WO2024095381A1

WO2024095381A1 - Switching unit and system

Info

Publication number: WO2024095381A1
Application number: PCT/JP2022/040941
Authority: WO
Inventors: 孝佳板東; 将義廣田
Original assignee: 住友電気工業株式会社; 住友電装株式会社; 株式会社オートネットワーク技術研究所
Priority date: 2022-11-02
Filing date: 2022-11-02
Publication date: 2024-05-10

Abstract

This switching unit comprises: a parallel-connection switch that causes a first storage battery and a second storage battery to be in a parallel-connection state; a serial-connection switch that causes the first storage battery and the second storage battery to be in a serial-connection state; and a first voltage sensor that measures voltage between both terminals of each of the first storage battery and the second storage battery that have been caused to be in the parallel-connection state or in the serial-connection state.

Description

Switching Unit and System

This disclosure relates to a switching unit and system.

　Systems capable of switching between series and parallel connection of multiple storage batteries are known. For example, the following Patent Document 1 discloses a charging device incorporated into a system that includes two storage batteries and two inverters and supplies power to an open-end winding motor. This charging device includes three relays for connecting the two storage batteries in series or in parallel. The charging device uses the three relays to connect the two storage batteries in series or in parallel, and charges these two storage batteries.

JP 2020-88913 A

The switching unit according to one aspect of the present disclosure includes a parallel connection switch that connects the first storage battery and the second storage battery in a parallel connection state, a series connection switch that connects the first storage battery and the second storage battery in a series connection state, and a first voltage sensor that measures the voltage between both terminals of the first storage battery and the second storage battery that are connected in parallel or in series.

A system according to another aspect of the present disclosure includes a first storage battery and a second storage battery, and a switching unit that switches the connection state of the first storage battery and the second storage battery, the switching unit including a parallel connection switch that connects the first storage battery and the second storage battery in a parallel connection state, a series connection switch that connects the first storage battery and the second storage battery in a series connection state, and a voltage sensor that measures the voltage between both terminals of the first storage battery and the second storage battery that are connected in parallel or in series.

FIG. 1 is a block diagram illustrating a power conversion system including a switching unit according to an embodiment of the present disclosure. FIG. 2 is a circuit diagram showing a specific configuration of the power conversion system shown in FIG. FIG. 3 is a circuit diagram showing a state in which two storage batteries are connected in series in the power conversion system shown in FIG. FIG. 4 is a circuit diagram showing a state in which two storage batteries are connected in parallel in the power conversion system shown in FIG. FIG. 5 is a circuit diagram showing a configuration of a power conversion system including a switching unit different from that in FIG.

[Problem to be solved by this disclosure]
In an electric vehicle (hereinafter referred to as EV (Electric Vehicle)), power is normally supplied from a storage battery to a motor by a single inverter. The motor uses a closed-end winding motor in which one end of each winding is connected. For an EV with such a configuration, the method disclosed in Patent Document 1, that is, a method of driving a motor with open-end windings using two storage batteries and two inverters, has the advantage that the TN characteristics, which represent the torque and rotation speed of the motor, can be improved and the driving range can be expanded. However, when the charging device of Patent Document 1 is applied to a system with such a method, there is a problem that the influence on the peripheral devices in the vehicle is large, such as the need to change the peripheral devices.

Therefore, the present disclosure aims to provide a switching unit and system that can reduce the impact on peripheral devices within a vehicle.

[Effects of the present disclosure]
According to the present disclosure, it is possible to provide a switching unit and system that can reduce the effect on peripheral devices in a vehicle.

[Description of the embodiments of the present disclosure]
The contents of the embodiments of the present disclosure will be listed and described below. At least some of the embodiments described below may be combined in any combination.

(1) The switching unit according to the first aspect of the present disclosure includes a parallel connection switch that connects the first storage battery and the second storage battery in a parallel connection state, a series connection switch that connects the first storage battery and the second storage battery in a series connection state, and a first voltage sensor that measures the voltage between both terminals of the first storage battery and the second storage battery that are connected in parallel or in series. This reduces the impact on peripheral devices in the vehicle.

(2) In the above (1), the switching unit may further include a control unit that controls the on/off of the parallel connection switch and the series connection switch. This allows the first storage battery and the second storage battery to be efficiently connected in parallel or in series. In addition, the amount of electrical wiring between the switching unit and the outside can be reduced, reducing the impact of noise on surrounding devices.

(3) In the above (1) or (2), the switching unit may further include a first connection switch for connecting a charger for charging the first storage battery and the second storage battery to both terminals of the first storage battery and the second storage battery that are connected in parallel or series. This makes it possible to connect the external charger and the storage battery after confirming that the first storage battery and the second storage battery are connected in parallel or series.

