Power supply system

Abstract

To provide a power supply system capable of suppressing incorrect detection of abnormality.SOLUTION: In a power supply system 1, a DC / DC converter 22 can execute a first operation that converts a voltage of an output node N1 to a charge voltage to supply the charge voltage to a sub power supply 24, and a second operation that converts a voltage of the sub power supply 24 to an output voltage to supply the output voltage to the output node N1. A load 14a is connected to the output node N1 via a feed line 16a. The load 14a has a voltage detection unit 30 that detects a voltage output from the feed line 16a. Control units (a control unit 28 and a control unit 34) charge the sub power supply 24 by causing a first switch 20 to be conductive to allow the DC / DC converter 22 to execute the first operation, and after the charging of the sub power supply 24, switch the first switch 20 to non-conductive to allow the DC / DC converter 22 to execute the second operation, and on the basis of the voltage detected by the voltage detection unit 30, detect an abnormality.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply system.

Background Art

[0002] As a power supply mounted on a vehicle or the like, when the main power supply fails, a redundant power supply that supplies power from a sub-power supply to a load is known. Patent Document 1 discloses a power supply device including a first system, a second system, an inter-system switch, a current supply unit, and a disconnection detection unit. The first system supplies the power of the first power supply to the load. The second system supplies the power of the second power supply to the load. The inter-system switch can connect and disconnect a connection path connecting the first system and the second system. The current supply unit constantly flows a current through a specific path between a connection point between the connection path and the second system and the second power supply. The disconnection detection unit detects a disconnection of the specific path according to the presence or absence of a current flowing through the specific path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to surely perform backup by a redundant power supply, it is desirable to detect a disconnection of a power supply line connecting the redundant power supply and a load to be backed up. As an example of a disconnection detection method, a technique of supplying power from a main power supply to a load via an internal path and a power supply line of a redundant power supply and determining that there is an abnormality when the voltage on the load side is lower than a threshold value can be considered. In this technique, even when the power supply line is not disconnected, in the worst case, the voltage on the load side may become lower than the threshold value, and there is a possibility of being erroneously detected as having an abnormality.

[0005] An object of the present invention is to provide a power supply system capable of suppressing false detection of an abnormality.

Means for Solving the Problem

[0006] To solve the above problems, a power supply system according to an aspect of the present invention includes a main power supply, a rechargeable sub - power supply, a first switch for switching whether to conduct between the main power supply and an output node, a first operation of converting the voltage of the output node into a charging voltage and supplying the charging voltage to the sub - power supply, a second operation of converting the voltage of the sub - power supply into an output voltage and supplying the output voltage to the output node, a DC / DC converter capable of performing the above operations, a load connected to the output node via a power supply line, the load having a voltage detection unit for detecting the voltage output from the power supply line, and a control unit for controlling the first switch and the DC / DC converter. The control unit charges the sub - power supply by turning on the first switch and causing the DC / DC converter to perform the first operation. After charging the sub - power supply, the control unit switches the first switch to non - conducting, causes the DC / DC converter to perform the second operation, and detects an abnormality based on the voltage detected by the voltage detection unit.

Advantages of the Invention

[0007] According to the present invention, a power supply system capable of suppressing false detection of abnormalities can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0009] FIG. 1 schematically shows the configuration of the power supply system 1 according to the embodiment. The power supply system 1 is mounted on, for example, a vehicle (not shown) and supplies power to each part of the vehicle. The vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0010] The power supply system 1 includes a main power supply 10, a redundant power supply 12, a load 14a, a load 14b, a power supply line 16a, and a power supply line 16b. Hereinafter, the load 14a and the load 14b are collectively referred to as the "load 14" as appropriate. The power supply line 16a and the power supply line 16b are collectively referred to as the "power supply line 16" as appropriate.

[0011] The main power supply 10 is a rechargeable power storage device, such as a lead-acid battery. The main power supply 10 is charged by the power from a generator (such as an alternator) (not shown) mounted on the vehicle. The generator generates electricity by receiving the driving force from a driving force source such as an engine mounted on the vehicle.

[0012] The main power supply 10 is electrically connected to each of the load 14a and the load 14b. Although two loads 14 are illustrated in FIG. 1, the main power supply 10 may be connected to any number of loads 14. When the main power supply 10 is normal, that is, when the main power supply 10 is not defective, the main power supply 10 can supply power to each of the load 14a and the load 14b. The load 14a and the load 14b are systems to be backed up, and details will be described later.

