Power supply control device and power supply control method

Abstract

To provide a power supply controller and a power supply control method which can supply power to a load from a sub-power supply while suppressing power loss of the sub-power supply for a period when an ignition switch is turned off.SOLUTION: A power supply controller in accordance with an embodiment comprises a sub-power supply, a first path, a second path and a control part. The sub-power supply has an output voltage lower than an output voltage of a main power supply and can supply power to a load group operating for a period when an ignition switch of a vehicle is turned off. The first path boosts an output voltage of the sub-power supply through a DC / DC converter and supplies power to the load group. The second path supplies the output voltage of the sub-power supply to the load group through the switch. For a period when the ignition switch is turned off, the control part selects the first path when supplying power to a high-voltage load operating with a voltage higher than the output voltage of the sub-power supply among the load group, and selects the second path when supplying power to a low-voltage load operating with the output voltage of the sub-power supply.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed embodiments relate to a power supply control device and a power supply control method. [Background technology]

[0002] There is a power supply control device that supplies power to a load from a main power supply while the ignition switch of a vehicle is on, and when the load is operated while the ignition switch is off, supplies power to the load from a secondary power supply that has a lower output voltage than the main power supply.When supplying power from the secondary power supply, the power supply control device, for example, boosts the output voltage of the secondary power supply using a DC-DC converter and supplies power to the load (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-57179 Summary of the Invention [Problem to be solved by the invention]

[0004] However, some loads operated while the ignition switch is off can be operated with the output voltage of the secondary power supply, which has a lower output voltage than the main power supply. In this case, if the power supply control device boosts the output voltage of the secondary power supply to supply power to the load, power loss occurs in the DC-DC converter.

[0005] One aspect of the embodiment has been made in consideration of the above, and aims to provide a power supply control device and a power supply control method that can supply power from a secondary power supply to a load while suppressing power loss in the secondary power supply during the period when the ignition switch is off. [Means for solving the problem]

[0006] A power supply control device according to one aspect of the embodiment includes a secondary power supply, a first path, a second path, and a control unit. The secondary power supply has an output voltage lower than the output voltage of a main power supply and is capable of supplying power to a group of loads that operate while a vehicle ignition switch is off. The first path boosts the output voltage of the secondary power supply via a DC-DC converter and supplies power to the group of loads. The second path supplies the output voltage of the secondary power supply to the group of loads via a switch. The control unit selects the first path when supplying power to high-voltage loads that operate at a voltage higher than the output voltage of the secondary power supply among the group of loads while the ignition switch is off, and selects the second path when supplying power to low-voltage loads that operate at the output voltage of the secondary power supply. [Effects of the Invention]

[0007] A power supply control device and a power supply control method according to an aspect of the embodiment provide an advantage in that, while an ignition switch is off, power loss in the secondary power supply is suppressed and power can be supplied from the secondary power supply to a load. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of the configuration of a power supply control device according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of a high-voltage load according to the embodiment. [Figure 3] FIG. 3 is an explanatory diagram showing an example of a low-pressure load according to the embodiment. [Figure 4] FIG. 4 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 6] FIG. 6 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 7] FIG. 7 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of processing executed by the control unit of the power supply control device according to the embodiment while the IG is on. [Figure 11] FIG. 11 is a flowchart illustrating an example of processing executed by the control unit of the power supply control device according to the embodiment while the IG is off. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a power supply control device and a power supply control method will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. The power supply control device according to the embodiments is a device that controls the power supply to a plurality of electrical loads mounted on a vehicle.

[0010] [1. Configuration example of power supply control device 1] 1 is an explanatory diagram showing an example of the configuration of a power supply control device 1 according to an embodiment. As shown in Fig. 1, the power supply control device 1 is connected to a main power supply 10, a DC-DC converter (hereinafter referred to as "DCDC 11"), a vehicle 12, a plurality of high-voltage loads 101, and a plurality of low-voltage loads 102.

[0011] When the ignition switch (hereinafter referred to as "IG") of the vehicle 12 is turned on, the vehicle 12 outputs an IG-on signal indicating this to the power supply control device 1 via the IG signal input line 13. When the IG is turned off, the vehicle 12 outputs an IG-off signal indicating this to the power supply control device 1 via the IG signal input line 13.

