Control device for a heating system, vehicle equipped with the same, and method for managing a heat medium

Abstract

To balance the performance of a heating medium with suppression of its degradation.SOLUTION: A temperature management system 40 heats a battery 10 through a liquid heat medium (LCC). A battery ECU 50 as a controller of the temperature management system 40 includes a processor 51 which calculates an upper limit temperature of the LCC during heating of the battery 10. The processor 51 lowers the upper limit temperature as thermal deterioration of the LCC progresses.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present disclosure relates to a control device for a heating system, a vehicle including the same, and a method for managing a heat medium, and more particularly, to a technique for heating a battery by heat exchange between a liquid heat medium and a battery.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2016-112933 (Patent Document 1) discloses a warming device for a vehicle battery. The warming device includes a heat exchange circuit in which a refrigerant passes through the inside to perform heat exchange between the refrigerant and the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, in a low-temperature environment, the charge / discharge performance (the power that the battery can charge / discharge) of the battery may decrease. Therefore, an electric vehicle is equipped with a heating system that heats the battery (also called temperature rise or warming) by heat exchange between the battery and a liquid heat medium. In particular, a heat medium (coolant) for a vehicle has high electrical insulation in case of leakage.

[0005] The inventors of the present invention have focused on the fact that the following problems may occur in such a heating system. If the temperature of the heat medium is excessively increased to heat the battery, the heat medium may undergo thermal degradation, and the electrical insulation of the heat medium may decrease. Therefore, it is desirable to suppress the thermal degradation of the heat medium while ensuring the heating performance of the heat medium (and thus the charge and discharge performance of the battery), in other words, to achieve both performance assurance and degradation suppression of the heat medium.

[0006] The present disclosure has been made to solve the above problems, and one of the objects of the present disclosure is to achieve both performance assurance and degradation suppression of the heat medium.

Means for Solving the Problems

[0007] (1) In a control device of a heating system according to an aspect of the present disclosure, the heating system heats a battery using a liquid heat medium. The control device includes a processor that calculates an upper limit temperature of the heat medium during heating of the battery. The processor lowers the upper limit temperature as the thermal degradation of the heat medium progresses.

[0008] In the configuration of (1) above, when the thermal degradation of the heat medium has not progressed, the upper limit temperature can be increased to improve the heating performance of the heat medium. On the other hand, when the thermal degradation of the heat medium is progressing, the upper limit temperature can be lowered to suppress further progress of the thermal degradation of the heat medium. Therefore, both performance assurance and degradation suppression of the heat medium can be achieved.

[0009] (2) The processor calculates an index indicating the degree of progress of the thermal degradation of the heat medium based on the temperature of the heat medium, estimates the life of the heat medium based on the index, and when it is estimated that the life is shorter than a predetermined period, lowers the upper limit temperature compared to when it is estimated that the life is longer than the predetermined period.

[0010] According to the configuration of (2) above, when it is estimated that the life is shorter than a predetermined period, the upper limit temperature is lowered, so the thermal degradation of the heat medium is suppressed. As a result, it becomes possible to make the life of the heat medium longer than the predetermined period.

[0011] (3) The processor repeatedly executes arithmetic processing for calculating an index. The arithmetic processing calculates a minute index indicating the degree of progress of thermal degradation of the heat medium during the period based on the temperature of the heat medium during the period from the previous operation to the current operation, and adds the minute index during the period from the previous operation to the current operation to the index up to the previous operation to calculate the index up to the current operation.

[0012] (4) A minute index is calculated based on the product of the temperature frequency of the heat medium during the period and a coefficient determined for each temperature of the heat medium.

[0013] According to the configurations of (3) and (4) above, the index can be calculated with high accuracy (that is, the degree of progress of thermal degradation of the heat medium can be evaluated with high accuracy).

[0014] (5) The processor shortens the operation interval of the arithmetic processing as the index indicates that the thermal degradation of the heat medium is progressing.

[0015] In the configuration of (5) above, at the stage where the thermal degradation of the heat medium has not progressed, the operation load of the processor for calculating the index can be reduced by lengthening the operation interval. On the other hand, by shortening the operation interval as the thermal degradation of the heat medium progresses, it becomes possible to adjust the upper limit temperature based on an accurate index. As a result, excessive thermal degradation of the heat medium can be more reliably suppressed.

[0016] (6) The processor executes first life estimation processing. The first life estimation processing includes processing for calculating an index based on information on the region where the heating system is used.

[0017] (7) The first life estimation processing includes processing for calculating an index when a temperature load in the region where the heating system is used is applied to the heat medium.

[0018] (8) The first life estimation processing includes processing for estimating an index when a usage load in the region where the heating system is used is applied to the heat medium.

[0019] (9) The processor executes a second life estimation process. The second life estimation process includes a process of estimating the life by performing a regression analysis of the indicators over the entire period.

[0020] (10) The processor executes a third life estimation process. The third life estimation process includes a process of estimating the life by performing a regression analysis of a part of the indicators including the indicators up to the time of the current calculation among the indicators over the entire period.

[0021] (11) The processor executes a fourth life estimation process. The fourth life estimation process includes a process of multiplying the result of the first life estimation process and the result of the second life estimation process. The first life estimation process includes a process of calculating an indicator based on information on the region where the heating system is used. The second life estimation process includes a process of estimating the life by performing a regression analysis of the indicators over the entire period.

[0022] (12) The higher the indicator indicates that the thermal degradation of the heat medium is progressing, the higher the ratio of the result of the second life estimation process used in the fourth life estimation process is.

[0023] According to the configurations (6) to (12) above, the life of the heat medium can be estimated with high accuracy according to the region (the first life estimation process), the actual usage situation over the entire period (the second life estimation process), the recent actual usage situation (the third life estimation process), both the region and the usage situation (the fourth life estimation process), etc.

