JP2018147665A - Control method and device of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide control method and device of secondary battery capable of increasing the capacity, by suppressing deterioration of Si of a negative electrode incident to electric charge and discharge.SOLUTION: A discharge characteristic line indicating the relation of the discharge characteristic value dQ/dV, i.e., the variation dQ in the residual capacity per unit time of a battery 10 to the variation dV in the voltage per unit time of the battery during discharge, and the voltage of the battery 10 is acquired, a voltage Vfor maximizing the absolute value of the discharge characteristic value dQ/dV is extracted, a voltage Vat an inflection point C where the absolute value of slope of the discharge characteristic line changes from decrement to increment in the voltage range of less than the voltage Vis extracted, and then use of the battery 10 is restrained at a voltage less than the voltage Vobtained by adding a prescribed value Vto the voltage V.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a secondary battery control method and apparatus.

  2. Description of the Related Art As a secondary battery, a battery whose capacity is increased by forming a negative electrode with a mixture of a material containing Si (silicon) and a carbon material is known (see, for example, Patent Document 1).

JP 2012-89521 A

  However, the secondary battery described in Patent Document 1 has a problem that, when charging and discharging are repeated, the capacity of the negative electrode decreases due to deterioration of Si of the negative electrode.

  The problem to be solved by the present invention is to provide a secondary battery control method and apparatus capable of increasing the capacity by suppressing the deterioration of Si in the negative electrode accompanying charge / discharge.

  The present invention relates to a discharge characteristic value which is a change amount of a remaining capacity per unit time of a secondary battery during discharge with respect to a change amount of a voltage per unit time of the secondary battery during discharge, and a voltage of the secondary battery. A discharge characteristic line indicating the relationship is obtained, a first voltage at which the absolute value of the discharge characteristic value is maximized is extracted, and an absolute value of the slope of the discharge characteristic line is obtained in a voltage range equal to or lower than the first voltage. Solving the above problem by extracting the second voltage at the inflection point from the decrease to the increase and suppressing the use of the secondary battery below the third voltage obtained by adding a predetermined value to the second voltage. To do.

  According to the present invention, by suppressing the use of the secondary battery in a voltage range where the contribution of Si to the discharge of the secondary battery is large, it is possible to suppress the deterioration of the Si of the negative electrode accompanying charging / discharging. The capacity can be increased.

1 is a system configuration diagram of a vehicle to which a secondary battery control method according to an embodiment of the present invention is applied. It is a functional block diagram of a vehicle control device. It is a graph which shows the discharge characteristic line of the battery obtained by experiment. It is a flowchart which shows the torque control process by the vehicle control apparatus of FIG. 2, the discharge suppression process of a battery, and the deterioration determination process of Si negative electrode. It is a functional block diagram of the vehicle control apparatus which concerns on other embodiment. It is a flowchart which shows the driving mode setting process by the vehicle control apparatus of FIG. 5, the discharge suppression process of a battery, and the deterioration determination process of Si negative electrode. It is a functional block diagram of the vehicle control apparatus which concerns on other embodiment. It is a figure which shows the indicator which shows the charge condition of the battery of the vehicle by which the vehicle control apparatus of FIG. 7 is mounted. It is a flowchart which shows the display control process of the indicator by the vehicle control apparatus of FIG. 7, the discharge suppression process of a battery, and the deterioration determination process of Si negative electrode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram of a vehicle 1 to which a secondary battery control method and apparatus according to an embodiment of the present invention is applied. As shown in this figure, a vehicle 1 is an electric vehicle that travels by the driving force of an electric motor, and includes a battery 10, an inverter 20, a motor 30, a voltage sensor 40, a current sensor 50, and an accelerator opening sensor. 60, a discharge switch 70, a charge switch 80, and a vehicle control device 100. Although the vehicle 1 of this embodiment is an electric vehicle, it is not limited to an electric vehicle, A hybrid vehicle, a plug-in hybrid vehicle, etc. may be sufficient. In FIG. 1, a thick line indicates a power line, and a thin line indicates a signal line.

  The battery 10 is a lithium ion secondary battery having a Si negative electrode, in which the negative electrode active material is composed of a mixture of a material containing Si (silicon) and another material (for example, graphite or the like). Examples of the material containing Si (Si-based material) include crystalline and non-crystalline Si, Si—O-based materials, and the like. On the other hand, as the positive electrode active material, NMC (nickel / manganese / cobalt), LMO (lithium manganate), NCA (nickel / cobalt / aluminum), LFP (olivine lithium iron phosphate), LCO (lithium cobaltate), etc. Can be illustrated. In the battery 10 of this embodiment, the negative electrode active material is a mixture of crystalline Si and graphite in a ratio of 20:80, and the positive electrode active material is NMC.

  The battery 10 is connected to an external charger 90 via a charging plug, and is charged by the charger 90. On the other hand, the charger 90 includes a discharge circuit and can perform constant current discharge from the battery 10 to the outside (for example, system power). In this embodiment, a constant current discharge of 0.3 C from the battery 10 to the outside can be performed. Further, the battery 10 outputs DC power to the inverter 20.

