Charging control device

Abstract

The charging control device (15) calculates a learning instruction value of a charging parameter used in an initial period, i.e., a learning phase, of a charging control period of the secondary battery (11) based on the temperature of the secondary battery, operates a charger (14) in the learning phase to control the charging parameter to the learning instruction value, calculates a temperature rise rate, i.e., a learning temperature rise rate, of the secondary battery in the learning phase based on the temperature of the secondary battery, calculates a temperature rise rate, i.e., a charging temperature rise rate, of the secondary battery in the charging phase based on a limit temperature of the secondary battery and a length of the charging phase before the start of a charging phase following the learning phase, calculates a charging instruction value of the charging parameter from the start time to the end time of the charging phase based on the learning instruction value, the learning temperature rise rate, and the charging temperature rise rate, and operates the charger in the charging phase to control the charging parameter to the charging instruction value.

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2019-205714 filed on November 13, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a charge control device that controls the charge of a secondary battery. Background Art

[0004] As disclosed in Patent Document 1, a known control device controls the charging current of a secondary battery to a command current so that the secondary battery's temperature does not exceed its limit temperature. Specifically, the control device calculates the command current based on the limit temperature, the internal resistance of the secondary battery, and the battery's charging period. This prevents the secondary battery from overheating during charging control.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-108522. Summary of the Invention

[0008] Secondary batteries degrade over time. This degradation may alter the battery's temperature characteristics during charging. Furthermore, the battery's ambient temperature may change each time the battery is charged. Therefore, it is necessary to properly calculate the commanded value for the secondary battery's charging current or charging power to keep the battery's temperature within the specified temperature range, taking into account the effects of the secondary battery's degradation over time and the ambient temperature.

[0009] A main object of the present disclosure is to provide a charge control device capable of improving calculation accuracy of a command value of a charge current or charge power of a secondary battery so that the temperature of the secondary battery does not exceed a limit temperature.

[0010] The present disclosure provides a charging control device, which is applicable to a system including a secondary battery and a charger electrically connected to the secondary battery, and controls, through the charger, either a charging current or a charging power of the secondary battery, i.e., a charging parameter. The charging control device includes:

[0011] a learning command value calculation unit that calculates a learning command value of the charging parameter used in a learning phase that is an initial period of a charging control period of the secondary battery based on a temperature of the secondary battery;

[0012] a learning operation unit configured to operate the charger during the learning phase to control the charging parameter to the learning instruction value;

[0013] a learned temperature increase rate calculation unit that calculates a learned temperature increase rate based on the temperature of the secondary battery, the learned temperature increase rate being a rate of increase in the temperature of the secondary battery during the learning phase;

[0014] a charging temperature rise rate calculation unit that calculates a charging temperature rise rate based on a limit temperature of the secondary battery and a length of the charging phase before a charging phase following the learning phase begins during the charging control period, the charging temperature rise rate being a rate of increase in the temperature of the secondary battery during the charging phase;

[0015] a charging command value calculation unit that calculates a charging command value of the charging parameter from a start time to an end time of the charging phase based on the learned command value, the learned temperature increase rate, and the charging temperature increase rate; and

[0016] A charging operation unit operates the charger during the charging phase to control the charging parameter to the charging instruction value.

[0017] This disclosure calculates the rate of temperature rise of a secondary battery, or the learned temperature rise rate, when charging parameters are controlled to a learned command value during the initial learning phase of secondary battery charging control. Using the learned command value and the learned temperature rise rate, it is possible to quantify the appropriate temperature variation characteristics of the secondary battery, reflecting the current degradation state of the secondary battery and the ambient temperature.

[0018] In the present disclosure, the temperature rise rate of the secondary battery in the charging stage following the learning stage, that is, the temperature rise rate during charging, is calculated based on the limit temperature of the secondary battery and the length of the charging stage. Furthermore, in addition to the temperature rise rate during charging, the learning instruction value and the learned temperature rise rate are also used to calculate the charging instruction value. Since the learning instruction value and the learned temperature rise rate are calculated using the learning stage set during the same charging control period, they are values ​​that quantify the appropriate temperature change characteristics reflecting the current degradation state of the secondary battery and the ambient temperature. Therefore, by using the learning instruction value and the learned temperature rise rate in addition to the temperature rise rate during charging, it is possible to calculate the appropriate charging instruction value reflecting the current degradation state of the secondary battery and the ambient temperature. As a result, the calculation accuracy of the charging instruction value that keeps the temperature of the secondary battery from exceeding the limit temperature can be improved during the charging stage.

[0019] Furthermore, in the present disclosure, the charge command value for the period from the start to the end of the charging phase is calculated before the charging phase begins, and the calculated charge command value is primarily used during the charging phase. This prevents the period from starting to end charging of the secondary battery from significantly deviating from the charge control period. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description.

