A method for starting a BLDC motor without a position sensor

Abstract

The invention relates to a method for starting a BLDC motor without a position sensor, comprising step A: resetting: selecting a voltage Vds on the ds axis, while maintaining the voltage Vqs=0 on the qs axis, so that the motor returns to a preset position; steps B: In the state where the motor is firmly locked, given a magnetic flux λ of the motor, during the climbing process of the current Iqs of the qs axis, the voltage magnetic flux closed loop of the ds axis is used to control the magnetic flux to keep the magnetic flux constant. Use the torque current closed loop of the qs axis to compare the preset starting torque T0 with the measured torque T1 and perform closed-loop control until the measured torque T1 reaches the preset starting torque T0; Step C: Based on the starting torque T0, use the torque current closed loop The loop continues to increase the torque to make the load rotate, compare the preset starting speed V0 with the measured speed V1 and perform closed-loop control. The invention has closed-loop control throughout the whole process, smooth and even start-up, small start-up current, small impact on current power components, and low noise generated.

Description

[0001] Technical field: [0002] The invention relates to a starting method of a BLDC motor without a position sensor. [0003] Background technique: [0004] Most of the BLDC motors without position sensor are controlled by vector control method. Since the rotor angle / position θ is the key to the conversion of voltage and current in vector control, there are few key elements in the actual operation of the previous position sensorless brushless motor. When the position sensor is a brushless motor, the usual method is to give energy to the motor first, and send the DC current Id to the d-axis (the direct axis of the rotor rotation coordinate system), while maintaining the q-axis (the quadrature axis of the rotor rotation coordinate system) Current Iq is zero. The motor will lock to its original position, defined as the zero time position. Then, it employs an open-loop control mode to control the motor operation, achieves a normal start when it reaches a predefined speed, and t...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a method for starting a BLDC motor without a position sensor, which solves the technical problems in the prior art that the inrush current is large during the start-up stage of the motor, causing inrush current power components and noise, and affecting the working life of the motor.

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