JPH0583846A - Inverter protector for air-conditioner - Google Patents

Abstract

PURPOSE:To protect an air-conditioner upon occurrence of nonconduction of three-phase output from an inverter unit for feeding power to a three-phase induction motor having three-phase winding of two systems or more. CONSTITUTION:In an inverter controller 9c for air-conditioner provided with two or more systems of inverter units for feeding power to a three-phase induction motor 15 having three-phase winding of two or more systems, three- phase output currents from the inverters 9a, 9b are detected, respectively, through current detecting means 16a, 16b. A nonconduction decision circuit 17 connected with the current detecting means 16a, 16b makes a decision of nonconduction of three-phase outputs. When a decision is made that one or more systems are nonconducting an abnormality signal is delivered to a protection control circuit 18 connected with the nonconduction decision circuit 17 and the protection control circuit 18 protects an air-conditioner.

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 equipped with two or more systems of inverter devices.

[0002]

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

Conventionally, many air conditioners of this type are equipped with an inverter device for control. The configuration will be described below with reference to FIG. The dotted line portion in FIG. 2 will be described as being not connected. As shown in FIG. 2, the refrigerant circuit of the outdoor unit 101 includes a compressor 102, a four-way valve 103, a heat exchanger 104, an electric expansion valve 105, and a three-way valve 106, and the indoor heat exchanger 12 of the indoor unit 120.
It is connected to 1. The compressor 102 is controlled at a variable speed by the variable voltage and variable frequency output of the inverter device 109a, and the four-way valve 103, the electric expansion valve 105, and the fan motor 107 are appropriately controlled by the control circuit 108 to perform cooling or heating operation. It is controlled to be

In the above configuration, the inverter device 1
Reference numeral 09a denotes a rectifier circuit 1 that rectifies and smoothes the AC power supply 110.
11 a and a power transistor module 112 a connected to a three-phase bridge for inverse conversion into three-phase alternating current, and the voltage and frequency were determined by the signal from the PWM waveform generation circuit 114 via the base drive circuit 113 a. Further, in such a configuration, when the capacity of the air conditioner becomes about 4 to 5 kW or more, the inverter device 109a
Of the inverter device 109a, and the power transistor module 112.
A having a large capacity must be adopted. Therefore, an inverter control device for an air conditioner using two or more inverter devices for supplying electric power to a compressor equipped with a three-phase induction motor having two or more three-phase windings has been previously proposed. (Application number No. 258069 in 1990).

[0005]

In the inverter control device 109c composed of two or more systems of inverter devices 109a and 109b like the above-proposed inverter control device, each inverter device 109a is used.
-In one or more inverter devices of 109b, the base drive circuit 113a or 113b and the power transistor module 112a or 112b.
When the contact is bad in the connection relationship connecting the three-phase output and the three-phase output is de-energized, the system is supplied with a current equal to the sum of the currents flowing through the three-phase windings of each system of the three-phase induction motor 102 during normal operation. Since the current flows, the value of the current flowing through the energized system is larger than the value of the current that normally flows. Therefore, when the three-phase output of one or more inverter devices 109a or 109b is de-energized, the three-phase winding of the three-phase induction motor 102 of the energized system and the inverter device 109b or 109a, particularly the power transistor module 11
There is a problem in that 2b or 112a is burdened and, in the worst case, is destroyed.

The present invention solves the above problems by providing a circuit for detecting the three-phase output of each inverter device to detect the non-energization, and when the three-phase outputs of one or more inverter devices are non-energized. An object of the present invention is to provide an inverter protection device for an air conditioner, which can protect an inverter device and a three-phase induction motor built in a compressor by providing a protection circuit.

[0007]

To achieve this object, the present invention provides an air system comprising two or more inverter devices for supplying electric power to a three-phase induction motor having two or more systems of three-phase windings. An inverter control device for a harmony machine, comprising: an inverter control device having two or more systems in parallel with a rectifier circuit for rectifying and smoothing a power supply to generate a direct current; and a power transistor module for converting a direct current into a three-phase alternating current; A PWM waveform generation circuit for outputting to a system inverter device via a base drive circuit, each power transistor module configured in each of the inverter devices, and a power transistor connected to a three-phase induction motor, An empty line provided with a current detection means and a protection control circuit from the current detection means through a non-conduction determination circuit in the middle of the connected line. It is obtained by the configuration of an inverter protection device of conditioner.