[0012] The main power supply 10 is an in-vehicle battery, for example, a lead battery. The main power supply 10 may be any secondary battery other than a lead battery. Here, the description will be given assuming that the output voltage of the main power supply 10 is 12V to 16V.

[0013] The DCDC 11 is a generator that converts the rotational energy of the engine into electrical energy to generate electricity when the vehicle 12 is an engine vehicle. When the vehicle 12 is an electric vehicle or a hybrid vehicle, the DCDC 11 is a power conversion device that steps down the output voltage of a high-voltage battery (not shown) that supplies power to a motor that drives the vehicle, and charges the main power supply 10 or a secondary power supply 20 (described later).

[0014] The plurality of high-voltage loads 101 are a group of loads that operate at a voltage higher than the output voltage of a secondary power supply 20, which will be described later. The plurality of low-voltage loads 102 are a group of loads that operate at the output voltage of a secondary power supply 20, which will be described later.

[0015] Here, examples of the high-voltage load 101 and the low-voltage load 102 will be described with reference to Figures 2 and 3. Figure 2 is an explanatory diagram showing an example of the high-voltage load 101 according to an embodiment. Figure 3 is an explanatory diagram showing an example of the low-voltage load 102 according to an embodiment.

[0016] 2, the high-voltage loads 101 include high-voltage loads 101 for driving the vehicle 12 and high-voltage loads 101 for non-driving purposes. The high-voltage loads 101 for driving also include high-voltage loads 101 that may be used while the vehicle is parked, that is, while the IG is off, and high-voltage loads 101 that are only used when the vehicle is driving and are unlikely to be used while the vehicle is parked.

[0017] Among the high-voltage loads 101 for driving, those that may be used while the vehicle is parked include, for example, headlights, taillights, and a horn. Among the high-voltage loads 101 for driving, those that may not be used while the vehicle is parked, i.e., those that are used exclusively while driving include, for example, a power steering device, a shift-by-wire device, and an engine control ECU (Electronic Control Unit).

[0018] Among the non-driving high voltage loads 101, high voltage loads 101 that may be used while the vehicle is parked include, for example, an audio device, a repro (reprogramming) device, and a battery monitoring ECU.

[0019] Here, a case will be described in which, among the non-driving high voltage loads 101, there is no high voltage load 101 that is unlikely to be used while the vehicle is parked, but the vehicle 12 may be equipped with high voltage loads 101 that are unlikely to be used while the vehicle is parked. All of these high voltage loads 101 operate on a voltage of 12V to 16V, which is the output voltage of the main power supply 10. Furthermore, the high voltage loads 101 that are likely to be used while the vehicle is parked are also used while the vehicle is driving.

[0020] 3, the low-voltage loads 102 include low-voltage loads 102 for driving the vehicle 12 and low-voltage loads 102 for non-driving purposes. Among the low-voltage loads 102 for driving, low-voltage loads 102 that may be used while the vehicle is parked include, for example, a drive recorder and an impact detection sensor. Among the low-voltage loads 102 for non-driving purposes, low-voltage loads 102 that may be used while the vehicle is parked include, for example, a USB (registered trademark) power supply device, a communication device, and an immobilizer.

[0021] Although the following description will be given of a case where there is no low-pressure load 102 that is likely to be used while parked, among the low-pressure loads 102 for driving or non-driving, the vehicle 12 may be equipped with a low-pressure load 102 that is likely to be used while parked. Also, the low-pressure load 102 that is likely to be used while parked is also used while driving.

[0022] All of these low-voltage loads 102 operate at a voltage lower than 12 V, which is the minimum output voltage of the main power supply 10. For example, the low-voltage loads 102 operate at the output voltage of the secondary power supply 20, which will be described later, and which has a lower output voltage than the main power supply 10. However, the rated voltage of the low-voltage loads 102 is set to be equal to or higher than the voltage of the main power supply 10, and so they can operate at the voltage of the main power supply 10, although this will result in increased heat loss.

