Electricity storage system

Abstract

A power storage system capable of efficiently charging in accordance with the voltage state of a charging device and capable of suppressing manufacturing cost. This power storage system is provided with: a storage battery provided with first to third semiconductor switches capable of switching between a first voltage state in which a first power storage unit (21) and a second power storage unit (22) are connected in series and can be charged at a first voltage, and a second voltage state in which the first power storage unit and the second power storage unit are connected in parallel and can be charged at a second voltage; a three-phase motor; an inverter (5) and a first smoothing capacitor (C1) connected to power supply circuits (11P, 11N) between the battery and the three-phase motor; and DC power supply circuits (13P, 13N) connected to the power supply circuits (11P, 11N) between the inverter and the storage battery. The DC power supply circuit (13P) on the positive electrode side has a branch circuit (14) connected to coils (32U, 32V, 32W) of any phase of the three-phase motor.

Description

Technical Field

[0001] The present invention relates to a power storage system. Background Art

[0002] In recent years, in order to ensure that more people have access to affordable, reliable, and sustainable modern energy, research and development of charging and power supply in mobile objects equipped with secondary batteries that contribute to energy efficiency has been actively carried out.

[0003] Regarding the charging power supply in mobile bodies equipped with secondary batteries, there are two types of charging equipment such as charging piles, which support 400V and 800V. If the mobile body only supports 400V charging equipment, if it supports 800V charging equipment, it cannot enjoy the fast charging performance of 800V charging equipment.

[0004] When a mobile object supports the use of charging equipment that supports 400V class and 800V class, a voltage converter is generally used to step up the voltage to 800V for charging when using a charging equipment that supports 400V class, or a voltage converter is used to step down the voltage to 400V for charging when using a charging equipment that supports 800V class. However, if a charging voltage converter is used during charging, efficiency deteriorates.

[0005] Regarding this problem, it is also known that a mobile object can be charged using both a charging device supporting 400V class and a charging device supporting 800V class without using a charging voltage converter by switching the connection method of the battery module (for example, Patent Document 1 and Patent Document 2).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-080474

[0009] Patent Document 2: Japanese Patent Application Publication No. 2020-150618 Summary of the invention

[0010] Problems to be solved by the invention

[0011] On the other hand, there are two types of auxiliary machines used in mobile bodies: auxiliary machines driven at 400V level and auxiliary machines driven at 800V level. In a mobile body that switches the connection method of the battery module, when driving a 400V level auxiliary machine while charging with a charging device that supports 800V level, or when driving an 800V level auxiliary machine while charging with a charging device that supports 400V level, a voltage converter for the auxiliary machine is generally used for voltage conversion. However, the voltage converter for the auxiliary machine is expensive, and the manufacturing cost increases.

[0012] The present invention provides a power storage system capable of efficiently charging according to the voltage state of a charging facility and capable of suppressing manufacturing costs.

[0013] Means for solving problems

[0014] The power storage system of the present invention comprises:

[0015] A storage battery comprising a first power storage unit, a second power storage unit, and a first switch unit capable of switching between a first voltage state and a second voltage state, wherein the first power storage unit and the second power storage unit are connected in series and can be charged at a first voltage, and the second voltage state wherein the first power storage unit and the second power storage unit are connected in parallel and can be charged at a second voltage;

[0016] a three-phase motor in which coils of three phases are connected at a neutral point and the three-phase motor is driven by electric power supplied from the battery;

[0017] an inverter connected to a power transmission path between the battery and the three-phase motor;

[0018] a DC power supply circuit connected to a first connection portion on a power transmission path between the inverter and the battery;

[0019] a capacitor provided on the power transmission path between the battery and the three-phase motor; and

[0020] a branch circuit which branches from the DC power supply circuit on the positive side and is connected to a coil of any one phase among the three-phase coils,

[0021] The first switch unit includes a semiconductor switch.

[0022] Effects of the Invention

[0023] According to the present invention, charging can be performed efficiently according to the voltage state of the charging facility, and manufacturing costs can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram showing the configuration of a power storage system 1 according to the first embodiment.

[0025] Figure 2 It is a diagram showing the first voltage state (800 V starting) of the battery 2 .

[0026] Figure 3 1 is a diagram showing the second voltage state (400 V starting) of the battery 2 .

[0027] Figure 4This is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is traveling.

[0028] Figure 5 This is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is charged at the first voltage (800 V).

[0029] Figure 6 This is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is charged at the second voltage (400 V).

[0030] Figure 7 It is a diagram showing an operation sequence when an electric vehicle equipped with the power storage system 1 according to the first embodiment is traveling.

[0031] Figure 8 This is a diagram showing an operation sequence when charging the electric vehicle equipped with the power storage system 1 according to the first embodiment at the first voltage (800 V).

[0032] Fig. 9 This is a diagram showing an operation sequence when charging the electric vehicle equipped with the power storage system 1 according to the first embodiment at the second voltage (400 V).

[0033] Fig.10 1 is a diagram showing the flow of current during the pre-charging operation in the first voltage state (800 V starting) of the storage battery 2 of the comparative example.

[0034] Fig.11 It is a diagram showing the operation sequence during the precharge operation of the comparative example.

[0035] Fig.12 This is a diagram showing the flow of current during the pre-charging operation in the first voltage state (800 V starting) of the battery 2 according to the first embodiment.

[0036] Fig.13 It is a diagram showing the operation sequence during the precharge operation according to the first embodiment.

[0037] Fig.14 It is a diagram showing the configuration of an electric vehicle equipped with a power storage system 1 according to the second embodiment.

[0038] Fig.15 This is a diagram showing the flow of current when an electric vehicle equipped with the power storage system 1 according to the second embodiment is traveling.

[0039] Fig.16 This is a diagram showing the flow of current when an electric vehicle equipped with the power storage system 1 according to the second embodiment is charged at a first voltage (800 V).

[0040] Fig.17This is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the second embodiment is charged at the second voltage (400 V).

[0041] Fig.18 It is a diagram showing an operation sequence when an electric vehicle equipped with the power storage system 1 according to the second embodiment is traveling.

[0042] Fig.19 This is a diagram showing an operation sequence when charging the electric vehicle equipped with the power storage system 1 according to the second embodiment at the first voltage (800 V).

[0043] Fig. 20 This is a diagram showing an operation sequence when charging the electric vehicle equipped with the power storage system 1 according to the second embodiment at the second voltage (400 V).