(4) In any one of (1) to (3) above, when the first storage battery and the second storage battery are charged in a parallel connection state, the parallel connection switch may be turned on and the series connection switch may be turned off, and when the first storage battery and the second storage battery are charged in a series connection state, the series connection switch may be turned on and the parallel connection switch may be turned off. This ensures that the first storage battery and the second storage battery are connected in parallel or in series.

(5) In any one of (1) to (4) above, the switching unit may further include a plurality of second connection switches for connecting the switching unit to the first storage battery and the second storage battery. This improves the ease of installation of the switching unit in the EV.

(6) In the above (5), the switching unit may further include a circuit breaker connected in series with one of the second connection switches. This makes it possible to prevent excessive current from flowing and protect the storage battery.

(7) In any one of (1) to (6) above, the switching unit may further include a second voltage sensor that detects the voltage between both terminals of each of the first storage battery and the second storage battery. This makes it possible to determine the difference in voltage between the first storage battery and the second storage battery, and if the difference is large (e.g., a difference equal to or greater than a predetermined threshold), the first storage battery and the second storage battery can be balanced, for example, by making the voltages of the first storage battery and the second storage battery equal.

(8) In any one of (1) to (7) above, the switching unit may be disposed in a housing that houses the first storage battery and the second storage battery. This allows the first storage battery and the second storage battery to be configured integrally with the parallel connection switch and the direct connection switch, making handling easier and, for example, improving workability when mounting the device on a vehicle. In addition, the layout design of peripheral devices of the switching unit becomes easier.

(9) In any one of (1) to (8) above, when the first storage battery and the second storage battery are discharged, the parallel connection switch may be turned on and the series connection switch may be turned off. This allows power of an appropriate voltage to be supplied.

(10) In any one of (1) to (9) above, the first storage battery supplies power to a first inverter for driving the motor, the second storage battery supplies power to a second inverter for driving the motor, and the switching unit switches the connection state of the first storage battery and the second storage battery so that current flows bypassing the first inverter and the second inverter. This makes it possible to realize an EV equipped with two storage batteries and two inverters, and, for example, a motor with open-end windings, thereby expanding the driving range.

(11) In any one of (1) to (10) above, the switching unit may be mounted on a vehicle, and the parallel connection switch and the series connection switch may switch the connection state of the first storage battery and the second storage battery to a series connection state or a parallel connection state according to the voltage of the storage battery mounted on the other vehicle when supplying power from the first storage battery and the second storage battery mounted on the vehicle to a storage battery mounted on another vehicle other than the vehicle. This allows the storage battery of the other vehicle to be charged with an appropriate voltage according to the voltage of the storage battery of the other vehicle.

(12) A system according to a second aspect of the present disclosure includes a first storage battery and a second storage battery, and a switching unit that switches the connection state of the first storage battery and the second storage battery, and the switching unit includes a parallel connection switch that connects the first storage battery and the second storage battery to a parallel connection state, a series connection switch that connects the first storage battery and the second storage battery to a series connection state, and a voltage sensor that measures the voltage between both terminals of the first storage battery and the second storage battery that are connected in parallel or in series. This reduces the impact on peripheral devices in the vehicle.

[Details of the embodiment of the present disclosure]
In the following embodiments, the same parts are denoted by the same reference numerals, and their names and functions are also the same, so detailed description thereof will not be repeated.

1, the switching unit 100 according to the embodiment of the present disclosure includes a first parallel connection switch RY1, a series connection switch RY2, a second parallel connection switch RY3, a voltage sensor 106, and a control unit 120. The switching unit 100 is integrally formed by accommodating the first parallel connection switch RY1, the series connection switch RY2, the second parallel connection switch RY3, the voltage sensor 106, and the control unit 120 in a housing made of, for example, resin. The switching unit 100 constitutes a power conversion system together with the first battery unit 102, the second battery unit 104, the voltage sensor 108, the voltage sensor 110, the first inverter 130, the second inverter 132, and the inverter control unit 134. That is, the power conversion system is a double-ended inverter system that drives a motor using two battery units and two inverters. The power conversion system is installed in the EV and controlled by a vehicle ECU (Electric Control Unit) 202, supplying power to a motor 140 and high-voltage auxiliary equipment 210 for driving the EV. An external charger is connected to a terminal section 212 of the power conversion system, and the power conversion system charges the first battery unit 102 and the second battery unit 104.

