JP2009029187A - Cooling device for electric power converter of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To downsize a cooling device for an electric power converter of a hybrid vehicle. <P>SOLUTION: The cooling device comprises a common refrigerant supply passage 80 for supplying a refrigerant to an electric power converter 100 including inverters 21, 31 and a step-up converter 11; each of cooling flow passages 53a, 53b, 63a, 63b, 73a, 73b for cooling each of conversion modules, respectively, by means of refrigerants supplied from the passage 80; each of current detection sensors 28, 29, 38, 39 for detecting each of input/output currents in/from inverters 21, 31, respectively; flow rate regulating valves 55, 65, 75; control unit 90 for controlling opening degrees of the valves 55, 65, 75; and a refrigerant flow rate distribution means for varying the opening degrees of the valves 55, 65, 75 according to a ratio of a magnitude of each current detected by means of each of sensors 28, 29, 38, 39, and varying distribution ratios of the refrigerant flow rates from the common passage 80 to each of flow passages 53a, 53b, 63a, 63b, 73a, 73b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of a cooling device for a power converter of a hybrid vehicle.

  A hybrid vehicle that drives a vehicle with an engine and a motor, and an electric vehicle that drives a vehicle with a motor include a power converter that converts electric power of a secondary battery for driving the motor mounted on the vehicle into electric power for driving the motor. . The power converter includes an inverter that converts DC power supplied from a secondary battery into a three-phase AC current for driving a motor, and converts current by switching operations of a plurality of semiconductor elements. Since each semiconductor element generates heat in the switching operation, a cooling device is provided for circulating the cooling water to keep the inverter at a predetermined operating temperature. The cooling device includes a cooling channel that cools each semiconductor element of the inverter, a circulation pump that circulates the cooling water through the cooling channel, and a radiator that cools the cooling water whose temperature has been increased by cooling the semiconductor element.

  Since a cooling device mounted on a vehicle is required to be small, it is necessary to balance the flow rate of the cooling flow path of the cooling device and downsize the flow path shape so that the inverter can be cooled efficiently. It has been proposed (for example, see Patent Document 1).

  Further, the cooling device is required to reduce power consumption. For this reason, when the temperature of the inverter rises, the cooling device starts the circulation pump to cool the inverter, and when the inverter temperature is low, stops the operation of the circulation pump to drive the cooling device. A method for reducing power may be used. However, the magnitude of the current of an inverter used in a hybrid vehicle or an electric vehicle changes abruptly depending on the driving state of the vehicle. For example, when the current suddenly increases as in the case where the accelerator is suddenly opened, the temperature of the semiconductor element may rise rapidly, and the temperature of the semiconductor element may exceed the allowable temperature due to inadequate activation and cooling of the circulation pump. For this reason, a method has been proposed in which the circulation pump is activated in advance by the accelerator opening to prevent overheating of the semiconductor element (see, for example, Patent Document 2).

  Moreover, in the cooling of the inverter used for an electric vehicle, the method of cooling an inverter by controlling the rotation speed of a circulation pump according to the temperature of a semiconductor element and the output current of the inverter is proposed (for example, Patent Document 3). reference).

  In an electronic device that performs information processing with a large number of heat-generating semiconductor components housed inside a housing, the temperature of each heat-generating semiconductor is detected and the flow rate of the cooling medium to each semiconductor is adjusted, and the amount of heat generated and power consumption of the semiconductor Has been proposed (see, for example, Patent Document 4).

JP 2006-203138 A JP-A-6-121402 JP 2005-117819 A JP-A-8-63261

  By the way, in the prior art cooling devices described in Patent Documents 1 to 3, the circulation pump and the radiator are common, and the refrigerant is distributed to each cooling flow path for cooling each of the plurality of inverters from the common cooling water supply path. For example, the flow rate of each cooling channel is determined by the channel shape such as the cross-sectional area or length of each channel. And even when the flow rate of the cooling water is adjusted by the temperature of the semiconductor element or the like as in the prior art described in Patent Document 3, the ratio of the cooling water flowing through each cooling channel is not changed.

