Power supply unit and control method for power supply unit

Abstract

To provide an electric power unit capable of acquiring characteristics of an electric double-layer capacitor effective at a start of use.SOLUTION: An electric power unit comprises: an electric power storage circuit which has a first node connected to an electric power supply and a grounded second node and comprises an electric double-layer capacitor between the first node and the second node; a charging circuit which is connected to the first node, and charges the electric power storage circuit; and an electric power supply control part which measures the voltage at the first node to control the charging circuit, wherein the electric power control part executes a procedure to: charge the electric power storage circuit by the charging circuit when determining that a stop period is longer than a threshold period; and then calculate a first capacity value and a first equivalent series resistance value of the electric double-layer capacitor based upon the measured voltage at the first node.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power supply device and a method for controlling the power supply device.

Background Art

[0002] In an automobile, in the case of a failure or interruption of the main power supply, a backup power supply provided to supply electrical energy in place of the main power supply or assist the main power supply is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003] s

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses that a supercapacitor is used as a backup power supply. Patent Document 1 discloses a diagnostic module that monitors the soundness status of the supercapacitor by measuring the capacitance value and the internal equivalent resistance.

[0005] When measuring the characteristics of an electric double layer capacitor during discharge, if it is left unused for a long time after discharge, the capacitance value and the equivalent series resistance value measured during discharge may not be valid. On the other hand, if the characteristics of the electric double layer capacitor are measured every time at the start of use, it takes time to start up the power supply device.

[0006] The present disclosure provides a power supply device capable of acquiring the characteristics of an effective electric double layer capacitor at the start of use.

Means for Solving the Problems

[0007] One aspect of the present disclosure provides a power supply device comprising: a power storage circuit having a first node connected to a power source and a second node grounded, with an electric double-layer capacitor between the first node and the second node; a charging circuit connected to the first node for charging the power storage circuit; and a power control unit that measures the voltage of the first node and controls the charging circuit, wherein the power control unit, when it determines that the period of shutdown is longer than a threshold period, causes the charging circuit to charge the power storage circuit and calculates a first capacitance value and a first equivalent series resistance value of the electric double-layer capacitor based on the measured voltage of the first node. [Effects of the Invention]

