KR101059817B1 - Cooling system for power electronic components - Google Patents

Abstract

The present invention relates to a cooling device for power electronic components of a refrigeration system, and in particular, the present invention is controlled by using a sensor that is basically mounted in a refrigeration system, instead of a temperature sensor mounted on a conventional heat sink, material costs according to additional sensor mounting. It is possible to control the opening of the refrigerant valve more quickly and effectively because it can be controlled within a small fluctuation range by using factors such as pressure and rotation frequency as a control factor for adjusting the opening amount of the refrigerant valve. .

To this end, the present invention comprises a compressor, a condenser, an evaporator, and a cooler, and in the power electronic component cooling apparatus of a refrigeration system for cooling the power electronic components by arranging the cooler in the power electronic components driving the compressor, the condenser outlet Refrigerant supply line for supplying a part of the coolant to the cooler, characterized in that it comprises a refrigerant valve provided to be adjustable in the refrigerant supply line, and a control unit for controlling the opening degree of the refrigerant valve in accordance with the operation degree of the compressor.

Description

COOLING DEVICE FOR COMPRESSOR DRIVING ELEMENT IN A REFRIGERATING SYSTEM}

1 is a refrigerant cycle diagram of an apparatus for cooling power electronic components of a conventional refrigeration system.

2 is a control block diagram of a power electronic component cooling apparatus of a refrigeration system according to the present invention.

3 is a control flowchart of a method for cooling power electronic components of a refrigeration system according to the present invention.

4 is a control flowchart of a method for cooling power electronic components of a refrigeration system according to an embodiment of the present invention.

[Description of the Reference Numerals]

100: compressor 101: condenser

102 evaporator 103 expansion valve

104: refrigerant line 105: frequency variable drive device

106: heat sink 107: IGBT

108: refrigerant supply line 109: cooler

110: refrigerant discharge line 111: refrigerant valve

112: pressure sensor 113: control unit

114: temperature sensor

The present invention relates to an apparatus for cooling power electronic components of a refrigeration system, and more particularly, to an apparatus for cooling power electronic components of a refrigeration system for cooling power electronic components of a frequency variable driving apparatus provided for driving an inverter compressor using a refrigerant. will be.

In general, refrigeration systems require inverter compressors that are variable in frequency because the required load conditions vary with ambient temperature conditions. Therefore, a variable frequency motor (for example, BC motor) should be used in the inverter compressor, and a control device for driving the inverter should be installed in the refrigeration system. Most of these controls are installed in outdoor units containing condensers and compressors.

In such a refrigeration system, since a considerable amount of heat is generated in the power electronic components constituting the variable frequency control device, proper cooling is required to protect the components and the system.

In the related art, as shown in FIG. 1, the frequency variable control device 10 includes an aluminum block-type heat sink (a block of insulating gate anode transistor (IGBT) 11), which is a power electronic component that is known to generate the largest amount of heat. 12) and a structure through which a copper pipe 15 connected to the outlet of the condenser 13 and the outlet of the evaporator 14 (or the compressor inlet) of the refrigeration system in the block of the heat sink 12 is shown. In addition, the refrigerant valve 16 and the valve sensor 17 for controlling the supply of the refrigerant of the refrigerant line is mounted, and the microprocessor 18 may be mounted for more precise control.

As shown in FIG. 1, the control unit 18 senses a temperature through a valve sensor (mainly a temperature sensor) 17 attached to a heat sink 12, and maintains a temperature between 50 ° C. and 100 ° C. as an example of a stable temperature range. Adjust the opening of (16).

When the coolant valve 16 is opened, the coolant is supplied through the coolant supply line 13a connected to the outlet of the condenser 13 of the coolant system, and passes through the blocks of the heat sink 12 to heat through heat exchange with the heat sink 12. The temperature of the IGBT 11 is maintained at a stable temperature by taking off. The refrigerant, which has become hot through heat exchange, is circulated in the refrigeration system by being connected to the evaporator 14 outlet or the compressor 19 inlet through the refrigerant discharge line 14a.

