Control device for secondary battery

Abstract

The present invention provides a control device (10) for a secondary battery (110) that can limit the power value of the secondary battery (110) per unit time without excessively limiting the allowable power value of the secondary battery (110). The control device (10) for the secondary battery (110) includes an allowable power setting unit (421) and an allowable power limiting unit (422). The allowable power setting unit (421) sets an allowable power value for the secondary battery (110) during at least one of discharging and charging, based on specified information of the secondary battery (110). The allowable power limiting unit (422) limits the power value before the power value of the secondary battery (110) reaches the allowable power value. The allowable power limiting unit (422) limits the power value in stages at two or more different ratios.

Description

Technical Field

[0001] This invention relates to a control device for secondary batteries. Background Technology

[0002] Previously, techniques were known to limit the power value of a secondary battery per unit time (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2008 / 111594 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] A control device for a secondary battery that limits the power value of the secondary battery per unit time without excessively restricting the allowable power value of the secondary battery.

[0008] Technical means for solving problems

[0009] The control device for a secondary battery includes: a permissible power setting unit that sets a permissible power value for the secondary battery during at least one of discharging and charging, based on specified information about the secondary battery; and a permissible power limiting unit that limits the power value before the power value of the secondary battery reaches the permissible power value. The permissible power limiting unit limits the power value in stages at two or more different ratios.

[0010] Invention Effects

[0011] According to the present invention, a control device for a secondary battery can be obtained, which can limit the power value of the secondary battery per unit time without excessively limiting the allowable power value of the secondary battery. Attached Figure Description

[0012] Figure 1 This is a block diagram showing a battery system 1, etc., including a control device 10 containing a secondary battery 110 according to the first embodiment.

[0013] Figure 2 This is a block diagram representing the battery state estimation and control unit 400 of battery system 1.

[0014] Figure 3 It is a graph showing the relationship between the limiting rate [%] of the discharge capacity of the secondary battery 110 in the first embodiment and the threshold value of the discharge voltage [V] of the secondary battery 110.

[0015] Figure 4It is a graph showing the relationship between the allowable power per unit time [kW / sec] of the secondary battery 110 in the first embodiment and the threshold value of the discharge voltage [V] of the secondary battery 110.

[0016] Figure 5 It is a graph representing the oscillation phenomenon of a comparative secondary battery.

[0017] Figure 6 It is a graph showing the relationship between the limiting rate [%] of the allowable charging power of the secondary battery 110 in the second embodiment and the threshold value of the charging voltage [V] of the secondary battery 110. Detailed Implementation

[0018] (First Implementation)

[0019] (Structure of battery system 1 including control device 10 of secondary battery 110)

[0020] Reference Figures 1 to 4 The structure of the battery system 1, which includes the control device 10 containing the secondary battery 110, will be described.

[0021] Figure 1 This is a block diagram showing a battery system 1, etc., including a control device 10 containing a secondary battery 110 according to the first embodiment. Figure 2 This is a block diagram representing the battery state estimation and control unit 400 of battery system 1. Figure 3 It is a graph showing the relationship between the limiting rate [%] of the discharge capacity of the secondary battery 110 in the first embodiment and the threshold value of the discharge voltage [V] of the secondary battery 110. Figure 4 It is a graph showing the relationship between the allowable power per unit time [kW / sec] of the secondary battery 110 in the first embodiment and the threshold value of the discharge voltage [V] of the secondary battery 110.

[0022] In the first embodiment, such as Figure 2 As shown, the control device 10 of the secondary battery 110 includes, for example, the allowable power setting unit 421 and the allowable power limiting unit 422 of the battery state estimation control unit 400 of the battery system 1.

[0023] Battery system 1 is a system that supplies electrical power from secondary battery 110 to external devices. These devices include, for example, electric vehicles, hybrid vehicles, trams, and industrial equipment. Figure 1 The battery system 1 shown is a system that supplies electrical power to the secondary battery 110 from the electric generator 1300 (M / G) used for driving a hybrid electric vehicle.

[0024] Battery system 1 is connected to inverter 1200 via a pair of relays 1100. Inverter 1200 converts the electrical power from secondary battery 110 from DC to AC and supplies it from battery system 1 to electric generator 1300. Figure 1 In this configuration, the electric generator 1300 is referred to as M / G. The motor / inverter control unit 1400 controls the inverter 1200 and the electric generator 1300. The vehicle control unit 1500 determines the distribution of electrical power output from the combined battery 100 based on information input from the battery system 1 regarding the secondary battery 110, information input from the motor / inverter control unit 1400, information input from the engine (not shown), etc.

[0025] like Figure 1 As shown, the battery system 1 includes a battery pack 100, a battery control unit 200, a measurement unit 300, a battery state estimation and control unit 400, a communication unit 500, and a storage unit 600. The structure of the battery pack 100 to the storage unit 600 included in the battery system 1 will be described below.

[0026] (Structure of battery pack 100)

[0027] Reference Figure 1 The structure of the battery pack 100 is described.

[0028] The battery pack 100 supplies electrical power to an external device. The battery pack 100 includes multiple secondary batteries 110. In the battery pack 100, the multiple secondary batteries 110 are divided into two groups: a first battery pack 100A and a second battery pack 100B. The battery pack 100 can have three or more groups, or it can have only one group. The first battery pack 100A and the second battery pack 100B are connected in series. The first battery pack 100A and the second battery pack 100B can also be connected in parallel. In the first battery pack 100A and the second battery pack 100B, the multiple secondary batteries 110 are connected in series. In the first battery pack 100A and the second battery pack 100B, the multiple secondary batteries 110 can be connected in series and in parallel, or they can be connected in parallel. The secondary batteries 110 are, for example, lithium-ion secondary batteries. The secondary batteries 110 can also be nickel-metal hydride batteries, lead-acid batteries, double-layer capacitors, or other rechargeable batteries, as well as devices with energy storage functions.

[0029] (Structure of the battery control unit 200)

[0030] Reference Figure 1 The structure of the battery control unit 200 will be explained.

[0031] The battery control unit 200 controls the secondary batteries 110 included in the battery pack 100. The battery control unit 200 includes a first battery control unit 210 and a second battery control unit 220. The first battery control unit 210 controls the first battery pack 100A based on information input from the battery state estimation control unit 400, the measurement unit 300, etc. The first battery control unit 210 measures the voltage of each secondary battery 110 included in the first battery pack 100A. Drive power is supplied from the first battery pack 100A to the first battery control unit 210. The second battery control unit 220 controls the second battery pack 100B based on information input from the battery state estimation control unit 400, the measurement unit 300, etc. The second battery control unit 220 measures the voltage of each secondary battery 110 included in the second battery pack 100B. Drive power is supplied from the second battery pack 100B to the second battery control unit 220. The battery control unit 200 may also be integrally configured with the battery state estimation control unit 400.

[0032] (Structure of measuring unit 300)

[0033] Reference Figure 1 The structure of the measuring unit 300 will be explained.

[0034] The measuring unit 300 measures the current, voltage, and temperature of the secondary batteries 110 included in the battery pack 100. The measuring unit 300 includes a current measuring unit 310, a voltage measuring unit 320, and a temperature measuring unit 330. The current measuring unit 310 measures the current of the secondary batteries 110 included in the battery pack 100. The current measuring unit 310 is connected in series with the battery pack 100. The voltage measuring unit 320 measures the voltage of the secondary batteries 110 included in the battery pack 100. The voltage measuring unit 320 is connected in parallel with the battery pack 100. The temperature measuring unit 330 measures the temperature of one or more secondary batteries 110 included in the battery pack 100. The temperature measuring unit 330 is mounted on the secondary batteries 110. The measuring unit 300 may also be integrated with the battery state estimation and control unit 400.

[0035] (Structure of the battery state estimation and control unit 400)

[0036] Reference Figures 1 to 4 The structure of the battery state estimation and control unit 400 will be explained.

[0037] The battery state estimation and control unit 400 estimates and controls the state of the secondary battery 110 included in the battery pack 100. The battery state estimation and control unit 400 includes a SOC / SOHR calculation unit 410 and a battery state calculation unit 420.

