Power supply device

Abstract

A control circuit (24) of a power supply device (10) forms a state in which an auxiliary power supply (22) is connected to a main power supply (11) via a charging circuit (21) when a power switch (13) provided on a power feeding path is turned on. The control circuit (24) calculates the internal resistance of the auxiliary power supply (22) on the basis of the charging current (I). When the power switch (13) is turned off, the control circuit (24) forms a state in which the power supply device (10) is disconnected from the main power source (11) and the power feeding object (12) and only the auxiliary power source (22) and the booster circuit (23) are connected to each other. When the terminal voltage (V2) of the auxiliary power supply (22) is less than a stop determination threshold value, the control circuit (24) disconnects the auxiliary power supply (22) from the booster circuit (23).

Description

Technical Field

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

[0002] A power supply device is known that feeds backup power to a power feeding object by using an auxiliary power supply when a main power supply fails. For example, a power supply device described in Japanese Unexamined Patent Application Publication No. 2023-18841 is provided in a power feeding path between a main power supply of a vehicle and a steering control device. The power supply device includes an auxiliary power supply and a charging circuit. For example, the auxiliary power supply is a lithium ion capacitor. The charging circuit is a circuit for charging the auxiliary power supply. The charging circuit includes a boost circuit that increases the output voltage of the main power supply. Summary of the invention

[0003] In the power supply device described in JP 2023-18841A, degradation diagnosis is performed in some cases. For example, the internal resistance of the auxiliary power supply during charging is calculated, and the degree of degradation of the auxiliary power supply is determined based on the calculated internal resistance. In order to ensure the reliability of the diagnosis, it is necessary to ensure the calculation accuracy of the internal resistance.

[0004] According to one aspect of the present disclosure, a power supply device includes: an auxiliary power supply of a main power supply for supplying power to a power-fed object; a charging circuit provided in a charging path between the main power supply and the auxiliary power supply, the charging circuit being configured to charge the auxiliary power supply by using power from the main power supply; a booster circuit provided in a discharge path between the auxiliary power supply and the power-fed object, the booster circuit being configured to boost an output voltage of the auxiliary power supply; and a control circuit configured to control the opening and closing of the charging path and the opening and closing of the discharge path. The control circuit is configured to: when a power switch provided in a power feeding path between the main power supply and the power-fed object is turned on, form a state in which the auxiliary power supply is connected to the main power supply via the charging circuit, and calculate an internal resistance of the auxiliary power supply based on a charging current supplied from the charging circuit to the auxiliary power supply. The control circuit is configured to: when the power switch is turned off, form a state in which the power supply device is disconnected from the main power supply and the power-fed object and only the auxiliary power supply and the booster circuit are connected to each other, and when the voltage of the auxiliary power supply is less than a stop determination threshold, disconnect the auxiliary power supply from the booster circuit.

[0005] According to this configuration, the voltage of the auxiliary power supply becomes lower than the stop determination threshold value when the power switch is turned on next time. Therefore, sufficient charging current flows from the charging circuit to the auxiliary power supply. Therefore, the calculation accuracy of the internal resistance can be ensured.

[0006] In the above-mentioned power supply device, the control circuit can be configured such that: by forming a state in which the auxiliary power supply and the boost circuit are connected to each other when the power switch is turned on, the control circuit is supplied with power from the main power supply and supplied with power from the boost circuit, and the control circuit is configured such that the control circuit is continuously supplied with power from the boost circuit during a time period when the power switch is turned off until the voltage of the auxiliary power supply becomes less than a stop determination threshold.

[0007] According to this configuration, even when the power supply from the main power source to the control circuit is stopped due to the turning off of the power switch, the power from the booster circuit is supplied to the control circuit. Therefore, the control circuit can continue to operate by consuming the power from the booster circuit.

[0008] In the above-mentioned power supply device, when the power switch is turned on again during the time period from when the power switch is turned off until the voltage of the auxiliary power supply becomes less than the stop judgment threshold, the control circuit can be configured not to perform the calculation of the internal resistance of the auxiliary power supply when the charging current is less than the current threshold.

[0009] If a sufficient charging current does not flow, there is a risk that the calculation accuracy of the internal resistance of the auxiliary power supply cannot be ensured. According to the above configuration, unnecessary internal resistance calculation for which the calculation accuracy cannot be ensured can be avoided.