[0021] Figure 1 It is an overall configuration diagram of the in-vehicle charging system according to the first embodiment.

[0022] Figure 2 This is a diagram showing a control unit and sensors and the like as its peripheral configuration.

[0023] Figure 3 : is a flowchart showing the steps of the charging control process.

[0024] Figure 4 : is a flowchart showing the procedure of the correction process.

[0025] Figure 5 It is a diagram showing the relationship between temperature deviation and correction amount.

[0026] Figure 6 It is a timing chart showing an example of the charging control process.

[0027] Figure 7 1 is a flowchart showing the procedure of the charging control process according to the second embodiment.

[0028] Figure 8 : is a flowchart showing the steps of the charging control process.

[0029] Figure 9 It is a timing chart showing an example of the charging control process. DETAILED DESCRIPTION

[0030] <First embodiment>

[0031] Hereinafter, a first embodiment of the charge control device of the present disclosure will be described with reference to the accompanying drawings. The charge control device of this embodiment is mounted on a vehicle.

[0032] like Figure 1 As shown, vehicle 10 includes a secondary battery 11 and a rotating electric machine 12. Secondary battery 11 is, for example, a lithium-ion battery or a nickel-metal hydride battery, and in this embodiment, is assumed to be a battery pack. Rotating electric machine 12 is driven by power supplied from secondary battery 11 and serves as a driving power source for vehicle 10.

[0033] Vehicle 10 includes a battery monitoring device 13, a charger 14, and a control unit 15. Battery monitoring device 13 has the function of detecting the terminal voltage of each battery cell constituting secondary battery 11 and calculating the SOC of each battery cell. Charger 14 is a device for charging secondary battery 11 with power supplied from power supply equipment located outside vehicle 10.

[0034] like Figure 2 As shown, vehicle 10 includes a temperature sensor 20, a voltage sensor 21, and a current sensor 22. The temperature sensor 20 detects the temperature of the secondary battery 11, the voltage sensor 21 detects the terminal voltage of the secondary battery 11, and the current sensor 22 detects the current flowing through the secondary battery 11. The detection values ​​of the sensors 20 and 22, as well as information such as the SOC of the secondary battery 11 calculated by the battery monitoring device 13, are input to the control unit 15.

[0035] Based on the input detection values ​​and information, the control unit 15 controls charging of the secondary battery 11 from the charger 14. The functions provided by the control unit 15 may be provided by software stored in a physical memory device and a computer executing the software, hardware, or a combination thereof.

[0036] Next, the charge control process of the secondary battery 11 executed by the control unit 15 will be described. In this embodiment, the charge control period of the secondary battery 11 is composed of a learning phase, a constant current charging phase (equivalent to a "charging phase"), and a constant voltage charging phase.

[0037] Figure 3 The procedure of the charging control process of the secondary battery 11 is shown.

[0038] In step S10 , it is determined whether or not charging of the secondary battery 11 is permitted. If it is determined that charging is permitted, charging of the secondary battery 11 is started, and a charging current starts flowing into the secondary battery 11 .

[0039] In the next step S11 , it is determined whether the learning process is prohibited. In this embodiment, the learning process is determined to be prohibited when at least one of the first to third conditions described below is satisfied.

[0040] The first condition is that the charging current of the secondary battery 11 detected by the current sensor 22 (hereinafter referred to as the charging current detection value Ichr) is less than or equal to the specified current Ij. This condition determines whether the current charging mode is normal charging mode rather than high-speed charging mode. In other words, in this embodiment, the learning process is prohibited if the charging mode is normal charging mode.

[0041] The second condition is that the terminal voltage of the secondary battery 11 detected by the voltage sensor 21 (hereinafter referred to as the voltage detection value Vbr) is greater than or equal to the specified voltage Vj. This condition determines whether the learning phase can be maintained during the charging control period. Specifically, in this embodiment, the constant-voltage charging phase begins when the voltage detection value Vbr reaches its target voltage Vtgt. Therefore, if the voltage detection value Vbr is too high, a sufficient period for the learning phase cannot be ensured. Furthermore, the specified voltage Vj can be set to, for example, the same value as the target voltage Vtgt or a value slightly lower than the target voltage Vtgt.

[0042] The third condition is that the temperature of the secondary battery 11 detected by the temperature sensor 20 (hereinafter referred to as the temperature detection value Tbr) is above the predetermined temperature Tj. This condition determines whether the secondary battery 11 may have overheated during the charge control process. The process in step S11 corresponds to the "prohibition determination unit."

[0043] If it is determined in step S11 that the learning process is not prohibited, the process proceeds to step S12 to determine whether the conditions for starting the learning process are met. In this embodiment, if the fluctuation in the charging current detection value Ichr is determined to be less than a predetermined fluctuation amount, the charging current is determined to be stable and the conditions for starting the learning process are determined to be met.

