JPH04281393A - Controller for air conditioner - Google Patents

Abstract

PURPOSE:To provide a controller for an air conditioner which eliminates a load to a system due to stop of a compressor by increasing an operating time of the compressor by using a power element of an inverter to its maximum capacity in the controller for the conditioner having the inverter for controlling the revolution of the compressor. CONSTITUTION:Temperature detecting means 8 for detecting a case temperature of a power element of an inverter 6, sensing temperature deciding means 14 for deciding detected case temperature, and operating frequency deciding means 13 for inputting a signal from the means 14 and deciding the operating frequency of a compressor, are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner equipped with an inverter device for controlling the rotational speed of a compressor.

0002

BACKGROUND OF THE INVENTION In recent years, many air conditioner control devices have been used that control capacity by increasing or decreasing the rotational speed of a compressor using an inverter device that varies the frequency of a power source. As a conventional technique, for example, Utility Model Application No. 58-1535
There is a publication No. 89.

[0003] An example of the above-mentioned air conditioner control device will be described below with reference to the drawings. FIG. 4 is a schematic configuration diagram of a conventional air conditioner control device, FIG. 5 is a flowchart of its operation, and FIG. 6 is a diagram showing changes over time in the power element case temperature of the inverter circuit and the operating state of the compressor.

In FIG. 4, 1 is a three-phase commercial AC power supply;
2 is a converter circuit for converting alternating current power into direct current power, and the commercial alternating current power supply 1 is connected to an alternating current input section. 3 is an inrush current limiting resistor, 4 is an inrush current limiting relay, 5 is an electrolytic capacitor for smoothing DC power, the inrush current limiting resistor 3 is connected in parallel with the inrush current limiting relay 4, and one end is on the positive terminal side of the converter circuit 2; The other end is connected to the positive electrode side of the electrolytic capacitor 5. The negative electrode side of electrolytic capacitor 5 is connected to the negative electrode side of converter circuit 2 . 6 is an inverter circuit which inputs the DC power smoothed by the electrolytic capacitor 5, converts it into three-phase AC power, and outputs it to the compressor 7.

Reference numeral 8 denotes temperature detection means for detecting the temperature of the power element case of the inverter circuit 6. Reference numeral 9 designates an operation command input unit that determines whether to start or stop the compressor, 10 represents an inverter control means, 11 represents a relay drive means, and 12 represents a voltage detection means that detects the voltage of the electrolytic capacitor 5. Inverter control means 10 receives signals from operation command input section 9 and voltage detection means 12 and outputs signals to relay drive means 11 . The relay driving means 11 is an inrush current limiting relay 4
Outputs a signal to. Reference numeral 13 denotes operating frequency determining means, which inputs signals from the inverter control signal 10 and temperature detecting means 8 and outputs signals to the inverter circuit 6.

The operation of the conventional air conditioner control device configured as described above will be explained below with reference to FIGS. 5 and 6. In FIG. 5, first, in step a, the commercial AC power supply 1 is turned on. Next, in step b, the signal S1 is outputted from the operation command input section 9 to the inverter control means 10, and if "operation", the logic returns to step c and otherwise to step b. Next, in step c, the electrolytic capacitor 5 is charged via the converter circuit 2 and the inrush current limiting resistor 3, the charging voltage is detected by the voltage detection means 12, a signal S4 is output to the inverter control means 10, and the charging voltage is If is equal to or higher than the specified voltage, the logic returns to step d; otherwise, the logic returns to step c.

Next, in step d, the inverter control means 10
outputs the signal S2 to the relay driving means 11, and further outputs the signal S3 from the relay driving means 11 to the inrush current limiting relay 4.
output to turn on the inrush current limit relay 4. Next, in step e, the signal S5 is output from the inverter control means 10 to the operating frequency determining means 13 to determine the operating frequency. Next, in step f, the operating frequency determining means 13 outputs the signal S6 to the inverter circuit 6, and the inverter circuit 6 supplies the electric power converted from DC to three-phase AC to the compressor 7, and the compressor 7 starts operating. Start.

