A method for suppressing zero-sequence current of open-winding permanent magnet motor with common bus based on proportional resonance control

Abstract

The invention discloses a proportion resonance control based method for inhibiting zero sequence currents of a common bus winding permanent magnetic motor. The method is based on a permanent magnetic motor in a winding structure, employs a common DC source structure, and realizes the purpose of inhibiting the zero sequence currents through the design of a proportion resonance controller. A system only relates to one DC source and does not have to be isolated, the inhibition of the zero sequence currents only involves modification in a control algorithm, and the system hardware cost is not increased. At the same time, according to the zero sequence inhibition method is directly based on detection of the zero sequence currents, a current enclosed ring structure is designed, the control is simple, and the stability is high. Compared to a conventional structure, the system complexity is reduced, the cost is reduced, at the same time, under the condition that hardware is not increased, the problem that a permanent magnet counterelectromotive force comprises triple harmonic waves, the control method is simple, and the anti-interference capability is high.

Description

technical field [0001] The invention belongs to the technical field of motor control, and in particular relates to a method for suppressing the zero-sequence current of a common-bus open-winding permanent magnet motor based on proportional resonance control. Background technique [0002] Due to the emergence of permanent magnet materials with high magnetic energy density such as AlNiCo, ferrite and NdFeB, permanent magnet motors have achieved unprecedented development and growth. At the same time, the permanent magnet motor abandons devices such as brushes and collector rings, and does not require excitation windings and excitation power supplies, which greatly reduces the loss of the motor and improves the operational reliability of the motor. Due to its high power density, high efficiency, simple structure and reliable operation, permanent magnet motors have been widely used in various fields such as aerospace, automobiles, national defense and power generation. [0003] ...

AI Technical Summary

Problems solved by technology

The structure of the traditional open-winding permanent magnet motor system is as follows: figure 1 As shown, under this structure, the two converters are respectively connected to two isolated DC power supplies. Due to the isolation of the two DC power supplies, there is no zero-sequence current loop in the system. Even if there is a third harmonic in the voltage, no zero-sequence current loop will be generated sequence current, but since the system requires two isolated DC sources, it increases the complexity and cost of the system

However, if figure 2 As shown, when the two converters share the same DC power supply, there is a zero-sequence current loop in the corresponding structure, and because of the third harmonic of the back EMF in the permanent magnet motor, there will be zero-sequence current flow in the system, resulting in low system efficiency , bearing heating and other issues

[0004] Based on the above considerations, in order to suppress the zero-sequence current, some people propose to connect inductors in series with the three-phase circuit to suppress the magnitude of the third and higher harmonic currents. However, adding inductors in series will increase the hardware cost and complexity of the system. At the same time, it will Increase the loss and reactive power of the system

It has also been suggested that when using voltage space vector modulation, the vector without common-mode voltage is used for modulation to eliminate the zero-sequence voltage generated by the inverter. This method is suitable for induction motors, but for permanent magnet motors, the permanent magnet back EMF There is a third harmonic that cannot be suppressed. At the same time, this method is only based on open-loop control, which is easily affected by various disturbances and has large errors.

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