[0008] According to the power supply device of this disclosure, the effective characteristics of an electric double-layer capacitor can be obtained at the start of use. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of the configuration of a power supply device according to the first embodiment. [Figure 2] Figure 2 shows an example of the configuration of the equalization discharge circuit of the power supply device according to the first embodiment. [Figure 3] Figure 3 is a flowchart illustrating the processing procedure of the power supply device according to the first embodiment. [Figure 4] Figure 4 is a flowchart illustrating the processing procedure of the power supply device according to the first embodiment. [Figure 5] Figure 5 is a flowchart illustrating the discharge-type characteristic measurement process of the power supply device according to the first embodiment. [Figure 6] Figure 6 is an equivalent circuit diagram of the circuit that performs the discharge-type characteristic measurement processing of the energy storage circuit in the power supply device according to the first embodiment. [Figure 7] Figure 7 is a flowchart of the capacity value measurement process of the energy storage circuit in the power supply device according to the first embodiment. [Figure 8] Figure 8 is a flowchart of the process for measuring the equivalent series resistance of the energy storage circuit in the power supply device according to the first embodiment. [Figure 9] Figure 9 is a flowchart of the measurement process (characteristic measurement process) for the capacity value and equivalent series resistance value of the energy storage circuit in the power supply device according to the first embodiment. [Figure 10] Figure 10 is an equivalent circuit diagram of the circuit that performs equalization processing of the energy storage circuit in the power supply device according to the first embodiment. [Figure 11] Figure 11 is a flowchart of the equivalent processing of the energy storage circuit in the power supply device according to the first embodiment. [Figure 12] Figure 12 is a flowchart of the discharge process of the energy storage circuit in the power supply device according to the first embodiment. [Figure 13] Figure 13 is a flowchart illustrating the rechargeable characteristic measurement process of the power supply device according to the first embodiment. [Figure 14] Figure 14 is an equivalent circuit diagram of the circuit that performs rechargeable characteristic measurement processing of the energy storage circuit in the power supply device according to the first embodiment. [Figure 15] Figure 15 is a flowchart of the capacity value measurement process of the energy storage circuit in the power supply device according to the first embodiment. [Figure 16] Figure 16 is a flowchart of the process for measuring the equivalent series resistance of the energy storage circuit in the power supply device according to the first embodiment. [Figure 17] Figure 17 is a flowchart of the charging process of the energy storage circuit in the power supply device according to the first embodiment. [Figure 18] Figure 18 shows an example of the configuration of a power supply device according to the second embodiment. [Figure 19] Figure 19 is a flowchart illustrating the discharge-type characteristic measurement process of the power supply device according to the second embodiment. [Figure 20] Figure 20 is an equivalent circuit diagram of the circuit that performs the discharge-type characteristic measurement processing of the energy storage circuit in the power supply device according to the second embodiment. [Figure 21] Figure 21 is a flowchart of the capacity value measurement process of the energy storage circuit in the power supply device according to the second embodiment. [Figure 22] Figure 22 is a flowchart of the process for measuring the equivalent series resistance of the energy storage circuit in the power supply device according to the second embodiment. [Figure 23] FIG. 23 is a flowchart for explaining the charging characteristic measurement process of the power supply device according to the second embodiment. [Figure 24] FIG. 24 is an equivalent circuit diagram of a circuit for performing the charging characteristic measurement process of the power storage circuit in the power supply device according to the second embodiment. [Figure 25] FIG. 25 is a flowchart for the capacity value measurement process of the power storage circuit in the power supply device according to the second embodiment. [Figure 26] FIG. 26 is a flowchart for the equivalent series resistance value measurement process of the power storage circuit in the power supply device according to the second embodiment. [Figure 27] FIG. 27 is a flowchart for explaining the characteristic measurement process of the power supply device according to the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, the power supply device according to the present embodiment will be described in detail with reference to the drawings.

[0011] <<First Embodiment>> <Power Supply Device 1> FIG. 1 is a diagram showing a configuration example of the power supply device 1 according to the present embodiment. In recent years, in a latch mechanism which is a mechanical lock mechanism of an automobile door, a system in which the operation of the lock portion of the latch is performed by a motor has been adopted as an electric latch system. It is essential that the automobile door can be unlocked even in an emergency such as an accident. Therefore, even when the battery power is lost due to destruction in an accident or the like, the electric latch system needs to be able to continue operating for a certain period of time. The power supply device 1 according to the present embodiment is used, for example, as a backup power supply for an electric latch system.

[0012] The power supply device 1 stores the power supplied from the power supply 100. Further, the power supply device 1 supplies power to the load device 200 when the power from the power supply 100 is cut off. Note that the power supply 100 is also directly connected to the load device 200. The power supply 100 is connected to the load device 200 via a diode 71 in order to prevent reverse current of the current.

[0013] The power supply 100 is, for example, an on-board battery. The load device 200 comprises a load 210 and a load drive circuit 220 that drives the load 210. The load 210 is, for example, a motor in an electric latch system for a car door.

[0014] The power supply unit 1 comprises a power storage circuit 10, a charging circuit 20, a boost circuit 30, an equalizing discharge circuit 40, and a power control unit 50. Each component constituting the power supply unit 1 will be described below.

[0015] [Energy storage circuit 10] The energy storage circuit 10 is a circuit for storing electricity. The energy storage circuit 10 includes at least one electric double-layer capacitor, a so-called supercapacitor. The energy storage circuit 10 of the power supply device 1 according to this embodiment includes an electric double-layer capacitor 11 and an electric double-layer capacitor 12 connected in series.

