JP2013193632A - Cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of efficiently cooling an inverter device together with an electric motor, in a system using the inverter device for controlling the drive of the electric motor.SOLUTION: A cooling system 10 cools a motor 30 as a driving source for an automobile, and an inverter device 20 including a power element for controlling power to be supplied to the motor 30. The cooling system 10 includes a refrigerant circuit 40 in which refrigerant for cooling the motor 30 is circulated, a cooling fin 46 of a radiator 45 provided on the refrigerant circuit 40 for cooling the refrigerant, a blowing fan 47 for blowing air toward the cooling fin 46, a heat pipe 23 for cooling the power element 21 having heat resistance to the temperature of the refrigerant cooling the motor 30, and a cooling fin provided on the heat pipe 23 for cooling the heat pipe 23. The cooling fin is arranged at a position to receive the air blown by the blowing fan 47.

Description

  The present invention relates to a system that efficiently cools a motor and an inverter device in a system that controls driving of an electric motor by an inverter device.

Against the background of energy saving and environmental problems, hybrid vehicles and electric vehicles have been put into practical use. Further improvements have been made.
In addition to an engine as an internal combustion engine, a hybrid vehicle uses a DC power source, an inverter, and a motor driven by the inverter as a power source. Then, a power source is obtained by driving the engine, a DC voltage from a DC power source is converted into an AC voltage by an inverter, and a motor power source rotated by the converted AC voltage is also used.

Conventionally, what is indicated by patent documents 1 is known as a cooling mechanism in a system which controls a motor with an inverter device.
As shown in FIG. 5, the system of Patent Document 1 includes an AC motor 1 having a water cooling structure frame 3 provided with a motor side cooling water channel 2. One end of a heat pipe 5 is connected to the inverter device 4 that controls the AC motor 1, and the other end of the heat pipe 5 is inserted into the motor-side cooling water channel 2.

  Patent Document 1 employs a water cooling structure for the AC motor 1 and a heat pipe 5 for cooling the inverter device 4. The cooling of the heat pipe 5 is inserted into the motor side cooling water channel 2 of the AC motor 1 for cooling. To do. For this reason, it is supposed that there is an effect that heat can be radiated in the motor side cooling water channel 2 and the configuration of the entire cooling water circuit can be simplified.

JP 2001-346360 A

However, in the system disclosed in Patent Document 1, an inverter is used unless the temperature of the cooling water in the motor-side cooling water channel 2 is sufficiently lower than the hydraulic fluid (refrigerant) of the heat pipe 5 heated by the inverter device 4. The device 4 cannot be cooled effectively.
The present invention has been made based on such a technical problem, and provides a cooling system capable of efficiently cooling an inverter device together with a motor in a hybrid vehicle and an electric vehicle in which the drive of the motor is controlled by the inverter device. With the goal.

In order to cool the inverter device, it is necessary to determine the temperature of the cooling water as the refrigerant mainly considering the heat loss of the power element (switching element) which is the main element of the inverter device. The upper limit of the operating temperature of silicon (Si) -based power elements, which are mainstream as power elements, is about 150 ° C. In the case of an inverter device having a general configuration using copper, aluminum, or the like as a heat sink, the temperature of the cooling water should be For example, it is necessary to suppress to about 40-50 degreeC.
However, the amount of heat generated by the engine which is an internal combustion engine is large, and the temperature of the cooling water in the engine cooling system rises to about 110 ° C. Cannot be used. Even in an electric vehicle that uses a motor as a driving source, a temperature that is several tens of degrees higher than the cooling water temperature of the inverter is set as a temperature suitable for the cooling system for the motor. Although the temperature of the cooling water for the motor may be lowered to the cooling temperature of the inverter, since the cooling device is enlarged, there are few merits of common cooling water.

  The present invention made there is a cooling system that cools a motor that is a driving source of an automobile and an inverter device that includes a power element that controls electric power supplied to the motor, and the refrigerant that cools the motor is circulated. A refrigerant circuit, a first fin that dissipates heat of the refrigerant, a blower fan that blows air toward the first fin, and a power that is heat resistant to the temperature of the refrigerant that cools the motor A heat pipe that cools the element; and a second fin that is provided in the heat pipe and dissipates heat of the working fluid of the heat pipe. The second fin is disposed at a position that receives air blown by the blower fan. It is characterized by that.

