Power System

Abstract

In a power supply system, a first path (ES1) includes a first power supply (12, 14) connected to a first load (34). A second path (ES2) includes a second power supply (12, 16) connected to a second load (36). A connection route (LB) connects the first and second paths to each other at a connection point (PB). The first power supply includes a voltage generator (12) that generates an operating voltage for operating the first and second loads. The second power supply includes a power storage device (16) that is charged based on power supplied from the voltage generator. A switch circuit (24) includes a first switch (SW3) having a diode component (DA3) with an anode and a cathode directed to the power storage device and the connection route, respectively, and is configured between the connection point (PB) and the power storage device in the second path. When a charging determiner (40) determines that the power storage device is in a fully charged state, a switch state controller (40) outputs a disconnection instruction to the first switch.

Description

Technical Field

[0001] The present disclosure relates to a power supply system. Background Art

[0002] A power supply system recently used in a vehicle can control the behavior of the vehicle. However, in such a power supply system, when an abnormality occurs in a load such as an electric brake, an electric power steering device, etc. that performs a necessary function for driving the vehicle, the function is completely lost, thereby stopping the vehicle. In order to avoid a complete loss of function when such an abnormality occurs during vehicle driving, a conventional system employs a first load and a second load that perform a common function.

[0003] For example, a conventional power supply system has a first path and a second path, wherein the first path includes a first power supply connected to a first load, and the second path includes a second power supply connected to a second load. In this system, an inter-path switch is configured in a connection route connecting the first path and the second path to each other. When the controller determines that an abnormality has occurred in one of the first path and the second path, the inter-path switch is disconnected. Thus, one of the first load and the second load in the applicable one of the first path and the second path operating in a normal state continues to drive the vehicle, thereby ensuring the functions required for driving the vehicle.

[0004] In a known power supply system, the power supply of one of the first path and the second path may be composed of a voltage generator using a DC-DC converter, and the other power supply of the first path and the second path may be composed of a power storage device. With this configuration, sufficient power can continue to be supplied in each of the first path and the second path while allowing the power storage device to be properly charged. However, the power storage device is likely to be redundantly charged by receiving power supplied from the voltage generator. Summary of the invention

[0005] Therefore, the present disclosure has been made to solve the problems as described above, and an object of the present disclosure is to provide a novel power supply system including a voltage generator and a power storage device capable of suppressing or reducing overcharge of the power storage device.

[0006] Therefore, one aspect of the present disclosure provides a novel power supply system, which includes: a first path ES1, the first path includes a first power supply 12, 14 connected to a first load 34; a second path ES2, the second path includes a second power supply 12, 16 connected to a second load 36, and a connection route LB, which connects the first path and the second path to each other. The connection route is connected to the second path at a connection point PB. The first power supply includes a voltage generator 12, which generates an operating voltage that operates each of the first load and the second load. The second power supply includes a power storage device 16 that is charged based on the power supplied from the voltage generator. The power supply system also includes a switch circuit 24 configured between the connection point PB and the power storage device in the second path. The switch circuit includes a switch SW3 having a diode component DA3, and the anode and cathode of the diode component are respectively directed to the power storage device and the connection route. The power supply system further includes: a charging determiner 40 for determining whether the power storage device is in a fully charged state; and a switch state controller 40 for outputting a disconnection instruction to the switch when the charging determiner 40 determines that the power storage device is in a fully charged state.

[0007] Therefore, according to one aspect of the present disclosure, since power can be supplied mutually between the first path and the second path, power can be redundantly supplied from the first power source and the second power source to the first load and the second load. Specifically, since the first power source includes a voltage generator that generates an operating voltage that causes each of the first load and the second load to operate, and the second power source includes a power storage device that can be charged (i.e., stores charge (the same hereinafter)) based on the power supplied from the voltage generator, power is redundantly supplied to each load while allowing the power storage device to be appropriately charged.

[0008] Specifically, there may be a risk that the power storage device is overcharged based on the electric power supplied from the voltage generator.

[0009] In view of this, according to one aspect of the present disclosure, an on-off switch (i.e., a switch) having a diode component is configured between a connection point where the connection route is connected to the second path and the energy storage device. The forward direction of the diode component extends from the energy storage device to the connection route. Thus, a judgment is made as to whether the energy storage device is in a fully charged state, and if the judgment is affirmative (i.e., the energy storage device is in a fully charged state), a disconnection instruction is output to the switch and the switch is disconnected. Thus, when the energy storage device is in a fully charged state, charging is stopped, and at the same time, the energy storage device is appropriately discharged due to the diode component. As a result, the energy storage device can avoid or reduce overcharging.

[0010] According to another aspect of the present disclosure, the power supply system further includes: inter-path switches SW1 and SW2 configured in the connection route; and an abnormality determiner 40 for determining whether an abnormality has occurred in the first path. When the switch is in an off state in response to an off instruction sent from the switch state controller and the abnormality determiner determines that an abnormality has occurred in the first path, the switch state controller outputs an off instruction to the inter-path switch.

[0011] Therefore, according to another aspect of the present disclosure, since an inter-path switch is configured in the connection route connecting the first path and the second path to each other, when it is determined that an abnormality has occurred in another system, the inter-path switch can be disconnected so that the load in one system where no abnormality has occurred continues to operate. For example, when it is determined that an abnormality has occurred in the first path, the inter-path switch is disconnected. In this case, if the switch is in an off state, the power supply to the second load is interrupted, thereby possibly stopping the continued operation of the second load.

[0012] In view of this, according to another aspect of the present disclosure, even if the switch is in the off state, power can continue to be supplied from the second power supply to the second load via the diode component. Thus, even after the switch enters the off state, the second load can continue to operate.

[0013] According to another aspect of the present disclosure, the power supply system further includes: inter-path switches SW1 and SW2 configured in the connection route; and an abnormality determiner 40 for determining whether an abnormality has occurred in the first path. When the switch is in an off state in response to an off instruction sent from the switch state controller and the abnormality determiner determines that an abnormality has occurred in the first path, the switch state controller outputs an off instruction to the inter-path switch. The switch state controller also outputs an on instruction to the switch after the inter-path switch enters an off state in response to the off instruction.

[0014] Specifically, when an abnormality occurs in the first path, the inter-path switch is disconnected, and power is continuously supplied from the second power source to the second load through the diode component of the switch, and the amount of power consumption in the second power source increases due to the forward voltage of the diode component. In this case, since the remaining capacity of the power storage device included in the second power source is limited, there is a risk that the second load cannot continue to operate due to the exhaustion of the remaining capacity.

[0015] According to another aspect of the present disclosure, after the inter-path switch enters the disconnected state in response to the disconnection instruction, the switch state controller also outputs an on instruction to the switch to put the switch into the on state. Thus, the power consumption of the energy storage device caused by the forward voltage of the diode component is suppressed, and the working time period of the second load can be extended to the time after the switch enters the disconnected state.

[0016] According to another aspect of the present disclosure, the power supply system further includes an inductor unit 38 having a given inductance component ZB, the inductor unit 38 being connected in series to the inter-path switch in the connection route. The inductance component has a first given value, the first given value causing the time constant TM of the circuit formed by the second path and the connection route to have a second given value, the second given value preventing the voltage of the second load from decreasing to a lower limit of the operating voltage during the cut-off time period TS. The cut-off time period represents a time period from when the abnormality determiner determines that an abnormality has occurred in the first path to when the inter-path switch enters the disconnected state in response to a disconnection instruction sent from the switch state controller.

[0017] Specifically, when it is determined that an abnormality has occurred in the first path, the inter-path switch is disconnected, and the second load continues to operate. However, after it is determined that an abnormality has occurred, a given disconnection period is required before the inter-path switch enters the disconnected state. Therefore, the voltage of the second load in the path where no abnormality has occurred decreases from the lower limit of the operating voltage during the disconnection period, and the second load is likely to stop operating.

