A torque control method for surface-mounted permanent magnet synchronous motor without current feedback

Abstract

The invention provides a current-feedback-free surface mounted type permanent-magnet synchronous motor torque control method. The method includes the steps of firstly, regularly collecting mechanical angles of a motor rotor in a digital controller, and calculating the angular speed of the rotor; secondly, calculating the required shaft voltage component according to the angular speed, the expected motor output torque value and motor parameters; thirdly, converting the mechanical angles of the rotor into electrical angles according to the calibrated conversion relation, and conducting shafting conversion through the current electrical angle to calculate the required motor three-phase terminal voltage; fourthly, completing the output of the three-phase terminal voltage through a PWM inverter so that the output control of the electromagnetic torque can be achieved. According to the method, the current vector coordinate conversion and current feedback control process is replaced with the open loop voltage vector control method, no current sensors or current-controllable PWM inverters need to be used, the good torque control effect can be achieved within the wide rotating speed range, and the method is particularly suitable for low-bandwidth precise servo control systems with the high requirement for circuit reliability.

Description

technical field [0001] The invention belongs to the field of motor servo control, and relates to a torque control method of a permanent magnet synchronous motor. Specifically, in the drive control of a permanent magnet synchronous motor, an open-loop voltage vector control method is used to replace the current vector coordinate transformation and The current feedback control process is used to simplify the hardware structure and improve reliability, and to achieve good torque control effect in a wide speed range. Background technique [0002] The permanent magnet synchronous motor has the advantages of simple structure and small torque fluctuation, and is especially suitable for precision motion servo applications in the aerospace field that require high reliability and motion stability. But its disadvantage is that the control method is complex, and it needs to be equipped with high-resolution rotor position sensors, current sensors, and PWM inverters with fast current cont...

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Problems solved by technology

But as long as ω r Slightly higher, according to formula (2), then i q with u q is no longer linear, and there is no guarantee that i d = 0, so u cannot be simply adjusted linearly q Achieve good control of output torque

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