JP2008253098A - Cooling system and vehicle with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system for combining a thermal protection in a load drive circuit and power saving in a cooling apparatus, and to provide a vehicle with the same. <P>SOLUTION: A controller 40 generates a current instruction based on an output required for an AC motor M1 determined from the degree of an open of an accelerator in the vehicle, and controls a switching operation of a power element for composing an inverter 41 so as to match an actual motor current with the current instruction. The controller 40 estimates a loss generated in the inverter 14 based on the degree of the open of the accelerator, and configures a target flow rate Q* of cooling water flowing in cooling medium paths 52-58 based on the estimated loss. The controller 40 generates a signal PWR for driving a water pump 60 so as to circulate the cooling water at the configured target flow rate Q*, and outputs the signal PWR to the water pump 60. The water pump 60 has a rotating speed controlled in response to the signal PWR, and circulates the cooling water in the cooling medium paths 52-58 at the flow rate corresponding to the target flow rate Q*. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling system and a vehicle including the same, and more particularly to a cooling system for a load drive circuit and a vehicle equipped with the cooling system.

  Usually, in a vehicle such as an electric vehicle (EV) or a hybrid vehicle (HV), the driving force by electric energy is converted from DC power supplied from a high-voltage battery to three-phase AC power by an inverter. This is obtained by rotating a three-phase AC motor. Further, when the vehicle is decelerated, the battery is stored with regenerative energy obtained by the regenerative power generation of the three-phase AC motor, so that the vehicle travels without wasting energy.

  In such a hybrid vehicle or electric vehicle, the inverter generates heat by the switching operation of the switching element. Therefore, it is necessary to provide a cooling device for protecting the inverter from thermal destruction due to overheating.

  Conventionally, in a diesel engine, a gasoline engine, or the like, the combustion gas temperature in the cylinder reaches 2000 ° C. or higher, and therefore, a cooling liquid such as cooling water or oil is circulated to cool these parts. (For example, refer to Patent Documents 1 to 3).

  For example, Japanese Patent Laid-Open No. 2000-297643 (Patent Document 1) provides a coolant return passage having a flow rate control valve, and adjusts and controls the amount of coolant supplied to the engine side in accordance with the load state of the engine. Accordingly, an engine cooling apparatus that can reduce heat loss due to engine cooling and improve engine fuel efficiency is disclosed.

  Japanese Patent Laid-Open No. 11-294164 (Patent Document 2) discloses a cooling fan provided opposite to a radiator for dissipating heat of engine cooling water, and a cooling water passage between the engine and the radiator. Disclosed is a control device for a cooling fan that includes a thermostat that is provided and controls a valve opening amount that regulates the flow rate of cooling water. According to this, unnecessary operation of the cooling fan is prevented by controlling the rotation speed of the cooling fan in conjunction with controlling the valve opening amount of the thermostat according to the coolant temperature and the engine load range. ing.

  Further, Japanese Patent Laid-Open No. 10-8960 (Patent Document 3) predicts the amount of heat generated by the engine based on the operating state of the engine, and the cooling fan power necessary for radiating the amount of heat corresponding to the amount of generated heat from the coolant. Accordingly, a cooling fan device for a vehicle that drives the cooling fan in a feed-forward manner is disclosed.

  As for a cooling device for a hybrid vehicle, for example, Japanese Patent Application Laid-Open No. 11-285106 (Patent Document 4) and Japanese Patent Application Laid-Open No. 2004-324613 (Patent Document 5) describe a cooling apparatus between A radiator for circulating cooling water and an electric fan for supplying cooling air to the radiator are provided, and the cooling air volume of the electric fan based on the detection output of the electric motor and the power supply device and the predicted load of the prime mover (engine and electric motor) Fan driving means for controlling is disclosed.

Further, as a cooling device for a semiconductor element, for example, in Japanese Patent Laid-Open No. 2003-314910 (Patent Document 6), the number of revolutions of a refrigerant pump is controlled by the difference between the temperature of a temperature sensor provided on the semiconductor element cooling plate and a set temperature. What to do is disclosed.
JP 2000-297643 A JP-A-11-294164 Japanese Patent Laid-Open No. 10-8960 JP-A-11-285106 JP 2004-324613 A Japanese Patent Laid-Open No. 2003-314910

  In general, in an inverter cooling device, a configuration in which a refrigerant path is provided between a radiator and an inverter and an electric water pump is driven to circulate cooling water through the refrigerant path is widely adopted. In this configuration, the electric water pump is driven to rotate by receiving electric power from a power source mounted on the vehicle. Therefore, as the power consumption of the electric water pump is increased, the fuel consumption of the vehicle is deteriorated.

  However, among the conventional cooling devices described above, the engine cooling device is only intended to improve the fuel efficiency of the engine by maintaining the engine at a substantially constant temperature. Nothing has been considered. This is because, in many engine cooling devices, the water pump is driven by the rotational force from the crankshaft of the engine, and thus power consumption is not taken into consideration.

  In addition, for the device that controls the rotation speed of the refrigerant pump according to the detection result of the temperature of the semiconductor element cooling plate, although the power consumption of the refrigerant pump at low temperatures can be reduced, the amount of heat generated by the inverter due to a sudden change in the required output of the motor When the current increases rapidly, there is a possibility that the cooling capacity control cannot follow the actual inverter temperature rise. As a result, overheating of the inverter cannot be sufficiently prevented, and the inverter may be thermally destroyed.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a cooling system capable of achieving both thermal protection of the load drive circuit and power saving of the cooling device. is there.

  Another object of the present invention is to provide a vehicle including a cooling system capable of achieving both thermal protection of a load drive circuit and power saving of a cooling device.

  According to the present invention, a cooling system includes a drive circuit that converts power between a power source and an electric load by a switching operation of the switching element, a cooling device that cools the drive circuit by receiving power from the power source, and a drive And a cooling control device that controls the supply amount of the cooling medium to the circuit. The cooling control device includes a power loss estimation unit that estimates a power loss generated in the drive circuit, and a supply amount determination unit that determines a supply amount of the cooling medium based on the estimated power loss.

  According to the above cooling system, since an appropriate amount of cooling medium is set for the loss generated in the drive circuit, the cooling device is reduced compared to the cooling device that uniformly fixes the amount of cooling medium supplied. Electricity is achieved. Moreover, since the supply amount of the cooling medium can be reduced when the loss is low, the pressure loss in the cooling device can be reduced and the cooling efficiency can be increased. Furthermore, since an appropriate amount of cooling medium can be supplied with high responsiveness to the drive circuit that is expected to rise in temperature, the drive circuit can be reliably thermally protected.

  Preferably, the power loss estimation means includes first loss estimation means for estimating a power loss from a required output for the electric load. The supply amount determining means determines the supply amount of the cooling medium corresponding to the estimated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium.

  According to the above cooling system, an appropriate amount of cooling medium can be supplied with high responsiveness to the drive circuit expected to rise in temperature, so that the drive circuit can be thermally protected and the cooling device can save power. Can be realized.

  Preferably, the electric load is a rotating electric machine that generates a driving force of the vehicle. The cooling system further generates a current command based on the required output for the rotating electrical machine determined from the accelerator opening of the vehicle, and further includes a control device that controls the switching operation so that the driving current of the rotating electrical machine matches the current command. Prepare. The first loss estimation means estimates the power loss based on the accelerator opening.

  According to the above cooling system, since the supply amount of the cooling medium is set based on the accelerator opening that is a determinant of the required output, it is possible to easily achieve both thermal protection of the drive circuit and power saving of the cooling device. Can be achieved.

  Preferably, the electric load is a rotating electric machine that generates a driving force of the vehicle. The cooling system further includes a control device that controls the switching operation so that the output of the rotating electrical machine matches the required output. The first loss estimation means presets the relationship between the output of the rotating electrical machine and the power loss, and estimates the power loss corresponding to the requested output based on the set relationship.

  According to the above cooling system, since the supply amount of the cooling medium is set based on the required output, it is possible to easily achieve both thermal protection of the drive circuit and power saving of the cooling device.

  Preferably, the cooling system further includes a voltage sensor that detects an input voltage of the driving circuit. The power loss estimation means further includes power loss correction means for correcting the power loss estimated by the first loss estimation means using the input voltage detected by the voltage sensor. The supply amount determining means determines the supply amount of the cooling medium corresponding to the corrected power loss based on the relationship between the preset power loss and the supply amount of the cooling medium.

  According to the above cooling system, the supply amount of the cooling medium can be further adapted to the loss of the drive circuit, so that the power consumption of the cooling device can be further reduced.

  Preferably, the electric load is a rotating electric machine that generates a driving force of the vehicle. The cooling system generates a current command based on a required output to the rotating electrical machine, and includes a control device that controls the switching operation so that the driving current of the rotating electrical machine matches the current command, and a current sensor that detects the driving current. Further prepare. The power loss estimation means includes second loss estimation means for estimating power loss from the drive current. The second loss estimation means presets the relationship between the drive current and the power loss, and estimates the power loss corresponding to the detected drive current based on the set relationship. The supply amount determining means determines the supply amount of the cooling medium corresponding to the estimated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium.

