Sensorless control method and device for motor

Abstract

The invention discloses a sensorless control method and device for a motor. The sensorless control method comprises the following steps: step 1, setting an initial motor phase current peak value; 2, scanning to obtain a quadrature-axis current within a preset current angle range under a phase current peak value; determining the quadrature-axis current meeting the constraint relationship between the quadrature-axis inductance and the direct-axis inductance, and taking the quadrature-axis current corresponding to the maximum torque as a fitting point; 3, if the phase current peak value does notreach the phase current amplitude limiting value, repeating the step 2 after the current step value is added to the phase current peak value to serve as a new phase current peak value; if so, enteringthe next step; 4, obtaining a maximum torque-current ratio curve through fitting of the fitting points, and applying the maximum torque-current ratio curve to motor control. By adopting the scheme, under the condition of no position sensor, the high-frequency change of the inductance is considered, a new maximum torque-current ratio curve is established and applied, the closed-loop control convergence of the motor is ensured, and the closed-loop stability of the system is still ensured even under the condition of outputting large torque.

Description

technical field [0001] The invention relates to the field of motor control, in particular to a motor position sensorless control method and device. Background technique [0002] When an electric vehicle encounters a position sensor failure, it will use a position sensorless control technology solution to continue to control the operation of the motor. In the zero-speed and low-speed operation stages of the motor, the pulse vibration high-frequency voltage injection scheme can track the rotor position very well. [0003] In the pulse vibration high-frequency voltage injection scheme adopted in the prior art, the inductance used in the equations used to describe the motor model are all constants, so only the current differential term is used in the equation, and the inductance differential term is not considered (the high-frequency change of the inductance is not considered ), it is impossible to express the true characteristics of the inductance under high-frequency current,...

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Problems solved by technology

[0003] In the pulse vibration high-frequency voltage injection scheme adopted in the prior art, the inductance used in the equations used to describe the motor model are all constants, so only the current differential term is used in the equation, and the inductance differential term is not considered (the high-frequency change of the inductance is not considered ), it is impossible to express the true characteristics of the inductance under high-frequency current, but due to the influence of the inductance saturation effect, the high-frequency change of the inductance value of the motor under high-frequency current cannot be ignored. If the maximum torque-current ratio curve obtained from this is used (MTPA, Maximum Torque Per Ampere) load, causing the motor to control divergence under high torque

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