[0024] (13) The predetermined period is the warranty period of the heat medium. According to the configuration (13) above, it becomes possible to make the life of the heat medium longer than the warranty period of the heat medium.

[0025] (14) A vehicle according to another aspect of the present disclosure includes the above-described control device for the heating system and the heating system.

[0026] (15) The battery heating method according to another aspect of the present disclosure includes a step of calculating the upper limit temperature of the liquid heat medium and a step of heating the battery using the heat medium. The calculating step includes a step of lowering the upper limit temperature as the thermal degradation of the heat medium progresses.

[0027] According to the configuration of the above (14) and the method of the above (15), similar to the configuration of the above (1), it is possible to achieve both ensuring the performance of the heat medium and suppressing degradation.

Effect of the Invention

[0028] According to the present disclosure, it is possible to achieve both ensuring the performance of the heat medium and suppressing degradation.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Mode for Carrying Out the Invention

[0030] Hereinafter, 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 the description thereof will not be repeated.

[0031] In the following embodiments, a configuration in which a heating system (and its control device) according to the present disclosure is mounted on a vehicle will be described as an example. However, the use of the heating system according to the present disclosure is not limited to vehicle use. The heating system according to the present disclosure is applicable to any use (for example, stationary use).

[0032] [Embodiment] [Vehicle Configuration] FIG. 1 is a diagram schematically showing the overall configuration of a vehicle equipped with a heating system according to an embodiment of the present disclosure. Vehicle 1 is an electric vehicle equipped with a battery. In this example, vehicle 1 is a battery electric vehicle (BEV). Vehicle 1 may be a plug-in hybrid electric vehicle (PHEV), or may be a fuel cell electric vehicle (FCEV). Vehicle 1 may also be a hybrid electric vehicle (HEV) that does not support plug-in charging.

[0033] Vehicle 1 includes, for example, a battery 10, a monitoring unit 20, a system main relay (SMR) 30, a temperature management system 40, a battery electronic control unit (ECU) 50, an inlet 61, an AC / DC converter 62, a charge relay (CHR) 63, a power control unit (PCU) 71, a motor generator (MG) 72, a power transmission gear 73, drive wheels 74, and an integrated ECU 80.

[0034] Battery 10 is a battery pack including a plurality of cells. Each cell is typically a liquid-based secondary battery (such as a lithium-ion battery or a nickel-metal hydride battery), but may also be a all-solid-state battery. Battery 10 stores electric power for driving MG 72 and supplies the electric power to MG 72 through PCU 71. Also, battery 10 is charged by receiving the generated electric power through PCU 71 when MG 72 generates electricity.

[0035] The monitoring unit 20 includes various sensors for monitoring the state of the battery 10. Specifically, the monitoring unit 20 includes a voltage sensor, a current sensor, and a temperature sensor (none of which are shown). The voltage sensor detects the voltage VB of the battery 10 (each cell). The current sensor detects the current IB charged and discharged to and from the battery 10. The temperature sensor detects the temperature TB of the battery 10 (at least one cell). Each sensor outputs its detected value to the battery ECU 50.

[0036] The SMR 30 is electrically connected to the power lines connecting the battery 10 and the PCU 71, and between the battery 10 and the CHR 63. The SMR 30 is opened and closed according to a command from the battery ECU 50. When the SMR 30 is opened (off), the battery 10 is electrically disconnected from the PCU 71 and the CHR 63. When the SMR 30 is closed (on), the battery 10 is electrically connected to the PCU 71 and the CHR 63.

[0037] The temperature management system 40 is configured to adjust the temperature of the battery 10 using a liquid heat medium according to a control command from the battery ECU 50. The temperature management system 40 corresponds to the "heating system" according to the present disclosure. The temperature management system 40 includes, for example, a flow path 41, a coolant temperature sensor 42, an electric heater 43, and a heater control device 44.

[0038] The flow path 41 includes a piping circuit through which the heat medium flows (circulates). In the present embodiment, the flow path 41 is configured to cool the battery 10 when the battery 10 is at a high temperature by circulating the heat medium through the circuit, and is also configured to heat (raise the temperature, warm up) the battery 10 in an environment of low temperature (for example, -20°C or higher and less than 0°C) or extremely low temperature (for example, less than -20°C). Hereinafter, the heat medium is referred to as "LLC" (Long Life Coolant). LLC has high electrical insulation in case of leakage.

[0039] The coolant temperature sensor 42 detects the temperature of the LLC (hereinafter referred to as "coolant temperature") TC and outputs the detected value to the battery ECU 50.

[0040] The electric heater 43 is, for example, a PTC (Positive Temperature Coefficient) heater and heats the LLC. Thereby, the battery 10 is heated.

[0041] The heater control device 44 controls the electric heater 43 according to a control command from the battery ECU 50. More specifically, in the present embodiment, the battery ECU 50 commands the heater control device 44 the upper limit temperature UL of the allowable temperature range of the coolant temperature TC. The heater control device 44 controls the electric heater 43 so that the coolant temperature TC approaches the upper limit temperature UL but does not exceed the upper limit temperature UL. The way of controlling the electric heater 43 may be the switching (on / off switching) of the electric heater 43 or the output adjustment from the electric heater 43.

[0042] The battery ECU 50 includes a processor 51 and a memory 52. The processor 51 is an arithmetic processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The memory 52 is a storage device including a ROM (Read Only Memory) and a RAM (Random Access Memory). The memory 52 stores a system program including an OS (Operating System), a control program including computer-readable code, and various parameters for managing the battery 10. The processor 51 realizes various processes by reading out the system program, the control program, and the parameters, expanding them in the memory 52, and executing them.