  The cooling system of the present invention uses a heat pipe for cooling the inverter device, and uses a blower fan prepared for cooling the motor to cool the heat heat pipe. Therefore, it is possible to effectively cool the inverter device together with the motor, and it is not necessary to redundantly provide the blower fans.

In the cooling system of the present invention, the heat pipe in the second fin can be arranged on the upstream side of the refrigerant circuit in the first fin on the basis of the direction of air blowing by the blower fan, and conversely on the downstream side. It can also be arranged.
In the present invention, an element having high heat resistance, such as a SiC-based power element, is used in an inverter device, so that it can be cooled even at a temperature higher than the cooling water temperature of a conventional inverter. Cooling is possible even at water temperature.
Therefore, if the heat pipe in the second fin is arranged upstream of the refrigerant circuit in the first fin, the inverter device is preferentially cooled, which is suitable when the power element is to be preferentially cooled over the motor. .
On the other hand, if the heat pipe in the second fin is arranged downstream of the refrigerant circuit in the first fin, cooling of the motor that drives the wheels of the automobile is prioritized, so that heat dissipation from the heat pipe of the inverter is Suitable for reducing the effect on cooling performance.
Note that the position of the heat pipe in the second fin is not limited to the above. For example, in order to suppress the influence of the air blow by the blower fan, the position of the heat pipe can be shifted with respect to the refrigerant circuit and arranged laterally. By doing so, it becomes difficult to receive the influence of heat mutually between a refrigerant circuit and a heat pipe.

In the cooling system of the present invention, the first fin of the refrigerant circuit and the second fin of the heat pipe can be shared.
Since the temperature of the refrigerant flowing through the refrigerant circuit is lower than the temperature of the heat pipe, by using the first fin and the second fin in common, the refrigerant flowing through the refrigerant circuit is used for cooling the inverter device via the heat pipe. Therefore, the inverter device can be efficiently cooled. Further, by sharing the first fin and the second fin, it is possible to contribute to a reduction in the number of parts in the cooling system and further to downsizing of the cooling system.

The cooling system of the present invention can arrange an engine as a driving source of an automobile in addition to a motor on a refrigerant circuit. That is, the cooling system of the present invention can be applied to a hybrid vehicle in addition to an electric vehicle.
In this case, the refrigerant preferably flows through the refrigerant circuit so as to pass through the motor, the engine, and the first fin in this order.
The temperature of the refrigerant heated by the engine is considerably high. Therefore, if a motor is placed on the downstream side of the engine, the motor is not sufficiently cooled, and it may be difficult to ensure stable operation. On the other hand, if a refrigerant circuit is provided so that the refrigerant flows through the motor and the engine in this order, such a problem does not occur.

  According to this invention, while using a heat pipe for cooling of an inverter apparatus, in order to cool this heat heat pipe, the ventilation fan prepared for cooling of a motor is utilized. Therefore, the inverter device can be effectively cooled together with the motor.

It is a figure which shows the structure of the cooling system in 1st Embodiment. It is a figure which shows the structure of the cooling system in 2nd Embodiment. It is a figure which shows the structure of the cooling system in 3rd Embodiment. It is a figure which shows the structure of the cooling system in 4th Embodiment. It is a figure which shows the structure of the cooling system described in patent document 1. FIG.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
[First Embodiment]
A cooling system 10 shown in FIG. 1 is incorporated in, for example, an electric vehicle, and includes an inverter device 20, a motor 30, and a refrigerant circuit 40. The cooling system 10 ensures stable operation of the inverter device 20 and the motor 30 by cooling the heat generated in the inverter device 20 and the heat generated in the motor 30.

  Inverter device 20 receives a DC voltage from battery 60, converts the received DC voltage into an AC voltage, and outputs the AC voltage to motor 30. When the motor 30 functions as a generator, the inverter device 20 can also convert the AC voltage generated by the motor (generator) 30 into a DC voltage and charge the battery 60. As the battery 60, for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery can be used.

