Electrical circuit device

Abstract

There is a need for an electrical circuit device that can reduce costs while providing adequate thermal protection. [Solution] An electrical circuit device comprising N (where N is an integer of 2 or more) electronic components 4, a cooling unit for cooling the N electronic components, and N temperature detection units 2 provided corresponding to each of the N electronic components 4, each unit detecting the temperature of the corresponding electronic component 4, wherein the cooling unit includes a heat medium flow path 39 through which a heat medium flows, the N electronic components 4 are arranged so as to be lined up from the upstream side to the downstream side of the heat medium flow path 39, and the detection accuracy of the temperature detection unit 2 corresponding to the downstream electronic component 4a, which is the electronic component 4 located furthest downstream of the N temperature detection units 2, is configured to be higher than the detection accuracy of the temperature detection units 2 corresponding to the electronic components 4 other than the downstream electronic component 4a.

Description

Technical Field

[0001] The present invention relates to an electric circuit device.

Background Art

[0002] An example of such an electric circuit device is disclosed in Patent Document 1 below. In the following description of the background art, the reference numerals in Patent Document 1 are cited in parentheses.

[0003] The electric circuit device of Patent Document 1 includes a plurality of electronic components (power devices 1 to 6), thermistors (21 to 26), and temperature information transmission means (7). Each electronic component is provided with one thermistor (21 to 26). When current continues to flow through these electronic components, each electronic component generates heat. The temperature information transmission means (7) monitors the temperature of each electronic component detected by the thermistors (21 to 26). In this electric circuit device, when the detected maximum temperature reaches the limit temperature, thermal protection is provided for the electronic components by reducing the command current flowing through the electronic components.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an electric circuit device such as that of Patent Document 1, it is necessary to accurately detect the temperature of each electronic component. However, there is a problem that if high-precision temperature detection means is provided for all electronic components, the cost tends to increase.

[0006] Therefore, it is desired to realize an electric circuit device that can appropriately perform thermal protection while reducing costs.

Means for Solving the Problems

[0007] An electrical circuit device comprising N electronic components (where N is an integer of 2 or more), a cooling unit for cooling the N electronic components, and N temperature detection units provided corresponding to each of the N electronic components, each unit for detecting the temperature of the corresponding electronic component, The cooling unit is equipped with a heat transfer medium channel through which the heat transfer medium flows, The N electronic components are arranged so as to be aligned from the upstream side to the downstream side of the heat transfer fluid channel. The temperature detection units are configured such that the detection accuracy of the temperature detection unit corresponding to the downstream electronic component, which is the electronic component located furthest downstream among the N temperature detection units, is higher than the detection accuracy of the temperature detection units corresponding to the electronic components other than the downstream electronic component.

[0008] With this configuration, the detection accuracy of the temperature detection unit corresponding to the downstream electronic component, which is most likely to reach high temperatures, is made higher than the detection accuracy of the temperature detection units corresponding to other electronic components located further upstream. This allows for proper thermal protection of the downstream electronic component, and consequently, proper thermal protection of the entire electrical circuit device. Furthermore, this configuration allows for lower detection accuracy in the temperature detection unit corresponding to electronic components upstream of the downstream electronic components, thereby reducing the cost of the temperature detection unit and, consequently, the cost of the electrical circuit device. Thus, this configuration allows for cost reduction while providing adequate thermal protection.

[0009] Further features and advantages of the technology relating to this disclosure will become clearer from the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0010] [Figure 1] Skeleton diagram of a vehicle drive system [Figure 2]Schematic control block diagram of a rotating electric machine [Figure 3] Side view of the vehicle drive unit as seen from the second axial side. [Figure 4] Circuit diagram of the temperature detection unit [Figure 5] A schematic diagram showing a heat transfer fluid circuit. [Figure 6] A schematic exploded perspective view showing the arrangement of the cooling unit and electronic components. [Figure 7] A schematic plan view showing the arrangement of the heat transfer fluid channel and the temperature sensor. [Figure 8] A schematic plan view showing the arrangement relationship between the heat transfer fluid channel and the temperature sensor in another embodiment. [Figure 9] A schematic plan view showing the arrangement relationship between the heat transfer fluid channel and the temperature sensor in another embodiment. [Modes for carrying out the invention]

[0011] 1. Embodiment Hereinafter, an embodiment in which the electrical circuit device 1 is applied to a vehicle drive system 100 will be described with reference to the drawings. As shown in Figure 1, the vehicle drive system 100 includes a rotating electric machine MG equipped with a rotor 12, an output member driven and connected to a wheel W, and a power transmission mechanism GT that transmits driving force between the rotating electric machine MG and the output member. As will be described later, if the direction along the rotation axis A of the rotor 12 is defined as the axial direction L, the power transmission mechanism GT is positioned on the axial first side L1, which is one side of the axial direction L relative to the rotor 12. The rotating electric machine MG is the driving force source of the vehicle, and the power transmission mechanism GT includes a reduction gear 6 and a differential gear mechanism 5. Specifically, the vehicle drive unit 100 includes a rotating electric machine MG equipped with a rotor 12, a pair of output members each driven and connected to a wheel W, a reduction gear 6 that reduces the rotation of the rotor shaft 13, a differential gear mechanism 5 that distributes the driving force from the rotating electric machine MG transmitted to the differential input element (differential case 50) via the reduction gear 6 to the pair of output members, and a case 9 (Figure 3) that forms a housing chamber (second housing chamber E2, described later) that houses the rotating electric machine MG, the reduction gear 6, and the differential gear mechanism 5.

