Electric machinery system

Abstract

An electric machine system 1 comprises: an electric machine 2 that includes a rotor 21 and a coil 221; a power converter 3 that outputs an output current to the coil 221 of the electric machine 2; and a controller 4 that controls the power converter 3. The controller 4 comprises: a signal output unit 42 that outputs, to the power converter 3, a signal for controlling the form of an output current; and an abnormality detection unit 41 that, in an abnormal situation in which the occurrence of a failure current generated in the coil 221 by rotation of the rotor 21 should be inhibited, receives an abnormality signal θ1 indicating the abnormal situation. When the abnormality detection unit 41 has received the abnormality signal, the signal output unit 42 outputs a demagnetization control signal φ2 to the power converter 3. In accordance with input of the demagnetization control signal φ2, the power converter 3 causes a demagnetization current to flow through the coil 221 for a demagnetization magnetic flux D3 that demagnetizes a permanent magnet 211 of the rotor 21.

Claims

1. An electric motor having a rotor that includes a magnet and rotates together with a shaft, and coils fixedly arranged to surround the rotor, A power converter that outputs an output current to the coil of the electric machine, The system includes a controller for controlling the power converter, The controller is, A signal output unit that outputs a signal to the power converter for controlling the mode of the output current, An abnormality detection unit that receives an abnormal signal indicating an abnormal situation, The rotor has a demagnetization evaluation unit that evaluates the degree of irreversible demagnetization of the magnets, When the abnormality detection unit receives the abnormality signal, the signal output unit outputs a demagnetization control signal to the power converter. The power converter, upon input of the demagnetization control signal, causes a demagnetizing current to flow through the coil for a demagnetizing flux that demagnetizes the magnets of the rotor. The demagnetization evaluation unit stops the application of the demagnetizing magnetic flux for a predetermined period of time, acquires a fault current generated in the coil based on the magnetic flux generated by the magnet that has undergone irreversible demagnetization while the application of the demagnetizing magnetic flux is stopped, and, as a result of comparing the fault current with a threshold, stops the output of the demagnetization control signal if the magnitude of the fault current is less than or equal to the threshold.

2. The electric motor system according to claim 1, wherein the power converter, upon input of the demagnetization control signal, causes the coil to pass a demagnetizing current for the demagnetizing flux, which includes a first demagnetizing flux component that is in the opposite direction to the direction of the magnetic field generated by the magnet and synchronized with the rotation of the magnet.

3. The electric motor system according to claim 2, wherein the power converter controls, in response to the input of the demagnetization control signal, the current flowing through the coils surrounding the rotor that are located at a position where the d-axis component is greater than the q-axis component relative to the rotor is greater than the current flowing through the coils that are located at a position where the q-axis component is greater than the d-axis component.

4. The electric motor system according to claim 3, wherein the power converter does not pass current through coils located at positions where the q-axis component is greater than the d-axis component.

5. The electric motor system according to claim 2, wherein the intensity of the demagnetizing flux including the first demagnetizing flux component is such that irreversible demagnetization occurs to the magnets of the rotor.

6. The electric motor system according to claim 1, wherein the demagnetization control signal causes the power converter to output to the coil a demagnetizing current for the demagnetizing flux, which includes a second demagnetizing component of alternating current linked to the magnet of the rotor.

7. The shaft is connected to the rotation mechanism of the prime mover at a position different from the position where the rotor is installed. The shaft receives power transmitted from the rotating mechanism to rotate the rotor, The electric motor system according to claim 1, wherein the electric motor generates electricity due to the rotation of the rotor.

8. An electric motor having a rotor that includes a magnet and rotates together with a shaft, and coils fixedly arranged to surround the rotor, A power converter that outputs an output current to the coil of the electric machine, The system includes a controller for controlling the power converter, The controller is, A signal output unit that outputs a signal to the power converter for controlling the mode of the output current, It has an abnormality detection unit that receives an abnormality signal indicating an abnormal situation, When the abnormality detection unit receives the abnormality signal, the signal output unit outputs a demagnetization control signal to the power converter. The power converter, upon input of the demagnetization control signal, causes a demagnetizing current to flow through the coil for a demagnetizing flux that demagnetizes the magnets of the rotor. The power converter, upon input of the demagnetization control signal, causes the coil to pass a demagnetizing current for the demagnetizing flux, which includes a first demagnetizing flux component that is in the opposite direction to the direction of the magnetic field generated by the magnet and synchronized with the rotation of the magnet. The power converter is an electric motor system that, upon input of the demagnetization control signal, controls the current flowing through the coils surrounding the rotor that are located at a position where the d-axis component is greater than the q-axis component relative to the rotor, so that the current flowing through the coils that are located at a position where the q-axis component is greater than the d-axis component is greater than the d-axis component.

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