JP6293010B2 - Power storage system - Google Patents

Description

  The present invention relates to a power storage system having a plurality of battery packs connected in parallel to each other, and at least a part of the battery packs being removable, and a control method therefor.

  As a battery of an electric vehicle, a battery module in which battery packs having a plurality of batteries connected in series with each other are connected in parallel with each other is used. Charging of the battery module is performed using an external power supply source, and a method of simultaneously charging all the battery packs constituting the battery module is employed. In many cases, dedicated equipment is required to charge the battery module. For this reason, charging of the battery is not easy to use because the degree of freedom of selection is low for the user.

  In addition, there is a charging method for increasing the remaining capacity of a battery pack having a low remaining capacity by performing power interchange between battery packs constituting a battery module when an external power supply source is not used (for example, Patent Documents). 1, 2).

Japanese Utility Model Publication No. 64-20039 Special table 2014-511095 gazette

  However, the inventions according to Patent Documents 1 and 2 described above only exchange power within the battery module, and in order to increase the remaining capacity of the entire battery module, the battery module is connected to an external power supply source. It is necessary and is not different from the conventional charging method.

  In view of the above background, an object of the present invention is to increase options for a charging method in a power storage system.

  In order to solve the above problems, the present invention provides a chargeable / dischargeable battery (11), a converter (12) that changes the discharge current and the charge current of the battery, and detects the state of the battery and controls the converter. A plurality of battery packs (7) each having a pack control unit (13) to be connected, and a circuit for connecting the plurality of battery packs in parallel to each other and to an electrical load (3, 4) and a power supply source (5) (8) and an integrated control unit (35) for setting a command value for each discharge current and charge current of the battery pack based on the state of the battery and outputting the command value to the pack control unit. The pack control unit controls the converter based on the command value when the command value is acquired, and at least one of the battery packs includes a front Characterized in that it is detachably connected to the circuit.

  According to this configuration, since at least one of the battery packs is detachably connected to the circuit, the battery pack can be detached from the circuit and the removed battery pack can be individually charged. Therefore, when there is no external power source that can be used around the power storage system, charging can be performed by separating some of the battery packs from the power storage system and transporting them to an available external power source.

  Moreover, since each battery pack has a converter and can change the discharge current (discharge voltage) and the charge current (charge voltage), an excessive current is generated even when a large voltage difference occurs between the batteries of each battery pack. Is prevented from flowing.

In the above invention, at least one of the battery packs suitable for attachment / detachment from the circuit belongs to the attachment / detachment battery pack group (41), and the other batteries other than the attachment / detachment battery pack group Assume that the pack belongs to the installed battery pack group (42), the pack control unit detects the voltage of each battery of the battery pack, and the integrated control unit detects the battery pack belonging to the removable battery pack group. The battery pack in which the discharge current of the battery pack belonging to the removable battery pack group belongs to the installed battery pack group when the average value (V1 _AVE ) of the battery voltage is equal to or greater than a predetermined voltage threshold value (V1 _SH ). The command value may be set to be larger than the discharge current.

  According to this configuration, since the battery packs belonging to the removable battery pack group are expected to be charged separately from the power storage system, the discharge amount is larger than the battery packs belonging to the installation battery pack group, and the remaining capacity The capacity which can be charged can be increased by lowering. In addition, since the SOC of the battery pack belonging to the installed battery pack group is maintained high, the charge amount between packs from the battery pack belonging to the removable battery pack group to the battery pack belonging to the installed battery pack group is reduced, and the power usage efficiency Will improve.

In the above invention, the integrated control unit acquires a required power value (P) of the electric load, the required power value is equal to or less than a predetermined required power threshold value (P _SH ), and the removable battery pack. The average value (V1 _AVE ) of the batteries of the battery packs belonging to a group is equal to or greater than a predetermined voltage threshold (V1 _SH ), and the average value of the voltages of the batteries of the battery packs belonging to the removable battery pack group A voltage difference (D) obtained by subtracting an average value (V2 _AVE ) of the batteries of the battery packs belonging to the installed battery pack group from the first voltage difference threshold (D1) greater than 0 and the first When it is equal to or smaller than a second voltage difference threshold (D2) greater than the voltage threshold, it is released to the pack controller of the battery pack belonging to the removable battery pack group. The pack controller of the battery pack which belongs to the installation battery pack group and sets the command value of the current may be set to the command value of the charging current.

  According to this configuration, when the voltage difference between the battery pack belonging to the removable battery pack group and the battery pack belonging to the installed battery pack group is within a predetermined range, power is supplied from the removable battery pack group to the installed battery pack group. The installed battery pack group can be charged. If the voltage difference is greater than D2 or less than D1, the charging efficiency is low. Therefore, charging efficiency can be improved by not performing inter-pack charging.

  In the above invention, at least one of the battery packs suitable for attachment / detachment from the circuit belongs to the attachment / detachment battery pack group, and the other battery packs other than the attachment / detachment battery pack group are installed. The pack control unit detects the voltage of each battery of the battery pack, and the integrated control unit detects that the charging current of the battery pack belonging to the installation battery pack group is the detachable battery. The command value may be set to be larger than a charging current of the battery pack belonging to the pack group.

  According to this configuration, since the battery pack belonging to the removable battery pack group is expected to be charged separately from the power storage system, the battery pack belonging to the installed battery pack group rather than the battery pack belonging to the removable battery pack group. It is possible to charge efficiently by charging with priority. In addition, since the SOC of the battery pack belonging to the installed battery pack group is increased, the charge amount between packs from the battery pack belonging to the removable battery pack group to the battery pack belonging to the installed battery pack group is reduced, and the power use efficiency is improved. To do.