  The inverter 20 includes an inverter circuit and a circuit control device (not shown). The inverter circuit of the inverter 20 converts the DC power output from the battery 10 into three-phase AC power and outputs it to the motor 30. Further, the circuit control device of the inverter 20 controls the three-phase AC power so that the output torque of the motor 30 corresponding to the torque command value output from the vehicle control device 100 is realized as will be described later.

  The motor 30 is a three-phase AC motor that drives the drive wheels of the vehicle 1, and is driven by electric power that is output as DC power from the battery 10 and converted into three-phase AC power by the inverter 20. The motor 30 generates regenerative power when it is rotated by the drive wheels and rotates. In this case, the inverter 20 converts the alternating current generated by the motor 30 into a direct current and supplies it to the battery 10.

  The voltage sensor 40 detects the voltage V of the battery 10 and outputs it to the vehicle control device 100. Current sensor 50 is provided on a DC power supply line between battery 10 and inverter 20, detects the current value of the current flowing from battery 10 to inverter 20, and outputs the detected current value to vehicle control device 100. The accelerator opening sensor 60 detects the accelerator opening and outputs it to the vehicle control device 100.

  The discharge switch 70 is operated by a user of the vehicle 1 or an operator who performs maintenance of the vehicle 1 when instructing the discharge of the battery 10. The charging switch 80 is operated by a user of the vehicle 1 or an operator who performs maintenance of the vehicle 1 when instructing charging of the battery 10. Examples of the discharge switch 70 and the charge switch 80 include a touch panel and a push button provided in the room of the vehicle 1, a touch panel and a push button provided in the charger 90, and the like.

  ON / OFF of the discharge switch 70 is detected by the vehicle control device 100. When the discharge switch 70 is turned on while the battery 10 is connected to the charger 90, a discharge command is output from the vehicle control device 100 to the charger 90. Is done. Here, the discharge switch 70 is a switch for instructing discharge of the battery 10 when performing a calculation process of a discharge suppression voltage range of the battery 10 and a determination process of deterioration of the Si negative electrode, which will be described later.

  ON / OFF of the charging switch 80 is detected by the vehicle control device 100. When the charging switch 80 is turned on with the battery 10 connected to the charger 90, a charging command is output from the vehicle control device 100 to the charger 90. Is done. When the discharge switch 70 is turned on, charging is performed after the discharge is performed regardless of whether the charge switch 80 is turned on or off.

  The vehicle control device 100 is a control device that realizes various functions such as a travel control function of the vehicle 1 and a charge / discharge control function of the battery 10. The travel control function of the vehicle 1 includes a torque control process for controlling the torque of the motor 30. Further, the charge / discharge control function of the battery 10 includes a discharge suppression process for limiting the discharge of the battery 10 and a deterioration determination process for determining deterioration of the Si negative electrode.

  The vehicle control device 100 includes a ROM (Read Only Memory) storing programs for executing torque control processing, battery 10 discharge suppression processing, Si negative electrode deterioration determination processing, and the like, and programs stored in the ROM. And a RAM (Random Access Memory) functioning as an accessible storage device. As an operation circuit, instead of or in addition to a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. Can be used.

  FIG. 2 is a functional block diagram of the vehicle control device 100. As shown in this figure, the vehicle control device 100 includes a charge / discharge command unit 101, a dQ / dV calculation unit 102, a deterioration determination unit 103, a discharge power control unit 104, a torque command value calculation unit 105, an accelerator. An opening-torque command value map 106 is provided.

  The charge / discharge command unit 101 detects the ON / OFF state of the discharge switch 70, and when the discharge switch 70 is turned ON and the battery 10 is connected to the charger 90, the discharge command is sent to the charger 90. Is output. That is, when a user of the vehicle 1 or an operator who performs maintenance operates the discharge switch 70 when the battery 10 is connected to the charger 90 and the battery 10 is charged, the charge / discharge command unit 101 Command the battery 10 to discharge. The discharge of the battery 10 here is carried out until complete discharge or SOC = 1-20%.

  The charging / discharging command unit 101 detects the ON / OFF state of the charging switch 80, and when the charging switch 80 is turned ON and the battery 10 is connected to the charger 90, the charging command is sent to the charger 90. Is output. In addition, when both the discharge switch 70 and the charge switch 80 are turned on, the charge / discharge command unit 101 outputs the discharge command in advance, and outputs the charge command after the discharge is completed.

Here, when the voltage of the battery 10 is less than the predetermined value V ₄ , the charge / discharge command unit 101 outputs a command for charging the voltage of the battery 10 to the voltage V ₄ or more to the charger 90, and the battery 10 after being charged to a voltage V ₄ or more, and outputs a discharge command to the charger 90. Here, the predetermined value V ₄ is the voltage higher than the voltage V ₃ at the time when the absolute value of dQ / dV below is maximized.

