Power System

Abstract

To provide an electrical power system in which multiple battery units including batteries and converters are connected in parallel capable of equalizing the load on each battery unit.SOLUTION: A electrical power system P consists of multiple battery units Bu connected in parallel. The battery unit Bu includes a battery pack 1 and a converter 2. A control unit 3 is configured to control the feedback by proportional control only so that the unit output voltage, which is the output voltage of the battery unit Bu, is the voltage command input by the PCS 100.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 and a converter, are connected in parallel. [Background technology]

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

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-103804 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-154692 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-186405 [Patent Document 4] International Publication No. 2017 / 163508 Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery system (power supply system) in which multiple battery packs (batteries) are connected in parallel, differences in the voltage of each battery occur due to differences in the characteristics and deterioration of each battery, which generates circulating current. One possible solution is to provide a converter for each battery connected in parallel to suppress the circulating current and battery deterioration caused by the circulating current.

[0005] In a power supply system in which battery units, each including a battery and a converter, are connected in parallel, it is desirable to control the output voltage and output power of the power supply system to desired values. For example, the converter of each battery unit is controlled based on a voltage command and a power command required by a load or the like connected to the power supply system. In this case, it is conceivable to perform voltage control in a certain battery unit so that the output voltage of the power supply system matches the voltage command, and perform power control in other battery units so that the output power of the power supply system matches the power command.

[0006] When a difference occurs between the output power and the power command in power control (power deviation occurs) due to errors in various sensors, control response delays, etc., the output voltage fluctuates. Since voltage control is executed in response to the output voltage fluctuation caused by the power deviation, the operation amount of the battery unit executing voltage control increases, which increases the load (power burden) on the specified battery unit (the battery unit on which voltage control is executed), and this may accelerate the deterioration of the specified battery unit.

[0007] An object of the present disclosure is to equalize the load (burden) on each battery unit in a power supply system in which a plurality of battery units, each including a battery and a converter, are connected in parallel. [Means for solving the problem]

[0008] (1) The power supply system of the present disclosure is a power supply system in which multiple battery units, each including a battery and a converter, are connected in parallel. The power supply system includes a control device that controls the converters. The control device executes voltage control to control each of the converters using a voltage command RV, which is a command value for the output voltage of the power supply system, as an input parameter.

[0009] With this configuration, each converter of the parallel-connected battery units is voltage-controlled using the voltage command RV as an input parameter. Even if a power discrepancy occurs, voltage control is performed on each battery unit, so the load (power burden) of each battery unit can be equalized.

[0010] (2) Preferably, in (1), the power supply system further includes a voltage sensor for detecting a unit output voltage VO(N) that is an output voltage of the battery unit. The voltage control performed by the control device may be feedback control using only proportional control so that the unit output voltage VO(N) becomes the voltage command RV.

[0011] When feedback controlling each of multiple parallel-connected battery units so that the unit output voltage VO(N) matches the voltage command RV, including an integral term (integral control) can lead to control interference between the battery units because the integral term controls the output power (output current) of each battery unit to eliminate steady-state deviation. With this configuration, feedback control is performed using only proportional control so that the unit output voltage VO(N) matches the voltage command RV, thereby suppressing control interference between the battery units.

[0012] (3) In (2), it is preferable to set the gain of the proportional control so that the fluctuation of the unit output voltage VO(N) falls within a predetermined range.

[0013] If feedback control is performed using only proportional control to make the unit output voltage VO(N) coincide with the voltage command, it is difficult for the unit output voltage VO(N) to converge to the voltage command RV because an integral term (integral control) is not included. If the gain of proportional control is increased so that the unit output voltage VO(N) approaches the voltage command RV, the unit output voltage VO(N) will fluctuate significantly. With this configuration, the gain of proportional control is set so that the fluctuation of the unit output voltage VO(N) falls within a predetermined range, making it possible to keep the fluctuation of the unit output voltage VO(N) within the tolerance range of the load, etc., while making the unit output voltage VO(N) approach the voltage command.

[0014] (4) Preferably, in (1), the power supply system further includes a voltage sensor for detecting a unit output voltage VO(N) that is the output voltage of the battery unit, and an output power acquisition unit for acquiring a unit output power OP(N) that is the output power of the battery unit. The control device includes a power command calculation unit for calculating a unit power command TP(N) that is a command value for the unit output power OP(N) based on a power command RP that is a command value for the output power of the power supply system, and a voltage command correction unit for correcting the voltage command RV so that it becomes smaller as the deviation between the unit power command TP(N) and the unit output power OP(N) increases when the unit output power OP(N) is greater than the unit power command TP(N), and correcting the voltage command RV so that it becomes larger as the deviation between the unit power command TP(N) and the unit output power OP(N) increases when the unit output power OP(N) is smaller than the unit power command TP(N), thereby obtaining a corrected voltage command RV(N). The voltage control performed by the control device may be feedback control so that the unit output voltage VO(N) becomes the corrected voltage command RV(N).

