POWER SUPPLY CONTROL DEVICE AND POWER SUPPLY SYSTEM

Abstract

Power supply control device (30) used in a power supply system comprising: a variety of electricity storage devices (12, 13) and a switching unit comprising a plurality of switching devices (21 to 25) which switch in electrical paths leading to each of the electrical storage devices and between a parallel state in which the plurality of electrical storage devices are connected in parallel to each other and a series state in which the plurality of electrical storage devices are connected in series to each other, and The switching unit switches the multitude of electrical storage devices between the series state and the parallel state in response to a switching request. wherein the power supply control device comprises: a procurement unit which, as a parameter indicating a state of the plurality of electrical storage devices, procures an electricity storage state parameter that is correlated with an amount of current flowing through a feed path including paths between each of the electrical storage devices in the parallel state or the series state, and a resistance control unit that adjusts a resistance value of a variable-resistance part present in the feed path in the parallel state or the series state based on the electricity storage state parameter, wherein In a case where the switching request is generated from the series state to the parallel state, the procurement unit procures the electricity storage state parameter both before and after the switching operation is completed by the switching unit. The resistance control unit performs an adjustment of a resistance value of the variable resistance part that is present in the supply path in the parallel state, based on the electricity storage state parameter before completion of switching and after completion of switching according to the switching request to the parallel state.

Description

Technical field

[0001] The present disclosure relates to a power supply control device used in a power supply system comprising a plurality of electrical storage devices, and to the power supply system. State of the art

[0002] In a power supply device comprising a plurality of storage batteries, a technique for switching between a state in which a plurality of storage batteries are connected in parallel and a state in which they are connected in series, corresponding to a power engine operating state, was conventionally known (see, for example, patent literature 1 (PTL1)). In particular, in a power engine automatic starting system, during power engine operation, the storage batteries are connected to a parallel state by a relay acting as a switching device, and the storage batteries are charged by a generator. Additionally, at the time of a restart after a power engine automatic stop, the storage batteries are switched to a series state by the relay, and power is supplied to a starter.It is then assumed that the configuration described above can make a power engine start smooth and can prevent deterioration of the storage battery. Citation list of patent literature

[0003] PTL1 JP 2003 - 155 968 A Summary of the invention

[0004] However, in a system that allows switching between a parallel and a series connection of a plurality of storage batteries as described above, connecting switching devices such as relays or switches are provided on each power supply path leading to a plurality of storage batteries, and since the number of relays or switches on the power supply path differs between the series and parallel states, a difference in the resistance of the power supply path is caused for each storage battery. Therefore, the charging / discharging currents flowing through the plurality of storage batteries differ, and as a result, a variation in the state of charge (SOC) of each storage battery occurs.If a SOC variation is generated in each storage battery, for example when a large number of storage batteries are switched from the series state to the parallel state, an overcurrent flows between the storage batteries due to the SOC difference, and can ultimately damage the storage battery, the switch, or the like.

[0005] The present disclosure was made with regard to the problem described above, and its main purpose is to provide a power supply control device and a power supply system capable of suppressing the generation of excessive current and ultimately achieving protection of an electrical storage device, switches and the like in a system comprising a plurality of electrical storage devices capable of series-parallel switching.

[0006] The power supply control device according to the present disclosure is used in a power supply system comprising a plurality of electrical storage devices and a switching unit comprising a plurality of switching devices provided in an electrical path leading to each of the electrical storage devices, and switching between a parallel state in which the plurality of electrical storage devices are connected in parallel to each other and a series state in which they are connected in series to each other, wherein the switching unit switches the plurality of electrical storage devices between the series state and the parallel state in response to a switching request.The power supply control device comprises a procurement unit that procures an electrical storage state parameter, which is correlated with an amount of current flowing through the supply path, including paths between each of the electrical storage devices in the parallel or series state, and a resistance control unit that adjusts a resistance value of a variable-resistance part present in the supply path in the parallel or series state based on the electrical storage state parameter.In a case where the switching request is generated from the series state to the parallel state, the procurement unit procures the electricity storage state parameter both before and after the switching is completed by the switching unit, and the resistance control unit adjusts a resistance value of the variable resistance part present in the supply path in the parallel state based on the electricity storage state parameter both before and after the switching is completed following the switching request to the parallel state.

[0007] In a power supply system that has a multitude of electrical storage devices, and allows switching between a parallel circuit and a series circuit of each electrical storage device by ON / OFF of a multitude of switching devices, there are concerns that, due to a varying state of charge (SOC) or the like in each electrical storage device, for example, an overcurrent may flow between the electrical storage devices due to capacity self-adjustment.In this respect, with the configuration described above, an electrical storage state parameter is obtained as a parameter specifying a state of a plurality of electrical storage devices. This parameter correlates with the amount of current flowing through the supply path, including paths between each of the electrical storage devices in the parallel or series state. A resistance value of the variable-resistance part present in the supply path in the parallel or series state is adjusted based on the electrical storage state parameter.In such a case, the current flowing through the supply path in the parallel or series state—that is, the current flowing between the electrical storage devices—can be controlled by adjusting the resistance value of the variable resistor. Even if a state-of-charge (SOC) variation occurs between the electrical storage devices, the flow of an overcurrent between them is suppressed. As a result, it is possible to achieve the appropriate use of each electrical storage device while simultaneously protecting the electrical storage device, the switch, and similar components.

[0008] It is also possible to suppress thermal damage to each of the switches 21 to 25 on the supply path by adjusting a switch resistance value based on the electrical storage state parameter of each of the lithium-ion storage batteries 12, 13. That is, a loss from each of the switches 21 to 25 can be suppressed by “loss = V·I = (V 2 ) / R" is determined using an output voltage difference or a supply current, which is generated from the SOC difference of each of the lithium-ion storage batteries 12, 13, and an on-resistance (switch-on resistance). In this case, the heat loss can be reduced by adjusting the on-resistance.

[0009] It should be noted that a configuration in which a series-parallel connection of a large number of electrical storage devices (for example, lithium-ion storage batteries) is carried out can be a configuration that has two or more electrical storage devices capable of series-parallel connection, and, for example, a power supply system that has three or more electrical storage devices also includes a configuration in which series-parallel connection is carried out for at least two electrical storage devices. Brief description of the drawings

[0010] The tasks, other functions, features, and advantages of the present disclosure described above will become clearer with reference to the following detailed description and the accompanying drawings. The drawings show: Fig. 1 an electrical circuit diagram illustrating a power supply system according to an exemplary embodiment, Fig. 2 a representation illustrating a specific configuration of a switch, Fig. 3(a) a representation illustrating a state in which the respective lithium-ion storage batteries are connected in parallel, and Fig. Figure 3(b) shows a representation illustrating a state in which the respective lithium-ion storage batteries are connected in series. Fig. 4(a) a representation illustrating a current flow during parallel charging, and Fig. Figure 4(b) shows a representation illustrating the current flow during parallel charging. Fig. 5 a representation illustrating current flow during a series discharge, Fig. 6 a diagram illustrating a relationship between a gate voltage and a drain-source resistance, Fig. 7. A flowchart illustrating a processing sequence for controlling a connection state and a charging / discharging current of a lithium-ion storage battery. Fig. 8 a graph illustrating a relationship between a difference ΔV of a supply voltage and a switch resistance value, Fig. 9 a graph illustrating a relationship between a switch temperature and a switch resistance value, Fig. 10 a graph illustrating a relationship between a difference ΔV of an application voltage, a switch temperature and a switch resistance value, Fig. 11 a time-course diagram to explain in more detail a resistance value control that accompanies a series-parallel connection of lithium-ion storage batteries, Fig. 12 a time-history diagram illustrating a change in feed current when lithium-ion storage batteries are switched from a series state to a parallel state, Fig. 13 a graph illustrating a relationship between a supply current and a switch resistance value, and Fig. 14 a graph illustrating a relationship between a supply current, a switch temperature and a switch resistance value. Description of exemplary implementations

[0011] An embodiment of the present disclosure is described below with reference to the drawings. The present disclosure embodies a vehicle-integrated power supply device for supplying power to various devices of a vehicle, which is powered by an internal combustion engine as a drive source. The present power supply system is a so-called dual power supply system, comprising a first power storage device with a lead-acid battery and a second power storage device with a plurality of lithium-ion batteries.

[0012] As it is in Fig. As shown in Figure 1, the present power supply system comprises a lead-acid storage battery 11 and two lithium-ion storage batteries 12, 13, and power can be supplied from each of the storage batteries 11 to 13 to various electrical loads 14, 15 and a rotating electric machine 16. Furthermore, each of the storage batteries 11 to 13 can be charged by the rotating electric machine 16.