[0023] Returning to the explanation of Figure 1, the power supply control device 1 includes a first system 110 that supplies power from the main power supply 10 to the high-voltage load 101, a secondary power supply 20, a second system 120 that supplies power from the secondary power supply 20 to the high-voltage load 101 and the low-voltage load 102, and a control unit 3.

[0024] The auxiliary power supply 20 is a backup power supply that supplies power to the high-voltage load 101 in place of the main power supply 10 in the event of a failure of the first system 110. The auxiliary power supply 20 has an output voltage lower than the output voltage of the main power supply 10, and is a power supply that can supply power to the load group of the high-voltage load 101 and the low-voltage load 102 that operate while the IG of the vehicle 12 is off.

[0025] The auxiliary power supply 20 is, for example, a lithium ion battery. However, the auxiliary power supply 20 may be any secondary battery other than a lithium ion battery. In this description, the output voltage of the auxiliary power supply 20 is assumed to be 10 V, which is lower than the output voltage of the main power supply 10.

[0026] Furthermore, the power supply control device 1 includes an inter-system switch 40, first to eighth switches 41 to 48, diodes 51 and 52, current sensors 53, 54, 55 and 56, and a DC-DC converter (hereinafter referred to as "DCDC 21").

[0027] The inter-system switch 40 is a switch that can connect and disconnect the first system 110 and the second system 120. The first switch 41 is a switch that can connect and disconnect the main power supply 10 and the first system 110. The inter-system switch 40 may be a bidirectional DC-DC converter that can step up and down.

[0028] The second switch 42 is a switch that can connect and disconnect the secondary power supply 20 and the second system 120. The third switch 43 is a switch that can connect and disconnect the first system 110 and a power supply input line 130 that supplies power to the high-voltage load 101 and the low-voltage load 102. The fourth switch 44 is a switch that can connect and disconnect the power supply input line 130 and the second system 120.

[0029] The fifth switch 45 and the sixth switch 46 are load switches that can connect and disconnect the power supply input line 130 to and from each high-voltage load 101. The seventh switch 47 and the eighth switch 48 are load switches that can connect and disconnect the power supply input line 130 to and from each low-voltage load 102.

[0030] The diode 51 is connected between the third switch 43 and the power supply input line 130. The diode 51 has an anode connected to the third switch 43 and a cathode connected to the power supply input line 130. The diode 52 is connected between the fourth switch 44 and the power supply input line 130. The diode 52 has an anode connected to the fourth switch 44 and a cathode connected to the power supply input line 130.

[0031] The current sensors 53 and 54 detect the current flowing from the power supply input line 130 to each high-voltage load 101 and output the detection results to the control unit 3. The current sensors 55 and 56 detect the current flowing from the power supply input line 130 to each low-voltage load 102 and output the detection results to the control unit 3.

[0032] The DCDC 21 is connected between the secondary power supply 20 and the second system 120 in parallel with the second switch 42. The DCDC 21 has a function of boosting the output voltage of the secondary power supply 20 to a voltage equivalent to the output voltage of the main power supply 10 and outputting the boosted output voltage to the second system 120, and a function of lowering the output voltage of the main power supply 10 to a voltage equivalent to the charging voltage of the secondary power supply 20 and outputting the boosted output voltage to the secondary power supply 20.

[0033] The control unit 3 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various circuits. The control unit 3 controls the operations of the inter-system switch 40, the first to eighth switches 41 to 48, and the DCDC 21 by the CPU executing a program stored in the ROM using the RAM as a work area, thereby controlling the power supply to the high-voltage load 101 and the low-voltage load 102.

[0034] Note that some or all of the functions of the control unit 3 may be configured using hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0035] The power supply control device 1 also includes a first voltage sensor 61 and a second voltage sensor 62. The first voltage sensor 61 detects the voltage of the first system 110 and outputs the detection result to the control unit 3. The second voltage sensor 62 detects the voltage of the second system 120 and outputs the detection result to the control unit 3.

[0036] [2. Example of operation of power supply control device 1] Next, an example of the operation of the power supply control device 1 will be described with reference to Figures 4 to 9. Figures 4 to 9 are explanatory diagrams showing an example of the operation of the power supply control device 1 according to an embodiment. In Figures 4 to 9, the power supply line to which the output voltage of the main power supply 10 is supplied is indicated by a thick solid line, and the power supply line to which the output voltage of the secondary power supply 20 is supplied is indicated by a thick dotted line.

