JP2020099127A - Battery temperature management device - Google Patents

Abstract

To provide a battery temperature management device for managing the temperature of a nickel-metal hydride battery mounted on a vehicle, and capable of suppressing a rise in battery temperature while preventing unnecessary discharge after travel completion.SOLUTION: A BCU13 configuring a battery temperature management device 1 is provided with: a discharge-necessity determination section 132 for determining whether or not discharging after travel completion is necessary on the basis of whether or not an index value that correlates with temperature rise of a battery pack 11 after travel completion (for example, charge/discharge amperage of the battery pack 11 immediately before travel completion, etc.) is a predetermined threshold value or more; and a discharge control section 133 for driving a discharge circuit 40 to discharge when discharging is determined to be necessary.SELECTED DRAWING: Figure 1

Description

The present invention relates to a battery temperature management device.

In recent years, a hybrid vehicle (HV) and a plug-in hybrid vehicle (PHV) capable of effectively improving the fuel consumption rate (fuel consumption) of a vehicle by using an engine and an electric motor together have been widely put into practical use. .. An electric vehicle (EV) that uses only an electric motor as a power source and does not emit exhaust gas has also been put into practical use. For example, in such hybrid vehicles and electric vehicles, an assembled battery (battery module) in which a plurality of secondary batteries (battery cells) such as nickel-hydrogen batteries are connected in series is used.

By the way, in a nickel-hydrogen battery, the battery temperature may increase after charging due to reaction heat due to self-discharge. More specifically, in the nickel-hydrogen battery, as shown by the following chemical formula (1), nickel hydroxide (II) (Ni(OH) ₂ ) on the positive electrode side is hydroxide ion (OH-) at the time of charging. To form nickel hydroxide (NiOOH) and water (H ₂ O).
Ni(OH) ₂ +OH ⁻ →NiOOH+H ₂ O+e ⁻ (1)
Here, nickel hydroxide (NiOOH) is classified into a stable β type and an unstable γ type, and the γ type has nickel hydroxide (II) (Ni(OH) as shown by the following chemical formula (2). ) ₂ ) self-decomposes to generate oxygen.
4NiOOH+2H ₂ O→4Ni(OH) ₂ +O ₂ ... (2)
Then, oxygen binds to the metal hydride on the negative electrode side, and as shown by the following chemical formula (3), water is generated and reaction heat is generated.
4MH+O ₂ → 4M+2H ₂ O+ heat of reaction (3)
As a result, the performance of the nickel-hydrogen battery may be deteriorated or an abnormal temperature may be reached.

On the other hand, in Patent Document 1, it is possible to suppress an increase in the maximum value of the battery temperature and yet to uniformly charge all the cells of a battery pack including a plurality of nickel hydrogen batteries (cells) uniformly. A secondary battery charging device is disclosed. More specifically, in this charging device, in a charging device for a secondary battery that charges an assembled battery in which a plurality of secondary battery cells are connected in series, the secondary battery is charged until it is fully charged, and immediately after completion of charging. During a short time, preparatory discharge with a predetermined discharge current is performed.

According to this charging device, the temperature rise after charging can be suppressed by performing a small amount of preliminary discharge immediately after the completion of charging. More specifically, by performing the preparatory discharge immediately after the completion of charging, the oxygen gas generated in the positive electrode during the charging process is absorbed by the positive electrode, and as a result, the chemical reaction that recombines with hydrogen to generate water is suppressed. Therefore, it is possible to suppress an increase in the peak of the battery temperature. Therefore, all the cells of the battery pack can be fully charged evenly without any problem due to temperature rise.

JP, 2007-89363, A

However, in the above-described charging device, the preparatory discharge is always performed after the full charge is completed, that is, the preparatory discharge is performed even when it is not necessary to perform the preparatory discharge, so that the loss of power may increase. is there. Further, in the above-described charging device, since the situation other than the time when the full charge is completed is not considered, that is, the preparatory discharge is not performed except the time when the full charge is completed. If the vehicle is stopped and ready-off (that is, the contactor is opened) in that state, the temperature of the assembled battery (battery module) may rise after the traveling is completed. is there.

The present invention has been made to solve the above problems, and in a battery temperature management device for managing the temperature of a nickel-hydrogen battery (battery) mounted in a vehicle, unnecessary discharge is generated after traveling. It is an object of the present invention to provide a battery temperature management device capable of preventing the battery temperature from rising while preventing it.

A battery temperature management device according to the present invention is a discharging unit that discharges a nickel-hydrogen battery via a discharging resistor, and an index-value acquiring unit that acquires an index value having a correlation with a temperature increase of the nickel-hydrogen battery after traveling. And a discharge necessity determining means for determining whether or not it is necessary to discharge after traveling based on whether the index value acquired by the index value acquiring means is equal to or more than a predetermined threshold value, Discharging control means for driving the discharging means to perform discharging when the necessity determining means determines that discharging is required.

