control device

Abstract

This invention provides a control device that can estimate the internal temperature of a junction box with high accuracy without requiring a temperature sensor to be installed inside the junction box. [Solution] The control device manages the battery pack, which includes the battery and junction box. The battery is configured to exchange power with the outside of the battery pack via the junction box. The control device is configured to estimate the internal temperature of the junction box using the current flowing through the junction box, the external temperature of the battery pack, and the temperature of the heat transfer medium. The heat transfer medium transfers the heat emitted from the junction box to the outside of the battery pack.

Description

Technical Field

[0001] The present disclosure relates to a control device for managing electrical components.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-044983 (Patent Document 1) discloses a technique for estimating the temperature of an AC cable provided in a motor room using the temperature around the AC cable in the motor room and the phase current flowing through the AC cable. A peripheral temperature sensor and a phase current sensor are provided in the motor room.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even if the above technique can be applied to estimating the temperature of components (AC cables) in the motor room, it cannot necessarily be applied to estimating the temperature of a junction box (J / B) connected to the in-vehicle battery. For example, since high-voltage power is supplied from the in-vehicle battery to the junction box, there are technical difficulties in providing a temperature sensor inside the junction box. Also, from a cost perspective, it is desirable to omit the temperature sensor.

[0005] It is also conceivable to estimate the temperature (internal temperature) inside the junction box from the detection value of a temperature sensor provided outside the junction box. However, it is difficult to accurately estimate the internal temperature of the junction box by a method of estimating the internal temperature of the junction box only from the detection value of a temperature sensor provided outside the junction box.

[0006] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a control device that can estimate the internal temperature of a junction box with high accuracy without installing a temperature sensor inside the junction box. [Means for solving the problem]

[0007] According to one embodiment of the present disclosure, the following control device is provided. The control device manages a battery pack including a battery and a junction box. The battery is configured to exchange power with the outside of the battery pack via the junction box. The control device is configured to estimate the internal temperature of the junction box using the current flowing through the junction box, the external temperature of the battery pack, and the temperature of a heat transfer medium. The heat transfer medium transfers heat emitted from the junction box to the outside of the battery pack. [Effects of the Invention]

[0008] According to this disclosure, it becomes possible to provide a control device that can estimate the internal temperature of a junction box with high accuracy without having to install a temperature sensor inside the junction box. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the schematic configuration of a vehicle according to an embodiment of the present disclosure. [Figure 2] This figure shows the internal configuration of the battery pack shown in Figure 1. [Figure 3] This is a flowchart showing the J / B internal temperature estimation method according to this embodiment. [Figure 4] This flowchart shows the pump control method according to this embodiment. [Figure 5] This is a time chart showing the change in the internal temperature of the J / B according to this embodiment. [Figure 6] This flowchart shows the charge and discharge control of the battery according to this embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. In each drawing, the orientation of the three mutually orthogonal axes (X-axis, Y-axis, and Z-axis) is indicated by a "+" sign in the direction pointed to by the arrow, and a "-" sign in the opposite direction.

[0011] Figure 1 shows the configuration of a vehicle equipped with the control device according to this embodiment. In Figure 1, the vertical and longitudinal directions are shown as being orthogonal to each other. "Forward" corresponds to the direction of travel of the vehicle, and "rearward" is the opposite direction. "Down" corresponds to the vertical direction (direction of gravity), and "up" is the opposite direction.

[0012] Referring to Figure 1, the vehicle 1000 includes a battery pack 100, which includes batteries and a junction box. The battery pack 100 is fixed, for example, under the floor of the vehicle 1000 (such as the underside of the floor panel). However, the mounting configuration of the battery pack 100 is arbitrary. For example, the case of the battery pack 100 may constitute part of the vehicle body (e.g., the floor panel). The internal configuration of the battery pack 100 will be described later (see Figure 2).

[0013] The vehicle 1000 further includes an ECU (Electronic Control Unit) 500 that manages the battery pack 100. The ECU 500 includes a processor and a memory device. The memory device is configured to store stored information. In addition to the program, the memory device stores various information used by the program. In the ECU 500, various controls are performed by the processor executing the program stored in the memory device. The ECU 500 is an example of a "control device" according to this disclosure.

