JP5206483B2 - Power converter cooling system - Google Patents

Description

  The present invention relates to a cooling system for a power conversion device, and more particularly to a power conversion device configured to liquid-cool a power semiconductor in a closed power conversion unit constituting the power conversion device and to cool air in the closed power conversion unit. Relates to the cooling system.

  The power conversion device includes a power semiconductor in the power conversion unit, and converts the alternating current into direct current or alternating current, or converts direct current into direct current or alternating current by switching the power semiconductor. Since power semiconductors generate a large amount of heat during the switching operation, it is necessary to dissipate such heat and cool the power semiconductor.

  Especially in a closed type power conversion unit having a sealed housing structure, the heat generated by the power semiconductor is guided to the outside of the device and dissipated to cool the power semiconductor, and the heat radiated to the air in the power conversion unit. Is known to cool the air in the power conversion unit by absorbing heat with an endothermic fin (see, for example, Patent Document 1).

  Such a closed type power conversion unit includes a cooling body that allows a liquid refrigerant to flow between the radiator and the radiator installed outside the apparatus, and a power semiconductor is mounted on the cooling body. The heat generated by the power semiconductor is led out of the apparatus by the refrigerant flowing through the cooling body and is dissipated by the radiator installed outside, thereby cooling the power semiconductor.

  Moreover, since the calorific value of the power semiconductor changes according to the output of the power converter, the power semiconductor is excessively cooled when the output power of the power converter is low. On the other hand, a cooling system that does not excessively cool the power semiconductor is known (see, for example, Patent Document 2). According to this cooling system, the number of revolutions of the pump circulating the refrigerant is controlled according to the amount of heat generated by the power semiconductor, so that the power semiconductor is properly cooled.

  On the other hand, the temperature of the air inside the closed type power conversion unit is raised by the heat generated by the electronic components that drive and control the power semiconductor. An electronic component and an electronic circuit incorporating the electronic component may malfunction electrically when the ambient temperature exceeds the manufacturer's recommended temperature. In addition, it is known that solder that joins a printed wiring board and an electronic component is subjected to stress due to a change in ambient temperature due to a difference in thermal expansion coefficient between the printed wiring board and the electronic component, and leads to a solder crack (for example, And Patent Document 3). The stress applied to the solder part is affected by the magnitude of the temperature change and the number of repetitions of the temperature change.

  In the closed type power conversion unit, when the temperature of the air inside becomes higher than the temperature of the outside air, the internal heat is naturally radiated and cooled by the heat passing phenomenon that is transmitted through the housing to the outside. However, the amount of heat released by the heat passage is generally small, and it is difficult to greatly improve the heat transfer rate to the housing even if the air is forced to convection by a fan. On the other hand, in the related art of Patent Document 1, the fan in which air is forcibly convected inside the power converter is configured to apply the forced convection air to the cooling fins that are thermally connected to the cooling body. Yes. As a result, the heat dissipated in the air by the heat generating electronic component is once more efficiently collected by the cooling fins, and the heat is transferred to the cooling body of the power semiconductor and further from the cooling body to the outside of the power converter. It is transferred to the heat and is radiated.

JP 2008-60515 A JP 2008-130791 A JP 2007-73991 A

  However, since the cooling system of the power conversion device has a very small amount of heat generated by other electronic components compared to the amount of heat generated by the power semiconductor in the closed power conversion unit, the heat dissipation substantially corresponding to the amount of heat generated by the power semiconductor. Therefore, if the power converter continues to operate at its maximum output for a long time, sufficient heat dissipation of the internal air temperature of the closed power conversion unit will not be performed, and the internal air temperature will be There was a problem that it might exceed the recommended ambient temperature of parts.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a cooling system for a power conversion device in which the air temperature inside the closed power conversion unit does not exceed a predetermined value. And