  The inverter device 20 has a known configuration including an inverter, a capacitor, and a power supply line. The inverter is composed of a transistor and a diode. In the present embodiment, a high heat resistance is used as the power element 21. As the high heat resistance power element, a SiC (silicon carbide) power element is preferably used. SiC power elements have a larger forbidden bandwidth and thermal conductivity than conventional Si power elements, and also have characteristics such as high heat resistance, low loss, and high withstand voltage. It has the characteristics of This embodiment uses high heat resistance among these various characteristics. That is, since the SiC power element can operate up to about 400 ° C., the cooling water of the motor 30 can be used for cooling the inverter device 20.

  The inverter device 20 includes a heat radiating plate 22 provided so as to be in contact with the power element 21 that has generated heat by operation. The heat radiating plate 22 is made of a plate-like metal material having excellent thermal conductivity, such as copper, copper alloy, aluminum, and aluminum alloy.

The inverter device 20 is provided with a heat pipe 23.
The heat pipe 23 is vacuum-sealed with a small amount of hydraulic fluid (refrigerant) in an airtight container (pipe), and has a capillary structure called a wick on the inner wall. The heat pipe 23 is a heat transport element that uses latent heat of evaporation and condensation, and has an advantage that large heat can be transported with a small temperature difference. Heat transfer to the heat pipe 23 is smoothly performed by joining one end side of the heat pipe 23 to the heat radiating plate 22 of the inverter device 20. The fins 46 connected on the other end side of the heat pipe 23 are shared with the radiator 45 provided in the refrigerant circuit 40.
Cooling (heat exchange) in the heat pipe 23 is performed as follows. That is, when a part of the heat pipe 23 is heated, the hydraulic fluid evaporates (absorption of latent heat of vaporization) in the heating part, the steam moves to the low temperature part, and the transferred steam condenses in the low temperature part (the latent heat of evaporation). A series of phase changes in which the condensed liquid recirculates to the heating part by capillary action, and heat moves quickly.

  The motor 30 is composed of, for example, a three-phase AC synchronous motor generator, and has a main component including a rotor incorporating a plurality of permanent magnets and a stator wound with a three-phase coil that generates a magnetic field. In the motor 30, the rotor rotates by the interaction between the magnetic field generated by the permanent magnet and the magnetic field generated by the three-phase coil. The motor 30 can also have a function as a generator that generates electromotive force at both ends of the three-phase coil by the interaction between the magnetic field generated by the permanent magnet and the rotation of the rotor.

  The refrigerant circuit 40 is connected to a motor 30, a radiator 45, and a circulation pump 48. The refrigerant circuit 40 is generated in the inverter device 20 via the heat pipe 23 in addition to cooling the heat generated in the motor 30. Cool down heat.

  The refrigerant circuit 40 includes a flow path 41 between the outlet side of the motor 30 and the inlet side of the radiator 45, a flow path 42 between the outlet side of the radiator 45 and the inlet side of the circulation pump 48, and the circulation pump 48. And a flow path 43 between the outlet side and the inlet side of the motor 30. That is, the motor 30, the radiator 45, and the circulation pump 48 are connected in series on the refrigerant circuit 40 by the flow paths 41 to 43.

The radiator 45 cools the cooling water circulating in the refrigerant circuit 40 and cools the inverter device 20, particularly the power element 21 via the heat pipe 23. The radiator 45 includes fins 46 and a blower fan 47. The refrigerant circuit 40 penetrates the fin 46, and the cooling efficiency of the cooling medium flowing through the region is improved. Furthermore, the cooling efficiency of the cooling medium is further improved by blowing air from the blower fan 47 toward the fins 46.
The circulation pump 48 is a pump for circulating cooling water such as an antifreeze liquid, and circulates the cooling water in a flow direction a indicated by a solid arrow shown in the figure. Note that the flow of the cooling medium may be reversed.

  The fins 46 of the radiator 45 are provided so as to penetrate the front end side of the heat pipe 23, and the refrigerant circuit 40 and the heat pipe 23 share the fins 46. When the fins 46 receive the air blown from the blower fan 47, both the cooling water flowing through the refrigerant circuit 40 and the working fluid of the heat pipe 23 are cooled. In the present embodiment, the heat pipe 23 is disposed on the upstream side and the refrigerant circuit 40 is disposed on the downstream side with reference to the direction b of the air blow indicated by the broken arrow.

