Power System

Abstract

To provide a power source system in which voltages in a battery assembly can be uniformized to a desired reference voltage while operation of the power source system is continued.SOLUTION: A power source system P is formed of a plurality of battery units Bu that are arranged in parallel. Each of the battery units Bu includes a battery pack 1 and a converter 2. A control device 3 controls the converter 2 in such a way that the voltage of the battery unit Bu (battery pack 1) having a voltage higher / lower than a reference voltage by a prescribed value or more is adjusted to be equal to the reference voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply system, and more particularly to a power supply system in which a plurality of battery units, each including a battery pack and a converter, are connected in parallel. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2014-103804 (Patent Document 1) discloses a technique for equalizing the voltages of a plurality of assembled batteries in a battery system in which the assembled batteries are connected in parallel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-103804 A [Patent Document 2] JP 2013-70441 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery system (power supply system) described in Patent Document 1, the battery pack with the lowest voltage is identified among multiple battery packs. Then, equalization control is performed so that the voltage of the identified (lowest voltage) battery pack is set as a reference voltage and the voltages of the other battery packs are reduced to the reference voltage. When such equalization control is adopted, the reference voltage is limited to the voltage of the battery pack with the lowest voltage.

[0005] An object of the present disclosure is to provide a power supply system that can equalize the voltages of a battery pack to a desired reference voltage while continuing to operate the power supply system. [Means for solving the problem]

[0006] (1) The power supply system disclosed herein is a power supply system that charges and discharges between an external system. The power supply system includes a battery unit including a battery pack and a converter, and a control device that controls the battery unit, and the battery units are connected in parallel. When a request for equalization control to equalize the voltages of the battery packs occurs, the control device controls the converter to perform equalization control for some of the battery packs while maintaining a state in which charging and discharging is possible between the remaining battery packs and the external system.

[0007] According to this configuration, the battery unit is composed of a battery pack and a converter. The power supply system is formed by connecting a plurality of battery units in parallel. Since the battery unit is composed of a battery pack and a converter, the voltage of the battery pack can be equalized to a desired voltage by controlling the converter (the voltage of the battery pack can be made to be the desired voltage). In addition, charging and discharging can be performed between the battery pack and an external system by controlling the converter.

[0008] When a request for equalization control for equalizing the voltages of the assembled batteries occurs, the control device controls the converter to maintain a state in which charging and discharging is possible between the remaining assembled batteries and the external system while performing equalization control for some assembled batteries. Thus, the voltages of the assembled batteries can be equalized to a desired reference voltage while continuing to operate the power supply system.

[0009] (2) Preferably, in (1), the converter is a converted three-phase inverter, and the battery packs are connected to each phase arm of the three-phase inverter. The control device has a control unit that controls the three-phase inverter. The control device may be configured to simultaneously execute equalization control of the three battery packs connected to the three-phase inverter.

[0010] According to this configuration, the converter is a repurposed three-phase inverter, and an assembled battery is connected to each phase arm of the three-phase inverter. Since an assembled battery is connected to each of the U-phase arm, V-phase arm, and W-phase arm of the three-phase inverter, a configuration is achieved in which three battery units are connected in parallel. The control device has a control unit that controls the three-phase inverter, and simultaneously executes equalization control of the three assembled batteries connected to the three-phase inverter. Since the control unit that controls the three-phase inverter simultaneously controls equalization control of the three assembled batteries connected to the three-phase inverter, the control specifications can be made relatively simple.

[0011] In recent years, electric vehicles such as hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) have become increasingly popular. It is desirable to recycle or reuse the batteries (battery packs) and power control units (PCUs) that are collected when these vehicles are replaced or dismantled. With this configuration, the reuse of PCUs can be promoted by converting the three-phase inverter of a collected PCU into a converter for a power supply system (battery unit). If the collected batteries (battery packs) are used as the battery packs for the power supply system (battery unit), the reuse of batteries can also be promoted.

[0012] In addition, an electric vehicle is equipped with a control device for controlling the PCU. This control device includes a control unit (control device) that controls the three-phase inverter of the PCU. By using the control unit (control device) that controls the three-phase inverter to control the three-phase inverter that has been converted into a converter, the control specifications can be made relatively simple. Furthermore, if the control device (control unit) that was installed in the vehicle is converted into a power supply system, it is possible to promote the reuse of the control device (control unit).

[0013] (3) Preferably, in (1) or (2), the control device may generate a request for equalization control based on the voltage or time of the battery pack.

[0014] According to this configuration, a request for equalization control is generated based on the voltages of the assembled batteries or based on time. For example, if a request for equalization control is generated when the voltage of any of the assembled batteries becomes high or when the voltage of any of the assembled batteries becomes low, it is possible to prevent the voltage difference between the assembled batteries from increasing. By generating a request for equalization control at predetermined time intervals and sequentially repeating the equalization control for each assembled battery, it is possible to prevent the voltage difference between the assembled batteries from increasing. Furthermore, the time may be the hour of the day. For example, if a request for equalization control is generated during the middle of the night, it is possible to execute the equalization control while satisfying the charge / discharge power required for the power supply system.

[0015] (4) Preferably, in (3), the control device may obtain an average voltage of the assembled batteries included in the power supply system, and target the assembled batteries that exhibit a voltage difference from the average voltage that is greater than a predetermined value for the equalization control.

