Hall-free method for starting servo motor

Abstract

The invention discloses a hall-free method for starting a servo motor. The hall-free method includes steps of firstly, perturbing the servo motor and sequentially providing basic torque vectors; and secondly, judging an electric angle sector where a rotor is currently located according to a turning result fed by an incremental encoder, providing an electric angle initial value and switching the rotor to be under conventional field-oriented control. Only a tiny perturbation test is required when the motor is electrified and started for the first time, normal operation of a sewing machine is hardly affected, and accordingly the method can be used as an emergency treatment method when the sewing machine cannot be used due to damage of a hall sensor. The hall-free method has the advantages that the perturbation test is carried out for the servo motor, and the location of the rotor is judged by the aid of output of the encoder, so that the rotor can be switched to be under the conventional field-oriented control, the motor is started, operation is simple and convenient, and the production efficiency is high.

Description

technical field

[0001] The invention relates to the technical field of industrial sewing machine control systems, in particular to a method for starting a servo motor without a hall. Background technique

[0002] The industrial sewing machine servo motor code disc is generally equipped with 3 hall sensors and an incremental encoder, where the hall sensor is used for motor startup. The rotor of the servo motor is made of permanent magnets, the commutation of the stator winding is used instead of the commutation of the brush, and the position information of the rotor is sensed by the hall element. The built-in 3 hall elements will output 3 determined voltage signals in real time to represent the rotor position information. The digital control circuit realizes the selective conduction of the drive circuit according to different voltage signals, so that the coil generates a magnetic torque that excites the rotor to rotate. In one cycle, each MOS transistor is turned on for 120°...

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