[0044] Fig.21 It is a diagram showing a configuration of a modified example of the power storage system 1 according to the first embodiment.

[0045] Description of Reference Numerals

[0046] 1. Power storage system

[0047] 2 Batteries

[0048] 21 First power storage unit

[0049] 22 Second power storage unit

[0050] 3 three-phase motor

[0051] 10. Control Unit

[0052] 31 Neutral point

[0053] 32U, 32V, 32W coil

[0054] 34 Connection part (second connection part)

[0055] 4 Auxiliary machines

[0056] 5 Inverter

[0057] 111P, 111N connection part (first connection part)

[0058] 11P, 11N Power supply circuit (power transmission path)

[0059] 12P, 12N auxiliary machine drive circuit

[0060] 13P, 13N DC power supply circuit

[0061] 14 Branch circuit

[0062] S / C_A First semiconductor switch (first switch unit)

[0063] S / C_B Second semiconductor switch (first switch section)

[0064] S / C_C Third semiconductor switch (first switch section)

[0065] M / C First contactor (third switch unit)

[0066] VS / C Second contactor (third switch section)

[0067] QC / C_C Fifth contactor (second switch section)

[0068] C1 First smoothing capacitor (capacitor)

[0069] L1 First reactor (first switch section)

[0070] L2 Second reactor (first switch unit). DETAILED DESCRIPTION

[0071] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. Figures 1 to 13 A first embodiment of the present invention will be described.

[0072] [First embodiment]

[0073] Figure 1 The power storage system 1 of the first embodiment shown is mounted on an electric vehicle such as an electric car. The electric vehicle equipped with the power storage system 1 supports 400V and 800V charging equipment, and can not only quickly charge the battery 2 at 400V and 800V charging voltages, but also efficiently drive the three-phase motor 3 and the auxiliary machine 4 at a basic voltage of 800V.

[0074] Specifically, if Figure 1 As shown, the power storage system 1 includes a battery 2 , a three-phase motor 3 , an auxiliary machine 4 , an inverter 5 (INV), a DC-DC converter 6 , power supply circuits 11P and 11N, auxiliary machine drive circuits 12P and 12N, DC power supply circuits 13P and 13N, a branch circuit 14 , and a control unit 10 .

[0075] like Figures 1 to 3 As shown, the battery 2 includes a first power storage unit 21, a second power storage unit 22, a first contactor M / C, first to third semiconductor switches S / C_A, S / C_B, S / C_C, first and second reactors L1, L2, a current sensor IS and a current breaker FUSE.

[0076] The first power storage unit 21 and the second power storage unit 22 are battery modules capable of 400V charge and discharge, respectively.

[0077] The first contactor M / C is disposed at the end portion on the positive electrode side of the battery 2 , and functions as a main switch that opens and closes the connection with the outside of the battery 2 (the power supply circuit 11P).

[0078] The first to third semiconductor switches S / C_A, S / C_B, S / C_C are composed of MOSFET, bipolar transistor, IGBT, etc., and switch the connection state between the first power storage unit 21 and the second power storage unit 22. For example, Figure 2 As shown in FIG. 1 , if the first semiconductor switch S / C_A is turned on and the second semiconductor switch S / C_B and the third semiconductor switch S / C_C are turned off, the battery 2 is in the first voltage state (800V start) in which the first power storage unit 21 and the second power storage unit 22 are connected in series, and 800V charging and discharging are possible. Figure 3 As shown, if the first semiconductor switch S / C_A is turned off and the second semiconductor switch S / C_B and the third semiconductor switch S / C_C are turned on, the battery 2 becomes a second voltage state (400V starting) in which the first power storage unit 21 and the second power storage unit 22 are connected in parallel, and 400V charging and discharging are possible. In addition, starting is a concept that includes driving when an electric vehicle equipped with the power storage system 1 is running and charging when the electric vehicle is parked. The first to third semiconductor switches S / C_A, S / C_B, and S / C_C are an example of a first switch unit that can switch between a first voltage state (800V starting) and a second voltage state (400V starting).

[0079] The first and second reactors L1 and L2 are arranged in series with the first to third semiconductor switches S / C_A, S / C_B, S / C_C to prevent short circuit when the first to third semiconductor switches S / C_A, S / C_B, S / C_C are turned on.

[0080] Specifically, Figure 2 and Figure 3 As shown, the battery 2 includes a positive electrode side node N1, a negative electrode side node N2, a negative electrode side connection node N3, and a positive electrode side connection node N4. At the positive electrode side node N1, the positive electrode side path K1 of the first power storage unit 21 is connected in parallel with the positive electrode side path K2 of the second power storage unit 22. At the negative electrode side node N2, the negative electrode side path K3 of the first power storage unit 21 is connected in parallel with the negative electrode side path K4 of the second power storage unit 22. At the negative electrode side connection node N3, the series connection path K5 connecting the negative electrode side path K3 of the first power storage unit 21 and the positive electrode side path K2 of the second power storage unit 22 is connected to the negative electrode side path K3 of the first power storage unit 21. At the positive electrode side connection node N4, the series connection path K5 is connected to the positive electrode side path K2 of the second power storage unit 22.

[0081] The first semiconductor switch S / C_A is arranged on the series connection path K5, the second semiconductor switch S / C_B is arranged between the positive side node N1 and the positive side connection node N4, and the third semiconductor switch S / C_C is arranged between the negative side node N2 and the negative side connection node N3. In addition, the first inductor L1 is arranged between the positive side connection node N4 and the positive electrode of the second power storage unit 22, and the second inductor L2 is arranged between the negative side connection node N3 and the negative electrode of the first power storage unit 21. Thus, when starting with the first voltage (800V), the two inductors L1 and L2 are connected in series, and when starting with the second voltage (400V), one inductor L1 and L2 are connected to each path, and the inductors L1 and L2 are appropriately arranged according to the voltage. In addition, the number and arrangement of the inductors are not limited to the above example. It is sufficient to configure at least one reactor in the form of a circuit in each of the first voltage state (800V starting) and the second voltage state (400V starting). Therefore, for example, even if it is a reactor arranged between the first contactor M / C and the current sensor IS, it can prevent a short circuit when the first to third semiconductor switches S / C_A, S / C_B, S / C_C are turned on.

