Motor drive device

Abstract

Problems with accuracy reading position detection signal peaks and minute phase differences in the detection current make motor drive control easily susceptible to differences in motor characteristics. The rotor position is determined based on whether or not a neutral point difference voltage, which is the difference voltage between the neutral point voltage and the pseudo-neutral-point voltage when the motor phases are selectively energized, exceeds a specific threshold value. The phase energized to start the motor is determined based on this determination and the motor is energized accordingly to start. Instead of switching directly from the search step at the initial rotor position to the back-EMF voltage mode, a search and start mode that creates initial rotor speed sufficient to start the motor is executed before entering the back-EMF voltage mode.

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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