Power Supply Control Device

Abstract

The present invention includes: A DC / DC converter that, serving as a back-up for a first power supply, supplies power from a second power supply to a relay; a third power supply that is charged by the first power supply and outputs the charged power to the relay; a switch of the third power supply; and a control unit that controls the DC / DC converter, the switch, and the second power supply. In a state where the control unit turns OFF the DC / DC converter, and turns the switch ON to cause the third power supply to be in a charging state, the control unit: turns the switch OFF to stop the charging of the third power supply, if the voltage of the third power supply is at least a first threshold; turns the switch ON to restart charging of the third power supply, if the voltage of the third power supply is no more than a second threshold which is lower than the first threshold; and turns the DC / DC converter ON, if the voltage of the third power supply is no more than a third threshold which is lower than the second threshold.

Description

[Technical Field]

[0001] The present invention relates to a power supply control device. [Background technology]

[0002] Conventionally, configurations for backing up a power supply mounted on a vehicle have been known. For example, a configuration has been disclosed in which a DC-DC converter is used to generate a backup power supply in an in-vehicle system with low current consumption (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-348769 Summary of the Invention [Problem to be solved by the invention]

[0004] When a DC-DC converter is operated, electrical noise such as EMI (Electro Magnetic Interference) is generated in electrical equipment, which may affect electrical equipment that uses wireless communication such as radios and televisions. Therefore, an object of the present invention is to provide a power supply control device that can suppress electrical noise caused by the operation of a DC-DC converter. [Means for solving the problem]

[0005] The power supply control device of the present invention is applied to an apparatus including an electric device, a relay connected to the electric device, a first power supply that enables the relay to operate, and a second power supply that supplies power to the electric device via the relay. The power supply control device includes a DC-DC converter that supplies power from the second power supply to the relay as a backup for the first power supply, a third power supply that is charged by the first power supply and outputs the charged power to the relay, a switch for the third power supply, and a control unit that controls the DC-DC converter, the switch, and the second power supply. When the DC-DC converter is turned OFF and the switch is turned ON to charge the third power supply, if the voltage of the third power supply is equal to or higher than a first threshold, the control unit turns OFF the switch to stop charging of the third power supply, and if the voltage of the third power supply is equal to or lower than a second threshold that is lower than the first threshold, the control unit turns ON the switch to resume charging of the third power supply, and if the voltage of the third power supply is equal to or lower than a third threshold that is lower than the second threshold, the control unit turns ON the DC-DC converter. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a power supply control device that can suppress electrical noise caused by the operation of a DC-DC converter used as a component of a backup power supply. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a circuit diagram of a vehicle electrical system to which a power supply control device according to an embodiment of the present invention is applied; [Figure 2] 1. FIG. 4 is a graph showing charging (boosting) and discharging (decreasing) of a capacitor that forms a third power supply in the power supply control device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a vehicle electrical system 100 to which a power supply control device 10 according to the present invention is applied will be described with reference to FIG.

[0009] The vehicle electrical system 100 includes an inverter 101, which is an electrical device, a relay 102 connected to the inverter 101, a lead battery 110 (an example of a first power source) that operates the relay 102 with a first power P1, a lithium ion battery 120 (an example of a second power source) that discharges to the inverter 101 via the relay 102, and a power supply control device 10. Examples of the electrical devices include a radio or television that uses wireless communication, as well as a car navigation system. The vehicle may be an EV, HV, PHV, PHEV, or FCV (hereinafter also referred to as "EV, etc.").

[0010] The lead battery 110 supplies a first power P1. The first power P1 is supplied for excitation to operate the relay 102, for driving the control unit 13, which is similar to a computer, and for driving a part of the electrical equipment. The part of the electrical equipment here may be considered to be a 12V electrical component. On the other hand, the lithium ion battery 120 is, for example, a 40V storage battery configured in a series-parallel configuration. The capacitor 12 is charged by the lead battery 110 and is configured to be able to output a third power P3 for excitation to operate the relay 102.