[0018] Therefore, in another aspect of the present disclosure, the inductor unit is connected in series to the inter-path switch in the connection route. In addition, the time constant of the circuit composed of the second path and the connection route is designed to satisfy the condition that the voltage of the second load will not drop to less than the lower limit of the operating voltage during the cut-off period. That is, even if an abnormality occurs in the first path, the power supply system will generate a transition voltage (i.e., a voltage difference) between the first path and the second path based on the transition change in the current caused by the abnormality and the inductance component of the inductor unit so as not to reduce the voltage of the second load to less than the lower limit of the operating voltage. Thus, the second load can continue to operate before and after the switch enters the disconnected state.

[0019] According to another aspect of the present disclosure, each of the first load and the second load performs at least one function required for driving the moving body.

[0020] Specifically, in a power supply system adopted by a mobile body having a first load and a second load that perform respective required functions, when an abnormality occurs in the first path, and if the second load cannot continue to work at this time, the first load and the second load stop working at the same time, thereby making it impossible for the mobile body to continue working. However, according to another aspect of the present disclosure, since the second load continues to work before and after the switch is disconnected, the mobile body can continue to work.

[0021] According to another aspect of the present disclosure, the power supply system also includes a restricted charging request determiner 40, which determines whether a restricted charging request is made to allow the storage device to be charged under restricted charging conditions. The switching circuit also includes a second switch SW4 having a diode component DA4, the anode and cathode of which point to the connection route and the storage device, respectively. The second switch SW4 is connected in series to the first switch SW3. When the restricted charging request determiner determines that a restricted charging request is made, the switch state controller outputs a connection instruction to the first switch and a disconnection instruction to the second switch. When the charging determiner determines that the storage device is in a fully charged state, the switch state controller outputs a disconnection instruction to the first switch and outputs a connection instruction to the second switch.

[0022] Specifically, usually, some switching circuits are composed of a first on-off switch (i.e., the first switch) and a second on-off switch (i.e., the second switch), and the first on-off switch and the second on-off switch are connected in series with diode components that are opposite to each other. According to another aspect of the present disclosure, by switching the state of each of the first switch and the second switch, the amount of charge in the storage device can be appropriately reduced. Specifically, when it is determined that a restricted charging request is made to allow the storage device to be charged under restricted charging conditions (i.e., based on a limited amount of charging current), the first switch is turned on and the second switch is turned off. Thus, the storage device can continue to be charged even based on the limited amount of charging current passing through the diode component included in the second switch. In addition, when it is determined that the storage device is in a fully charged state, the first switch is turned off and the second switch is turned on. Thus, the charging of the storage device can be stopped, thereby limiting the amount of charge in the storage device.

[0023] According to still another aspect of the present disclosure, when a request for increasing the operating voltage generated by the voltage generator is made, the limited charge request determiner determines that the limited charge request is made.

[0024] Specifically, in a power supply system including a voltage generator and a power storage device, it is necessary to increase the operating voltage generated by the voltage generator according to the operating state of each of the first load and the second load. As a result, when the power storage device is charged based on the increased voltage, the power storage device may sometimes be overcharged. In view of this, in another aspect of the present disclosure, when a request for increasing the operating voltage is made, it is determined that a restricted charging request for charging under restricted charging conditions is made, the first switch is turned on, and the second switch is turned off. As a result, the forward voltage of the diode component included in the second switch suppresses the increase in the voltage applied to the power storage device, thereby preventing or reducing overcharging of the power storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Thus, a more complete appreciation of the present disclosure and many of its attendant advantages may be more readily acquired by reference to the following detailed description, so that substantially the same may be better understood when considered in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 is a diagram showing an overall structure of an exemplary power supply system according to one embodiment of the present disclosure;

[0027] Figure 2 is a flowchart showing an exemplary sequence of a control process according to one embodiment of the present disclosure;

[0028] Figure 3 is a timing chart showing an exemplary control process performed when a ground fault occurs in a first path according to one embodiment of the present disclosure;

[0029] Figure 4 is a timing chart showing an exemplary control process performed when a ground fault occurs in the second path according to one embodiment of the present disclosure;

[0030] Figure 5 is a timing chart showing an exemplary control process performed when an operating voltage increase request is generated before and after a second low voltage secondary battery becomes fully charged according to one embodiment of the present disclosure;

[0031] Figure 6 is a diagram showing an overall structure of a power supply system according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views thereof, and reference Figure 1 The power supply system 100 is configured to supply power to a general load 30 and a specific load 32. The power supply system 100 includes a high-voltage secondary battery 10, a DC-DC (direct current to direct current) converter (hereinafter, simply referred to as a converter) 12, and a first low-voltage secondary battery 14. The power supply system 100 also includes a second low-voltage battery 16, a switch unit 20, and a controller 40.

[0033] The high-voltage secondary battery 10 has a rated voltage (e.g., several hundred volts) higher than the rated voltage of the first low-voltage secondary battery 14 and the second low-voltage secondary battery 16. The high-voltage secondary battery 10 can be composed of a lithium-ion secondary battery. The converter 12 converts the power supplied from the high-voltage battery 10 into power that provides an operating voltage VM (e.g., 12 volts) that enables the general load 30 and the specific load 32 to operate. The converter 12 then supplies the conversion results to the general load 30 and the specific load 32, respectively. Therefore, in the present embodiment of the present disclosure, the converter 12 is used as a voltage generator, which generates an operating voltage VM 32 that enables the specific load 32 to operate.

[0034] The general load 30 is an electric load (hereinafter, simply referred to as a load) such as an air conditioner, an audio device, a power window, etc., which is not used when controlling the driving of the vehicle as a moving body.

[0035] In contrast, the specific load 32 is a load that controls driving the vehicle to perform at least one function. For example, the specific load 32 includes an electric power steering device 50 that controls the steering of the vehicle, an electric brake 51 that provides braking force to the wheels, and a driving controller 52 that monitors the conditions around the vehicle.

[0036] Therefore, when any of these specific loads 32 is abnormal and its function is completely lost, driving control cannot be performed. Therefore, in order to prevent the complete loss of function even when an abnormality occurs, the specific load 32 is composed of a first load 34 and a second load 36 that redundantly provide the function. Specifically, the electric power steering device 50 has a first steering motor 50A and a second steering motor 50B. The electric brake 51 includes a first brake 51A and a second brake 51B. The driving controller 52 has a camera 52A and a laser radar 52B. Therefore, the first steering motor 50A, the first brake 51A and the camera 52A collectively correspond to the first load 34. In addition, the second steering motor 50B, the second brake 51B and the laser radar 52B collectively correspond to the second load 36.

[0037] Therefore, the first load 34 and the second load 36 cooperate to achieve one function. However, each of the first load 34 and the second load 36 can partially achieve the function alone. For example, the electric power steering device 50 can freely perform the steering of the vehicle using the first steering motor 50A and the second steering motor 50B. In addition, although each of the steering speed and the steering range, etc. is limited to a certain extent, these steering motors 50A, 50B can achieve the steering of the vehicle alone.

[0038] Therefore, each specific load 32 implements a function of assisting a driver who manually controls driving. In addition, each specific load 32 implements a function required for autonomous driving that autonomously controls the behavior of the vehicle, such as driving, stopping, etc. Thus, each specific load 32 may be a load that also performs at least one of the functions required for driving a vehicle.

