Control system

Abstract

A control system (100) comprises: a first switch (SW1) of a first electrical path (21) that connects a first power storage unit (31) and an electrical load (10); a second switch (SW2) of a second electrical path (22) that connects a second power storage unit (32) and the electrical load; a third switch (SW3) of a third electrical path (23) that connects the second power storage unit and the electrical load; a fourth switch (SW4) of a fourth electrical path (24) that connects the first power storage unit and the second power storage unit; and a fifth switch (SW5) of a fifth electrical path (25) that connects the first power storage unit and the second electrical path. The fifth electrical path is connected to the second electrical path at one of the two ends of the second switch on the second power storage unit side. Precharge circuits (71, 72) are connected in parallel to the first switch and the third switch.

Description

Control System CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-112449, filed on July 12, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a control system that controls switching of a connection state of a power storage unit.

[0003] A power supply system has been known in the past in which the connection state of two cell units (power storage units) can be switched between series connection and parallel connection. Such technology is described, for example, in Patent Document 1.

[0004] JP 2022-166494 A

[0005] In the disclosure of Patent Document 1, when a voltage difference occurs between the terminal voltage of one cell unit and the terminal voltage of the other cell unit, an inrush current flows from one cell unit to the other cell unit when switching from a series state to a parallel state. Generally, since the cell units are connected by bus bars or the like with low electrical resistance, this inrush current becomes large and there is a risk of failure of switches on the path.

[0006] A primary object of the present disclosure is to provide a control system that can suppress the generation of large currents.

[0007] A first control system that solves the above problem is a control system for an electric circuit that can switch a connection state of a first power storage unit and a second power storage unit with respect to an electric load, and includes: a first switch that switches between energizing and cut-off a first electric path that connects a positive terminal of the first power storage unit and the electric load; a second switch that switches between energizing and cut-off a second electric path that connects a negative terminal of the second power storage unit and the electric load; a third switch that switches between energizing and cut-off a third electric path that connects the positive terminal of the second power storage unit and the electric load; a fourth switch that switches between energizing and cut-off a fourth electric path that connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; and a fifth switch that switches between energizing and cut-off a fifth electric path that connects the negative terminal of the first power storage unit and the second electric path. A first end of the third electrical path is connected in the fourth electrical path between the positive terminal of the second storage unit and the fourth switch; a first end of the fifth electrical path is connected in the fourth electrical path between the fourth switch and the negative terminal of the first storage unit, and a second end of the fifth electrical path is connected to the second electrical path on the side of the second switch to which the second storage unit is connected; and a precharge circuit is connected in parallel to any two of the first switch, the second switch, and the third switch.

[0008] According to the control system, the sneak current caused by the voltage difference between the first power storage unit and the second power storage unit can be appropriately suppressed by the precharge circuit.

[0009] A second control system that solves the above problem is a control system for an electric circuit that can switch a connection state of a first power storage unit and a second power storage unit with respect to an electric load, and includes: a first switch that switches between energizing and cut-off a first electric path that connects a positive terminal of the first power storage unit and the electric load; a second switch that switches between energizing and cut-off a second electric path that connects a negative terminal of the second power storage unit and the electric load; a third switch that switches between energizing and cut-off a third electric path that connects the negative terminal of the first power storage unit and the electric load; a fourth switch that switches between energizing and cut-off a fourth electric path that connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; and a fifth switch that switches between energizing and cut-off a fifth electric path that connects the positive terminal of the second power storage unit and the first electric path. A first end of the third electrical path is connected in the fourth electrical path between the negative terminal of the first storage unit and the fourth switch; a first end of the fifth electrical path is connected in the fourth electrical path between the fourth switch and the positive terminal of the second storage unit, and a second end of the fifth electrical path is connected to the first electrical path on the side of the first switch to which the first storage unit is connected; and a precharge circuit is connected in parallel to any two of the first switch, the second switch, and the third switch.

[0010] According to the control system, the sneak current caused by the voltage difference between the first power storage unit and the second power storage unit can be appropriately suppressed by the precharge circuit.

[0011] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagram showing an electric circuit of this embodiment, Fig. 2 is a diagram showing an electric circuit of a comparative example, Fig. 3 is a diagram showing an electric circuit before transition to a parallel connection state, Fig. 4 is a diagram showing an electric circuit before transition to a series connection state, Fig. 5 is a diagram showing an electric circuit of a comparative example, Fig. 6 is a diagram showing an electric circuit of a second embodiment, Fig. 7 is a diagram showing an electric circuit of a third embodiment, Fig. 8 is a diagram showing an electric circuit before transition to a parallel connection state, Fig. 9 is a diagram showing an electric circuit before transition to a parallel connection state, Fig. 10 is a diagram showing an electric circuit before transition to a series connection state, Fig. 11 is a diagram showing an electric circuit of a fourth embodiment, Fig. 12 is a diagram showing an electric circuit of a fifth embodiment, and Fig. 13 is a diagram showing an electric circuit of a sixth embodiment.

[0012] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0013] A first embodiment of a control system according to the present disclosure will now be described with reference to the drawings. A control system 100 according to the present embodiment is installed in an electric vehicle such as an electric car or a hybrid car, an electric aircraft, an electric ship, or the like, and constitutes an electric vehicle system.