[0011] The relay 102 can switch a large DC current, for example, by normally open operation, in which the contacts are closed only when power is applied. If the relay 102 is disconnected due to an unexpected interruption of the excitation current, the large DC current will be momentarily interrupted, generating a high voltage that may damage the inverter 101. Therefore, the relay 102 must prevent the excitation current from being unexpectedly interrupted. The power supply control device 10 is provided with a backup power supply to prevent such an event.

[0012] If the lead battery 110 that supplies the excitation current to the relay 102 fails without warning due to a wire break or the like, the second power P2 connected to the lead battery 110 via an OR circuit formed by diodes 4 and 2 is supplied as a backup in place of the failed first power P1. However, if the first power P1 fails, it takes several tens of milliseconds for the DC-DC converter 11 to be turned on and for the second power P2 to be sufficiently supplied. The excitation current to the relay 102 is not interrupted in this way, and the third power P3 is supplied from the capacitor 12, so that the ON state due to the excitation of the relay 102 continues.

[0013] A latching relay is suitable for the relay 102. A latching relay does not require a continuous flow of excitation current, and can maintain its state by adding a signal current only when switching, resulting in a greater power saving effect. The first power P1 is power for keeping the relay 102 ON. The voltage of the first power P1 is, for example, 12V to 13.8V, and turns on the transistor 8 to form an excitation drive circuit. The transistor 8 is opened and closed by a relay control signal from the MPU 13 (an example of a control unit).

[0014] The power supply control device 10 has a DC-DC converter 11, a capacitor 12 (an example of a third power supply), a control unit (e.g., a micro-processing unit, hereinafter also referred to as "MPU") 13, a notification unit 14, an input unit 15, a switch 16, a cell voltage measurement IC (CCIC) 17, and a power supply IC 18. A BAT terminal of the power supply IC 18 is connected to the positive terminal of a lead battery 110, and power is constantly supplied via a diode 1. An IG terminal 19 of the power supply IC 18 is connected to a vehicle operation means (not shown) and receives an operation signal.

[0015] The MPU (control unit) 13 is a type of processor also called a microprocessor, and is implemented on a microchip. The MPU 13 performs voltage measurement (S1) to monitor the backup voltage, relay control (S2), shutdown control of the DC / DC converter (S3), shutdown control of the CCIC (S4), control of the operation of the switch 16 (S5), and voltage measurement (S6) to monitor the lead battery voltage. The MPU 13 controls the relay 102, the lithium ion battery 120, the DC-DC converter 11, and the switch 16 according to the measurement results of the voltage of the lead battery 110 related to the first power P1 and the voltage related to the second power P2 supplied from the lithium ion battery 120.

[0016] The control unit 13 is the core of the power supply control device 10, and in the case of a one-chip microcomputer with a minimum drive power of 7V, for example, the circuit configuration is such that power is always supplied stably and reliably from the lead battery 110 via the diode 1 and the power supply IC 18. However, the power supply control device 10 also assumes that the lead battery 110 may fail. If the lead battery 110 fails, it will be backed up by the circuit configuration of the diodes 2 to 4, as will be described later.

[0017] When the DC-DC converter 11 is turned OFF and the switch 16 is turned ON to charge the capacitor 12, if the voltage of the second power P2 is equal to or higher than the first threshold V1, the MPU 13 turns OFF the switch 16 to stop charging the capacitor 12.

[0018] When the voltage of the second power P2 is equal to or lower than a second threshold V2 that is lower than the first threshold V1, the MPU 13 turns on the switch 16 to resume charging of the capacitor 12, and when the voltage of the second power P2 is equal to or lower than a third threshold V3 that is lower than the second threshold V2, the MPU 13 turns on the DC-DC converter 11.