[0015] When voltage control is performed in each battery unit to equalize the load (burden) of each battery unit, control interference may occur between the battery units. According to this configuration, when the unit output power OP(N) is greater than the unit power command TP(N), the voltage command correction unit calculates a corrected voltage command RV(N) in which the voltage command RV is corrected so that it decreases as the deviation between the unit power command TP(N) and the unit output power OP(N) increases. Also, when the unit output power OP(N) is smaller than the unit power command TP(N), the voltage command correction unit calculates a corrected voltage command RV(N) in which the voltage command RV is corrected so that it increases as the deviation between the unit power command TP(N) and the unit output power OP(N) increases. Then, feedback control is performed so that the unit output voltage VO(N) becomes the corrected voltage command RV(N), and when the unit output power OP(N) is greater than the unit power command TP(N), the unit output voltage VO(N) of the battery unit is controlled to become smaller, and when the unit output power OP(N) is smaller than the unit power command TP(N), the unit output voltage VO(N) of the battery unit is controlled to become larger, thereby suppressing control interference between the battery units.

[0016] (5) Preferably, in (4), the voltage command corrector may set the voltage command RV to the corrected voltage command RV(N) when the unit output power OP(N) and the unit power command TP(N) are equal.

[0017] According to this configuration, when the unit output power OP(N) and the unit power command TP(N) are equal, the voltage command RV is not corrected and is set to the corrected voltage command RV(N), so that the output voltage of the power supply system can be controlled to the voltage command RV.

[0018] (6) Preferably, in (5), the voltage command corrector may determine the corrected voltage command RV(N) so that the relationship between the deviation and the corrected voltage command RV(N) is linear.

[0019] According to this configuration, the relationship between the deviation between the unit power command TP(N) and the unit output power OP(N) and the corrected voltage command RV(N) is linear, so the unit output voltage VO(N) can be stably controlled.

[0020] (7) Preferably, in any of (1) to (6), the converter is a converted three-phase inverter, and a battery may be connected to each phase arm of the three-phase inverter.

[0021] In recent years, electric vehicles such as hybrid electric vehicles (HEVs: Hybrid Electric Vehicles) and battery electric vehicles (BEVs: Battery Electric Vehicles) have become increasingly popular. It is desirable to recycle or reuse the batteries and power control units (PCUs) collected when these vehicles are replaced or dismantled. This configuration promotes the reuse of PCUs by converting the three-phase inverter of a collected PCU into a converter for a power supply system (battery unit). Furthermore, if collected batteries are used as batteries for the power supply system (battery unit), the reuse of batteries can also be promoted. [Effects of the Invention]

[0022] According to the present disclosure, in a power supply system in which a plurality of battery units, each including a battery and a converter, are connected in parallel, it is possible to equalize the load (burden) on each battery unit. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram showing the overall configuration of a power supply system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram illustrating an example of an electric vehicle. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a control device of a power supply system. [Figure 4] 2 is an example of a block diagram for controlling output power of the power supply system in the first embodiment. [Figure 5] 10 is an example of a block diagram for controlling output power of a power supply system in the second embodiment. [Figure 6] 5A and 5B are diagrams illustrating corrected voltage commands calculated by a voltage command corrector. [Figure 7] FIG. 10 is a diagram illustrating a control device of a power supply system according to a first modification. [Figure 8] FIG. 10 is a diagram showing the overall configuration of a power supply system according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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 numerals, and description thereof will not be repeated.

[0025] 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 (Power Control Unit) mounted on an electric vehicle that have been repurposed for use in the power supply system P. An example of the configuration of an electric vehicle equipped with battery packs and a PCU will be described.

[0026] 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 device 40, and drive wheels 50.

[0027] 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 or 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 interrupted. 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.

[0028] PCU 20 includes a boost converter 21, an inverter 22, and an inverter 23. Boost converter 21 boosts battery voltage VB input from battery pack 1 and outputs the boosted voltage to inverter 22 and inverter 23. Inverter 22 converts the DC power boosted by boost converter 21 into three-phase AC power and drives motor generator MG1 to start engine 30, for example. Inverter 22 also converts AC power generated by motor generator MG1 using power transmitted from engine 30 into DC power and returns the DC power to boost converter 21. At this time, boost converter 21 is controlled to operate as a step-down circuit. Inverter 23 converts the DC power output from boost converter 21 into three-phase AC power and outputs it to motor generator MG2.