[0014] As shown in the electrical circuit of FIG. 1 , the control system 100 is connected to an electrical load 10. In this embodiment, the electrical load 10 is assumed to be a motor 11 and its inverter 12. The motor 11 is a three-phase synchronous machine, and includes star-connected U-, V-, and W-phase armature windings and a rotor. The motor 11 is, for example, a permanent magnet synchronous machine. The rotor is capable of transmitting power to the drive wheels of the vehicle. Therefore, the motor 11 serves as a source of torque for propelling the vehicle.

[0015] The inverter 12 includes three phases of series-connected upper-arm switches SWH and lower-arm switches SWL. An upper-arm diode DH, which is a freewheeling diode, is connected in antiparallel to the upper-arm switch SWH, and a lower-arm diode DL, which is also a freewheeling diode, is connected in antiparallel to the lower-arm switch SWL. In this embodiment, each of the switches SWH and SWL is an IGBT.

[0016] The inverter 12 includes a smoothing capacitor 13. A high-potential terminal of the smoothing capacitor 13 is connected to a first electrical path 21, which is a positive bus. A low-potential terminal of the smoothing capacitor 13 is connected to a second electrical path 22, which is a negative bus. The smoothing capacitor 13 may be provided outside the inverter 12.

[0017] In each phase, a first end of the armature winding of the motor 11 is connected to a connection point between the emitter, which is the low potential terminal of the upper arm switch SWH, and the collector, which is the high potential terminal of the lower arm switch SWL. The second ends of the armature windings of each phase are star-connected and connected to each other at the neutral point.

[0018] The collectors of the upper arm switches SWH of each phase are connected to a first electrical path 21. The emitters of the lower arm switches SWL of each phase are connected to a second electrical path 22. The control system 100 is connected to the inverter 12 via the first electrical path 21 and the second electrical path 22.

[0019] In this embodiment, the motor 11 and the inverter 12 are the electric load 10, but an electric load other than these may be connected to the first electric path 21 and the second electric path 22. Furthermore, the electric load 10 may be changed to an electric load other than the motor 11 and the inverter 12.

[0020] A first storage battery 31 (corresponding to the "first power storage unit") and a second storage battery 32 (corresponding to the "second power storage unit") are connected to the control system 100. Each of the storage batteries 31, 32 serves as a power supply source for driving the rotor of the motor 11 to rotate. Each of the storage batteries 31, 32 is an assembled battery configured as a series connection of battery cells, which are single cells. The positive terminal of the first storage battery 31 is connected to the first electrical path 21, and the negative terminal of the second storage battery 32 is connected to the second electrical path 22. The terminal voltages (e.g., rated voltages) of the battery cells constituting the assembled battery are set to be the same, for example. The battery cells are, for example, secondary batteries such as lithium-ion batteries.

[0021] Each of the storage batteries 31, 32 can be charged by an external charger 40 (described later) that is provided outside the vehicle. The external charger 40 is, for example, a stationary charger. The power supply path of the external charger 40 is configured to be connectable to the first electrical path 21 and the second electrical path 22, respectively, via a connector of the external charger 40, a charging port of the vehicle, a relay switch, and the like. In this embodiment, a high-voltage charger and a low-voltage charger are assumed as the external charger 40. The charging voltage of the high-voltage charger is approximately the same as the inter-terminal voltage (specifically, the rated voltage) of the series connection of the first storage battery 31 and the second storage battery 32, for example, 800 V. On the other hand, the charging voltage of the low-voltage charger is approximately the same as the inter-terminal voltage of the first storage battery 31 or the second storage battery 32, for example, 400 V.

[0022] The control system 100 includes a first switch SW1 serving as a positive-side main switch that switches between energization and de-energization of a first electrical path 21 that connects the first storage battery 31 and the inverter 12. The first switch SW1 is provided on the first electrical path 21. The control system 100 also includes a second switch SW2 serving as a negative-side main switch that switches between energization and de-energization of a second electrical path 22 that connects the second storage battery 32 and the inverter 12. The second switch SW2 is provided on the second electrical path 22.

[0023] The control system 100 includes a third switch SW3, a fourth switch SW4, and a fifth switch SW5 as switches for switching the connection state of the first storage battery 31 and the second storage battery 32 to either a series connection state or a parallel connection state.

[0024] The third switch SW3 is provided on a third electrical path 23 that connects the positive terminal of the second storage battery 32 and the electrical load 10. When the third switch SW3 is turned on, the positive terminal of the second storage battery 32 and the electrical load 10 are electrically connected. When the third switch SW3 is turned off, the positive terminal of the second storage battery 32 and the electrical load 10 are electrically disconnected.

[0025] The fourth switch SW4 is provided on a fourth electrical path 24 that connects the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32. When the fourth switch SW4 is turned on, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically connected. On the other hand, when the fourth switch SW4 is turned off, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically disconnected.

[0026] The fifth switch SW5 is provided on a fifth electrical path 25 that connects the negative terminal of the first storage battery 31 and the second electrical path 22. When the fifth switch SW5 is turned on, the negative terminal of the first storage battery 31 and the second electrical path 22 are electrically connected. When the fifth switch SW5 is turned off, the negative terminal of the first storage battery 31 and the second electrical path 22 are electrically disconnected.

[0027] In this embodiment, the switches SW1, SW2, SW3, SW4, and SW5 (hereinafter referred to as switches SW1 to SW5) are mechanical relays. When turned off, each of the switches SW1 to SW5 blocks bidirectional current flow, and when turned on, allows bidirectional current flow. Note that the switches SW1 to SW5 are not limited to mechanical relays and may be, for example, semiconductor switching elements.