[0037] [2.1. Example of operation of the Power Supply Control Device 1 while the IG is on] First, an example of the operation of the power supply control device 1 while the IG is on will be described with reference to Figures 4 to 6. As shown in Figure 4, when an IG on signal is input from the vehicle 12, the control unit 3 turns on the first switch 41 and the third to eighth switches 43 to 48 and turns off the inter-system switch 40 and the second switch 42, and supplies power from the main power supply 10 to the high-voltage load 101 and the low-voltage load 102.

[0038] Thereafter, the control unit 3 monitors the amount of stored power in the secondary power supply 20, which is acquired from the secondary power supply 20 via the monitoring line 22, and when the amount of stored power in the secondary power supply 20 falls below a predetermined amount of stored power, the control unit 3 charges the secondary power supply 20 as shown in Fig. 5. The predetermined amount of stored power is, for example, the amount of stored power when the SOC (State Of Charge) of the secondary power supply 20 is 80%.

[0039] Specifically, when the amount of electricity stored in the secondary power supply 20 falls below a predetermined amount while the IG is on, the control unit 3 turns on the system switch 40, causes the DCDC 21 to perform a step-down operation, and steps down the output voltage of the main power supply 10 via the DCDC 21 to supply power to the secondary power supply 20 and charge the secondary power supply 20.

[0040] As a result, when the amount of stored power in the secondary power supply 20 falls below a predetermined amount while the IG is on, the power supply control device 1 can charge the secondary power supply 20 while continuing to supply power from the main power supply 10 to the high-voltage load 101. When the amount of stored power in the secondary power supply 20 recovers to or exceeds the predetermined amount, the control unit 3 turns off the system switch 40, stops the step-down operation of the DCDC 21, and ends the charging of the secondary power supply 20.

[0041] Furthermore, if the first system 110 fails while the first system 110 is supplying power to the high-voltage load 101, the power supply control device 1 stops supplying power to the high-voltage load 101. Therefore, the control unit 3 determines whether or not the first system 110 has failed while the IG is on.

[0042] For example, when the detection result of the voltage of the first system 110 input from the first voltage sensor 61 continues to be below the ground fault threshold for a predetermined time, the control unit 3 detects a ground fault as a malfunction of the first system 110. Furthermore, when the detection result of the voltage of the second system 120 input from the second voltage sensor 62 continues to be below the ground fault threshold for a predetermined time, the control unit 3 detects a ground fault as a malfunction of the second system 120.

[0043] If the first system 110 fails while power is being supplied to the high-voltage load 101 by the first system 110, the control unit 3 switches the power supply to the high-voltage load 101 from the first system 110 to the power supply by the second system 120.

[0044] 6, the control unit 3 controls the DCDC 21 to perform a step-up operation, and the DCDC 21 steps up the output voltage of the secondary power supply 20 to a voltage equivalent to the output voltage of the main power supply 10, and supplies the voltage to the high-voltage load 101. As a result, even if the first system 110 fails, the power supply control device 1 can perform backup control to supply power from the secondary power supply 20 to the high-voltage load 101 using the second system 120. If the second system 120 fails, the control unit 3 turns off the seventh and eighth switches 47, 48. This lengthens the time for which power required for backup is supplied to the high-voltage load 101, and the backup control time can be extended.

[0045] [2.2. Example of operation of the Power Supply Control Device 1 while the IG is off] Next, an example of the operation of the power supply control device 1 while the IG is off will be described with reference to Figures 7 to 9. As shown in Figure 7, when an IG off signal is input from the vehicle 12 via the IG signal input line 13, the control unit 3 turns off the first switch 41 and turns on the second switch 42.

[0046] Furthermore, the control unit 3 turns on the load switch corresponding to the load that operates during the period when the IG is off, among the high voltage load 101 and the low voltage load 102, and turns off the load switch corresponding to the load that does not operate.

