JP5465119B2 - Battery remaining capacity calculation device - Google Patents

Description

  The present invention relates to a battery remaining capacity calculation device, and more particularly to a battery remaining capacity calculation device that can more accurately calculate the remaining capacity of a secondary battery.

  Conventionally, it is known to consider various parameters in order to improve the calculation accuracy of the remaining capacity (charge capacity) of the secondary battery.

  In Patent Document 1, the amount of self-discharge of the secondary battery is estimated and detected based on the temperature of the secondary battery detected by the temperature sensor, and the amount of self-discharge is subtracted from the charge capacity at the time of full charge. A battery remaining capacity calculation device is disclosed that increases the capacity calculation accuracy.

JP 2004-191151 A

  By the way, since a secondary battery (hereinafter also referred to as a battery) mounted as a power source for an electric motorcycle or the like requires a high voltage, it generally has a module structure in which a plurality of cells are combined. It is. In a battery having such a module structure, there is a possibility that the temperature of each cell varies depending on the position in the battery. For example, if an attempt is made to detect and detect the self-discharge amount of each cell individually, the same number of temperature sensors as the number of cells are required, resulting in difficulty in sensor arrangement and an increase in cost. Furthermore, the technique described in Patent Document 1 is to detect one of the self-discharge amounts by measuring either the internal temperature, the surface temperature, or the atmospheric temperature of one secondary battery. The difference in self-discharge amount, in other words, “capacity shift” of each cell was not considered.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art and to consider a difference in self-discharge amount based on a temperature difference between cells in a battery, and to calculate a remaining battery capacity with higher accuracy. Is to provide.

  In order to achieve the object, the present invention provides a temperature sensor (91U, 91L) for detecting a temperature at a predetermined position of a battery (36) formed by combining a plurality of cells (2a), and a battery (36). In the battery remaining capacity calculation device, including a control unit (200) that calculates a remaining capacity (R) of the battery (36) by subtracting a plurality of subtraction elements from the full charge capacity (A), the temperature sensor (91U , 91L) is disposed at a position where a high temperature is expected in the battery (36) and at a position where a low temperature is expected in the battery (36). A low temperature side temperature sensor (91L), and the control unit (200) determines the low temperature side temperature sensor (SHmax) from the maximum self-discharge amount (SHmax) derived based on the output of the high temperature side temperature sensor (91U). 1L), a value obtained by subtracting the minimum self-discharge amount (SHmin) derived based on the output of 1L) is calculated as the capacity deviation amount (Ft) of the battery (36), and the capacity deviation amount (Ft) is calculated as the remaining capacity. A first feature is that the subtraction element to be subtracted from the full charge capacity (A) is included in the calculation of (R).

  Also, the capacity deviation amount (Ft) is set to the current value, and the integrated value of the current value (Ft) of the capacity deviation amount and the previous value (F0) of the capacity deviation amount calculated at the time of the previous remaining capacity calculation. The second feature is that the capacity deviation subtraction amount (F) is used as a subtraction element for subtracting from the full charge capacity (A) when calculating the remaining capacity (R).

  Further, based on the output values of the low temperature side temperature sensor (91L) and the high temperature side temperature sensor (91U) and the value of the charge rate (SOC) of the battery (36), the maximum self-discharge amount (SHmax) and the minimum A third feature is that a self-discharge amount map (206m) for deriving the self-discharge amount (SHmin) is provided.

  In addition, the battery (36) is formed in a substantially rectangular parallelepiped with its ceiling surface and bottom surface oriented substantially horizontally when mounted on the vehicle (1), and the high temperature side sensor (91U) is provided with the battery (36). There is a fourth feature in that the low temperature side sensor (91L) is attached to the bottom surface side of the battery (36).

  Further, the low temperature side temperature sensor (91L) and the high temperature side temperature sensor (91U) are respectively attached to the approximate center of the battery (36) in the longitudinal direction of the vehicle body and the approximate center of the vehicle width direction. There is a fifth feature.

  Further, the control unit (200) determines the low temperature charge shortage amount (B) and the low temperature discharge shortage amount (C) based on the difference between the charging characteristics at the basic temperature and the low temperature charging characteristics of the battery (36). And the integrated value (D) of the discharge amount of the battery (36) is calculated based on the measured value of the charge / discharge current measuring unit (90), and the maximum self-discharge amount (SHmax) is set to the current value. Then, an integrated value (E) of the current value (SHmax) of the maximum self-discharge amount and the previous value (SHmax0) of the maximum self-discharge amount calculated at the time of the previous remaining capacity calculation is calculated, and the calculated capacity deviation is calculated. The amount (Ft) is set to the current value, and the capacity deviation subtraction, which is an integrated value of the current value (Ft) of the capacity deviation amount and the previous value (F0) of the capacity deviation amount calculated at the time of the previous remaining capacity calculation. The amount (F) is calculated, and from the full charge capacity (A), The low temperature charge shortage amount (B), the low temperature discharge shortage amount (C), the discharge amount integrated value (D), the maximum self discharge amount integrated value (E), and the capacity deviation subtraction amount ( There is a sixth feature in that the remaining capacity (R) is calculated by subtracting F).

  Further, the battery (36) is housed in a box-shaped battery case (37), and the battery case (37) is supplied with cooling air introduced from an opening (93) provided on a wall surface on one side. Is led out from an opening (94) provided on the other side wall surface, and the high temperature side temperature sensor (91U) is arranged downstream of the cooling air from the low temperature side temperature sensor (91L). There is a seventh feature in that it is characterized.

  According to the first feature, the temperature sensor includes a high temperature side temperature sensor disposed at a position where high temperature is expected in the battery, and a low temperature side temperature sensor disposed at a position where low temperature is expected within the battery. The controller is configured to subtract the value obtained by subtracting the minimum self-discharge amount derived based on the output of the low temperature side temperature sensor from the maximum self discharge amount derived based on the output of the high temperature side temperature sensor. Since the amount of capacity deviation is included in the subtraction element that is subtracted from the full charge capacity when calculating the remaining capacity, the capacity deviation amount of the battery module is estimated and detected based on the outputs of the two temperature sensors. By using the amount, it is possible to improve the detection accuracy of the remaining capacity. Further, since it is not necessary to provide a temperature sensor for each of the plurality of cells, it is possible to reduce the number of parts and the cost of the battery unit.

