Decoupling control method for permanent magnet synchronous motor

Abstract

The invention provides a decoupling control method for a permanent magnet synchronous motor. The method includes the following steps that (1) an open-loop transfer function of a current loop controlled object of a motor model is constructed on a space vector coordinate system according to q-axis and d-axis voltage equations of the permanent magnet synchronous motor; (2) a current motor rotation speed is introduced to be added to a current loop of the motor model so that a complex vector PI regulator with a plurality of zero points can be constructed; (3) an integrating factor of the complex vector PI regulator is set in a complex vector PI control method, so that zero points of a transfer function of the complex vector PI regulator are equal to pole points of the open-loop transfer function of the current loop controlled object in number, and motor coupling influences are eliminated. The decoupling control method has the advantages that the structure with the complex vector PI regulator is adopted so that the complex vector PI regulator generates a plurality of zero points in the same quantity as the pole points of the current loop controlled object, cancellation conditions of zero and pole points are met, the motor coupling influences are effectively eliminated, stability of the motor operating at a high speed is improved and the decoupling control method is especially suitable for the field of electric vehicles.

Description

technical field [0001] The invention relates to the field of permanent magnet synchronous motor control, in particular to a decoupling control method for permanent magnet synchronous motors. Background technique [0002] The permanent magnet synchronous motor has been widely used in the field of electric vehicles because of its high power density and wide range of speed expansion. Electric vehicles are mainly concerned with the field weakening multiple and overload capacity of the motor. Generally, the maximum speed of the motor is required to reach 3 times the rated speed, and the maximum load can reach 3 times the rated torque. When the motor speed increases, the field weakening current will increase, and when the motor load increases, the torque current will increase. Under high current and high speed, it will often cause current coupling oscillation. To improve the control quality, the precise decoupling control of the current becomes an important point. [0003] We o...

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Problems solved by technology

But in actual motor parameter L q , L d Unknown, even if known, in the case of high-speed and high-current operation of the motor, the parameter changes greatly. If this parameter is directly used to calculate the coupling item and add it to the current loop output item, the coupling between the dq axes is serious, which seriously affects the current. The quality of control leads to the instability of the motor during high-speed operation, and the reduction of load capacity, which is more likely to cause system instability and current oscillation

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