Electrical energy source system

Abstract

Electrical energy source system for a vehicle, wherein the vehicle comprises a starter device (10) which is driven by electrical energy and starts an engine of the vehicle, wherein the starter device (10) is provided by an electrical energy generator, wherein the electrical energy source system comprises: a lead-acid battery (11) which is electrically connected in parallel with the starting device (10) as a first storage battery; a second storage battery (12) which is electrically connected to the starting device (10), wherein the lead-acid battery (11) and the second storage battery (12) are connected in parallel with respect to the starting device (10); a switching device (15) which is arranged on an electrical path that electrically connects the lead-acid battery (11) with the second storage battery (12) between the lead-acid battery (11) and the second storage battery (12); at least one electrical load (14a, 14b, 14c) connected to the electrical path and located closer to the lead-acid battery (11) on the electrical path compared to the second storage battery (12); and a switching control unit (20) that controls the switching device to maintain a closed state, except during an engine start period during which the engine is started by the starting device (10) after a power supply to the vehicle has been switched on, characterized by: a power supply control device (17, 24) arranged on a bypass path, wherein the bypass path bridges the switching device (15) and is connected to the electrical path connecting the lead-acid battery (11) to the second storage battery (12), wherein, when a fault is detected in the lead-acid battery (11), the power supply control device (17, 24) activates a power supply from the second storage battery (12) to the at least one electrical load (14a, 14b, 14c).

Description

TECHNICAL AREA

[0001] The present disclosure relates to an electrical energy source system for a vehicle. BACKGROUND

[0002] An electrical power supply system for a vehicle comprises several types of storage or accumulator batteries, such as lead-acid batteries and lithium-ion batteries. These different types of storage or accumulator batteries supply energy in a suitable manner to the various electrical loads with which the vehicle is equipped.

[0003] For example, as disclosed in publication JP 2012-130 108 A, a lead-acid battery and a lithium-ion battery are connected via a switch. Some of the electrical loads in the vehicle require a stabilized electrical supply. Here, stabilized electrical supply refers to energy or power that has a constant voltage or a voltage that fluctuates only within a predetermined range. These types of electrical loads are connected to the lithium-ion battery. In this configuration, the lithium-ion battery provides a power supply to the electrical loads that require the stabilized supply. Among the electrical loads, excluding those requiring the stabilized supply, a starter motor and other general electrical loads, such as headlights, are connected to the lead-acid battery.In this configuration, the lead-acid battery provides power to the starter motor and other general electrical loads.

[0004] In the configuration described above, if the lead-acid battery malfunctions, it will be unable to supply power to the general electrical loads connected to it. Similarly, if the lithium-ion battery malfunctions, it will be unable to supply stabilized power to the electrical loads requiring the stabilized power supply. Consequently, malfunctions or abnormalities may occur in the electrical loads requiring the stabilized power supply.

[0005] The patent application US 2012 / 0330538A1, which constitutes the generic prior art, discloses a (generic) electrical energy source system according to the preamble of the independent claim. In particular, it discloses an electrical system for a vehicle with an internal combustion engine with start / stop capability, comprising: a primary battery connectable to a motor starter motor; a secondary battery, an alternator, and an electrical load connected in parallel to each other and selectively connectable in parallel to the primary battery by means of a charging switch; a DC / DC converter connected in parallel to the secondary battery and in series with a third electrical energy source; and a bypass switch operable to selectively bypass the DC / DC converter.The bypass switch allows selective bypassing of the DC / DC converter and charging / discharging of the third electrical energy source during start-stop operation to ensure a sufficient voltage level across the vehicle's additional electrical consumers when the combustion engine and thus the alternator are not running.

[0006] Further prior art is known from the publications DE 102 29 018 A1, DE 196 45 944 A1, DE 10 2011 056 270 A1 and EP 0 601 300 A1. SUMMARY

[0007] In view of the aforementioned difficulties, one objective of the present disclosure is to provide an electrical energy source system that can continuously and stably supply energy to different types of electrical loads.

[0008] According to the invention, an electrical energy source system is provided as defined in the patent claims.

[0009] The aforementioned electrical energy source system can provide a continuous and stable energy supply to the electrical loads with which the vehicle is equipped. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The aforementioned and further tasks, features and advantages of the present disclosure will become clearer from the following detailed description, which is given with reference to the accompanying drawings. Fig. Figure 1 is a circuit diagram showing an electrical energy source system according to an embodiment of the present disclosure; Fig. 2A is a diagram showing a SOC-based operating range of a lead-acid battery; Fig. 2B is a diagram showing a SOC-based application range of a lithium-ion battery; Fig. Figure 3 is a representation showing an IV characteristic curve of a lead-acid battery and an IV characteristic curve of a lithium-ion battery; Fig. 4 is a flowchart showing a switching control process; Fig. 5 is a flowchart showing an energy limitation process; Fig. Figure 6 is a time graph showing signal changes related to a power supply during vehicle operation over time; Fig. Figure 7 is a time graph showing signal changes related to a power supply during vehicle operation over time; and Fig. Figure 8 is a circuit diagram showing an electrical energy source system according to a further embodiment of the present disclosure. DETAILED DESCRIPTION

[0011] The following describes exemplary embodiments of the present disclosure with reference to accompanying drawings. In these exemplary embodiments, a vehicle equipped with an electrical energy source system uses an internal combustion engine as its power source. The vehicle features an idle speed reduction function and an idle speed driving function.

[0012] As it is in Fig. As shown in Figure 1, the electrical power source system comprises a rotary device or rotator or starter 10, a lead-acid battery (Pb-BATTERY) 11, a lithium-ion battery (Li-BATTERY) 12, a starter (ST) 13, several electrical loads (LOADS) 14a to 14c, a metal oxide semiconductor (MOS) switch 15, and a switching rectifier (SMR) switch 16. The lithium-ion battery 12 and the switches 15 and 16 are housed in an integrated unit (not shown). This integrated unit is referred to as the battery unit U. The battery unit U further comprises a control unit 20 for controlling the lithium-ion battery 12. The switches 15 and 16 and the control unit 20 are mounted on the same circuit board, which is housed in the enclosure.

[0013] The battery unit U further comprises a first terminal T1 and a second terminal T2. The lead-acid battery 11, the starter 13, and the electrical loads 14a to 14c are connected to the first terminal T1, and the rotary device 10 is connected to the second terminal T2. Each of the two terminals T1 and T2 supports a high current flow, such as an input current or an output current of the rotary device 10.

