A model predictive flux linkage control method for semi-controlled open-winding permanent magnet synchronous generators

Abstract

The invention discloses a semi-controlled open-winding permanent magnet synchronous generator model prediction flux linkage control method. First, obtain the reference torque T through the voltage regulator e ref , according to i d = 0 control mode and flux equation calculation to get the stator flux amplitude reference value ψ s ref and load angle reference value δ ref , and then obtain the stator flux d-axis, q-axis and zero-axis component amplitude reference values ​​at (k+1) time; then, according to the prediction model and combined with the flux equation, online prediction of the stator flux d-axis at (k+1) time , q-axis and zero-axis components, use the reference value and predicted value of the stator flux d-axis, q-axis and zero-axis components at (k+1) time to establish a value function; finally, obtain the optimal value of the inverter by minimizing the value function switch signal. The method of the invention avoids the selection of weight coefficients in the value function, reduces system complexity, and effectively solves the problem of zero-sequence current in the common DC bus structure of open-winding motors.

Description

technical field [0001] The invention relates to a semi-controlled open-winding permanent magnet synchronous generator model prediction flux linkage control method, which belongs to the field of motor drive and control. Background technique [0002] The open-winding motor is to open the neutral point of the traditional three-phase motor to form an open winding structure with two ports. The magnetic circuit and structure of the motor have not changed. After the point is opened, the constraint relationship between the motor windings no longer exists, and the windings are independent, which can improve the reliability of the motor body and the fault tolerance of the motor drive system to a certain extent. The two interfaces of the motor are respectively connected to the converter, and through the coordinated control of the converters at the two ports, the power can be distributed to the two converters, which better meets the needs of the high-power motor system for the converter...

AI Technical Summary

Problems solved by technology

However, for this half-controlled open-winding motor system, in the case of a common DC bus, the common-mode voltage generated by the modulation of the converter and the third harmonic of the back EMF cause the system to generate circulating zero-sequence current, which brings Therefore, in the control of open-winding motors, the suppression of zero-sequence current is an important content

[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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