[0082] According to such a storage battery 2, the first voltage state (800V start) and the second voltage state (400V start) are switched by the first to third semiconductor switches S / C_A, S / C_B, S / C_C, so that the first smoothing capacitor C1 described later can be precharged by PWM (Pulse Width Modulation) control of the first to third semiconductor switches S / C_A, S / C_B, S / C_C. As a result, compared with the case where the first voltage state (800V start) and the second voltage state (400V start) are switched using a mechanical switch (contactor, etc.) that cannot perform high-frequency switching, a precharge circuit is not required, so the volume and weight of the circuit of the storage battery 2 can be reduced. In addition, the PWM control of the first to third semiconductor switches S / C_A, S / C_B, S / C_C will be described later.

[0083] The current sensor IS is disposed between the first contactor M / C and the power storage units 21 and 22 to measure the current.

[0084] The current breaker FUSE is arranged at the end of the negative electrode side of the storage battery 2, and disconnects the connection with the outside (power supply circuit 11N) of the storage battery 2 when an abnormality occurs. In the power storage system 1 of the present embodiment, the current breaker FUSE is composed of a high-temperature fuse (Pyro Fuse) that can actively cut off the current according to an electrical signal. When an abnormality occurs (a collision of the vehicle, a short circuit in the storage battery 2, etc.), the current breaker FUSE is caused to perform a circuit breaking action, and all the contactors and semiconductor switches in the storage battery 2 are disconnected (opened).

[0085] In this way, when an abnormality occurs, the connection with the outside can be cut off at the positive and negative ends of the battery 2. In addition, in either the first voltage state (800V start) or the second voltage state (400V start), the circuit can be reliably cut off even when the contactor or semiconductor switch fails by disconnecting the multiple contactors and semiconductor switches present in the circuit. Furthermore, by making the current breaker FUSE a high-temperature fuse, the contactor disposed at the end of the negative electrode side of the battery 2 is not required, and the number of components and costs can be reduced.

[0086] The three-phase motor 3 includes three-phase coils 32U, 32V, and 32W connected at one end to a neutral point 31, and is rotationally driven by the power supplied from the battery 2 via the inverter 5. The three-phase motor 3 of the present embodiment includes a U-phase terminal 33U, a V-phase terminal 33V, and a W-phase terminal 33W connected to the other end of the coils 32U, 32V, and 32W. The U-phase terminal 33U, the V-phase terminal 33V, and the W-phase terminal 33W are connected to the inverter 5. In addition, the other end of the coil 32U, 32V, and 32W of any phase is connected to the branch circuit 14 at the connection portion 34. In the present embodiment, the coil 32U among the three-phase coils 32U, 32V, and 32W is connected to the branch circuit 14 at the connection portion 34 located between the U-phase terminal 33U and the inverter 5.

[0087] The inverter 5 converts the DC power supplied from the battery 2 into three-phase AC power by switching a plurality of switching elements, thereby rotating and driving the three-phase motor 3. In addition, when the inverter 5 supplies a DC current (400V) from the branch circuit 14 to the connection portion 34, the inverter 5 can function as a boost circuit that boosts the DC current (800V) by switching a plurality of switching elements using a coil connected to the branch circuit 14 and a coil of another phase (in this embodiment, coils 32U, 32V or coils 32U, 32W). That is, the coils 32U, 32V, and 32W wound around the stator core are used as a transformer. Regardless of whether the gate is turned on or off, the inverter 5 allows the flow of current from the three-phase motor 3 side to the battery 2 side, and allows the flow of current from the battery 2 side to the three-phase motor 3 side only when the gate is turned on.

[0088] The auxiliary machine 4 is a high voltage driven vehicle-mounted device that can be driven by DC power from the battery 2 and an external power supply, and includes, for example, an electric compressor for air conditioning, a heater, etc. The auxiliary machine 4 is connected to the battery 2 via the auxiliary machine drive circuits 12P and 12N, the second contactor VS / C, and the power supply circuits 11P and 11N described later. The second contactor VS / C is an example of the third switch unit. The auxiliary machine 4 of this embodiment operates at a basic voltage of 800V.

[0089] The DC-DC converter 6 steps down the voltage of the DC power from the battery 2 and the external power supply to drive the low-voltage driving vehicle-mounted equipment. The DC-DC converter 6 is provided with an ammeter (not shown).

[0090] The power supply circuits 11P and 11N are composed of a positive and negative pair, and connect the battery 2 to the inverter 5 (three-phase motor 3). The power supply circuits 11P and 11N are provided with connection parts 111P and 111N with the DC power supply circuits 13P and 13N, and connection parts 112P and 112N with the auxiliary machine drive circuits 12P and 12N (auxiliary machine 4) are provided on the inverter 5 side of the connection parts 111P and 111N. In addition, the power supply circuit 11P on the positive side is provided with a second contactor VS / C that turns the circuit on and off between the connection part 112P connected to the auxiliary machine drive circuit 12P and the connection part 111P of the DC power supply circuit 13P. In addition, a first voltage sensor V_PIN, a first smoothing capacitor C1, and a first resistor R1 are provided on the inverter 5 side of the power supply circuits 11P and 11N. The first voltage sensor V_PIN, the first smoothing capacitor C1 and the first resistor R1 are provided on a circuit connecting the positive power supply circuit 11P and the negative power supply circuit 11N. The first resistor R1 is provided to discharge the first smoothing capacitor C1 when the circuit is disconnected.

[0091] The DC power supply circuit 13P, 13N is composed of a positive and negative pair, and a charging terminal 131P, 131N capable of connecting an external power source such as a charging device is provided at one end thereof, and the other end is connected to the power supply circuit 11P, 11N via a connecting portion 111P, 111N. A third contactor QC / C_A and a fourth contactor QC / C_B are provided in the DC power supply circuit 13P, 13N to connect and disconnect each circuit. In addition, a second voltage sensor V_BAT is provided at a position closer to the connecting portion 111P, 111N than the third contactor QC / C_A and the fourth contactor QC / C_B. In addition, a third voltage sensor V_QC is provided at a position closer to the charging terminal 131P, 131N than the third contactor QC / C_A and the fourth contactor QC / C_B.

[0092] The branch circuit 14 is branched at a position closer to the connection portion 111P than the third contactor QC / C_A and the second voltage sensor V_BAT in the DC power supply circuit 13P on the positive side, and is connected to any coil of the three-phase motor 3 via the connection portion 34. A fifth contactor QC / C_C for connecting and disconnecting the circuit is provided in the middle of the branch circuit 14. The fifth contactor QC / C_C is an example of a second switch portion.