[0043] In this embodiment, the battery ECU 50 performs "thermal degradation evaluation" for quantitatively evaluating the degree of progress of thermal degradation of the LLC. Further, the battery ECU 50 performs "upper limit temperature control" for controlling the temperature (coolant temperature TC) of the LLC within an appropriate temperature range according to the result of the thermal degradation evaluation. The thermal degradation evaluation and the upper limit temperature control will be described in detail later. Note that the battery ECU 50 corresponds to the "control device" according to the present disclosure.

[0044] The inlet 61 is configured such that a charging connector (not shown) provided at the tip of the charging cable is connected with mechanical connection when performing plug-in charging. When the inlet 61 and the charging connector are connected, an electrical connection between the charging facility (not shown) and the vehicle 1 is ensured. The inlet 61 corresponds to both AC charging (normal charging) and DC charging (rapid charging) in this example.

[0045] The AC / DC converter 62 converts the AC power supplied from the AC charging facility via the charging cable into DC power for charging the battery 10. The vehicle 1 may include a DC / DC converter (not shown) corresponding to DC charging instead of or in addition to the AC / DC converter 62.

[0046] The CHR 63 is connected in series to the SMR 30 on the power line which is the charging path from the inlet 61. The CHR 63 is opened and closed according to a command from the integrated ECU 80. When the CHR 63 is closed and the SMR 30 is closed, the battery 10 can be charged with the power from the inlet 61.

[0047] The PCU 71 is electrically connected between the SMR 30 and the MG 72. The PCU 71 includes a converter and an inverter (both not shown) and drives the MG 72 according to a command from the integrated ECU 80.

[0048] MG72 is an AC rotating electrical machine, for example, a permanent magnet synchronous motor including a rotor in which permanent magnets are embedded. The output torque of MG72 is transmitted to the drive wheels 74 through the power transmission gear 73 to drive the vehicle 1. Also, MG72 can generate electricity by the rotational force of the drive wheels 74 during the braking operation of the vehicle 1. The electric power generated by MG72 is converted into the charging power of the battery 10 by the PCU71.

[0049] The integrated ECU 80 includes a processor 81 and a memory 82, similar to the battery ECU 50. The integrated ECU 80 executes various controls for controlling the vehicle 1 to a desired state based on the signals received from each sensor and the programs and maps stored in the memory 82. The integrated ECU 80 controls, for example, the power charged and discharged between the battery 10 and the PCU 71. Also, the integrated ECU 80 communicates with the charging facility and controls the AC / DC converter 62 and the CHR 63 to control the plug-in charging of the vehicle 1. The battery ECU 50 and the integrated ECU 80 are configured to be able to communicate with each other. The battery ECU 50 and the integrated ECU 80 may be integrally configured.

[0050] <Thermal degradation evaluation> FIG. 2 is a flowchart showing an example of the processing procedure for thermal degradation evaluation in the present embodiment. The processing shown in this flowchart is executed when a predetermined condition is satisfied (for example, at predetermined intervals). Each step is realized by software processing by the battery ECU 50, but may also be realized by hardware (electric circuit) arranged in the battery ECU 50. The same applies to the upper limit temperature control (see FIG. 7) described later. Hereinafter, the steps are abbreviated as S.

[0051] The outline of thermal degradation evaluation will be described. The battery ECU 50 calculates an index indicating the degree of progress of LLC thermal degradation during the period from the previous calculation to the current calculation. This index is described as "thermal degradation TD". The currently calculated thermal degradation is described as "TD(t)", the previously calculated thermal degradation is described as "TD(t - 1)", and the thermal degradation calculated two times before the previous is described as "TD(t - 2)". The same applies to before that. Further, the battery ECU 50 calculates an index indicating the degree of progress of LLC thermal degradation at present by integrating the thermal degradation from the start (first calculation) to the present (current calculation) (that is, from TD(t0) to TD(t)). This index is described as "integrated thermal degradation ΣTD". The initial value of the integrated thermal degradation ΣTD is 0. Note that the thermal degradation TD corresponds to the "minute index" according to the present disclosure, and the integrated thermal degradation ΣTD corresponds to the "index" according to the present disclosure.

[0052] In S101, the battery ECU 50 calculates the calculation timing of the current integrated thermal degradation ΣTD(t). More specifically, the battery ECU 50 calculates the calculation interval from the previous calculation to the current calculation based on the previous integrated thermal degradation ΣTD(t - 1). Then, the battery ECU 50 determines the time when the calculation interval has elapsed from the calculation time of the previous integrated thermal degradation ΣTD(t - 1) as the calculation timing of the current integrated thermal degradation ΣTD(t).

[0053] Figure 3 is a diagram showing an example of a method for determining the calculation interval of the integrated thermal degradation. The horizontal axis represents the previous integrated thermal degradation ΣTD(t - 1). The vertical axis represents the calculation interval from the previous calculation to the current calculation. As shown in Figure 3, the larger the previous integrated thermal degradation ΣTD(t - 1) (that is, the more the LLC thermal degradation has progressed), the shorter the calculation interval is determined.

[0054] When the integrated heat deterioration ΣTD is small (when the heat deterioration of the LLC has not progressed much), by increasing the calculation interval, the calculation load of the battery ECU 50 consumed for heat deterioration evaluation can be reduced. On the other hand, as the integrated heat deterioration ΣTD increases (as the heat deterioration of the LLC progresses), by shortening the calculation interval, it becomes possible to execute the upper limit temperature control described later based on the accurate integrated heat deterioration ΣTD. As a result, excessive heat deterioration of the LLC can be more reliably suppressed.

[0055] Note that FIG. 3 shows an example in which the calculation interval decreases stepwise as the integrated heat deterioration ΣTD increases. However, the calculation interval may decrease continuously (linearly or curvilinearly) as the integrated heat deterioration ΣTD increases. Alternatively, the calculation interval may be constant regardless of the integrated heat deterioration ΣTD.