[0019] The DC-DC converter 11 is supplied with power from the lithium ion battery 120 and is capable of outputting a second power P2 for excitation to operate the relay 102. The second power P2 is a backup function in case the first power P1 of the lead battery 110 fails, and is therefore configured as a circuit capable of charging the capacitor 12 in place of the lead battery 110. The switch 16 is inserted between the lead battery 110 and the capacitor 12 and regulates the power input and output between them.

[0020] The cell voltage measurement IC (hereinafter also referred to as "CCIC") 17 not only measures the cell voltages of the multiple cells that make up the lithium-ion battery 120, but many also function as a cell controller that equalizes the voltages of each cell. The CCIC 17 is charged to a high voltage, but its high-voltage section is insulated by the isolated photocouplers 5 and 6 and the isolated communication IC 7 while exchanging control signals with the MPU 13. This circuit configuration also protects the 7V-powered single-chip microcontroller from high-voltage shocks.

[0021] The DC-DC converter 11 can output a second power P2 from the lithium ion battery 120 to the relay 102 as a backup for the lead battery 110. The second power P2 is power for keeping the relay 102 ON as a backup for a failed lead battery 110. The voltage of the second power P2 is, for example, 10 to 11 V.

[0022] The capacitor 12 is charged by the lead battery 110 and is configured to output a third power P3 to the relay 102. The third power P3 is power for keeping the relay 102 ON, which serves as a backup for the failed lead battery 110 until the DC-DC converter 11 is started up. The voltage of the third power P3 is, for example, 10.5 to 11 V. The switch 16 regulates the input and output of power to the capacitor 12. The MPU 13 controls the operations of the DC-DC converter 11, the switch 16, and the lithium-ion battery 120.

[0023] For example, a nickel-metal hydride battery may be used instead of the lithium ion battery 120. Furthermore, for example, a nickel-metal hydride battery or an alkaline battery may be used instead of the lead battery 110.

[0024] The operation of the power supply control device 10 will be described with reference to Figures 1 and 2. Figure 2 is a graph showing the charging (boosting) and discharging (stepping down) of the capacitor 12 that forms the third power supply in the power supply control device 10 of Figure 1. In a state in which the DC-DC converter 11 is turned off and the switch 16 is turned on to charge the capacitor 12, if the voltage of the second power P2 is equal to or higher than the first threshold V1, the MPU 13 turns off the switch 16 to stop charging the capacitor 12.

[0025] 2, the first threshold V1 is, for example, 11 V. When the voltage of the second power P2 is equal to or lower than a second threshold V2 (for example, 10.5 V) that is lower than the first threshold V1, the MPU 13 turns on the switch 16 to resume charging of the capacitor 12.

[0026] The power supply control device 10 has a circuit as shown in FIG. 1 configured so that the second power P2 supplied from the lithium ion battery 120 can charge the capacitor 12 as a backup function in case the lead battery 110 fails.

[0027] Furthermore, if the lead battery 110 that supplies the excitation current to the relay 102 fails due to a dead battery or the like, the third power P3 is instantaneously supplied to the lead battery 110 from the capacitor 12 that is connected to the OR circuit of the diodes 2 and 4 in place of the failed first power P1, thereby keeping the relay 102 in the ON state.

[0028] Furthermore, when the voltage of the second power P2 is equal to or lower than a third threshold V3 (for example, 10 V) that is lower than the second threshold V2, the MPU 13 turns on the DC-DC converter 11. Furthermore, when the first power P1 becomes equal to or lower than the third threshold V3, the MPU 13 turns on the DC-DC converter 11.

[0029] The notification unit 14 notifies of an abnormality in the lead battery 110 when the second power P2 is output for more than a predetermined time. An abnormality in the lead battery 110 may be, for example, a failure or a disconnection. The notification unit 14 outputs the abnormality via an output device such as a monitor or speaker mounted on the vehicle. The input unit 15 allows input for changing the first threshold value V1 to the second threshold value V2.