[0044] If the starting conditions are determined to be met in step S12, the process proceeds to step S13, where the learning phase begins. In step S13, the temperature detection value Tbr and the state of charge (SOC) of the secondary battery 11 are acquired. Based on these acquired temperature detection value Tbr and SOC, the command learning current Ist (equivalent to the "learning command value"), which serves as the charging current command for the secondary battery 11 during the learning phase, is calculated. For example, the command learning current Ist can be calculated to decrease as the temperature detection value Tbr moves away from a reference temperature near 0°C toward the lower or higher temperature sides. Alternatively, the command learning current Ist can be calculated to increase as the SOC increases.

[0045] Alternatively, for example, the command learning current Ist may be calculated based on mapping information that defines the command learning current Ist in association with the temperature detection value Tbr and the SOC. This mapping information is stored in the memory 15a included in the control unit 15. The memory 15a is a non-transitory physical storage medium other than ROM (e.g., a non-volatile memory other than ROM).

[0046] Then, in step S13, the calculated command learning current Ist is set as the target current Itgt, and the charger 14 is operated to initiate feedback control of the detected charging current value Ichr (equivalent to the "charging parameter") to the target current Itgt. This initiates charging of the secondary battery 11 with the command learning current Ist. In this embodiment, the processing in step S13 corresponds to the "learning command value calculation unit" and the "learning operation unit."

[0047] In step S14 , based on the temperature detection value Tbr, it is determined whether the temperature increase ΔTr after the start of charging the secondary battery 11 with the command learning current Ist in the process of step S13 has reached a predetermined increase ΔTα (eg, 0.5° C.).

[0048] If the answer is yes in step S14, the process proceeds to step S15, where the learning period TA, the period from the start of charging the secondary battery 11 with the command learning current Ist in step S13 until the answer is yes in step S14, is calculated. The learned temperature rise rate dTst is then calculated by dividing the predetermined increase ΔTα by the calculated learning period TA. The process in step S15 corresponds to the "learned temperature rise rate calculation unit."

[0049] In step S16 , the charging temperature increase rate dTf is calculated using the following equation (eq1) based on the limit temperature Tlimit of the secondary battery 11 , the currently acquired temperature detection value Tbr, ie, the initial temperature Tini, and the predetermined period TL.

[0050] [Mathematical formula 1]

[0051]

[0052] In this embodiment, the specified period TL is set to an assumed value for the length of the constant-current charging phase. Since the length of the constant-current charging phase may vary depending on factors such as the SOC of the secondary battery 11 before charging begins, the actual length of the constant-current charging phase may deviate from the assumed value. Furthermore, the limit temperature Tlimit is set, for example, to the upper limit temperature of the secondary battery 11 that prevents degradation of the secondary battery 11.

[0053] Then, in step S16, based on the calculated charging temperature rise rate dTf, the learned temperature rise rate dTst calculated in step S15, and the command learning current Ist calculated in step S13, the command charging current I* (equivalent to the "charging command value") is calculated using the following equation (eq2).

[0054] [Mathematical formula 2]

[0055]

[0056] The above equation (eq2) is derived by setting the condition "R1 = R2" in the following equation (eq3), which shows the relationship between the calorific value and temperature rise rate of secondary battery 11 during the learning phase and the calorific value and temperature rise rate of secondary battery 11 during the constant current charging phase. R1 represents the internal resistance of secondary battery 11 during the learning phase, and R2 represents the internal resistance of secondary battery 11 during the constant current charging phase.

[0057] [Mathematical formula 3]

[0058]

[0059] During a short charging period, changes in the ambient temperature and internal resistance of the secondary battery 11 can be ignored. Therefore, the above equation (eq3) can be approximated as the above equation (eq2). In addition, the processing of step S16 corresponds to the "heat rise rate calculation unit during charging" and the "charge command value calculation unit."

[0060] Then, in step S17, the calculated command charging current I* is set as the target current Itgt, and the process of feedback-controlling the detected charging current value Ichr to the target current Itgt begins by operating the charger 14. This initiates the constant-current charging phase, and charging of the secondary battery 11 begins at the command charging current I*. In this embodiment, the process of step S17 corresponds to the "charging operation unit."

[0061] In the present embodiment, the command charging current I* calculated in step S16 is basically used as the target current Itgt from the start of the constant current charging phase until the prescribed period TL has passed. This is because in the present embodiment, the vehicle 10 does not include a cooling device such as a fan and a cooling water channel for cooling the secondary battery 11. That is, in this case, during the charging of the secondary battery 11, if the temperature of the secondary battery 11 becomes high, it is impossible to immediately reduce the temperature, and the temperature of the secondary battery 11 may exceed the limit temperature Tlimit. In particular, when charging while the vehicle is parked, the air cooling effect of the secondary battery 11 accompanying the driving of the vehicle 10 cannot be expected, and the possibility of the temperature of the secondary battery 11 exceeding the limit temperature Tlimit becomes greater. Therefore, before the start of the constant current charging phase, the command charging current I* is determined so that the temperature of the secondary battery 11 does not exceed the limit temperature Tlimit. In the constant current charging phase, the above-mentioned command charging current I* is basically set as the target current Itgt.