[0012] Here, "rotating electric machine" is used as a concept that includes motors, generators, and motor-generators that perform both motor and generator functions as needed. Furthermore, "drive connection" refers to a state in which two rotating elements are connected in a manner that can transmit driving force, and is used as a concept that includes a state in which the two rotating elements are connected so as to rotate as a whole, or a state in which the two rotating elements are connected in a manner that can transmit driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, chains, etc. Also, such transmission members may include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices.

[0013] The pair of wheels W includes a first wheel W1 and a second wheel W2, with the first wheel W1 being driven and connected to a first drive shaft DS1, and the second wheel W2 being driven and connected to a second drive shaft DS2. In this embodiment, the pair of side gears 52, which are the output gears of the differential gear mechanism 5, include a first side gear 53 and a second side gear 54. The first side gear 53 is driven and connected to the first drive shaft DS1 via a connecting shaft J, and the second side gear 54 is driven and connected to the second drive shaft DS2. For example, the first side gear 53 and the connecting shaft J are connected by a spline coupling, and the second side gear 54 and the second drive shaft DS2 are also connected by a spline coupling. These coupling parts are spline engagement parts 59. The output members are, for example, these spline engagement parts 59. Alternatively, the output members may be the first side gear 53, the second side gear 54, the first drive shaft DS1, the second drive shaft DS2, and the connecting shaft J.

[0014] In the following description, as described above, the direction along the rotation axis A of the rotor 12 is defined as the "axial direction L". One side of the axial direction L is defined as the "first axial side L1", and the other side of the axial direction L is defined as the "second axial side L2". In the present embodiment, the rotating electrical machine MG, the reduction gear 6, and the differential gear mechanism 5 are arranged coaxially with each other in the order described from the second axial side L2 toward the first axial side L1. The vehicle drive device 100 of the present embodiment has a single-axis configuration, and the axis (rotation axis A) on which the rotating electrical machine MG, the reduction gear 6, and the differential gear mechanism 5 are arranged is the rotation axis A of the vehicle drive device 100 and is also the rotation axis of the rotating electrical machine MG, the reduction gear 6, and the differential gear mechanism 5. Further, the direction orthogonal to the rotation axis A of the rotor 12 is defined as the "radial direction". In the radial direction, the side closer to the rotation axis A of the rotor 12 is defined as the "radial inner side", and the opposite side is defined as the "radial outer side". Further, in the vehicle-mounted state in which the vehicle drive device 100 is mounted on the vehicle, the direction along the vertical direction is defined as the "vertical direction Z", the upper side is defined as the "upper side Z1 of the vertical direction Z", and the lower side is defined as the "lower side Z2 of the vertical direction Z". When the vehicle drive device 100 is horizontally mounted on the vehicle, one direction within the radial direction coincides with the vertical direction Z. Further, the direction orthogonal to the axial direction L and the vertical direction Z is defined as the "front-rear direction H".

[0015] As shown in FIG. 2, the vehicle drive device 100 further includes an electric circuit device 1. In this example, the electric circuit device 1 is a device for driving and controlling the rotating electrical machine MG. Further, the vehicle drive device 100 includes a power module electrically connected to the vehicle-mounted battery BT and having a charging circuit for charging the vehicle-mounted battery BT from an external power source, and a case 9 for housing these devices. As shown in FIG. 3, the case 9 includes a first housing chamber E1 and a second housing chamber E2. In the first housing chamber E1, the electric circuit device 1 and the power module are housed. In the second housing chamber E2, the rotating electrical machine MG and the power transmission mechanism GT are housed.

[0016] The rotating electric machine MG functions as a driving force source for a pair of wheels W. As shown in FIG. 3, the rotating electric machine MG is electrically connected to an in-vehicle battery BT (a DC power source composed of a power storage device such as a secondary battery or a capacitor) via an electric circuit device 1. The rotating electric machine MG has a function as a motor (an electric motor) that generates power by receiving power supply from the in-vehicle battery BT, and a function as a generator (a power generator) that generates power by receiving power supply from the side of the wheels W. The rotating electric machine MG generates a driving force by traveling with the power stored in the in-vehicle battery BT, and generates power by the driving force transmitted from the side of the pair of wheels W to charge the in-vehicle battery BT. The in-vehicle battery BT is a high-voltage DC power source with a rated voltage of about 48 volts to 400 volts. The in-vehicle battery BT is configured to be chargeable not only by the power generated by the rotating electric machine MG, but also by the power supplied from an external power source such as a commercial power source with a rating of about 100 volts to 240 volts AC as described above.

