A common mode current suppression circuit for motor drive system

Abstract

The invention belongs to the field of power electronics technology, and provides a common-mode current suppression circuit for a motor drive system, which is used to solve the interference of high-frequency interference generated by controllable rectification and inverters on the motor drive system and its surrounding equipment; the invention includes 3 1 LC filter circuit, transmission device and micro control unit; 3 LC filter circuits are respectively connected in series between the inverter output terminal and the motor input terminal, and each LC filter circuit is composed of an adjustable inductance and a non-polar capacitor in series; the micro The control unit controls the transmission device according to the frequency of the modulated wave signal output by the inverter, and the transmission device individually controls the inductance value of the adjustable inductor in each LC filter circuit through the sliding plate to make the drive current of the motor reach resonance in the LC filter circuit . The invention effectively restrains the common mode current from the total conduction path, realizes the common mode current restraint of the motor driving system; meanwhile, ensures that the driving signal of the motor will not be attenuated.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a common-mode current suppression circuit for a motor drive system. Background technique [0002] With the development of modern society, the requirements for the speed of the motor are getting higher and higher, and the switching frequency of the switching devices in the motor drive system is getting higher and higher. Due to the existence of high-frequency du / dt and parasitic capacitance, it will provide impedance for high-frequency signals Smaller circuits, these high-frequency current signals can cause serious electromagnetic interference (EMI) to the motor drive system. For example, the high-frequency common-mode current forms high-frequency electromagnetic radiation, which causes a certain induced current in the closed loop of surrounding equipment and the system itself. Therefore, in order to ensure that the system can work normally when the motor is...

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Problems solved by technology

[0003] At present, commonly used common-mode current suppression circuits such as figure 2 As shown, three capacitors are connected in parallel between the inverter output terminal and the motor input terminal to provide a high-frequency loop so that the common-mode current can flow away from the capacitor. However, due to the parasitic Capacitors, if parallel capacitors are used to suppress the common-mode current, multiple high-frequency current loops will appear, and at this time, the suppression effect of the common-mode current will be reduced; at the same time, the circuit is equivalent to the original common-mode current loop A small impedance loop is connected in parallel, which will actually increase the common mode current in the entire system, which may make the electromagnetic interference in the system more obvious

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