[0093] The control unit 10 is, for example, a vehicle ECU, and controls the driving and charging of the power storage system 1. More specifically, the control unit 10 performs on / off control of each contactor M / C, VS / C, QC / C_A, QC / C_B, and QC / C_C and their failure detection (melting detection), on / off control (including PWM control) and failure detection of each semiconductor switch S / C_A, S / C_B, and S / C_C, and controls the DC-DC converter 6 and the inverter 5.

[0094] Next, refer to Figures 4 to 9 The operation of the power storage system 1 will be described.

[0095] Figure 4 is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is traveling (800 V drive), Figure 7 This is a diagram showing an operation sequence when an electric vehicle equipped with the power storage system 1 according to the first embodiment is traveling (800 V drive).

[0096] When the ignition switch IG of the electric vehicle is turned on (turned on), the control unit 10 first turns on the first contactor M / C and the second contactor VS / C, and checks the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT. When the detection voltage value of the first voltage sensor V_PIN or the second voltage sensor V_BAT rises, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C is faulty, and issues an abnormality notification.

[0097] When the control unit 10 determines that there is no failure of the first to third semiconductor switches S / C_A, S / C_B, S / C_C, the first semiconductor switch S / C_A is continuously turned on through an intermittent on period based on PWM control, and the circuit in the battery 2 is connected under the first voltage state (800V). As a result, the first smoothing capacitor C1 is precharged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase. And when the precharging of the first smoothing capacitor C1 is completed, the electric vehicle can travel. At this time, the auxiliary machine 4 is connected to the power supply circuit 11P, 11N via the auxiliary machine drive circuit 12P, 12N, and is driven by the first voltage (800V) supplied from the battery 2.

[0098] On the other hand, when the ignition switch IG is turned off (off operation), the control unit 10 first turns off the second contactor VS / C and checks the detection voltage value of the first voltage sensor V_PIN. If the detection voltage value of the first voltage sensor V_PIN does not decrease due to the discharge of the first smoothing capacitor C1, the control unit 10 determines that the second contactor VS / C is faulty and issues an abnormality notification.

[0099] When the control unit 10 determines that the second contactor VS / C has no fault, the first contactor M / C is disconnected at the time when the discharge of the first smoothing capacitor C1 is completed to check the detection voltage value of the second voltage sensor V_BAT. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that the first contactor M / C has a fault and issues an abnormality notification.

[0100] When the control unit 10 determines that the first contactor M / C is not faulty, it turns off the first semiconductor switch S / C_A to terminate the operation sequence during driving.

[0101] Figure 5 1 is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is charged at the first voltage (800 V charging). Figure 8 This is a diagram showing an operation sequence during first voltage charging (800 V charging) of an electric vehicle equipped with the power storage system 1 according to the first embodiment.

[0102] If the charging plug is connected to the charging terminals 131P and 131N, the control unit 10 performs CAN communication with the charging device to identify the charging voltage. When the charging voltage is the first voltage (800V), first, the control unit 10 turns on the first contactor M / C and the second contactor VS / C, and checks the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT. When the detection voltage value of the first voltage sensor V_PIN or the second voltage sensor V_BAT rises, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C has a fault, and issues an abnormality notification.

[0103] When the control unit 10 determines that there is no failure in the first to third semiconductor switches S / C_A, S / C_B, and S / C_C, the first semiconductor switch S / C_A is continuously turned on through an intermittent on period based on PWM control, and the circuit in the battery 2 is connected at the first voltage state (800V). As a result, the first smoothing capacitor C1 is precharged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase. Then, when the precharging of the first smoothing capacitor C1 is completed, the battery 2 becomes a state where it can start charging at the first voltage (800V).

[0104] After that, the control unit 10 turns on the third contactor QC / C_A and the fourth contactor QC / C_B to start charging the battery 2 with the first voltage (800 V). At this time, the auxiliary machine 4 is connected to the DC power supply circuits 13P and 13N via the auxiliary machine drive circuits 12P and 12N and the second contactor VS / C, and is driven by the first voltage (800 V) supplied from the charging equipment.

[0105] On the other hand, when the control unit 10 determines that the input of the charging stop signal is received, the third contactor QC / C_A and the fourth contactor QC / C_B are disconnected, and the detection voltage value of the third voltage sensor V_QC is checked. If the detection voltage value of the third voltage sensor V_QC does not decrease, the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B have failed, and issues an abnormality notification.

[0106] When the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B are not faulty, the control unit 10 disconnects the second contactor VS / C and checks the detection voltage value of the first voltage sensor V_PIN. When the detection voltage value of the first voltage sensor V_PIN does not decrease due to the discharge of the first smoothing capacitor C1, the control unit 10 determines that the second contactor VS / C is faulty and issues an abnormality notification.

[0107] When the control unit 10 determines that the second contactor VS / C has no fault, the first contactor M / C is disconnected at the time when the discharge of the first smoothing capacitor C1 is completed to check the detection voltage value of the second voltage sensor V_BAT. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that the first contactor M / C has a fault and issues an abnormality notification.

[0108] When the control unit 10 determines that the first contactor M / C has no failure, it turns off the first semiconductor switch S / C_A to terminate the operation sequence during the first voltage (800 V) charging.

[0109] Figure 6 1 is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the first embodiment is charged at the second voltage (400 V charging). Fig. 9 This is a diagram showing an operation sequence during second voltage charging (400 V charging) of an electric vehicle equipped with the power storage system 1 according to the first embodiment.

[0110] If the charging plug is connected to the charging terminals 131P and 131N, the control unit 10 performs CAN communication with the charging device to identify the charging voltage. When the charging voltage is the second voltage (400V), first, the control unit 10 turns on the first contactor M / C and the fifth contactor QC / C_C, and checks the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT. When the detection voltage value of the first voltage sensor V_PIN or the second voltage sensor V_BAT rises, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C has a fault, and issues an abnormality notification.

[0111] When the control unit 10 determines that there is no failure in the first to third semiconductor switches S / C_A, S / C_B, and S / C_C, the second semiconductor switch S / C_B and the third semiconductor switch S / C_C are continuously turned on via an intermittent on period based on PWM control, and the circuit in the battery 2 is connected at the second voltage state (400 V). As a result, the first smoothing capacitor C1 is precharged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase.