[0016] According to this configuration, the equalization control is performed on battery packs that exhibit a voltage difference from the average voltage of the battery packs included in the power supply system that is greater than a predetermined value, so that a high equalization effect can be obtained for the power supply system as a whole. Effect of the Invention

[0017] According to the present disclosure, it is possible to provide a power supply system capable of equalizing the voltages of the assembled batteries to a desired reference voltage while continuing the operation of the power supply system. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing an overall configuration of a power supply system according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a diagram illustrating an example of an electric vehicle. [Diagram 3] FIG. 4 is a diagram illustrating an example of an equalization circuit included in the monitoring unit. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a control device of a power supply system. [Diagram 5]4 is a flowchart showing an example of an equalization control process executed in the control device. [Figure 6] FIG. 13 is a diagram illustrating a control device of a power supply system according to a first modified example. [Figure 7] 10 is a flowchart showing an example of equalization control executed in a control device of the first modification. [Figure 8] FIG. 11 is a diagram illustrating an example of equalization control executed by the control device in Modification 2. [Figure 9] FIG. 13 is a diagram showing an overall configuration of a power supply system in a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0020] Fig. 1 is a diagram showing the overall configuration of a power supply system P of this embodiment. The power supply system P includes a power supply subunit Su including three battery packs 1 and a converter 2, and a control device 3. In this embodiment, the power supply subunit Su is a battery pack and a PCU mounted on an electric vehicle that are converted for use in the power supply system P. An example of the configuration of an electric vehicle equipped with a battery pack and a PCU will be described with reference to Fig. 2.

[0021] Fig. 2 is a diagram illustrating an example of an electric vehicle. In Fig. 2, the electric vehicle V is a hybrid vehicle that uses both a rotating electric machine and an engine to drive the vehicle. The electric vehicle V includes a battery pack 1, a PCU 20, an engine 30, motor generators MG1 and MG2 as rotating electric machines, a power split mechanism 40, and drive wheels 50.

[0022] The battery pack 1 includes a battery 10 and a system main relay (SMR) 11. The battery 10 is an assembled battery in which single cells (battery cells) made of secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries are electrically connected in series. The output terminals (positive terminal, negative terminal) of the battery pack 1 are connected to a battery connection terminal 25 of the PCU 20. When the SMR 11 is closed, the battery 10 and the PCU 20 are connected, and when the SMR 11 is opened, the connection between the battery 10 and the PCU 20 is cut off. The battery pack 1 is provided with a monitoring unit 15, which detects the voltage VB of the battery 10, the input / output current IB of the battery 10, the temperature of the battery 10, etc.

[0023] The PCU 20 includes a boost converter 21, an inverter 22, and an inverter 23. The boost converter 21 boosts the battery voltage VB input from the battery pack 1 and outputs it to the inverter 22 and the inverter 23. The inverter 22 converts the DC power boosted by the boost converter 21 into three-phase AC power, and drives the motor generator MG1 to start the engine 30, for example. The inverter 22 also converts AC power generated by the motor generator MG1 using the power transmitted from the engine 30 into DC power and returns it to the boost converter 21. At this time, the boost converter 21 is controlled to operate as a step-down circuit. The inverter 23 converts the DC power output from the boost converter 21 into three-phase AC power and outputs it to the motor generator MG2.

[0024] The power split mechanism 40 is a mechanism that is connected to the engine 30 and the motor generators MG1, MG2 and distributes power therebetween. A planetary gear mechanism can be used as the power split mechanism 40, and for example, the engine 30 is connected to a planetary carrier, the motor generator MG1 is connected to a sun gear, and the motor generator MG2 is connected to a ring gear. The rotor of the motor generator MG2 (and the rotating shaft of the ring gear of the power split mechanism 40) is connected to the drive wheels 50 via a reduction gear, a differential gear, and a drive shaft (not shown).

[0025] The boost converter 21 of the PCU 20 includes a reactor and switching elements Q1a, Q1b, Q2a, and Q2b. The switching elements Q1a to Q2b are, for example, IGBT (Insulated Gate Bipolar Transistor) elements, and include a diode connected in anti-parallel to each IGBT element. The switching elements Q1a and Q1b are provided in parallel, and the switching elements Q2a and Q2b are provided in parallel, and the switching elements Q1a and Q1b are driven by the same drive signal, and the switching elements Q2a and Q2b are driven by the same drive signal. The collectors of the switching elements Q1a and Q1b are connected to the positive electrode line Pl, and the emitters of the switching elements Q2a and Q2b are connected to the negative electrode line Nl. The reactor is connected to the emitters of the switching elements Q1a and Q1b and the collectors of the switching elements Q2a and Q2b.

[0026] Inverter 22 is a three-phase inverter and includes a U-phase arm made up of switching elements Q3 and Q4 connected in series between positive electrode line Pl and negative electrode line Nl, a V-phase arm made up of switching elements Q5 and Q6 connected in series between positive electrode line Pl and negative electrode line Nl, and a W-phase arm made up of switching elements Q7 and Q8 connected in series between positive electrode line Pl and negative electrode line Nl. Similar to switching element Q1a, switching elements Q3 to Q8 are switching elements including diodes connected in anti-parallel to IGBT elements.

[0027] The midpoint of the arm of each phase is connected to the coil of each phase of motor generator MG1 via MG1 connection terminal 26. Motor generator MG1 is a three-phase permanent magnet synchronous motor, and may be, for example, an IPM (Interior Permanent Magnet) synchronous motor.