[0013] The lead-acid battery 11 is a well-known general-purpose storage battery. In contrast, the lithium-ion storage battery 12, 13 is a high-density storage battery with lower power loss during charging and discharging, a higher output density, and a higher energy density compared to the lead-acid battery 11. The lithium-ion storage battery 12, 13 is preferably a storage battery with a higher energy efficiency during charging and discharging compared to the lead-acid battery 11. Additionally, the lithium-ion storage battery 12, 13 is configured as a composite battery with a plurality of electrical cells. The nominal voltage of these storage batteries 11 to 13 is the same, for example, 12 V.

[0014] A detailed explanation by illustration has been omitted; however, the two lithium-ion storage batteries 12, 13 are housed in a casing and configured as an integrated battery unit U. The battery unit U has two output terminals P1, P2, and output terminal P1 is connected to the lead-acid storage battery 11 and the electrical load 14, and output terminal P2 is connected to the electrical load 15 and the rotating electric machine 16.

[0015] The electrical load 14 connected to output terminal P1 is a 12V system load powered by a 12V supply from the lead-acid storage battery 11 or the lithium-ion storage batteries 12, 13. The electrical load 14 has a constant voltage requirement load, which requires stability so that the voltage of the supplied power is constant or at least fluctuates within a predetermined range, and a general electrical load other than the constant voltage requirement load.

[0016] A constant voltage demand load is a protected load and one for which a power supply error is not permissible. Specific examples of constant voltage demand loads include a navigation device, an audio device, a measuring device, and various ECUs for a power machine ECU. In this case, because the voltage fluctuation of the supplied power is suppressed, the occurrence of unnecessary resets or similar issues in each of the devices described above can be prevented, thus enabling stable operation. Additionally, specific examples of general electrical loads include lamps such as a headlight, a windshield wiper device, and an electrically driven pump.

[0017] Additionally, the electrical load 15 is a high-voltage system load for which, for example, a high driving force can be required temporarily during vehicle operation; that is, a high power output can be demanded. Specific examples include an electric power steering system. It should be noted that the electrical load connected to output terminal P1 corresponds to a low-voltage electrical load, and the electrical load 15 and the rotating electric machine 16 connected to output terminal P2 correspond to a high-voltage electrical load.

[0018] A rotating shaft of the rotating electric machine 16 is drivenly connected to a (not shown) power machine output shaft by a belt or the like, and while the rotating shaft of the rotating electric machine 16 rotates by rotation of the power machine output shaft, the power machine output shaft rotates by rotation of the rotating shaft of the rotating electric machine 16. The rotating electric machine 16 is a motor-generator (MG) and has a power generation function of performing power generation (regenerative power generation) by rotating the power machine output shaft or an axle, and a power driving function in which the power machine output shaft is subjected to a rotational force.For the rotating electric machine 16, adjustment of the power generation current during power generation and torque adjustment during power drive operation are performed by an inverter as a power conversion device, which is provided either integrally or separately. Engine start and torque support are provided by the drive of the rotating electric machine 16. The rotating electric machine 16 is an electrical load with respect to adding power to the engine output shaft and is also a high-power / high-current load in comparison to the electrical load 14.

[0019] A switch 17 is provided between the electrical load 15 and the rotating electrical machine 16, and the storage batteries 11 to 13 and the rotating electrical machine 16 are electrically connected to or disconnected from the electrical loads 15 by ON / OFF of the switch 17.

[0020] An electrical configuration of the battery unit U is described below. According to the present embodiment, two lithium-ion storage batteries 12, 13 can be switched between a parallel connection state and a series connection state, and this point is described in detail.

[0021] In battery unit U, switches 21 and 22 are connected in series in an electrical path L1 between output terminals P1 and P2. It should be noted that electrical path L1 is also part of the power supply path through which the electrical loads 14 and 15 and the rotating electric machine 16 are connected to the lead-acid battery 11 in this system. A positive terminal (positive electrode terminal) of the lithium-ion battery 12 is connected to a first point N1 between switches 21 and 22, and a positive terminal of the lithium-ion battery 13 is connected to a second point N2 between switch 22 and output terminal P2. Furthermore, switches 23 and 24 are each connected between a negative terminal (negative electrode terminal) of the lithium-ion battery 12 and ground, and between a negative terminal of the lithium-ion battery 13 and ground.Furthermore, the first point N1 is connected to a third point N3 between the negative terminal of the lithium-ion storage battery 13 and the switch 24, and a switch 25 is provided in a connecting path from this point. Switches 21 to 25 constitute a "switching unit".

[0022] Each of the switches 21 to 25 described above is constructed from a semiconductor switching element such as a MOSFET, an IGBT, or a bipolar transistor. According to the present embodiment, each of the switches 21 to 25 is constructed from the MOSFET, and the ON / OFF state of each of the switches 21 to 25 is switched in response to the application of a predetermined gate voltage.

[0023] It should be noted that, as it says in Fig. As shown in Figure 2, each of the switches 21 to 25 is configured to have a pair of MOSFETs, and the parasitic diodes of the MOSFET pair are preferably connected in series such that the diodes face opposite directions. Because the diodes face opposite directions, when each of the switches 21 to 25 is in an off state, any current flowing through a path in which each switch is provided is completely switched off. However, the configuration of a semiconductor switching element in each of the switches 21 to 25 is arbitrary; for example, a configuration can be used in which the parasitic diodes of the MOSFETs are not arranged to face each other.

[0024] By appropriately switching ON / OFF each of the switches 21 to 25, a state in which the lithium-ion storage batteries 12, 13 are connected in parallel and a state in which the lithium-ion storage batteries 12, 13 are connected in series can be switched.

[0025] Fig. Figure 3(a) shows a state in which the lithium-ion storage batteries 12, 13 are connected in parallel, and Fig. Figure 3(b) shows a state in which the lithium-ion storage batteries 12, 13 are connected in series. Fig. 3(a) and Fig. 3(b) For the sake of clarity, only the on-state switches are shown for switches 21 to 25, and an illustration of the off-state switches has been omitted. The in Fig. 3(a) The feed path shown is a “parallel feed path”, and the one shown in Fig. The power supply path shown in 3(a) is a "series power supply path". Note that switch 17 is off in the parallel state and is switched on as required in the series state.

[0026] In Fig. 3(a) Switches 21 to 24 are switched on and switch 25 is switched off, and in this state, the lithium-ion storage batteries 12, 13 are connected in parallel. In this case, both output voltages at output terminals P1, P2 are approximately 12V. In the parallel connection state, the lead-acid storage battery 11 and the lithium-ion storage batteries 12, 13 are connected in parallel to the electrical load 14 on the P1 side, and the lead-acid storage battery 11 and the lithium-ion storage batteries 12, 13 are connected in parallel to the rotating electric machine 16 on the P2 side. In the parallel connection state, the electrical load 14 is connected to an intermediate position (first point N1) on a path connecting the positive electrodes of the lithium-ion storage batteries 12, 13.

[0027] In Fig. 3(b) Switches 21, 23, and 25 are switched on, and switches 22 and 24 are switched off. In this state, the lithium-ion storage batteries 12 and 13 are connected in series. In this case, the output voltage of output terminal P1 is approximately 12 V, and the output voltage of output terminal P2 is approximately 24 V. In this series connection, the lead-acid storage battery 11 and the lithium-ion storage battery 12 are connected in parallel to the electrical load 14 on the P1 side. Furthermore, the lithium-ion storage batteries 12 and 13 are connected in series to the rotating electric machine 16 on the P2 side. In this series connection, the rotating electric machine 16 is connected to a position (the second point N2) on the positive electrode side of the high-voltage side of the lithium-ion storage batteries 12 and 13.

[0028] For the rotating electric machine 16, a 12 V power drive with a power supply voltage of 12 V and a 24 V power drive with a power supply voltage of 24 V are available. In a state where the lithium-ion storage batteries 12, 13 are connected in parallel, the rotating electric machine 16 is driven by 12 V, and in a state where the lithium-ion storage batteries 12, 13 are connected in series, the rotating electric machine 16 is driven by 24 V. The electrical load 15 connected to the output terminal P2 is driven by 24 V in a state where the lithium-ion storage batteries 12, 13 are connected in series.

[0029] According to Fig. In Figure 1, the battery unit U includes a control unit 30, which forms a battery control device. The control unit 30 switches each of the switches 21 to 25 in the battery unit U ON / OFF (open / close). In this case, the control unit 30 controls the ON / OFF operation of each of the switches 21 to 25 based on the vehicle's driving state and the state of charge of each of the storage batteries 11 to 13. This allows for selective charging and discharging using the lead-acid storage battery 11 and the lithium-ion storage batteries 12, 13. The charging and discharging control based on the state of charge of each of the storage batteries 11, 12 is briefly described.It should be noted that an illustration has been omitted, but that in each of the lithium-ion storage batteries 12, 13 a voltage sensor is provided to detect a voltage for each storage battery and a current sensor is provided to detect a supply current for each storage battery, and that the detection result of each sensor is output to the control unit 30.

