Power supply device

Abstract

To provide a power supply device capable of assuring reliability for degradation diagnosis.SOLUTION: A control circuit 24 calculates a first correction coefficient which decreases accompanying increase of charge current I or output current Idis, and a second correction coefficient which increases accompanying increase of electric power required to output to an auxiliary power supply 22. The control circuit 24 corrects an internal resistance to a corrected internal resistance according to a reference current value by multiplying the internal resistance of the auxiliary power supply 22 by the first correction coefficient, at the time of degradation diagnosis of the auxiliary power supply 22. The control circuit 24 corrects an internal resistance threshold value to an internal resistance threshold value according to the reference current value by multiplying the internal resistance threshold value by the second correction coefficient.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there is known a power supply device that uses an auxiliary power supply to back up power supply to a power supply target when the main power supply fails. For example, the power supply device of Patent Document 1 is provided in a power supply path between a main power supply and a steering control device of a vehicle. The power supply device has an auxiliary power supply and a charging circuit. The auxiliary power supply is, for example, a lithium ion capacitor. The charging circuit is a circuit for charging the auxiliary power supply. The charging circuit has a boost circuit that boosts the output voltage of the main power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-18841 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a power supply device such as that described in Patent Document 1, a deterioration diagnosis may be performed. For example, the internal resistance of the auxiliary power supply during charging is calculated, and the degree of deterioration of the auxiliary power supply is determined based on the calculated internal resistance. It is required for the power supply device to ensure the reliability of the deterioration diagnosis. [Means for solving the problem]

[0005] A power supply device that can solve the above problem includes an auxiliary power supply for a main power supply that supplies power to a power supply target, and a control circuit configured to control charging and discharging of the auxiliary power supply. The power supply device is configured such that the control circuit calculates an internal resistance of the auxiliary power supply based on a voltage change amount and a charging current value when the auxiliary power supply is charged, or a voltage change amount and a discharging current value when the auxiliary power supply is discharged, and diagnoses deterioration of the auxiliary power supply through a comparison between the calculated internal resistance and an internal resistance threshold value that is set according to a temperature of the auxiliary power supply. The control circuit calculates a first correction coefficient that decreases with an increase in the charging current or the discharging current, and a second correction coefficient that increases with an increase in power required to be output to the auxiliary power supply. When diagnosing deterioration of the auxiliary power supply, the control circuit is configured to correct the internal resistance to the corrected internal resistance corresponding to a reference current value by multiplying the internal resistance by the first correction coefficient, and to correct the internal resistance threshold value to the internal resistance threshold value corresponding to the reference current value by multiplying the internal resistance threshold value by the second correction coefficient.

[0006] According to this configuration, when diagnosing the deterioration of the auxiliary power supply, the internal resistance is corrected to a corrected internal resistance according to the reference current value, and the internal resistance threshold value is corrected to an internal resistance threshold value according to the reference current value. That is, the internal resistance and the internal resistance threshold value are standardized according to the reference current value. Therefore, in the same power supply device, the deterioration diagnosis of the auxiliary power supply can be appropriately performed whether the deterioration diagnosis of the auxiliary power supply is performed based on the charging current or the discharging current. Furthermore, even if the value of the current used to diagnose the auxiliary power supply differs depending on the specifications of the power supply device, such as when the power supply target is different, the deterioration diagnosis of the auxiliary power supply can be appropriately performed. The reliability of the deterioration diagnosis of the auxiliary power supply can also be ensured.

[0007] In the above power supply device, the pre-correction internal resistance threshold value may be set based on a pre-correction value of the internal resistance at which it becomes difficult for the auxiliary power supply to output the power required for the auxiliary power supply in accordance with the temperature of the auxiliary power supply.

[0008] With this configuration, it is possible to diagnose deterioration of the auxiliary power supply based on whether it is difficult for the auxiliary power supply to output the power required, depending on the temperature of the auxiliary power supply. In the above power supply device, the control circuit may be configured to calculate the first correction coefficient by using a first coefficient map that defines a relationship between the charging current and the first correction coefficient, and to calculate the second correction coefficient by using a second coefficient map that defines a relationship between the discharging current and the second correction coefficient.