  According to the second feature, the capacity deviation amount is set to the current value, and the capacity deviation which is an integrated value of the current value of the capacity deviation amount and the previous value of the capacity deviation amount calculated at the time of the previous remaining capacity calculation. Since the subtraction amount is used as a subtraction element that subtracts from the full charge capacity when calculating the remaining capacity, the accuracy of calculating the remaining battery capacity can be improved by using the capacity deviation amount as an integrated value.

  According to the third feature, the self-discharge amount map for deriving the maximum self-discharge amount and the minimum self-discharge amount based on the output values of the low temperature side temperature sensor and the high temperature side temperature sensor and the value of the charge rate of the battery. Thus, it is possible to easily derive the capacity deviation amount of the battery module by using a map set in advance by experiments or the like.

  According to the fourth feature, the battery is formed in a substantially rectangular parallelepiped with its ceiling surface and bottom surface oriented substantially horizontally when mounted on the vehicle, the high temperature side sensor is attached to the ceiling surface side of the battery, and the low temperature side Since the sensor is attached to the bottom surface side of the battery, it is possible to easily detect the battery temperature on the high temperature side and the battery temperature on the low temperature side.

  According to the fifth feature, each of the low temperature side temperature sensor and the high temperature side temperature sensor is attached at the approximate center of the battery in the longitudinal direction of the vehicle body and at the approximate center of the vehicle width direction. Becomes easy.

  According to the sixth feature, the control unit calculates the low-temperature charge shortage and the low-temperature discharge shortage based on the difference between the charge characteristic at the basic temperature of the battery and the charge characteristic at the low temperature, and measures the charge / discharge current. The integrated value of the battery discharge amount is calculated based on the measured value of the unit, the maximum self-discharge amount is set to the current value, and the current value of the maximum self-discharge amount and the maximum self-discharge calculated at the previous calculation of the remaining capacity are calculated. Calculate the integrated value of the discharge amount with the previous value, set the calculated capacity deviation amount to the current value, and set the current value of this capacity deviation amount and the previous value of the capacity deviation amount calculated when calculating the previous remaining capacity. The amount of subtraction of the capacity deviation, which is the integrated value of, is calculated, and from the full charge capacity, the low temperature charge shortage amount, the low temperature discharge shortage amount, the discharge amount integration value, the maximum self-discharge amount integration value, and the capacity deviation subtraction are calculated. The remaining capacity is calculated by subtracting the amount, so 5 reductions By defining an element, further, it is possible to improve the calculation accuracy of the remaining capacity of the battery.

  According to the seventh feature, the battery is housed in a box-shaped battery case, and the battery case is provided with cooling air introduced from an opening provided on a wall surface on one side on the wall surface on the other side. Since the high temperature side temperature sensor is arranged downstream of the cooling air from the low temperature side temperature sensor, the high temperature side temperature sensor is provided downstream of the cooling air. As a result, the accuracy of temperature detection can be further improved.

It is a side view of the electric vehicle carrying the battery remaining capacity calculation apparatus which concerns on one Embodiment of this invention. It is a perspective view of an electric vehicle. FIG. 3 is a perspective view of main parts of the electric vehicle shown in FIG. 2. It is an electrical system diagram of an electric vehicle. It is a perspective view of a main battery. It is a disassembled perspective view of a main battery. It is side surface sectional drawing of a main battery. It is a block diagram which shows the structure of a battery remaining capacity calculation apparatus. It is a self-discharge amount map. It is the figure which showed the calculation method of battery remaining capacity. It is a flowchart which shows the procedure of the battery remaining capacity calculation process in a vehicle stop. It is a flowchart which shows the procedure of the battery remaining capacity calculation process during vehicle travel or charging.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a left side view of an electric vehicle equipped with a battery remaining capacity calculation device according to an embodiment of the present invention, and FIG. 2 is a left front perspective view thereof. The electric vehicle 1 is a scooter type two-wheeled vehicle having a low floor, and each component is attached to the body frame F directly or indirectly through other members.

  1 and 2, the vehicle body frame F is connected to a head pipe 26 which is a front portion, a down frame 27 whose front end is joined to the head pipe 26 and whose rear end extends downward, and a lower portion of the down frame 27. The pair of underframes 28 are branched to the left and right in the vehicle body width direction and extend toward the rear of the vehicle body, and a rear frame 29 extends from the underframe 28 to the rear of the vehicle body. The head pipe 26 rotatably supports the steering shaft 20. A steering handle 25 is connected to the upper part of the steering shaft 20, and a front fork 24 that supports the front wheel WF is connected to the lower part.

  A front stay 50 made of a pipe is coupled to the front portion of the head pipe 26, a headlight 51 is attached to the front end portion of the front stay 50, and a front carrier supported by a bracket 57 above the headlight 51. 19 is provided.

  A pivot plate 30 extending toward the rear of the vehicle body is joined to an intermediate region between the under frame 28 and the rear frame 29 of the vehicle body frame F. The pivot plate 30 extends in the vehicle body width direction. A pivot shaft 32 is provided, and the swing arm 22 is supported by the pivot shaft 32 so as to be swingable up and down. The swing arm 22 is provided with an electric motor 23 as a vehicle drive source. The output of the motor 23 is transmitted to the rear wheel axle 21, and the rear wheel WR supported by the rear wheel axle 21 is driven. The housing including the rear wheel axle 21 and the rear frame 29 are connected by a rear suspension 33. A side stand 31 that supports the vehicle body while the vehicle is stopped is rotatably attached to a lower extension portion of the pivot plate 30, and a main stand 34 is attached to the lower surface of the swing arm 22.