[0029] Power split mechanism 40 is a mechanism that is connected to engine 30 and motor generators MG1 and MG2 and distributes power between them. A planetary gear mechanism can be used as power split mechanism 40, and for example, engine 30 is connected to a planetary carrier, motor generator MG1 is connected to a sun gear, and motor generator MG2 is connected to a ring gear. The rotor of motor generator MG2 (and the rotating shaft of the ring gear of power split mechanism 40) is connected to drive wheels 50 via a reduction gear, a differential gear, and a drive shaft (not shown).

[0030] 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. 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 a positive electrode line P1, and the emitters of the switching elements Q2a and Q2b are connected to a negative electrode line N1. The reactor is connected to the emitters of the switching elements Q1a and Q1b and the collectors of the switching elements Q2a and Q2b.

[0031] 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 P1 and negative electrode line N1, a V-phase arm made up of switching elements Q5 and Q6 connected in series between positive electrode line P1 and negative electrode line N1, and a W-phase arm made up of switching elements Q7 and Q8 connected in series between positive electrode line P1 and negative electrode line N1. Similar to switching element Q1a, switching elements Q3 to Q8 are switching elements including diodes connected in anti-parallel to IGBT elements.

[0032] 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.

[0033] Inverter 23 is a three-phase inverter similar to 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] The monitoring unit 15 includes a voltage sensor VB that detects the voltage VB of the battery 10, a current sensor IB that detects the input / output current IB, etc. 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 the SOC to the HV-ECU 200.

[0038] For driving 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 determine 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 for motor generator MG1, and command torque Tm2 for 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.

[0039] MG-ECU 210 performs PWM (Pulse Width Modulation) control on each switching element of inverter 22 so that motor generator MG1 outputs command torque Tm1. MG-ECU 210 also performs PWM (Pulse Width Modulation) control on each switching element of inverter 23 so that motor generator MG2 outputs command torque Tm2.

[0040] The EG-ECU 230 controls the engine 30 so that the engine 30 is operated at a target engine rotation speed Ne and a target engine torque Te.

[0041] Referring to FIG. 1, in the power supply system P, the battery pack 1 and the converter 2 are repurposed versions of the battery pack 1 and PCU 20 mounted on an electric vehicle V. The positive terminals of the output terminals of three battery packs 1 (1-1-1, 1-1-2, 1-1-3) are connected via a coil (inductor) 5 to an MG2 connection terminal 27 to which is connected an intermediate point of each phase arm (U-phase arm, V-phase arm, W-phase arm) of an inverter 23 (three-phase inverter) of the PCU 20. 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 a negative line Nl of the PCU 20 by a power line Nl1. Note that the monitoring unit 15 is not shown in FIG. 1.

[0042] 1, switching elements Q4, Q5, and Q7 of inverter 22 of PCU 20 are short-circuited. At MG1 connection terminal 26, to which the midpoints of the phase arms of inverter 22 are connected, the terminal to which the U-phase arm is connected is connected by power line Nl2 to the negative terminal of battery connection terminal 25. The negative terminal of battery connection terminal 25 is connected to negative terminal 28b of power supply subunit Su. At MG1 connection terminal 26, the terminal to which the V-phase arm and W-phase arm are connected is connected by power line Pl1 to positive terminal 28a of power supply subunit Su.

[0043] 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 boosts the voltage of the battery pack 1 (battery 10) connected to each phase arm of the inverter 23.

[0044] In FIG. 1, battery pack 1 corresponds to an example of a "battery" in the present disclosure. A chopper circuit consisting of each phase arm, coil 5, and capacitor 6 corresponding to one battery pack 1 (connected to one battery pack 1) corresponds to a "converter" in the present disclosure. Note that in FIG. 1, for convenience, three converters are collectively designated by the reference numeral 2. A configuration including battery pack 1 and one converter 2 corresponds to a "battery unit" in the present disclosure. For example, in FIG. 1, battery pack 1-1-1, U-phase arm (switching elements Q9a, Q9b, Q10a, Q10b), coil 5 connected to the midpoint of the U-phase arm, and capacitor 6 provided in the power line between the positive terminal of battery pack 1-1-1 and coil 5 correspond to a "battery unit" in the present disclosure. Note that in the description of this embodiment, the battery units are referred to as "Battery Units" without distinction between them.