[0028] The inverter 23 is a three-phase inverter similar to the inverter 22, except that the switching elements of the arms of each phase are arranged in parallel. Switching elements Q9a and Q9b correspond to switching element Q3, and switching elements Q10a and Q10b correspond to switching element Q4, forming a U-phase arm. Switching elements Q11a and Q11b correspond to switching element Q5, and switching elements Q12a and Q12b correspond to switching element Q6, forming a V-phase arm. Switching elements Q13a and Q13b correspond to switching element Q7, and switching elements Q14a and Q14b correspond to switching element Q8, forming a W-phase arm.

[0029] The midpoint of the arm of each phase is connected to the coil of each phase of motor generator MG2 via MG2 connection terminal 27. Motor generator MG2 may also be an IPM synchronous motor.

[0030] The PCU 20 is provided with a current sensor iu that detects a U-phase current iu of each of the inverters 22 and 23, a current sensor iv that detects a V-phase current iv, and a current sensor iw that detects a W-phase current iw. The PCU 20 also includes a voltage sensor VH that detects a system voltage VH that is a voltage supplied from the boost converter 21 to the inverters 22 and 23, and a voltage sensor VL that detects a voltage VL input from the battery pack 1 to the boost converter 21.

[0031] The electric vehicle V includes, as control devices, a hybrid ECU (Electronic Control Unit) (HV-ECU) 200, a motor generator ECU (MG-ECU) 210, a battery ECU (BT-ECU) 220, and an engine ECU (EG-ECU) 230. Each ECU includes a CPU (Central Processing Unit), a memory, and a buffer (none of which are shown).

[0032] The monitoring unit 15 includes a voltage detection circuit VB that detects the voltage (battery voltage) VB and cell voltage (single cell voltage) Vb of the battery 10, a current sensor IB that detects an input / output current IB, etc. The monitoring unit 15 also includes an equalization circuit that equalizes the voltages of the single cells (battery cells) of the battery 10, as described later. The BT-ECU 220 calculates the SOC (State Of Charge) of the battery 10 based on the voltage VB and the input / output current IB detected by the monitoring unit 15, and transmits it to the HV-ECU 200.

[0033] For travel control of electric vehicle V, HV-ECU 200 calculates required drive torque Tr based on, for example, accelerator opening, vehicle speed, etc., and multiplies required drive torque Tr by the rotation speed of drive wheels 50 to obtain required power Pd. Required power Pe required of engine 30 is set by subtracting charge / discharge power Pb (a positive value when discharging from battery 10) based on the SOC of battery 10 from required power Pd. Then, target engine rotation speed Ne, target engine torque Te, command torque Tm1 of motor generator MG1, and command torque Tm2 of motor generator MG2 are set so that required power Pe is output from engine 30 and required drive torque Tr is output to drive wheels 50.

[0034] The MG-ECU 210 performs PWM (Pulse Width Modulation) control on each switching element of the inverter 22 so that the command torque Tm1 is output from the motor generator MG1. The MG-ECU 210 also performs PWM control on each switching element of the inverter 23 so that the command torque Tm2 is output from the motor generator MG2.

[0035] The EG-ECU 230 controls the engine 30 so that the engine 30 is operated at a target engine speed Ne and a target engine torque Te.

[0036] 3 is a diagram showing an example of an equalization circuit EQ provided in the monitoring unit 15. In the battery 10, a plurality of single cells (battery cells) 101-10M are connected in series. The voltage detection circuit VB detects the voltages of the single cells 101-10M via a plurality of voltage detection lines L1, a branch line L11, and a branch line L12. The voltage detection line L1 is connected to the positive terminal of the single cell 101 and the negative terminal of the single cell 10M. In addition, the voltage detection line L1 is connected to the negative terminal of one of the single cells and the negative terminal of the other of the single cells between the single cells 101-10M.

[0037] The voltage detection line L1 is provided with a fuse F and chip beads Cb. The fuse F melts when an overcurrent occurs to protect the circuit. The chip beads Cb reduce the applied stress when a surge voltage is applied instantaneously.

[0038] A Zener diode D is connected in parallel to the cells 101-10M via a voltage detection line L1. The cathode of the Zener diode D is connected to the positive terminal side of the corresponding cell, and the anode is connected to the negative terminal side of the corresponding cell. When an overvoltage is applied from the battery 10 (cell) to the voltage detection circuit VB, a current flows through the Zener diode D, thereby protecting the voltage detection circuit VB from the overvoltage.

[0039] The voltage detection line L1 branches into a branch line L11 and a branch line L12 on the monitoring unit 15 side of the Zener diode D. The branch line L11 is connected to a comparator VBc via a switch So, and the branch line L12 is connected to the comparator VBc via a switch Sh. For example, a photo MOS (Metal Oxide Semiconductor) relay can be used for the switch So and the switch Sh. Note that the branch line L11 branched from the voltage detection line L1 connected to the positive terminal of the cell 101 arranged on the positive output terminal side of the battery 10 is not connected to the comparator VBc. In addition, the voltage detection line L1 connected to the negative terminal of the cell 10M arranged on the negative output terminal side of the battery 10 does not include the branch line L12.