[0013] The main power supply 10 is also electrically connected to the redundant power supply 12. The redundant power supply 12 is also called an integrated redundant power supply or an SBM (Second Battery Module). The redundant power supply 12 is also electrically connected to the load 14a by the power supply line 16a such as a wire harness and to the load 14b by the power supply line 16b.

[0014] The redundant power supply 12 includes a first switch 20, a DC / DC converter 22, a sub-power supply 24, a second switch 26a, a second switch 26b, a control unit 28, a power supply terminal T1, a power supply terminal T2a, and a power supply terminal T2b.

[0015] When, for example, an ignition switch (not shown) of a vehicle is turned on, the redundant power supply 12 charges the sub-power supply 24 with the power supplied from the main power supply 10. After the sub-power supply 24 is charged, if the main power supply 10 fails due to, for example, a ground fault, the redundant power supply 12 supplies the power of the sub-power supply 24 to each of the loads 14a and 14b via the power supply line 16a and the power supply line 16b. Thereby, the loads 14a and 14b can operate even when the main power supply 10 fails.

[0016] The sub-power supply 24 is a chargeable and dischargeable power storage device, and is composed of, for example, a power storage element such as an electric double layer capacitor. The sub-power supply 24 may be a secondary battery such as a lithium ion battery or a nickel metal hydride battery.

[0017] The first switch 20 is composed of, for example, a semiconductor switch element. The first switch 20 may be composed of a relay or the like. The first switch 20 is connected between the power supply terminal T1 and the output node N1. The first switch 20 switches whether to conduct between the main power supply 10 connected to the power supply terminal T1 and the output node N1.

[0018] The DC / DC converter 22 is connected between the sub-power supply 24 and the output node N1. The DC / DC converter 22 is a bidirectional DC / DC converter capable of stepping up and down. The DC / DC converter 22 can execute a first operation of converting the voltage of the output node N1 into a charging voltage and supplying the charging voltage to the sub-power supply 24, and a second operation of converting the voltage of the sub-power supply 24 into an output voltage and supplying the output voltage to the output node N1. The values of the charging voltage and the output voltage can be appropriately determined by experiments or simulations.

[0019] The second switch 26a and the second switch 26b are each composed of, for example, a semiconductor switch element or a relay. The second switch 26a is connected between the output node N1 and the power supply terminal T2a. The second switch 26a switches whether to conduct between the output node N1 and the power supply terminal T2a.

[0020] The second switch 26b is connected between the output node N1 and the power supply terminal T2b. The second switch 26b switches whether to conduct between the output node N1 and the power supply terminal T2b.

[0021] The control unit 28 controls the first switch 20, the DC / DC converter 22, the second switch 26a, and the second switch 26b.

[0022] The power supply terminal T2a is connected to the power supply terminal T5a of the load 14a by the power supply line 16a. That is, the load 14a is connected to the output node N1 via the power supply line 16a and the second switch 26a.

[0023] The load 14a is, for example, an electric brake system of a vehicle. The load 14a includes a first rectifying element D1a, a second rectifying element D2a, a voltage detection unit 30, an internal load 32a, a control unit 34, a first resistor R1, a second resistor R2, a power supply terminal T4a, and a power supply terminal T5a.

[0024] The first rectifying element D1a is, for example, a diode. The anode of the first rectifying element D1a is connected to the power supply terminal T4a connected to the main power supply 10. The cathode of the first rectifying element D1a is connected to the power supply node of the internal load 32a.

[0025] The second rectifying element D2a is, for example, a diode. The anode of the second rectifying element D2a is connected to the power supply terminal T5a. The cathode of the second rectifying element D2a is connected to the cathode of the first rectifying element D1a.

[0026] The internal load 32a includes various loads related to the electric brake, such as a brake ECU (Electronic Control Unit) that executes processes related to the control of the electric brake, and an actuator for operating the electric brake. The internal load 32a operates using the power supplied to the power supply node as a power source. Since the internal load 32a has a known configuration, further detailed description thereof is omitted.

[0027] The first resistor R1 has one end connected to the power supply terminal T5a and the other end connected to one end of the second resistor R2. The second resistor R2 has one end connected to the other end of the first resistor R1 and the other end connected to the ground.

[0028] The voltage detection unit 30 detects the voltage at the connection node between the first resistor R1 and the second resistor R2. This corresponds to the voltage detection unit 30 detecting the voltage output from the power supply line 16a. The voltage detection unit 30 supplies the detected voltage value to the control unit 34.

[0029] The control unit 34 detects a disconnection of the power supply line 16a based on the voltage detected by the voltage detection unit 30.

