Power supply unit and battery unit

Abstract

A power supply device applicable to a power supply system comprising a first storage battery (11) and a second storage battery (12), the first and second batteries being connected in parallel to a first electrical load (15) and a second electrical load (16), respectively, the power supply device comprising: a first switch (21) inserted in a supply path (L1) through which a supply current for the first and second electrical loads (15, 16) flows, a second switch (22) inserted into the supply path (L1), a third switch (23) inserted into the supply path (L1), wherein each of the first, second and third switches is configured to establish an electrical connection of the supply path or to interrupt the electrical connection of the supply path, a first point (N1) provided at a first end of the first switch (21), the first switch (21) having the first end and a second end as both ends thereof, and the second switch (22) is provided at the second end of the first switch (21), a second point (N2) provided between the first switch (21) and the second switch (22), a third point (N3) provided between the second switch (22) and the third switch (23), a fourth point (N4) provided at a first end of the third switch (23), the third switch (23) having the first end and a second end as both ends thereof, and the second switch (22) being provided at the second end of the third switch (23), wherein each of the first storage battery (11), the second storage battery (12), the first electrical load (15) and the second electrical load (16) is connected to a corresponding one of the first, second, third and fourth points, and a control unit (30) configured to control switching on and off operations of each of the first to third switches (21, 22, 23), wherein one of the first and second storage batteries (11, 12) is defined as a priority battery which is preferably used, and the other of the first and second storage batteries (11, 12) is defined as a non-priority battery, the control unit (30) is configured to control the switching on and off operations of each of the first to third switches (21, 22, 23) according to a parameter comprising a state of charge and a temperature of the first and second storage batteries (11, 12), and the control unit (30) is configured to perform a first discharge mode in which the priority battery supplies electrical power to the first and second electrical loads (15, 16), in any one of: first case, in which the state of charge of the priority battery is higher than the state of charge of the non-priority battery as a result of a comparison between the priority and non-priority batteries, and to select a second case in which the state of charge of the non-priority battery is higher than the state of charge of the priority battery as a result of a comparison between the priority and non-priority batteries, and the state of charge of the priority battery is greater than a predetermined state of charge threshold or the temperature of the priority battery is lower than a predetermined temperature threshold, wherein the control unit (30) is configured to switch between a second discharge mode and a third discharge mode according to the state of charge and / or the temperature of the priority battery when the state of charge of the non-priority battery is higher than the state of charge of the priority battery, wherein the second discharge mode is configured such that the priority battery supplies electric power to one of the first and second electrical loads (15, 16), and the non-priority battery supplies electric power to the other of the first and second loads, and the third discharge mode is configured such that the non-priority battery supplies electrical power to each of the first and second electrical loads (15, 16).

Description

Technical area

[0001] The present disclosure relates to power supply devices and battery units that can be installed, for example, in a vehicle. BACKGROUND

[0002] A power supply system known as an on-vehicle power supply system, which can be installed in a vehicle, for example, includes a plurality of storage batteries such as lead-acid batteries or lithium-ion batteries. This power supply system selects the batteries to be used to supply power to various loads (see Patent Literature 1 for an example).

[0003] For example, switches are provided on respective supply paths, the supply paths extending from a power generator to the respective batteries. Controlling the batteries according to the charge rate of each battery to select one of the batteries allows the power generator to charge the selected one of the batteries via the corresponding supply path. Citation listPatent literaturePatent literature 1

[0004] Japanese Patent Application Publication No. JP 2011 - 15 516 A

[0005] JP 2015 154 618 A discloses a battery unit with a lithium storage battery, in which a lead storage battery is connected to a first terminal, a rotating machine is connected to a second terminal, and an electrical load is connected to a third terminal. The battery unit includes main connections that connect the terminals and connect the lithium storage battery to a battery connection point, auxiliary connections through which the terminals are connected in parallel with the channels and an electrical load is connected to a load connection point, switches provided in the main connections, switches provided in the auxiliary connections, and a switch provided in a bypass connection for connecting the battery connection point and the load connection point.The switches in the auxiliary connections in the bypass connection are controlled in such a way that a current flow through the load connection point to the auxiliary connections is prevented.

[0006] DE 10 2014 103 545 A1 discloses a power supply system mounted in a vehicle. A rotating machine is connected to an output shaft of an internal combustion engine of the vehicle and has a power generation function, a starting function, and an output assist function for the internal combustion engine. A connection switch is configured to electrically connect and disconnect a second secondary battery and a parallel connection of a first secondary battery and a rotating machine. A first battery switch, connected between the first secondary battery and a first node disposed between the first secondary battery and the connection switch, is configured to electrically connect and disconnect the first secondary battery and the first node. A first electrical load is electrically connected to the first node.A second electrical load is electrically connected to the second node located between the second secondary battery and the connection switch.

[0007] WO 2014 / 068 884 A1 discloses a power supply device comprising: a lead-acid battery and a nickel-metal hydride battery that supply power to electrical devices of a vehicle; a main switch connected between the lead-acid battery and the electrical devices; a sub-switch connected between the nickel-metal hydride battery and the electrical devices; and a control circuit that controls the supply of operating power from the lead-acid battery and the nickel-metal hydride battery to the electrical devices of the vehicle. The nickel-metal hydride battery is connected to an alternator of the vehicle via the sub-switch and the main switch.The control circuit is equipped with a residual capacity detection circuit and a switching circuit, and switches the sub-switch and the main switch on and off via the switching circuit according to the residual capacity of the nickel-metal hydride battery detected by the residual capacity detection circuit. Technical problem

[0008] Various power supply targets are provided in a battery system. For example, appropriate power from each battery is supplied to a plurality of electrical loads as such power supply targets. The electrical loads include constant-voltage loads and / or high-power loads. Constant-voltage loads require constant-voltage drive, and high-power loads require high-power drive.

[0009] When the batteries supply power to the electrical loads described above, one of the batteries may be over-stressed and / or a power supply to one of the electrical loads may have a negative effect on the power supply to the other electrical loads. Therefore, opportunities exist to improve this aspect.

[0010] The present disclosure aims to address these issues. Specifically, a primary object of the present disclosure is to provide power supply devices and battery units, each of which enables each storage battery to appropriately supply appropriate electric power to electrical loads. Solution to the problem

[0011] This object is achieved by a power supply device as defined in claim 1 and alternatively by a battery unit as defined in claim 9.

[0012] Advantageous embodiments are specified in the dependent patent claims.

[0013] A power supply device according to a first aspect of the present disclosure is applicable to a power supply system including a first storage battery and a second storage battery, the first and second batteries being connected in parallel to a first electrical load and a second electrical load, respectively. The power supply device includes a first switch inserted in a feed path through which a feed current for the first and second electrical loads flows, a second switch inserted in the feed path, and a third switch inserted in the feed path. Each of the first, second, and third switches is configured to establish electrical connection of the feed path or to interrupt electrical connection of the feed path. The power supply device includes a first point provided at a first end of the first switch.The first switch has the first end and a second end as both ends thereof, and the second switch is provided at the second end of the first switch. The power supply device has a second point provided between the first switch and the second switch, and a third point provided between the second switch and the third switch. The power supply device has a fourth point provided at a first end of the third switch. The third switch has the first end and a second end as both ends thereof, and the second switch is provided at the second end of the third switch. Each of the first battery, the second battery, the first electrical load, and the second electrical load is connected to a corresponding one of the first, second, third, and fourth points.The power supply device includes a control unit configured to control on and off operations of each of the first to third switches.

[0014] In the power supply device according to the first aspect, the first, second, and third switches connected in series are inserted in the first feed path through which the feed current for the first and second electrical loads flows. Each of the first battery, the second battery, the first electrical load, and the second electrical load is connected to a corresponding one of the first, second, third, and fourth points. Each of the first to fourth points constitutes one of both ends of a corresponding one of the first to third switches. Controlling the on-off operations of each of the first to third switches by the control unit enables easy changing of a connection configuration selected from among the first and second storage batteries and the first and second electrical loads.This allows for easy selection of one of the first and second storage batteries as a power source for supplying electrical power to each of the electrical loads. This allows for preferential use of one of the first and second storage batteries and / or reducing the load on each of the first and second batteries based on the use of the corresponding one of the batteries. This results in an appropriately selected power supply from the first and second storage batteries to each of the first and second electrical loads.

[0015] Note that a configuration in which each of the first battery, the second battery, the first electrical load, and the second electrical load is connected to a corresponding one of the first, second, third, and fourth points means a configuration in which the first battery, the second battery, the first electrical load, and the second electrical load provided for the first, second, third, and fourth points are connected to each other. That is, this configuration in which each of the first battery, the second battery, the first electrical load, and the second electrical load is connected to a corresponding one of the first, second, third, and fourth points has: (1) a configuration in which each of the first battery, the second battery, the first electrical load, and the second electrical load is directly connected to a corresponding one of the first, second, third, and fourth points, (2) a configuration in which each of the first battery, the second battery, the first electrical load, and the second electrical load is indirectly connected to a corresponding one of the first, second, third, and fourth points.

[0016] According to the second aspect of the present disclosure, the control unit is configured to control the turning on and off operations of each of the first to third switches according to a parameter including a charge status and / or a temperature of the first and second storage batteries, to thereby switch between (1) a first discharge mode in which the first storage battery supplies electrical power to the first and second electrical loads, (2) a second discharge mode in which the first storage battery supplies electric power to one of the first and second electric loads, and the second storage battery supplies electric power to the other of the first and second electric loads, (3) a third discharge mode in which the second storage battery supplies electrical power to the first and second electrical loads.

[0017] As described above, the first, second and third switches connected in series are inserted into the feed path, and each of the first battery, the second battery, the first electrical load and the second electrical load is connected to a corresponding one of the first, second, third and fourth points.

[0018] This configuration allows switching between the on and off states of each of the first to third switches, thereby selecting one of the first and second storage batteries as a power source for supplying electric power to the first and second electrical loads. That is, this configuration allows selecting: (1) the first discharge mode in which the first storage battery supplies electric power to the first and second electric loads, (2) the second discharge mode in which the first storage battery supplies electric power to one of the first and second electric loads and the second storage battery supplies electric power to the other of the first and second electric loads, (3) the third discharge mode in which the second storage battery supplies electric power to the first and second electric loads.

[0019] A condition for selecting any one of the first and second storage batteries as a power source may be changed depending on the charging status and / or the temperature of each of the first and second storage batteries.

[0020] In this regard, the above-described configuration selects one of the first discharge mode, the second discharge mode, and the third discharge mode according to the parameter including the charge status and / or temperature of each of the first and second storage batteries. This configuration therefore prevents the charged capacity and / or temperature conditions of any of the first and second storage batteries from being excessively deteriorated. This therefore enables the use of the first and second storage batteries while reducing a load on each of the first and second storage batteries based on the use of the corresponding one of the first and second storage batteries.

[0021] According to the third aspect of the present disclosure, one of the first and second storage batteries is defined as a priority battery that is preferentially used, and the other of the first and second storage batteries is defined as a non-priority battery. The parameter includes the charge status and temperature of each of the first and second storage batteries.

[0022] The control unit is configured to select a first discharge state (a first discharge mode) in which the priority battery supplies electric power to the first and second electric loads in any one of a first case in which the state of charge of the priority battery is higher than the state of charge of the non-priority battery as a result of a comparison between the priority and non-priority batteries, and a second case in which (1) the charge status (state of charge) of the non-priority battery is higher than the charge status of the priority battery as a result of a comparison between the priority and non-priority batteries, (2) a charged capacity (state of charge) of the priority battery is greater than a predetermined charged capacity threshold (state of charge threshold value) or the temperature of the priority battery is lower than a predetermined temperature threshold value.