[0040] A resistor R1 is provided on the branch line L12. A capacitor (flying capacitor) C is provided between the branch line L12 connected to the positive electrode terminal of each cell and the branch line L11 connected to the negative electrode terminal. In the branch line L12, the capacitor C is connected between the resistor R1 and the switch Sh, and the resistor R1 and the capacitor C form an RC low-pass filter. The capacitor C is connected in parallel with the corresponding cell 101-10M, and the electric charge of the corresponding cell 101-10M is charged to the capacitor C, and the voltage value of the capacitor C becomes equal to the voltage value of the corresponding cell 101-10M. By turning on (closing) the switch Sh and the switch So corresponding to a specific cell 101-10M, the comparator VBc outputs the voltage (cell voltage) Vb of the specific cell 101-10M. As a result, the monitoring unit 15 can detect the cell voltage Vb of each of the cells 101-10M using the voltage detection circuit VB by sequentially turning on the switches Sh and So corresponding to each of the cells 101-10M. Also, by turning on (closing) the switch Sh of the cell 101 and the switch So connected to the negative terminal of the cell 10M, the voltage VB of the battery 10 can be detected.

[0041] The equalization circuit EQ is composed of a discharge resistor Rd provided in the branch line L11 and a switch S1 that connects (closes) / disconnects (opens) adjacent branch lines L11. The switch S1 switches between ON (closed) and OFF (open) upon receiving a control signal from the BT-ECU 220. In FIG. 4, the dashed arrow indicates the flow of current when equalization control is executed to eliminate unevenness in the cell voltages Vb. This shows a case where the cell voltage Vb of the single battery 102 is higher than the cell reference voltage, and the single battery 102 is discharged to execute equalization control. When the cell voltage Vb of the single battery 102 is higher than the cell reference voltage, the switch S1 corresponding to the single battery 102 is turned ON (closed). When the switch S1 corresponding to the cell 102 is turned ON (closed), as shown by the dashed arrow, the current discharged from the cell 102 is consumed by the discharge resistors Rd, Rd, causing the cell voltage Vb of the cell 102 to drop, and cell voltage equalization is performed. In this manner, equalization is performed between the battery cells of the battery 10 (battery pack).

[0042] Referring again to FIG. 1, in the power supply system P, the battery pack 1 and the converter 2 are repurposed battery packs 1 and PCU 20 mounted on an electric vehicle V. The positive terminals of the output terminals of the three battery packs 1 (1-1-1, 1-1-2, 1-1-3) are connected to an MG2 connection terminal 27 to which the midpoints of the phase arms (U-phase arm, V-phase arm, W-phase arm) of an inverter 23 (three-phase inverter) of the PCU 20 are connected, via a coil (inductor) 5. The power line between the positive terminal of the battery pack 1 and the coil 5 is connected to the negative terminal of the output terminal of the battery pack 1, via a capacitor 6. The negative terminal of the battery pack 1 is connected to the negative line Nl of the PCU 20 by a power line Nl1. For convenience, the monitoring unit 15 is partially omitted in FIG. 1.

[0043] 1, switching elements Q4, Q5, and Q7 of inverter 22 of PCU 20 are short-circuited. In MG1 connection terminal 26 to which the midpoints of the arms of each phase of inverter 22 are connected, a terminal to which the U-phase arm is connected is connected to the negative terminal of battery connection terminal 25 by power line Nl2. The negative terminal of battery connection terminal 25 is connected to negative terminal 28b of power supply subunit Su. In MG1 connection terminal 26, a terminal to which the V-phase arm and W-phase arm are connected is connected to positive terminal 28a of power supply subunit Su by power line Pl1.

[0044] In this way, by connecting each phase arm of the inverter 23 of the PCU 20 to the battery pack 1, shorting some of the switching elements of the inverter 22, and connecting the MG1 connection terminal 26 to the positive terminal 28a and negative terminal 28b of the power supply subunit Su, the PCU 20 is converted into a converter 2 that controls the voltage of the battery pack 1 (battery 10) connected to each phase arm of the inverter 23.

[0045] In FIG. 1, the battery pack 1 or the battery 10 included in the battery pack 1 corresponds to an example of the "battery pack" of the present disclosure. A chopper circuit consisting of each phase arm, a coil 5, and a capacitor 6 corresponding to one battery pack 1 (connected to one battery pack 1) corresponds to the "converter" of the present disclosure. In FIG. 1, for convenience, three converters are collectively labeled with the reference symbol 2. A configuration including the battery pack 1 and one converter 2 corresponds to the "battery unit" of the present disclosure. For example, in FIG. 1, the battery pack 1-1-1, the U-phase arm (switching elements Q9a, Q9b, Q10a, Q10b), the coil 5 connected to the midpoint of the U-phase arm, and the capacitor 6 provided in the power line between the positive terminal of the battery pack 1-1-1 and the coil 5 correspond to the "battery unit" of the present disclosure. In the description of the present embodiment, the battery units are denoted by the reference symbol Bu without distinguishing between the battery units.

[0046] The power supply subunit Su is composed of three battery units Bu including a converter 2 that is a repurposed PCU 20. In the power supply subunit Su, the battery units Bu are connected in parallel. The power supply system P includes a plurality of power supply subunits Su, and each power supply subunit Su is connected in parallel to the PCS 100. In this embodiment, the power supply subunit Su includes n (n is a positive integer) power supply subunits Su, and may include, for example, 20 power supply subunits Su. Three battery units Bu (battery packs 1) are connected in parallel to the power supply subunit Su, and in the power supply system P including 20 power supply subunits Su, 60 battery units Bu (battery packs 1) are connected in parallel. In FIG. 1, n in the symbol Su-n indicates that it is the n-th power supply subunit Su. n in the symbols 1-n-1, 1-n-2, and 1-n-3 indicates the battery pack 1 included in the n-th power supply subunit Su.