[0014] The vehicle 1000 further comprises a drive unit 20 for driving the vehicle 1000, and an inlet 410 and a charger 420 (onboard charger) used for charging the battery pack 100.

[0015] The drive device 20 includes a PCU (Power Control Unit) 21, an MG (Motor Generator) 22, and an engine 23. The vehicle 1000 is configured to be able to travel using the electric power output from the battery pack 100. The vehicle 1000 is, for example, a PHEV (Plug-in Hybrid Electric Vehicle). However, the vehicle 1000 may be other electric vehicles (xEVs). Examples of other electric vehicles include HEV (Hybrid Electric Vehicle) and BEV (Battery Electric Vehicle).

[0016] The PCU 21 includes, for example, an inverter. The MG 22 functions as a driving motor and rotates the drive wheels 24 of the vehicle 1000. The PCU 21 drives the MG 22 using the electric power supplied from the battery pack 100. As a result, the MG 22 enters the power running state. The MG 22 in the power running state converts electric power into torque. The torque is transmitted to the drive wheels 24. Also, the MG 22 enters the regeneration state, for example, when the vehicle 1000 decelerates, and charges each battery included in the battery pack 100 by regenerative power generation.

[0017] The engine 23 functions as an internal combustion engine and rotates the drive wheels 24 of the vehicle 1000. The engine 23 generates power by burning fuel supplied from a fuel tank (not shown). The power generated by the engine 23 is transmitted to the drive wheels 24. The exhaust pipe 23a is connected to the engine 23 and discharges the exhaust of the engine 23 to the outside of the vehicle.

[0018] The vehicle 1000 is configured to perform external charging of the battery pack 100 (charging by electric power supplied from outside the vehicle) while parked. The inlet 410 is configured to be connectable to a charging cable of a power supply facility provided outside the vehicle. The charger 420 performs AC / DC conversion. During external charging, the ECU 500 controls the charger 420 while AC power is input from outside the vehicle to the charger 420 via the inlet 410. The charger 420 converts the AC power into DC power according to a control command from the ECU 500 and outputs the DC power to the battery pack 100. Thereby, each battery included in the battery pack 100 is charged.

[0019] The vehicle 1000 is further equipped with a cooling device for cooling the battery pack 100. The cooling device includes heat medium circuits C1 and C2, and a chiller 240. The heat medium circuit C1 includes a pump 210, a heater 220, and a reserve tank (R / T) 230. The pump 210 circulates the heat medium in the heat medium circuit C1. The heater 220 heats the heat medium flowing through the heat medium circuit C1 in response to a request from the ECU 500. The heat medium flowing through the heat medium circuit C1 cools the battery pack 100 when the temperature of the battery pack 100 rises. However, when the temperature of the battery pack 100 is low due to the influence of weather or location (e.g., cold regions), the heat medium heated by the heater 220 may raise the temperature of the battery pack 100. The heat medium circuit C2 includes a refrigeration cycle device 250. The refrigeration cycle device 250 includes various devices for temperature adjustment by a refrigeration cycle (a cycle of evaporation process, compression process, condensation process, and expansion process). The cooling circuit of an air conditioner (not shown) mounted on the vehicle 1000 may constitute the refrigeration cycle device 250. The heat medium flowing through the heat medium circuit C2 is cooled by the refrigeration cycle device 250. The chiller 240 is connected to the heat medium circuits C1 and C2 and performs heat exchange between the heat medium circulating in the heat medium circuit C1 and the heat medium circulating in the heat medium circuit C2.

[0020] FIG. 2 is a diagram showing the internal configuration of the battery pack 100. Referring to FIG. 2, the battery pack 100 is mounted on the vehicle 1000 such that the -Z side is "down" in FIG. 1 and the -X side is "front" in FIG. 1. In FIG. 2, the UPR (upper) case connected to the +Z side of the LWR (lower) case 101 is omitted, and the configuration inside the case of the battery pack 100 is shown. The battery pack 100 includes battery stacks 111 and 112, a J / B (junction box) 113, reinforcing members (reinforces) 121 to 123, a cooling pipe 130, and a connector block 150.