According to the battery temperature management device of the present invention, the index value having a correlation with the temperature rise of the nickel-hydrogen battery after traveling is acquired, and whether or not the acquired index value is equal to or more than a predetermined threshold value Based on the result, it is determined whether or not discharging is necessary after the traveling is completed, and when it is determined that discharging is necessary, discharging is performed. Therefore, the amount of γ-type nickel hydroxide (NiOOH) accumulated on the surface of the positive electrode after charging is removed by discharging, so that the amount of self-decomposition of γ-type nickel hydroxide is reduced and the temperature rise of the battery can be suppressed. it can. As a result, it is possible to prevent the battery temperature from rising while preventing unnecessary discharge after the traveling ends.

In the battery temperature management device according to the present invention, the index value acquisition means has a charge/discharge current amount acquisition means for acquiring the charge/discharge current amount in a predetermined period immediately before the end of traveling, and the discharge necessity determination means is the charge/discharge current. It is preferable to determine whether or not it is necessary to discharge, based on whether or not the amount of charging/discharging current acquired by the amount acquiring means is equal to or more than a predetermined threshold value.

In this case, it is determined whether or not it is necessary to discharge, based on whether or not the charge/discharge current amount is equal to or greater than a predetermined threshold value. Therefore, it becomes possible to accurately determine the necessity of discharging based on the charge/discharge current amount that correlates with the temperature rise of the nickel-hydrogen battery.

In the battery temperature management device according to the present invention, the index value acquisition means acquires a plurality of index values having a correlation with the temperature increase of the nickel-hydrogen battery after the end of traveling, and the discharge necessity determination means determines the plurality of index values respectively. Regarding, regarding each index value is greater than or equal to a corresponding predetermined threshold value, weighting is given, and discharge is necessary when the sum of weighting of each of the plurality of index values is greater than or equal to a predetermined discharge determination threshold value. It is preferable to judge that

In this case, a plurality of index values having a correlation with the temperature increase of the nickel-hydrogen battery after traveling is acquired, and for each of the plurality of index values, when each index value is equal to or greater than a corresponding predetermined threshold value, weighting is performed. Is given, and it is determined that the discharge is necessary when the total sum of the weights of the plurality of index values is equal to or more than a predetermined discharge determination threshold value. Therefore, by using a plurality of index values and the sum of their weighting, it becomes possible to more accurately determine the necessity of discharging.

In the battery temperature management device according to the present invention, the index value acquisition means, the charge/discharge current amount acquisition means for acquiring the charge/discharge current amount of the nickel-hydrogen battery in the predetermined period immediately before the end of traveling, and the charge state of the nickel-hydrogen battery. It is preferable to have a charge state acquisition means for acquiring.

By doing so, it is possible to more accurately determine the necessity of discharging by considering the charging/discharging current amount and the charging state of the nickel-hydrogen battery, which has a correlation with the temperature increase of the nickel-hydrogen battery after traveling. It will be possible.

In the battery temperature management device according to the present invention, it is preferable that the index value acquisition unit further includes a battery temperature detection unit that detects the battery temperature of the nickel hydrogen battery.

By doing so, it becomes possible to more accurately determine the necessity of discharging by further considering the battery temperature of the nickel-hydrogen battery having a correlation with the temperature increase of the nickel-hydrogen battery after traveling.

In the battery temperature management device according to the present invention, it is preferable that the index value acquisition unit further includes an environmental temperature detection unit that detects an environmental temperature around the nickel hydrogen battery.

By doing this, it is possible to more accurately determine the necessity of discharging by further considering the environmental temperature around the nickel-hydrogen battery, which has a correlation with the temperature increase of the nickel-hydrogen battery after traveling. Become.

In the battery temperature management device according to the present invention, the discharge necessity determination means determines, for each of the plurality of index values, a predetermined threshold value corresponding to each index value when each index value is equal to or higher than a corresponding predetermined threshold value. It is preferable that weighting is given according to the deviation from the threshold value, and it is determined that the discharge is necessary when the sum of the weighting of each of the plurality of index values is equal to or more than a predetermined discharge determination threshold value.

In this case, for each of the plurality of index values, when each index value is greater than or equal to the corresponding predetermined threshold value, weighting is given according to the deviation between each index value and the corresponding predetermined threshold value, When the sum of weighting of each of the plurality of index values is equal to or larger than a predetermined discharge determination threshold value, it is determined that the discharge is necessary. That is, weighting is given to each index value according to the deviation between the index value and a predetermined threshold value. Therefore, it is possible to more accurately reflect the contribution of each index value to the temperature rise.

In the battery temperature management device according to the present invention, when it is determined that the discharge is necessary, the discharge control means determines, according to the deviation between the sum of the weighting of each of the plurality of index values and the predetermined discharge determination threshold value. It is preferable to set the discharge amount and perform the discharge according to the discharge amount.

In this case, when it is determined that the discharge is necessary, the discharge amount is set according to the deviation between the sum of the weighting of each of the plurality of index values and the predetermined discharge determination threshold value, and the discharge amount is set according to the discharge amount. Discharge is performed. That is, the discharge amount can be changed according to the deviation between the sum of weighting of each of the plurality of index values and the predetermined discharge determination threshold value. Therefore, it becomes possible to more reliably prevent the temperature rise.