The first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, which constitute the switching unit 100, short-circuit (hereinafter referred to as "on") or open (hereinafter referred to as "off") both terminals of each switch under the control of the control unit 120. The short-circuit control and the open control are also collectively referred to as on-off control. Each of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 is, for example, a relay. By using a relay, as described later, multiple batteries can be efficiently connected in parallel or in series under the control of the control unit 120. Each of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 may be a semiconductor element having a switching function, such as a FET (Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

Under the control of the vehicle ECU 202, the control unit 120 outputs a control signal (see the three dashed arrows output from the control unit 120) and controls the on/off of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3. The control unit 120 can efficiently connect the first battery unit 102 and the second battery unit 104 in parallel or series. The control unit 120 can be realized by a logic circuit. That is, the control unit 120 can be realized by a semiconductor integrated circuit such as an ASIC (Application Specific Integrated Circuit) or a programmable logic device (such as an FPGA (Field Programmable Gate Array)). The control unit 120 may be configured as a control device (computer) including a computing element (CPU: Central Processing Unit) and a storage element (memory), etc.

The voltage sensor 106 measures the voltage between both terminals of the first battery unit 102 and the second battery unit 104, which are connected in parallel or in series. The voltage measured by the voltage sensor 106 (i.e., an electrical signal corresponding to the measured voltage) is input to the control unit 120. This allows the control unit 120 to determine whether the first battery unit 102 and the second battery unit 104 are connected in parallel or in series. That is, after the control unit 120 performs on/off control of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, it can confirm that the first battery unit 102 and the second battery unit 104 are connected as controlled.

The power conversion system further includes a system main relay RY4, ..., a system main relay RY7, a DC relay (Direct Cut Relay) DCR1, and a DC relay DCR2. Each of the system main relays RY4, ..., the system main relay RY7, the DC relay DCR1, and the DC relay DCR2 turns on or off both terminals under the control of the vehicle ECU 202. When the system main relays RY4, ..., and the system main relay RY7 are turned on, the switching unit 100 is connected to the first battery unit 102 and the second battery unit 104. When an external charger is connected to the terminal portion 212, the DC relay DCR1 and the DC relay DCR2 are turned on, and the switching unit 100 is connected to the external charger. Each of the system main relays RY4, ..., the system main relay RY7, the DC relay DCR1, and the DC relay DCR2 is, for example, a relay. Each of the system main relays RY4, ..., system main relay RY7, DC relay DCR1, and DC relay DCR2 may be a semiconductor element having a switching function such as an FET or an IGBT.

The power conversion system further includes a circuit breaker Fu1 and a circuit breaker Fu2. The circuit breaker Fu1 is connected in series to a system main relay RY4 connected to the first battery unit 102. The circuit breaker Fu2 is connected in series to a system main relay RY6 connected to the second battery unit 104. The circuit breakers Fu1 and Fu2 connect their respective terminals with a low resistance value, and have the function of opening the connection between the respective terminals when a large current of a predetermined value or more flows. The circuit breakers Fu1 and Fu2 are, for example, fuses. When a large current flows and the fuse becomes hot, it melts and opens the connection between the two terminals. Therefore, it is possible to prevent an excessive current from flowing, and to protect the first battery unit 102 and the second battery unit 104. The circuit breaker Fu1 may be connected in series to the system main relay RY5. The circuit breaker Fu2 may be connected in series to the system main relay RY7.

The first battery unit 102 and the second battery unit 104 are units of the same specifications, composed of chargeable and dischargeable storage batteries. The first battery unit 102 and the second battery unit 104 include, for example, lithium ion batteries. The first battery unit 102 and the second battery unit 104 are, for example, battery units of 400V specifications (i.e., rated charging voltage and output voltage are 400V). Note that the battery unit is not limited to being composed of multiple batteries, and may also be composed of a single battery.

Each of the first battery unit 102 and the second battery unit 104 is provided with a battery management system (BMS) (not shown). The battery management system has functions such as preventing overcharging and overdischarging of each battery unit, preventing overcurrent, and calculating the remaining capacity of the battery (SOC: State of Charge).

The first inverter 130 and the second inverter 132 convert the DC power supplied from the first battery unit 102 and the second battery unit 104 into AC power and supply it to the motor 140. At this time, the control unit 120 turns off the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3. Each of the first inverter 130 and the second inverter 132 includes a plurality of switching elements as described below. The power conversion system shown in FIG. 1 further includes an inverter control unit 134 for controlling the on/off of each switching element constituting the first inverter 130 and the second inverter 132 in response to an instruction from the vehicle ECU 202. The motor 140 is a three-phase AC motor driven by AC power. In this embodiment, the motor 140 is a motor with open-end windings as described below.