[0014] A rotary axis of the rotary device 10 is operationally connected to an output shaft of a motor (not shown) by means of a belt or similar device. When the motor's output shaft rotates, the rotary axis of the rotary device 10 is driven, causing it to rotate. The rotary device 10 can generate or regenerate electrical energy or power by rotating the motor's output shaft or a vehicle axle. Furthermore, the rotary device 10 supplies a torque to the motor's output shaft to drive the motor. Thus, the rotary device 10 can generate electrical energy and also drive the motor by supplying the torque to the motor.In the present disclosure, the rotary device is provided by an integrated starter generator (ISG).

[0015] The lead-acid battery 11 and the lithium-ion battery 12 are connected in parallel with respect to the rotating device 10. When the rotating device 10 generates electrical energy, the batteries 11 and 12 can be charged by the generated electrical energy. The rotating device 10 is driven by the electrical energy supplied by each of the batteries 11 and 12.

[0016] The lead-acid battery 11 is a well-known storage or accumulator battery. Compared to the lead-acid battery 11, the lithium-ion battery 12 exhibits lower energy loss during charging and discharging, and its output power density and energy density are higher than those of the lead-acid battery 11. Thus, the lithium-ion battery 12 is a high-density storage or accumulator battery. In the present disclosure, the lithium-ion battery 12 is described as an example of a second storage or accumulator battery, and the lead-acid battery 11 is described as an example of a first storage or accumulator battery. In the present disclosure, the second storage or accumulator battery exhibits a higher output power density and a higher energy density than the first storage or accumulator battery.

[0017] In the lead-acid battery 11, the active material of the positive electrode is provided by lead dioxide (PbO2), the active material of the negative electrode is provided by lead (Pb), and the electrolyte is provided by sulfuric acid (H2SO4). The lead-acid battery 11 comprises several battery cells with the electrode material described above, and the several battery cells are connected in series. These several battery cells configure a battery cell group 11a. In the present embodiment, it is assumed that the electrical storage capacity of the lead-acid battery 11 is greater than the electrical storage capacity of the lithium-ion battery 12.

[0018] In the lithium-ion battery 12, the active material of the positive electrode is provided by an oxide containing lithium, such as lithium composite metal oxide. For example, the lithium composite metal oxide can include LiCoO2, LiMn2O4, LiNiO2, LiFePO4, or the like. In the lithium-ion battery 12, the active material of the negative electrode is provided by an alloy containing carbon (C), graphite, lithium titanate (for example, Li x The lithium-ion battery 12 comprises TiO2), Si, Su, or the like. In the lithium-ion battery 12, the electrolyte is provided by an organic electrolyte. The lithium-ion battery 12 comprises several battery cells with the electrode material described above, and the several battery cells are connected in series. These several battery cells configure a battery cell group 12a.

[0019] As it is in Fig. As shown in Figure 1, the lead-acid battery 11 comprises the battery cell group 11a and an internal resistance 11b. Similarly, the lithium-ion battery 12 comprises the battery cell group 12a and an internal resistance 12b. In the following description, a voltage generated by the battery cell group 11a, 12a in an open state is represented as the open-circuit / resting voltage (or open terminal / voltage) V0, a ​​current flowing through the battery 11, 12 in a discharge state is represented as the discharge current Id, and a current flowing through the battery 11, 12 in a charge state is represented as the charge current Ic. The internal resistance 11b and 12b has a resistance value R. In this case, the terminal voltage Vd in a discharge state and the terminal voltage Vc in a charge state are defined by the following expressions 1 and 2. Vd=V0−Id×R Vc=V0+Ic×R

[0020] As shown by expressions 1 and 2, the terminal voltage Vd decreases in the discharge state with an increase in the internal resistance R, and the terminal voltage Vc increases in the charging state with an increase in the internal resistance R.

[0021] Among the electrical loads 14a to 14c, loads 14a and 14b must be protected by ensuring a constant and stable supply of the operating voltage at which they can function normally. This means that loads 14a and 14b must be supplied with stabilized electrical energy. Here, stabilized electrical energy refers to energy that has a constant voltage or a voltage that fluctuates only within a predetermined range. Thus, loads 14a and 14b operate within a predetermined voltage range and cease operation if the supply voltage falls outside this range. In other words, if the supply voltage falls outside the predetermined voltage range, loads 14a and 14b are reset.

[0022] The electrical load 14a, which requires the stabilized power supply, is an electrical load related to the vehicle's driving operation. For example, the electrical load 14a could be a braking device, an oil pump integrated into an automatic transmission, a fuel pump, a power steering device, or the like. The electrical load 14a is a driving-related electrical load for controlling the vehicle's driving behavior.

[0023] The electrical load 14b, which also requires a stabilized power supply, is a different electrical load than the electrical load related to vehicle operation. For example, the electrical load 14b could be a navigation device, a display device for showing various instruments, an audio device, or the like. The electrical loads 14a and 14b can operate in a stable manner by suppressing or limiting voltage fluctuations in the power supply to the electrical loads 14a and 14b.

[0024] Electrical load 14c is a general electrical load, excluding the starter 13 and electrical loads 14a and 14b. As described above, electrical loads 14a and 14b require a stabilized power supply. Electrical load 14c is capable of operating within a voltage range wider than the predetermined voltage range required by electrical loads 14a and 14b. For example, the general electrical load could be headlights, windshield wipers, a ventilation fan of an air conditioning system, a defrost heating element of a rear window, or the like. If the voltage of the power supply to the headlights, wipers, and ventilation fan fluctuates, the headlights may flicker, the wipers' operating speed may change, and the ventilation fan's rotational speed may change.Changes in the rotational speed of the ventilation fan can cause a change in the noise of the air bubbles. Therefore, the voltage of the power supply to these devices must be constant.

[0025] The battery unit U has a first connection path 21 and a second connection path 22, which are arranged within the battery unit U. The first and second connection paths 21, 22 connect terminals T1 and T2 to the lithium-ion battery 12. Specifically, the first connection path 21 connects the first terminal T1 to the second terminal T2 and includes the MOS switch 15 as a switching device. Furthermore, the second connection path 22 connects a point N1 of the first connection path 21 to the lithium-ion battery 12. Here, point N1 of the first connection path 21 is located between the first terminal T1 and the second terminal T2 and is referred to as the battery connection point. Furthermore, the second connection path 22 includes the SMR switch 16. Each of the MOS switch 15 and the SMR switch 16 includes several MOS field-effect transistors (FETs), and the number of MOSFETs is 2 x n. Here, n denotes an integer.Specifically, two MOSFETs each configure a MOSFET set, and the MOSFETs are connected in series such that a parasitic diode from each MOSFET set is defined in the opposite direction to a parasitic diode of an adjacent MOSFET set. With this configuration, when switches 15 and 16 are in the OFF states, any current flowing through the path on which each switch 15 or 16 is located can be completely interrupted by the parasitic diode of the corresponding switch.