The battery temperature control device according to the present invention is provided in series with a positive electrode power source line connected to a positive electrode of a nickel hydrogen battery and/or a negative electrode power source line connected to a negative electrode of a nickel hydrogen battery, And/or whether or not the discharge necessity determination means is required to be provided with an electromagnetic switch that electrically connects and disconnects the negative electrode power supply line, and when there is a request to open the electromagnetic switch after the vehicle is stopped. It is preferable that the discharge control means permits the electromagnetic switch to be opened after performing the discharge when it is determined that the discharge is necessary.

In this case, when there is a request to open the electromagnetic switch after the vehicle is stopped, it is determined whether or not it is necessary to discharge, and if it is determined that it is necessary to discharge, the electromagnetic switching is performed after the discharge is executed. Opening the vessel (i.e. ready-off) is allowed. Therefore, after the vehicle is stopped, it is possible to perform the discharge before the electromagnetic switch is opened, and it is possible to reliably prevent the subsequent temperature increase of the nickel hydrogen battery.

According to the present invention, in a battery temperature management device for managing the temperature of a nickel-hydrogen battery (battery) mounted on a vehicle, it is possible to prevent the battery temperature from rising while preventing unnecessary discharge after traveling. Can be suppressed.

It is a block diagram showing composition of a battery temperature management device concerning an embodiment, and a battery pack etc. to which the battery temperature management device was applied. It is a flowchart (the 1) which shows the process sequence of the battery temperature management process by the battery temperature management apparatus which concerns on embodiment. It is a flowchart (the 2) which shows the process sequence of the battery temperature management process by the battery temperature management apparatus which concerns on embodiment. It is a figure for demonstrating the acquisition method of a charging/discharging electric current amount. It is a figure for demonstrating the weighting method of a charge condition (SOC). It is a figure for demonstrating the weighting method of battery temperature. It is a figure for demonstrating the weighting method of environmental temperature.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals are used for the same or corresponding parts. Moreover, in each drawing, the same elements are denoted by the same reference numerals, and overlapping description will be omitted. In addition, here, a case where the present invention is applied to an electric vehicle (for example, an HV or a PHV) will be described as an example.

First, the configuration of the battery temperature management device 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the configurations of a battery temperature management device 1 and a battery pack 10 to which the battery temperature management device 1 is applied.

The battery temperature management device 1 manages the temperature of an assembled battery (battery module) 11 including a plurality of nickel hydrogen batteries (battery cells) 111 to 11n mounted on an electric vehicle equipped with an electric motor as a driving force source. More specifically, the battery temperature management device 1 prevents the unnecessary heat from being discharged (while reducing the loss due to the discharge) after the traveling of the vehicle, and the reaction heat caused by the self decomposition of the γ-type nickel hydroxide. This prevents the temperature of the assembled battery 11 from rising.

The battery temperature management device 1 is mainly configured to include a battery control unit (hereinafter referred to as “BCU”) 13, a discharge circuit 40, a current sensor 136, a battery temperature sensor 137, and an environmental temperature sensor 138. The BCU 13 mainly includes a total voltage detection unit (total voltage sensor) 131, a discharge necessity determination unit 132, a discharge control unit 133, a charge state acquisition unit 134, and a charge/discharge current amount acquisition unit 135. .. The details of each component will be described later.

The battery pack 10 to which the battery temperature management device 1 is applied mainly includes an assembled battery (battery module) 11, a positive contactor 121, a negative contactor 122, and a BCU 13.

The assembled battery (battery module) 11 is configured by connecting several tens to several hundreds of battery cells 111 to 11n in series (that is, configured as a high voltage battery of several tens to several hundreds V). There is.

One end of a positive power supply line 21 is connected to the positive electrode of the assembled battery 11. Similarly, one end of a negative electrode power supply line 22 is connected to the negative electrode of the assembled battery 11. The other end of the positive electrode power supply line 21 is connected to the positive electrode of the inverter 30 to which the power of the assembled battery 11 is supplied. Similarly, the negative electrode of the inverter 30 is connected to the other end of the negative power supply line 22.

In the positive electrode power source line 21 that electrically connects the positive electrode of the assembled battery 11 and the positive electrode of the inverter 30, a positive electrode side contactor 121 that electrically connects and disconnects the positive electrode power source line 21 is inserted in series (series). There is. Similarly, in the negative electrode power supply line 22 that electrically connects the negative electrode of the assembled battery 11 and the negative electrode of the inverter 30, a negative electrode side contactor 122 that electrically connects and disconnects the negative electrode power supply line 22 is connected in series. It is equipped. Each of the positive contactor 121 and the negative contactor 122 is an electromagnetic switch/electromagnetic contactor that opens and closes a contact with an electromagnet. The opening and closing of each of the positive electrode side contactor 121 and the negative electrode side contactor 122 is controlled by the HEV-CU 50 and the BCU 13.