However, conventionally, the temperature is mainly sensed by a separate temperature sensor 17 mounted on the block surface of the heat sink 12 or the surface of the refrigerant pipe passing through the heat sink 12 to adjust the opening degree of the refrigerant valve 16. Normally, temperature sensors are less efficient because of their slower responsiveness or response compared to other control factors, ie rotational frequency or pressure. In particular, it is effective to select and control a fast response factor for cooling power electronic components. In addition, additional material costs increase as additional temperature sensors are additionally mounted for valve control.

On the other hand, in the related art, when the temperature sensor is separated, since the temperature is sensed lower than the actual radiator temperature, proper cooling is not performed, and the parts may overheat and damage the driving apparatus.

The present invention is to solve the above problems, an object of the present invention is to provide a cooling device for power electronic components of the refrigeration system capable of more efficiently cooling the power electronic components of the frequency variable drive device provided for the drive of the compressor. To provide.

The cooling device for power electronic components of the refrigeration system of the present invention for achieving the above object is provided with a compressor, a condenser, an evaporator, and a cooler, and the cooler is disposed on the power electronic components for driving the compressor to the power A power electronic component cooling apparatus of a refrigeration system for cooling electronic components, comprising: a refrigerant supply line for supplying a part of refrigerant at an outlet of the condenser to the cooler, a refrigerant valve provided at an adjustable opening in the refrigerant supply line, It includes a control unit for adjusting the opening degree of the refrigerant valve in accordance with the degree of operation.

The control unit may determine the operation degree of the compressor based on the discharge pressure of the compressor.

The controller may determine the operation degree of the compressor based on the rotation frequency determined by the discharge pressure and the discharge temperature of the compressor.

The control unit may increase the opening amount of the refrigerant valve as the operation degree of the compressor is higher.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

In the present invention, by using a pressure sensor or a temperature sensor mounted on the outlet side of the compressor for the control of the refrigeration system, the opening degree of the refrigerant valve for controlling the amount of refrigerant supplied to the cooler for the purpose of cooling the power electronic components of the variable frequency drive device. Adjust.

2 is a control block diagram of a power electronic component cooling apparatus of a refrigeration system according to the present invention. As shown in FIG. 2, the refrigeration system includes a compressor 100 connected by a refrigerant line, a condenser 101, an evaporator 102, and an expansion valve 103. When the refrigeration system is operated, the gas refrigerant passing through the compressor 100 is compressed to high temperature and high pressure and is moved to the condenser 101. Through the heat exchange in the condenser 101, the refrigerant becomes a high pressure liquid refrigerant and expands the expansion valve ( Go to 103). The liquid refrigerant, which has passed through the expansion valve 103 and is in a low pressure low temperature state, becomes a refrigerant of low pressure gas through heat exchange in the evaporator 102 and moves to the compressor 100. This compression-condensation-expansion-evaporation-compression process is repeated.

The compressor 100 is an inverter compressor for varying the compression capacity by changing the rotational speed of the compressor motor by the variable frequency. In order to drive the inverter compressor, a frequency variable driving device 105 for controlling the rotational speed of the compressor motor of the inverter compressor is required. This frequency variable drive device 105 is typically equipped with a plurality of power electronic components that require cooling in order to operate optimally over the operating range of the refrigeration system to the heat sink 106. The core component of such power electronic components is an insulated gate bipolar transistor (hereinafter referred to as IGBT) 107 and occupies most of the heat generated in the frequency variable driving device 105.

Therefore, the refrigeration system has a cooler 109 provided in the heat sink 106 to cool the variable frequency drive device 105 in the refrigerant supply line 108 branched separately from the outlet of the condenser 101 to cool it. do. By the cooler 109, the IGBT 107 in the variable frequency drive device 105 is deprived of heat energy by heat exchange of the refrigerant and cooled.

The cooler 32 is zigzag mounted to the heat sink 106 to provide the maximum contact area between the heat sink 106 and the cooler 109. The cooler 109 is fitted into the heat sink 106 and is a copper pipe of a predetermined length having an inlet and an outlet.