  In order to solve the above problems, the present invention includes a closed power conversion unit including a power converter having a power semiconductor and a power converter control circuit that controls the output of the power converter to a desired value. In a cooling system for a power converter, a cooling body on which the power semiconductor is mounted, a radiator installed outside, a pump with an electric motor that circulates a refrigerant between the cooling body and the radiator, and a valve A three-way valve that distributes the refrigerant circulating at an angle to the bypass pipe arranged in parallel to the radiator and the radiator, and the heat of the air in the closed type power conversion unit that is thermally connected to the cooling body. A heat absorber that absorbs heat, a fan that circulates air in the closed type power conversion unit, a temperature sensor that detects an air temperature in the closed type power conversion unit, and an air temperature detected by the temperature sensor. An angle command circuit that calculates an angle command value of the three-way valve from a temperature, and a three-way valve control circuit that controls the angle of the three-way valve using the output of the angle command circuit as a command value, and the angle of the three-way valve Is controlled so as to keep the air temperature in the closed power conversion unit at a predetermined value, a cooling system for a power conversion device is provided.

  According to such a cooling system for a power conversion device, when the amount of heat radiated into the air in the closed type power conversion unit exceeds the amount of heat radiated naturally from the housing to the outside due to the passage of heat, the temperature of the internal air increases. By controlling the angle of the three-way valve, the amount of refrigerant passing through the radiator is increased to control the temperature of the refrigerant. Thereby, the temperature of the air in the closed type power conversion unit is lowered by decreasing the temperature of the cooling body and increasing the heat absorption amount of the heat absorber thermally connected thereto, and the temperature of the air exceeds a predetermined value. I'm trying not to get it.

  The cooling system of the power conversion device configured as described above controls the angle of the three-way valve according to the air temperature in the closed power conversion unit, increases the flow rate of the refrigerant flowing through the radiator, and decreases the temperature of the cooling body, Since the heat absorption amount of the heat absorber is increased, the air temperature in the closed type power conversion unit can be kept below the permissible temperature of the electronic circuit and almost constant, preventing malfunction of the electronic circuit and printing. There is an advantage that it is possible to prevent deterioration of the solder used for mounting the wiring board and the electronic component, and to improve the reliability and extend the life.

It is a block diagram which shows the cooling system of the power converter device which concerns on 1st Embodiment. It is a figure which shows the structural example of an angle command circuit. It is a figure which shows the heat-transfer circuit in a closed type power conversion unit. It is a block diagram which shows the cooling system of the power converter device which concerns on 2nd Embodiment. It is a figure which shows the structural example of an angle command circuit. It is a block diagram which shows the cooling system of the power converter device which concerns on 3rd Embodiment. It is a figure which shows the 1st structural example of a three-way valve control circuit. It is a figure which shows the 2nd structural example of a three-way valve control circuit. It is a block diagram which shows the cooling system of the power converter device which concerns on 4th Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a cooling system for a power conversion device according to the first embodiment, FIG. 2 is a diagram showing a configuration example of an angle command circuit, and FIG. 3 shows a heat transfer circuit in a closed power conversion unit. FIG.

  The power conversion device includes a closed power conversion unit 10, and the closed power conversion unit 10 includes a power semiconductor 11 and a power converter control circuit 12. The power semiconductor 11 constitutes a power converter that performs power conversion by switching the power semiconductor 11 and generates a large amount of heat due to power loss when a current is passed. The power converter control circuit 12 includes a microcomputer and is configured by electronic components that control the output of the power converter including such a power semiconductor 11 to a desired value.

  The cooling system includes a closed body power conversion unit 10, a cooling body 20 on which the power semiconductor 11 is mounted, a heat absorption fin (heat absorber) 21 thermally connected to the cooling body 20 by, for example, a heat pipe, A fan 22 for blowing the circulating air inside the closed power conversion unit 10 to the heat absorption fin 21 is provided. A radiator 23 is provided outside the closed power conversion unit 10, and a pipe 24 and a pump 25 with an electric motor are provided so that refrigerant circulates between the cooling body 20. In this refrigerant circulation circuit, a bypass pipe 26 is provided side by side so as to bypass the radiator 23, and a three-way valve 27 is disposed at a branch portion on the upstream side of the radiator 23. The three-way valve 27 controls the flow rate of the refrigerant flowing through the radiator 23 by controlling the diversion ratio of the refrigerant flowing through the radiator 23 and the bypass pipe 26 according to the angle of the valve. Further, the cooling system includes a temperature sensor 28 that detects an air temperature inside the closed type power conversion unit 10, and an output of the temperature sensor 28 is connected to an input of an angle command circuit 29. The output of the angle command circuit 29 is connected to the input of the three-way valve control circuit 30, and the output is connected to the three-way valve 27.