The inverter 30 mainly includes a switching unit 30a, a voltage detection unit 31, and a smoothing capacitor 32.

The switching unit 30a is configured to include a plurality of switching elements such as IGBTs or MOSFETs, and converts the DC power of the battery pack 11 into three-phase AC power and supplies the three-phase AC power to the motor generator 33. The motor generator 33 is, for example, a three-phase AC type AC synchronous motor. The switching unit 30a (inverter 30) drives the motor generator 33 based on the torque command value received from the HEV-CU 50. On the other hand, the switching unit 30a (inverter 30) converts the AC voltage generated by the motor/generator 33 into a DC voltage to charge the assembled battery 11.

The smoothing capacitor 32 has one end connected to the positive power supply line 21 and the other end connected to the negative power supply line 22. The smoothing capacitor 32 smoothes noise generated by the switching operation of the inverter 30 (switching unit 30a).

The voltage detection unit (voltage sensor) 31 is connected in parallel with the smoothing capacitor 32 (that is, between the positive electrode power source line 21 and the negative electrode power source line 22), and the voltage between the terminals of the smoothing capacitor 32 (that is, the positive electrode power source line 21 and The potential difference between the negative power supply line 22) is detected.
The detected voltage value (voltage data) is transmitted to the BCU 13 via the CAN 100.

The discharge circuit 40 is housed in, for example, a DC-DC converter that steps down the DC high voltage of the assembled battery 11 to approximately 12V. The discharge circuit 40 is mainly configured to include a discharge resistor 41, a switching element (for example, a transistor) 42, and a control unit (CPU) 43.

The discharge circuit 40 has a discharge resistor 41, and is connected in parallel with the smoothing capacitor 32 (that is, one end is connected to the positive power supply line 21 and the other end is connected to the negative power supply line 22). The discharge circuit 40 discharges the assembled battery (battery module) 11 via the discharge resistor 41. That is, the discharging circuit 40 functions as the discharging means described in the claims.

The discharge resistor 41 is connected in parallel with the smoothing capacitor 32. The transistor 42 (discharge switch) is turned on/off (opened/closed) by a control unit (CPU) 43. When the transistor 42 is turned on, a current flows through the discharge resistor 41 and the battery pack 11 is discharged. The control unit 43 receives a command from the BCU 13 and outputs a signal for turning on/off the transistor 42.

The HEV-CU 50 comprehensively controls the BCU 13, the inverter 30, and the discharge circuit 40 (DC-DC converter). The HEV-CU 50 is communicably connected to the BCU 13, the inverter 30, the discharge circuit 40 (DC-DC converter), and the like via the CAN 100.

The HEV-CU 50 is a microprocessor that performs calculations, a ROM that stores programs for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM that retains the stored contents, And an input/output I/F and the like. The HEV-CU 50 functionally has a control unit 51. In the HEV-CU 50, the functions of the control unit 51 are realized by the CPU executing a program stored in an EEPROM or the like.

The control unit 51 controls opening/closing of the positive contactor 121 and opening/closing of the negative contactor 122. The control unit 51 outputs a control signal (request signal) for switching between closing and opening of the positive electrode side contactor 121 and the negative electrode side contactor 122 via the CAN 100.

The BCU 13 detects and manages the state of charge (SOC: State Of Charge) of the assembled battery 11 that supplies electric power to the motor generator 33. Further, the BCU 13 manages the temperature of the assembled battery (battery module) 11 including the plurality of nickel hydrogen batteries 111 to 11n.

The BCU 13 has a total voltage detection unit (total voltage sensor) 131 that detects the terminal voltage (total voltage) of the assembled battery (battery module) 11. The total voltage detection unit 131 is electrically connected to the A/D input terminal of the BCU 13, and after the signal (voltage value) corresponding to the terminal voltage (total voltage) of the assembled battery 11 is A/D converted. , BCU13. Similarly, the BCU 13 includes a current sensor 136 that detects a charge/discharge current of the assembled battery 11, a battery temperature sensor 137 that detects a battery temperature (battery temperature) of the assembled battery 11 (battery cells 111 to 11n), and an assembled battery. An environmental temperature sensor 138 that detects the environmental temperature (ambient temperature) around 11 is also connected. The current sensor 136, the battery temperature sensor 137 (corresponding to the battery temperature detecting means), and the environment temperature sensor 138 (corresponding to the environment temperature detecting means) are used after the end of traveling (that is, after the vehicle is stopped and ready/off). An index value acquisition unit that acquires an index value (parameter) having a correlation with the temperature rise of the assembled battery 11 is configured.

The BCU 13 drives a CPU that performs an operation, an EEPROM that stores a program for causing the CPU to execute each process, a RAM that stores various data such as an operation result, and a contactor 121 on the positive electrode side and a contactor 122 on the negative electrode side. It is configured to have an I/F such as a driver circuit or a CAN driver. The BCU 13 is a reaction caused by the self-decomposition of γ-type nickel hydroxide while preventing unnecessary discharge (while reducing loss due to discharge) after traveling (that is, after ready-off from vehicle stop). It has a function of suppressing an increase in battery temperature due to heat.