  On the other hand, in recent hybrid vehicles, a plurality of motor generators are used, and control is performed to change the load of each motor generator according to the running state so as to obtain an optimum driving state. Such a hybrid vehicle including a plurality of motor generators is provided with a plurality of inverters that supply driving power to each motor generator and convert electric power from the motor generator into charging power for a secondary battery. ing. And the load of each motor generator changes variously according to a driving | running | working state, Thereby, the output of each inverter and the emitted-heat amount also change variously. For this reason, when the ratio of the coolant flow rate supplied to each inverter is constant as in the prior art described in Patent Documents 1 to 3, the coolant flow rate corresponding to the maximum heat generation amount in each inverter can be flowed. It is necessary to use a circulation pump and a radiator that can dissipate the total calorific value of each inverter, which increases the size of the cooling device and increases the power consumption.

  Further, as in the prior art described in Patent Document 4, the method of controlling the flow rate of the cooling medium according to the temperature of a plurality of semiconductor elements cannot cope with a rapid temperature change of the inverter of the hybrid vehicle, The conductive element may overheat. For this reason, when the cooling flow rate is controlled according to the temperature of the semiconductor element, it is necessary to provide a larger cooling system in consideration of a control delay.

  An object of the present invention is to downsize a cooling device for a power converter of a hybrid vehicle.

  A cooling device for a power converter of a hybrid vehicle according to the present invention includes a common refrigerant supply path that supplies a refrigerant to a power converter that includes a plurality of current conversion modules and converts vehicle driving power, and a branch from the refrigerant supply path. Each cooling flow path for cooling each conversion module with the supplied refrigerant, each current detecting means for detecting each input / output current of each current conversion module, a flow rate adjusting valve provided in at least one cooling flow path, A cooling device for a power converter of a hybrid vehicle comprising: a control unit that controls an opening degree of the flow rate control valve, wherein the control unit adjusts the flow rate according to a ratio of each current magnitude detected by each current detection means It is characterized by having a refrigerant flow rate distribution means for changing the opening degree of the valve and changing the distribution ratio of the refrigerant flow rate from the common refrigerant supply path to each cooling flow path.

  Further, in the cooling device for a power converter of a hybrid vehicle of the present invention, the refrigerant flow rate distribution means is a distribution ratio of the refrigerant flow rate of the cooling flow path of the current conversion module in which the ratio of the magnitude of each current detected by each current detection means is large. And adjusting the opening of the flow control valve so as to reduce the distribution ratio of the refrigerant flow rate in the cooling flow path of the current conversion module in which the ratio of the magnitude of each current detected by each current detection means is small, Is also suitable.

  A cooling device for a power converter of a hybrid vehicle according to the present invention includes a common refrigerant supply path that supplies a refrigerant to a power converter that includes a plurality of current conversion modules and converts vehicle driving power, and a branch from the refrigerant supply path. Each cooling flow path for cooling each conversion module with the supplied refrigerant, each current detecting means for detecting each input / output current of each current conversion module, a flow rate adjusting valve provided in at least one cooling flow path, A cooling device for a power converter of a hybrid vehicle comprising: a control unit that controls an opening degree of the flow control valve, wherein the control unit is configured to drive the hybrid vehicle based on the magnitude of each current detected by each current detection unit. A travel mode prediction means for predicting the mode, and the opening of the flow rate control valve is changed in correspondence with the travel mode predicted by the travel mode prediction means, Having a coolant flow distribution means for changing the distribution ratio of the refrigerant flow rate to 却流 path, characterized by.

  In the cooling device for a power converter of a hybrid vehicle of the present invention, the input / output current of each current conversion module is a three-phase AC current, the current detection means detects the current of each phase, and the travel mode prediction means determines the current of each phase. It is also preferable to estimate the traveling mode from the ratio of the sizes of the two. It is also preferable that the power converter includes at least one voltage conversion module.

  The present invention has an effect that a cooling device for a power converter of a hybrid vehicle can be downsized.