[0112] In addition, the control unit 10 turns on the third contactor QC / C_A and the fourth contactor QC / C_B after activating the boost circuit composed of the three-phase motor 3 and the inverter 5. As a result, the battery 2 is in a state where it can start charging with the second voltage (400V). In addition, the three-phase motor 3 and the inverter 5 connected to the DC power supply circuits 13P and 13N via the branch circuit 14 can boost the second voltage (400V) supplied from the charging device to the first voltage (800V) to drive the auxiliary machine 4.

[0113] On the other hand, when the control unit 10 determines that the input of the charging stop signal is received, the third contactor QC / C_A and the fourth contactor QC / C_B are disconnected, and the detection voltage value of the third voltage sensor V_QC is checked. If the detection voltage value of the third voltage sensor V_QC does not decrease, the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B have failed, and issues an abnormality notification.

[0114] When the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B are not faulty, the control unit 10 stops the boosting of the three-phase motor 3 and the inverter 5, disconnects the fifth contactor QC / C_C, and checks the detection voltage value of the first voltage sensor V_PIN. When the detection voltage value of the first voltage sensor V_PIN does not decrease, the control unit 10 determines that the fifth contactor QC / C_C is faulty and issues an abnormality notification.

[0115] When the control unit 10 determines that the fifth contactor QC / C_C is not faulty, it disconnects the first contactor M / C and checks the detection voltage value of the second voltage sensor V_BAT. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that the first contactor M / C is faulty and issues an abnormality notification.

[0116] When the control unit 10 determines that the first contactor M / C is not faulty, it turns off the second semiconductor switch S / C_B and the third semiconductor switch S / C_C to terminate the operation sequence during the second voltage (400 V) charging.

[0117] Next, refer to Figures 10 to 13 The precharge operation will be described.

[0118] Fig.10 is a diagram showing a first voltage state (800 V starting) of the battery 2 of the comparative example. Fig.11 It is a diagram showing the operation sequence during the precharge operation of the comparative example.

[0119] like Fig.10 As in the comparative example shown in the figure, when a first switch unit (S / C_A, S / C_B, S / C_C) that switches between a first voltage state (800V start) and a second voltage state (400V start) is formed using a mechanical switch (contactor, etc.) that cannot perform high-frequency switching, a pre-charging circuit is provided to pre-charge the first smoothing capacitor C1. The pre-charging circuit is provided in parallel with the first contactor M / C, for example. In the pre-charging circuit, a pre-charging contactor P / C and a pre-charging resistor R are arranged in series.

[0120] like Fig.11 As shown, when the battery 2 is started at the first voltage state (800V start), the control unit 10 activates the pre-charging contactor P / C and the second contactor VS / C (see Figure 1 ) is turned on, the mechanical switch S / C_A (in the second voltage state, the mechanical switch S / C_B and the mechanical switch S / C_C) is turned on. As a result, a current (I_C1) determined by the pre-charge resistor R flows through the first smoothing capacitor C1, and the first smoothing capacitor C1 is pre-charged (V_C1).

[0121] Fig.12 1 is a diagram showing a first voltage state (800 V starting) of the battery 2 according to the first embodiment. Fig.13 It is a diagram showing the operation sequence during the precharge operation according to the first embodiment.

[0122] like Fig.12As shown in FIG. 1 , in this embodiment, the first switch unit is composed of semiconductor switches S / C_A, S / C_B, and S / C_C. Fig.13 As shown, when the battery 2 is started at the first voltage state (800V starting), the control unit 10 makes the first contactor M / C and the second contactor VS / C (see Figure 1 ) is turned on, the first semiconductor switch S / C_A (the second semiconductor switch S / C_B and the third semiconductor switch S / C_C in the second voltage state) is turned on. In this case, the control unit 10 intermittently turns on the first semiconductor switch S / C_A through PWM control, thereby controlling the current flowing through the first smoothing capacitor C1 and precharging the first smoothing capacitor C1.

[0123] The slope of the current value I_C1 flowing through the first smoothing capacitor C1 is determined by the inductance of the reactors L1 and L2. In addition, if the initial on-time of the first semiconductor switch S / C_A (or the second semiconductor switch S / C_B and the third semiconductor switch S / C_C) is long, there is a possibility that the reactors L1 and L2 will be saturated and become short-circuit currents. Therefore, the control unit 10 determines an unsaturated upper limit current to switch the first semiconductor switch S / C_A (or the second semiconductor switch S / C_B and the third semiconductor switch S / C_C). In this way, by forming a first switch unit with semiconductor switches S / C_A, S / C_B, and S / C_C, and performing PWM control on the first switch unit to pre-charge the first smoothing capacitor C1, it is possible to omit Fig.10 The pre-charge circuit described in .

[0124] [Second embodiment]

[0125] Next, refer to Figures 14 to 20 A power storage system 1 according to the second embodiment will be described. Here, for configurations common to those of the first embodiment, the description of the first embodiment may be cited using the same reference numerals as those of the first embodiment.

[0126] In the power storage system 1 of the first embodiment described above, the third contactor QC / C_A as the main switch for charging is connected in series with the first contactor M / C as the main switch for the battery 2. However, in the power storage system 1 of the second embodiment, Fig.14 As shown, the third contactor QC / C_A is connected in parallel with the first contactor M / C.

[0127] Even the power storage system 1 of the second embodiment can obtain the same effect as the power storage system 1 of the first embodiment based on the operation of the working sequence described later. In addition, in the power storage system 1 of the second embodiment, during the charging of the second voltage (400V), the first contactor M / C can be used to separate the battery 2 charged by the second voltage (400V) and the first voltage (800V) boosted by the three-phase motor 3 and the inverter 5, so a switch component equivalent to the second contactor VS / C of the first embodiment is not required.

[0128] In the second embodiment, the first to third semiconductor switches S / C_A, S / C_B, S / C_C are examples of the first switch unit, and the fifth contactor QC / C_C is an example of the second switch unit, which is the same as the first embodiment, but different from the first embodiment in that the first contactor M / C is an example of the third switch unit.

[0129] In the power storage system 1 of the second embodiment, the third contactor QC / C_A, the fourth contactor QC / C_B, the fifth contactor QC / C_C, the second voltage sensor V_BAT, and the third voltage sensor V_QC are arranged in the battery 2 .

[0130] Next, refer to Figures 15 to 20 The operation of the power storage system 1 according to the second embodiment will be described.

[0131] Fig.15 is a diagram showing the flow of current when an electric vehicle equipped with the power storage system 1 according to the second embodiment is traveling (800 V drive), Fig.18 This is a diagram showing an operation sequence when an electric vehicle equipped with the power storage system 1 according to the second embodiment is traveling (800 V drive).