[0021] Each of the battery stacks 111 and 112 comprises multiple energy storage cells (hereinafter simply referred to as "cells"), each functioning as a secondary battery. Each battery stack is, for example, an energy storage module in which multiple electrically connected cells are modularized. In each of the battery stacks 111 and 112, the multiple cells are stacked and constrained, for example, in the Y direction. Examples of cells include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, or sodium-ion batteries. The type of secondary battery may be a liquid-type secondary battery or an all-solid-state secondary battery. The cell casing may be a laminated casing or a metal rectangular case. Each battery stack may contain only cells of the same type or may contain cells of different types.

[0022] J / B113 is positioned on the -X side of the battery stacks 111 and 112. J / B113 is electrically connected to each of the battery stacks 111 and 112. Each battery in the battery stacks 111 and 112 is configured to exchange power with the outside of the battery pack 100 via J / B113. J / B113 includes a relay and / or fuse and is electrically connected to an external device of the battery pack 100 (e.g., PCU21 and charger 420). When J / B113 is connected (e.g., the relay is closed), the power output by the battery stacks 111 and 112 is output to the PCU21 (Figure 1) via J / B113. When J / B113 is disconnected (e.g., the relay is open), the power supply from the battery stacks 111 and 112 to the PCU21 (Figure 1) is interrupted by J / B113. J / B113 in this embodiment does not include a temperature sensor. However, the components of J / B113 are not limited to those listed above, and are arbitrary.

[0023] Each of the reinforcing members 121 to 123 is formed to be elongated in the Y direction and is connected to the LWR case 101. Reinforcing member 121 is located between the battery stack 111 and the J / B 113. The battery stack 111 is positioned between reinforcing members 121 and 122. The battery stack 112 is positioned between reinforcing members 122 and 123. Reinforcing members 121 to 123 provide collision protection and vibration suppression for the battery stacks 111 and 112.

[0024] The cooling pipe 130 is located on the -Z side of each of the battery stacks 111, 112 and J / B113. The cooling pipe 130 constitutes part of the heat transfer medium circuit C1 (Figure 1), and the heat transfer medium pumped by the pump 210 flows through the cooling pipe 130. The heat transfer medium flowing through the cooling pipe 130 exchanges heat with each of the battery stacks 111, 112 and J / B113. Water is used as the heat transfer medium, and a water pump is used as the pump 210. However, the heat transfer medium is not limited to water; other liquids (such as antifreeze) or gases (such as carbon dioxide) may also be used.

[0025] The cooling pipe 130 is broadly divided into an upstream section that cools the battery stacks 111 and 112 and a downstream section that cools the J / B 113. Both the upstream and downstream sections may be made of metal (e.g., aluminum). The downstream section includes a J / B cooling section 134 and an output port P2 that receives the heat transfer medium output from the J / B cooling section 134. The upstream section is located upstream of the downstream section in the cooling pipe 130 (heat transfer medium flow path) and includes an input port P1 into which the heat transfer medium is input. The battery stacks 111, 112 and J / B 113 can be continuously cooled by circulating the heat transfer medium through the heat transfer medium circuit C1 using the pump 210 (Figure 1).

[0026] The upstream section further includes a horizontal channel 131 that is long in the X direction, vertical channels 132a and 132b that are long in the Y direction, and a horizontal channel 133 that is long in the X direction. The horizontal channel 133 is located on the +Y side of the horizontal channel 131. The horizontal channel 131 and the horizontal channel 133 are in communication via the vertical channels 132a and 132b. The vertical channel 132b is located on the +X side of the vertical channel 132a. The input port P1 is located at the inlet (-X side end) of the horizontal channel 131. The heat transfer fluid input to the input port P1 flows through the horizontal channel 131 on the +X side, through the vertical channels 132a and 132b on the +Y side, and through the horizontal channel 133 on the -X side. The heat transfer fluid flowing through the vertical channel 132a flows directly below the battery stack 111 (-Z side) and exchanges heat with the battery stack 111. Furthermore, the heat transfer fluid flowing through the vertical channel 132b flows directly beneath the battery stack 112 (-Z side) and exchanges heat with the battery stack 112. In the vertical channels 132a and 132b, the heat transfer fluid flows to cool the battery stacks 111 and 112, respectively.

