JPH09168299A - Induction motor - Google Patents

Abstract

It is an object of the present invention to improve motor efficiency and reduce power consumption by changing a motor drive system and improving a rotor structure in a motor. A motor has a control configuration in which the rotation speed of the motor is changed by changing the frequency and electric power by an inverter, and the rotor of the motor is an induction motor of a wound rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor used for an indoor unit of an air conditioner, an outdoor unit and the like.

[0002]

2. Description of the Related Art Conventionally, fan motors used in indoor units of outdoor air conditioners, outdoor units, etc. have been actively pursued with high efficiency and noise reduction in response to market demand for energy saving.

FIG. 3 is a block diagram showing a speed control system for a fan motor of a conventional air conditioner indoor unit.

In FIG. 3, reference numeral 1 is a motor, and currently a single-phase induction motor is mainly used. Reference numeral 2 is a capacitor, which is attached to rotate the single-phase induction motor of 1. 3 is a bidirectional switching element.

The operation of the conventional fan motor speed control system for an air conditioner indoor unit constructed as described above will be described below.

When varying the rotation speed of the fan motor, the voltage applied to the electric motor is controlled by the bidirectional switching element 3.
The torque generated by the electric motor is changed to change the rotation speed of the electric motor.

[0007]

However, the frequency cannot be changed by the speed control method of the fan motor of the air conditioner indoor unit using the conventional bidirectional switching element, and when the motor is used in Japan 50
Since the same motor is used in the Hz and 60 Hz regions, the rotation speed-torque characteristics of FIG. 4 are A at 50 Hz, B at 60 Hz, and F at fan, and the actual rotation speeds are a and b, respectively. As shown in Fig. 4, the motor operates at a rotation speed lower than the rotation speed at which the maximum torque is not very efficient and consumes a lot of power (the rotation speed at which the maximum efficiency is between the maximum torque rotation speed and the synchronous rotation speed It is in).

The present invention solves the problem that the conventional bidirectional switching element consumes a large amount of power when operating a single-phase induction motor, and an object of the invention is to reduce the power consumption.

[0009]

In order to achieve this object, the electric motor of the present invention is operated by an inverter and is a wound rotor of the electric motor rotor.

As a result, the motor efficiency can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a single-phase or three-phase induction motor driven by an inverter, wherein the rotor is a winding type rotor, and the motor is a winding type rotor. The secondary resistance is small and the efficiency during operation is good, but the starting torque is small. Therefore, it has an effect of driving the electric motor by the inverter and lowering the frequency at the time of starting to increase the starting torque.

According to a second aspect of the invention, the motor output is 2
The invention according to claim 1 is applied to an induction motor of 00 W or less, and particularly in a low output motor of 200 W or less, when the winding type rotor is used, the secondary resistance tends to be small.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a speed control system of a fan motor according to an embodiment of the present invention, and 4 is a wound-rotor induction motor. An inverter 5 outputs an AC voltage having a variable voltage and a variable frequency to the induction motor 4 of the winding type rotor.

A speed control method of the fan motor configured as described above will be described with reference to the rotation speed-torque characteristic of FIG. A solid line C is the characteristic of the motor, and a broken line F is the characteristic of the fan. Then, the actual rotation speed is the intersection point c between the rotation speed at which the maximum torque is efficient and the synchronous rotation speed.
It rotates and can reduce power consumption. Although the starting torque is small in the state of FIG. 2, if the output frequency of the inverter is set to a small value at the time of starting, a large starting torque can be obtained because the starting torque is inversely proportional to the frequency, and the starting can be easily performed.

[0015]

As described above, according to the present invention, in the control configuration in which the fan motor is driven by the inverter, the electric motor is an induction motor having a wound rotor, so that the electric motor efficiency is improved and the power consumption can be reduced. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a speed control system of a fan motor according to a first embodiment of the present invention.

FIG. 2 is a rotation speed in the first embodiment of the present invention-
Torque characteristic diagram

FIG. 3 is a block diagram showing a speed control method for a conventional fan motor.

FIG. 4 is a rotational speed-torque characteristic diagram of a conventional fan motor speed control method using phase control.

FIG. 5 is a rotation speed-torque characteristic diagram in a speed control system using an inverter of a fan motor of a squirrel-cage induction motor.

[Explanation of symbols]

 3 Bidirectional switching element 4 Three-phase induction motor 5 Inverter

Claims (2)

[Claims] 1. A single-phase or three-phase induction motor driven by an inverter, wherein the rotor is a wound rotor. 2. The induction motor according to claim 1, wherein the motor output is 200 W or less.