[0016] [Charging circuit 20] The charging circuit 20 charges the energy storage circuit 10 using power supplied from the power supply 100. The charging circuit 20 performs charging based on the charging control signal CTL1 of the power supply control unit 50.

[0017] [Boost circuit 30] The boost circuit 30 boosts the power supplied from the energy storage circuit 10 and supplies power to the load device 200. The boost circuit 30 supplies power based on the boost control signal CTL2 of the power supply control unit 50. The boost circuit 30 is connected to the load device 200 via a diode 72 to prevent reverse current flow. Note that the diode 72 may be omitted.

[0018] [Equalization discharge circuit 40] The equalizing discharge circuit 40 performs equalization processing on the energy storage circuit 10. The equalizing discharge circuit 40 also performs discharge processing on the energy storage circuit 10. Figure 2 shows an example of the configuration of the equalizing discharge circuit 40 of the power supply device 1 according to this embodiment.

[0019] When electric double-layer capacitors such as supercapacitors are connected in series, an imbalance in the voltage distribution of each capacitor may occur due to variations in individual leakage current and capacitance. If an imbalance occurs in the voltage distribution of each capacitor, even if the total voltage obtained by adding the rated voltages of each capacitor is within the rated voltage range, it is possible that one of the capacitors may have a voltage exceeding its rated or set value applied to it. The equalization discharge circuit 40 performs an equalization process to eliminate the voltage distribution imbalance and equalize the voltage applied to each capacitor in order to prevent a voltage exceeding the rated or set value from being applied to either the electric double-layer capacitor 11 or the electric double-layer capacitor 12.

[0020] The equalization discharge circuit 40 performs equalization and discharge processing of the energy storage circuit 10 using the SW1 control signal CTL3, which opens and closes switch 41, and the SW2 control signal CTL4, which opens and closes switch 42. Furthermore, the equalization discharge circuit 40 outputs the voltage signal SIGV1 from the electric double-layer capacitor 11 and the voltage signal SIGV2 from the electric double-layer capacitor 12 to the power control unit 50.

[0021] The equalization discharge circuit 40 includes switches 41 and 42, and resistors 45 and 46. The energy storage circuit 10 includes an electric double-layer capacitor 11 between node N1 and node N3. The energy storage circuit 10 also includes an electric double-layer capacitor 12 between node N3 and node N2. Node N1 is connected to the power supply 100 and the load device 200. Node N2 is grounded.

[0022] Switch 41 has a first terminal 41a and a second terminal 41b. Switch 41 connects or disconnects the first terminal 41a and the second terminal 41b. Switch 41 is installed between node N1 and resistor 45. In the following description, switch 41 may be referred to as switch SW1. Switch 41 is opened and closed based on the SW1 control signal CTL3.

[0023] Resistor 45 is provided between switch 41 and node N4. Resistors 45 and 46 are connected in series at node N4. Resistor 45 has a resistance value R1.

[0024] Switch 42 has a first terminal 42a and a second terminal 42b. Switch 42 connects or disconnects the first terminal 42a and the second terminal 42b. Switch 42 is located between node N2 and resistor 46. In the following description, switch 42 may be referred to as switch SW2. Switch 42 is opened and closed based on the SW2 control signal CTL4.

[0025] Resistor 46 is provided between node N4 and node N2. Resistor 46 has a resistance value R2. Note that resistance value R2 may be equal to resistance value R1. Note that "equal resistance values" does not only mean they are exactly the same, but also includes cases where they are equal within the manufacturing tolerance range.

[0026] The equalizing discharge circuit 40 outputs the terminal voltage Vtc1 at node N1 as a voltage signal SIGV1 to the power supply control unit 50. The equalizing discharge circuit 40 also outputs the terminal voltage Vtc2 at node N3 as a voltage signal SIGV2 to the power supply control unit 50. Note that the voltage at node N1 is sometimes referred to as the terminal voltage Vtc of the energy storage circuit 10.

[0027] Note that node N1 is an example of the first node, and node N2 is an example of the second node.