[0056] Returning to FIG. 2, in S102, the battery ECU 50 acquires the coolant temperature TC from the coolant temperature sensor 42. Then, the battery ECU 50 calculates the frequency f of the coolant temperature TC (for example, the frequency of each temperature range when the coolant temperature TC is classified every 1°C) (S103).

[0057] In S104, the battery ECU 50 determines whether the calculation timing calculated in S101 has arrived. If the calculation timing has not arrived (NO in S104), the battery ECU 50 returns the process to S102. As a result, the sampling of the coolant temperature TC and the calculation of the frequency f are executed again. When the calculation timing arrives (YES in S104), the battery ECU 50 advances the process to S105 and calculates the current heat deterioration TD(t).

[0058] FIG. 4 is a conceptual diagram for explaining the calculation method (the process of S105) of the heat deterioration of the LLC. The horizontal axis represents the coolant temperature TC. The upper vertical axis represents the frequency f of the coolant temperature TC, and the lower vertical axis represents the deterioration coefficient k. The frequency f of the coolant temperature TC is obtained by the processes of S102 and S103.

[0059] A large deterioration coefficient k indicates a large degree of progress of thermal deterioration of the battery 10. The higher the coolant temperature TC, the larger the deterioration coefficient k. The deterioration coefficient k is determined by prior experiments according to the specifications of the battery 10. In the present embodiment, it is determined such that the deterioration coefficient k at the upper limit temperature Tcmp (described later) of the comparative example is 1. When TC < Tcmp, k < 1. When TC > Tcmp, k > 1.

[0060] The battery ECU 50 multiplies the frequency f by the deterioration coefficient k for each temperature range (for example, 1 °C) of the coolant temperature TC. Then, the battery ECU 50 adds the product (f × k) for all coolant temperatures TC. Thereby, the current thermal deterioration TD(t) is calculated (see Equation (1)). TD(t)=Σ(f×k) ···(1)

[0061] Returning to FIG. 2, in S106, the battery ECU 50 calculates the integrated thermal deterioration ΣTD(t) up to the current time by adding the current thermal deterioration TD(t) to the integrated thermal deterioration ΣTD(t - 1) up to the previous time (see Equation (2)). ΣTD(t)=ΣTD(t-1)+TD(t) ···(2)

[0062] <Upper Limit Temperature Control> To clarify the characteristics of the upper limit temperature control in the present embodiment, first, the temperature control in the comparative example will be described.

[0063] FIG. 5 is a diagram for explaining how to determine the upper limit temperature in the comparative example. The horizontal axis represents the elapsed time from the initial time t0 (for example, at the time of manufacturing the battery 10). The upper vertical axis represents the coolant temperature TC, and the lower vertical axis represents the integrated thermal deterioration ΣTD. The same applies to FIG. 6 described later.

[0064] In the comparative example, the upper limit temperature UL that allows the change in the coolant temperature TC is set to Tcmp. The upper limit temperature UL = Tcmp of the comparative example is maintained constant over the entire period. Tcmp is determined such that the integrated thermal degradation ΣTD reaches the guaranteed value W at the time when the guarantee period tW (for example, tW = 20 years) of the LLC has elapsed. The guaranteed value W is a value that can ensure the necessary electrical insulation of the LLC even if UL = Tcmp always holds until the guarantee period tW elapses, and is determined based on the results of the evaluation test (characteristic test regarding electrical insulation) of the LLC. Reaching the guaranteed value W for the integrated thermal degradation ΣTD means that the LLC has reached the end of its life.

[0065] When the coolant temperature TC reaches the upper limit temperature UL = Tcmp, further heating of the LLC is restricted (prohibited), so that the charge-discharge performance of the battery 10 (especially the charging performance during DC charging) cannot be sufficiently ensured. On the other hand, if the coolant temperature TC is set higher than Tcmp, the thermal degradation of the LLC progresses too fast, and there is a possibility that the electrical insulation of the LLC cannot be ensured until the guarantee period tW of the LLC elapses. It is desirable to suppress the thermal degradation of the LLC while ensuring the heating performance of the LLC (thereby ensuring the charge-discharge performance of the battery 10), in other words, to achieve both performance assurance and degradation suppression of the LLC. Therefore, in the present embodiment, the upper limit temperature UL is set to be variable. More specifically, the more the thermal degradation of the LLC progresses, the lower the upper limit temperature UL is set.

[0066] FIG. 6 is a diagram for explaining the outline of the upper limit temperature control in the present embodiment. In this example, the upper limit temperature UL is set to three levels: Tlim, T1, or T2. These three temperatures have the relationship of Tlim > T1 > T2, and all are higher than the upper limit temperature Tcmp in the comparative example.

[0067] In the example shown in FIG. 6, during the period from time t1 to time t2, the coolant temperature TC exceeds the upper limit temperature Tcmp in the comparative example. Therefore, the degradation coefficient k>1 during this period (see FIG. 5). Thus, during this period, the thermal degradation TD(t) is larger and the increase rate of the integrated thermal degradation ΣTD is faster compared to the reference line L0 of the comparative example where k = 1. Conversely, outside the above period, the degradation coefficient k<1. Therefore, outside the above period, the thermal degradation TD(t) is smaller and the increase rate of the integrated thermal degradation ΣTD is slower (the slope is gentle) compared to the reference line L0 of the comparative example where k = 1.

[0068] Thus, even when the upper limit temperature UL is variably set according to the coolant temperature TC, by appropriately calculating the integrated thermal degradation ΣTD according to the coolant temperature TC in accordance with the above-described thermal degradation evaluation (see FIG. 2), it is possible to ensure that the integrated thermal degradation ΣTD at the time when the guarantee period has elapsed does not exceed the guarantee value W. Thereby, excessive thermal degradation of the LLC can be suppressed. In addition, by allowing the coolant temperature TC to rise above Tcmp, the heating of the LLC is not unnecessarily restricted. As a result, the charge / discharge performance of the battery 10 can be ensured.