[0028] In this embodiment, the first storage battery 31, the second storage battery 32, the fourth switch SW4, the fifth switch SW5, and the wiring connecting them are configured as a single battery unit 61. As shown in Fig. 1 , the wiring in the battery unit 61 configures a portion of the first electrical path 21, a portion of the second electrical path 22, a portion of the third electrical path 23, and a fourth electrical path 24. The battery unit 61 is housed inside a battery pack or the like in a vehicle, for example.

[0029] In this embodiment, the first switch SW1, the second switch SW2, the third switch SW3, and the wiring connecting them are configured as a single connection unit 62. As shown in Fig. 1 , the wiring in the connection unit 62 configures a portion of the first electrical path 21, a portion of the second electrical path 22, and a portion of the third electrical path 23. The connection unit 62 is housed, for example, inside a junction box or the like in a vehicle. Note that the connection unit 62 may also be housed inside the above-mentioned battery pack while being housed inside the junction box.

[0030] A control device 51 (corresponding to a "switch control unit") is connected to the control system 100. The control device 51 is primarily configured with a microcomputer, which includes a CPU. The functions provided by the microcomputer can be provided by software stored in a physical memory device and a computer that executes the software, software alone, hardware alone, or a combination thereof. For example, when the microcomputer is provided by a hardware electronic circuit, the functions can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer executes a program stored in a non-transitory tangible storage medium that serves as its own storage unit. The program includes, for example, a program for processing the on / off control of each switch SW1 to SW5. Execution of the program results in the execution of a method corresponding to the program. The storage unit is, for example, a non-volatile memory. The programs stored in the storage unit can be updated via a communication network such as the Internet, for example, via OTA (Over the Air).

[0031] The control device 51 performs switching control of the switches SWH and SWL constituting the inverter 12 to feedback control the control variable of the motor 11 to a command value based on detection values ​​from various sensors (not shown, such as a voltage sensor, a current sensor, and a rotation angle sensor). The control variable is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. This feedback control transmits the rotational power of the rotor to the drive wheels, causing the vehicle to run.

[0032] Furthermore, the control device 51 controls the on / off of each of the switches SW1 to SW5 to switch the connection state of the first storage battery 31 and the second storage battery 32 in accordance with the required voltage of the electric load 10 connected to the control system 100 or the charging voltage of the external charger 40. Specifically, the control device 51 controls the on / off of each of the switches SW1 to SW5 to switch to a series connection state when the required voltage or charging voltage is high, and to switch to a parallel connection state when the required voltage or charging voltage is low.

[0033] For example, when the required voltage is high, the control device 51 controls the on / off of each of the switches SW1 to SW5 to connect the first storage battery 31 and the second storage battery 32 in series to supply high-voltage power to the electrical load 10. Furthermore, when a high-voltage charger is connected as the external charger 40 (when the charging voltage is high), the control device 51 controls the on / off of each of the switches SW1 to SW5 to connect the first storage battery 31 and the second storage battery 32 in series to charge each of the storage batteries 31, 32.

[0034] On the other hand, when the required voltage is low (when a low-voltage load is connected as the electrical load), the control device 51 controls the on / off of each of the switches SW1 to SW5 to connect the first storage battery 31 and the second storage battery 32 in parallel to the electrical load 10, thereby supplying power to the electrical load 10. For example, when the electrical load 10 is an electrical load other than the motor 11 that requires a low voltage and is connected to the control system 100, the parallel connection state is selected.

[0035] In addition, when a low-voltage charger is connected as the external charger 40 (when the charging voltage is low), the control device 51 controls the on / off of each switch SW1 to SW5 to connect the first storage battery 31 and the second storage battery 32 in parallel and charge each storage battery 31, 32.

[0036] However, if a voltage difference occurs between the terminal voltage of the first storage battery 31 and the terminal voltage of the second storage battery 32, if the circuit configuration of the comparative example shown in Figure 2 is adopted, when switching to a parallel connection state, there is a possibility that an inrush current (hereinafter referred to as a sneak current) will occur from one storage battery 31, 32 to the other storage battery 31, 32.

[0037] The sneak current will be described in detail with reference to FIG. 2 . Components identical to those in FIG. 1 (the present embodiment) are denoted by the same reference numerals and will not be described again. The comparative example in FIG. 2 illustrates a circuit configuration in which one end of the third electrical path 1023 is connected to the first storage battery 31 side of the first switch SW1 in the first electrical path 21. In this comparative example in FIG. 2 , a precharge circuit 172 is connected in parallel to the second switch SW2. The precharge circuit 172 is composed of a series connection of a resistor 172a and a switch 172b, and the switch 172b is turned on before the second switch SW2 is turned on.

[0038] In the circuit configuration shown in Fig. 2, when the batteries are connected in parallel, a closed circuit is formed as shown by the solid arrow in Fig. 2. At this time, if a voltage difference occurs between the first storage battery 31 and the second storage battery 32, a current will flow through the closed circuit shown by the solid arrow. This closed circuit does not include an element that acts as a resistor during switching, such as the precharge circuit 172, so a large inrush current may flow. In this case, a large current may flow through the third switch SW3 or the fifth switch SW5, causing them to fuse and fail.

[0039] When the series connection state is established, the switch 172b of the precharge circuit 172 is turned on before the second switch SW2, thereby preventing a large inrush current from flowing to the first switch SW1, the smoothing capacitor 13, etc.

