Method for starting permanent magnet synchronous motor without position sensor

Abstract

The invention relates to a method for starting a permanent magnetic synchronous motor without a position sensor. A method for conducting closed-loop control on a stator flux linkage is used for achieving open-loop control starting of the permanent magnetic synchronous motor. The steps of conducting closed-loop control on the stator flux linkage is that the output voltage Us of a stator is calculated and obtained at last based on an estimated stator flux linkage increment delta psi, detected resistance Rs and a stator current is. When open-loop control starting of the permanent magnetic synchronous motor is conducted, the largest output torque is not affected by loads, and the phenomenon of step falling out of the motor is effectively avoided.

Description

technical field [0001] The invention relates to a starting method of a permanent magnet synchronous motor without a position sensor. Background technique [0002] Permanent magnet synchronous motor is a new type of synchronous motor composed of rare earth permanent magnet materials instead of excitation windings. It has the advantages of simple structure, small size, light weight, high efficiency, large overload capacity, moment of inertia and small torque ripple. The operation control of the permanent magnet synchronous motor requires a position sensor to detect the rotor pole position, and the rotor pole position is detected by the position sensor. According to the detected rotor pole position, the current flows through the stator coils of each phase to generate a rotating magnetic field. The interaction between the magnetic fields of the magnet generates torque from the poles, thereby transferring power to the load. Traditional position sensors usually use mechanical pos...

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Problems solved by technology

However, since the counter electromotive force of the permanent magnet synchronous motor is zero or very small at rest or at low speed, the accurate rotor position cannot be obtained, resulting in the failure of starting the motor. Therefore, other methods need to be set up to realize the starting of the motor. : Three-stage starting method, pre-positioning starting method, frequency-boosting synchronous starting method, and short-time detection pulse rotor positioning starting method, etc. Considering the cost and detection reliability, the three-stage starting method is the most widely used. The working principle is to perform directional control on the rotor, and then perform open-loop control of the voltage-frequency ratio. After starting, switch to the motor closed-loop control operation state. Since the working methods or principles of these starts are different, but because they all adopt the voltage open-loop method Finally, the motor is started. The starting torque of the motor is greatly affected by the load, and the constant starting torque of the motor cannot be guaranteed. The larger the load, the less the maximum output torque of the motor, which will easily lead to the motor out of step.

Moreover, for the three-stage starting method, when the permanent magnet synchronous motor rotor is at a specific position, the directional control cannot control the rotor to the due position, and the motor has a starting dead point problem.

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