[0045] 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, 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 a power supply system P including 20 power supply subunits Su, 60 battery units Bu (battery packs 1) are connected in parallel. In FIG. 1, the n in the symbol Su-n indicates the nth power supply subunit Su. The n in the symbols 1-n-1, 1-n-2, and 1-n-3 indicates the battery pack 1 included in the nth power supply subunit Su.

[0046] 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.

[0047] In addition to the power supply system P, the PCS100 is connected to a power grid PG, a photovoltaic power generation device 650, and a load (electrical load) 300. The power grid 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. When an upward DR is requested, the PCS100 converts AC power from the power grid PG into DC power and charges the power supply system P (battery unit Bu). When a downward DR is requested, the PCS100 converts the discharge power (output power) of the power supply system P (battery unit Bu) into AC power and performs reverse power flow. The load 300 may be a household load (home appliance) or an electrical load in a business or factory.

[0048] The power supply system P performs grid-connected operation, in which it exchanges power with the power grid PG, and independent operation, in which it is disconnected (shut off) from the power grid PG. During grid-connected operation, power is supplied to the load 300 mainly from the power grid PG. During grid-connected operation, the power supply system P exchanges power with 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.

[0049] 3 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 for power output from the power supply system P (battery unit Bu) or a required value for power input to the power supply system P, and a voltage command RV that is a command value for voltage output from the power supply system P.

[0050] When power is output from the power supply system P (when discharging from the battery unit Bu), the control ECU 400 generates a power command TP based on a power command RP and a voltage command RV. The drive ECU 450 controls the battery unit (converter 2) to P so that the output power of the power supply system P (battery unit Bu) becomes the power command TP. W.M. Control.

[0051] (Embodiment 1) FIG. 4 is an example of a block diagram for controlling the output power of power supply system P in the first embodiment. This block diagram may be configured as software and / or hardware in control ECU 400 and drive ECU 450. In FIG. 4, a voltage command RV and a power command RP are input from PCS-ECU 500. Voltage command RV is a required value (target voltage) of the output voltage of power supply system P, and may be, for example, 100 V, 200 V, or 600 V. Furthermore, power command RP may be power required by (to be supplied to) a load or the like connected to PCS 100.

[0052] For example, if voltage control is performed in a specific battery unit Bu so that the output voltage VP of the power supply system P matches the voltage command RV, and power control is performed in other battery units Bu so that the output power OP of the power supply system P matches the power command RP, a difference will occur between the output power OP and the power command RP (a power deviation will occur) due to errors in the current sensors or response delays in the power control, causing the output voltage VP to fluctuate. Since voltage control is performed in response to this fluctuation in output voltage VP, the operating amount of the specific battery unit Bu that is performing voltage control will increase, increasing the load (burden) on that battery unit Bu and possibly accelerating the deterioration of that battery unit Bu (or the battery pack 1 included therein). For this reason, in the first embodiment, voltage control is performed in all battery units Bu to equalize the load (burden) on each battery unit Bu (battery pack 1).

[0053] In the first embodiment, voltage control is performed in all battery units Bu without using the power command RP input from the PCS 100. The block diagram in Fig. 4 shows a block diagram in which the converter is PWM controlled for each battery unit Bu. Since the block diagram for each battery unit Bu is common, only the battery unit Bu including the battery pack 1-1-1 will be described.

[0054] The voltage command RV input from PCS-ECU 500 and the unit output voltage VO(1-1-1), which is the output voltage of battery unit Bu, are input to subtraction point 301, and the deviation ΔRV between the voltage command RV and the unit output voltage VO(1-1-1) is output from subtraction point 301 to P controller 302. The unit output voltage VO(1-1-1) may be the detection value of a voltage sensor VH that detects a system voltage VH and is provided in PCU 20 diverted to power supply subunit Su-1. In this case, the voltage sensor VH corresponds to an example of the "voltage sensor that detects the unit voltage" of the present disclosure.

[0055] The P controller 302 performs feedback control using only proportional control, and for example, multiplies the deviation ΔRV by a proportional constant (proportional gain) Kp to output an IL command. The IL command is a current command to be output from the battery unit Bu.

[0056] The IL command output from the P controller 302 and IL(1-1-1), which is the output current of the battery unit Bu, are input to a subtraction point 303, and the deviation ΔIL between the IL command and IL(1-1-1) is output from the subtraction point 303 to a PI controller 304. IL(1-1-1) is the output current of the battery unit Bu including the battery pack 1-1-1, and may be the detection value of a current sensor iu that detects a U-phase current iu of the U-phase to which the battery pack 1-1-1 is connected, or may be the detection value of a current sensor IB that detects an input / output current IB of the battery 10 of the battery pack 1-1-1.