  As shown in FIG. 2, the angle command circuit 29 includes an angle adjustment circuit 31 and a temperature setting unit 32, and the angle adjustment circuit 31 receives the output of the temperature sensor 28 and the temperature setting value of the temperature setting unit 32. Then, an angle command is output to the three-way valve control circuit 30 so that the temperature detected by the temperature sensor 28 becomes the air temperature set by the temperature setting unit 32. The three-way valve control circuit 30 has, for example, a proportional integration controller, and generates a signal of a proportional integration operation so that the deviation between the angle command value given from the angle adjustment circuit 31 and the actual detected angle value becomes zero. The three-way valve 27 is driven and controlled.

  That is, the cooling system of the power conversion device detects the air temperature inside the closed power conversion unit 10 and controls the angle of the three-way valve 27 so that the detected air temperature is kept at a predetermined value.

  Next, the heat transfer circuit inside the closed type power conversion unit 10 will be described. Here, as an example of the power semiconductor 11, for example, a power module containing an IGBT (Insulated Gate Bipolar Transistor) which is a power switching element of an inverter circuit and a freewheeling diode (FWD) which consumes a counter electromotive force generated at the time of switching. The case will be described.

In the power module 11a, as shown in FIG. 3, the junction of the IGBT is a heat generation source, the temperature is Tj (IGBT), and the heat generation amount is P _IGBT . The temperature of the free wheeling diode is Tj (FWD), and the heat generation amount is P _FWD . The thermal resistance between the junction of the IGBT and the freewheeling diode and the case is represented by Rth (j−c), and the case temperature is represented by Tc. The amount of heat P (= P _IGBT + P _FWD ) generated in the power module 11a moves from the case of the power module 11a to the cooling body 20, and the thermal resistance at that time is Rth (cf).

  The endothermic fin 21 thermally connected to the cooling body 20 absorbs the amount of heat Q from the air having the air temperature Ta, the thermal resistance at that time is Rth (a−fa), and the temperature is Tfa. Further, the thermal resistance between the endothermic fins 21 and the cooling body 20 is Rth (fa−f).

  The temperature of the cooling body 20 becomes Tf due to the movement of the amount of heat P generated by the power module 11a and the amount of heat Q absorbed by the endothermic fins 21. The amount of heat (P + Q) is transferred to the circulating refrigerant through Rth (f−w) which is the thermal resistance between the cooling body 20 and the refrigerant, and the temperature of the refrigerant at that time is Tw.

  As described above, the cooling of the power module 11a is performed by moving the heat generated by the power module 11a to the cooling body 20 and moving it from the cooling body 20 to the circulating refrigerant. The heat transferred to the refrigerant is circulated from the cooling body 20 by the pump 25 with the electric motor, transferred to the radiator 23 installed outside, and dissipated from there.

  The temperature Tf of the cooling body 20 is expressed as a temperature obtained by multiplying the refrigerant temperature Tw by the temperature obtained by multiplying the heat generation amount P of the power module 11a by the thermal resistance Rth (fw) between the cooling body 20 and the refrigerant. Is done.

  For cooling the air inside the closed type power conversion unit 10, the air in the closed type power conversion unit 10 is circulated by the fan 22, and the heat absorbing fins 21 are installed in a path through which the air circulates. This is done by absorbing the amount of heat. The amount of heat Q absorbed by the heat-absorbing fins 21 moves to the thermally connected cooling body 20, further moves to the refrigerant, and is radiated by the external radiator 23.

  The air temperature Ta inside the closed type power conversion unit 10 is determined from the amount of heat Q radiated from the circuit components / circuit conductors into the heat absorption fin 21 and the surface of the casing of the closed type power conversion unit 10. It is thermally saturated when it matches the total amount of heat that is naturally radiated to the outside.

  The heat dissipated in the closed power conversion unit 10 includes heat generated by the power consumed by the operation of the power converter control circuit 12 composed of electronic components, and the power module 11a generated by the current conduction of the power converter. There are heat generated due to loss in peripheral parts (such as a snubber circuit) and conductors, and heat radiated from the surface due to the temperature rise of the power module 11a itself.