[0030] The control unit 30 sequentially acquires input voltage values ​​for the lead-acid battery 11 and the lithium-ion batteries 12, 13, and sequentially acquires supply currents for the lead-acid battery 11 and the lithium-ion batteries 12, 13. Based on these acquired values, the control unit 30 then calculates open-circuit voltages (OCV) and states of charge (SOC) for the lead-acid battery 11 and the lithium-ion batteries 12, 13, and controls the charging and discharging quantities to and from the lithium-ion batteries 12, 13 such that the OCVs and SOCs are kept within a predetermined operating range.

[0031] In the battery unit U, after the main power is supplied to the vehicle, the lithium-ion storage batteries 12, 13 are essentially connected in parallel. In response to a load drive request at the output terminal P2 or a request for high-voltage power generation for the rotating electric machine 16, the lithium-ion storage batteries 12, 13 can be switched to series. In this case, the control unit 30 performs a control operation to temporarily switch the lithium-ion storage batteries 12, 13 from the parallel state to the series state, for example, based on the drive request of the electric steering device (electric load 15) or the torque support request from the rotating electric machine 16.

[0032] An ECU 40 is connected to the control unit 30. The control unit 30 and the ECU 40 are connected via a communication network such as CAN, allowing them to communicate and share various types of data stored in the control unit 30 and the ECU 40. The ECU 40 is an electronic control device with the function of performing an idle stop control of the vehicle. As is commonly known, the idle stop control automatically stops a motor when a predetermined automatic stop condition is met and restarts the motor when a predetermined restart condition is met after the automatic stop. In the vehicle, the motor is started by the rotating electric motor 16 during the automatic restart of the idle stop control.

[0033] Below is described operation during parallel charging, when the lithium-ion storage batteries 12, 13 are charged in the parallel connection state by the rotating electric machine 16, and operation during parallel discharging, when the lithium-ion storage batteries 12, 13 are discharged in the parallel connection state to the electrical load 14. Fig. 4(a) shows a current flow during parallel charging, and Fig. Figure 4(b) shows a current flow during parallel discharge.

[0034] During parallel charging according to Fig. 4(a) A power generation current is output by the rotating electric machine 16, and this power generation current charges the lead-acid storage battery 11 and the lithium-ion storage batteries 12, 13 and supplies power to the electrical load 14. In the battery unit U, switches 22, 23 are arranged in a charging path to the lithium-ion storage battery 12, and a charging current IiN1 flows corresponding to a path resistance value including switches 22, 23. Additionally, switch 24 is arranged in a charging path to the lithium-ion storage battery 13, and a charging current IiN2 flows corresponding to a path resistance value including switch 24. When comparing the charging currents IiN and IiN2, IiN1 is assumed to be greater than IiN2, and in particular, the difference in path resistance value is assumed to be "IiN1 < IiN2".

[0035] Additionally, during parallel discharge according to Fig. 4(b) Power is supplied to the electrical load 14 from the lithium-ion storage batteries 12, 13. Switches 21, 23 are arranged in a discharge path from the lithium-ion storage battery 12 to the electrical load 14, and a discharge current Iout1 flows corresponding to a path resistance value including switches 21, 23. Additionally, switches 21, 22, 24 are arranged in a discharge path from the lithium-ion storage battery 13 to the electrical load 14, and a discharge current Iout2 flows corresponding to a path resistance value including switches 21, 22, 24. When comparing the discharge currents Iout1 and Iout2, Iout1 is assumed to be greater than Iout2, and in particular, the difference in path resistance value is assumed to be "Iout1 > Iout2".

[0036] As described above, the magnitudes of the currents flowing through the respective lithium-ion storage batteries 12, 13 differ in the parallel state of the storage batteries 12, 13. Therefore, there is concern that a variation in the state of charge (SOC) (electrical capacity) is generated in each of the lithium-ion storage batteries 12, 13. Further explanation is given for this point. In the parallel state of charge according to Fig. 4(a) “Iin1 < Iin2” applies due to the difference in the path resistance value, while in the parallel discharge state according to Fig. 4(b) “Iout1 > Iout2” applies due to the difference in the path resistance value, and it is assumed that due to such a difference in current, the lithium-ion storage battery 13 has a higher SOC than the lithium-ion storage battery 12. However, when the state transitions to the series connection state (see Fig. 3(b)) assume that the difference in SOC of each of the storage batteries 12, 13 is greater.

[0037] This means that in the series discharge state, as it occurs in Fig. As shown in Figure 5, the lithium-ion storage battery 13 is discharged to the electrical load 15 and the rotating electrical load 16, whereas the lithium-ion storage battery 12 is discharged to the electrical load 14 in addition to the electrical load 15 and the rotating electrical machine 16. Accordingly, the discharge current Iout1 of the lithium-ion storage battery 12 is greater than the discharge current Iout2 of the lithium-ion storage battery 13, thus increasing the state of charge (SOC) difference between the storage batteries 12 and 13. If a variation is introduced in each of the lithium-ion storage batteries 12 and 13, the disadvantage is that the usable capacity of the respective storage batteries 12 and 13 cannot be fully utilized.

[0038] In a state where the state of charge (SOC) difference between the lithium-ion storage batteries 12 and 13 is large, a "capacitance self-adjusting current" flows when switching from the series to the parallel state due to the SOC difference (or a voltage difference) between the storage batteries 12 and 13. The capacity self-adjusting current is a current that flows according to the SOC difference between the lithium-ion storage batteries 12 and 13 and the path resistance value, and is defined, for example, as "I = equalizing voltage difference between storage batteries x path resistance value". In this case, a large current flows between the storage batteries, and there are concerns that adverse effects will be exerted on the switches and storage batteries on the supply paths.

[0039] Thus, according to the present embodiment, a parameter is obtained that correlates with the amount of current flowing through each of the lithium-ion storage batteries 12, 13, and current suppression is appropriately controlled based on this parameter. Specifically, the parameter correlated with the current between each of the lithium-ion storage batteries 12, 13 is an electricity storage state parameter, indicating the state of each of the lithium-ion storage batteries 12, 13, and a switch state parameter, indicating the state of each of the switches 21 to 25, is obtained, and a switch resistance value of any of the switches 21 to 25 is adjusted based on each of these parameters. According to the present embodiment, when the lithium-ion storage batteries 12, 13 are in the parallel state, a switch resistance value of switch 22 is adjusted.Additionally, when the lithium-ion storage batteries 12 and 13 are in series, a switch resistance value of switch 25 is adjusted. It should be noted that the control unit 30 corresponds to the "procurement unit" and the "resistance value control unit".

[0040] The electricity storage state parameter, for example, is the connection voltage, state of charge (SOC), and / or charging and discharging current of each of the lithium-ion storage batteries 12 and 13. Additionally, the temperature of each of the lithium-ion storage batteries 12 and 13 is obtained. The switch state parameter, for example, is the temperature of each of the switches 21 to 25.

[0041] The resistance value control in the parallel state and the resistance value control in the series state, which are carried out by the control unit 30, are described below.

[0042] In the parallel state, there is a Fig. 3(a) The supply path shown in the battery unit U is formed, and in a situation where a difference in state of charge (SOC) has occurred in the lithium-ion storage batteries 12, 13, there is a concern that an overcurrent will flow between the storage batteries 12, 13. Therefore, to suppress the overcurrent, the control unit 30 adjusts the resistance value of the switch 22, which is located in the intermediate position between the storage batteries 12, 13, to one side of increasing the resistance value of the switch 22 in the supply path in the parallel state, based on the state of charge parameter of each of the lithium-ion storage batteries 12, 13. In doing so, the control unit 30 obtains a difference ΔV in the connection voltage of each of the lithium-ion storage batteries 12, 13 and performs a control based on ΔV, thereby controlling the resistance value of the switch 22 to a desired value.More precisely, the control unit 30 controls the resistance value of switch 22 by performing gate voltage control of switch 22. This increases the resistance value of switch 22 in an on state, and consequently decreases the current between the storage batteries. This control regulates the current between the storage batteries to a desired value.