  According to the above cooling system, since the supply amount of the cooling medium is set based on the drive current, the supply amount of the cooling medium can be further adapted to the loss of the drive circuit. Therefore, the power consumption of the cooling device can be further reduced.

  Preferably, the power loss estimation means includes third loss estimation means for calculating the input power and the output power of the drive circuit, respectively, and calculating the power loss from the difference between the calculated input power and output power. The supply amount determining means determines the supply amount of the cooling medium corresponding to the calculated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium.

  According to the above cooling system, since the supply amount of the cooling medium is set based on the calculation result of the power loss, the supply amount of the cooling medium can be further adapted to the loss of the drive circuit. Therefore, the power consumption of the cooling device can be further reduced.

  Preferably, the cooling device is provided with a refrigerant path through which the cooling medium flows, a radiator that cools the cooling medium, and a rotational drive driven by power supplied from the power source to supply the cooling medium to the refrigerant path. And a circulating pump. The cooling control device controls the discharge amount of the pump according to the determined supply amount of the cooling medium.

  According to the above cooling system, by making the pump discharge amount variable according to the power loss of the drive circuit, it is possible to reduce the power consumption of the pump while ensuring the cooling capacity necessary for cooling the drive circuit. it can.

  Preferably, the cooling device is provided with a refrigerant path through which the cooling medium flows, a radiator that cools the cooling medium, and a rotational drive driven by power supplied from the power source to supply the cooling medium to the refrigerant path. It includes a pump to be circulated, and a flow rate control valve that is disposed in a refrigerant path between the pump and the drive circuit and allows at least a part of the cooling medium to flow through the drive circuit in accordance with the valve opening amount. The cooling control device controls the valve opening amount in accordance with the determined supply amount of the cooling medium.

  According to the above cooling system, the flow rate of the cooling medium flowing through the drive circuit is made variable according to the power loss of the drive circuit, thereby reducing the pressure loss in the cooling device and saving the power of the pump. Can do.

  Preferably, the cooling device further includes a fan for supplying cooling air to the radiator. The cooling control device controls the supply amount of the cooling air based on the estimated power loss.

  According to the above cooling system, the amount of heat received from the drive circuit and the amount of heat released from the radiator can be made equal, so that the cooling capacity can be appropriately increased according to the increase in the amount of cooling medium supplied.

  Preferably, the cooling device includes a refrigeration cycle configured with a compressor, a condenser, a decompressor, and an evaporator. The cooling control device controls the discharge amount of the compressor according to the determined supply amount of the cooling medium.

  According to the above cooling system, in the cooling system composed of the refrigeration cycle, the cooling capacity necessary for cooling the drive circuit is ensured by making the discharge amount of the compressor variable according to the power loss of the drive circuit. However, the power consumption of the cooling system can be reduced.

  Preferably, the cooling device further includes a fan for supplying cooling air to the condenser. The cooling control device controls the supply amount of the cooling air based on the estimated power loss.

  According to the above cooling system, the amount of heat received from the drive circuit and the amount of heat released from the condenser can be made equal, so that the cooling capacity can be appropriately increased according to the increase in the amount of cooling medium supplied.

  Preferably, the cooling medium has a boiling point lower than the operating temperature of the switching element. The cooling device causes the cooling medium to collide with the cooling plate to which the switching element is fixed and cools the drive circuit by boiling.

  According to the above cooling system, by adopting boiling cooling for the cooling device, it is possible to efficiently cool the drive circuit in which the operating temperature of the switching element is higher than the boiling point of the cooling medium while suppressing power consumption.

Preferably, the switching element is a power element made of silicon carbide.
According to the above cooling system, by adopting the boil cooling for the cooling device, the drive circuit can be efficiently cooled while suppressing the power consumption of the cooling device.

Preferably, the switching element is a gallium nitride power element.
According to the above cooling system, by adopting boiling cooling for the cooling device, the drive circuit can be efficiently cooled while suppressing the power consumption of the cooling device.

According to the present invention, the vehicle includes any one of the cooling systems described above.
According to the above vehicle, the fuel consumption can be improved by reducing the power consumption of the cooling system.

  According to the present invention, it is possible to achieve both thermal protection of the drive circuit and power saving of the cooling device. As a result, the fuel efficiency of a vehicle equipped with the cooling system according to the present invention can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
1 is a block diagram conceptually showing a cooling system according to Embodiment 1 of the present invention.

  Referring to FIG. 1, a cooling system includes a radiator (radiator) 50, a refrigerant path 51, an inverter 14 that controls drive of an AC motor, an evaporator 54, a radiator 50, an electric pump (hereinafter referred to as a pump). ) 60, a gas-liquid separator 52, and an electric fan (hereinafter abbreviated as “fan”) 70.

  The pump 60 is a pump for circulating a refrigerant such as an antifreeze liquid, and circulates the refrigerant in the direction of an arrow shown in the drawing.

  The evaporator 54 exchanges heat between the liquid-phase refrigerant discharged from the pump 60 and the inverter 14, receives heat generated from the inverter 14, and cools the inverter 14.

  The radiator 50 receives the refrigerant flowing out of the evaporator 54 from the refrigerant passage 51 and cools the received refrigerant using the fan 70. The gas-liquid separator 52 is provided on the downstream side of the radiator 50, separates the refrigerant into a liquid phase and a gas phase, and sends only the liquid phase refrigerant to the upstream side of the pump 60.

  Control device 40 generates signal PWMI for driving and controlling inverter 14 based on torque command value TR and motor rotation speed MRN by a method described later, and outputs the generated signal PWMI to inverter 14.

  Further, the control device 40 generates a signal PDR for controlling the discharge amount of the pump 60 by a method described later, and outputs the generated signal PDR to the pump 60.

  Furthermore, the control device 40 generates a signal FDR for controlling the amount of cooling air supplied from the fan 70 by a method described later, and outputs the generated signal FDR to the fan 70.

  FIG. 2 is a state diagram (TS diagram) of the cooling system of FIG. 1. Points 1 to 4 in the figure indicate refrigerant state points in the cooling system of FIG. 1.

  Referring to FIG. 2, heat is exchanged by isothermal change 1-2 and isothermal change 2-3. Specifically, the isothermal change between points 1-2 indicates heat exchange between the inverter 14 and the refrigerant in the evaporator 54. At this time, the refrigerant receives from the inverter 14 a heat amount (heat input amount) Q1 indicated by an arrow in the figure.

  Further, the isothermal change between the points 2-3 indicates heat exchange between the refrigerant and the cooling air in the radiator 50. At this time, the refrigerant radiates heat (heat output) Q2 indicated by an arrow in the drawing to the cooling air.

  And the operating pressure P of a refrigerant | coolant is kept substantially constant by making this heat input Q1 and the heat output Q2 equal. That is, the refrigerant temperature T can be kept substantially constant.

FIG. 3 is a schematic block diagram of a motor drive device to which the cooling system of FIG. 1 is applied.
Referring to FIG. 3, the motor drive device includes a battery B, a power control unit 21 that controls AC motor M <b> 1, and a control device 40.

  AC motor M1 is a drive motor for generating torque for driving drive wheels of a hybrid vehicle or an electric vehicle. Further, AC motor M1 is a motor that has a function of a generator driven by an engine and operates as an electric motor for the engine and can start the engine, for example.

  Power control unit 21 includes boost converter 12, capacitor C <b> 2, and inverter 14.

  Boost converter 12 includes a reactor L1, NPN transistors Q1, Q2, and diodes D1, D2. Reactor L1 has one end connected to the power supply line of battery B and the other end connected to an intermediate point between NPN transistor Q1 and NPN transistor Q2. NPN transistors Q1 and Q2 are connected in series between the power supply line and the earth line. The collector of NPN transistor Q1 is connected to the power supply line, and the emitter of NPN transistor Q2 is connected to the ground line. Further, diodes D1 and D2 for passing a current from the emitter side to the collector side are connected between the collector and emitter of each NPN transistor Q1 and Q2.

  The capacitor C2 is connected between the power supply line and the ground line, and reduces the influence on the inverter 14 due to voltage fluctuation. The voltage sensor 13 detects the voltage Vm across the capacitor C2 (that is, corresponds to the input voltage of the inverter 14. The same applies hereinafter), and outputs the detected voltage Vm to the control device 40.

  Inverter 14 includes U-phase arm 15, V-phase arm 16, and W-phase arm 17. U-phase arm 15, V-phase arm 16 and W-phase arm 17 are provided in parallel between the power supply line and the earth line.

  U-phase arm 15 includes NPN transistors Q3 and Q4 connected in series. V-phase arm 16 includes NPN transistors Q5 and Q6 connected in series. W-phase arm 17 includes NPN transistors Q7 and Q8 connected in series. Further, diodes D3 to D8 that flow current from the emitter side to the collector side are connected between the collectors and emitters of the NPN transistors Q3 to Q8, respectively.