The power conversion system further includes a voltage sensor 108 and a voltage sensor 110. The voltage sensor 108 measures the voltage between both terminals of the first battery unit 102. The voltage sensor 110 measures the voltage between both terminals of the second battery unit 104. The voltages detected by the voltage sensors 108 and 110 (i.e., electrical signals corresponding to the detected voltages) are input to the inverter control unit 134 and used to control the first inverter 130 and the second inverter 132.

The high-voltage auxiliary equipment 210 is a high-voltage load of the auxiliary equipment system, and is supplied with power from the power conversion system. The high-voltage auxiliary equipment 210 includes, for example, an air conditioner, a heater, and a step-down DC/DC converter. The step-down DC/DC converter steps down the voltage from the first battery unit 102 when supplying power to a low-voltage (e.g., 12 V) battery.

Referring to FIG. 2, each of the first inverter 130 and the second inverter 132 is composed of a plurality of switching elements. FIG. 2 explicitly shows that the motor 140 is a motor with open-end windings in which the ends of each winding are not connected but are pulled out to the outside. FIG. 2 does not show the inverter control unit 134, high-voltage auxiliary equipment 210, and terminal unit 212 shown in FIG. 1, but shows the external charger 200 connected to terminal unit 212. The other components are the same as those shown in FIG. 1, except that their positions are different from those shown in FIG. 1.

The first inverter 130 is a three-phase inverter that converts DC power from the first battery unit 102 into three-phase AC power. The first inverter 130 includes six switching elements Q1, ..., and switching element Q6. A freewheel diode is connected to each of the switching elements Q1, ..., and switching element Q6. Each of the switching elements Q1, ..., and switching element Q6 is, for example, an FET. For the purpose of protection from surge currents, etc., the switching elements and the freewheel diodes are connected in parallel so that their forward bias directions are opposite to each other. Each of the switching elements Q1, ..., and switching element Q6 may be, for example, an IGBT.

Switching elements Q1, ... and switching element Q6 form the upper and lower arms of the U phase, V phase, and W phase. For example, switching element Q1, which is the upper arm element, and switching element Q2, which is the lower arm element, are connected in series to form the upper and lower arms of the U phase. Switching element Q3, which is the upper arm element, and switching element Q4, which is the lower arm element, are connected in series to form the upper and lower arms of the V phase. Switching element Q5, which is the upper arm element, and switching element Q6, which is the lower arm element, are connected in series to form the upper and lower arms of the W phase.

The second inverter 132 is configured in the same manner as the first inverter 130. That is, the second inverter 132 is a three-phase inverter that converts DC power from the second battery unit 104 into three-phase AC power. The second inverter 132 includes six switching elements Q7, ..., and switching element Q12. A freewheel diode is connected to each of the switching elements Q7, ..., and switching element Q12. Each of the switching elements Q7, ..., and switching element Q12 is, for example, an FET. The switching elements and the freewheel diodes are connected in parallel so that their forward bias directions are opposite to each other. Each of the switching elements Q7, ..., and switching element Q12 may be, for example, an IGBT.

Switching elements Q7, ... and switching element Q12 form the upper and lower arms of the U phase, V phase, and W phase. For example, switching element Q7, which is the upper arm element, and switching element Q8, which is the lower arm element, are connected in series to form the upper and lower arms of the U phase. Switching element Q9, which is the upper arm element, and switching element Q10, which is the lower arm element, are connected in series to form the upper and lower arms of the V phase. Switching element Q11, which is the upper arm element, and switching element Q12, which is the lower arm element, are connected in series to form the upper and lower arms of the W phase.

Motor 140 includes three-phase windings (U-phase winding, V-phase winding, and W-phase winding). Both terminals of each winding are connected to first inverter 130 and second inverter 132. That is, both terminals of the U-phase winding of motor 140 are connected to the connection node of switching element Q1 and switching element Q2 that constitute the upper and lower arms of the U-phase of first inverter 130, and the connection node of switching element Q7 and switching element Q8 that constitute the upper and lower arms of the U-phase of second inverter 132. Both terminals of the V-phase winding of motor 140 are connected to the connection node of switching element Q3 and switching element Q4 that constitute the upper and lower arms of the V-phase of first inverter 130, and the connection node of switching element Q9 and switching element Q10 that constitute the upper and lower arms of the V-phase of second inverter 132. Both terminals of the W-phase winding of the motor 140 are connected to the connection node of the switching elements Q5 and Q6 that constitute the upper and lower arms of the W-phase of the first inverter 130, and the connection node of the switching elements Q11 and Q12 that constitute the upper and lower arms of the W-phase of the second inverter 132.