[0017] As shown in FIG. 2, the rotating electric machine MG includes a stator 11 fixed to a case 9 and a rotor 12 connected to a rotor shaft 13 so as to rotate integrally with the rotor shaft 13. The rotating electric machine MG is an inner rotor type rotating electric machine, and the rotor 12 is disposed radially inside the stator 11. The rotating electric machine MG is a rotating field type rotating electric machine, and the stator 11 includes a stator core 11a and a stator coil 11b wound around the stator core 11a. Further, the rotor 12 includes a rotor core 12a and a permanent magnet (not shown) fixed to the rotor core 12a. The rotor shaft 13 is formed in a cylindrical shape coaxial with the rotor core 12a, and on the outer peripheral side of the first side L1 in the axial direction of the rotor shaft 13, a sun gear SG of a planetary gear mechanism constituting a speed reducer 6 is disposed so as to rotate integrally with the rotor shaft 13. As will be described later, the sun gear SG is an input element of the speed reducer 6.

[0018] As shown in Figures 2 to 5, the electrical circuit device 1 comprises N (where N is an integer of 2 or more) electronic components 4, a cooling unit 3 for cooling the N electronic components 4, and N temperature detection units 2, each corresponding to one of the N electronic components 4, for detecting the temperature of the corresponding electronic component 4. In this embodiment, the electrical circuit device 1 further comprises a rotating electric machine control unit 17 and a driver 18. The rotating electric machine MG is driven and controlled by the rotating electric machine control unit 17 based on a target torque of the rotating electric machine MG set according to a command from a higher-level control device, the vehicle control device (not shown). In this embodiment, the N electronic components 4 (power modules PM) are used for the same purpose. The heat generated by each of the N electronic components 4 is equivalent to that of the others. Here, the N electronic components 4 are used to supply current to the stator coils 11b of each phase. The N electronic components 4 are basically controlled so that an alternating current of the same amplitude and frequency flows through the stator coils 11b of each phase. Therefore, the amount of heat generated by each of the N electronic components 4 is equivalent to that of the others.

[0019] Electronic component 4 is a power module PM equipped with at least one switching element 41. The electrical circuit device 1 is an inverter module INV equipped with multiple (here, N=3) such electronic components 4 as power module PMs equipped with switching elements 41. These power module PMs as a whole function as an inverter circuit. That is, the rotating electric machine control unit 17 switches and controls the inverter circuit (multiple power module PMs) equipped with multiple switching elements 41 to convert power between DC and multi-phase (here, 3-phase) AC in the inverter circuit. The operating voltage of the rotating electric machine control unit 17 is approximately 3.3 volts to 5 volts, the input / output voltage of the inverter circuit is approximately 48 volts to 400 volts, and the voltage of the switching control signal of the switching element 41 constituting the inverter circuit is approximately 15 volts to 24 volts. For this reason, a driver 18 is provided between the rotating electric machine control unit 17 and the inverter circuit to amplify the voltage of the switching control signal output from the rotating electric machine control unit 17, thereby increasing the driving force and supplying it to the inverter circuit.

[0020] Each power module PM is equipped with an AC single-phase arm, which consists of a series circuit of an upper switching element on the DC positive side and a switching element 41 on the negative side. Each switching element 41 is equipped with a freewheeling diode, with the forward direction being from the negative to the positive side (from the lower side to the upper side). It is preferable to use power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), SiC-MOSFETs (Silicon Carbide - Metal Oxide Semiconductor FETs), SiC-SITs (SiC - Static Induction Transistors), and GaN-MOSFETs (Gallium Nitride - MOSFETs) as the switching elements 41. In this example, multiple (three in this case) power modules PMs have switching elements 41 integrated together with freewheeling diodes.

[0021] When the rotating electric machine MG is driven, a large current flows through the switching elements 41 located in each power module PM, causing the switching elements 41 to generate heat. Consequently, the amount of heat generated by multiple power modules PM (inverter circuits) each containing multiple switching elements 41 becomes significant. Therefore, in this embodiment, as shown in Figures 3 and 5, a cooling unit 3 for cooling the switching elements 41 and multiple temperature detection units 2 corresponding to multiple power modules PM are provided.

[0022] The electrical circuit device 1 (in this case, the inverter module INV) may not include the rotating electric motor control unit 17 and the driver 18. Also, as shown in Figure 2, a DC link capacitor 16 (smoothing capacitor) is provided on the DC side of the multiple power modules PM, that is, between these power modules PM and the vehicle battery BT. The DC link capacitor 16 smooths the voltage on the DC side of the multiple power modules PM. The inverter module INV may include the DC link capacitor 16.