  In the present embodiment, NPN transistors Q1-Q8 and diodes D1-D8 constituting boost converter 12 and inverter 14 are made of, for example, silicon carbide (SiC). SiC power elements are power semiconductor elements that have been attracting attention in recent years, and have larger forbidden bandwidth and thermal conductivity than conventional Si-based power elements, and have high withstand voltage, high heat resistance, low loss, low It has characteristics such as on-resistance, and has many characteristics required for automotive electronics.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of AC motor M1. In other words, AC motor M1 is a three-phase permanent magnet motor, and is configured such that one end of three coils of U, V, and W phases is commonly connected to the midpoint. The other end of the U-phase coil is at the midpoint of NPN transistors Q3 and Q4, the other end of the V-phase coil is at the midpoint of NPN transistors Q5 and Q6, and the other end of the W-phase coil is at the midpoint of NPN transistors Q7 and Q8. Each is connected.

  As the battery B, a secondary battery such as nickel hydride or lithium ion, a fuel cell, or the like is applied. Further, as a power storage device replacing battery B, a large-capacity capacitor such as an electric double layer capacitor may be used. Voltage sensor 10 detects DC voltage Vb output from battery B and outputs the detected DC voltage Vb to control device 40.

  When DC voltage Vb is supplied from battery B, boost converter 12 boosts DC voltage Vb according to the period during which NPN transistor Q2 is turned on by signal PWMC from control device 40, and supplies the boosted voltage to capacitor C2.

  When boost converter 12 receives signal PWMC from control device 40, boost converter 12 steps down the DC voltage supplied from inverter 14 via capacitor C 2 and charges battery B.

  When the DC voltage is supplied from the battery B, the inverter 14 converts the DC voltage into an AC voltage based on the signal PWMI from the control device 40 and drives the AC motor M1. As a result, AC motor M1 is driven to generate the required torque specified by the torque command value.

  Further, the inverter 14 converts the AC voltage generated by the AC motor M1 into a DC voltage based on the signal PWMI from the control device 40 during regenerative braking of the hybrid vehicle or electric vehicle on which the motor drive device is mounted. DC voltage is supplied to battery B.

  Note that regenerative braking here refers to braking with regenerative power generation when the driver operating the hybrid vehicle or electric vehicle performs footbrake operation, or while not operating the footbrake, Including decelerating (or stopping acceleration) the vehicle while regenerating power.

  Current sensor 24 detects motor currents Iv and Iw flowing through AC motor M <b> 1, and outputs the detected motor currents Iv and Iw to control device 40. In FIG. 1, only two current sensors 24 are shown. This is because, when AC motor M1 is a three-phase motor, if motor currents Iv and Iw flowing in two phases are detected, motor current Iu flowing in the remaining phases is calculated based on the detected motor currents Iv and Iw. Because it can. Therefore, when the motor currents Iu, Iv, and Iw flowing in the three phases are detected independently, three current sensors 24 may be provided.

  The resolver 30 is attached to the rotation shaft of the AC motor M1, detects the rotation angle θ of the rotor of the AC motor M1, and outputs it to the control device 40.

  Control device 40 receives torque command value TR and motor rotational speed MRN from an external ECU (Electric Control Unit) (not shown), receives output voltage Vm from voltage sensor 13, receives motor currents Iv and Iw from current sensor 24, and resolves them. 30 receives the rotation angle θ. Based on output voltage Vm, torque command value TR, motor currents Iv, Iw, and rotation angle θ, control device 40 uses inverters 14 to drive NPN transistors Q3-Q8 when inverter 14 drives AC motor M1 by a method described later. A signal PWMI for switching control is generated, and the generated signal PWMI is output to the inverter 14.

  Further, the control device 40 generates an AC voltage generated by the AC motor M1 based on the output voltage Vm, the torque command value TR, and the motor currents Iv and Iw at the time of regenerative braking of a hybrid vehicle or an electric vehicle on which the motor driving device is mounted. Is converted to a DC voltage, and the generated signal PWMI is output to the inverter 14.

  Furthermore, when inverter 14 drives AC motor M1, control device 40 switches NPN transistors Q1, Q2 of boost converter 12 based on DC voltage Vb, output voltage Vm, torque command value TR, and motor rotation speed MRN. A signal PWMC for control is generated and output to boost converter 12.

  In the motor drive device configured as described above, the inverter 14 is cooled by the cooling system shown in FIG. 1 in order to suppress a temperature rise due to heat loss generated from the switching element. At this time, the SiC power element constituting the switching element has an operating temperature rise to about 400 ° C. while the upper limit of the operating temperature of the conventional Si-based power element is about 150 ° C. In addition, boiling cooling with high cooling performance is applied.

  FIG. 4 is a cross-sectional view for explaining the cooling structure of the NPN transistor constituting the inverter.

  Referring to FIG. 4, heat radiating plate 86 is arranged on heat sink 90 via silicon grease 88. The insulating substrate 82 is made of aluminum nitride 822 and aluminum 820 and 824. Aluminum 820 is installed on one main surface of aluminum nitride 822, and aluminum 824 is installed on the opposite surface of one main surface of aluminum nitride 822.

  The insulating substrate 82 is fixed to the heat sink 86 by bonding aluminum 824 to the heat sink 86 with solder 84. The NPN transistor Q3 is fixed to the insulating substrate 82 by being bonded to the aluminum 820 by the solder 80. The wire WL is connected to the NPN transistor Q3.

  Other NPN transistors and diodes are also fixed to the substrate (insulating substrate 82 and heat sink 86) in the manner shown in FIG. 4 in the same manner as NPN transistor Q3.

The heat sink 90 and the plate-like bodies 92 and 94 constitute the evaporator 54 shown in FIG.
Specifically, a refrigerant path for allowing cooling water to flow is provided between the lower surface of the heat sink 90 and the plate-like body 94. The refrigerant path is divided into two in the vertical direction by a plate-like body 92 in which a plurality of through holes 96 are formed. The liquid refrigerant discharged from the pump 60 (not shown) is introduced into the first refrigerant path located below the divided refrigerant paths.

  Then, the refrigerant introduced into the first refrigerant path flows through the first refrigerant path to the second refrigerant path located on the upper side while flowing through the first refrigerant path, as indicated by an arrow in the figure. Flows in.

  In the second refrigerant path, when the refrigerant that has passed through the through hole 96 collides with the lower surface of the heat sink 90, the flow direction is changed by 90 ° to flow radially on the plane of the heat sink 90, but at this time, heat is received from the heat sink 90. Heated to flow downstream while generating bubbles. The refrigerant containing the bubbles is led out to the refrigerant path 51 and then returned to the radiator 50 through the refrigerant path 51.

  In the present embodiment, a case where boiling cooling is employed in the cooling system will be described. However, the scope of application of the present invention is not limited to boiling cooling, but includes all cooling systems that are cooled by a refrigerant. .

  Next, drive control of the pump 60 and the fan 70 in the cooling system according to the embodiment of the present invention thus configured will be described.

FIG. 5 is a functional block diagram of the control device 40 in FIG.
Referring to FIG. 5, control device 40 includes an inverter control circuit, a converter control circuit (not shown), a pump drive control unit 430 that drives and controls pump 60, and a fan drive control unit 440 that drives and controls fan 70. Including.

  The inverter control circuit includes a current command conversion unit 410, subtracters 412 and 414, PI control units 416 and 418, a two-phase / three-phase conversion unit 420, a PWM generation unit 422, and a three-phase / two-phase conversion unit. 424. In addition, although FIG. 4 demonstrates the case where PWM control is applied to an inverter control circuit, it is not limited to this, It is good also as a structure to which rectangular wave control is applied.

  The three-phase / two-phase converter 424 receives the motor currents Iv, Iw from the two current sensors 24, 24. The three-phase / 2-phase converter 424 receives the motor current Iu based on the motor currents Iv, Iw. = -Iv-Iw is calculated.

  Further, the three-phase / two-phase converter 424 performs three-phase to two-phase conversion on the motor currents Iu, Iv, and Iw using the rotation angle θ from the resolver 30. That is, the three-phase / two-phase conversion unit 424 uses the three-phase motor currents Iu, Iv, Iw flowing in the respective phases of the three-phase coil of the AC motor M1 as currents flowing in the d-axis and the q-axis using the rotation angle θ. Convert to values Id and Iq. Then, the three-phase / two-phase converter 424 outputs the calculated current value Id to the subtractor 412 and outputs the calculated current value Iq to the subtractor 414.

  Current command conversion unit 410 receives torque command value TR and motor rotational speed MRN from an external ECU, and receives voltage Vm from voltage sensor 13. Current command conversion unit 410 generates current commands Id * and Iq * for outputting the required torque specified by torque command value TR based on torque command value TR, motor rotation speed MRN, and voltage Vm. The generated current commands Id * and Iq * are output to the subtracters 412 and 414, respectively.

  Subtractor 412 receives current command Id * from current command conversion unit 410 and receives current value Id from three-phase / two-phase conversion unit 424. Then, the subtractor 412 calculates a deviation (= Id * −Id) between the current command Id * and the current value Id, and outputs the calculated deviation to the PI control unit 416. Subtractor 414 receives current command Iq * from current command converter 410 and receives current value Iq from three-phase / 2-phase converter 424. Then, the subtractor 414 calculates a deviation (= Iq * −Iq) between the current command Iq * and the current value Iq, and outputs the calculated deviation to the PI control unit 418.