  Further, in the above invention, the pack control unit of each of the battery packs is configured so that the current flowing through each of the battery packs is less than or equal to a preset maximum current value in preference to the command value. Each converter of the pack may be controlled.

  According to this structure, it is prevented that an excessive electric current flows into a battery pack, and damage and deterioration of a battery pack are suppressed. In particular, even when the potential difference between the battery pack belonging to the detachable battery pack group and the battery pack belonging to the stationary battery pack group is large, the discharge current of the detachable battery pack group is suppressed to a maximum current value or less.

  The integrated control unit may set the command values for the discharge current and the charge current of each of the battery packs based on at least one of the temperature of the battery and the SOC of the battery.

  According to this configuration, the SOC and battery temperature of each battery pack can be controlled.

  Another aspect of the present invention is an electric vehicle (1) including the power storage system and an electric motor (3) as the electric load.

  Another aspect of the present invention is a battery that can be charged and discharged (11), a converter (12) that changes a discharge current and a charge current of the battery, and a pack that detects the state of the battery and controls the converter. A plurality of battery packs (7) each having a control unit (13); a plurality of the battery packs connected in parallel to each other; and a circuit (8) connected to an electric load (3, 4) and a power supply source; An integrated control unit (35) for setting a command value for each discharge current and charge current of the battery pack based on the state of the battery and outputting the command value to the pack control unit; The control unit controls the converter based on the command value when the command value is acquired, and at least one of the battery packs is detachable from the circuit. It is assumed that at least one of the battery packs that is suitable for attachment and detachment from the circuit belongs to the detachable battery pack group (41), and the other battery packs other than the detachable battery pack group are installed batteries. A method for controlling a power storage system belonging to a pack group (42), wherein the pack control unit detects a voltage of each battery of the battery pack, and the integrated control unit is connected to the removable battery pack group. When the average value of the battery voltage of the battery pack to which the battery pack belongs is equal to or greater than a predetermined voltage threshold, the discharge current of the battery pack belonging to the removable battery pack group is the discharge current of the battery pack belonging to the stationary battery pack group And setting the command value to be larger than It is characterized in.

  According to the above configuration, the charging method options can be increased in the power storage system.

Configuration diagram of an electric vehicle equipped with a power storage system Configuration diagram of first battery pack (A) Explanatory diagram showing the flow of current when discharging the first battery pack, (B) Explanatory diagram showing the flow of current when charging the first battery pack Flow chart showing the control procedure of the integrated control unit The figure which shows each control area _| region based on detachable battery pack group average voltage V1 _AVE and installation battery pack group average voltage V2 _AVE The block diagram of the 1st battery pack which concerns on a modification

  Hereinafter, an embodiment in which a power storage system according to the present invention is applied to a power source of an electric vehicle will be described with reference to the drawings. The electric vehicle includes an electric vehicle including an electric motor as a drive source, a small electric vehicle (micro EV), and a plug-in hybrid vehicle.

  As shown in FIG. 1, the electric vehicle 1 includes a power storage system 2, an electric motor 3 (motor generator) and a PDU 4 (power drive unit) as an electric load, and a charging device 5. The power storage system 2 includes a plurality of battery packs 7 and a circuit 8 that connects the plurality of battery packs 7 in parallel to each other and connects the battery pack 7 to the PDU 4 and the charging device 5. In the present embodiment, the power storage system 2 includes first to sixth battery packs 7.

  The electric motor 3 is a motor generator, receives electric power supplied from the power storage system 2 via the PDU 4, and generates a driving force for rotating the wheels. The electric motor 3 generates electric power by regeneration during braking of the vehicle, and supplies electric power to the power storage system 2 via the PDU 4. The PDU 4 includes an inverter, converts DC power from the power storage system 2 into three-phase AC, and controls the drive of the electric motor 3 by controlling the current value. The PDU 4 controls the amount of regeneration generated by the electric motor 3, converts alternating-current regenerative power into direct current, and supplies the direct current to the power storage system 2. The charging device 5 is a device that connects the power storage system 2 and an external power supply source. The power supply source may be, for example, a commercial power supply. In this case, the charging device 5 converts alternating current into direct current and supplies it to the power storage system 2. The charging device 5 may include a converter that boosts or lowers the voltage of the external power supply.

  FIG. 2 is a configuration diagram of the first battery pack 7. The second to sixth battery packs 7 have the same configuration as the first battery pack 7. The first battery pack 7 includes a battery 11, a converter 12, and a BMU 13 (battery management unit, pack control unit). The battery 11, the converter 12, and the BMU 13 are disposed in the battery case 14. A positive terminal 16, a negative terminal 17, and a control terminal 18 are provided on the outer surface of the battery case 14.

  The battery 11 has a plurality of battery cells 11A connected to each other. The plurality of battery cells 11A may be connected in series and in parallel. In the present embodiment, the battery 11 includes a plurality of battery cells 11A connected in series. The positive electrode of the battery 11 is connected to the positive terminal 16 via the power line 19, and the negative electrode of the battery 11 is connected to the negative terminal 17 via the power line 19.

  The converter 12 is a DC-DC converter, and is provided on a power line 19 that connects the negative electrode of the battery 11 and the negative terminal 17. The converter 12 includes, in order from the negative electrode side of the battery 11, a discharging FET 21 as a discharging contactor, an inductor 22, and a charging FET 23 as a charging contactor. The discharging FET 21 and the charging FET 23 are N-channel MOSFETs. The source of the discharge FET 21 is connected to the negative electrode of the battery 11, and the drain is connected to the inductor 22. The charging FET 23 has a source connected to the negative terminal 17 side and a drain connected to the inductor 22. The gates of the discharging FET 21 and the charging FET 23 are connected to the BMU 13, respectively, and a signal is input from the BMU 13.