In this manner, the first inverter 130, the second inverter 132, and the motor 140 are configured, and the switching elements Q1, ..., and switching element Q12 constituting the first inverter 130 and the second inverter 132 are controlled by the inverter control unit 134, causing a current to flow through each winding of the motor 140 and driving the motor 140. As described above, the inverter control unit 134 receives instructions from the vehicle ECU 202 and controls the switching elements Q1, ..., and switching element Q12. For example, the first inverter 130 and the second inverter 132 are controlled by setting target values so that the power supplied from the first battery unit 102 to the motor 140 is equal to the power supplied from the second battery unit 104 to the motor 140.

The external charger 200 is a DC power source for charging the first battery unit 102 and the second battery unit 104. When a rapid charger (e.g., output 800V) is used as the external charger 200 to rapid charge the first battery unit 102 and the second battery unit 104, the first battery unit 102 and the second battery unit 104 are connected in series by the switching unit 100. When a normal charger (e.g., output 400V) is used as the external charger 200 to charge the first battery unit 102 and the second battery unit 104, the first battery unit 102 and the second battery unit 104 are connected in parallel by the switching unit 100.

As described above, by incorporating the first parallel connection switch RY1, the series connection switch RY2, the second parallel connection switch RY3, and the voltage sensor 106 into one switching unit 100, the influence on peripheral devices in the vehicle can be reduced. In addition, the voltage sensor 106 can reliably determine whether the first battery unit 102 and the second battery unit 104 are connected in parallel or in series. Therefore, safety is improved when charging with an external charger. In addition, the switching unit 100 switches the connection state of the first battery unit 102 and the second battery unit 104 so that the first inverter 130 and the second inverter 132 are bypassed, that is, the charging current is supplied without passing through the first inverter 130 and the second inverter 132. Therefore, an EV equipped with two battery units, two inverters, and a motor with open-end windings can be realized, and the driving range can be expanded.

The switching unit 100 is integrally formed including the control unit 120 that controls the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, so that the first battery unit 102 and the second battery unit 104 can be efficiently connected in parallel or in series. In addition, the amount of electrical wiring between the switching unit 100 and the vehicle ECU 202 can be reduced, reducing the impact of noise on surrounding devices.

As described above, the first inverter 130 and the second inverter 132 are controlled by setting a target value so that the power supplied from the first battery unit 102 to the motor 140 is equal to the power supplied from the second battery unit 104 to the motor 140. As a result, the capacity of the first battery unit 102 to which the high-voltage auxiliary device 210 is connected usually decreases faster than that of the second battery unit 104. Therefore, an imbalance in the remaining capacity occurs between the first battery unit 102 and the second battery unit 104. The power conversion system can determine the imbalance in the remaining capacity between the first battery unit 102 and the second battery unit 104, for example, by measuring the voltage with the voltage sensor 108 and the voltage sensor 110. Therefore, it is possible to supply power from one of the first battery unit 102 and the second battery unit 104 to the other, and balance the remaining capacity between the first battery unit 102 and the second battery unit 104.

If an abnormality occurs in one of the first battery unit 102 and the second battery unit 104 while the EV is running using the motor 140, the motor 140 may be driven by the other battery unit and its corresponding inverter. At this time, among the system main relays RY4, ... and RY7, the system main relays corresponding to the normal battery units are turned on, and the system main relays corresponding to the abnormal battery unit are turned off. In addition, the lower arm of the inverter corresponding to the abnormal battery unit is turned on, and the corresponding ends of the three windings of the motor 140 are connected to each other. An abnormality in the first battery unit 102 and the second battery unit 104 can be determined from the voltage values output from the

voltage sensors

108 and 110.

(Charging operation)
The operation of the first battery unit 102 and the second battery unit 104 during charging will be described. With reference to FIG. 3, when the first battery unit 102 and the second battery unit 104 are charged by a quick charger, the quick charger is connected to the terminal unit 212. At this time, the vehicle ECU 202 turns on the system main relays RY4, ..., and RY7, and then instructs the control unit 120 to control the on/off of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 so that the first battery unit 102 and the second battery unit 104 are in a series connection state. The control unit 120 turns on the series connection switch RY2 and maintains the first parallel connection switch RY1 and the second parallel connection switch RY3 in an off state in accordance with the instruction from the vehicle ECU 202. Note that the initial states of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 are off. The control unit 120 judges whether or not the voltage input from the voltage sensor 106 is the voltage (for example, about 800 V) when the first battery unit 102 and the second battery unit 104 are connected in series. When the control unit 120 judges that the voltage input from the voltage sensor 106 is the voltage when the first battery unit 102 and the second battery unit 104 are connected in series, it notifies the vehicle ECU 202 that the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 have been set as instructed. In response to this, the vehicle ECU 202 turns on the DC relays DCR1 and DCR2. As a result, the current supplied from the quick charger connected to the terminal unit 212 in FIG. 3 flows without passing through the first inverter 130 and the second inverter 132, as indicated by the thick dashed arrow, and the first battery unit 102 and the second battery unit 104 are charged.