[0040] Therefore, in this embodiment, the third electrical path 23 is configured as shown in Fig. 1. That is, as shown in Fig. 1, a first end of the third electrical path 23 is connected to a connection point P31 in the fourth electrical path 24 between the positive terminal of the second storage battery 32 and the fourth switch SW4. Meanwhile, a second end of the third electrical path 23 is connected to the first electrical path 21 at a connection point P32 between the electrical load 10 and the first switch SW1 inside the connection unit 62. That is, the third electrical path 23 merges with the first electrical path 21 at the connection point P32 inside the connection unit 62.

[0041] A first end of the fifth electrical path 25 is connected to a connection point P51 on the fourth electrical path 24 between the fourth switch SW4 and the negative terminal of the first storage battery 31. A second end of the fifth electrical path 25 is connected to the second electrical path 22 at a connection point P52 on the side of the second switch SW2 to which the second storage battery 32 is connected. This connection point P52 is located inside the battery unit 61. Therefore, the fifth electrical path 25 merges with the second electrical path 22 at the connection point P52 inside the battery unit 61.

[0042] 1, a first precharge circuit 71 is connected in parallel to the first switch SW1. The first precharge circuit 71 is composed of a series connection of a resistor 71a and a switch 71b, and the switch 71b is turned on before the first switch SW1 is turned on.

[0043] A second precharge circuit 72 is connected in parallel to the second switch SW2. The second precharge circuit 72 is composed of a series connection of a resistor 72a and a switch 72b, and the switch 72b is turned on before the second switch SW2 is turned on.

[0044] The specifications such as the resistance value and withstand voltage of the resistor 71a of the first precharge circuit 71 are the same as those of the second precharge circuit 72. Specifically, the resistance value of the resistors 71a and 72a is 5 Ω, and the withstand voltage of the precharge circuits 71 and 72 is the voltage when the voltage between the terminals of the series-connected body of the storage batteries 31 and 32 is applied, that is, 800 V.

[0045] The operation and effects of the control system 100 in this embodiment will be described.

[0046] Before the parallel connection state is established as shown in Fig. 3, the control device 51 turns on the switch 71b of the first pre-charge circuit 71, the switch 72b of the second pre-charge circuit 72, the third switch SW3, and the fifth switch SW5, and turns off the other switches SW1, SW2, and SW4. As a result, current flows from the first storage battery 31 as shown by the dashed arrow in Fig. 3, and current flows from the second storage battery 32 as shown by the dashed arrow in Fig. 3, and power is supplied to the smoothing capacitor 13, which is pre-charged (charged). Note that for convenience of illustration, the smoothing capacitor 13 is shown outside the inverter 12 in Figs. 3 and 4.

[0047] In this case, a closed circuit not including the smoothing capacitor 13 is also formed, as shown by the solid arrow in Fig. 3. However, even if there is a voltage difference between the first storage battery 31 and the second storage battery 32, the resistor 71a of the first precharge circuit 71 is present in the closed circuit shown by the solid arrow in Fig. 3. Therefore, the maximum current flowing in this closed circuit is approximately 80 A, and it is possible to prevent a large current from flowing in the closed circuit shown by the dashed line in Fig. 3. This makes it possible to prevent the first switch SW1 and the fifth switch SW5 from breaking down.

[0048] Furthermore, before the parallel connection state is established, the voltage applied to each closed circuit is a maximum of 400 V, which is lower than the withstand voltage of the precharge circuits 71 and 72, and therefore the precharge circuits 71 and 72 will not break down.

[0049] 4, before the series connection state is established, the control device 51 turns on the switch 71b of the first precharge circuit 71, the switch 72b of the second precharge circuit 72, and the switch SW4, and turns off the other switches SW1, SW2, SW3, and SW5. As a result, current flows from the first storage battery 31 and the second storage battery 32, as indicated by the dashed arrows in FIG. 4, and power is supplied to the smoothing capacitor 13, which is precharged.

[0050] In this case, the resistor 71a of the first precharge circuit 71 and the resistor 72a of the second precharge circuit 72 are interposed in the closed circuit shown by the dashed line in FIG. 4 . Their resistance values ​​are 5 Ω, resulting in a total of 10 Ω resistors 71a and 72a. Therefore, the maximum current flowing through this closed circuit is approximately 80 A, preventing large currents from flowing through the closed circuit. This prevents breakdown of the switches SW1, SW2, and SW4. Furthermore, in the series-connected state, the maximum voltage applied to this closed circuit is 800 V, which is below the withstand voltage of the precharge circuits 71 and 72, preventing breakdown of the precharge circuits 71 and 72.

[0051] Furthermore, a second end of the third electrical path 23 is connected to the first electrical path 21 at a connection point P32 between the electrical load 10 and the first switch SW1 within the connection unit 62. That is, the third electrical path 23 merges with the first electrical path 21 at the connection point P32 and thereafter and is connected to the electrical load 10 via the first electrical path 21. With this configuration, the connection to the electrical load 10 is made via the first electrical path 21 and the second electrical path 22, and therefore it is possible to connect the connection unit 62 and the electrical load 10 with two wires (bus bars). That is, as shown in FIG. 5 , if the connection point P32 is set outside the connection unit 62 and the first electrical path 21 and the second electrical path 22 are merged outside the connection unit 62, the number of wires would be increased to three in part, but with the configuration of this embodiment, it is possible to reduce the number of wires to two.

[0052] One end of the fifth electrical path 25 is connected to the second electrical path 22 at a connection point P52 in the battery unit 61. This allows the battery unit 61 and the connection unit 62 to be connected by the first electrical path 21, the second electrical path 22, and the third electrical path 23. In other words, the connection unit 62 and the battery unit 61 can be connected by three wires (such as bus bars).