  The power line 19 is provided with a bypass line 25 that bypasses the battery 11 and connects the positive terminal 16 and the negative terminal 17. The bypass line 25 has one end connected to the portion between the positive electrode of the battery 11 and the positive terminal 16, and the other end connected to the source side of the discharging FET 21 of the power line 19 via the first capacitor 26. The other end of the bypass line 25 is connected to the drain side of the charging FET 23 of the power line 19 via the second capacitor 27 and connected to the drain side of the discharging FET 21 of the power line 19 via the first diode 28. The power line 19 is connected to the source side of the charging FET 23 via the second diode 29. The first capacitor 26, the second capacitor 27, the first diode 28, and the second diode 29 are connected in parallel to each other. The first diode 28 and the second diode 29 allow a current to flow from the negative terminal 17 side of the power line 19 to the bypass line 25 side.

  The BMU 13 detects the voltage, current, and temperature of the battery 11 and inputs signals to the gates of the discharging FET 21 and the charging FET 23 to control the opening and closing of the discharging FET 21 and the charging FET 23. A shunt resistor 31 is provided between the negative electrode of the battery 11 in the power line 19 and the discharging FET 21. Both ends of the shunt resistor 31 are connected to the BMU 13, and the current flowing through the shunt resistor 31 is detected by the BMU 13. In this way, the BMU 13 acquires a current (battery current) flowing through the battery 11. The positive and negative electrodes of each battery cell 11A are connected to the BMU 13, and the voltage between both ends of each battery cell 11A is detected by the BMU 13. The BMU 13 acquires the voltage of the battery 11 based on the voltage of each battery cell 11A. Further, the BMU 13 has a temperature sensor 32 for detecting the temperature of the battery 11 and acquires the battery temperature based on a signal from the temperature sensor 32. The temperature sensor 32 may be a thermistor, for example. The BMU 13 calculates an SOC (State Of Charge) from the acquired battery voltage.

  As shown in FIG. 1, the BMU 13 of each battery pack 7 is connected to an MG_ECU 35 (integrated control unit) via a network such as CAN. Each BMU 13 inputs the acquired battery current, battery voltage, battery temperature, and SOC to the MG_ECU 35. The MG_ECU 35 inputs a command value to the BMU 13 of each battery pack 7 based on the acquired battery current, battery voltage, battery temperature, SOC, and the like. The command value includes a discharge current value and a charge current value.

  The BMU 13 performs PWM control of the discharging FET 21 and the charging FET 23 of the converter 12 based on the command value from the MG_ECU 35, thereby realizing the discharge current and the charging current of the command value. When receiving the command value of the discharge current, the BMU 13 turns on the charging FET 23 and opens / closes the discharging FET 21 based on PWM control. As shown by the solid arrow in FIG. 3A, when the discharging FET 21 is turned on, the current flows through the charging FET 23, the inductor 22, and the discharging FET 21 in this order. At this time, energy is stored in the inductor 22 and a back electromotive force is generated. 3A, when the discharging FET 21 is turned off, a current flowing through the inductor 22, the first diode 28, and the bypass line 25 in sequence is generated, and the battery pack 7 Current flows between the terminals.

  When receiving a charge command, the BMU 13 turns on the discharge FET 21 and opens / closes the charge FET 23 based on PWM control. As indicated by a solid arrow in FIG. 3B, when the discharging FET 21 is turned on, the current flows through the discharging FET 21, the inductor 22, and the charging FET 23 in this order. At this time, energy is stored in the inductor 22 and a back electromotive force is generated. 3B, when the charging FET 23 is turned off, a current flowing through the inductor 22, the second diode 29, and the bypass line 25 in order is generated, and the battery pack 7 Current is generated between the terminals.

  As described above, the converter 12 steps down the discharge voltage and the charge voltage and reduces the discharge current and the charge current. That is, the converter 12 functions as a step-down device. The BMU 13 performs PWM control on the converter 12 to change the discharge voltage (discharge current) and the charge voltage (charge current) of each battery pack 7. The discharge voltage and the charge voltage become lower as the duty ratio becomes smaller. The first and second capacitors 26 and 27 are provided for the purpose of absorbing a switching surge.

  Further, the BMU 13 controls the converter 12 so that an excessive current does not flow through each battery pack 7 during discharging and charging. In each battery pack 7, the BMU 13 acquires the battery current and determines whether the battery current is less than a preset maximum battery current. The maximum battery current is set for each battery pack 7 and is set to a value that may cause damage and deterioration of the battery pack 7 when this value is exceeded. When the battery current is less than the maximum battery current, the BMU 13 sets the duty ratio of the discharging FET 21 or the charging FET 23 by feedback control so that the battery current becomes equal to the command value. On the other hand, when the battery current is equal to or greater than the maximum battery current, the duty ratio of the discharging FET 21 or the charging FET 23 is set by feedback control so that the battery current becomes equal to the maximum battery current.

  At least one of the first to sixth battery packs 7 is detachably connected to the circuit 8 and a structure such as a vehicle body. Among the detachable battery packs 7, at least one battery pack 7 suitable for detachment from the circuit 8 is referred to as a battery pack 7 belonging to the detachable battery pack group 41. The battery packs 7 other than the battery packs 7 belonging to the removable battery pack group 41 among all the battery packs 7 are referred to as battery packs 7 belonging to the installation battery pack group 42. The battery pack 7 belonging to the detachable battery pack group 41 is configured to be detachable from the circuit 8 more easily than the battery pack 7 belonging to the installed battery pack group 42, and is frequently attached and detached by the user without using tools or the like. It is configured to be able to. On the other hand, the battery packs 7 belonging to the installation battery pack group 42 are fastened to a structure such as a vehicle body by bolts or the like. The installed battery pack group 42 can include a battery pack 7 that is detachably connected to the circuit 8. The removable battery pack 7 belonging to the installed battery pack group 42 can be replaced when it is damaged or deteriorated.