  The PI control units 416 and 418 calculate voltage operation amounts Vd and Vq for motor current adjustment using the PI gain with respect to the deviations Id * −Id and Iq * −Iq, respectively, and the calculated voltage operation amounts Vd , Vq to the 2-phase / 3-phase converter 420.

  The two-phase / three-phase conversion unit 420 performs two-phase three-phase conversion on the voltage operation amounts Vd and Vq from the PI control units 416 and 418 using the rotation angle θ from the resolver 30. That is, the two-phase / three-phase converter 420 applies the voltage operation amounts Vd and Vq applied to the d-axis and the q-axis to the voltage operation amounts Vu and Vv applied to the three-phase coil of the AC motor M1 using the rotation angle θ. , Vw. Then, the two-phase / three-phase converter 420 outputs the voltage manipulated variables Vu, Vv, and Vw to the PWM generator 422.

  The PWM generator 422 generates a signal PWMI based on the voltage manipulated variables Vu, Vv, Vw and the voltage Vm from the voltage sensor 13 and outputs the generated signal PWMI to the inverter 14.

  As described above, the inverter control circuit converts the required torque of AC motor M1 (corresponding to torque command value TR) into current commands Id * and Iq * of the d-axis component and q-axis component of AC motor M1, So-called current control is employed in which feedback is performed by PI control so that the actual current values Id and Iq coincide with these current commands.

  The torque command value TR is set by a torque command calculation unit 400 provided in the external ECU. Specifically, the torque command calculation unit 400 first calculates the vehicle required power from the accelerator opening ACC of the vehicle and the vehicle speed, and determines the motor required power to satisfy the vehicle required power. For example, in a hybrid vehicle, the vehicle required power is secured by the sum of the engine output power and the motor output power. Therefore, after determining the engine output power with priority on engine efficiency, the engine output power is subtracted from the vehicle required power. The required motor power is determined. Then, the motor required torque (torque command value TR) is calculated in consideration of the motor rotational speed MRN with the determined motor required power mainly taking into account the charge amount of the battery B and the like.

  Here, in the current control described above, a loss occurs in each NPN transistor when the feedback-controlled current passes through the NPN transistors Q3 to Q8 of the inverter 14. Since this loss is substantially proportional to the square of the passing current, the loss generated in NPN transistors Q3 to Q8 increases as torque command value TR of AC motor M1 increases.

  And if the loss (heat generation amount) generated in the inverter 14 increases, it is necessary to increase the cooling capacity of the cooling system following this. In particular, when the loss of the inverter 14 increases rapidly in response to a rapid change in the required torque of the AC motor M1, it is necessary to quickly increase the cooling capacity.

  In order to ensure the control response of the cooling system, there is a method of driving the cooling system while fixing the cooling capacity required when the loss of the inverter 14 becomes maximum. However, in this method, since the flow rate of the refrigerant circulating in the refrigerant path is fixed near the maximum flow rate, it is necessary to continuously apply a large driving force to the pump 60. This unnecessarily increases the power consumption of the cooling system, which causes a reduction in fuel consumption in a vehicle equipped with a motor drive device.

  Therefore, the cooling system according to the present invention is configured to estimate the loss generated in the inverter 14 during the drive control of the AC motor M1, and to variably control the flow rate of the refrigerant flowing through the refrigerant path 51 according to the estimated loss. .

  Further, in order to efficiently dissipate the heat generated from the inverter 14 received by the refrigerant to the cooling air to lower the refrigerant temperature, the cooling from the fan 70 provided in the radiator 50 is performed according to the estimated loss of the inverter 14. The air supply amount is variably controlled.

  According to this, when the refrigerant flow rate increases, the supply amount of cooling air from the fan 70 also increases. That is, as the heat removal capability from the inverter increases due to the increase in the refrigerant flow rate, the heat dissipation capability from the radiator 50 also increases.

  This is to avoid the operating pressure P and operating temperature T1 of the cooling system from increasing due to the unbalanced amount of heat input Q1 and amount of heat output Q2 shown in the state diagram of FIG. The increase in the operating pressure P and the operating temperature T1 of the cooling system leads to a problem that the heat removal capability itself from the inverter 14 hardly increases even when the refrigerant flow rate increases.

  Therefore, according to the present invention, the cooling capacity of the cooling system can be increased following the temperature increase of the inverter 14. As a result, the thermal protection of the inverter 14 at high temperatures can be reliably performed, while the power consumption can be prevented from being increased unnecessarily at low temperatures. As a result, the cooling system can save power and improve the fuel efficiency of the vehicle.

[Explanation of inverter loss estimation means]
As a means for estimating the loss of the inverter 14, a configuration for estimating the loss based on the required power for the AC motor M1 is employed in the present embodiment. According to this, it is possible to supply the refrigerant with high responsiveness to the inverter 14 that is expected to rapidly increase in temperature due to a rapid increase in required power. Therefore, the inverter 14 can be reliably protected from overheating.

  Specifically, in the control device 40 of FIG. 5, the pump drive control unit 430 generates an inverter based on the accelerator opening ACC detected by an accelerator opening sensor (not shown) that detects the amount of depression of the accelerator pedal. 14 losses are estimated.

  In FIG. 5, as described above, the torque command value TR given to the inverter control circuit is based on the accelerator opening ACC from the accelerator opening sensor in the torque command calculation unit 400 of the external ECU (for example, a hybrid ECU). It is determined by comprehensively considering the charge amount of B and the like. At this time, the determined torque command value TR increases so as to be substantially proportional to the increase in the accelerator opening ACC. When receiving the torque command value TR from the external ECU, the inverter control circuit converts the torque command value TR into the current commands Id * and Iq * by the method described above, and the current according to the converted current commands Id * and Iq *. Execute control.

  At this time, the NPN transistors Q3 to Q8 of the inverter 14 generate a loss proportional to the square of the motor current substantially corresponding to the current commands Id * and Iq *. That is, since the one-to-one correspondence as shown in FIG. 6 is established between the loss generated in the inverter 14 and the accelerator opening ACC, the loss of the inverter 14 is estimated based on the accelerator opening ACC. Is possible.

  Therefore, the pump drive control unit 430 presets the relationship between the accelerator opening ACC and the target flow rate Q * based on the relationship between the accelerator opening ACC and the loss of the inverter 14 shown in FIG. The target flow rate Q * is set based on the relationship.

  FIG. 7 is a diagram showing the relationship between the accelerator opening ACC, the target flow rate Q *, and the target air volume F *.

  Referring to line LN1 in FIG. 7, target flow rate Q * is set to increase as accelerator opening ACC increases. Specifically, the target flow rate Q1 corresponding to a certain accelerator opening A1%, for example, coincides with current commands Id * and Iq * determined based on the torque command value TR corresponding to the accelerator opening A1%. Thus, the loss of the inverter 14 generated per unit time when the motor currents Id and Iq whose currents are controlled flow through the NPN transistors Q3 to Q8 of the inverter 14 is estimated. For the estimated loss of the inverter 14, The amount of heat radiation per unit time when the refrigerant corresponding to the target flow rate Q1 is circulated is set to exceed.

  Then, the pump drive control unit 430 stores the relationship between the accelerator opening degree ACC and the target flow rate Q * indicated by the line LN1 in FIG. 7 in advance in a storage area (not shown) as a target flow rate setting map. When ACC is given, the corresponding flow rate is extracted from the target flow rate setting map and set as the target flow rate Q *. Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the discharge amount of the pump 60 matches the set target flow rate Q * and outputs the signal PDR to the pump 60. The number of revolutions of the pump 60 is controlled according to the signal PDR from the pump drive control unit 430, and the refrigerant having a flow rate that matches the target flow rate Q * is circulated through the refrigerant path 51.

  Further, in the fan drive control unit 440, similarly to the pump drive control unit 430, the relationship between the accelerator opening degree ACC and the target air volume F * shown in the line LN2 in FIG. 7 is set in advance and illustrated as a target air volume setting map. Not stored in the storage area. In this relation, the target air volume F1 corresponding to a certain accelerator opening A1% is based on the amount of heat radiated from the refrigerant to the cooling air (corresponding to the heat output Q2 in FIG. 2) based on the accelerator opening A1%. This is equivalent to the estimated loss of the inverter 14, and is set to be approximately equal to the amount of heat (heat input Q1 in FIG. 2) received by the refrigerant from the inverter 14.

  Then, when the accelerator opening degree ACC is given, the fan drive control unit 440 extracts the corresponding air volume from the target air volume setting map and sets it as the target air volume F *. The fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the cooling air is supplied with the set target air volume F *, and outputs the signal FDR to the fan 70. The fan 70 has a rotation speed controlled in accordance with a signal FDR from the fan drive control unit 440 and supplies cooling air having an air volume that matches the target air volume F * to the radiator 50.

  FIG. 8 is a flowchart for illustrating drive control of pump 60 and fan 70 according to the first embodiment of the present invention.

  Referring to FIG. 8, upon receiving accelerator opening ACC from the accelerator opening sensor (step S01), pump drive control unit 430 receives a target flow rate setting map (stored in line LN1 in FIG. 7) stored in advance in the storage area. The flow rate corresponding to the accelerator opening degree ACC given from (equivalent) is extracted and set as the target flow rate Q * (step S02).