Since the motor 30 generates a relatively large amount of heat, the temperature of the cooling water for cooling the motor 30 reaches about 80 ° C. On the other hand, as described above, the conventional Si-based power element needs to suppress the temperature of the cooling water to about 65 ° C. based on the upper limit of the operating temperature of about 150 ° C. Therefore, the cooling water of the motor 30 cannot be used for cooling the inverter device.
However, in this embodiment, since the SiC power element 21 whose upper limit of the operating temperature is about 400 ° C. is used for the inverter device 20, the temperature of the cooling water for cooling the inverter device 20 is set to the cooling water for the motor 30. It can be higher than the temperature (80 ° C.). Therefore, according to the cooling system 10 of the present embodiment, the cooling water of the motor 30 can be used for cooling the inverter device 20.

Cooling in the cooling system 10 is performed as follows.
Heated (for example, 80 ° C.) cooling water flowing through the flow path 41 through the motor 30 by the operation of the circulation pump 48 passes through the radiator 45 and reaches the flow path 42. In the process of passing through the radiator 45, the cooling water is cooled (for example, 25 ° C.) by receiving the action of the fins 46 and the blower fan 47, and then the motor is passed through the flow paths 42 and 43 by the operation of the circulation pump 48. To 30. Furthermore, after the motor 30 is cooled by passing through the motor 30, it reaches the flow path 41 as heated cooling water. Thereafter, the cooling water circulates through the refrigerant circuit 40 according to the same process.

Further, the heat pipe 23 receives the action of the fins 46 and the blower fan 47 so that the working fluid in the vapor state is cooled and condensed (release of latent heat of evaporation), and the condensed and cooled liquid is caused by capillary action. It recirculates to the inverter device 20 (power element 21) which is a heating part, and this time, the inverter device 20 (power element 21) is cooled.
Here, the fin 46 constitutes the radiator 45 responsible for cooling the motor 30, and the cooling water flowing into the radiator 45 from the motor 30 is, for example, about 80 ° C., and the upper limit operating temperature of the SiC power element 21 (for example, Considerably lower than 400 ° C). Therefore, the heated cooling water from the motor 30 flowing into the radiator 45 is used for cooling the heat pipe 23.

According to the cooling system 10 described above, the blower fan 47 attached to the radiator 45 is used for cooling the heat pipe 23 responsible for cooling the inverter device 20 in addition to the refrigerant circuit 40 responsible for cooling the motor 30. Therefore, the inverter device 20 can be efficiently cooled together with the motor 30 without providing a separate blower fan.
Further, in the cooling system 10, since the temperature of the cooling water flowing through the refrigerant circuit 40 is lower than the temperature of the hydraulic fluid in the heat pipe 23, the refrigerant flowing through the refrigerant circuit 40 causes the heat pipe 23 to pass through the fin 46. The inverter device 20 is used for cooling. Therefore, the cooling system 10 can cool the inverter device 20 efficiently. Further, by using the fins 46 in common, the number of parts in the cooling system 10 can be reduced, and further, the cooling system 10 can be reduced in size.
Furthermore, since the cooling system 10 cools the inverter device 20 with the heat pipe 23, a circulation circuit including a pump is not required, the cooling system of the inverter device 20 can be simplified, and there is no fear of water leakage.

  Although the present invention has been described based on the cooling system 10 shown in FIG. 1, the present invention allows the modifications described below.

[Second Embodiment]
The cooling system 10 in FIG. 1 is provided with the heat pipe 23 on the upstream side in the direction b of air blowing and the refrigerant circuit 40 on the downstream side with respect to the blower fan 47. As shown in FIG. It is also possible to reverse the heat pipe 23 and the refrigerant circuit 40 to provide the cooling system 110 in which the refrigerant circuit 40 is provided on the upstream side in the air flow direction b and the heat pipe 23 is provided on the downstream side. In FIG. 2, the same elements as those in FIG.