  Hereinafter, preferred embodiments of the cooling device 10 for a power converter according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the power converter 100 mounted on the hybrid vehicle is a voltage conversion module that boosts the voltage from the secondary battery 18 to the voltages for the first and second motor generators 42 and 44. The converter 11, the first inverter 21 that is a current conversion module that converts the DC power boosted by the boost converter 11 into three-phase AC power for driving the first motor generator 42, and three for driving the second motor generator 44 And a second inverter 31 for converting into phase AC power.

  Boost converter 11 includes semiconductor elements 13a and 13b that perform a switching operation. The first and second inverters 21 and 31 have six semiconductor elements 22a, 22b, 23a, 23b, 24a, 24b and 32a, two for each of the three-phase AC U, V and W phases. 32b, 33a, 33b, 34a, 34b. The semiconductor elements 22a and 22b of the first inverter output U-phase power supplied to the first motor generator 42 from the power output line 25, and the semiconductor elements 23a and 23b supply V-phase power supplied to the first motor generator 42. The power is output from the power output line 26, and the semiconductor elements 24 a and 24 b output the W-phase power supplied to the first motor generator 42 from the power output line 27. The semiconductor elements 32 a and 32 b of the second inverter output U-phase power supplied to the second motor generator 44 from the power output line 35, and the semiconductor elements 33 a and 33 b are V-phase power supplied to the second motor generator 44. Power is output from the power output line 36, and the semiconductor elements 34 a and 34 b output W-phase power supplied to the second motor generator 44 from the power output line 37.

  The three-phase alternating currents output from the first and second inverters 21 and 31 are supplied to the first motor generator 42 and the second motor generator 44, respectively.

  On the other hand, the drive device for the hybrid vehicle includes an engine 41 and first and second motor generators. The output of the engine 41 is distributed by the power distribution device 43 into power for driving the first motor generator as a generator and power for driving the wheels 45 together with the second motor generator 44. The electric power generated by the first motor generator 42 is converted into direct current by the first inverter 21 and stored in the secondary battery 18. On the other hand, the second motor generator 44 is driven by driving three-phase AC power obtained by converting the electric power stored in the secondary battery 18 and directly drives the wheels 45. The traveling pattern of the hybrid vehicle is a pattern during normal traveling, and has various traveling patterns at the time of start-up, climbing, and the like.

  Current sensors 28 and 29 for measuring the current flowing in each phase are provided in any two of the three-phase power output lines 25, 26, and 27 from the first inverter 21 to the first motor generator 42. Yes. In the present embodiment, the current sensor is provided on any two power lines U, V, and W, and the current value of the other power line is obtained by means such as subtraction from the entire current value. However, a current sensor may be attached to the power output lines 25, 26, and 27 of each layer. Similarly, current sensors 38 and 39 for measuring the current flowing in each phase in any two of the power output lines 35, 36 and 37 of the three-phase power from the second inverter 31 to the second motor generator 44. Is provided. Similarly to the output of the first inverter, the current sensors 38, 39 may be attached to the power output lines 35, 36, 37 of the respective phases.

  The semiconductor elements 13a and 13b provided in the boost converter 11 and the semiconductor elements 22a, 22b, 23a, 23b, 24a and 24b and 32a, 32b, 33a, 33b, 34a and 34b provided in the inverters 21 and 31, respectively. Heat is generated by the switching operation. Therefore, cooling channels 53a and 53b for cooling the semiconductor elements 13a and 13b are provided inside or outside the boost converter 11. The cooling flow path may be configured to be divided into two as in the present embodiment, or may be configured as one. The cooling flow paths 53a and 53b are connected to the branch pipe 52 from the refrigerant supply pipe 80, and a flow rate adjustment valve 55 for adjusting the refrigerant flow rate between the refrigerant supply pipe 80 of the branch pipe 52 and the cooling flow paths 53a and 53b. Is attached. The cooling flow paths 53 a and 53 b of the boost converter 11 are gathered together in the collecting pipe 54 when they exit the boost converter 11, and are connected to the refrigerant discharge pipe 81.