[0027] The -X side end (upstream end) of the lateral flow path 133 is connected to the downstream section near the branch end 134c of the J / B cooling section 134. In this embodiment, the upstream and downstream sections of the cooling pipe 130 are integrally molded and seamlessly connected. However, the embodiment is not limited to this, and the upstream and downstream sections may be molded separately and then joined together.

[0028] As shown in the upper part of Figure 2, the J / B cooling section 134 includes four channels B1 to B4, a base channel 134a that is long in the Y direction, a confluence channel 134b that is long in the Y direction, a branch end 134c, and a confluence end 134d. The channel from the upstream section (lateral channel 133) branches at branch end 134c into the base channel 134a and channel B1. The confluence channel 134b is located on the -X side of the base channel 134a. The base channel 134a and the confluence channel 134b are in communication via channels B1 to B4. Channel B1 is located at the +Y side end of the battery pack 100 and is formed along the contour of the battery pack 100. Channel B1 connects the +Y side end (branch end 134c) of the base channel 134a and the +Y side end of the confluence channel 134b. Each of the channels B2 to B4 is formed to be elongated in the X direction. Channel B4 connects the -Y side end of the base channel 134a to the -Y side end of the confluence channel 134b (confluence end 134d). The confluence channel 134b and channel B4 merge at the confluence end 134d. Output port P2 is located near the confluence end 134d (on the -X side of the confluence end 134d).

[0029] In the J / B cooling section 134, the base channel 134a branches into channels B1 to B4, and channels B1 to B4 merge in a confluence channel 134b. The heat transfer fluid flowing through each of channels B2 to B4 flows directly beneath the J / B113 (-Z side) and exchanges heat with the J / B113. Channel B1 is located near the J / B113. In each of channels B1 to B4, the heat transfer fluid flows to cool the J / B113 (for example, the copper plate of the J / B113).

[0030] In this embodiment, a temperature sensor 113a is provided in the flow path of the J / B cooling unit 134 to detect the temperature of the heat transfer medium flowing through the flow path. The temperature sensor 113a is located, for example, at the confluence end 134d. The temperature sensor 113a is located downstream of the J / B 113 and detects the temperature of the heat transfer medium after the J / B 113 has been cooled (hereinafter referred to as "J / B cooling water temperature"). The vehicle 1000 further includes a temperature sensor 113b that detects the temperature outside the battery pack 100 (hereinafter referred to as "outside pack temperature"). The temperature sensor 113b is installed, for example, on the -Z side of the J / B cooling unit 134 (for example, on the lower surface of at least one of the flow paths B2 to B4). The vehicle 1000 further includes a current sensor 113c that detects the current flowing through the battery stacks 111, 112 and the J / B 113 (hereinafter referred to as "J / B current"). The J / B current detected by the current sensor 113c includes the current output from the battery stacks 111 and 112 to the PCU 21 (Figure 1) via the J / B 113, the current input from the PCU 21 (Figure 1) to the battery stacks 111 and 112 via the J / B 113, and the current input from the charger 420 (Figure 1) to the battery stacks 111 and 112 via the J / B 113. The detected values ​​of the temperature sensors 113a, 113b, and current sensor 113c are output to the ECU 500 (Figure 1). The battery pack 100 may also further include a voltage sensor and a temperature sensor to detect the voltage and temperature of each cell included in the battery stacks 111 and 112. The vehicle 1000 may also further include a protective plate on the -Z side of the J / B cooling unit 134 to protect the J / B cooling unit 134.

[0031] In this embodiment, the ECU 500 is configured to estimate the temperature inside the J / B 113 (hereinafter referred to as "J / B internal temperature") using the outputs of the sensors described above. Figure 3 is a flowchart showing the process related to the estimation of the J / B internal temperature by the ECU 500. The processing flow F1 shown in Figure 3 is repeatedly executed by the ECU 500. "S" in the flowchart means step.

[0032] Referring to Figure 3 in conjunction with Figures 1 and 2, in S11, the ECU 500 acquires the J / B coolant temperature, the outside temperature of the pack, and the J / B current using temperature sensors 113a and 113b and current sensor 113c, and stores the acquired data in a memory device, linked to the acquisition time.

[0033] In the following step S12, the ECU500 determines whether the pump 210 is operating or not. The ON / OFF (stop) control of the pump 210 will be described later (see Figure 4).