  The fan drive control unit 440 extracts the air volume corresponding to the accelerator opening ACC given from the target air volume setting map (corresponding to the line LN2 in FIG. 7) stored in advance in the storage area, and extracts the target air volume F *. (Step S03).

  Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the target flow rate Q * set in step S02 matches the discharge amount, and outputs the signal PDR to the pump 60 (step S04). The rotation speed of the pump 60 is controlled according to the signal PDR of the pump drive control unit 430, and the refrigerant having a flow rate that matches the target flow rate Q * is discharged and circulated through the refrigerant path 51.

  The fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the target air volume F * set in step S03 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S05). . The rotation speed of the fan 70 is controlled in accordance with the signal FDR from the fan drive control unit 440, and the cooling air having the air volume that matches the target air volume F * is supplied to the radiator 50.

  As described above, according to the first embodiment of the present invention, by variably controlling the flow rate of the refrigerant based on the required output of the AC motor, the inverter loss that changes in accordance with the operating state of the AC motor can be prevented. An appropriate flow rate of refrigerant can be supplied with good responsiveness. Thereby, it is possible to realize power saving of the cooling system as compared with the conventional cooling system that drives the cooling system while fixing the cooling capacity required when the loss of the inverter 14 is maximized. As a result, the fuel consumption of the vehicle can be improved.

  The means for estimating the loss of the inverter 14 can be performed by the configurations disclosed in the following modifications 1 to 4 in addition to the configuration estimated based on the accelerator opening ACC described above.

[Modification 1]
The loss of the inverter 14 can also be estimated by deriving in advance the relationship between the output (torque, rotation speed) of the AC motor M1 and the loss of the inverter 14, as described below.

  According to this, it is possible to estimate the loss more accurately while estimating the loss of the inverter 14 uniquely from the accelerator opening including the variation of several percent. That is, the difference between the estimated loss and the loss actually generated during the operation of the inverter 14 can be further reduced. As a result, it is possible to suppress the refrigerant flow rate from becoming excessive with respect to the loss of the inverter 14, and to further reduce the power consumption of the pump 60.

FIG. 9 is a diagram showing the relationship between the output characteristics of AC motor M1 and the loss of inverter 14. In FIG.
Referring to FIG. 9, line LN3 corresponds to the relationship between output torque of AC motor M1 and motor rotational speed MRN. The torque of AC motor M1 is substantially constant up to a predetermined rotational speed, and when it exceeds the predetermined rotational speed, it gradually decreases as motor rotational speed MRN increases.

  The loss of the inverter 14 tends to increase as the output (torque × rotational speed) of the AC motor M1 becomes relatively high. The losses L1, L2, L3,... Of the inverter 14 shown in the figure are obtained by actually measuring or calculating the loss generated in the inverter 14 when the output of the AC motor M1 is changed in advance. is there. Then, the relationship shown in FIG. 10 is derived by appropriately setting the target flow rate Q * corresponding to the obtained loss.

FIG. 10 is a diagram showing the relationship between the output characteristics of AC motor M1 and target flow rate Q *.
Referring to FIG. 10, target flow rates Qa, Qb, Qc... Are set corresponding to the losses L1, L2, L3. For example, when the operating state of AC motor M1 is the operating state specified by output torque T1 and motor rotational speed MRN1 (corresponding to point Pa in the figure), the loss of inverter 14 is estimated to be L1 from the relationship shown in FIG. The The target flow rate Q * in this case is set to Qa from the relationship shown in FIG.

  The pump drive control unit 430 stores the relationship between the output characteristics of the AC motor M1 in FIG. 10 and the target flow rate Q * in advance in a storage area (not shown) as a target flow rate setting map, and requests the AC motor M1 from the external ECU. When the torque command value TR and the motor rotational speed MRN are given as outputs, the flow rate corresponding to the requested output is extracted from the target flow rate setting map and set as the target flow rate Q *. Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the set target flow rate Q * matches the discharge amount, and outputs the generated signal PDR to the pump 60.

  Although illustration is omitted, also in the fan drive control unit 440, based on the relationship between the output characteristic of the AC motor M1 and the loss of the inverter 14 in FIG. The relationship is preset and stored in the storage area. Then, when the torque command value TR and the motor rotational speed MRN are given from the external ECU, the fan drive control unit 440 extracts the air volume corresponding to the requested output from the target air volume setting map and sets it as the target air volume F *. At the same time, a signal FDR for driving the fan 70 is generated and output to the fan 70 so that the set target air volume F * and the supply amount of cooling air coincide with each other.

  FIG. 11 is a flowchart for illustrating drive control of pump 60 and fan 70 according to the first modification of the first embodiment of the present invention.

  Referring to FIG. 11, upon receiving torque command value TR and motor rotation speed MRN from an external ECU (step S11), pump drive control unit 430 receives a target flow rate setting map (FIG. 10) stored in advance in a storage area. The flow rate corresponding to the torque command value TR and the motor rotational speed MRN given from the above is extracted and set as the target flow rate Q * (step S12).

Similarly, in fan drive control unit 440, when torque command value TR and motor rotational speed MRN are received from the external ECU, torque command value TR and the command value TR given from the target air volume setting map stored in the storage area in advance are stored. The air volume corresponding to the motor rotational speed MRN is extracted and set as the target air volume F * (step S13).
Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the target flow rate Q * set in step S12 matches the discharge amount, and outputs the signal PDR to the pump 60 (step S14). The rotation speed of the pump 60 is controlled according to the signal PDR of the pump drive control unit 430, and the refrigerant having a flow rate that matches the target flow rate Q * is discharged and circulated through the refrigerant path 51.

  Further, the fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the target air volume F * set in step S13 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S13). S15). The rotation speed of the fan 70 is controlled in accordance with the signal FDR from the fan drive control unit 440, and the cooling air having the air volume that matches the target air volume F * is supplied to the radiator 50.

[Modification 2]
The relationship between the output characteristic of AC motor M1 and the loss of inverter 14 shown in FIG. 9 is that the current generated by using preset input voltage Vm of inverter 14 and input voltage Vm and torque command value TR. It is obtained based on the commands Id * and Iq *.

  Therefore, even when AC motor M1 outputs the torque specified by torque command value TR, when actual value of input voltage Vm of inverter 14 is different from the set value, it is actually generated in inverter 14. It is possible that the loss that is present is different from the loss estimated from the relationship of FIG.

  For example, even when the output of the AC motor M1 matches the required output, if the input voltage Vm is half of the set value, the current passing through the inverter 14 increases to approximately twice the set value. It becomes. As a result, the loss of the inverter 14 increases in proportion to the square of the current value, and thus increases to approximately four times the loss estimated from the relationship of FIG. In this case, sufficient cooling capacity cannot be obtained with the target flow rate Q * and the target air flow rate F * set based on the estimated loss of the inverter 14.

  Therefore, in this modification, the loss of the inverter 14 derived from the relationship of FIG. 9 is corrected according to the actual measurement value of the input voltage Vm of the inverter 14.

  According to this, in the case of the above-described example, the inverter obtained based on the torque command value TR and the motor rotational speed MRN from the relationship of FIG. 9 in response to the voltage Vm from the voltage sensor 13 being half of the set value. The loss of 14 is corrected so as to be approximately four times the loss. At this time, in order to ensure the cooling capacity commensurate with the corrected loss, the target flow rate Q * is approximately 4 of the flow rate derived from the relationship between the output characteristics of the AC motor M1 and the target flow rate Q * shown in FIG. Obviously, it is only necessary to correct the setting by a factor of two.

Therefore, when the torque command value TR and the motor rotation speed MRN are given as the requested output of the AC motor M1 from the external ECU, the pump drive control unit 430 has a flow rate corresponding to the requested output from the target flow rate setting map shown in FIG. Is extracted and set as the target flow rate Q *, and the ratio r between the detected value of the voltage Vm from the voltage sensor 13 and the set value is obtained. Then, the target flow rate Q * set by the equation (1) is corrected using this ratio r.
Q * (correction value) = 1 / r ² · Q * (setting value) (1)
Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the corrected target flow rate Q * matches the discharge amount, and outputs the signal PDR to the pump 60. As a result, the rotation speed of the pump 60 is controlled according to the signal PDR of the pump drive control unit 430, and the refrigerant having a flow rate that matches the target flow rate Q * is discharged and circulated through the refrigerant path 51.

Such correction is also executed in the fan drive control unit 440. That is, when the torque command value TR and the motor rotation speed MRN are given from the external ECU, the fan drive control unit 440 extracts the air volume corresponding to the requested output from the preset target air volume setting map, and the target air volume F *. Set as. Then, the target air volume F * set by the equation (2) is corrected using the ratio r between the detected value of the voltage Vm from the voltage sensor 13 and the set value.
F * (correction value) = 1 / r ² · F * (setting value) (2)
Then, the fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the corrected target air volume F * matches the supply amount of cooling air, and outputs the signal FDR to the fan 70.

  FIG. 12 is a flowchart for illustrating drive control of pump 60 and fan 70 according to the second modification of the first embodiment of the present invention.