[0009] According to this configuration, the control circuit can easily calculate the first correction coefficient based on the first coefficient map, and the control circuit can easily calculate the second correction coefficient based on the second coefficient map.

[0010] In the above power supply device, the control circuit may be configured to calculate the pre-correction internal resistance threshold value using an internal resistance threshold value map that defines the relationship between the temperature of the auxiliary power supply and the pre-correction internal resistance threshold value.

[0011] According to this configuration, the control circuit can easily calculate the internal resistance threshold value before correction based on the internal resistance threshold value map. In the above power supply device, the power supply target may include a control device of a vehicle.

[0012] Vehicle control devices are required to have high operational reliability, and the above-described power supply device is suitable for use in vehicle control devices. Effect of the Invention

[0013] According to the power supply device of the present invention, the reliability of the degradation diagnosis can be ensured. [Brief description of the drawings]

[0014] [Figure 1] 1 is a circuit diagram of a power supply device according to an embodiment; [Diagram 2] FIG. 2 is a circuit diagram of an auxiliary power supply according to an embodiment when not charging. [Diagram 3] FIG. 2 is a circuit diagram of an auxiliary power supply during charging according to one embodiment. [Figure 4] 4 is a graph showing a voltage rise at the start of charging of an auxiliary power supply according to one embodiment. [Diagram 5] 1 is a graph illustrating a first coefficient map according to an embodiment. [Figure 6] 1 is a graph showing an internal resistance threshold map according to an embodiment. [Figure 7] 11 is a graph illustrating a second coefficient map according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of a power supply device will be described below. As shown in Fig. 1, a power supply device 10 is provided in a power supply path between a main power supply 11 and a power supply target 12. The main power supply 11 is, for example, a battery. The power supply target 12 is, for example, a vehicle control device that operates by consuming power supplied via the power supply device 10. The control device is, for example, a steering control device that controls a motor that is a drive source for a steering device of the vehicle. Examples of steering devices include an electric power steering device or a steer-by-wire type steering device.

[0016] The power supply path includes a first power line L1 and a second power line L2. The second power line L2 branches off from a first connection point P1 set on the first power line L1. The first connection point P1 is set between the main power supply 11 and the power switch 13 on the first power line L1.

[0017] The power of the main power supply 11 is supplied, for example, to an electric circuit of a power system of the power supply target 12 via a first power supply line L1. The electric circuit of the power system is a circuit that handles larger power, and includes, for example, an inverter that converts the DC power of the main power supply 11 into AC power. Moreover, the power of the main power supply 11 is supplied, for example, to an electric circuit of a control system of the power supply target 12 via a second power supply line L2. The electric circuit of the control system is, for example, a circuit for controlling a motor, and includes a processing circuit such as a microcomputer.

[0018] A power switch 13 is provided in the first power line L1 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 starting to run the vehicle. Through the operation of the power switch 13, the conduction of the first power line L1 is switched between on and off.

[0019] The first power line L1 and the second power line L2 form a power supply path between the main power supply 11 and the power supply target 12. <Configuration of power supply device 10> Next, the configuration of the power supply device 10 will be described.

[0020] The power supply device 10 has a charging circuit 21, an auxiliary power supply 22, a boost circuit 23, and a control circuit 24. The power supply device 10 also has first to fifth switches 31 to 35, a first voltage sensor 41, a second voltage sensor 42, a current sensor 43, and a temperature sensor 44.

[0021] The charging circuit 21 is a circuit for charging 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 set on 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.

[0022] Auxiliary power supply 22 is a power storage device capable of charging and discharging electric charge, and may be, for example, a lithium ion capacitor or a lithium ion battery. The voltage of auxiliary power supply 22 is set lower than the voltage of main power supply 11. The voltage of auxiliary power supply 22 and the voltage of main power supply 11 are each a terminal voltage, and are actual output voltages.