[0034] If pump 210 is stopped (NO in S12), ECU 500 calculates the amount of heat generated by J / B 113 (hereinafter referred to as "J / B heat generation") in S13 using the J / B current acquired in S11. Subsequently, in S14, ECU 500 calculates the amount of heat dissipated from the inside of battery pack 100 to the outside of battery pack 100 (hereinafter referred to as "external heat dissipation") using the J / B cooling water temperature and external pack temperature acquired in S11. Further on, in S15, ECU 500 estimates the internal temperature of J / B using the calculated J / B heat generation and external heat dissipation. Finally, ECU 500 stores the obtained estimated value in a memory device, linked to the acquisition time.

[0035] More specifically, as shown in the lower part of Figure 2, within the battery pack 100, J / B113 is installed on the inner wall surface of the bottom J1 of the LWR case 101. A thermal conductive material (for example, a silicone adhesive) may be provided between J / B113 and the LWR case 101. The heat emitted from J / B113 is released to the outside of the battery pack 100 via the bottom J1 of the LWR case 101, the upper J2 and lower J4 of the piping that constitutes the flow path of the J / B cooling section 134, and the heat transfer medium J3 flowing through the piping. The heat transfer medium J3 transfers the heat emitted from J / B113 to the outside of the battery pack 100. The heat generated in J / B113 is released from J / B113 toward the -Z side and transferred to the -Z side in the following order: bottom J1 of the LWR case 101, upper J2 of the piping, heat transfer medium J3 in the piping, lower J4 of the piping, and the outside of the battery pack 100.

[0036] In S13 of Figure 3, ECU500, for example, uses the first equation "J / B heat generation = R × I 2 The heat generation of J / B is calculated according to the following. In the first equation, "R" is the electrical resistance of J / B113, and "I 2 '' represents the squared value of the J / B current. The electrical resistance of J / B113 is a constant (fixed value) and is stored in the memory of the ECU500 beforehand. In S14 of Figure 3, the ECU500 calculates the amount of heat dissipated outside the pack according to, for example, the second equation "Heat dissipation amount outside the pack = Heat transfer area × Heat transfer coefficient × (J / B cooling water temperature - Temperature outside the pack)". In the second equation, "Heat transfer area" corresponds to the contact area between J / B113 and the upper part J2 of the piping. Also, "Heat transfer coefficient" represents the rate at which heat passes from J / B113 to the outside of the battery pack 100. Both the heat transfer area and the heat transfer coefficient are constants (fixed values) and are stored in the memory of the ECU500 beforehand. The heat transfer coefficient may be calculated using the material and thickness of the piping, as well as the heat transfer coefficient of the heat transfer medium J3. As shown in the second equation, heat is dissipated to the outside of the battery pack 100 as long as the J / B cooling water temperature is higher than the temperature outside the pack. When the J / B cooling water temperature matches the outside temperature of the pack, heat dissipation ceases. If the amount of heat generated by the J / B is greater than the amount of heat dissipated outside the pack, the ECU500 determines in S15 of Figure 3 that the temperature of J / B113 will rise and calculates the temperature rise based on the amount of heat generated by the J / B and the amount of heat dissipated outside the pack (for example, the difference between the two). On the other hand, if the amount of heat dissipated outside the pack is greater than the amount of heat generated by the J / B, the ECU500 determines in S15 of Figure 3 that the temperature of J / B113 will fall and calculates the temperature drop based on the amount of heat generated by the J / B and the amount of heat dissipated outside the pack (for example, the difference between the two). The ECU500 can obtain the latest estimated J / B internal temperature (current value) by adding the temperature rise (positive value) or temperature drop (negative value) to the current J / B internal temperature (previous value). In step S15 of Figure 3, the latest estimated J / B internal temperature, calculated in this way, is stored in the ECU500's memory device, linked to the acquisition time.