[0026] The electrical power source system further comprises a bypass or shunt path 23 that bypasses the MOSFET switch 15. The bypass path 23 allows the lead-acid battery 11 to be connected directly to the rotary device 10 without the MOSFET switch 15 intervening. Specifically, the bypass path 23 directly and electrically connects an electrical path connected to the first terminal T1 to an electrical path connected to the second terminal T2, without passing through the battery unit U. Here, the electrical path connected to the first terminal T1 is an electrical path connected to the lead-acid battery 11, and the electrical path connected to the second terminal T2 is an electrical path connected to the rotary device 10. The bypass path 23 comprises a bypass or shunt path 23.The bypass switch 24 is a power supply control device that activates or deactivates a connection between a circuit part located on the side of the lead-acid battery 11 and a circuit part located on the side of the rotary device. The bypass switch 24 is a normally closed relay switch. The bypass path 23 and the bypass switch 24 can also be included in the battery unit U. In this case, the bypass path 23 and the bypass switch 24 are configured to bypass the MOS switch 15 in the battery unit U.

[0027] The control unit 20 is connected to an electronic control unit (ECU) 30, which is located outside the battery unit U. The control unit 20 is connected to the ECU 30 via a communication network such as a Controller Area Network (CAN). The control unit 20 and the ECU 30 are capable of bidirectional communication. Furthermore, data stored in the control unit 20 and the ECU 30 can be shared or used jointly by both the control unit 20 and the ECU 30. The ECU 30 performs idle speed reduction control and idle speed control. In idle speed reduction control, the engine is automatically switched off when a predetermined condition for automatic shutdown is met, and the engine is restarted from the switched-off state in response to the fulfillment of a predetermined restart condition. In idle speed control, the vehicle is controlled to maintain a stable idle speed.Inert driving involves performing idle driving in a state where fuel supply to the engine is deactivated. Inert driving aims to improve fuel efficiency. During inert driving, a clutch located between the engine and transmission disconnects the engine from the transmission, allowing the vehicle to be driven using its inertia when the accelerator is off.

[0028] In each of the idle reduction control and idle speed control, the engine is automatically switched off in response to the fulfillment of a predetermined condition for automatic engine shutdown, such as the accelerator being in the OFF state. After the engine is switched off, the engine is restarted by the rotary device 10 when a restart condition is met.

[0029] As described above, the rotary device 10 also generates electrical energy or power through the rotational energy delivered by the output shaft of the motor. Specifically, when a rotor enclosed in the rotary device 10 begins to rotate, driven by the output shaft of the motor, an excitation current is generated in a rotor coil, and an alternating current is induced in a stator corresponding to the excitation current generated in the rotor coil. The generated alternating current is then converted into a direct current by a rectifier (not shown). The excitation current generated in the rotor coil is regulated by a controller to ensure that the direct current generated by the rotary device 10 has a predetermined control voltage Vreg.

[0030] The electrical energy generated in the rotary unit 10 is supplied to the electrical loads 14a to 14c and also stored in the lead-acid battery 11 and the lithium-ion battery 12. When the motor stops operating and the rotary unit 10 accordingly stops generating electrical energy, the lead-acid battery 11 and the lithium-ion battery 12 supply electrical energy to the electrical loads 14a to 14c. The amount of discharge from the lead-acid battery 11 and the lithium-ion battery 12 to the electrical loads 14a to 14c is appropriately controlled within a SOC-based operating range to prevent over-discharging. Likewise, the amount of charge to the lead-acid battery 11 and the lithium-ion battery 12 is appropriately controlled by the rotary unit 10 within the SOC-based operating range to prevent over-charging. Here, SOC stands for "State of Charge".State of charge (SOC) refers to the available battery charge level. SOC also denotes the ratio of an actually charged battery level to a fully charged battery level.

[0031] The control unit 20 performs protective control to protect the battery 12 from overcharging and over-discharging. Specifically, the control unit 20 limits the amount of charge to or discharge from the lithium-ion battery 12 to ensure that the state of charge (SOC) of the lithium-ion battery 12 remains appropriately within a predetermined operating range. The predetermined operating range W2, which is defined in Fig. The section specified in 2B is described in detail below.

[0032] To perform the protective control, the control unit 20 continuously monitors the detected terminal voltages Vc(Li) and Vd(Li) of the lithium-ion battery 12 or the detected open-circuit / quiescent voltage V0(Li) of the lithium-ion battery 12. The control unit 20 also continuously monitors the current flowing through the lithium-ion battery 12, which is detected by a current detector (not shown). For example, if the terminal voltage Vd of the lithium-ion battery 12 decreases in the state of discharge so that it falls below a lower limit voltage, the rotary device 10 is activated to supply charging energy to the lithium-ion battery 12 to protect it from over-discharge. Here, the lower limit voltage is preset according to a lower limit of the state of charge (SOC) operating range. In this embodiment, the lower limit of the SOC operating range is defined as 10%.At the same time, the control unit 20 controls the terminal voltage Vc of the lithium-ion battery 12 during the state of charge, ensuring that it is equal to or lower than an upper limit voltage to protect the lithium-ion battery 12 from overcharging by instructing a change in the control voltage Vreg. Here, the upper limit voltage is preset according to an upper limit of the state of charge (SOC) operating range. In this embodiment, the upper limit of the SOC operating range is defined as 90%.

[0033] For the lead-acid battery 11, a battery control unit, which is similar to the control unit 20 described above but not shown, performs a similar protection control for the lead-acid battery 11.

[0034] In the present embodiment, the rotary device 10 uses regenerative energy from the vehicle, generated during a reduction in vehicle speed, to produce electrical energy and charge the two storage or accumulator batteries 11, 12 with the generated electrical energy. During charging, the lithium-ion battery 12 is primarily charged by the generated electrical energy. This type of regeneration, utilizing vehicle speed reduction, is performed in response to a reduction in vehicle speed or the deactivation of fuel injection to the engine.

[0035] In the present embodiment, the charging and discharging of the lithium-ion battery 12 is carried out with a higher priority between the two storage or accumulator batteries 11 and 12. A characteristic of each battery 11, 12 is described below with regard to Fig. 2A to Fig. 3 described.

