Charging system and charging method of battery

Abstract

The invention relates to a charging system and a charging method of a battery. A charging system is provided with a battery that can be charged using an external power source, a heater that heats the battery, and a control device. The control device acquires the actual temperature of the battery and the output power of the external power supply, sets the target temperature of the battery on the basis of the output power, and drives the heater when the actual temperature is lower than the target temperature during charging of the battery using the external power supply. The control device also compares the current value of the output power and the last value of the output power during charging of the battery using the external power supply, updates the target temperature based on the current value when the current value exceeds the last value, and maintains the target temperature at the current value when the current value does not exceed the last value.

Description

Technical Field

[0001] The present disclosure relates to systems and methods for charging a battery using an external power source. Background Art

[0002] Japanese Patent Laid-Open No. 2023-102958 discloses a system for a battery capable of being charged using an external power source (external charging). This conventional system drives and controls a heater that heats the battery during a period when the temperature of the battery during external charging is lower than a reference temperature. However, the power from the battery during external charging is used to drive the heater. Therefore, in the conventional system, in the drive control of the heater, the power supplied from the external power source to the battery and the minimum value of the power consumed by the heater are compared. Furthermore, when the power supplied from the external power source is less than the minimum value of the power consumed by the heater, the heater is driven intermittently.

[0003] As documents indicating the technical level in the technical field related to the present disclosure, Japanese Patent Application Laid-Open No. 2023-102958, Japanese Patent Application Laid-Open No. 2016-110957 and Japanese Patent Application Laid-Open No. 11-341698 can be exemplified. Summary of the invention

[0004] The external power source includes an external power source whose output power varies according to the power consumption in the home or various facilities. In the present disclosure, the drive control of the heater during the charging of the battery using such an external power source is considered. In this case, in order to shorten the charging time, it is desirable to change the target temperature of the battery in the drive control of the heater according to the output power. For example, when the output power is small, the target temperature is lowered, and when the output power is large, the target temperature is increased. By changing the target temperature in this way, the power consumption of the heater can be suppressed during the period of small output power, and the charging time can be shortened by increasing the temperature of the battery during the period of large output power.

[0005] However, if the target temperature is changed according to the output power, the actual temperature of the battery may change in a manner that crosses the target temperature. If the actual temperature changes in a manner that crosses the target temperature, it is expected that the heater drive will be repeatedly stopped and the drive will be restarted after the stop. As a result, when the total number of stops and restarts of the drive increases, components such as relays are easily worn out. Therefore, in the case of changing the target temperature according to the output power, it is desirable to make improvements from the perspective of suppressing the occurrence of adverse conditions associated with the change.

[0006] One object of the present disclosure is to provide a technology that can reduce the occurrence of malfunctions associated with changes in the target temperature of the battery according to the output power of the external power source when charging the battery using the external power source, and shorten the charging time.

[0007] A first aspect of the present disclosure is a battery charging system having the following features.

[0008] The charging system comprises: A battery capable of being charged using an external power source; a heater for increasing the temperature of the battery; and A control device controls the driving of the heater.

[0009] The control device obtains the actual temperature of the battery and the output power of the external power supply, sets a target temperature of the battery based on the output power, and drives the heater when the actual temperature is lower than the target temperature during charging of the battery using the external power supply.

[0010] The control device also compares the current value of the output power with the previous value of the output power during charging of the battery using the external power supply, and updates the target temperature based on the current value when the current value exceeds the previous value, and maintains the target temperature at the current value when the current value does not exceed the previous value.

[0011] A second aspect of the present disclosure is a battery charging method having the following features.

[0012] The method comprises the following steps: acquiring an actual temperature of a battery capable of being charged using an external power source and output power of the external power source; setting a target temperature of the battery based on the output power; during charging of the battery using the external power supply, when the actual temperature is lower than the target temperature, driving a heater for raising the temperature of the battery; During charging of the battery using the external power source, comparing a current value of the output power with a previous value of the output power; and When the current value exceeds the previous value, the target temperature is updated based on the current value, and when the current value does not exceed the previous value, the target temperature is maintained at the current value.

[0013] According to the present disclosure, during charging of a battery using an external power source, a current value of the output power of the external power source is compared with a previous value. And, in a case where the current value exceeds the previous value, the target temperature of the battery based on the current value is updated. On the other hand, in a case where the current value does not exceed the previous value, the target temperature is maintained at the current value. That is, the target temperature is updated only when the current value exceeds the previous value. Therefore, compared with a case where the target temperature is updated every time the output power changes, the total number of times the drive of the heater is stopped and the drive is restarted after the stop can be suppressed. In addition, by updating the target temperature based on the current value that exceeds the previous value, the updated target temperature can also be set to a temperature higher than the target temperature before the update. Therefore, the charging time can also be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which: Figure 1 is a diagram illustrating a structure particularly related to a charging system according to an embodiment of the present disclosure; Figure 2 A diagram for explaining an overview of drive control of a heater performed during charging of a battery using an external power source and features of an embodiment; Figure 3 is a flowchart showing the flow of a process of driving control of a heater particularly related to the embodiment; Figure 4 is a diagram for explaining a second processing example of the drive control of the heater; and Figure 5 It is a diagram for explaining the third processing example of the drive control of the heater. DETAILED DESCRIPTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the structures and the like described in the embodiments shown below are not essential to the present disclosure unless otherwise specified or clearly defined in principle.