[0043] The resistance value control of switch 22 changes the resistance value of switch 22 and ultimately the path resistance value between the lithium-ion storage batteries 12, 13, for example, by using a relationship between a gate voltage Vg and a drain-source resistance, which is given in Fig. Figure 6 shows how to adjust the drain-source resistance by controlling the gate voltage Vg. Fig. 6 is based on a resistance value R minIn a normal on state, a relationship is defined in which the gate voltage Vg is decreased to increase the drain-source resistance, and the switch resistance value (drain-source resistance) is variably set to one side where the switch resistance value is greater than R. min is done.

[0044] It should be noted that it is possible to determine whether an overcurrent flows in this situation by using the SOC or the charging and discharging current of each of the lithium-ion storage batteries 12, 13 as the electricity storage state parameter, and also to control the resistance value of the switch 22 on the basis of the SOC or the charging and discharging current of each of the lithium-ion storage batteries 12, 13 in the situation in which the overcurrent flows.

[0045] In addition to the electricity storage state parameter, the switch state parameter is also used in this embodiment to implement current suppression control. In this case, the control unit 30 obtains the temperature of switch 22 as the switch state parameter, with switch 22 serving as an adjustment target in the parallel state. Based on the switch temperature, the control unit 30 then adjusts the resistance value of switch 22 to reduce the current between the storage batteries. Specifically, the control unit 30 controls the resistance value of switch 22 to a desired value by regulating the temperature of switch 22. This increases the resistance value of switch 22 in the "on" state and consequently reduces the current between the storage batteries.

[0046] In the series state, the in Fig. 3(b) The power supply path shown in the battery unit U is formed, and when the power supply voltage formed by both of the lithium-ion storage batteries 12, 13 is high, there is a concern that an overcurrent will flow through the power supply path between the storage batteries 12, 13 and the electrical load 15 or the rotating electrical machine 16. In fact, there is a concern that an overcurrent will flow through a smoothing capacitor provided in the electrical load 15 and the rotating electrical machine 16. Therefore, to suppress the overcurrent, the control unit 30 adjusts the resistance value of the switch 25, which is located at the intermediate position between each of the storage batteries 12, 13 in the power supply path in the series state, to one side of increasing the resistance value of the switch 25, based on the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13.The control unit 30 procures a series power supply voltage (combined voltage Vhi) by obtaining the sum of the terminal voltages of each of the lithium-ion storage batteries 12, 13 and controls the resistance of switch 25 to a desired value by performing a regulation based on Vhi. More precisely, the control unit 30 controls the resistance of switch 25 by performing gate voltage control of switch 25. This increases the resistance of switch 25 in the on state and correspondingly reduces the current between the storage batteries. This control regulates the current between the storage batteries to a desired value.

[0047] The resistance value control of the switch 25 in the series state, as during the parallel state, changes the resistance value of the switch 25 and ultimately the path resistance value of the supply path between the storage batteries 12, 13 and the electrical load 15 or the rotating electrical machine 16, for example by using the relationship according to Fig. 6, to adjust the drain-source resistance by controlling the gate voltage Vg.

[0048] Additionally, the control unit 30 obtains the temperature of switch 25 as a switch state parameter, with switch 25 as an adjustment target in the series state. Then, to reduce the current between the storage batteries, the control unit 30 adjusts the resistance value of switch 25 by either increasing or decreasing it based on the switch temperature. Specifically, the control unit 30 controls the resistance value of switch 25 by regulating its temperature to a desired value. This increases the resistance of switch 25 in the "on" state and consequently reduces the current between the storage batteries.

[0049] Additionally, in a configuration where the series-parallel state of each of the lithium-ion storage batteries 12, 13 is switched as required, there are concerns that immediately after series-parallel switching, an overcurrent flows through the electrical path between the storage batteries, which accompanies the change in the connection state, and in particular, there is a risk that immediately after switching, the overcurrent cannot be temporarily suppressed due to a delay in the control.

[0050] Thus, according to the present embodiment, when a series-to-parallel switching request is generated, feedforward control is performed for a predetermined period from the time of the request until at least the completion of the switching, thereby suppressing the generation of the overcurrent immediately after the series-to-parallel switching. This feedforward control, taking into account the state after the series and parallel switching states, controls the resistance value by using a parameter in the state after the switching.

[0051] At the time of switching from the series state to the parallel state, the control unit 30 obtains, within a predetermined time period from the switching request time, the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 and the switching parameter of the switch 22 to be adjusted, which is present on the supply path in the parallel state, and performs the feedforward control based on each of the parameters.

[0052] At the time of switching from the parallel state to the series state, the control unit 30 obtains, within a predetermined time period from the switching request time, the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 and the state parameter of the switch 25 to be adjusted, which is present on the supply path in the series state, and performs the feedforward control based on each of the parameters.

[0053] Fig. Figure 7 shows a flowchart illustrating the processing sequence for controlling the connection state and the charging and discharging current of each of the lithium-ion storage batteries 12, 13. This processing is repeatedly performed by the control unit 30 according to a predetermined cycle. It should be noted that this processing is performed during both the discharging and charging phases of each of the lithium-ion storage batteries 12, 13. However, this processing can only be performed during either the discharging or the charging phase.

[0054] According to Fig. In step S11, the electricity storage state parameter is obtained, and in step S12, the switch state parameter is obtained. According to the present embodiment, the electricity storage state parameter is the charging and discharging current, the connection voltage, and / or the state of charge (SOC), which are recorded for each of the lithium-ion storage batteries 12, 13. The switch state parameter is the temperature of the switches 22, 25, which are provided between the lithium-ion storage batteries 12, 13.

[0055] In step S13, it is then determined whether a state flag indicating the parallel and series states to which the lithium-ion storage batteries 12 and 13 are switched is set. A state flag of 1 indicates that they are in the parallel state, and a state flag of 0 indicates that they are in the series state. If the state flag is 1, processing proceeds to step S14, and if the state flag is 0, processing proceeds to step S19. It should be noted that in the case of a state flag of 1, the switching request time from the series state to the parallel state and the time after switching are included in the sequence, and in the case of a state flag of 0, the switching request time from the parallel state to the series state and the period after switching are included in the sequence.

[0056] In step S14, it is determined whether the lithium-ion storage batteries 12, 13 are to be switched from the series state to the parallel state, that is, whether the state flag is to be switched from 0 to 1. For example, in a case where the 24V drive of the electric load 15 or the rotating electric machine 16 is terminated, the switching request from the series state to the parallel state is generated.

[0057] Then, when the switching request time arrives, the processing proceeds to step S15, and the execution of the switching of the lithium-ion storage batteries 12, 13 from the series state to the parallel state is instructed. Specifically, of the switches 21 to 25 of battery unit U, switches 22, 24 are switched "OFF→ON" and switch 25 is switched "ON→OFF". It should be noted that switching off switch 25 can be performed before switching on switches 22, 24. Additionally, for switching on switches 22, 24, and 25, one of the switches can be performed first and the other can be performed later. By switching switches 22, 24, and 25 ON / OFF, the lithium-ion storage batteries 12, 13 are switched to the parallel state.

[0058] In step S15, if a switch to the parallel state is performed, or if a negative determination is made in step S14, processing proceeds to step S16. Step S16 determines whether a predetermined time has elapsed since the switching request from the series state to the parallel state. The predetermined time is the sum of the time required for the state switch from the series state to the parallel state and a control delay time, for example, a time of approximately a few milliseconds to a few tens of milliseconds. If step S16 is positive, processing proceeds to step S17, and if step S16 is negative, processing proceeds to step S18. It should be noted that if an initial state is set to the parallel state after the vehicle has started, a positive determination is made in step S16.

[0059] In step S17, a control system adjusts the switch resistance value in the power supply path of each of the lithium-ion storage batteries 12 and 13. This adjustment is based on the electricity storage state parameter of each lithium-ion storage battery 12 and 13 and the state parameter of the switch 22 to be adjusted, which is in the parallel state in the power supply path. This controls the current flowing between the lithium-ion storage batteries 12 and 13 to a desired value. It should be noted that the control unit 30 adjusts the switch resistance value using either digital-to-analog control or PWM control (the same applies to steps S18, S22, and S23 described later).

[0060] In particular, the control unit 30 uses the terminal voltage of each of the lithium-ion storage batteries 12, 13 as the electricity storage state parameter to calculate a terminal voltage difference ΔV. Then the control unit 30 uses the relationship of Fig. 8 for determining an adjustment resistance value of switch 22 based on the connection voltage difference ΔV. In Fig. Equation 8 defines a relationship that states that as the connection voltage difference ΔV increases, the adjustment resistance value of switch 22 also increases. A larger value in relation to the resistance value (minimum value R) min ) of switch 22 in a fully ON state is set to the adjustment resistance value (the same applies to Fig. 9 and Fig. 10, which are described below).