[0053] In other words, as shown in Figure 5, if the second electrical path 22 and the fifth electrical path 25 were to merge at a connection point P52 outside the battery unit 61, such as inside the connection unit 62, the number of wires between the battery unit 61 and the connection unit 62 would increase to four, but by configuring as in this embodiment, it is possible to reduce the number of wires between the battery unit 61 and the connection unit 62 to three.

[0054] Second Embodiment A second embodiment will be described, in which a portion of the control system 100 of the first embodiment is modified. FIG. 6 illustrates the control system 100 of the second embodiment. As shown in FIG. 6, the control system 100 of the second embodiment is connected to an electric load 110a and an electric load 110b. As in the first embodiment, the electric load 110a is configured with a motor 111a and its inverter 112a, and the electric load 110b is configured with a motor 111b and its inverter 112b. In the second embodiment, the types and numbers of the electric loads 110a and 110b are not limited to the motors 111a and 111b, and can be changed as desired. In this embodiment, the electric load 110a corresponds to a first group of electric loads, and the electric load 110b corresponds to a second group of electric loads.

[0055] The first electrical path 21 is connected to the positive electrode side of the electrical load 110a, the third electrical path 23 is connected to the positive electrode side of the electrical load 110b, and the second electrical path 22 is connected to the negative electrode sides of the electrical load 110a and the electrical load 110b.

[0056] As a result, in the parallel connection state, power can be supplied from the first storage battery 31 to the electrical load 110a, and power can be supplied from the second storage battery 32 to the electrical load 110b.

[0057] The effects of the second embodiment will be described.

[0058] In the circuit configuration shown in the control system 100 of the second embodiment, before establishing a parallel connection state, the control device 51 turns on the switch 71b of the first precharge circuit 71, the switch 72b of the second precharge circuit 72, the third switch SW3, and the fifth switch SW5, and turns off the other switches SW1, SW2, and SW4. This allows the capacitor 113a of the electrical load 110a and the capacitor 113b of the electrical load 110b to be precharged simultaneously. Therefore, the time required for precharging can be shortened compared to a control system having a circuit configuration in which the electrical loads 110a and 110b are individually connected to the storage batteries 31 and 32 at different times and precharged.

[0059] Third Embodiment A third embodiment will be described, in which a portion of the control system 100 of the first embodiment is modified. FIG. 7 illustrates the control system 100 of the third embodiment. As shown in FIG. 7, in the control system 100 of the third embodiment, a third precharge circuit 73 is connected in parallel to the third switch SW3. The third precharge circuit 73 is composed of a series connection of a resistor 73a and a switch 73b, and the switch 73b is turned on before the third switch SW3 is turned on. However, unlike the first embodiment, the third embodiment does not include the first precharge circuit 71.

[0060] In the third embodiment, the resistance value of the resistor 72a of the second pre-charge circuit 72 is set to 10 Ω. The withstand voltage of the second pre-charge circuit 72 is set to the maximum voltage when the voltage across the terminals of the series-connected battery 31, 32 is applied, that is, 800 V. The resistance value of the third pre-charge circuit 73 is set to 1 Ω. The withstand voltage of the third pre-charge circuit 73 is set to 400 V.

[0061] The operation and effects of the third embodiment will be described.

[0062] Before the parallel connection state is established as shown in Fig. 8 , the control device 51 turns on the first switch SW1, the switch 72b of the second pre-charge circuit 72, the switch 73b of the third pre-charge circuit 73, and the fifth switch SW5, and turns off the other switches SW2, SW3, and SW4. As a result, current flows from the first storage battery 31 as indicated by the dashed-dotted arrow in Fig. 8 , and current flows from the second storage battery 32 as indicated by the dashed-two-dotted arrow, supplying power to the smoothing capacitor 13 and pre-charging (charging) it. At this time, both pre-charge currents pass through the second pre-charge circuit 72, preventing a large current from flowing through the closed circuits indicated by the dashed-dotted and dashed-two-dotted lines.

[0063] In this closed circuit, the resistor 72a of the second pre-charge circuit 72 is the main resistor. Therefore, the resistance value of the resistor 72a of the second pre-charge circuit 72 is set to twice that of the first embodiment, specifically, 10 Ω. Therefore, the current value flowing through this closed circuit is expected to be approximately 40 A at most. Also, in FIGS. 8 to 10, for convenience of the drawings, the motor 11 and inverter 12 are simplified and illustrated as an electrical load 10. Also, in FIGS. 8 to 10, for convenience of the drawings, a smoothing capacitor 13 is illustrated external to the electrical load 10.

[0064] Furthermore, before the parallel connection state is established, a closed circuit is also formed without the smoothing capacitor 13, as shown by the dashed-dotted arrow in Figure 9. However, even if there is a voltage difference between the first storage battery 31 and the second storage battery 32, the resistor 73a of the third precharge circuit 73 is present in the closed circuit shown by the dashed-dotted arrow in Figure 9. This makes it possible to prevent a large current from flowing in the closed circuit shown by the dashed-dotted arrow in Figure 9. This makes it possible to prevent the first switch SW1 and the fifth switch SW5 from breaking down.