[0016] Battery Charging System The battery charging system of the embodiment is mounted on a vehicle, for example. The vehicle is, for example, a vehicle that can be plug-in charged using power supplied from an external power supply provided outside the vehicle. As such a vehicle, a plug-in hybrid electric vehicle (PHEV) can be exemplified.

[0017] Figure 1 FIG. 2 is a diagram for explaining a configuration particularly related to the charging system of the embodiment. Figure 1 2 , an external power source 10 , a charging system 20 , and a motor 30 are depicted. The external power source 10 is, for example, a single-phase 100V AC power source or a single-phase 200V AC power source for household use. The external power source 10 includes a connector 11 .

[0018] The charging system 20 is a configuration equivalent to the battery charging system of the embodiment and includes a charging cap 21 , a power line 22 , a step-up / step-down unit 23 , a battery 24 , a heater 25 , a control device 26 , and a temperature sensor 27 .

[0019] The charging cover 21 is a portion into which the connector 11 is inserted. The power line 22 connects the charging cover 21 and the buck-boost unit 23. The power line 22 also connects the charging cover 21 and the heater 25. The power line 22 supplies power received from the external power source 10 via the connector 11 to the buck-boost unit 23 and the heater 25, respectively.

[0020] The buck-boost unit 23 is a device that charges the battery 24. For example, the buck-boost unit 23 includes a buck-boost converter (not shown) and various relays (not shown). The buck-boost converter boosts the power supplied from the external power source 10 based on a control signal from the control device 26. The various relays operate based on the control signal from the control device 26 and supply the power boosted by the buck-boost converter to the battery 24.

[0021] The battery 24 is a power storage device for driving the motor 30. The battery 24 is composed of a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. For example, the battery 24 is composed of a battery stack in which a plurality of battery cells of about 1V to 5V are stacked.

[0022] The heater 25 is a device that generates Joule heat by resistance by energizing the battery 24, thereby heating the battery 24. The temperature (actual temperature AT) of the heater 25 is measured by a temperature sensor 27 attached to the battery 24. Information on the actual temperature AT measured by the temperature sensor 27 is output to the control device 26.

[0023] The control device 26 is a computer that performs various controls in a vehicle equipped with the charging system 20. The control device 26 includes computer hardware such as a processor and a memory, and operates according to software such as an installed operating system (OS) and application programs. The various controls performed by the control device 26 include drive control of the heater 25. The drive control of the heater 25 includes control performed during plug-in charging of the battery 24 using the external power source 10 and control performed during the drive of the motor 30. The former drive control is performed from the perspective of charging efficiency, and the latter drive control is performed from the perspective of discharging efficiency. In the embodiment, focus is placed on the former drive control.

[0024] The motor 30 drives the vehicle equipped with the charging system 20. The motor 30 is supplied with electric power from the battery 24. The motor 30 converts the electric power supplied from the battery 24 into rotational energy to rotate the wheels. It should be noted that a plurality of motors 30 may be provided.

[0025] Heater drive control Figure 2 The diagram is a diagram for explaining the outline of the drive control of the heater 25 and the features of the embodiment during the plug-in charging of the battery 24 using the external power source 10. The drive control of the heater 25 is performed when the actual temperature AT is lower than the target temperature TT of the battery 24.

[0026] In the embodiment, in order to shorten the charging time of the battery 24, the target temperature TT is set based on the output power OP of the external power source 10. For example, the larger the output power OP is, the higher the target temperature TT is set. When the target temperature TT is set to a higher temperature, the actual temperature AT rises in a shorter time. Therefore, the charging time can be shortened as the charging efficiency increases. On the other hand, when the target temperature TT is set to a lower temperature, the power consumption of the heater can also be suppressed.

[0027] exist Figure 2 In the example shown, threshold values ​​TH1 and TH2 are set for setting the target temperature of the battery based on the system power (output power of the external power supply). In this example, the target temperature is set by comparing the system power with the threshold values ​​TH1 and TH2. For example, when the system power is less than the threshold value TH1, the target temperature is set to the temperature TT1. In addition, when the system power is greater than the threshold value TH2, the target temperature is set to the temperature TT2 (TT2>TT1). In addition, when the system power is between the threshold values ​​TH1 and TH2, the target temperature is set to the temperature TT3 (TT2>TT3>TT1).