[0037] Referring again to Figure 3, if the pump 210 is operating (YES in S12), the ECU 500 estimates the J / B internal temperature in S16 using the J / B coolant temperature acquired in S11. While the pump 210 is operating, the J / B coolant temperature has high responsiveness to the J / B internal temperature, and there is a tendency for the J / B coolant temperature and the J / B internal temperature to have a certain relationship. In this embodiment, information (e.g., a formula or map) showing the relationship between the J / B coolant temperature and the J / B internal temperature while the pump 210 is operating is pre-stored in the memory of the ECU 500. In S16, the ECU 500 refers to this information and obtains an estimated value (current value) of the J / B internal temperature from the J / B coolant temperature without using the external pack temperature or J / B current. The latest estimated value of the J / B internal temperature thus obtained is stored in the memory of the ECU 500, linked to the acquisition time.

[0038] Once processing S15 or S16 is completed, the process returns to the first step (S11). Also, each time the J / B internal temperature is estimated in S15 or S16 in Figure 3 above, the ECU 500 starts processing flows F2 and F3, which are described below. Processing flows F2 and F3 are executed in parallel.

[0039] Figure 4 is a flowchart showing the process related to pump control. In the process flow F2 shown in Figure 4, the ECU 500 determines in S21 whether the internal temperature of the J / B estimated in S15 or S16 of Figure 3 exceeds a predetermined reference value (hereinafter referred to as "Temp1"). Temp1 may be around 40°C. If the internal temperature of the J / B exceeds Temp1 (YES in S21), in S22 the ECU 500 controls the pump 210 so that it is in operation. In operation, the pump 210 circulates the heat transfer medium. As a result, the heat transfer medium circulates through the heat transfer medium circuit C1 and flows through the cooling pipe 130. On the other hand, if the internal temperature of the J / B is Temp1 or less (NO in S21), in S23 the ECU 500 controls the pump 210 so that it is in a stopped state. In a stopped state, the pump 210 does not circulate the heat transfer medium. As a result, the circulation (flow) of the heat transfer medium stops. Once processing S22 or S23 is completed, processing flow F2 terminates. In this way, the ECU 500 is configured to switch the operation / stop of the pump 210 based on the estimated internal temperature of the junction box.

[0040] Figure 5 is a time chart showing the changes in the internal temperature of the J / B and the cooling water temperature of the J / B. In the time chart, "t" represents the timing. In Figure 5, line L1 shows the change in the internal temperature of the J / B. Line L2 shows the change in the cooling water temperature of the J / B. Line L3 shows the change in the state of the pump 210 (operating / stopped). The periods t1-t2 and t3-t4 correspond to the periods when the pump 210 is operating (hereinafter referred to as the "pump operating period"). The period t2-t3 corresponds to the period when the pump 210 is stopped (hereinafter referred to as the "pump stopping period").

[0041] At t1, if the internal temperature of the J / B exceeds Temp1, the pump 210 is started by the process in S22 of Figure 4. Then, at t2, if the internal temperature of the J / B falls below Temp1, the pump 210 stops by the process in S23 of Figure 4. During the period from t2 to t3, the internal temperature of the J / B does not exceed Temp1, and the pump 210 remains stopped. Then, at t3, if the internal temperature of the J / B exceeds Temp1, the pump 210 starts operating again by the process in S22 of Figure 4. Then, at t4, if the internal temperature of the J / B falls below Temp1, the pump 210 stops by the process in S23 of Figure 4.

[0042] As shown in Figure 5, during the pump operation period, the J / B coolant temperature (line L2) shows high responsiveness to the J / B internal temperature (line L1). Therefore, during the pump operation period, the ECU 500 can estimate the J / B internal temperature with high accuracy by converting the J / B coolant temperature to the J / B internal temperature according to a formula or map pre-stored in the memory. Furthermore, during the pump shutdown period, the ECU 500 can estimate the J / B internal temperature with high accuracy by using the J / B coolant temperature, the outside temperature of the pack, and the J / B current.

[0043] Figure 6 is a flowchart showing the process related to battery charge and discharge control. In the processing flow F3 shown in Figure 6, the ECU 500 calculates the evaluation value F of J / B113 in S31 using the J / B internal temperature estimated in S15 or S16 of Figure 3. The evaluation value F is a parameter that indicates the heat generation state of the target component (e.g., J / B113). A larger evaluation value F indicates that heat generation is more dominant than heat dissipation in the target component. The heat generated by J / B113 is proportional to the square of the current flowing through J / B113. Furthermore, heat dissipation from J / B113 can be approximated by a first-order lag system. For this reason, the ECU 500 may calculate the evaluation value F by applying a first-order lag process to the square of the current of J / B113. Specifically, the ECU 500 may calculate the evaluation value F according to the third equation shown below.

