A unilateral controllable common bus open-winding permanent magnet motor system and its zero-sequence current suppression method

Abstract

The invention discloses a co-bus winding opening permanent magnet motor system with one side controllable and a zero sequence current suppression method of the co-bus winding opening permanent magnet motor system with one side controllable. The winding opening permanent magnet motor system is of a co-direct-current power source structure, the zero sequence current can be suppressed by designing a proportion resonant controller, a full-control converter and a non-control converter are adopted for the system, the capacity of the system is increased while cost is reduced, the system only relates to one direct-current power source which does not need to be isolated, only a control algorithm is modified for zero sequence current suppression, and the hardware cost of the system does not need to be increased. Meanwhile, according to the zero sequence current suppression method, a current loop structure is designed directly based on zero sequence current detection, and the method is easy to control and high in stability. Compared with a traditional structure, the complexity of the system is reduced, cost is reduced, the capacity of the system is increased, meanwhile, under the condition that no hardware is added, the problem that permanent magnet counter emf contains third harmonics is well solved, the control method is simple, and the anti-jamming capability is high.

Description

technical field [0001] The invention belongs to the technical field of motor control, and in particular relates to a unilaterally controllable common busbar open-winding permanent magnet motor system and a zero-sequence current suppression method thereof. 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] In ...

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, when the two converters share the same DC power supply, there is a zero-sequence current loop in the corresponding structure, and because there is a back EMF third harmonic in the permanent magnet motor, there will be a zero-sequence current flowing in the system, resulting in low system efficiency and bearing Fever and other issues

At the same time, the system uses two fully-controlled converters. Since the fully-controlled power electronic devices are expensive and the capacity is much smaller than that of uncontrolled power electronic devices, the cost of this structure is high and the capacity is limited.

[0004] Based on the above considerations, in order to reduce the system cost, increase the system capacity and suppress the zero-sequence current at the same time, some people propose to connect the inductor in series with the three-phase circuit to suppress the magnitude of the third and higher harmonic current. However, adding the inductor in series will increase the system hardware cost and complexity, while also increasing system losses and reactive power

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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