  Most of the heat due to the loss generated inside the power module 11a is transferred to the outside of the closed power conversion unit 10 by the cooling body 20 to which the power module 11a is attached, and dissipated. The influence of the module 11a on the temperature rise of the internal air of the closed power conversion unit 10 is small.

When the amount of heat released from the surface of the closed type power conversion unit 10 to the outside is small, when the air temperature Ta inside the closed type power conversion unit 10 is saturated, all the heat radiated inside is absorbed by the heat absorbing fins 21. It has been transferred to the cooling body 20. Therefore, the temperature calculated by multiplying the internal heat radiation amount Q by the thermal resistance Rth between the air and the cooling body 20 becomes a temperature difference between the internal air and the cooling body 20, and the temperature Tf of the cooling body 20 is The temperature obtained by adding the temperature difference between the air including the heat absorbing fins 21 and the cooling body 20 is substantially the air temperature Ta. That is, the internal air temperature Ta of the closed power conversion unit 10 is Tf as the temperature of the cooling body 20, and Rth = Rth (a−fa) + Rth (fa−f) as the thermal resistance between the air and the cooling body 20. If the heat dissipation amount of the heat generating component is Q,
Ta = Tf + Rth × Q (1)
Can be expressed as In the calculation of the internal air temperature Ta, the thermal resistance Rth between the air and the cooling body 20 and the heat radiation amount Q of the heat generating component are determined by the operating state of the apparatus and are constant. Therefore, in order to adjust the internal air temperature Ta, the temperature Tf of the cooling body 20 may be adjusted.

The temperature Tf of the cooling body 20 is obtained by adding a temperature difference ΔT between the refrigerant and the cooling body 20 to the refrigerant temperature Tw.
Tf = Tw + ΔT (2)
The temperature difference ΔT between the refrigerant and the cooling body 20 is expressed by the heat resistance (R + (f−w)) between the cooling body 20 and the refrigerant. Is the temperature obtained by multiplying by. This thermal resistance Rth (fw) is determined by the amount of refrigerant flowing through the cooling body 20 per unit time and the heat transfer area S. If the heat transfer coefficient between the refrigerant and the cooling body 20 is h, the temperature difference ΔT is
ΔT = (P + Q) / (h · S) (3)
It is represented by If the output of the closed type power conversion unit 10 is constant, the amount of heat (P + Q) transferred from the cooling body 20 to the refrigerant is constant. Therefore, if the amount of refrigerant circulated by the pump 25 with the electric motor is constant, the heat transfer area S of the refrigerant is determined by the apparatus and is constant, and therefore, the internal air temperature Ta of the closed power conversion unit 10, that is, the cooling body 20. In order to adjust the temperature Tf of the refrigerant, the temperature Tw of the refrigerant flowing through the cooling body 20 may be adjusted.

  Here, as a specific example of adjusting the temperature Tw of the circulating refrigerant, the three-way valve control circuit 30 uses a proportional integral regulator so that the internal air temperature Ta of the closed power conversion unit 10 becomes a predetermined value. The angle of the valve 27 is controlled. As a result, the refrigerant circulated in a constant amount of refrigerant by the motor-equipped pump 25 changes the ratio of the amount of refrigerant diverted to the radiator 23 and the bypass pipe 26, and the refrigerant cooled downstream of the radiator 23. And the uncooled refrigerant passing through the bypass pipe 26 are mixed, and the temperature of the refrigerant flowing through the cooling body 20 is adjusted.

  That is, when the air temperature becomes higher than the set temperature, the three-way valve control circuit 30 controls the angle of the three-way valve 27 so as to close to the bypass pipe 26 side, and the refrigerant flowing to the radiator 23 side is controlled. The flow rate is increased and the temperature of the refrigerant flowing through the cooling body 20 is decreased. When the air temperature becomes lower than the set temperature, the three-way valve control circuit 30 controls the angle of the three-way valve 27 to close to the radiator 23 side to reduce the flow rate of the refrigerant flowing to the radiator 23 side. The temperature of the refrigerant flowing through the cooling body 20 is increased.

  In the embodiment of FIG. 1, the angle command circuit 29 is built in the closed type power conversion unit 10, but may be installed outside the closed type power conversion unit 10. Further, the three-way valve control circuit 30 may be installed not inside the closed power conversion unit 10 but inside.

