JPS62202963A - Controller for air conditioner - 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 Industrial Application) The present invention relates to a control device for an air conditioner equipped with an inverter.

(Prior Art) FIG. 5 is a circuit configuration diagram showing a conventional air conditioner control device disclosed in, for example, Japanese Unexamined Patent Publication No. 57-40369. In the figure, ■ is a commercial AC power supply, 2 is a diode stack that is a rectifier, 3 is a smoothing electrolytic capacitor, and 4 is a rectifier.
1 is a power transistor module serving as an inverter section, and constitutes an inverter 5 together with a diode stack 2 and an electrolytic capacitor 3. 6 is a compressor motor that is a load of the inverter 5; 7 is a base drive circuit that drives the power transistor module 4; and 8 is a control circuit that controls the output voltage and output frequency of the inverter 5.

Next, the operation will be explained. Inverter 5 is a commercial power line! The diode stack 2 converts the alternating current into direct current, and the electrolytic capacitor 3 smoothes this direct current. Then, the power transistor module 4 converts the AC signal back into an alternating current signal with an arbitrary frequency, and provides the variable frequency output to the compressor motor 6 to drive the compressor motor 6.

FIG. 6 is a diagram showing data of the output voltage and output frequency pattern (hereinafter referred to as V/F pattern) of the inverter 5. This V/F pattern is set by the control circuit 8, and under that condition the base drive circuit 7
Inverter 5 is driven through. For example, at startup, both the output cuff pressure (Vmin+) and the output frequency (Fmin) are the lowest, as shown in data A, and at the maximum rated output, the output voltage (Vmax) and output frequency (Fmin) are the lowest, as shown in data B.
max) are both maximum.

(Problems to be Solved by the Invention) Since the conventional air conditioner control device is configured as described above, if an overload condition occurs in a low frequency operating range such as when starting the compressor motor 6, which is the load, There is a problem in that an excessive current flows through the inverter 5, which causes the overcurrent protection circuit to operate, resulting in a narrow operable frequency range.

This invention has been made to solve these problems, and aims to provide a control device for an air conditioner that does not allow excessive current to flow even in low frequency operating ranges and has a wide operable frequency range. The purpose is

(Means for Solving the Problems) The air conditioner control device of the present invention is provided with an overload state detection means, and when overloaded, a dedicated output voltage and output frequency pattern is set and the control device operates under these conditions. Drive the inverter,
At times other than overload, normal output voltage and output frequency patterns are set and the inverter is driven under these conditions.

[Effect]

The inverter is driven under normal V/F pattern conditions except when overloaded, but when the detection means detects an overload condition, such as during startup, a V/F pattern specifically designed for overload conditions is activated. condition, and prevents excessive current from flowing in the low frequency range.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In the figure, l is a commercial AC power supply, 2 is a diode stack, 3 is an electrolytic capacitor, 4 is a power transistor module, 5 is an inverter consisting of the above-mentioned structure, 6 is a compressor motor, 7 is a base drive circuit, and 8 is a These are the same parts of the control circuit as the conventional one (see FIG. 5). 9 is a microcomputer (hereinafter referred to as microcomputer) provided in the control circuit 8; 10 is an indoor temperature detection circuit; and 11 is an outdoor temperature detection circuit; these detection results are manually input to the microcomputer 9, which detects an overload condition. whether it is detected. That is, the microcomputer 9 is provided as a means for detecting an overload state, and the above-mentioned detection circuit 1
An overload condition is detected based on the detected indoor temperature and outdoor temperature of 0.11.

The indoor temperature detection circuit 10 is composed of a thermistor 12 disposed indoors, a voltage dividing resistor 13, a resistor 14, 15 for determining a reference voltage for comparison, and a comparator 16, and the outdoor temperature detection circuit 11 is also constructed in the same manner. It also includes a thermistor 17, a voltage dividing resistor 18, a resistor 19, 20 for determining a reference voltage for comparison, and a comparator 21, which are arranged outside the room.

FIG. 2 is a diagram showing data of two V/F patterns set by the control circuit 80 and the microcomputer 9. That is, during normal times other than overload, the inverter 5 is driven under the normal V/F pattern conditions shown by curve (A) similar to the conventional one, and when overloaded, the inverter 5 is driven under the conditions of the normal V/F pattern shown by curve (0). The inverter 5 is driven under the conditions of the F pattern.

In the dedicated V/F pattern used during this overload, the voltage is higher than normal in the low output region of the inverter 5 such as during startup, and the lowest data C is the frequency F.
Keeping m1n as it is, the voltage Va+in2 (Vmin2>V
min, ) is high.

Next, the operation of detecting the above-mentioned overload state and controlling the inverter 5 will be described. In the indoor temperature detection circuit 10, the indoor temperature detected by the thermistor 12 is compared with a certain reference temperature, and the comparison result is input to the microcomputer 9. Specifically, the indoor temperature is converted into a voltage value by thermistor 12, and this voltage is compared with a reference voltage determined by resistor 14.15 by comparator 16. Similarly, in the outdoor temperature detection circuit 11, the thermistor 17
The detected voltage of the outdoor temperature converted by is compared with the reference voltage by the comparator 21. And these comparators 16.
Both outputs of 21 are manually input to the microcomputer 9. Here, for example, when the indoor temperature detection voltage is lower than the reference voltage, the output of the comparator 16 becomes "H" (high level), and when the outdoor temperature detection voltage is lower than the reference voltage, the output of the comparator 21 becomes "H". ”, then in the overload state, comparison 31
The outputs of 6 and 21 both become "H", and this signal is input to the microcomputer 9. And the microcomputer 9 is the rain detection circuit 1
When the signals from 0.11 to
) is controlled under the conditions of the V/F pattern exclusively for overload. Therefore, in a low output region such as when starting the compressor motor 6, which is a load, the output voltage of the inverter 5 is high (the frequency is constant), and no overcurrent flows. In other words, an excessive current will not flow even in the low frequency range of the inverter 5, and the compressor motor 6
can be driven stably.

