JPH05252794A - Inverter protection device for air conditioner - Google Patents

Abstract

PURPOSE:To provide an inverter protection device capable of certainly protecting an air conditioner when an abnormal state occurs in a DC output current after rectification by each inverter unit. CONSTITUTION:Two inverters 108a and 108b are installed, and they are connected respectively to rectifying circuits 112a, 112b, current detecting circuits 2a, 2b for detecting rectified and smoothed DC output current, protection circuits 3a, 3b, and power transistor modules 113a, 113b. If any abnormal state occurs in the output current, an air conditioning unit is protected through a protection circuit 3a, 3b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter protection device for an air conditioner having two or more systems of inverter devices.

[0002]

2. Description of the Related Art In recent years, demands for pursuing energy saving or improving comfort have been increased in air conditioners, and variable speed control of compressors has become mainstream.

Conventionally, an inverter device is mounted on this type of air conditioner, and the configuration of this air conditioner will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the refrigerant circuit of the outdoor unit 101 includes a compressor 102, a four-way valve 103, and an outdoor heat exchanger 10.
4, an electric expansion valve 105, and a three-way valve 106,
It is connected to the indoor heat exchanger 202 of the indoor unit 201.
The compressor 102 is controlled at a variable speed by the variable voltage / variable frequency output of the inverter device 108 which is determined by the output signal of the PWM waveform generation circuit 107. The four-way valve 1
03, electric expansion valve 105, and fan motor 109
Are controlled by the control circuit 110 so that the cooling or heating operation is appropriately performed.

In the above configuration, the inverter device 1
As shown in FIG. 3, 08 is a rectifier circuit 112 that rectifies and smoothes the AC power supply 111, a power transistor module 113 that is connected to a three-phase bridge that reverse-converts the rectified and smoothed DC into three-phase AC, The three-phase output 115 of the inverter device 108 is composed of a base drive circuit 114 that supplies a base current.
The output signal of 07 will determine the voltage and frequency. And in such a configuration,
When the cooling capacity of the air conditioner exceeds 4-5 kW,
The work of the compressor 102 increases, and the inverter device 108
Therefore, the rectifier circuit component and the power circuit component such as a transistor module that constitute the inverter device 108 have a large capacity.

[0006]

In the conventional inverter protection device for an air conditioner, the inverter device 10 is used.
When the DC output current rectified and smoothed by the rectifier circuit 112 of 8 becomes abnormal, the load on the compressor 102 increases,
Further, there is a problem that the inverter device 108, particularly the power transistor module 113, is destroyed even if it has a large capacity.

The present invention solves the above-mentioned problems, and a current detection circuit for detecting the DC output currents rectified and smoothed by the rectification circuits of a plurality of inverter devices, and a protection circuit when an abnormality occurs in the DC output current. It is an object of the present invention to provide an inverter protection device that can reliably protect an air conditioner by providing a protection circuit that protects the air conditioner.

[0008]

In order to achieve the above object, an inverter protector for an air conditioner according to the present invention is a three-phase induction device having a structure in which electrically isolated two-system three-phase windings are mounted. Each of the inverter devices is equipped with a compressor having a built-in electric motor, a first inverter device that supplies electric power to each of the two-system three-phase windings of the three-phase induction motor of the compressor, and a second inverter device. Is a rectifier circuit, a current detection circuit that detects a DC output current that has been rectified and smoothed by this rectification circuit, and this current detection circuit and a power transistor module are connected to the rectification circuit, and are also connected to a base drive circuit, The inverter protection device for an air conditioner includes a protection circuit that protects the air conditioner by an abnormal signal from the current detection circuit.

[0009]

According to the present invention, when the DC output current is abnormal by the current detection circuit for detecting the DC output current rectified and smoothed by the rectifier circuit of each inverter device, the current detection circuit causes A signal is output to the protection circuit, and then a signal is output from the protection circuit to the base drive circuit to stop the output from the base drive circuit and reliably protect the air conditioner equipped with two or more inverter devices. can do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The same reference numerals as those used in the conventional example indicate the same items, and the description thereof will be omitted.