[0028] [Power control unit 50] The power control unit 50 controls the charging, power supply, discharge, and equalization of the energy storage circuit 10. The power control unit 50 also measures the characteristics of the energy storage circuit 10. The power control unit 50 is composed of a controller, such as a microcontroller.

[0029] The power control unit 50 controls the charging of the energy storage circuit 10 by the charging control signal CTL1. The power control unit 50 also controls the power supply to the load device 200 by the boost circuit 30 by the boost control signal CTL2. The power control unit 50 controls the equalization process of the equalization discharge circuit 40 by the SW1 control signal CTL3 or the SW2 control signal CTL4.

[0030] Furthermore, the power control unit 50 controls the discharge process of the equalization discharge circuit 40 using the SW1 control signal CTL3 and the SW2 control signal CTL4. The power control unit 50 also controls the load drive circuit 220 using the drive control signal CTL5.

[0031] The power control unit 50 is equipped with a timer for measuring time. The power control unit 50 calculates the time using the number of counts from when the timer starts counting until it stops.

[0032] The vehicle control unit 300 is connected to the power supply control unit 50. The vehicle control unit 300 is, for example, an ECU (Electronic Control Unit). The power supply control unit 50 receives various signals CTLh from the vehicle control unit 300, such as whether the vehicle is stopped or in use, and outputs, for example, its status and information to the vehicle control unit 300.

[0033] The term "stopped state" refers to a state where the engine is stopped and systems such as electric latches are not operating. Furthermore, in the stopped state, the vehicle's systems are in a low-power consumption state. The stopped state includes the state where the vehicle is parked and the state where the vehicle is stored. The term "operating state" refers to a state where the engine is running or in a state where the engine can be started, and systems such as electric latches are operating.

[0034] <Processing procedure for power supply unit 1> Next, the processing procedure of the power supply unit 1 will be described. Figures 3 and 4 are flowcharts illustrating the processing procedure of the power supply unit 1 according to the first embodiment. In this description, it is assumed that the vehicle on which the power supply unit 1 is installed is in use before processing begins.

[0035] When processing begins, the power control unit 50 obtains information from the vehicle control unit 300 regarding the vehicle's status, such as whether it is in use or stopped. The power control unit 50 then determines whether the vehicle is stopped (step S10).

[0036] If the vehicle is not in a stationary state (No. in step S10), the power control unit 50 repeats step S10.

[0037] If the vehicle is stopped (Yes in step S10), the power control unit 50 performs a discharge-type characteristic measurement process (step S20).

[0038] [Discharge-type characteristic measurement process] The discharge-type characteristic measurement process of the energy storage circuit 10 in the power control unit 50 of the power supply device 1 according to the first embodiment will be described. Figure 5 is a flowchart illustrating the discharge-type characteristic measurement process of the power supply device 1 according to the first embodiment. The discharge-type characteristic measurement process includes a capacity value measurement process (step S22) and an equivalent series resistance value measurement process (ESR value measurement process) (step S24). The power control unit 50 determines the capacity value and equivalent series resistance value of the energy storage circuit 10 as characteristics of the energy storage circuit 10.

[0039] [Capacitance value and equivalent series resistance value of the energy storage circuit 10] The characteristics of the energy storage circuit 10 in the power supply device 1 according to the first embodiment will now be described. Figure 6 is an equivalent circuit diagram of the circuit that performs the discharge-type characteristic measurement processing of the energy storage circuit 10 in the power supply device 1 according to the first embodiment.

[0040] In the energy storage circuit 10 according to this embodiment, the electric double-layer capacitors 11 and 12 connected in series are considered as a single capacitor having an equivalent capacitance value Csc and a single resistor having a resistance value ESRsc connected in series with that capacitor. Then, the characteristics of the energy storage circuit 10 are determined using the capacitance value Csc and the resistance value ESRsc.