[0010] In the above power supply device, when the power switch is turned on, the control circuit may be configured not to calculate the internal resistance of the auxiliary power supply if the voltage of the auxiliary power supply is not less than the stop determination threshold.

[0011] When the voltage of the auxiliary power supply is not less than the stop determination threshold, there is a risk that insufficient charging current flows, making it impossible to ensure the calculation accuracy of the internal resistance of the auxiliary power supply. According to the above configuration, unnecessary internal resistance calculation without ensuring calculation accuracy can be avoided.

[0012] In the above-mentioned power supply device, the power feeding object may include a control device of a vehicle. A higher operational reliability is required for the control device of the vehicle. The above-mentioned power supply device is suitable for the control device of the vehicle.

[0013] According to the power supply device of the present disclosure, it is possible to ensure the calculation accuracy of the internal resistance of the auxiliary power source. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0015] Figure 1 is a circuit diagram of a power supply device according to one embodiment;

[0016] Figure 2 is a circuit diagram of an auxiliary power supply during non-charging according to an embodiment;

[0017] Figure 3 is a circuit diagram of an auxiliary power supply during charging according to one embodiment; and

[0018] Figure 4 is a graph showing a voltage increase of an auxiliary power source when charging starts according to an embodiment. DETAILED DESCRIPTION

[0019] In the following, an embodiment of a power supply device is described. Figure 1 As shown, the power supply device 10 is provided on a power feeding path between a main power source 11 and a power feeding object 12. For example, the main power source 11 is a battery. The power feeding object 12 is, for example, a control device of a vehicle, which operates by consuming the power supplied via the power supply device 10. The control device is, for example, a steering control device, which controls a motor as a driving source of a steering system of the vehicle. An example of a steering system is an electric power steering system or a steer-by-wire steering system.

[0020] The power feeding path includes a first power line L1 and a second power line L2. The second power line L2 branches from a first connection point P1 provided in the first power line L1. The first connection point P1 is provided between the main power source 11 and the power switch 13 in the first power line L1.

[0021] The power of the main power source 11 is supplied to, for example, a circuit of a power system of the power-fed object 12 via the first power supply line L1. For example, the circuit of the power system is a circuit that handles a large power, and includes an inverter that converts the DC power of the main power source 11 into AC power and other devices, etc. The power of the main power source 11 is also supplied to, for example, a circuit of a control system of the power-fed object 12 via the second power supply line L2. The circuit of the control system is, for example, a circuit for controlling a motor, and includes a processing circuit such as a microcomputer.

[0022] In the first power line L1, a power switch 13 is provided between the power supply device 10 and the main power supply 11. The power switch 13 includes, for example, an ignition switch and is operated when the vehicle starts running. By operating the power switch 13, the energization of the first power line L1 is switched between on and off.

[0023] The first power line L1 and the second power line L2 constitute a power feeding path between the main power source 11 and the power-fed object 12 .

[0024] Configuration of the power supply device 10

[0025] Next, the following describes the configuration of the power supply device 10. The power supply device 10 includes a charging circuit 21, an auxiliary power supply 22, a boost circuit 23, and a control circuit 24. The power supply device 10 also includes first to fifth switches 31 to 35, a first voltage sensor 41, a second voltage sensor 42, and a current sensor 43.

[0026] The charging circuit 21 is a circuit that charges the auxiliary power supply 22 using power from the main power supply 11. An input terminal of the charging circuit 21 is connected to a second connection point P2 provided in the second power supply line L2 via a third power supply line L3. An output terminal of the charging circuit 21 is connected to the auxiliary power supply 22 via a fourth power supply line L4.

[0027] The auxiliary power supply 22 is a power storage device capable of charging and discharging electric charge, and may include a lithium ion capacitor or a lithium ion battery as an example of the auxiliary power supply. The voltage of the auxiliary power supply 22 is set to be lower than the voltage of the main power supply 11. Both the voltage of the auxiliary power supply 22 and the voltage of the main power supply 11 are terminal voltages and actual output voltages thereof.