Here, in the nickel-hydrogen battery, as shown by the following chemical formula (1), nickel hydroxide (II) (Ni(OH) ₂ ) on the positive electrode side is bonded to hydroxide ion (OH-) during charging. To produce nickel hydroxide (NiOOH) and water (H ₂ O).
Ni(OH) ₂ +OH ⁻ →NiOOH+H ₂ O+e ⁻ (1)
Here, nickel hydroxide (NiOOH) is classified into a stable β type and an unstable γ type, and the γ type has nickel hydroxide (II) (Ni(OH) as shown by the following chemical formula (2). ) ₂ ) self-decomposes to generate oxygen.
4NiOOH+2H ₂ O→4Ni(OH) ₂ +O ₂ ... (2)
Then, oxygen binds to the metal hydride on the negative electrode side, and as shown by the following chemical formula (3), water is generated and reaction heat is generated.
4MH+O ₂ → 4M+2H ₂ O+ heat of reaction (3)

As described above, the BCU 13 functionally operates the total voltage detection unit (total voltage sensor) 131, the discharge necessity determination unit 132, the discharge control unit 133, the charge state acquisition unit 134, and the charge/discharge current amount acquisition unit 135. Have In the BCU 13, the program stored in the EEPROM or the like is executed by the CPU, so that the total voltage detection unit 131, the discharge necessity determination unit 132, the discharge control unit 133, the charge state acquisition unit 134, and the charge/discharge current amount. The function of the acquisition unit 135 is realized.

The charge state acquisition unit 134 acquires the charge state (SOC) of the assembled battery (battery module) 11. More specifically, the charge state acquisition unit 134 reads the voltage value/current value of the assembled battery 11 and detects the charged state (charge amount) (%) of the assembled battery 11 using, for example, a current integration method. The charge state acquisition unit 134 functions as a charge state acquisition unit described in the claims. The acquired state of charge (SOC) is output to the discharge necessity determination unit 132.

The charging/discharging current amount acquisition unit 135 acquires the charging/discharging current amount in a predetermined period immediately before the end of traveling, that is, immediately before the vehicle is stopped and ready-off. More specifically, the charge/discharge current amount acquisition unit 135 obtains the charge/discharge current amount (Ah) by integrating the charge/discharge current value (see FIG. 4) for a predetermined time (period). The charging/discharging current amount acquisition unit 135 functions as the charging/discharging current amount acquisition unit described in the claims. Here, when the charge/discharge current amount is positive (+), it can be determined that the vehicle has stopped in the charged state, and when the charge/discharge current amount is negative (-), it can be determined that the vehicle has stopped in the discharged state. it can. The acquired charge/discharge current amount is output to the discharge necessity determination unit 132.

The discharge necessity determination unit 132 discharges after traveling (after the vehicle is stopped and before ready-off) based on whether the acquired index value is equal to or greater than a predetermined threshold value. Determine if it is necessary. That is, the discharge necessity determination unit 132 functions as a discharge necessity determination unit described in the claims.

In particular, the discharge necessity/non-necessity determination unit 132 has, for each of a plurality of index values (charging/discharging current amount, state of charge (SOC), battery temperature, environmental temperature), each index value not less than a corresponding predetermined threshold value. In this case, weighting is given, and it is determined that the discharge is necessary when the sum of the weighting of each of the plurality of index values is equal to or more than a predetermined discharge determination threshold value.

More specifically, the discharge necessity determination unit 132 assigns a predetermined value (for example, E) as weighting when the charge/discharge current amount is a predetermined threshold value (for example, A(Ah)) or more, and It is temporarily stored in the buffer (RAM). On the other hand, when the charge/discharge current amount is less than the predetermined threshold value, the discharge necessity determination unit 132 gives zero as a weighting and temporarily stores it in the first buffer.

Similarly, the discharge necessity determination unit 132, as shown in FIG. 5, when the state of charge (SOC) is a predetermined threshold value (for example, B (%)) or more, a predetermined value (for example, F ) Is added and is temporarily stored in the second buffer (RAM). On the other hand, when the state of charge (SOC) is less than the predetermined threshold value, the discharge necessity determination unit 132 gives zero as a weighting and temporarily stores it in the second buffer.

Further, as shown in FIG. 6, the discharge necessity determination unit 132 gives a predetermined value (for example, G) as weighting when the battery temperature is equal to or higher than a predetermined threshold value (for example, C (° C.)). , And temporarily stored in the third buffer (RAM). On the other hand, when the battery temperature is lower than the predetermined threshold value, the discharge necessity determination unit 132 gives zero as a weighting and temporarily stores it in the third buffer.

