control device

Abstract

This technology makes it easier to secure battery output power from the moment the vehicle starts running. [Solution] In the control device 34, the acquisition unit 40 acquires the temperature, voltage, and internal resistance of the battery (auxiliary battery 30) mounted on the vehicle. The determination unit 44 determines the battery's heating temperature based on the acquired temperature, voltage, and internal resistance. The control unit 46 controls the heater 32 for heating the battery based on the acquired battery temperature and the determined heating temperature while the vehicle is parked and in motion.

Description

Technical Field

[0001] The present invention relates to a control device mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a battery diagnostic device. The battery diagnostic device includes an acquisition unit that acquires the temperature and internal resistance of a battery, a determination unit that determines a diagnostic temperature, which is the temperature used for diagnosing the battery, based on the temperature acquired by the acquisition unit, an estimation unit that estimates the internal resistance of the battery at the diagnostic temperature based on the temperature and internal resistance acquired by the acquisition unit and the diagnostic temperature determined by the determination unit, and a diagnostic unit that diagnoses the battery based on the internal resistance estimated by the estimation unit. The battery is a lithium-ion battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the output of a lithium-ion battery decreases at low temperatures, in the technology of Patent Document 1, the battery is heated by a heater at low temperatures to improve the power characteristics of the battery. The heating by the heater is performed after the vehicle is started. Therefore, when the vehicle is started and begins to run at low temperatures, the battery may not be able to supply the required power until it is heated.

[0005] An object of the present invention is to provide a technology that can easily ensure the output power of a battery from the start of vehicle running.

Means for Solving the Problems

[0006] To solve the above problems, a control device according to one aspect of the present invention includes: an acquisition unit that acquires the temperature, voltage, and internal resistance of a battery mounted on a vehicle; a determination unit that determines the heating temperature of the battery based on the acquired temperature, voltage, and internal resistance of the battery; and a control unit that controls a heater for heating the battery based on the acquired temperature and the determined heating temperature while the vehicle is parked and in motion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technology that makes it easier to secure battery output power from the moment the vehicle starts running. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the functional configuration of the power supply system in the embodiment. [Figure 2] Figure 1 is a flowchart showing the temperature rise control process of the control device. [Figure 3] Figure 3(a) shows an example of the discharge current pattern of the auxiliary battery, Figure 3(b) shows the relationship between the current and voltage acquired by the acquisition unit, and Figure 3(c) shows an example of the derived resistance table. [Figure 4] This figure shows the change in the battery temperature of the auxiliary battery due to temperature control. [Modes for carrying out the invention]

[0009] Figure 1 schematically shows the functional configuration of the power supply system 1 of the embodiment. The power supply system 1 is mounted on a vehicle (not shown). The vehicle is, for example, an electric vehicle. The electric vehicle may be, for example, a battery electric vehicle (BEV) or a fuel cell electric vehicle (FCEV) that generates vehicle driving force solely by a motor. The vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0010] The power supply system 1 comprises an auxiliary battery unit 10, a first body ECU (Electronic Control Unit) 12, a second body ECU 14, a third body ECU 16, a DC / DC converter 18, a first switch 20a, a high-voltage battery 22, a first load 24a, a second load 24b, a third load 24c, a fourth load 24d, a fifth load 24e, and a sixth load 24f. Hereafter, unless otherwise specified, the first load 24a through the sixth load 24f will be collectively referred to as load 24.

[0011] The high-voltage battery 22 is the vehicle's drive battery and is a rechargeable secondary battery, such as a lithium-ion battery. The high-voltage battery 22 can supply power to the DC / DC converter 18 via the first switch 20a. The high-voltage battery 22 can also supply power to a motor (not shown) via a power conversion unit (not shown). The motor generates the vehicle's driving force using the output power of the power conversion unit. The motor's driving force is transmitted to the vehicle's drive wheels. The DC / DC converter 18 and the first switch 20a are controlled by a control device (not shown).

[0012] The DC / DC converter 18 is a bidirectional step-up / step-down converter capable of supplying power from the high-voltage battery 22 to multiple loads 24 and auxiliary battery units 10 via the first body ECU 12. The DC / DC converter 18 can also supply power from the auxiliary battery units 10 via the first body ECU 12 to the power conversion unit.

[0013] The first body ECU 12 includes a third switch 20c, a fourth switch 20d, a fifth switch 20e, a sixth switch 20f, a seventh switch 20g, and a control device 50. Hereinafter, unless otherwise specified, the first switch 20a, etc., will be collectively referred to as switches 20. Switches 20 can be made up of, for example, semiconductor relays.