[0041] Furthermore, resistors 45 and 46 connected in series are evaluated as having a discharge resistance R_discharge with a resistance value R (= resistance value R1 + resistance value R2). That is, the resistance value R obtained by adding the resistance value R1 of resistor 45 and the resistance value R2 of resistor 46 is taken as the resistance value of the discharge resistance R_discharge.

[0042] Furthermore, during the characteristic measurement process, switches SW1 and SW2 are simultaneously turned on (closed) and off (opened). Therefore, simultaneously turning on (closing) and off (opening) switches SW1 and SW2 is equivalently represented by turning on (closing) and off (opening) switch SWd.

[0043] [Measurement of the capacity value of the energy storage circuit 10] Electric double-layer capacitors deteriorate over time with use. If the deterioration of an electric double-layer capacitor progresses and its capacitance value decreases, it is conceivable that, for example, the current supplied to the motor may be affected, shortening the time it can be used as a backup power source or preventing the latch from being released. Therefore, in the power supply device 1 according to the first embodiment, the capacitance value of the electric double-layer capacitor is measured and monitored.

[0044] Figure 7 is a flowchart of the capacity value measurement process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. When this process is performed, the charging circuit 20 and the boost circuit 30 stop operating. That is, the energy storage circuit 10 is not being charged by the power supply 100. Also, the energy storage circuit 10 is not supplying power to the load device 200. Furthermore, when this process is performed, it is desirable that the energy storage circuit 10 is charged to a certain extent, for example, 50% or more of full charge, preferably 80% or more.

[0045] The processing procedure of the power control unit 50 and the control method of the power supply unit 1 according to the first embodiment will be explained in accordance with the flowchart in Figure 7.

[0046] (Step S221) First, the power control unit 50 turns on (closes) switches SW1 and SW2. That is, it turns on (closes) switch SWd. When switches SW1 and SW2 are turned on (closed), the discharge resistor R_discharge is connected to the energy storage circuit 10. When the discharge resistor R_discharge is connected to the energy storage circuit 10, the power stored in the energy storage circuit 10 flows to ground at a current I_R through the discharge resistor R_discharge. When the power stored in the energy storage circuit 10 flows to ground at a current I_R, the terminal voltage Vtc of the energy storage circuit 10 begins to decrease.

[0047] (Step S222) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10. The power control unit 50 then records (acquires) the measured terminal voltage Vtc as the starting voltage value V1. At the same time, it starts the timer count.

[0048] (Step S223) Next, the power control unit 50 determines whether the voltage value of the terminal voltage Vtc of the energy storage circuit 10 has become less than or equal to the predetermined termination voltage value V2. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is higher than the predetermined termination voltage value V2 (No in step S223), step S223 is repeated. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is less than or equal to the predetermined termination voltage value V2 (Yes in step S223), the power control unit 50 proceeds to step S224. The termination voltage value V2 is set to a value lower than the start voltage value V1.

[0049] (Step S224) Next, the power control unit 50 stops the timer count and records the count value. Then, the power control unit 50 calculates and records the time T from the count value, from when the timer count started until it stopped. It is desirable that the process in step S224 be performed simultaneously with step S223 or as quickly as possible within the limits of what the power control unit 50 can perform after step S223 has been executed.

[0050] (Step S225) Next, the power control unit 50 turns off (opens) switches SW1 and SW2. When switches SW1 and SW2 are turned off (open), the discharge resistor R_discharge is disconnected from the energy storage circuit 10.

[0051] (Step S226) Next, the power control unit 50 calculates the capacitance value Csc using Equation 1, based on the measured start voltage value V1, end voltage value V2, and time T. Note that the resistance value R is the resistance value of the discharge resistance R_discharge. Ln represents the natural logarithm.

[0052]

number

[0053] For example, in step S223, if the terminal voltage Vtc of the energy storage circuit 10 falls below, for example, the termination voltage V2, the terminal voltage Vtc may be measured again and set as the termination voltage V2. Alternatively, the set time Ts may be set first, switches SW1 and SW2 may be turned on (closed), the terminal voltage Vtc may be measured in step S222, and then the terminal voltage Vtc of the energy storage circuit 10 after time Ts has elapsed may be measured as the termination voltage V2. When setting time Ts, time T in equation 1 should be time Ts.