[0038] (Structure of SOC / SOHR Computing Unit 410)

[0039] Reference Figure 2The structure of the SOC / SOHR computing unit 410 will be described.

[0040] The SOC / SOHR calculation unit 410 calculates the State of Charge (SOC) and State of Health (SOHR) based on the current, voltage, and temperature of the secondary battery 110 input from the measurement unit 300. The SOC / SOHR calculation unit 410 outputs the calculated SOC and SOHR of the secondary battery 110 to the battery state calculation unit 420.

[0041] The information input to the SOC / SOHR calculation unit 410 regarding the voltage of the secondary battery 110 includes the maximum voltage, average voltage, minimum voltage, and voltage deviation of the secondary battery 110. The information regarding the current of the secondary battery 110 includes the instantaneous current acquired at the same timing as the voltage acquisition. The information regarding the current of the secondary battery 110 includes the interval average current, which is obtained by continuously sampling the current flowing in the battery pack 100 over a specified time period and averaging the multiple sampled current values. The information regarding the temperature of the secondary battery 110 includes the highest temperature, average temperature, and lowest temperature obtained from multiple temperature sensors installed in the battery pack 100. The temperature information of the secondary battery 110 includes a temperature reflecting the temperature distribution of the battery pack 100, the first battery pack 100A, the second battery pack 100B, and the secondary battery 110. The information input to the SOC / SOHR calculation unit 410 includes diagnostic results indicating whether the secondary battery 110 is overcharged or over-discharged, and abnormal signals output from the communication unit 500 in the event of a communication error, etc. Diagnosis of the secondary battery 110 is performed, for example, by the measuring unit 300.

[0042] Alternatively, the SOC / SOHR calculation unit 410 can be replaced with an SOC / SOHC calculation unit. That is, in the first embodiment, a structure that calculates SOHC instead of SOHR can also be used. SOHC (State of Health based on Capacity) is the rate of capacity degradation of the secondary battery 110. In such a structure, the structure that calculates the increase in the resistance value of the secondary battery 110 is changed to a structure that calculates the capacity of the secondary battery 110. That is, in such a structure, the capacity of the secondary battery 110 is calculated based on the SOC of the secondary battery 110 at a predetermined time point and the value of the accumulated current of the secondary battery 110 after the predetermined time point. In addition, in the first embodiment, a structure that uses both the SOC / SOHR calculation unit 410 and the SOC / SOHC calculation unit can also be used.

[0043] (Structure of the battery status calculation unit 420)

[0044] Reference Figures 2 to 4 The structure of the battery status calculation unit 420 will be explained.

[0045] The battery state calculation unit 420 calculates the state of the secondary battery 110 included in the battery pack 100. Information such as the SOC and SOHR of the secondary battery 110 is input from the SOC / SOHR calculation unit 410 to the battery state calculation unit 420. Based on the information regarding the SOC and SOHR of the secondary battery 110, the battery state calculation unit 420 calculates and outputs the allowable charging power and allowable discharging power of the secondary battery 110. The allowable charging power of the secondary battery 110 is the electrical power equivalent to the upper limit voltage of the rechargeable voltage of the secondary battery 110, and is an electrical power including a predetermined margin. The allowable discharging power of the secondary battery 110 is the electrical power equivalent to the lower limit voltage of the dischargeable voltage of the secondary battery 110, and is an electrical power including a predetermined margin.

[0046] The battery status calculation unit 420 includes a permissible power setting unit 421 and a permissible power limiting unit 422.

[0047] (Structure of the allowable power setting unit 421)

[0048] Reference Figure 2 The structure of the allowable power setting unit 421 included in the battery state calculation unit 420 will be described.

[0049] The permissible power setting unit 421 is included in the control device 10 of the secondary battery 110.

[0050] The allowable power setting unit 421 sets the allowable power value of the secondary battery 110 during discharge and charging based on specified information of the secondary battery 110. The specified information includes the voltage value (OCV), current value, internal resistance value (DCR: Direct Current Resistance), state of charge, temperature, and degradation state (SOHR, SOHC) of the secondary battery 110. The allowable power value of the secondary battery 110 is set based on the allowable voltage value of the secondary battery 110.

[0051] The allowable power setting unit 421 sets the allowable power of the secondary battery 110 based on its SOC, SOHR, voltage, current, and temperature. The allowable power setting unit 421 inputs battery information (SOC, voltage, temperature, and current, etc.) of the secondary battery 110 into its equivalent circuit model and calculates the allowable power of the secondary battery 110. In other words, the allowable power setting unit 421 sets the allowable power of the secondary battery 110 based on its equivalent circuit model. The equivalent circuit model of the secondary battery 110 is determined by... Figure 2 The permissible power setting unit 421 shown corresponds to equation (1) described later.

[0052] (Structure of the permissible power limiting unit 422)

[0053] Reference Figures 2 to 4 The structure of the allowable power limiting unit 422 included in the battery state calculation unit 420 will be described.

[0054] The permissible power limiting unit 422 is included in the control device 10 of the secondary battery 110.

[0055] The permissible power limiting unit 422 determines, based on information such as the SOC, voltage, current, and temperature of the secondary battery 110, whether the permissible power of the secondary battery 110 should be limited, according to the permissible power set by the permissible power setting unit 421. If the permissible power limiting unit 422 determines that the permissible power of the secondary battery 110 should be limited, then the permissible power of the secondary battery 110 is limited.

[0056] The permissible power limiting unit 422, for example, limits the power value of the secondary battery 110 before it reaches the permissible power value during discharge, for example, when the secondary battery 110 is discharging. The permissible power limiting unit 422 limits the power value in stages at two different ratios. During discharge, the permissible power limiting unit 422 limits the power value in stages such that the change in power value per unit time caused by the limitation of the earlier applied power value is less than the change in power value per unit time caused by the limitation of the later applied power value. The change in power value per unit time caused by the limitation of the earlier applied power value is less than... Figure 3 The change in the first limiting rate region S1 is equivalent to the change in the power value. The change in power value corresponds to the limiting rate [%] of the allowable discharge power of the secondary battery 110 and the allowable discharge power [kW] of the secondary battery 110. The change in power value per unit time caused by the power value limitation implemented later is equivalent to the change in power value per unit time. Figure 3 The change in the second limiting rate region S2 is comparable.

[0057] The permissible power limiting unit 422 begins limiting the power value of the secondary battery 110 when the electrical power of the secondary battery 110 decreases to a predetermined threshold that limits the power value of the secondary battery 110. The predetermined threshold is related to... Figure 3 The first threshold Vth1 shown is equivalent to this. A specified threshold is, for example, 3.0V in OCV. Specified thresholds include those measured by sensors, such as the voltage V, temperature T, current I, and container pressure of the secondary battery 110. Specified thresholds also include computationally based thresholds, such as the SOC of the secondary battery 110.

[0058] The permissible power limiting unit 422 releases the power limit after limiting the power value. Compared to the first threshold when limiting the power value, the permissible power limiting unit 422 relaxes the second threshold when releasing the power value limit. For example, if the permissible power limiting unit 422 starts limiting the permissible power of the secondary battery 110 when the SOC is 90%, it releases the permissible power limit of the secondary battery 110 after the SOC becomes 80%. Furthermore, if the permissible power limiting unit 422 starts limiting the permissible power of the secondary battery 110 when the voltage of the secondary battery 110 is 4.3V, it releases the permissible power limit of the secondary battery 110 after the voltage of the secondary battery 110 becomes 4.2V.

[0059] (Structure of the variable amount limiting part 422A)

[0060] Reference Figure 2 The structure of the variable amount limiting part 422A will be explained.

[0061] The variation limiting unit 422A includes a charging variation limiting unit 422A1 and a discharging variation limiting unit 422A2.

[0062] To suppress abrupt changes in the allowable charging power of the secondary battery 110 during charging, the charging variation limiting unit 422A1 limits the maximum change in the allowable charging power of the secondary battery 110 per unit time. A set allowable charging power is input from the allowable power setting unit 421 to the charging variation limiting unit 422A1. The set allowable charging power differs from the final allowable power output from the allowable power limiting unit 422. The charging allowable limit value is input from the allowable charging power limiting unit 422B1 to the charging variation limiting unit 422A1 via the charging multiplication unit 431. The charging variation limiting unit 422A1 calculates and outputs the allowable charging power based on the set allowable charging power input from the allowable power setting unit 421 and the charging allowable limit value input from the allowable charging power limiting unit 422B1.