  The air temperature inside the closed power conversion unit 10 becomes substantially uniform due to the circulation of air by the fan 22. The temperature sensor 28 for detecting the air temperature is installed so that the ambient temperature or the upper temperature of the printed circuit board on which the electronic component is mounted can be measured.

  As a set value of the air temperature inside the closed type power conversion unit 10, for example, a temperature with a margin is set for the ambient temperature allowed for the electronic components and the like mounted on the control circuit. Specifically, the operation-guaranteed ambient temperature of the electronic circuit is generally about 40 ° C. to 60 ° C., and therefore should be set to a temperature lower than that. Thereby, the air temperature inside the closed type power conversion unit 10 can be controlled so as not to exceed a predetermined set value.

  FIG. 4 is a block diagram showing a cooling system for a power converter according to the second embodiment, and FIG. 5 is a diagram showing a configuration example of an angle command circuit. 4 and 5, the same or equivalent components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the cooling system for the power conversion device according to this embodiment, the temperature sensor 28 does not directly detect the air temperature inside the closed power conversion unit 10 but indirectly detects the air temperature, The angle of the three-way valve 27 is controlled so that the air temperature is maintained at a set predetermined value. Therefore, the temperature sensor 28 detects the temperature of the cooling body 20 on which the power semiconductor 11 is mounted, and determines the temperature difference between the temperature of the cooling body 20 and the air temperature of the closed power conversion unit 10 as the power converter control circuit 12. Is calculated and the calculated temperature difference is added to the temperature of the cooling body 20 to estimate the air temperature inside the closed type power conversion unit 10.

  As shown in FIG. 5, the angle command circuit 29 includes an angle adjustment circuit 31, a temperature setting unit 32, and an air temperature estimation circuit 33, and the air temperature estimation circuit 33 outputs the power and power of the temperature sensor 28. The air temperature is estimated by receiving the output of the temperature difference calculation circuit 12a included in the converter control circuit 12. The angle adjustment circuit 31 inputs the air temperature estimated by the air temperature estimation circuit 33 and the temperature setting value of the temperature setting unit 32 so that the estimated air temperature becomes the air temperature set by the temperature setting unit 32. An angle command is output to the three-way valve control circuit 30. The three-way valve control circuit 30 generates a signal of a proportional integration operation so that the deviation between the angle command value given from the angle adjustment circuit 31 and the actual detected angle value becomes zero, and drives and controls the three-way valve 27.

  The fact that the air temperature estimation circuit 33 can estimate the air temperature from the temperature of the cooling body 20 and the temperature difference can be explained by the heat transfer circuit shown in FIG. That is, as shown in the above equation (1), the internal air temperature Ta of the closed type power conversion unit 10 is changed from the heat radiation amount Q of the heat generating component and the heat absorption fin 21 to the temperature Tf of the cooling body 20 through the heat absorption fins 21. 20 is represented by a temperature obtained by adding a temperature difference obtained by multiplying by 20 the thermal resistance Rth of the heat transfer path. The temperature Tf of the cooling body 20 is detected by the temperature sensor 28, the thermal resistance Rth is a constant, and the heat dissipation amount Q of the heat generating component is obtained by calculation by the temperature difference calculation circuit 12 a of the power converter control circuit 12.

  The heat dissipation amount Q of the heat generating component can be calculated in the temperature difference calculation circuit 12a of the power converter control circuit 12 as follows. The loss generated at the input unit of the power converter is calculated based on the input voltage and the input current. Moreover, the loss which generate | occur | produces in the output part of a power converter is calculated by calculation based on an output voltage and an output current. The amount of heat radiated from the surface of the power semiconductor 11 is calculated based on the relationship between the surface area of the power semiconductor 11 and the estimated air temperature, assuming that the junction temperature of the power semiconductor 11 is the surface temperature. The amount of heat generated by the power converter control circuit 12 is obtained based on calculating or measuring the power consumed by the circuit. Accordingly, the temperature difference calculation circuit 12a has the operation value of the closed power conversion unit 10 by having the total value of the heat dissipated in the closed power conversion unit 10 as a table or a function expression as a function of output. It is possible to know the amount of heat dissipated in the closed power conversion unit 10 with respect to an arbitrary output according to the output. The amount of heat is multiplied by the thermal resistance Rth of the path for transferring heat from the air to the cooling body 20 through the heat sink 21, and the temperature difference between the air and the cooling body 20 is multiplied by the air temperature estimation circuit 33 of the angle command circuit 29. Given. The air temperature estimation circuit 33 adds the temperature detected by the temperature sensor 28 and the temperature difference by the temperature difference calculation circuit 12a, and outputs the result to the angle adjustment circuit 31 as an estimated air temperature.

