Therefore, choosing a relatively perfect high-performance controller is a serious challenge for scientific research and engineering personnel

[0007] (3) Compensate the cost of harmonic equipment

According to the basic principle of the active power filter, in order to ensure its normal operation, not only the real-time detection of the three-phase load harmonic current as a reference, but also the real-time detection of the three-phase compensation current of the active power filter as the controller feedback input, so it is necessary A large number of high-speed and high-precision sensor equipment, high-speed and high-precision signal conditioning circuits and processors with powerful computing capabilities, coupled with a large number of high-power power electronic full-control devices, are relatively expensive

[0008] To sum up, (1) The current PWM rectifier in the traditional sense can only realize its own unity power factor rectification, but it does not have the function of suppressing the grid harmonics caused by other loads in the grid

(2) The current equipment for suppressing grid harmonics, including passive filters and active filters, has certain shortcomings

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