A Suppression Circuit of Common Mode Voltage at Motor Terminal of Frequency Converter Drive System

Abstract

The invention discloses a circuit for suppressing the common-mode voltage at the motor end of a frequency converter drive system, comprising: a frequency converter, and a common-mode filter connected to the output terminal of the frequency converter; wherein, the inductance of the common-mode filter connected in series at the output end of the frequency converter; the neutral points of the two resistor-capacitor circuits of the common-mode filter are respectively connected to the positive and negative terminals of the DC bus of the frequency converter; the present invention uses the two resistor-capacitor circuits The neutral point is respectively connected to the positive and negative terminals of the DC bus of the inverter. This topology common-mode filter can suppress the common-mode voltage at the motor end of the inverter drive system without disassembling the inverter. It is practical and operable, and the common-mode filter set by this topology can produce a better suppression effect on the common-mode voltage and improve user experience. In addition, the present invention also discloses a frequency converter drive system, which also has the above beneficial effects.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a circuit for suppressing the common-mode voltage at the motor end of a frequency converter drive system and the frequency converter drive system. Background technique [0002] With the continuous development of power electronics technology and control theory, the comprehensive performance of PWM inverters has been greatly improved, and PWM inverters have been widely used in industry and energy fields. However, due to the use of PWM modulation technology, frequency control has many negative effects on the drive system. Under the PWM modulation strategy, there is a high-frequency common-mode voltage in the output of the inverter. Under the coupling effect of the motor parasitic capacitance, the voltage induces a shaft voltage on the motor shaft, and then causes a shaft current, causing electrical corrosion of the bearing and seriously endangering the variable frequency d...

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Problems solved by technology

[0003] In the prior art, most inverters are packaged as a whole, and there is no connection terminal for the neutral point of the DC bus. Because the existing LRC passive filter needs to connect the neutral point of the star-connected resistor-capacitor circuit to the inverter DC bus neutral point connection, if the reference point of the DC bus neutral point needs to be obtained, the inverter must be disassembled, which increases the difficulty of testing and does not have practical operability, and when the traditional filter is used, the total The suppression effect of the mode voltage is not obvious enough

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