A built-in permanent magnetic brushless DC motor control system for no position sensor

Abstract

The invention relates to an embedded permanent brushless DC motor non-position sensor control system, composed of a microprocessor controller, a IPM module and a drive unit, a current detection circuit, a phase voltage detection circuit, an output display circuit, a control input circuit, an embedded rotor structured permanent brushless DC motor, a drive and control power source, etc. The invention judges the position of rotor by detecting variation of inductance of stator winding indirectly according to the character that the inductance of rotor winding of the embedded rotor structured permanent brushless DC motor is the function of rotor position theta. In the embedded rotor structured permanent brushless DC motor with star-shaped connection adopted by stator winding, when self inductance of two phase windings therein are equal, the position is the counter potential zero-crossing point without phase connection. Therefore, adopting non-connection phase voltage to ground continuously in one PWM period, and comparing the difference value, to judge non-connection phase counter potential zero-crossing point, and lagging behind for 30 degrees electric angel as phase-exchange time of next time. The method of the invention is indirect induction method. The non-position sensor control method of indirection induction method is nothing to do with rotating speed of motor, so that the invention overcomes the problem of malfunction at low speed of the conventional non-position sensor control method-the detection method of counter potential zero-crossing point. The invention can work reliably at ultra-low speed even if the rotating speed of motor is close to zero.

Description

technical field [0001] The invention relates to a position sensorless brushless DC motor control system, in particular to a position sensorless control system of a star-connected permanent magnet brushless DC motor with an embedded rotor structure. Background technique [0002] The operation of the permanent magnet brushless DC motor is realized by changing the different trigger combination states of the inverter power device correspondingly with the different positions of the rotor. Therefore, it is the key to control the normal operation of the brushless DC motor to accurately detect the position of the rotor and switch the trigger combination state of the power device on time according to the rotor position. It is the most direct and effective method to use the position sensor as the position detection device of the rotor. The position sensor is one of the components of the brushless DC motor system. Its function is to detect the position of the rotor during motion, conv...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is: in order to solve the problem that the commonly used position sensorless control method - "back electromotive force method" fails in the low speed range or near zero speed range, and provide a kind of working range that can expand the position sensorless control, in extremely low speed (5% of the rated speed) the built-in permanent magnet brushless DC motor control system without position sensor can also work reliably

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