JP2002327687A - Pre-heating control device of compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pre-heating control device of a compressor capable of controlling the pre-heating energizing current to the compressor when the supply voltage varies in an air conditioner. SOLUTION: The pre-heating control device has a comparing/judging means for detecting the supply voltage of the compressor 6, comparing the detected supply voltage and a standard voltage, and judging the size of the supply voltage. A drive circuit of the compressor is controlled by a control means 12 based on the result of the judgement and the pre-heating energizing current is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in preheating control of a compressor which is performed in an air conditioner in order to prevent a decrease in the startability of a compressor and a reduction in efficiency of a heating operation.

2. Description of the Related Art When a compressor used in an air conditioner or the like is started in a cooled state, a large amount of liquid-cooled soot is dissolved in lubricating oil, the lubricating oil becomes thin, and damage to the compressor may occur. May be invited. Therefore, in order to prevent this and to improve the start-up at the time of heating, a method of monitoring the temperature of the compressor and the outside air temperature and preheating the coil of the compressor has conventionally been adopted. Regarding the method of controlling the preheating of the compressor, an energizing method in which a weak current flows in two of the three phases of the compressor, a so-called rotating magnetic field that does not rotate the compressor, and an energizing method that creates a rotating magnetic field. Even so, various control methods such as a method of energizing the energizing speed at a considerably high speed and preventing the compressor from rotating were taken,
Each had its pros and cons. The preheating control of the compressor is performed by turning on / off a power transistor constituting a driving circuit of the compressor through a driver such as a photocoupler by a microcomputer output based on preheating energization data inside the microcomputer as a control means regardless of the magnitude of the power supply voltage. By turning it off, the compressor was preheated. The preheating energizing current level of the compressor, the so-called preheating level, is determined by the O
It is determined by changing the duty ratio of N / OFF.

However, the output of only one data determined by the microcomputer may cause the destruction of a semiconductor such as a power transistor due to the magnitude of the power supply voltage or the like, or the startup at the time of heating may be extremely slow. May occur. FIG. 1 shows an example in which an inverter circuit is used as a drive circuit of an air conditioner. An AC power supply voltage is rectified by a diode 1 and smoothed by a voltage doubler capacitor 2 and a smoothing capacitor 3 at the rear, and the DC voltage is doubled. The DC voltage is used as a compressor drive voltage and is supplied to the compressor 6 via the inverter circuit 5 including the power transistor 4. In such a circuit configuration, for example, when the power supply voltage is high, the preheating energizing current of the compressor 6 increases in proportion thereto, and when the power supply voltage is low, the preheating energizing current of the compressor 6 decreases in proportion thereto. Become. When the preheating energizing current of the compressor 6 increases, the temperature of the chip of the power transistor 4 or the regenerative diode 7 that flows the current increases, and when the ambient temperature or the like is used, the chip of the power transistor 4 increases. There is a risk that these chips may be destroyed at the highest temperature. Also, if the preheating energizing current of the compressor is small, the energy supplied to the coil in the compressor is small, causing a problem that the startup at the time of heating is not as good as expected. Therefore, in the development stage of the microcomputer, the data of the preheating current of the compressor may be determined while considering the fluctuation of the power supply voltage so that the above-mentioned problem does not occur in one microcomputer preheating current data. Is very difficult. Therefore, when the compressor coil is preheated for the purpose of improving the startability of the compressor and the efficiency of the heating operation, when the preheating level fluctuates due to the power supply voltage or the like, the startability of the compressor and the efficiency of the heating operation are increased. Therefore, there is a problem that the performance is deteriorated and the power element for driving the compressor is destroyed, and some solution has been awaited. In view of the above, the present invention provides a control circuit for controlling a preheating energizing current to a compressor when a power supply voltage fluctuates, thereby reducing the startability of a compressor and the efficiency of a heating operation. It is an object of the present invention to provide a compressor preheating control device that prevents the power element that drives the compressor from being destroyed.