Next, in step g, the temperature detecting means 8 detects the power element case temperature of the inverter circuit 6 (hereinafter this temperature will be referred to as Tc), and outputs it as a signal S7 to the operating frequency determining means 13, and formula (1) is obtained. If the condition is satisfied, the logic proceeds to step h; otherwise, the logic proceeds to step f.

[0009]Tc≧T0...
・ (1) Here, T0 is smaller than the power element maximum allowable case temperature (hereinafter this temperature is referred to as Tcmax), and T0
The value takes into account the overshoot of c.

Next, in step h, the operating frequency determining means 13 outputs a signal S6 to the inverter circuit 6, and the compressor 7 is stopped. Next, in step i, the power element case temperature Tc is detected by the temperature detecting means 8, and outputted as a signal S7 to the operating frequency determining means 13. If the formula (2) is satisfied, proceed to step e; otherwise, proceed to step Proceed the logic to h.

[0011] Tc≦T1...
- (2) Here, T1 is a value smaller than the above-mentioned T0.

FIG. 6 shows the temporal change in the power element case temperature of the inverter circuit and the compressor operating state during the operations of steps e to i described above.

[0013]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional configuration, the case temperature setting value for power element protection is low, and the power element cannot be used to its maximum capacity, which not only shortens the compressor operating time. However, the disadvantage is that the load on the system increases due to repeated operation and stopping of the compressor.

The present invention solves the above-mentioned conventional problems, and provides an air conditioner control device that uses the power element to its maximum capacity to lengthen the compressor operation time and eliminates the load on the system due to compressor stoppage. This is what we provide.

[0015]

[Means for Solving the Problems] In order to achieve this object, the air conditioner control device of the present invention includes a converter circuit for converting AC power into DC power, and one end connected to the positive electrode side of the converter circuit. an inrush current limiting resistor; an electrolytic capacitor connected to the other end of the inrush current limiting resistor and smoothing the DC power converted by the converter circuit;
an inrush current limiting relay connected in parallel with the inrush current limiting resistor; an inverter circuit that inputs the DC power smoothed by the electrolytic capacitor and converts it into three-phase AC power to control the compressor; an operation command input section that determines operation/stop; a voltage detection means that detects the voltage of the electrolytic capacitor; an inverter control means that receives signals from the operation command input section and the voltage detection means; and the inverter control means. a relay driving means that receives a signal from the inrush current limiting relay and outputs a signal to the inrush current limiting relay; a temperature detection means that detects a case temperature of a power element of the inverter circuit; and a detection device that receives a signal from the temperature detection means as an input. The apparatus includes a temperature determining means, and an operating frequency determining means that receives signals from the inverter control means and the detected temperature determining means and outputs signals to the inverter circuit.

[0016]

[Operation] With this configuration, the power element case temperature of the inverter circuit is detected by the temperature detection means, the rate of increase in the case temperature is judged by the detection temperature judgment means, and based on the judgment result, the operating frequency determination means is used to determine the operating frequency of the compressor. By determining , the case temperature setting value for power element protection can be brought close to the power element allowable case temperature, and the power element can be used to its maximum capacity.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a control device for an air conditioner according to an embodiment of the present invention, FIG. 2 is an operation flowchart thereof, and FIG. 3 shows changes over time in the power element case temperature of the inverter circuit and the operating state of the compressor. It is a diagram. In Figure 1, 1 is a three-phase commercial AC power supply, 2 is a converter circuit, 3 is an inrush current limiting resistor, 4 is an inrush current limiting relay, 5 is an electrolytic capacitor, 6 is an inverter circuit, 7 is a compressor, and 9 is an operation In the command input section, 10 is an inverter control means, 11 is a relay drive means, and 12 is a voltage detection means, and since the above is the same as the conventional configuration shown in FIG. 4, a detailed explanation will be omitted.

Reference numeral 8 indicates a temperature detection means for detecting the temperature of the power element case of the inverter circuit 6, 13 indicates an operating frequency determination means, and 14 indicates a detected temperature determination means. The detected temperature determining means 14 receives the signal from the temperature detecting means 8, and the operating frequency determining means 13 receives the signal from the inverter control means 10 and the detected temperature determining means 14, and outputs the signal to the inverter circuit 6.