[0062] In the next step S18, correction processing is performed. Figure 4 The steps of the correction process are shown.

[0063] In step S30, an estimated temperature value Test of secondary battery 11 is calculated based on the initial temperature Tini, the charging temperature rise rate dTf, and the time elapsed since charging of secondary battery 11 with the commanded charging current I* was initiated in step S17. Specifically, the estimated temperature value Test is calculated by adding the product of the charging temperature rise rate dTf and the elapsed time to the initial temperature Tini. The process of step S30 corresponds to the "temperature estimation unit."

[0064] In step S31 , the temperature deviation Terr is calculated by subtracting the temperature estimation value Test from the acquired current temperature detection value Tbr.

[0065] In step S32, it is determined whether the temperature deviation Terr is equal to or greater than a threshold value Tth (>0). The threshold value Tth in step S32 corresponds to the "first threshold value".

[0066] If a positive determination is made in step S32, the process proceeds to step S33, where the command value correction amount ΔIchg is set to a negative value. Figure 5 As shown, the greater the absolute value of the positive temperature deviation Terr is, the greater the absolute value of the negative command value correction amount ΔIchg is set.

[0067] After completing step S33, the process proceeds to step S34, where the command charge current I* calculated in step S16 is added to the command value correction amount ΔIchg set in step S33 to calculate a corrected command charge current I*. This corrects the command charge current I* calculated in step S16 to decrease it. This corrected command charge current I* is then used as the target current Itgt.

[0068] If it is determined in step S32 that the temperature deviation Terr is smaller than the threshold value Tth, the process proceeds to step S35 to determine whether the temperature deviation Terr is equal to or smaller than “−Tth.” Note that “−Tth” in step S35 corresponds to the “second threshold value.”

[0069] If a positive determination is made in step S35, the process proceeds to step S36, where the command value correction amount ΔIchg is set to a positive value. Figure 5 As shown, the greater the absolute value of the negative temperature deviation Terr is, the greater the absolute value of the positive command value correction amount ΔIchg is set.

[0070] After completing step S36, the process proceeds to step S34, where the command charge current I* calculated in step S16 is added to the command value correction amount ΔIchg set in step S36 to calculate a corrected command charge current I*. This increases the command charge current I* calculated in step S16. This corrected command charge current I* is then used as the target current Itgt. The processes of steps S32 through S36 constitute the "correction unit."

[0071] If it is determined in step S35 that the temperature deviation Terr is greater than "-Tth", the process proceeds to step S37, where the command value correction amount ΔIchg is set to 0 (see Figure 5 ) When the process proceeds to step S34 after the completion of step S37, the command charging current I* calculated in step S16 is not corrected.

[0072] The correction process described above is performed in consideration of the fact that the SOC and temperature of the secondary battery 11 change during the learning phase and the constant current charging phase, and the internal resistance of the secondary battery 11 changes depending on the SOC and temperature.

[0073] Back to the previous Figure 3 As explained above, after the processing of step S18 is completed, the process proceeds to step S19 to determine whether the constant current charging stage is completed. Specifically, when it is determined that the voltage detection value Vbr reaches the target voltage Vtgt, it is determined that the constant current charging stage is completed. In the case of a negative determination in step S19, the process proceeds to step S18. On the other hand, in the case of an affirmative determination in step S19, in this embodiment, the process proceeds to the constant voltage charging stage. In the constant voltage charging stage, the secondary battery 11 is charged by feedback controlling the voltage applied from the charger 14 to the secondary battery 11 to be the target voltage Vtgt.

[0074] If a negative determination is made in step S12, the learning phase is not set and the process transitions to the constant current charging phase. Specifically, in step S20, the command charging current I* is calculated for the case where the learning phase is not set. Furthermore, in step S21, the calculated command charging current I* is set as the target current Itgt, and the process of feedback control of the charging current detection value Ichr to the target current Itgt is initiated through the operation of the charger 14. Furthermore, in step S22, a correction process is performed similarly to step S18, and in step S23, a determination is made as to whether the constant current charging phase has ended, similarly to step S19.

[0075] Figure 6 An example of charging control processing is shown. Figure 6 (a) shows the change of the target current Itgt. Figure 6 (b) shows the change of the voltage detection value Vbr. Figure 6 (c) shows the transition of the temperature detection value Tbr and the temperature estimation value Test.

[0076] The learning phase starts at time t1, and the command learning current Ist is set to the target current Itgt. Then, the learning temperature rise rate dTst is calculated in step S15, and the charging temperature rise rate dTf and the command charging current I* are calculated in step S16.