  The dQ / dV calculation unit 102 detects the ON / OFF state of the discharge switch 70, and is output from the voltage sensor 40 when the discharge switch 70 is turned ON and the discharge process of the battery 10 is executed according to the discharge command. Based on the voltage V of the battery 10 and the current A of the battery 10 output from the current sensor 50, dQ is a ratio of the change amount dQ of the remaining capacity Q of the battery 10 to the change amount dV of the voltage V of the battery 10. / DV is calculated. The dQ / dV calculation unit 102 outputs dQ / dV to the deterioration determination unit 103 and the discharge power control unit 104 from the start of discharge to the end of discharge. The discharge power control unit 104 records the discharge characteristic line (discharge curve, see FIG. 3), which is the input dQ / dV time series data, together with the number of charge / discharge cycles in the memory.

  The deterioration determination unit 103 determines deterioration of the Si negative electrode of the battery 10 based on the discharge characteristic line, and outputs the determination result to the discharge power control unit 104. A method for determining the deterioration of the Si negative electrode will be described later.

  The discharge power control unit 104 calculates a voltage range for suppressing the discharge of the battery 10 (hereinafter referred to as a discharge suppression voltage range) based on the discharge characteristic line. A method for calculating the discharge suppression voltage range of the battery 10 will be described later.

  Here, the discharge power control unit 104 calculates the discharge suppression voltage range according to the determination result of the deterioration of the Si negative electrode of the battery 10 output from the deterioration determination unit 103. For example, when the degree of deterioration of the Si negative electrode of the battery 10 is relatively large, it is calculated that there is no discharge suppression voltage range, or the degree of deterioration of the Si negative electrode of the battery 10 increases, Or so that the upper limit value of becomes lower.

  The discharge power control unit 104 records the calculated discharge suppression voltage range in the memory. While the vehicle 1 is traveling, the discharge power control unit 104 determines whether or not the voltage V of the battery 10 output from the voltage sensor 40 is included in the discharge suppression voltage range, and the voltage V is included in the discharge suppression voltage range. The torque suppression command is output to the torque command value calculation unit 105.

  The torque command value calculation unit 105 reads a torque command value corresponding to the accelerator opening output from the accelerator opening sensor 60 from the accelerator opening-torque command value map 106 and outputs it to the inverter 20. Here, when the torque suppression command is not output from the discharge power control unit 104, the torque command value calculation unit 105 corrects the torque command value read from the accelerator opening-torque command value map 106 without correcting the torque command value. 20 is output. On the other hand, when a torque suppression command is output from the torque command value calculation unit 105, a predetermined correction value α (<1.0 for the torque command value read from the accelerator opening-torque command value map 106 is obtained. ) And the corrected torque command value is output to the inverter 20.

  Here, a method for calculating the discharge suppression voltage range of the battery 10 and a method for determining the deterioration of the Si negative electrode will be described. The inventor of the present application conducted experiments described below, and found that there was a voltage range in which the contribution during discharge was large between Si and graphite of the Si negative electrode. Hereinafter, the contents and results of this experiment will be described.

  In this experiment, a lithium ion secondary battery having a Si negative electrode with a ratio of Si to graphite of 20:80 and a positive electrode made of NMC, a capacity of 3.5 Ah, and a maximum voltage of 4.2 V was obtained. Prepared. This lithium ion secondary battery was repeatedly charged and discharged at a current rate of 0.3 C between 4.2 V (SOC: about 100%) to 2.7 V (SOC: about 0 to 10%). . And the voltage V and the remaining capacity Q of the battery 10 at the time of discharge were measured continuously, and the discharge characteristic line of the battery 10 at the time of discharge was acquired.

  FIG. 3 is a graph showing a discharge characteristic line (dQ / dV curve during discharge) of the battery 10 obtained in this experiment. Curve (A) in this graph is a discharge characteristic line in the first cycle, curve (B) in the graph is a discharge characteristic line in the 200th cycle, and curve (C) in the graph is It is a discharge characteristic line in the 500th cycle.

  As shown in the graph of FIG. 3, in the initial stage of discharge (4.2V-3.7V), the change in the absolute value of dQ / dV accompanying the increase in the number of charge / discharge cycles is minute, whereas the discharge From the middle to the end (3.7V-2.7V), the decrease in the absolute value of dQ / dV with the increase in the number of charge / discharge cycles is relatively large. In particular, the end of discharge (3.4V− At 2.7 V), the difference between the absolute value of dQ / dV at the 200th cycle and the 500th cycle and the absolute value of dQ / dV at the first cycle becomes significant.

  Here, while the deterioration of Si progresses with an increase in the number of charge / discharge cycles, the capacity of the battery 10 does not decrease with the increase in the number of cycles at the beginning of discharge. From this, it can be determined that, at the beginning of discharge, the contribution of Si to the discharge of the battery 10 is smaller than the contribution of graphite to the discharge of the battery 10. On the other hand, at the end of discharge, the capacity of the battery 10 is significantly reduced as the number of cycles increases. From this, it can be determined that the contribution of Si to the discharge of the battery 10 is larger than the contribution of graphite to the discharge of the battery 10 at the end of discharge.

