Brushless direct current motor electromagnetic torque observation method based on self-adapting slipform observer

Abstract

The invention discloses a brushless direct current motor electromagnetic torque observation method based on a self-adapting slip-form observer, belonging to the control field of permanent magnet motors. The observation method comprises the following steps of: constructing a state space equation of a brushless direct current motor in an alpha-beta coordinate system based on easily-observing signals, such as motor rotating speed, each phase current of a stator, each ground voltage of the stator, rotor position, and the like; observing a counter emf (Electromotive Force) of the brushless direct current motor in the alpha-beta coordinate system in real time by using the slip-form observer; meanwhile online identifying a stator resistance parameter of the brushless direct current motor to eliminate the influence of a resistance parameter error on counter emf observation; and finally calculating the electromagnetic torque of the brushless direct current motor in real time according to the counter emf, the current and the rotating speed. In the invention, when the stator resistance parameter is unknown or a stator resistance changes due to the influences of temperature and skin effect, the counter emf and the electromagnetic torque of the brushless direct current motor can be accurately observed, the problem of the traditional method influenced by the resistance parameter is solved, and an accurate torque feedback value can be provided for the torque close loop control of the brushless direct current motor.

Description

technical field [0001] The invention relates to an electromagnetic torque observation method of a brushless DC motor, which belongs to the field of permanent magnet motor control. Background technique [0002] The ideal back EMF waveform of the brushless DC motor is a trapezoidal wave, which is controlled by a 120° conduction mode, and a constant torque can be generated when a square wave current is passed. However, due to the design or manufacture of the motor, the actual back EMF waveform of the brushless DC motor is not an ideal trapezoidal wave, let alone a sine wave. When a square wave current is applied, low-frequency torque ripple will be generated. In order to reduce the torque ripple of the brushless DC motor, the method of closed-loop control of the electromagnetic torque of the brushless DC motor is widely used at present, which requires real-time calculation of the electromagnetic torque. [0003] The formula for calculating the electromagnetic torque of a brush...

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Problems solved by technology

[0016] The purpose of the present invention is to solve the problem that the observation accuracy of the electromagnetic torque of the brushless DC motor is affected by the deviation of the stator resistance in the prior art, and to provide a brushless DC motor electromagnetic torque based on an adaptive sliding mode observer with a resistance parameter identification function. method of moment observation

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