[0063] In order to suppress drastic changes in the allowable discharge power of the secondary battery 110 during discharge, the discharge variation limiting unit 422A2 limits the maximum change in the allowable discharge power of the secondary battery 110 per unit time during discharge. The set allowable discharge power is input from the allowable power setting unit 421 to the discharge variation limiting unit 422A2. The set allowable discharge power differs from the final allowable power output from the allowable power limiting unit 422. The allowable discharge limit value is input from the allowable discharge power limiting unit 422B2 to the discharge variation limiting unit 422A2 via the discharge multiplication unit 432. The discharge variation limiting unit 422A2 calculates and outputs the allowable discharge power based on the set allowable discharge power input from the allowable power setting unit 421 and the allowable discharge limit value input from the allowable discharge power limiting unit 422B2.

[0064] (Structure of the permissible power limiting section 422B)

[0065] Reference Figure 2 The structure of the permissible power limiting unit 422B will be described.

[0066] The permissible power limiting unit 422B includes a charging permissible power limiting unit 422B1 and a discharging permissible power limiting unit 422B2.

[0067] The voltage, current, and temperature of the secondary battery 110 during charging are input from the measuring unit 300 to the charging allowable power limiting unit 422B1. The SOC of the secondary battery 110 during charging is input from the SOC / SOHR calculation unit 410 to the charging allowable power limiting unit 422B1. The charging allowable power limiting unit 422B1 outputs a signal regarding the allowable power of the secondary battery 110 during charging to the charging variation limiting unit 422A1 of the variation limiting unit 422A1 via the charging multiplication unit 431. The charging multiplication unit 431 sets a charging limit rate from 100% (unrestricted) to 0% (fully limited, 0kW) for the allowable power of the secondary battery 110 during charging.

[0068] The voltage, current, and temperature of the secondary battery 110 during discharge are input from the measuring unit 300 to the discharge allowable power limiting unit 422B2. The SOC of the secondary battery 110 during discharge is input from the SOC / SOHR calculation unit 410 to the discharge allowable power limiting unit 422B2. The discharge allowable power limiting unit 422B2 outputs a signal related to the limitation of the allowable power of the secondary battery 110 during discharge to the discharge variation limiting unit 422A2 of the variation limiting unit 422A2 via the discharge multiplication unit 432. The discharge multiplication unit 432 sets a discharge limitation rate from 100% (unrestricted) to 0% (fully limited, 0kW) for the allowable power of the secondary battery 110 during discharge.

[0069] (Voltage of secondary battery 110)

[0070] The voltage V of the secondary battery 110 is explained with reference to formula (1).

[0071] Equation (1) represents the voltage V of the secondary battery 110.

[0072]

[0073] The voltage V of the secondary battery 110 is represented by the sum of the open circuit voltage (OCV), the value obtained by multiplying the current I by the DC resistance Ro, and the value obtained by connecting the capacitor component τ in parallel with the polarization voltage Vp. The polarization voltage Vp is generated when the current I flows through the parallel circuit of the polarization resistor Rp and the polarization capacitance component CR of the secondary battery 110.

[0074] (Permissible charging power of secondary battery 110)

[0075] The allowable charging power of the secondary battery 110 is explained with reference to equations (2) to (5).

[0076] Equation (2) represents the rechargeable current Ichg of the secondary battery 110.

[0077]

[0078] The rechargeable current Ichg of the secondary battery 110 is the maximum current that can be input to the secondary battery 110. Figure 2 In the equivalent circuit model of the secondary battery 110 shown in the allowable power setting unit 421, the current of the secondary battery 110 when the voltage V of the secondary battery 110 is equal to the upper limit voltage Vmax used in the battery system 1 is given. Equation (2) is derived by replacing Equation (1) with the current I as the reference and modifying the I×Ro part. Referring to the OCV-SOC mapping which represents the correspondence between the SOC of the secondary battery 110 and the battery temperature, the open-circuit voltage OCV of the secondary battery 110 is calculated based on the current SOC and temperature T of the secondary battery 110. Referring to the Ro mapping, the DC resistance Ro of the secondary battery 110 is calculated based on the current SOC and temperature T of the secondary battery 110.

[0079] Equation (3) represents the maximum rechargeable current Imax,chg of the secondary battery 110.

[0080]

[0081] The secondary battery 110 is controlled to be charged such that even if the chargeable current is less than the maximum chargeable current Imax, chg will not exceed the upper limit current Ilimit on the charging side of the battery system 1.

[0082] Equation (4) represents the maximum rechargeable voltage Vmax,chg of the secondary battery 110.

[0083]

[0084] Equation (4) is derived by transforming the I×Ro portion of Equation (1). The Ro mapping is composed of the new value of the secondary battery 110. Equation (4) takes into account the degradation of the secondary battery 110 by multiplying the Ro mapping by the SOHR of the secondary battery 110.

[0085] Equation (5) represents the allowable charging power Wchg of the secondary battery 110.

[0086]

[0087] The allowable charging power Wchg of the secondary battery 110 is derived by multiplying the allowable charging current Imax,chg shown in equation (3) with the rechargeable voltage Vmax,chg shown in equation (4). The combined battery 100 is constructed by connecting N secondary batteries 110 in series. Therefore, the allowable charging power Wchg of the combined battery 100 is expressed by setting the allowable charging power of the secondary batteries 110 to N times.

[0088] (Permissible discharge capacity of secondary battery 110)

[0089] The allowable discharge capacity of the secondary battery 110 is explained with reference to equations (6) to (9).

[0090] Equation (6) represents the discharge current Idischg of the secondary battery 110.

[0091]

[0092] The discharge current Idischg of the secondary battery 110 is the maximum current that the secondary battery 110 can output. The discharge current Idischg of the secondary battery 110 is... Figure 2 In the equivalent circuit model of the secondary battery 110 shown in the allowable power setting unit 421, the current of the secondary battery 110 is defined as the current when the voltage V of the secondary battery 110 is equal to the lower limit voltage Vmin used in the battery system 1. Equation (6) is derived by modifying the part of equation (1) related to the current I.

[0093] Equation (7) represents the maximum discharge current Imax,dischg of the secondary battery 110.

[0094]

[0095] The secondary battery 110 is controlled to discharge such that even if the discharge current Imax is less than the rechargeable current, the discharge current will not exceed the upper limit current Ilimit on the discharge side of the battery system 1.

[0096] Equation (8) represents the maximum discharge voltage Vmax,dischg of the secondary battery 110.

[0097]

[0098] Equation (8) is derived by partially transforming the I×Ro of Equation (1). The Ro mapping is composed of the new value of the secondary battery 110. Equation (8) takes into account the case where the secondary battery 110 is degraded by multiplying the Ro mapping by the SOHR of the secondary battery 110.

[0099] Equation (9) represents the allowable discharge power Wdischg of the secondary battery 110.

[0100]

[0101] The allowable discharge capacity Wdischg of the secondary battery 110 is derived by multiplying the allowable discharge current Imax,dischg shown in equation (7) with the discharge voltage Vmax,dischg shown in equation (8). The combined battery 100 is constructed by connecting N secondary batteries 110 in series. Therefore, the allowable discharge capacity Wdischg of the combined battery 100 is expressed by setting the allowable discharge capacity of the secondary batteries 110 to N times.

[0102] (The calculation principle of the charging limit rate Dchg of the secondary battery 110 performed by the charging allowable power limit unit 422B1)

[0103] The calculation principle of the charging limit rate Dchg of the secondary battery 110 by the charging allowable power limit unit 422B1 is explained with reference to formula (10).

[0104] Equation (10) represents the charging limit rate Dchg of the secondary battery 110.

