Research On PMSM Speed Estimation Method Based On Current Signal

Rotation Speed is one of the important indicators to evaluate the running status and control performance of the motor system.Therefore,the speed test is of great significance for reducing the cost of motor design and maintenance,monitoring the safe operation of the motor system to avoid industrial accidents,and ensuring personal safety..In the rotation speed test of the motor system,when the speed sensor is inconvenient to install,the current or vibration signal of the motor can be spectrum analyzed to obtain the rotation speed information,but this method has poor tracking performance under the working condition of sudden rotation speed.Therefore,research on a simple,universal,fast and accurate speed test method has certain engineering application value.This paper proposes three speed testing methods,and verifies the feasibility and effectiveness of the proposed method through simulation and experiment.The main research contents are as follows: The stator voltage harmonic characteristics under Pulse Width Modulation(PWM)of the permanent magnet synchronous motor are studied,and a general speed measurement method is proposed based on the idea of the carrier frequency component method in sensorless control.Taking the space vector modulation(Space Vector Pulse Width Modulation,SVPWM)asymmetric regular sampling strategy commonly used in the industry as an example,the demodulated current related to the position of the motor rotor is deduced,and it is found that the amplitude of the demodulated component has nothing to do with the difference in inductance.Therefore,it is commonly used in permanent magnet synchronous motors;at the same time,the proposed method is not limited to motor control methods and has a wide range of speed testing.Aiming at the motor controlled by pulsating high-frequency injection method in the coordinate system,a speed test method is proposed.Since the current modulation component near the injection frequency in the high-frequency injection method is related to the motor speed,and its amplitude is higher than the carrier frequency,selecting the modulation component near the injection frequency for speed extraction can obtain a more accurate estimation result;An optimization solution method for the rotation angle is proposed,which improves the anti-noise interference ability of the rotation angle extraction;after the rotation angle is obtained,a more accurate rotation speed estimation value can be obtained in real time through Kalman filter.Compared with the speed test method based on the carrier frequency component,the proposed method eliminates the complicated PI parameter tuning process and integration link.Aiming at the motor controlled by pulsating high-frequency injection method in the coordinate system,a speed test method is proposed.The idea of speed construction is the same as that of the high-frequency pulse injection method under the coordinate system,but this method is only suitable for embedded permanent magnet synchronous motors with structural salient poles.Corresponding theoretical analysis,simulation and experimental verification are carried out on the three speed estimation methods.The proposed method only needs to simply collect the three-phase current of the permanent magnet synchronous motor to obtain the real-time and accurate estimated speed,which is of great significance to the speed test and research of the motor system.