[0039] In addition, the first load 34 is connected to the converter 12 via the route LA1 within the first path. The first low-voltage battery 14 and the general load 30 are also connected to the route LA1 within the first path. The first low-voltage battery 14 is composed of, for example, a lead-acid battery. Therefore, according to the present embodiment, the converter 12, the first low-voltage battery 14, the general load 30 and the first load 34 are connected to each other via the route LA1 within the first path, and collectively constitute the first path ES1. In addition, as shown in the figure, the route LA1 within the first path also includes an inductance component ZA1 for the first path ES1. Therefore, according to the present embodiment of the present disclosure, the converter 12 and the first low-voltage battery 14 collectively correspond to (i.e., serve as) a first power source.

[0040] In addition, the second load 36 is connected to the second low-voltage battery 16 via the route LA2 within the second path. The second low-voltage battery 16 is composed of, for example, a lithium-ion secondary battery. Therefore, according to the present embodiment, the second low-voltage battery 16 and the second load 36 are associated with each other through the route LA2 within the second path, and together constitute the second path ES2. In addition, as shown in the figure, the route LA2 within the second path includes an inductance component ZA2 for the second path ES2. Therefore, according to one embodiment of the present disclosure, the second low-voltage battery 16 is equivalent to (i.e., used as) a second power source or power storage device.

[0041] In addition, a switch unit 20 is configured in a connection route LB that connects the first path and the second path to each other. Specifically, one end of the connection route LB is connected to the first path intra-route LA1 at a connection point PA. The other end of the connection route LB is connected to the second path intra-route LA2 at a connection point PB. The switch unit 20 includes a first switch SW1 and a second switch SW2 connected in series to each other. In the switch unit 20, the first switch SW1 is configured to be closer to the first path ES1 than the second switch SW2. Therefore, according to one embodiment of the present disclosure, the first switch SW1 and the second switch SW2 are collectively equivalent to (i.e., used as) an inter-path switch.

[0042] In addition, in the present embodiment, each of the first switch SW1 and the second switch SW2 is composed of an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) (hereinafter, referred to as MOSFET). Therefore, the first parasitic diode DA1 is connected in parallel to the first switch SW1. The second parasitic diode DA2 is connected in parallel to the second switch SW2. In the present embodiment, the first switch SW1 and the second switch SW2 are connected in series so that the directions of the first parasitic diode DA1 and the second parasitic diode DA2 are opposite to each other. Specifically, the anode of the first parasitic diode DA1 is configured to be closer to the second path ES2 than its cathode, and the cathode is configured to be closer to the first path ES1 than the anode. Similarly, the anode of the second parasitic diode DA2 is configured to be closer to the first path ES1 than its cathode, and the cathode is configured to be closer to the second path ES2.

[0043] In addition, the current detector 26 is arranged in the connection route LB. The current detector 26 is arranged in the connection route LB so as to be closer to the first path ES1 than the switch unit 20. The current detector 26 detects the magnitude and direction of the inter-path current flowing through the connection route LB.

[0044] In addition, the reactor 38 is also arranged in the connection route LB, and is connected in series to the switch unit 20. The reactor 38 is arranged in the connection route LB in a manner closer to the second path ES2 than the switch unit 20. As will be described in detail later, the reactor 38 has a given inductance component ZB. Therefore, according to one embodiment of the present disclosure, the reactor 38 is equivalent to (that is, used as) an inductance portion.

[0045] In addition, the controller 40 is provided in the power supply system, and generates a first switching signal SC1 and a second switching signal SC2 based on the detection value detected by the current detector 26 to switch the states of the first switch SW1 and the second switch SW2. Then, the controller 40 outputs instructions composed of the first switching signal SC1 and the second switching signal SC2 to the first switch SW1 and the second switch SW2, respectively. The controller 40 also generates a control signal SD to control the converter 12, and outputs an instruction composed of the control signal SD to the converter 12. Then, the control signal SD switches the state of the converter 12 between the operating state and the operating stop state.

[0046] The controller 40 is also connected to an information unit 44, an IG (ignition) switch 45, and an input unit 46, and controls these devices. The information unit 44 provides information to the driver in a visual or auditory manner, and is composed of, for example, a display or a speaker installed inside the vehicle. The IG switch 45 is used as a vehicle start switch. Therefore, the controller 40 monitors the on-off state of the IG switch 45. The input unit 46 accepts various operations from the driver, such as operations of a handle, a lever, a button, etc. The operation of the pedal and the voice input device is also illustrated.

[0047] The controller 40 drives the vehicle manually and autonomously by using the specific load 32 as described above. Therefore, the controller 40 includes a well-known microcomputer composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory). The controller 40 also includes a flash memory and the like. Thus, the CPU refers to the operation program and control data stored in the ROM to realize various functions of manual driving and autonomous driving.

[0048] Here, manual driving refers to a driving method of driving and controlling a vehicle through the operation of a driver. In contrast, autonomous driving refers to a driving method of driving and controlling a vehicle based on control contents determined by the controller 40 that do not include driver operations. Specifically, autonomous driving is classified as level three or higher among level zero to level five of autonomous driving levels specified by the National Highway Traffic Safety Administration (NHTSA). Specifically, in the case of level three autonomous driving, the controller 40 can control both steering wheel operation and acceleration and deceleration based on observation of the driving environment.

[0049] In addition, the controller 40 can also perform driving assistance functions such as LKA (LaneKeeping Assistance), LCA (Lane Change Assistance), PCS (Pre-Crash Safety), etc. by using the specific load 32 as described above. Here, the driving assistance function is performed both when the driver manually drives the vehicle by using the driving assistance function and when the vehicle autonomously drives.

[0050] In addition, when the vehicle is traveling based on manual driving and autonomous driving, the controller 40 determines whether an abnormality has occurred in any one of the first path ES1 and the second path ES2. Then, when the controller 40 determines that no abnormality has occurred in any one of the paths ES1 and ES2, autonomous driving and driving assistance are performed in the vehicle by using the first load 34 and the second load 36. Thus, the first load 34 and the second load 36 cooperate with each other to achieve a function required for autonomous driving and driving assistance. In the present embodiment, the abnormality indicates a power loss abnormality such as a ground fault, a disconnection, etc.

[0051] On the contrary, when it is determined that an abnormality has occurred in either path ES1 or ES2, the first switch SW1 and the second switch SW2 are turned off, thereby electrically isolating the first path ES1 and the second path ES2 from each other. Therefore, even if an abnormality has occurred in either path ES1 or ES2, one of the loads 34 and 36 in the other path ES1 or ES2 where the abnormality has not occurred can be operated.

[0052] In addition, when it is determined that no abnormality occurs in each of the paths ES1 and ES2, power is supplied from the converter 12 to the first load 34 and the second load 36. At the same time, power is supplied from the converter 12 to both the first low-voltage battery 14 and the second low-voltage battery 16, thereby allowing the first low-voltage battery 14 and the second low-voltage battery 16 to start charging. Therefore, the power supplied from the converter 12 may sometimes cause the first low-voltage battery 14 and the second low-voltage battery 16 to be overcharged. Since the storage capacity of the second low-voltage battery 16 is smaller than the storage capacity of the first low-voltage battery 14, there is a risk of overcharging the second low-voltage battery 16.

[0053] In view of this, according to the present embodiment, in the second path ES2, the switch unit 24 is configured between the connection point PB connected to the connection route LB and the second low-voltage battery 16. Hereinafter, in order to distinguish each other, the switch unit 20 is referred to as the first switch unit 20, and the switch unit 24 is referred to as the second switch unit 24. The second switch unit 24 includes a third switch SW3 connected in parallel with the diode component DA3. Specifically, the anode of the diode component DA3 is configured to be closer to the second low-voltage battery 16 than its cathode, and the cathode is configured to be closer to the connection route LB than the anode. In other words, the third switch SW3 has a diode component DA3 configured such that its forward direction extends from the second low-voltage battery 16 to the connection route LB. Therefore, according to one embodiment of the present disclosure, the third switch SW3 is equivalent to (i.e., used as) a switch or a first switch.