If the control unit 120 determines that the voltage input from the voltage sensor 106 is not the voltage when the first battery unit 102 and the second battery unit 104 are connected in series, it notifies the vehicle ECU 202 of an abnormality. In response to this, the vehicle ECU 202 keeps the DC relays DCR1 and DCR2 off, and quick charging is not performed. The vehicle ECU 202 may issue an alarm or the like indicating the abnormality.

4, when the first battery unit 102 and the second battery unit 104 are normally charged, a normal charger is connected to the terminal section 212. At this time, the vehicle ECU 202 turns on the system main relays RY4, ..., and RY7, and then instructs the control section 120 to control the on/off of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 so that the first battery unit 102 and the second battery unit 104 are connected in parallel. The control section 120 turns on the first parallel connection switch RY1 and the second parallel connection switch RY3 and maintains the series connection switch RY2 off in accordance with the instruction from the vehicle ECU 202. The control section 120 determines whether the voltage input from the voltage sensor 106 is the voltage (e.g., about 400 V) when the first battery unit 102 and the second battery unit 104 are connected in parallel. When the control unit 120 determines that the voltage input from the voltage sensor 106 is the voltage when the first battery unit 102 and the second battery unit 104 are connected in parallel, it notifies the vehicle ECU 202 that the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 have been set as instructed. In response to this, the vehicle ECU 202 turns on the DC relays DCR1 and DCR2. As a result, the current supplied from the normal charger connected to the terminal unit 212 in FIG. 4 flows without passing through the first inverter 130 and the second inverter 132, as shown by the thick dashed arrow, and the first battery unit 102 and the second battery unit 104 are charged.

When the control unit 120 determines that the voltage input from the voltage sensor 106 is not the voltage when the first battery unit 102 and the second battery unit 104 are connected in parallel, it notifies the vehicle ECU 202 of an abnormality. In response to this, the vehicle ECU 202 keeps the DC relays DCR1 and DCR2 off, and normal charging is not performed. The vehicle ECU 202 may issue an alarm or the like indicating the abnormality.

The switching unit 100 configured in this manner can reliably determine whether the first battery unit 102 and the second battery unit 104 are connected in parallel or in series. For example, if any of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 does not operate normally during quick charging, a high voltage will be applied when the first battery unit 102 and the second battery unit 104 are not connected in series, damaging the first battery unit 102 and the second battery unit 104. By checking the voltage input from the voltage sensor 106, such an abnormality can be reliably avoided.

(Discharge operation)
The first battery unit 102 and the second battery unit 104 can be discharged to supply power to the outside from the terminal unit 212. In this case, the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 are controlled by the control unit 120 in the same manner as described above to place the first battery unit 102 and the second battery unit 104 in a series connection state or a parallel connection state. That is, the control unit 120 turns on the series connection switch RY2 and keeps the first parallel connection switch RY1 and the second parallel connection switch RY3 off, so that the first battery unit 102 and the second battery unit 104 connected in series can supply a high voltage (e.g., about 800 V) DC voltage. The control unit 120 turns on the first parallel connection switch RY1 and the second parallel connection switch RY3 and keeps the series connection switch RY2 off, so that the first battery unit 102 and the second battery unit 104 connected in parallel can supply a normal voltage (e.g., about 400 V) DC voltage. Therefore, power of an appropriate voltage can be supplied from the terminal portion 212 .

For example, power can be supplied from a power conversion system mounted on a vehicle to a battery unit mounted on another vehicle. In this case, it is preferable that the control unit 120 controls the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 so that the first battery unit 102 and the second battery unit 104 are connected in parallel or in series according to the voltage of the battery unit of the other vehicle. This allows the battery unit of the other vehicle to be charged with an appropriate voltage according to the voltage of the battery unit of the other vehicle. In order for the control unit 120 to know the voltage of the battery unit of the other vehicle, for example, a connection terminal that receives the output (i.e., a signal representing the measured voltage) of a voltage sensor that measures the voltage of the battery unit of the other vehicle may be provided in the terminal unit 212, and electrical wiring may be provided between the terminal unit 212 and the control unit 120.