[0057] The PI controller 304 performs feedback control using proportional-integral control (PI control), and outputs a duty ratio Du(1-1-1) that is the sum of a proportional term and an integral term so that the deviation ΔIL becomes 0 (so that IL(1-1-1) matches the IL command). Then, the converter 2 (U-phase arm (switching elements Q9a, Q9b, Q10a, Q10b)) of the battery unit Bu that includes the battery pack 1-1-1 is PWM-controlled using the duty ratio Du(1-1-1). Note that all battery units Bu are controlled in the same way.

[0058] According to this first embodiment, voltage control is performed to control each of the converters 2 of the battery units Bu using a voltage command RV, which is a command value for the output voltage VP of the power supply system P, as an input parameter. As a result, even if a difference occurs between the output power OP and the power command RP (even if a power discrepancy occurs), voltage control is performed in each battery unit Bu, thereby making it possible to equalize the load (burden) on each battery unit Bu. Note that when the output power OP of the power supply system P falls below the power command RP, the output voltage VP decreases, and therefore voltage control is performed to increase the output power OP. When the output power OP exceeds the power command RP, the output voltage VP increases, and therefore voltage control is performed to decrease the output power OP. As a result, the output power OP is also controlled to satisfy the power command RP.

[0059] According to this first embodiment, the voltage control executed by the control device 3 is a feedback control using only proportional control by the P controller 302 so that the unit output voltage VO(N) matches the voltage command RV. Since feedback control is executed using only proportional control so that the unit output voltage VO(N) matches the voltage command RV, control interference between the battery units Bu can be suppressed. Note that the "N" in the unit output voltage VO(N) corresponds to the symbol of the battery pack included in the battery unit Bu, and the unit output voltage of the battery unit Bu including battery pack 1-n-1 is expressed as the unit output voltage VO(1-n-1). Hereinafter, "N" will be treated in the same manner, and "N" will correspond to the symbol of the battery pack.

[0060] If feedback control is performed using only proportional control to make the unit output voltage VO(N) coincide with the voltage command RV, it is difficult for the unit output voltage VO(N) to converge to the voltage command RV because an integral term (integral control) is not included. If the gain Kp of the proportional control is increased so that the unit output voltage VO(N) approaches the voltage command RV, the unit output voltage VO(N) will fluctuate significantly. It is preferable to determine the gain Kp of the proportional control in advance by experiment or the like so that the fluctuations in the unit output voltage VO(N) fall within a range acceptable to the PCS100, and perform voltage control using this gain Kp to bring the unit output voltage VO(N) close to the voltage command RV while keeping the fluctuations in the unit output voltage VO(N) within the acceptable range of the PCS100.

[0061] (Embodiment 2) In the second embodiment, in order to equalize the load (burden) of each battery unit Bu (battery pack 1), voltage control is performed in all battery units Bu. Then, a droop characteristic is applied to the voltage command of each battery unit Bu to suppress control interference between the battery units Bu.

[0062] 5 is an example of a block diagram for controlling the output power of power supply system P in the second embodiment. This block diagram may be configured as software and / or hardware in control ECU 400 and drive ECU 450. In FIG. 5, voltage command RV and power command RP are input from PCS-ECU 500, similarly to the first embodiment.

[0063] 5, the power command calculation unit 310 calculates a unit power command TP(N), which is a command value for the output power of each battery unit Bu. As explained above, "N" corresponds to the code of the battery pack included in the battery unit Bu. The power command RP and output power OP input from the PCS-ECU 500 are input to a subtraction point 401. The output power OP is the output power of the power supply system P, and may be calculated from the output power VP and output current IP of the power supply system. A deviation ΔRP between the power command RP and the output power OP is output from the subtraction point 401 and input to a PI controller 402. The PI controller 402 performs feedback control using proportional-integral control (PI control), and outputs a power correction Frp so that the deviation ΔRP becomes zero (so that the output power OP matches the power command RP).

[0064] The power command RP and the power correction Frp are input to a summing point 403 of the power command calculation unit 310, and the summing point 403 outputs an output power command TP for the power supply system P. The output power command TP output from the summing point 403 is input to a distributor 404. The distributor 404 outputs a unit power command TP(N), which is a command value for the output power (unit output power) of each battery unit Bu. In the power supply system P of this embodiment, 60 battery units Bu are connected in parallel, and the distributor 404 distributes 1 / 60 of the output power command TP to each battery unit Bu. For example, the distributor 404 multiplies the output power command TP by 1 / 60 to output the unit power command TP(N).