[0069] ≪Overall processing flow≫ FIG. 7 is a flowchart showing an example of the processing procedure for upper limit temperature control in the present embodiment. At the start of a series of processes, the battery ECU 50 sets the upper limit temperature UL of the LLC to, for example, the highest Tlim.

[0070] In S2, the battery ECU 50 executes a life estimation process for estimating the life of the LLC. The life of the LLC means the period during which the LLC can ensure the electrical insulation required for the LLC. In the present embodiment, five lines are used for the life estimation process. The five lines include the first to fourth estimation lines L1 to L4 in addition to the reference line L0 similar to the comparative example. Each line will be described using the following flowchart and time chart.

[0071] ≪Life estimation process≫ FIG. 8 is a flowchart showing an example of the processing procedure of the life estimation process. FIG. 9 is a time chart for explaining an example of the life estimation process. In FIG. 9, the horizontal axis represents the elapsed time from the initial time t0. The vertical axis represents the integrated thermal degradation ΣTD.

[0072] Referring to FIG. 9(A), the reference line L0 (see FIG. 9(A)) is the same as L0 in the comparative example. As described above, the reference line L0 is determined such that the integrated thermal degradation ΣTD reaches the guaranteed value W at the end of the guarantee period tW of the LLC.

[0073] Referring to FIG. 8, the processes of S201 to S204 are processes for calculating the first estimated line L1. First, in S201, the battery ECU 50 acquires the regional information of the vehicle 1. The regional information is information indicating the location of the vehicle 1, and is typically position information acquired by GPS (Global Positioning System). However, the regional information may be fixed information such as the destination information of the vehicle 1.

[0074] In S202, the battery ECU 50 calculates an environmental estimated line L1env based on the regional information. The environmental estimated line L1env is an estimated line indicating the increase in the integrated thermal degradation when a typical temperature load at the location of the vehicle 1 is applied to the LLC, and is determined according to the past outside air temperature in the region. Further, the battery ECU 50 calculates a usage estimated line L1use based on the regional information (S203). The usage estimated line L1use is an estimated line indicating the increase in the integrated thermal degradation when a typical usage load at the location of the vehicle 1 is applied to the LLC, and is determined according to the normal driving mode (driving speed, gradient, driving time, etc.) of the vehicle in the region. Each of the environmental estimated line L1env and the usage estimated line L1use is prepared in advance for each region and stored in the memory 52 of the battery ECU 50.

[0075] In S204, the battery ECU 50 calculates a first estimated line L1 based on the environmental estimated line L1env and the usage estimated line L1use. More specifically, as shown in FIG. 9(B), the first estimated line L1 is calculated by adding the environmental estimated line L1env and the usage estimated line L1use (adding the estimated values at the same time) (see Equation (3)). L1 = L1env + L1use ···(3)

[0076] In S205, the battery ECU 50 calculates a second estimated line L2, which is a regression line of the integrated thermal degradation ΣTD over the entire period from the initial time t0 to the present. In the example of FIG. 9(C), the second estimated line L2 is calculated, for example, by the least squares method so as to provide a good approximation for the four integrated thermal degradations Σ0, ΣTD(t1), ΣTD(t2), ΣTD(t3)) from the initial time t0 to the present.

[0077] In S206, the battery ECU 50 calculates a third estimated line L3 based on the two most recent integrated thermal degradations ΣTD, that is, the integrated thermal degradation ΣTD(t - 1) up to the previous time and the integrated thermal degradation ΣTD(t - 1) up to the current time. More specifically, the current third estimated line L3 is a straight line L3c connecting the integrated thermal degradation ΣTD(t - 1) up to the previous time and the integrated thermal degradation ΣTD(t - 1) up to the current time. Past straight lines L3a and L3b are also shown in FIG. 9(D). By calculating the third estimated line L3, the most recent usage pattern of the LLC can be reflected in the life estimation compared to the case where only the second estimated line L2 is calculated. For example, when the integrated thermal degradation ΣTD rapidly increases, it becomes possible to quickly lower the upper limit temperature UL (details will be described later).

[0078] In S207, the battery ECU 50 calculates a fourth estimated line L4 by multiplying the first estimated line L1 and the second estimated line L2 by a ratio j (where 0 ≤ j ≤ 1) (see Equation (4)). L4 = L1 × j + L2 × (1 - j)···(4)

[0079] FIG. 10 is a diagram showing an example of a method for determining the ratio j. The horizontal axis represents the integrated thermal degradation ΣTD(t−1) up to the previous time. The vertical axis represents the ratio j. As shown in FIG. 10, the larger the integrated thermal degradation ΣTD(t−1) up to the previous time (i.e., the more the thermal degradation of the LLC progresses), the lower the ratio j is determined.

[0080] When the integrated thermal degradation ΣTD is small (when the thermal degradation of the LLC does not progress much), the ratio j is high, and the contribution of the first estimated line L1 is larger than the contribution of the second estimated line L2. Then, to put it simply, the fourth estimated line L4 is calculated mainly based on the regional information of vehicle 1, which is pre-prepared data. On the other hand, as the integrated thermal degradation ΣTD increases (as the thermal degradation of the LLC progresses), the ratio j decreases, so the contribution of the first estimated line L1 decreases and the contribution of the second estimated line L2 increases. As a result, the fourth estimated line L4 is calculated mainly based on the integrated thermal degradation ΣTD of the LLC over the entire period, which reflects the actual usage situation of vehicle 1.

[0081] Note that FIG. 10 shows an example in which the ratio j decreases stepwise as the integrated thermal degradation ΣTD increases. However, the ratio j may decrease continuously (linearly or curvilinearly) as the integrated thermal degradation ΣTD increases. Alternatively, the ratio j may be constant regardless of the integrated thermal degradation ΣTD.