  In this embodiment, all the battery packs 7 are detachably connected to the circuit 8, the first and second battery packs 7 belong to the removable battery pack group 41, and the third to sixth battery packs 7 are installed. It belongs to the battery pack group 42. That is, the 1st and 2nd battery pack 7 is comprised so that frequent attachment or detachment is possible, and the 3rd-6th battery pack 7 is comprised so that replacement | exchange is possible when damaged.

  Each battery pack 7 is connected to the circuit 8 at the positive terminal 16 and the negative terminal 17, and is connected to the network at the control terminal 18. Each battery pack 7 is connected to the PDU 4 and the charging device 5 via a circuit 8.

  As described above, since the first and second battery packs 7 belonging to the detachable battery pack group 41 are easily detachable, the user removes at least one of the first and second battery packs 7 from the circuit 8 to store the power. Charging can be performed separately at a location away from the system 2 and the electric vehicle 1. Since the battery pack 7 removed from the power storage system 2 is a part of the plurality of battery packs 7 constituting the power storage system 2, it is relatively light and easy to carry by the user. For example, the user can bring the removed battery pack 7 into a building such as a house and charge the battery pack 7 using a commercial power source provided in the house. In that case, the charging device 5 which connects the battery pack 7 and a commercial power supply may be used. Further, the charging device 5 may be built in the battery pack 7.

  In addition, the user can attach another battery pack 7 that has already been charged instead of the removed battery pack 7 to the power storage system 2 as the first or second battery pack 7. Thus, even when there is no power supply facility available around the power storage system 2 and the electric vehicle 1, the user can recover the SOC of at least one of the first and second battery packs 7.

  When the SOC of at least one of the first and second battery packs 7 is recovered by the charge after removal or the replacement with the battery pack 7 that has been charged, the electric power of the first and second battery packs 7 is used. Charge between packs for charging the third to sixth battery packs 7 can be performed. Thereby, SOC of the 3rd-6th battery pack 7 can be recovered.

Next, the control procedure of the power storage system 2 will be described. The power storage system 2 is controlled differently during discharging when the power supply source is not connected to the charging device 5 and during charging when the power supply source is connected to the charging device 5. The control of the power storage system 2 at the time of discharging is performed based on the flow shown in FIG. First, in step S1, the MG_ECU 35 determines whether or not the required power P of the PDU 4 is less than or equal to a predetermined required power threshold value P _SH . The required power P is set based on, for example, the accelerator pedal opening degree and the vehicle speed of the electric vehicle 1. The required power threshold value P _SH is set to an amount of power that can be supplied while the power storage system 2 performs inter-pack charging.

When the required power P is less than or equal to the required power threshold P _SH , the MG_ECU 35 attaches / detaches battery pack group average voltage V1 that is an average value of the battery voltages of the first and second battery packs 7 belonging to the attachable / detachable battery pack group 41 in step S2. _{AVE is,} it is determined whether the preset predetermined voltage threshold V _SH or more.

When the detachable battery pack group average voltage V1 _AVE is equal to or higher than the voltage threshold V _SH in step S2, the MG_ECU 35 determines from the detachable battery pack group average voltage V1 _AVE to the installed battery pack group 42 in step S3. Whether or not the voltage difference D obtained by subtracting the installed battery pack group average voltage V2 _AVE , which is the average value of the battery voltages of 7, is equal to or greater than the first voltage difference threshold D1 and equal to or less than the second voltage difference threshold D2. judge. The first voltage difference threshold D1 is a value greater than zero.

  In step S3, when the relationship of D1 ≦ D ≦ D2 is satisfied, in step S4, the MG_ECU 35 selects inter-pack charge control. In the inter-pack charge control, the MG_ECU 35 inputs the command value of the discharge current to the BMU 13 of the first and second battery packs 7 and also inputs the command value of the charge current to the BMU 13 of the third to sixth battery packs 7.

When the battery currents in the first to sixth battery packs 7 are I _{1 to} I ₆ and the current flowing through the PDU 4 is I ₇ (= P / V), the command values are the first and second values belonging to the removable battery pack group 41. The sum of the battery currents of the battery pack 7 and the battery currents of the third to sixth battery packs 7 belonging to the installed battery pack group 42 and the current flowing through the PDU 4 are set to be equal to the sum of I ₇ (I _{1 + I 2 = I 3 +} I 4 + I 5 + I 6 + I 7). Also, the distribution of the battery current (discharge current) of the first and second battery packs 7 belonging to the detachable battery pack group 41, the battery current (charge current) of the third to sixth battery packs 7 belonging to the installation battery pack group 42, The distribution may be set in consideration of the SOC of each battery pack 7 and the battery temperature. For example, the battery current distribution of the first and second battery packs 7 is set so that the distribution is larger (the discharge current is larger) as the SOC is higher, and the distribution is smaller (the discharge current is smaller) as the battery temperature is higher. Good. The battery current distribution of the third to sixth battery packs 7 is such that the distribution is higher (the charging current is larger) as the SOC is smaller, and the distribution is smaller (the charging current is smaller) as the battery temperature is higher. Should be set.

  BMU 13 of each battery pack 7 receives a command value from MG_ECU 35 and controls converter 12 so that each battery current is equal to the command value. At this time, as described above, the BMU 13 controls the converter 12 so that the battery current becomes equal to or less than the maximum battery current in preference to the command value.