The inlet of the cooler is connected to the outlet of the condenser 101 by the refrigerant supply line 108, and the outlet of the cooler 109 is also connected to the outlet of the evaporator 102 or the inlet of the compressor 100 by the refrigerant discharge line 110. do.

In order to regulate the refrigerant in the refrigerant line, an opening degree adjustable refrigerant valve 111 is installed in the refrigerant supply line 108. Through this, the refrigerant is lowered from a high pressure to a low pressure to provide a low temperature refrigerant to the cooler 109 and to control the amount of the refrigerant flowing into the inlet of the cooler 109. The opening degree control of the refrigerant valve 111 is provided with a temperature sensor in a conventional frequency variable drive device, and instead of a method of controlling by a temperature value detected through the temperature sensor, the compressor discharge side pressure sensor basically installed in the refrigerating system. Control using 112. It is possible to determine the operation degree of the compressor 100 as the discharge pressure of the compressor 100 because the calorific value of the frequency variable drive device 105 is affected by the state amount of the high pressure side of the refrigeration system, so that the frequency variable drive device 105 This is because it is possible to estimate the degree of heat generation. That is, when the pressure of the refrigerant discharged from the compressor 100 is increased, the entire refrigeration system is overheated, and the operation degree of the compressor 100 is increased, thereby causing an overload of the frequency variable drive device 105, resulting in an overload current. This increases, which leads to an increase in the amount of heat generated by the IGBT 107.

The opening degree adjustment of the refrigerant valve is performed by the control unit 113 which is electrically connected to the pressure sensor 112 and the refrigerant valve 111 to perform the overall control.

The control unit 113 detects the discharge pressure of the compressor 100 through the pressure sensor 112 and determines the opening degree of the refrigerant valve 111 by determining the operation degree of the compressor 100 based on the detected pressure. The opening degree of the refrigerant valve 111 is adjusted according to the opening amount. In this case, not only the opening amount of the refrigerant valve 111 can be adjusted by using the discharge pressure as a control factor, but also the operation degree of the compressor 100 is more closely related to the rotation frequency of the compressor 100. It is also possible to adjust the opening amount of the refrigerant valve by using the rotation frequency determined from the discharge temperature as a control factor.

Therefore, conventionally, by selecting the temperature of the heat sink as the control factor, the variation of the control is large because the reaction is relatively slow, while in the present invention, the control factors such as pressure and rotation frequency are selected more quickly and effectively. You can do it. In addition, the temperature sensor for sensing the temperature of the heat sink can be removed, which is advantageous in terms of overall manufacturing cost.

Hereinafter, a method of cooling the power electronic components of the refrigeration system in the present invention.

3, first, in step S100, the control unit 113 operates the refrigeration system. At this time, the compressor 100 is driven and the expansion valve 103 and the refrigerant valve 111 are opened to the initial opening degree. In the case of the refrigerant valve 111, it is opened to the minimum opening degree at the beginning of operation, and control is started based on the discharge pressure value periodically detected after a certain time.

After that, the control unit 113 detects the discharge pressure of the compressor 100 through the pressure sensor 112 provided on the discharge side of the compressor 100 in steps S110 and S120, and based on the detected discharge pressure, the compressor 100. Judge the driving degree. At this time, the higher the discharge pressure of the compressor 100, the greater the degree of operation of the compressor 100, the smaller it is determined that the degree of operation of the compressor 100 is less.

Therefore, the following control schemes can be suggested. In the first way. The control unit 113 determines that the refrigerant valve 111 is “up” or “up” in steps S130 to 150 depending on whether the operation degree of the compressor 100 is “up”, “middle” or “low” as a result of the determination in step S120. Open with the difference of opening amount as "middle" and "low". In the second method, a correlation between the opening degree of the refrigerant valve 111 and the discharge pressure value is generated. By inputting this correlation into the basic control algorithm of the air conditioner, the opening degree of the refrigerant valve 111 is automatically calculated by the discharge pressure value periodically detected, and the control unit changes the opening degree of the refrigerant valve according to the calculated opening degree. Let's do it. At this time, the adjustment period of the refrigerant valve opening degree is set based on the pressure detection period. In other words, when the pressure detection cycle is small (less than 30 seconds), the refrigerant valve opening period is maintained at about twice (1 minute) as the pressure detection period, and when the pressure detection period is 30 seconds or more, the refrigerant valve opening period is the pressure. Set the same as the detection period. This is to maintain the lifetime and reliability of the refrigerant valve due to the frequent change of the refrigerant valve opening degree.