[0044] F(n+1) = {(K(n)-1) × F(n) + IB(n)} 2} / K(n) In the third equation above, n represents the number of control cycles, i.e., elapsed time, since the start of the processing flow F1 shown in Figure 3. One control cycle may be approximately 100 milliseconds. n is a natural number, F(n+1) represents the evaluation value F for the current (n+1th) cycle, and F(n) represents the evaluation value F for the previous (nth) cycle. The initial value of the evaluation value F may be stored in the memory of the ECU500 beforehand. IB(n) represents the current value flowing through J / B113 when the number of control cycles n is reached. K(n) represents a coefficient for performing a first-order lag approximation, i.e., a coefficient equivalent to the time constant (annealing constant). K(n) is a constant of 1 or greater, and the smaller K(n) is, the larger the increase in F(n+1) per unit time. Different values ​​may be set for the coefficient K(n) when the current is increasing and when it is decreasing.

[0045] The ECU500 corrects K(n) using the estimated internal temperature of the J / B, and calculates the evaluation value F of the J / B113 according to Equation 3 to which the corrected K(n) is applied. The ECU500 corrects K(n) so that, for example, the evaluation value F increases as the internal temperature of the J / B increases. The J / B current obtained in S11 of Figure 3 is substituted into IB(n).

[0046] The method for calculating the evaluation value F is not limited to the above and is arbitrary. For example, the ECU500 may obtain the evaluation value F using the IT (current-time) characteristic map of the J / B113. The IT characteristic map is a three-dimensional map that shows how much current can be applied to the J / B113 before it overheats and becomes unusable. The ECU500 may correct the IT characteristic map using an estimated value of the J / B's internal temperature and obtain the evaluation value F of the J / B113 based on the corrected IT characteristic map. Alternatively, the ECU500 may obtain the evaluation value F using a trained model. The trained model may be generated by machine learning using AI (artificial intelligence). The trained model may be trained to output the evaluation value F of the J / B113 when given data showing the current transition of the J / B113 and the estimated J / B's internal temperature as input.

[0047] In the subsequent S32, the ECU500 uses the evaluation value F from J / B113 above to determine a first guard value (hereinafter referred to as "MWin") which indicates the upper limit of the input power of the battery pack 100, and a second guard value (hereinafter referred to as "MWout") which indicates the upper limit of the output power of the battery pack 100. The lower MWWin, the stricter the input restriction, and the smaller the maximum power that can be input to the battery pack 100. Input restriction reduces energy recovery efficiency and charging speed. The lower MWout, the stricter the output restriction, and the smaller the maximum power that the battery pack 100 can output. Output restriction reduces the driving performance (especially acceleration performance) of the vehicle 1000.

[0048] For example, the ECU500 sets MWin higher when the evaluation value F of J / B113 is below the first threshold than when the evaluation value F of J / B113 exceeds the first threshold. The ECU500 may also lower MWin as the evaluation value F of J / B113 increases. Furthermore, the ECU500 sets MWout higher when the evaluation value F of J / B113 is below the second threshold than when the evaluation value F of J / B113 exceeds the second threshold. The ECU500 may also lower MWout as the evaluation value F of J / B113 increases. Note that each threshold can be set arbitrarily. The first and second thresholds may be the same or different.

[0049] In the subsequent S33, the ECU 500 performs charge and discharge control of each battery in the battery pack 100 based on the MWin and MWout determined as described above. For example, when MG22 is in the powering state, discharge control is performed. In this discharge control, the ECU 500 controls the PCU 21 so that the output power of the battery pack 100 does not exceed MWout. When MG22 is in the regenerative state, first charge control is performed. In first charge control, the ECU 500 controls the PCU 21 so that the input power of the battery pack 100 does not exceed MWin. During external charging, second charge control is performed. In second charge control, the ECU 500 controls the charger 420 so that the input power of the battery pack 100 does not exceed MWin.