[0023] The boost circuit 23 is a circuit for boosting the output voltage of the auxiliary power supply 22. The boost circuit 23 boosts the output voltage of the auxiliary power supply 22 to, for example, a voltage higher than the terminal voltage of the auxiliary power supply 22 and lower than the terminal voltage of the main power supply 11. An input terminal of the boost circuit 23 is connected to the auxiliary power supply 22 via a fifth power supply line L5. The boost circuit 23 has two output terminals. A first output terminal of the boost circuit 23 is connected to a third connection point P3 set on the first power supply line L1 via a sixth power supply line L6. A second output terminal of the boost circuit 23 is connected to a fourth connection point P4 set on the second power supply line L2 via a seventh power supply line L7. The fourth connection point P4 is set between the second connection point P2 on the second power supply line L2 and the power supply target 12.

[0024] The first switch 31 is provided on the third power line L3. The first switch 31 opens and closes the third power line L3. The second switch 32 is provided on the fourth power line L4. The second switch 32 opens and closes the fourth power line L4. The third switch 33 is provided on the fifth power line L5. The third switch 33 opens and closes the fifth power line L5. The fourth switch 34 is provided on the sixth power line L6. The fourth switch 34 opens and closes the sixth power line L6. The fifth switch 35 is provided on the seventh power line L7. The fifth switch 35 opens and closes the seventh power line L7.

[0025] The first voltage sensor 41 is provided between the power switch 13 and the third connection point P3 in the first power line L1. The first voltage sensor 41 detects a voltage V1 occurring in the first power line L1. The second voltage sensor 42 is provided between the second switch 32 and the auxiliary power supply 22 in the fourth power line L4. The second voltage sensor 42 detects a terminal voltage V2 of the auxiliary power supply 22. The terminal voltage V2 is a 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 a current occurring in the fourth power line L4, that is, a charging current I to the auxiliary power supply 22. The charging current I is a current supplied to the auxiliary power supply 22 when the auxiliary power supply 22 is charged. The temperature sensor 44 detects a temperature T of the auxiliary power supply 22.

[0026] The control circuit 24 is connected to a fifth connection point P5 set on the sixth power line L6 via an eighth power line L8. The fifth connection point P5 is set between the fourth switch 34 and the boost circuit 23 on the sixth power line L6. 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 through 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 smaller than a predetermined voltage threshold, the control circuit 24 determines that the voltage VB of the main power supply 11 has dropped. The voltage threshold is a criterion for determining a voltage drop of the main power supply 11.

[0027] The third power supply line L3 and the fourth power supply line L4 form a charging path between the main power supply 11 and the auxiliary power supply 22. The fifth power supply line L5, the sixth power supply line L6, and the seventh power supply line L7 form a discharging path between the auxiliary power supply 22 and the power supply target 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.

[0028] <Operation of power supply device 10> Next, a description will be given of the operation of the power supply device 10. In the initial state, the power switch 13 and the first to fifth switches 31 to 35 are turned off.

[0029] When the power switch 13 is turned on, power from the main power supply 11 is supplied to the electric circuit of the control system of the power supply target 12 via the first power supply line L1. When the power switch 13 is turned on, power from the main power supply 11 is also supplied to the control circuit 24 via a power supply line (not shown). Regardless of whether the power switch 13 is on or off, power from the main power supply 11 is supplied to the electric circuit of the power system of the power supply target 12 via the second power supply line L2.

[0030] When the power switch 13 is turned on, the control circuit 24 turns on the first to fourth switches 31 to 34 while maintaining the fifth switch 35 in an off state. Therefore, the power from the main power supply 11 is charged into the auxiliary power supply 22 via the charging circuit 21. The charging circuit 21 controls charging while monitoring, for example, the charging current I and the charging voltage.