[0047] The positive terminal 28a of each power supply subunit Su is connected via a positive line PL to an input / output terminal of the PCS 100. The negative terminal 28b of each power supply subunit Su is connected via a negative line NL to an input / output terminal of the PCS 100.

[0048] The PCS100 is connected to a power system P, a power grid PG, a photovoltaic power generation device 650, and a load (electrical load) 300. The power system PG is, for example, a commercial power source formed from a power plant or a power transmission network. The PCS100 includes a power conversion device, and supplies power generated by the photovoltaic power generation device 650 to the load 300 and performs reverse power flow. The PCS100 converts AC power of the power system PG to DC power and charges the power system P (battery unit Bu). The PCS100 converts discharge power (output power) of the power system P (battery unit Bu) to AC power and supplies it to the load 300 and performs reverse power flow. The load 300 may be a household load (home appliance) or an electrical load in an office or factory.

[0049] The power supply system P performs interconnected operation in which it receives and transmits power to and from the power grid PG, and independent operation in which it is disconnected (cut off) from the power grid PG. During interconnected operation, power is mainly supplied to the load 300 from the power grid PG. During interconnected operation, the power supply system P receives and transmits power to and from the power grid PG in response to a request for lowering DR or raising DR. During independent operation of the power supply system P, the output power (discharge power) of the power supply system P (battery unit Bu) is supplied to the load 300.

[0050] 4 is a diagram showing an example of the configuration of the control device 3 of the power supply system P. The control device 3 includes a control ECU 400 and a drive ECU 450. Each ECU includes a CPU, a memory, and a buffer (none of which are shown). The PCS-ECU 500 is a control device that controls the PCS 100, and outputs to the control ECU 400 a power command RP that is a required value of power output from the power supply system P (battery unit Bu) or a required value of power input to the power supply system P, and a voltage command RV that is a command value of the voltage output from the power supply system P.

[0051] The control ECU 400 controls the charging and discharging of the power supply system P (battery unit Bu). The drive ECU 450 PMW controls the battery unit Bu (converter 2) so that the charging and discharging power of the power supply system P (battery unit Bu) becomes a power command RP and the output voltage of the power supply system P becomes RV. The control ECU 400 also executes equalization control of the battery unit Bu (battery 10).

[0052] In the power supply system P configured in this manner, it is preferable to equalize (balance) the voltages of the batteries 10 among the battery units Bu (batteries 10), and it is preferable to equalize the voltages among the battery cells of the battery 10 (battery pack). In this case, it is desirable to perform the equalization while continuing to operate the power supply system P (charging and discharging the power supply system P). In this embodiment, the converter 2 of the battery unit Bu is controlled to equalize the voltages of the batteries 10 (battery units Bu) to a desired reference voltage. Also, equalization is performed among the battery cells of the battery 10 (battery units Bu).

[0053] 5 is a flowchart showing an example of the equalization control process executed by the control device 3 (control ECU 400). This flowchart is repeatedly processed at predetermined intervals during operation of the power supply system P. The predetermined period may be, for example, 1 hour, 12 hours, or 48 hours.

[0054] In step (hereinafter, step is abbreviated as "S") 10, the battery voltage VB detected by the monitoring unit 15 of each battery unit Bu is acquired. In this embodiment, since 60 battery units Bu are provided, 60 battery voltages VB are acquired. In the following S12, an average voltage VBav is calculated from the acquired 60 battery voltages VB. The average voltage VBab may be a simple average.

[0055] In S13, it is determined whether the difference (|VBav-VB|) between the average voltage VBav calculated in S12 and the battery voltage VB of each battery unit Bu (battery 10) is equal to or greater than a predetermined value α. The predetermined value α is a value that allows for tolerance of voltage variations between the battery units Bu (batteries 10), and is set in advance through experiments or the like. If the difference between the average voltage VBab and the battery voltage VB in all battery units Bu is less than the predetermined value α (|VBav-VB|<α), a negative determination is made, and the current routine is terminated.

[0056] If the difference between the average voltage VBav and the battery voltage VB in any battery unit Bu (battery 10) is equal to or greater than a predetermined value α (|VBav-VB|≧α), an affirmative determination is made in S13 and the process proceeds to S14.

[0057] In S14, it is determined whether or not to execute equalization between the battery cells of the battery 10 included in the battery unit Bu in which it has been determined that the difference between the average voltage VBav and the battery voltage VB is equal to or greater than the predetermined value α. In the following, the battery 10 included in the battery unit Bu in which it has been determined that the difference between the average voltage VBav and the battery voltage VB is equal to or greater than the predetermined value α is also referred to as the "target battery." For example, when the deviation between the maximum and minimum values ​​of the cell voltage Vb of the target battery is equal to or greater than a set value, it is determined that equalization between the battery cells of the target battery is to be executed (positive determination), and the process proceeds to S15. When the deviation between the maximum and minimum values ​​of the cell voltage Vb of the target battery is less than the set value, it is determined that equalization between the battery cells of the target battery is not necessary (negative determination), and the process proceeds to S16.