[0065] In the closed circuit indicated by the dashed-dotted arrow in Figure 9, the voltage applied to the third pre-charge circuit 73 corresponds to the voltage difference between the first storage battery 31 and the second storage battery 32. Generally, the SOC of the first storage battery 31 and the SOC of the second storage battery 32 are approximately the same value due to equalization processing, so the voltage difference is not very large, and in this embodiment, it is assumed to be at most about 30 V. Accordingly, the resistance value and withstand voltage of the resistor 73a of the third pre-charge circuit 73 can be reduced, enabling miniaturization.

[0066] That is, the resistance value of the resistor 73a of the third pre-charge circuit 73 is set to 1 Ω, taking into consideration that only sneak current based on the voltage difference flows through the third pre-charge circuit 73. Note that with a 1 Ω resistor 73a, sneak current can be appropriately suppressed even if the voltage difference is 120 V. Furthermore, the withstand voltage of the third pre-charge circuit 73 is set to 400 V, taking into consideration that only the voltage difference between the first storage battery 31 and the second storage battery 32 is applied to the third pre-charge circuit 73.

[0067] 10, before the series connection state is established, the control device 51 turns on the first switch SW1, the switch 72b of the second precharge circuit 72, and the fourth switch SW4, and turns off the other switches SW2, SW3, SW5, and 73b. As a result, current flows from the first storage battery 31 and the second storage battery 32, as indicated by the dashed-dotted arrows in FIG. 10, and power is supplied to the smoothing capacitor 13, which is precharged.

[0068] At this time, the resistor 72a of the second precharge circuit 72 is interposed in the closed circuit indicated by the dashed line in FIG. 10 . Unlike the first embodiment, the third embodiment has only one resistor 72a, which has twice the resistance value of the first embodiment. As a result, the maximum current flowing through this closed circuit is approximately 80 A, the same as in the first embodiment, and large currents can be prevented from flowing through the closed circuit. This prevents failure of the switches SW1, SW4, and 72b. Furthermore, in the series connection state, the voltage applied to this closed circuit is a maximum of 800 V, which is below the withstand voltage of the second precharge circuit 72, and therefore the second precharge circuit 72 will not fail.

[0069] (Fourth Embodiment) A control system 100 according to a fourth embodiment, which is a partial modification of the control system 100 according to the first embodiment, will be described. The control system 100 according to the fourth embodiment is shown in FIG. 11 . Note that the same components as those in the first embodiment are denoted by the same reference numerals and will not be described again. For convenience of illustration, the motor 11 and inverter 12 are simplified and shown as an electrical load 10 in FIG. 11 . For convenience of illustration, a smoothing capacitor 13 is shown outside the electrical load 10 in FIG.

[0070] 11 , in the control system 100 of the fourth embodiment, a first end of the third electrical path 123 is connected to a connection point P131 between the negative terminal of the first storage battery 31 and the fourth switch SW4 in the fourth electrical path 24. Furthermore, a second end of the third electrical path 123 is connected to a connection point P132, which is one of the ends of the second switch SW2 on the side of the electrical load 10, in the second electrical path 22. The connection point P132 is set inside the connection unit 62. That is, the third electrical path 123 merges with the second electrical path 22 at the connection point P132 inside the connection unit 62.

[0071] Furthermore, a first end of the fifth electrical path 125 of the fourth embodiment is connected to a connection point P151 on the fourth electrical path 24 between the fourth switch SW4 and the positive terminal of the second storage battery 32. A second end of the fifth electrical path 125 is connected to the first electrical path 21 at a connection point P152 on the side of the first switch SW1 to which the first storage battery 31 is connected. This connection point P152 is located inside the battery unit 61. Therefore, the fifth electrical path 125 of the fourth embodiment merges with the first electrical path 21 at the connection point P152 inside the battery unit 61. The control system 100 of the fourth embodiment has substantially the same functions and effects as those of the first embodiment.

[0072] Fifth Embodiment A control system 100 according to a fifth embodiment, which is a partial modification of the control system 100 according to the fourth embodiment, will be described. The control system 100 according to the fifth embodiment is illustrated in Fig. 12. The same components as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0073] 12 , the control system 100 of the fifth embodiment has an electric load 110a and an electric load 110b connected thereto, similar to the second embodiment. Specifically, the first electric path 21 branches and is connected to the positive terminals of the electric loads 110a and 110b, and the third electric path 123 is connected to the negative terminal of the electric load 110b. The second electric path 22 is connected to the negative terminal of the electric load 110a. The control system 100 of the fifth embodiment has substantially the same effects as the second embodiment.

[0074] Sixth Embodiment A control system 100 according to a sixth embodiment, which is a partial modification of the control system 100 according to the fourth embodiment, will be described. The control system 100 according to the sixth embodiment is shown in FIG. 13. Note that the same components as those in the fourth embodiment are denoted by the same reference numerals and will not be described again. For convenience of illustration, the motor 11 and inverter 12 are simplified and shown as an electrical load 10 in FIG. 13. For convenience of illustration, a smoothing capacitor 13 is shown outside the electrical load 10 in FIG.

[0075] 13, in the control system 100 of the sixth embodiment, a third precharge circuit 73 is connected in parallel to the third switch SW3. The third precharge circuit 73 is composed of a series connection of a resistor 73a and a switch 73b, and the switch 73b is turned on before the third switch SW3 is turned on. Meanwhile, unlike the fourth embodiment, the sixth embodiment does not include the first precharge circuit 71.