[0047] Here, it is assumed that the high-voltage load 101 connected to the fifth switch 45 and the low-voltage load 102 connected to the seventh and eighth switches 47 and 48 may operate while the IG is off. It is also assumed that the high-voltage load 101 connected to the sixth switch 46 may not operate while the IG is off.

[0048] In this case, when an IG off signal is input from the vehicle 12 via the IG signal input line 13, the control unit 3 turns off the sixth switch 46. In this way, the control unit 3 cuts off the power supply path to the high-voltage load 101 that is connected to the sixth switch 46 and is unlikely to operate while the IG is off, and suppresses unnecessary consumption of dark current, thereby making it possible to extend the power supply time from the auxiliary power supply 20.

[0049] In the state shown in FIG. 7, the output voltage of the secondary power supply 20 is applied to the high-voltage load 101 connected to the fifth switch 45 and the low-voltage load 102 connected to the seventh and eighth switches 47 and 48, but unless these high-voltage load 101 and low-voltage load 102 are activated, no power greater than the dark current is consumed.

[0050] Thereafter, the control unit 3 determines whether the high-voltage load 101 or the low-voltage load 102 has started operating while the IG is off. For example, when a current is detected by the current sensor 53, the control unit 3 determines that the high-voltage load 101 connected to the fifth switch 45 has started operating. When a current is detected by the current sensor 55, the control unit 3 determines that the low-voltage load 102 connected to the seventh switch 47 has started operating. When a current is detected by the current sensor 56, the control unit 3 determines that the low-voltage load 102 connected to the eighth switch 48 has started operating.

[0051] When the control unit 3 determines that the high-voltage load 101 connected to the fifth switch 45 has started operating while the IG is off, it turns off the second switch 42 and causes the DCDC 21 to perform boost operation, as shown in Figure 8.

[0052] In this way, the control unit 3 uses the first path 31, which boosts the output voltage of the secondary power supply 20 via the DCDC 21 and supplies power to the loads, to supply power of a voltage higher than the output voltage of the secondary power supply 20 to the high-voltage load 101 connected to the fifth switch 45. At this time, the power supply control device 1 turns off the sixth switch 46, thereby suppressing the generation of unnecessary dark current.

[0053] At this time, power is also supplied to the low-voltage load 102 via the seventh switch 47 and the eighth switch 48, but unless the low-voltage load 102 operates, the low-voltage load 102 does not consume power greater than the dark current.

[0054] Furthermore, if the control unit 3 determines that the low-voltage load 102 connected to the seventh and eighth switches 47 and 48 has started operating while the IG is off, it maintains the second, seventh and eighth switches 42, 47 and 48 in the on state, as shown in FIG. 9.

[0055] In this way, the control unit 3 supplies power of the output voltage of the secondary power supply 20 to the low-voltage load 102 connected to the seventh and eighth switches 47, 48 using the second path 32 that supplies power to the load group via the second switch 42, without boosting the output voltage of the secondary power supply 20. At this time, the power supply control device 1 turns off the sixth switch 46, thereby suppressing the generation of unnecessary dark current.

[0056] At this time, power is also supplied to the high-voltage load 101 via the fifth switch 45, but if the high-voltage load 101 is not activated, the high-voltage load 101 does not consume power greater than the dark current. If the high-voltage load 101 connected to the fifth switch 45 also activates in this state, as shown in Fig. 8, power with a voltage higher than the output voltage of the secondary power supply 20 is supplied to the high-voltage load 101 connected to the fifth switch 45 using the first path 31 that boosts the output voltage of the secondary power supply 20 via the DCDC 21 and supplies power to the loads.

[0057] The control unit 3 may also be configured to detect whether the load that has started operating while the IG is off is the high-voltage load 101 or the low-voltage load 102. In this case, the control unit 3 supplies power to the high-voltage load 101 or the low-voltage load 102 that has started operating while the IG is off, out of the multiple high-voltage loads 101 and the multiple low-voltage loads 102.

[0058] On the other hand, while the IG is off, the control unit 3 stops the power supply to the inactive high-voltage load 101 and the inactive low-voltage load 102. This allows the power supply control device 1 to minimize the power consumption of the secondary power supply 20 while the IG is off.