[0023] The control unit is configured to switch between a second discharge state and a third discharge state according to the charged capacity and / or the temperature of the priority battery when the charge status of the non-priority battery is higher than the charge status of the priority battery. The second discharge state is configured such that the priority battery supplies electrical power to one of the first and second electrical loads, and the non-priority battery supplies electrical power to the other of the first and second loads. The third discharge state is configured such that the non-priority battery supplies electrical power to each of the first and second electrical loads.

[0024] The third embodiment preferentially uses the priority battery among the first and second storage batteries, and uses the non-priority battery when determining that use of the non-priority battery is necessary depending on a change in the charged capacity and / or temperature of the priority battery. Therefore, this configuration selectively uses the first and second storage batteries depending on whether one of the first and second storage batteries is preferentially used, and reduces the load on each of the first and second storage batteries based on the use of the corresponding one of the first and second storage batteries.

[0025] Assuming that a lithium-ion battery is defined as the priority battery and a lead-acid battery is defined as the non-priority battery, it is possible to preferentially use the lithium-ion battery, which has higher energy efficiency, and to use the lead-acid battery when it is determined that the use of the lead-acid battery is necessary. This therefore allows the use of the lithium-ion battery, which has higher energy efficiency, to be given priority over the lead-acid battery. Reducing the load on the lead-acid battery prevents deterioration of the lead-acid battery.

[0026] According to the fourth aspect of the present disclosure, the first and second storage batteries are respectively connected to the first to fourth points, which are the two outermost points of the first to fourth points, and the first and second electrical loads are respectively connected to the second and third points. The circuit configuration according to the fourth aspect of the present disclosure is shown, for example, in Fig. 1, by reference numeral (a) of Fig. 8, or by reference numeral (a) of Fig. 9 illustrates.

[0027] In each example, the first and second storage batteries are connected to the respective first and fourth points, which form the two outer points of the series connection circuit having the first to third switches. In addition, the first electrical load and the second electrical load are connected to the respective middle second and third points. Turning on and off operations of the first to third switches in the connection configuration enables the first to third discharge modes to be switched. This enables electric power supply to be performed to the first and second electrical loads in a desired manner, while resulting in the power supply device having a simplified configuration.

[0028] According to the fifth aspect of the present disclosure, the first storage battery has a first battery characteristic curve indicating a relationship between a state of charge (SOC) of the first battery and an open-circuit voltage of the first storage battery. The second storage battery has a second battery characteristic curve indicating a relationship between the state of charge of the second storage battery and the open-circuit voltage of the second storage battery. Values of the open-circuit voltage within a predetermined first region of the state of charge in the second battery characteristic curve are higher than values of the open-circuit voltage within a second region of the state of charge in the first battery characteristic curve. The second region corresponds to the first region. The second storage battery is connected to one of the first and fourth points that form the outer points of the first to fourth points.The first battery, the first electrical load and the second electrical load are connected to the remaining points of the first to fourth points.

[0029] The circuit configuration according to the fifth embodiment of the present disclosure is shown, for example, in Fig. 1, by reference numeral (a) of Fig. 8, reference symbol (b) of Fig. 8, reference symbol (a) of Fig. 9, reference symbol (b) of Fig. 9, reference symbol (a) of Fig. 10 or reference symbol (b) of Fig. 10. In each example, the second storage battery is connected to one of the first and fourth points constituting the two outer points of the series connection circuit including the first to third switches. In addition, the first battery, the first electrical load, and the second electrical load are connected to the remaining points of the first to fourth points. Turning on and off operations of the first to third switches in the connection configuration enables switching of the first to third discharge modes. This enables the electric power supply to be performed to the first and second electrical loads in a desired manner, while resulting in the power supply device having a simplified configuration.

[0030] According to the sixth aspect of the present disclosure, the first storage battery has a first battery characteristic curve indicating a relationship between a state of charge (SOC) of the first storage battery and an open-circuit voltage of the first storage battery. The second storage battery has a second battery characteristic curve indicating a relationship between the state of charge of the second storage battery and the open-circuit voltage of the second storage battery. Values of the open-circuit voltage within a predetermined first region of the state of charge in the second battery characteristic curve are higher than values of the open-circuit voltage within a predetermined second region of the state of charge in the first battery characteristic curve, the second region corresponding to the first region. One of the first and second electrical loads is connected to one of the first and fourth points constituting the two outer points of the first to fourth points.The second storage battery is connected to one of the remaining three points other than the point to which one of the first and second electrical loads is connected. The first storage battery is connected to one of the remaining two points such that the point to which the first storage battery is connected and one of the first and fourth points sandwich the point to which the second storage battery is connected. The other of the first and second electrical loads is connected to the last remaining point. The power supply device further includes a bypass route connecting the point to which the first storage battery is connected and one of the outer points, and a bypass switch inserted in the bypass route, wherein the control unit is configured to control on / off operations of the bypass switch.

[0031] The circuit configuration according to the sixth embodiment of the present disclosure is denoted, for example, by reference character (c) of Fig. 8, reference symbol (d) of Fig. 8, reference symbol (c) of Fig. 9, reference symbol (d) of Fig. 9, reference symbol (c) of Fig. 10 or reference symbol (d) of Fig. 10. In each example, one of the first and second electrical loads is connected to one of the first and fourth points constituting the two outermost points of the first to fourth points. The second storage battery is connected to one of the remaining three points except for the point to which one of the first and second electrical loads is connected. The first storage battery is connected to one of the remaining two points such that the point to which the first storage battery is connected and one of the first and fourth points sandwich the point to which the second storage battery is connected. The other of the first and second electrical loads is connected to the last remaining point.In the configuration described above, it would become difficult to cause the first storage battery to discharge electric power to the first and second electric loads while the first and second electric loads are disconnected from the second storage battery.

[0032] In this regard, the bypass route is connected between the point to which the first storage battery is connected and one of the external points, and the bypass switch is inserted into the bypass route. Turning on and off the first to third switches and the bypass switch in the above-described connection configuration enables switching of the first to third discharge modes. This enables the electric power supply to the first and second electric loads to be performed in a desired manner.

[0033] According to the seventh aspect of the present disclosure, the first storage battery and one of the first and second electrical loads are connected to the first point and the second point, respectively. The second storage battery and the other of the first and second electrical loads are connected to the third point and the fourth point, respectively.

[0034] The circuit configuration according to the seventh embodiment of the present disclosure is shown, for example, in Fig. 1, by one of the reference numerals (a) to (d) of Fig. 8, or by one of the reference numerals (a) to (d) of Fig. 9. The first and second points are nodes located on one side of the feed path via the middle second switch, and the third and fourth points are nodes located on the other side of the feed path via the middle second switch. The first storage battery and one of the first and second electrical loads are connected to the first point and the second point, respectively. The second storage battery and the other of the first and second electrical loads are connected to the third point and the fourth point, respectively. This configuration makes it possible to prevent voltage variations in the first storage battery 11 due to the driving of one of the first and second electrical loads from affecting the driving of the other of the first and second electrical loads.

[0035] According to the eighth aspect of the present disclosure, the first electrical load is an electrical load that requires a voltage of the supplied electrical power to be maintained at a constant level or to vary stably within a predetermined range. The second electrical load is an electrical load to which electrical power or an electrical current is supplied, wherein the electrical power or an electrical current supplied to the second electrical load is higher than the electrical power or an electrical current supplied to the first electrical load.

[0036] When the first electrical load is a constant-voltage load and the second electrical load is an electrical load to which higher electrical power or higher electrical current is supplied, power supply to the second electrical load may have an influence on the power supply to the first electrical load depending on the charge status of each of the first and second storage batteries. In this regard, this configuration according to the eighth aspect makes it possible to easily select one of the first and second storage batteries as a power source for supplying electric power to each of the first and second electrical loads. This configuration therefore leads to a reduction in mutual interference between the power supply to the first electrical load and the power supply to the second electrical load.

[0037] According to the ninth aspect of the present disclosure, the first electrical load is an electrical load that requires a voltage supplied to the electrical load to be maintained at a constant level or to stably vary within a predetermined range. The second electrical load is a rotating electrical machine that is rotatably driven based on electric power or electric current. The electric power or electric current for rotatably driving the rotating electrical machine is higher than the electric power or electric current for driving the first electrical load.

[0038] When the first electrical load is a constant-voltage load and the second electrical load is a rotating electrical machine, the power supply to the second electrical load may have an influence on the power supply to the first electrical load depending on the charge status of each of the first and second storage batteries. In this regard, this configuration according to the ninth aspect makes it possible to easily select one of the first and second storage batteries as a power source for supplying electric power to each of the first and second electrical loads. This configuration therefore leads to a reduction in mutual interference between the power supply to the first electrical load and the power supply to the second electrical load.

[0039] According to the tenth aspect of the present disclosure, one of the first and second storage batteries is connected to one of the first and fourth points constituting the two outermost points of the first to fourth points, or the first and second storage batteries are respectively connected to the first and fourth points constituting the two outermost points of the first to fourth points. The power supply device further includes a malfunction determination unit configured to determine whether there is a malfunction in one of the first and second storage batteries connected to one of the first and fourth points. The control unit is configured, when determining that there is a malfunction, to control the first to third switches to thereby: (1) to disconnect from the supply path one of the first and second storage batteries connected to one of the first and fourth points, (2) cause the remaining storage battery to supply electrical power to the first and second electrical loads.

[0040] According to the tenth aspect, when it is determined that there is a malfunction in one of the first and second storage batteries connected to one of the first and fourth points, power supply is performed from the other of the first and second storage batteries to the first and second electrical loads while the storage battery with the malfunction is disconnected from the power supply path. This configuration, even if there is a malfunction in one of the first and second storage batteries, uses the remaining other storage battery within its usable range to thereby continuously supply electric power to the first and second electrical loads. This results in providing measures against a power supply failure of one of the first and second storage batteries.

[0041] The eleventh aspect of the present disclosure is a battery unit including the power supply device according to any one of the first to tenth aspects. The battery unit includes the second storage battery, a first terminal, a second terminal, and a third terminal. The first storage battery, the first electrical load, and the second electrical load are connected to the first, second, and third terminals, respectively. The first to third switches are inserted into the feed path through which the first storage battery, the first electrical load, and the second electrical load are connected to the second storage battery.

[0042] Connecting the first storage battery, the first electrical load, and the second electrical load to the respective first, second, and third terminals in the battery unit having the second storage battery enables power supply from the first and second storage batteries to the first and second electrical loads to be properly performed. Short description of the drawings Fig. 1 shows an electrical circuit diagram illustrating a battery system according to an embodiment of the present disclosure. Fig. 2A shows a graph showing a SOC usage range of a Fig. 1 illustrated lead-acid battery. Fig. Figure 2B shows a graph showing a SOC usage range of a Fig. 1 illustrated lithium-ion battery. Fig. 3 shows a set of circuit diagrams showing the states of each Fig. 1 illustrate the switches for the respective conditions of a vehicle. Fig. 4 shows a set of circuit diagrams showing the states of each Fig. 1 illustrated switch for the respective conditions of the vehicle. Fig. Figure 5 shows a set of circuit diagrams illustrating four discharge modes of each battery used in Fig. 1 is illustrated. Fig. Figure 6 shows a timing diagram illustrating how a voltage is changed while the Fig. 1 illustrates the discharge of the lithium-ion battery. Fig. Figure 7 shows a flowchart illustrating a switch selection routine performed by a Fig. 1 illustrated control unit is executed. Fig. 8 shows a set of circuit diagrams illustrating a first example of the other circuit configurations of the battery system according to the present disclosure. Fig. 9 shows a set of circuit diagrams illustrating a second example of the other circuit configurations of the battery system according to the present disclosure. Fig. 10 shows a set of circuit diagrams illustrating a third example of the other circuit configurations of the battery system according to the present disclosure. Fig. 11 shows a set of circuit diagrams illustrating a fourth example of the other circuit configurations of the battery system according to the present disclosure. Fig. 12 shows a set of circuit diagrams illustrating a fifth example of the other circuit configurations of the battery system according to the present disclosure. Fig. 13 shows a set of circuit diagrams illustrating a sixth example of the other circuit configurations of the battery system according to the present disclosure. Fig. 14 shows a set of circuit diagrams illustrating a seventh example of the other circuit configurations of the battery system according to the present disclosure. Description of an embodiment

[0043] An embodiment of the present invention will be described below with reference to the accompanying drawings. A vehicle in which an on-vehicle power supply device is installed runs based on an internal combustion engine, referred to as an engine, as its drive source and has a so-called idle reduction function.