[0036] In a Fig. In graph 2A, a horizontal axis denotes the state of charge (SOC) of the lead-acid battery 11, and a solid line A1 represents a voltage characteristic curve that describes the relationship between the open-circuit / resting voltage V0(Pb) of the lead-acid battery 11 and the SOC of the lead-acid battery 11. The open-circuit / resting voltage V0(Pb) increases proportionally with an increase in the SOC. Here, the increase in SOC denotes an increase in the charge applied to the lead-acid battery 11. In a Fig. In graph 2B, a horizontal axis denotes the state of charge (SOC) of the lithium-ion battery 12, and a solid line A2 represents a voltage characteristic curve that describes the relationship between the open-circuit voltage V0(Li) of the lithium-ion battery 12 and the SOC of the lithium-ion battery 12. The open-circuit voltage V0(Li) increases with an increase in the SOC. Here, the increase in the SOC denotes an increase in the charge level of the lithium-ion battery 12. The voltage characteristic curve A2 includes two inflection points, P1 and P2. At each inflection point P1, P2, there is a sharp change in the slope of the voltage characteristic curve A2. A segment between the two inflection points P1 and P2 exhibits a relatively small change in slope.

[0037] If the storage or accumulator batteries 11, 12 undergo excessive discharge or overcharging, premature deterioration may occur. Therefore, the storage or accumulator batteries 11, 12 must be controlled to operate within a range other than excessive charging or excessive discharging. Specifically, the storage or accumulator batteries 11, 12 must be controlled to operate within a suitable operating range defined based on the state of charge (SOC). Hereinafter, the suitable operating range defined based on the SOC is also referred to as the SOC-based operating range.The SOC-based operating range W1(Pb) of the lead-acid battery 11 can be defined in a range of 88% to 100%, and the SOC-based operating range W2(Li) of the lithium-ion battery 12 can be defined in a range of 10% to 90%. The SOC-based operating range W2(Li) of the lithium-ion battery 12 can also be defined as being greater than 0% and less than 100%.

[0038] In lead-acid battery 11, early or premature deterioration can occur within the SOC range of 0% to 88%. Furthermore, it states Fig. Figure 2B shows an enlarged view of a part that is in Fig. 2A is shown by a dashed line. The part shown by the dashed line corresponds to the SOC-based operating range W1(Pb) of the lead-acid battery 11. As shown in Fig. 2A and Fig. As shown in 2B, a point corresponds to the SOC value of 0% with reference to the lead-acid battery 11, which is in Fig. Figure 2B shows the SOC value of 88% with reference to the lithium-ion battery 12. Here, the SOC value of 88% of the lithium-ion battery 12 represents a starting point of the SOC-based operating range W1(Pb) of the lead-acid battery 11.

[0039] The battery characteristics of the lithium-ion battery 12 are preset such that the voltage characteristic of the lithium-ion battery 12 fulfills the following five conditions, comprising the first through fifth conditions. The battery characteristics of any storage or accumulator battery 11, 12 can be adjusted by appropriately setting the open-circuit / resting voltage V0 and the internal resistance R. In the lithium-ion battery 12, the open-circuit / resting voltage V0 can be adjusted by appropriately selecting the active material of the positive electrode, the active material of the negative electrode, and the electrolyte. 1. First condition

[0040] As it is in Fig. As shown in Figure 2B, within the entire state of charge (SOC) range (0% to 100%) of the lithium-ion battery 12, a specific point Vds exists in a predetermined region on one side of the lower SOC of the SOC-based operating range W2(Li). At this specific point Vds, the open-circuit voltage V0(Li) of the lithium-ion battery 12 is equal to the open-circuit voltage V0(Pb) of the lead-acid battery 11. Furthermore, throughout the entire SOC-based operating range W2(Li), the open-circuit voltage V0(Li) of the lithium-ion battery 12 is always higher than the open-circuit voltage V0(Pb) of the lead-acid battery 11. In the Fig. In the battery characteristic shown in Figure 2B, a kink point P1 is defined corresponding to a state of charge (SOC) lower than the lower limit of the SOC-based operating range W2(Li), and another kink point P2 is defined corresponding to a SOC higher than the upper limit of the SOC-based operating range W2(Li). Furthermore, on the voltage characteristic A2, the special point Vds is positioned relative to kink point P1 corresponding to a higher SOC. Alternatively, the special point Vds can be positioned relative to kink point P1 corresponding to a lower SOC. 2. Second condition

[0041] During the charging state, the internal resistance R(Li) of the lithium-ion battery 12 and the internal resistance R(Pb) of the lead-acid battery 11 are set such that they satisfy the relationship R(Li) < R(Pb). During the discharging state, the internal resistance R(Li) of the lithium-ion battery 12 and the internal resistance R(Pb) of the lead-acid battery 11 are set such that they satisfy the relationship R(Li) ≤ R(Pb). A difference between the current-voltage (IV) characteristics of the two batteries 11 and 12 is in Fig. 3 shown. In Fig. 3 denotes a solid line B1(Pb) the IV characteristic curve of the lead-acid battery 11, a solid line B2(Li) denotes the IV characteristic curve of the lithium-ion battery 12, and a solid line B3 denotes a regulated voltage Vreg. In the Fig. In the graphs shown, the horizontal axis denotes the current Ic, Id, and the vertical axis denotes the terminal voltage Vc, Vd. Furthermore, the current Ic during the charging state is denoted by a positive value, and the current Id during the discharging state is denoted by a negative value.

[0042] In each of the IV characteristic curves B1 and B2, the terminal voltage Vc increases proportionally with an increase in the charging current Ic during the charging state, and the terminal voltage Vd decreases proportionally with a decrease in the discharging current Id during the discharging state. Here, the increase in terminal voltage Vc denotes the charging state, and the decrease in terminal voltage Vd denotes the discharging state. A slope of each of the IV characteristic curves B1 and B2 denotes the internal resistance R. In the lithium-ion battery 12, the internal resistance R(Li) is the same during both the charging and discharging states. In the lead-acid battery 11, the internal resistance R(Pb) during the charging state is greater than the internal resistance R(Pb) during the discharging state. Thus, the internal resistances R of the two batteries during the charging state satisfy the relationship R(Li) < R(Pb).Furthermore, the internal resistance values ​​of the two batteries during the discharge state satisfy the relationship R(Li) ≤ R(Pb).