[0065] The block diagram downstream of the power command calculation unit 310 is common to each battery unit Bu, so the following description will be given of the battery unit Bu including the battery pack 1-1-1.

[0066] The output power acquisition unit 320 acquires the unit output power OP(1-1-1) of the battery unit Bu. In this embodiment, the unit output power OP(1-1-1) is acquired by multiplying the voltage VB(1-1-1) of the battery 10 included in the battery pack 1-1-1 by IL(1-1-1), which is the output current of the battery unit Bu (battery pack 1-1-1). The unit output power OP(1-1-1) acquired (calculated) by the output power acquisition unit 320 is input to the voltage command correction unit 330.

[0067] Voltage command corrector 330 corrects voltage command RV to calculate corrected voltage command RV(1-1-1). Voltage command corrector 330 receives as input voltage command RV output from PCS-ECU 500, unit power command TP(1-1-1) output from power command calculator 310 (distributor 404), and unit output power OP(1-1-1) output from output power acquirer 320.

[0068] 6 is a diagram illustrating the corrected voltage command RV(N) calculated by the voltage command corrector 330. In FIG. 6, the vertical axis represents the corrected voltage command RV(N), and the horizontal axis represents the power deviation ΔP. The power deviation ΔP is the power deviation of the unit output electric power O P(N) to unit Toden force Directive T P(N) is subtracted from OP(N) (ΔP=OP(N)-TP(N)). As shown in FIG. 6, when the power deviation ΔP is 0 (when the unit output power OP(N) and the unit power command TP(N) are equal), the corrected voltage command RV(N) is set to the voltage command RV. The relationship between the power deviation ΔP and the corrected voltage command RV(N) is linear.

[0069] 6, when the unit output power OP(N) is greater than the unit power command TP(N) and the power deviation ΔP is a positive value, the corrected voltage command RV(N) is a value obtained by correcting the voltage command RV so that the larger the power deviation ΔP, the smaller the voltage command RV becomes. Also, when the unit output power OP(N) is smaller than the unit power command TP(N) and the power deviation ΔP is a negative value, the larger the power deviation ΔP, the larger the voltage command RV becomes.

[0070] Based on the relationship (characteristics) shown in Fig. 6, voltage command corrector 330 corrects voltage command RV by power deviation ΔP (= OP(N) - TP(N)), calculates corrected voltage command RV(N), and outputs it to subtraction point 406. (In the battery unit Bu including battery pack 1-1-1, corrected voltage command RV(1-1-1) is output to subtraction point 406.) The corrected voltage command RV(1-1-1) output from the voltage command corrector 330 and the unit output voltage VO(1-1-1), which is the output voltage of the battery unit Bu, are input to a subtraction point 406, and the deviation ΔRV between the corrected voltage command RV(1-1-1) and the unit output voltage VO(1-1-1) is output from the subtraction point 406 to a PI controller 407. The unit output voltage VO(1-1-1) may be the detection value of a voltage sensor VH that detects a system voltage VH and is provided in the PCU 20 diverted to the power supply subunit Su-1. This voltage sensor VH corresponds to an example of the "voltage sensor that detects the unit voltage" of the present disclosure.

[0071] The PI controller 407 performs feedback control using proportional-integral control (PI control) and outputs an IL command so that the deviation ΔRV becomes 0 (so that the unit output voltage VO(1-1-1) matches the corrected voltage command RV(1-1-1)). The IL command is a current command to be output from the battery unit Bu.

[0072] The IL command output from the PI controller 407 and IL(1-1-1), which is the output current of the battery unit Bu, are input to a subtraction point 408, and the deviation ΔIL between the IL command and IL(1-1-1) is output from the subtraction point 408 to a PI controller 409. IL(1-1-1) is the output current of the battery unit Bu including the battery pack 1-1-1, and may be the detection value of a current sensor iu that detects a U-phase current iu of the U-phase to which the battery pack 1-1-1 is connected, or may be the detection value of a current sensor IB that detects an input / output current IB of the battery 10 of the battery pack 1-1-1.

[0073] The PI controller 409 performs feedback control using proportional-integral control (PI control), and outputs a duty ratio Du(1-1-1) that is the sum of a proportional term and an integral term so that the deviation ΔIL becomes 0 (so that IL(1-1-1) matches the IL command). Then, the converter 2 (U-phase arm (switching elements Q9a, Q9b, Q10a, Q10b)) of the battery unit Bu that includes the battery pack 1-1-1 is PWM-controlled using the duty ratio Du(1-1-1). Note that all battery units Bu are controlled in the same way.