  Further, as shown in the graph of FIG. 3, in the discharge characteristic lines (A) and (B) in the first cycle and the 200th cycle, the voltage V of the battery 10 is 3.4 to 3.5 V (SOC is 40%). It was confirmed that the absolute value of dQ / dV was maximized at the time. In the discharge characteristic lines (A) and (B), the absolute value of dQ / dV starts to decrease after the slope of the absolute value of dQ / dV decreases while the absolute value of dQ / dV decreases from the maximum value to the minimum value. (Hereinafter referred to as inflection point C) was confirmed to be present at a time of about 3.2 V (SOC is about 20 to 30%). On the other hand, in the discharge characteristic line (C) at the 500th cycle, it was not confirmed that the inflection point C was present at the end of discharge. That is, in the charge / discharge cycle in which the contribution of Si to the discharge remains, it is confirmed that the inflection point C exists in a voltage range in which the contribution of Si to the discharge is larger than the contribution of graphite to the discharge. It was.

  As described above, in the discharge characteristic lines (A) and (B) of the first cycle to the 200th cycle, the voltage range is equal to or lower than the voltage (3.4 to 3.5 V) at which the absolute value of dQ / dV is maximum, It was confirmed that the voltage range in which the inflection point C exists is a voltage range in which the contribution of Si to the discharge is larger than the contribution of graphite to the discharge.

  Further, by comparing the inflection point C in the discharge characteristic line (A) of the first cycle with the inflection point C in the discharge characteristic line (B) of the 200th cycle, the battery 10 accompanying the increase in the number of cycles can be obtained. A decrease in capacity can be confirmed, whereby the degree of progress of Si degradation accompanying an increase in the number of cycles can be confirmed. Further, in the discharge characteristic line (B) at the 500th cycle, the existence of the inflection point C confirmed in the discharge characteristic line (A) in the first cycle and the discharge characteristic line (B) in the 200th cycle is not confirmed. Accordingly, it was confirmed that when the inflection point C is not confirmed due to the progress of Si degradation accompanying the increase in the number of cycles, it can be determined that the Si degradation has become significant.

  Here, it is generally known that Si has a large volume change accompanying charge / discharge compared to other negative electrode active materials. For this reason, the use of the battery 10 in a voltage range where the contribution of Si to the discharge is large becomes a factor that accelerates the deterioration of Si and causes wrinkles on the Si negative electrode. When wrinkles occur in the Si negative electrode, the distance between the positive electrode and the negative electrode becomes non-uniform, so that current concentrates on a part of the electrode, and the durability of the electrode decreases.

Therefore, the discharge power control unit 104 of the present embodiment is equal to or lower than the voltage V ₃ (3.4 to 3.5 V) at which the absolute value of dQ / dV is maximized in the charge / discharge cycle where the inflection point C exists. The voltage range in which the inflection point C exists is set to the discharge suppression voltage range (V _{MIN to} V _MAX ) of the battery 10. Here, the upper limit value V _MAX of the discharge suppression voltage range of the battery 10 satisfies the following expression (1). The lower limit value V _MIN of the discharge suppression voltage range of the battery 10 corresponds to the voltage at the end of discharge (corresponding to about SOC = 0 to 20%) in the charge / discharge cycle.
V _MAX = V ₁ + V ₂ (1)
However, _{V 1} is the voltage corresponding to the inflection point C, _{V 2} is a predetermined value. Here, V ₂ is set so as not to exceed voltage V ₃ .

Incidentally, it may set the voltage V _MAX by using only the voltage V _1, V ₃ in the first cycle of charge and discharge cycles, or using the average value of the voltage V _1, V ₃ in a plurality of charge-discharge cycles, the most recent The voltage V _MAX may be set by using the voltages V ₁ and V ₃ in the charge / discharge cycle.

In addition, the discharge power control unit 104 of the present embodiment records a discharge characteristic line that is time series data of dQ / dV in each charge cycle in a memory. In the case where the inflection point C can be detected when the charge / discharge cycle is performed, the deterioration determination unit 103 detects the inflection point C and the inflection of the discharge characteristic line of the previous cycle recorded in the memory. The point C is compared, and the degree of Si degradation is determined from the difference between these dQ / dV. Furthermore, when the inflection point C corresponding to the voltage V ₁ of the discharge characteristic line recorded in the memory cannot be detected, the deterioration determination unit 103 determines that the progress of Si deterioration is equal to or greater than a predetermined threshold. The determination result is output to the discharge power control unit 104. In this case, the discharge power control unit 104 cancels the discharge power suppression control.

  FIG. 4 is a flowchart showing a torque control process, a battery 10 discharge suppression process, and a Si negative electrode deterioration determination process performed by the vehicle control apparatus 100. The process shown in this flowchart is started when the battery 10 is connected to the charger 90 and the discharge switch 70 is operated.