[0008]

With this configuration, the current of the three-phase output of each inverter device is detected between each power transistor module and the three-phase induction motor, and the non-energization judging circuit judges non-energization. When the three-phase output of 3 is de-energized, the protection control circuit can temporarily stop and protect the air conditioner.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, the first-phase three-phase winding u ₁ · v _{1 of} the three-phase induction motor 15 having two-system three-phase windings
· The w ₁ is supplied with electric power are connected output u _1, v _1, w ₁ of the first inverter device 9a is. On the other hand, three-phase induction motor 1
The output u ₂ · v ₂ · w ₂ of the second inverter device 9b is connected to the three-phase winding u ₂ · v ₂ · w ₂ of the second system 5 to supply power. Further, the AC power supply 10 supplies power to the first and second inverter devices 9a and 9b in common. On the other hand, the PWM waveform generation circuit 14 is also the base drive circuit 1 of the first and second inverter devices 9a and 9b.
The base drive circuits 13a and 13b are connected to send a PWM signal in common to 3a and 13b.

Here, the first and second inverter devices 9a and 9b are rectifier circuits 11a and 11b for rectifying and smoothing the AC power supply 10 into DC, and three-phase for inversely converting the smoothed DC into three-phase AC. The power transistor modules 12a and 12b connected to the bridge and the base drive circuits 13a and 13b for supplying a base current are connected.
Further, current detecting means 16a, 16b for detecting the current of the three-phase output of each inverter device are provided on the connection line between each inverter device 9a, 9b and the three-phase induction motor 15. The current detecting means 16a and 16b are electrically connected to respective three-phase outputs,
It is connected to a protection control circuit 18 via a non-energization determination circuit 17 that determines whether or not the power is non-energized.

With the above configuration, for example, when the three-phase output of the inverter device 9a is de-energized, the current detecting means 1
De-energization determination circuit 17 based on the current value signals from 6a and 16b
Determines that the three-phase output of the inverter device 9a is not energized, and sends a signal indicating an abnormality to the protection control circuit 18. In the protection control circuit 18 that receives the abnormal signal, the PWM waveform generation circuit 14
Each inverter device 9 is controlled so as to stop the WM signal.
The operation of the air conditioner can be stopped to protect the a.9b and the three-phase induction motor 15.

As described above, according to the inverter protection device for the air conditioner of the embodiment of the present invention, in the inverter control device 9c for the air conditioner provided with the inverter devices for two systems, either one of the inverter devices 9a is provided. When the three-phase output of 9b is de-energized, the three-phase induction motor 15 and the inverter devices 9a and 9b, especially the power transistor modules 12a and 12b can be protected.

In this embodiment, the case where the three-phase output of the inverter device of one system among the inverter control devices 9c composed of the two systems of inverter devices is de-energized has been described. Even when the three-phase output of one or more inverter devices is de-energized by the inverter control device including the inverter device, the air conditioner can be protected as in the present embodiment.

In the present embodiment, the PWM waveform generation circuit 14 protects the PWM signal by stopping it.
Even when the base drive circuits 13a and 13b are controlled so as not to output the PWM signal to the power transistor modules 12a and 12b, the air conditioner can be protected as in the present embodiment.

[0016]

As is apparent from the above embodiments, according to the present invention, two or more inverter systems for supplying electric power to a three-phase induction motor having two or more three-phase windings are provided. In an inverter control device for an air conditioner, the three-phase output current of each inverter device is detected, a non-energization determination circuit determines non-energization, and a signal indicating an abnormality is received from the non-energization determination circuit, the air conditioner. An inverter protection device for an air conditioner that can protect the air conditioner even if one or more lines of the three-phase output of each inverter device are de-energized because a protection control circuit for protecting the air conditioner is provided. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inverter 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 an inverter device for an air conditioner according to a conventional example.

[Explanation of symbols]

 9a ・ 9b Inverter device 9c Inverter control device 10 AC power supply 11a ・ 11b Rectifier circuit 12a ・ 12b Power transistor module 13a ・ 13b Base drive circuit 14 PWM waveform generation circuit 15 Three-phase induction motor 16a ・ 16b Current detection means 17 De-energization judgment circuit 18 Protection control circuit

Claims (1)

[Claims] 1. An inverter control device for an air conditioner comprising two or more systems for supplying electric power to a three-phase induction motor having two or more systems of three-phase windings, wherein the power supply is rectified and smoothed. A rectifier circuit for direct current, and an inverter control device having two or more systems in parallel having an inverter device having a power transistor module for converting direct current into three-phase alternating current,
A PWM waveform generation circuit for outputting to the inverter device of each system via a base drive circuit, each power transistor module configured in each inverter device, and a power transistor connected to a three-phase induction motor An inverter protection device for an air conditioner, which is provided with a current detection means in the middle of the connected line and a protection control circuit from the current detection means via a non-conduction determining circuit.