[0044] According to Fig. 1, a power supply system is configured as a dual power supply system including a lead-acid battery 11 serving as a first storage battery and a lithium-ion battery 12 serving as a second storage battery. Each of the first batteries 11 and 12 is capable of supplying power to a starter motor 13 and various electrical loads 14 and 15. A rotating electric machine 16 is capable of charging the batteries 11 and 12. This power supply system is configured such that the lead-acid battery 11 and the lithium-ion battery 12 are connected in parallel to the rotating electric machine 16 and also to each of the electrical loads 14 and 15.

[0045] The lead-acid battery 11 is a well-known, available battery. In contrast, the lithium-ion battery 12 is a battery that has lower power loss during battery charging and discharging, higher power density, and higher energy density compared to the lead-acid battery 11. A battery that has higher energy efficiency during battery charging and discharging compared to the lead-acid battery 11 is preferably used as the lithium-ion battery 12.

[0046] The electrical loads 14 have voltage requirements for power supplied from each battery 11 and 12, and the electrical loads 15 have different voltage requirements for power supplied from each battery 11 and 12. The electrical loads 15 include constant-voltage loads, each of which has a requirement that the voltage of the supplied power be stable, i.e., maintained at a constant level or at least stably varied within a predetermined range. In contrast, the electrical loads 14 are ordinary electrical loads except for the constant-voltage loads. The electrical loads 15 are also referred to as protected loads.

[0047] In addition, the electrical loads 15 are loads for which the error of power supply thereto is not allowed, and the electrical loads 14 are loads for which the error of power supply thereto is allowed compared to the electrical loads 15.

[0048] The constant-voltage loads of the electrical loads 15 include, as specific examples, a navigation device, an audio device, meters, and various ECUs including an engine ECU. Reducing the fluctuations in the voltage of the supplied power prevents, for example, unnecessary resets of these electrical loads, enabling stable operation of these electrical loads. The electrical loads 14 include, as specific examples, heaters such as seat heaters and defrost heaters for a rear window, headlights, windshield wipers, air conditioning fans, and other similar devices.

[0049] The rotating electric machine 16 has a rotating shaft that is drivably coupled to an engine output shaft (not shown) via a belt or similar element. Rotation of the engine output shaft causes the rotating shaft of the rotating electric machine 16 to rotate, and rotation of the rotating shaft of the rotating electric machine 16 causes the engine output shaft to rotate. That is, the rotating electric machine 16 has: 1. a power supply function, i.e. a regenerative function of generating power based on rotation of the engine output shaft or rotation of the vehicle's axles, 2. a drive power output function of applying torque to the engine output shaft.

[0050] An inverter serving as a power converter provided integrally or separately for the rotating electric machine 16 is configured to adjust a current generated by the power generation function and to adjust the torque of the rotating electric machine 16 generated by the drive power output function.

[0051] The rotating electric machine 16 serves as an electrical load because the rotating electric machine 16 supplies drive power to the engine output shaft, and also serves as a high-power, high-current load compared to the electrical loads 15. Note that the electrical loads 15 serve as a first electrical load, and the rotating electric machine 16 serves as a second electrical load. Hereinafter, the electrical loads 15 and the rotating electric machine 16 are collectively referred to as electrical loads 15 and 16 for convenience.

[0052] The circuit structure of the power supply system is described in detail below.

[0053] The power supply system includes a feed path L1 through which a feed current input to or output from the rotating electric machine 16 and a feed current for the electrical loads 15 flow. The feed path L1 also serves as a path connecting the lead-acid battery 11 and the lithium-ion battery 12. A first switch 21, a second switch 22, and a third switch 23 are provided on the feed path L1 to be connected in series with each other. Each of the switches 21 to 23 serves as an opening and closing unit composed of a semiconductor switch such as a MOSFET. Note that each of the switches 21 to 23 is preferably composed of a pair of MOSFETs connected in series such that their intrinsic diodes face opposite directions.The fact that the intrinsic diodes of each switch are connected in their opposite directions allows for interrupting a current flow through a segment of the path on which the corresponding switch is provided when the corresponding switch is turned off. It should be noted that each of the switches 21 to 23 can be freely configured based on one or more semiconductor switches. For example, each of the switches 21 to 23 can be configured such that the intrinsic diodes of the MOSFETs do not have their opposite directions. Each of the switches 21 to 23 can consist of semiconductor switches connected in series or in parallel.

[0054] The supply path L1 has a first point N1 located at a first end of the first switch 21; a second end of the first switch 21 is connected to the second switch 22. The supply path L1 has a second point N2 located between the first and second switches 21 and 22. The supply path L1 has a third point N3 located between the second and third switches 22 and 23. The supply path L1 has a fourth point N4 located at a first end of the third switch 23; a second end of the third switch 23 is connected to the second switch 22. A starter motor 13 and the electrical loads 14 are connected to the first point N1. The rotating electrical machine 16 is connected to the second point N2 via a path L2. The electrical loads 15 are connected to the third point N3 via a path L3.The lithium-ion battery 12 is connected to the fourth point N4.

[0055] The power supply system includes a control unit 30 serving as a battery control device. The battery unit 30 is mainly composed of a computer including, for example, a CPU, a memory, and input-output interfaces connected to each other. The control unit 30 performs on-off (open-close) switching operations of each of the switches 21 to 23. Specifically, the control unit 30 monitors the operating conditions of the vehicle and the charging status (state of charge) of each of the batteries 11 and 12. Then, based on the monitored operating conditions of the vehicle and the monitored charging status of each of the batteries 11 and 12, the control unit 30 controls on-off switching operations of each of the switches 21 to 23. This enables charging or discharging of a selected one of the lead-acid battery 11 and the lithium-ion battery 12.

[0056] A charging and discharging control based on the charging status of each of the batteries 11 and 12, which is executed by the control unit 30, will be briefly described below.

[0057] The control unit 30 sequentially acquires a measured value of a terminal voltage of the lead-acid battery 11 and a measured value of a terminal voltage of the lithium-ion battery 12, which are measured by respective voltage sensors VS. The control unit 30 sequentially acquires an input / output current, i.e., a charge / discharge current, to / from the lead-acid battery 11 and an input / output current, i.e., a charge / discharge current, to / from the lithium-ion battery 12.

[0058] Based on the acquired measured values, the control unit 30 calculates an open-circuit voltage (OCV) across each of the lead-acid battery 11 and the lithium-ion battery 12 and calculates the remaining capacity, i.e., the state of charge (SOC), of each of the lead-acid battery 11 and the lithium-ion battery 12. Then, the control unit 30 controls the charging rate for each of the lead-acid battery 11 and the lithium-ion battery 12, and then the discharging rate from each of the lead-acid battery 11 and the lithium-ion battery 12, thereby maintaining the open-circuit voltage and SOC of the corresponding ones of the batteries 11 and 12 within a corresponding one of predetermined usable ranges. The open-circuit voltage and / or the SOC serves as the charging status of each of the batteries 11 and 12.Information regarding the temperature of each of the batteries 11 and 12 is input to the control unit 30 from a corresponding one of temperature sensors TS; the temperature sensors TS are provided for the respective batteries 11 and 12.

[0059] The lithium-ion battery 12 of the batteries 11 and 12 is housed in a non-illustrated case, ie, a storage container, to be constructed as a battery unit U. The battery unit U is preferably configured such that the switches 21 to 23 and the control unit 30 are installed in the case, with the switches 21 to 23 and the control unit 30 being mounted on a common substrate. The switches 21 to 23 and the control unit 30 may be mounted on different portions of the battery unit U, such as different substrates.

[0060] In addition, the battery unit U has a first terminal P1 serving as an external connection enabling terminal to which the lead-acid battery 11, the starter motor 13, and the electrical loads 14 are connected. The battery unit U also has a second terminal P2 serving as an external connection enabling terminal to which the rotating electrical machine 16 is connected, and a third terminal P3 serving as an external connection enabling terminal to which the electrical loads 15 are connected. The battery unit U further has fourth and fifth terminals P4 and P5 to which bypass routes L4 and L5, described later, are connected.

[0061] An electronic control unit (ECU) is connected to the control unit 30. This control unit 30 and the ECU 40 are commonly connected to each other via a communication network such as a Controller Area Network (CAN). The control unit 30 and the ECU 40 are configured to share various data stored in each of the control unit 30 and the ECU 40. The ECU 40 is an electronic control unit for performing idle reduction control. The idle reduction control is for automatically stopping the engine when predetermined known automatic stop conditions are met, and for restarting the engine that has been automatically stopped when predetermined restart conditions are met.

[0062] A manual initial start operation or an automatic engine restart operation enables starting the vehicle's engine. Specifically, the present embodiment is configured such that the starter motor 13 starts the engine the first time, and the rotary electric machine 16 starts the engine during the automatic restart operation.

[0063] The frequency of occurrence of the rotating electric machine 16 is greater than that of the starter motor 13.

[0064] The usable range of the SOC of each of the batteries 11 and 12 is described below. Fig. 2A and Fig. 2B each illustrates a correlation relationship between the open circuit voltage (OCV) and the state of charge (SOC) of the corresponding ones of the lead-acid battery 11 and the lithium-ion battery 12.

[0065] Fig. 2A illustrates the correlation relationship between the open circuit voltage and the SOC of the lead-acid battery (Pb) 11, and also illustrates the usable SOC range of the lead-acid battery 11 as W1.

[0066] Fig. 2B illustrates the correlation relationship between the open circuit voltage and the SOC of the lithium-ion (Li) battery 12, and also illustrates a usable SOC range of the lithium-ion battery 12 as W2. Fig. Figure 2B shows an enlarged view of a region corresponding to a region according to Fig. 2A, which is enclosed by a dot-dashed line in the usable SOC range W1 (Pb). 0 (%) of the SOC of the lithium-ion battery 12 on the horizontal axis in Fig. 2B corresponds to a value SOCa of the usable SOC range W1 (Pb). The voltages Va and Vb in Fig. 2A are identical to the voltages Va and Vb in Fig. 2B.

[0067] The horizontal axis in Fig. 2A shows the SOC of the lead-acid battery 11, and the solid line A1 in Fig. 2A represents a voltage characteristic curve indicating the relationship between the SOC of the lead-acid battery 11 and the open-circuit voltage V0 (Pb); the voltage characteristic curve shows that the open-circuit voltage V0 (Pb) increases in proportion to an increase in the SOC due to an increase in the charging rate.

[0068] The horizontal axis in Fig. 2B shows the SOC of the lithium-ion battery 12, and the solid line A2 in Fig. 2B represents a voltage characteristic curve indicating the relationship between the SOC of the lithium-ion battery 12 and the open-circuit voltage V0 (Li); the voltage characteristic curve shows that the open-circuit voltage V0 (Li) increases when the SOC increases due to an increase in the charging rate.