  Referring to FIG. 12, pump drive control unit 430 and fan drive control unit 440 receive torque command value TR and motor rotational speed MRN from an external ECU, and input voltage Vm of inverter 14 from voltage sensor 13 (step S21). ). Then, the pump drive control unit 430 extracts the flow rate corresponding to the torque command value TR and the motor rotational speed MRN given from the target flow rate setting map (see FIG. 10) stored in advance in the storage area, and outputs the target flow rate. Set as Q * (step S22).

  Similarly, the fan drive control unit 440 extracts the air flow corresponding to the torque command value TR and the motor rotational speed MRN given from the target air flow setting map stored in advance in the storage area, and sets it as the target air flow F *. Set (step S23).

  Next, the pump drive control unit 430 corrects the target flow rate Q * according to the ratio r between the input voltage Vm of the inverter 14 given from the voltage sensor 13 and the set value. Similarly, the fan drive control unit 440 corrects the target air volume F * according to the ratio r between the input voltage Vm of the inverter 14 and the set value (step S24).

  The pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the target flow rate Q * corrected in step S24 matches the discharge amount, and outputs the signal PDR to the pump 60 (step S25).

  In addition, the fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the target air volume F * corrected in step S24 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S40). S26).

[Modification 3]
As described above, the cooling system according to the present invention estimates the loss generated in the inverter 14 when the motor is driven, and variably controls the discharge amount of the pump 60 and the cooling air supply amount of the fan 70 according to the estimated loss. The configuration is as follows.

  In such a configuration, the loss of the inverter 14 is estimated by estimating the loss that can occur in the inverter 14 from the required output of the motor (accelerator opening or torque command value and motor rotational speed) as described above. Compared with controlling the flow rate of the refrigerant according to the temperature rise of the inverter, the control response of the cooling capacity can be ensured.

  However, on the other hand, in order to prevent the cooling capacity from being insufficient when the actual loss exceeds the estimated loss, the loss is expected in consideration of the maximum value of the current that can pass through the inverter 14 at a certain required motor output. There is a need to estimate. Therefore, when the passing current of the inverter 14 is less than the maximum value, the cooling capacity becomes excessive, and the effect of the present invention of low power consumption may not be sufficiently enjoyed.

  Accordingly, the cooling system according to the present modification calculates the loss of the inverter 14 during motor drive control from the viewpoint of further power saving, and the discharge amount of the pump 60 and the cooling air supply amount of the fan 70 according to the calculation result. Is configured to be variably controlled. According to this, compared with the case where the loss of the inverter 14 is estimated from the required output of the motor, the refrigerant having a flow rate corresponding to the loss actually generated in the inverter 14 is always supplied to the refrigerant path. The power consumption of the system can be further reduced.

Specifically, pump drive control unit 430 calculates input power Pin and output power Pout of inverter 14 when AC motor M1 is driven. Referring to FIG. 13, control device 40 receives input voltage Vm of inverter 14 from voltage sensor 13 and receives input current Im of inverter 14 from current sensor 20. The pump drive control unit 430 in the control device 40 calculates the input power Pin of the inverter 14 by substituting these input signals into the equation (3).
Pin = Im × Vm (3)
Similarly, when the pump drive control unit 430 receives the interphase voltage Vvw between the V phase and the W phase of the AC motor M1 from the voltage sensor 18 and the V phase motor current Iv from the current sensor 24, the expression (4 ) To calculate the output power Pout of the inverter 14.
Pout = √3 · Vvw × Ivcosφ (4)
Here, cos φ is a power factor.

Next, the pump drive control unit 430 obtains the loss Ploss of the inverter 14 by substituting the calculated input power Pin and output power Pout into Expression (5).
Ploss = Pin−Pout (5)
Then, the pump drive control unit 430 sets the target flow rate Q * based on the obtained loss Ploss. At this time, the pump drive control unit 430 stores a map indicating the relationship between the loss Ploss and the target flow rate Q * in the storage area in advance, and extracts a flow rate corresponding to the calculated loss Ploss from the map. Set as target flow rate Q *.

  Similarly, in fan drive control unit 440, target air volume F * is set based on inverter loss Ploss obtained according to equations (3) to (5). The fan drive control unit 440 stores in advance a map indicating the relationship between the loss Ploss and the target air volume F * in the storage area, extracts the air volume corresponding to the calculated loss Ploss from the map, and extracts the target air volume F. Set as *.

  FIG. 14 is a flowchart for illustrating drive control of pump 60 and fan 70 according to the third modification of the first embodiment of the present invention.

  Referring to FIG. 14, pump drive control unit 430 (and fan drive control unit 440) receives input voltage Vm of inverter 14 from voltage sensor 13 and drives inverter 14 from current sensor 20 during the drive control of AC motor M <b> 1. When the input current Im is received (step S31), the input power Pin of the inverter 14 is calculated by the method described above based on these inputs (step S32).

  Further, when the pump drive control unit 430 (and the fan drive control unit 440) receives the interphase voltage Vvw from the voltage sensor 18 and the motor current Iv from the current sensor 24 (step S33), the pump drive control unit 430 (and fan drive control unit 440) described above based on these inputs. The output power Pout of the inverter 14 is calculated by the method (step S34). Then, the loss Ploss of the inverter 14 is calculated from the input power Pin and the output power Pout obtained in steps S32 and S34 (step S35).

  Next, the pump drive control unit 430 extracts the flow rate corresponding to the loss Ploss from the target flow rate setting map stored in advance in the storage area, and sets it as the target flow rate Q * (step S36). Further, the fan drive control unit 440 extracts the air volume corresponding to the loss Ploss from the target air volume setting map stored in advance in the storage area, and sets it as the target air volume F * (step S37).

  The pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the target flow rate Q * set in step S36 matches the discharge amount, and outputs the signal PDR to the pump 60 (step S38).

  Further, the fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the target air volume F * set in step S37 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S40). S39).

[Modification 4]
As a method of obtaining the loss of the inverter 14 more simply, a relationship between the current passing through the NPN transistors Q3 to Q8 of the inverter 14 and the loss of the inverter 14 is derived in advance, and the detected value of the passing current is determined according to the relationship. One method is to calculate the corresponding loss.

  Since this method can further adjust the cooling capacity to the loss of the inverter 14 in the same manner as the method of calculating the loss of the inverter 14 shown in the third modification, the power saving of the cooling system can be improved. It is effective in that

  Specifically, the pump drive control unit 430 and the fan drive control unit 440 set in advance a relationship between the output current (motor current) of the inverter 14 and the loss of the inverter 14 shown in FIG. Based on this, the loss of the inverter 14 is obtained.

  Here, even when the output current of the inverter 14 and the loss are the same (for example, the current value I1), the NPN transistors Q3 to Q8 of the inverter 14 are turned on / off. There is a relationship in which the loss generated varies depending on the switching frequency.

  Specifically, when the switching frequency is relatively high, for example, when the inverter 14 is in the PWM control mode, the switching loss that occurs during the switching operation increases, so that a relatively large loss is indicated as indicated by a point P10 in FIG. Will occur. On the other hand, when the switching frequency is relatively low, for example, when inverter 14 is in the rectangular wave control mode, the switching loss is suppressed, so that a relatively small loss occurs as shown by point P11 in FIG.

  Therefore, in FIG. 15, in order to absorb the variation in loss due to the switching frequency, the relationship between the output current and the loss is set based on the loss (corresponding to the point P10) when the switching frequency is the highest.

  Then, the pump drive control unit 430 presets the relationship between the output current of the inverter 14 and the target flow rate Q * based on the relationship between the output current of the inverter 14 and the loss of the inverter 14 obtained in FIG. The relationship is stored in the storage area as a target flow rate setting map.

  Similarly, for fan drive control unit 440, the relationship between the output current of inverter 14 and target air volume F * is set in advance based on the relationship between the output current of inverter 14 and the loss of inverter 14 shown in FIG. The relationship is stored in the storage area as a target air volume setting map.

  FIG. 16 is a diagram showing the relationship between the output current I1 of the inverter 14, the target flow rate Q *, and the target air volume F *.

  Referring to line LN4 in FIG. 16, target flow rate Q1 for an output current I1 is, for example, the loss of inverter 14 generated per unit time when current I1 flows through NPN transistors Q3-Q8 of inverter 14. On the other hand, the heat dissipation possible amount per unit time when the refrigerant corresponding to the target flow rate Q1 is circulated is set to be higher.

  Further, referring to line LN5 in FIG. 16, the target air volume F1 with respect to the output current I1 is the amount of heat radiated from the refrigerant to the cooling air (corresponding to the amount of heat output Q2 in FIG. 2), but the current I1 flows through the inverter 14. It is set so as to be substantially equal to the amount of heat that is generated by the refrigerant and is received by the refrigerant from the inverter 14 (the amount of heat input Q1 in FIG. 2).

  FIG. 17 is a flowchart for illustrating drive control of pump 60 and fan 70 according to the fourth modification of the first embodiment of the present invention.