[0031] The output voltage of the auxiliary power supply 22 is boosted by the boost circuit 23. When the voltage VB of the main power supply 11 is not lowered, the voltage V3 boosted by the boost circuit 23 is lower than the voltage VB of the main power supply 11. Therefore, the voltage V3 boosted by the boost circuit 23 is not supplied to the electric circuit of the control system of the power supply target 12 via the sixth power supply line L6 and the first power supply line L1. A first diode for preventing reverse current (not shown) is provided between the third connection point P3 in the sixth power supply line L6 and the fourth switch 34. The first diode prevents power from flowing from the main power supply 11 to the boost circuit 23 via the first power supply line L1 and the sixth power supply line L6. The voltage boosted by the boost circuit 23 is supplied to the control circuit 24 via the eighth power supply line L8.

[0032] In contrast, when the voltage VB of the main power supply 11 drops, power from the boost circuit 23 is instantly supplied to the electric circuit of the control system of the power supply target 12 via the sixth power supply line L6 and the first power supply line L1. This is because, as the voltage VB of the main power supply 11 drops, the voltage V3 boosted by the boost circuit 23 becomes higher than the voltage of the main power supply 11 and, by extension, the voltage generated in the first power supply line L1. Therefore, even if the power supply from the main power supply 11 to the power supply target 12 is interrupted, the power supply to the electric circuit of the control system of the power supply target 12 is backed up by the auxiliary power supply 22.

[0033] 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 supply line L1. The second diode prevents power from flowing from the boost circuit 23 to the main power supply 11 via the sixth power supply line L6 and the first power supply line L1.

[0034] When the voltage VB of the main power supply 11 drops, the control circuit 24 turns on the fifth switch 35. As a result, power from the boost circuit 23 is supplied to the power system electric circuit of the power supply target 12 via the seventh power supply line L7 and the second power supply line L2. This is because, as the voltage VB of the main power supply 11 drops, the voltage V3 boosted by the boost circuit 23 becomes higher than the voltage of the main power supply 11 and, by extension, the voltage generated on the second power supply line L2. Therefore, even if the power supply from the main power supply 11 to the power supply target 12 is interrupted, the power supply to the power system electric circuit of the power supply target 12 is backed up by the auxiliary power supply 22.

[0035] 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 boost circuit 23 to the main power supply 11 via the sixth power line L6 and the second power line L2.

[0036] <Deterioration Diagnosis Processing of Auxiliary Power Supply 22> The control circuit 24 diagnoses the deterioration of the auxiliary power supply 22 while the auxiliary power supply 22 is being charged. When the power switch 13 is turned on, the control circuit 24 determines the degree of deterioration of the auxiliary power supply 22 based on the internal resistance of the auxiliary power supply 22 during charging. This is based on the fact that the internal resistance of the auxiliary power supply 22 increases as the deterioration of the auxiliary power supply 22 progresses. The internal resistance is an electrical resistance that the auxiliary power supply 22 has inside.

[0037] As shown in FIG. 2, the auxiliary power supply 22 generates an electromotive force V s and internal resistance R s It can be represented by an electric circuit with and connected in series. s is the theoretical voltage of the auxiliary power supply 22. When the auxiliary power supply 22 is not being charged, that is, when the charging current I is not being supplied from the charging circuit 21 to the auxiliary power supply 22, the internal resistance R s Therefore, the terminal voltage V2 of the auxiliary power supply 22 does not increase in proportion to the electromotive force V s The terminal voltage V2 is the voltage actually output from the auxiliary power supply 22.

[0038] As shown in FIG. 3, when the auxiliary power supply 22 is being charged, that is, when a charging current I is being supplied from the charging circuit 21 to the auxiliary power supply 22, the internal resistance R s Therefore, when the auxiliary power supply 22 is being charged, the terminal voltage V2 of the auxiliary power supply 22 is increased by an electromotive force V s The increased voltage ΔV is the amount of change in the voltage of the auxiliary power supply 22 due to the increase caused by the charging of the auxiliary power supply 22.

[0039] 4, depending on the charging method of charging circuit 21, when charging of auxiliary power supply 22 starts (time T1), terminal voltage V2 of auxiliary power supply 22 rises instantaneously. After that, terminal voltage V2 gradually increases as charging progresses, and eventually is maintained at a constant voltage.