[0023] The rotating electric machine control unit 17 drives and controls the rotating electric machine MG via the inverter circuit by performing current feedback control based on the rotational position of the rotor 12 (the magnetic pole position of the permanent magnet), the rotational speed of the rotor 12, and the current flowing through the stator coils 11b of each of the three phases. The current flowing through the stator coils 11b is detected by a current sensor 15. The current sensor 15 is preferably a non-contact type current sensor installed near a power line, such as a busbar connecting the inverter circuit and the stator coils 11b of the rotating electric machine MG, as shown in Figure 2.

[0024] As shown in Figure 2, the reducer 6 is configured as a planetary gear mechanism comprising an input element that rotates integrally with the rotor shaft 13, a fixed element fixed to the case 9, an output element that rotates integrally with the differential input element (differential case 50), and planetary gears. This planetary gear mechanism is a composite type planetary gear mechanism comprising one sun gear SG, two ring gears (first ring gear RG1, second ring gear RG2), two planetary gears that rotate integrally (first planetary gear PG1, second planetary gear PG2), and a carrier CR that rotatably supports the two planetary gears. In this embodiment, the first planetary gear PG1 is formed to have a smaller diameter than the second planetary gear PG2.

[0025] The sun gear SG rotates integrally with the rotor 12 and rotor shaft 13. The second ring gear RG2 is fixed to the case 9. The first ring gear RG1 is positioned axially on the first side L1 relative to the second ring gear RG2 and is connected to the differential case 50 so as to rotate integrally with the differential case 50. The second planetary gear PG2 meshes with the sun gear SG and the second ring gear RG2, and the first planetary gear PG1 rotates integrally with the second planetary gear PG2 and also meshes with the first ring gear RG1. In this embodiment, the sun gear SG is the input element, the second ring gear RG2 is the fixed element, and the first ring gear RG1 is the output element. The carrier CR is not connected to any of the rotating or fixed elements.

[0026] The differential gear mechanism 5 is a bevel gear type differential gear mechanism, and each includes a bevel gear pinion gear 51 and side gears 52. The pinion gear 51 is supported by a pinion shaft 55 which is supported by the differential case 50 and is arranged to extend radially. The pinion shaft 55 rotates integrally with the differential case 50, and the pinion gear 51 is configured to rotate freely (rotate) around the pinion shaft 55 and to rotate freely (revolve) around the rotation axis A of the differential case 50. Multiple pinion shafts 55 are arranged radially (for example, in a cross shape) around the rotation axis A of the differential case 50, and a pinion gear 51 is attached to each of the multiple pinion shafts 55. The differential case 50 houses the pinion gear 51, side gears 52, and pinion shafts 55 inside.

[0027] The side gear 52 comprises a first side gear 53 and a second side gear 54, arranged as a pair spaced apart in the axial direction L. The first side gear 53 and the second side gear 54 mesh with each of the multiple pinion gears 51 and are arranged to rotate about the rotation axis A of the differential case 50. As shown in Figure 2, the first side gear 53 is connected to a connecting shaft J that extends along the axial direction L through the radially inward side of the reduction gear 6 and the hollow cylindrical rotor shaft 13. The connecting shaft J is connected to a first drive shaft DS1 which is driven to the first wheel W1, which is the wheel W on the axial second side L2, so as to rotate integrally with it. Therefore, the first side gear 53 is driven to the first wheel W1 via the connecting shaft J. The second side gear 54 is connected to a second drive shaft DS2 which is driven to the second wheel W2, which is the wheel W on the axial first side L1, so as to rotate integrally with it.

[0028] The first drive shaft DS1, the second drive shaft DS2, the connecting shaft J, the first side gear 53, and the second side gear 54, which are driven and connected to the wheel W and rotate integrally with the wheel W, can all be considered rotating members corresponding to output members. The first side gear 53 and the second side gear 54 can be considered both the differential gear mechanism 5 and the output members. The first side gear 53 and the second side gear 54 each have a gear portion that meshes with the pinion gear 51 and a spline engagement portion 59 that is connected to the connecting shaft J and the second drive shaft DS2, respectively. When considered functionally separately, the gear portion corresponds to the rotating member included in the differential gear mechanism 5, and the spline engagement portion 59 corresponds to the output member.

[0029] The cooling unit 3 is equipped with a heat transfer medium passage 39 through which a heat transfer medium flows. In this embodiment, a refrigerant (in this case, cooling water) flows through the heat transfer medium passage 39. As described above, the cooling unit 3 cools the switching elements 41 of multiple power modules PM. For this reason, the heat transfer medium passage 39 through which the cooling water flows is arranged to correspond to each of the multiple power modules PM. Here, the vehicle drive unit 100 is equipped with a cooling water circuit 30 that circulates the cooling water. As shown in Figure 5, a radiator 37 (on-board radiator) and a water pump (not shown) are connected to the cooling water circuit 30. Such a cooling water circuit 30 includes a water channel formed in the case 9. A three-way valve may also be connected to the cooling water circuit 30. The cooling water cooled (heat dissipated) by the radiator 37 is sent to the cooling water circuit 30 by the water pump, absorbs heat from the electrical circuit device 1 (inverter module INV) in the cooling unit 3, and returns to the radiator 37 as waste heat. The heat transfer medium may be something other than cooling water; for example, it is preferably a gas such as cooling oil, air conditioner refrigerant, or air.