Meanwhile, as described above, instead of adjusting the opening amount of the refrigerant valve 111 by using the discharge pressure of the compressor 100 as a control factor, the compressor 100 to more accurately determine the operation degree of the compressor 100. The opening degree of the refrigerant valve 111 can be adjusted by using the rotation frequency of the control factor.

Referring to FIG. 4, first, in step S200, the control unit 113 operates the refrigeration system. At this time, the compressor 100 is driven and the expansion valve 103 and the refrigerant valve 111 are opened to the initial opening degree.

After that, the control unit 113 detects the discharge pressure of the compressor 100 through the pressure sensor 112 provided on the discharge side of the compressor 100 in steps S210, S220, and S230, and the temperature sensor 114 provided on the discharge side of the compressor 100. Detects the discharge temperature of the compressor 100 through the), and determines the rotation frequency of the compressor 100 from the detected discharge pressure and the discharge temperature.

The controller 113 determines the degree of operation of the compressor 100 based on the rotation frequency of the compressor 100 determined in step S240. At this time, it is determined that the higher the rotational frequency of the compressor 100, the greater the degree of operation of the compressor 100, and the smaller the degree of operation of the compressor 100. In this way, the operation of the compressor can be more precisely determined.

Therefore, the two control schemes as described above can be proposed. In the first method, the control unit 113 determines that the operation degree of the compressor 100 is "up", "medium" or "low" according to the determination result of step S240, and the refrigerant valve 111 in steps S250 to 270. Open with the difference of opening amount as “up”, “middle” and “low”. In the second method, a correlation between the opening rate and the rotational frequency of the refrigerant valve 111 is generated. By inputting this correlation into the basic control algorithm of the air conditioner, the rotational frequency is calculated based on the discharge pressure and the discharge temperature value periodically detected, and the opening degree of the refrigerant valve 111 is automatically calculated through the correlation to control the controller. The opening degree of the refrigerant valve is changed according to the opening degree calculated in. The control method based on the rotational frequency accurately determines the operating state of the compressor and adjusts the opening degree of the refrigerant valve, so that the opening degree can be adjusted more precisely and efficiently.

On the other hand, the refrigerant valve opening period is set in the manner mentioned in the control method using the discharge pressure.

As described in detail above, the present invention has the effect of reducing the material cost due to the additional sensor by controlling by using a pressure sensor basically mounted on the refrigeration system, instead of the temperature sensor mounted on a conventional heat sink. .

In addition, the present invention can control the opening degree of the refrigerant valve more quickly and effectively because it is possible to control within a small fluctuation range by selecting a factor such as pressure and rotation frequency as a control factor for adjusting the opening amount of the refrigerant valve. It works.

In addition, the present invention can accurately determine the operation degree of the compressor using the rotational frequency of the compressor as a control factor has the effect of cooling the power electronic components more effectively.

Claims (4)

A power electronic component cooling apparatus of a refrigeration system, comprising a compressor, a condenser, an evaporator, and a cooler, wherein the cooler is disposed in a power electronic component for driving the compressor to cool the power electronic component. A refrigerant supply line for supplying some refrigerant at the outlet of the condenser to the cooler; A refrigerant valve provided to be adjustable in the refrigerant supply line; And a control unit for adjusting the opening degree of the refrigerant valve according to the operation degree of the compressor. The apparatus of claim 1, wherein the controller determines an operation degree of the compressor based on the discharge pressure of the compressor. The apparatus of claim 1, wherein the controller determines the operation degree of the compressor based on a rotation frequency determined by the discharge pressure and the discharge temperature of the compressor. The apparatus of claim 1, wherein the control unit increases the opening amount of the refrigerant valve as the operation degree of the compressor increases.

Images