The operation of the air conditioner control device configured as described above will be explained below with reference to FIGS. 2 and 3. In FIG. 2, first in step 1, the commercial AC power supply 1 is turned on. Next, in step 2, the operation command input unit 9 outputs the signal S8 to the inverter control means 10, and if it is "operating", the process goes to step 3. Otherwise, it goes to step 2.
Return logic to. Next, in step 3, the electrolytic capacitor 5 is charged via the converter circuit 2 and the inrush current limiting resistor 3, the charging voltage is detected by the voltage detecting means 12, a signal S11 is output to the inverter controlling means 10, and the charging voltage is If is equal to or higher than the specified voltage, the logic returns to step 4; otherwise, the logic returns to step 3.

Next, in step 4, the inverter control means 10
The signal S9 is outputted to the relay driving means 11, and the signal S10 is further outputted from the relay driving means 11 to the inrush current limiting relay 4 to turn on the inrush current limiting relay 4. Next, in step 5, the inverter control means 10 outputs the signal S1.
2 is output to the operating frequency determining means 13 to determine the operating frequency. Next, in step 6, the operating frequency determining means 1
3 outputs a signal S15 to the inverter circuit 6, and from the inverter circuit 6, the power converted from DC to three-phase 75Hz AC is supplied to the compressor 7, and the compressor 7 starts operating at 75Hz.

Next, in step 7, the temperature detecting means 8 detects the power element case temperature of the inverter circuit 6 (hereinafter this temperature will be referred to as Tc), and outputs it as a signal S13 to the detected temperature determining means 14. If the condition is satisfied, the logic proceeds to step 8; otherwise, the logic proceeds to step 6.

[0022] Tc ≧ T2 (
3) Here, T2 is a preset value.

Next, in step 8, the detected temperature determining means 14 outputs the signal S14 to the operating frequency determining means 13, and the operating frequency determining means 13 further outputs the signal S15 to the inverter circuit 6, so that the compressor 7 is operated at 70Hz. Become. Next, in step 9, the temperature detecting means 8 detects the case temperature Tc.
is detected and outputted as a signal S13 to the detected temperature determination means 14, and if the equation (4) is satisfied, the logic advances to step 10; otherwise, the logic advances to step 8.

[0024] Tc ≧ T3 (
4) Here, T3 is a value determined from the rate of increase θ1 of the power element case temperature when the compressor is operated at 70 Hz. Rise rate θ1
is (T3-T2)/(t2-t1) as shown in FIG.

Next, in step 10, the detected temperature determining means 14 outputs a signal S14 to the operating frequency determining means 13, and the operating frequency determining means 13 further outputs a signal S15 to the inverter circuit 6, so that the compressor 7 is operated at 65 Hz. Become. Next, in step 11, the case temperature Tc is detected by the temperature detection means 8, and the detected temperature determination means 14 detects the case temperature Tc as a signal S13.
If the formula (5) is satisfied, go to step 12.
Otherwise, the logic advances to step 10.

[0026] Tc ≧ T4 (
5) Here, T4 is a value determined from the rate of increase θ2 of case temperature when the compressor is operated at 65 Hz. Next, in step 12, the detected temperature determining means 14 outputs the signal S14 to the operating frequency determining means 13, and the operating frequency determining means 13 further outputs the signal S15 to the inverter circuit 6.
Hz operation.

Next, in step 13, the temperature detection means 8
The case temperature Tc is detected and output as a signal S13 to the detected temperature determining means 14, and if the equation (6) is satisfied, the logic advances to step 14, otherwise the logic advances to step 12.

[0028] Tc ≧ T5 (
6) Here, T5 is a value determined from the rate of increase θ3 of the case temperature when the compressor is operated at 60 Hz. Next, in step 14, the detected temperature determining means 14 outputs the signal S14 to the operating frequency determining means 13, and the operating frequency determining means 13 further outputs the signal S15 to the inverter circuit 6.
Hz operation. At this time, the power element maximum allowable case temperature (hereinafter this temperature will be referred to as Tcmax) is a value that takes into consideration the overshoot at the start of 55 Hz operation.