[0082] Note that the processes of calculating the first estimated line L1 to the fourth estimated line L4 correspond to the "first life estimation process" to the "fourth life estimation process" according to the present disclosure, respectively.

[0083] Returning to FIG. 7, after calculating the four estimated lines L1 to L4 by the life estimation process, the battery ECU 50 advances the process to S3 and determines which of Tlim, T1, and T2 the upper limit temperature UL of the LLC is set to. When UL = Tlim (Tlim in S3), the battery ECU 50 determines whether the current integrated thermal degradation ΣTD(t) obtained by the thermal degradation evaluation (see FIG. 2) is less than the reference line L0(t) (S4).

[0084] FIG. 11 is a diagram for explaining the determination process of S4. As shown in FIG. 11(A), when the current integrated thermal degradation ΣTD(t) is less than the reference line L0(t) (YES in S4), the battery ECU 50 executes the first control (S5). On the other hand, as shown in FIG. 11(B), when the current integrated thermal degradation ΣTD(t) is greater than or equal to the reference line L0(t) (NO in S4), the battery ECU 50 executes the second control (S6).

[0085] Returning to FIG. 7, when UL = T1 in S3 (T1 in S3), the battery ECU 50 executes the third control (S7). When UL = T2 in S3 (T2 in S3), the battery ECU 50 executes the fourth control (S8). A series of processes end after the execution of any one of the first control to the fourth control. Hereinafter, the details of the first control to the fourth control will be described in order.

[0086] ≪First Control≫ FIG. 12 is a flowchart showing an example of the processing procedure of the first control. FIG. 13 is a time chart for explaining the first control. The first control is executed when the current integrated thermal degradation ΣTD(t) is below the reference line L0(t) on the condition that the upper limit temperature UL = Tlim (in short, when the progress of thermal degradation is slow and there is a margin with respect to the standard). In the first control, the upper limit temperature UL remains unchanged at Tlim. On the other hand, it is determined whether it is better to suppress further thermal degradation of the LLC.

[0087] Referring to FIGS. 12 and 13, in S501, the battery ECU 50 calculates L4(tW), which is the estimated value by the fourth estimated line at the end of the guarantee period (t = tW). As described above, the estimated value by the fourth estimated line L4 is a combination of the previously prepared data (L1) and the data (L2) reflecting the actual usage situation of vehicle 1 according to the ratio j.

[0088] In S502, the battery ECU 50 determines whether L4(tW) at the end of the warranty period is greater than or equal to the guaranteed value W (in other words, whether the life of the LLC is longer than the warranty period). If L4(tW) ≥ W (YES in S502), the battery ECU 50 proceeds to S503. On the other hand, if L4(tW) < W (NO in S502), since it is unlikely that the integrated heat deterioration ΣTD will exceed the guaranteed value W even after the warranty period has elapsed, the battery ECU 50 maintains the upper limit temperature UL of the LLC at Tlim (S509).

[0089] In S503, the battery ECU 50 calculates L3(tW), which is the estimated value based on the third estimated line at the end of the warranty period. As described above, the estimated value based on the third estimated line L3 reflects the most recent usage pattern of the LLC in life estimation.

[0090] In S504, the battery ECU 50 determines whether L3(tW) at the end of the warranty period is greater than or equal to the guaranteed value W. If L3(tW) ≥ W (YES in S504), the battery ECU 50 proceeds to S505. On the other hand, if L3(tW) < W (NO in S504), the battery ECU 50 maintains the upper limit temperature UL of the LLC at Tlim (S509).

[0091] In S505, the battery ECU 50 calculates the deviation rate (error rate) λ(t) of the integrated heat deterioration ΣTD(t) with respect to the current reference line L0(t) (see Equation (5)). The absolute value of the deviation rate λ represents the magnitude of the deviation of the integrated heat deterioration ΣTD(t) from the reference line L0(t). Note that instead of the deviation rate λ, the difference between the reference line L0(t) and the integrated heat deterioration ΣTD(t) may be used. λ(t) = ΣTD(t) / L0(t) ···(5)

[0092] In S506, the battery ECU 50 determines whether the absolute value of the current deviation rate λ(t) is less than or equal to a predetermined threshold TH. When |λ(t)| ≤ TH (YES in S506), the current integrated thermal degradation ΣTD(t) is close to the reference line L0(t), and in the future, the integrated thermal degradation ΣTD(t) may exceed the reference line L0(t). Therefore, the battery ECU 50 maintains the upper limit temperature UL of the LLC at Tlim (S507). Furthermore, the battery ECU 50 notifies (proposes) the user via a non - shown HMI (Human Machine Interface) so as to reduce as much as possible the usage pattern of the vehicle 1 that causes thermal degradation of the LLC (specifically, the frequency and / or time of DC charging).

[0093] On the contrary, when |λ(t)| > TH (NO in S506), since there is sufficient margin in the current integrated thermal degradation ΣTD(t) with respect to the reference line L0(t), the battery ECU 50 does not notify the user and simply maintains the upper limit temperature UL of the LLC at Tlim (S509).

[0094] When notification to the user is made in the first control, although the integrated thermal degradation ΣTD may exceed the guaranteed value W by the end of the guarantee period as it is, the upper limit temperature UL of the LLC cannot be lowered. When the current integrated thermal degradation ΣTD(t) exceeds the reference line L0(t) (NO in S4 of FIG. 7), the following second control is executed instead of the first control, and the upper limit temperature UL of the LLC is lowered.

[0095] ≪Second Control≫ FIG. 14 is a flowchart showing an example of the processing procedure of the second control. FIG. 15 is a time chart for explaining the second control. The second control is executed when the current integrated thermal degradation ΣTD(t) is greater than or equal to the reference line L0(t) (in short, when the thermal degradation is progressing more than the reference) on the condition that the upper limit temperature UL = Tlim. In the second control, the upper limit temperature UL can be lowered from Tlim to T1 or T2.