[0077] At time t2 , the constant current charging phase begins, and the command charging current I* is set to the target current Itgt.

[0078] Then, at time t3, it is determined that the temperature deviation Terr exceeds the estimated temperature value Test by a threshold value Tth or more. Therefore, a correction is implemented to reduce the commanded charging current I*. To avoid sudden changes in the commanded charging current I* before and after the correction, it is ideal to gradually change the commanded charging current I*. Furthermore, at time t4, the detected voltage value Vbr reaches the target voltage Vtgt, and the constant-voltage charging phase begins.

[0079] According to the present embodiment described in detail above, the following effects can be obtained.

[0080] During the learning phase, the learned temperature rise rate dTst, the rate of temperature rise of secondary battery 11, is calculated when the detected charging current value Ichr is feedback-controlled to the command learning current Ist. Using the command learning current Ist and the learned temperature rise rate dTst, the appropriate temperature change characteristics of secondary battery 11, reflecting the current degradation state of secondary battery 11 and the ambient temperature, can be quantified.

[0081] Next, based on the difference between the limit temperature Tlimit and the initial temperature Tini of the secondary battery 11 and the predetermined period TL, the charge temperature rise rate dTf, the rate of temperature rise of the secondary battery 11 during the constant current charging phase following the learning phase, is calculated. Furthermore, in addition to the charge temperature rise rate dTf, the command learning current Ist and the learned temperature rise rate dTst are also used to calculate the command charging current I*. Because the command learning current Ist and the learned temperature rise rate dTst are calculated during the learning phase set within the same charging control period, they quantify appropriate temperature variation characteristics that reflect the current degradation state of the secondary battery 11 and the ambient temperature. Therefore, by using the command learning current Ist and the learned temperature rise rate dTst in addition to the charge temperature rise rate dTf, an appropriate command charging current I* that reflects the current degradation state of the secondary battery 11 and the ambient temperature can be calculated. As a result, an appropriate command charging current I* that keeps the temperature of the secondary battery 11 from exceeding the limit temperature Tlimit during the constant current charging phase can be calculated.

[0082] Furthermore, before the constant-current charging phase begins, the command charging current I* is calculated for the period from the start to the end of the constant-current charging phase. This calculated command charging current I* is essentially used during the constant-current charging phase. This prevents the period from starting to end charging of the secondary battery 11 from significantly deviating from the charging control period.

[0083] The learned temperature rise rate dTst is calculated by dividing the specified temperature rise amount ΔTα by the learning period TA required to bring the temperature rise amount ΔTr to the specified temperature rise amount ΔTα. This calculation method allows the learned temperature rise rate dTst to be calculated after the temperature of the secondary battery 11 has risen to a certain level, even in situations where the temperature of the secondary battery 11 is unlikely to rise. This improves the accuracy of the calculation of the learned temperature rise rate dTst, and consequently, the accuracy of the calculation of the command charging current I*. On the other hand, if the temperature of the secondary battery 11 is likely to rise, the waiting time in step S41 is shortened compared to situations where the temperature is unlikely to rise, thus terminating the learning phase earlier.

[0084] If it is determined in step S11 that the learning process is prohibited, the process shifts to the constant current charging phase rather than the learning phase, thereby avoiding the learning process being performed under conditions where the calculation accuracy of the command learning current Ist and the learning temperature rise rate dTst is reduced.

[0085] After the constant-current charging phase begins, if the temperature deviation Terr (the difference between the detected temperature value Tbr and the estimated temperature value Test) exceeds a threshold value Tth or higher, the command charging current I* is reduced. On the other hand, if the temperature deviation Terr falls by -Tth or higher, the command charging current I* is increased. This allows the temperature of the secondary battery 11 to remain within the limit temperature Tlimit, even if the command charging current I* determined before the constant-current charging phase begins deviates from the appropriate value.

[0086] <Modification of the First Embodiment>

[0087] ·You can also Figure 4 The absolute value of the threshold value (>0) used in step S32 and the absolute value of the threshold value (<0) used in step S35 are set to different values.

[0088] ·You can also Figure 3 In step S11, any one or two of the first to third conditions are used as conditions for determining whether to prohibit the learning process.

[0089] You can also Figure 3 Step S14 calculates the amount of increase in temperature detection value Tbr from the start of charging of secondary battery 11 with command learning current Ist in step S13 until the predetermined period has elapsed. In this case, step S15 calculates the learned temperature rise rate dTst by dividing the amount of increase in temperature detection value Tbr by the predetermined period.

[0090] ·You can also Figure 3 In step S13, the voltage detection value Vbr is used to calculate the command learning current Ist. In addition, the SOC may not be used in the calculation of the command learning current Ist.