[0054] The power supply device 1 according to this embodiment can measure the capacitance value of the energy storage circuit 10 during discharge when current is released from the energy storage circuit 10. Furthermore, by measuring the capacitance value of the energy storage circuit 10, the power supply device 1 according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0055] The equalization discharge circuit 40 of the power supply device 1 according to this embodiment also operates as a discharge circuit that discharges the energy stored in the energy storage circuit 10. Therefore, the operation of the discharge circuit can be confirmed by measuring the capacity value of the energy storage circuit 10 in the power supply device 1 according to this embodiment.

[0056] Note that the starting voltage value V1 is an example of the first voltage value, and the ending voltage value V2 is an example of the second voltage value.

[0057] [Measurement of the equivalent series resistance of the energy storage circuit 10] Electric double-layer capacitors deteriorate over time with use. If the deterioration of the electric double-layer capacitor progresses and the equivalent series resistance increases, it is conceivable that, for example, the current supplied to the motor may be impaired, making it impossible to release the latch. Therefore, in the power supply device 1 according to this embodiment, the equivalent series resistance of the electric double-layer capacitor is measured and monitored.

[0058] Figure 8 is a flowchart of the equivalent series resistance measurement process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. When this process is performed, the charging circuit 20 and the boost circuit 30 stop operating. That is, the energy storage circuit 10 is not being charged by the power supply 100. Also, the energy storage circuit 10 is not supplying power to the load device 200. Furthermore, when this process is performed, it is desirable that the energy storage circuit 10 is charged to a certain extent, for example, 50% or more of full charge, preferably 80% or more.

[0059] The processing procedure of the power control unit 50 and the control method of the power supply unit 1 according to this embodiment will be explained in accordance with the flowchart in Figure 8.

[0060] (Step S241) First, the power control unit 50 turns on (closes) switches SW1 and SW2, i.e., switch SWd. When switches SW1 and SW2 are turned on (closed), the discharge resistor R_discharge is connected to the energy storage circuit 10. When the discharge resistor R_discharge is connected to the energy storage circuit 10, the power stored in the energy storage circuit 10 flows to ground through the discharge resistor R_discharge with a current I_R. When the power stored in the energy storage circuit 10 flows to ground with a current I_R, the terminal voltage Vtc of the energy storage circuit 10 begins to decrease.

[0061] (Step S242) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50 stores (acquires) the measured terminal voltage Vtc as the conduction voltage value Vsc_on.

[0062] (Step S243) Next, immediately after measuring the terminal voltage Vtc of the energy storage circuit 10 in step S242, the power control unit 50 turns off (opens) switches SW1 and SW2. When switches SW1 and SW2 are turned off (open), the discharge resistor R_discharge is disconnected from the energy storage circuit 10. It is desirable that the process in step S243 be performed simultaneously with step S242 or as quickly as possible within the limits of what the power control unit 50 can perform after step S242.

[0063] (Step S244) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10 after switches SW1 and SW2 are turned off (open). The power control unit 50 then stores (acquires) the measured terminal voltage Vtc as the non-conductive voltage value Vsc_off.

[0064] (Step S245) Next, the power control unit 50 calculates the equivalent series resistance value ESR using Equation 2, based on the measured conduction voltage value Vsc_on and non-conduction voltage value Vsc_off. Note that the resistance value R is the resistance value of the discharge resistance R_discharge.