[0058] In S15, equalization control between the battery cells of the target battery is executed. For example, the converter 2 of the battery unit Bu of the target battery is stopped (the switching elements of each phase arm are turned off). Then, the average value of the cell voltage Vb calculated by excluding the maximum and minimum values ​​of the cell voltage Vb of the target battery is set as the cell reference voltage, and discharge is performed from the single battery showing a cell voltage higher than the cell reference voltage (current is consumed by the discharge resistors R1, R1), thereby executing the equalization control between the battery cells of the target battery. When the equalization control between the battery cells of the target battery is completed, the process proceeds to S16.

[0059] In S16, equalization control of the target battery (battery pack) is executed. In the equalization control, the converter 2 of the battery unit Bu of the target battery is controlled so that the battery voltage VB of the target battery becomes the average voltage VBav. For example, when the battery voltage VB is higher than the average voltage VBav, the converter 2 is controlled so that the battery unit Bu is discharged. When the battery voltage VB is lower than the average voltage BVav, the converter 2 is controlled so that the battery unit Bu (battery 10) is charged. The battery unit Bu may be charged by power supplied from the power system PG, or may be charged by power supplied from another battery unit Bu. When the battery voltage VB becomes the average voltage VBav, the battery unit Bu of the target battery is controlled so that it becomes the operation mode (charge or discharge) required by the power supply system P, and the process returns to S10. During the processing of this routine, the converter 2 of the battery unit Bu that does not include the target battery (the battery for which the processing of S14 and S13 is executed) is controlled so that it becomes the operation mode (charge or discharge) required by the power supply system P.

[0060] Returning to S10, the battery voltage VB detected by the monitoring unit 15 of each battery unit Bu is obtained again, and each step of S10 to S16 is processed. Then, when the equalization control (S16) of all the target batteries is completed, in all the battery units Bu, the difference between the average voltage VBab and the battery voltage VB becomes smaller than the predetermined value α (|VBav-VB|<α), so a negative determination is made in S13, and the current routine is terminated.

[0061] According to this embodiment, the battery unit Bu is composed of a battery 10 (battery pack) and a converter 2. A plurality of battery units Bu are connected in parallel to form a power supply system P. Since the battery unit Bu is composed of the battery 10 and the converter 2, the voltages of the batteries 10 can be equalized to a desired voltage by controlling the converter 2 (S16).

[0062] When a request for equalization control for equalizing the voltages of the batteries 10 occurs (positive determination in S13), the control device 3 controls the converter 2 to maintain a state in which charging and discharging is possible between the remaining batteries 10 (battery units Bu) and the PCS 100 while performing equalization control on some of the batteries 10 (target batteries). Therefore, the voltages of the batteries 10 can be equalized to a desired reference voltage while continuing to operate the power supply system P.

[0063] According to the above embodiment, the converter 2 of the battery unit Bu is a repurposed inverter 23 (three-phase inverter) included in the PCU 20 of the electric vehicle V. In addition, the battery pack 1 of the electric vehicle V is used as the battery pack 1 of the battery unit Bu. This makes it possible to promote the reuse of batteries and PCUs that are collected when the electric vehicle V is replaced or dismantled.

[0064] (Variation 1) Fig. 6 is a diagram illustrating a control device 3a of a power supply system P according to the first modification. The control device 3a of the first modification utilizes an HV-ECU 200, an MG-ECU 210, and a BT-ECU 220 mounted on an electric vehicle V. In Fig. 6, an H / HV-ECU 220a, and HV-ECU(1) 220a-1 to HV-ECU(3) 220a-3 utilize the HV-ECU 200 mounted on the electric vehicle V. The MG-ECU 210a utilizes the MG-ECU 210. The BT-ECU 220a1 to BT-ECU 220a-3 utilize the BT-ECU 220.

[0065] The interface ECU (I / F-ECU) 600 connects the PCS-ECU 500 and the control device 3a (H / HV-ECU 200a) and performs consistency between the communication protocol of the PCS-ECU 500 and the communication protocol of the control device 3a. The H / HV-ECU 200a calculates the power command RP for each battery unit Bu from the power command RP, voltage command RV, etc. received from the PCS-ECU 500 via the I / F-ECU 600. The H / HV-ECU 200a also outputs a command for equalization control of the battery units Bu (batteries 10).

[0066] The sub-control device 3a1, which is composed of the MG-ECU 210a, the HV-ECU(1) 220a-1 to the HV-ECU(3) 220a-3, and the BT-ECU 220a1 to the BT-ECU 220a-3, is a control device that controls the power supply subunit Su. In Fig. 6, the sub-control device 3a1-1 is a control device that controls the power supply subunit Su-1 in Fig. 1, and a sub-control device 3a1 is provided for each power supply subunit Su. In other words, the control device 3a has n sub-control devices 3a1, namely, the sub-control device 3a1-1 to the sub-control device 3a1-n.

[0067] The BT-ECU(1) 220a-1 monitors the voltage VB, input / output current IB, temperature, etc. of the battery 10 of the battery pack 1-1-1 of the power supply subunit Su-1, and performs equalization control between the battery cells. The HV-ECU(1) 200a-1 performs opening and closing control of the SMR 11 of the battery pack 1-1-1 based on the power command RP and the voltage command RV. The HV-ECU 200(1)a-1 also detects the degree of deterioration of the battery 10 of the battery pack 1-1-1. The BT-ECU(2) 220a-2 and the HV-ECU(2) 200a-2 perform the same processing as the BT-ECU(1) 220a-1 and the HV-ECU(1) 200a-1 for the battery pack 1-1-2. The BT-ECU(3) 220a-3 and the HV-ECU(3) 200a-3 perform the same processing as the BT-ECU(1) 220a-1 and the HV-ECU(1) 200a-1 for the battery pack 1-1-3. The MG-ECU 210a controls the converter 2 (drives the switching elements of the phase arms of the inverter 23) based on the voltage command RV, the power command RP, etc., or based on an equalization control command from the H / HV-ECU 200a.