[0028] The boost circuit 23 is a circuit for increasing the output voltage of the auxiliary power supply 22. For example, the boost circuit 23 increases the output voltage of the auxiliary power supply 22 to a voltage that is higher than the terminal voltage of the auxiliary power supply 22 and lower than the terminal voltage of the main power supply 11. The input terminal of the boost circuit 23 is connected to the auxiliary power supply 22 via the fifth power line L5. The boost circuit 23 has two output terminals. The first output terminal of the boost circuit 23 is connected to the third connection point P3 provided in the first power line L1 via the sixth power line L6. The second output terminal of the boost circuit 23 is connected to the fourth connection point P4 provided in the second power line L2 via the seventh power line L7. The fourth connection point P4 is provided between the second connection point P2 in the second power line L2 and the power feeding object 12.

[0029] The first switch 31 is provided in the third power line L3. The first switch 31 opens and closes the third power line L3. The second switch 32 is provided in the fourth power line L4. The second switch 32 opens and closes the fourth power line L4. The third switch 33 is provided in the fifth power line L5. The third switch 33 opens and closes the fifth power line L5. The fourth switch 34 is provided in the sixth power line L6. The fourth switch 34 opens and closes the sixth power line L6. The fifth switch 35 is provided in the seventh power line L7. The fifth switch 35 opens and closes the seventh power line L7.

[0030] The first voltage sensor 41 is provided between the power switch 13 in the first power line L1 and the third connection point P3. The first voltage sensor 41 detects the voltage V1 generated in the first power line L1. The second voltage sensor 42 is provided between the second switch 32 in the fourth power line L4 and the auxiliary power supply 22. The second voltage sensor 42 detects the terminal voltage V2 of the auxiliary power supply 22. The terminal voltage V2 is the voltage actually output from the auxiliary power supply 22. The current sensor 43 is provided between the charging circuit 21 and the second switch 32 in the fourth power line L4. The current sensor 43 detects the current generated in the fourth power line L4, that is, the charging current I of the auxiliary power supply 22. The charging current I is the current supplied to the auxiliary power supply 22 when the auxiliary power supply 22 is charged.

[0031] The control circuit 24 is connected to a fifth connection point P5 provided in the sixth power line L6 via the eighth power line L8. The fifth connection point P5 is provided between the fourth switch 34 in the sixth power line L6 and the boost circuit 23. The control circuit 24 controls the on and off of the first to fifth switches 31 to 35. The control circuit 24 detects the on and off of the power switch 13 based on the voltage V1 detected by the first voltage sensor 41. The control circuit 24 monitors the voltage of the main power supply 11. When the value of the voltage VB of the main power supply 11 is less than a predetermined voltage threshold, the control circuit 24 determines that the voltage VB of the main power supply 11 becomes low. The voltage threshold is a reference for determining that the voltage of the main power supply 11 is reduced.

[0032] The third power line L3 and the fourth power line L4 constitute a charging path between the main power source 11 and the auxiliary power source 22. The fifth power line L5, the sixth power line L6, and the seventh power line L7 constitute a discharging path between the auxiliary power source 22 and the power-fed object 12. The control circuit 24 controls the opening and closing of the charging path and the discharging path by controlling the on and off of the first to fifth switches 31 to 35.

[0033] Operation of the power supply device 10

[0034] Next, a description is given of the operation of the power supply device 10. As an initial state, the power switch 13 and the first to fifth switches 31 to 35 are turned off.

[0035] When the power switch 13 is turned on, the power from the main power supply 11 is supplied via the first power line L1 to the circuit of the control system of the power-fed object 12. When the power switch 13 is turned on, the power from the main power supply 11 is also supplied via a power line not shown to the control circuit 24. Regardless of whether the power switch 13 is turned on or off, the power from the main power supply 11 is supplied to the circuit of the power system of the power-fed object 12 via the second power line L2.

[0036] When the power switch 13 is turned on, the control circuit 24 turns on the first to fourth switches 31 to 34 while keeping the fifth switch 35 in the off state. Thus, the auxiliary power supply 22 is charged with power from the main power supply 11 via the charging circuit 21. For example, the charging circuit 21 controls charging while monitoring the charging current and the charging voltage.

[0037] The boost circuit 23 increases the output voltage of the auxiliary power supply 22. When the voltage VB of the main power supply 11 is not reduced, the voltage V3 increased by the boost circuit 23 is lower than the voltage VB of the main power supply 11. Therefore, the voltage V3 increased by the boost circuit 23 is not supplied to the circuit of the control system of the power feeding object 12 via the sixth power line L6 and the first power line L1. Between the third connection point P3 in the sixth power line L6 and the fourth switch 34, a first diode not shown for preventing reverse current is provided. The first diode prevents power from flowing from the main power supply 11 to the boost circuit 23 via the first power line L1 and the sixth power line L6. The voltage increased by the boost circuit 23 is supplied to the control circuit 24 via the eighth power line L8.