[0132] When the ignition switch IG of the electric vehicle is turned on, the control unit 10 turns on the first contactor M / C, and then turns the first semiconductor switch S / C_A to a continuously turned-on state through an intermittent on period based on PWM control, so that the circuit in the battery 2 is connected in the first voltage state (800V). As a result, the first smoothing capacitor C1 is precharged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase. And when the precharging of the first smoothing capacitor C1 is completed, the electric vehicle can travel. At this time, the auxiliary machine 4 is connected to the power supply circuit 11P, 11N via the auxiliary machine drive circuit 12P, 12N, and is driven by the first voltage (800V) supplied from the battery 2.

[0133] On the other hand, when the ignition switch IG is turned off, the control unit 10 first disconnects the first contactor M / C and checks the detection voltage value of the first voltage sensor V_PIN. If the detection voltage value of the first voltage sensor V_PIN does not decrease due to the discharge of the first smoothing capacitor C1, the control unit 10 determines that the first contactor M / C is faulty and issues an abnormality notification.

[0134] When the control unit 10 determines that the first contactor M / C has no fault, the first semiconductor switch S / C_A is turned off at the time when the discharge of the first smoothing capacitor C1 is completed to check the detection voltage value of the second voltage sensor V_BAT. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C has a fault and issues an abnormality notification.

[0135] When the control unit 10 determines that the first to third semiconductor switches S / C_A, S / C_B, and S / C_C are not faulty, the control unit 10 ends the operation sequence during driving.

[0136] Fig.16 1 is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the second embodiment is charged at the first voltage (800 V charging). Fig.19 This is a diagram showing an operation sequence during first voltage charging (800 V charging) of an electric vehicle equipped with the power storage system 1 according to the second embodiment.

[0137] If the charging plug is connected to the charging terminals 131P and 131N, the control unit 10 performs CAN communication with the charging equipment to identify the charging voltage. When the charging voltage is the first voltage (800V), the control unit 10 turns on the first contactor M / C, and then turns the first semiconductor switch S / C_A to a continuously turned-on state through an intermittent on period based on PWM control, so that the circuit in the battery 2 is connected under the first voltage state (800V). As a result, the first smoothing capacitor C1 is pre-charged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase. Then, when the pre-charging of the first smoothing capacitor C1 is completed, the battery 2 becomes a state where it can start charging from the first voltage (800V).

[0138] After that, the control unit 10 turns on the third contactor QC / C_A and the fourth contactor QC / C_B to start charging the battery 2 with the first voltage (800 V). At this time, the auxiliary machine 4 is connected to the DC power supply circuits 13P and 13N via the auxiliary machine drive circuits 12P and 12N and the first contactor M / C, and is driven by the first voltage (800 V) supplied from the charging device.

[0139] On the other hand, when the control unit 10 determines that the input of the charging stop signal is received, the third contactor QC / C_A and the fourth contactor QC / C_B are disconnected, and the detection voltage value of the third voltage sensor V_QC is checked. If the detection voltage value of the third voltage sensor V_QC does not decrease, the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B have failed, and issues an abnormality notification.

[0140] When the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B are not faulty, the control unit 10 disconnects the first contactor M / C and checks the detection voltage value of the first voltage sensor V_PIN. When the detection voltage value of the first voltage sensor V_PIN does not decrease due to the discharge of the first smoothing capacitor C1, the control unit 10 determines that the first contactor M / C is faulty and issues an abnormality notification.

[0141] When the control unit 10 determines that the first contactor M / C has no fault, the first semiconductor switch S / C_A is turned off at the time when the discharge of the first smoothing capacitor C1 is completed to check the detection voltage value of the second voltage sensor V_BAT. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C has a fault and issues an abnormality notification.

[0142] When the control unit 10 determines that the first to third semiconductor switches S / C_A, S / C_B, and S / C_C are not faulty, the control unit 10 ends the operation sequence during the first voltage (800 V) charging.

[0143] Fig.17 1 is a diagram showing the flow of current when the electric vehicle equipped with the power storage system 1 according to the second embodiment is charged at the second voltage (400 V charging). Fig. 20 This is a diagram showing an operation sequence during second voltage charging (400 V charging) of an electric vehicle equipped with the power storage system 1 according to the second embodiment.

[0144] If the charging plug is connected to the charging terminals 131P and 131N, the control unit 10 performs CAN communication with the charging equipment to identify the charging voltage. When the charging voltage is the second voltage (400V), the control unit 10 turns on the fifth contactor QC / C_C, and then turns the second semiconductor switch S / C_B and the third semiconductor switch S / C_C into a continuous on state through an intermittent on period based on PWM control, so that the circuit in the battery 2 is connected at the second voltage state (400V). As a result, the first smoothing capacitor C1 is precharged, and the detection voltage values ​​of the first voltage sensor V_PIN and the second voltage sensor V_BAT gradually increase.

[0145] In addition, the control unit 10 turns on the third contactor QC / C_A and the fourth contactor QC / C_B after activating the boost circuit composed of the three-phase motor 3 and the inverter 5. As a result, the battery 2 is in a state where it can start charging with the second voltage (400V). In addition, the three-phase motor 3 and the inverter 5 connected to the DC power supply circuits 13P and 13N via the branch circuit 14 can boost the second voltage (400V) supplied from the charging device to the first voltage (800V) to drive the auxiliary machine 4.

[0146] On the other hand, when the control unit 10 determines that the input of the charging stop signal is received, the third contactor QC / C_A and the fourth contactor QC / C_B are disconnected, and the detection voltage value of the third voltage sensor V_QC is checked. If the detection voltage value of the third voltage sensor V_QC does not decrease, the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B have failed, and issues an abnormality notification.

[0147] When the control unit 10 determines that the third contactor QC / C_A and the fourth contactor QC / C_B are not faulty, the control unit 10 stops the boosting of the three-phase motor 3 and the inverter 5, disconnects the fifth contactor QC / C_C, and checks the detection voltage value of the first voltage sensor V_PIN. When the detection voltage value of the first voltage sensor V_PIN does not decrease, the control unit 10 determines that the fifth contactor QC / C_C is faulty and issues an abnormality notification.

