Observation method and device for electromagnetic torque of salient pole type permanent-magnet brushless direct current motor

Abstract

The invention relates to an observation method and device for an electromagnetic torque of a salient pole type permanent-magnet brushless direct current motor, and is particularly suitable for the electromagnetic torque and rotation speed control of a motor driving system without position sensors or speed sensors. The observation method and the observation device utilize a rotor counter electromotive force self-adapting stator current observation device, a phase-locked loop based rotor rotation speed and position angle observation device, a rotor counter electromotive force / rotor flux / rotor position angle relation curve, a coordinate conversion device, a stator flux computing device and an electromagnetic torque computing device to observe the electromagnetic torque continuously, instantly and accurately when the position sensors are not available, and observe rotor speed and stator flux in an intermediate variable manner simultaneously, so that the sensorless, high-performance and direct-torque control requirements of the motor are met. The observation method and the device have the advantages of good instantaneity, high observation accuracy, low cost and the like.

Description

technical field [0001] The invention relates to the technical field of drive control of permanent magnet brushless DC motors, in particular to a position sensorless electromagnetic torque observation method and device suitable for direct torque control systems of salient pole permanent magnet brushless DC motors. Background technique [0002] Permanent magnet brushless DC motor (BLDCM) has the characteristics of high efficiency and simple control structure, and is widely used in household appliances and industries. However, due to the influence of various factors in the actual manufacturing process, the rotor back EMF is not an ideal waveform (neither trapezoidal nor sine wave), and the use of simple square wave current PWM to control the torque ripple is relatively large, which restricts the expansion of its application field. [0003] In order to improve the driving performance of permanent magnet brushless DC motors, direct torque control strategies are proposed for this ...

AI Technical Summary

Problems solved by technology

Of course, for the permanent magnet brushless DC motor whose magnetic salient pole phenomenon is not obvious, this neglect will not bring too much electromagnetic torque observation and control error

However, in practical applications, many permanent magnet brushless DC motors have serious magnetic saliency phenomenon. If the magnetic saliency phenomenon is still ignored, it will inevitably bring large electromagnetic torque observation and control errors, which will greatly affect the drive of this type of motor. The operating performance of the system, such as reduced load capacity of the motor, unstable steady-state speed, etc.

Therefore, for the salient pole permanent magnet brushless DC motor, the key technology to realize its direct torque control is also the continuous, real-time and accurate observation of the electromagnetic torque, but two factors make it very difficult to observe the electromagnetic torque of this motor: 1) The magnetic saliency phenomenon of the motor makes the mathematical model of the motor a time-varying nonlinear system related to the rotor position angle; 2) The rotor back electromotive force and the rotor flux linkage are serious non-sinusoidal waves

These two factors lead to the fact that the existing electromagnetic torque observation method in permanent magnet brushless DC motors that ignores the magnetic saliency phenomenon is not suitable for salient pole permanent magnet brushless DC motors.

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