  Referring to FIG. 17, when driving control of AC motor M1 is performed, pump drive control unit 430 receives a motor current from current sensor 24 (step S41), and a target flow rate setting map stored in advance in a storage area. The flow rate corresponding to the motor current given from (corresponding to the line LN4 in FIG. 16) is extracted and set as the target flow rate Q * (step S42).

  When the fan drive control unit 440 receives the motor current from the current sensor 24, the fan drive control unit 440 calculates the air volume corresponding to the motor current given from the target air volume setting map (corresponding to the line LN5 in FIG. 16) stored in the storage area in advance. Extracted and set as the target air volume F * (step S43).

  Then, the pump drive control unit 430 generates a signal PDR for driving the pump 60 so that the target flow rate Q * set in step S42 matches the discharge amount, and outputs the signal PDR to the pump 60 (step S44).

  Further, the fan drive control unit 440 generates a signal FDR for driving the fan 70 so that the target air volume F * set in step S43 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S43). S45).

[Embodiment 2]
FIG. 18 is a block diagram conceptually showing the cooling system according to the second embodiment of the present invention.

  Referring to FIG. 18, the cooling system includes a radiator 50, a refrigerant path 51, an inverter 14, an evaporator 54, a radiator 50, a pump 60, a gas-liquid separator 52, a fan 70, and a bypass valve. 56 and a bypass line 58. In the cooling system of FIG. 18, the refrigerant that has flowed through the refrigerant path 51 by the bypass valve 56 between the pump 60 and the evaporator 54 in the cooling system of FIG. It has been modified to be guided to at least one.

  The bypass valve 56 is provided on the downstream side of the pump 60 and includes a switching damper 561 and an actuator 560.

  The switching damper 561 has its valve opening amount controlled by an actuator 560 controlled by a signal DRV from the control device 40A. The actuator 560 controls the opening amount of the switching damper 561 in response to the signal DRV from the closed position where the flow of the refrigerant from the pump 60 to the evaporator 54 is blocked to all the refrigerant from the pump 60 to the evaporator 54. Control up to the open position allowing flow. Accordingly, at least a part of the refrigerant flowing through the refrigerant passage 51 circulates in the evaporator 54 according to the valve opening amount of the switching damper 561. At this time, the remaining part of the refrigerant flows through the bypass line 58 and is directly returned to the radiator 50 without passing through the evaporator 54.

  When the target flow rate Q * is set using any of the plurality of methods disclosed in the first embodiment, the control device 40A causes the refrigerant of the set target flow rate Q * to flow through the evaporator 54. The valve opening amount of the switching damper 561 is determined, and a signal DRV indicating the determined valve opening amount is generated and output to the actuator 560. Actuator 560 drives and controls switching damper 561 so that the valve opening amount is instructed by signal DRV. As a result, a refrigerant having a flow rate corresponding to the loss of the inverter 14 flows through the evaporator 54.

  As described above, in the cooling system according to the present embodiment, the evaporator is controlled by controlling the valve opening amount of the bypass valve 56 disposed on the upstream side of the evaporator 54 while keeping the flow rate of the entire refrigerant path constant. The flow rate of the refrigerant flowing through 54 is controlled.

  With such a configuration, when the required output of the AC motor M1 is relatively small, the flow rate of the refrigerant flowing through the evaporator 54 having a large flow resistance can be reduced, thereby reducing the pressure loss. be able to. As a result, power for driving the pump 60 can be suppressed, and power consumption can be reduced.

  FIG. 19 is a flowchart for illustrating drive control of bypass valve 56 according to the second embodiment of the present invention. In the flowchart of FIG. 19, the target flow rate Q * is set based on the accelerator opening ACC as described in the first embodiment.

  Referring to FIG. 19, when control device 40A receives accelerator opening ACC from the accelerator opening sensor (step S51), target flow rate setting map stored in the storage area in advance (corresponding to line LN1 in FIG. 7). The flow rate corresponding to the accelerator opening degree ACC given from is extracted and set as the target flow rate Q * (step S52).

  Then, the control device 40A determines the valve opening amount of the switching damper 561 so that the refrigerant flows through the evaporator 54 at the set target flow rate Q *, and outputs a signal DRV indicating the determined valve opening amount. Generated and output to the actuator 560 (step S53). Actuator 560 controls switching damper 561 in accordance with signal DRV from control device 40A. As a result, the refrigerant having a flow rate that matches the target flow rate Q * of the refrigerant flowing through the refrigerant path 51 flows through the evaporator 54.

  As described above, according to the second embodiment of the present invention, since the flow rate of the refrigerant flowing through the evaporator is variably controlled according to the loss of the inverter, the pressure loss generated in the refrigerant path can be reduced, and the cooling The power consumption of the system can be reduced. As a result, the fuel efficiency of a vehicle equipped with the cooling system according to the present invention can be improved.

[Embodiment 3]
Further, the cooling system according to the present invention may be configured as shown in FIG.

  FIG. 20 is a block diagram conceptually showing the cooling system according to the third embodiment of the present invention.

  Referring to FIG. 20, the cooling system depressurizes the compressor 62 that sucks and compresses the refrigerant, the condenser (heat radiator) 50B that condenses the refrigerant discharged from the compressor 62, and the refrigerant that flows out of the condenser 50B. It includes an expansion valve 63, an evaporator 54 that evaporates the refrigerant decompressed by the expansion valve 63 and cools the inverter 14, a refrigerant path 51, and a fan 70. In the cooling system according to the present embodiment, the compressor 62, the condenser 50B, the expansion valve 63, and the evaporator 54 constitute a vapor compression refrigeration cycle (hereinafter referred to as a refrigeration cycle).

  FIG. 21 is a state diagram (TS diagram) of the cooling system of FIG. Points 1 to 4 in the figure indicate refrigerant state points in the cooling system of FIG.

  Referring to FIG. 21, heat is exchanged by an isobaric isothermal change 1-2 and an isobaric change 3-4. Specifically, the isobaric isothermal change between points 1-2 indicates heat exchange between the inverter 14 and the refrigerant in the evaporator 54. At this time, the refrigerant receives from the inverter 14 a heat amount (heat input amount) Q1 indicated by an arrow in the figure.

  Moreover, the equal pressure change between points 3-4 has shown the heat exchange between the refrigerant | coolant and cooling air in the condenser 50B. At this time, the refrigerant radiates heat (heat output) Q2 indicated by an arrow in the drawing to the cooling air.

  By making the heat input amount Q1 and the heat output amount Q2 equal, each of the low-pressure side operating pressure P1 and the high-pressure side operating pressure P2 is kept substantially constant. That is, the operating temperatures T1 and T2 of the refrigerant can be kept substantially constant on each of the low pressure side and the high pressure side.

  In such a refrigeration cycle, the flow rate of the refrigerant circulating in the cycle can be performed, for example, by controlling the discharge amount of the compressor 62. Specifically, the amount of refrigerant discharged can be controlled by controlling the number of rotations of the motor by driving the compressor 62 using a motor.

  Therefore, in the present embodiment, in a cooling system constituted by a refrigeration cycle, a loss generated in the inverter 14 during drive control of the AC motor M1 is estimated, and the discharge amount of the compressor 62 is variable according to the estimated loss. The configuration is to be controlled.

  Specifically, when controller 40B estimates the loss of inverter 14 using any one of the plurality of methods disclosed in the first embodiment, the estimated loss may be covered by the latent heat of vaporization of the refrigerant. The target discharge amount P * of the compressor 62 is set so that it can be performed. Then, the rotational speed of the compressor 62 is controlled so that the set target discharge amount P * and the discharge amount coincide with each other.

  Furthermore, the control device 40B cools the fan 70 so that the amount of heat radiated from the refrigerant to the cooling air is equivalent to the estimated loss of the inverter 14 and substantially equal to the amount of heat received by the refrigerant from the inverter 14. Set the target air flow rate F *. And the rotation speed of the fan 70 is controlled so that the cooling air of the set target air volume F * is supplied to the condenser 50B.

  As an example, the control device 40B stores the relationship between the accelerator opening ACC, the target discharge amount P *, and the target air amount F * as shown in FIG. 22 in a storage area (not shown) as a target discharge amount (or target air amount) setting map. When the accelerator opening degree ACC is stored, the corresponding discharge amount (or air volume) is extracted from the map and set as the target discharge amount P * (or target air volume F *). .

  FIG. 22 is a diagram showing the relationship between the accelerator opening ACC, the target discharge amount P *, and the target air volume F *. The line LN6 in the figure shows the relationship between the accelerator opening ACC and the target discharge amount P *, and the line LN7 shows the relationship between the accelerator opening ACC and the target air volume F *.

  FIG. 23 is a flowchart for illustrating drive control of compressor 62 and fan 70 according to Embodiment 3 of the present invention.

  23, when control device 40B receives accelerator opening ACC from the accelerator opening sensor (step S61), control device 40B corresponds to a target discharge amount setting map (corresponding to line LN6 in FIG. 21) stored in advance in the storage area. ) Is extracted and set as a target discharge amount Q * (step S62).

  Further, the control device 40B extracts the air volume corresponding to the accelerator opening degree ACC given from the target air volume setting map (corresponding to the line LN7 in FIG. 21) stored in advance in the storage area, and sets it as the target air volume F *. (Step S63).