[0030] The cooling unit 3 comprises a cooler 31 that forms a heat transfer fluid channel 39 inside, and a heat dissipation member 32. The cooler 31 is positioned to correspond to the inverter module INV. The cooler 31 is also connected to the cooling water circuit 30 described above. Therefore, cooling water circulating in the cooling water circuit 30 flows through the heat transfer fluid channel 39 inside the cooler 31. As shown in Figure 3, the cooling unit 3 is positioned below Z2 in the vertical direction Z relative to the inverter module INV housed in the first housing chamber E1 of the case 9. More specifically, the cooler 31 has an internal space that forms a heat transfer fluid channel 39 inside. The cooler 31 also has an inlet 34 through which cooling water enters the heat transfer fluid channel 39 and an outlet 35 through which the cooling water exits. In the example in Figure 6, the top of the cooler 31 is open upwards, and a heat dissipation member 32 is attached to cover the opening. Examples of the heat dissipation member 32 include a sheet coated with thermal grease or a heat sink. N (here, N=3) electronic components 4 (power modules PM) are placed on the heat dissipation member 32. In this way, the multiple power modules PM are arranged so as to be in contact with the cooling unit 3 (here, the heat dissipation member 32). The heat dissipation member 32 may be a heat sink plate as shown in Figures 6 and 7, or it may be a three-dimensionally formed member such as a heat sink.

[0031] As shown in Figures 6 to 9, the N electronic components 4 are arranged so as to be aligned from the upstream side to the downstream side of the heat transfer fluid channel 39. In the following description, the direction in which the cooling water flows through the heat transfer fluid channel 39 will be referred to as the direction of movement X, the upstream side of the direction of movement X will be referred to as the upstream side of the direction of movement X1, and the downstream side of the direction of movement X will be referred to as the downstream side of the direction of movement X2. The direction perpendicular to the direction of movement X will be referred to as the width direction Y. In this embodiment, the width direction Y is perpendicular to the direction of movement X and the vertical direction Z. As shown in Figure 7, the multiple power modules PM are arranged in order from the upstream side of the direction of movement X1 (upstream side) to the downstream side of the direction of movement X2 (downstream side). The inlet 34 is formed on the surface of the cooler 31 facing the upstream side of the direction of movement X1, and the outlet 35 is formed on the surface of the cooler 31 facing the downstream side of the direction of movement X2. In the example in Figure 7, the inlet 34 and the outlet 35 are arranged to be spaced apart in the width direction Y. The heat transfer fluid channel 39 is formed throughout the entire internal space of the box-shaped cooler 31.

[0032] The temperature detection unit 2 includes a temperature detection circuit 20, which includes a temperature sensor 21. Multiple temperature detection units 2 are arranged to correspond to each of the multiple power modules PM. As shown in Figure 4, the temperature detection circuit 20 includes a temperature sensor 21 equipped with a thermistor and a pull-up resistor 22 connected in series with the temperature sensor 21. In this embodiment, the temperature sensor 21 is built into each electronic component 4 (power module PM) and is mounted, for example, on the circuit board of the power module PM. Here, the resistance value of the temperature sensor 21 (thermistor) is output to the rotating electric machine control unit 17. The rotating electric machine control unit 17 then calculates the temperature based on the resistance value. The pull-up resistor 22 is provided, for example, on the circuit board on which the driver 18 is located or on the control circuit board on which the rotating electric machine control unit 17 is located. Note that a pull-down resistor may be connected instead of the pull-up resistor 22.

[0033] As shown in Figure 7, the N power modules PM are arranged along the heat transfer fluid channel 39 and are lined up sequentially from the upstream side X1 in the direction of movement to the downstream side X2 in the direction of movement. In such an example, the electronic component 4 located furthest upstream (the power module PM located at the furthest upstream side X1 in the direction of movement) tends to be cooler than the electronic components 4 located further downstream because it exchanges more thermal energy with the cooling water compared to the other electronic components 4. On the other hand, the downstream electronic component 4a (the power module PM located at the furthest downstream side X2 in the direction of movement) tends to be hotter than the electronic components 4 located further upstream. Generally, when it is detected that the temperature of a power module PM is above a predetermined temperature, the rotating electric machine control unit 17 performs control such as reducing the torque of the rotating electric machine NG to prevent malfunctions in the inverter module INV, rotating electric machine MG, etc. In the case where multiple power modules PM are provided, as in this example, when it is detected that the highest temperature among the power modules PM is above a predetermined temperature, the above-described control is performed. Therefore, when multiple electronic components 4 are arranged in a line from upstream to downstream, it is conceivable that the temperature of the downstream electronic component 4a, which is most likely to reach the highest temperature, can be detected with high precision, while the temperature detection precision for the electronic components 4 further upstream can be reduced. This approach aims to reduce costs while providing appropriate thermal protection.