Next, in step 15, the temperature detection means 8
The case temperature Tc is detected and output as a signal S13 to the detected temperature determining means 14, and if the equation (7) is satisfied, the logic advances to step 6, otherwise the logic advances to step 14.

[0030] Tc≦T2 (
7) FIG. 3 shows the temporal change in the power element case temperature of the inverter circuit and the compressor operating state during the operations of steps 5 to 15 described above.

As described above, according to this embodiment, the signal S13 is inputted from the temperature detection means 8 for detecting the case temperature of the power element of the inverter circuit 6 to the detected temperature determination means 14,
The operating frequency of the compressor 7 can be varied by providing a configuration in which the signal 14 is input from the detected temperature determining means 14 to the driver fraction determining means 13, and the signal S15 is further input from the operating frequency determining means 13 to the inverter circuit 6. Therefore, the power element can be used at its maximum capacity up to near the maximum permissible case temperature of the power element, and the operating time can be extended without stopping the compressor 7.

Although the compressor operating frequency is set in 5 Hz increments, it is also possible to set the compressor operating frequency in consideration of the system capacity.

[0033]

As described above, the present invention provides a converter circuit for converting AC power into DC power, an inrush current limiting resistor whose one end is connected to the positive electrode side of the converter circuit, and the other end of the inrush current limiting resistor. an electrolytic capacitor connected to the converter circuit to smooth the DC power converted by the converter circuit; an inrush current limiting relay connected in parallel with the inrush current limiting resistor; an inverter circuit that converts the AC power into alternating current power and controls the compressor; an operation command input section that determines whether to start or stop the compressor; a voltage detection means that detects the voltage of the electrolytic capacitor; an inverter control means that receives a signal from the voltage detection means; a relay drive means that receives a signal from the inverter control means and outputs a signal to the inrush current limiting relay; and a case temperature of a power element of the inverter circuit. a temperature detecting means to detect; a detected temperature determining means receiving a signal from the temperature detecting means; and an operating frequency determining means receiving signals from the inverter control means and the detected temperature determining means and outputting a signal to the inverter circuit. An excellent air conditioner control device that allows the power element to be used to its maximum capacity by providing a means to do so, allows continuous operation of the compressor without stopping, and eliminates the load on the system due to repeated running and stopping of the compressor. It is possible to realize this.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an air conditioner control device in an embodiment of this description.

[Figure 2] Operation flowchart in Figure 1

[Figure 3] Time chart showing the temporal change in power element case temperature and compressor operating status in Figure 1

[Figure 4] Schematic configuration diagram of a conventional air conditioner control device

[Figure 5] Operation flowchart in Figure 4

[Fig. 6] Time chart showing temporal changes in power element case temperature and compressor operating status in Fig. 4.

[Explanation of symbols]

1 Three-phase commercial AC power supply 2 Converter circuit 3 Inrush current limiting resistance 4 Inrush current limit relay 5　Electrolytic capacitor 6 Inverter circuit 8 Temperature detection means

Claims (1)

[Claims] 1. A converter circuit for converting alternating current power into direct current power, an inrush current limiting resistor having one end connected to the positive terminal side of the converter circuit, and an inrush current limiting resistor connected to the other end of the inrush current limiting resistor, the converter circuit comprising: An electrolytic capacitor smoothes the converted DC power, an inrush current limiting relay connected in parallel with the inrush current limiting resistor, and the DC power smoothed by the electrolytic capacitor is inputted and converted into three-phase AC power. an inverter circuit that controls the compressor;
an operation command input section that determines whether to start or stop the compressor; a voltage detection means that detects the voltage of the electrolytic capacitor; an inverter control means that receives signals from the operation command input section and the voltage detection means; Relay driving means receives a signal from the inverter control means and outputs a signal to the inrush current limiting relay; temperature detection means detects the case temperature of the power element of the inverter circuit; and inputs the signal from the temperature detection means. a detection temperature determination means,
A control device for an air conditioner, comprising operating frequency determining means for receiving signals from the inverter controlling means and the detected temperature determining means and outputting signals to the inverter circuit.