  A high voltage (for example, 72 volt rated) main battery 36 in which a plurality of battery cells are built in a battery case 37 is mounted on the underframe 28. A duct 64 for introducing air as battery cooling air into the battery case 37 is connected to the front portion of the main battery 36 via a connection pipe 65, and an air cleaner 68 is connected above the duct 64 via a connection pipe 66. Is provided. The air cleaner 68 is provided at substantially the same height as the head pipe 26. The duct 64 and the connecting pipes 65 and 66 are collectively referred to as a front connecting pipe 110 (see FIG. 7).

  A duct (hereinafter referred to as “rear connecting pipe”) 69 is connected to the rear part of the battery case 37, and the rear part of the rear connecting pipe 69 is connected to a cooling fan 70 that is a blowing means. The cooling fan 70 is disposed along the rear frame 29 extending obliquely upward and rearward from the under frame 28. The cooling fan 70 is preferably a sirocco fan, and is configured to be able to reverse the rotation direction so that the flow direction of the air blown into the battery case 37 through the front connection pipe 110 and the rear connection pipe 69 can be reversed. Is done.

  Provided on the rear frame 29 is a power receiving side connector 78 to which a power feeding side connector (described later) connected to a charging cable extending from an external charger for charging the main battery 36 can be coupled. The rear frame 29 is further provided with a rear carrier 59 and a taillight 52.

  A luggage compartment 38 is provided between the pair of left and right rear frames 29. A cargo compartment bottom 38a projecting downward from the luggage compartment 38 has a low voltage (for example, rated at 12 volts) charged by the main battery 36. The sub-battery 40 is accommodated. A driver seat 39 that also serves as a lid for the luggage compartment 38 is provided on the luggage compartment 38.

  The vehicle body frame F is covered with a vehicle body cover made of synthetic resin. The vehicle body cover includes a handle cover 56, a front cover 42, a leg shield 43, a low floor floor 44, a floor side cover 45, an under cover 46, a seat lower front cover 47, a side cover 48, and a rear cover 49.

  The front cover 42 covers the head pipe 26, the front stay 50, and the like from the front. The leg shield 43 is connected to the front cover 42 and is disposed so as to be positioned in front of the leg portion of the driver sitting on the driver seat 39. Among the head pipe 26 and the front connection pipe 110, the duct 64 and the connection pipe 66 are provided. Is covered from the driver seat 39 side. The low floor floor 44 is continuous with the lower part of the leg shield 43, and the floor side cover 45 is continuous with the low floor floor 44. The low floor 44 covers the battery case 37 from above, and the floor side cover 45 covers the underframe 28 and the battery case 37 from the left and right sides of the vehicle body.

  The under cover 46 is passed between the lower edges of the left and right floor side covers 45. The lower seat front cover 47 rises from the rear end of the low floor floor 44 so as to cover the luggage compartment 38 from the front. A pair of left and right side covers 48 are connected to both sides of the lower seat front cover 47 so as to cover the cargo compartment 38 from the left and right. The rear cover 49 covers the rear wheel WR from above and continues to the side cover 48.

  FIG. 3 is a main part perspective view showing a main part of the electric vehicle 1. In FIG. 3, the lower seat front cover 47 shown in FIG. 2 is removed. A cooling fan 70 and a luggage compartment 38 can be seen inside the electric vehicle 1 from which the under-seat front cover 47 is removed. The luggage compartment 38 is supported by stays 35 a and 35 b joined to a subframe 35 spanned between the rear frames 29 and 29. The cooling fan 70 is biased to the right side of the vehicle body, and the fan exhaust port 41 faces the left side of the vehicle body. The cooling fan 70 is fixed to a case 71 a of a power drive unit (PDU) for driving the motor 23 with three bolts 53.

  FIG. 4 is an electric system diagram of the electric vehicle. The PDU 71 includes a control unit (ECU). The PDU 71 is connected to the positive terminal of the main battery 36 via the fuse 72 and the first relay switch 73. A series circuit including a second relay switch 74 and a resistor 76 is connected to the first relay switch 73 in parallel. The main battery 36 and the sub battery 40 can be charged with electric power supplied from the external power source PS by the charger 75. The charger 75 includes a power supply side connector 77 and can be connected to a power reception side connector 78 provided in the vehicle. The power receiving side connector 78 is connected to the DC-DC converter 79.

  The DC-DC converter 79 converts the voltage from the field effect transistor (FET) 80 inserted into one L1 of the pair of lines L1 and L2 connected to the power receiving side connector 78 and the charger 76 to a low voltage (for example, 12). Voltage drop circuit 81 connected to the lines L1 and L2. Lines L1 and L2 are used to charge the main battery 36 with a high-voltage charging current, so that a series circuit including a second relay switch 74 (precharge contactor) and a resistor 76 and a first relay switch 73 (main contactor) It is connected to the main battery 36 through a parallel circuit. The output side of the voltage drop circuit 81 is connected to the sub battery 40.

  The sub battery 40 is connected to the ECU built in the PDU 71 via the main switch 82, and control power is supplied from the sub battery 40. The sub battery 40 is also connected to a battery management unit (BMU) 83 via the main switch 82, and the BMU 83 has a function of instructing on / off of the first relay switch 73 and the second relay switch 74.

  In operation, when the main switch 82 is turned on, the BMU 83 turns on the second relay switch 74 to pass a current from the main battery 36 to the PDU 71 via the second relay switch 74, the resistor 76 and the fuse 72. The relay switch 73 is turned on. As described above, the first relay switch 73 is turned on after the second relay switch 74 is turned on in order to prevent the inrush current to the capacitor provided in the PDU 71 from flowing to the first relay switch 73. It is.

  The first relay switch 73, the second relay switch 74, and the BMU 83 can be housed in the battery case 37 together with the main battery 36.

