Direct torque control method for brushless direct current motor

Abstract

The invention discloses a direct torque control method for a brushless direct current motor. By speed and torque double closed loop control, a rotating speed loop is used as an outer loop, and a torque loop is used as an inner loop; motor speed is calculated according to an output signal of a Hall sensor of the brushless direct current motor, and the motor speed is compared with reference speed to obtain speed error; an output value obtained after fuzzy self-adaptation adjustment is used as a torque expectation value; torque error is obtained by subtracting actual torque from expectation torque, wherein the actual torque is calculated by multiplying back-EMF (Electromotive Force) and phase current; the torque error is inputted into a hysteresis comparator; the hysteresis comparator outputs a position signal of a rotor; and an appropriate voltage vector is selected from a formulated switch list to control an inverter bridge connected with a DC power supply so as to make the brushless direct current motor output stable torque. By the method, the defect that current hysteresis control has a poor effect of inhibiting electromagnetic torque is avoided, and the problem that a traditional PID control method has low precision and poor anti-jamming capability in control of BLDCM is overcome.

Description

technical field [0001] The invention relates to a direct torque control method of a brushless DC motor. Background technique [0002] As a kind of permanent magnet synchronous motor, brushless DC motor not only has the advantages of simple structure, reliable operation and convenient maintenance of AC motor, but also has the advantages of high operating efficiency, no excitation loss and good speed regulation performance of DC motor. Due to some disadvantages brought by mechanical brushes of DC motors, it is more and more widely used in various fields of national production. The brushless DC motor is a multi-variable, strongly coupled nonlinear system, and it is difficult to meet the actual requirements by classical control theory. The most prominent problem with brushless DC motors is torque ripple. Torque ripple brings vibration, resonance, noise and other problems, which reduces the control characteristics and reliability of the electric drive system, thus limiting the ...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problems existing in the prior art, the present invention proposes a new type of direct torque control method for brushless DC motors, which avoids the defect that current hysteresis control has a poor suppression effect on electromagnetic torque, and overcomes the traditional PID control method. The method has the problems of low precision and poor anti-interference ability when controlling the brushless DC motor, which saves the observation and control of the stator flux linkage, and at the same time has the characteristics of simplified structure and low cost

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