[0061] Alternatively, control unit 30 uses the relationship of Fig. 9 for determining the adjustment resistance value of switch 22 based on a temperature of switch 22 as the switch state parameter. In Fig. 9 defines a relationship that, as the switch temperature increases, the adjustment resistance value of switch 22 increases.

[0062] As described above, in a case where the switch resistance value is calculated based on the electricity storage state parameter and the switch resistance value is calculated based on the switch state parameter, the larger of the resistance values ​​of switch 22 calculated by the respective calculations can be determined as the adjustment resistance value of switch 22 to be applied at that time. For example, if the resistance value calculated using the relationship of Fig. 8. The calculated resistance value R1 is and the one obtained by using the relationship of Fig. If the calculated resistance value R2 is greater than R1 and R1 > R2, the resistance value R1 is determined as the adjustment resistance value of switch 22 to be applied at that time. Alternatively, a configuration can be used in which the smaller of the switch resistance values ​​calculated based on the electricity storage state parameter and the switch resistance value calculated based on the switch state parameter is determined as the adjustment resistance value of switch 22 to be applied at that time, or a configuration can be used in which the average of the respective switch resistance values ​​is determined as the adjustment resistance value of switch 22 to be applied at that time.

[0063] It should be noted that the adjustment resistance value of switch 22 can be determined using a relationship of Fig. 10 can be determined. In Fig. Section 10 defines the relationship between the terminal voltage difference ΔV of each of the lithium-ion storage batteries 12, 13, the temperature of the switch 22, and the adjustment resistance value of the switch 22. In this case, the adjustment resistance value of the switch 22 is set based on each of the parameters described above.

[0064] In step S18, the switch resistance value in the parallel supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by feedforward control. This feedforward control is based on the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 and the state parameter of the switch 22 to be adjusted, which is present in the supply path in the parallel state.

[0065] Step S18 is performed after the switching request from the series state to the parallel state is generated and before the switching to the parallel state is complete. However, since the switching to the parallel state is incomplete at this point, the electricity storage state parameter cannot be obtained in the parallel state. Therefore, in the series state, the control unit 30 obtains the terminal voltage of each of the lithium-ion storage batteries 12 and 13 as the electricity storage state parameter and calculates the difference ΔV of the terminal voltage of each of the storage batteries 12 and 13 based on each of the terminal voltages. Then, the adjustment resistance value of the switch 22 is determined based on the terminal voltage difference ΔV. At this time, the adjustment resistance value of the switch 22 can be determined using the relationship of Fig. 8. It should be noted that in step S18 the electricity storage state parameter is obtained in the series state as the electricity storage state parameter in the parallel state.

[0066] Alternatively, the control unit 30 obtains the temperature of switch 22 on the parallel power supply path as the switch state parameter and determines the adjustment resistance value of switch 22 based on the switch temperature. The adjustment resistance value of switch 22 can be determined using the relationship of Fig. 9 will be set.

[0067] As described above, in a case where the switch resistance value is calculated based on the electricity storage state parameter and the switch resistance value is calculated based on the switch state parameter, for example, as in step S12, the larger of the resistance values ​​of switch 22 calculated by the respective calculations can be determined as the resistance value of switch 22 to be applied at that time. Alternatively, in step S17, the resistance value of switch 22 can be determined by using the relationship of Fig. 10 will be determined.

[0068] Additionally, in a state where the state flag is set to 0 in step S13 (i.e., a state where it is determined that the system is in the series state), step S19 determines for the lithium-ion storage batteries 12 and 13 whether it is the switching request time from the parallel state to the series state, i.e., whether it is the switching time "1⇒0" of the state flag. For example, in a case where the 24V drive of the electric load 15 or the rotating electric machine 16 is started, the switching request from the parallel state to the series state is generated.

[0069] Then, when the switching request time arrives, the processing proceeds to step S20, and the execution of the switching of the lithium-ion storage batteries 12, 13 from the parallel state to the series state is instructed. Specifically, among the switches 21 to 25 of battery unit U, switches 22, 24 are switched "ON→OFF" and switch 25 is switched "OFF→ON". It should be noted that at this time, the OFF switching of switches 22, 24 can be performed first and the ON switching of switch 25 can be performed later. Additionally, for switches 22, 24, one of the switches can be switched OFF first and the other later. By switching switches 22, 24, and 25 ON / OFF, the lithium storage batteries 12, 13 are switched to the series state.

[0070] If the switch to the parallel state is performed in step S20, or if a negative determination is made in step S19, processing proceeds to step S21. Step S21 determines whether a predetermined time has elapsed since the switching request from the parallel state to the series state. This predetermined time is the sum of the time required for the state switch from the parallel state to the series state and a control delay time, for example, a time ranging from a few milliseconds to several tens of milliseconds. If step S21 is positive, processing proceeds to step S22; if step S21 is negative, processing proceeds to step S23.

[0071] In step S22, the switch resistance value in the supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by the control system. This adjustment is based on the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 and the state parameter of the switch 25 to be adjusted, which is present in the supply path in series. This controls the current flowing between the lithium-ion storage batteries 12, 13 to a desired value.

[0072] In particular, the control unit 30 uses the terminal voltage of each of the lithium-ion storage batteries 12, 13 as the electricity storage state parameter to calculate a combined voltage Vhi (i.e., a voltage value of the output terminal P2) of the lithium-ion storage batteries 12, 13 in the series state. The control unit 30 uses the relationship of Fig. 8 (where the horizontal axis is Vhi) to determine an adjustment resistance value of switch 25 based on the voltage Vhi. In Fig. Equation 8 defines a relationship such that as the voltage Vhi increases, the adjustment resistance value of switch 25 also increases. Alternatively, control unit 30 uses the relationship of Fig. 9 to determine an adjustment resistance value of the switch 25 based on the temperature of the switch 25 as the switch state parameter.

[0073] As described above, in a case where the switch resistance value is calculated based on the electricity storage state parameter, and the switch resistance value is calculated based on the switch state parameter, the larger of the resistance values ​​of switch 25 calculated by the respective calculations can be determined as the adjustment resistance value of switch 25 to be applied at that time.

[0074] It should be noted that the adjustment resistance value of switch 25 can be determined using the relationship of Fig. 10 (where, however, the horizontal axis is Vhi) can be determined. In Fig. Figure 10 defines a relationship between the combined voltage Vhi of the lithium-ion storage batteries 12, 13, the temperature of the switch 25, and the adjustment resistance value of the switch 25. In this case, the adjustment resistance value of the switch 25 is calculated based on each of the parameters described above.

[0075] In step S23, the switch resistance value in the series feed path of each of the lithium-ion storage batteries 12, 13 is adjusted by feedforward control. This feedforward control is based on the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 and the state parameter of the switch 25 to be adjusted, which is present in the series state in the feed path.

[0076] Step S23 is performed after the switching request from the parallel state to the series state has been generated and before the switching to the series state is complete. However, since the switching to the series state is incomplete at this point, the electricity storage state parameter cannot be obtained in the series state. Then, in the parallel state, the control unit 30 obtains the terminal voltage of each of the lithium-ion storage batteries 12 and 13 as the electricity storage state parameter and calculates the combined voltage Vhi of each of the storage batteries 12 and 13 based on the terminal voltages. The adjustment resistance value of switch 25 is then determined based on the combined voltage Vhi. At this time, the adjustment resistance value of switch 25 can be determined using the relationship of Fig. 8 is set (where, however, the horizontal axis is Vhi). It should be noted that in step S23, the electricity storage state parameter is obtained in the parallel state as the electricity storage state parameter in the series state.

[0077] Alternatively, the control unit 30 obtains the temperature of switch 25 on the series supply path as the switch state parameter and determines the adjustment resistance value of switch 25 based on the switch temperature. The adjustment resistance value of switch 25 can be determined using the relationship of Fig. 9 will be set.

[0078] As described above, in a case where the switch resistance value is calculated based on the electricity storage state parameter and the switch resistance value is calculated based on the switch state parameter, for example, as in step S22, the larger of the resistance values ​​of switch 22 calculated by the respective calculations can be determined as the resistance value of switch 25 to be applied at that time. Alternatively, as in step S22, the resistance value of switch 25 can be determined by using the relationship of Fig. 10 can be determined (it should be noted that the horizontal axis is Vhi).

[0079] Fig. Figure 11 shows a time-course diagram to explain in more detail the resistance value control, which accompanies the series-parallel connection of the lithium-ion storage batteries 12, 13.