[0054] Thus, it is judged whether the second low-voltage battery 16 is in a fully charged state. When it is judged that the second low-voltage battery 16 is in a fully charged state, as a control process, a disconnection instruction is output to the third switch SW3 to disconnect (i.e., open the state) the third switch SW3. Therefore, in the fully charged state of the second low-voltage battery 16, the second low-voltage battery 16 stops charging, and is allowed to discharge appropriately due to the diode component DA3. As a result, the second low-voltage battery 16 can be prevented from being overcharged.

[0055] In addition, in addition to the third switch SW3, the second switch unit 24 also includes a fourth switch SW4 connected in series to the third switch SW3. As shown in the figure, the third switch SW3 is arranged in the second switch unit 24 in a manner closer to the connection route LB than the fourth switch SW4. Therefore, in one embodiment of the present disclosure, the second switch unit 24 is equivalent to (i.e., used as) a switch circuit, and the fourth switch SW4 is equivalent to (i.e., used as) a second switch.

[0056] In addition, the third switch SW3 and the fourth switch SW4 of the present embodiment are respectively constituted by MOSFETs. Therefore, the third parasitic diode DA3 is connected in parallel to the third switch SW3 to serve as a diode component DA3. The fourth parasitic diode DA4 is also connected in parallel to the fourth switch SW4. Specifically, in the present embodiment, the third switch SW3 and the fourth switch SW4 are connected in series so that the directions of the third parasitic diode DA3 and the fourth parasitic diode DA4 are opposite to each other. More specifically, the anode of the fourth parasitic diode DA4 is configured to be closer to the connection route LB than its cathode, and the cathode is configured to be closer to the second low-voltage battery 16 than the anode.

[0057] In addition, the controller 40 generates a third switching signal SC3 and a fourth switching signal SC4 based on the charging state of the second low-voltage battery 16 to switch the states of the third switch SW3 and the fourth switch SW4, and outputs the instructions composed of the third switching signal SC3 and the fourth switching signal SC4 to the third switch SW3 and the fourth switch SW4, respectively.

[0058] Now, refer to Figure 2 An exemplary control process performed according to one embodiment of the present disclosure is described. That is, Figure 2 is a flowchart showing an exemplary control process. As shown in the figure, when the IG switch 45 is switched to the on state (i.e., closed state), the control process is repeatedly performed within a given control cycle. Here, when the IG switch 45 is switched to the on state, each of the first switch SW1 and the second switch SW2 is in the on state, and the converter 12 is in the operating state.

[0059] When the control process starts, first, in steps S10 and S11, it is determined whether an abnormality has occurred in any one of the first path ES1 and the second path ES2. Specifically, in step S10, it is determined whether an abnormality has occurred in the second path ES2. When the determination in step S10 is negative (No in step S10), it is then determined in step S11 whether an abnormality has occurred in the first path ES1. Therefore, according to one embodiment of the present disclosure, the processing of step S11 is equivalent to serving as an abnormality determiner.

[0060] In the execution of steps S10 and S11, the occurrence of an abnormality can be detected based on the magnitude and direction of the inter-path current detected by the current detector 26. For example, when a ground fault occurs in the first path ES1, the inter-path current detected by the current detector 26 flows in the direction from the second path ES2 to the first path ES1. In addition, the magnitude of the inter-path current detected by the current detector 26 exceeds the upper limit of the normal current range. In addition, for example, when a ground fault occurs in the second path ES2, the inter-path current detected by the current detector 26 flows in the opposite direction from the first path ES1 to the second path ES2. In addition, the magnitude of the inter-path current detected by the current detector 26 exceeds the upper limit of the normal current range. Therefore, according to the magnitude and direction of the inter-path current detected by the current detector 26, it is possible to identify which of the paths ES1 and ES2 causes the abnormality.

[0061] In addition, when it is determined that no abnormality occurs in each of the paths ES1 and ES2, the determination in step S11 is negative (No in step S11). In this case, it is then determined in step S12 whether the second low-voltage battery 16 is in a fully charged state. Therefore, in the present embodiment, the processing of step S12 is equivalent to (i.e., serves as) the charging state determiner mentioned in the claims.

[0062] Specifically, in step S12, the data of the remaining capacity SA (e.g., SOC (state of charge)) of the second low-voltage battery 16 is obtained via a battery monitor (not shown) and compared with a given full charge threshold Sth (e.g., 90% of SOC). When the remaining capacity SA of the second low-voltage battery 16 is greater than the full charge threshold Sth, it is determined that the second low-voltage battery 16 is in a fully charged state, so that a positive judgment is made in step S12 (yes in step S12). In this case, a disconnection command is subsequently output to the third switch SW3 in step S14, and a connection command is simultaneously output to the fourth switch SW4 in step S14, thereby completing the control process.

[0063] On the contrary, when the remaining capacity SA of the second low-voltage battery 16 is less than the full charge threshold value Sth, it is determined that the second low-voltage battery 16 is not in a fully charged state, and a negative judgment is made in step S12 (No in step S12). In this case, it is then determined in step S16 whether an operating voltage increase request for increasing the operating voltage VM generated by the converter 12 is made.

[0064] This is because, depending on the operating state of each of the first load 34 and the second load 36, the remaining capacity of the first low-voltage battery 14 may sometimes be less than a given over-discharge threshold (e.g., 10% of SOC). However, the first low-voltage battery 14 is used to supply dark current to the second path ES2 through a dark current supply route (not shown) during the deactivated state of the power supply system 100. As a result, a charging request is sometimes generated to allow the first low-voltage battery 14 to charge. As a result, when a charging request is generated for charging the first low-voltage battery 14, it is necessary to charge the first low-voltage battery 14 quickly to increase the operating voltage VM. Therefore, a request to increase the operating voltage is sometimes generated.

[0065] In this case, when a request for an increase is generated, the judgment in step S16 becomes affirmative (yes in step S16). However, in this case, when the second low-voltage battery 16 is charged based on the operating voltage VM increased according to the request for an increase in the operating voltage, the second low-voltage battery 16 may be overcharged thereby. Therefore, the second low-voltage battery 16 is charged in a manner that limits the amount of charge charged to the second low-voltage battery 16. Therefore, the request for an increase in the operating voltage is substantially equivalent to a charging request for allowing the second low-voltage battery 16 to be charged under restricted charging conditions. Thus, according to one embodiment of the present disclosure, the processing performed in step S16 is equivalent to a charge amount limit determiner.

[0066] Specifically, when the determination in step S16 is affirmative (YES in step S16 ), in step S18 , an on instruction is output to the third switch SW3 , and an off instruction is output to the fourth switch SW4 , thereby terminating the control process.

[0067] On the contrary, if the operating voltage increase request is not generated, the judgment in step S16 is negative (No in step S16). In this case, in step S20, an on instruction is output to the third switch SW3, and an on instruction is also output to the fourth switch SW4, thereby terminating the control process.

[0068] In addition, when it is determined that an abnormality has occurred in any one of the paths ES1 and ES2, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2, thereby stopping the supply of power to the system in which the abnormality has occurred. Specifically, when the judgment in step S10 is affirmative (yes in step S10), first, in step S36, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2. Subsequently, in step S38, a disconnection instruction is output to each of the third switch SW3 and the fourth switch SW4, thereby terminating the control process. As a result, the second low-voltage battery 16 stops charging and discharging, and the power supply to the second load 36 is stopped.

[0069] Furthermore, when the determination in step S11 is positive (Yes in step S11), first, in step S22, a command to switch the state of converter 12 to the operation stop state is output. Subsequently, in step S24, it is determined whether the third switch SW3 is in the off state.