[0069] Fig. 2B shows that the correlation between the open-circuit voltage and the SOC in the lead-acid battery 11 is different from the correlation between the open-circuit voltage and the SOC in the lithium-ion battery 12. The open-circuit voltage of the lithium-ion battery 12 is set to be higher than the open-circuit voltage of the lead-acid battery 11 within the usable SOC range W2 (Li). The lithium-ion battery 12 serves as a priority battery, and the lead-acid battery 11 serves as a non-priority battery.

[0070] If batteries 11 and 12 are each in an overcharged or undercharged state, this may cause the corresponding battery to deteriorate prematurely. The charging rate and discharging rate of each of batteries 11 and 12 are limited to thereby maintain the SOC of the corresponding one of batteries 11 and 12 within the corresponding usable range defined between predetermined lower and upper SOC limits. That is, maintaining the SOC of each of batteries 11 and 12 within the corresponding usable range prevents the SOC of the corresponding one of batteries 11 and 12 from being overcharged or overdischarged.

[0071] That is, the control unit 30 is configured to perform a protection control that (1) limits the charging rate to each of the batteries 11 and 12 to maintain the SOC of the lead-acid battery 11 within the usable SOC range W1 and to maintain the SOC of the lithium-ion battery 12 within the usable SOC range W2, (2) limits the discharge rate from each of the batteries 11 and 12, thereby maintaining the SOC of the lead-acid battery 11 within the usable SOC range W1 and maintaining the SOC of the lithium-ion battery 12 within the usable SOC range W2.

[0072] This protection control results in protection of each of the batteries 11 and 12 against excessive charging and excessive discharging.

[0073] In addition, the present system includes bypass routes L4 and L5, which enable the lead-acid battery 11 to be connected to the rotating electrical machine 16 and the electrical loads 15 without the intervention of the respective first switch 21 and second switch 22. A first bypass switch 24 is provided on the bypass route L4, and a second bypass switch 25 is provided on the bypass route L5. Each of the bypass switches 24 and 25 is composed, for example, of a normally open relay switch. Turning on (i.e., closing) the first bypass switch 24 enables the lead-acid battery 11 and the rotating electrical machine 16 to be electrically connected to each other. Turning on (i.e., closing) the second bypass switch 25 enables the lead-acid battery 11 and the electrical loads 15 to be electrically connected to each other even when the switches 21 and 22 are off.

[0074] The operating conditions of the vehicle and the state of each of the switches 21 to 23 are described below with reference to Fig. 3 and Fig. 4 described. Fig. 3 and Fig. 4 illustrate that the system installed in the vehicle is supplied with power, ie, an ignition switch (IG) is in the on state, and the bypass switches 24 and 25 are off. It should be noted that in the subsequent figures, including Fig. 3 and Fig. 4 a representation of the bypass paths L4 and L5 in the battery unit U, the control unit 30 and the terminals P1 to P5 is omitted for the sake of simplicity if this is required.

[0075] Reference symbol (a) of Fig. 3 shows a deceleration and regeneration state of the vehicle executed by the rotary electric machine 16, reference numeral (b) of Fig. 3 shows an automatically stopped state of the engine, and reference character (c) of Fig. 3 shows a restart state of the engine which has been automatically stopped.

[0076] Reference symbol (a) of Fig. 4 shows a power assist state of the vehicle executed by the rotary electric machine 16, and reference numeral (b) of Fig. 4 shows an unusable state of the lithium-ion battery 12.

[0077] In the case of (a) of Fig. In the deceleration and regeneration state illustrated in Figure 3, the control unit 30 controls the first switch 21 to be on, the second switch 22 to be on, and the third switch 23 to be on. This causes electric power generated by the regenerative function of the rotating electric machine 16 to be supplied to each of the batteries 11 and 12, so that the batteries 11 and 12 are charged. The electric power generated by the rotating electric machine 16 is also supplied to each of the electrical loads 14 and 15.

[0078] In the case of (b) of Fig. In the automatically stopped state of the engine illustrated in FIG. 3, the first switch 21 is controlled to be on, the second switch 22 is controlled to be off, and the third switch 23 is controlled to be on. This allows the lead-acid battery 11 to supply electric power to the electrical loads 14. In addition, the lithium-ion battery 12 supplies electric power to the electrical loads 15.

[0079] In the case of (c) of Fig. 3, the first switch 21 is controlled to be on, the second switch 23 is controlled to be off, and the third switch 23 is controlled to be on. That is, the switches 21 to 23 are controlled in the same manner as the switches 21 to 23 in the state shown by (b) of Fig. 3. This allows the lead-acid battery 11 to supply electric power to both the electric loads 14 and the rotating electric machine 16, allowing the rotating electric machine 16 to restart the engine. In addition, the lithium-ion battery 12 supplies electric power to the electric loads 15. At this time, the power supply path to the rotating electric machine 16 and the power supply path to the electric loads 15 are separated by the second switch 22 being in the off state. This therefore prevents fluctuations in the voltage of the electric power supplied to the electric loads 15, which are constant-voltage loads.

[0080] In the case of (a) of Fig. In the power assist state of the vehicle illustrated in FIG. 4, the first switch 21 is controlled to be off, the second switch 22 is controlled to be on, and the third switch 23 is controlled to be on. This allows the lead-acid battery 11 to supply electric power to the electric loads 14. In addition, the lithium-ion battery 12 supplies electric power to both the electric loads 15 and the rotating electric machine 16. Note that the states of the respective switches 21 to 23 are appropriately controlled based on the charge status of the lead-acid battery 11 in the power assist state performed by the rotating electric machine 16, the details of which will be described later.

[0081] In the case of (b) of Fig. 4, the first switch 21 is controlled to be on, the second switch 22 is controlled to be on, and the third switch 23 is controlled to be off. Charging and discharging of the lithium-ion battery 12 is prevented, for example, in the case (1) an incomplete calculation of the SOC of the lithium-ion battery 12 after the systems installed in the vehicle have been started, (2) a low SOC of the lithium-ion battery 12, (3) low temperatures of the lithium-ion battery 12, or (4) a fail-safe mode of operation of the lithium-ion battery 12.

[0082] In this unusable state of the lithium-ion battery 12, electrical power is supplied from the lead-acid battery 11 to both the electrical loads 14 and 15 and the rotating electrical machine 16.

[0083] The control unit 30 according to the present embodiment controls on-off operations of the switches 21 to 23 based on the charge status of each of the lead-acid battery 11 and the lithium-ion battery 12 in the state of power supply to the rotating electric machine 16, such as the power assist state of the vehicle, the discharge state for high-voltage driving, or the power supply state to the other electric loads 14 and 15. The details of the on-off operations will be described below.

[0084] Fig. 5 illustrates first to fourth discharge modes when the electric loads 14 and 15 and the rotating electric machine 16 are respectively set as power supply targets.

[0085] The control unit 30 according to the present embodiment is configured to selectably determine which of the batteries 11 and 12 is discharging based on a comparison between the charge status of the lead-acid battery 11 and the charge status of the lithium-ion battery 12. In addition, the control unit 30 according to the present embodiment is configured to selectably determine, based on a comparison between the charge status of the lead-acid battery 11 and the charge status of the lithium-ion battery 12, to which of the discharge targets electric power is discharged from the lithium-ion battery 12 when it is determined that discharging is being performed from the lithium-ion battery 12.

[0086] It should be noted that the control unit 30 according to the present embodiment is configured to control opening or closing of each of the switches 21 to 23 based on, for example, the open circuit voltage or the SOC of each of the batteries 11 and 12 as a charge status parameter.

[0087] The control unit 30 controls the first to third switches 21 to 23 in the order indicated by reference numeral (a) of Fig. 5, ie, turns on the first switch 21, turns on the second switch 22, and turns on the third switch 23. This first mode of operation is selected when the available power supply capacity of the lithium-ion battery 12 is sufficient, so that electric power from the lithium-ion battery 12 is supplied to the electric loads 14 and 15 and the rotating electric machine 16 while discharging from the lead-acid battery 11 is stopped.

[0088] Specifically, the control unit 30 compares the open-circuit voltage of the battery 11 with the open-circuit voltage of the battery 12, thereby comparing the charge status of the priority battery (Li) with the charge status of the non-priority battery (Pb). The control unit 30 executes the discharge mode, which causes the priority battery to supply electric power to all of the electric loads 14 to 16, when it is determined that the charge status of the priority battery (Li) is higher than the charge status of the non-priority battery (Pb).

[0089] When the open circuit voltage of the lithium ion battery 12 decreases to become smaller than the open circuit voltage of the lead acid battery 11 with an increase in power consumption, the control unit 30 switches the first operation mode to the second operation mode indicated by reference symbol (b) of Fig. 5 when it is determined that the open circuit voltage of the lithium-ion battery 12 is higher than a predetermined voltage threshold TH1 and that the temperature of the lithium-ion battery 12 is lower than a predetermined temperature threshold TH2. Specifically, in the second operation mode, the control unit 30 turns off the first switch 21, turns on the second switch 22, and turns on the third switch 23. Note that the voltage threshold TH1 is preferably determined based on a lower discharge limit voltage of the lithium-ion battery 12. For example, the voltage threshold TH1 is preferably determined to be close to and higher than the lower discharge limit voltage. The temperature threshold TH2 is preferably determined to be lower than an allowable upper limit temperature of the lithium-ion battery 12.

[0090] The second mode of operation starts discharging from the lead-acid battery 11 in addition to discharging from the lithium-ion battery 12. Even after the open-circuit voltage of the lithium-ion battery 12 is lower than the open-circuit voltage of the lead-acid battery 11, the control unit 30 continuously causes the lithium-ion battery 12 to discharge electric power to the limited electric loads, that is, preferentially causes the lithium-ion battery 12 to discharge electric power to the electric loads 15 and 16. This dampens the temperature rise of the lead-acid battery 11 and also reduces a load on the lead-acid battery 11 based on the use of the lead-acid battery 11.

[0091] Specifically, the control unit 30 performs the discharge mode that causes the priority battery (Li) to supply electric power to the electric loads 15 and 16 when it is determined based on a comparison between the priority battery (Li) and the non-priority battery (Pb) that (1) the charge status of the non-priority battery (Pb) is higher than the charge status of the priority battery (Li), (2) the open-circuit voltage representing the charged capacity of the priority battery (Li) is higher than the voltage threshold TH1, which indicates a threshold for the charged capacity of the priority battery (Li), (3) the temperature of the priority battery (Li) is lower than the temperature threshold TH2.

[0092] When the temperature of the lithium-ion battery 12 increases with use of the lithium-ion battery 12 to reach the temperature threshold TH2, the control unit 30 switches the second operation mode to the third operation mode indicated by reference character (c) of Fig. 5. Specifically, in the third mode, the control unit 30 turns on the first switch 21, turns off the second switch 22, and turns on the third switch 23.

[0093] The third mode limits the discharge target from the lithium-ion battery 12 to only the electrical loads 15, while causing the lead-acid battery 11 to supply electrical power to the electrical loads 14 and the rotating electrical machine 16. This further dampens a temperature rise of the lithium-ion battery 12 due to continuous discharge from the lithium-ion battery 12.

[0094] Specifically, the control unit 30 performs the discharge mode that causes the priority battery (Li) to supply electric power to the electric load 16 or the electric loads 15 and causes the non-priority battery (Pb) to supply electric power to the other of the electric load 16 and the electric loads 15 when it is determined based on a comparison between the priority battery (Li) and the non-priority battery (Pb) that (1) the charge status of the non-priority battery (Pb) is higher than the charge status of the priority battery (Li), (2) the open circuit voltage representing the charged capacity of the priority battery (Li) is higher than the voltage threshold TH1 representing a threshold for the charged capacity of the capacity battery (Li), (3) the temperature of the priority battery (Li) is higher than the temperature threshold TH2.