  The first and second inverters 21, 31 also have cooling channels 63a, 63b, 73a for cooling the semiconductor elements 22a, 22b, 23a, 23b, 24a, 24b and 32a, 32b, 33a, 33b, 34a, 34b. , 73b are provided. Similarly to the cooling flow paths 53a and 53b of the boost converter, the cooling flow paths 63a and 63b of the first inverter are connected to the branch pipe 62 from the refrigerant supply pipe 80, and the refrigerant supply pipe 80 and the cooling flow path 63a of the branch pipe 62 are connected. , 63b, a flow rate adjusting valve 65 for adjusting the flow rate of the refrigerant is attached, and the cooling flow paths 73a, 73b of the second inverter are connected to the branch pipe 72 from the refrigerant supply pipe 80, and the refrigerant in the branch pipe 72 A flow rate adjusting valve 75 for adjusting the refrigerant flow rate is attached between the supply pipe 80 and the cooling flow paths 73a and 73b. Refrigerant pressurized by a refrigerant circulation pump (not shown) and cooled through the radiator is diverted from the refrigerant supply pipe 80 to the branch pipes 52, 62, 72, and the cooling flow paths 53a, 53b, 63a, 63b, 73a. , 73b, the respective semiconductor elements 13a, 13b, 22a, 22b, 23a, 23b, 24a, 24b and 32a, 32b, 33a, 33b, 34a, 34b are cooled, and the refrigerant whose temperature has risen is supplied to each outlet collecting pipe. From 54, 64, and 74, the refrigerant discharge pipe 81 returns to the circulation pump to be pressurized, and is cooled by the radiator to flow into the refrigerant supply pipe 80 as a low-temperature refrigerant.

  Each current sensor 28, 29, 38, 39 and each flow rate adjustment valve 55, 65, 75 are connected to the control unit 90, and the current value acquired by each current sensor is input to the control unit 90. The flow rate control valves 55, 65, and 75 are configured to be able to adjust the opening degree according to a command from the control unit 90. The engine 41, the first motor generator 42, and the second motor generator 44 are also connected to the control unit 90, respectively, and can be driven by commands from the control unit 90.

  The control unit 90 may be a computer including a CPU and a memory inside, or may be a combination of various electronic components so that a control operation can be performed.

  Operation | movement of the cooling device 10 for electric power converters demonstrated above is demonstrated. When the hybrid vehicle is activated, the control unit 90 acquires the current value flowing through each power line from the current sensors 28, 29 and 38, 39. Then, the control unit 90 acquires the amount of power output from the first inverter 21 or input to the first inverter 21. Similarly, the power output from the second inverter or the power input to the second inverter is detected. And according to the input / output electric energy of each inverter, each flow control valve 65,75 is adjusted, and the ratio of the refrigerant | coolant flow rate which flows into the cooling flow paths 63a, 63b, 73a, 73b of each inverter is changed. Specifically, a flow rate adjusting valve for adjusting the refrigerant flow rate of the inverter having a large current is set so that the refrigerant flow rate of the cooling flow path having a large ratio of each current detected by each of the current sensors 28, 29, 38, and 39 is increased. This is done by opening and reducing the opening of the other flow control valve. Since the amount of heat generated by the inverter is often proportional to its load, each flow rate control valve is adjusted so that the refrigerant flow rate is proportional to the output current of each inverter 21, 31 acquired by the current sensors 28, 29, 38, 39. You may adjust the opening degree of 65,75. To adjust the opening, a characteristic map of the opening and flow rate of each valve is provided in the memory of the control unit 90, the required flow rate is calculated from the measured current value, and the opening of each valve is adjusted from the result. May be. As described above, when the refrigerant flow rate of each of the inverters 21 and 31 is adjusted by the measured values of the current sensors 28, 29, 38, and 39, the refrigerant flow rate of the boost converter 11 is the first inverter 21 and the second inverter 31. It is good also as changing a refrigerant | coolant flow volume with the total output of these outputs. The control of the refrigerant flow rate described above is control for changing the flow rate distribution ratio of the refrigerant flowing through each refrigerant flow path.