First, in step S101, the charge and discharge command section 101, the voltage of the battery 10 detected by the voltage sensor 40 is equal to or above the predetermined value V ₄ higher. The predetermined value V ₄ corresponds to a voltage higher than the voltage V ₃ of the battery 10 at the time when the absolute value of dQ / dV becomes maximum. If an affirmative determination is made in this step, the process proceeds to step S103, and if a negative determination is made in this step, the process proceeds to step S102.

In step S <b> 102, the charge / discharge command unit 101 outputs a charge command to the charger 90. The charger 90 charges the battery 10 when a charging command is input. Returns from step S102 to step S101, the voltage of the battery 10 is step S101, S102 are repeated until rises above a predetermined value _{V 4.}

  On the other hand, in step S <b> 103, the charge / discharge command unit 101 outputs a discharge command to the charger 90. When the discharge command is input, the charger 90 discharges the battery 10. Next, in step S <b> 104, while the battery 10 is being discharged, the dQ / dV calculation unit 102 determines the voltage V of the battery 10 output from the voltage sensor 40 and the current of the battery 10 output from the current sensor 50. Based on A, dQ / dV is calculated and output to the deterioration determination unit 103 and the discharge power control unit 104. The discharge power control unit 104 records a discharge characteristic line, which is dQ / dV time series data, together with the number of charge / discharge cycles in the memory.

Next, in step S105, the discharge power control unit 104 determines whether or not the discharge has ended. If a negative determination is made in this step, the process returns to step S104. If an affirmative determination is made in this step, the process proceeds to step S106. In step S106, the deterioration determination unit 103 extracts the maximum value of the absolute value of dQ / dV from the discharge characteristic line stored in the memory in step S104, the extracted maximum value is equal to or greater than a predetermined value, and the voltage V ₃ or less of the voltage range corresponding to the maximum value determines the inflection point C is present. If an affirmative determination is made in this step, the process proceeds to step S107, and if a negative determination is made in this step, the process proceeds to step S111.

  In step S <b> 107, the deterioration determination unit 103 outputs a discharge suppression command to the discharge power control unit 104. In addition, the deterioration determination unit 103 compares the inflection point C detected from the discharge characteristic line of the current charge / discharge cycle with the inflection point C of the discharge characteristic line of the previous charge / discharge cycle recorded in the memory. The degree of Si degradation is determined from the difference between these dQ / dV. The process proceeds from step S107 to step S108.

In step S108, the discharge power control unit 104, the presence of discharge characteristic line is stored in the memory in step S104, a voltage _{V 3} corresponding to the maximum value of the absolute value of dQ / dV, the voltage range of the voltage _{V 3} or less The voltage V ₁ corresponding to the inflection point C to be extracted is extracted, and the discharge suppression voltage range V _{MIN to} V _MAX is calculated from the above equation (1) based on the extracted voltages V ₁ and V ₃ . Next, in step S109, the discharge power control unit 104 determines whether or not the voltage V output from the voltage sensor 40 is included in the discharge suppression voltage range V _{MIN to} V _MAX while the vehicle 1 is traveling. If a positive determination is made in this step, the process proceeds to step S110, and if a negative determination is made in this step, the process proceeds to step S112.

  In step S <b> 110, discharge power control unit 104 outputs a torque suppression command to torque command value calculation unit 105. When the torque suppression command is output from the discharge power control unit 104 while the vehicle 1 is traveling, the torque command value calculation unit 105 performs a predetermined operation on the torque command value read from the accelerator opening-torque command value map 106. Multiply the correction value α (<1.0) and output the corrected torque command value to the inverter 20. The process proceeds from step S110 to step S112.

  On the other hand, in step S <b> 111, degradation determination unit 103 outputs a discharge suppression release / prohibition command for canceling / prohibiting discharge suppression control to discharge power control unit 104. When the discharge suppression release / prohibition command is output from the degradation determination unit 103, the discharge power control unit 104 does not output the torque suppression command to the torque command value calculation unit 105 while the vehicle 1 is traveling. Therefore, the torque command value calculation unit 105 outputs the torque command value read from the accelerator opening-torque command value map 106 to the inverter 20 without correcting it while the vehicle 1 is traveling. In this step, the deterioration determination unit 103 determines the progress of Si deterioration. Here, the progress degree of Si deterioration determined in this step is higher than the progress degree of Si deterioration determined in Step S107. The process proceeds from step S111 to step S112.

  In step S <b> 112, the charge / discharge command unit 101 outputs a charge command to the charger 90. Next, in step S113, the charge / discharge command unit 101 determines whether or not the SOC of the battery 10 has increased to a value specified by the user. If an affirmative determination is made in this step, the process ends.