[0095] In addition, the control unit 30 performs the discharge mode that causes the non-priority battery (Pb) to supply electric power to the electric loads 15 and the electric load 16 when it is determined based on a comparison between the priority battery (Li) and the non-priority battery (Pb) that (1) the charge status of the non-priority battery (Pb) is higher than the charge status of the priority battery (Li), (2) the open circuit voltage representing the charged capacity of the priority battery (Li) is lower than the voltage threshold TH1 indicating a threshold for the charged capacity of the priority battery (Li).

[0096] As described above, the control unit 30 controls switching among the first operating mode, the second operating mode, the third operating mode, and the fourth operating mode. This control enables appropriate application of electric power to the electric loads while preferentially using the lithium-ion battery 12 among the lead-acid battery 11 and the lithium-ion battery 12. The control unit 30 enables appropriate switching between the batteries 11 and 12 to supply stable electric power to the electric loads while maintaining the drive voltage required for each of the electric loads.

[0097] In addition, the control unit 30 is configured to limit a discharge performed by each of the batteries 11 and 12 to corresponding predetermined situations, thereby making it possible to reduce a load on the batteries 11 and 12 based on the use of the batteries 11 and 12.

[0098] Switching between the first to fourth operating modes allows the number of discharge targets to which electrical power is discharged from the lithium-ion battery 12 to be gradually reduced while the SOC of the lithium-ion battery 12 gradually decreases. By gradually reducing the number of discharge targets, the discharge current from the lithium-ion battery 12 is gradually reduced. This gradual reduction in the discharge current causes the voltage, i.e., the open-circuit voltage, across the lithium-ion battery 12 to increase each time one of the operating modes is changed to another, thereby allowing the usable period of the lithium-ion battery 12 to be extended.

[0099] In particular, Fig. 6 shows that the voltage, i.e., the open-circuit voltage of the lithium-ion battery 12, decreases over time during the discharge state of the lithium-ion battery 12, but shows that the voltage gradually increases at each of times t1 and t2; each of time t1 and time t2 represents that the operation mode has been switched. In this regard, disconnecting the electrical loads for the lithium-ion battery 12 from the lithium-ion battery 12 allows the voltage of the lithium-ion battery 12 to increase compared with the voltage of the lithium-ion battery 12 before the load disconnection. This therefore enables full utilization of the lithium-ion battery 12 down to the usable lower limit voltage.

[0100] Next, processing of a switch selection control, that is, a switch selection control routine executed by the control unit 30, will be described with reference to the flowchart of Fig. 7. The control unit 30 executes this routine at a predetermined period. Specifically, the switch selection control when the rotating electrical machine 16 is activated will be described below.

[0101] The control unit 30 determines in step S11 of Fig. 7, whether there is a drive request for the rotating electric machine 16. If it is determined that there is a drive request for the rotating electric machine 16, the switch selection control routine proceeds to step S12. In step S12, the control unit 30 determines whether the open circuit voltage of the lithium-ion battery 12, which is indicated as Li_OCV in Fig. 7, is higher than the open circuit voltage of the lead-acid battery 11, which is referred to as Pb_OCV in Fig. 7 is illustrated.

[0102] If the determination result in step S12 is YES, the switch selection routine proceeds to step S13. In step S13, the control unit 30 controls the switches 21 to 23 in the first mode. Specifically, the control unit 30 turns on or keeps the first switch 21 on, turns on or keeps the second switch 22 on, and turns on or keeps the third switch 23 on.

[0103] Otherwise, if the determination result in step S12 is NO, the switch selection routine proceeds to step S14. Then, the control unit 30 performs a selection of one of the operation modes according to the determination result in step S14 and the determination result in S15.

[0104] Specifically, in step S14, the control routine 30 determines whether the open circuit voltage of the lithium-ion battery 12 is equal to or less than the voltage threshold TH1, and in step S15, the control unit 30 determines whether the battery temperature of the lithium-ion battery 12, which is Fig. 7 is illustrated as Temp, is equal to or greater than the temperature threshold TH2.

[0105] If the determination in each of steps S14 and S15 is NO, the switch selection routine proceeds to step S16. In step S16, the control unit 30 controls the switches 21 to 23 in the second mode. Specifically, the control unit 30 turns off the first switch 21, keeps the second switch 22 on, and keeps the third switch 23 on.

[0106] If the determination in step S14 is NO and the determination in step S15 is YES, the switch selection routine proceeds to step S16. In step S17, the control unit 30 controls the switches 21 to 23 in the third mode. Specifically, the control unit 30 keeps the first switch 21 on, turns off the second switch 22, and keeps the third switch 23 on.

[0107] If the determination in step S14 is YES, the switch selection routine proceeds to step S18. In step S18, the control unit 30 controls the switches 21 to 23 in the fourth mode. Specifically, the control unit 30 keeps the first switch 21 on, keeps the second switch 22 on, and turns the third switch 23 off.

[0108] As described above in detail, the power supply system according to the present embodiment achieves the following excellent effects.

[0109] In particular, the power supply system according to the present embodiment is configured such that (1) the first, second and third switches 21 to 23, which are connected in series, are provided on the supply path L1 through which the supply current for the electrical loads 15 and 16 flows, (2) the lead-acid battery 11, the lithium-ion battery 12, the set of electrical loads 15 and the electrical load 16 are each connected to a corresponding one of the end points of the first, second and third switches 21, 22 and 23.

[0110] This configuration allows for easy changing of a connection configuration selected among the batteries 11 and 12 and the electrical loads 15 and 16. That is, this configuration allows for easy selection of one of the batteries 11 and 12 as a power source for supplying electrical power to each of the electrical loads 16 and 15. This makes it possible to preferentially use any of the batteries and / or reduce the load on each of the batteries 11 and 12 based on the usage of the corresponding one of the batteries 11 and 12. This results in appropriate selective power supply from the battery 11 and / or the battery 12 to each of the electrical loads 16 and 15.

[0111] The power supply system according to the present embodiment is configured to switch between (1) the first discharge mode in which the lead-acid battery 11 supplies electric power to both of the electric loads 15 and 16, (2) the second discharge mode in which the lead-acid battery 11 supplies electric power to the electrical loads 15 and the lithium-ion battery 12 supplies electric power to the rotating electric machine 16, (3) the third discharge mode in which the lithium-ion battery 12 supplies electrical power to both of the electrical loads 15 and 16.

[0112] This configuration prevents excessive deterioration of the charged capacity and / or temperature conditions of either battery. This allows for use of batteries 11 and 12 while reducing the load on each of batteries 11 and 12 based on the use of the corresponding batteries 11 and 12. This reduction in the load on each of batteries 11 and 12 results in an extension of the service life of the corresponding batteries 11 and 12.

[0113] In particular, the control unit 30 is configured to switch between (1) the first operating mode in which the lithium-ion battery 12 discharges electrical power to the electrical loads 14 to 16, (2) the second mode of operation in which the lithium-ion battery 12 discharges electrical power to the electrical loads 15 and 16 and the lead-acid battery 11 discharges electrical power to the electrical loads 14, (3) the third mode of operation in which the lithium-ion battery 12 discharges electrical power to the electrical loads 15 or the electrical load 16, and the lead-acid battery 11 discharges electrical power to the electrical loads 14 and 16, (4) the fourth mode of operation, in which the lead-acid battery 11 discharges electrical power to the electrical loads 14 to 16.

[0114] Assuming that the lithium-ion battery 12 is defined as a priority battery and the lead-acid battery 11 is defined as a non-priority battery, the power supply system preferentially uses the lithium-ion battery 12, and uses the lead-acid battery 11 when it is determined that the use of the lead-acid battery 11 is required depending on a change in the charged capacity and the temperature of the lithium-ion battery 12.

[0115] The power supply system therefore selectively uses the batteries 11 and 12 depending on whether one of the batteries 11 and 12 is preferentially used, and reduces a load on each of the batteries 11 and 12 based on the usage of the corresponding one of the batteries 11 and 12. That is, this configuration allows the lithium-ion battery 12, which has higher energy efficiency, to be used in priority over the lead-acid battery 11. Reducing the load on the lead-acid battery 11 prevents deterioration of the lead-acid battery 11.

[0116] In the Fig. 1, the lead-acid battery 11 is connected to the first point N1, which forms a first outer point of the first to fourth points N1 to N4, and the lithium-ion battery 12 is connected to the fourth point N4, which forms a second outer point of the first to fourth points N1 to N4. In the circuit configuration shown in Fig. In the circuit configuration illustrated in FIG. 1, the electric loads 15 are connected to the second point N2, which forms an intermediate point (middle point), and the rotating electric machine 16 is connected to the third point N3, which forms an intermediate point. This circuit configuration enables the control unit 30 to perform on-off operations of the switches 21 to 23 to switch between the desired three discharge modes, that is, the first to third discharge modes. This enables electric power supply to the electric loads 15 and 16 to be performed at desired timings, while resulting in the battery system having a simplified configuration.

[0117] In the Fig. In the circuit configuration illustrated in FIG. 1, the lithium-ion battery 12 is connected to the fourth point N4, which is an outer point of the first to fourth points N1 to N4, and the lead-acid battery 11, the set of electric loads 15, and the rotating electric machine 16 are individually connected to the other points N1, N3, and N2, respectively. This configuration enables switching between the first to third discharge modes to be appropriately performed using the lithium-ion battery 12, which has a higher voltage region than the lead-acid battery 11 in the battery characteristics indicating the relationship between the SOC and the open-circuit voltage of the battery 11 and those of the battery 12.

[0118] In addition, in the Fig. 1, the lead-acid battery 11 is connected to the first point N1, the rotating electric machine 16 is connected to the second point N2, the lithium-ion battery 12 is connected to the fourth point N4, and the electrical loads 15 are connected to the third point N3. This configuration allows the electrical loads 15 serving as the constant-voltage loads and the rotating electric machine 16 to be operated, while preventing voltage variations in the batteries 11 and 12 due to the drive of the rotating electric machine 16 from affecting the drive of the electrical loads 15.

[0119] The control unit 30 may include a determination device 30a in the configuration in which the lead-acid battery 11 is connected to the first point N1, which is an outer point of the first to fourth points; the determination device 30a determines whether there is a malfunction in the lead-acid battery 11, that is, a power supply failure in the lead-acid battery 11. The control unit 30 may be configured to disconnect the lead-acid battery 11 from the corresponding supply path and control the switches 21 to 23 to cause the lithium-ion battery 12 to supply electric power to the electrical loads 15 and 16 when the determination device 30a determines that there is a power supply failure in the lead-acid battery 11.

[0120] The determination means 30a in the control unit 30 monitors, for example, the terminal voltage of the lead-acid battery 11 measured by the corresponding voltage sensor VS, and determines that there is a power supply failure in the lead-acid battery 11 when it is determined that the monitored terminal voltage is lower than a predetermined value.

[0121] Even if there is a malfunction in the lead-acid battery 11, this configuration uses the remaining lithium-ion battery 12 within its usable range to thereby continuously supply electric power to the electric loads 15 and 16. This results in taking measures against a power supply failure of the lead-acid battery 11.

[0122] It should be noted that it is possible to determine whether there is a malfunction in the lithium-ion battery 12 connected to the fourth point N4 instead of or in addition to the lead-acid battery 11.

[0123] The following are circuit configuration examples that can be implemented as the power supply system with reference to Fig. 8, Fig. 9 and Fig. 10 described.