[0070] Specifically, in step S24, when the third switch SW3 is in the on state, for example, in response to one of the on instructions generated in steps S18 and S20, and then it is determined that an abnormality has occurred in the first path ES1, the determination in step S24 becomes negative (No in step S24). In this case, in step S32, the disconnection instruction is then output to each of the first switch SW1 and the second switch SW2. Subsequently, in step S34, the on instruction is output to the fourth switch SW4, thereby terminating the control process. As a result, the power supply from the second low-voltage battery 16 to the second load 36 is ensured (i.e., maintained).

[0071] On the contrary, in step S24, when the third switch SW3 is turned off in response to the disconnection instruction generated in step S14 and then it is determined that an abnormality has occurred in the first path ES1, the determination in step S24 becomes positive (yes in step S24). In this case, then in step S26, it is determined whether each of the first switch SW1 and the second switch SW2 is in the disconnected state.

[0072] In step S26, when the judgment is negative (No in step S26), in step S28, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2, thereby terminating the control process. Specifically, when it is determined that an abnormality has occurred in the first path ES1 after the third switch SW3 is disconnected in response to the disconnection instruction generated in step S14, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2.

[0073] On the contrary, in step S26, when the judgment is affirmative (yes in step S26), an on instruction is output to the third switch SW3 in step S30, thereby terminating the control process. That is, after the first switch SW1 and the second switch SW2 are turned off in response to the off instruction generated in step S28, an on instruction is output to the third switch SW3. Therefore, according to one embodiment of the present disclosure, the processes performed in steps S14, S18, S20, S30, S34, and S38 collectively correspond to (i.e., function as) a switch state controller.

[0074] Next, we will refer to Figures 3 to 5 An exemplary control process is described below. Figure 3 1 shows a transition of the first voltage VA applied to the first load 34 configured in the first path ES1 when the vehicle is traveling and a ground fault occurs in the first path ES1 after the second low-voltage battery 16 is fully charged. Figure 3 Also shown is a transition of a second voltage VB applied to a portion of route LA2 within the second path between second low voltage battery 16 and second switching unit 24 when the vehicle is traveling and a ground fault occurs in first path ES1 after second low voltage battery 16 is fully charged.

[0075] Specifically, in Figure 3 , graph A shows the transition of the state of the IG switch 45. Graph B shows the transition of the on-off state of each of the first switch SW1 and the second switch SW2. Graph C also shows the transition of the on-off state of the third switch SW3. Graph D also shows the transition of the on-off state of the fourth switch SW4. In addition, graph E shows the transition of the judgment result of the ground fault. Graph F also shows the transition of the remaining capacity SA of the second low-voltage battery 16. Graph G shows the transition of the first voltage VA. Graph H shows the transition of the second voltage VB.

[0076] More specifically, in the graph H, the solid line indicates the transition of the second voltage VB caused when the reactor 38 is configured in the connection route LB according to the present embodiment. The dotted line indicates the transition of the second voltage VB of the comparative example in which the reactor 38 is not configured in the connection route LB. In addition, the double-dotted line indicates the transition of the second voltage VB that is reduced when a ground fault occurs in the first path ES1. In addition, in each of the graphs F and H, the single-dotted line indicates the transition of the application value (SA, VB) caused when the second low-voltage battery 16 is judged to be in a fully charged state but the third switch SW3 is not disconnected.

[0077] In addition, if Figure 3As shown, during the off period of the IG switch 45 to time t1 (ie, the rest state of the power supply system 100 ), the first to fourth switches SW1 to SW4 are turned off, and the state of the converter 12 is switched to the operation stop state.

[0078] When the IG switch 45 is turned on at time t0, an on command is output to each of the first to fourth switches SW1 to SW4, and another command is output to the converter 12 to switch the state of the converter 12 to the working state. Thus, at time t1, each of the first to fourth switches SW1 to SW4 is then placed in an on state, and the state of the converter 12 is switched to the working state. As a result, each of the first voltage VA and the second voltage VB rises to the working voltage VM, and the second low-voltage battery 16 starts to charge (i.e., store charge), thereby increasing its remaining capacity SA.

[0079] Subsequently, when the remaining capacity SA increases to the full charge threshold value Sth at time t2, the disconnection instruction is output to the third switch SW3, and the third switch SW3 is subsequently disconnected at time t3. That is, when the remaining capacity SA increases to the full charge threshold value Sth and it is correspondingly determined that the second low-voltage battery 16 is in a fully charged state, the connection instruction is output to the third switch SW3, thereby disconnecting the third switch SW3.

[0080] Therefore, as shown in graphs G and H, even if the operating voltage VM generated by the converter 12 is increased to the boosted voltage VX based on the request for increasing the operating voltage VM during the period from time t3 to time t4, the second voltage VB is prevented from being increased to the boosted voltage VX (see Figure 3 , single-dot line). As a result, as shown in graph F, the remaining capacity SA is prevented from exceeding the full charge threshold value Sth, and the second low-voltage battery 16 is prevented from entering an over-discharge state.

[0081] Here, during the time period from time t3 to time t4, the second low-voltage battery 16 can be discharged via the third parasitic diode DA3 of the third switch SW3. However, in the present embodiment, since power continues to be supplied from the converter 12 during the time period from time t3 to time t4, the second low-voltage battery 16 is not discharged, and the remaining capacity SA is maintained at the full charge threshold Sth.

[0082] In addition, it is determined whether a ground fault has occurred in any one of the first path ES1 and the second path ES2 during vehicle driving. When it is determined that a ground fault has not occurred in each of the paths ES1 and ES2, each of the first switch SW1 and the second switch SW2 remains in the on state. Thus, power can be supplied from the converter 12 and the first low-voltage battery 14 and the second low-voltage battery 16 to the first load 34 and the second load 36. Specifically, the converter 12 can continue to supply power even during long-term autonomous driving. At the same time, the power supply from each of the first low-voltage battery 14 and the second low-voltage battery 16 enables power supply with low voltage fluctuations.

[0083] On the contrary, when it is determined that a ground fault has occurred in either path ES1 or ES2, the state of each of the first switch SW1 and the second switch SW2 is switched to an off state as described below. Figure 3 In the control process shown, it is assumed that a ground fault occurs in the first path ES1 at time t4 after the third switch SW3 is disconnected. Therefore, at time t4, the first voltage VA and the second voltage VB begin to decrease. When the inter-path current begins to increase and it is determined at time t5 that the magnitude of the inter-path current becomes greater than the upper limit of the normal current range, it is then determined that a ground fault has occurred. Then, at time t5, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2.

[0084] Subsequently, the first switch SW1 and the second switch SW2 are disconnected at time t6. That is, based on the situation that the third switch SW3 is in the disconnected state and the ground fault occurs in the first path ES1, the disconnection instruction is output to each of the first switch SW1 and the second switch SW2, and each of these switches SW1 and SW2 is placed in the disconnected state.

[0085] In addition, in the present embodiment, when each of the first switch SW1 and the second switch SW2 is placed in the off state, the third switch SW3 is in the off state. However, the power supply from the second low-voltage battery 16 is enabled via the third parasitic diode DA3 of the third switch SW3. Therefore, after the first switch SW1 and the second switch SW2 are disconnected at time t6, the second load 36 continues to operate based on the power supplied from the second low-voltage battery 16.