[0028] exist Figure 2 In the example shown, the system power roughly moves between the threshold values ​​TH1 and TH2. However, this example includes a time period when the system power is less than the threshold value TH1 and a time period when the system power is greater than the threshold value TH2. In the time period when the system power is less than the threshold value TH1, the target temperature is changed from the temperature TT3 to the temperature TT1 (TT1 < TT3). In the time period when the system power is greater than the threshold value TH2, the target temperature is changed from the temperature TT3 to the temperature TT2 (TT2 > TT3).

[0029] If the target temperature is changed in this way, the magnitude relationship between the target temperature and the actual temperature of the battery may be reversed before and after the target temperature is changed. If the magnitude relationship is reversed, the execution of the heater drive control may be affected. Figure 2 In the example shown, the heater is stopped (from on to off) after the system power decreases and falls below the threshold value TH1 and after the system power decreases and falls below the threshold value TH2. Also, the heater is started again (from off to on) after the system power increases and exceeds the threshold value TH1 and after the system power increases and exceeds the threshold value TH2.

[0030] Even when the target temperature is not changed, the heater driving is repeatedly stopped and the driving is restarted according to the magnitude relationship between the target temperature and the actual temperature of the battery. However, when the target temperature is changed, it is expected that the heater driving is repeatedly stopped and the driving is restarted compared to the case where this is not the case. As a result, when the total number of driving stops and restarts increases, components such as relays are easily worn out.

[0031] Therefore, in the embodiment, in the plug-in charging of the battery 24 using the external power source 10, the target temperature TT is updated only when the output power OP becomes larger. In the example already described, the larger the output power OP is, the higher the target temperature TT is set to. Therefore, updating the target temperature TT only when the output power OP becomes larger means that the update of the target temperature TT is allowed only when the temperature is changed to a high temperature. Therefore, compared with the case where the target temperature TT is changed to a high temperature and the target temperature TT is changed to a low temperature, the total number of stops and restarts of the drive can be suppressed. In addition, the shortening of the charging time caused by changing the target temperature TT to a high temperature can also be achieved.

[0032] Processing example Figure 3 This is a flowchart showing a process flow of drive control of the heater 25 particularly related to the embodiment. Figure 3 The routine shown is repeatedly executed by the processor of the control device 26 while the connector 11 is inserted into the charging cover 21 (ie, while the power is plugged in), for example.

[0033] Figure 3 The routine shown first acquires output power OP and actual temperature AT ( S11 ). Information on output power OP can be acquired from the external power source 10 or from the buck-boost unit 23 . Information on actual temperature AT is acquired from the temperature sensor 27 .

[0034] Following the processing of S11, it is determined whether the current value OP(k) of the output power OP exceeds the previous value OP(k-1) (S12). The current value OP(k) is the latest value of the output power OP acquired in the processing of S11. The previous value OP(k-1) is, for example, a past value of the output power OP acquired in the processing of S11 of the previous routine. In another example, the previous value OP(k-1) is the output power OP acquired at a predetermined time in the history of the output power OP before the acquisition time of the current value OP(k).

[0035] If the result of S12 is positive, the processing of S13 and S14 is performed. If not, the processing of S13 and S14 is skipped and the processing of S15 is performed. It should be noted that in the processing of S12, a simple comparison between the current value OP (k) and the previous value (k-1) can also be performed. In addition, in order to detect a significant increase in the output power OP while allowing some changes in the output power OP, the current value (k) can also be compared after adding the previous value (k-1) to the predetermined margin. In addition, there is no previous value (k-1) just after plugging in. Therefore, in this case, the processing of S13 and S14 is performed as an exception.

[0036] In the process of S13, the target temperature TT is set. The larger the output power OP is, the higher the target temperature TT is set. In the process of S14, the target temperature TT is updated using the latest target temperature TT set in the process of S13. In the case where the processes of S13 and S14 are not performed, the target temperature TT is not updated. In this case, the current value of the target temperature TT is maintained. The current value of the target temperature TT refers to the value set in the process of S13 before the last routine.

[0037] In the process of S15, it is determined whether the heater 25 is being driven. If the determination result of S15 is affirmative, the process of S16 is performed. If not, the process of S17 is performed.

[0038] In the processing of S16 and S17, the target temperature TT and the actual temperature AT are compared respectively. The target temperature TT is the latest value of the target temperature TT. The actual temperature AT is the latest value of the actual temperature AT acquired in the processing of S11. In the processing of S16, it is determined whether the actual temperature AT is above the target temperature TT. In the processing of S17, it is determined whether the actual temperature AT is lower than the target temperature TT. When the determination result of S16 is affirmative and the determination result of S17 is negative, the driving of the heater 25 is stopped (S18). When the determination result of S16 is negative and the determination result of S17 is affirmative, the heater 25 is driven (S19).

