JPS63228916A - Air harmonizer protector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a protection device for an air conditioner using a three-phase power supply.

BACKGROUND OF THE INVENTION A conventional air conditioner that drives a compressor by controlling the current applied to the compressor by a semiconductor switching group generates a current flowing through a semiconductor switching group 13 across a resistor 140, as shown in FIG. The structure is such that the DC voltage detection means 15 detects the voltage drop caused by the voltage drop, and when the detected voltage exceeds a certain value,
2, an abnormality signal is output to the drive means 16 to turn off all the elements of the semiconductor switching group 13.

With this configuration, when an overcurrent flows through the semiconductor switching group 13 due to an abnormality in the compressor 17 or an abnormality in the semiconductor switching group 13, all elements of the semiconductor switching group 13 are turned OFF to prevent current from flowing. 13 and compressor 17 from destruction.

Problems to be Solved by the Invention However, with the above configuration, during open phase operation of the compressor,
Since extreme overcurrent does not often flow through the semiconductor switching group 13, there is a problem in that it is difficult to protect the compressor 17 during compressor open-phase operation, and even if it is possible to do so, the time it takes to detect an abnormality is shortened. There was a problem that it took a while.

In view of the above problems, the present invention aims to reliably protect the compressor even during open-phase operation of the compressor.

Means for Solving the Problems In order to solve the above problems, the present invention provides a semiconductor switching group for controlling the applied current to a compressor, and a semiconductor switching group for forming signals necessary for operating the compressor. The DC power source for the semiconductor switching group is configured to be generated from the A-phase power source, and the current detecting means detects the phase current of at least two phases of the three-phase power source and converts it into a DC voltage. and comparison means for comparing the output DC voltage values of the respective current detection means,
If the difference between the output DC voltage values exceeds a certain value,
This configuration is such that all the elements of the semiconductor switching group are turned off.

Function The present invention uses the above-described configuration to detect open-phase operation of the compressor when using a three-phase power source, and protect the compressor.

Example An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a three-phase power supply, which is converted into a DC power by a rectifier and smoothing section 2 composed of a diode bridge and a capacitor, and is supplied to a semiconductor switching group 3. Reference numeral 4 denotes a driving means that generates signals necessary for operating the compressor 5 and outputs them to the semiconductor switching group 3. 6.
Reference numerals 7 denote current detection means, which detect two-phase currents between the three-phase power supply 1 and the rectifying and smoothing section 2 and converting them into DC voltages. Each DC voltage value output from the current detection means 6.7 is input to the comparison means 8. The comparing means 8 compares whether the difference between the respective input voltage values exceeds a certain value, and if it exceeds a certain value, outputs an abnormal signal to the driving means 4, and all elements of the semiconductor switching group 3 are activated. Turn it off.

Now, if the compressor 5 has an open phase for some reason, an imbalance will occur in the current flowing from the semiconductor switching group 3, and the balance of each phase current from the three-phase power supply 1 will be disrupted.
A difference occurs in the current value. The current values of two of the phase currents are detected by, for example, a CTl lance constituting the current detection means 6.7, rectified and smoothed by a diode bridge and a capacitor, and then converted into a DC voltage by a load resistor. Here, as a characteristic of the CT lance, the phase current value and the output DC voltage are proportional, so the magnitude of the phase current can be determined from the output DC voltage value.

The comparison means 8 can be realized by, for example, something like the one shown in FIG. The output DC voltages are input to the A and B terminals (el, e2), respectively, and the difference between the voltage values is output to the output terminal of the operational amplifier 9 (eO). This output voltage is the reference voltage (
vrof) 10 and the comparator 11, and if the phase currents become unbalanced and the difference in voltage values to terminals A, B exceeds a certain value (e□>Vrof), the first
The power supply of the drive means 4 shown in the figure is turned off by the transistor 12.
L, all elements of semiconductor switching group 3 in FIG.
Set to FF state.

Effects of the Invention As described above, the present invention can detect open-phase operation of a compressor by detecting the difference in phase current values of at least two phases of a three-phase power supply, and if open-phase operation is detected, the compressor can be stopped. It has the effect of stopping and protecting the compressor.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of a protection device for an air conditioner showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing an embodiment of a comparison means which is a function of the protection device, and Fig. 3 is a FIG. 2 is a configuration diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Three-phase power supply, 3... Semiconductor switching group, 4... Drive means, 5... Compressor, 6.7...・Current detection means, 8...
・Means of comparison.

Claims (1)

[Claims] A semiconductor switching group for controlling the current applied to the compressor, and a driving means for forming signals necessary for operating the compressor and outputting them to the semiconductor switching group, and a DC power source for the semiconductor switching group is supplied from a three-phase power source. Further, the current detecting means detects the phase current of at least two phases of the three-phase power supply and converts it into a DC voltage, and the comparing means compares the output DC voltage value of each current detecting means, A protection device for an air conditioner configured to turn off all elements of the semiconductor switching group when a difference in DC voltage values exceeds a certain value.