[0105]

[0106] Dmax_chg is the maximum value of the charging limit rate Dchg of secondary battery 110. Dvol_chg is the charging limit rate of secondary battery 110 due to overcharging. Dsoc_chg is the charging limit rate of secondary battery 110 due to reaching the upper limit of SOC of secondary battery 110. Dcur is the charging limit rate of secondary battery 110 due to abnormal current of secondary battery 110. Dtemp is the charging limit rate of secondary battery 110 due to abnormal temperature of secondary battery 110.

[0107] Each limiting rate is set within the range of 0% to 100%. After calculating each limiting rate by the charging allowable power limiting unit 422B1, the charging limiting rate Dchg of the secondary battery 110 is determined based on the minimum limiting rate among the various limiting rates. If any one of the indicators representing the battery state, such as voltage V, current I, temperature T, and SOC, of ​​the secondary battery 110 becomes abnormal, the charging allowable power limiting unit 422B1 limits the charging allowable power of the secondary battery 110. In this case, it is preferable to determine the charging limiting rate Dchg of the secondary battery 110 based on the minimum limiting rate, i.e., the most stringent limiting rate.

[0108] Dchg is the charging limit rate. Dchg is set within the range of 0% to Dmax_chg%. When Dmax_chg is set to 100%, Dchg is calculated unrestricted based on Dvol_chg, Dsoc_chg, Dcur, and Dtemp. When Dmax_chg is set to less than 100%, an upper limit of Dchg is calculated based on factors other than the voltage, current, temperature, and SOC of the secondary battery 110. That is, Dmax_chg can be used as a margin means to always set the limit rate for the allowable power of the secondary battery 110, or it can be used to set an upper limit for the limit rate based on factors not caused by the state of the secondary battery 110.

[0109] (The principle of calculating the discharge limit rate Ddischg of the secondary battery 110 by the discharge capacity allowable power limiting section 422B2)

[0110] The principle of calculating the discharge limitation rate Ddischg of the secondary battery 110 by the discharge capacitor allowable power limiting unit 422B2 is explained with reference to Equation (11).

[0111] Equation (11) represents the discharge limitation rate Ddischg of the secondary battery 110.

[0112]

[0113] Dmax_dischg is the maximum value of the limiting rate Ddischg of the secondary battery 110. Dvol_dischg is the limiting rate of charging the secondary battery 110 due to overcharging. Dsoc_dischg is the limiting rate of charging the secondary battery 110 due to reaching the lower limit of the SOC of the secondary battery 110. The calculation method of the limiting rate Dvol_dischg is equivalent to the calculation method of the limiting rate of the discharge voltage of the secondary battery 110 by the discharge capacitor allowable power limiting unit 422B2. Dcur is the limiting rate of charging the secondary battery 110 due to abnormal current. Dtemp is the limiting rate of charging the secondary battery 110 due to abnormal temperature.

[0114] Each limiting rate is set within the range of 0% to 100%. After each limiting rate is calculated by the discharge capacity allowable power limiting unit 422B2, the discharge limiting rate Ddischg of the secondary battery 110 is determined based on the minimum limiting rate among the various limiting rates.

[0115] Ddischg is the discharge limitation rate. Ddischg is set within the range of 0% to Dmax_dischg%. When Dmax_dischg is set to 100%, Ddischg is calculated unrestricted based on Dvol_dischg, Dsoc_dischg, Dcur, and Dtemp. When Dmax_dischg is set to less than 100%, an upper limit for Ddischg is calculated based on factors other than the voltage, current, temperature, and SOC of the secondary battery 110.

[0116] (An example of calculating the discharge limit rate Ddischg of the secondary battery 110 by the discharge limit unit 422B2)

[0117] Reference Figure 3 Equation (11) illustrates an example of calculating the discharge limit rate Ddischg of the secondary battery 110 by the discharge capacitor power limit unit 422B2.

[0118] The upper limit threshold Vth_sys is a threshold equivalent to the upper limit of the voltage of the secondary battery 110 within the normal operating range of battery system 1. The upper limit threshold Vth_sys is, for example, the voltage at which lithium deposition will occur in the secondary battery 110.

[0119] The lower limit threshold Vth_cell is a threshold corresponding to the lower limit of the voltage of the secondary battery 110 within the normal operating range of battery system 1. The lower limit threshold Vth_cell is, for example, the voltage of the secondary battery 110 just before it is about to be over-discharged.

[0120] The limiting rate is set in two regions: a first limiting rate region S1 and a second limiting rate region S2. The first limiting rate region S1 and the second limiting rate region S2 are adjacent. The first limiting rate region S1 and the second limiting rate region S2 are set between the upper limit threshold Vth_sys and the lower limit threshold Vth_cell.

[0121] The first limiting rate region S1 is set at a position closer to the upper threshold Vth_sys than the second limiting rate region S2. The first threshold Vth1 is set to a value below the upper threshold Vth_sys. The first limiting rate region S1 is defined as the voltage region from the first threshold Vth1 to the second threshold Vth2. The first threshold Vth1 is the voltage value at the start of the voltage limiting of the secondary battery 110 in the first limiting rate region S1. The second threshold Vth2 is the voltage value at the end of the voltage limiting of the secondary battery 110 in the first limiting rate region S1.

[0122] The second limiting rate region S2 is set at a lower threshold Vth_cell level than the first limiting rate region S1. The third threshold Vth3 is set to a value above the lower threshold Vth_cell. The second limiting rate region S2 is defined as the voltage region from the second threshold Vth2 to the third threshold Vth3. The second threshold Vth2 is the voltage value at the start of voltage limiting of the secondary battery 110 in the second limiting rate region S2. The third threshold Vth3 is the voltage value at the end of voltage limiting of the secondary battery 110 in the second limiting rate region S2.

[0123] The second threshold Vth2 serves as both the end voltage threshold of the first limiting rate region S1 and the start voltage threshold of the second limiting region. The second threshold Vth2 is a value between the first threshold Vth1 and the third threshold Vth3, and is set to be closer to the third threshold Vth3 than the first threshold Vth1. The second threshold Vth2 is set to allow the transition from the first limiting region S1 to the second limiting rate region S2 when the voltage of the secondary battery 110 drops to near the over-discharge voltage.

[0124] Equation (12) represents the relationship between the first threshold Vth1, the third threshold Vth3, and the second threshold Vth2 of the secondary battery 110.

[0125]

[0126] The first limiting rate region S1 is the region where the voltage limiting rate of the secondary battery 110 is within the range of 100% to a_Vth2 (%). The second limiting rate region S2 is the region where the voltage limiting rate of the secondary battery 110 is within the range of a_Vth2 (%) to 0%. The second threshold Vth2 is the limiting rate that forms the boundary between the first limiting rate region S1 and the second limiting rate region S2. The second threshold Vth2 is set to a value where the voltage limiting rate of the secondary battery 110 exceeds 50% but is less than 100%. That is, the limiting rate range of the first limiting rate region S1 is set to be larger than the limiting rate range of the second limiting rate region S2.

[0127] Compared to the second limiting rate region S2, the first limiting rate region S1 has a wider voltage range and a smaller limiting rate change per unit voltage. For example... Figure 3 As shown, the slope of the change in the limiting rate in the first limiting rate region S1 is set to be gentler than the slope of the second limiting rate region S2. The first limiting rate region S1, with a gentle slope, is set on the upper limit threshold Vth_sys side of battery system 1. The second limiting rate region S2, with a sharp slope, is set on the lower limit threshold Vth_cell side of battery system 1.

[0128] (Standard limits on the discharge voltage of secondary battery 110)

[0129] Reference Figure 3 The conventional limitations on the discharge voltage of the secondary battery 110 are explained.

[0130] Battery system 1 typically operates within a voltage range above the lower threshold Vth_cell. Battery system 1 repeatedly charges and discharges the secondary battery 110 based on the conditions of the electric vehicle equipped with battery system 1. For example, if an abnormality occurs in the secondary battery 110 or the electric vehicle, causing the voltage of the secondary battery 110 to drop sharply below the upper threshold Vth_sys and then decrease towards the lower threshold Vth_cell, battery system 1 limits the discharge voltage of the secondary battery 110. That is, when the voltage of the secondary battery 110 exceeds a predetermined value and decreases, battery system 1 limits the allowable discharge power of the secondary battery 110 to prevent the voltage of the secondary battery 110 from falling below the lower threshold Vth_cell.