  Next, the control device 40B generates a signal CDR for controlling the number of revolutions of the compressor 62 so as to discharge the refrigerant at the target discharge amount Q * set in step S62, and outputs the signal CDR to the compressor 62 (step). S64).

  The control device 40B further generates a signal FDR for driving the fan 70 so that the target air volume F * set in step S63 matches the supply amount of cooling air, and outputs the signal FDR to the fan 70 (step S65).

  As described above, according to the third embodiment of the present invention, the flow rate of the refrigerant circulating in the refrigeration cycle is variably controlled based on the required output of the AC motor, thereby changing according to the operating state of the AC motor. A refrigerant having an appropriate flow rate can be supplied with good responsiveness to the loss of the inverter. Thereby, it is possible to realize power saving of the cooling system as compared with the conventional cooling system that drives the cooling system while fixing the cooling capacity required when the loss of the inverter 14 is maximized. As a result, the fuel consumption of the vehicle can be improved.

  In each of the above embodiments, the configuration for cooling inverter 14 has been described. However, the configuration may be such that power control unit 21 including inverter 14 and boost converter 12 is cooled.

  In each of the above embodiments, the case where the SiC power element is used as the switching element used in the inverter 14 has been described representatively. However, other power elements, for example, GaN-based power made of gallium nitride (GaN) are used. It may be an element or a diamond-based power element.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a cooling system for a load driving device mounted on a vehicle.

It is a block diagram which shows notionally the cooling system by Embodiment 1 of this invention. FIG. 2 is a state diagram of the cooling system of FIG. 1. It is a schematic block diagram of the motor drive device to which the cooling system of FIG. 1 is applied. It is sectional drawing for demonstrating the cooling structure of the NPN transistor which comprises an inverter. It is a functional block diagram of the control apparatus in FIG. It is a figure which shows the relationship between an accelerator opening and the loss of an inverter. It is a figure which shows the relationship between an accelerator opening, a target flow volume, and a target air volume. It is a flowchart for demonstrating drive control of the pump and fan by Embodiment 1 of this invention. It is a figure which shows the relationship between the output characteristic of an AC motor, and the loss of an inverter. It is a figure which shows the relationship between the output characteristic of an AC motor, and a target flow rate. It is a flowchart for demonstrating drive control of the pump and fan by the modification 1 of Embodiment 1 of this invention. It is a flowchart for demonstrating drive control of the pump and fan by the modification 2 of Embodiment 1 of this invention. It is a figure for demonstrating the calculation method of the loss of an inverter. It is a flowchart for demonstrating drive control of the pump and fan by the modification 3 of Embodiment 1 of this invention. It is a figure which shows the relationship between the output current of an inverter, and the loss of an inverter. It is a figure which shows the relationship between the output current of an inverter, target flow volume, and target air volume. It is a flowchart for demonstrating drive control of the pump and fan by the modification 4 of Embodiment 1 of this invention. It is a block diagram which shows notionally the cooling system by Embodiment 2 of this invention. It is a flowchart for demonstrating drive control of the bypass valve by Embodiment 2 of this invention. It is a block diagram which shows notionally the cooling system by Embodiment 3 of this invention. FIG. 21 is a state diagram of the cooling system of FIG. 20. It is a figure which shows the relationship between an accelerator opening, a target discharge amount, and a target air volume. It is a flowchart for demonstrating drive control of the compressor and fan by Embodiment 3 of this invention.

Explanation of symbols

  10, 13 Voltage sensor, 12 Boost converter, 13, 18 Voltage sensor, 14 Inverter, 15 U-phase arm, 16 V-phase arm, 17 W-phase arm, 20, 24 Current sensor, 30 Resolver, 40, 40A, 40B Control device , 50 Radiator, 50B Condenser, 52 Gas-liquid separator, 54 Evaporator, 56 Bypass valve, 560 Actuator, 561 Switching damper, 58 Bypass line, 60 Pump, 62 Compressor, 63 Expansion valve, 70 Fan, 80, 84 Solder, 82 Insulating substrate, 86 Heat sink, 88 Silicon grease, 90 Heat sink, 92,94 Plate, 96 Through hole, 400 Torque command calculation unit, 410 Current command conversion unit, 412,414 Subtractor, 416,418 PI Control unit, 420 2-phase / 3-phase conversion unit, 422 PWM generation Part, 424 three-phase / two-phase conversion part, 430 pump drive control part, 440 fan drive control part, 820,824 aluminum, 822 aluminum nitride, B battery, C2 capacitor, D1-D8 diode, L1 reactor, M1 AC motor, Q1-Q8 NPN transistor, WL wire.

Claims (16)

A drive circuit that performs power conversion between a power source and an electric load by a switching operation of the switching element;
A cooling device for receiving power from the power source and cooling the drive circuit;
A cooling control device for controlling the amount of cooling medium supplied to the drive circuit,
The cooling control device includes:
Power loss estimation means for estimating power loss generated in the drive circuit;
And a supply amount determining means for determining a supply amount of the cooling medium based on the estimated power loss. The power loss estimation means includes first loss estimation means for estimating the power loss from a required output for the electric load,
The supply amount determination means determines the supply amount of the cooling medium corresponding to the estimated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium. As described in the cooling system. The electric load is a rotating electric machine that generates a driving force of a vehicle,
A control device that generates a current command based on a required output for the rotating electrical machine determined from the accelerator opening of the vehicle, and controls the switching operation so that a driving current of the rotating electrical machine matches the current command. In addition,
The cooling system according to claim 2, wherein the first loss estimation means estimates the power loss based on the accelerator opening. The electric load is a rotating electric machine that generates a driving force of a vehicle,
A control device for controlling the switching operation so that the output of the rotating electrical machine matches the required output;
The first loss estimation means preliminarily sets a relationship between the output of the rotating electrical machine and the power loss, and estimates the power loss corresponding to the requested output based on the set relationship. 2. The cooling system according to 2. A voltage sensor for detecting an input voltage of the drive circuit;
The power loss estimation means further includes power loss correction means for correcting the power loss estimated by the first loss estimation means using the input voltage detected by the voltage sensor,
The said supply amount determination means determines the supply amount of the said cooling medium corresponding to the corrected said power loss based on the relationship between the said preset power loss and the supply amount of the said cooling medium. As described in the cooling system. The electric load is a rotating electric machine that generates a driving force of a vehicle,
A control device that generates a current command based on a required output for the rotating electrical machine, and controls the switching operation so that a driving current of the rotating electrical machine matches the current command;
A current sensor for detecting the drive current;
The power loss estimation means includes second loss estimation means for estimating the power loss from the drive current,
The second loss estimation means presets a relationship between the drive current and the power loss, and estimates the power loss corresponding to the detected drive current based on the set relationship.
The supply amount determination means determines the supply amount of the cooling medium corresponding to the estimated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium. As described in the cooling system. The power loss estimation means includes third loss estimation means for calculating the input power and the output power of the drive circuit, and calculating the power loss from the difference between the calculated input power and the output power,
The supply amount determining means determines the supply amount of the cooling medium corresponding to the calculated power loss based on a relationship between the preset power loss and the supply amount of the cooling medium. As described in the cooling system. The cooling device is
A refrigerant path through which the cooling medium flows;
A radiator disposed in the refrigerant path and configured to cool the cooling medium;
A pump that is rotationally driven in response to the supply of electric power from the power source and circulates the cooling medium in the refrigerant path,
The cooling system according to any one of claims 1 to 7, wherein the cooling control device controls a discharge amount of the pump according to the determined supply amount of the cooling medium. The cooling device is
A refrigerant path through which the cooling medium flows;
A radiator disposed in the refrigerant path and configured to cool the cooling medium;
A pump that is rotationally driven in response to the supply of electric power from the power source and circulates the cooling medium in the refrigerant path;
A flow rate control valve disposed in the refrigerant path between the pump and the drive circuit, for allowing at least a part of the cooling medium to flow through the drive circuit according to a valve opening amount;
The cooling system according to any one of claims 1 to 7, wherein the cooling control device controls the valve opening amount in accordance with the determined supply amount of the cooling medium. The cooling device is
A fan for supplying cooling air to the radiator;
The cooling system according to claim 8 or 9, wherein the cooling control device controls a supply amount of the cooling air based on the estimated power loss. The cooling device is
Including a refrigeration cycle configured with a compressor, a condenser, a decompressor, and an evaporator;
The cooling system according to any one of claims 1 to 7, wherein the cooling control device controls a discharge amount of the compressor according to the determined supply amount of the cooling medium. The cooling device further includes a fan for supplying cooling air to the condenser,
The cooling system according to claim 11, wherein the cooling control device controls the supply amount of the cooling air based on the estimated power loss. The cooling medium has a boiling point lower than the operating temperature of the switching element;
The cooling system according to any one of claims 1 to 12, wherein the cooling device collides the cooling medium with a cooling plate to which the switching element is fixed and cools the drive circuit by boiling.   The cooling system according to claim 13, wherein the switching element is a power element made of silicon carbide.   The cooling system according to claim 13, wherein the switching element is a gallium nitride power element.   A vehicle comprising the cooling system according to any one of claims 1 to 15.

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