[0043] To fulfill the condition described above, during the operating state of the electrical loads 14a to 14c, i.e., during the discharge state of the batteries 11, 12, the terminal voltages Vd can be adjusted so that they satisfy a relationship Vd(Li) > Vd(Pb). Furthermore, during the charging of the batteries 11, 12 by the rotary device 10, the terminal voltages can be adjusted so that they satisfy a relationship Vc(Li) > Vc(Pb) within a predetermined range near zero of the current Ic, and the terminal voltages can be adjusted so that they satisfy a relationship Vc(Li) < Vc(Pb) in the remaining range, except for the predetermined range near zero of the current Ic. Under this setting condition, the internal resistance value R(Li) of the lithium-ion battery 12 can be controlled so that it is smaller than the internal resistance value R(Pb) of the lead-acid battery 11 during the charging state of the batteries 11, 12. 3. Third condition

[0044] During the charging state, the terminal voltage Vc(Li) of the lithium-ion battery 12 is set to be lower than the control voltage Vreg generated by the rotary device 10 when a maximum charging current (Imax) flows through the lithium-ion battery 12. This means that during the charging state, the lithium-ion battery 12 has a terminal voltage Vc(Li) that corresponds to the upper limit (90%) of the SOC-based operating range W2(Li), and is set to a value lower than the control voltage Vreg. 4. Fourth condition

[0045] The SOC-based operating area W2(Li) of the lithium-ion battery 12 includes a midpoint P3 at a central position within the SOC-based entry area W2(Li). The slope of the voltage characteristic A2, corresponding to a lower SOC side from midpoint P3, is set to be different from the slope of the voltage characteristic A2, corresponding to a higher SOC side from midpoint P3. Here, the slope of the voltage characteristic A2 denotes the rate of change of the open-circuit / quiescent voltage with respect to the SOC. When this condition is met, the voltage characteristic A2 exhibits a wave-like or upward-curving shape. In this case, with respect to midpoint P3, the slope (average slope) of the voltage characteristic A2 on the lower SOC side is greater than the slope of the voltage characteristic A2 on the higher SOC side.Furthermore, instead of defining the midpoint P3 at the center position of the SOC-based application range W2(Li), a point can be defined as a reference point that is near the upper limit or near the lower limit of the SOC-based application range W2(Li). In this case, the slope of the stress characteristic A2 can be set based on the reference point that is near the upper limit or the lower limit of the SOC-based application range W2(Li). 5. Fifth condition

[0046] In the voltage characteristic A2 of the lithium-ion battery 12, a segment between the inflection points P1 and P2 has a relatively small slope, and a segment corresponding to the side of lower SOC from the inflection point P1 and a segment corresponding to the side of higher SOC from the inflection point P2 each have slopes that are greater than the slope of the segment between the inflection points P1 and P2.

[0047] Control unit 20 controls the switching on and off of each switch 15, 16. Therefore, control unit 20 is also referred to as a switching control unit. When the vehicle's ignition switch is in the OFF state, control unit 20 keeps switches 15, 16 in the OFF state. When the ignition switch is ON, control unit 20 keeps MOS switch 15 and SMR switch 16 in the ON state, and then, when the engine start is activated by the rotary device 10, control unit 20 switches off MOS switch 15. Control unit 20 also switches off MOS switch 15 when the engine is restarted from the OFF state after the vehicle's ignition switch has been turned on.In this case, after the ignition switch is turned on, the engine may be shut down by the idle reduction control or the idle speed control, and then the engine will be restarted from the OFF state in response to the fulfillment of the engine restart condition.

[0048] With the configuration described above, the electrical loads 14a to 14c are always connected to the two storage batteries 11, 12 after the vehicle power supply (ignition switch) is switched on and before the engine restarts from the OFF state. During the engine restart period, the MOS switch 15 is kept in the OFF state. This prevents the voltage fluctuation caused by the operation of the rotary device 10 from being transmitted to the lead-acid battery 11 and each of the electrical loads 14a to 14c.

[0049] If the lead-acid battery 11 has a fault, such as a disconnection of the terminal from the connecting object, by switching off the MOS switch 15, the power supply to the electrical loads 14a to 14c can be interrupted.

[0050] Considering the scenario described above, the control unit 20 determines whether a fault is present in the lead-acid battery 11. If it is determined that the lead-acid battery 11 is normal, i.e., that no fault is detected, the MOS switch 15 is switched off in response to a motor restart. If it is determined that the lead-acid battery 11 is abnormal, i.e., that any fault is detected, the MOS switch 15 is kept in the ON state, and the electrical loads 14a to 14c are continuously supplied with energy from the lithium-ion battery 12.

[0051] If the motor automatically shuts down and the lead-acid battery 11 has a fault, the energy consumption of the lithium-ion battery 12 must advantageously be reduced to ensure sufficient electrical energy for safe vehicle operation. In the present embodiment, if the motor shuts down automatically and the lead-acid battery 11 has a fault, the energy supply from the lithium-ion battery 12 to the electrical loads 14a to 14c is limited.

[0052] When the engine shuts off automatically due to the idle control, the energy consumption of the lithium-ion battery 12 is limited to ensure vehicle safety, as the vehicle is still in a driving state. In the automatic engine shutdown state, the idle control is determined to trigger automatic engine shutdown when the vehicle speed exceeds a predetermined threshold Th. In this case, power is maintained to the driving-related electrical load 14a, while power to the electrical loads 14b and 14c, which are not related to vehicle operation, is limited. This means that the power supply to electrical loads 14b and 14c is switched off.Hereinafter, each of the electrical loads 14b and 14c that is not related to the vehicle's operation will also be referred to as a non-operating electrical load. Since the power supply to the operating-related electrical load is maintained, evacuation or clearing operations can be reliably carried out by the vehicle's driver for safety purposes.

[0053] In the automatic engine shutdown state, it is determined that the automatic engine shutdown is triggered by the idle speed reduction control when the vehicle speed is equal to or less than the predetermined threshold Th. In this case, the energy supply to all electrical loads 14a to 14c is limited, regardless of whether the electrical loads 14a to 14c are related to vehicle operation or not. This configuration allows the energy consumption of the lithium-ion battery 12 to be reduced as much as possible.

[0054] The following will refer to Fig. 4 and Fig. Five processes are described that are executed by the control unit 20. Fig. Figure 4 is a flowchart showing a process executed by the control unit 20 to control the switching on and off of the MOS switch 15. Fig. Figure 5 is a flowchart showing a process executed by control unit 20 to limit the energy supply. The in Fig. 4 and Fig. The processes shown in Figure 5 are executed repeatedly at predetermined intervals after the vehicle's power supply or electrical system is switched on. In the following description, the SMR switch 16 is always in an ON state.