[0080] According to Fig. 11, when the switching request from the series state to the parallel state is generated at time t1, the switching from the series state to the parallel state is carried out by the switching operation of switches 21 to 25 during a period from t1 to t3. Specifically, at time t2, of the switches 21 to 25 of battery unit U, switch 25 is switched "ON→OFF" first, and at the subsequent time t3, switches 22 and 24 are switched "OFF→ON". The switching to the parallel state is completed at time t3. At this time, since switch 25 is switched to OFF first, a ground fault in each of the lithium-ion storage batteries 12 and 13 is suppressed.

[0081] Furthermore, at times t1 to t4, the switch resistance value in the supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by the feedforward control. At this time, in anticipation of the transition to the parallel state, the switch resistance value of switch 22, which is present in a path between the batteries in the parallel state, is adjusted such that no excessive current flows through switch 22 in the parallel state. That is, during a predetermined time period "t1 to t4", which includes time t3, the time of completion of the parallel connection, the switch resistance value is adjusted by the feedforward control using the parameter obtained in the series state as any parameter obtained in the parallel state.

[0082] Then, at time t4, the switch resistance value in the supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by the control system. At this time, as in the preceding feedforward control, the switch resistance value of switch 22 is adjusted so that no excessive current flows through switch 22.

[0083] Furthermore, if the switching request from the parallel state to the series state is generated at time t5, the switching from the parallel state to the series state is carried out by the switching operation of switches 21 to 25 during a period from t5 to t7. Specifically, at time t6, switches 22 and 24 of battery unit U are first switched "ON→OFF", and at the subsequent time t7, switch 25 is switched "OFF→ON". The switching to the series state is completed at time t7. At this time, since switch 25 is switched ON later, a ground fault in each of the lithium-ion storage batteries 12 and 13 is suppressed.

[0084] Furthermore, at times t5 to t8, the switch resistance value in the supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by the feedforward control. At this time, in anticipation of the transition to the series state, the switch resistance value of switch 25, which is present in a path between the batteries in the series state, is adjusted such that no excessive current flows through switch 25 into the series state. That is, during a predetermined time period "t5 to t8", which includes time t7, the point at which the series connection is completed, the switch resistance value is adjusted by the feedforward control using the parameter obtained in the parallel state, which is obtained as any parameter in the series state.

[0085] Fig. Figure 12 shows a time-course diagram illustrating a change in the supply current when the lithium-ion storage batteries 12, 13 are switched from the series state to the parallel state. The in Fig. The supply current value shown in Figure 12 is a current value flowing through the switch 22, which is positioned in the supply path between the lithium-ion storage batteries 12, 13 in the parallel state. A solid line shows a current change obtained by control according to the present embodiment, and a dashed line indicates a current change when control according to the present embodiment is not carried out.

[0086] According to Fig. The switching request from the series state to the parallel state is generated at time t11, and the switching from the series state to the parallel state is completed by the switching operation of switches 21 to 25 at time t12. Then, during a time period tx (t11 to t13), which includes time t12, the feedforward control is performed. With existing conventional technology, there is a concern immediately after time t12 that an overcurrent will be generated in the parallel state, i.e., in the state of charge (SOC) at switch 22, due to the difference in state of charge (SOC) between the lithium-ion storage batteries 12 and 13, as indicated by the dashed line between the lithium-ion storage batteries 12 and 13. In contrast, according to the present embodiment, a reduction in the current value is achieved by adjusting the switch resistance value through feedforward control.

[0087] Furthermore, at time t13 and thereafter, the switch resistance value in the supply path of each of the lithium-ion storage batteries 12, 13 is adjusted by the control system. For example, the adjustment resistance value of switch 22 is determined based on the difference ΔV in the connection voltage of each of the lithium-ion storage batteries 12, 13. At this time, the supply current value is controlled with an overcurrent threshold Th as the upper limit. At time t14, if the supply current value is less than the overcurrent threshold Th, the switch resistance value assumes a small value (R). min ) . Thus, the occurrence of an unnecessary loss is suppressed.

[0088] Although an illustration is omitted, the feedforward control during the switching from parallel to series operation suppresses the generation of an inrush current to the electrical load 15 and the rotating electric machine 16 immediately after switching. This means that when the lithium-ion storage batteries 12, 13 are switched from parallel to series, the output voltage to the rotating electric machine 16 (or similar device) changes from 12V to 24V, and there is a concern that an inrush current could flow, for example, to a smoothing capacitor in the rotating electric machine 16 due to the voltage difference. In this respect, the inrush current can be reduced by adjusting the switch resistance value via the feedforward control.

[0089] It should be noted that, considering that the electrical load 15 and the rotating electrical machine 16 each have a smoothing capacitor, there is a concern that an inrush current due to discharge from the smoothing capacitor will also be generated when switching from the series to the parallel state. However, in this respect too, the inrush current can be reduced by adjusting the switch resistance value via the feedforward control.

[0090] According to the present embodiment, which has been described in detail above, the following excellent effects can be obtained.

[0091] With the configuration described above, an electricity storage state parameter, indicating the state of a plurality of lithium-ion storage batteries 12, 13, is obtained, and the resistance value of a switch present in the supply path in the parallel or series state is adjusted based on the electricity storage state parameter. In such a case, a current flowing through the supply path in the parallel or series state, that is, a current flowing between the lithium-ion batteries 12, 13, and the like, can be controlled by adjusting the switch resistance value, and even if a state of charge (SOC) variation is generated between the storage batteries, it is possible to prevent an overcurrent flow between the storage batteries. As a result, each of the lithium-ion storage batteries 12, 13 can be used appropriately.A suitable use of each of the lithium-ion storage batteries 12, 13 makes it possible to suppress deterioration or destruction of each of the storage batteries 12, 13, of semiconductor switching elements forming the switches 21 to 25, wiring harness and the like.

[0092] Adjusting the switch resistance value based on the electricity storage state parameter of each of the lithium-ion storage batteries 12, 13 also makes it possible to suppress thermal damage at each of the switches 21 to 25 on the supply path. That is, a loss at each of the switches 21 to 25 by “loss = V·I = (V 2) / R" using an output voltage difference or a supply current, which is generated from the SOC difference of each of the lithium-ion storage batteries 12, 13 respectively, and an on-resistance. In this case, the heat loss can be reduced by adjusting the on-resistance.

[0093] If an overcurrent between the lithium-ion storage batteries 12, 13 can be suppressed, it becomes possible to reduce the design measures required to mitigate overcurrents. In this case, a design for overcurrent suppression can be eliminated, ultimately reducing costs. Furthermore, it becomes unnecessary to limit an output to suppress state-of-charge (SOC) variation in each of the lithium-ion storage batteries 12, 13 in anticipation of overcurrent generation. This eliminates the need to limit the capacity of a storage battery and allows for sufficient utilization of its capabilities.

[0094] In a case where the path resistance value of the parallel supply path or the series supply path in the battery unit U is changed, a configuration can be applied in which the resistance value of switch 22 on the parallel supply path or the resistance value of switch 25 on the series supply path is changed to one side of increasing the resistance value of the switch. That is, a configuration can be applied in which the resistance value of each of the switches 22, 23 in a fully ON state (minimum resistance value R) min) is changed on one side of the resistance value being increased. In this case, it is possible to prevent the charging and discharging current from becoming excessively large and to achieve protection for each of the lithium-ion storage batteries 12, 13. Additionally, considering that the switches 22, 25 are constructed from semiconductor switching elements such as MOSFETs, it is possible to easily adjust the resistance value by controlling the gate voltage of the semiconductor switching elements.

[0095] In a case where a state of charge (SOC) difference exists between the lithium-ion storage batteries 12 and 13, an overcurrent due to this difference can occur when the batteries are connected in parallel. When the lithium-ion storage batteries 12 and 13 are switched from series to parallel, an overcurrent can occur during the switching process. Since the resistance value of switch 22 on the parallel supply path is adjusted based on the state of charge of the storage batteries in the parallel state, the occurrence of this overcurrent can be appropriately suppressed.

[0096] When the lithium-ion storage batteries 12, 13 are switched from the series state to the parallel state, an instantaneous current flows, accompanying the change in the connection state. However, if the switch resistance value is adjusted after the switching operation is complete, the response to the instantaneous current can be delayed. In this respect, since the switch resistance value is adjusted based on the electricity storage state parameter before and after the switching operation to the parallel connection state, the generation of the instantaneous current at the time of the switch to the parallel state can be suppressed.

[0097] When the lithium-ion storage batteries 12, 13 are switched from the series state to the parallel state, the response to the instantaneous current may be delayed because the electricity storage state parameter in the parallel state is not obtained at the time of completion of the switching or the like.In this respect, since the electricity storage state parameter in the series state is obtained as the electricity storage state parameter in the parallel state after the switching request to the parallel state and before completion of the parallel switching, and the switch resistance value is adjusted by the feedforward control by using the electricity storage state parameter obtained as the electricity storage state parameter in the parallel state during a predetermined time period including a time of completion of the parallel switching, the response to the instantaneous current can be carried out instantaneously at the time of switching to the parallel state.