[0030] Unless the lead battery 110 fails or the like, the contacts of the relay 102 are always kept closed by the first power P1 from the lead battery 110. The first power P1 is power for keeping the relay 102 ON, and its voltage is set to 12 V. The lithium ion battery 120 can supply power to electrical equipment and the inverter 101 via the relay 102 in the ON state.

[0031] The lithium ion battery 120 outputs a second power P2 stepped down by the DC-DC converter 11 under the control of the MPU 13. The lithium ion battery 120 does not discharge to the DC-DC converter 11 until the lead battery 110 fails. The second power P2 is a power for keeping the relay 102 ON as a backup for the failed lead battery 110, and its voltage is set between 10 and 11 V.

[0032] The voltage value (10V to 11V) of the second power P2 is set lower than the voltage value (12V) of the first power P1. The path for supplying the excitation current to the relay 102 forms an OR circuit by connecting the cathodes of two diodes 2 and 4. The first power P1 is supplied to the anode of one diode 2 of this OR circuit, and the second power P2 is supplied to the anode of the other diode 4. Therefore, this OR circuit backs up the first power P1 with the second power P2, preventing a power outage of the excitation current of the relay 102.

[0033] The capacitor 12 is charged by the second power P2, which is the output of the DC-DC converter 11. The capacitor 12 outputs a third power P3 to the relay 102. The third power P3 is a power for keeping the relay 102 ON as a backup for the failed lead battery 110 until the DC-DC converter 11 starts up, and its voltage is set between 10.5 and 11 V.

[0034] The capacitor 12 is charged by the first power P1 of the lead battery 110 while the voltage is increased from the second threshold V2 of 10.5 V to the first threshold V1 of 11 V over a short period of time, for example, a few seconds. After that, the switch 16 is turned OFF under the control of the MPU 13, and the charging of the capacitor 12 with the first power P1 stops. Therefore, the capacitor 12 is discharged while the voltage is gradually decreased from the first threshold V1 of 11 V to the second threshold V2 of 10.5 V over a few minutes due to natural discharge or the like.

[0035] When the voltage value of capacitor 12 drops from 11 V of the first threshold V1 to 10.5 V of the second threshold V2, switch 16 is turned ON (restarted) under the control of MPU 13. As a result, capacitor 12 is again charged by first power P1 while the voltage is increased from 10.5 V of the second threshold V2 to 11 V of the first threshold V1 in a short period of time, for example, a few seconds.

[0036] For just these few seconds, discharge from the lead battery 110 to the capacitor 12 is resumed. For this reason, discharge from the lead battery 110 to the capacitor 12 is performed only for the short time while the voltage value of the capacitor 12 rises from 10.5 V to 11 V.

[0037] When the first power P1 is cut off due to a failure of the lead battery 110, first, the third power P3 is supplied from the capacitor 12 to the relay 102. Next, the second power P2 is supplied from the DC-DC converter 11 to the relay 102. That is, for a short time until the DC-DC converter 11 starts up, the capacitor 12 functions as a backup power source for the lead battery 110. Thereafter, the lithium ion battery 120 functions as a backup power source for the lead battery 110.

[0038] 2, the DC-DC converter 11 will not start unless the lead battery 110 fails. Therefore, EMI noise caused by the operation of the DC-DC converter 11 will not be generated until the lead battery 110 fails, and unless the lead battery 110 fails, on-board devices such as radios and televisions mounted on the vehicle will not be affected by EMI noise.

[0039] On the other hand, even if a failure of the lead battery 110 causes noise to be mixed into the audio of the car radio being listened to, the vehicle cannot operate normally at that time, so this level of noise is considered to be within an acceptable range. Therefore, in such an abnormal situation, even if some noise is generated from the operating DC-DC converter 11, the actual harm is negligible.

[0040] Next, the operation and effects of the power supply control device 10 will be described. [1] The MPU 13 controls the ON / OFF of the DC-DC converter 11 and the switch 16 under the following conditions, as shown in Figure 2. When an abnormal situation is detected in this normal state, the MPU 13 transitions to states (1) to (4) as follows. Note that the voltages in parentheses are merely examples.