[0034] Therefore, among the N temperature detection units 2, the detection accuracy of the temperature detection unit 2 corresponding to the downstream electronic component 4a is configured to be higher than the detection accuracy of the temperature detection units 2 corresponding to electronic components 4 other than the downstream electronic component 4a. In this embodiment, the temperature detection circuit 20 corresponding to the downstream electronic component 4a is configured using a circuit element 2a (in this example, a pull-up resistor 22) with higher accuracy than the temperature detection circuits 20 corresponding to electronic components 4 other than the downstream electronic component 4a. In this example, the temperature sensors 21 (thermistors) built into each electronic component 4 (power module PM) are of roughly the same accuracy. On the other hand, the pull-up resistor 22 as a circuit element 2a corresponding to the power module PM located at the downstream end has higher accuracy than the pull-up resistor 22 corresponding to the power module PM located further upstream. The accuracy of the pull-up resistor 22 can be determined, for example, by the range of resistance error. Specifically, a pull-up resistor 22 with a small absolute resistance error (for example, a resistance error of ±0.5%) can be said to be more accurate than a pull-up resistor 22 with a larger absolute resistance error (for example, a resistance error of ±5%). Furthermore, using a pull-up resistor 22 with a small resistance error makes the temperature detection circuit 20 less susceptible to noise and surges, and makes it easier to detect a stable temperature value compared to when the resistance error of the pull-up resistor 22 is large.

[0035] Furthermore, the temperature sensor 21 of the power module PM located at the furthest downstream can be made more accurate than the temperature sensors 21 of the power modules PM located further upstream, while the accuracy (resistance error) of all pull-up resistors 22 can be made to be of the same degree. In this case, for example, the temperature sensor 21 of the furthest downstream power module PM can be made more temperature sensitive than the other temperature sensors 21. By creating a difference in the level of temperature sensitivity in this way, it is possible to reduce costs while appropriately performing thermal protection. For example, in the rotating electric machine control unit 17 or a control device higher than it, a temperature threshold (first threshold) for controlling the reduction of the torque of the rotating electric machine MG and a temperature threshold (second threshold) for controlling the interruption of power supply to the rotating electric machine MG are set. The second threshold is set higher than the first threshold. The first threshold for reducing the torque of the rotating electric machine MG is applied to the temperature sensor 21 built into the furthest downstream power module PM. The second threshold for controlling the interruption of power supply to the rotating electric machine MG is applied to the temperature sensors 21 built into all power modules PM. This allows for highly accurate temperature detection of the downstream power module PM, which is most prone to high temperatures, and reduces the torque of the rotating electric machine MG if the detected temperature exceeds the first threshold. Furthermore, if an abnormal temperature exceeding the second threshold is detected in at least one power module PM, the power supply to the rotating electric machine MG is shut off. In this way, it is preferable to set multiple thresholds to provide appropriate thermal protection. Note that the configuration of the control when each threshold is exceeded can be changed as appropriate.

[0036] Furthermore, in this embodiment, the temperature sensor 21 of the temperature detection unit 2 corresponding to the downstream electronic component 4a is positioned at the location in the downstream electronic component 4a where the efficiency of heat exchange with the heat transfer medium is the worst. Also, the temperature sensor 21 of the temperature detection unit 2 corresponding to the downstream electronic component 4a is positioned at the location of the downstream electronic component 4a where the temperature is highest. Locations where the efficiency of heat exchange with the heat transfer medium is the worst include locations in the heat transfer medium flow path 39 where the flow of the heat transfer medium (in this case, cooling water) tends to stagnate, and locations far from the heat dissipation member 32. These locations are preferably determined experimentally or empirically. Also, locations of the downstream electronic component 4a where the temperature is highest include locations where the power module PM is hottest when in use. These locations are preferably determined experimentally. In the example in Figure 7, the outlet 35 of the heat transfer medium flow path 39 is located at one end in the width direction Y. Therefore, in the downstream power module PM, the region that overlaps with the downstream end X2 of the heat transfer medium flow path 39 in the direction of movement and the other end in the width direction Y relative to the outlet 35, when viewed in the vertical direction, is the location with the least efficient heat exchange, or in other words, the location that is prone to becoming hot. Accordingly, the temperature sensor 21 is mounted at this location in the power module PM. Furthermore, in the example in Figure 7, the power module PM upstream of the downstream power module PM is positioned on the other side of the central region in the width direction Y (the side where the inlet 34 is located in the width direction Y), where cooling water is considered to flow relatively easily. However, it may also be positioned on one side of the central region in the width direction Y (the side where the outlet 35 is located in the width direction Y).