[0038] On the other hand, when the voltage VB of the main power source 11 decreases, the power from the boost circuit 23 is immediately supplied to the circuit of the control system of the power-fed object 12 via the sixth power line L6 and the first power line L1. This is because, as the voltage VB of the main power source 11 decreases, the voltage V3 boosted by the boost circuit 23 becomes higher than the voltage of the main power source 11, and thus higher than the voltage generated in the first power line L1. Therefore, even when the power feeding from the main power source 11 to the power-fed object 12 is interrupted, the backup power is fed to the circuit of the control system of the power-fed object 12 by the auxiliary power source 22.

[0039] A second diode not shown for preventing reverse current is provided between the first voltage sensor 41 and the third connection point P3 in the first power line L1. The second diode prevents power from flowing from the booster circuit 23 to the main power supply 11 via the sixth power line L6 and the first power line L1.

[0040] When the voltage VB of the main power supply 11 decreases, the control circuit 24 turns on the fifth switch 35. As a result, the power from the boost circuit 23 is supplied to the circuit of the power system of the power-fed object 12 via the seventh power line L7 and the second power line L2. This is because, as the voltage VB of the main power supply 11 decreases, the voltage V3 boosted by the boost circuit 23 becomes higher than the voltage of the main power supply 11, and thus higher than the voltage generated in the second power line L2. Therefore, even when the power feeding from the main power supply 11 to the power-fed object 12 is interrupted, the backup power is fed to the circuit of the power system of the power-fed object 12 by the auxiliary power supply 22.

[0041] A third diode not shown for preventing reverse current is provided between the second connection point P2 and the fourth connection point P4 in the second power line L2. The third diode prevents power from flowing from the booster circuit 23 to the main power source 11 via the seventh power line L7 and the second power line L2.

[0042] Deterioration diagnosis process of auxiliary power supply 22

[0043] The control circuit 24 diagnoses degradation of the auxiliary power source 22 during charging of the auxiliary power source 22. When the power switch 13 is turned on, the control circuit 24 determines the degree of degradation of the auxiliary power source 22 based on the internal resistance of the auxiliary power source 22 during charging. This is based on the fact that the internal resistance of the auxiliary power source 22 increases as the auxiliary power source 22 becomes degraded. The internal resistance is the resistance inside the auxiliary power source 22.

[0044] like Figure 2 As shown, the auxiliary power supply 22 can be provided by an electromotive force V s With internal resistance R s The electromotive force V s is the theoretical voltage of the auxiliary power supply 22. When the auxiliary power supply 22 is not charged, that is, when there is no charging current supplied from the charging circuit 21 to the auxiliary power supply 22, no resistance R s Therefore, the terminal voltage V2 of the auxiliary power supply 22 is theoretically equal to the electromotive force V s The terminal voltage V2 is a voltage actually output from the auxiliary power supply 22 .

[0045] like Figure 3 As shown in FIG. 1 , when the auxiliary power source 22 is charged, that is, when the charging current I is supplied from the charging circuit 21 to the auxiliary power source 22, an increase in voltage proportional to the internal resistance Rs is generated. Therefore, during the charging of the auxiliary power source 22, the terminal voltage V2 of the auxiliary power source 22 becomes greater than the electromotive force V s The increased voltage ΔV is higher than the increased voltage ΔV. The increased voltage ΔV is the voltage of the auxiliary power source 22 corresponding to the increased amount generated by charging the auxiliary power source 22 .

[0046] like Figure 4 As shown, regardless of the charging method using the charging circuit 21, when charging of the auxiliary power supply 22 starts (time T1), the terminal voltage V2 of the auxiliary power supply 22 immediately rises. Thereafter, the terminal voltage V2 gradually increases as charging proceeds, and finally remains at a constant voltage.

[0047] The voltage increase ΔV of the auxiliary power source 22 during charging is expressed by the following equation (1). The symbol "·" in equation (1) indicates multiplication.

[0048] ΔV=I·Rs (1)

[0049] The terminal voltage V2 of the auxiliary power source 22 during charging is expressed by the following equation (2).