[0059] In addition, during the period when the IG is off, the control unit 3 selects the first path 31 when supplying power to a high-voltage load 101 among the loads that operates at a voltage higher than the output voltage of the secondary power supply 20, and selects the second path 32 when supplying power to a low-voltage load 102 that operates at the output voltage of the secondary power supply 20.

[0060] That is, when the control unit 3 supplies power to the low-voltage load 102 that operates on the output voltage of the secondary power supply 20 while the IG is off, the control unit 3 supplies power from the secondary power supply 20 to the low-voltage load 102 via the second switch 42, which has an extremely small power loss compared to the DCDC 21. In this way, the power supply control device 1 can supply power from the secondary power supply 20 to the low-voltage load 102 while suppressing power loss in the secondary power supply 20 while the IG is off.

[0061] Furthermore, when power is supplied from the secondary power supply 20 to the high-voltage load 101 or the low-voltage load 102 while the IG is off, the power supply control device 1 supplies power using the second system 120 provided as a backup for the first system 110 in the redundant power supply system. This allows the power supply control device 1 to supply power from the secondary power supply 20 to the high-voltage load 101 or the low-voltage load 102 without adding a new configuration for power supply while the IG is off.

[0062] [3. Processing Executed by the Control Unit 3 of the Power Supply Control Device 1] Next, processing executed by the control unit of the power supply control device 1 according to the embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a flowchart showing an example of processing executed by the control unit 3 of the power supply control device 1 according to the embodiment while the IG is on. Fig. 11 is a flowchart showing an example of processing executed by the control unit 3 of the power supply control device 1 according to the embodiment while the IG is off.

[0063] When the IG is turned on, the control unit 3 of the power supply control device 1 repeatedly executes the process shown in Fig. 10 until the IG is turned off. Specifically, as shown in Fig. 10, when the IG is turned on, the control unit 3 first turns off the inter-system switch 40, turns on the first, third to eighth switches 41, 43, 44, 45, 46, 47, and 48, and turns off the second switch 42 (step S101). In this way, the power supply control device 1 supplies power from the main power supply 10 via the first system 110 to the high-voltage load 101 and the low-voltage load 102.

[0064] Next, the control unit 3 determines whether the amount of stored power in the secondary power supply 20 is less than the predetermined amount (step S102). If the control unit 3 determines that the amount of stored power in the secondary power supply 20 is not less than the predetermined amount (step S102, No), the control unit 3 proceeds to step S107.

[0065] Furthermore, when the control unit 3 determines that the amount of stored power in the secondary power supply 20 is less than the predetermined amount of stored power (step S102, Yes), it turns on the inter-system switch 40 (step S103), causes the DCDC 21 to perform step-down operation (step S104), and causes the DCDC 21 to step up the output voltage of the main power supply 10 and supply it to the secondary power supply 20, thereby charging the secondary power supply 20. At this time, if the output voltage of the main power supply 10 is not sufficiently high, the DCDC 11 charges the main power supply 10 until the output voltage of the main power supply 10 becomes sufficiently high.

[0066] Thereafter, the control unit 3 determines whether the amount of stored power in the secondary power supply 20 has reached a predetermined amount or more (step S105). If the control unit 3 determines that the amount of stored power in the secondary power supply 20 has not reached the predetermined amount or more (step S105, No), the control unit 3 proceeds to step S104.

[0067] Furthermore, when the control unit 3 determines that the amount of stored power in the secondary power supply 20 has reached or exceeded the predetermined amount of stored power (step S105, Yes), it turns off the inter-system switch 40 (step S106) and determines whether or not the first system 110 has failed (step S107).When the control unit 3 determines that the first system 110 has not failed (step S107, No), it ends the process and restarts the process from step S101.

[0068] When the control unit 3 determines that the first system 110 has failed (step S107, Yes), it causes the DCDC 21 to perform a boost operation (step S108), and the output voltage of the secondary power supply 20 is boosted by the DCDC 21 to supply power to the high-voltage load 101. This allows the power supply control device 1 to perform fail-safe control using the secondary power supply 20 even if the first system 110 has failed. Thereafter, the control unit 3 ends the process.

