Motor drive method

Abstract

A motor driving method is provided. A rotor position is determined based on whether or not a neutral point voltage difference, or a voltage difference between neutral point voltage and pseudo neutral point voltage exceeds a predetermined threshold when an energization phase is sequentially selected and energized. The energization phase for starting a motor is determined based on the result of this determination, and the motor is energized and started according to the determined energization phase. The operation mode is not changed directly from a step for searching the initial position of the rotor to a counter electromotive voltage mode. Instead, a search start mode for supplying appropriate rotational speed to the initial startup of the motor is once established, and then the mode is changed to the counter electromotive voltage mode. Following problems are solved: a problem of the correctness of a peak value of a position detection signal taken in; a problem of proneness to be influenced by a variation in motor characteristics caused by the slightness of differences in detection currents between phases; and a problem that methods of comparing voltage differences determined with respect to each group of measured voltages that occurs at a neutral point of motor windings each time a detection signal is applied to determine a large voltage difference require a reference table and high computing power.

Description

technical field [0001] The present invention relates to a three-phase brushless motor drive technology capable of stably and rapidly starting without a rotor position sensor. Background technique [0002] In the brushless motor, the stator selects an appropriate coil, and flows a current to provide a stable torque to the rotor. Therefore, the electrical relative position of the rotor to the stator is required. In order to know this relative position, various rotor position sensors are used. On the other hand, in terms of reliability, cost increase, and environmental resistance, sensorless drive technology that does not require a rotor position sensor has also been developed. Among such sensorless driving techniques, there is generally known a technique of detecting a rotor position by reading a reverse induced voltage generated in a stator phase coil when the rotor rotates. However, since the reverse induced voltage is not generated when the rotor is stopped, various dete...

AI Technical Summary

Problems solved by technology

Therefore, it is difficult to apply when obtaining autonomous controllability or an inexpensive motor drive system from the motor.

[0016] In Patent Document 3, there is a problem that there is an area where the rotor position cannot be detected

In this area, the motor stops when starting, no matter how the rotor search pulse is applied, the motor may be in a stopped state, resulting in the problem of not being able to start

In addition, when the rotor position cannot be detected correctly like this, even if the initial position search process of the rotor position is switched to the reverse induced voltage mode, there is a problem of reverse or step deviation.

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