[0040] The increased voltage ΔV of auxiliary power supply 22 during charging is expressed by the following equation (1): "·" in equation (1) indicates multiplication. ΔV=I Rs …(1) Terminal voltage V2 of auxiliary power supply 22 during charging is expressed by the following equation (2).

[0041] V2=V s +ΔV …(2) Internal resistance R s is expressed by the following formula (3). Formula (3) is obtained from the previous formula (1). " / " in formula (3) indicates division.

[0042] R s =ΔV / I …(3) The control circuit 24 calculates the internal resistance R of the auxiliary power supply 22 using equation (3). s The control circuit 24 calculates, for example, the internal resistance R s is greater than a predetermined internal resistance threshold, the control circuit 24 determines that the auxiliary power supply 22 has deteriorated. When the control circuit 24 determines that the auxiliary power supply 22 has deteriorated, the control circuit 24 executes a predetermined process. The process includes, for example, visually or audibly notifying the user of the vehicle that the auxiliary power supply 22 has deteriorated.

[0043] The control circuit 24 can also diagnose the deterioration of the auxiliary power supply 22 while the auxiliary power supply 22 is being discharged. When the auxiliary power supply 22 is being discharged, that is, when a current is output from the auxiliary power supply 22, the internal resistance R s Therefore, when the auxiliary power supply 22 is discharged, the terminal voltage V2 of the auxiliary power supply 22 is increased by an amount corresponding to the voltage drop. s The voltage drop is the amount of change in the voltage of the auxiliary power supply 22 that is the amount of voltage drop due to the discharge of the auxiliary power supply 22. In contrast, when the auxiliary power supply 22 is not discharged, that is, when no current is output from the auxiliary power supply 22, the internal resistance R s Therefore, the terminal voltage V2 of the auxiliary power supply 22 does not drop in proportion to the electromotive force V s Therefore, the internal resistance R of the auxiliary power supply 22 during discharge is equal to s Based on this, it is possible to determine the degree of deterioration of the auxiliary power supply 22. The method of determination is the same as the method of determining deterioration when the auxiliary power supply 22 is being charged.

[0044] However, when diagnosing deterioration of the auxiliary power supply 22 while the auxiliary power supply 22 is being charged or discharged, the following two concerns A1 and A2 arise. A1. Internal resistance R s That is, the internal resistance R s varies depending on the temperature of the auxiliary power supply 22. s decreases as the temperature of the auxiliary power supply 22 increases. However, as the temperature of the auxiliary power supply increases, the internal resistance R s The slope, which is the rate of change of, gradually becomes smaller.

[0045] A2. Internal resistance R s The internal resistance R s The internal resistance R measured when the charging current I is 10A decreases as the charging current I or discharging current increases. s is 10mΩ, and the internal resistance R measured when the discharge current is 50A. s That is, the internal resistance R measured when the charging current I is 10A is 6mΩ. s and the internal resistance R measured when the discharge current was 50A. s The value of is different even for the same auxiliary power supply 22.

[0046] Due to these concerns A1 and A2, if the value of the current used for deterioration diagnosis of auxiliary power supply 22 differs depending on the specifications of power supply device 10, deterioration diagnosis of auxiliary power supply 22 may not be performed appropriately. The current used for deterioration diagnosis is charging current I or discharging current. Therefore, in this embodiment, in order to appropriately diagnose deterioration of auxiliary power supply 22, control circuit 24 executes the following process.

[0047] <Processing to ensure reliability of deterioration diagnosis> When diagnosing the deterioration of the auxiliary power supply 22, the control circuit 24 uses the above formula (3) to calculate the internal resistance R s Calculate the following.

[0048] The control circuit 24 calculates the first correction coefficient G1 based on the charging current I detected via the current sensor 43. The control circuit 24 calculates the first correction coefficient G1 by using a first coefficient map M1.

[0049] 5, the first coefficient map M1 is a two-dimensional map that defines the relationship between the charging current I and the first correction coefficient G1, and has the following characteristics: the value of the first correction coefficient G1 decreases linearly and gradually as the charging current I increases. The first coefficient map M1 is stored in a storage device such as a memory.