[0096] As shown in FIG. 15, in the present embodiment, first reference value REF1 to third reference value REF3 are defined. These three reference values have a magnitude relationship of REF1 > REF2 > REF3, and all are smaller than guaranteed value W.

[0097] Referring to FIGS. 14 and 15, in S601, battery ECU 50 calculates L4(tW), which is an estimated value by the fourth estimated line at the time (t = tW) when the guarantee period has elapsed.

[0098] In S602, battery ECU 50 determines whether L4(tW) at the time when the guarantee period has elapsed is greater than or equal to guaranteed value W. If L4(tW) ≥ W (YES in S602), as it is, there is a possibility that integrated thermal degradation ΣTD exceeds guaranteed value W by the time the guarantee period has elapsed. Also, the fact that the second control is being executed means that the current integrated thermal degradation ΣTD(t) is greater than or equal to reference line L0(t). Therefore, battery ECU 50 proceeds to S603 to lower the upper limit temperature UL of LLC.

[0099] On the other hand, if L4(tW) < W (NO in S602), although it can be said that the current integrated thermal degradation ΣTD(t) is greater than or equal to reference line L0(t), it is estimated that integrated thermal degradation ΣTD will not exceed guaranteed value W by the time the guarantee period has elapsed. Therefore, battery ECU 50 maintains the upper limit temperature UL of LLC at Tlim (S607).

[0100] In S603, battery ECU 50 calculates L1env(tW), which is an estimated value by the environmental estimated line at the time when the guarantee period has elapsed. L1env(tW) is an estimated value of integrated thermal degradation ΣTD when a typical temperature load at the location of vehicle 1 is continuously applied to LLC until the guarantee period has elapsed. Thermal degradation due to typical use loads at the location of vehicle 1 is not taken into account in L1env(tW). That is, L1env(tW) indicates the degree of progress of thermal degradation of LLC when vehicle 1 is left unused until the guarantee period has elapsed.

[0101] In S604, the battery ECU 50 determines whether L1env(tW) at the expiration of the warranty period is greater than or equal to the second reference value REF2. When L1env(tW) ≥ REF2 (YES in S604), the battery ECU 50 lowers the upper limit temperature UL of the LLC in two steps and sets it to T2 (S605). Thereby, it is possible to prevent the integrated thermal degradation ΣTD from reaching the guaranteed value W even if the vehicle 1 is left unattended until the expiration of the warranty period.

[0102] On the other hand, when L1env(tW) < REF2 (NO in S604), the battery ECU 50 lowers the upper limit temperature UL of the LLC in one step and sets it to T1 (S606). This is to minimize the decrease in the charge and discharge performance of the battery 10 (minimize the impact on the charge and discharge performance).

[0103] In the second control, unlike the first control, the estimated value based on the third estimated line is not used. This is because at the time of execution of the second control, thermal degradation has already progressed beyond the standard at the current time (ΣTD(t) ≥ L0(t)), and the upper limit temperature UL of the LLC is lowered regardless of the recent usage pattern of the LLC. That is, in the second control, deterioration suppression of the LLC is prioritized compared to the first control.

[0104] In addition, when lowering the upper limit temperature UL of the LCC, the frequency at which DC charging is possible (the number of charging permits during a predetermined period) may be decreased. When the upper limit temperature UL = Tlim, the frequency is the highest (the restriction on the number of charging times is the loosest). When the upper limit temperature UL = T1, the frequency is moderate. When the upper limit temperature UL = T2, the frequency is the lowest (the restriction on the number of charging times is the strictest). Thereby, thermal degradation of the LCC can be further suppressed.

[0105] ≪Third Control≫ FIG. 16 is a flowchart showing an example of the processing procedure of the third control. FIG. 17 is a time chart for explaining the third control. The third control is executed when the upper limit temperature UL of the LLC = T1. In the third control, the upper limit temperature UL may be maintained at T1, may be raised to Tlim, or may be lowered to T2.

[0106] Referring to FIGS. 16 and 17, in S701, the battery ECU 50 calculates L4(tW), which is the estimated value by the fourth estimated line when the warranty period has elapsed. Further, the battery ECU 50 calculates L1env(tW), which is the estimated value by the environmental estimated line when the warranty period has elapsed (S702).

[0107] In S703, the battery ECU 50 determines whether L4(tW) is greater than or equal to the guaranteed value W and whether L1env(tW) is greater than or equal to the second reference value REF2. If L4(tW) ≥ and L1env(tW) ≥ REF2 (YES in S703), the battery ECU 50 lowers the upper limit temperature UL of the LLC and sets it to T2 (S704). If L4(tW) < W or L1env(tW) < REF2 (NO in S703), the battery ECU 50 proceeds to S705 for processing.

[0108] In S705, the battery ECU 50 determines whether L1env(tW) is greater than or equal to the first reference value REF1. If L1env(tW) ≥ REF1 (YES in S705), the battery ECU 50 maintains the upper limit temperature UL of the LLC at T1 (S706). On the other hand, if L1env(tW) < REF1 (NO in S705), the battery ECU 50 raises the upper limit temperature UL of the LLC and sets it to Tlim (S707).

[0109] <<Fourth Control>> FIG. 18 is a flowchart showing an example of the processing procedure of the fourth control. FIG. 19 is a time chart for explaining the fourth control. The fourth control is executed when the upper limit temperature UL = T2. In the fourth control, the upper limit temperature UL is maintained at T2 or raised by one step to T1.

[0110] Referring to FIGS. 18 and 19, in S801, the battery ECU 50 calculates L4(tW), which is the estimated value by the fourth estimated line when the warranty period has elapsed.

