JPS6051664B2 - Cage type induction machine rotation speed detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation speed detection device for a cage-type induction machine.

Conventionally, in a detection coil that detects the rotational speed of the rotor based on the vibration frequency induced by the rotor teeth of a cage-type induction machine, the output voltage is determined by the main magnetic flux generated by the main excitation coil and the main magnetic flux generated by the rotor teeth. The magnetic flux that fluctuates due to changes in magnetic resistance is superimposed,
In order to detect the rotational speed of the rotor, only the rotational output voltage is required, and the fundamental wave voltage induced by the main magnetic flux is not required.

For this reason, various methods have been adopted to remove the fundamental wave voltage, such as passing it through a high-pass filter or canceling the power supply voltage and the fundamental wave voltage to output only the oscillating frequency.

When an induction machine is used as an electric motor or as a variable speed induction generator, the removal of the fundamental wave becomes a problem because the magnitude and phase of the main magnetic flux change.

The present invention was made in view of this point, and the rotation speed detection wire is placed at the end of the stator magnetic pole teeth, and the compensation wire is placed at the electrical angle nπ (
However, they are wound around the base of the stator magnetic pole teeth at positions n = 0, 1, 2, etc.) and connected so as to cancel out the induced fundamental wave, which is induced by the rotor teeth. The number of rotations of the rotor is detected using the operating frequency.

Furthermore, a pair of wires consisting of such a rotation speed detection wire and a compensation wire, and a pair of wires having the same shape and output as the aforementioned wire at a position of electrical angle (112+n)π are provided. It is connected so that it is added to the mechanical output of the above-mentioned wire ring, and a mechanical output with a constant amplitude value can be obtained, and the rotation speed of the rotor can be detected with even higher accuracy. This is what I did. Figure 1 is a cross-sectional diagram of an induction machine. 1 is a stator, 2 is a stator tooth, 3 is a main excitation wire ring, 4 is a wire groove, 5 is a wedge, 6 is a rotor, is a rotor tooth, 8 9 is a cage-shaped conductor, 9 is a rotation speed detection wire, and 10 is a compensation wire.

FIG. 2 is an enlarged sectional view of the rotation speed detection wire and the compensation wire. The coil is constructed as a single-row multilayer flat coil so that it can be easily grooved into the main excitation coil groove at the same time as the main excitation coil. A rotation speed detection wire 9 is wound around the end of the tooth, and a compensation wire 10 is wound around the base of the tooth. It is effective to wind the wire so as to correspond to one rotor tooth, but it may be wound around one stator tooth or two depending on the rotor tooth width. Next, when the induction machine is used as an electric motor, the main magnetic flux due to the current flowing through the excitation wire ring 3 is generated by the rotation speed detection wire 9 wound around the stator magnetic pole tooth end and the rotation speed detection wire 9 wound around the magnetic pole tooth base. It also passes through the compensation wire 10.

Furthermore, the magnetic resistance of the rotation speed detection coil 9 changes due to the rotor teeth 7 of the rotor 6, and a magnetic flux corresponding to the rotor teeth 7 is superimposed on the fundamental wave, and a voltage is induced. On the other hand, compensation wire 1
0 is wound around the base of the stator teeth at a position of electrical angle nπ with respect to the rotation speed detection wire 9, but it is hardly affected by the magnetic resistance caused by the rotor teeth, and is induced by this. The voltage generated is only the fundamental wave due to the main magnetic flux. For this purpose, by connecting the rotation speed detection wire 10 and the compensation wire 11 so that the fundamental waves cancel each other out, only the percussive frequency generated by the rotor teeth 8 is output. The rotor teeth of the rotor are unique to each induction machine, and the rotor speed can be detected by detecting the rotor frequency.
In this case, the peak value of the chanting frequency has a waveform that looks like it has been modulated by a fundamental wave.

On the other hand, at the (112+n)π position, another pair of detection wires having the same shape and output as the pair of wires described above are further wound and connected so that the output is added to the output of the wires described above. For example, the peak value of the combined output is a constant value. FIG. 3 shows the characteristic curve. A is the output voltage of the rotational speed detection wire 10, and A is the output voltage of the compensation wire 9, the frequency is equal to the power supply voltage, and the incantation output C is after canceling the fundamental wave of both wires. Furthermore, if the winding position of another pair of coils of the same type is electrical angle (ν + n) π, then the incantation output is 2, and these two pairs of wires are connected so as to add the outputs of C and 2. This makes it possible to obtain an output with a constant amplitude, making it extremely easy to specify and control the rotational speed. The present invention uses the rotation speed detection wire and the compensation wire wound as described above.
Since it can output a oscillation frequency corresponding to the rotation speed, it can be used with closed-type induction machines, canned-type induction machines, where it is difficult to install a tachometer, or induction generator-type electric dynamometers that operate at variable speeds. In this case, the output is a high-frequency digital output with high precision, simple structure, and can provide an inexpensive speed detection device.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an induction machine. 1... Stator, 2... Stator teeth, 3.
...Main excitation wire ring, 6...Rotor, 7...
...Rotor teeth, 9...Rotation speed detection wire ring, 1
0... Compensation wire ring.

Claims (1)

[Scope of Claims] 1. A rotation speed detection wire is wound around the end of the stator magnetic pole tooth, and a compensation wire is wound around the base of the stator magnetic pole tooth at the electrical nπ position, and an excitation wire is wound around the base of the stator magnetic pole tooth. Rotation speed detection of a cage-type induction machine characterized in that both wire wheels are connected so that the induced fundamental waves cancel each other out, and the rotation speed of the rotor is detected by the vibration frequency induced by the rotor teeth. Device. 2. A pair of rotation speed detection wires each having a rotation speed detection wire wound around the end of the stator magnetic pole tooth and a compensation wire wound around the base of the stator magnetic pole tooth at an electrical angle nπ position. Furthermore, the electrical angle (
A pair of detection coils having the same shape and output as the coils are wound at the position of 1/2+n)π, and connected so that the respective mechanical outputs of the two pairs of coils are added. A rotational speed detection device for a cage-type induction machine, characterized in that the rotational speed of a rotor is detected from a rotational frequency.