Three-phase bridge PWM converter and active power filter formed by same

Abstract

The invention discloses a three-phase bridge PWM converter. The three-phase bridge PWM converter comprises a first bridge arm circuit, a second bridge arm circuit and a third bridge arm circuit which have the same connecting mode. One end of each bridge arm circuit is connected with the positive electrode of a capacitor, and the other end of each bridge arm circuit is connected with the negative electrode of the capacitor. Each bridge arm circuit comprises two IGBTs which are in series connection, and each IGBT is in parallel connection with a diode. The invention further discloses an active power filter which is provided with the three-phase bridge PWM converter. By means of the three-phase bridge PWM converter and the active power filter formed by the same, harmonic waves and idle work with the variable frequency and size can be compensated, the defect of the active filter can be overcome, and the compensation characteristic better than that of the active filter can be obtained.

Description

technical field [0001] The present invention relates to the field of power equipment manufacturing, in particular to a three-phase bridge PWM (pulse width adjustment) converter; the invention also relates to an active power filter with the three-phase bridge PWM converter . Background technique [0002] With the development of modern industry, the nonlinear load in the power system has increased greatly. Various nonlinear and time-varying electronic devices such as inverters, rectifiers and various switching power supplies are widely used, and their negative effects are becoming more and more obvious. Power electronic devices such as inverters, rectifiers, and various switching power supplies inject a large number of harmonics into the grid during switching operations, which seriously distorts the voltage and current waveforms in the grid. Power electronic devices have become the most important source of harmonics in the power grid, and the research on the harmonic polluti...

AI Technical Summary

Problems solved by technology

[0005] (1) Make the components in the power grid generate additional harmonic losses, such as causing additional losses to the motor, increasing heat generation, reducing overload capacity, service life and efficiency, and generating pulsating torque; in addition, it reduces the power generation, transmission and electrical equipment. Efficiency, a large amount of 3rd harmonic current flowing through the neutral wire can cause the neutral wire to overheat or even cause a fire

[0006] (2) The voltage drop of harmonic current on the transmission line will cause serious distortion of the voltage waveform at the user end, affecting the normal operation of electrical equipment

Harmonics cause overheating of capacitors, cables and other equipment, aging of insulation, shortening of life, and damage

[0007] (3) It is easy to cause local parallel or series resonance between the power grid and the shunt capacitor used to compensate the reactive power of the power grid, resulting in overvoltage or overcurrent, aging of the capacitor insulation, and even serious accidents

[0008] (4) Harmonics will lead to malfunction of relay protection and automatic devices, and make the measurement of electrical measuring instruments inaccurate, affecting the measurement accuracy

[0009] (5) Harmonics will interfere with the adjacent communication system. The light ones will generate noise and reduce the quality of communication. The severe ones will cause information loss and make the communication system unable to work normally.

However, LC tuned filters also have disadvantages such as filter compensation characteristics depending on grid and load parameters, drift of LC parameters will lead to changes in filter characteristics, negative voltage adjustment effect, heavy weight, large volume, and easy resonance with the system, etc.

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