[0111] In S802, the battery ECU 50 determines whether L4(tW) is greater than or equal to the guaranteed value W. If L4(tW) ≥ W (YES in S802), the battery ECU 50 proceeds with the process to S803. On the other hand, if L4(tW) < W (NO in S802), the battery ECU 50 maintains the upper limit temperature UL of the LLC at T2 (S806).

[0112] In S803, the battery ECU 50 calculates L1env(tW), which is the estimated value based on the environmental estimation line at the expiration of the guaranteed period (t = tW).

[0113] In S804, the battery ECU 50 determines whether L1env(tW) is less than the third reference value REF3. If L1env(tW) < REF3 (YES in S804), the battery ECU 50 raises the upper limit temperature UL of the LLC and sets it to T1 (S803). On the other hand, if L1env(tW) ≥ REF3 (NO in S804), the battery ECU 50 maintains the upper limit temperature UL of the LLC at T2 (S806).

[0114] It is also conceivable to use a common reference value for raising the upper limit temperature UL of the LLC in the third control and lowering the upper limit temperature UL of the LLC in the fourth control. However, in the present embodiment, different second reference value REF2 and third reference value REF3 are used (REF2 > REF3). In the third control, the upper limit temperature UL of the LLC is not lowered until L1env(tW) exceeds the second reference value REF2 (YES in S703, S704). In the fourth control, the upper limit temperature UL of the LLC is not raised until L1env(tW) is lower than the third reference value REF3 (YES in S804, S805). Thus, providing two types of reference values corresponds to giving hysteresis to the reference value. This can prevent unnecessary switching (so-called chattering) of the upper limit temperature UL of the LLC.

[0115] As described above, in this embodiment, when the thermal degradation of the heat medium has not progressed (YES in S4), the upper limit temperature UL = Tlim can be set to improve the heating performance of the heat medium (first control). On the other hand, when the thermal degradation of the heat medium is progressing (NO in S4), the upper limit temperature UL = T1 or T2 can be set to suppress further progress of the thermal degradation of the heat medium (second control to fourth control). Therefore, according to this embodiment, it is possible to achieve both performance assurance and degradation suppression of the heat medium.

[0116] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0117] 1 Vehicle, 10 Battery, 20 Monitoring Unit, 30 SMR, 40 Temperature Management System, 41 Flow Path, 42 Coolant Temperature Sensor, 43 Electric Heater, 44 Heater Control Device, 50 Battery ECU, 51 Processor, 52 Memory, 61 Inlet, 62 AC / DC Converter, 71 PCU, 72 MG, 73 Power Transmission Gear, 74 Driving Wheel, 80 Integrated ECU, 81 Processor, 82 Memory.

Claims

1. A control device for a heating system that heats a battery using a liquid heat medium, comprising a processor that calculates an upper limit temperature of the heat medium during heating of the battery, wherein the processor lowers the upper limit temperature as the thermal degradation of the heat medium progresses, a control device for a heating system.

2. The processor, calculates an index indicating the degree of progress of thermal degradation of the heat medium based on the temperature of the heat medium, estimates the life of the heat medium based on the index, and when it is estimated that the life is shorter than a predetermined period, lowers the upper limit temperature compared to when it is estimated that the life is longer than the predetermined period, the control device for a heating system according to claim 1.

3. The processor repeatedly executes arithmetic processing for calculating the index, and the arithmetic processing, calculates a minute index indicating the degree of progress of thermal degradation of the heat medium during the period from the previous calculation to the current calculation based on the temperature of the heat medium during the period, and includes a process of calculating the index up to the current calculation by adding the minute index during the period from the previous calculation to the current calculation to the index up to the previous calculation, the control device for a heating system according to claim 2.

4. calculates the minute index based on the product of the temperature frequency of the heat medium during the period and a coefficient determined for each temperature of the heat medium, the control device for a heating system according to claim 3.

5. The processor shortens the calculation interval of the arithmetic processing as the index indicates that the thermal degradation of the heat medium is progressing, the control device for a heating system according to claim 3.

6. The processor executes a first life estimation process, The control device for a heating system according to any one of claims 2 to 5, wherein the first life estimation process includes a process of calculating the index based on information on the area where the heating system is used.

7. The control device for a heating system according to claim 6, wherein the first life estimation process includes a process of calculating the index when a temperature load in the area where the heating system is used is applied to the heat medium.

8. The control device for a heating system according to claim 6, wherein the first life estimation process includes a process of estimating the index when a usage load in the area where the heating system is used is applied to the heat medium.

9. The processor executes a second life estimation process, The control device for a heating system according to any one of claims 3 to 5, wherein the second life estimation process includes a process of estimating the life by regression analysis of the index over the entire period.

10. The processor executes a third life estimation process, The control device for a heating system according to any one of claims 3 to 5, wherein the third life estimation process includes a process of estimating the life by regression analysis of a part of the index including the index up to the current calculation time among the indexes over the entire period.

11. The processor executes a fourth life estimation process, The fourth life estimation process includes a process of multiplying the result of the first life estimation process and the result of the second life estimation process, The first life estimation process includes a process of calculating the index based on information on the area where the heating system is used, The control device for a heating system according to any one of claims 3 to 5, wherein the second life estimation process includes a process of estimating the life by regression analysis of the index over the entire period.

12. The control device for a heating system according to claim 11, wherein the processor increases the ratio of the result of the second life estimation process used in the fourth life estimation process as the index indicates that the thermal degradation of the heat medium is progressing.

13. The control device for a heating system according to any one of claims 2 to 5, wherein the predetermined period is a guarantee period of the heat medium.

14. A vehicle comprising the control device for a heating system according to any one of claims 1 to 5, and the heating system.

15. A method for managing a heat medium, comprising: calculating an upper limit temperature of a liquid heat medium; and heating a battery using the heat medium, wherein the calculating step includes a step of lowering the upper limit temperature as the thermal degradation of the heat medium progresses. ​

Images