[0014] The third switch 20c, the fourth switch 20d, and the fifth switch 20e are connected in series between the auxiliary battery unit 10 and the DC / DC converter 18. The sixth switch 20f is connected between one end of the fourth switch 20d and the first load 24a. The seventh switch 20g is connected between the other end of the fourth switch 20d and the second load 24b. The control device 50 controls each of the switches 20 of the first body ECU 12.

[0015] The second body ECU 14 includes an eighth switch 20h, a ninth switch 20i, and a control device 52. The eighth switch 20h is connected between one end of the fourth switch 20d of the first body ECU 12 and the third load 24c. The ninth switch 20i is connected between one end of the fourth switch 20d and the fourth load 24d. The control device 52 controls each of the switches 20 of the second body ECU 14. The control device 52 can communicate with the control device 50.

[0016] The third body ECU 16 includes a 10th switch 20j, an 11th switch 20k, and a control device 54. The 10th switch 20j is connected between the other end of the 4th switch 20d of the first body ECU 12 and the 5th load 24e. The 11th switch 20k is connected between the other end of the 4th switch 20d and the 6th load 24f. The control device 54 controls each of the switches 20 of the third body ECU 16. Although the communication lines are not shown in the diagram, the control device 54 can communicate with the control device 50.

[0017] Various known control methods can be employed to control each switch 20 by the control devices 50, 52, and 54.

[0018] The multiple loads 24 are loads such as electronic equipment installed in the vehicle. The loads 24 may include, for example, various ECUs, various actuators, navigation systems, audio systems, advanced driver-assistance systems, etc. The loads 24 can operate using at least one of the power from the high-voltage battery 22 and the power from the auxiliary battery unit 10. The number of loads 24 is arbitrary.

[0019] The auxiliary battery unit 10 includes a second switch 20b, an auxiliary battery 30, a heater 32, and a control device 34.

[0020] The auxiliary battery 30 is a rechargeable secondary battery such as a lithium-ion battery, for example. The auxiliary battery 30 is a battery with a voltage lower than that of the high-voltage battery 22. The auxiliary battery 30 is connected to the first body ECU 12 via the second switch 20b. The auxiliary battery 30 can be charged by the power of the high-voltage battery 22 supplied via the DC / DC converter 18 and the first body ECU 12.

[0021] When the high-voltage battery 22 fails, the auxiliary battery 30 can supply power to a plurality of loads 24 via the first body ECU 12, and can supply power to the motor via the first body ECU 12, the DC / DC converter 18, and the power conversion unit. The auxiliary battery 30 enables the vehicle to perform backup driving when the high-voltage battery 22 fails.

[0022] Output requirements are predetermined for the auxiliary battery 30. Ensuring power for backup driving when the high-voltage battery 22 fails is also one of the output requirements. The power required for backup driving is relatively large. Since the output power of the lithium-ion battery of the auxiliary battery 30 decreases at low temperatures, it cannot meet the output requirements and cannot output the power for backup driving at low temperatures. Therefore, a heater 32 is installed to warm up and keep warm the auxiliary battery 30, thereby ensuring the output power of the auxiliary battery 30. The heater 32 can operate with the power of the auxiliary battery 30 and can heat the auxiliary battery 30.

[0023] The control device 34 controls the conduction and non-conduction of the first switch 20a and controls the operation and stop of the heater 32. The control device 34 can communicate with the control device 50 of the first body ECU 12.

[0024] The control device 34 includes an acquisition unit 40, an output unit 42, a determination unit 44, and a control unit 46. The functional configuration of the control device 34 can be realized through the cooperation of hardware and software resources. The control device 34 has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. as hardware resources. The ROM stores various control programs and maps that are referenced when executing these control programs as software resources. The CPU performs calculation processing based on the various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores the calculation results from the CPU and data input from various sensors. The control device 34 can be configured as, for example, a microcontroller.

[0025] The acquisition unit 40 acquires the temperature of the auxiliary battery 30 (hereinafter referred to as battery temperature) detected by a temperature sensor (not shown), the output current of the auxiliary battery 30 detected by a current sensor (not shown), and the output voltage of the auxiliary battery 30 detected by a voltage sensor (not shown). Based on the acquired current and voltage, the acquisition unit 40 acquires the internal resistance of the auxiliary battery 30.

[0026] The derivation unit 42 derives an estimated value of the internal resistance at a predetermined lower voltage limit for each of several temperatures, based on the battery temperature, voltage, internal resistance acquired by the acquisition unit 40, and a pre-held standard resistance map, and derives a resistance table that tables outlining the derived values.

[0027] The determination unit 44 determines the temperature rise of the auxiliary battery 30 based on the resistance table derived by the derivation unit 42 and a predetermined resistance threshold. In other words, the determination unit 44 determines the temperature rise based on the acquired battery temperature, voltage, and internal resistance.