[0148] When the control unit 10 determines that the fifth contactor QC / C_C has no fault, the second semiconductor switch S / C_B and the third semiconductor switch S / C_C are turned off, and the detection voltage value of the second voltage sensor V_BAT is checked. When the detection voltage value of the second voltage sensor V_BAT does not decrease, the control unit 10 determines that one of the first to third semiconductor switches S / C_A, S / C_B, and S / C_C has a fault, and issues an abnormality notification.

[0149] When the control unit 10 determines that the first to third semiconductor switches S / C_A, S / C_B, and S / C_C are not faulty, the control unit 10 ends the operation sequence during the second voltage (400 V) charging.

[0150] Next, a modification of the power storage system 1 of the first embodiment will be described. Note that the same reference numerals as those of the first embodiment are used for the same configurations as those of the first embodiment, and description thereof is omitted, and only the modified configurations will be described.

[0151] Fig.21 It is a diagram showing a configuration of a modified example of the power storage system 1 according to the first embodiment.

[0152] exist Figure 1 In the power storage system 1 of the first embodiment shown in FIG. 1 , the first contactor M / C is arranged at the end of the positive electrode side of the battery 2, and the current breaker FUSE is arranged at the end of the negative electrode side of the battery 2. However, in this modification, as shown in FIG. Fig.21 As shown, the first contactor M / C is arranged on the negative electrode side of the battery 2, and the current breaker FUSE is arranged on the positive electrode side of the battery 2. In addition, as a structure of the battery 2, a second contactor VS / C, a third contactor QC / C_A, a fourth contactor QC / C_B, a fifth contactor QC / C_C, a third voltage sensor V_QC, and a second voltage sensor V_BAT are arranged closer to the end side than the first contactor M / C and the current breaker FUSE.

[0153] exist Figure 1 In the power storage system 1 of the first embodiment shown, when the power supply of the storage battery 2 is cut off when the storage battery 2 fails, in other words, when the power supply to the outside of the storage battery 2 is cut off, it is necessary to disconnect the first contactor M / C arranged at the end of the positive electrode side of the storage battery 2 and disconnect the current breaker FUSE arranged at the end of the negative electrode side of the storage battery 2. Once the current breaker FUSE is disconnected, it is necessary to replace it.

[0154] In this modification, when the power supply of the battery 2 is cut off, the second contactor VS / C and the third contactor QC / C_A, which are arranged on the positive side of the battery 2 and closer to the end side than the circuit breaker FUSE, are opened, and the first contactor M / C, which is arranged on the negative side of the battery 2, is opened, thereby cutting off the power supply of the battery 2 without cutting off the circuit breaker FUSE. In this way, according to this modification, when it is necessary to cut off the power supply of the battery 2, it can be achieved by the on-off control of the contactor, so the control can be simplified, and the circuit breaker FUSE does not need to be replaced.

[0155] Above, various embodiments have been described with reference to the accompanying drawings, but the present invention is certainly not limited to such examples. It should be understood by those skilled in the art that various variations or modifications can be conceived within the scope of the technical solution, and these variations or modifications certainly also belong to the technical scope of the present invention. In addition, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined within the scope of the gist of the invention.

[0156] For example, in the above-described embodiment, CAN communication is performed between the control unit 10 and the charging equipment, but the communication method is not limited to CAN communication, and any communication method can be adopted.

[0157] In this specification, at least the following matters are described. In addition, although the corresponding components and the like in the above-mentioned embodiment are shown in brackets, the present invention is not limited thereto.

[0158] (1) A power storage system comprising:

[0159] a storage battery (storage battery 2) including a first storage unit (first storage unit 21), a second storage unit (second storage unit 22), and a first switch unit capable of switching between a first voltage state in which the first storage unit and the second storage unit are connected in series and can be charged at a first voltage and a second voltage state in which the first storage unit and the second storage unit are connected in parallel and can be charged at a second voltage;

[0160] a three-phase motor (three-phase motor 3) having three-phase coils (coils 32U, 32V, 32W) connected at a neutral point (neutral point 31) and driven by electric power supplied from the battery;

[0161] an inverter (inverter 5 ) connected to a power transmission path (power supply circuits 11P, 11N) between the battery and the three-phase motor;

[0162] a DC power supply circuit (DC power supply circuit 13P, 13N) connected to a first connection portion (connection portion 111P, 111N) located on a power transmission path between the inverter and the battery;

[0163] a capacitor (a first smoothing capacitor C1 ) provided on the electric power transmission path between the battery and the three-phase motor; and

[0164] a branch circuit (branch circuit 14) branched from the DC power supply circuit on the positive side and connected to a coil of any one phase among the three-phase coils,

[0165] The first switch unit includes semiconductor switches (a first semiconductor switch S / C_A, a second semiconductor switch S / C_B, and a third semiconductor switch S / C_C).

[0166] According to (1), regardless of whether the external charging device is a system that charges at a first voltage or a system that charges at a second voltage, by switching the connection mode between the first power storage unit and the second power storage unit using the first switch unit, charging can be performed appropriately according to the voltage state of the charging device. That is, charging can be performed without passing through a voltage converter, thereby avoiding the deterioration of efficiency caused by the voltage converter, and eliminating the need for a voltage converter for charging.

[0167] In addition, since the DC power supply circuit on the positive side connected to the connection portion on the power transmission path between the inverter and the battery has a branch circuit connected to the coil of any phase of the three-phase motor, the three-phase motor and the inverter can be used for voltage conversion. Therefore, even if the voltage state of the charging equipment and the operating voltage of the auxiliary machine are different, a dedicated voltage converter is not required, and the manufacturing cost can be suppressed.

[0168] Furthermore, by configuring the first switch unit to include a semiconductor switch, compared to a configuration including a contactor, a precharge circuit can be eliminated, thereby reducing the size and weight of the battery circuit.

[0169] (2) The power storage system according to (1), wherein:

[0170] The power storage system further includes a control unit (control unit 10) that controls the first switch unit.

[0171] The control unit performs PWM control on the first switching unit during precharging of the capacitor.

[0172] According to (2), the capacitor can be precharged by performing PWM control on the semiconductor switch.