[0050] V2=V s +ΔV (2)

[0051] Internal resistance R s It is expressed by the following formula (3). Formula (3) is obtained according to the above formula (1). The symbol " / " in formula (3) indicates division.

[0052] R s =ΔV / I (3)

[0053] The control circuit 24 calculates the internal resistance R of the auxiliary power supply 22 by using equation (3): s For example, when the calculated internal resistance R s When the resistance is greater than a predetermined resistance threshold, the control circuit 24 determines that the auxiliary power source 22 is degraded. When determining that the auxiliary power source 22 is degraded, the control circuit 24 performs a predetermined process. The process includes, for example, visually or audibly notifying the user of the vehicle of the deterioration of the auxiliary power source 22.

[0054] However, when the deterioration diagnosis of the auxiliary power source 22 is performed during the charging of the auxiliary power source 22, there is the following problem. That is, when the auxiliary power source 22 is almost fully charged, a sufficient charging current I does not flow, so that the signal-to-noise ratio (SN ratio) of the current sensor 43 decreases, which may make it impossible to ensure that the internal resistance R of the auxiliary power source 22 is within the range of 100 Hz. s Therefore, in this embodiment, in order to ensure the internal resistance R of the auxiliary power supply 22 s The control circuit 24 performs the following processing in order to obtain the calculation accuracy.

[0055] Ensure that the internal resistance R s The calculation accuracy of

[0056] When the power switch 13 is turned off, the control circuit 24 turns off the first switch 31, the second switch 32, the fourth switch 34, and the fifth switch 35. In other words, the control circuit 24 keeps only the third switch 33 in the on state. Therefore, the power from the auxiliary power supply 22 is continuously supplied to the boost circuit 23. As a result, the boost circuit 23 continues to operate. As the power of the auxiliary power supply 22 is consumed by the boost circuit 23, the charge amount of the auxiliary power supply 22 gradually decreases. As the charge amount decreases, the terminal voltage V2 of the auxiliary power supply 22 decreases.

[0057] The control circuit 24 operates by consuming the electric power supplied from the booster circuit 23 via the eighth power supply line L8. The control circuit 24 determines whether the following formula (4) is satisfied.

[0058] V2 <V th (4)

[0059] Among them, "V th " is the stop determination threshold. The stop determination threshold V th is a reference for determining whether to completely stop the operation of the power supply device 10. For example, the stop determination threshold V is set based on the following terminal voltage V2 of the auxiliary power source 22. th : At this terminal voltage V2, the charging current I is expected to flow sufficiently when the auxiliary power source 22 is charged next time.

[0060] When the above formula (4) is not satisfied, that is, when the terminal voltage V2 of the auxiliary power supply 22 is equal to or greater than the stop determination threshold V th When the voltage is turned on, the control circuit 24 only keeps the third switch 33 in the on state. The power of the auxiliary power supply 22 is continuously consumed by the boost circuit 23.

[0061] When the above formula (4) is satisfied, that is, when the terminal voltage V2 of the auxiliary power supply 22 is less than the stop determination threshold V th , the control circuit 24 turns off the third switch 33. As a result, the power supply from the auxiliary power supply 22 to the boost circuit 23 stops, and thus the operation of the boost circuit 23 stops. When the operation of the boost circuit 23 stops, the power supply from the boost circuit 23 to the control circuit 24 via the eighth power line L8 stops. Therefore, the operation of the control circuit 24 also stops. In other words, the operation of the power supply device 10 stops completely.

[0062] Thereafter, when the power switch 13 is turned on again, the control circuit 24 turns on the first to fourth switches 31 to 34 while keeping the fifth switch 35 in the off state. The control circuit 24 calculates the internal resistance R of the auxiliary power supply 22 by using the above formula (3) based on the charging current I detected by the current sensor 43 and the terminal voltage V2 of the auxiliary power supply 22 detected by the second voltage sensor 42. s Since the terminal voltage V2 of the auxiliary power supply 22 decreases to less than the stop determination threshold V th At the level of , sufficient charging current I flows from the charging circuit 21 to the auxiliary power supply 22. Therefore, it is possible to ensure that the internal resistance R s The calculation accuracy of .