[0037] In the example shown in Figure 9, the inlet 34 and outlet 35 are located in the central region in the width direction Y. In such an example, the cooling water tends to accumulate relatively easily on the side of the heat transfer fluid flow path 39 that is not in the central region in the width direction Y. For this reason, the temperature sensor 21 for the downstream power module PM is located in a region to one side of the central region in the width direction Y. For the other power modules PM, the temperature sensor 21 is located in a region to one or the other side of the central region in the width direction Y, but it may also be located in the central region in the width direction Y where the cooling water flows more easily.

[0038] In the example shown in Figure 8, a pipe 38 forming a heat transfer fluid channel 39 is provided inside the cooler 31. The pipe 38 connects an inlet 34 and an outlet 35 and is arranged in a meandering manner. In such an example, the temperature in the power module PM tends to be higher in areas where the pipe 38 is not located. Therefore, in the downstream power module PM, the temperature sensor 21 is located in an area that does not overlap with the pipe 38 in a vertical view. The temperature sensors 21 are located in similar areas in the other power module PMs, but they may also be located so as to overlap with the pipe 38 in a vertical view. Even when the heat transfer fluid channel 39 is meandering in this way, each power module PM does not need to be located along the meandering channel; for example, they only need to be located along the direction of movement X (here, the direction in which the cooling water flows as a whole in the cooling unit 3, and the longitudinal direction of the cooler 31). Naturally, the heat transfer fluid channel 39 may be formed according to the position of the temperature sensors 21 installed in the downstream power module PM and the power module PMs upstream of it. In that case, it is preferable to form the heat transfer fluid channel 39 so that the temperature rises in line with the position of the temperature sensor 21 of the downstream power module PM.

[0039] 2. Other Embodiments (1) In the above embodiment, a configuration was described as in which all power modules PM provided by the electrical circuit device 1 are arranged in a line from the upstream side to the downstream side of the heat medium flow path 39, but the invention is not limited to this configuration. For example, N (where N is an integer of 2 or more) of all power modules PM provided by the electrical circuit device 1 may be arranged in a line from the upstream side to the downstream side of the heat medium flow path 39. Alternatively, multiple heat medium flow paths 39 may be provided as illustrated in Figures 7 to 9, and multiple power modules PM may be arranged corresponding to each of the heat medium flow paths 39.

[0040] (2) In the above embodiment, the temperature sensor 21 of the temperature detection unit 2 corresponding to the downstream electronic component 4a was described as being placed at the location in the downstream electronic component 4a where the efficiency of heat exchange with the heat medium is the worst, but the embodiment is not limited to this. The temperature sensor 21 corresponding to the downstream electronic component 4a may be placed at a location other than the location in the downstream electronic component 4a where the efficiency of heat exchange with the heat medium is the best. Alternatively, it may be placed at the location that is easiest to install, regardless of the efficiency of heat exchange with the heat medium in the downstream electronic component 4a.

[0041] (3) In the above embodiment, the temperature sensor 21 of the temperature detection unit 2 corresponding to the downstream electronic component 4a was described as being placed at the hottest point of the downstream electronic component 4a, but the embodiment is not limited to this. The temperature sensor 21 corresponding to the downstream electronic component 4a may be placed at a location other than the coldest point of the downstream electronic component 4a as appropriate. Alternatively, it may be placed at the location that is easiest to install, regardless of the temperature of the downstream electronic component 4a.

[0042] (4) In the above embodiment, the temperature sensor 21 was described as being built into the corresponding power module PM as an example, but the invention is not limited to this. The temperature sensor 21 may be located outside the power module PM, for example, between the power module PM and the heat dissipation member 32. Alternatively, the invention may have a configuration in which both a temperature sensor 21 built into the power module PM and a power module PM located outside the power module PM are provided.

[0043] (5) In the above embodiment, the configuration in which the electronic component 4 is a power module PM equipped with at least one switching element 41 was described as an example, but the invention is not limited to this. For example, if a driver 18 is provided separately for each of the multiple power modules PM, each of the drivers 18 may be an electronic component 4. Also, the electronic component 4 may be a component that does not have a switching element. For example, the electronic component 4 may be a component equipped with a diode element such as a light-emitting diode, or it may be a component equipped only with a resistive element.

[0044] (6) The configurations disclosed in each of the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate without departing from the spirit of this disclosure.

[0045] 3. Summary of this embodiment The following describes the outline of the electrical circuit device (1) described above.