Next, an embodiment in which a cooling system for a power converter is applied to a power converter for a multiphase motor will be described.
FIG. 6 is a block diagram showing a cooling system for a power converter according to the third embodiment, FIG. 7 is a diagram showing a first configuration example of a three-way valve control circuit, and FIG. 8 is a second diagram of the three-way valve control circuit. It is a figure which shows the example of a structure. 6 to 8, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  This power conversion device 1 is for driving a multi-phase motor 40 having a plurality of independent single-phase windings. In order to individually control each phase, a plurality of closed-type power conversion units 10a, 10b, ..., 10n. Each of the closed type power conversion units 10a, 10b,..., 10n has the same configuration as the closed type power conversion unit 10 shown in FIG.

  In this cooling system for the power conversion device 1, the piping on the refrigerant outlet side and the piping on the refrigerant introduction side that come out of the cooling bodies 20 of all the closed power conversion units 10a, 10b,. The refrigerant inlet of the three-way valve 27 and the refrigerant outlet of the pump 25 with electric motor are connected. Thereby, the refrigerant pumped by the pump 25 with the electric motor is branched and sent to the cooling bodies 20 of the respective closed type power conversion units 10a, 10b,..., 10n, and the respective closed type power conversion units 10a, 10a, The refrigerant that has exited the cooling bodies 20 of 10b,..., 10n merges and is sent to the three-way valve 27.

  As shown in FIG. 7, the three-way valve control circuit 30 that controls the three-way valve 27 has an average angle command calculation circuit 34 and a three-way valve drive circuit 35. The average angle command calculation circuit 34 receives the angle commands a, b,..., N output from the angle command circuits 29 of the respective closed power conversion units 10a, 10b,. An average value of the commands a, b,..., N is calculated and output as a command value. The three-way valve drive circuit 35 drives and controls the three-way valve 27 based on the command value output from the average angle command calculation circuit 34. Thereby, the cooling system of this power converter device 1 controls the angle of the three-way valve 27 so that the air temperature inside each closed type power conversion unit 10a, 10b,..., 10n is maintained at a predetermined value. become.

  The three-way valve control circuit 30 shown in FIG. 8 has a minimum angle command selection circuit 36 and a three-way valve drive circuit 35. The minimum angle command selection circuit 36 inputs the angle commands a, b,..., N output from the angle command circuits 29 of the respective closed power conversion units 10a, 10b,. The minimum value of commands a, b,..., N is selected as the command value. The three-way valve drive circuit 35 drives and controls the three-way valve 27 based on the command value output from the minimum angle command selection circuit 36. Thereby, the cooling system of this power converter device 1 controls the angle of the three-way valve 27 so that the air temperature inside each of the closed type power conversion units 10a, 10b,. become.

  FIG. 9 is a block diagram showing a cooling system of the power conversion device according to the fourth embodiment. 9, the same or equivalent components as those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the cooling system of the power conversion device 1, the air temperature inside the closed power conversion unit 10 is estimated, and the angle of the three-way valve 27 is controlled so that the estimated air temperature is maintained at a set predetermined value. Yes. Therefore, in the angle command circuit 29 of this cooling system, the temperature of the cooling body 20 detected by the temperature sensor 28 by the air temperature estimation circuit 33 and the air calculated by the temperature difference calculation circuit 12a of the power converter control circuit 12 From the temperature difference with the cooling body 20, the air temperature inside the closed type power conversion unit 10 is estimated, and the angle adjustment circuit 31 maintains the estimated air temperature at a set predetermined value. An angle command is output.