[0074] According to this second embodiment, voltage control is performed to control each of the converters 2 of the battery units Bu using, as an input parameter, a voltage command RV, which is a command value for the output voltage VP of the power supply system P. As a result, even if a difference occurs between the output power OP and the power command RP (even if a power discrepancy occurs), voltage control is performed in each battery unit Bu, thereby making it possible to equalize the load (burden) on each battery unit Bu.

[0075] According to the second embodiment, the power command calculation unit 310 calculates a unit power command TP(N), which is a command value for the output power of each battery unit Bu, based on a power command RP, which is a command value for the output power of the power supply system P. Then, when the unit output power OP(N) is greater than the unit power command TP(N) (when the power deviation ΔP is positive), the voltage command correction unit 330 corrects the voltage command RV so that it becomes smaller as the deviation (power deviation ΔP) between the unit power command TP(N) and the unit output power OP(N) becomes larger, and when the unit output power OP(N) is smaller than the unit power command TP(N) (when the power deviation ΔP is negative), the voltage command correction unit 330 corrects the voltage command RV so that it becomes larger as the deviation (power deviation ΔP) between the unit power command TP(N) and the unit output power OP(N) becomes larger, thereby obtaining a corrected voltage command RV(N). The voltage control executed by the control device 3 is feedback control so that the unit output voltage VO(N) becomes equal to the corrected voltage command RV(N). When the unit output power OP(N) is greater than the unit power command TP(N), the unit output voltage VO(N) of the battery unit Bu is controlled to be smaller, and when the unit output power OP(N) is smaller than the unit power command TP(N), the unit output voltage VO(N) of the battery unit Bu is controlled to be larger, thereby suppressing control interference between the battery units Bu.

[0076] Furthermore, when the unit output power OP(N) and the unit power command TP(N) are equal (when the power deviation ΔP is 0), the voltage command RV is not corrected and is set to the corrected voltage command RV(N), so the output voltage VP of the power supply system P can be controlled to become the voltage command RV. Furthermore, because the relationship between the power deviation ΔP and the corrected voltage command RV(N) is set to be linear, the unit output voltage VO(N) can be stably controlled.

[0077] In the above embodiment, the power supply system P is made up of a plurality of power supply subunits Su connected in parallel, which makes it possible to increase the input and output power of the power supply system P.

[0078] According to the above embodiment, the converter 2 of the power supply subunit Su 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 power supply subunit Su. This makes it possible to promote the reuse of batteries and PCUs that are collected when the electric vehicle V is replaced or dismantled.

[0079] (Variation 1) FIG. 7 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. 7, the H / HV-ECU 2 0 The HV-ECU 200 mounted on the electric vehicle V is utilized as the HV-ECU 200. The MG-ECU 210a utilizes the MG-ECU 210. The BT-ECU 220a1 to BT-ECU 220a-3 utilize the BT-ECU 220.

[0080] 7, an interface ECU (I / F-ECU) 600 connects the PCS-ECU 500 and the control device 3a (H / HV-ECU 200a) and ensures compatibility between the communication protocol of the PCS-ECU 500 and the communication protocol of the control device 3a. The H / HV-ECU 200a calculates a power command TP(N) for each battery unit Bu, etc., from the power command RP, voltage command RV, etc. received from the PCS-ECU 500 via the I / F-ECU 600.

[0081] MG-ECU210a, HV-ECU(1)2 0 0a-1~HV-ECU(3)2 07, sub-control device 3a1, which is made up of BT-ECU 220a-3 and BT-ECU 220a1 to BT-ECU 220a-3, is a control device that controls power supply subunit Su. In Fig. 7, sub-control device 3a1-1 is a control device that controls 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, control device 3a has n sub-control devices 3a1, sub-control device 3a1-1 to sub-control device 3a1-n.

[0082] 7, 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 calculates the SOC. The HV-ECU(1) 200a-1 controls the opening and closing of the SMR 11 of the battery pack 1-1-1 based on a power command TP(1-1-1) and a voltage command RV. The HV-ECU 200a-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 calculates the duty ratio Du(1-1-1) based on the voltage command RV, the power command TP(1-1-1), etc., as described above, and controls the converter 2 (drives the switching element of the U-phase arm of the inverter 23).

