JP2965851B2 - Induction motor speed adjustment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the speed of an induction motor.

[0002]

2. Description of the Related Art Conventionally, a method of adjusting the speed of an induction motor is shown in FIG.
The main winding 101 and the auxiliary winding 102 are connected in parallel, and the auxiliary winding 102 and the capacitor 103 are connected in series. In the case of performing the speed adjustment operation, a tap is pulled out from the middle of the auxiliary winding 102, divided into the auxiliary winding 102 and the speed adjustment winding 104, and separated from a connection portion of the main winding 101 and the speed adjustment winding 104. A method including a speed changeover switch 107 for switching the connection between the strong operation lead wire 105 and the weak operation lead wire 106 through the tap of the auxiliary winding 102 and the speed adjustment winding 104 is used. Especially for induction motors used for overseas products with low output and high rated voltage, the main winding 1
The main winding 101 and the auxiliary winding 102 are connected in series as shown in FIG. The capacitors 103 are connected in parallel.
When performing the speed adjustment operation, a tap is pulled out from the middle of the main winding 101, and the main winding 101 and the speed adjustment winding 104
And a lead wire 105 for strong operation formed by taps of the main winding 101 and the speed adjustment winding 104;
A method comprising a speed changeover switch 107 for switching the connection with the weak operation lead wire 106 from the end of the winding 04 has been used.

[0003]

When the speed of an induction motor having a low output and a high rated voltage is controlled in such a conventional manner, the speed control divided from the main winding 101 is required to widen the speed control range. It is necessary to increase the number of turns of the winding 104. However, if the number of turns of the speed adjustment winding 104 that is not used during the strong operation is increased, the number of turns of the main winding 101 is reduced accordingly, so that the current flowing through the main winding increases during the strong operation and the temperature of the induction motor rises. Will be higher. That is, as compared with the case where the rated voltage is low at the same output, the speed adjusting winding 104 which is not used at the time of the strong operation is required. And there is a problem that the cost increases.

Further, when designing the winding, if the characteristic at the time of strong operation is first designed as a reference, the number of windings of the speed adjusting winding is too large to meet the target of the weak operation, so that the winding cannot be accommodated in the slot. There was also a problem that it took time to redesign the winding.

The present invention solves the above-mentioned problem. At all speeds of the induction motor, there is no conductor that is not used in the winding inserted into the slot of the stator. A first object is to propose a method for adjusting the speed of an induction motor without increasing the amount of copper in a conductor and without changing the volume of a stator, since the temperature rise is equal to or higher than when the temperature is low.

A second object is to provide a method for shortening the design time for adjusting the speed of an induction motor.

[0007]

SUMMARY OF THE INVENTION In order to achieve the first object, the method for adjusting the speed of an induction motor according to the present invention is such that the first means is separately inserted into a plurality of slots of a stator of the induction motor. It consists of a main winding, an auxiliary winding connected in series to the main winding, and a plurality of series-connected capacitors connected in parallel to the auxiliary winding. The configuration is such that the connection between the lead wire protruding and the lead wire protruding from the connection part of each capacitor is switched.

In order to achieve a second object, a second
Means inserted into multiple slots of stator of induction motor
Main winding and the auxiliary winding connected in series with this main winding.
A line, a plurality of capacitors connected in parallel to the auxiliary winding, and a switch for switching the plurality of capacitors between a series connection and a parallel connection.
By changing the combined capacitance of the capacitors,
The speed is adjusted .

[0009]

According to the first aspect of the present invention, a conductor which is not used at all speeds of an induction motor used for an overseas product having a small output and a high rated voltage due to the configuration of the first means is not required, so that the temperature rise can be reduced. Also, the amount of copper used for the conductor can be reduced, and there is no need to change the volume of the stator.

Further, according to the configuration of the second means, it is possible to calculate and adjust the combined capacitance when the capacitors are connected in series and when they are connected in parallel, thereby facilitating the design of speed adjustment.

[0011]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. As shown in the figure, in the case of strong / weak operation, the power supply 8 is connected to the main winding 1 and the speed changeover switch 7, and the main winding 1 and the auxiliary winding 2 are connected in series. Has two capacitors A3 and B4 connected in series, which are connected in parallel. The speed changeover switch 7 is connected to the capacitor A3
The connection is switched so as to be switched to a strong operation lead wire 5 from a connection portion between the auxiliary winding 2 and the capacitor A3 and a weak operation lead wire 6 from a connection portion between the auxiliary winding 2 and the capacitor A3.