  FIG. 5 is a perspective view showing the configuration of the main battery from the left front side of the vehicle body, and FIG. 6 is an exploded perspective view of modules constituting the main battery. 5 and 6, the symbol FR indicates the vehicle body front direction, and the symbol L indicates the vehicle body left direction. The main battery 36 includes three battery modules 2 arranged side by side in the longitudinal direction of the vehicle body. However, FIG. 6 shows one of the three modules. Each of the battery modules 2 is arranged in two upper and lower stages and is arranged with a plurality of (here, 15 sets) battery cells 2a arranged with a predetermined gap in the vehicle body width direction. The front wall 4 and the rear wall 5 are arranged in the longitudinal direction of the vehicle body, and the cover 6 is arranged in front of the front wall 4. The front wall 4 and the rear wall 5 are provided with ribs 4a and 5a, respectively, at the center in the height direction and extending in the vehicle width direction.

  On the upper surface of the cell unit 3, an upper wall 7 having reinforcing ribs 7 a arranged in the vehicle body width direction at predetermined intervals and extending in the vehicle body front-rear direction is provided. Slots 7b that are long in the longitudinal direction of the vehicle body are formed between the reinforcing ribs 7a of the upper wall 7. A lower wall (only the reinforcing rib 7 a is shown) having the same shape as the upper wall 7 is provided on the lower surface of the cell unit 3. Furthermore, the cell unit 3 has side walls 8 arranged on both sides in the vehicle body width direction.

  Each battery cell (hereinafter also simply referred to as a cell) 2a includes an electrode D arranged toward the front of the vehicle body, and an internal pressure release valve 9 is provided between the two electrodes D of each battery cell. An electrolyte guide path 10 extending horizontally in the vehicle body width direction over two upper and lower stages is provided at a position of the front wall 4 facing the internal pressure release valve 9, and the electrolyte guide path 10 is an electrolyte drain extending in the vertical direction. 11 is connected in communication. The electrolytic solution drain 11 is concentrated on one side (left side in this example) in the vehicle body width direction to facilitate maintenance.

  Convex portions 6a and 6a are formed at the lower portions of both ends in the vehicle width direction of the cover 6, respectively. The space region 12 between the convex portions 6 a and 6 a at both ends is a portion that does not come into contact with the bottom of the battery case 37 when the main battery 36 is accommodated in the battery case 37. Therefore, in the state accommodated in the battery case 37, the space region 12 forms a gap penetrating in the front-rear direction of the vehicle body between the lower surface of the main battery 36 and the battery case 37.

  A gap 13 is formed between the adjacent battery modules 2, and this gap 13 is vertically divided into two by the ribs 4 a and 5 a. Therefore, air circulation between the respective portions of the gap 13 divided into the upper and lower portions by the ribs 4a and 5a is prevented. Therefore, between the lower part and the upper part of the main battery 36, air flows through the slot 7b without flowing through the gap 13.

  Among the side walls 8 of each battery module 2, an anode connection terminal 14, a cathode connection terminal 15, an anode cable 16, a cathode cable 17, a voltage / temperature monitoring board 18, and a communication connector 67 are provided on the left side wall 8. The anode cable 16 and the cathode cable 17 are held by cable guides 84 and 85 fixed to the side wall 8.

  The battery is configured such that three modules connected in parallel are taken as one set, and each set is connected in series to obtain a predetermined battery voltage (for example, 72 volts). A battery cell connection line is schematically shown by an arrow 86. One end of the connection line 86 is connected to the anode connection terminal 14, and the other end is connected to the cathode connection terminal 15.

  As shown in FIG. 5, the end of the anode cable 16 is connected to the anode connection terminal 14 on the front side of the vehicle body among the three battery modules 2, and the tip of the cathode cable 17 is connected to the end of the three battery modules 2. The cathode connection terminal 15 on the rear side of the vehicle body is connected. The cathode connection terminal 15 of the battery module 2 on the front side of the vehicle body is connected to the anode connection terminal 14 of the adjacent central battery module 2, and the cathode connection terminal 15 of the center battery module 2 is connected to the battery module 2 on the rear side of the vehicle body. Connected to the anode connection terminal 14. That is, each battery module 2 is connected in series.

  The voltage / temperature monitoring boards 18 of the three battery modules 2 are connected to each other by a harness 87 that is curved and wired. An equalization unit 88 that performs charge / discharge management is provided on the right side of the vehicle body of the upper wall 7 of the battery module 2 on the rear side of the vehicle body, and a harness 89 extending from the equalization unit 88 is connected to the voltage / temperature monitoring board 18. . The equalization unit 88 is provided with a charge / discharge current measurement unit 90 in which a shunt substrate for setting a current measurement reference and a fuse are integrated.

  The resin-molded voltage / temperature monitoring board 18 monitors the voltage and temperature for each battery module. Specific temperature detection is performed by an upper (high temperature side) temperature sensor 91U and a lower (low temperature side) temperature sensor 91L, which are arranged above and below each battery module 2, respectively. Both temperature sensors 91U and 91L are preferably installed apart from the slot 7b in the center in the vehicle width direction of the upper wall 7 and the lower wall (not shown) so as not to be directly affected by the air flow. . Both temperature sensors 91U and 91L are provided in each battery module 2, and represent the temperature of the upper region and the lower region of the battery module 2. And the temperature of the upper part of the main battery 36 and a lower part can be represented by the average of the detected value by three temperature sensors 91U and 91L provided in each of an upper area | region and a lower area | region.

  The high temperature side temperature sensor 91U is disposed at a position where the highest temperature is expected in the battery, and the one low temperature side temperature sensor 91L is at a position where the lowest temperature is expected in the battery. It is preferable to be disposed.

  In addition, arrangement | positioning of the temperature sensors 91U and 91L is not restricted to this, What is necessary is just to be able to measure each temperature in the upper area | region and lower area | region in the battery case 37 separately. Therefore, the temperature sensors 91U and 91L are not limited to the method provided in each of the three battery modules 2, but for example, one in each of the upper region and the lower region, at the center in the vehicle longitudinal direction and the center in the vehicle width direction. It can be arranged.