[0050] The first correction coefficient G1 is the internal resistance R calculated based on the above formula (3). s The standardization is used to standardize the internal resistance R calculated based on the above formula (3), for example. s The internal resistance R according to the reference current value s The reference current value is, for example, 10 A. "A" stands for ampere, which is the unit of current. When the charging current I is, for example, 10 A, the first correction coefficient G1 becomes "1.0".

[0051] Next, the control circuit 24 receives the temperature T of the auxiliary power supply 22 detected through the temperature sensor 44. Based on the temperature T of the auxiliary power supply 22, the control circuit 24 determines the internal resistance threshold value R limit The control circuit 24 calculates the internal resistance threshold map M R Using the internal resistance threshold R limit Calculate the following.

[0052] As shown in Figure 6, the internal resistance threshold map M R is the temperature T of the auxiliary power supply 22 and the internal resistance threshold R limit and has the following characteristics: limit The value of the internal resistance threshold R with respect to temperature T gradually decreases as the temperature T of the auxiliary power supply 22 increases. However, as the temperature T of the auxiliary power supply 22 increases, the internal resistance threshold R with respect to temperature T limitThe slope of the internal resistance threshold map M R is stored in a storage device such as a memory.

[0053] The internal resistance threshold R limit is the internal resistance R of the auxiliary power supply 22 at which it becomes difficult for the auxiliary power supply 22 to output the power required for the auxiliary power supply 22 in accordance with the temperature T of the auxiliary power supply 22. s For example, if the operating temperature range of the power supply device 10 is "-25°C to 60°C" and the power required for the auxiliary power supply 22 is "200 W", when the temperature T of the auxiliary power supply 22 is, for example, "-25°C", the internal resistance R s Unless the resistance is "43 mΩ" or less, the auxiliary power supply 22 cannot output a power of "200 W".

[0054] Next, the control circuit 24 reads the output power of the auxiliary power supply 22 required by the power supply target 12 from the storage device. The output power includes the output current and output voltage of the auxiliary power supply 22. The output current is the discharge current of the auxiliary power supply 22. The output power of the auxiliary power supply 22 required by the power supply target 12 differs for each power supply target 12 or for each system in which the power supply target 12 is mounted. The system includes, for example, a steering device.

[0055] The control circuit 24 calculates the second correction coefficient G2 based on the output current of the auxiliary power supply 22 required by the power supply target 12. The control circuit 24 calculates the second correction coefficient G2 by using a second coefficient map M2.

[0056] As shown in FIG. 7, the second coefficient map M2 is a coefficient for calculating the output current I dis and the second correction coefficient G2, and has the following characteristics: dis However, it increases gradually as the output current I dis As the value of increases, the output current I disThe slope, which is the rate of change of the second correction coefficient G2 with respect to the second coefficient map M2, gradually increases. The second coefficient map M2 is stored in a storage device such as a memory.

[0057] The second correction factor G2 is the internal resistance threshold R limit Normalization is used to normalize the internal resistance threshold R limit The internal resistance threshold value R according to the reference current value limit The reference current value is, for example, 10 A. "A" indicates an ampere, which is a unit of current strength. The output current I of the auxiliary power supply 22 required by the power supply target 12 is dis For example, when the output current I of the auxiliary power supply 22 required by the power supply target 12 is 10 A, the second correction coefficient G2 is 1.0. dis For example, when the current is 60A, the second correction coefficient G2 becomes "1.2."

[0058] Next, the control circuit 24 calculates the internal resistance R of the auxiliary power supply 22 based on the above equation (3). s is corrected by the first correction coefficient G1. The corrected internal resistance R s_fin is expressed by the following formula (4). In formula (4), "·" indicates multiplication. The corrected internal resistance R s_fin is a value corresponding to the reference current value.

[0059] R s_fin =R s ·G1… (4) The control circuit 24 also includes an internal resistance threshold map M R The internal resistance threshold R is calculated based on limit is corrected by the second correction coefficient G2. The corrected internal resistance threshold value R limit_fin is expressed by the following formula (5). In formula (5), "·" indicates multiplication. The corrected internal resistance threshold value R limit is a value corresponding to the reference current value.