[0030] The configurations of the control unit 28 and the control unit 34 can be realized by the cooperation of hardware resources and software resources, or by hardware resources only. As hardware resources, analog elements, microcomputers, DSPs, ROMs, RAMs, ASICs, FPGAs, and other LSIs can be used. As software resources, programs such as firmware can be used. The functions of the control unit 34 may be possessed by the control unit 28.

[0031] Also, the power supply terminal T2b of the redundant power supply 12 is connected to the power supply terminal T5b of the load 14b by the power supply line 16b. That is, the load 14b is connected to the output node N1 via the power supply line 16b and the second switch 26b.

[0032] The load 14b is, for example, a door unlocking system of a vehicle. The load 14b includes a first rectifying element D1b, a second rectifying element D2b, an internal load 32b, a power supply terminal T4b, and a power supply terminal T5b.

[0033] The anode of the first rectifying element D1b is connected to the power supply terminal T4b connected to the main power supply 10. The cathode of the first rectifying element D1b is connected to the power supply node of the internal load 32b.

[0034] The anode of the second rectifying element D2b is connected to the power supply terminal T5b. The cathode of the second rectifying element D2b is connected to the cathode of the first rectifying element D1b.

[0035] The internal load 32b includes, for example, a body ECU that executes processing related to door unlocking, and various loads such as an actuator. The internal load 32b operates using the power supplied to the power supply node as a power source.

[0036] Although not shown, the load 14b also includes a configuration equivalent to the voltage detection unit 30, the control unit 34, the first resistor R1, and the second resistor R2 of the load 14a, and can detect a disconnection of the power supply line 16b. The description of the disconnection detection of the power supply line 16b is omitted.

[0037] In addition to these loads 14, the power supply system 1 may further include various loads that require backup, such as a shift-by-wire system.

[0038] When the ignition switch of the vehicle is turned on, the control unit 28 turns on the first switch 20 and causes the DC / DC converter 22 to execute a first operation to charge the sub-power supply 24. The DC / DC converter 22 charges the sub-power supply 24 with the power of the main power supply 10. At this time, the control unit 28 may turn on the second switch 26a and the second switch 26b, or may leave them non-conductive.

[0039] The control unit 28 detects the completion of charging of the sub-power supply 24. For detecting the completion of charging of the sub-power supply 24, known techniques can be utilized. For example, the voltage of the sub-power supply 24 can be monitored by a voltage sensor (not shown), and based on the voltage, it can be determined whether the charging is completed. After the completion of charging of the sub-power supply 24, the control unit 28 switches the first switch 20 to non-conductive, conducts the second switch 26a and the second switch 26b, and causes the DC / DC converter 22 to execute a second operation. The DC / DC converter 22 supplies the output voltage obtained by converting the voltage of the sub-power supply 24 to the loads 14a and 14b.

[0040] When the control unit 28 causes the DC / DC converter 22 to execute the second operation, it outputs a control signal to the control unit 34 of the load 14a.

[0041] When the control unit 34 receives a control signal from the control unit 28, it detects an abnormality based on the voltage detected by the voltage detection unit 30. The abnormality is an open circuit of the power supply line 16a. The control unit 34 compares the voltage detected by the voltage detection unit 30 with a predetermined abnormality determination value. When the voltage detected by the voltage detection unit 30 is equal to or lower than the abnormality determination value, the control unit 34 determines that an abnormality has occurred. When the voltage detected by the voltage detection unit 30 is higher than the abnormality determination value, the control unit 34 determines that no abnormality has occurred. The abnormality determination value can be appropriately determined by experiments or simulations so that the occurrence of an open circuit can be properly detected. When an abnormality is detected, the control unit 34 executes a predetermined process such as recording diagnostic information indicating the open circuit of the power supply line 16a.

[0042] When the abnormality detection is executed, the control unit 34 notifies the control unit 28 of the redundant power supply 12 of the completion of the abnormality detection by a control signal. When the control unit 28 receives a control signal from the control unit 34, with the second operation of the DC / DC converter 22 being continued, it switches the second switch 26a and the second switch 26b to non-conductive and monitors the presence or absence of a failure of the main power supply 10. Thereby, the power stored in the sub-power supply 24 can be retained, and it is possible to prepare for a failure of the main power supply 10.

