A Field Weakening Control Method for Enhanced Permanent Magnet Synchronous Motor

Abstract

The invention discloses a field weakening control method of an enhancement type permanent magnet synchronous motor. The field weakening control method is the method that current closed-loop control is carried out on an inner ring, voltage closed-loop field weakening control is carried out on an outer ring in a combined mode, in particular, the virtual voltage is used as voltage feedback, and voltage error feedforward control is increased, wherein a torque current command iqref and a first exciting current command idref1 which are used for the current closed-loop control are respectively obtained according to a current amplitude command isref, and controlled accordingly to the maximum torque current ratio at the speed lower than the base speed; a second exciting current command idref2 is obtained according to stator voltage closed-loop control, and the field weakening control over the second exciting current command idref2 is achieved at the speed higher than the base speed; dynamic responses of the field weakening control is improved by designing feedforward orientation angle delta theta control according a voltage error value delta u, the field weakening control accuracy is greatly improved, and the flux weakening area current dynamic response speed is greatly increased; control at the speed lower than the base speed and control at the speed higher than the base speed are organically fused, and a large-output torque and high-speed operation integrated control method is formed. The field weakening control method can be widely used for driving control of electric cars.

Description

technical field [0001] The invention relates to a field-weakening control method of a synchronous motor, in particular to a field-weakening control method of an enhanced permanent magnet synchronous motor for an electric vehicle. Background technique [0002] With the depletion of non-renewable energy sources such as oil and natural gas, new energy technologies have been vigorously developed. Electric vehicles driven by new energy instead of traditional fossil fuels are the mainstream development direction of the future automobile industry. Permanent magnet synchronous motors are more and more used in the drive of electric vehicles because of their high efficiency, good reliability and many other advantages. In practice, in order to meet the low-speed climbing requirements of electric vehicles, the motor control needs to achieve low-speed high-torque control; at the same time, in order to meet the high-speed operation of electric vehicles, the motor control also needs to ac...

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Problems solved by technology

However, this control method has shortcomings. First, due to the influence of nonlinear characteristics such as the dead zone of the inverter, the reference voltage is not equal to the actual voltage, thereby reducing the control accuracy of the voltage closed-loop field weakening; second, it does not consider The problem of dynamic response to the current in the field weakening area greatly reduces the control effect

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