  Since the power of the first and second battery packs 7 belonging to the removable battery pack group 41 is supplied to the third to sixth battery packs 7 belonging to the installation battery pack group 42 by the inter-pack charge control, the removable battery pack group 41 While the SOCs of the first and second battery packs 7 belonging to, the SOC of the third to sixth battery packs 7 belonging to the installed battery pack group 42 increases.

If the relationship of D1 ≦ D ≦ D2 is not satisfied in the determination of step S3, that is, if the voltage difference D is larger or smaller than a predetermined range, or the removable battery pack group average voltage V1 _AVE is the installed battery pack group average voltage If it is smaller than V2 _AVE , in step S5, the MG_ECU 35 selects concentrated discharge control. In the concentrated discharge control, the discharge amounts of the first and second battery packs 7 belonging to the removable battery pack group 41 are made larger than those of the third to sixth battery packs 7 belonging to the installed battery pack group 42.

In the concentrated discharge control, the MG_ECU 35 inputs a discharge current command value to the BMU 13 of the first to sixth battery packs 7. The command value is set so that the battery currents of the first and second battery packs 7 belonging to the detachable battery pack group 41 are larger than the battery currents of the third to sixth battery packs 7 belonging to the installation battery pack group 42. Is done. At this time, the battery currents of the first and second battery packs 7 are equal to each other, and the battery currents of the third to sixth battery packs 7 are set to be equal to each other (I ₁ = I ₂ > I ₃ = I ₄ = I ₅ = I ₆ ). The distribution of the battery currents (discharge currents) of the first and second battery packs 7 belonging to the detachable battery pack group 41 and the battery currents (discharge currents) of the third to sixth battery packs 7 belonging to the installation battery pack group 42 are as follows. The distribution may be set in consideration of the SOC and battery temperature of each battery pack 7. For example, the battery current distribution of the first and second battery packs 7 is set so that the distribution is larger (the discharge current is larger) as the SOC is higher, and the distribution is smaller (the discharge current is smaller) as the battery temperature is higher. Good. Further, the battery current distribution of the third to sixth battery packs 7 is such that the higher the SOC is, the larger the distribution is (the discharge current is large), and the higher the battery temperature is, the smaller the distribution is (the discharge current is small). Should be set.

  BMU 13 of each battery pack 7 receives a command value from MG_ECU 35 and controls converter 12 so that each battery current is equal to the command value. At this time, as described above, the BMU 13 controls the converter 12 so that the battery current becomes equal to or less than the maximum battery current in preference to the command value.

  Due to the concentrated discharge control, the SOC of the first and second battery packs 7 belonging to the removable battery pack group 41 is larger than the SOC of the third to sixth battery packs 7 belonging to the installation battery pack group 42. Thereby, SOC of the 1st and 2nd battery pack 7 which can be removed and charged from the electrical storage system 2 can be reduced preferentially.

The region where the inter-pack charge control and the concentrated discharge control are performed based on the determination in step S2 and step S3 is the region shown in FIG. In FIG. 5, the horizontal axis represents the detachable battery pack group average voltage V1 _AVE , and the vertical axis represents the installed battery pack group average voltage V2 _AVE . The inter-pack charge control is executed in a region R1 in which the detachable battery pack group average voltage V1 _AVE is equal to or higher than the voltage threshold V _SH and the voltage difference D satisfies the relationship of D1 ≦ D ≦ D2. In the concentrated discharge control, the detachable battery pack group average voltage V1 _AVE is equal to or higher than the voltage threshold V _SH and the voltage difference D is less than D1, or the detachable battery pack group average voltage V1 _AVE is equal to or higher than the voltage threshold V _SH . And in the region R3 where the voltage difference D is greater than D2. When the voltage difference D is less than D1, since the voltage difference is small, the charging efficiency is lowered. When the voltage difference D is greater than D2, the battery current flowing through the battery pack 7 is increased because the voltage difference is large. Therefore, the battery current is suppressed below the maximum battery current by converter 12, and charging efficiency is reduced.

When the detachable battery pack group average voltage V1 _AVE is less than the voltage threshold V _SH in step S2 (region R4 in FIG. 5), in step S5, the MG_ECU 35 selects normal discharge control. In the normal discharge control, the MG_ECU 35 selects one of the following first to fifth normal discharge controls.

  In the first normal discharge control, the MG_ECU 35 inputs a discharge current command value equal to the BMU 13 of the first to sixth battery packs 7. In the first normal discharge control, the amount of decrease in SOC of each battery pack 7 is substantially equal.

In the second normal discharge control, a discharge current command value is set based on the SOC of each battery pack 7. In the second normal discharge control, the distribution (ratio) of the battery current (discharge current) of each battery pack 7 is the reciprocal of the SOC of each battery pack 7 (I ₁ : I ₂ : I ₃ : I ₄ : I ₅ : I ₆ = 1 / SOC ₁ : 1 / SOC ₂ : 1 / SOC ₃ : 1 / SOC ₄ : 1 / SOC ₅ : 1 / SOC ₆ ), and the MG_ECU 35 sets a command value. Here, the subscript after the SOC represents the number of the corresponding battery pack 7. According to the second normal discharge control, the SOC of each battery pack 7 approaches the same value due to the discharge.

  In the third normal discharge control, a command value for the discharge current is set based on the SOC of each battery pack 7. In the third normal discharge control, the lower limit threshold value of the SOC is set, and the MG_ECU 35 sets the command value so that the discharge current of the battery pack 7 whose SOC is equal to or lower than the lower limit threshold value becomes zero. According to the third normal discharge control, the SOC of each battery pack 7 approaches the lower limit threshold value due to the discharge.

  In the fourth normal discharge control, a command value for the discharge current is set based on the battery temperature of each battery pack 7. In the fourth normal discharge control, the MG_ECU 35 sets the command value so that the distribution (ratio) of the battery current (discharge current) of each battery pack 7 decreases as the battery temperature increases. According to the fourth normal discharge control, the discharge current is suppressed in the battery pack 7 having a higher temperature, and the temperature rise is suppressed.