  The cooling system 10 of FIG. 1 is suitable for the case where it is desired to cool the power element 21 of the inverter device 20 in preference to the motor 30 because the heat pipe 23 having a high temperature is preferentially cooled. On the other hand, the cooling system 110 in FIG. 2 gives priority to the cooling of the motor 30 that drives the wheels, so that the heat radiation from the heat pipe 23 of the inverter device 20 has less influence on the cooling performance of the motor 30, and the automobile Can contribute to stable driving.

[Third Embodiment]
Next, the cooling system 10 in FIG. 1 shares the fins 46 of the radiator 45 with the heat pipe 23, but the present invention is not limited to this, and is independent of the fins 46 as shown in FIG. A cooling system 210 in which the fins 25 are provided on the heat pipe 23 may be used. However, also in this case, the portion of the heat pipe 23 provided with the fins 25 is placed in a region that receives the air blown from the blower fan 47, as shown in FIG. In this case, the heat pipe 23 can be handled as a cooling module to which the fins 25 are attached.

According to the cooling system 210 of FIG. 3, even if the motor 30 and the refrigerant circuit 40 are produced without intending to share the fins 46 with the heat pipe 23, by receiving air from the blower fan 47, The inverter device 20 can be efficiently cooled via the heat pipe 23.
Also in the cooling system 210 in FIG. 3, the refrigerant circuit 40 can be provided on the upstream side in the direction b of blowing, and the heat pipe 23 can be provided on the downstream side.

[Fourth Embodiment]
Next, although the cooling system 10 of FIG. 1 assumes an electric vehicle including only the motor 30 as a driving source of wheels, a hybrid including an engine 50 as an internal combustion engine as in the cooling system 310 illustrated in FIG. 4. The present invention can be applied to automobiles.
The cooling system 310 of FIG. 4 has the cooling water flowing in the opposite direction to the cooling system 10 of FIG. This is because the calorific value of the engine 50 is larger than that of the inverter device 20 and the motor 30. Therefore, if the inverter device 20 and the motor 30 are placed on the downstream side of the engine 50, it is difficult to secure these stable operations. Because. Therefore, the cooling system 310 has the inverter device 20 and the motor 30 on the upstream side of the engine 50.

The preferred embodiments of the present invention have been described above. However, unless departing from the requirements of the present invention described in the claims, the configurations listed in the above embodiments are selected or appropriately changed to other configurations. Is possible.
For example, although the example using the SiC-based power element 21 is shown, for example, a highly heat-resistant power element such as a GaN-based power element made of gallium nitride (GaN) can be applied.

DESCRIPTION OF SYMBOLS 1 AC motor 2 Motor side cooling water channel 3 Frame 4 Inverter device 5 Heat pipe 10, 110, 210, 310 Cooling system 20 Inverter device 21 Power element 22 Heat sink 23 Heat pipe 25 Fin 30 Motor 40 Refrigerant circuit 41, 42, 43 Flow Passage 45 Radiator 46 Fin 47 Blower fan 48 Circulation pump 50 Engine 60 Battery

Claims (5)

A cooling system that cools a motor that is a driving source of an automobile and an inverter device that includes a power element that controls electric power supplied to the motor,
The cooling system includes:
A refrigerant circuit in which a refrigerant for cooling the motor is circulated;
A first fin provided on the refrigerant circuit for radiating heat of the refrigerant;
A blower fan for blowing air toward the first fin;
A heat pipe for cooling a power element having heat resistance against the temperature of the refrigerant for cooling the motor;
A second fin provided on the heat pipe and dissipating heat of the working fluid of the heat pipe;
The second fin is disposed at a position to receive the air blow by the blower fan.
A cooling system characterized by that. Based on the direction of the blowing by the blowing fan,
The heat pipe in the second fin is disposed upstream of the refrigerant circuit in the first fin.
The cooling system according to claim 1. Based on the direction of the blowing by the blowing fan,
The heat pipe in the second fin is disposed downstream of the refrigerant circuit in the first fin.
The cooling system according to claim 1. The first fin and the second fin are shared with each other;
The cooling system as described in any one of Claims 1-3. In addition to the motor, an engine as a driving source of the automobile is disposed on the refrigerant circuit,
The refrigerant flows through the refrigerant circuit so as to pass through the motor, the engine, and the first fin in this order.
The cooling system as described in any one of Claims 1-4.

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