In order to achieve the above object, according to the present invention, before the compressor is preheated, the compressor drive power supply voltage is monitored to determine the magnitude of the power supply voltage. The preheating energizing current is adjusted by controlling the compressor drive circuit accordingly. That is, the compressor preheating control device according to the present invention includes a detecting unit that detects a power supply voltage of the compressor, a comparison determining unit that compares the detected voltage with a reference voltage to determine the magnitude of the voltage, and a determination result. It is characterized by comprising control means for controlling the drive circuit of the compressor accordingly to adjust the preheating energizing current. The comparing and judging means includes first comparing and judging means for comparing the magnitude of a detected voltage with a first reference voltage, and second comparing and judging comparing the magnitude of a detected voltage and a second reference voltage higher than the first reference voltage. Means for controlling the drive circuit of the compressor based on the preheating energization data set in accordance with the first and second reference voltages based on the determination results of the first and second comparison and determination means. , To adjust the preheating current. Specifically, when the detected voltage is lower than the first reference voltage, the control unit turns on / off a power transistor constituting a drive circuit of the compressor based on preheating energization data set in accordance with the first reference voltage. Increase the duty ratio of
When the detected voltage is higher than the second reference voltage, the ON / OFF duty ratio of the power transistor is reduced based on the preheating energization data set according to the second reference voltage to adjust the preheating energizing current. The comparison determination means and the control means can be incorporated in a single microcomputer. On the other hand, it is also possible to use a comparison determining means constituted by a voltage comparator and a photocoupler. That is, detection means for detecting the power supply voltage by dividing the voltage between the DC power supply voltages for driving the compressor by a resistor, a voltage comparator for comparing the detected voltage with a reference voltage, and operating according to the output of the voltage comparator. Comparison / decision means constituted by a photocoupler to be turned on and off / on of a power transistor constituting a drive circuit of a compressor in response to a signal from the photocoupler.
And a control means for adjusting the preheating current by adjusting the duty ratio of the compressor. Two types of detection circuits including a high-voltage detection circuit and a low-voltage detection circuit are provided as the detection circuit including the detection unit and the comparison determination unit, and the control unit determines whether the voltage is higher than a limit reference voltage set in each detection circuit. Reduces the duty ratio based on the preheating energization data set according to the reference voltage, and adjusts the preheating energizing current by increasing the duty ratio based on the preheating energization data set according to the reference voltage when the voltage is low. Like that. It is desired that the detection of the power supply voltage be performed in a state where load fluctuation is small, that is, when the compressor and the fan are stopped and before preheating.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preheating control device for a compressor of an air conditioner using an inverter circuit as a drive circuit will be described below. The basic circuit configuration for driving the compressor is the same as that shown in FIG. 1. The AC power supply voltage is rectified by a diode 1, smoothed by a rear voltage-doubling capacitor 2 and a smoothing capacitor 3, and converted into a DC voltage.
The DC voltage is supplied to the compressor 6 via the inverter circuit 5 including the power transistor 4 as a compressor drive voltage. FIG. 2 shows a control circuit for controlling the preheating current when the power supply voltage is high. A voltage obtained by dividing the voltage between the DC power supply voltages in FIG. 1 by a resistor 8a is input to the minus side of a voltage comparator (comparator) 9a. (Hereinafter referred to as input A), and a reference voltage determined by the resistor 10a is input to the other input + side (hereinafter referred to as input B) of the voltage comparator 9a. This reference voltage is the maximum allowable voltage. The voltage of the input A of the voltage comparator 9a is
When the voltage of the voltage comparator 9a becomes larger than the voltage of
It is connected so that it may become a level (0V). An increase in the voltage of the input A means that the DC voltage of the compressor 6 has become higher than the maximum allowable voltage. The output of the voltage comparator 9a is connected to a photocoupler 11a for power supply insulation. When the output of the voltage comparator 9a becomes L level (0 V), the photocoupler 11a operates. When the photocoupler 11a operates, a signal is input to the microcomputer 12 to inform the microcomputer 12 that the DC voltage of the compressor 6 has increased. Based on this, the microcomputer 12 turns on / off the power transistor 4 based on preheating energization data set in advance according to the reference voltage.
The duty ratio of the FF is reduced to adjust the preheating energizing current of the compressor 6. FIG. 3 shows a control circuit when the power supply voltage is low, and a voltage obtained by dividing the voltage between the DC power supply voltages in FIG. 1 by the resistor 8b is input to the + side of a voltage comparator (comparator) 9b (hereinafter, referred to as a control circuit). Input C)
A reference voltage determined by a resistor 10b is input to the other input side (hereinafter, input D) of the voltage comparator 9b. When the voltage of the input C of the voltage comparator 9b becomes smaller than the voltage of the input D, the output of the voltage comparator 9b is connected to the L level (0 V). The decrease in the voltage of the input C means that the DC voltage of the compressor 6 has decreased. A photocoupler 11b for power supply insulation is connected to the output of the voltage comparator 9b. When the output of the voltage comparator 9b becomes L level (0 V), the photocoupler 11b operates. When the photocoupler 11b operates, a signal is input to the microcomputer 12 to inform the microcomputer 12 that the DC voltage of the compressor 6 has increased. Based on this, the microcomputer 12 adjusts the preheating energizing current of the compressor 6 by increasing the ON / OFF duty ratio of the power transistor 4 for the lower power supply voltage based on the preheating energizing data set in advance according to the reference voltage. Thus, the startability of the compressor 6 is improved. Of course, if none of the above determination signals is input, the microcomputer 12 determines that the DC power supply voltage is rated (100 V).
It is determined that the current is 100 V for the model, and the preheating energizing current of the compressor is not adjusted. The above operation state is summarized as follows. Voltage Large Rating Small Photocoupler 11a on off off Photocoupler 11b off off on Duty ratio Decrease Unadjusted Increase Fig. 4 shows the control state when the comparison determination means and the control means are incorporated in a single microcomputer. In the flowchart illustrating an example, the comparison and determination unit includes a first comparison and determination unit 13 that compares the magnitude of a detection voltage V and a first reference voltage V1, a second comparison voltage that is higher than the detection voltage V and the first reference voltage V1. And a second comparing / determining means for comparing the magnitude with V2. The controlling means is configured to control the preheating energizing data set in accordance with the first and second reference voltages based on the determination results of the first and second comparing / determining means. The control circuit controls the drive circuit of the compressor based on the first reference voltage V1. Specifically, when the detection voltage V is lower than the first reference voltage V1, the control circuit responds to the first reference voltage V1. The ON / OFF duty ratio of the power transistor constituting the drive circuit of the compressor is increased based on the preheating energization data set in advance, and when the detection voltage V is higher than the second reference voltage V2, the ON / OFF duty ratio depends on the second reference voltage V2. The ON / OFF duty ratio of the power transistor is reduced on the basis of the preheating energizing data set in advance to adjust the preheating energizing current. When the detected voltage V is higher than the first reference voltage V1 and lower than the second reference voltage V2, it is determined that the voltage is appropriate.