[0028] The control unit 46 controls the heater 32 based on the acquired battery temperature and the determined heating temperature while the vehicle is in motion, stopped, or parked.

[0029] Next, the operation of the control device 34 with the above configuration will be explained. Figure 2 is a flowchart showing the temperature rise control process of the control device 34 in Figure 1. The process in Figure 2 starts when the ignition switch or power switch, which is the vehicle's starting switch, is turned on, that is, when the vehicle is started.

[0030] When the vehicle is started, the acquisition unit 40 turns on the second switch 20b and instructs the control device 50 to discharge the auxiliary battery 30 for a certain period of time and supply the discharged power to a predetermined load 24. The acquisition unit 40 acquires the voltage and current of the auxiliary battery 30 before and during discharge and acquires the battery temperature T0 (S10).

[0031] Figure 3(a) shows an example of the discharge current pattern of the auxiliary battery 30. The acquisition unit 40 acquires the current I1 and voltage V1 before discharge. The current I1 is zero. As shown in Figure 3(a), discharge is performed for a certain period of time with a constant current and voltage. The acquisition unit 40 also acquires the current I0 and voltage V0 in a stable state during discharge.

[0032] Returning to Figure 2, the acquisition unit 40 derives the internal resistance R1 of the auxiliary battery 30 (S12) based on the acquired current I1 and voltage V1 before discharge and the current I0 and voltage V0 during discharge, and acquires the internal resistance R1.

[0033] Figure 3(b) shows the relationship between current and voltage acquired by the acquisition unit 40. The acquisition unit 40 derives the internal resistance R1 as the absolute value of the slope of the line passing through the sample points for current I1 and voltage V1 and the sample points for current I0 and voltage V0. As the auxiliary battery 30 deteriorates and the degree of performance degradation increases, the internal resistance R1 increases.

[0034] Returning to Figure 2, the derivation unit 42 derives an estimated value of the internal resistance at the lower voltage Vlow for each temperature, based on the acquired internal resistance R1, battery temperature T0, voltage V0, and a pre-held standard resistance map (S14). The derivation unit 42 derives a resistance table containing the estimated values ​​of the internal resistance at the lower voltage Vlow for each of a predetermined number of temperatures. The lower voltage Vlow is included in the output requirements of the auxiliary battery 30.

[0035] The standard resistance map maps the voltage and temperature dependence of the internal resistance of auxiliary batteries of the same type as the auxiliary battery 30. The standard resistance map is acquired in advance through experiments and stored in the memory of the control device 34.

[0036] The internal resistance of the auxiliary battery 30 at temperature T and lower voltage Vlow is denoted as R(T,Vlow). The derivation section 42 derives the internal resistance R(T,Vlow) according to the following equation (1). The internal resistance at temperature T and voltage V in the standard resistance map is denoted as r(T,V).

[0037] R(T,Vlow)=R1×r(T,Vlow) / r(T0,V0)...Equation (1)

[0038] Figure 3(c) shows an example of a resistance table derived in the derivation section 42. In this resistance table, T0 = 0°C, and estimated values ​​of the internal resistance R(T,Vlow) at the lower limit voltage Vlow are derived for every 5°C from -15°C to 5°C. R(-15,Vlow) = R10, R(-10,Vlow) = R11, R(-5,Vlow) = R12, R(0,Vlow) = R13, R(5,Vlow) = R14. R10 to R14 represent numerical values. Note that the internal resistance R1 at temperature T0 and voltage V0 is the internal resistance R1 obtained in S12.

[0039] The internal resistance R(T,Vlow) at the lower voltage limit Vlow in the resistance table is derived based on the current internal resistance R1 of the auxiliary battery 30. Therefore, the internal resistance R(T,Vlow) at the lower voltage limit Vlow reflects the degradation of the auxiliary battery 30.

[0040] As can be seen from equation (1), the standard resistance map can also be said to specify how many times the internal resistance r(T,Vlow) at the lower limit voltage Vlow at each temperature T is compared to the internal resistance r(T0,V0) at the voltage V0 at temperature T0 in a standard auxiliary battery.

[0041] Returning to Figure 2, the determination unit 44 determines the heating temperature based on the derived resistance table and a predetermined resistance threshold (S16). The resistance threshold is determined based on the upper limit of the internal resistance that satisfies the output requirements of the auxiliary battery 30. The determination unit 44 identifies the internal resistance at the lower limit voltage Vlow, which is below the resistance threshold and closest to the resistance threshold, in the resistance table, and sets the temperature at the identified internal resistance as the heating temperature.