  The angle commands output from each of the closed type power conversion units 10a, 10b,..., 10n are input to the three-way valve control circuit 30, where the average angle or the minimum angle of the angle commands is calculated to calculate the three-way valve. 27 angles are controlled.

DESCRIPTION OF SYMBOLS 1 Power converter 10, 10a, 10b, ..., 10n Closed type power conversion unit 11 Power semiconductor 11a Power module 12 Power converter control circuit 12a Temperature difference calculation circuit 20 Cooling body 21 Endothermic fin 22 Fan 23 Radiator 24 Piping DESCRIPTION OF SYMBOLS 25 Pump with motor 26 Bypass piping 27 Three-way valve 28 Temperature sensor 29 Angle command circuit 30 Three-way valve control circuit 31 Angle adjustment circuit 32 Temperature setting part 33 Air temperature estimation circuit 34 Average angle command calculation circuit 35 Three-way valve drive circuit 36 Minimum angle command Selection circuit 40 Multiphase motor

Claims (5)

In a cooling system for a power conversion device including a closed power conversion unit including a power converter having a power semiconductor and a power converter control circuit that controls an output of the power converter to a desired value.
A cooling body on which the power semiconductor is mounted;
A radiator installed outside,
A pump with an electric motor for circulating a refrigerant between the cooling body and the radiator;
A three-way valve that distributes the refrigerant circulating according to the angle of the valve to the bypass pipe arranged in parallel to the radiator and the radiator;
A heat absorber that is thermally connected to the cooling body and absorbs heat of air in the closed power conversion unit;
A fan for circulating air in the closed power conversion unit;
A temperature sensor for detecting an air temperature in the closed type power conversion unit;
An angle command circuit for calculating an angle command value of the three-way valve from an air temperature detected by the temperature sensor and a set temperature;
A three-way valve control circuit for controlling the angle of the three-way valve using the output of the angle command circuit as a command value;
And the angle of the three-way valve is controlled to keep the air temperature in the closed power conversion unit at a predetermined value. In a cooling system for a power conversion device including a closed power conversion unit including a power converter having a power semiconductor and a power converter control circuit that controls an output of the power converter to a desired value.
A cooling body on which the power semiconductor is mounted;
A radiator installed outside,
A pump with an electric motor for circulating a refrigerant between the cooling body and the radiator;
A three-way valve that distributes the refrigerant circulating according to the angle of the valve to the bypass pipe arranged in parallel to the radiator and the radiator;
A heat absorber that is thermally connected to the cooling body and absorbs heat of air in the closed power conversion unit;
A fan for circulating air in the closed power conversion unit;
A temperature sensor for detecting an air temperature in the closed type power conversion unit;
Between the amount of heat radiated in the closed type power conversion unit and a thermal resistance of a path for transferring heat from the air to the cooling body through the heat absorber, between the cooling body and the air in the closed type power conversion unit. A temperature difference calculation circuit for calculating a temperature difference;
An air temperature estimating circuit for estimating an air temperature in the closed power conversion unit from the temperature of the cooling body detected by the temperature sensor and the temperature difference calculated by the temperature difference calculating circuit;
An angle command circuit for calculating an angle command value of the three-way valve from the air temperature and the set temperature estimated by the air temperature estimation circuit;
A three-way valve control circuit for controlling the angle of the three-way valve using the output of the angle command circuit as a command value;
And the angle of the three-way valve is controlled to keep the air temperature in the closed power conversion unit at a predetermined value.   The cooling system for a power conversion device according to claim 1 or 2, wherein the heat absorber is installed in an air circulation path in the closed power conversion unit. The power conversion device includes a plurality of the closed power conversion units,
The cooling bodies in all the closed power conversion units are connected to the radiator so that the refrigerant circulates,
3. The three-way valve control circuit drives and controls the angle of the three-way valve using an average value of angle command values output from the angle command circuits of all the closed power conversion units as a command value. A cooling system for the power converter described. The power conversion device includes a plurality of the closed power conversion units,
The cooling bodies in all the closed power conversion units are connected to the radiator so that the refrigerant circulates,
2. The three-way valve control circuit drives and controls the angle of the three-way valve using a minimum value among the angle command values output from the angle command circuits of all the closed power conversion units as a command value. Or the cooling system of the power converter device of 2.

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