Method for detecting position of rotor in lower-speed state of brushless dc motor without position sensing device

Abstract

The invention discloses a method for detecting the position of a rotor in the lower-speed state of a brushless dc motor without a position sensing device. Firstly the initial position of the rotor is determined in the pulse positioning method, the next voltage vector is conducted to make the motor to rotate. Then the rotating speed threshold V1 of the motor is set, when the actual rotating speed v is less than V1, the motor is in the lower rotating speed running state. The current position of the rotor is judged under the lower rotating speed running state of the motor by the maximum probability method, namely the detected effective counterelectromotive force vector is counted in the T1 time, the counterelectromotive force vector corresponding to the maximum counting value is the current position of the rotor. The method is adopted for realizing the stable and reliable start-up of the brushless dc motor without the position sensing device in the normal carrying range, having simple control and easy realization.

Description

technical field [0001] The invention discloses a method for detecting the position of a rotor of a brushless DC motor without a position sensor in a low-speed running state, and is especially suitable for detecting the position of the rotor of a brushless DC motor without a position sensor in an electric vehicle running at a low speed. Background technique [0002] Brushless DC Motor (BLDCM) has the advantages of no commutation spark, reliable operation, convenient maintenance, and simple structure, so it has been widely used in many occasions. But the traditional BLDCM needs an additional position sensor to detect the rotor position, which brings many adverse effects to its application. Therefore, the position sensorless control technology of BLDCM has become a relatively popular research topic at home and abroad in recent decades. The core of BLDCM position sensorless control research is to construct the rotor position signal detection circuit, which indirectly obtains re...

AI Technical Summary

Problems solved by technology

These starting methods solve the commutation problem of the motor under static and low-speed running conditions, but their disadvantages are also obvious, that is, the range of adaptation to the load change is small when starting, and the stability and flexibility of the motor operation are difficult to be effectively guaranteed.

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