[0124] In each of the Fig. 8 to 10, the first, second, and third switches 21 to 23, which are connected in series, are provided on the supply path L1, and the first point N1, the second point N2, the third point N3, and the fourth point N4 are provided at the respective end points of the switches 21, 22, and 23. This circuit configuration is similar to that shown in Fig. 1. In addition, the lithium-ion battery 12 has a higher voltage region than the lead-acid battery 11 in the battery characteristics indicating the relationship between the SOC and open-circuit voltage of the battery 11 and those of the battery 12.

[0125] In each of the circuit configuration examples, the arrangement order of the battery 11, the battery 12, the set of electric loads 15 and the rotating electric machine 16 from left to right connected to the corresponding points N1 to N4 may be reversed so that their arrangement order is from right to left.

[0126] Circuit configuration examples are described below, each of which is indicated by reference numerals (a) and (b) of Fig. 8. In the figures indicated by the reference numerals (a) and (b) of Fig. 8, the lithium-ion battery 12 is connected to the fourth point N4, which is an external point, and the electrical loads 15 are connected to the third point N3, which is located adjacent to the fourth point N4. The circuit configuration indicated by reference symbol (a) of Fig. 8 is essentially identical to that shown in Fig. 1. The lead-acid battery 11 and the rotating electric machine 16 are interchangeably connected to the remaining first and second points N1 and N2. In particular, reference symbol (a) of Fig. 8, the lead-acid battery 11 and the rotating electric machine 16 are connected to the first and second points N1 and N2, respectively. In contrast, the reference symbol (b) of Fig. 8, that the rotating electric machine 16 and the lead-acid battery 11 are connected to the first and second points N1 and N2, respectively.

[0127] In the circuit configuration examples illustrated by reference numerals (a) and (b), respectively, the control unit 30 controls on-off operations of the switches 21 to 23 according to parameters including the charge status and / or the temperature of each of the batteries 11 and 12.

[0128] This allows switching between: I. the discharge mode (1), in which the lead-acid battery 11 supplies electrical power to the electrical loads 15 and the rotating electrical machine 16, II. the discharge mode (2), in which the lead-acid battery 11 supplies electrical power to either the rotating electrical machine 16 or the electrical loads 15, such as the rotating electrical machine 16, and the lithium-ion battery 12 supplies electrical power to the other of the rotating electrical machine 16 and the electrical loads 15, such as the electrical loads 15, III. the discharge mode (3), in which the lithium-ion battery 12 supplies electrical power to the electrical loads 15 and the rotating electrical machine 16.

[0129] For example, when the lithium-ion battery 12 is defined as the priority battery, the control unit 30 sequentially selects one of the discharge modes (1), (2), and (3) in the order of the discharge mode (3), the discharge mode (2), and the discharge mode (1) when the charged capacity of the lithium-ion battery 12 gradually decreases from a large value. In contrast, the control unit 30 sequentially selects one of the discharge modes (1), (2), and (3) in the order of the discharge mode (3), the discharge mode (2), and the discharge mode (1) when the temperature of the lithium-ion battery 12 increases.

[0130] This example enables appropriate use of the batteries 11 and 12 while reducing a load on each of the batteries 11 and 12 based on the use of the corresponding ones of the batteries 11 and 12.

[0131] In the figures indicated by the reference symbols (a) and (b) of Fig. In the circuit configuration examples illustrated in FIG. 8, the lithium-ion battery 12 is connected to the fourth point N4, which is an external point, and the lead-acid battery 11, the set of electric loads 15, and the rotating electric machine 16 are individually connected to the corresponding other points. This configuration enables switching between the discharge modes (1) to (3) to be properly performed with the aid of the lithium-ion battery 12, which has a higher voltage region than the lead-acid battery 11 in the battery characteristics indicating the relationship between the SOC and the open-circuit voltage of the battery 11 and those of the battery 12.

[0132] Circuit configuration examples are described below, each of which is denoted by reference numerals (c) and (d) of Fig. 8. In the figures indicated by each of the reference numerals (c) and (d) of Fig. In the circuit configuration example illustrated in FIG. 8, the electrical loads 15 are connected to the fourth point N4, which is an external point, and the lithium-ion battery 12 is connected to the third point N3, which is adjacent to the fourth point N4. The lead-acid battery 11 and the rotating electric machine 16 are interchangeably connected to the remaining first and second points N1 and N2.

[0133] In particular, reference symbol (c) of Fig. 8 illustrates a situation in which the lead-acid battery 11 and the rotating electric machine 16 are connected to the first and second points N1 and N2, respectively. In contrast, reference symbol (b) of Fig. 8, that the rotating electric machine 16 and the lead-acid battery 11 are connected to the first and second points N1 and N2, respectively.

[0134] In other words, the electrical loads 15 are connected to the fourth point N4, which forms an outer point, and the lead-acid battery 11 and the lithium-ion battery 12 are connected to the corresponding points at the other points N1 to N3 such that the point to which the lead-acid battery 11 is connected and the fourth point N4 sandwich the point to which the lithium-ion battery 12 is connected. The rotating electric machine 16 is connected to the remaining point.

[0135] In the figures indicated by each of the reference symbols (c) and (d) of Fig. In the circuit configuration example illustrated in FIG. 8, a bypass route 51 is provided to connect the fourth point N4 and the point to which the lead-acid battery 11 is connected; this enables electric power supply from the lead-acid battery 11 to the electrical loads 15 while the lithium-ion battery 12 is disconnected from the circuit configuration. A bypass switch 52 is provided on the bypass route 51. The bypass switch 52 is composed of, for example, a semiconductor switch or an electromagnetic relay switch.

[0136] In the figures indicated by the reference symbols (c) and (d) of Fig. 8, the control unit 30 enables switching between the discharge modes (1) to (3) according to parameters including the charge status and / or the temperature of each of the batteries 11 and 12. In addition, in the circuit configuration examples respectively indicated by reference numerals (c) and (d) of Fig. 8, turning on the bypass switch 52 by the control unit 30 while the vehicle is off causes the supply of a dark current from the lead-acid battery 11 to the electrical loads 15.

[0137] Circuit configuration examples are described below, each of which is indicated by reference numerals (a) and (b) of Fig. 9. In the figures indicated by the reference numerals (a) and (b) of Fig. In the circuit configuration examples illustrated in Figure 9, the lithium-ion battery 12 is connected to the fourth point N4, which forms an external point, and the rotating electric machine 16 is located at the third point N3, which is adjacent to the fourth point N4. The lead-acid battery 11 and the set of electrical loads 15 are interchangeably connected to the remaining first and second points N1 and N2. In particular, reference numeral (a) of Fig. 9, the lead-acid battery 11 and the set of electrical loads 15 are connected to the first and second points N1 and N2, respectively. In contrast, reference symbol (b) of Fig. 9, that the set of electrical loads 15 and the lead-acid battery 11 are connected to the first and second points N1 and N2, respectively.

[0138] In the figures indicated by the reference symbols (a) and (b) of Fig. 9, the control unit 30 enables switching between the discharge modes (1) to (3) according to parameters including the charge status and / or the temperature of each of the batteries 11 and 12.

[0139] For example, when the lithium-ion battery 12 is defined as the priority battery, the control unit 30 sequentially selects one of the discharge modes (1), (2), and (3) in the order of the discharge mode (3), the discharge mode (2), and the discharge mode (1) when the charged capacity of the lithium-ion battery 12 gradually decreases from a large value. In contrast, the control unit 30 sequentially selects one of the discharge modes (1), (2), and (3) in the order of the discharge mode (3), the discharge mode (2), and the discharge mode (1) when the temperature of the lithium-ion battery 12 increases.

[0140] This example enables appropriate use of the batteries 11 and 12 while reducing a load on each of the batteries 11 and 12 based on the use of the corresponding ones of the batteries 11 and 12.

[0141] In the figures indicated by the reference symbols (a) and (b) of Fig. In the circuit configuration examples illustrated in FIG. 9, the lithium-ion battery 12 is connected to the fourth point N4, which is an external point, and the lead-acid battery 11, the set of electric loads 15, and the rotating electric machine 16 are individually connected to the other points. This configuration enables switching between the discharge modes (1) to (3) to be properly performed with the aid of the lithium-ion battery 12, which has a higher voltage region than the lead-acid battery 11 in the battery characteristics indicating the relationship between the SOC and the open-circuit voltage of the battery 11 and those of the battery 12.

[0142] In the following, reference symbols (c) and (d) respectively denote Fig. 9 illustrated circuit configuration examples are described. In the figures indicated by reference numerals (c) and (d) of Fig. In the circuit configuration examples illustrated in Fig. 9, the rotating electric machine 16 is connected to the fourth point N4, which forms an external point, and the lithium-ion battery 12 is connected to the third point N3, which is located adjacent to the fourth point N4. The lead-acid battery 11 and the set of electrical loads 15 are interchangeably connected to the remaining first and second points N1 and N2. In particular, reference symbol (c) of Fig. 9, the lead-acid battery 11 and the set of electrical loads 15 are connected to the first and second points N1 and N2, respectively. In contrast, the reference symbol (d) of Fig. 9, that the set of electrical loads 15 and the lead-acid battery 11 are connected to the first and second points N1 and N2, respectively.

[0143] In other words, the rotating electric machine 16 is connected to the fourth point N4, which forms an outer point, and the lead-acid battery 11 and the lithium-ion battery 12 are connected to the corresponding points of the other points N1 and N3 such that the point to which the lead-acid battery 11 is connected and the fourth point N4 sandwich the point to which the lithium-ion battery 12 is connected. The set of electrical loads 15 is connected to the remaining point.

[0144] In the figures indicated by the reference symbols (c) and (d) of Fig. In the circuit configuration examples illustrated in FIG. 9, the bypass route 51 is provided to connect the fourth point N4 and the point to which the lead-acid battery 11 is connected; this enables electric power supply from the lead-acid battery 11 to the electrical loads 15 while the lithium-ion battery 12 is disconnected from the circuit configuration. The bypass switch 52 is provided on the bypass route 51.

[0145] In the figures indicated by the reference symbols (c) and (b) of Fig. 9, the control unit 30 enables switching between the discharge modes (1) to (3) according to parameters including the charge status and / or the temperature of each of the batteries 11 and 12. In addition, in the circuit configuration examples indicated by reference numerals (c) and (b) of Fig. 9, turning on the bypass switch 52 by the control unit 30 while the vehicle is turned off causes the supply of a dark current from the lead-acid battery 11 to the electrical loads 15.

[0146] In the following, reference symbols (a) and (b) respectively denote Fig. 10 illustrated circuit configuration examples are described. In the circuit configuration examples illustrated by reference numerals (a) and (b), respectively, the lithium-ion battery 12 is connected to the first point N1, which forms an outer point of the first to fourth points N1 to N4, and the lead-acid battery 11 is connected to the second point N2, which is located adjacent to the first point N1. The set of electrical loads 15 and the rotating electrical machine 16 are interchangeably connected to the remaining third and fourth points N3 and N4. In particular, reference numeral (a) of Fig. 10, the set of electrical loads 15 and the rotating electrical machine 16 are connected to the third and fourth points N3 and N4, respectively. In contrast, the reference symbol (b) of Fig. 10, that the rotating electrical machine 16 and the set of electrical loads 15 are connected to the third and fourth points N3 and N4, respectively.

[0147] In addition, the starter motor 13 is also connected to the first point N1.

[0148] In the figures indicated by the reference symbols (a) and (b) of Fig. In the circuit configuration examples illustrated in FIG. 10, controlling the first switch 21 by the control unit 30 enables the electrical route through which the starter motor 13 is driven by the lithium-ion battery 12 to be separated from the electrical route through which the rotating electric machine 16 is driven by the lead-acid battery 11. This reduces mutual interference due to voltage variations in the batteries 11 and 12.