[0131] (Discharge capacity limiter 422B2 limits the discharge capacity of the secondary battery 110.)

[0132] Reference Figure 3 This section explains how the discharge capacity limiter 422B2 limits the discharge capacity of the secondary battery 110.

[0133] Figure 3 The vertical axis on the right shows the allowable discharge capacity of the secondary battery 110 and... Figure 3 The left vertical axis shows the limiting rate of the discharge capacity of the secondary battery 110, which is related to the limiting rate of the discharge capacity. Figure 3 The allowable power W1 of the secondary battery 110 shown on the right vertical axis is... Figure 3 The left vertical axis shows the electrical power of the secondary battery 110 at a discharge capacity limit of 100%. Figure 3 The allowable power W2 of the secondary battery 110 shown on the right vertical axis is... Figure 3 The power of the secondary battery 110 at a discharge capacitance of 2% (a_Vth) is shown on the left vertical axis.

[0134] (Based on the gradual limitation of the discharge voltage in the first limiting rate region S1 of the secondary battery 110)

[0135] Reference Figure 3 and Figure 4 The gradual limitation of the discharge voltage in the first limiting rate region S1 based on the secondary battery 110 is explained.

[0136] When the voltage of the secondary battery 110 falls below the upper limit threshold Vth_sys and is less than the first threshold Vth1, the voltage of the secondary battery 110 enters the first limiting rate region S1. When the first threshold Vth1 is the same as or near the upper limit threshold Vth_sys, the probability of the voltage of the secondary battery 110 falling below the upper limit threshold Vth_sys is relatively higher. Even if the voltage of the secondary battery 110 is less than the first threshold Vth1, the limiting rate of the voltage of the secondary battery 110 is gentle when it is above the second threshold Vth2. That is, a first limiting rate region S1 with relatively gentle limiting of the discharge voltage is set near the upper limit threshold Vth_sys of the secondary battery, so the discharge voltage of the secondary battery is not excessively limited. The gentle limiting of the secondary battery 110 based on the first limiting rate region S1 suppresses the generation of oscillation phenomena in the discharge voltage of the secondary battery 110. That is, compared with the secondary battery of the comparative example, the secondary battery 110 of the first embodiment suppresses the occurrence of oscillation phenomena. Furthermore, since a first limiting rate region S1 with a relatively gentle discharge voltage limit is set near the upper limit threshold Vth_sys of the secondary battery 110, the limiting of the discharge voltage of the secondary battery 110 begins relatively early. Thus, the voltage drop of the secondary battery 110 is safely suppressed. Figure 4 The allowable power W2 per unit time of the secondary battery in the first limiting rate region S1 shown is compared with Figure 3 The limit value of a_Vth2% of the allowable discharge power of the secondary battery 110 in the first limiting rate region S1 shown is related to this limit.

[0137] (Based on the sharp limitation of the discharge voltage in the second limiting rate region S2 of the secondary battery 110) Refer to Figure 3 and Figure 4 The sharp limitation of the discharge voltage in the second limiting rate region S2 based on the secondary battery 110 is explained.

[0138] When the voltage of the secondary battery 110 is less than the second threshold Vth2, the voltage of the secondary battery 110 enters the second limiting rate region S2. The abrupt limitation of the discharge voltage in the second limiting rate region S2 prevents the discharge voltage of the secondary battery 110 from reaching the lower limit threshold Vth_cell. That is, when the gradual limitation in the first limiting rate region S1 cannot suppress the decrease in the discharge voltage of the secondary battery 110, the abrupt limitation in the second limiting rate region S2 is used to suppress it. Figure 4 The allowable power W1 per unit time of the secondary battery in the second limiting rate region S2 shown is... Figure 3 The second limiting rate region S2 shown is related to the 100% limit value of the discharge capacity of the secondary battery 110.

[0139] (Oscillation of discharge voltage of a comparative secondary battery)

[0140] Reference Figure 5 The oscillation of the discharge voltage of the comparative secondary battery is explained.

[0141] Figure 5 It is a graph representing the oscillation phenomenon of a comparative secondary battery. Figure 5 (A) is a graph showing the relationship between the discharge voltage [V] of the comparative secondary battery and time. Figure 5 (B) is a graph showing the relationship between the limiting rate [%] of the discharge voltage of the comparative secondary battery and time. Figure 5 (C) is a graph showing the relationship between the allowable discharge power [kW] of the secondary battery in the comparative example and time. Time t1 < time t2 < time t3 < time t4 < time t5 < time t6.

[0142] The comparative secondary battery is a secondary battery controlled by a conventional secondary battery control device. The comparative secondary battery exhibits oscillation phenomena in its discharge voltage, such as a sharp increase in the discharge voltage limit. Furthermore, the oscillation phenomenon is characterized by frequent release of the discharge voltage limit.

[0143] Time t1 represents the state before the voltage of the secondary battery is limited. At time t1, the voltage of the secondary battery is greater than the upper limit threshold Vth_sys. At time t1, the limitation rate of the secondary battery is 100%. At time t1, the allowable discharge power of the secondary battery is not limited. At times t1, t2, t3, and t4, when the voltage of the secondary battery drops sharply, the following applies.

[0144] From time t2 to time t3, the voltage of the secondary battery is less than the upper limit threshold Vth_sys. From time t2 to time t3, the voltage of the secondary battery is above the first threshold Vth1. From time t2 to time t3, there is no limit to the allowable discharge power of the secondary battery. Therefore, from time t2 to time t3, the secondary battery continues to discharge, and the voltage decreases.

[0145] When time t3 is exceeded, the voltage of the secondary battery becomes lower than the first threshold Vth1. Therefore, the discharge limitation rate of the secondary battery decreases, and the allowable discharge power of the secondary battery begins to decrease. In other words, the discharge of the secondary battery is limited.

[0146] When time t4 is exceeded, the allowable discharge power of the secondary battery further decreases, meaning that the discharge of the secondary battery is further restricted. Therefore, from time t4 to time t5, the voltage of the secondary battery recovers.

[0147] When time t5 is reached, the discharge limit of the secondary battery returns to 100%. At time t5, the discharge of the secondary battery increases.

[0148] At time t6, the voltage of the secondary battery begins to decrease again. Subsequently, the comparative secondary battery repeats the behavior from time t1 to time t6. That is, the comparative secondary battery repeatedly experiences a decrease and increase in its discharge capacity within a relatively short period, potentially making the battery system's operation unstable.

[0149] (Structure of the Communications Department 500)

[0150] Reference Figure 1 The structure of the Communications Section 500 will be explained.

[0151] The communication unit 500 communicates information about the secondary battery 110 and other components among the multiple structures included in the battery system 1. The communication unit 500 communicates between the first battery control unit 210 and the second battery control unit 220. The communication unit 500 connects the first battery control unit 210 and the battery state estimation control unit 400, and the second battery control unit 220 and the battery state estimation control unit 400, in a loop. Such a connection is called a daisy-chain connection, a beaded connection, or a series connection.

[0152] The communication unit 500 communicates with the first battery control unit 210 and the battery state estimation control unit 400 via an insulating element. The communication unit 500 also communicates with the second battery control unit 220 and the battery state estimation control unit 400 via an insulating element. The insulating element is, for example, an optocoupler. The insulating element eliminates the difference between the reference potential of the battery control unit 200 and the reference potential of the battery state estimation control unit 400. The battery state estimation control unit 400 is supplied with drive power from a battery for vehicle auxiliary equipment (reference potential, for example, 12V). Drive power is also supplied to the battery control unit 200 from the battery pack 100 (reference potential, for example, 48V or higher).

[0153] (Structure of storage unit 600)

[0154] Reference Figure 1 The structure of the storage unit 600 will be described.

[0155] The storage unit 600 stores information related to the secondary battery 110, etc. This information includes, for example, information about the internal resistance characteristics, polarization resistance characteristics, degradation characteristics, full-charge capacity, and individual differences of the secondary battery 110. The storage unit 600 also stores mappings related to the secondary battery 110. These mappings, for example, relate to a mapping (OCV-SOC mapping) that represents the correspondence between the open-circuit voltage (OCV) and the state of charge (SOC) of the secondary battery 110. The storage unit 600 may also be integrated with the battery state estimation control unit 400 and the battery control unit 200.