[0042] For example, in the resistance table example in Figure 3(c), assume that the resistance threshold is less than R11 and greater than R12. In this case, the determination unit 44 determines the heating temperature to be -5°C, which is the temperature when R12 is used. If the temperature of the auxiliary battery 30 is raised to -5°C or higher, the internal resistance of the auxiliary battery 30 will be below the resistance threshold, and it will be possible to output the lower limit voltage Vlow and power specified in the output requirements of the auxiliary battery 30, thus satisfying the output requirements.

[0043] Returning to Figure 2, the acquisition unit 40 acquires the battery temperature (S18). If the battery temperature acquired in S18 is lower than the heating temperature (Y in S20), the control unit 46 drives the heater 32 (S22). If the battery temperature is not lower than the heating temperature (N in S20), the process returns to S18. After S22, if the battery temperature is "heating temperature + α" or higher (Y in S24), the control unit 46 stops the heater 32 (S26), and the process returns to S18. If the battery temperature is not "heating temperature + α" or higher (N in S24), the process returns to S18. The processes from S18 to S26 are executed while the vehicle is running and stopped, as well as while parked with the start switch off.

[0044] Figure 4 shows the change in the battery temperature of the auxiliary battery 30 due to temperature rise control. The heater 32 is stopped until the battery temperature falls below the temperature rise threshold. When the battery temperature falls below the temperature rise threshold, the heater 32 is activated, and the battery temperature begins to rise in response to the heating by the heater 32. When the battery temperature rises to or above the temperature rise threshold threshold, the heater 32 stops. The control continues in the same manner thereafter, and the auxiliary battery 30 is kept warm even when parked.

[0045] As described above, according to this embodiment, the heater 32 is controlled based on the battery temperature of the auxiliary battery 30 and the temperature to be raised while the vehicle is running, stopped, or parked, so that the auxiliary battery 30 can be raised even when parked. Therefore, even when starting to drive a parked vehicle in a low-temperature environment, it becomes easier to secure the output power of the auxiliary battery 30 necessary for backup driving, etc., from the start of driving. In other words, it becomes easier to meet the output requirements of the auxiliary battery 30 from the start of driving the vehicle.

[0046] Here, the longer the auxiliary battery 30 is used, the more it deteriorates. Also, even if the usage period is the same, the degree of deterioration differs depending on how the auxiliary battery 30 is used. As the auxiliary battery 30 deteriorates, the power it can output decreases, so it is necessary to raise the heating temperature.

[0047] In this regard, according to the embodiment, an estimated value of the internal resistance at the lower voltage Vlow is derived for each predetermined temperature based on the internal resistance R1 of the auxiliary battery 30, the battery temperature T0, the voltage V0, and a standard resistance map, so that the internal resistance at the lower voltage Vlow that reflects the degree of deterioration of the auxiliary battery 30 can be estimated. Then, the heating temperature is determined based on the internal resistance at the lower voltage Vlow and the resistance threshold for each temperature, so that the heating temperature corresponding to the degree of deterioration of the auxiliary battery 30 can be determined. Therefore, the auxiliary battery 30 can be heated to an appropriate temperature with minimal waste in order to secure the necessary output power. As a result, the power consumption of the heater 32 can be prevented from becoming too high, and the reduction in the vehicle's mileage can also be prevented from becoming too low.

[0048] The present invention has been described above based on embodiments. The embodiments are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of each component and each processing process, and that such modifications also fall within the scope of the present invention.

[0049] For example, in this embodiment, the auxiliary battery 30 is kept warm even while parked. However, if the vehicle's start switch is not turned on even after a predetermined first hour has elapsed since parking began, the control unit 46 may stop the temperature-raising control. The first hour may be, for example, 12 hours, 24 hours, etc., and can be determined appropriately by experiment or simulation. This makes it possible to suppress power consumption in situations where the frequency of driving is relatively low. In this case, even if the vehicle's start switch is not turned on after the temperature-raising control is stopped, the control device 34 may start processing the flowchart in Figure 2 after a predetermined second hour has elapsed. The second hour may be, for example, several hours, or the same as the first hour, and can be determined appropriately by experiment or simulation. This makes it possible to increase the possibility of securing the required output power of the auxiliary battery 30 from the start of driving. [Explanation of Symbols]

[0050] 1...Power supply system, 10...Auxiliary battery unit, 22...High-voltage battery, 30...Auxiliary battery, 32...Heater, 34...Control device, 40...Acquisition unit, 42...Output unit, 44...Determination unit, 46...Control unit.

Claims

[Claim 1] An acquisition unit that acquires the temperature, voltage, and internal resistance of the battery installed in the vehicle, A determination unit that determines the temperature rise of the battery based on the acquired temperature, voltage, and internal resistance of the battery, A control unit controls a heater for heating the battery based on the battery temperature obtained and the determined heating temperature while the vehicle is parked and in motion. A control device characterized by comprising:

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