[0076] In the sixth embodiment, the resistance value of the resistor 72a of the second pre-charge circuit 72 is set to 10 Ω. The withstand voltage of the second pre-charge circuit 72 is set to the maximum voltage when the voltage between the terminals of the series-connected battery 31, 32 is applied, that is, 800 V. The resistance value of the third pre-charge circuit 73 is set to 1 Ω. The withstand voltage of the third pre-charge circuit 73 is set to 400 V. The control system 100 of the sixth embodiment has the same effects as the control system 100 of the third embodiment.

[0077] (Modification) A modification in which part of the configuration of the control system 100 of each of the above embodiments is changed will be described.

[0078] In the above embodiment, the precharge circuits 71, 72, and 73 may be provided in parallel with any two of the first switch SW1, the second switch SW2, and the third switch SW3. Alternatively, the precharge circuits 71, 72, and 73 may be provided in parallel with all of the first switch SW1, the second switch SW2, and the third switch SW3, respectively.

[0079] In the above embodiment, the connection points P32 and P132 to which the second ends of the third electrical paths 23 and 123 are connected may be located outside the connection unit 62.

[0080] In the above embodiment, the connection points P52, P152 to which the second ends of the fifth electrical paths 25, 125 are connected may be located outside the battery unit 61. For example, the connection points P52, P152 may be located inside the connection unit 62.

[0081] In the above embodiment, the type and number of the electric loads 10 may be changed arbitrarily.

[0082] The technical ideas that can be derived from the above-described embodiments and modifications will be described below.

[0083] [Configuration 1] An electric circuit control system (100) capable of switching a connection state between a first power storage unit (31) and a second power storage unit (32) with respect to an electric load (10, 110a, 110b), comprising: a first switch (SW1) that switches between energizing and interrupting a first electric path (21) that connects a positive electrode terminal of the first power storage unit and the electric load; a second switch (SW2) that switches between energizing and interrupting a second electric path (22) that connects a negative electrode terminal of the second power storage unit and the electric load; a third switch (SW3) that switches between energizing and interrupting a third electric path (23) that connects a positive electrode terminal of the second power storage unit and the electric load; and a fourth switch (SW4) that switches between energizing and interrupting a fourth electric path (24) that connects a negative electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit. a fifth switch (SW5) that switches between energization and de-energization of a fifth electric path (25) that connects a negative terminal of the first power storage unit and the second electric path, wherein a first end of the third electric path is connected in the fourth electric path between a positive terminal of the second power storage unit and the fourth switch, a first end of the fifth electric path is connected in the fourth electric path between the fourth switch and the negative terminal of the first power storage unit, and a second end of the fifth electric path is connected to the second electric path at a side of both ends of the second switch to which the second power storage unit is connected, and a pre-charge circuit (71, 72, 73) is connected in parallel to any two of the first switch, the second switch, and the third switch.

[0084] [Configuration 2] The first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), a second end of the third electrical path is connected to the first electrical path between the electrical load and the first switch within the connection unit, and the third electrical path is connected to the electrical load via the first electrical path from the second end onwards, and the connection unit is connected to the positive side of the electrical load by the first electrical path and to the negative side of the electrical load by the second electrical path. This is the control system described in Configuration 1.

[0085] [Configuration 3] The control system according to Configuration 1, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), there are a plurality of the electric loads, and the plurality of the electric loads are divided into a first group of electric loads (110a) and a second group of electric loads (110b), and the connection unit is connected to the positive sides of the first group of electric loads by the first electric path, connected to the positive sides of the second group of electric loads by the third electric path, and connected to the negative sides of the first group of electric loads and the second group of electric loads by the second electric path.

[0086] [Configuration 4] An electric circuit control system capable of switching a connection state of a first power storage unit (31) and a second power storage unit (32) to an electric load (10, 110a, 100b), comprising: a first switch (SW1) that switches between energizing and interrupting a first electric path (21) that connects a positive electrode terminal of the first power storage unit and the electric load; a second switch (SW2) that switches between energizing and interrupting a second electric path (22) that connects a negative electrode terminal of the second power storage unit and the electric load; a third switch (SW3) that switches between energizing and interrupting a third electric path (123) that connects the negative electrode terminal of the first power storage unit and the electric load; and a fourth switch (SW4) that switches between energizing and interrupting a fourth electric path (24) that connects the negative electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit. a fifth switch (SW5) that switches between energization and de-energization of a fifth electric path (125) that connects the positive terminal of the second power storage unit and the first electric path, wherein a first end of the third electric path is connected in the fourth electric path between the negative terminal of the first power storage unit and the fourth switch, a first end of the fifth electric path is connected in the fourth electric path between the fourth switch and the positive terminal of the second power storage unit, and a second end of the fifth electric path is connected to the first electric path at a side of the first switch to which the first power storage unit is connected, and a pre-charge circuit (71, 72, 73) is connected in parallel to any two of the first switch, the second switch, and the third switch.

[0087] [Configuration 5] The first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), a second end of the third electrical path is connected to the second electrical path between the electrical load and the second switch within the connection unit, and the third electrical path is connected to the electrical load via the second electrical path from the second end onwards, and the connection unit is connected to the positive side of the electrical load by the first electrical path and to the negative side of the electrical load by the second electrical path. This is the control system described in Configuration 4.

[0088] [Configuration 6] The control system according to Configuration 4, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), there are a plurality of the electric loads, and the plurality of the electric loads are divided into a first group of electric loads (110a) and a second group of electric loads (110b), and the connection unit is connected to the positive sides of the first group of electric loads and the second group of electric loads by the first electric path, connected to the negative side of the first group of electric loads by the second electric path, and connected to the negative side of the second group of electric loads by the third electric path.