[0091] <Second embodiment>

[0092] The following describes the second embodiment with reference to the accompanying drawings, focusing on the differences from the first embodiment. In this embodiment, multiple (two) learning stages are set during the initial charging control period. This setting is designed to further improve the calculation accuracy of the command charging current, given the positive correlation (specifically, a proportional relationship) between the command learning current and the learned temperature rise rate.

[0093] Figure 7 、 Figure 8 The steps of the charging control process of this embodiment are shown. Figure 7 、 Figure 8 For convenience, Figure 3The same processes are denoted by the same symbols.

[0094] If a positive determination is made in step S12, the process proceeds to step S40. In step S40, the detected temperature value Tbr and the SOC are acquired. Based on these values, the first command learning current Ist1 for the first learning phase is calculated. The calculated first command learning current Ist1 is then set as the target current Itgt. The charger 14 is then operated to initiate feedback control of the detected charging current value Ichr to the target current Itgt. This initiates charging of the secondary battery 11 with the first command learning current Ist1.

[0095] In step S14 , based on the temperature detection value Tbr, it is determined whether the temperature increase ΔTr1 after the start of charging of the secondary battery 11 with the first command learning current Ist1 in the process of step S40 has reached a predetermined increase ΔTα.

[0096] If the answer is yes in step S14, the process proceeds to step S42, where the first learning period TA1, the period from the start of charging the secondary battery 11 with the first command learning current Ist1 in step S40 until the answer is yes in step S41, is calculated. The first learned temperature increase rate dTst1 is then calculated by dividing the predetermined temperature increase amount ΔTα by the calculated first learning period TA1.

[0097] In step S42, the first charging temperature rise rate dTf1 is calculated using the following equation (eq4) based on the current temperature limit Tlimit of the secondary battery 11, the currently detected temperature value Tbr (i.e., the first initial temperature Tini1), and the first predetermined period TL1. The first predetermined period TL1 is set, for example, to a value obtained by adding the assumed lengths of the second learning phase and the constant current charging phase.

[0098] [Formula 4]

[0099]

[0100] In the next step S43, the temperature detection value Tbr and the SOC are acquired. Based on these acquired temperature detection values ​​Tbr and SOC, a second command learning current Ist2 is calculated for the second learning phase. In this embodiment, the second command learning current Ist2 is set to a value greater than the first command learning current Ist1. Furthermore, the calculated second command learning current Ist2 is set as the target current Itgt. Through the operation of the charger 14, feedback control of the charging current detection value Ichr to the target current Itgt begins. Thus, charging of the secondary battery 11 begins with the second command learning current Ist2.

[0101] In step S44 , based on the temperature detection value Tbr, it is determined whether the temperature increase ΔTr2 after the start of charging of the secondary battery 11 with the second command learning current Ist2 in the process of step S43 has reached a predetermined increase ΔTα.

[0102] If the answer is yes in step S44, the process proceeds to step S45, where the second learning period TA2, the period from the start of charging the secondary battery 11 with the second command learning current Ist2 in step S43 until the answer is yes in step S44, is calculated. The second learned temperature increase rate dTst2 is then calculated by dividing the predetermined temperature increase amount ΔTα by the calculated second learning period TA2.

[0103] In step S45, the second charging temperature rise rate dTf2 is calculated using the following formula (eq5) based on the limit temperature Tlimit of the secondary battery 11, the temperature detection value Tbr obtained at the current moment, that is, the second initial temperature Tini2, and the second predetermined period TL2. In this embodiment, the second predetermined period TL2 is set to an assumed value of the length of the constant current charging stage, which is shorter than the first predetermined period TL1.

[0104] [Formula 5]

[0105]

[0106] In the next step S46 , a first command charging current I1* is calculated using the following equation (eq6) based on the first charge temperature increase rate dTf1 and the first learned temperature increase rate dTst1 calculated in step S42 and the first command learning current Ist1 calculated in step S40 .

[0107] [Formula 6]

[0108]

[0109] Furthermore, based on the second charge temperature increase rate dTf2 and the second learned temperature increase rate dTst2 calculated in step S45 and the second command learning current Ist2 calculated in step S43 , the second command charging current I2* is calculated using the following equation (eq7).

[0110] [Formula 7]

[0111]

[0112] In the next step S47, a determination is made as to whether the calculated first command charging current I1* and the calculated second command charging current I2* are equal. Specifically, if the absolute value of the difference between the first command charging current I1* and the second command charging current I2* is less than or equal to a predetermined value, the determination is made that the first command charging current I1* and the second command charging current I2* are equal. The predetermined value is set to a small value near zero.

[0113] If the command charging currents I1* and I2* are determined to be equal in step S47, the process proceeds to step S48, where either command charging current I1* or I2* is selected as the command charging current I*. The reason why either command charging current I1* or I2* can be used as the command charging current I* is that the reliability of either command charging current I1* or I2* is considered high. Specifically, due to the proportional relationship between the command learning current and the learned temperature increase rate, the first command charging current I1* calculated based on the first command learning current Ist1 and the first learned temperature increase rate dTst1 and the second command charging current I2* calculated based on the second command learning current Ist2 and the second learned temperature increase rate dTst2 are substantially the same value.