In the above, the case where the switching unit 100 includes the first parallel connection switch RY1, the series connection switch RY2, the second parallel connection switch RY3, the voltage sensor 106, and the control unit 120 has been described, but is not limited to this. The switching unit 100 may also include DC relays DCR1 and DCR2 for connecting an external charger to the first battery unit 102 and the second battery unit 104. In this way, after confirming from the voltage measured by the voltage sensor 106 that the two storage batteries are connected in parallel or in series, the external charger can be connected to the first battery unit 102 and the second battery unit 104.

The switching unit 100 may also include a system main relay RY4 and a system main relay RY5 for connecting to the first battery unit 102, and a system main relay RY6 and a system main relay RY7 for connecting to the second battery unit 104. This improves the ease of installation of the switching unit in an EV.

The switching unit 100 may also include a circuit breaker Fu1 and a circuit breaker Fu2 connected in series with any of the system main relays RY4, ..., and the system main relay RY7. This can prevent excessive current from flowing, and protect the first battery unit 102 and the second battery unit 104.

The switching unit 100 may also include a voltage sensor 108 that detects the voltage of the first battery unit 102, and a voltage sensor 110 that detects the voltage of the second battery unit 104. This allows the difference in voltage between the first battery unit 102 and the second battery unit 104 to be determined as described above, and if the difference is large (e.g., a difference equal to or greater than a predetermined threshold), the first battery unit 102 and the second battery unit 104 can be balanced, such as by making the voltages of the first battery unit 102 and the second battery unit 104 equal.

The switching unit 100 may be disposed in a housing that houses the first battery unit 102 and the second battery unit 104. This allows the first battery unit 102 and the second battery unit 104 to be configured integrally with the switching unit 100, making it easier to handle and improving workability, for example, when mounting the switching unit on a vehicle.

Comparative Example
The effectiveness of the switching unit 100 shown in FIG. 1 will be shown below by showing the configuration of a power conversion system including a switching unit having a different configuration from that shown in FIG. 1. For example, referring to FIG. 5, the switching unit 150 includes a first parallel connection switch RY1, a series connection switch RY2, and a second parallel connection switch RY3. The switching unit 150 is integrally formed by accommodating the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 in a housing made of, for example, resin. The switching unit 150 constitutes a power conversion system together with the first battery unit 102, the second battery unit 104, the voltage sensor 106, the voltage sensor 108, the voltage sensor 110, the first inverter 130, the second inverter 132, and the inverter control unit 134. The power conversion system shown in FIG. 5 is the power conversion system shown in FIG. 1 except that the control unit 120, the circuit breaker Fu1, and the circuit breaker Fu2 are deleted, the voltage sensor 106 is disposed outside the switching unit 100, and the vehicle ECU 202 is replaced by the vehicle ECU 220. In Fig. 5, components having the same reference numerals as those in Fig. 1 are the same as those in Fig. 1 and have the same functions, so in the following, overlapping descriptions will not be repeated and differences will mainly be described.

In the power conversion system shown in FIG. 5, the vehicle ECU 220, like the vehicle ECU 202 shown in FIG. 1, performs on/off control of the system main relays RY4, ..., and RY7, as well as the DC relays DCR1 and DCR2. In addition, the vehicle ECU 220 also performs on/off control of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, which were handled by the control unit 120 in FIG. 1. The voltage measured by the voltage sensor 106 (i.e., a signal corresponding to the measured voltage) is input to the vehicle ECU 220. The vehicle ECU 220 performs on/off control of the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3 so that the first battery unit 102 and the second battery unit 104 are in a series connection state or a parallel connection state, and then performs a process of determining the voltage between both terminals based on the voltage input from the voltage sensor 106.

Therefore, when the power conversion system shown in FIG. 5 is installed in a vehicle (i.e., an EV), the control program of the vehicle ECU must be significantly modified from the conventional program. In contrast, in the power conversion system shown in FIG. 1, the switching unit 100 controls the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, and includes a control unit 120 that determines the voltage measured by the voltage sensor 106. Therefore, the control program of the vehicle ECU 202 can be realized with only slight modifications from the control program of the conventional vehicle ECU. Therefore, when the power conversion system shown in FIG. 1 is installed in a vehicle such as an EV, the impact on surrounding devices in the vehicle can be suppressed.

Furthermore, the vehicle ECU 220 needs to be connected to the switching unit 150 and the voltage sensor 106. That is, electrical wiring is required to control the first parallel connection switch RY1, the series connection switch RY2, and the second parallel connection switch RY3, and electrical wiring is required to transmit a signal from the voltage sensor 106. In contrast, in the configuration shown in FIG. 1, only two electrical wiring is required between the switching unit 100 and the vehicle ECU 202: an electrical wiring for transmitting a command from the vehicle ECU 202 to the switching unit 100, and an electrical wiring for transmitting a voltage confirmation from the switching unit 100 to the vehicle ECU 202. That is, the switching unit 100 can reduce the number of wirings, and the power conversion system shown in FIG. 1 can be easily installed in a vehicle such as an EV. In addition, the effect of noise on devices around the vehicle can be reduced.