According to the present invention, before the compressor is preheated, the compressor drive power supply voltage is monitored and compared with the allowable upper and lower limit reference voltages to determine the magnitude of the power supply voltage. The preheating energizing current is adjusted based on the preheating energizing data set in advance according to the reference voltage by controlling the driving circuit of the compressor according to the reference voltage. In addition, the preheating current to the compressor can be controlled within a predetermined range, which can prevent the startability of the compressor and the efficiency of the heating operation from decreasing, and do not cause the destruction of the power element for driving the compressor. A compressor preheating control device could be provided.

[Brief description of the drawings]

FIG. 1 is a drive circuit diagram of a compressor using an inverter circuit.

FIG. 2 shows an example of a control circuit for controlling a preheating energizing current when a power supply voltage is high.

FIG. 3 shows an example of a control circuit for controlling a preheating energizing current when a power supply voltage is low.

FIG. 4 is a flowchart showing an example of a control state by a microcomputer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diode (rectifier) 2 Double voltage capacitor 3 Smoothing capacitor 4 Power transistor 5 Inverter circuit 6 Compressor 7 Regeneration diode chip 8a, 8b Resistance 9a, 9b Voltage comparator (comparator) 10a, 10b Resistance 11a, 11b Photocoupler 12 Microcomputer 13 First comparison / determination means 14 Second comparison / determination means V Detection voltage V1 First reference voltage V2 Second reference voltage

Claims (6)

[Claims] 1. A detecting means for detecting a power supply voltage of a compressor, a comparing and judging means for judging a magnitude of a voltage by comparing the detected voltage with a reference voltage, and controlling a drive circuit of the compressor in accordance with the judgment result. And a control means for adjusting the preheating current through the compressor. 2. The comparison / judgment means compares the detected voltage with a first reference voltage, and compares the detected voltage with a second reference voltage higher than the first reference voltage. And the second comparing and judging means performs the first comparing and judging based on the judgment results of the first and second comparing and judging means.
2. The preheating control device for a compressor according to claim 1, wherein a driving circuit of the compressor is controlled based on the preheating energization data set according to the second reference voltage to adjust the preheating energizing current. 3. The control means according to claim 1, wherein when the detected voltage is lower than said first reference voltage, said control means turns on / off a power transistor constituting a drive circuit of said compressor based on preheating energization data set according to said first reference voltage. When the detected voltage is higher than the second reference voltage, the ON / OFF duty ratio of the power transistor is reduced based on the preheating energization data set in accordance with the second reference voltage to increase the preheating energizing current. 3. The preheating control device for a compressor according to claim 2, wherein: 4. A detecting means for detecting a power supply voltage by dividing a voltage between a DC power supply voltage for driving a compressor by a resistor, a voltage comparator for comparing the detected voltage with a reference voltage, and an output of the voltage comparator. A comparison / judgment means constituted by a photocoupler which operates in response to the signal; and a preheating energizing current adjusted by receiving a signal from the photocoupler and adjusting an ON / OFF duty ratio of a power transistor constituting a drive circuit of the compressor. A preheating control device for a compressor, the control device comprising: 5. A detecting circuit comprising the detecting means and the comparing and judging means comprises a high voltage detecting circuit and a low voltage detecting circuit,
The control means reduces the duty ratio based on the preheating energization data set according to the reference voltage when the voltage is higher than the limit reference voltage set in each detection circuit, and when the voltage is low, the duty ratio is reduced to the reference voltage. 5. The preheating control device for a compressor according to claim 4, wherein the duty ratio is increased based on the preheating energization data set accordingly to adjust the preheating energizing current. 6. The preheating control device for a compressor according to claim 1, wherein the detection of the power supply voltage is performed before the preheating when the compressor and the fan are stopped.