[0156] (Confirmation of the effectiveness of implementing the first embodiment)

[0157] Reference Figure 3 The discharge capacity of the secondary battery 110 is used to illustrate the effectiveness of the implementation related to the first embodiment.

[0158] If the first implementation method is effective, then Figure 3 The curve showing the allowable discharge power [kW] obtained by actual measurement through the secondary battery 110, displayed on the right vertical axis, becomes a parallel curve with... Figure 3 The curve on the left vertical axis shows a similar discharge limitation rate [%] curve to the secondary battery 110. That is, if the implementation of the first embodiment is effective, the waveform of the measured discharge voltage of the secondary battery 110 becomes a waveform containing multiple sloping regions. The waveform containing multiple sloping regions is equivalent to the waveform in the first limitation rate region S1 and the waveform in the second limitation rate region S2.

[0159] The effectiveness of the first embodiment is confirmed by measuring the discharge voltage of the secondary battery 110 from the upper threshold Vth_sys to the lower threshold Vth_cell. The voltage of the secondary battery 110 is measured at certain intervals, such as 0.1V intervals. The measurement of the secondary battery 110 is performed after a sufficiently long predetermined time, such as 1 minute, following the setting of each discharge voltage. The reason for setting the predetermined time is that the discharge voltage of the secondary battery 110 is generally limited by the amount of variation. Therefore, after a predetermined time has elapsed since the allowable power variation of the secondary battery 110 has ended, the stable discharge voltage of the secondary battery 110 is measured.

[0160] Regarding the effectiveness of implementing the first embodiment, the effectiveness of the implementation is also confirmed by the same method for Dvol_chg and Dsoc_chg in equation (10), Dsoc_dischg in equation (11), or Dcur and Dtemp common to equations (10) and (11). The variation of the allowable charging power of the secondary battery 110 in Dvol_chg and Dsoc_chg becomes the object of confirmation. The variation of the allowable discharging power in Dsoc_dischg becomes the object of confirmation. The variation of the allowable charging power and allowable discharging power in Dcur and Dtemp becomes the object of confirmation.

[0161] (Effect of the control device 10 for the secondary battery 110 in the first embodiment)

[0162] The effects of the control device 10 for the secondary battery 110 in the first embodiment will be explained.

[0163] (1) The control device 10 for the secondary battery 110 includes a permissible power setting unit 421 and a permissible power limiting unit 422. The permissible power setting unit 421 sets a permissible power value for the secondary battery 110 during discharge based on specified information about the secondary battery 110. The permissible power limiting unit 422 limits the power value before the power value of the secondary battery 110 reaches the permissible power value. The permissible power limiting unit 422 limits the power value in stages at two or more different ratios.

[0164] According to the control device 10 of the secondary battery 110 with such a structure, the permissible power limiting unit 422 limits the power value in stages at two or more different ratios. Therefore, the control device 10 of the secondary battery 110 can suppress the power value of the secondary battery 110 from exceeding the permissible power value even if the power value of the secondary battery 110 changes relatively largely, without excessively limiting the permissible power value of the secondary battery 110. As a result, the control device 10 of the secondary battery 110 can limit the power value of the secondary battery 110 per unit time without excessively limiting the permissible power value of the secondary battery 110.

[0165] In the first embodiment, a state in which the allowable power value of the secondary battery 110 is not excessively limited is equivalent to a state in which the threshold of the allowable power value of the secondary battery 110 has no margin. In the first embodiment, a power value of the secondary battery 110 exceeding the allowable power value is equivalent to a state in which the power value of the secondary battery 110 is less than the allowable voltage value when discharging. Furthermore, in the first embodiment, a power value of the secondary battery 110 exceeding the allowable power value is equivalent to a state in which the power value of the secondary battery 110 exceeds the allowable voltage value when charging.

[0166] In the first embodiment, the control device 10 of the secondary battery 110 limits the power value in stages using two or more different ratios during both discharging and charging. The control device 10 of the secondary battery 110 may also be configured to limit the power value in stages using two or more different ratios during either discharging or charging.

[0167] In the first embodiment, the control device 10 of the secondary battery 110 limits the power value in stages at two different ratios. The control device 10 of the secondary battery 110 may also be configured to limit the power value in stages at three or more different ratios. The control device 10 of the secondary battery 110 may also be configured to limit the power value in stages at three different ratios during discharge and in stages at two different ratios during charging.

[0168] In the first embodiment, regarding two or more different ratios, by Figure 3 The power value is defined by the gradient of the power value of the secondary battery 110 in the first limiting rate region S1 and the gradient of the power value of the secondary battery 110 in the second limiting rate region S2. The gradient of the power value of the secondary battery 110 can be linear, for example, or it can be curved.

[0169] (2) In the control device 10 of the secondary battery 110, the allowable power value is set based on one or more of the allowable voltage value and allowable current value of the secondary battery 110.

[0170] According to the control device 10 of the secondary battery 110 with such a structure, the allowable power value of the secondary battery 110 can be limited per unit time without excessively limiting the allowable power value of the secondary battery 110, based on the allowable voltage value or allowable current value of the secondary battery 110, which has relatively high versatility in the control of the secondary battery 110.

[0171] In the first embodiment, the control device 10 of the secondary battery 110 limits the power value in stages at two or more different ratios based on the allowable voltage value. The control device 10 of the secondary battery 110 may also be configured to limit the power value in stages at two or more different ratios based on the allowable current value.

[0172] (3) In the control device (10) of the secondary battery (110), the permissible power limiting unit (422) limits the power value in stages when the secondary battery (110) is discharging, so that the change in power value per unit time caused by the power value limitation implemented earlier is less than the change in power value per unit time caused by the power value limitation implemented later.

[0173] According to the control device 10 of the secondary battery 110 with such a structure, when the secondary battery 110 is discharging, it can relatively reduce the limitation on the power value of the secondary battery 110 until the power value of the secondary battery 110 is relatively close to the allowable power value. As a result, when the secondary battery 110 is discharging, the control device 10 of the secondary battery 110 can reduce the limitation on the allowable power value of the secondary battery 110 and limit the power value of the secondary battery 110 per unit time.

[0174] In the first embodiment, the control device 10 of the secondary battery 110 limits the power value in stages at two different ratios when the secondary battery 110 is discharging. That is, the first implementation relative to the first ratio is the first of the two different ratios. The second implementation relative to the second ratio is the second of the two different ratios. When the control device 10 of the secondary battery 110 is configured to limit the power value in stages at three or more different ratios, the following applies. That is, the second implementation relative to the first ratio is, for example, the second of four different ratios. On the other hand, the fourth implementation relative to the second ratio is, for example, the fourth of four different ratios.

[0175] (4) In the control device 10 of the secondary battery 110, the permissible power limiting unit 422 limits the power value before the power value of the secondary battery 110 reaches the lower limit of the permissible power value when the secondary battery 110 is discharging.

[0176] The control device 10 of the secondary battery 110 with such a structure can limit the power value of the secondary battery 110 per unit time without excessively limiting the allowable power value of the discharge side of the secondary battery 110 before the power value of the secondary battery 110 reaches the lower limit of the allowable power value.

[0177] (5) In the control device 10 of the secondary battery 110, the permissible power limiting unit 422 starts limiting the power value of the secondary battery 110 when a specified threshold related to the power value limitation is reached.

[0178] The control device 10 of the secondary battery 110 with such a structure is able to stably start limiting the power value of the secondary battery 110 based on a predetermined threshold.

[0179] (6) In the control device 10 of the secondary battery 110, the specified information includes any one or more of the voltage value, current value, internal resistance value, charging state, temperature and deterioration state of the secondary battery 110.

[0180] According to the control device 10 of the secondary battery 110 with such a structure, the allowable power setting unit 421 can set the allowable power value of the secondary battery 110 based on various information about the relatively high versatility of the secondary battery 110.

[0181] (7) In the control device 10 of the secondary battery 110, the permissible power limiting unit 422 releases the power value limitation of the secondary battery 110 after limiting the power value.