[0043] For detecting a failure of the main power supply 10, known techniques can be used. For example, a voltage sensor (not shown) monitors the voltage of the power supply terminal T1, and the control unit 28 may periodically determine the presence or absence of a failure based on the voltage. When the voltage of the power supply terminal T1 is equal to or lower than a predetermined failure determination value, the control unit 28 determines that the main power supply 10 has failed. When the voltage of the power supply terminal T1 is higher than the failure determination value, the control unit 28 determines that the main power supply 10 has not failed. The failure determination value can be appropriately determined by experiments or simulations so that a power supply failure can be properly detected.

[0044] When the main power supply 10 has failed, the control unit 28 conducts the second switch 26a and the second switch 26b. Since the DC / DC converter 22 is in the second operation during a power supply failure, the power of the sub-power supply 24 can be immediately supplied to the load 14 without waiting for the operation start of the DC / DC converter 22.

[0045] On the other hand, when the main power supply 10 has not failed, the control unit 28 keeps the second switch 26a and the second switch 26b non-conductive.

[0046] Next, the overall operation of the power supply system 1 with the above configuration will be described. FIG. 2 is a flowchart showing the process related to the disconnection detection of the power supply system 1 in FIG. 1. The process in FIG. 2 starts when the ignition switch is switched from off to on.

[0047] The control unit 28 turns on the first switch 20 and starts charging the sub-power supply 24 by the DC / DC converter 22 (S10). The control unit 28 determines whether the charging of the sub-power supply 24 is completed (S12). If the charging is not completed (N in S12), the process returns to S12.

[0048] When the charging of the sub-power supply 24 is completed (Y in S12), the control unit 28 turns off the first switch 20, turns on the second switch 26a and the second switch 26b, and supplies power from the DC / DC converter 22 to the load 14 (S14). The control unit 34 executes disconnection detection (S16) and ends the process.

[0049] Here, the power supply system of the comparative example will be described. FIG. 3 schematically shows the configuration of the power supply system 1X of the comparative example. The configuration of the power supply system 1X of the comparative example is basically the same as the configuration of the embodiment in FIG. 1, but as will be described below, the control by the control unit 28X is different from that of the embodiment. In FIG. 3, the second switches 26a and 26b are omitted, and a state in which they are conducting is shown.

[0050] FIG. 4 is a flowchart showing the process related to the disconnection detection of the power supply system 1X of the comparative example. The process in FIG. 4 starts when the ignition switch is switched from off to on.

[0051] The control unit 28X turns on the first switch 20 and starts charging the sub-power supply 24 by the DC / DC converter 22 (S40). The power supply system 1X supplies power from the main power supply 10 to the load 14 (S42). In S42, the power of the main power supply 10 is supplied to the load 14 through the internal path of the redundant power supply 12X. In this state, the control unit 34 of the load 14a executes disconnection detection (S44) and ends the process.

[0052] That is, while the DC / DC converter 22 is performing the first operation and the sub-power supply 24 is being charged with the power of the main power supply 10, based on the power supplied from the main power supply 10 to the load 14a through the on-state first switch 20, the voltage is detected at the load 14a and disconnection detection is executed. The current path at this time is indicated by an arrow in FIG. 3.

[0053] FIG. 5 is a diagram for explaining an example of the voltage of each part at the time of disconnection detection in the power supply system 1X of the comparative example. FIG. 5 shows the worst-case voltage.

[0054] In the worst case, assume that due to deterioration of the main power supply 10, for example, the voltage of the main power supply 10 has dropped to 10.5V. Also, assume that a voltage drop occurs due to the charging current of the sub-power supply 24 flowing through the wiring resistance of the current path from the power supply terminal T1 to the power supply terminal T2a, and that the voltage drop is 2.6V. In this case, the voltage of the power supply terminal T2a of the redundant power supply 12 is 7.9V.

[0055] Assuming that the voltage drop due to the power supply line 16a is 0.6V, the voltage of the power supply terminal T5a of the load 14a is 7.3V.

[0056] Assuming that the variation in the detected voltage value by the voltage detection unit 30 is ±10%, the detected voltage value in the worst case is 6.6V. Note that the detected voltage value is a value converted to the voltage of the power supply terminal T5a based on the voltage division ratio of the first resistor R1 and the second resistor R2. For example, assuming that the abnormal determination value is 6.8V, in the worst case of FIG. 5, even if the power supply line 16a is not disconnected, it is erroneously detected as having a disconnection.

[0057] Although not included in FIG. 5, when the internal load 32b of the load 14b operates at the time of disconnection detection and the power of the main power supply 10 passes through the internal path of the redundant power supply 12X and is supplied to the load 14b, the voltage of the power supply terminal T5a of the load 14a also drops.