[0098] In the parallel state, the resistance value of switch 22, located between the lithium-ion storage batteries 12 and 13, is adjusted by switches 22 to 24, which are present on the parallel supply path. In this case, a suitable configuration can be implemented to achieve the protection of each of the lithium-ion storage batteries 12 and 13.

[0099] When the lithium-ion storage batteries 12, 13 are switched from the parallel state to the series state, there is a concern that an instantaneous current (load inrush current) may be generated at the time the switch to the series state is completed. In this respect, since the resistance value of the switch 25 on the series supply path is adjusted based on the electricity storage state parameter in the series state, the generation of this overcurrent can be appropriately suppressed.

[0100] When the lithium-ion storage batteries 12, 13 are switched from the parallel state to the series state, an instantaneous current (load inrush current) flows, accompanying the change in the connection state. However, if the switch resistance value is adjusted after the switching operation is complete, the response to the instantaneous current can be delayed. In this respect, since the switch resistance value is adjusted based on the electricity storage state parameter before and after the switching operation is completed, the generation of the instantaneous current at the time of the switch to the series state can be suppressed.

[0101] When the lithium-ion storage batteries 12, 13 are switched from the parallel state to the series state, the response to the instantaneous current may be delayed because the electricity storage state parameter in the series state is not obtained at the time of completion of the switching or the like.In this respect, since the electricity storage state parameter in the parallel state is obtained as the electricity storage state parameter in the series state after the switching request to the series state and before completion of the series switching, and the switch resistance value is adjusted by the feedforward control using the electricity storage state parameter in the parallel state, which is obtained as the electricity storage state parameter in the series state, during a predetermined time period including a time of completion of the series switching, the response to the instantaneous current can be carried out instantaneously at the time of switching to the series state.

[0102] In the series configuration, the resistance value of switch 25, located between the lithium-ion storage batteries 12 and 13, is adjusted by switches 23 and 25, which are present on the series supply path. In this case, a suitable configuration can be implemented to protect each of the lithium-ion storage batteries 12 and 13.

[0103] A configuration can be used in which the charging and discharging current, the connection voltage, and / or the state of charge (SOC) of each of the lithium-ion storage batteries 12, 13 are obtained as the electricity storage state parameters, and the switch resistance value is adjusted based on the obtained results. In this case, the control and feedforward control can be performed appropriately according to the actual electricity storage state of each of the lithium-ion storage batteries 12, 13.

[0104] A configuration can be used in which the switch resistance value is adjusted at any time during the discharge and charging phases of each of the lithium-ion storage batteries 12, 13. This can enable suitable use of the battery unit U, which incorporates the lithium-ion storage batteries 12, 13 as a secondary battery.

[0105] Since switches 21 to 25 are configured from semiconductor switching elements, a desired current control can be easily achieved by gate voltage control of MOSFETs or the like.

[0106] Since the semiconductor switching elements are used as switches 21 to 25, a system with higher operational reliability can be constructed compared to a case where a contact-type switch (a so-called mechanical switch) is used. Furthermore, the semiconductor switching element reduces losses in the power supply path because the resistance value can be made much lower compared to the mechanical switch.

[0107] One configuration can be used in which a pair of MOSFETs is used as each of the switches 21 to 25, and the MOSFETs are connected in series such that their parasitic diodes are oppositely oriented. This makes it possible to appropriately switch off the current flowing through the supply path when each switch 21 to 25 is turned off.

[0108] A configuration can be used in which switches 21 to 25 are used for series-parallel connection as a variable-resistance component, and the switch resistance values ​​are adjusted to perform current control. In this case, current control is achieved by utilizing the fact that an ON resistance is created in each of the switches 21 to 25, making it possible to control the current flowing through each of the lithium-ion storage batteries 12, 13 and the switches as desired without complicating the configuration.

[0109] A configuration can be used where the gate voltage control is performed by a digital-to-analog converter or a PWM controller for each of the switches 21 to 25, which are the targets for resistance value adjustment. This allows for easy adjustment of the resistance value. A highly efficient system can be implemented with PWM control, as the power loss due to current during the off-state of the duty cycle is theoretically zero.

[0110] Additionally, the path resistance value is controlled by using a series-parallel switching switch, which is provided as a basic function of the battery unit U, and the control unit 30 performs the switching control of it, thus making it possible to achieve a desired adjustment processing of a resistance value without adding any element or the like to the unit's basic configuration.

[0111] Since the charging and discharging current flowing through each of the lithium-ion storage batteries 12, 13 is controlled by using a switch temperature as the switch state parameter, it is possible to implement current control in addition to a thermal factor in a suitable manner. This makes it possible to prevent thermal damage to the lithium-ion storage batteries 12, 13 and to each switch. Other examples of implementation

[0112] The embodiments described above can be modified as follows, for example.

[0113] In the regulation or the input control, which according to the above described Fig. 7. Control or feedforward control can be performed by using the supply current and / or the state of charge (SOC) of the lithium-ion storage batteries 12, 13 as the electricity storage state parameters instead of or in addition to the terminal voltage of the lithium-ion storage batteries 12, 13. A configuration can be used in which two or more of the charge / discharge current, the terminal voltage, and the SOC are obtained as the electricity storage state parameters, and the switch resistance value is adjusted using these parameters. In this case, increasing the number of available parameters can improve the accuracy of the current control and increase the safety margin against damage.

[0114] A configuration can be used in which a temperature from each of the lithium-ion storage batteries 12, 13 is obtained as the electricity storage state parameter, and the switch resistance value is adjusted based on the acquisition result. In particular, a “temperature” in Fig. 9 or Fig. 10 is set as a battery temperature, and then the switch resistance value can be adjusted based on the relationship of Fig. 9 or Fig. 10. In this case, a suitable configuration to achieve protection of each of the storage batteries 12, 13 can be implemented by additionally controlling or feedforward the battery temperature. Unlike electrical parameters such as the charging and discharging current, the terminal voltage, and the state of charge (SOC), the battery temperature is a parameter that can be obtained at any time regardless of a series-parallel state (i.e., a switching state) and can be appropriately monitored for the state of each of the lithium-ion storage batteries 12, 13.

[0115] Another configuration can be used where a supply current in at least one of the switches present in the parallel or series supply path is obtained as the switch state parameter, and the switch resistance parameter is adjusted based on the procurement result. Specifically, the switch resistance value is determined based on the switch supply current using a relationship of Fig. 13 set. Alternatively, the switch resistance value is determined based on the switch supply current and the switch temperature using a relationship of Fig. 14 is set. In this case, the regulation can also be implemented according to the actual switch state.

[0116] According to the embodiment described above, the configuration can be used in which the switch resistance value is adjusted by using both the electricity storage state parameter and the switch state parameter, but this can be changed to a configuration in which the switch resistance value is adjusted by using only one of these parameters.

[0117] According to the embodiment described above, the configuration can be used in which the resistance value of switch 22 is adjusted in the parallel state, and the resistance value of switch 25 is adjusted in the series state; however, this can be modified. A configuration can be used in which the resistance value of at least one of the switches 22, 23, and 24, which are present in the parallel power supply path, is adjusted in the parallel state. Additionally, a configuration can be used in which the resistance value of at least one of the switches 23 and 25, which are present in the series power supply path, is adjusted in the series state.

[0118] A configuration can be used where the switch used to obtain a switch state parameter and the switch that is to be a target for resistance adjustment are different from each other. For example, a configuration can be used where, from switches 22, 23, and 24, which are present in the parallel power path in the parallel state, the switch state parameter for switch 22 is obtained, and the resistance value adjustment is performed for any one of switches 23 or 24. Additionally, a configuration can be used where, from switches 23 and 25, which are present in the series power path in the series state, the switch state parameter for switch 23 is obtained, and the resistance value adjustment is performed for switch 25.

[0119] A configuration can be used in which an overcurrent threshold is predefined to determine that an overcurrent has flowed in the supply path, including the path between the lithium-ion storage batteries 12 and 13, and the control unit 30 determines the presence or absence of an overcurrent based on this threshold. In such a case, the control unit 30 is configured to set an overcurrent threshold based on the charge and discharge current, the state-of-charge (SOC) connection voltage, and / or the battery temperature as the electricity storage state parameters. In a state where an overcurrent is minimal, the overcurrent threshold can be set low. Additionally, a configuration can be used in which the current threshold is set based on the switch supply current and / or the switch temperature as the switch state parameters.