[0050] As explained above, the ECU500 (control unit) is configured to estimate the J / B internal temperature (internal temperature of the junction box) using the J / B current (current flowing through the junction box), the external pack temperature (temperature outside the battery pack), and the J / B cooling water temperature (temperature of the heat transfer medium that transfers heat emitted from the junction box to the outside of the battery pack). With this configuration, it becomes possible to estimate the internal temperature of the junction box with high accuracy without installing a temperature sensor inside the junction box.

[0051] The ECU 500 may determine MWin and MWout using the highest value within the estimated error range of the J / B internal temperature, according to the processing flow F3 shown in Figure 6. This method makes it easier to protect the battery pack 100. On the other hand, with this method, if the estimation accuracy of the J / B internal temperature is low, MWin and MWout tend to be set low. In this regard, the ECU 500 according to the above embodiment determines MWin and MWout based on the J / B internal temperature estimated in S16 of Figure 3 during the pump operation period, and determines MWin and MWout based on the J / B internal temperature estimated in S15 of Figure 3 during the pump stop period. The ECU 500 can estimate the J / B internal temperature with high accuracy during both the pump operation period and the pump stop period. Therefore, even when the ECU 500 determines MWin and MWout using the highest value within the estimated error range of the J / B internal temperature, it is easier to set MWin and MWout high. This makes it possible to achieve both protection of the battery pack 100 and improvement of the performance of the battery pack 100.

[0052] The battery pack configuration is not limited to the configuration shown in Figure 2. For example, a temperature sensor may be added upstream of J / B113 to detect the temperature of the heat transfer medium before it cools J / B113. Such a temperature sensor may be provided at the branch terminal 134c shown in Figure 2. During the pump operation period, the ECU 500 may use the temperature of the heat transfer medium before it cools J / B113 to correct the aforementioned J / B cooling water temperature. The vehicle configuration is also not limited to the configuration shown in Figure 1. The vehicle is not limited to a four-wheeled passenger car, but may be a bus or truck, or an xEV with three or five or more wheels. The battery pack may be configured to be wirelessly rechargeable while parked or driving, or to be replaceable at a battery swapping station. The vehicle may be equipped with solar panels or have flight capabilities. The control device may also be used in vehicles other than automobiles (ships, airplanes, railway vehicles, etc.), unmanned mobile vehicles (autonomous transport vehicles, agricultural machinery, construction machinery, robots, drones, etc.), or buildings (houses, factories, etc.).

[0053] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0054] 100 battery packs, 111, 112 battery stacks, 113 junction boxes, 130 cooling pipes, 210 pumps, 500 ECUs, 1000 vehicles.

Claims

1. A control device for managing a battery pack, including batteries and a junction box, The battery is configured to exchange power with the outside of the battery pack via the junction box. The control device is configured to estimate the internal temperature of the junction box using the current flowing through the junction box, the external temperature of the battery pack, and the temperature of the heat transfer medium that transmits heat emitted from the junction box to the outside of the battery pack.

2. The control device is Using the current flowing through the junction box, the amount of heat generated by the junction box is calculated. Using the external temperature of the battery pack and the temperature of the heat transfer medium, the amount of heat dissipated from the inside of the battery pack to the outside of the battery pack is calculated. The control device according to claim 1, configured to estimate the internal temperature of the junction box using the calculated heat generation amount and heat dissipation amount.

3. The control device is configured to control a pump provided in the flow path through which the heat transfer medium flows. The control device is When the pump is operating, the internal temperature of the junction box is estimated using the temperature of the heat transfer medium, rather than using the current flowing through the junction box. The control device according to claim 1 or 2, configured to estimate the internal temperature of the junction box using the current flowing through the junction box, the external temperature of the battery pack, and the temperature of the heat transfer medium when the pump is stopped.

4. The control device according to claim 3, wherein the control device is configured to switch the operation / stop of the pump based on the estimated internal temperature of the junction box.

5. The control device is configured to determine a first guard value indicating an upper limit of the input power of the battery pack using the estimated internal temperature of the junction box, and to control the charging of the battery so that the input power of the battery pack does not exceed the first guard value. The control device according to claim 3, wherein the control device is configured to determine a second guard value indicating an upper limit of the output power of the battery pack using the estimated internal temperature of the junction box, and to control the discharge of the battery so that the output power of the battery pack does not exceed the second guard value.

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