In addition, when the comparison results manually input to the microcomputer 9 from both comparators 16 and 21 do not become "H" and it is determined that there is no overload condition, the normal V as shown by the curve (A) in FIG. /
The output of the inverter 5 is controlled under the conditions of the F pattern.

FIGS. 3 and 4 are diagrams showing other embodiments of the present invention. In this embodiment, an overload condition is detected based on the temperature of the indoor heat exchanger and the temperature of the outdoor heat exchanger. That is, in FIG. 3, 22 is a four-way valve that switches the refrigerant flow path, 23 is an indoor heat exchanger, 24 is a thermistor for detecting its temperature, 25 is an indoor fan, 26 is an outdoor heat exchanger, and 27 is its temperature detection thermistor. A temperature detection thermistor 28 is an outdoor fan.

Also, Figure 4 shows the configuration of the electric circuit, and 29
．． 30 are temperature detection circuits for the indoor heat exchanger 23 and the outdoor heat exchanger 26, respectively. The temperature detection circuit 29 of the indoor heat exchanger 23 is composed of a -h symbol mister 24, a voltage dividing resistor 31, a resistor 32, 33 for determining a reference voltage for comparison, and a comparator 34. The temperature detection circuit 30 of 26 is composed of a thermistor 27, a voltage dividing resistor 35, a resistor 36.degree. 37 for determining a reference voltage for comparison, and a comparator 38. Note that these temperature detection circuits 29 and 30 are similar to the temperature detection circuit 10 in the above-mentioned embodiment.
．． It has the same configuration as No. 11.

In the indoor temperature detection circuit 29, the thermistor 24
The detection voltage of the temperature of the indoor heat exchanger 23 converted by is compared with the reference voltage, and similarly the outdoor temperature detection circuit 3
0, the detection voltage of the temperature of the outdoor heat exchanger 26 is compared with the reference voltage, and each comparison result is sent to the comparator 34.3.
8 to the microcomputer 9. Here, for example, when the detection voltage (converted voltage) of the temperature of the indoor heat exchanger 23 is higher than the reference voltage, the output of the comparator 34 becomes "yes", and the detection voltage of the temperature of the outdoor heat exchanger 26 becomes the reference voltage. If the output of the comparator 38 is "L" when the voltage is lower than the voltage, the outputs of the comparators 34 and 38 are both "L" when the voltage is overloaded, and this signal is input to the microcomputer 9. Then, the microcomputer 9 receives both signals from the rain detection circuits 29 and 30 as “C”.
Then, as in the case of the above-mentioned embodiment, it is determined that there is an overload condition, and the output of the inverter 5 is changed to the curve (0) in FIG.
Conditions for the V/F pattern specifically for overload shown in
’ to control. Therefore, it is possible to prevent excessive current from flowing in the low frequency region, and stable operation control of the compressor motor 6 is possible.

In addition, when there is no overload condition, the data of song W (A) in Fig. 2 is selected as the V/F pattern of the inverter 5, and the compressor motor 6 is operated under the conditions of the normal V/F pattern.
is driven.

〔Effect of the invention〕

As explained above, according to the present invention, since the inverter is driven under the conditions of a dedicated output pattern (V/F pattern) during overload, it is possible to prevent excessive current from flowing during overload such as during startup. Therefore, there is an effect that an overcurrent does not occur even in a low frequency region, and a wide operable frequency region can be obtained.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing pattern data of the output voltage and output frequency of the inverter shown in Fig. 1, and Fig. 3 is another embodiment of the invention. 1-v# diagram, FIG. 4 is a configuration diagram of its electric circuit, and FIG. 5 is a circuit configuration diagram showing a conventional air conditioner control device.
FIG. 6 is a diagram showing a pattern of the output voltage and frequency of the inverter of FIG. 5. 5------ Inverter 6--- Compressor (load) 7------
--Base drive circuit 8...Control circuit 9...Microcomputer (detection means) 10
---Indoor temperature detection circuit 11--Outdoor temperature detection circuit 23--Indoor heat exchanger 26--Outdoor heat exchanger 29-- Temperature Detection Circuit 30 - Temperature Detection Circuit The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (3)

[Claims] (1) In a control device for an air conditioner equipped with an inverter that provides a variable frequency output to the load, an overload state detection means is provided, and in the event of an overload, a dedicated output voltage and output frequency pattern is set. Drive the inverter under the conditions,
1. A control device for an air conditioner, characterized in that a normal pattern of output voltage and output frequency is set and an inverter is driven under these conditions except during times of overload. (2) The control device for an air conditioner according to claim 1, wherein the overload state detection means detects the overload state based on indoor temperature and outdoor temperature. (3) The air conditioner according to claim 1, wherein the overload state detection means detects the overload state based on the temperature of the indoor heat exchanger and the temperature of the outdoor heat exchanger. control device.