[0063] Advantageous Effects of Implementation Methods

[0064] This embodiment achieves the following beneficial effects. When the power switch 13 is turned on, the control circuit 24 turns on the first switch 31 and the second switch 32 to form a state where the auxiliary power supply 22 is connected to the main power supply 11 via the charging circuit 21. The control circuit 24 calculates the internal resistance R of the auxiliary power supply 22 based on the charging current I supplied from the charging circuit 21 to the auxiliary power supply 22.s When the power switch 13 is turned off, the control circuit 24 turns off the first switch 31, the fourth switch 34, and the fifth switch 35 to disconnect the power supply device 10 from the main power supply 11 and the power feeding object 12. In addition, the control circuit 24 turns off the second switch 32 while keeping the third switch 33 in the on state to form a state in which only the auxiliary power supply 22 and the boost circuit 23 are connected to each other. When the terminal voltage V2 of the auxiliary power supply 22 becomes less than the stop determination threshold V th When the control circuit 24 turns off the third switch 33, the auxiliary power supply 22 is disconnected from the boost circuit 23.

[0065] According to this configuration, the next time the power switch 13 is turned on, the terminal voltage V2 of the auxiliary power supply 22 decreases to a value less than the stop determination threshold value V th Therefore, sufficient charging current I flows from the charging circuit 21 to the auxiliary power supply 22. Therefore, the internal resistance R of the auxiliary power supply 22 can be ensured. s In addition, at the timing when the degradation diagnosis of the auxiliary power source 22 is required, the degradation diagnosis of the auxiliary power source 22 can be appropriately performed before the vehicle travels. The reliability of the degradation diagnosis can also be ensured.

[0066] After the power switch 13 is turned off, the power of the auxiliary power supply 22 consumed by the boost circuit 23 is small. Therefore, the terminal voltage V2 of the auxiliary power supply 22 decreases to a value less than the stop determination threshold value V th However, the terminal voltage V2 of the auxiliary power source 22 is adjusted when the vehicle is not in use (for example, when it is parked). Therefore, the adjustment of the terminal voltage V2 of the auxiliary power source 22 does not affect the operation of the vehicle system.

[0067] When the power switch 13 is turned on, sufficient charging current I flows. Therefore, the amount of reduction in the SN ratio (signal-to-noise ratio) of the current sensor 43 is reduced, thereby reducing the reduction in the detection accuracy of the current sensor 43. Therefore, a high-precision current sensor 43 is not required.

[0068] When the power switch 13 is turned on, the power from the main power supply 11 is supplied to the control circuit 24. When the power switch 13 is turned on, the control circuit 24 turns on the third switch 33 to form a state in which the auxiliary power supply 22 and the booster circuit 23 are connected to each other. Therefore, the power from the booster circuit 23 is supplied to the control circuit 24. In addition, the power supply 22 is stopped from the time when the power switch 13 is turned off until the terminal voltage V2 of the auxiliary power supply 22 becomes less than the stop determination threshold value V thDuring the time period, the power from the boost circuit 23 is continuously supplied to the control circuit 24. Therefore, even when the power supply from the main power supply 11 to the control circuit 24 is stopped due to the turning off of the power switch 13, the control circuit 24 can continue to operate by consuming the power from the boost circuit 23.

[0069] When the auxiliary power source 22 is discharged, that is, when current is output from the auxiliary power source 22, a current is generated that is proportional to the internal resistance R s Therefore, when the auxiliary power supply 22 is discharged, the terminal voltage V2 of the auxiliary power supply 22 becomes greater than the electromotive force V s The dropped voltage is the voltage of the auxiliary power source 22 corresponding to the drop amount caused by the discharge of the auxiliary power source 22. On the other hand, when the auxiliary power source 22 is not discharged, that is, when no current is output from the auxiliary power source 22, no current is caused to flow into the auxiliary power source 22. s Therefore, the terminal voltage V2 of the auxiliary power supply 22 is equal to the electromotive force V s .

[0070] Therefore, it is also possible to calculate the internal resistance R of the auxiliary power source 22 during the discharge period. s to determine the degree of degradation of the auxiliary power supply 22. However, in order to ensure that the internal resistance R s In order to ensure the calculation accuracy of the auxiliary power source 22 and thereby ensure the determination accuracy of the degree of degradation of the auxiliary power source 22, it is necessary to allow a certain amount of discharge current to flow. For this purpose, the power supply device 10 is provided with a current path including, for example, special components such as a large-capacity discharge resistor. Providing a current path may result in an increase in the size of the power supply device 10 or an increase in product cost. In this regard, based on the internal resistance R of the auxiliary power source 22 during charging, the current path may be increased. s The special components involved in the discharge are not required to determine the degree of degradation of the auxiliary power source 22. This is advantageous in terms of the size or product cost of the power supply device 10.