  FIG. 7 is a side sectional view showing the main battery 36 accommodated in the battery case 37. In FIG. 7, the battery case 37 includes a case front plate 37f, a case rear plate 37r, a case upper plate 37u, a case bottom plate 37b, and a case side plate 37s, and forms a space for housing the battery module 2. The battery module 2 on the front side of the vehicle body shows the outer shape of the battery cell 92 with a dotted line. In the remaining two battery modules 2, the battery cells 92 are similarly arranged in two upper and lower stages.

  A connection pipe 65 is connected to a wall (case front plate) 37f on the front side of the vehicle body of the battery case 37 so that air can flow between the connection pipe 65 and the battery case 37 (intake port). 93 is formed. On the other hand, an opening (exhaust port) 94 for allowing air to flow between the rear connecting pipe 69 and the inside of the battery case 37 is formed in the rear wall (case rear plate) 37r of the battery case 37. .

  On the inner surface of the case front plate 37f, a rib 37a extending in the vehicle width direction is provided above the intake port 93, and a gap formed between the case front plate 37f and the cover 6 of the vehicle body front side battery module 2 is provided. The rib 37a is divided into two parts up and down. On the other hand, the case rear plate 37r is similarly provided with a rib 37c extending in the vehicle width direction below the exhaust port 94, and between the case rear plate 37r and the rear wall 5 of the vehicle body rear side battery module 2. A gap that can be formed is divided into two vertically by this rib 37c.

  The passage of the cooling air generated by the rotation of the cooling fan 70 includes an air cleaner 68, a front connection pipe 110, a battery case 37, and a rear connection pipe 69.

  The cooling fan 70 starts and stops driving according to a temperature condition to be described later and a traveling state (for example, traveling speed) of the electric vehicle 1. When the cooling fan 70 rotates, air is sucked from the air cleaner 68, and the air is introduced into the battery case 37 from the air inlet 93 through the front connecting pipe 110. Since the air introduced into the battery case 37 is prevented from flowing upward by the rib 37a, it is guided downward along the arrow A1 and passes through the region (gap) 12 formed by the convex portion 6a. Turn to the lower part 12a of the module 2. As indicated by arrows A <b> 2 to A <b> 4, the battery cell 92 passes between the slots 7 b and reaches the upper space 37 d of the battery case 37. Since the air flowing into the upper space 37d is prevented from flowing downward by the rib 37c, it flows into the rear connecting pipe 69 from the exhaust port 94 and is exhausted by the cooling fan 70.

  Here, in the secondary battery, the degree of self-discharge in which the amount of stored electricity gradually decreases with the passage of time is large, and furthermore, in the case of a module structure composed of a plurality of cells, The difference in self-discharge amount becomes a problem. Specifically, if there is a difference in the remaining capacity of each cell due to the difference in the self-discharge amount of each cell, if the discharge is performed in accordance with a cell having a small self-discharge amount, the self-discharge amount is large. The cell may be overdischarged. In order to prevent this, it is necessary to execute discharge control in accordance with a cell having a large self-discharge amount. In order to execute such discharge control, the difference in self-discharge amount of each cell is taken into consideration. It is preferable to calculate the remaining capacity of the entire module. The present embodiment is characterized in that the difference in self-discharge amount can be estimated and detected based on the output values of the upper (high temperature side) temperature sensor 91U and the lower (low temperature side) temperature sensor 91L.

  FIG. 8 is a block diagram illustrating a configuration of the remaining battery capacity calculation apparatus according to the present embodiment. The remaining battery capacity calculation means 201 included in the control unit 200 of the remaining battery capacity calculation device includes a fully charged state detection means 202, a discharge amount detection means 203, a low temperature charge shortage detection means 204, a low temperature discharge shortage detection means 205, a capacity. Based on each information input from the deviation amount calculation means 206, the remaining capacity (charge capacity) of the main battery 36 is detected.

  The fully charged state detecting means 202 detects the fully charged state based on the detection value of the battery voltage sensor 202a that detects the voltage of the main battery 36 reaching a predetermined voltage (for example, 72V). Further, the discharge amount detection means 203 detects the discharge amount by calculating the integrated current value from the fully charged state based on the detection value of the charge / discharge current measuring unit 90.

  The output of the low temperature side lower temperature sensor 91L is input to the low temperature charge shortage detection means 204 and the low temperature discharge shortage detection means 205, respectively. Further, the output of the upper temperature sensor 91U and the lower temperature sensor 91L is input to the displacement amount calculation means 206, respectively.

  Here, a secondary battery such as a lithium ion battery reaches a predetermined voltage (for example, 2.8 V per cell) and has a charging capacity of 100% when the battery temperature is a standard temperature (for example, 25 ° C.). Even when the temperature of the battery is lower than the standard temperature, the charging capacity does not reach 100% even when the predetermined voltage is reached, that is, insufficient charging occurs (for example, only 80% is charged). ). The low-temperature charge shortage detection means 204 can derive the charge shortage at a low temperature using a charge characteristic map m determined in advance by experiments or the like.

  Further, even if the secondary battery has a standard temperature (for example, 25 ° C.) and the charge capacity can be discharged by 100%, the discharge amount does not reach 100% if the battery temperature is lower than the standard temperature. That is, it has the property that insufficient discharge occurs (for example, only 80% can be discharged). The low temperature discharge shortage detection means 205 can derive the shortage of discharge at a low temperature by using a charging characteristic map m determined in advance by experiments or the like.

  Further, the capacity deviation amount calculation means 206 includes a self-discharge amount calculation means 207 and a self-discharge amount map 206m. In the self-discharge amount map 206m determined in advance by experiments or the like, the relationship between the battery temperature and the battery charge rate and the self-discharge amount is defined.