As described above, in the control method and apparatus for the battery 10 according to the present embodiment, the remaining capacity per unit time of the battery 10 during discharge with respect to the change amount dV of the voltage per unit time of the battery 10 during discharge. a discharge characteristic value dQ / dV is the change amount dQ, acquires the discharge characteristic curve showing the relationship between the voltage of the battery 10, and extracts a voltage V ₃ that the absolute value of the discharge characteristic value dQ / dV is maximized, The voltage V _{MAX obtained} by extracting the voltage V ₁ at the inflection point C where the absolute value of the slope of the discharge characteristic line changes from decreasing to increasing in the voltage range of the voltage V ₃ or less, and adding the predetermined value V ₂ to the voltage V _1. The use of the battery 10 in the following is suppressed. That is, the use of the battery 10 in a voltage range in which the contribution of Si to the discharge is large is suppressed. Thereby, since deterioration of Si of the negative electrode accompanying charging / discharging can be suppressed, the capacity | capacitance of the battery 10 can be increased.

In the control method and apparatus for the battery 10 according to the present embodiment, the upper limit value V _MAX of the discharge suppression voltage range is equal to or lower than the voltage V ₃ at which the absolute value of the discharge characteristic value dQ / dV is maximized. As a result, the discharge suppression voltage range can be limited to a voltage range in which the contribution of Si to the discharge is large, and the voltage range that limits the use of the battery 10 can be set to the minimum necessary range.

  In the control method and apparatus for the battery 10 according to the present embodiment, the torque of the motor 30 is suppressed when the voltage of the battery 10 is included in the discharge voltage suppression range. Thereby, it is possible to suppress the use of the battery 10 in a voltage range in which the contribution of Si to the discharge is large, and it is possible to suppress the deterioration of Si of the negative electrode accompanying charge / discharge.

  Here, when the deterioration degree of the Si negative electrode is significant, there is little need to suppress the use of the battery 10 and suppress the deterioration of the Si. Therefore, in the control method and apparatus for the battery 10 according to this embodiment, the deterioration degree of the Si negative electrode is determined based on at least one of the presence / absence of the inflection point C and the discharge characteristic value dQ / dV at the inflection point C. Determination is made, and when the degree of deterioration of the Si negative electrode is equal to or greater than the threshold value, suppression of use of the battery 10 is canceled or prohibited. Thereby, the use limitation of the battery 10 can be minimized.

  Further, the control device for the battery 10 according to the present embodiment determines the degree of deterioration of the Si negative electrode based on at least one of the presence / absence of the inflection point C and the discharge characteristic value dQ / dV at the inflection point C. A deterioration determination unit 103 is provided. Thereby, the deterioration degree of Si negative electrode can be alert | reported to the user of the vehicle, the worker who performs maintenance, etc.

  FIG. 5 is a functional block diagram of a vehicle control device 200 according to another embodiment. The vehicle on which the vehicle control apparatus 200 of this embodiment is mounted is a hybrid vehicle or a plug-in hybrid vehicle. In addition, the same code | symbol is attached | subjected to the structure similar to the vehicle control apparatus 100 of the above-mentioned embodiment, the overlapping description is abbreviate | omitted and the above-mentioned description is used. As shown in FIG. 5, the vehicle control device 200 includes a charge / discharge command unit 101, a dQ / dV calculation unit 102, a deterioration determination unit 103, a discharge power control unit 204, and a travel mode setting unit 205. Yes.

The discharge power control unit 204 calculates the discharge voltage suppression range (V _{MIN to} V _MAX ) when a discharge suppression command is output from the deterioration determination unit 103, similarly to the discharge power control unit 104 of the above-described embodiment. . The discharge power control unit 204 travels a motor drive prohibition command that prohibits motor drive when the voltage V output from the voltage sensor 40 is included in the discharge suppression voltage range V _{MIN to} V _MAX while the vehicle is traveling. Output to the mode setting unit 205.

  On the other hand, the discharge power control unit 204 does not output the motor drive prohibition command to the travel mode setting unit 205 while the vehicle 1 is traveling when the command for canceling / prohibiting the discharge suppression control is output from the deterioration determination unit 103. .

  The driving mode set by the driving mode setting unit 205 includes an engine / motor driving mode in which the vehicle is driven by both the engine and the motor, an engine driving mode in which the vehicle is driven only by the engine, and a motor that drives the vehicle only by the motor. There are three types of driving modes, and the driving mode setting unit 205 switches the driving mode according to the driving state of the vehicle and the charging state of the battery 10. Here, the traveling mode setting unit 205 always sets the traveling mode to the engine traveling mode regardless of the traveling state of the vehicle when the motor drive prohibition command is output from the discharge power control unit 204 while the vehicle is traveling. On the other hand, when the motor drive prohibition command is not output from the discharge power control unit 204 during travel of the vehicle, the travel mode setting unit 205 sets the travel mode to the above three travel modes according to the travel state of the vehicle. Set to either.

  FIG. 6 is a flowchart showing a travel mode setting process, a battery 10 discharge suppression process, and a Si negative electrode deterioration determination process performed by the vehicle control device 200. The process shown in this flowchart is started when the battery 10 is connected to the charger 90 and the discharge switch 70 is operated.

First, processing similar to steps S101 to S109 and S111 in the above-described embodiment is executed. In step S109, the discharge power control unit 204 determines whether or not the voltage V output from the voltage sensor 40 is included in the discharge suppression voltage range V _{MIN to} V _MAX while the vehicle 1 is traveling. If a positive determination is made in this step, the process proceeds to step S210. If a negative determination is made in this step, the process proceeds to step S112.