[0071] The power feeding object 12 includes a control device of a vehicle. A higher operational reliability is required for the control device of a vehicle. The power supply device 10 of the present embodiment is suitable for use in a control device of a vehicle.

[0072] Other Implementations

[0073] The present embodiment can be implemented by the following modification. When the power switch 13 is turned off, the terminal voltage V2 of the auxiliary power supply 22 becomes smaller than the stop determination threshold V th During the time period, when the power switch 13 is turned on again, when the charging current I is less than the current threshold, the control circuit 24 may not calculate the internal resistance R of the auxiliary power supply 22. s Through experiments or simulations, the current threshold is set to the expected value to ensure that the internal resistance R sWhen insufficient charging current I flows, the internal resistance R of the auxiliary power source 22 may not be ensured. s According to the above configuration, unnecessary internal resistance calculations that cannot ensure calculation accuracy can be avoided.

[0074] When the power switch 13 is turned on, the terminal voltage V2 of the auxiliary power supply 22 is not less than the stop determination threshold V th When the control circuit 24 does not need to calculate the internal resistance R of the auxiliary power supply 22 s When the terminal voltage V2 of the auxiliary power supply 22 is not less than the stop determination threshold V th When the charging current I is insufficient, there is a risk that the internal resistance R of the auxiliary power source 22 cannot be ensured. s According to the above configuration, unnecessary internal resistance R that cannot ensure calculation accuracy can be avoided. s Calculation.

Claims

1. A power supply device (10), characterized in that: include: An auxiliary power source (22) for a main power source (11) for supplying power to a power-fed object (12); a charging circuit (21) provided in a charging path between the main power source (11) and the auxiliary power source (22), the charging circuit (21) being configured to charge the auxiliary power source (22) by using power from the main power source (11); a booster circuit (23) provided in a discharge path between the auxiliary power source (22) and the power-fed object (12), the booster circuit (23) being configured to increase an output voltage of the auxiliary power source (22); as well as a control circuit (24) configured to control the opening and closing of the charging path and the opening and closing of the discharging path, The control circuit (24) is configured to: when a power switch (13) provided in a power feeding path between the main power supply (11) and the power feeding object (12) is turned on, establish a state in which the auxiliary power supply (22) is connected to the main power supply (11) via the charging circuit (21), and calculate an internal resistance of the auxiliary power supply (22) based on a charging current supplied from the charging circuit (21) to the auxiliary power supply (22), The control circuit (24) is configured such that: when the power switch (13) is turned off, the power supply device (10) is disconnected from the main power supply (11) and the power feeding object (12) and only the auxiliary power supply (22) and the boost circuit (23) are connected to each other; and when the voltage of the auxiliary power supply (22) is less than a stop determination threshold, the auxiliary power supply (22) is disconnected from the boost circuit (23).

2. The power supply device (10) according to claim 1, characterized in that: The control circuit (24) is configured to be supplied with power from the main power supply (11) and supplied with power from the boost circuit (23) by forming a state in which the auxiliary power supply (22) and the boost circuit (23) are connected to each other when the power switch (13) is turned on, and The control circuit (24) is configured to be continuously supplied with power from the boost circuit (23) during a period from when the power switch (13) is turned off until the voltage of the auxiliary power supply (22) becomes smaller than the stop determination threshold.

3. The power supply device (10) according to claim 1 or 2, characterized in that: In a case where the power switch (13) is turned on again during a period from when the power switch (13) is turned off until the voltage of the auxiliary power supply (22) becomes less than the stop determination threshold, the control circuit (24) is configured not to perform calculation of the internal resistance of the auxiliary power supply (22) when the charging current is less than the current threshold.

4. The power supply device (10) according to claim 1 or 2, characterized in that: When the power switch (13) is turned on, the control circuit (24) is configured not to calculate the internal resistance of the auxiliary power supply (22) if the voltage of the auxiliary power supply (22) is not less than the stop determination threshold.

5. The power supply device (10) according to claim 1 or 2, characterized in that: The power feeding object (12) includes a control device of a vehicle.

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