In the fifth normal discharge control, a command value for the discharge current is set based on the SOC of each battery pack 7 and the battery temperature. In the fifth normal discharge control, the distribution (ratio) of the battery current (discharge current) of each battery pack 7 is the reciprocal of the product of the SOC of each battery pack 7 and the battery temperature T (I ₁ : I ₂ : I ₃ : I ₄ : I ₅ : I ₆ = 1 / (SOC ₁ × T ₁ ): 1 / (SOC ₂ × T ₂ ): 1 / (SOC ₃ × T ₃ ): 1 / (SOC ₄ × T ₄ ): 1 / (SOC ₅ × T ₅ ): 1 / (SOC ₆ × T ₆ )), the MG_ECU 35 sets a command value. Here, the subscript after the battery temperature T represents the number of the corresponding battery pack 7. According to the fifth normal discharge control, the SOC of each battery pack 7 approaches the same value due to the discharge, and the discharge current is suppressed and the temperature rise is suppressed as the battery pack 7 has a higher temperature.

  The MG_ECU 35 may execute one selected in advance from the first to fifth normal discharge controls in the normal discharge control. Further, the MG_ECU 35 may select one of the first to fifth normal discharge controls based on the state of the battery pack 7 in the normal discharge control. For example, when a predetermined SOC threshold value and a battery temperature threshold value are set, and the first normal discharge control is selected when the lowest SOC among the battery packs 7 is equal to or higher than the predetermined SOC threshold value, and becomes less than the predetermined threshold value Alternatively, the second normal discharge control or the third normal discharge control may be selected. Further, the first normal discharge control is selected when the highest battery temperature in each battery pack 7 is equal to or lower than a predetermined battery temperature threshold, and the fourth normal discharge control or the second 5 Ordinary discharge control may be selected.

In the flowchart of FIG. 4, when the required power P is larger than the required power threshold value P _SH in step S1, the MG_ECU 35 determines in step S7 whether the detachable battery pack group average voltage V1 _AVE is equal to or higher than _the voltage threshold value V _SH . Determine.

When the detachable battery pack group average voltage V1 _AVE is equal to or higher than the voltage threshold V _SH in step S7, the MG_ECU 35 performs concentrated discharge control in step S8. The concentrated discharge control is the same as the control in step S5 described above.

If the detachable battery pack group average voltage V1 _AVE is less than the voltage threshold V _SH in step S7, the MG_ECU 35 performs normal discharge control in step S9. The normal discharge control is the same as the control in step S6 described above.

  Next, a control method of the power storage system 2 when the charging device 5 is connected to an external power supply source and the first to sixth battery packs 7 are charged (during charging) will be described. At the time of charging, the MG_ECU 35 inputs a charging current command value to the BMU 13 of the first to sixth battery packs 7 based on the charging control. The MG_ECU 35 selects and executes one of the following first to fifth charging controls in the charging control.

  In the first charge control (equal charge control), the MG_ECU 35 equalizes the command value of the charge current input to the BMU 13 of each battery pack 7. In the first charge control, the amount of increase in SOC of each battery pack 7 is substantially equal.

  In the second charge control (centralized charge control), the MG_ECU 35 is set so that the battery current (charge current) of the third to sixth battery packs 7 is larger than the battery current (charge current) of the first and second battery packs 7. Sets each command value. According to the second charge control, the SOC of the third to sixth battery packs 7 belonging to the installation battery pack group 42 is higher than the SOC of the first and second battery packs 7 belonging to the removable battery pack group 41. Distribution of the battery current (charging current) of the first and second battery packs 7 belonging to the detachable battery pack group 41 and distribution of the battery current (charging current) of the third to sixth battery packs 7 belonging to the installation battery pack group 42 are as follows: The battery pack 7 may be set in consideration of the SOC and battery temperature. For example, the battery current distribution of the first and second battery packs 7 is set so that the distribution is smaller (the charging current is smaller) as the SOC is higher, and the distribution is smaller (the charging current is smaller) as the battery temperature is higher. Good. The battery current distribution of the third to sixth battery packs 7 is such that the higher the SOC is, the smaller the distribution is (the charging current is small), and the higher the battery temperature is, the smaller the distribution is (the charging current is small). Should be set.

In the third charging control, a charging current command value is set based on the SOC of each battery pack 7. In the third charge control, the distribution (ratio) of the battery current (charge current) of each battery pack 7 is the reciprocal of the SOC of each battery pack 7 (I ₁ : I ₂ : I ₃ : I ₄ : I ₅ : I ₆ = 1 / SOC ₁ : 1 / SOC ₂ : 1 / SOC ₃ : 1 / SOC ₄ : 1 / SOC ₅ : 1 / SOC ₆ ), and the MG_ECU 35 sets a command value. According to the third charging control, the SOCs of the battery packs 7 approach the same value due to charging.

  In the fourth charging control, a charging current command value is set based on the battery temperature of each battery pack 7. In the fourth charge control, the MG_ECU 35 sets the command value so that the battery current (charge current) distribution (ratio) of each battery pack 7 decreases as the battery temperature increases. According to the fourth charging control, the charging current is suppressed in the battery pack 7 having a higher temperature, and the temperature rise is suppressed.