[0055] The following will describe the in Fig. The process shown in Figure 4 is described. In S10, the control unit 20 determines whether the motor is started by the rotary device 10. If the control unit 20 determines in S10 that the motor is to be started, the control unit 20 determines in S11 whether the lead-acid battery 11 is in a normal state. That is, the control unit 20 determines whether a fault is present in the lead-acid battery 11. This determination is made based on the detected terminal voltage or the detected current flowing through the lead-acid battery 11. If the control unit 20 determines in S11 that the lead-acid battery 11 is in a normal state, the control unit 20 switches off the MOS switch 15 in S12. If the control unit 20 determines in S11 that a fault is present in the lead-acid battery 11, the control unit 20 keeps the MOS switch 15 in S13 in an ON state. If a fault occurs in the lead-acid battery 11, the engine is started in a state in which the energy supply or-supply to the electrical loads 14a to 14c is continued by the lithium-ion battery 12.

[0056] If the control unit 20 does not determine a motor start in S10, i.e., at a time other than the motor start duration, the control unit 20 proceeds to S13 and switches on the MOS switch 15. With this configuration, at a time other than the motor start duration, both the lead-acid battery 11 and the lithium-ion battery 12 are connected to the electrical loads 14a to 14c.

[0057] The following will describe the in Fig. The process shown in Figure 5 is described. In S20, the control unit 20 determines whether the engine is in an automatic shutdown state. If the engine enters an automatic shutdown state due to the idle reduction control or the idle speed control, the control unit 20 determines in S20 that the engine is in an automatic shutdown state and proceeds to S21. In S21, the control unit 20 determines whether a fault occurs in the lead-acid battery 11. Thus, the control unit 20 acts as an example of a fault detection unit. For example, the fault in the battery could refer to a condition in which a terminal is disconnected due to vibration or acceleration G generated while driving the vehicle. If the control unit 20 determines in S21 that the lead-acid battery 11 is in a normal state, the process is terminated.If the control unit 20 in S21 determines that a fault is occurring in the lead-acid battery 11, the control unit 20 proceeds to S22.

[0058] In S22, control unit 20 determines whether the vehicle speed is equal to or higher than the predetermined threshold value Th. The threshold value Th is preset to determine whether the automatic engine shutdown is triggered by the idle speed reduction control or the idle speed control. For example, the threshold value Th can be set to 20 kilometers per hour.

[0059] If the control unit 20 in S22 determines that the vehicle speed is equal to or greater than the threshold Th, the control unit 20 determines that automatic engine shutdown is triggered by the idle speed control and performs a first power supply limitation. In the first power supply limitation, power is cut off to electrical loads 14b and 14c that are not related to vehicle operation. If the control unit 20 in S22 determines that the vehicle speed is less than the threshold Th, the control unit 20 determines that automatic engine shutdown is triggered by the idle speed reduction control and performs a second power supply limitation. In the second power supply limitation, power is cut off to all electrical loads 14a to 14c.

[0060] If control unit 20 determines in S20 that the motor is not in an automatic shutdown state, control unit 20 advances to S25. In S25, control unit 20 determines whether the motor has just restarted and whether one of the first and second power supply limits is currently being executed. If control unit 20 determines that the motor has just restarted and whether one of the first and second power supply limits is currently being executed, control unit 20 advances to S26 and disables the power supply limit that is currently being executed.

[0061] The following is a specific example to illustrate the processes described above with reference to the in Fig. 6 and Fig. The 7 time diagrams shown are described. Fig. Figure 6 is an embodiment when the lead-acid battery 11 is operating in a normal state. Fig. Figure 7 is an embodiment where a fault occurs in the lead-acid battery 11.

[0062] As it is in Fig. As shown in Figure 6, during the vehicle's driving state, it is assumed that the condition for automatic engine shutdown is met by the idle speed reduction control, which is activated at time t1. In response to the activation of the idle speed reduction control, the engine automatically shuts down. The vehicle speed for activating the automatic engine shutdown condition can, for example, be set to 10 kilometers per hour, and it is assumed that the vehicle speed decreases to zero after one second. At this time, the energy supply limitation by the control unit 20 is not performed, since the lead-acid battery 11 is in its normal operating state.

[0063] At time t2, when the motor restart condition is met, for example by switching on or activating the accelerator, the rotary device 10 drives the motor to start operation and the motor is restarted. At this time t2, the MOS switch 15 is switched off so that any energy or power fluctuation caused by the motor restart by the rotary device 10 is not transmitted to the lead-acid battery 11.

[0064] After a predetermined time interval from time t2, the MOS switch 15 is switched on again, and the vehicle starts moving at the same time. During the vehicle's driving state, it is assumed that an automatic engine shutdown condition is met by the idle speed control, which is activated at time t3. In response to the activation of the idle speed control, the engine automatically stops operating when the vehicle speed is equal to or greater than the threshold value Th. In this case, the power supply limitation by the control unit 20 is not implemented because the lead-acid battery 11 is in its normal operating state. At time t4, when the engine restart condition is met, the rotary device 10 drives the engine to start, and the engine restarts with the MOS switch 15 in the OFF state.Thus, the energy or power fluctuation caused by the restart of the motor by the rotating device 10 is prevented or suppressed.

[0065] As it is in Fig. As shown in Figure 7, during the vehicle's driving state, it is assumed that the condition for automatic engine shutdown is met by the idle speed reduction control, which is activated at time t11. In response to the activation of the idle speed reduction control, the engine automatically shuts down. At this time, the vehicle speed is below the threshold value Th. In the Fig. In the case shown in Figure 7, the energy supply from the lithium-ion battery 12 to the electrical loads 14a to 14c is limited because the lead-acid battery 11 has a fault. This means that the second energy supply limitation, which corresponds to the no-load reduction control, is implemented.

[0066] At time t12, it is assumed that the motor restart condition is met. Therefore, the motor, driven by the rotary device 10, restarts operation. At this time, the MOS switch 15 is held in the ON state to maintain the connected state of the lithium-ion battery 12 for the power supply to the electrical loads 14a to 14c, since the lead-acid battery 11 has a fault. When the motor restart is complete, the second power supply limit is deactivated.