  In the embodiment described above, the distribution ratio of the refrigerant flow rate to each inverter 21, 31 and boost converter 11 is changed according to the current value flowing through each inverter 21, 31 acquired by each current sensor 28, 29, 38, 39. Therefore, the distribution ratio of the refrigerant flow rate can be changed with a faster response than when the refrigerant flow rate is changed using the temperature sensor. For this reason, it is not necessary to enlarge the cooling device for the power converter in anticipation of a response delay, and the power conversion cooling device can be reduced in size.

  As described above, the hybrid vehicle has a traveling pattern in which outputs of two motor generators or inputs to the inverters 21 and 31 by power generation are variously combined, and various controls are performed by this traveling pattern. There is a case. Hereinafter, a travel pattern is predicted from the current values detected by the current sensors 28, 29, 38, and 39, and the refrigerant flow rate in the cooling flow paths of the inverters 21 and 31 or the boost converter 11 is controlled according to the predicted travel pattern. This will be explained.

  First, an engine crank mode will be described as an example. Many hybrid vehicles are configured to rotate the first motor generator 42 and crank the engine when the engine 41 is started. In such a vehicle, when the hybrid vehicle is activated, the first motor generator 42 is first rotated to start the engine 41. In this case, since the hybrid vehicle is stopped, the rotation of the second motor generator 44 directly connected to the wheels 45 is stopped, so that there is almost no output power of the second inverter 31. Therefore, the hybrid vehicle is activated, and the output current of the first inverter detected by the current sensors 28 and 29 of the first inverter 21 is larger than a certain threshold, for example, and is detected by the current sensors 38 and 39 of the second inverter 31. For example, when the output current of the second inverter 31 is smaller than a predetermined threshold, the control unit 90 predicts that the hybrid vehicle is in the engine crank mode. And the flow volume which adjusts the flow path of the cooling flow paths 53a and 53b of the boost converter 11 so that the refrigerant flow volume of the first inverter 21 and the boost converter 11 which are predicted to flow a large amount of current in the engine crank mode is increased. The adjustment valve 55 and the opening degree of the flow rate adjustment valve 65 for adjusting the refrigerant flow rate of the cooling flow paths 63a and 63b of the first inverter are increased to adjust the refrigerant flow rate of the cooling flow paths 73a and 73b of the second inverter 31. The opening degree of the flow control valve 75 is reduced. The opening adjustment operation of each flow rate control valve is performed when the hybrid vehicle shifts to a certain travel mode, predicting the travel mode from the current value detected by each current sensor, to an inverter or converter that is predicted to rise in temperature. Therefore, the cooling effect can be further increased by prediction. For this reason, there exists an effect that a cooling device can be reduced more in size.

  As in the above, when the output power from the second inverter is larger than that in normal driving, the control unit 90 predicts the climbing mode in which the climbing is steep, and the second inverter 31 The opening degree of the flow control valve 75 is increased so as to increase the refrigerant flow rate. Similarly, in the case of the rapid acceleration travel mode in which the accelerator is greatly depressed and accelerates rapidly, the current of the second inverter 31 also increases rapidly. Predict that it is in accelerated running mode. Then, the opening degree of the flow rate adjustment valve 75 is increased so as to increase the flow rate of the refrigerant to the second inverter 31 that supplies power to the second motor generator 44 that directly drives the wheels 45.

  Further, the control unit 90 detects the current flowing in each UVW phase of the second motor generator 44 from each of the current sensors 38 and 39 of the second motor generator 44 that is driven by being directly connected to the wheel 45, and the current value of any one of them. Is very large compared to the other two current values, for example, when a certain threshold value is exceeded, the second motor generator 44 is locked and the traveling mode is stopped. Predict that it is. In this case, the control unit 90 predicts that a large current flows to the second inverter 31 due to the lock, and increases the flow rate of the refrigerant flowing in the cooling flow paths 73a and 73b of the second inverter 31 in advance. Increase the opening of 75. As a result, the refrigerant flow rate can be increased before the inverter 31 is overheated by a large current due to the lock, so that the second inverter 31 can be effectively cooled, and the power converter cooling device can be downsized. There is an effect that can be done.