[0149] In addition, the on-off switching of the switches 21 to 23 by the control unit 30 enables one of the lead-acid battery 11 and the lithium-ion battery 12 to be selectively used as a power source for supplying electric power to the electric loads 15 and 16. In addition, the bypass route 51, on which the bypass switch 52 is provided, is arranged to connect the fourth point N4 and the point to which the lead-acid battery 11 is connected. This bypass route 51 and the bypass switch 52 enable the control unit 30 to turn on the bypass switch 52 while the vehicle is turned off to supply a dark current from the lead-acid battery 11 to the electric loads 15.

[0150] A configuration example in which the first to third switches 21 to 23 connected in series are provided on the feed path L1 and other switches are combined is described below.

[0151] The element designated by reference symbol (a) of Fig. The configuration illustrated in Figure 11 is essentially identical to that shown in Fig. 1 or the configuration indicated by reference symbol (a) of Fig. 8. Specifically, the lead-acid battery 11 is connected to the first point N1 on the power path L1, and the electrical load 16, i.e., the rotating electrical machine 16, is connected to the second point N2. The electrical loads 15 are connected to the third point N3, and the lithium-ion battery 12 is connected to the fourth point N4.

[0152] In addition, a switch 61 is connected between the third point N3 and the set of electrical loads 15. The switch 61 is preferably made of a semiconductor switch, or may be made of an electromagnetic relay switch or a DC-DC converter. In summary, any device capable of establishing or interrupting an electrical connection between the third point N3 and the set of electrical loads 15 may be used as the switch 61. The switch 61 may be installed in the battery unit U, such as on the route L3 in the battery unit U, or may be located outside the battery unit U. In the position indicated by reference symbol (a) of Fig. 11, the above-described four switches are respectively provided at predetermined portions of the power supply system.

[0153] This means that in the position indicated by the reference symbol (a) of Fig. 11 illustrated configuration of the switches 61 to that in Fig. 1 or the configuration indicated by reference symbol (a) of Fig. 8, and the electrical loads 15 are connected to the third point N3 via the switch 61. As with the configurations described above, the lead-acid battery 11, the electrical load 16, the set of electrical loads 15, and the lithium-ion battery 12 are separately connected to the corresponding points N1, N2, N3, and N4 on the supply path L1.

[0154] Controlling the switches 21, 22, 23 and 61 by the control unit 30 in this configuration enables appropriate execution of power supply from the batteries 11 and 12 to the electrical loads 15 and 16.

[0155] The elements designated by reference numerals (b) to (d) of Fig. 11 and the configuration examples indicated by reference numerals (a) and (b) of Fig. 12 are modifications of the configuration examples indicated by reference character (a) of Fig. 11 illustrated circuit configuration.

[0156] According to the diagram indicated by reference symbol (b) of Fig. 11, series-connected switches 61 and 62 are connected between the third point N3 and the set of electrical loads 15. That is, as a different point from the one indicated by reference symbol (a) of Fig. 11, the switch 62 has been added. Like the switch 61, the switch 62 may be composed of a semiconductor switch, an electromagnetic relay switch, or a DC-DC converter. The component constituting the switch 62 may be different from the component constituting the switch 61. The switches 61 and 62 may be installed in the battery unit U, such as on the route L3 in the battery unit U, or only the switch 61 may be installed in the battery unit U, and the switch 62 may be located outside the battery unit U, or the switches 61 and 62 may be located outside the battery unit U. In the configuration indicated by reference character (b) of Fig. 11, the above-described five switches are respectively arranged at predetermined portions of the power supply system, which are similar to the configurations described below, respectively designated by reference numerals (c) and (d) of Fig. 11 and the reference symbols (a) and (b) of Fig. 12 are illustrated.

[0157] According to the diagram indicated by reference symbol (c) of Fig. 11 is shown as a different point from the configuration indicated by reference symbol (a) of Fig. 11, a switch 63 is connected in series between the second point N2 and the electrical load 16, i.e., the rotating electrical machine 16. The component constituting the switch 63 is similar to the component constituting the switch 62. The switch 63 may be installed in the battery unit U or located outside the battery unit U.

[0158] According to the diagram indicated by reference symbol (d) of Fig. 11 is shown as a different point from the configuration shown by reference character (a) of Fig. In the configuration illustrated in Figure 11, a switch 64 is connected in series with switch 22 between the second and third points N2 and N3. The component constituting switch 64 is similar to the component constituting switch 62.

[0159] According to the diagram indicated by reference symbol (a) of Fig. 12 is shown as a different point from the configuration shown by reference character (a) of Fig. In the configuration illustrated in Figure 11, a bypass route 65 in which a bypass switch 66 is inserted is connected between the first point N1 and the fifth point N5. The bypass switch 66 may be composed of, for example, a semiconductor switch or an electromagnetic relay switch.

[0160] According to the diagram indicated by reference symbol (b) of Fig. 12 is shown as a different point from the configuration shown by reference character (a) of Fig. In the configuration illustrated in Figure 11, a bypass route 67 in which a bypass switch 68 is inserted is connected between the second point N2 and the fifth point N5. The bypass switch 66 may be composed of, for example, a semiconductor switch or an electromagnetic relay switch.

[0161] Each of the elements designated by reference numerals (a) to (d) of Fig. 13 essentially represents a modification in which a part of the configurations indicated by reference character (c) of Fig. 8 has been changed. In each of the configurations indicated by reference numerals (a) to (d) of Fig. 13, the lead-acid battery 11 is connected to the first point N1 on the feed path L1, and the electrical load 16, ie, the rotating electrical machine 16, is connected to the second point N2, which is similar to the configuration indicated by reference character (c) of Fig. 8. The lithium-ion battery 12 is connected to the third point N3, and the electrical loads 15 are connected to the fourth point N4, which are similar to the configuration shown by reference character (c) of Fig. 8 illustrated configuration.

[0162] According to the diagram indicated by reference symbol (a) of Fig. 13, a switch 71 is connected between the fourth point N4 and the set of electrical loads 15 as a different point from the configuration indicated by reference character (c) of Fig. 8. Like the switches 21 to 23, the switch 71 preferably consists of a semiconductor switch. The switch 71 may consist of an electromagnetic relay or a DC-DC converter as a power conversion device. In summary, any device capable of establishing or interrupting an electrical connection between the fourth point N4 and the set of electrical loads 15 may be used as the switch 71. The switch 71 may be installed in the battery unit U or may be located outside the battery unit U. In the configuration indicated by reference character (c) of Fig. In the configuration illustrated in Figure 8, the bypass route 51 and the bypass switch 52 are optionally provided.

[0163] In particular, in the version designated by reference (a) of Fig. 13, the switches 71 are added to the configuration illustrated by reference symbol (c), and the electrical loads 15 are connected to the fourth point N4 via the switch 71. Like the configurations described above, the lead-acid battery 11, the electrical loads 16, the lithium-ion battery 12, and the set of electrical loads 15 are separately connected to the corresponding points N1, N2, N3, and N4 on the feed path L1.

[0164] Controlling the switches 21, 22, 23, 52 and 71 by the control unit 30 in this configuration enables appropriate execution of power supply from the batteries 11 and 12 to the electrical loads 15 and 16.

[0165] In the version designated by reference symbol (b) of Fig. 13 are shown as a different point from that shown by reference character (c) of Fig. In the configuration illustrated in Figure 8, bypass switches 52 and 72 connected in series are provided on the bypass route 51 connected between the first and fourth points N1 and N4. The bypass switch 72 is preferably composed of a semiconductor switch or an electromagnetic relay switch. Each of the bypass switches described below may also be composed of a semiconductor switch or an electromagnetic relay switch.

[0166] In the version designated by reference symbol (c) of Fig. 13 is shown as a different point from the configuration shown by reference character (c) of Fig. 8, a bypass route 73 is connected between the second and fourth points N2 and N4, and a bypass switch 72 is provided on the bypass route 73.

[0167] In the version designated by reference symbol (d) of Fig. 13 is shown as a different point from the configuration shown by reference character (c) of Fig. 8 illustrates a bypass route 75 connected between the first and third points N1 and N3 and a bypass switch 76 is provided on the bypass route 75 configuration.

[0168] In the version designated by reference symbol (c) of Fig. 13 is shown as a different point from the configuration shown by reference character (c) of Fig. 8, a bypass route 73 is connected between the second and fourth points N2 and N4, and a bypass switch 72 is provided on the bypass route 73.

[0169] The element designated by reference symbol (a) of Fig. 14 represents a modification in which a part of the structure shown by reference character (b) of Fig. 8 has been changed. The configuration indicated by reference symbol (b) of Fig. 14 represents a modification in which a part of the structure shown by reference character (a) of Fig. 9 has been changed.

[0170] In the version designated by reference symbol (a) of Fig. 14 is shown as a different point from the configuration shown by reference character (b) of Fig. In the configuration illustrated in Figure 8, a switch 81 is connected between the third point N3 and the set of electrical loads 15, and a bypass route 82, in which a bypass switch 83 is inserted, is provided between the second point N2 and a sixth point N6. The sixth point N6 is located between the switch 81 and the set of electrical loads 15. The switch 81 and the bypass switch 83 are each preferably composed of a semiconductor switch or an electromagnetic relay switch.

[0171] In the version designated by reference symbol (b) of Fig. 14 is shown as a different point from the configuration shown by reference character (a) of Fig. In the configuration illustrated in FIG. 9, a switch 84 is connected between the second point N2 and the set of electrical loads 15, and a bypass route 85, in which a bypass switch 86 is inserted, is connected between a seventh point N7 and the fourth point N4. The seventh point N7 is located between the switch 84 and the set of electrical loads 15. The switch 84 and the bypass switch 86 are preferably each composed of, for example, a semiconductor switch or an electromagnetic relay switch. Modifications

[0172] The embodiment described above can be modified as described below.

[0173] The Fig. The switch selection control routine illustrated in Fig. 7 is configured when the open circuit voltage of the lithium-ion battery 12 is lower than the open circuit voltage of the lead-acid battery 11 and is greater than the voltage threshold TH1 (NO in each of steps S12 and S14), (1) to control the switches 21 to 23 in the second operating mode when the temperature Temp of the lithium-ion battery 12 is lower than the temperature threshold TH2, (2) to control the switches 21 to 23 in the third operation mode when the temperature Temp of the lithium ion battery 12 is equal to or greater than the temperature threshold TH2.

[0174] This configuration can be modified.

[0175] For example, the control unit 30 may be configured, when the determination in each of steps S12 and S14 is NO, (1) to control the switches 21 to 23 in the third operating mode when the temperature Temp of the lithium-ion battery 12 is lower than the temperature threshold TH2, (2) to control the switches 21 to 23 in the second operating mode when the temperature Temp of the lithium ion battery 12 is equal to or greater than the temperature threshold TH2.

[0176] In addition, a voltage threshold TH11 that is greater than the voltage threshold TH1 may be defined as a second voltage threshold of the open circuit voltage of the lithium-ion battery 12.

[0177] When the open circuit voltage of the lithium-ion battery 12 is lower than the open circuit voltage of the lead-acid battery 11 (NO in step S12), the control unit 30 may determine, as the operation in S14, whether the open circuit voltage of the lithium-ion battery 12 is equal to or less than the voltage threshold TH11.

[0178] If, as a result of the determination in step S14, it is determined that the lithium-ion battery 12 is greater than the second voltage threshold TH11, the control unit 30 controls the switches 21 to 23 in the second mode. Otherwise, if, as a result of the determination in step S14, it is determined that the lithium-ion battery 12 is equal to or less than the second voltage threshold TH11, the control unit 30 controls the switches 21 to 23 in the third mode.

[0179] Defining multiple levels of the voltage threshold as described by this modification enables accurate monitoring of the charge status of the lithium-ion battery 12, making it possible to provide a more suitable configuration for reducing stress on the lithium-ion battery 12 due to use of the lithium-ion battery 12.