[0120] According to the embodiment described above, the configuration can be used in which, in a state where a plurality of lithium-ion storage batteries are connected in parallel, the charging and discharging current of each lithium-ion storage battery is individually controlled by adjusting a switch resistance value to one side of increasing the switch resistance value. However, this can be changed to a configuration in which the charging and discharging current of each lithium-ion storage battery is individually controlled by adjusting a switch resistance value to one side of decreasing the switch resistance value. For example, in a case where a switch resistance value (initial resistance value) is not the minimum value when the switch is normally ON, the switch resistance value is adjusted to one side of decreasing the switch resistance value.

[0121] A configuration can be used in which a device other than the lithium-ion storage battery is used for a variety of electrical storage devices. For example, any of the following configurations can be used for the variety of electrical storage devices: a configuration using a storage battery other than the lithium-ion storage battery, a configuration using a storage battery and a capacitor, and a configuration using a variety of capacitors.

[0122] According to the embodiment described above, the configuration can be used in which the resistance value of a switch for connecting a plurality of lithium-ion storage batteries in series-parallel is adjusted when switched on, thereby individually controlling the charging and discharging current for each of the lithium-ion storage batteries. However, this can be modified. For example, a configuration can be used in which another switch, constructed from semiconductor switching elements, is provided in the power supply path of the battery unit U in addition to the switch for series-parallel connection. The ON resistance value of this other switch is adjusted, thereby individually controlling the charging and discharging current for each of the lithium-ion storage batteries.

[0123] Besides using the semiconductor switching element as the variable resistance part, a variable resistor (variable resistance component) can also be used.

[0124] The present revelation is described according to functioning examples; however, it should be understood that the present revelation is not limited to these functioning examples and structures. The present revelation also exhibits various variations and modifications within an equivalent range. Additionally, various combinations and forms, and further combinations and forms that contain only one element, more than one, or less than one, are also included in the category and concept of the present revelation.

Claims

[1] Power supply control device (30) used in a power supply system comprising: a variety of electricity storage devices (12, 13) and a switching unit comprising a plurality of switching devices (21 to 25) which switch in electrical paths leading to each of the electrical storage devices and between a parallel state in which the plurality of electrical storage devices are connected in parallel to each other and a series state in which the plurality of electrical storage devices are connected in series to each other, and The switching unit switches the multitude of electrical storage devices between the series state and the parallel state in response to a switching request. wherein the power supply control device comprises: a procurement unit which, as a parameter indicating a state of the plurality of electrical storage devices, procures an electricity storage state parameter that is correlated with an amount of current flowing through a feed path including paths between each of the electrical storage devices in the parallel state or the series state, and a resistance control unit that adjusts a resistance value of a variable-resistance part present in the feed path in the parallel state or the series state based on the electricity storage state parameter, wherein In a case where the switching request is generated from the series state to the parallel state, the procurement unit procures the electricity storage state parameter both before and after the switching operation is completed by the switching unit. The resistance control unit performs an adjustment of a resistance value of the variable resistance part that is present in the supply path in the parallel state, based on the electricity storage state parameter before completion of switching and after completion of switching according to the switching request to the parallel state. [2] Power supply control device according to claim 1, characterized by , that The procurement unit procures the electricity storage state parameter in the series state as well as the electricity storage state parameter in the parallel state after the switching request to the parallel state and before completion of the parallel switching, and The resistance control unit performs an adjustment of a resistance value of the variable resistance part by means of a feedforward control using an electricity storage state parameter in the series state, which is obtained as the electricity storage state parameter in the parallel state, during a predetermined time period including a time of completion of the parallel switching after the switching request to the parallel state. [3] Power supply control device according to claim 1 or 2, characterized by , that the resistance control unit performs an adjustment of a resistance value of the variable resistance part (22) that is present between the plurality of electrical storage devices in the supply path in the parallel state. [4] Power supply control device according to one of claims 1 to 3, characterized by, that in a case where a switching request is generated from the parallel state to the series state, the procurement unit procures the electricity storage state parameter both before and after the switching is completed by the switching unit, and the resistance control unit adjusts a resistance value of the variable resistance part present in the supply path in the series state based on the electricity storage state parameter both before and after the switching is completed following the switching request to the series state. [5] Power supply control device according to claim 4, characterized by , that The procurement unit procures the electricity storage state parameter in the parallel state as the electricity storage state parameter in the series state after the switching request to the series state and before completion of the series switching, and The resistance control unit performs an adjustment of a resistance value of the variable resistance part by means of a feedforward control using an electricity storage state parameter in the parallel state, which is obtained as the electricity storage state parameter in the series state, during a predetermined time period including a time of completion of the series switching after the switching request to the series state. [6] Power supply control device according to claim 4 or 5, characterized by , that the resistance control unit performs an adjustment of a resistance value of the variable resistance part (25) that is present between the plurality of electrical storage devices in the supply path in the series state. [7] Power supply control device (30) used in a power supply system which has: a variety of electricity storage devices (12, 13) and a switching unit comprising a plurality of switching devices (21 to 25) which switch in electrical paths leading to each of the electrical storage devices and between a parallel state in which the plurality of electrical storage devices are connected in parallel to each other and a series state in which the plurality of electrical storage devices are connected in series to each other, and The switching unit switches the multitude of electrical storage devices between the series state and the parallel state in response to a switching request. wherein the power supply control device comprises: a procurement unit which, as a parameter indicating a state of the plurality of electrical storage devices, procures an electricity storage state parameter that is correlated with an amount of current flowing through a feed path including paths between each of the electrical storage devices in the parallel state or the series state, and a resistance control unit that adjusts a resistance value of a variable-resistance part present in the feed path in the parallel state or the series state based on the electricity storage state parameter, wherein In a case where a switching request is generated from the parallel state to the series state, the procurement unit procures the electricity storage state parameter both before and after the switching operation is completed by the switching unit. The resistance control unit performs an adjustment of a resistance value of the variable resistance part that is present in the supply path in the series state, based on the electricity storage state parameter before completion of switching and after completion of switching according to the switching request to the series state. [8] Power supply control device according to claim 7, characterized by , that The procurement unit procures the electricity storage state parameter in the parallel state as the electricity storage state parameter in the series state after the switching request to the series state and before completion of the series switching, and The resistance control unit performs an adjustment of a resistance value of the variable resistance part by means of a feedforward control using an electricity storage state parameter in the parallel state, which is obtained as the electricity storage state parameter in the series state, during a predetermined time period including a time of completion of the series switching after the switching request to the series state. [9] Power supply control device according to claim 7 or 8, characterized by , that the resistance control unit performs an adjustment of a resistance value of the variable resistance part (25) that is present between the plurality of electrical storage devices in the supply path in the series state. [10] Power supply control device according to any one of claims 1 to 9, characterized by, that the resistance control unit, in a case where the supply path is assumed to be in a situation where an overcurrent greater than a predetermined value flows in the parallel state or the series state, changes a resistance value of the variable resistance part based on the electricity storage state parameter to one side of increasing the resistance value. [11] Power supply control device according to any one of claims 1 to 10, characterized by , that the procurement unit procures a charging and discharging current, a connection voltage and / or a state of charge as the electricity storage state parameter in at least one of the multitude of electrical storage devices, and the resistance control unit performs an adjustment of a resistance value of the variable resistance part based on the procurement result of the procurement unit. [12] Power supply control device according to any one of claims 1 to 11, characterized by , that The procurement unit procures a temperature of at least one of the multitude of electrical storage devices as the electricity storage state parameter, and The resistance control unit performs an adjustment of a resistance value of the variable resistance part based on the procurement result by the procurement unit. [13] Power supply control device according to any one of claims 1 to 12, characterized by , that the resistance control unit performs an adjustment of a resistance value of the variable resistance part during a discharge time and / or a charging time of the multitude of electrical storage devices. [14] Power supply control device according to any one of claims 1 to 13, characterized by, that the variable resistance part has a semiconductor switching element, and the resistance control unit performs an adjustment of a resistance value in an ON state of the semiconductor switching element. [15] Power supply control device according to any one of claims 1 to 13, characterized by , that the resistance control unit uses any of the multitude of switching devices as the resistance variable part to perform an adjustment of a resistance value of the switching device. [16] Power supply control device according to claim 15, characterized by , that the switching device includes a semiconductor switching element, and The resistance control unit performs an adjustment of a resistance value in an ON state of the semiconductor switching element. [17] Power supply control device according to claim 14 or 16, characterized by, that the resistance control unit performs an adjustment of a resistance value of the semiconductor switching element by digital-analog control or PWM control. [18] Power supply system with a power supply control device according to any one of claims 1 to 17, a variety of electrical storage devices, and a switching unit.

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