[0069] Thereafter, when the IG is turned off, the control unit 3 executes the process shown in Fig. 11. Here, a case will be described in which the high-voltage load 101 connected to the fifth switch 45 and the low-voltage load 102 connected to the seventh switch 47 and the eighth switch 48 are loads that may operate while the IG is off, and the high-voltage load 101 connected to the sixth switch 46 is a load that may not operate while the IG is off.

[0070] 11, when IG is turned off, the control unit 3 first turns off the first and sixth switches 41 and 46 and turns on the second switch 42 (step S201). As a result, the high-voltage load 101 and the low-voltage load 102 connected to the fifth switch 45 are connected to the secondary power supply 20, but at this time, the high-voltage load 101 and the low-voltage load 102 do not consume the power supplied from the secondary power supply 20 unless they are operating.

[0071] Thereafter, the control unit 3 determines whether the high voltage load 101 has started operating (step S202). At this time, if the current sensor 53 detects a current, the control unit 3 determines that the high voltage load 101 connected to the current sensor 53 has started operating.

[0072] When the control unit 3 determines that the high-voltage load 101 has started operating (step S202, Yes), it turns off the second switch 42 (step S203) and causes the DCDC 21 to perform a voltage step-up operation (step S204). In this way, the control unit 3 causes the DCDC 21 to step up the output voltage of the secondary power supply 20, supplies power to the high-voltage load 101, and ends the process.

[0073] Furthermore, when the control unit 3 determines that the high-voltage load 101 has not started operating (step S202, No), it determines whether the low-voltage load 102 has started operating (step S205). When the current sensors 55 and 56 detect a current, the control unit 3 determines that the low-voltage load 102 connected to the current sensors 55 and 56 has started operating.

[0074] If the control unit 3 determines that the low-voltage load 102 has not started operating (step S205, No), it ends the process and restarts the process from step S201. If the control unit 3 determines that the low-voltage load 102 has started operating (step S205, Yes), it turns on the second switch 42 (step S206) and ends the process. In this way, the control unit 3 supplies power from the secondary power supply 20 to the low-voltage load 102 without going through the DCDC 21 or boosting the output voltage of the secondary power supply 20.

[0075] In the above-described embodiment, when the control unit 3 detects that the high-voltage load 101 is operating while the IG is off, it selects the first path 31 to supply power, and when it detects that the low-voltage load 102 is operating, it selects the second path 32 to supply power, but this is just one example.

[0076] For example, if the high voltage load 101 or the low voltage load 102 that operates while the IG is off is predetermined, the control unit 3 stores the high voltage load 101 or the low voltage load 102 that operates while the IG is off.

[0077] When the load that operates while the IG is off is the high-voltage load 101, the control unit 3 controls the load to be in the state shown in Fig. 8 upon receiving an IG off signal, and also controls the seventh and eighth switches 47, 48 to be turned off. When the load that operates while the IG is off is the low-voltage load 102, the control unit 3 controls the load to be in the state shown in Fig. 9 upon receiving an IG off signal, and also controls the fifth switch 45 to be turned off. In this way, the power supply control device 1 can supply power from the secondary power supply 20 to the low-voltage load 102 while suppressing power loss in the secondary power supply 20 during the period when the IG is off, and can further reduce dark current.