[0086] Here, the time period from time t5 to time t6 is determined based on the switching speed at which each of the first switch SW1 and the second switch SW2 is switched, etc. Therefore, the time period from time t5 to time t6 is hereinafter referred to as a cut-off time period TS. That is, the cut-off time period TS is a time period from the time when the ground fault is determined to have occurred in the first path ES1 to the time when the first switch SW1 and the second switch SW2 enter the disconnected state. In addition, during the cut-off time period TS, since each of the first switch SW1 and the second switch SW2 is not placed in the disconnected state, the second voltage VB decreases. That is, during the time period from time t4 to time t6, the second voltage VB continues to decrease.

[0087] Specifically, as shown by the dotted line in the graph H, if the reactor 38 is not configured in the connection route LB, the second voltage VB decreases according to the time constant determined based on the inductance component ZA2 included in the second path ES2. In this case, since the inductance component ZA2 of the second path ES2 is relatively small, the time constant determined by the inductance component ZA2 is relatively small. Therefore, as shown in the graphs G and H, the second voltage VB decreases at substantially the same speed as the first voltage VA. At the same time, during the cut-off period TS, the first voltage VA decreases to be less than the lower limit Vth of the operating voltage VM. As a result, before the second voltage VB increases to exceed the lower limit Vth of the operating voltage VM, the operation of the second load 36 is interrupted after the cut-off period TS. Thus, when the vehicle operates autonomously and the operation is interrupted so that the function of the second load 36 is lost, since the driver cannot control the vehicle, he or she cannot ensure driving safety.

[0088] In view of this, according to the present embodiment, the reactor 38 is arranged in the connection route LB. Then, according to the time constant TM determined by the inductance component ZA2 of the second path ES2 and the inductance component ZB of the reactor 38, the inductance component ZB of the second path ES2 is disconnected during the cut-off period TS (see Figure 3 At time t7 after the first switch SW1 and the second switch SW2 are disconnected at time t6, the second load 36 continues to operate based on the power supplied from the second low-voltage battery 16.

[0089] Specifically, a given value of the inductance component ZB of the reactor 38 is pre-specified so that the time constant TM of the circuit composed of the second path ES2 and the connection route LB satisfies the condition that the voltage of the second load 36 does not drop below the lower limit Vth of the operating voltage VM during the cutoff period TS.

[0090] For a more detailed description, it is assumed hereinafter that the time period from time t4 to time t5 corresponds to the determination time period TD. That is, the determination time period TD is a time period from the time when the ground fault occurs in the first path ES1 to the time when it is determined that the ground fault has occurred in the first path ES1. It is also assumed hereinafter that the time period from time t4 to time t7 corresponds to the reduction time period TL. The reduction time period TL is a time period from the time when the ground fault occurs in the first path ES1 to the time when the voltage of the second load 36 decreases to be lower than the lower limit Vth of the operating voltage VM. Then, the given inductance component ZB of the reactor 38 makes the time constant TM determined by the inductance component ZA1 of the first path ES1 and the inductance component ZB of the reactor 38 satisfy the first equation listed below.

[0091] TL>TD+TS

[0092] (First equation)

[0093] Subsequently, at time t8, the on command is output to the third switch SW3 and the third switch SW3 is turned on (i.e., the third switch SW3 enters the on state). That is, after the first switch SW1 and the second switch SW2 are disconnected, the on command is output to the third switch SW3 and the third switch SW3 is turned on. Therefore, the route through which the power supplied from the second low-voltage battery 16 passes is switched from the route extending through the third parasitic diode DA3 of the third switch SW3 to another route extending through its switch portion. As a result, the power consumption of the second low-voltage battery 16 caused by the forward voltage of the third parasitic diode DA3 is reduced, thereby extending the operating time period of the second load 36 when a ground fault occurs in the first path ES1.

[0094] Figure 4 1 shows the transition of the first voltage VA and the second voltage VB when the vehicle is traveling and a ground fault occurs in the second path ES2 after the second low-voltage battery 16 has been fully charged (ie, fully charged). Figure 4 Figures A to H are respectively Figure 3 Graphs A to H of are substantially the same, and therefore will not be described again. Figure 4 In the process performed before time t3, Figure 3 The described processing is basically the same, so it will not be described again.

[0095] First, in Figure 4In the control process of , it is assumed that a ground fault occurs in the second path ES2 at time t11 after the third switch SW3 is disconnected. Therefore, at time t11, the first voltage VA and the second voltage VB begin to decrease. Subsequently, when the inter-path current begins to increase and it is determined at time t12 that the magnitude of the inter-path current increases to a value greater than the upper limit of the normal current range, it is determined that a ground fault has occurred. Then, at time t12, a disconnection instruction is output to each of the first switch SW1 and the second switch SW2.

[0096] Subsequently, the first switch SW1 and the second switch SW2 are turned off (i.e., placed in an off state) at time t13. Then, in the present embodiment, after the cut-off period TS has elapsed, the first voltage VA is controlled to decrease to a level lower than the lower limit Vth of the operating voltage VM according to the time constant TM determined by the inductance component ZA1 of the first path ES1 and the inductance component ZB of the reactor 38. Thus, even if a ground fault occurs in the second path ES2, the first voltage VA is maintained at a level higher than the lower limit Vth of the operating voltage VM, so that the first load 34 continues to operate by receiving power from the converter 12 and the first low-voltage battery 14.

[0097] Subsequently, a disconnection instruction is output to the fourth switch SW4, thereby disconnecting the fourth switch SW4 at time t14. As a result, the power supply from the second low-voltage battery 16 is completely cut off by the third switch SW3 and the fourth switch SW4, so that the parasitic diodes DA3 and DA4 point in opposite directions to each other. As a result, the remaining capacity SA stops decreasing at time t14, and the second voltage VB increases to a level equivalent to the remaining capacity SA.

[0098] Figure 5 1 shows the transition of the first voltage VA and the second voltage VB when the vehicle is traveling and it is determined that an operating voltage increase request is generated before and after the second low-voltage battery 16 has been fully charged (ie, fully charged). Figure 5 In FIG. 1 , graph E shows the transition of the judgment on whether a request for raising the operating voltage is generated. That is, in graph E, a mark on indicates a state in which a request for raising the operating voltage is judged to be generated. A mark off indicates a state in which a request for raising the operating voltage is judged not to be generated. Figure 5 Figures A to D and F to H are respectively Figure 3 Graphs A to D and F to H of FIG. 1 are substantially the same, and thus the same description will not be repeated.

[0099] In addition, Figure 5In the graph H of FIG. 1 , the single-dotted chain line indicates the transition of the second voltage VB caused when the fourth switch SW4 is not disconnected even if it is determined that the operating voltage increase request is generated. In addition, in each of the graphs F and H, the double-dotted chain line indicates the transition of each application value caused when the third switch SW3 is not disconnected even if it is determined that the second low-voltage battery 16 is fully charged (i.e., fully charged).

[0100] In addition, if Figure 5 As shown, when the state of the IG switch 45 is switched to the on state, the remaining remaining capacity SA is less than Figure 3 and Figure 4 Therefore, the time period from time t1 to time t2 extends longer than Figure 3 and Figure 4 Each of the time periods shown in Figure 5 Since the processing performed before time t1 is the same as the reference Figure 3 The processing described above is basically the same, so its description is omitted.

[0101] Specifically, Figure 5 As shown, when the first switch SW1 to the fourth switch SW4 are turned on and the state of the converter 12 is switched to the working state at time t1, each of the first voltage VA and the second voltage VB rises to the working voltage VM. At the same time, the second low-voltage battery 16 starts to charge (i.e., acquires charge), thereby increasing the remaining capacity SA. Here, during the time period from time t1 to time t22, the remaining capacity SA increases at a first increase rate θ1 as time passes.

[0102] In addition, Figure 5 In the exemplary control process of , it is determined that the operating voltage increase request is generated at time t21 before time t2. Therefore, a cut-off instruction is output to the fourth switch SW4 at time t21, and then the fourth switch SW4 is disconnected at time t22. As a result, the second low-voltage battery 16 is charged (i.e., charges are acquired) via the fourth parasitic diode DA4 of the fourth switch SW4.