[0182] According to the control device 10 of the secondary battery 110 with such a structure, it is possible to control the secondary battery 110 to be able to use the power of the secondary battery 110 again after the power value of the secondary battery 110 deviates from the allowable power value of the secondary battery 110.

[0183] (8) In the control device 10 of the secondary battery 110, compared with the first threshold when limiting the power value of the secondary battery 110, the power limiting unit 422 relaxes the second threshold when releasing the power value limitation of the secondary battery 110.

[0184] The control device 10 for the secondary battery 110 with this structure can suppress the permissible power limiting section 422 from repeatedly limiting and releasing the power value of the secondary battery 110 at a relatively short frequency. That is, the control device 10 for the secondary battery 110 with this structure can suppress the permissible power limiting section 422 from oscillating.

[0185] (Structure of the control device 10 for the secondary battery 110 in the second embodiment)

[0186] Reference Figure 6 The structure of the control device 10 for the secondary battery 110 in the second embodiment will be described.

[0187] Figure 6 It is a graph showing the relationship between the limiting rate [%] of the allowable charging power of the secondary battery 110 in the second embodiment and the threshold value of the charging voltage [V] of the secondary battery 110.

[0188] In the control device 10 of the secondary battery 110 in the second embodiment, the allowable power setting unit 421 sets the allowable power value of the secondary battery 110 during charging based on the specified information of the secondary battery 110.

[0189] The permissible power limiting unit 422 limits the power value before the power value of the secondary battery 110 reaches the permissible power value. The permissible power limiting unit 422 limits the power value in stages at two or more different ratios.

[0190] The first limiting rate region S1 is set to the lower threshold Vth_cell side compared to the second limiting rate region S2. The first threshold Vth1 is set to a value above the lower threshold Vth_cell. The first limiting rate region S1 is defined as the voltage region from the first threshold Vth1 to the second threshold Vth2. The first threshold Vth1 is the voltage value at the start of the voltage limiting of the secondary battery 110 in the first limiting rate region S1. The second threshold Vth2 is the voltage value at the end of the voltage limiting of the secondary battery 110 in the first limiting rate region S1.

[0191] The second limiting rate region S2 is set at a position closer to the upper threshold Vth_sys than the first limiting rate region S1. The third threshold Vth3 is set to a value below the upper threshold Vth_cell. The second limiting rate region S2 is defined as the voltage region from the second threshold Vth2 to the third threshold Vth3. The second threshold Vth2 is the voltage value at the start of the voltage limiting of the secondary battery 110 in the second limiting rate region S2. The third threshold Vth3 is the voltage value at the end of the voltage limiting of the secondary battery 110 in the second limiting rate region S2.

[0192] The second threshold Vth2 also serves as the end voltage threshold of the first limiting rate region S1 and the start voltage threshold of the second limiting region. The second threshold Vth2 is a value between the first threshold Vth1 and the third threshold Vth3, and is set to be closer to the third threshold Vth3 than the first threshold Vth1. The second threshold Vth2 is set to allow the transition from the first limiting region S1 to the second limiting rate region S2 when the voltage of the secondary battery 110 rises to near the overcharge voltage.

[0193] The first limiting rate region S1 is the region where the voltage limiting rate of the secondary battery 110 is within the range of 100% to b_Vth2 (%). The second limiting rate region S2 is the region where the voltage limiting rate of the secondary battery 110 is within the range of b_Vth2 (%) to 0%. The second threshold Vth2 is the limiting rate that forms the boundary between the first limiting rate region S1 and the second limiting rate region S2. The second threshold Vth2 is set to a value where the voltage limiting rate of the secondary battery 110 exceeds 50% but is less than 100%. That is, the limiting rate range of the first limiting rate region S1 is set to be larger than the limiting rate range of the second limiting rate region S2.

[0194] Compared to the second limiting rate region S2, the first limiting rate region S1 is set to have a wider voltage range and a smaller limiting rate change per unit voltage. For example... Figure 6 As shown, the slope of the change in the limiting rate in the first limiting rate region S1 is set to be gentler than the slope of the second limiting rate region S2. The first limiting rate region S1, with a gentle slope, is set on the lower threshold Vth_cell side of battery system 1. The second limiting rate region S2, with a sharp slope, is set on the upper threshold Vth_sys side of battery system 1.

[0195] (The usual limitations of the charging voltage of the secondary battery 110)

[0196] Reference Figure 6 The conventional limitations on the charging voltage of the secondary battery 110 are explained.

[0197] Battery system 1 typically operates within a voltage range below the upper threshold Vth_sys. Battery system 1 repeatedly charges and discharges the secondary battery 110 based on the conditions of the electric vehicle equipped with battery system 1. For example, if an anomaly occurs in the secondary battery 110 or the electric vehicle, causing the voltage of the secondary battery 110 to rise sharply beyond the lower threshold Vth_cell and towards the upper threshold Vth_sys, battery system 1 limits the charging voltage of the secondary battery 110. That is, when the voltage of the secondary battery 110 exceeds a predetermined value and rises, battery system 1 limits the allowable charging power of the secondary battery 110 to prevent the voltage of the secondary battery 110 from exceeding the upper threshold Vth_sys.

[0198] (Based on the gradual limitation of the charging voltage in the first limiting rate region S1 of the secondary battery 110) Refer to Figure 6 The gradual limitation of the charging voltage in the first limiting rate region S1 based on the secondary battery 110 is explained.

[0199] When the voltage of the secondary battery 110 exceeds both the lower threshold Vth_cell and the first threshold Vth1, the voltage of the secondary battery 110 enters the first limiting rate region S1. When the first threshold Vth1 is set to be the same as or near the lower threshold Vth_cell, if the voltage of the secondary battery 110 exceeds the lower threshold Vth_cell, the probability of it exceeding the first threshold Vth1 becomes relatively higher. Even if the voltage of the secondary battery 110 exceeds the first threshold Vth1, the limiting rate of the voltage of the secondary battery 110 remains relatively flat if it is below the second threshold Vth2. That is, a first limiting rate region S1 with relatively flat charging voltage limiting is set near the lower threshold Vth_cell of the secondary battery, so the charging voltage of the secondary battery is not excessively limited. The flat limiting of the secondary battery 110 based on the first limiting rate region S1 suppresses the generation of oscillation phenomena in the charging voltage of the secondary battery 110. Furthermore, a first limiting rate region S1 with a relatively gentle limitation on the charging voltage is set near the lower limit threshold Vth_cell of the secondary battery 110, so the limitation on the charging voltage of the secondary battery 110 begins relatively early. As a result, the voltage rise of the secondary battery 110 is safely suppressed.

[0200] (Based on the sharp limitation of the charging voltage in the second limiting rate region S2 of the secondary battery 110) Refer to Figure 6 The control of the sharp limitation of the charging voltage in the second limiting rate region S2 based on the secondary battery 110 is explained.

[0201] When the voltage of the secondary battery 110 exceeds the second threshold Vth2, the voltage of the secondary battery 110 enters the second limiting rate region S2. The abrupt limitation of the charging voltage in the second limiting rate region S2 suppresses the charging voltage of the secondary battery 110 from reaching the upper limit threshold Vth_sys. That is, when the gradual limitation in the first limiting rate region S1 cannot suppress the voltage increase, the abrupt limitation in the second limiting rate region S2 suppresses the increase in the charging voltage of the secondary battery 110.

[0202] (Confirmation of the effectiveness of implementing the second embodiment)

[0203] The effectiveness of the implementation related to the second embodiment will be explained.

[0204] If the second embodiment is implemented effectively, the measured waveform of the charging voltage of the secondary battery 110 becomes a waveform containing multiple tilted regions. The waveform containing multiple tilted regions is equivalent to the waveform in the first limiting rate region S1 and the waveform in the second limiting rate region S2.

[0205] The effectiveness of the second embodiment is confirmed by measuring the charging voltage of the secondary battery 110 from the lower threshold Vth_cell to the upper threshold Vth_sys. The voltage of the secondary battery 110 is measured at certain intervals, such as 0.1V intervals. The measurement of the secondary battery 110 is performed after a sufficiently long predetermined time, such as 1 minute, following the setting of each charging voltage.