  In step S <b> 210, discharge power control unit 204 outputs a motor drive prohibition command to travel mode setting unit 205. The travel mode setting unit 205 always sets the travel mode to the engine travel mode regardless of the travel state of the vehicle when the motor drive prohibition command is output from the discharge power control unit 204 while the vehicle 1 is traveling. The process proceeds from step S210 to step S111. Note that it is not essential to prohibit the engine / motor travel mode when the motor drive prohibition command is output, and only the motor travel mode may be prohibited.

  On the other hand, in step S <b> 111, the deterioration determination unit 103 outputs a discharge suppression release / prohibition command for canceling / prohibiting the discharge suppression control to the discharge power control unit 204. When the discharge suppression release / prohibition command is output from the degradation determination unit 103, the discharge power control unit 204 does not output the motor drive prohibition command to the travel mode setting unit 205 while the vehicle 1 is traveling. For this reason, the traveling mode setting unit 205 sets the traveling mode to one of the three types of traveling modes according to the traveling state of the vehicle while the vehicle 1 is traveling. The process proceeds from step S111 to step S112.

  In step S <b> 112, the charge / discharge command unit 101 outputs a charge command to the charger 90. Next, in step S113, the charge / discharge command unit 101 determines whether or not the SOC of the battery 10 has increased to a value specified by the user. If an affirmative determination is made in this step, the process ends.

  As described above, in the control method and apparatus for the battery 10 according to the present embodiment, the engine running mode is set when the voltage of the battery 10 that is the driving power source of the motor of the hybrid vehicle is included in the discharge suppression voltage range. Thereby, it is possible to suppress the use of the battery 10 in a voltage range in which the contribution of Si to the discharge is large, and it is possible to suppress the deterioration of Si of the negative electrode accompanying charge / discharge.

  FIG. 7 is a functional block diagram of a vehicle control device 300 according to another embodiment. FIG. 8 is a diagram illustrating an indicator 310 that indicates the state of charge of the battery 10 of the vehicle on which the vehicle control device 300 of the present embodiment is mounted. In addition, the same code | symbol is attached | subjected to the structure similar to the vehicle control apparatuses 100 and 200 of the above-mentioned embodiment, the duplicate description is abbreviate | omitted, and the above-mentioned description is used. As shown in FIG. 7, the vehicle control device 300 includes a charge / discharge command unit 101, a dQ / dV calculation unit 102, a deterioration determination unit 103, a discharge power control unit 304, and an indicator control unit 305. .

As shown in FIG. 8, the indicator 310 is provided with a display unit 311 that indicates the state of charge of the battery 10 and a display lamp 312 that is provided in a low remaining amount area of the display unit 311. The remaining charge amount in the low remaining amount area of the display unit 311 corresponds to the remaining charge amount in the discharge voltage suppression range (V _{MIN to} V _MAX ).

Returning to FIG. 7, similarly to the discharge power control unit 104 of the above-described embodiment, the discharge power control unit 304 outputs a discharge voltage suppression range (V _{MIN to} V _MIN ) when a discharge suppression command is output from the deterioration determination unit 103. _MAX ). The discharge power control unit 304 outputs a lighting command for the display lamp 312 to the indicator control unit 305 when the voltage V output from the voltage sensor 40 is included in the discharge suppression voltage range V _{MIN to} V _MAX .

  On the other hand, the discharge power control unit 304 does not output a lighting command for the display lamp 312 to the indicator control unit 305 when a command for canceling / prohibiting the discharge suppression control is output from the deterioration determination unit 103.

The indicator control unit 305 turns on the display lamp 312 when a discharge command for the display lamp 312 is output from the discharge power control unit 304. This notifies the vehicle user that he / she will refrain from using the battery 10 in the discharge suppression voltage range V _{MIN to} V _MAX . Accordingly, the user of the vehicle increases the frequency of charging the battery 10. On the other hand, the indicator control unit 305 does not light the display lamp 312 when the discharge power control unit 304 does not output a lighting command for the display lamp 312.

  FIG. 9 is a flowchart illustrating an indicator display control process, a battery 10 discharge suppression process, and a Si negative electrode deterioration determination process performed by the vehicle control device 300. The process shown in this flowchart is started when the battery 10 is connected to the charger 90 and the discharge switch 70 is operated.

First, processing similar to steps S101 to S109 and S111 in the above-described embodiment is executed. In step S109, the discharge power control unit 304 determines whether or not the voltage V output from the voltage sensor 40 is included in the discharge suppression voltage range V _{MIN to} V _MAX while the vehicle 1 is traveling. If a positive determination is made in this step, the process proceeds to step S310, and if a negative determination is made in this step, the process proceeds to step S112.