In the fifth charging control, a charging current command value is set based on the SOC and battery temperature of each battery pack 7. In the fifth charging control, the distribution (ratio) of the battery current (charging current) of each battery pack 7 is the reciprocal of the product of the SOC of each battery pack 7 and the battery temperature T (I ₁ : I ₂ : I ₃ : I ₄ : I ₅ : I ₆ = 1 / (SOC ₁ × T ₁ ): 1 / (SOC ₂ × T ₂ ): 1 / (SOC ₃ × T ₃ ): 1 / (SOC ₄ × T ₄ ): 1 / (SOC ₅ × T ₅ ): 1 / (SOC ₆ × T ₆ )), the MG_ECU 35 sets a command value. According to the fifth charge control, the SOCs of the battery packs 7 approach each other due to discharge, and the discharge current is suppressed and the temperature rise is suppressed as the battery pack 7 has a higher temperature.

  The MG_ECU 35 may select and execute one of the first to fifth charge controls in advance in the charge control. Further, the MG_ECU 35 may select one of the first to fifth charging controls according to the state of the battery pack 7.

  The power storage system 2 configured as described above includes the removable battery pack 7 among the plurality of battery packs 7 connected in parallel to each other. Therefore, the user removes the battery pack 7 from the power storage system 2, and the power storage system The battery pack 7 can be charged at a location distant from 2. Therefore, even in a situation where there is no power supply source available around the vehicle equipped with the power storage system 2, the user removes some of the battery packs 7 from the power storage system 2 and transports the battery pack 7 to the power supply source. Can be charged. Moreover, by preparing the battery pack 7 that has been charged in advance, the SOC of some of the battery packs 7 can be recovered by replacement without being charged each time. As described above, the power storage system 2 according to the present embodiment has many options for the charging method. The battery pack 7 installed in the power storage system 2 can be supplied with electric power from the battery pack 7 whose SOC has been recovered by individual charging or replacement, and can recover the SOC.

When the first or second battery pack 7 belonging to the detachable battery pack group 41 is removed from the power storage system 2 and charged individually, the voltage difference D between the detachable battery pack group average voltage V1 _AVE and the installed battery pack group average voltage V2 _AVE May be greater than D2 (point 100 in region R3 in FIG. 5). In this case, when charging between packs, since the voltage difference D is large, the battery current flowing through the battery pack 7 is increased, and the battery current is suppressed below the maximum battery current by the converter 12, so that the charging efficiency is reduced. . Therefore, in this case, the power storage system 2 makes the discharge amounts of the first and second battery packs 7 larger than the discharge amounts of the third to sixth battery packs 7 by concentrated discharge control. When the concentrated discharge control is executed, the voltage difference D gradually decreases to D2 or less (point 101 at the boundary between the region R3 and the region R1 in FIG. 5). By performing the inter-pack charge control when the voltage difference becomes D2 or less, the inter-pack charge can be performed efficiently.

When the inter-pack charge control is executed, the voltage difference D further decreases and becomes equal to or less than D1 (point 102 at the boundary between the region R1 and the region R2 in FIG. 5). When the voltage difference D becomes smaller, the efficiency of inter-pack charging is lowered, and therefore switching from inter-pack charge control to concentrated discharge control is performed. Thereafter, until the detachable battery pack group average voltage V1 _AVE becomes less than the voltage threshold V _SH (point 102 at the boundary between the region R2 and the region R4 in FIG. 5), the concentrated discharge control is performed, so that the detachable battery pack group 41 The SOC of the first and second battery packs 7 to which it belongs is lower than the SOC of the third to sixth battery packs 7 that belong to the installed battery pack group 42. Thereby, the efficiency of charging by removing the first and second battery packs 7 is improved. In addition, maintaining the SOC of the third to sixth battery packs 7 reduces the power supplied for inter-pack charging and improves the efficiency. Thereafter, in the region 4 where the detachable battery pack group average voltage V1 _AVE is less than the voltage threshold V _SH , normal discharge control is performed, and discharge is performed from each battery pack.

  Each battery pack 7 has a converter 12 controlled by the BMU 13, and the current flowing through each battery pack 7 is controlled to be equal to or less than the maximum battery current. Therefore, even when a large voltage difference occurs between the battery packs 7, an excessive battery current is suppressed from flowing through each battery pack 7. In particular, the power storage system 2 according to the present embodiment is effective because the voltage difference between the battery packs 7 may increase because only a part of the battery packs 7 can be removed and charged.

  In the present embodiment, the battery packs 7 belonging to the removable battery pack group 41 are preferentially discharged by the concentrated discharge control, so that these battery packs 7 have a lower SOC than the battery packs 7 belonging to the installed battery pack group 42. It becomes easy to do. Therefore, the chargeable amount when the battery pack 7 belonging to the removable battery pack group 41 is removed and charged increases. In addition, since the SOC of the battery packs 7 belonging to the installed battery pack group 42 is maintained high, the amount of electric power moved by inter-pack charging is reduced, and the efficiency is improved.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the total number of battery packs 7, the number of battery packs belonging to the detachable battery pack group 41, and the number of battery packs 7 belonging to the installation battery pack group 42 can be arbitrarily selected.

  In the above embodiment, in each battery pack 7, the converter 12 is provided between the negative electrode of the battery 11 and the negative terminal 17. However, in another embodiment, the converter 60 is connected to the battery 11 as shown in FIG. 6. The positive electrode and the positive terminal 16 may be provided.