[0041] (1) Normally, the DC-DC converter 11 is turned off and the switch 16 is turned on, so that the capacitor 12 is continuously charged by the lead battery 110. (2) When the voltage of the third power supply is equal to or higher than the first threshold value V1 (11 V), the switch 16 is turned off to stop charging the capacitor 12. (3) When the voltage of the third power supply is equal to or lower than the second threshold V2 (10.5 V) which is lower than the first threshold V1 (11 V), the switch 16 is turned ON to restart charging of the capacitor 12. (4) When the voltage of the third power supply is equal to or lower than a third threshold V3 (10V) that is lower than the second threshold V2 (10.5V), the DC-DC converter 11 is turned on.

[0042] In the normal states (1) to (3), the MPU 13 of the power supply control device 10 alternates between normal charging states (1) and (3) and a normal charging pause state (2), thereby intermittently charging the capacitor 12 from the lead battery 110. Here, the circuit is configured so that the second power P2 supplied from the lithium ion battery 120 can charge the capacitor 12 instead of the lead battery 110, as a backup function in case the lead battery 110 fails unexpectedly due to a wire break or the like.

[0043] However, the third power P3 from the capacitor 12 can only be sustained for a few seconds at most. In response to this, the MPU 13 detects the abnormal state (4) and turns on the DC-DC converter 11. By turning on the DC-DC converter 11 in this way, the second power P2 is supplied from the lithium ion battery 120 without delay. As a result, the second power P2 is supplied from the lithium ion battery 120, which has sufficient capacity.

[0044] The second power P2, which has a large capacity, replaces the first power P1 from the lead battery 110, and continues to energize the relay 102 to keep it in the ON state, drive the MPU 13, and drive the inverter 101 for a long period of time. A third threshold V3 (10V) is set for the lead battery 110 (12V to 13.8V) at a level that detects a failure of the battery. In the case of an electric vehicle, for example, this state would be an abnormal situation that requires immediate suspension of operation and repair at a repair shop.

[0045] If the DC-DC converter 11 were to be turned on only in this abnormal situation, the resulting electrical noise would be tolerable. In other words, during normal operation of a vehicle equipped with the power supply control device 10, the DC-DC converter 11 is always off, so no electrical noise is generated. Therefore, the power supply control device 10 can suppress electrical noise caused by the operation of the DC-DC converter 11 used as a component of the backup power supply.

[0046] [2] In the above [1], when the first power P1 becomes equal to or less than the third threshold V3 (10V), the MPU 13 turns on the DC-DC converter 11. With this configuration, the lead battery 110, which has suddenly failed due to a disconnection, can be backed up by the lithium ion battery 120. The third threshold V3 (10V) is set as a level at which a failure of the lead battery 110 (12V to 13.8V) is detected.

[0047] In addition to sudden failures, consider the case where a vehicle equipped with the power supply control device 10 is left unused for a long period of time, coupled with poor operational management, leading to an extremely dead battery due to deterioration of the lead battery over time. Even in such a case, a serious failure that would require considerable effort to repair can be avoided. Such a serious failure would occur when the first power P1 drops below 7V, causing the computer of the MPU 13, which is powered by that supply voltage, to shut down and reset.

[0048] [3] In the above [1] or [2], the power supply control device 10 is applied to a vehicle electrical system 100 equipped with a normally open type relay 102, which is highly versatile and configured so that the contacts are closed only when power is applied. In such a power supply control device 10, if a failure occurs in the electrical system, the ON state caused by the excitation of the relay 102 can no longer be maintained. The relay 102 is inserted between the lithium ion battery 120 and the inverter 101, and is basically safe because it interrupts the main current, for example, a large DC current, by normally open operation.