  In step S <b> 310, the discharge power control unit 304 outputs a lighting command for the display lamp 312 to the indicator control unit 305. The indicator control unit 305 turns on the display lamp 312 when a discharge command for the display lamp 312 is output from the discharge power control unit 304. The process proceeds from step S310 to step S112.

  In step S <b> 112, the charge / discharge command unit 101 outputs a charge command to the charger 90. Next, in step S113, the charge / discharge command unit 101 determines whether or not the SOC of the battery 10 has increased to a specified value. If an affirmative determination is made in this step, the process ends.

  As described above, the display lamp 312 is turned on when the voltage of the battery 10 that is the driving power source of the vehicle including the display lamp 312 as the notification device is included in the discharge suppression voltage range. Thereby, the user of the vehicle can refrain from using the battery 10 in a voltage range in which the contribution of Si to the discharge is large, and the deterioration of Si of the negative electrode accompanying charging / discharging can be suppressed.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, the present invention has been described by exemplifying a control method and apparatus for a secondary battery mounted on a vehicle, but the present invention can also be applied to a secondary battery mounted on a device other than the vehicle. . Moreover, you may combine the control in each above-mentioned embodiment. For example, in the hybrid vehicle, when the voltage of the battery 10 is included in the discharge suppression voltage range, the engine / motor traveling mode may be set and the motor torque may be suppressed. Further, when the voltage of the battery 10 is included in the discharge suppression voltage range, the torque of the motor may be suppressed or the engine running mode may be set, and the display lamp 312 may be turned on.

In the above-described embodiment, the upper limit value V _MAX of the discharge suppression voltage range is set to the voltage V ₃ or less at which the absolute value of the discharge characteristic value dQ / dV is maximized. However, this is not essential, and the upper limit value V _{MAX is set} to the voltage. it may be set to a value greater than V _3.

10 battery 30 motor 100 vehicle control device 103 deterioration determining unit 200 the vehicle control device 300 the vehicle control device 310 indicator 312 indicator lamps _{V 1} voltage (second voltage)
V ₂ predetermined value V ₃ voltage (first voltage)
V _MAX voltage (third voltage)

Claims (8)

A method for controlling a secondary battery comprising a negative electrode containing Si as an active material, a positive electrode, and an electrolyte disposed between the negative electrode and the positive electrode,
A discharge characteristic value that is a change amount of the remaining capacity per unit time of the secondary battery during discharge with respect to a change amount of the voltage per unit time of the secondary battery during discharge, and a voltage of the secondary battery Get the discharge characteristic line showing the relationship,
Extracting a first voltage having a maximum absolute value of the discharge characteristic value;
Extracting a second voltage at an inflection point where the absolute value of the slope of the discharge characteristic line changes from decreasing to increasing in a voltage range equal to or lower than the first voltage;
A secondary battery control method for suppressing use of the secondary battery below a third voltage obtained by adding a predetermined value to the second voltage.   The method for controlling a secondary battery according to claim 1, wherein the third voltage is equal to or lower than the first voltage. The secondary battery is a drive power source of a motor,
The use of the secondary battery at the third voltage or lower is suppressed by suppressing the torque of the motor when the voltage of the secondary battery is lower than the third voltage. The control method of the secondary battery as described. The secondary battery is a driving power source for a motor of a hybrid vehicle,
Any of Claims 1-3 which suppress use of the said secondary battery below the said 3rd voltage by setting to engine driving mode when the voltage of the said secondary battery is below the said 3rd voltage. The control method of the secondary battery of Claim 1. The secondary battery is a drive power source of a device provided with a notification device,
Any of Claims 1-4 which suppress the use of the said secondary battery below the said 3rd voltage by operating the said alerting | reporting apparatus when the voltage of the said secondary battery is below the said 3rd voltage. The control method of the secondary battery of Claim 1. Based on the presence / absence of the inflection point and at least one of the discharge characteristic value at the inflection point, the deterioration degree of the negative electrode is determined,
The method for controlling a secondary battery according to any one of claims 1 to 5, wherein when the degree of deterioration is equal to or greater than a threshold value, suppression of use of the secondary battery is canceled or prohibited. A control device for a secondary battery, comprising a negative electrode containing Si as an active material, a positive electrode, and an electrolyte disposed between the negative electrode and the positive electrode,
A discharge characteristic value that is a change amount of the remaining capacity per unit time of the secondary battery during discharge with respect to a change amount of the voltage per unit time of the secondary battery during discharge, and a voltage of the secondary battery Get the discharge characteristic line showing the relationship,
Extracting a first voltage having a maximum absolute value of the discharge characteristic value;
Extracting a second voltage at an inflection point where the absolute value of the slope of the discharge characteristic line changes from decreasing to increasing in a voltage range equal to or lower than the first voltage;
A secondary battery control device that suppresses use of the secondary battery at a voltage equal to or lower than a third voltage obtained by adding a predetermined value to the second voltage.   The secondary battery control according to claim 7, further comprising a negative electrode deterioration determination unit that determines a deterioration degree of the negative electrode based on at least one of the presence or absence of the inflection point and the discharge characteristic value at the inflection point. apparatus.

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