[0068] Sub-controllers 3a1-2 to 3a1-n also perform the same processing as sub-controller 3a1-1 with respect to power supply subunits Su-2 to Su-n.

[0069] Fig. 7 is a flowchart showing an example of equalization control executed in the control device 3a of Modification 1. This flowchart is repeatedly processed at predetermined intervals while the power supply system P is in operation, similar to the flowchart of Fig. 5.

[0070] 7, steps S10 to S13 are the same as those in the flowchart of FIG 5, and are processed, for example, by the H / HV-ECU 200a. If a positive determination is made in S13, the H / HV-ECU 200a outputs an equalization control command to the sub-control device 3a1 that controls the power supply subunit Su including the battery unit Bu that has been determined to have a difference between the average voltage VBav and the battery voltage VB equal to or greater than the predetermined value α (S20).

[0071] In addition, in S20, the MG-ECU 210a of the sub-control device 3a1 that has received the command for equalization control controls the converter 2 (each phase arm of the inverter 23) of the power supply subunit Su so that the battery voltage Vb of the three battery units Bu (batteries 10) included in the power supply subunit Su becomes the average voltage VBav. Then, when the battery voltage VB of the three battery units Bu included in the power supply subunit Su becomes the average voltage VBav, the power supply subunit Su-n is controlled so as to be in the operation mode (charge or discharge) required by the power supply system P, and the process returns to S10. Note that while this routine is being processed, the converter 2 of the power supply subunit Su for which the equalization control process is not being performed is controlled so as to be in the operation mode (charge or discharge) required by the power supply system P.

[0072] According to this modification 1, the control device 3a has a sub-control device 3a1 (MG-ECU 210a) that controls the inverter 23 (three-phase inverter). Then, equalization control is simultaneously performed on the three batteries 10 connected to the inverter 23. Since the sub-control device 3a1 that controls the inverter 23 simultaneously controls the equalization control on the three batteries 10 connected to the inverter 23, the control specifications can be relatively simple. Furthermore, since the equalization control is simultaneously performed on the three batteries 10 (battery units Bu), the time required for the equalization control can be shortened.

[0073] According to this modification 1, it is possible to promote the utilization of the hardware of the HV-ECU 200, the MG-ECU 210, and the BT-ECU 220 mounted on the electric vehicle V as the control device of the power supply system P. In addition, it is possible to utilize the resources of the CAN (Controller Area Network) communication used by the HV-ECU 200, the MG-ECU 210, the BT-ECU 220, etc. mounted on the electric vehicle V, and it is possible to relatively easily execute highly reliable communication and monitoring of multiple systems.

[0074] (Variation 2) In the first modification, when a battery unit Bu is found to have a difference between the average voltage VBav and the battery voltage VB equal to or greater than a predetermined value α, the equalization control is simultaneously performed on the three battery units Bu (batteries 10) included in the power supply subunit Su. In the second modification, the equalization control is performed regardless of the difference between the average voltage VBav and the battery voltage VB.

[0075] The control device 3a of the second modification is similar to the control device 3a of the first modification. FIG. 8 is a diagram showing an example of equalization control executed by the control device 3a in the second modification. This flowchart starts at a predetermined time. The predetermined time may be, for example, midnight. When the time reaches midnight, in S30, the H / HV-ECU 200a increments the counter C and sets the incremented counter C to n. The initial value of the counter C is 0, and when S30 is processed for the first time, n is set to 1.

[0076] In the next step S31, the H / HV-ECU 200a outputs an equalization control command to the sub-control device 3a1-n. n is a value set in S30, and the same applies in the following description of the second modification. In addition, in S31, the MG-ECU 210a of the sub-control device 3a1-n that has received the equalization control command controls the converter 2 (each phase arm of the inverter 23) of the power supply subunit Su-n so that the battery voltage Vb of the three battery units Bu (batteries 10) included in the power supply subunit Su-n becomes the reference voltage VBbe. Then, when the battery voltage VB of the three battery units Bu included in the power supply subunit Su-n becomes the reference voltage VBbe, the power supply subunit Su-n is controlled so that the operation mode (charging or discharging) required for the power supply system P is set, and the process proceeds to S33. The reference voltage VBbe may be a value that is set in advance depending on the specifications of the power supply system P or the power supply subunit Su-n, the type of the battery (battery 10), or the like, or may be the average voltage VBav described above. In addition, in the power supply sub-units Su for which the equalization control process is not being performed, the converters 2 are controlled so as to be in an operation mode (charging or discharging) required by the power supply system P.

[0077] In S33, H / HV-ECU 200a determines whether n is 20 or greater. If n is less than 20 (n<20), a negative determination is made and the process proceeds to S34, where counter C is set to n, and the current routine is terminated. If n is 20 or greater (n≧20), a positive determination is made and the process proceeds to S35, where counter C is set to 0, and the current routine is terminated. Note that while this routine is being processed, the converter 2 of the power supply subunit Su for which the equalization control process is not being performed is controlled so as to be in the operation mode (charging or discharging) required by power supply system P.