[0049] [4] In the above [1] or [2], the power supply control device 10 may be applied to a vehicle electrical system 100 equipped with a normally closed type relay 102 (same reference numeral) that is configured so that its contacts open only when power is applied. Such a power supply control device 10 can be easily realized by reprogramming the MPU 13 to output a reversed relay control logic. Alternatively, this can be easily realized by reconfiguring the circuit to reverse the ON / OFF operation using the excitation drive circuit with the transistor 8, or by inserting a NOT operation circuit (not shown) to reverse the ON / OFF operation of the excitation circuit.

[0050] Furthermore, the operation type of the relay 102 (same symbol) may be a latch type, which can maintain operation after switching without an excitation current by inputting only a switching signal. In this case, an excitation drive circuit is not required, and the relay control logic of the MPU 13 can be modified by outputting only a switching signal and monitoring the ON / OFF state of the relay 102 by the MPU 13. In this way, the power supply control device 10 can be applied to a wide range of embodiments without limiting the operation type of the relay 102.

[0051] [5] In any of the above [1] to [4], the power supply control device 10 further includes a notification unit 14 that notifies predetermined information. When the second power P2 of the DC-DC converter 11 is output for a predetermined time or longer, the notification unit 14 notifies, for example, a vehicle occupant that an abnormality has occurred in the lead battery 110. With this configuration, for example, a vehicle occupant can recognize that an abnormality has occurred in the lead battery 110.

[0052] Furthermore, the vehicle occupant can take action such as consulting a vehicle repair shop when an abnormality occurs in the lead battery 110. If the normal state continues and there is no abnormality in the lead battery 110, the second power P2 is not output from the lithium ion battery 120. On the other hand, if an abnormality occurs in the lead battery 110, the notification unit 14 will notify the vehicle occupant, for example, so that the vehicle occupant can discover the abnormality early and prevent the situation from becoming serious.

[0053] [6] In any of the above [1] to [5], the MPU 13 operates on the first power P1. The MPU 13 is often a one-chip microcomputer with a minimum drive power of 7V, for example. Also, the first power P1 of the lead battery 110 is often supplied from a 13.8V lead battery. In such a case, the second power P2 from the lithium ion battery 120 (for example, 40V) is too high a voltage to drive the MPU 13 (for example, about 10V), and therefore a DC voltage conversion function is required.

[0054] Therefore, the power supply control device 10 directly operates the MPU 13 using the first power P1, which does not require the intervention of a DC voltage conversion function, which is simpler and easier. As a result, the power supply control device 10 can reduce the opportunities for the DC-DC converter 11 to operate, thereby suppressing electrical noise caused by that operation.

[0055] The power supply control device 10 configured as described above can be operated by the lead battery 110 without receiving power from the lithium ion battery 120 unless the lead battery 110 fails. As a result, the DC-DC converter 11 operates less frequently, thereby suppressing electrical noise caused by its operation.

[0056] [7] In any of the above [1] to [6], the device further includes an input unit 15 that can change at least one of the first threshold V1 (11 V), the second threshold V2 (10.5 V), and the third threshold V3 (10 V). With this configuration, at least one of the first threshold V1, the second threshold V2, and the third threshold V3 can be changed in consideration of the frequency of ON / OFF control of the DC-DC converter 11 by the MPU 13, etc. The advantages of changing this are as follows.

[0057] If the power supply control device 10 changes the threshold value to a lower value, the DC-DC converter 11 operates less frequently, thereby suppressing electrical noise caused by the operation of the DC-DC converter 11. In this way, the threshold value can be changed to a lower value if the conditions are met to ease the backup system for the lead battery 110 while maintaining the availability of the inverter 101.

[0058] The following are examples of conditions that may be considered to relax the backup system for the lead battery 110. Current EVs and the like are equipped with not only the lithium-ion battery 120 but also the lead battery 110, which has a much lower voltage and smaller capacity. This lead battery 110 is still indispensable as a power source for electrical components other than the main motor, and although it may not be possible to reduce its use suddenly, it is possible that the degree of dependence on it may be gradually reduced with expected technological innovation.