[0078] [4. Notes] As an appendix, the features of the present invention are as follows. (1) an auxiliary power supply having an output voltage lower than an output voltage of the main power supply and capable of supplying power to a group of loads that operate while an ignition switch of the vehicle is off; a first path that boosts the output voltage of the secondary power supply via a DC-DC converter and supplies power to the load group; a second path that supplies the output voltage of the secondary power supply to the load group via a switch; a control unit that selects the first path when power is supplied to a high-voltage load among the loads that operates at a voltage higher than the output voltage of the secondary power supply during a period when the ignition switch is off, and selects the second path when power is supplied to a low-voltage load that operates at the output voltage of the secondary power supply; A power supply control device comprising: (2) a load switch is provided between the high-voltage load and the power supply input line, and a load switch is provided between the low-voltage load and the power supply input line, The control unit turning on a load switch corresponding to a load that operates during a period in which the ignition switch is off, among the high-voltage load and the low-voltage load, and turning off a load switch corresponding to a load that does not operate during a period in which the ignition switch is off; The power supply control device according to (1) above. (3) The control unit When the amount of charge stored in the auxiliary power supply falls below a predetermined amount while the ignition switch is on, the output voltage of the main power supply is stepped down via the DC-DC converter to supply power to the auxiliary power supply and charge the auxiliary power supply. The power supply control device according to (1) or (2). (4) a first system that supplies power from the main power supply to the loads; a second system that supplies power from the secondary power supply to the load group; Equipped with The control unit If the first system fails while power is being supplied to the load group by the first system, power supply is switched to the second system. The power supply control device according to any one of (1) to (3) above. (5) an auxiliary power supply having an output voltage lower than an output voltage of the main power supply and capable of supplying power to a group of loads that operate when an ignition switch of the vehicle is off; a first path that boosts the output voltage of the secondary power supply via a DC-DC converter and supplies power to the load group; a second path that supplies the output voltage of the secondary power supply to the load group via a switch; a control unit that controls power supply to the load group; The control unit of the power supply control device includes: When the ignition switch is off, the first path is selected when power is supplied to a high-voltage load among the loads that operates at a voltage higher than the output voltage of the secondary power supply, and the second path is selected when power is supplied to a low-voltage load that operates at the output voltage of the secondary power supply. Power control method.

[0079] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0080] 1 Power supply control device 10 Main power 11,21 DCDC 12 vehicles 13 IG signal input line 20 Sub power supply 22 Monitoring Line 3. Control Unit 31 Route 1 32 Route 2 40 Intersystem switch 41 First Switch 42 Second Switch 43 Third Switch 44 4th Switch 45 5th Switch 46 6th Switch 47 7th Switch 48 8th Switch 51,52 Diode 53, 54, 55, 56 Current sensors 61 First voltage sensor 62 Second voltage sensor 101 High-voltage load 102 Low Pressure Load 110 1st system 120 2nd system 130 Power Input Line

Claims

1. an auxiliary power supply having an output voltage lower than an output voltage of the main power supply and capable of supplying power to a group of loads that operate while an ignition switch of the vehicle is off; a first path that boosts the output voltage of the secondary power supply via a DC-DC converter and supplies power to the load group; a second path that supplies the output voltage of the secondary power supply to the load group via a switch; a control unit that selects the first path when power is supplied to a high-voltage load among the loads that operates at a voltage higher than the output voltage of the secondary power supply during a period when the ignition switch is off, and selects the second path when power is supplied to a low-voltage load that operates at the output voltage of the secondary power supply; A power supply control device comprising:

2. a load switch is provided between the high-voltage load and the power supply input line, and a load switch is provided between the low-voltage load and the power supply input line, The control unit turning on a load switch corresponding to a load that operates during a period in which the ignition switch is off, among the high-voltage load and the low-voltage load, and turning off a load switch corresponding to a load that does not operate during a period in which the ignition switch is off; The power supply control device according to claim 1 .

3. The control unit When the amount of stored power in the auxiliary power supply falls below a predetermined amount while the ignition switch is on, the output voltage of the main power supply is stepped down via the DC-DC converter to supply power to the auxiliary power supply and charge the auxiliary power supply. The power supply control device according to claim 1 .

4. a first system that supplies power from the main power supply to the loads; a second system that supplies the power of the secondary power supply to the load group; Equipped with The control unit If the first system fails while power is being supplied to the load group by the first system, power supply is switched to the second system. The power supply control device according to claim 1 .

5. an auxiliary power supply having an output voltage lower than an output voltage of the main power supply and capable of supplying power to a group of loads that operate when an ignition switch of the vehicle is off; a first path that boosts the output voltage of the secondary power supply via a DC-DC converter and supplies power to the load group; a second path that supplies the output voltage of the secondary power supply to the load group via a switch; a control unit that controls power supply to the load group; The control unit of the power supply control device includes: When the ignition switch is off, the first path is selected when power is supplied to a high-voltage load among the loads that operates at a voltage higher than the output voltage of the secondary power supply, and the second path is selected when power is supplied to a low-voltage load that operates at the output voltage of the secondary power supply. Power control method.

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