  It is known that the secondary battery has a remaining capacity reduced due to self-discharge even when it is not used, and the amount of self-discharge depends on the temperature of the battery and the state of charge (SOC). It has been. The self-discharge amount calculating means 207 is based on the self-discharge amount map 206m, and the maximum self-discharge amount SHmax of the high temperature side cell based on the output of the upper temperature sensor 91H and the minimum self discharge of the low temperature side cell based on the output of the lower temperature sensor 91U. The quantity SHmin is derived respectively. The amount of self-discharge is greater at high temperatures than at low temperatures, and subtracting the minimum self-discharge amount SHmin of the low-temperature side cell from the maximum self-discharge amount SHmax of the high-temperature side cell results in the amount of capacity deviation caused by the cell temperature difference. The current value (current value) is obtained.

  For example, when the cells A and B having the same charge capacity are connected, there is an individual difference in the self-discharge amount, so that the charge capacity (remaining capacity) of the cell A and the cell B over time. ). When the battery module in which the capacity deviation has occurred is discharged, the overdischarge prevention circuit of the main battery 36 operates in accordance with the cells having a large self-discharge amount, and the cells having a small self-discharge amount are not sufficiently discharged. Discharging is stopped. On the other hand, when a battery with a capacity deviation is charged, a cell with a larger self-discharge amount reaches a predetermined voltage first and the overcharge prevention circuit is activated, and the other cell is not sufficiently charged. This causes a problem that charging is stopped.

  Therefore, the equalization processing unit 208 executes equalization processing on each cell of the main battery 36 at a predetermined cycle in order to repair the capacity deviation caused by the difference in self-discharge amount. Each cell of the main battery 36 incorporates an equalization processing circuit that enables this processing.

  The equalization processing circuit built into each cell, for example, bypasses low voltage cells at the end of discharge to prohibit discharge, or bypasses high voltage cells at the end of charge to charge only low voltage cells. Thus, the displacement is substantially corrected. In addition, since a certain amount of time is required for the equalization processing, for example, the equalization processing is executed at a cycle of once every 100 times of charging. The battery remaining capacity calculation device according to the present invention is intended to improve the calculation accuracy of the remaining battery capacity by estimating and detecting the capacity deviation amount until the next equalization process is executed. is there.

  FIG. 9 shows an outline of the self-discharge amount map 206m included in the capacity deviation amount calculation means 206. As described above, the self-discharge amount depends on the battery temperature and the battery charge rate. In this figure, only the graphs when the SOC is 100%, 75%, and 50% are shown, but a finer graph, for example, every 1% may be set. In the example of this figure, in the curve corresponding to SOC 75%, the self-discharge amount corresponding to the output value (Tmax) of the high temperature side temperature sensor 91U is derived as the maximum self discharge amount SHmax, and the output of the low temperature side temperature sensor 91L The self-discharge amount corresponding to the value (Tmin) is derived as the minimum self-discharge amount SHmin. A value obtained by subtracting the minimum self-discharge amount SHmin from the maximum self-discharge amount SHmax is applied as the current value Ft of the capacity shift amount.

  FIG. 10 is a schematic diagram of a method for calculating the remaining battery capacity by the remaining battery capacity calculating means 201 (see FIG. 8). As shown in the figure, A: full charge capacity, B: low temperature charge shortage amount, C: low temperature discharge shortage amount, D: discharge amount integrated value, E: self discharge amount integrated value, F: capacity deviation subtraction amount At this time, the remaining battery capacity R can be expressed by the equation A- (B + C + D + E + F). That is, when calculating the remaining capacity R, each value of BF becomes a subtraction element for A of the full charge capacity.

  The upper graph (a) is a “charging characteristic map” showing the difference between the charging characteristic at the basic temperature (25 ° C.) (solid line) and the charging characteristic at the low temperature (broken line) (shown in FIG. 8). Charging characteristic map m). The voltage of each cell of the battery module is set to a predetermined voltage V2 (for example, 2.8 V) corresponding to a fully charged state and a predetermined voltage V1 (for example, 1.. 8V).

  However, even when the cell voltage is the same predetermined voltage V2, if the battery temperature is the basic temperature, the battery capacity a1 (for example, 100%) is charged. If the battery temperature is low, the battery capacity a2 (for example, for example) It will be charged only up to 80%). This difference in charge capacity corresponds to the low temperature charge shortage B.

  Even when the battery cell voltage is the same predetermined voltage V1, if the battery temperature is the basic temperature, the battery capacity is discharged to a4 (for example, 0%). If the battery temperature is low, the battery capacity is a3. It will be discharged only up to (for example, 20%). This difference in charge capacity corresponds to the low temperature discharge shortage C.

  The lower graph (b) is a “capacity deviation characteristic map” showing the difference between the charging characteristic (solid line) at the basic temperature (25 ° C.) and the charging characteristic when the capacity deviation occurs. Referring to the graph, even when the battery cell voltage is the same predetermined voltage V2, if the battery temperature is the basic temperature, the battery is charged up to the battery capacity a5 (for example, 100%). Only the capacity a6 (for example, 80%) is charged.

  The difference between the charge capacities corresponds to a capacity deviation subtraction amount F. The capacity deviation subtraction amount F includes a current value Ft of the capacity deviation amount and a previous value F0 of the capacity deviation amount calculated at the previous remaining capacity calculation. The total value is obtained. The self-discharge amount map 206m shown in FIG. 9 is for deriving the current value Ft of this capacity deviation amount.

  FIG. 11 is a flowchart showing the procedure of the remaining battery capacity calculation process when the vehicle is stopped. In step S1, the low temperature charge shortage amount B, the low temperature discharge shortage amount C, the discharge amount integrated value D, the full charge capacity A, the previous value SHmax0 of the maximum self-discharge amount, and the previous time of the capacity shift amount are stored from the memory in the control unit 200. Each value F0 is read. The “previous value” means a value calculated at the time of the previous remaining capacity calculation, and the full charge capacity A is a predetermined fixed value.

  In step S2, the upper (high temperature side) temperature sensor 91U and the lower (low temperature side) temperature sensor 91L detect two temperatures on the ceiling surface side and the bottom surface side of the battery 36. In step S3, the remaining battery capacity R is calculated. As shown in FIG. 10, the remaining battery capacity R is calculated from the full charge capacity A, the low temperature charge shortage amount B, the low temperature discharge shortage amount C, the discharge amount integrated value D, and the maximum self discharge amount integrated value E. And the displacement deviation subtraction amount F is subtracted.