[0059] As a specific example of reducing the dependency, first, if not only the lights powered by the lead battery 110 are replaced with LEDs but also the relay 102 is replaced with a latching type, the excitation current becomes unnecessary, and energy saving for the lead battery 110 is promoted, thereby reducing the dependency on the battery. Also, since an EV does not have an internal combustion engine that generates heat, the installation environment of the lead battery 110 becomes low temperature. As a result, deterioration of the lead battery 110 is suppressed and reliability is improved.

[0060] Furthermore, it is conceivable that the lead battery 110 itself will become more highly functional. Alternatively, it is conceivable that the power supply voltage of in-vehicle electrical equipment will gradually be unified from the current rated output of 12V to 13.8V of the lead battery 110 to a voltage that matches the specifications of the lithium-ion battery 120. If the degree of dependence on the lead battery 110 is reduced in this way, it is preferable that the power supply control device 10 applied to an EV or the like allows a worker at a repair shop to change the above threshold value to a lower value via the input unit 15.

[0061] If we are currently in the midst of such technological innovation, it would be advisable to set the above thresholds as standard when the product to which the present invention is applied is first released, and then gradually lower the thresholds as the degree of dependence on lead battery 110 decreases over time. [Explanation of symbols]

[0062] 1 to 4: diodes, 5, 6: isolated photocouplers, 7: isolated communication IC, 8: transistor, 10: power supply control device, 11: DC-DC converter, 12: capacitor (an example of a third power supply), 13: MPU (an example of a control unit), 14: alarm unit, 15: input unit, 16: switch, 18: power supply IC, 19: IG terminal, 100: vehicle electrical system, 101: inverter (and other electrical equipment using wireless communication), 102: relay, 110: lead battery (an example of a first power supply), 120: lithium-ion battery (an example of a second power supply), P1: first power supply: power (voltage 12V) for keeping the relay 102 ON, P2: second power supply: power (voltage 10 to 11V) for keeping the relay 102 ON as a backup for the failed lead battery 110, P3 Third power: Power (voltage 10.5 to 11 V) used as a backup for the failed lead battery 110 until the DC-DC converter 11 starts up, to keep the relay 102 ON. V1: first threshold (11 V), V2: second threshold (10.5 V), V3: third threshold (10 V)

Claims

1. Electrical equipment and a relay connected to the electrical device; a first power source for enabling the relay; a second power source that energizes the electrical device via the relay; A power supply control device applied to a device including: a DC-DC converter that supplies power from the second power supply to the relay as a backup for the first power supply; a third power source that is charged by the first power source and outputs the charged power to the relay; a switch for the third power source; a control unit that controls the DC-DC converter, the switch, and the second power supply; and The control unit In a state where the DC-DC converter is turned off and the switch is turned on to charge the third power source, When the voltage of the third power supply is equal to or higher than a first threshold, the switch is turned off to stop charging of the third power supply; When the voltage of the third power source is equal to or lower than a second threshold value that is lower than the first threshold value, the switch is turned on to resume charging of the third power source; When the voltage of the third power supply is equal to or lower than a third threshold value that is lower than the second threshold value, the DC-DC converter is turned on. Power control device.

2. the control unit turns on the DC-DC converter when the voltage of the first power supply becomes equal to or lower than the third threshold. The power supply control device according to claim 1 .

3. Applied to the device having the relay configured to close contacts only when energized, The power supply control device according to claim 1 or 2.

4. Applied to the device having the relay configured such that the contacts open only when energized, The power supply control device according to claim 1 or 2.

5. Further comprising a notification unit that notifies predetermined information, The notification unit notifies of an abnormality in the first power supply when the DC-DC converter is turned on for a predetermined time or longer. The power supply control device according to claim 1 or 2.

6. The control unit is operated by the first power source. The power supply control device according to claim 1 or 2.

7. further comprising an input unit capable of changing at least one of the first threshold value, the second threshold value, and the third threshold value; The power supply control device according to claim 1 or 2.

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