[0046] An electrical circuit device (1) comprising N electronic components (4) (where N is an integer of 2 or more), a cooling unit (3) for cooling the N electronic components (4), and N temperature detection units (2) provided corresponding to each of the N electronic components (4), each unit for detecting the temperature of the corresponding electronic component (4), The cooling unit (3) is equipped with a heat transfer medium channel (39) through which the heat transfer medium flows. The N electronic components (4) are arranged so as to be aligned from the upstream side to the downstream side of the heat transfer fluid channel (39). The temperature detection units (2) are configured such that the detection accuracy of the temperature detection unit (2) corresponding to the downstream electronic component (4a), which is the electronic component (4) located furthest downstream among the N temperature detection units (2), is higher than the detection accuracy of the temperature detection units (2) corresponding to the electronic components (4) other than the downstream electronic component (4a).

[0047] With this configuration, the detection accuracy of the temperature detection unit (2) corresponding to the downstream electronic component (4a), which is most likely to reach high temperatures, is made higher than the detection accuracy of the temperature detection units (2) corresponding to the other electronic components (4) located further upstream. This allows for proper thermal protection of the downstream electronic component (4a), and consequently, proper thermal protection of the entire electrical circuit device (1). Furthermore, with this configuration, the detection accuracy of the temperature detection unit (2) corresponding to the electronic component (4) upstream of the downstream electronic component (4a) can be kept low, thereby reducing the cost of the temperature detection unit (2), and consequently, the cost of the electrical circuit device (1) can be reduced. Thus, this configuration allows for cost reduction while providing adequate thermal protection.

[0048] The temperature sensor (21) of the temperature detection unit (2), which corresponds to the downstream electronic component (4a), is positioned at the location in the downstream electronic component (4a) where the efficiency of heat exchange with the heat transfer medium is the worst.

[0049] With this configuration, the temperature of the part of the downstream electronic component (4a) that is most likely to become hot can be detected with high accuracy, so that the thermal protection of the downstream electronic component (4a) can be performed more appropriately, and consequently, the thermal protection of the entire electrical circuit device (1) can be performed appropriately.

[0050] The temperature sensor (21) of the temperature detection unit (2), which corresponds to the downstream electronic component (4a), is positioned at the point on the downstream electronic component (4a) that becomes the hottest.

[0051] With this configuration, the temperature of the point with the highest temperature among the downstream electronic components (4a) can be detected with high accuracy, so that the thermal protection of the downstream electronic components (4a) can be performed more appropriately, and consequently, the thermal protection of the entire electrical circuit device (1) can be performed appropriately.

[0052] The temperature detection unit (2) includes a temperature detection circuit (20) which includes a temperature sensor (21). The temperature detection circuit (20) corresponding to the downstream electronic component (4a) is configured using a circuit element (3a) that has higher accuracy than the temperature detection circuit (20) corresponding to the electronic component (4) other than the downstream electronic component (4a).

[0053] With this configuration, by using a high-precision circuit element (3a) in the temperature detection circuit (20) corresponding to the downstream electronic component (4a), the thermal protection of the downstream electronic component (4a) can be properly performed, and consequently, the thermal protection of the entire electrical circuit device (1) can be properly performed. Furthermore, by using a less precise circuit element (3a) in the temperature detection circuit (20) corresponding to the electronic component (4) upstream of the downstream electronic component (4a), the cost of the electrical circuit device (1) can be reduced. [Industrial applicability]

[0054] The technology disclosed herein can be used in electrical circuit devices. [Explanation of Symbols]

[0055] 1: Electrical circuit device, 2: Temperature detection unit, 2a: Circuit element, 3: Cooling unit, 4: Electronic component, 4a: Downstream electronic component, 20: Temperature detection circuit, 21: Temperature sensor, 39: Heat transfer fluid flow path, 41: Switching element

Claims

1. An electrical circuit device comprising N electronic components (where N is an integer of 2 or more), a cooling unit for cooling the N electronic components, and N temperature detection units provided corresponding to each of the N electronic components, each unit for detecting the temperature of the corresponding electronic component, The cooling unit is equipped with a heat transfer medium channel through which the heat transfer medium flows, The N electronic components are arranged so as to be aligned from the upstream side to the downstream side of the heat transfer fluid channel. An electrical circuit device configured such that the detection accuracy of the temperature detection unit corresponding to the downstream electronic component, which is the electronic component located furthest downstream among the N temperature detection units, is higher than the detection accuracy of the temperature detection units corresponding to the electronic components other than the downstream electronic component.

2. The electrical circuit device according to claim 1, wherein the temperature sensor of the temperature detection unit corresponding to the downstream electronic component is placed at the location in the downstream electronic component where the efficiency of heat exchange with the heat transfer medium is the worst.

3. The electrical circuit device according to claim 1, wherein the temperature sensor of the temperature detection unit corresponding to the downstream electronic component is placed at the location of the downstream electronic component that becomes hottest.

4. The temperature detection unit includes a temperature detection circuit that includes a temperature sensor. The electrical circuit device according to any one of claims 1 to 3, wherein the temperature detection circuit corresponding to the downstream electronic component is configured using circuit elements that have higher accuracy than the temperature detection circuit corresponding to the electronic component other than the downstream electronic component.

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