[0103] Therefore, when the second low-voltage battery 16 is charged (i.e., acquires charge) via the fourth parasitic diode DA4 in this manner, even if the operating voltage VM rises to the boosted voltage VX after time t22, the forward voltage of the fourth parasitic diode DA4 prevents the second voltage VB from rising to the boosted voltage VX (see Figure 5The single-dotted dashed line shown in the graph H of ). Then, the second low-voltage battery 16 continues to be charged by acquiring a limited amount of charge. Here, the charge amount is equal to the amount of the charging current. Therefore, the charge amount in the second low-voltage battery 16 is reduced to be less than the charge amount acquired via the switch portion of the fourth switch SW4, and thereby the remaining capacity SA increases at a second increase rate θ2 that is less than the first increase rate θ1.

[0104] Then, when it is determined that the operating voltage increase request has disappeared at time t23, the on command is now output to the fourth switch SW4, so that the fourth switch SW4 is then turned on at time t24. As a result, the charge amount in the second low-voltage battery 16 increases.

[0105] Then, when the remaining capacity SA increases to the full charge threshold value Sth at time t2, the on command is output to the third switch SW3, so that the third switch SW3 is then turned off at time t3. Figure 5 As shown in the graphs G and H of FIG. 1 , even if the operating voltage VM is increased to the increased voltage VX based on the operating voltage increase request after time t3, the second voltage VB is prevented from being increased to the increased voltage VX (see FIG. 1 ). Figure 5 That is, in the second low-voltage battery 16, the charge amount is limited by stopping the charging.

[0106] As described above, according to one embodiment of the present disclosure, the advantages described below can be obtained.

[0107] First, in one embodiment of the present disclosure, the first path ES1 and the second path ES2 are connected to each other via a connection route LB to perform mutual power supply between the two. That is, sufficient power can be supplied to the first load 34 and the second load 36 through the converter 12 and the first low-voltage battery 14 and the second low-voltage battery 16. Specifically, the power supply includes: a converter 12 that generates an operating voltage VM that enables the first load 34 and the second load 36 to operate; and a first low-voltage battery 14 and a second low-voltage battery 16 that can be charged by receiving power from the converter 12. As a result, the first low-voltage battery 14 and the second low-voltage battery 16 can be appropriately charged while providing sufficient power to each of the loads 34 and 36.

[0108] In addition to the configuration described above, the present embodiment further includes a third switch SW3 having a third parasitic diode DA3 disposed between a connection point PB connected to the connection route LB and the second low-voltage battery 16 in the second path ES2. The third parasitic diode DA3 is configured to extend from the second low-voltage battery 16 to the connection route LB in the forward direction. Then, a judgment is made as to whether the second low-voltage battery 16 is in a fully charged state. When it is determined that the second low-voltage battery 16 is in a fully charged state, a disconnection instruction is output to the third switch SW3 to disconnect the third switch SW3. As a result, the second low-voltage battery 16 in a fully charged state stops charging, and at the same time discharges appropriately due to the third parasitic diode DA3. As a result, overcharging of the second low-voltage battery 16 can be prevented.

[0109] In another embodiment of the present disclosure, the first switch SW1 and the second switch SW2 are configured in the connection route LB. Therefore, when it is determined that an abnormality has occurred in the first path ES1, the first switch SW1 and the second switch SW2 are disconnected, and the second load 36 in the second path ES2 where no abnormality has occurred continues to operate. However, in the present embodiment, even if the third switch SW3 is in an off state when the first switch SW1 and the second switch SW2 are disconnected, power can be supplied from the second low-voltage battery 16 to the second load 36 via the third parasitic diode DA3. Thus, even after the first switch SW1 and the second switch SW2 are disconnected, the second load 36 can continue to operate.

[0110] In another embodiment of the present disclosure, when the third switch SW3 is in an off state when the first switch SW1 and the second switch SW2 are turned off, after the first switch SW1 and the second switch SW2 are turned off, a turn-on instruction is further output to the third switch SW3 to turn on the third switch SW3. Thus, the power consumption in the second low-voltage battery 16 caused by the forward voltage of the third parasitic diode DA3 is reduced, so that the second load 36 can continue to operate for a longer time even after the first switch SW1 and the second switch SW2 are turned off.

[0111] In yet another embodiment of the present disclosure, the inductance section 38 is connected in series to the first switch SW1 and the second switch SW2 in the connection route LB. Then, the value of the time constant TM of the circuit composed of the second path ES2 and the connection route LB is determined based on the inductance component ZB of the inductance section 38 so that the value does not allow the voltage of the second load 36 to decrease to less than the lower limit Vth of the operating voltage VM during the cut-off period TS. That is, even if an abnormality occurs in the first path ES1, the transient change of the current generated by the abnormality and the inductance component ZB of the inductance section 38 jointly generate a transient voltage difference between these paths to prevent the voltage of the second load 36 from decreasing to less than the lower limit Vth of the operating voltage VM. Thus, before and after each of the first switch SW1 and the second switch SW2 enters the disconnected state, the second load 36 can continue to operate.

[0112] Furthermore, in the power supply system 100 applied to a car having the first load 34 and the second load 36 that perform functions required for driving the car, if the second load 36 cannot continue to operate when an abnormality occurs in the first path ES1, the operations of the first load 34 and the second load 36 stop, thereby causing interruption of its driving. In view of this, according to the present embodiment, before and after the first switch SW1 and the second switch SW2 are turned off, the second load 36 continues to operate, so that the car can continue to operate appropriately.

[0113] In another embodiment of the present disclosure, the third switch SW3 and the fourth switch SW4 are connected in series with each other in the second switch unit 24, so that the directions of the parasitic diodes DA3 and DA4 are opposite to each other. Therefore, by switching the states of the third switch SW3 and the fourth switch SW4, the amount of charge in the second low-voltage battery 16 can be appropriately limited.

[0114] More specifically, when it is determined that a request for raising is made, the third switch SW3 is turned on, and the fourth switch SW4 is turned off. Thus, since it is charged via the third parasitic diode DA3, the second low-voltage battery 16 can continue to be charged by limiting the amount of charge. In addition, when it is determined that the second low-voltage battery 16 is in a fully charged state, the third switch SW3 is turned off, and the fourth switch SW4 is turned on. Thus, the second low-voltage battery 16 stops charging, thereby limiting the amount of charge in the second low-voltage battery 16.

[0115] That is, in the power supply system 100 including the converter 12 and the second low-voltage battery 16, it is necessary to increase the operating voltage VM generated by the converter 12 according to, for example, the operating state of the first load 34 and the second load 36. In this case, when the second low-voltage battery 16 is charged based on the boosted voltage VX, the second low-voltage battery 16 may be overcharged. Therefore, in this embodiment of the present disclosure, when a boost request is made to boost the operating voltage VM, the third switch SW3 is turned on and the fourth switch SW4 is turned off. As a result, the forward voltage of the fourth parasitic diode DA4 of the fourth switch SW4 prevents the second voltage VB applied to the second low-voltage battery 16 from increasing, thereby enabling overcharging in the second low-voltage battery 16 to be suppressed.

[0116] The present disclosure is not limited to the embodiments described above, and may include various modifications thereof as described hereinafter.

[0117] First, the moving body is not limited to a vehicle, and may be, for example, a ship or an aircraft.

[0118] Furthermore, each of the loads 34 , 36 may be, for example, a device as described below.