In the above configuration, when the speed changeover switch 7 is connected to the strong operation lead wire 5, the state becomes as shown in FIG. 2, and the induction motor performs strong operation. The characteristic of the induction motor in this strong operation is the capacitor B4
When the capacitance of the capacitor A3 is constant, the torque tends to increase when the capacitance of the capacitor A3 increases as shown in FIG. 4, and tends to decrease when the capacitance decreases. Further, as shown in FIG. 5, when the capacitance of the capacitor A3 is constant and the capacitance of the capacitor B4 is increased at the same torque, the input value of the induction motor decreases. There is a characteristic that the value does not decrease. When the speed changeover switch 7 is connected to the weak operation lead line 6, the operation becomes as shown in FIG. 3, and the induction motor performs weak operation. The characteristic of the induction motor in the weak operation is determined by the combined capacitance of the capacitors A3 and B4 connected in series determined by the strong operation characteristic. The speed can be increased by increasing the capacitance of the capacitor B4 while keeping the capacitance of the capacitor A3 unchanged, and can be decreased by decreasing the capacitance.

As described above, by using the method for adjusting the speed of an induction motor according to the present invention, conductors that are not used at all speeds can be eliminated, the temperature rise of the induction motor can be reduced, and the amount of copper in the conductor can be reduced. Yes.

In this embodiment, the speed of the capacitor is adjusted in two stages by two types of capacitance. However, the number of capacitors connected in series is increased, and switching is performed by drawing out a lead wire from the connection portion of each capacitor. The speed adjustment can be adjusted in any number of steps.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. As shown in the figure, a capacitor C9 is connected to a contact G13 and a switch E11, and a capacitor D10 is connected to a contact I.
15 and a switch F12, the switch E11 is switched to a contact I15 and a contact H14, and the switch F12 is connected to be switched to a contact G13 and a contact H14.

In the above configuration, the switch E1
When 1 is connected to the contact point I15 and the switch F12 is connected to the contact point G13, the induction motor has a combined capacitance when the capacitors C9 and D10 are connected in parallel, and performs strong operation. The switch E11 is connected to the contact H14, and the switch F is
When 12 is connected to the contact H14, the induction motor has a combined capacitance when the capacitors C9 and D10 are connected in series, so that the induction motor operates weakly.

As described above, according to the method for adjusting the speed of an induction motor of the present invention, the speed of the induction motor can be adjusted by the combined capacitance of two types of capacitors connected in series and in parallel, so that the design is facilitated. Become.

[0018]

As is clear from the above description of the embodiment, according to the present invention, there is no conductor that is not used at all speeds of the induction motor having a small output and a high rated voltage, so that the temperature rise can be reduced. Therefore, the amount of copper used for the conductor can be reduced, and a low-cost speed adjusting method can be provided.

Further, according to the configuration of the second means, it is possible to calculate and adjust the combined capacitance when the capacitors are connected in series and in parallel, thereby providing a method for shortening the design time for speed adjustment. it can.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a speed adjusting method according to an embodiment of an induction motor according to a first embodiment of the present invention;

FIG. 2 is a connection diagram during strong operation according to the embodiment of the induction motor.

FIG. 3 is a connection diagram at the time of weak operation according to the embodiment of the induction motor.

FIG. 4 is a graph showing the relationship between the number of revolutions and torque during strong operation according to the embodiment of the induction motor.

FIG. 5 is a diagram showing capacitance-input characteristics during weak operation according to the embodiment of the induction motor.

FIG. 6 is a connection diagram of a speed adjusting method according to an embodiment of the induction motor of the second embodiment.

FIG. 7 is a connection diagram of a conventional method of adjusting the speed of an induction motor.

FIG. 8 is a connection diagram of a method for adjusting the speed of the induction motor having the low output and the high rated voltage.

[Explanation of symbols]

 1 Main winding 2 Auxiliary winding 3 Capacitor A 4 Capacitor B

Claims (2)

(57) [Claims] 1. A main winding inserted into a plurality of slots of a stator of an induction motor, an auxiliary winding connected in series to the main winding, and connected in parallel to the auxiliary winding. A speed of an induction motor, which is composed of a plurality of capacitors connected in series, and controls the speed by switching the connection between a lead from a connection between the auxiliary winding and the capacitor and a lead from a connection of each capacitor. Adjustment method. 2. In a plurality of slots of a stator of an induction motor.
And the main winding inserted in series with this main winding
An auxiliary winding consists switch for switching a plurality of capacitors connected in parallel with the auxiliary winding, a plurality of capacitors connected in series and parallel connection, switch
Switch to change the combined capacitance of the capacitors.
A method for adjusting the speed of an induction motor for further adjusting the speed.