[0173] (3) The power storage system according to (1) or (2), wherein:

[0174] The battery has:

[0175] a positive electrode side path (positive electrode side path K1 ) of the first power storage unit;

[0176] a positive electrode side path of the second power storage unit (positive electrode side path K2);

[0177] a positive electrode side node (positive electrode side node N1) connecting the positive electrode side path of the first power storage unit and the positive electrode side path of the second power storage unit in parallel;

[0178] a negative electrode side path (negative electrode side path K3 ) of the first power storage unit;

[0179] a negative electrode side path of the second power storage unit (negative electrode side path K4);

[0180] a negative electrode side node (negative electrode side node N2) connecting the negative electrode side path of the first power storage unit and the negative electrode side path of the second power storage unit in parallel;

[0181] a series connection path (series connection path K5 ) connecting the negative electrode side path of the first power storage unit and the positive electrode side path of the second power storage unit;

[0182] a negative electrode side connection node (negative electrode side connection node N3) connecting the series connection path and the negative electrode side path of the first power storage unit; and

[0183] a positive electrode side connection node (positive electrode side connection node N4) connecting the series connection path and the positive electrode side path of the second power storage unit,

[0184] The first switch unit comprises:

[0185] A first semiconductor switch (a first semiconductor switch S / C_A), which is arranged on the series connection path;

[0186] A second semiconductor switch (a second semiconductor switch S / C_B) is arranged between the positive electrode side node and the positive electrode side connection node;

[0187] a third semiconductor switch (third semiconductor switch S / C_C), which is arranged between the cathode side node and the cathode side connection node;

[0188] a first reactor (first reactor L1 ) disposed between the positive electrode side connection node and the positive electrode of the second power storage unit; and

[0189] The second reactor (second reactor L2 ) is arranged between the negative electrode side connecting node and the negative electrode of the first power storage unit.

[0190] According to (3), when starting at the first voltage, two reactors are connected in series, and when starting at the second voltage, one reactor is connected to each path, and the reactors are appropriately arranged according to the voltage.

[0191] (4) The power storage system according to (1) or (2), wherein:

[0192] The branch circuit is connected to a coil of any one phase among the three-phase coils at a second connection portion (connection portion 34 ) via a second switch portion (fifth contactor QC / C_C).

[0193] According to (4), when the voltage conversion is not performed by the three-phase motor, that is, when the coil of the three-phase motor is not used as a transformer, the connection to the second connection portion can be cut off.

[0194] (5) The power storage system according to (1) or (2), wherein:

[0195] The power storage system further comprises:

[0196] an auxiliary machine (auxiliary machine 4 ) that can be driven by direct current power from the battery and an external power source; and

[0197] an auxiliary machine drive circuit (auxiliary machine drive circuit 12P, 12N) connected to the power transmission path between the inverter and the first connection portion, and supplying power to the auxiliary machine;

[0198] The auxiliary machine operates at the first voltage.

[0199] According to (5), no voltage conversion is required during driving and charging at the first voltage.

[0200] (6) The power storage system according to (5), wherein:

[0201] The auxiliary machine is connected to the battery via a third switch unit (the second contactor VS / C of the first embodiment, the first contactor M / C of the second embodiment).

[0202] According to (6), when the voltage conversion is performed using a three-phase motor, that is, when the coil of the three-phase motor is used as a transformer, the third switch unit can be used to separate the portion in the first voltage state from the portion in the second voltage state.

[0203] (7) The power storage system according to (1) or (2), wherein:

[0204] The power storage system further includes a control unit (control unit 10) for controlling the first switch unit and the inverter.

[0205] The control unit increases the voltage supplied from the branch circuit to the three-phase motor to the first voltage using the inverter when charging the battery at the second voltage.

[0206] According to (7), voltage conversion can be performed using a three-phase motor and an inverter, so a voltage converter for auxiliary equipment can be eliminated.

Claims

1. A power storage system, wherein: The power storage system comprises: A storage battery comprising a first power storage unit, a second power storage unit, and a first switch unit capable of switching between a first voltage state and a second voltage state, wherein the first power storage unit and the second power storage unit are connected in series and can be charged at a first voltage, and the second voltage state wherein the first power storage unit and the second power storage unit are connected in parallel and can be charged at a second voltage; a three-phase motor having three-phase coils connected at a neutral point and driven by electric power supplied from the battery; an inverter connected to a power transmission path between the battery and the three-phase motor; a DC power supply circuit connected to a first connection portion on a power transmission path between the inverter and the battery; a capacitor provided on the power transmission path between the battery and the three-phase motor; and a branch circuit which branches from the DC power supply circuit on the positive side and is connected to a coil of any one phase among the three-phase coils, The first switch unit includes a semiconductor switch.

2. The power storage system according to claim 1, wherein: The power storage system further includes a control unit that controls the first switch unit. The control unit performs PWM control on the first switching unit during precharging of the capacitor.

3. The power storage system according to claim 1 or 2, wherein: The battery has: a positive electrode side path of the first power storage unit; a positive electrode side path of the second power storage unit; a positive electrode side node connecting the positive electrode side path of the first power storage unit and the positive electrode side path of the second power storage unit in parallel; a negative electrode side path of the first power storage unit; a negative electrode side path of the second power storage unit; a negative electrode side node connecting the negative electrode side path of the first power storage unit and the negative electrode side path of the second power storage unit in parallel; a series connection path connecting a negative electrode side path of the first power storage unit and a positive electrode side path of the second power storage unit; a negative electrode side connection node connecting the series connection path and a negative electrode side path of the first power storage unit; and a positive electrode side connection node connecting the series connection path and the positive electrode side path of the second power storage unit, The first switch unit comprises: A first semiconductor switch, which is arranged on the series connection path; a second semiconductor switch disposed between the positive electrode side node and the positive electrode side connection node; a third semiconductor switch disposed between the cathode-side node and the cathode-side connection node; a first reactor disposed between the positive electrode side connection node and the positive electrode of the second power storage unit; and The second reactor is disposed between the negative electrode side connection node and the negative electrode of the first power storage unit.

4. The power storage system according to claim 1 or 2, wherein: The branch circuit is connected to a coil of any one phase among the three-phase coils at a second connection portion via a second switch portion.

5. The power storage system according to claim 1 or 2, wherein: The power storage system further comprises: an auxiliary machine capable of being driven by direct current power from the battery and an external power source; and an auxiliary machine drive circuit connected to a power transmission path between the inverter and the first connection portion, and supplying power to the auxiliary machine; The auxiliary machine operates at the first voltage.

6. The power storage system according to claim 5, wherein: The auxiliary machine is connected to the battery via a third switch unit.

7. The power storage system according to claim 1 or 2, wherein: The power storage system further includes a control unit that controls the first switch unit and the inverter. The control unit increases the voltage supplied from the branch circuit to the three-phase motor to the first voltage using the inverter when charging the battery at the second voltage.

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