[0089] [Configuration 7] The control system according to any one of configurations 1 to 6, wherein the first storage unit, the second storage unit, the fourth switch, and the fifth switch are configured as one battery unit (61), the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), and a second end of the fifth electrical path is connected to the first electrical path or the second electrical path within the battery unit, thereby connecting the battery unit and the connection unit via the first electrical path, the second electrical path, and the third electrical path.

[0090] [Configuration 8] The control system according to any one of configurations 1 to 7, wherein the precharge circuit is connected in parallel to the first switch and the second switch, respectively.

[0091] [Configuration 9] The control system according to any one of configurations 1 to 7, wherein the precharge circuit is connected in parallel to the second switch and the third switch, respectively.

[0092] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. An electric circuit control system (100) capable of switching a connection state between a first power storage unit (31) and a second power storage unit (32) with respect to an electric load (10, 110a, 110b), comprising: a first switch (SW1) that switches between energizing and cutting off a first electric path (21) that connects a positive terminal of the first power storage unit and the electric load; a second switch (SW2) that switches between energizing and cutting off a second electric path (22) that connects a negative terminal of the second power storage unit and the electric load; a third switch (SW3) that switches between energizing and cutting off a third electric path (23) that connects a positive terminal of the second power storage unit and the electric load; and a fourth switch (SW4) that switches between energizing and cutting off a fourth electric path (24) that connects a negative terminal of the first power storage unit and a positive terminal of the second power storage unit. a fifth switch (SW5) that switches between energization and de-energization of a fifth electric path (25) that connects a negative terminal of the first power storage unit and the second electric path, wherein a first end of the third electric path is connected in the fourth electric path between a positive terminal of the second power storage unit and the fourth switch, a first end of the fifth electric path is connected in the fourth electric path between the fourth switch and the negative terminal of the first power storage unit, and a second end of the fifth electric path is connected to the second electric path at a side of both ends of the second switch to which the second power storage unit is connected, and a pre-charge circuit (71, 72, 73) is connected in parallel to any two of the first switch, the second switch, and the third switch.

2. The control system of claim 1, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), the second end of the third electrical path is connected to the first electrical path between the electrical load and the first switch within the connection unit, and the third electrical path is connected to the electrical load via the first electrical path from the second end onwards, and the connection unit is connected to the positive side of the electrical load by the first electrical path and to the negative side of the electrical load by the second electrical path.

3. The control system of claim 1, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62); there are a plurality of electrical loads, and the plurality of electrical loads are divided into a first group of electrical loads (110a) and a second group of electrical loads (110b); and the connection unit is connected to the positive sides of the first group of electrical loads by the first electrical path, connected to the positive sides of the second group of electrical loads by the third electrical path, and connected to the negative sides of the first group of electrical loads and the second group of electrical loads by the second electrical path.

4. A control system for an electric circuit capable of switching a connection state between a first power storage unit (31) and a second power storage unit (32) with respect to an electric load (10, 110a, 100b), comprising: a first switch (SW1) that switches between energizing and cutting off a first electric path (21) that connects a positive terminal of the first power storage unit and the electric load; a second switch (SW2) that switches between energizing and cutting off a second electric path (22) that connects a negative terminal of the second power storage unit and the electric load; a third switch (SW3) that switches between energizing and cutting off a third electric path (123) that connects the negative terminal of the first power storage unit and the electric load; and a fourth switch (SW4) that switches between energizing and cutting off a fourth electric path (24) that connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit. a fifth switch (SW5) that switches between energization and de-energization of a fifth electric path (125) that connects the positive terminal of the second power storage unit and the first electric path, wherein a first end of the third electric path is connected in the fourth electric path between the negative terminal of the first power storage unit and the fourth switch, a first end of the fifth electric path is connected in the fourth electric path between the fourth switch and the positive terminal of the second power storage unit, and a second end of the fifth electric path is connected to the first electric path at a side of the first switch to which the first power storage unit is connected, and a pre-charge circuit (71, 72, 73) is connected in parallel to any two of the first switch, the second switch, and the third switch.

5. The control system described in claim 4, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), the second end of the third electrical path is connected to the second electrical path between the electrical load and the second switch within the connection unit, and the third electrical path is connected to the electrical load via the second electrical path from the second end onwards, and the connection unit is connected to the positive side of the electrical load by the first electrical path and to the negative side of the electrical load by the second electrical path.

6. The control system of claim 4, wherein the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62); there are a plurality of electrical loads, and the plurality of electrical loads are divided into a first group of electrical loads (110a) and a second group of electrical loads (110b); and the connection unit is connected to the positive sides of the first group of electrical loads and the second group of electrical loads by the first electrical path, connected to the negative side of the first group of electrical loads by the second electrical path, and connected to the negative side of the second group of electrical loads by the third electrical path.

7. A control system according to any one of claims 1 to 6, wherein the first storage unit, the second storage unit, the fourth switch, and the fifth switch are configured as one battery unit (61), the first switch, the second switch, the third switch, and the precharge circuit are configured as one connection unit (62), and the second end of the fifth electrical path is connected to the first electrical path or the second electrical path within the battery unit, thereby connecting the battery unit and the connection unit via the first electrical path, the second electrical path, and the third electrical path.

8. A control system according to any one of claims 1 to 6, wherein the precharge circuit is connected in parallel to the first switch and the second switch, respectively.

9. A control system according to any one of claims 1 to 6, wherein the precharge circuit is connected in parallel to the second switch and the third switch, respectively.

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