[0039] Other processing examples In an embodiment, it is also possible to Figure 3 A portion of the processing example (first processing example) described in is modified. Figure 4 It is a diagram for explaining the second processing example of the drive control of the heater. Figure 5 It is a diagram for explaining the third processing example of the drive control of the heater.

[0040] exist Figure 4 In the second processing example shown, the output power OP at the start of charging (time t0) is set as the reference value OPref. Then, during plug-in charging, it is determined whether the current value OP(k) exceeds the reference value OPref. This determination is performed, for example, Figure 3 Then, if it is determined that the current value OP(k) exceeds the reference value OPref, the processing of S12 is performed, and if it is determined that it is not, the processing of S12 is performed. Figure 3 The S15 process.

[0041] Next Figure 3 In the case where the process of S11 determines whether the current value OP(k) exceeds the reference value OPref, the following effects can be expected. That is, when the output power OP is large at the start of charging, it is assumed that the output power OP temporarily decreases during plug-in charging ( Figure 4 However, by increasing the output power OP in the period of time following the temporary reduction (for example, Figure 4 The above determination can be skipped Figure 3 Processing of S12-S14.

[0042] In the embodiment in which the target temperature TT is set to a higher temperature as the output power OP increases, when an increase in the output power OP followed by a temporary decrease occurs, a target temperature TT higher than the current value is not set. In this regard, by making the above determination, it is possible to avoid setting and updating the target temperature TT lower than the current value (i.e., Figure 3 The processing of S13 and S14) can maintain the current value of the target temperature TT.

[0043] exist Figure 5 In the third processing example shown, the maximum value OPmax of the output power OP from the start of charging to the present is recorded. Then, during plug-in charging, it is determined whether the current value OP(k) exceeds the maximum value OPmax. This determination is performed, for example, Figure 3 Then, if it is determined that the current value OP(k) exceeds the maximum value OPmax, the processing of S12 is performed, and if it is determined that it is not, the processing of S12 is performed. Figure 3The S15 process.

[0044] Next Figure 3 In the case where the process of S11 determines whether the current value OP(k) exceeds the maximum value OPmax, the following effects can be expected. That is, when the output power OP is small at the start of charging, it is assumed that the output power OP temporarily increases during plug-in charging ( Figure 5 Therefore, by making the above determination in the time period when the output power OP increases, it is possible to set and update the target temperature TT higher than the current value (ie, Figure 3 processing of S13 and S14).

[0045] In an embodiment in which the target temperature TT is set to a higher temperature as the output power OP is larger, the target temperature TT higher than the current value will not be set unless the output power OP exceeds the maximum value OPmax from the start of charging to the present. In this regard, by performing the above determination, when the output power OP exceeds the maximum value OPmax from the start of charging to the present, the target temperature TT can be reliably set and updated based on the latest maximum value OPmax. In addition, in the case that this is not the case, the target temperature TT set based on the maximum value OPmax from the start of charging to the present can be maintained.

Claims

1. A battery charging system, wherein: The battery charging system has: A battery capable of being charged using an external power source; a heater for increasing the temperature of the battery; and a control device for controlling the driving of the heater, The control device acquires the actual temperature of the battery and the output power of the external power source, sets a target temperature of the battery based on the output power, and drives the heater when the actual temperature is lower than the target temperature during charging of the battery using the external power source. The control device also compares the current value of the output power with the previous value of the output power during charging of the battery using the external power supply, and updates the target temperature based on the current value when the current value exceeds the previous value, and maintains the target temperature at the current value when the current value does not exceed the previous value.

2. The charging system according to claim 1, wherein: The control device also sets the output power value at the start of charging of the battery using the external power supply as a reference value, compares the current value with the reference value, and compares the current value with the previous value when the current value exceeds the reference value.

3. The charging system according to claim 1, wherein: The control device also records the maximum value of the output power after the start of charging of the battery using the external power supply, compares the current value with the maximum value, and compares the current value with the previous value when the current value exceeds the maximum value.

4. A method for charging a battery, wherein: The battery charging method comprises the following steps: acquiring an actual temperature of a battery capable of being charged using an external power source and output power of the external power source; setting a target temperature of the battery based on the output power; during charging of the battery using the external power supply, when the actual temperature is lower than the target temperature, driving a heater for raising the temperature of the battery; During charging of the battery using the external power source, comparing a current value of the output power with a previous value of the output power; as well as When the current value exceeds the previous value, the target temperature is updated based on the current value, and when the current value does not exceed the previous value, the target temperature is maintained at the current value.

Images