Zero-speed protection device and zero-speed detection method for permanent magnet synchronous motor

Abstract

The invention discloses a zero-speed protective device for a permanent magnet synchronous motor. The zero-speed protective device comprises a back electromotive force detection module, a zero-speed judgment module and a zero-speed protective module, wherein the back electromotive force detection module is used for detecting back electromotive force of the permanent magnet synchronous motor; the zero-speed judgment module is connected with the back electromotive force detection module and used for comparing the back electromotive force of the permanent magnet synchronous motor with a preset threshold value and judging whether the permanent magnet synchronous motor is in a zero-speed state or not according to a comparison result; the zero-speed protective module is connected with the zero-speed judgment module and used for outputting a zero-speed protective signal to close a control signal input to the permanent magnet synchronous motor when the permanent magnet synchronous motor is in the zero-speed state. Therefore, the zero-speed protective device for the permanent magnet synchronous motor can detect the zero-speed state of the permanent magnet synchronous motor, so that an overheating or demagnetization phenomenon caused by electrification of the permanent magnet synchronous motor in the zero-speed state is avoided. The invention further discloses a zero-speed detection method for the permanent magnet synchronous motor.

Description

technical field [0001] The invention relates to the technical field of motors, in particular to a zero-speed protection device for a permanent magnet synchronous motor and a zero-speed detection method for a permanent magnet synchronous motor. Background technique [0002] Permanent magnet synchronous motors are more and more widely used because of their advantages such as large power inertia ratio, high efficiency, and wide speed range. Permanent magnet synchronous motors are usually vector controlled to improve their efficiency. However, vector control needs to obtain the position information of the permanent magnet synchronous motor rotor. For example, the angle of the motor rotor can be directly measured through angular position sensors such as encoders and resolvers. However, these angle sensors will increase the cost of the system. In addition, in some special applications, such as in compressor control, the angle sensor cannot be installed due to the high temperature...

AI Technical Summary

Problems solved by technology

But its disadvantage is that the permanent magnet synchronous motor needs to have a certain speed to ensure that the back electromotive force or the rate of change of magnetic flux is within a detectable range

Once the speed of the PMSM is zero, the position estimator cannot estimate an accurate position estimate

If the frequency conversion module is still transmitting power to the permanent magnet synchronous motor at this time, it may input voltage to the permanent magnet synchronous motor in the wrong direction, which will cause the permanent magnet synchronous motor to overheat or even demagnetize

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