[0180] In the Fig. In the switch selection control routine illustrated in Fig. 7, even if the open circuit voltage of the lithium-ion battery 12 is greater than the open circuit voltage of the lead-acid battery 11 (YES in step S12), the control unit 30 may be configured to perform the operation in step S17, that is, to control the switches 21 to 23 in the third mode, when the temperature of the lithium-ion battery 12 is equal to or greater than the temperature threshold TH2. Here, the control unit 30 may be configured to control the switches 21 to 23 in the second mode in step S16 or in the fourth mode in step S18, instead of controlling the switches 21 to 23 in the third mode.

[0181] In the Fig.In the switch selection control routine illustrated in FIG. 7, the control unit 30 is configured to switch the on-off states of the switches 21 to 23 between the first to fourth operating modes when it is determined that there is a drive request for the rotating electric machine 16, however, this configuration may be modified. Specifically, the control unit 30 may be configured to switch the on-off states of the switches 21 to 23 between the first to fourth operating modes regardless of whether there is a drive request for the rotating electric machine.

[0182] The control unit 30 may be configured to monitor the charging status of each of the batteries 11 and 12 according to the charging and discharging histories of the corresponding ones of the batteries 11 and 12.

[0183] The control unit 30 according to this modification is configured to obtain the charging history of each of the batteries 11 and 12 based on: (1) the number of charging cycles of the corresponding batteries 11 and 12, and / or (2) the total time during which the corresponding one of the batteries 11 and 12 has been charged.

[0184] In addition, according to this modification, the control unit 30 is configured to obtain the discharge history of each of the batteries 11 and 12 based on (1) the number of charging cycles of the corresponding batteries 11 and 12, and / or (2) the total time during which the corresponding one of the batteries 11 and 12 has been discharged.

[0185] Then, based on the discharge history, for example, the control unit 30 switches the discharge mode in which the lithium-ion battery 12 discharges electric power to both the set of electric loads 15 and the rotating electric machine 16 to another discharge mode in which the lithium-ion battery 12 discharges electric power to either the set of electric loads 15 or the rotating electric machine 16.

[0186] According to the embodiment described above, the lithium-ion battery 12 is defined as a priority battery and the lead-acid battery as a non-priority battery, however, the lithium-ion battery 12 may be defined as a non-priority battery and the lead-acid battery as a priority battery.

[0187] The above-described embodiment may use any electrical load other than the rotating electrical machine 16 as the second electrical load. For example, the above-described embodiment may use an electrical load requiring high electrical power or current, such as a heater or other similar device, as the second electrical load. The first electrical loads 15 may be loads other than constant-voltage loads.

[0188] The power supply system is not limited to the above-described configuration including the lead-acid battery 11 as a first storage battery and the lithium-ion battery 12 as a second storage battery. For example, the power supply system may be configured to include another secondary battery, such as a nickel-hydrogen storage battery. Lead-acid batteries may be used as the respective first and second storage batteries, or lithium-ion batteries may be used as the respective first and second storage batteries.

[0189] Switches other than semiconductor switches such as MOSFETs may be used as the respective switches 21 to 23 for electrically connecting or interrupting the power supply path L1. For example, an electromagnetic relay switch, a DC-DC converter, or an inverter may be used as at least one of the switches 21 to 23; the DC-DC converter and the inverter each serve as a power conversion device. In this modification, the control unit 30 may be configured to control an opening or closing control of each opening / closing unit included in the DC-DC converter or the inverter, thereby electrically connecting the power supply path L1 or interrupting the electrical conduction of the power supply path L1.

[0190] The power supply devices according to the present disclosure are not necessarily each integrated as a battery unit U. For example, each of the power supply devices may consist of: (1) a unit in which the lithium-ion battery 12 and the switches 21 to 23 are housed in a housing, (2) the control unit 30, which is located outside the unit.

[0191] The power supply devices according to the present disclosure are not limited to on-vehicle power supply devices, and can be used as power supply devices that are not installed in a vehicle. List of reference symbols 11 Lead-acid battery (first storage battery) 12 Lithium-ion battery (second storage battery) 15 Electrical load (first electrical load) 16 Rotating electrical machine (second electrical load) 21 First switch 22 Second switch 23 Third switch 30 Control unit

Claims

[1] A power supply device applicable to a power supply system comprising a first storage battery (11) and a second storage battery (12), the first and second batteries being connected in parallel to a first electrical load (15) and a second electrical load (16), respectively, the power supply device comprising: a first switch (21) inserted in a supply path (L1) through which a supply current for the first and second electrical loads (15, 16) flows, a second switch (22) inserted into the supply path (L1), a third switch (23) inserted into the supply path (L1), wherein each of the first, second and third switches is configured to establish an electrical connection of the supply path or to interrupt the electrical connection of the supply path, a first point (N1) provided at a first end of the first switch (21), the first switch (21) having the first end and a second end as both ends thereof, and the second switch (22) is provided at the second end of the first switch (21), a second point (N2) provided between the first switch (21) and the second switch (22), a third point (N3) provided between the second switch (22) and the third switch (23), a fourth point (N4) provided at a first end of the third switch (23), the third switch (23) having the first end and a second end as both ends thereof, and the second switch (22) being provided at the second end of the third switch (23), wherein each of the first storage battery (11), the second storage battery (12), the first electrical load (15) and the second electrical load (16) is connected to a corresponding one of the first, second, third and fourth points, and a control unit (30) configured to control switching on and off operations of each of the first to third switches (21, 22, 23), wherein one of the first and second storage batteries (11, 12) is defined as a priority battery which is preferably used, and the other of the first and second storage batteries (11, 12) is defined as a non-priority battery, the control unit (30) is configured to control the switching on and off operations of each of the first to third switches (21, 22, 23) according to a parameter comprising a state of charge and a temperature of the first and second storage batteries (11, 12), and the control unit (30) is configured to perform a first discharge mode in which the priority battery supplies electrical power to the first and second electrical loads (15, 16), in any one of: first case, in which the state of charge of the priority battery is higher than the state of charge of the non-priority battery as a result of a comparison between the priority and non-priority batteries, and to select a second case in which the state of charge of the non-priority battery is higher than the state of charge of the priority battery as a result of a comparison between the priority and non-priority batteries, and the state of charge of the priority battery is greater than a predetermined state of charge threshold or the temperature of the priority battery is lower than a predetermined temperature threshold, wherein the control unit (30) is configured to switch between a second discharge mode and a third discharge mode according to the state of charge and / or the temperature of the priority battery when the state of charge of the non-priority battery is higher than the state of charge of the priority battery, wherein the second discharge mode is configured such that the priority battery supplies electric power to one of the first and second electrical loads (15, 16), and the non-priority battery supplies electric power to the other of the first and second loads, and the third discharge mode is configured such that the non-priority battery supplies electrical power to each of the first and second electrical loads (15, 16). [2] A power supply device according to claim 1, wherein: the first and second storage batteries (11, 12) are respectively connected to the first and fourth points, which form the two outer points of the first to fourth points (N1-N4), and the first and second electrical loads (15, 16) are connected to the second and third points, respectively. [3] A power supply device according to claim 1, wherein: the first storage battery (11) has a first battery characteristic curve indicating a relationship between a state of charge (SOC) of the first storage battery (11) and an open circuit voltage of the first storage battery (11), the second storage battery (12) has a second battery characteristic curve which indicates a relationship between the state of charge of the second storage battery (12) and the open circuit voltage of the second storage battery (12), Open-circuit voltage values within a predetermined first region of the state of charge in the second battery characteristic curve are higher than open-circuit voltage values within a predetermined second region of the state of charge in the first battery characteristic curve, the second region corresponding to the first region, the second storage battery (12) is connected to one of the first and fourth points forming the outer points of the first to fourth points (N1-N4), and the first battery, the first electrical load (15) and the second electrical load (16) are connected to the remaining points of the first to fourth points (N1-N4). [4] A power supply device according to claim 1, wherein: the first storage battery (11) has a first battery characteristic curve indicating a relationship between a state of charge (SOC) of the first storage battery (11) and an open circuit voltage of the first storage battery (11), the second storage battery (12) has a second battery characteristic curve which indicates a relationship between the state of charge of the second storage battery (12) and the open circuit voltage of the second storage battery (12), Open-circuit voltage values within a predetermined first region of the state of charge in the second battery characteristic curve are higher than open-circuit voltage values within a predetermined second region of the state of charge in the first battery characteristic curve, the second region corresponding to the first region, one of the first and second electrical loads (15, 16) is connected to one of the first and fourth points forming the two outer points of the first to fourth points (N1-N4), the second storage battery (12) is connected to one of the remaining three points other than the point to which one of the first and second electrical loads (15, 16) is connected, the first storage battery (11) is connected to one of the remaining two points, so that the point to which the first storage battery (11) is connected and one of the first and fourth points sandwich the point to which the second storage battery (12) is connected, and the other of the first and second electrical loads (15, 16) is connected to the last remaining point, the power supply device continues a bypass route (51) connected between the point to which the first storage battery (11) is connected and one of the outer points, and a bypass switch (52) inserted into the bypass route (51), wherein the control unit (30) is configured to control switching on and off operations of the bypass switch (52). [5] A power supply device according to claim 1, wherein: the first storage battery (11) and one of the first and second electrical loads (15, 16) are respectively connected to the first point (N1) and the second point (N2), and the second storage battery (12) and the other of the first and second electrical loads (15, 16) are connected to the third point (N3) and the fourth point (N4), respectively. [6] A power supply device according to any one of claims 1 to 5, wherein: the first electrical load (15) is an electrical load that requires a voltage of the supplied electrical power to be maintained at a constant level or to vary stably within a predetermined range, and the second electrical load (16) is an electrical load to which electrical power or an electrical current is supplied, wherein the electrical power or the electrical current supplied to the second electrical load (16) is higher than electrical power or an electrical current supplied to the first electrical load (15). [7] A power supply device according to any one of claims 1 to 5, wherein: the first electrical load (15) is an electrical load that requires a voltage of the supplied electrical power to be maintained at a constant level or to vary stably within a predetermined range, and the second electrical load (16) is a rotating electrical machine that is rotatably driven based on electrical power or an electrical current, wherein the electrical power or the electrical current for rotatably driving the rotating electrical machine is higher than an electrical power or an electrical current for driving the first electrical load (15). [8] A power supply device according to any one of claims 1 to 7, wherein: one of the first and second storage batteries (11, 12) is connected to one of the first and fourth points forming the two outer points of the first to fourth points (N1-N4), or the first and second storage batteries (11, 12) are each connected to the first and fourth points forming the two outer points of the first to fourth points (N1-N4), wherein the power supply device further comprises: a malfunction determining means (30a) configured to determine whether there is a malfunction in one of the first and second storage batteries (11, 12) connected to one of the first and fourth points, wherein the control unit (30) is configured, when it is determined that there is a malfunction, to control the first to third switches (21, 22, 23) to thereby: to disconnect from the supply path (L1) one of the first and second storage batteries (11, 12) connected to one of the first and fourth points, and to cause the remaining storage battery to supply electrical power to the first and second electrical loads (15, 16). [9] Battery unit (U) with a power supply device according to one of claims 1 to 8, wherein the battery unit (U) comprises: the second storage battery (12), a first connection (P1), a second connection (P2) and a third terminal (P3), wherein the first storage battery (11), the first electrical load (15) and the second electrical load (16) are respectively connected to the first, second and third terminals, wherein the first to third switches (21, 22, 23) are inserted into the feed path (L1) through which the first storage battery (11), the first electrical load (15) and the second electrical load (16) are connected to the second storage battery (12).

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