Starting method for brushless DC motor without position sensor based on current feedback

Abstract

The invention discloses a starting method of a brushless, position sensor- free DC motor based on current feedback. The method comprises the steps as follows: a rotor is pre-positioned; the direction changing and the current converting are carried out; a preset voltage value is calculated according to a pressure-raising curve and is output in the form of PWM; the direction changing and the current converting are carried out when detection shows that a phasing current value I exceeds a predetermined value IH, and the preset voltage value in the next step is calculated at the same time according to the pressure-raising curve; and an electric motor is switched over to closed-loop operation when the current converting frequency is greater than the predetermined value, that is, rotational speed is high enough to obtain a back-EMF signal. Based on the real-time detection on the starting current, the technical proposal of the starting method obtains better starting performance compared with a traditional three-step starting method, ensures the stability and controllability of Delta during the whole accelerating process, leads the starting current to be more stable, enables the accelerating process to be smoother, automatically reduces the rotational speed and the Delta so as to obtain greater electromagnetic torque without desynchronizing when meeting with load disturbance, and does not need to add extra hardware or timers, thereby being simpler and more reliable.

Description

technical field [0001] The invention belongs to the technical field of motor control, in particular to a starting method of a position sensorless brushless DC motor based on current feedback. Background technique [0002] The operation of the brushless DC motor needs to detect the actual position of the rotor to realize the commutation of the winding, so a rotor position detection device is generally required. A more advanced technology is to use position sensorless control technology, which saves the position detection device, so that the system cost is lower and the reliability is higher. At present, a variety of control methods for brushless DC motors without position sensors have been studied at home and abroad. However, since the back EMF of the motor is very small at zero speed or low speed, it cannot be detected, so all position sensorless control technologies based on back EMF or its harmonics are not applicable at standstill or low speed, and require special starti...

AI Technical Summary

Problems solved by technology

It can be seen from Table 1 that with the continuous decrease of δ, Te will drop rapidly, which will directly lead to out of step;

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