JPH1138103A - Method for inspecting permanent-magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect a permanent-magnet motor for the impedance dispersion of its stator winding by making a direct current flow to the stator winding after a rotor is magnetized and, after the position of the rotor is decided from the attracting action between an electromagnet, which is generated by the direct current and the permanent magnet of the rotor, impressing a surge voltage upon the stator winding. SOLUTION: In the state where a rotor 2 is assembled with a stator 1, the rotor 2 is magnetized by making a magnetizing current flow to a stator winding 5. When a direct current is made to flow to the two phases of the winding 5 thereafter, a magnetic flux flows and the rotor 2 is moved and positioned by the attracting action between the magnetic flux and the permanent magnet of the rotor 2. After the rotor 2 is positioned, the stator winding 5 of the stator 1 is inspected for impedance dispersion by impressing a surge voltage upon the winding 5. The magnitude of the direct current is adjusted to the minimum value that can correct the positional deviation of the rotor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a stator winding of a permanent magnet motor using a reluctance torque in addition to a magnet torque by employing a rotor structure having a reverse saliency.

[0002]

2. Description of the Related Art Conventionally, a rotor structure having a reverse saliency is formed by embedding a permanent magnet in a rotor core made of a material having a high magnetic permeability such as iron, so that reluctance torque is used in addition to magnet torque. Permanent magnet motors are known. FIG. 7 is a structural cross-sectional view of a permanent magnet motor having a reverse saliency and a three-phase four-pole winding as a structure for effectively utilizing reluctance torque. In this permanent magnet motor, the rotor 2 is configured by embedding permanent magnets 3a and 3b in a rotor core 7 formed of an iron core made of a high magnetic permeability material or laminated electromagnetic steel plates. The rotor 2 generates a magnet torque and a reluctance torque by the rotating magnetic field generated by the winding 5 applied to the stator 1 and rotates the rotor 2.

[0003] Incorporating the magnetized rotor 2 into the stator 1 requires a great deal of labor. Therefore, after assembling the rotor 2 into the stator 1, a large current is instantaneously passed through the winding 5 of the stator 1. The permanent magnets 3a and 3b are magnetized.
Thereafter, in order to check whether an abnormality has occurred during the magnetization of the winding 5 of the stator 1, a surge voltage was applied to the winding 5 to check the impedance variation of the winding.

[0004]

However, in the above configuration, there is a case where reluctance torque acts upon magnetizing and rotational torque acts on the rotor 2 to shift the position of the rotor 2 in the rotational direction. If the rotor position shifts, the impedance viewed from the winding changes, and thus a problem has occurred in that an abnormality in the winding 5 cannot be detected. In order to solve the problem, it is necessary to add a work for correcting the displacement of the rotor after the magnetization.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention solves the above-mentioned problems. In this state, a magnetizing current is applied to a stator winding in a state where the rotor is incorporated in a stator. After a direct current is passed through the wire and the position of the rotor is determined by the attraction of the electromagnet and the permanent magnet of the rotor created by the current, a surge is applied to the stator winding to check the impedance variation of the winding.
In addition, a DC current in the same direction as the magnetizing current flows through the stator winding. By doing so, it becomes possible to prevent demagnetization of the permanent magnet. If the magnitude of the DC current is too large, a large displacement may occur due to the reluctance torque. Therefore, it is preferable that the magnitude of the direct current is set to a minimum value that can correct the displacement of the rotor.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 is a permanent magnet motor having reverse saliency, wherein the rotor is magnetized by passing a magnetizing current through the stator windings with the rotor incorporated in the stator. After that, a DC current is passed through the stator winding to determine the position of the rotor, and then a surge voltage is applied to the stator winding to check the impedance variation of the winding. The variation in impedance is eliminated, and it is possible to accurately detect a change in impedance due to an abnormality in the winding.

According to a second aspect of the present invention, in the method for inspecting a permanent magnet motor according to the first aspect, a DC current is supplied to the stator winding in the same direction as the magnetizing current to determine the position of the rotor. Even if an electric current is applied to the windings to correct the rotor position shift, the rotor is not demagnetized.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 and FIG. 3 are views showing one embodiment of the present invention. With the rotor 2 incorporated in the stator 1, a magnetizing current is passed through the stator windings 5 with the connections shown in FIG. 1 to magnetize the rotor, and then the windings 5 applied to the stator 1 in FIG. As shown in FIG. 1, by passing a DC current in two phases, a magnetic flux flows in the direction of the arrow shown in FIG. 2, and the rotor 2 of FIG. The rotor 2 moves to the position and is positioned. 2 and 3 in the winding 5 in FIG. 2 indicate that currents opposite to each other are flowing.

After that, as shown in FIG. 3, a surge voltage as shown in FIG. 4 is applied to the winding 5 of the stator 1 to check the variation of the impedance of the winding 5.

The DC current for positioning the rotor 2 is:
Make the same direction as the magnetizing current. Further, if the magnitude of the DC current is too large, the position of the rotor 2 may be greatly shifted due to reluctance torque.
It is more preferable to set the minimum size that can correct the positional deviation.

FIG. 5 is a diagram showing another embodiment. In the state where the rotor 2 is incorporated in the stator 1, a magnetizing current flows through the stator windings 5 in a connection as shown in FIG. 5, and after magnetizing the rotor, a DC current flows from one phase to the other two phases. As in FIG. 2, the magnetic flux flows in the direction of the arrow shown in FIG. 6, and the rotor 2 moves to the position of the rotor 2 in FIG. 6 and is positioned by the attraction of the rotor 2 with the permanent magnets 3a and 3b. You.

Thereafter, as shown in FIG. 3, a surge voltage as shown in FIG. 4 is applied to the winding 5 of the stator 1, and the variation of the impedance of the winding 5 is inspected.

It should be noted that the present invention is not limited to the above embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0015]

According to the first aspect of the present invention, since the inspection can be performed with the position of the rotor in the rotation direction being fixed, the variation in impedance viewed from the winding due to the displacement of the rotor is eliminated. It is possible to accurately detect a change in impedance due to an abnormality in the winding.

According to the second aspect of the present invention, since the direction of the current flowing through the winding for determining the rotor position is the same as the direction of the magnetizing current, an effect is obtained that the rotor is not demagnetized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of a motor showing one embodiment of the present invention.

FIG. 3 is a block diagram showing inspection of impedance variation of a stator winding according to the present invention.

FIG. 4 is a diagram showing a surge voltage waveform of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a sectional view of a motor showing another embodiment of the present invention.

FIG. 7 is a configuration diagram of a permanent magnet motor having a structure that utilizes not only a conventional magnet torque but also a reluctance torque.

[Explanation of symbols]

 Reference Signs List 1 stator 2 rotor 3a, 3b permanent magnet 5 winding

Claims (2)

[Claims] In a permanent magnet motor having a reverse saliency, a magnetizing current is applied to a stator winding in a state where the rotor is incorporated in a stator, and then a direct current is applied to the stator winding. A method for inspecting a permanent magnet motor in which after determining the position of a rotor, a surge voltage is applied to a stator winding to check for variations in impedance of the winding. 2. The method for inspecting a permanent magnet motor according to claim 1, wherein a DC current in the same direction as the magnetizing current is applied to the stator winding to determine the position of the rotor.