  Next, in step S4, the SOC (battery charge rate) is calculated by a calculation formula of SOC = previous value R0 of remaining capacity ÷ capacity at full charge A × 100. In the subsequent step S5, the value of plus 2 ° C. (for example, 52 ° C.) and the calculated value of SOC (for example, 75%) are applied to the high-temperature side cell temperature respectively to the self-discharge amount map m of FIG. A current value SHmax of the self-discharge amount is derived. Here, the reason why the value of the low temperature side cell temperature plus 2 ° C. is used is to allow a temperature detection error.

  In step S6, the integrated value E of the maximum self-discharge amount is calculated by a calculation formula of E = previous value SHmax0 of the maximum self-discharge amount + current value SHmax of the maximum self-discharge amount.

  In step S7, the value of the low temperature side cell temperature minus 2 ° C. (for example, 38 ° C.) and the calculated SOC value are respectively applied to the self discharge amount map m shown in FIG. 9, and the minimum self discharge amount SHmin is derived. Is done. Here, the value of the low temperature side cell temperature minus 2 ° C. is used to allow a temperature detection error as in the high temperature side. In the subsequent step S8, the capacity deviation subtraction amount F is calculated by a calculation formula of F = the previous value F0 of the capacity deviation amount (current value SHmax of the maximum self-discharge amount−minimum self-discharge amount SHmin), and the process proceeds to step S9.

  In step S9, the remaining battery capacity R, the maximum self-discharge amount integrated value E, and the capacity deviation subtraction amount F calculated this time are stored in the memory, and the series of controls is terminated. Next, when calculating the remaining battery capacity, the remaining battery capacity, the integrated value of the maximum self-discharge amount, and the capacity deviation subtraction amount stored in the memory in step S10 are respectively used as previous values.

  FIG. 12 is a flowchart showing a procedure of battery remaining capacity calculation processing during vehicle traveling or charging. In step S11, the low temperature charge shortage amount B, the previous discharge amount value D0, the maximum self-discharge amount integrated value E, the capacity shift amount integrated value FS, and the capacity shift subtraction amount F are read from the memory in the control unit 200, respectively. It is.

  In step S12, the temperature of two locations of the battery module is detected by the upper (high temperature side) temperature sensor 91U and the lower (low temperature side) temperature sensor 91L. In step S13, the low temperature side cell temperature minus 2 ° C. (for example, 38 ° C.) is applied to the charging characteristic map m shown in FIG.

  In step S14, whether or not the battery 36 is in the fully charged state is determined by the fully charged state detecting means 202 of the control unit 200. If the determination is negative, that is, it is determined that the battery 36 is not in the fully charged state, the process proceeds to step S15. In step S15, the integrated value D of the discharge amount is calculated by a calculation formula of D = previous value Dl of discharge amount + current value Dt of discharge amount, and the process proceeds to step S16. The current value Dt of the discharge amount is a value measured by the charge / discharge current measuring unit 90.

  On the other hand, if an affirmative determination is made in step S14, that is, it is determined that the battery is fully charged, the process proceeds to step S19, and the value of the low temperature side cell temperature minus 2 ° C. (for example, 38 ° C.) is displayed. Applying to the map m shown in Fig. 10 (a), the low temperature charge shortage B is derived. When the integrated value D of the discharge amount is set to 0 (zero) in step S20 and the integrated value E of the maximum self-discharge amount is set to 0 (zero) in step S21, the process proceeds to step S22.

  In step S22, it is determined whether or not the equalization processing by the equalization processing means 208 has been completed, and a negative determination is made in step S22, that is, if it is determined that the equalization processing has not yet ended, step S23 Proceed to In step S23, the displacement deviation subtraction amount F is calculated by an equation of F = integration value FS of displacement displacement amount + equalization remaining capacity K. Here, the equalization processing remaining capacity K is a correction coefficient in consideration of a capacity error that remains even after the equalization process is performed. In subsequent step S24, the integrated value FS of the displacement amount is set to a predetermined fixed value (for example, 0.5 Ah), the equalization end information is reset, and the process proceeds to step S16. If an affirmative determination is made in step S22, that is, if it is determined that the displacement amount has been corrected by the equalization process, the process proceeds to step S25, where the displacement amount subtraction amount F is set to the integrated value FS of the displacement amount. Then, the process proceeds to step S24.

  In step S16, the remaining battery capacity R is calculated as a full charge capacity A- (low temperature charge shortage amount B + low temperature discharge shortage amount C + discharge amount integrated value D + maximum self discharge amount integrated value E + capacity deviation subtraction amount F). Calculated by the formula. In continuing step S17, it is determined whether the system of the electric vehicle 1 stopped, and when negative determination is carried out, it will return to step S12. Thus, when the vehicle is traveling or charging, the calculation process of the remaining battery capacity R is always continued.

  On the other hand, when an affirmative determination is made in step S17, that is, when the vehicle power is turned off and the vehicle enters a stop state where the charging circuit is not operating, the process proceeds to step S18, and the low temperature charge shortage amount is stored in the memory of the controller 200 B, the integrated value D of the discharge amount, the integrated value E of the maximum self-discharge amount, the capacity deviation subtraction amount F, and the integrated value FS of the capacity deviation amount are respectively stored, and the series of control is finished. When calculating the remaining battery capacity next time, the low-temperature charge shortage amount B, the discharge amount integrated value D, and the maximum self-discharge amount integrated value E stored in the memory in step S18 are used as the previous values, respectively. Will be.