Further, as shown in FIG. 7, the discharge necessity determination unit 132 gives a predetermined value (for example, H) as a weight when the environmental temperature is equal to or higher than a predetermined threshold value (for example, D (° C.)). , And temporarily stored in the fourth buffer (RAM). On the other hand, when the environmental temperature is lower than the predetermined threshold value, the discharge necessity determination unit 132 gives zero as a weighting and temporarily stores it in the fourth buffer. Note that each weighting is set such that E>F>G and H, for example.

Then, the discharge necessity/unnecessity determining unit 132 stores the weighting value temporarily stored in the first buffer, the weighting value temporarily stored in the second buffer, and temporarily stores it in the third buffer. The weighting value stored in the fourth buffer is added to the weighting value temporarily stored in the fourth buffer, and the addition result (that is, the sum of the weighting of the respective index values) is a predetermined discharge determination threshold value. When it is (for example, J) or more, it is determined that the assembled battery 11 needs to be discharged. On the other hand, when the addition result (sum of weighting of each index value) is less than the predetermined discharge determination threshold value, it is determined that discharge is unnecessary.

It should be noted that the discharge necessity determination unit 132 determines whether or not the discharge is required when the positive contactor 121 and the negative contactor 122 are opened after the vehicle is stopped. The discharge necessity determination result by the discharge necessity determination unit 132 is output to the discharge control unit 133.

When it is determined that discharging is necessary, the discharging control unit 133 drives the discharging circuit 40 (transistor 42) to discharge the battery pack 11 by a predetermined value (specified value). At that time, the discharge control unit 133 controls the on/off of the discharge circuit 40 by outputting the on/off control information of the discharge circuit 40 (transistor 42) via the CAN 100. That is, the control unit 51 functions as the discharge control unit described in the claims.

Further, the discharge control unit 133 permits the positive electrode side contactor 121 and the negative electrode side contactor 122 to be opened (that is, ready/off) after the discharge is performed.

Next, the operation of the battery temperature management device 1 will be described with reference to FIGS. 2 and 3 together. 2 and 3 are flowcharts showing the processing procedure of the battery temperature management processing by the battery temperature management device 1. The process shown in FIGS. 2 and 3 is repeatedly executed mainly by the BCU 13 at a predetermined timing.

First, in step S100, the positive electrode side contactor 121 and the negative electrode side contactor 122 are closed (that is, brought into a ready-on state).

Next, in step S102, it is determined whether or not the charge/discharge current amount is equal to or greater than a predetermined threshold value (for example, A(Ah)). Here, when the charge/discharge current amount is equal to or larger than the predetermined threshold value, a predetermined value (for example, E) is added as weighting and is temporarily stored in the first buffer (step S104). On the other hand, when the charge/discharge current amount is less than the predetermined threshold value, zero is given as a weight and is temporarily stored in the first buffer (step S106). Then, the process proceeds to step S108. Since the method of acquiring the charge/discharge current amount is as described above, detailed description will be omitted here.

In step S108, it is determined whether or not the charge amount (SOC) is equal to or greater than a predetermined threshold value (for example, B(%)). Here, when the charge amount (SOC) is equal to or more than the predetermined threshold value, a predetermined value (for example, F) is added as weighting and is temporarily stored in the second buffer (step S110). On the other hand, when the state of charge (SOC) is less than the predetermined threshold value, zero is given as a weight and is temporarily stored in the second buffer (step S112). Then, the process proceeds to step S114. Since the method of obtaining the state of charge (SOC) is as described above, detailed description will be omitted here.

In step S114, it is determined whether or not the battery temperature (battery temperature) is equal to or higher than a predetermined threshold value (for example, C (° C.)). Here, when the battery temperature is equal to or higher than the predetermined threshold value, a predetermined value (for example, G) is given as weighting and is temporarily stored in the third buffer (step S116). On the other hand, when the battery temperature is lower than the predetermined threshold value, zero is given as a weight and is temporarily stored in the third buffer (step S118). Then, the process proceeds to step S120.

In step S120, it is determined whether or not the environmental temperature (ambient temperature) is equal to or higher than a predetermined threshold value (for example, D (° C.)). Here, when the environmental temperature is equal to or higher than the predetermined threshold value, a predetermined value (for example, H) is given as weighting and is temporarily stored in the fourth buffer (step S120). On the other hand, when the environmental temperature is lower than the predetermined threshold value, zero is given as a weight and is temporarily stored in the fourth buffer (step S122). Then, the process proceeds to step S126.

In step S126, the vehicle is stopped, and it is determined whether or not there is a request for opening the positive contactor 121 and/or the negative contactor 122. Here, if there is no request to open the positive contactor 121 and/or the negative contactor 122, the process proceeds to step S102, and the processes of steps S102 to S126 described above are repeatedly executed until the open request is made. To be done. On the other hand, if there is a request to open the positive contactor 121 and/or the negative contactor 122, the process proceeds to step S128.