[0067] Assume that the vehicle resumes driving and that the condition for automatic engine shutdown by the idle control is met at time t13. Therefore, in response to the activation of the idle control, the engine automatically shuts down. At this time, the vehicle speed is equal to or higher than the threshold Th. In the Fig. In the case shown in Figure 7, since the lead-acid battery 11 has a fault, the energy supply from the lithium-ion battery 12 to the driving-related electrical load 14a is maintained, and the energy supply to the driving-unrelated electrical loads 14b and 14c is limited. This means that the first energy supply limitation is implemented. At time t14, when the motor restart condition is met, the motor restarts operation in a state where the ON state of the MOS switch 15 is maintained, and the first energy supply limitation is deactivated.

[0068] The configuration described above provides the following advantages.

[0069] As described above, the electrical power source system is applied to a vehicle equipped with two types of batteries, including the lead-acid battery 11 and the lithium-ion battery 12. The electrical power source system includes the MOS switch 15, which is arranged between the two storage or accumulator batteries 11 and 12, as a switching device. Furthermore, the electrical power source system includes electrical loads 14a to 14c, which are arranged closer to the lead-acid battery 11 compared to the MOS switch 15 and the lithium-ion battery 12. Compared to an exemplary electrical power source system that has only one storage or accumulator battery, such as the lead-acid battery 11, the electrical power source system according to the present embodiment has a similar connection configuration of the electrical loads.Therefore, the electrical power source system with two storage or accumulator batteries according to the present embodiment can be easily configured based on the exemplary electrical power source system that has only one storage or accumulator battery, and changes to the electrical wiring can be significantly reduced. That is, the advantageous configuration can be achieved by configuring the two-battery system.

[0070] After the vehicle's power switch is turned on, the MOS switch 15 is held in the (open) OFF state during engine start. Turning on the power switch refers to a state in which electrical power is supplied to the vehicle's electrical loads, but the engine is in a deactivated state. For example, electrical power can be supplied to the vehicle's electrical loads by operating an ignition switch or a start button. In all other states, except for the engine start state, the MOS switch 15 is held in the (closed) ON state. This configuration prevents the voltage fluctuation caused by the engine start driven by the rotary mechanism 10 from being transmitted to the lead-acid battery 11.At the same time, energy can be supplied to the electrical loads 14a to 14c from both the lead-acid battery 11 and the lithium-ion battery 12. With this configuration, if a fault occurs in the lead-acid battery 11, the electrical loads 14a to 14c can be continuously supplied with energy from the lithium-ion battery 12. This configuration allows the electrical power supply to the electrical loads 14a to 14c to be carried out appropriately and continuously by the electrical power source system.

[0071] During engine start-up, if a fault occurs in the lead-acid battery 11 and the MOS switch 15 is in the OFF state, electrical energy cannot be adequately supplied from the lead-acid battery 11 to the electrical loads 14a to 14c. In the present embodiment, the MOS switch 15 is switched to the ON state during engine start-up if the lead-acid battery 11 is detected as abnormal, i.e., if any fault is detected. Even if the lead-acid battery 11 has a fault, the electrical loads 14a to 14c can be continuously and stably supplied with energy by another battery 12.

[0072] Consider the case where the engine is restarted by the rotary device 10 when the engine automatically shuts down in response to the idle reduction control or the idle speed control. The following compares the engine restart under the idle reduction control and the idle speed control. When the engine restart occurs after an automatic engine shutdown caused by the idle reduction control, the vehicle speed is essentially low or near zero. In contrast, when the engine restart occurs after an automatic engine shutdown caused by the idle speed control, the vehicle speed is proportionally higher than the vehicle speed corresponding to the idle reduction control.Therefore, it is considered that voltage fluctuations from the energy source may adversely affect vehicle operation during idle speed control compared to idle speed reduction control. Based on this consideration, in a case where the lead-acid battery 11 exhibits a fault when the engine is in a restart state and the vehicle speed is equal to or higher than a predetermined speed, only the energy supply to electrical loads unrelated to vehicle operation is limited. Thus, the energy supply limitation can be implemented appropriately, taking into account the actual vehicle driving conditions and driving safety.

[0073] In a system that uses the ISG as the rotary device 10, the rotary device 10 switches between an electrical power generation state and a motor start state (motor drive state). Therefore, the rotary device 10 cannot generate electrical power when the motor is in the restart state supported by the rotary device 10. Thus, limiting the power supply during the motor restart state is considered necessary and effective. Specifically, limiting the power supply is even more effective if the lead-acid battery 11 experiences a fault during the motor restart state.

[0074] While the disclosure has been described with reference to preferred embodiments, it is understood that the disclosure is not limited to these preferred embodiments and configurations. The disclosure is intended to cover various modifications and equivalent arrangements. Some examples are described below. While the various preferred combinations and configurations have been described, other combinations and configurations comprising more elements, fewer elements, or only a single element are likewise within the basic concept and scope of the disclosure. In the following description, the same reference numbers and symbols are used for the same or equivalent parts.

[0075] In the Fig. In the process shown in Figure 5, when the control unit 20 in S21 detects a fault in the lead-acid battery 11 and determines that the vehicle speed is equal to or higher than the threshold value Th, the power supply to the electrical loads 14b and 14c, which are not related to vehicle operation, is limited. The following configuration can be used when limiting the power supply to the electrical loads 14b and 14c that are not related to vehicle operation. The power supply limitation can have several levels set according to the vehicle speed, and the power supply limitation level can be increased with higher vehicle speeds and decreased with lower vehicle speeds.As an example of the multiple stages, the number of specific electrical loads to which the power supply is limited can be adjusted differently according to the vehicle speed.

[0076] In the Fig. In the process shown in Figure 5, the control unit 20 can omit the fault determination with respect to the lead-acid battery 11 in S21. That is, if the control unit 20 determines in S20 that the engine will automatically stop operation, the control unit 20 can be configured, regardless of the occurrence of a fault in the lead-acid battery 11, to perform the power supply limitation to the electrical loads in S23 and S24 based on the vehicle speed. Here, the first power supply limitation is performed in S23 according to the idle speed control, and the second power supply limitation is performed in S24 according to the idle speed reduction control.

[0077] In the Fig. In the process shown in Figure 5, the control unit 20 can omit the vehicle speed comparison with the threshold value Th in S22. For example, if the control unit 20 determines the automatic engine shutdown in S20 and determines the occurrence of a fault at the lead-acid battery 11 in S21, the control unit 20 can perform a power supply limitation on the electrical loads (for example, only the electrical loads that are not related to vehicle operation). If the control unit 20 determines the automatic engine shutdown in S20, but does not detect the occurrence of a fault at the lead-acid battery 11 in S21, the control unit 20 can perform no power supply limitation.