[0058] Here, if the charging current of the sub-power supply 24 is reduced, the voltage drop from the power supply terminal T1 to the power supply terminal T2a will be reduced, and it is considered that it will be less likely to be erroneously detected than in the comparative example. However, if there is a limit to the time from when the ignition switch is turned on until the charging of the sub-power supply 24 is completed, it is difficult to reduce the charging current. For example, in a remote parking system, there is a limit to the time from when the user starts the remote parking application on the terminal until the vehicle starts moving. Therefore, it is necessary to complete the charging of the sub-power supply 24 within a predetermined time and execute disconnection detection.

[0059] In addition, by setting the abnormal determination value low, it is considered that even if the voltage drops in the worst case, false detection is less likely to occur than in the comparative example. However, if the abnormal determination value is lowered, the discrimination accuracy of whether or not there is a disconnection may decrease.

[0060] On the other hand, in the embodiment, after the sub-power supply 24 is charged, the first switch 20 is switched to non-conduction, the DC / DC converter 22 is made to perform a second operation, and an abnormality is detected based on the voltage supplied to the load 14a. Therefore, an abnormality can be detected based on the output voltage of the DC / DC converter 22 that is more stable than the voltage of the main power supply 10. Also, no voltage drop due to the current for charging the sub-power supply 24 occurs in the voltage supplied from the redundant power supply 12 to the load 14a.

[0061] Thereby, when the power supply line 16a is not disconnected, even in the worst case, the voltage supplied to the load 14a can be prevented from dropping too much. Therefore, false detection of disconnection can be suppressed compared to the comparative example.

[0062] Also, there is no need to change the charging current of the sub-power supply 24 and the abnormal determination value for disconnection detection from the comparative example. Therefore, false detection of disconnection can be suppressed while maintaining the charging time of the sub-power supply 24 and the discrimination accuracy of the presence or absence of disconnection equivalent to the comparative example. Also, abnormality detection can be executed each time the ignition switch is turned on.

[0063] The present invention has been described based on the embodiment. It should be understood by those skilled in the art that the embodiment is merely an example, and various modifications are possible for the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

Explanation of Reference Numerals

[0064] 1…Power supply system, 10…Main power supply, 12…Redundant power supply, 14, 14a, 14b…Load, 16, 16a, 16b…Power supply line, 20…First switch, 22…DC / DC converter, 24…Sub power supply, 26a, 26b…Second switch, 28…Control unit, 30…Voltage detection unit, 32a, 32b…Internal load, 34…Control unit, D1a, D1b…First rectifying element, D2a, D2b…Second rectifying element, N1…Output node, R1…First resistor, R2…Second resistor.

Claims

1. A main power supply, a rechargeable sub-power supply, a first switch for switching whether to conduct between the main power supply and an output node, a DC / DC converter capable of performing a first operation of converting the voltage of the output node into a charging voltage and supplying the charging voltage to the sub-power supply, and a second operation of converting the voltage of the sub-power supply into an output voltage and supplying the output voltage to the output node, a load connected to the output node via a power supply line, the load having a voltage detection unit for detecting the voltage output from the power supply line, a control unit for controlling the first switch and the DC / DC converter, comprising: The control unit: charges the sub-power supply by turning on the first switch and causing the DC / DC converter to perform the first operation, after charging the sub-power supply, switches the first switch to non-conduction, causes the DC / DC converter to perform the second operation, and detects an abnormality based on the voltage detected by the voltage detection unit. A power supply system characterized by the above.

2. The load: an internal load, a first rectifying element having an anode connected to the main power supply and a cathode connected to the power supply node of the internal load, a second rectifying element having an anode connected to the power supply line and a cathode connected to the cathode of the first rectifying element, having: The power supply system: further comprises a second switch for switching whether to conduct between the output node and the power supply line, The control unit turns on the second switch to perform abnormality detection, and after performing the abnormality detection, switches the second switch to non-conduction while causing the DC / DC converter to perform the second operation, and monitors the presence or absence of a defect in the main power supply. The power supply system according to claim 1, characterized by the above.

3. When the main power supply fails, the control unit turns on the second switch. The power supply system according to claim 2, characterized by the above.

4. The power supply system is mounted on a vehicle, When the ignition switch of the vehicle is turned on, the control unit turns on the first switch and causes the DC / DC converter to perform the first operation to charge the sub-power supply. The power supply system according to claim 1, characterized by the above.

5. The load is the electric brake system of the vehicle. The power supply system according to claim 4, characterized by the above.

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