[0078] According to this modification 2, the voltage equalization of the battery units Bu (batteries 10) included in the power source subunit Su is periodically, sequentially, and repeatedly performed, so that the voltage difference between the battery units Bu (batteries 10) can be prevented from increasing. Furthermore, since the equalization control is performed during the night hours when the power consumption of the load 300 is small, the power required for the power source system P can be reliably secured even if the unit (three battery units Bu) of the power source subunit Su is simultaneously equalized. Furthermore, as in the modification 1, the sub-control device 3a1 that controls the inverter 23 simultaneously controls the equalization control of the three batteries 10 connected to the inverter 23, so that the control specifications can be relatively simple. Furthermore, since the three batteries 10 (battery units Bu) are simultaneously equalized, the time required for the equalization control can be shortened.

[0079] (Variation 3) 9 is a diagram showing an overall configuration of power supply system Pa in Modification 3. In the above embodiment, an example has been described in which PCU 20 including boost converter 21, inverter 22, and inverter 23 is diverted to converter 2 of power supply system P. In the above embodiment, in particular, inverter 23 having switching elements provided in parallel is used as the switching element of converter 2 in order to enable the passage of large power. However, some PCUs mounted on electric vehicles are provided with one inverter, and some PCUs are not provided with a boost converter.

[0080] The power supply system Pa in the third modification is a PCU equipped with only one inverter, or a circuit in which the inverter portion is extracted from the PCU, and used as the converter 2A of the power supply system Pa.

[0081] In FIG. 9, the converter 2A is a repurposed inverter (three-phase inverter) of a PCU mounted on an electric vehicle. In FIG. 9, SR1 and SR2 of the battery pack 1 are system main relays (SMR). As in the above embodiment, the positive terminals of the output terminals of the three battery packs 1 (1-1-1, 1-1-2, 1-1-3) are connected to the midpoints of the phase arms (U-phase arm 2A1, V-phase arm 2A2, W-phase arm 2A3) of the three-phase inverter of the PCU via coils (inductors) 5. The power line between the positive terminal of the battery pack 1 and the coil 5 is connected to the negative terminal of the output terminal of the battery pack 1 via a capacitor 6. The upper arms of the phase arms (U-phase arm 2A1, V-phase arm 2A2, W-phase arm 2A3) of the three-phase inverter are connected to a positive line PL and are connected to the input / output terminals of the PCS 100. The lower arms of each phase arm (U-phase arm 2A1, V-phase arm 2A2, W-phase arm 2A3) of the three-phase inverter are connected to a negative line NL and connected to an input / output terminal of the PCS 100. The negative terminal of the battery pack 1 is connected to the negative line NL. Note that the monitoring unit 15 is not shown in the figure.

[0082] Thus, in the power supply system Pa in the third modification, each phase arm of the three-phase inverter of the PCU is connected to the battery pack 1, and the three-phase inverter is converted into a converter 2A to form a power supply subunit Sua having three battery units Bu. As in the above embodiment, the power supply system Pa includes a plurality of power supply subunits Sua, which are connected in parallel. In the third modification, the control device 3b executes equalization control similar to that in the above embodiment, thereby achieving the same effects as in the above embodiment.

[0083] In the above embodiment and modification, a power supply system in which a three-phase inverter is converted into a converter has been described. However, the converter constituting the battery unit Bu does not have to be a three-phase inverter, and each battery unit Bu may be provided with an independent chopper circuit (converter). Also, a four-phase inverter may be converted into a converter. In this case, in modification 1 and modification 2, the four battery units (batteries) connected to each phase arm of the four-phase inverter may be simultaneously controlled to be equalized.

[0084] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0085] 1 battery pack, 2,2A converter, 3,3a,3b control device, 5 coil (inductor), 6 capacitor, 10 battery, 11 SMR, 15 monitoring unit, 20 PCU, 21 boost converter, 22,23 inverter, 25 battery connection terminal, 26 MG1 connection terminal, 27 MG2 connection terminal, 28a positive terminal, 28b negative terminal, 30 engine, 40 power split mechanism, 50 drive wheel, 100 PCS, 200 HV-ECU, 210 MEG-ECU, 220 BT-ECU 230 EG-ECU, 300 load, 400 control ECU, 450 drive ECU, 500 PCS-ECU, 600 I / F-ECU, 650 solar power generation device, Bu battery unit, MG1 motor generator, MG2 motor generator, Su,Sua power supply sub-unit, P,Pa Power supply system, PG power system, V electric vehicle.

Claims

1. A power supply system that charges and discharges between an external system, a battery unit including a battery pack and a converter; A control device that controls the battery unit, A plurality of the battery units are connected in parallel, When a request for equalization control for equalizing the voltages of the assembled batteries occurs, the control device performs the equalization control for a portion of the assembled batteries while controlling the converter to maintain a state in which charging and discharging is possible between the remaining assembled batteries and the external system.

2. the converter is a converted three-phase inverter, and the battery pack is connected to each phase arm of the three-phase inverter; The control device has a control unit that controls the three-phase inverter, The power supply system according to claim 1 , wherein the control device simultaneously executes the equalization control of three of the assembled batteries connected to the three-phase inverter.

3. 3. The power supply system according to claim 1, wherein the control device generates the request for the equalization control based on a voltage or time of the assembled battery.

4. 4. The power supply system according to claim 3, wherein the control device determines an average voltage of the assembled batteries included in the power supply system, and targets the assembled batteries that exhibit a voltage that differs from the average voltage by a predetermined value.

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