[0114] Furthermore, in step S48, the learning stage set in the next charging control period of the secondary battery 11 is set to one. Thus, in the next charging control, the first embodiment is performed. Figure 3 As a result, in the next charging control, the charging efficiency of the secondary battery 11 can be improved, and the period from the start to the end of charging of the secondary battery 11 can be shortened.

[0115] On the other hand, if it is determined in step S47 that they are not equal, the process proceeds to step S49, where the smaller of the command charging currents I1* and I2* is selected as the command charging current I*. In other words, the smaller of the first charging temperature rise rate dTf1 and the second learned temperature rise rate dTst2 is used to calculate the command charging current used in step S50. The processing in step S49 allows the safer command charging current to be used as the command charging current during the constant current charging phase, preventing the temperature of the secondary battery 11 from exceeding the limit temperature Tlimit.

[0116] Furthermore, in step S49, the learning stage set in the next charge control period of the secondary battery 11 is maintained at two. Thus, in the next charge control, Figure 7 、 Figure 8 The processing shown.

[0117] In the following step S50, the command charging current I* calculated in step S48 or step S49 is set as the target current Itgt. The charger 14 is then operated to feedback-control the detected charging current value Ichr to the target current Itgt. This initiates the constant-current charging phase, and charging of the secondary battery 11 begins at the command charging current I*.

[0118] Figure 9 An example of charging control processing is shown. Figure 9 (a) shows the change of the target current Itgt. Figure 9 (b) shows the transition of the temperature detection value Tbr and the temperature estimation value Test.

[0119] At time t1, the first learning phase starts, and the first instruction learning current Ist1 is set as the target current Itgt. Then, through the process of step S42, the first learned temperature increase rate dTst1 and the first charging temperature increase rate dTf1 are calculated.

[0120] At time ta, the second learning phase begins, and the second instruction learning current Ist2 is set to the target current Itgt. Then, through the processing of step S45, the second learning temperature rise rate dTst2 and the second charging temperature rise rate dTf2 are calculated. Furthermore, through the processing of steps S46 to S50, the instruction charging current I* is calculated, and the constant current charging phase begins at time t2. In addition, at the subsequent time t3, the same method as the first embodiment is implemented. Figure 6 With the same modification, the constant voltage charging phase begins at time t4.

[0121] <Other Implementation Methods>

[0122] In addition, each of the above-mentioned embodiments can also be implemented with the following modifications.

[0123] In the second embodiment, the first command learning current Ist1 may be smaller than the second command learning current Ist2. Alternatively, the first command learning current Ist1 and the second command learning current Ist2 may be the same value.

[0124] In the second embodiment, three or more learning stages may be set.

[0125] · It is also possible to Figure 3In step S13, based on the temperature detection value Tbr and the SOC, the command value for charging power of the secondary battery 11 during the learning phase, namely the command learning power Pst (equivalent to the "learning command value"), is calculated. For example, the command learning power Pst can be calculated to decrease as the temperature detection value Tbr moves away from a reference temperature near 0°C toward the lower or higher side. Alternatively, the command learning power Pst can be calculated to increase as the SOC increases.

[0126] The calculated command learning power Pst is then set as the target power Ptgt, and the process of feedback-controlling the charging power Pchr (equivalent to the "charging parameter") to the target power Ptgt is initiated by operating the charger 14. Here, the charging power Pchr can be calculated, for example, as the product of the charging current detection value Ichr and the voltage detection value Vbr.

[0127] Then, in step S16, the command charging power P* (equivalent to the "charge command value") is calculated using the following equation (eq8) based on the calculated charging temperature rise rate dTf, the learned temperature rise rate dTst calculated in step S15, and the command learning power Pst calculated in step S13. In deriving equation (eq8), an approximation is made that disregards changes in the terminal voltage of the secondary battery 11 during the learning phase.

[0128] [Formula 8]

[0129]

[0130] Then, in step S17, the calculated command charging power P* is set as the target power Ptgt, and the process of feedback control of charging power Pchr to target power Ptgt begins through the operation of charger 14. This begins the constant power charging phase (equivalent to the "charging phase"), which continues until an affirmative determination is made in step S19.

[0131] Note that the command correction amount in step S18 is the correction amount of electric power, not the correction amount of current.

[0132] The system may include a second temperature sensor provided near the secondary battery 11 and detecting a temperature of a member correlated with the temperature of the secondary battery 11. In this case, the temperature of the secondary battery 11 used for charge control can be calculated based on the detection value of the second temperature sensor.

[0133] The present disclosure can also be applied to a system that is not installed in a vehicle.