[0060] R limit_fin =R limit ·G2… (5) The control circuit 24 calculates the corrected internal resistance R s_finand the corrected internal resistance threshold R limit_fin The control circuit 24 compares the corrected internal resistance R s_fin is the corrected internal resistance threshold R limit_fin That is, the control circuit 24 determines that the auxiliary power supply 22 is not degraded when the auxiliary power supply 22 does not output the output current I required for the power supply target 12. dis The control circuit 24 determines that it is possible to output the corrected internal resistance R s_fin is the corrected internal resistance threshold R limit_fin When the output current I required for the power supply target 12 exceeds the threshold voltage Vcc, the control circuit 24 determines that the auxiliary power supply 22 is degraded. dis It is determined that it is difficult to output the

[0061] <Effects of the embodiment> This embodiment provides the following advantages. (1) The control circuit 24 calculates a first correction coefficient G1 that decreases with an increase in the charging current I or the discharging current, and a second correction coefficient G2 that increases with an increase in the power required to be output to the auxiliary power supply 22. When diagnosing the deterioration of the auxiliary power supply 22, the control circuit 24 calculates the internal resistance R s is multiplied by the first correction coefficient G1 to obtain the internal resistance R s The internal resistance R after correction according to the reference current value s_fin The control circuit 24 corrects the internal resistance threshold map M R The internal resistance threshold R is calculated based on limit The internal resistance threshold value R is calculated by multiplying it by the second correction coefficient G2. limit The internal resistance threshold value R according to the reference current value limit_fin Correct to.

[0062] According to this configuration, when diagnosing the deterioration of the auxiliary power supply 22, the internal resistance R s is the internal resistance R after correction according to the reference current value s_fin In addition, the internal resistance threshold R limitis the internal resistance threshold value R after correction according to the reference current value limit_fin In other words, the internal resistance before correction R s and the internal resistance threshold value R before correction limit and are standardized according to the reference current value. Therefore, in the same power supply device 10, whether the deterioration diagnosis of the auxiliary power supply 22 is performed based on the charging current I or based on the discharging current, the deterioration diagnosis of the auxiliary power supply 22 can be performed appropriately. Furthermore, even if the value of the current used for the deterioration diagnosis of the auxiliary power supply 22 differs depending on the specifications of the power supply device 10, such as when the power supply target 12 is different, the deterioration diagnosis of the auxiliary power supply 22 can be performed appropriately. The reliability of the deterioration diagnosis of the auxiliary power supply 22 can also be ensured.

[0063] (2) Internal resistance before correction R s and the internal resistance threshold value R before correction limit Therefore, even if the value of the current used in the deterioration diagnosis of the auxiliary power supply 22 is different, the deterioration diagnosis of the auxiliary power supply 22 based on the charging current I and the output current I dis In the deterioration diagnosis of the auxiliary power supply 22 based on the R In addition, an internal resistance threshold map M can be used for each power supply target 12 or each system in which the power supply target 12 is installed. R There is no need to prepare a separate output current I dis is the discharge current of the auxiliary power supply 22.

[0064] (3) Uncorrected internal resistance threshold R limit is set based on the value of the internal resistance before correction at which it becomes difficult for the auxiliary power supply 22 to output the power required for the auxiliary power supply 22 in accordance with the temperature T of the auxiliary power supply 22. With this configuration, it is possible to diagnose deterioration of the auxiliary power supply 22 based on whether it becomes difficult for the auxiliary power supply 22 to output the power required for the auxiliary power supply 22 in accordance with the temperature T of the auxiliary power supply 22.

[0065] (4) The control circuit 24 calculates the first correction coefficient G1 by using a first coefficient map M1 that defines the relationship between the charging current I and the first correction coefficient G1. dis and the second correction coefficient G2 is calculated using a second coefficient map M2 that specifies the relationship between the first correction coefficient G1 and the second correction coefficient G2. With this configuration, the control circuit 24 can easily calculate the first correction coefficient G1 based on the first coefficient map M1. Also, the control circuit 24 can easily calculate the second correction coefficient G2 based on the second coefficient map M2.