As shown in the figure, the output Ua, Va of the first inverter device 108a is connected to the three-phase windings U1, V1, W1 of the first system of the compressor 1 having two-system three-phase windings. ,
Wa is connected and electric power is supplied from the AC power supply 111. On the other hand, the three-phase windings U2, V2 of the second system of the compressor 1,
The output Ub of the second inverter device 108b is connected to W2,
Vb and Wb are connected and power is supplied from the AC power supply 111. Further, the AC power supply 111 supplies power in common to the first and second inverter devices 108a and 108b.

On the other hand, the PWM waveform generation circuit 107 is connected to the base drive circuits 114a and 114b. Each power transistor module 113a, 113
connected to b.

The internal structure of the first and second inverter devices 108a and 108b is the AC power supply 111.
Rectifying circuits 112a and 112b for rectifying and smoothing the current, and a current detection circuit 2 for detecting the rectified and smoothed DC output current
a, 2b, and power transistor modules 113a, 11 connected to the compressor 1 for inversely converting DC into three-phase AC
3b and a base drive circuit 11 for supplying a base current
4a and 114b are connected. A PWM waveform generation circuit 107 that outputs a PWM signal to control the output voltage and the output frequency of the first and second inverter devices 108a and 108b is connected to the base drive circuits 114a and 114b. The current detection circuits 2a and 2b are connected to the protection circuits 3a and 3b.

In the above structure, the rectifier circuit 112 is assumed.
When an abnormality occurs in the DC output current rectified and smoothed by a, the current detection circuit 2a detects the abnormality and sends a signal indicating an abnormal state to the protection circuit 3a and receives a signal indicating an abnormality. The protection circuit 3a stops the operation of the air conditioner. It should be noted that the same control as above can be performed when an abnormality occurs in the DC output current that has been rectified and smoothed by the rectifier circuit 112b.

As described above, according to the inverter protection device for the air conditioner of the embodiment of the present invention, the rectification circuits 112a, 112b of the inverter system for the air conditioner having the two or more systems of inverter devices 108a, 108b are used for rectification / commutation. When an abnormality occurs in the smoothed DC output current, the inverter devices 108a and 108a are activated by the current detection circuits 2a and 2b.
b, especially power transistor modules 113a, 11
3b can be protected reliably. In addition, in the present embodiment, the compressor 1 and the inverter devices 108a and 108b having the two-system three-phase windings are used, but the compressor 1 and the inverter devices having two or more three-phase windings are used. It does not make a difference in its action and effect. Further, in the present embodiment, the protection circuit is used for each inverter device, but even if only one protection circuit is provided, there is no difference in the action and effect.

[0016]

As is apparent from the above embodiments, according to the present invention, in the air conditioner composed of the compressor and the inverter device having the three-phase windings of two or more systems, the rectification of each inverter device is performed. Since a current detection circuit that detects a DC output current that has been rectified and smoothed by the circuit is provided, and a protection circuit that protects the air conditioner is provided when a signal indicating an abnormality is received from the current detection circuit, It is possible to provide an inverter protector for an air conditioner that has the effect of reliably protecting the air conditioner even if an abnormality occurs in the DC output current that has been rectified and smoothed by the rectifier circuit of the inverter device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inverter protection device for an air conditioner according to an embodiment of the present invention.

FIG. 2 is a control circuit and a refrigerant circuit diagram of a conventional air conditioner inverter device.

FIG. 3 is a control circuit diagram showing an internal configuration of the inverter device.

[Explanation of symbols]

 1 three-phase induction motor for compressor 2a current detection circuit 2b current detection circuit 3a protection circuit 3b protection circuit 108a first inverter device 108b second inverter device 112a rectification circuit 112b rectification circuit 113a power transistor module 113b power transistor module 114a base Drive circuit 114b Base drive circuit U1, V1, W1 Three-phase winding of the first system U2, V2, W2 Three-phase winding of the second system

Claims (1)

[Claims] 1. A compressor having a built-in three-phase induction motor having a structure in which electrically isolated two-system three-phase windings are installed, and two-system three-phase windings of the three-phase induction motor of the compressor. A first inverter device for supplying electric power to each of the above, and a second inverter device, each inverter device having a rectifier circuit, and a current detection circuit for detecting a DC output current rectified and smoothed by the rectifier circuit. An air conditioner having a protection circuit that connects the current detection circuit and the power transistor module to the rectifier circuit and also connects to the base drive circuit, and protects the air conditioner with an abnormal signal from the current detection circuit. Inverter protection device.