[0078] In the aforementioned embodiments, the engine automatically shuts down when the condition for automatic engine shutdown is met in response to the activation of the idle control. As a further example, the engine may not shut down automatically, even if the condition for automatic engine shutdown in response to the activation of the idle control is met.

[0079] In the aforementioned embodiments, the SMR switch 16 is arranged on the second connection path 22 between the connection point N1 of the first connection path 21 and the lithium-ion battery 12. As a further example, the SMR switch 16 can be located away from the second connection path 22.

[0080] In the aforementioned embodiments, the MOS switch 15 is switched on to ensure a power supply path to the electrical loads 14a to 14c in the two-battery system when a fault occurs in the lead-acid battery 11. As a further example, which is described in Fig. As shown in Figure 8, a bypass or shunt path L can be configured to bridge the first connection path 21, on which the MOS switch 15 is located. A diode 17 can be configured on the bypass path L as the power supply control device, such that one anode of the diode 17 is connected to the lithium-ion battery 12 and one cathode of the diode 17 is connected to the electrical loads 14a to 14c. In this configuration, if the lead-acid battery 11 experiences a fault while the MOS switch 15 is open, the power supply to the electrical loads 14a to 14c can be provided by the lithium-ion battery 12 via the bypass path L. Fig. In the configuration shown in Figure 8, during the engine restart state after idle reduction control or after idle driving control, even if the lead-acid battery 11 has a fault, the lithium-ion battery 12 can supply energy or power to the electrical loads 14a to 14c via the diode 17 installed on the bridging path L.

[0081] The in Fig. The process shown in section 4 can also be found in the [document / section]. Fig. The configuration shown in Figure 8 can be executed. In this case, if the lead-acid battery 11 has a fault, the power supply from the lithium-ion battery 12 to the electrical loads 14a to 14c can be continuously carried out by at least one of the first connection path 21, on which the MOS switch 15 is installed, and the bridging path L, on which the diode 17 is installed.

[0082] In the aforementioned embodiments, the MOS switch 15 can be held in the open state during the engine start condition, which is driven by the starter motor 13.

[0083] In the aforementioned embodiments, the control unit 20 determines the vehicle speed in S22 and limits the power supply to the electrical loads 14a to 14c in S23 and S24. As a further example, the ECU 30 connected to the control unit 20 can determine the vehicle speed and limit the electrical power supply to the electrical loads 14a to 14c. Therefore, the control unit 20 or the ECU 30 functions as an example of a vehicle speed determination unit and a power supply limiting unit.

[0084] An electrical energy source system for a vehicle comprises a lead-acid battery (11) electrically connected in parallel with a starter device (10) as a first storage battery, a second storage battery (12) electrically connected in parallel with the starter device (10), a switching device (15) arranged on an electrical path connecting the lead-acid battery (11) to the second storage battery (12), at least one electrical load (14a, 14b, 14c) electrically connected to the electrical path and located closer to the lead-acid battery (11), and a switching control unit (20) that controls the switching device to maintain a closed state, except during an engine start period in which the engine is started by the starter device (10) after a vehicle power supply has been switched on.

Claims

[1] Electrical energy source system for a vehicle, wherein the vehicle comprises a starter device (10) which is driven by electrical energy and starts an engine of the vehicle, wherein the starter device (10) is provided by an electrical energy generator, wherein the electrical energy source system comprises: a lead-acid battery (11) which is electrically connected in parallel with the starting device (10) as a first storage battery; a second storage battery (12) which is electrically connected to the starting device (10), wherein the lead-acid battery (11) and the second storage battery (12) are connected in parallel with respect to the starting device (10); a switching device (15) which is arranged on an electrical path that electrically connects the lead-acid battery (11) with the second storage battery (12) between the lead-acid battery (11) and the second storage battery (12); at least one electrical load (14a, 14b, 14c) connected to the electrical path and located closer to the lead-acid battery (11) on the electrical path compared to the second storage battery (12); and a switching control unit (20) that controls the switching device to maintain a closed state, except during an engine start period during which the engine is started by the starting device (10) after a power supply to the vehicle has been switched on, characterized by : a power supply control device (17, 24) arranged on a bypass path, wherein the bypass path bridges the switching device (15) and is connected to the electrical path connecting the lead-acid battery (11) to the second storage battery (12), wherein, when a fault is detected in the lead-acid battery (11), the power supply control device (17, 24) activates a power supply from the second storage battery (12) to the at least one electrical load (14a, 14b, 14c). [2] Electrical energy source system according to claim 1, wherein the switching control unit (20) continues to function as a fault detection unit, which determines whether a fault has occurred in the lead-acid battery (11), wherein, if the fault detection unit determines that a fault has occurred in the lead-acid battery (11), the switching control unit (20) puts the switching device (15) into the closed state during the engine start period. [3] Electrical energy source system according to claim 1 or 2, wherein the energy supply control device (17) is provided by a diode connected in parallel with the switching device (15), with a forward direction from the second storage battery (12) to the at least one electrical load (14a, 14b, 14c). [4] Electrical energy source system according to claim 2 or 3, additionally comprising: a vehicle speed determination unit that determines whether a vehicle speed is equal to or higher than a threshold value; and a power supply limiting unit that limits a power supply to the at least one electrical load (14a, 14b, 14c), wherein which includes at least one electrical load (14a, 14b, 14c), a driving-related electrical load (14a) that is related to vehicle driving, and a driving-unrelated electrical load (14b, 14c) that is not related to vehicle driving, and If a fault is detected in the lead-acid battery (11) and the vehicle speed is determined to be equal to or higher than the threshold, the power supply limiting unit limits the power supply to the non-driving-related electrical load (14b, 14c). [5] Electrical energy source system according to claim 4, wherein when a fault is detected in the lead-acid battery (11) and the vehicle speed is determined to be below the threshold, the energy supply limiting unit limits the energy supply to at least one of the driving-related electrical load (14a) and the driving-unrelated electrical load (14b, 14c). [6] Electrical energy source system according to claim 4 or 5, wherein the energy supply limiting unit sets a limiting stage of the energy supply to the driving-related electrical load (14a) or the driving-unrelated electrical load (14b, 14c) according to the vehicle speed determined by the vehicle speed determination unit. [7] Electrical energy source system according to any one of claims 1 to 6, wherein the electric energy generator used as the starting device (10) is a motor generator which has a starting function as the starting device, and the motor generator is electrically connected to the electrical path and is located closer to the lead-acid battery (11) on the electrical path compared to the switching device (15).

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