[0066] (5) The control circuit 24 detects the temperature T of the auxiliary power supply 22 and the uncorrected internal resistance threshold R limit The internal resistance threshold map M R Using the uncorrected internal resistance threshold R limit According to this configuration, the control circuit 24 calculates the internal resistance threshold map M R Based on the uncorrected internal resistance threshold R limit can be easily calculated.

[0067] (6) The power supply target 12 includes a vehicle control device. Higher operational reliability is required for the vehicle control device. The power supply device 10 of the present embodiment is suitable for the vehicle control device. <Other embodiments> This embodiment may be modified as follows.

[0068] The control circuit 24 may calculate the first correction coefficient G1 without using the first coefficient map M1. The control circuit 24 may calculate the first correction coefficient G1 by using a predetermined calculation formula, for example. It is sufficient that the first correction coefficient G1 can be obtained based on the charging current I.

[0069] The control circuit 24 may calculate the second correction coefficient G2 without using the second coefficient map M2. The control circuit 24 may calculate the second correction coefficient G2 by using, for example, a predetermined calculation formula. dis The second correction coefficient G2 can be obtained based on the above.

[0070] The control circuit 24 is configured to calculate the internal resistance threshold map M R Without using the internal resistance threshold R limit The control circuit 24 may calculate the internal resistance threshold value R limit The internal resistance threshold value R may be calculated based on the temperature T of the auxiliary power supply 22. limit It is sufficient to obtain the following. [Explanation of symbols]

[0071] 10…Power supply device 11…Main power supply 12…Power supply target 22…Auxiliary power supply 24...Control circuit G1: First correction factor G2: Second correction factor M1…First coefficient map M2: Second coefficient map M R …Internal resistance threshold map R limit …Internal resistance threshold (before correction) R limit_fin …Internal resistance threshold (after correction) R s …Internal resistance (before correction) R s_fin …Internal resistance (after correction) T…Temperature

Claims

1. An auxiliary power source for a main power source that supplies power to a power supply target; A control circuit configured to control charging and discharging of the auxiliary power supply, the control circuit calculates an internal resistance of the auxiliary power supply based on a voltage change amount and a charging current value when the auxiliary power supply is charged, or a voltage change amount and a discharging current value when the auxiliary power supply is discharged, and diagnoses deterioration of the auxiliary power supply by comparing the calculated internal resistance with an internal resistance threshold value that is set in accordance with a temperature of the auxiliary power supply, the control circuit calculates a first correction coefficient that decreases with an increase in the charging current or the discharging current, and a second correction coefficient that increases with an increase in power that is requested to be output to the auxiliary power supply; a power supply device configured, when diagnosing deterioration of the auxiliary power supply, to correct the internal resistance to a corrected internal resistance corresponding to a reference current value by multiplying the internal resistance by the first correction coefficient, and to correct the internal resistance threshold value to the internal resistance threshold value corresponding to the reference current value by multiplying the internal resistance threshold value by the second correction coefficient.

2. 2. The power supply device according to claim 1, wherein the internal resistance threshold value before correction is set based on a value of the internal resistance before correction at which it becomes difficult for the auxiliary power supply to output the power required for the auxiliary power supply in accordance with the temperature of the auxiliary power supply.

3. the control circuit calculates the first correction coefficient by using a first coefficient map that defines a relationship between the charging current and the first correction coefficient; 3. The power supply device according to claim 1, configured to calculate the second correction coefficient using a second coefficient map that defines a relationship between the discharge current and the second correction coefficient.

4. 3. The power supply device according to claim 1, wherein the control circuit is configured to calculate the internal resistance threshold value before correction using an internal resistance threshold value map that specifies the relationship between the temperature of the auxiliary power supply and the internal resistance threshold value before correction.

5. The power supply device according to claim 1 or 2, wherein the power supply target includes a control device of a vehicle.

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