  As shown in FIG. 6, the converter 60 includes, in order from the negative electrode side of the battery 11, a discharging FET 21 that is a discharging contactor, an inductor 22, and a charging FET 23 that is a charging contactor. The discharging FET 21 and the charging FET 23 are P-channel MOSFETs. The source of the discharge FET 21 is connected to the positive electrode of the battery 11, and the drain is connected to the inductor 22. The charging FET 23 has a source connected to the positive terminal 16 side and a drain connected to the inductor 22. The gates of the discharging FET 21 and the charging FET 23 are connected to the BMU 13, respectively, and a signal is input from the BMU 13. The bypass line 61 has one end connected to a portion between the negative electrode of the battery 11 and the negative terminal 17, and the other end connected to the source side of the discharging FET 21 of the power line 19 via the first capacitor 26. The other end of the bypass line 61 is connected to the source side of the charging FET 23 of the power line 19 through the second capacitor 27 and connected to the drain side of the discharging FET 21 of the power line 19 through the first diode 28. The power line 19 is connected to the drain side of the charging FET 23 via the second diode 29. The first capacitor 26, the second capacitor 27, the first diode 28, and the second diode 29 are connected in parallel to each other. The first diode 28 and the second diode 29 allow a current to flow from the bypass line 61 side to the positive terminal 16 side of the power line 19.

In another embodiment, in step S2, MG_ECU 35 is the median value of the battery voltages of the first and second battery packs 7 belonging to the removable battery pack group 41 instead of the removable battery pack group average voltage V1 _AVE. The detachable battery pack group voltage median value V1 _MED and the detachable battery pack group voltage minimum value V1 which is the lowest value (lower value) of the battery voltages of the first and second battery packs 7 belonging to the detachable battery pack group 41. _It may be determined whether or not _MIN is equal to or higher than the voltage threshold V _SH . Using the detachable battery pack group voltage minimum value V1 _MIN for the determination may satisfy the determination in step S2 more than using the detachable battery pack group average voltage V1 _AVE or the detachable battery pack group voltage median value V1 _MED. Limited. That is, when the minimum battery pack group voltage V1 _MIN is used for determination, the case where inter-pack charge control is performed is limited, and the voltage drop of the first and second battery packs 7 belonging to the removable battery pack group 41 is reduced. Is suppressed, and the SOC of the first and second battery packs 7 is suppressed to zero.

In step S3, the MG_ECU 35 subtracts the installed battery pack group average voltage V2 _AVE that is the average value of the battery voltages of the third to sixth battery packs 7 belonging to the installed battery pack group 42 from the removable battery pack group average voltage V1 _AVE. In other embodiments, the voltage difference D is calculated from the median value of the battery voltage of the third to sixth battery packs 7 belonging to the installed battery pack group 42 from the median value V1 _MED of the detachable battery pack group. By subtracting the battery pack group voltage median value V2 _MED , or from the detachable battery pack group voltage minimum value V1 _MIN, it is the lowest value among the battery voltages of the third to sixth battery packs 7 belonging to the installed battery pack group 42. the voltage difference by subtracting the installed battery pack group voltage minimum value V2 _MIN It may be calculated.

  DESCRIPTION OF SYMBOLS 1 ... Electric vehicle, 2 ... Power storage system, 3 ... Electric motor, 4 ... PDU, 5 ... Charging device, 7 ... Battery pack, 8 ... Circuit, 11. Battery, 11A ... Battery cell, 12 ... Converter, 13 ... BMU (pack control unit), 14 ... Battery case, 16 ... Positive terminal, 17 ... Negative terminal, 18. ..Control terminal, 19 ... Power line, 21 ... Discharge FET, 22 ... Inductor, 23 ... Charge FET, 25 ... Bypass line, 26 ... First capacitor, 27 ... second capacitor, 28 ... first diode, 29 ... second diode, 31 ... shunt resistor, 32 ... temperature sensor, 35 ... MG_ECU (integrated control unit), 41 ... Removable battery pack group, 42 ... Installed battery pack group

Claims (5)

A plurality of battery packs each having a chargeable / dischargeable battery, a converter that changes a discharge current and a charge current of the battery, a pack control unit that detects the state of the battery and controls the converter;
A plurality of battery packs connected in parallel to each other and connected to an electrical load and a power supply source;
Based on the state of the battery, setting a command value for each discharge current and charge current of the battery pack, and having an integrated control unit that outputs the command value to the pack control unit,
The pack control unit controls the converter based on the command value when the command value is acquired,
Among the battery packs, it is assumed that at least one of the battery packs suitable for attachment / detachment from the circuit belongs to the attachment / detachment battery pack group, and other battery packs other than the attachment / detachment battery pack group belong to the installation battery pack group,
The pack control unit detects a voltage of each battery of the battery pack,
The integrated control unit acquires a required power value of the electric load, the required power value is equal to or less than a predetermined required power threshold, and an average value of the battery voltages of the battery packs belonging to the removable battery pack group Is equal to or greater than a predetermined voltage threshold value, and the average value of the battery voltage of the battery pack belonging to the stationary battery pack group is subtracted from the average value of the battery voltage of the battery pack belonging to the removable battery pack group. The pack control unit of the battery pack belonging to the detachable battery pack group when the voltage difference is greater than or equal to the first voltage difference threshold greater than 0 and less than or equal to the second voltage difference threshold greater than the first voltage difference threshold. The command value of the discharge current is set in the battery pack and the pack controller of the battery pack belonging to the installed battery pack group is charged. Power storage system and sets the command value of the current. The pack control unit detects a voltage of each battery of the battery pack,
The integrated control unit sets the command value so that a charging current of the battery pack belonging to the installed battery pack group becomes larger than a charging current of the battery pack belonging to the removable battery pack group. The power storage system according to claim 1 . Each pack control unit of each of the battery packs controls each of the converters of the battery pack so that a current flowing through each of the battery packs is lower than a preset maximum current value in preference to the command value. It controls, The electrical storage system of Claim 1 or Claim 2 characterized by the above-mentioned.   The said integrated control part sets the said command value of each discharge current and charging current of the said battery pack based on at least 1 of the temperature of the said battery, and the SOC of the said battery, The Claim 1 characterized by the above-mentioned. The electricity storage system described. The power storage system according to any one of claims 1 to 4 ,
An electric vehicle comprising: an electric motor as the electric load.

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