  In the embodiment described above, the flow rate adjusting valves 55, 65, and 75 for adjusting the refrigerant flow rate are attached to the inlets of the cooling channels. However, the cooling channels 53a, 53b, 63a, 63b, 73a, and 73b are described. As shown in FIG. 2, for example, as shown in FIG. 2, the flow rate regulating valve is connected to the second inverter having a large refrigerant flow rate without providing a flow rate regulating valve in each cooling channel. It is also preferable that 75 is provided so that the flow rate control valve is not provided in other inverters and converters.

It is a figure which shows the system | strain structure of the cooling device for power converters of the hybrid vehicle in embodiment of this invention. It is a figure which shows the system | strain structure of the cooling device for power converters of the hybrid vehicle in other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Power converter cooling device, 11 Boost converter, 13a, 13b, 22a, 22b, 23a, 23b, 24a, 24b Semiconductor element, 18 Secondary battery, 21 1st inverter, 25, 26, 27, 35, 36, 37 Power output line, 28, 29, 38, 39 Current sensor, 31 Second inverter, 41 Engine, 42 First motor generator, 43 Power distribution device, 44 Second motor generator, 45 Wheel, 52, 62, 72 Branch pipe, 53a, 53b, 63a, 63b, 73a, 73b Cooling flow path, 54, 64, 74 Collecting pipe, 55, 65, 75 Flow control valve, 80 Refrigerant supply pipe, 81 Refrigerant discharge pipe, 90 Control unit, 100 Power converter .

Claims (5)

A common refrigerant supply path that supplies a refrigerant to an electric power converter that includes a plurality of current conversion modules and converts electric power for driving the vehicle, and each cooling that cools each conversion module with the refrigerant that is branched from the refrigerant supply path A flow path, each current detection means for detecting each input / output current of each current conversion module, a flow control valve provided in at least one cooling flow path, a control unit for controlling the opening of the flow control valve, A cooling device for a power converter of a hybrid vehicle comprising:
The control unit changes the degree of distribution of the refrigerant flow rate from the common refrigerant supply path to each cooling flow path by changing the opening degree of the flow rate control valve according to the ratio of the magnitude of each current detected by each current detection means. Having a refrigerant flow rate distribution means,
A cooling device for a power converter of a hybrid vehicle. A cooling device for a power converter of a hybrid vehicle according to claim 1,
The refrigerant flow distribution means increases the distribution ratio of the refrigerant flow in the cooling flow path of the current conversion module having a large ratio of the magnitudes of the respective currents detected by the respective current detection means, and the magnitudes of the respective currents detected by the respective current detection means. Adjusting the opening of the flow control valve so as to reduce the distribution ratio of the refrigerant flow rate in the cooling flow path of the current conversion module having a small ratio
A cooling device for a power converter of a hybrid vehicle. A common refrigerant supply path that supplies a refrigerant to an electric power converter that includes a plurality of current conversion modules and converts electric power for driving the vehicle, and each cooling that cools each conversion module with the refrigerant that is branched from the refrigerant supply path A flow path, each current detection means for detecting each input / output current of each current conversion module, a flow control valve provided in at least one cooling flow path, a control unit for controlling the opening of the flow control valve, A cooling device for a power converter of a hybrid vehicle comprising:
The control unit predicts the driving mode of the hybrid vehicle based on the magnitude of each current detected by each current detecting means,
Corresponding to the travel mode predicted by the travel mode prediction means, the refrigerant flow distribution means for changing the opening ratio of the flow rate control valve and changing the distribution ratio of the refrigerant flow rate from the common refrigerant supply path to each cooling flow path. ,
A cooling device for a power converter of a hybrid vehicle. A cooling device for a power converter of a hybrid vehicle according to claim 3,
The input / output current of each current conversion module is a three-phase AC current, and the current detection means detects the current of each phase,
The driving mode prediction means estimates the driving mode from the ratio of the current magnitude of each phase,
A cooling device for a power converter of a hybrid vehicle. A cooling device for a power converter of a hybrid vehicle according to claim 1 or 3,
The power converter includes at least one voltage conversion module;
A cooling device for a power converter of a hybrid vehicle.

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