In the above, the case where fuses are used as the circuit breakers Fu1 and Fu2 has been described, but the present invention is not limited to this. The circuit breakers Fu1 and Fu2 may be any element capable of interrupting a large current such as a short circuit current, and may be a circuit breaker or the like.

Although the above describes the case where the switching unit is mounted on an EV, this is not limiting. The switching unit of the present disclosure may be mounted on a device that includes a motor driven by a battery. The switching unit may be mounted on, for example, a hybrid electric vehicle (HEV) and a plug-in hybrid electric vehicle (PHEV), etc.

　In the above, the motor is described as having open-end windings, but this is not limited to this. Motors with windings other than open-end windings may also be used.

The present disclosure has been described above by explaining the embodiments, but the above-mentioned embodiments are merely examples, and the present disclosure is not limited to only the above-mentioned embodiments. The scope of the present disclosure is indicated by each claim in the scope of claims, taking into consideration the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wording described therein.

Reference Signs List

100, 150 Switching unit 102 First battery unit 104

Second battery unit

106, 108, 110 Voltage sensor 120 Control unit 130 First inverter 132 Second inverter 134 Inverter control unit 140 Motor 200

External charger

202, 220 Vehicle ECU
210 High voltage auxiliary machine 212 Terminal section DCR1, DCR2 DC relay Fu1, Fu2 Circuit breaker Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12 Switching element RY1 First parallel connection switch RY2 Series connection switch RY3 Second parallel connection switches RY4, RY5, RY6, RY7 System main relay

Claims

a parallel connection switch that connects the first storage battery and the second storage battery in parallel;
a series connection switch that connects the first storage battery and the second storage battery in series;
a first voltage sensor that measures a voltage between both terminals of the first storage battery and the second storage battery that are in the parallel connection state or the series connection state.
The switching unit according to claim 1, further comprising a control unit that controls the on/off of the parallel connection switch and the series connection switch.
The switching unit according to claim 1 or claim 2, further comprising a first connection switch for connecting a charger for charging the first storage battery and the second storage battery to both terminals of the first storage battery and the second storage battery in the parallel connection state or the series connection state.
When the first storage battery and the second storage battery are charged in the parallel connection state, the parallel connection switch is turned on and the series connection switch is turned off;
The switching unit according to claim 1 , wherein when the first storage battery and the second storage battery are charged in the series connection state, the series connection switch is turned on and the parallel connection switch is turned off.
The switching unit according to any one of claims 1 to 4, further comprising a plurality of second connection switches for connecting the switching unit to the first storage battery and the second storage battery.
The switching unit according to claim 5, further comprising a circuit breaker connected in series with one of the plurality of second connection switches.
The switching unit according to any one of claims 1 to 6, further comprising a second voltage sensor that detects the voltage between both terminals of the first storage battery and the second storage battery.
The switching unit according to any one of claims 1 to 7, wherein the switching unit is disposed in a housing that houses the first storage battery and the second storage battery.
The switching unit according to any one of claims 1 to 8, wherein when the first storage battery and the second storage battery are discharged, the parallel connection switch is turned on and the series connection switch is turned off.
The first storage battery supplies power to a first inverter for driving a motor;
the second storage battery supplies power to a second inverter for driving the motor;
The switching unit according to claim 1 , wherein the switching unit switches a connection state of the first storage battery and the second storage battery so that a current flows bypassing the first inverter and the second inverter.
The switching unit is mounted on a vehicle,
The switching unit according to any one of claims 1 to 10, wherein when power is supplied from the first storage battery and the second storage battery mounted on the vehicle to a storage battery mounted on another vehicle other than the vehicle, the parallel connection switch and the series connection switch switch a connection state of the first storage battery and the second storage battery to the series connection state or the parallel connection state depending on a voltage of the storage battery mounted on the other vehicle.
A first storage battery and a second storage battery;
a switching unit that switches a connection state of the first storage battery and the second storage battery,
The switching unit includes:
a parallel connection switch that connects the first storage battery and the second storage battery in parallel;
a series connection switch that connects the first storage battery and the second storage battery in series;
a voltage sensor that measures a voltage between both terminals of the first storage battery and the second storage battery that are in the parallel connection state or the series connection state.