In step S128, the weighting value temporarily stored in the first buffer, the weighting value temporarily stored in the second buffer, and the weighting value temporarily stored in the third buffer. And the weighting value temporarily stored in the fourth buffer are added, and the addition result (that is, the sum of the weighting of each index value) is equal to or larger than a predetermined discharge determination threshold value (for example, J). A determination is made as to whether there is. Here, if the addition result (sum) is greater than or equal to the predetermined discharge determination threshold value, it is determined that discharge is necessary, and the process proceeds to step S130. On the other hand, when the addition result (sum) is less than the predetermined discharge determination threshold value, it is determined that the discharge is unnecessary, and the process proceeds to step S132.

In step S130, the discharge circuit 40 (transistor 42) is turned on, and the assembled battery (battery module) 11 is discharged through the discharge resistor 41 by a predetermined value (specified value). Then, the process proceeds to step S132.

In step S132, opening of the positive electrode side contactor 121 and/or the negative electrode side contactor 122 is permitted, and a control instruction is output to open the positive electrode side contactor 121 and/or the negative electrode side contactor 122. Then, the process is exited.

As described above in detail, according to the present embodiment, the index value having a correlation with the temperature increase of the assembled battery (battery module) 11 after the traveling is acquired, and the acquired index value has the predetermined threshold. Based on whether or not the value is greater than or equal to the value, it is determined whether or not discharging is necessary after the traveling is completed, and when it is determined that discharging is necessary, discharging is performed. Therefore, the amount of γ-type nickel hydroxide (NiOOH) accumulated on the surface of the positive electrode after charging is removed by discharging, so that the amount of self-decomposition of γ-type nickel hydroxide is reduced and the temperature rise of the battery can be suppressed. it can. As a result, it is possible to prevent the battery temperature from rising due to reaction heat due to self-decomposition of γ-type nickel hydroxide while preventing unnecessary discharge (while reducing loss due to discharge) after the end of traveling. It will be possible.

In particular, according to the present embodiment, a plurality of index values (charge/discharge current amount, state of charge (SOC), battery temperature, environmental temperature) having a correlation with the temperature rise of the assembled battery (battery module) 11 after the traveling is completed are obtained. For each of the plurality of index values acquired, if each index value is equal to or more than a corresponding predetermined threshold value, weighting is given, and the sum of weighting of each of the plurality of index values is equal to or more than a predetermined discharge determination threshold value. In this case, it is determined that discharge is necessary. Therefore, by using the plurality of index values and the sum of their weighting, it becomes possible to accurately determine the necessity of discharging.

At that time, according to the present embodiment, the charging/discharging current amount, the state of charge (SOC), the battery temperature, and the environmental temperature, which are correlated with the temperature rise of the assembled battery (battery module) 11 after the traveling ends, are considered. Therefore, it becomes possible to more accurately determine the necessity of discharging.

According to the present embodiment, after the vehicle is stopped, when there is a request for opening the positive contactor 121 and the negative contactor 122, it is determined whether or not discharging is necessary, and it is determined that discharging is necessary. In this case, opening (that is, ready/off) of the positive electrode side contactor 121 and the negative electrode side contactor 122 is allowed after the discharge is performed. Therefore, after the vehicle is stopped, the positive electrode side contactor 121 and the negative electrode side contactor 122 can be discharged (completed) before being opened, and it is possible to reliably prevent the subsequent temperature rise of the assembled battery 11. Becomes

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, although the contactor is used as the electromagnetic switch in the above embodiment, a relay or the like may be used instead of the contactor. Further, in the above embodiment, the case where one battery pack (battery module) 11 is provided has been described as an example, but a plurality of battery packs (battery module) 11 may be connected in parallel. Furthermore, in the above-described embodiment, the positive electrode side contactor 121 and the negative electrode side contactor 122 are provided. However, only one of the positive electrode side contactor 121 and the negative electrode side contactor 122 may be provided.

Further, the system configuration of the battery temperature management device 1 and the function sharing of each control unit (CU) are not limited to those in the above embodiment. For example, the functions of the discharge necessity determination unit 132, the discharge control unit 133, the charge state acquisition unit 134, and/or the charge/discharge current amount acquisition unit 135 are replaced with the BCU 13, and, for example, the HEV-CU 50, the inverter 30, or the like is used. You may have. Similarly, the discharge circuit 40 may be provided in the inverter 30 or the like, for example.

In the above-described embodiment, when the charge/discharge current amount, the state of charge (SOC), the battery temperature, the environmental temperature, and other index values exceed the corresponding predetermined threshold values, a certain weight is given. For each of the plurality of index values, when each index value is equal to or greater than a corresponding predetermined threshold value, weighting is given according to the deviation between each index value and the corresponding predetermined threshold value (for example, The result of multiplying the deviation and the weighting may be given), and the discharge may be determined to be necessary when the sum of the weighting of each of the plurality of index values is equal to or greater than a predetermined discharge determination threshold value. In this way, weighting is given to each index value according to the deviation between the index value and the predetermined threshold value, so that the contribution of each index value (parameter) to the temperature rise can be reflected more accurately. It will be possible.