[0083] Sub-control devices 3a1-2 to 3a1-n also perform the same processing as sub-control device 3a1-1 for power supply subunits Su-2 to Su-n. According to this first modification, it is possible to promote the utilization of hardware such as HV-ECU 200, MG-ECU 210, and BT-ECU 220 mounted on electric vehicle V as control devices for power supply system P. In addition, it is possible to utilize the CAN (Controller Area Network) communication resources used by HV-ECU 200, MG-ECU 210, BT-ECU 220, etc. mounted on electric vehicle V, and it is possible to perform highly reliable communication and monitoring of multiple systems relatively easily.

[0084] (Variation 2) FIG. 8 is a diagram showing the overall configuration of power supply system Pa in Modification 2. 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, inverter 23, which has a switching element connected in parallel with it, is used as the switching element of converter 2, particularly to enable the passage of large amounts of power. However, some PCUs mounted on electric vehicles are provided with a single inverter, or are not provided with a boost converter.

[0085] The power supply system Pa in the second 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.

[0086] In FIG. 8, converter 2A is a repurposed inverter (three-phase inverter) of a PCU mounted on an electric vehicle. In FIG. 8, SR1 and SR2 of battery pack 1 are system main relays (SMR). As in the above embodiment, the positive terminals of the output terminals of three battery packs 1 (1-1-1, 1-1-2, 1-1-3) are connected to 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 battery pack 1 and coil 5 is connected to the negative terminal of the output terminal of battery pack 1 via 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 input / output terminals of 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 are connected to input / output terminals of PCS 100. The negative terminal of battery pack 1 is connected to the negative line NL.

[0087] Thus, in the power supply system Pa of the second 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 diverted to the 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 this second modification, the control device 3b executes voltage control similar to that in the above embodiment, thereby achieving the same effects as in the above embodiment.

[0088] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0089] 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 wheels, 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 in which a plurality of battery units, each including a battery and a converter, are connected in parallel, A control device for controlling the converter, the control device executes voltage control for controlling each of the converters using a voltage command, which is a command value for an output voltage of a power supply system, as an input parameter; a power supply subunit including the plurality of battery units connected in parallel and provided with a positive terminal and a negative terminal; The converter is a first three-phase inverter, The power supply subunit includes a conversion inverter obtained by converting a second three-phase inverter, The converter includes three-phase first arms connected in parallel to each other between a positive pole line and a negative pole line, The conversion inverter includes a three-phase second arm connected in parallel to each other between the positive pole line and the negative pole line, the three-phase second arm includes a first phase arm, a second phase arm, and a third phase arm; the first phase arm has a first upper arm and a first lower arm connected in series, and a midpoint between the first upper arm and the first lower arm is electrically connected to the negative terminal; the second phase arm has a second upper arm and a second lower arm connected in series, and a midpoint between the second upper arm and the second lower arm is electrically connected to the positive terminal, the third phase arm has a third upper arm and a third lower arm connected in series, and a midpoint between the third upper arm and the third lower arm is electrically connected to the positive terminal, the battery is connected to each phase arm of the first three-phase inverter; A power supply system, wherein each of the first lower arm, the second upper arm, and the third upper arm is short-circuited.

2. A voltage sensor is further provided to detect a unit output voltage which is an output voltage of the battery unit, 2. The power supply system according to claim 1, wherein the voltage control executed by the control device is feedback control using only proportional control so that the unit output voltage becomes the voltage command.

3. 3. The power supply system according to claim 2, wherein a gain of said proportional control is set so that fluctuations in said unit output voltage are within a predetermined range.

4. a voltage sensor for detecting a unit output voltage, which is an output voltage of the battery unit; an output power acquisition unit that acquires a unit output power that is an output power of the battery unit, The control device includes: a power command calculation unit that calculates a unit power command that is a command value of the unit output power based on a power command that is a command value of the output power of the power supply system; a voltage command correction unit which, when the unit output power is greater than the unit power command, corrects the voltage command so that the voltage command becomes smaller as the deviation between the unit power command and the unit output power increases, and, when the unit output power is smaller than the unit power command, corrects the voltage command so that the voltage command becomes larger as the deviation between the unit power command and the unit output power increases, thereby obtaining a corrected voltage command, 2. The power supply system according to claim 1, wherein the voltage control executed by the control device is feedback control so that the unit output voltage becomes the corrected voltage command.

5. 5. The power supply system according to claim 4, wherein the voltage command corrector sets the voltage command to the corrected voltage command when the unit output power and the unit power command are equal.

6. The power supply system according to claim 5 , wherein the voltage command correction unit determines the corrected voltage command so that a relationship between the deviation and the corrected voltage command is linear.

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