  As described above, according to the remaining battery capacity calculation device of the present invention, the high-temperature side temperature sensor disposed at the highest temperature position (position expected to be high temperature) in the battery, Low temperature side temperature sensor disposed at the lowest temperature position (position where the temperature is expected to be low), the output value of the low temperature side temperature sensor and the high temperature side temperature sensor, and the value of the charging rate of the battery Based on the above, the maximum self-discharge amount and the minimum self-discharge amount of the battery were derived, and the value obtained by subtracting the minimum self-discharge amount from the maximum self-discharge amount was calculated as the capacity deviation amount of each cell. It is possible to improve the detection accuracy of the remaining capacity of the battery by considering the capacity shift amount.

  The battery capacity and structure, the configuration of the control unit, the charging characteristic map, the capacity deviation characteristic map, the setting of the self-discharge amount map, the execution timing of the remaining capacity calculation process and the equalization process are not limited to the above embodiments, Various changes are possible. The battery remaining capacity calculation device according to the present invention can be applied to secondary batteries used for various purposes in addition to batteries used as power sources for electric vehicles.

  2a ... battery cell, 36 ... main battery (battery), 90 ... charge / discharge current measuring unit, 91U ... upper (high temperature side) temperature sensor, 91L ... lower (low temperature side) temperature sensor, 200 ... control unit, 202 ... full Charge state detection means, 202a ... battery voltage sensor, 203 ... discharge amount detection means, 204 ... low temperature charge shortage detection means, 205 ... low temperature discharge shortage detection means, 206 ... capacity deviation amount calculation means, 207 ... self discharge amount calculation Means, 206m ... Self-discharge amount map, 208 ... Equalization processing means, m ... Charging characteristic map, A ... Full charge capacity, B ... Low temperature charge shortage amount, C ... Low temperature discharge shortage amount, D ... Discharge amount integrated value, E: integrated value of maximum self-discharge amount, F: capacity shift subtraction amount, FS: integrated value of capacity shift amount, SHmax: current value of maximum self-discharge amount, SHmax0: previous value of maximum self-discharge amount, Hmin ... minimum amount of self-discharge, Ft ... capacity the amount of deviation of the current value, F0 ... capacity deviation amount of the previous value

Claims (7)

A temperature sensor (91U, 91L) for detecting a temperature at a predetermined position of the battery (36) formed by combining a plurality of cells (2a);
In a battery remaining capacity calculation device comprising: a control unit (200) that calculates a remaining capacity (R) of the battery (36) by subtracting a plurality of subtraction elements from a full charge capacity (A) of the battery (36). ,
The temperature sensor (91U, 91L) includes a high temperature side temperature sensor (91U) disposed at a position where a high temperature is expected in the battery (36), and a position where a low temperature is expected in the battery (36). A low temperature side temperature sensor (91L) disposed in
The control unit (200) is configured to obtain a minimum self derived based on an output of the low temperature side temperature sensor (91L) from a maximum self discharge amount (SHmax) derived based on an output of the high temperature side temperature sensor (91U). A value obtained by subtracting the discharge amount (SHmin) is calculated as a capacity deviation amount (Ft) of the battery (36), and the capacity deviation amount (Ft) is calculated when the remaining capacity (R) is calculated. The remaining battery capacity calculation device is included in a subtraction element to be subtracted from   The capacity deviation amount (Ft) is set to the current value, and is an integrated value of the current value (Ft) of the capacity deviation amount and the previous value (F0) of the capacity deviation amount calculated at the time of the previous remaining capacity calculation. The battery remaining capacity calculation device according to claim 1, wherein the capacity deviation subtraction amount (F) is used as a subtraction element for subtracting from the full charge capacity (A) when calculating the remaining capacity (R).   Based on the output values of the low temperature side temperature sensor (91L) and the high temperature side temperature sensor (91U) and the value of the charge rate (SOC) of the battery (36), the maximum self-discharge amount (SHmax) and the minimum self-discharge The battery remaining capacity calculation device according to claim 1 or 2, further comprising a self-discharge amount map (206m) for deriving an amount (SHmin). The battery (36) is formed in a substantially rectangular parallelepiped with its ceiling surface and bottom surface oriented substantially horizontally when mounted on the vehicle (1),
The high temperature side sensor (91U) is attached to the ceiling surface side of the battery (36),
The battery low capacity calculation device according to any one of claims 1 to 3, wherein the low temperature side sensor (91L) is attached to a bottom surface side of the battery (36).   The low temperature side temperature sensor (91L) and the high temperature side temperature sensor (91U) are respectively attached to the approximate center of the battery (36) in the longitudinal direction of the vehicle body and the approximate center of the vehicle width direction. The remaining battery capacity calculation device according to claim 4. The control unit (200)
Based on the difference between the charging characteristics at the basic temperature and the charging characteristics at a low temperature of the battery (36), the low temperature charge shortage (B) and the low temperature discharge shortage (C) are calculated,
Based on the measured value of the charge / discharge current measuring unit (90), the integrated value (D) of the discharge amount of the battery (36) is calculated,
The maximum self-discharge amount (SHmax) is set to the current value, and the current value (SHmax) of the maximum self-discharge amount is integrated with the previous value (SHmax0) of the maximum self-discharge amount calculated at the time of the previous remaining capacity calculation. Calculate the value (E)
The calculated displacement amount (Ft) is set to the current value, and the present value (Ft) of the displacement amount is integrated with the previous value (F0) of the displacement amount calculated at the previous remaining capacity calculation. Calculate the capacity deviation subtraction amount (F) that is the value,
From the full charge capacity (A), the low temperature charge shortage amount (B), the low temperature discharge shortage amount (C), the discharge amount integrated value (D), and the maximum self discharge amount integrated value (E 2) and the capacity deviation subtraction amount (F), the remaining capacity (R) is calculated by calculating the remaining battery capacity (R). The battery (36) is housed in a box-shaped battery case (37),
The battery case (37) is configured such that cooling air introduced from an opening (93) provided on one wall surface is led out from an opening (94) provided on the other wall surface,
The battery remaining capacity calculation device according to any one of claims 1 to 6, wherein the high temperature side temperature sensor (91U) is disposed downstream of the cooling air from the low temperature side temperature sensor (91L). .

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