Further, when it is determined that the discharge is necessary, the discharge amount is set according to the deviation between the sum of the weighting of each of the plurality of index values and the predetermined discharge determination threshold value, and the discharge is performed according to the discharge amount. It may be configured to perform. With this configuration, the amount of discharge can be varied according to the deviation between the sum of weighting of each of the plurality of index values and the predetermined discharge determination threshold value, so that the temperature rise of the assembled battery 11 can be prevented more reliably. It becomes possible to do.

Although four index values (parameters) are used in the above embodiment, it is not always necessary to use all four index values. For example, it may be configured to determine whether or not it is necessary to perform the discharge based on only the charge/discharge current amount (that is, based on whether the charge/discharge current amount is equal to or more than a predetermined threshold value). By doing so, it is possible to determine whether or not the assembled battery (battery module) 11 needs to be discharged while reducing costs and processing load. On the other hand, an index value other than the above-mentioned four index values (parameters) may be considered.

1 Battery Temperature Management Device 10 Battery Pack 11 Batteries (Battery Module)
111, 112, 113,..., 11n NiMH battery (battery cell)
121 Contactor on the positive electrode side (electromagnetic switch)
122 Negative contactor (electromagnetic switch)
13 BCU
131 Total Voltage Detector (Total Voltage Sensor)
132 Discharge necessity determination unit 133 Discharge control unit 134 Charge state acquisition unit 135 Charge/discharge current amount acquisition unit 136 Current sensor 137 Battery temperature sensor 138 Environmental temperature sensor 21 Positive power supply line 22 Negative power supply line 30 Inverter 30a Switching unit 31 Voltage detection unit (Voltage sensor)
32 smoothing capacitor 40 discharge circuit 41 discharge resistance 50 HEV-CU
51 control unit 100 CAN

Claims (9)

Discharging means for discharging the nickel-hydrogen battery via the discharge resistor,
Index value acquisition means for acquiring an index value having a correlation with the temperature rise of the nickel-hydrogen battery after the end of travel,
Based on whether or not the index value acquired by the index value acquisition means is equal to or greater than a predetermined threshold value, a discharge necessity determination means for determining whether or not it is necessary to discharge after traveling,
A battery temperature management device, comprising: a discharge control unit that drives the discharge unit to perform discharge when the discharge necessity determination unit determines that discharge is necessary. The index value acquisition means has a charge/discharge current amount acquisition means for acquiring a charge/discharge current amount in a predetermined period immediately before the end of traveling,
The discharge necessity determination means determines whether or not it is necessary to discharge, based on whether the charge/discharge current amount acquired by the charge/discharge current amount acquisition means is equal to or more than a predetermined threshold value. The battery temperature management device according to claim 1, wherein: The index value acquisition means acquires a plurality of index values having a correlation with the temperature rise of the nickel-hydrogen battery after the end of traveling,
The discharge necessity determination means assigns weighting to each of the plurality of index values when each index value is equal to or higher than a corresponding predetermined threshold value, and the sum of the weighting of each of the plurality of index values is the predetermined discharge value. The battery temperature management device according to claim 1, wherein the battery temperature management device determines that discharging is required when the threshold value is equal to or higher than a determination threshold value. The index value acquisition means is a charge/discharge current amount acquisition means for acquiring the charge/discharge current amount of the nickel hydrogen battery in a predetermined period immediately before the end of traveling, and a charge state acquisition means for acquiring the charge state of the nickel hydrogen battery. The battery temperature management device according to claim 3, further comprising: The battery temperature management device according to claim 4, wherein the index value acquisition unit further includes a battery temperature detection unit that detects a battery temperature of the nickel hydrogen battery. The battery temperature management device according to claim 5, wherein the index value acquisition unit further includes an environmental temperature detection unit that detects an environmental temperature around the nickel hydrogen battery. The discharge necessity determination means, for each of the plurality of index values, when each index value is equal to or greater than a corresponding predetermined threshold value, according to the deviation between each index value and the corresponding predetermined threshold value. The battery temperature management device according to claim 3, wherein weighting is applied, and it is determined that discharging is necessary when the sum of weighting of each of the plurality of index values is equal to or greater than a predetermined discharging determination threshold value. The discharge control means, when it is determined that the discharge is necessary, sets the discharge amount according to the deviation between the total of the weighting of each of the plurality of index values and the predetermined discharge determination threshold value, and the discharge amount. The battery temperature management device according to claim 7, wherein the battery temperature management device discharges according to the following. The positive electrode power supply line connected to the positive electrode of the nickel-hydrogen battery and/or the negative electrode power supply line connected to the negative electrode of the nickel-hydrogen battery is connected in series, and the positive electrode power supply line and/or the negative electrode power supply is provided. Equipped with an electromagnetic switch that electrically connects and disconnects the line,
The discharge necessity determination means determines whether or not it is necessary to discharge when there is a request to open the electromagnetic switch after the vehicle is stopped,
The discharge control means permits the electromagnetic switch to be opened after performing discharge when it is determined that discharge is necessary. The battery temperature management device described.

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