Constant torque control method for permanent magnet synchronous motor based on position sensor-less vector control

Abstract

The invention discloses a constant torque control method for a permanent magnet synchronous motor based on position sensor-less vector control. The method includes the following steps: the motor is started and operated, a target current value iq_A of a q-axis is set to be equal to a current given value iq_limit, and constant torque control is achieved by utilizing a current PI control ring of theq-axis; when a torque command value is small or a load becomes heavy, a rotating speed decreases until a real-time detected rotating speed V is less than a preset reference rotating speed Vref1, a constant torque control mode is exited to enter constant rotating speed control, and the rotating speed is intervened through addition of extra current increment delta_iq based on the current given valueiq_limit of the q-axis to make the motor perform constant rotating speed control; and when the real-time detected rotating speed V rises and reaches a stable state, when a rotating speed difference Err is greater than a certain set value E0, the constant rotating speed control is exited to return and reenter the constant torque control. The method can ensure stable rotating speed, and stable operation, and enables vibration and noise of motor operation to be reduced.

Description

Technical field: [0001] The invention relates to a constant torque control method of a permanent magnet synchronous motor based on a position sensorless vector control. Background technique: [0002] At present, there are generally three control methods for position sensorless vector control permanent magnet synchronous motors: constant torque control mode, constant speed control mode, or constant air volume control mode. [0003] For example, U.S. Patent No. 7,525,269 discloses a position sensorless 3-phase synchronous motor motor vector controller, which only discloses a current torque control mode for constant torque control. [0004] Chinese patent CN103929109 (A) also discloses a constant speed control method based on position sensorless vector control permanent magnet synchronous motor. [0005] Such as figure 1 As shown, the general block diagram of constant torque control is shown as figure 1 As shown, since the torque T is only related to the q-axis current, acco...

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Problems solved by technology

[0016] The purpose of the present invention is to provide a permanent magnet synchronous motor constant torque control method based on position sensorless vector control, to solve the problem in the prior art: it is very easy to enter an unstable state due to inaccurate speed estimation at low speed; when the torque command value deviates from When the load becomes heavier, the speed drops, and if the speed is not effectively controlled, it is easy to enter an unstable technical problem

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