[0119] Specifically, each of the loads 34 and 36 can be a drive motor and a drive circuit that drives the drive motor to provide driving force to the engine together. In this case, each of the first load 34 and the second load 36 includes, for example, a corresponding three-phase permanent magnet synchronous motor and a three-phase inverter.

[0120] Furthermore, each of the loads 34, 36 may be an anti-lock brake that prevents wheels from locking during braking. In this case, each of the first and second loads 34, 36 includes, for example, an ABS (Anti-skid Braking System) actuator that can individually regulate hydraulic brake pressure during braking.

[0121] In addition, each of the loads 34, 36 may be a cruise controller that detects a preceding vehicle traveling ahead of the own vehicle and, when the preceding vehicle is detected, maintains a constant vehicle gap with the preceding vehicle. The cruise controller may be of a type that causes the own vehicle to travel at a given vehicle speed when the preceding vehicle is no longer detected. In this case, each of the first load 34 and the second load 36 may include, for example, a millimeter wave radar.

[0122] Furthermore, the loads 34 , 36 are not necessarily a combination of identical or similar devices, and may be another combination implemented by different types of devices having substantially the same functions.

[0123] Furthermore, the voltage generator is not limited to the converter 12 and may be, for example, an alternator.

[0124] Furthermore, the power storage device is not limited to a lithium-ion storage battery, and may be a lead-acid battery or a nickel metal hydride storage battery.

[0125] In addition, the third switch SW3 and the fourth switch SW4 are not limited to MOSFETs, and may be, for example, IGBTs (insulated gate bipolar transistors). The first switch SW1 and the second switch SW2 may also be IGBTs. In this case, since no parasitic diode is used in the IGBT, it is necessary to additionally provide corresponding freewheeling diodes equivalent to the third parasitic diode DA3 and the fourth parasitic diode DA4.

[0126] In addition, the inductance portion configured in the connection route LB is not limited to the reactor 38. That is, the connection route LB may be extended. In this case, the reactor 38 is no longer required, and the inductance portion is constituted by the extended portion of the connection route LB. Therefore, the inductance component is equivalent to the inductance component of the extended portion.

[0127] In addition, the charging request is not limited to the operating voltage increase request, and may be a charging request generated when the second low-voltage battery 16 is charged and the remaining capacity SA is close to the full charge threshold Sth. In addition, a charging request may be generated when the voltage fluctuation width of the operating voltage VM generated by the converter 12 exceeds a given level.

[0128] In the above-mentioned embodiment, as an example, the third switch SW3 and the fourth switch SW4 are configured in the second switch unit 24, but it is not limited thereto. Figure 6 As shown, the fourth switch SW4 does not necessarily need to be set. In this case, Figure 2 In the control process, each of steps S16, S20, and S34 is not executed, and in each of steps S14, S18, and S38, only the instruction is output to the third switch SW3.

[0129] In addition, in the above-described embodiment, as an example, a single connection route LB is configured, but the present disclosure is not limited thereto. That is, two connection routes LB that respectively connect the paths to each other may be configured. In this case, the two connection routes LB and the first intra-path route LA1 and the second intra-path route LA2 may be connected to each other in a ring state.

[0130] In addition, in the above-described embodiment, as an example, the power supply system 100 is applied to a vehicle that is manually driven and autonomously driven, but the present disclosure is not limited thereto. That is, the power supply system 100 may be applied only to a vehicle such as a fully autonomous vehicle for autonomous driving. Similarly, the power supply system 100 may be applied only to a vehicle that can only be manually driven.

[0131] Specifically, when the power supply system 100 is applied to a vehicle that travels only based on autonomous driving, for example, and an abnormality occurs in one of the paths ES1, ES2, the autonomous driving process stops the vehicle immediately or stops the vehicle after moving the vehicle to a safe place by using one of the loads 34, 36 that can be applied in the paths ES1, ES2 in which no abnormality occurs.

[0132] In addition, in the above-described embodiment, as an example, when it is determined that an abnormality occurs in one of the paths ES1 and ES2, the power supply to the applicable one of the paths ES1 and ES2 where the abnormality occurs is stopped. However, the present disclosure is not limited thereto, and the power supply to the one of the paths ES1 and ES2 where the abnormality occurs may continue at a reduced amount.

[0133] In addition, the detection method for detecting abnormality is not limited to the above-mentioned detection method for detecting abnormality based on current. For example, abnormality may be detected based on voltage.

Claims

1. A power supply system, comprising: a first path including a first power source connected to a first load; a second path including a second power source connected to a second load; as well as a connecting route connecting the first path and the second path to each other, the connecting route being connected to the second path at a connecting point, an inter-path switch as a second switch being arranged in the connecting route, The first power supply includes a voltage generator, the voltage generator generates an operating voltage for operating each of the first load and the second load, The second power supply includes a power storage device charged based on the power supplied from the voltage generator, In the second path, a switch circuit is arranged between the connection point and the power storage device. The switch circuit includes a first switch having a diode component, an anode and a cathode of the diode component pointing to the power storage device and the connection route, respectively; The power supply system further comprises: a charging determiner for determining whether the power storage device is in a fully charged state; a switch state controller that outputs a disconnection instruction to the first switch when the charge determiner determines that the power storage device is in the fully charged state; and an abnormality determiner, the abnormality determiner determines whether an abnormality occurs in the first path, When the first switch is in the disconnected state in response to the disconnection instruction sent from the switch state controller and the abnormality determiner determines that an abnormality has occurred in the first path, the switch state controller outputs a disconnection instruction to the inter-path switch. After the inter-path switch enters an off state in response to the off instruction and the off state continues, the switch state controller outputs an on instruction to the first switch.

2. The power supply system according to claim 1, characterized in that: further comprising an inductor having a given inductance component, the inductor being connected in series to the inter-path switch in the connection route, wherein the inductance component has a first given value, the first given value causes a time constant of a circuit composed of the second path and the connection route to have a second given value, and the second given value prevents the voltage of the second load from decreasing to a lower limit of an operating voltage that operates the second load during a cut-off period, The disconnection time period indicates a time period from when the abnormality determiner determines that an abnormality has occurred in the first path to when the inter-path switch enters a disconnected state in response to a second disconnection instruction sent from the switch state controller.

3. The power supply system according to claim 2, characterized in that: Each of the first load and the second load performs at least one function required for driving a moving body.

4. A power supply system, comprising: a first path including a first power source connected to a first load; a second path including a second power source connected to a second load; as well as a connecting route that connects the first path and the second path to each other, the connecting route being connected to the second path at a connecting point, The first power supply includes a voltage generator, the voltage generator generates an operating voltage for operating each of the first load and the second load, The second power supply includes a power storage device charged based on the power supplied from the voltage generator, In the second path, a switch circuit is arranged between the connection point and the power storage device. The switch circuit includes: a first switch having a diode component, an anode and a cathode of the diode component pointing to the power storage device and the connection route, respectively; and a second switch having a diode component, an anode and a cathode of the diode component pointing to the connection route and the power storage device, respectively, and the second switch is connected in series to the first switch, Wherein, the power supply system further includes: a charging determiner for determining whether the power storage device is in a fully charged state; a switch state controller that outputs a disconnection instruction to the first switch when the charge determiner determines that the power storage device is in the fully charged state; and a charging request determiner for determining whether to make a charging request for increasing the operating voltage when the charging determiner determines that the power storage device is not in a fully charged state, When the charge request determiner determines that the charge request is made, the switch state controller outputs an on command to the first switch and outputs an off command to the second switch, When the charging determiner determines that the power storage device is in a fully charged state, the switch state controller outputs an off command to the first switch and outputs an on command to the second switch.

5. The power supply system according to claim 4, characterized in that: The charge request determiner determines that the charge request is made when a step-up request for stepping up the operating voltage generated by the voltage generator is made.

Images