[0134] The control unit and the method thereof described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory, and the processor is programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and the method of the control unit described in the present disclosure may be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and the method of the control unit described in the present disclosure may be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor composed of one or more hardware logic circuits. In addition, the computer program may also be stored in a computer-readable non-transitory tangible storage medium as an instruction executed by a computer.

[0135] While the present disclosure has been described based on embodiments, it should be understood that the present disclosure is not limited to the aforementioned embodiments and structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combinations and methods, including combinations and methods based on a single element, or combinations and methods above or below these elements, also fall within the scope and spirit of the present disclosure.

Claims

1. A charging control device, adapted for use in a system including a secondary battery and a charger electrically connected to the secondary battery, wherein the charging control device controls, via the charger, either a charging current or a charging power of the secondary battery, i.e., a charging parameter. The charging control device includes: a learning command value calculation unit that calculates a learning command value of the charging parameter used in a learning phase that is an initial period of a charging control period of the secondary battery based on a temperature of the secondary battery; a learning operation unit configured to operate the charger during the learning phase to control the charging parameter to the learning instruction value; a learned temperature increase rate calculation unit that calculates a learned temperature increase rate based on the temperature of the secondary battery, the learned temperature increase rate being a rate of increase in the temperature of the secondary battery during the learning phase; a charging temperature rise rate calculation unit that calculates a charging temperature rise rate based on a limit temperature of the secondary battery and a length of the charging phase before a charging phase following the learning phase begins during the charging control period, the charging temperature rise rate being a rate of increase in the temperature of the secondary battery during the charging phase; a charging command value calculation unit that calculates a charging command value of the charging parameter from a start time to an end time of the charging phase based on the learned command value, the learned temperature increase rate, and the charging temperature increase rate; as well as A charging operation unit operates the charger during the charging phase to control the charging parameter to the charging instruction value.

2. The charging control device according to claim 1, wherein: The charge-time temperature increase rate calculation unit calculates the charge-time temperature increase rate based on a difference between an initial temperature of the secondary battery in the charge phase and the limit temperature and a length of the charge phase.

3. The charging control device according to claim 1, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate based on a time required for the temperature increase amount of the secondary battery to reach a predetermined increase amount and the predetermined increase amount.

4. The charging control device according to claim 2, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate based on a time required for the temperature increase amount of the secondary battery to reach a predetermined increase amount and the predetermined increase amount.

5. The charging control device according to any one of claims 1 to 4, characterized in that: A prohibition determination unit is included that determines whether to prohibit operation of the charger by the learning operation unit and calculation of the learned temperature increase rate by the learned temperature increase rate calculation unit based on at least one of the temperature, voltage, and charging current of the secondary battery.

6. The charging control device according to any one of claims 1 to 4, characterized in that: include: a temperature estimating unit configured to estimate the temperature of the secondary battery based on the temperature increase rate during charging each time during the charging phase; a temperature acquiring unit configured to acquire a temperature of the secondary battery; as well as A correction unit, which, during the charging stage, makes a reduction correction to the calculated charging instruction value when the acquired temperature of the secondary battery is higher than the temperature estimated by the temperature estimating unit by more than a first threshold value, and makes an increase correction to the calculated charging instruction value when the acquired temperature of the secondary battery is lower than the temperature estimated by the temperature estimating unit by more than a second threshold value.

7. The charging control device according to any one of claims 1 to 4, characterized in that: A plurality of the learning stages are set in an initial period of the charging control period.

8. The charging control device according to claim 7, characterized in that: The learning command value calculation unit sets the learning command values ​​used in the respective learning stages to different values.

9. The charging control device according to claim 7, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate in each of the learning stages and determines whether the calculated learned temperature increase rates are equal to each other. When it is determined that the learned temperature increase rates are equal, the charge command value calculation unit uses any one of the calculated learned temperature increase rates to calculate the charge command value used in the charge operation unit.

10. The charging control device according to claim 8, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate in each of the learning stages and determines whether the calculated learned temperature increase rates are equal to each other. When it is determined that the learned temperature increase rates are equal, the charge command value calculation unit uses any one of the calculated learned temperature increase rates to calculate the charge command value used in the charge operation unit.

11. The charging control device according to claim 7, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate in each of the learning stages and determines whether the calculated learned temperature increase rates are equal to each other. If it is determined that the learned temperature increase rates are not equal, the charge command value calculation unit uses the smallest learned temperature increase rate among the calculated learned temperature increase rates to calculate the charge command value used in the charging operation unit.

12. The charging control device according to claim 7, wherein: The learned temperature increase rate calculation unit calculates the learned temperature increase rate in each of the learning stages and determines whether the calculated learned temperature increase rates are equal to each other. If it is determined that the learned temperature increase rates are equal, the learning stage set in the next charge control period of the secondary battery is set to one.

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