[0206] (Effect of the control device 10 for the secondary battery 110 in the second embodiment)

[0207] The effects of the control device 10 for the secondary battery 110 in the second embodiment will be explained.

[0208] (9) In the control device 10 of the secondary battery 110, the permissible power limiting unit 422 limits the power value in stages during the charging of the secondary battery 110, so that the change in power value per unit time caused by the power value limitation implemented earlier is less than the change in power value per unit time caused by the power value limitation implemented later.

[0209] According to the control device 10 of the secondary battery 110 with such a structure, during the charging of the secondary battery 110, the limitation on the power value of the secondary battery 110 can be relatively reduced until the power value of the secondary battery 110 is relatively close to the allowable power value. As a result, during the charging of the secondary battery 110, the control device 10 of the secondary battery 110 can reduce the limitation on the allowable power value of the secondary battery 110 and limit the power value of the secondary battery 110 per unit time.

[0210] In the second embodiment, the control device 10 of the secondary battery 110 limits the power value in stages at two different ratios during the charging of the secondary battery 110. That is, the first implementation relative to the second implementation refers to the first of the two different ratios. The second implementation relative to the third implementation refers to the second of the two different ratios. When the control device 10 of the secondary battery 110 is configured to limit the power value in stages at three or more different ratios, the following applies. That is, the second implementation relative to the first implementation refers to, for example, the second of four different ratios. On the other hand, the fourth implementation relative to the third implementation refers to, for example, the fourth of four different ratios.

[0211] Furthermore, according to the control device 10 of the secondary battery 110 with such a structure, constant voltage (CV) control is not required in the control of the secondary battery 110 in a deteriorated BEV.

[0212] (10) In the control device 10 of the secondary battery 110, the permissible power limiting unit 422 limits the power value before the power value of the secondary battery 110 reaches the upper limit of the permissible power value when the secondary battery 110 is being charged.

[0213] The control device 10 of the secondary battery 110 with such a structure can limit the power value of the secondary battery 110 per unit time without excessively limiting the allowable power value of the charging side of the secondary battery 110 before the power value of the secondary battery 110 reaches the upper limit of the allowable power value.

[0214] (Control device for secondary batteries in other embodiments)

[0215] The control device for the secondary battery of the present invention is not limited to the structure of the control device for the secondary battery described in the first embodiment and the second embodiment, and can be appropriately configured according to the contents described in the claims.

[0216] The first and second embodiments have been described in detail or in brief for the purpose of easily understanding the present invention, and are not required to have all the structures described, or may include structures not shown.

[0217] In other embodiments, the maximum change in the limit can be varied according to changes in the input limit rate. That is, the maximum change in the limit can be switched in stages from the first limit rate region S1 to the second limit rate region S2. The maximum change in the second limit rate region S2 is set to be greater than the maximum change in the first limit rate region S1. That is, the maximum change in the first limit rate region S1 is configured without change from the voltage range used by the conventional system (above the upper limit threshold Vth_sys). This is because, in the first limit rate region S1, since it is a voltage region close to the system's operating range, there is a margin up to the over-discharge voltage requiring battery protection. On the other hand, the second limit rate region S2 is a region where the allowable discharge power is drastically limited near the over-discharge voltage, and battery use is to be prohibited. Therefore, increasing the maximum change improves the responsiveness to limiting the allowable power. In other embodiments, the maximum change in the system's operating voltage range and the maximum change in the first limit rate region S1 use the same value, but are not limited to this; any value smaller than the maximum change in the second limit rate region S2 is acceptable. Furthermore, the maximum change in the second limiting rate region S2 can also be set to a large value that is substantially ineffective as a change limit. A method for limiting the change in voltage based on the first limiting rate region S1 and the second limiting rate region S2 in the over-discharge voltage of the discharge change limiting unit 422A2 has been explained. This is because, in the event of a rapid change or increase in allowable power, the prevention of abnormal voltage is a significant issue regarding battery safety, so controlling the maximum change in voltage-based change limit is considered. Additionally, although the explanation is omitted, the same structure as the voltage-based overcharge voltage is used in the charging change limiting unit 422A1. Therefore, even at the allowable charging power, improved safety in the charging direction can be anticipated in the event of a rapid voltage increase. Other embodiments have described a method for limiting the maximum change in the voltage-based change limiting unit, but the input object for which the maximum value of the change limit can be varied is not limited to voltage. That is, battery state values ​​such as SOC, current, and temperature can also be used. In this case, safety is also improved when the input increases or decreases rapidly.

[0218] Explanation of reference numerals in the attached figures

[0219] 1 Battery System

[0220] 10. Control device

[0221] 100 battery packs

[0222] 100A First Battery Pack

[0223] 100B Second Battery Pack

[0224] 110 Secondary Battery

[0225] 200 Battery Control Unit

[0226] 210 First Battery Control Unit

[0227] 220 Second Battery Control Unit

[0228] 300 Measurement Department

[0229] 310 Current Measurement Section

[0230] 320 Voltage Measurement Section

[0231] 330 Temperature Measurement Section

[0232] 400 Battery State Estimation and Control Unit

[0233] 410 SOC / SOHR Computing Department

[0234] 420 Battery Status Calculation Unit

[0235] 421 Permissible power setting unit (control device 10)

[0236] 422 Permissible power limiting unit (control device 10)

[0237] 422A Variation Limitation Section

[0238] 422A1 Charging Variation Limiting Section

[0239] 422A2 Discharge Variation Limiting Section

[0240] 422B Permissible Power Limiting Section

[0241] 422B1 Charging Permissible Power Limiting Section

[0242] 422B2 Discharge Capacitor Power Limiting Section

[0243] 431 Charging Multiplication Section

[0244] 432 Discharge Multiplication Section

[0245] 500 Ministry of Communications

[0246] 600 Storage Unit

[0247] 1100 Relay

[0248] 1200 inverter

[0249] 1300 Electric Generator

[0250] 1400 Motor / Inverter Control Unit

[0251] 1500 Vehicle Control Department.

Claims

1. A control device for a secondary battery, characterized in that, include: The permissible power setting unit, based on specified information about the secondary battery, sets a permissible power value for the secondary battery during at least one of discharging and charging; and The permissible power limiting unit limits the power value before the power value of the secondary battery reaches the permissible power value. The permissible power limiting unit limits the power value in stages using two or more different ratios.

2. The control device for a secondary battery as described in claim 1, characterized in that: The allowable power value is set based on one or more of the allowable voltage and allowable current values ​​of the secondary battery.

3. The control device for a secondary battery as described in claim 1, characterized in that: The permissible power limiting unit limits the power value in stages during the discharge of the secondary battery, such that the change in the power value per unit time caused by the power value limitation implemented earlier is less than the change in the power value per unit time caused by the power value limitation implemented later.

4. The control device for a secondary battery as described in claim 1, characterized in that: The permissible power limiting unit limits the power value in stages during the charging of the secondary battery, such that the change in the power value per unit time caused by the power value limitation implemented earlier is less than the change in the power value per unit time caused by the power value limitation implemented later.

5. The control device for a secondary battery as described in claim 1, characterized in that: The permissible power limiting unit limits the power value of the secondary battery before the power value of the secondary battery reaches the lower limit of the permissible power value during the discharge of the secondary battery.

6. The control device for a secondary battery as described in claim 1, characterized in that: The permissible power limiting unit limits the power value of the secondary battery before the power value of the secondary battery reaches the upper limit of the permissible power value during charging.

7. The control device for a secondary battery as described in claim 1, characterized in that: The permissible power limiting unit begins limiting the power value when a predetermined threshold for limiting the power value is reached.

8. The control device for a secondary battery as described in claim 1, characterized in that: The specified information includes one or more of the following: voltage value, current value, internal resistance value, charging state, temperature, and degradation state of the secondary battery.

9. The control device for a secondary battery as described in claim 1, characterized in that: After limiting the power value, the allowable power limiting unit releases the power value limitation.

10. The control device for a secondary battery as described in claim 9, characterized in that: The permissible power limiting unit makes the second threshold for releasing the power value limit more lenient than the first threshold for limiting the power value.

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