[0065]

number

[0066] The power supply device 1 according to this embodiment can measure the equivalent series resistance of the energy storage circuit 10 during discharge when current is released from the energy storage circuit 10. Furthermore, by measuring the equivalent series resistance of the energy storage circuit 10, the power supply device 1 according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0067] Furthermore, the equalization discharge circuit 40 of the power supply device 1 according to this embodiment also operates as a discharge circuit that discharges the energy stored in the energy storage circuit 10. Therefore, the operation of the discharge circuit can be confirmed by measuring the equivalent series resistance value of the energy storage circuit 10 in the power supply device 1 according to this embodiment.

[0068] [Simultaneous measurement of the capacity value and equivalent series resistance value of the energy storage circuit 10] Furthermore, the power supply device 1 according to the first embodiment can simultaneously measure the capacitance value and the equivalent series resistance value of an electric double-layer capacitor.

[0069] Figure 9 is a flowchart of the capacity value and equivalent series resistance value measurement process (characteristic measurement process) of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. When this process is performed, the charging circuit 20 and the boost circuit 30 stop operating. That is, the energy storage circuit 10 is not being charged from the power supply 100. Also, the energy storage circuit 10 is not supplying power to the load device 200. Furthermore, when this process is performed, it is desirable that the energy storage circuit 10 is charged to a certain extent, for example, 50% or more of full charge, preferably 80% or more.

[0070] The processing procedure of the power control unit 50 and the control method of the power supply unit 1 according to this embodiment will be explained in accordance with the flowchart in Figure 9.

[0071] (Step S261) First, the power control unit 50 turns on (closes) switches SW1 and SW2, i.e., switch SWd. When switches SW1 and SW2 are turned on (closed), the discharge resistor R_discharge is connected to the energy storage circuit 10. When the discharge resistor R_discharge is connected to the energy storage circuit 10, the power stored in the energy storage circuit 10 flows to ground through the discharge resistor R_discharge with a current I_R. When the power stored in the energy storage circuit 10 flows to ground with a current I_R, the terminal voltage Vtc of the energy storage circuit 10 begins to decrease.

[0072] (Step S262) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10. The power control unit 50 then records (acquires) the measured terminal voltage Vtc as the starting voltage value V1. It also starts the timer count.

[0073] (Step S263) Next, the power control unit 50 determines whether the voltage value of the terminal voltage Vtc of the energy storage circuit 10 has become less than or equal to a predetermined termination voltage value V2. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is higher than the predetermined termination voltage value V2 (No in step S263), step S263 is repeated. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is less than or equal to the predetermined termination voltage value V2 (Yes in step S263), the power control unit 50 proceeds to step S264. The termination voltage value V2 is set to a value lower than the start voltage value V1.

[0074] (Step S264) Next, the power control unit 50 stops the timer count and records the count value. Then, the power control unit 50 calculates and records the time T from the count value, from when the timer count started until it stopped. It is desirable that the process in step S264 be performed simultaneously with step S263 or as quickly as possible within the limits of what the power control unit 50 can perform after step S263 has been executed.

[0075] For example, in step S263, if the terminal voltage Vtc of the energy storage circuit 10 falls below, for example, the termination voltage V2, the terminal voltage Vtc may be measured again and set as the termination voltage V2. Alternatively, the set time Ts may be set first, switches SW1 and SW2 may be turned on (closed), the terminal voltage Vtc may be measured in step S262, and then the terminal voltage Vtc of the energy storage circuit 10 after time Ts has elapsed may be measured as the termination voltage V2.

[0076] (Step S265) Next, immediately after step S264, the power control unit 50 turns off (opens) switches SW1 and SW2. When switches SW1 and SW2 are turned off (open), the discharge resistor R_discharge is disconnected from the energy storage circuit 10. It is desirable that the processing in step S265 be performed simultaneously with step S264 or as quickly as possible within the limits of what the power control unit 50 can perform after step S264.

[0077] (Step S266) Next, the power control unit 50 measures the voltage value of the terminal voltage Vtc of the energy storage circuit 10 after the switch SW1 is turned off (open). The power control unit 50 then stores the measured terminal voltage Vtc as the non-conductive voltage value V3.

[0078] (Step S267) Next, the power control unit 50 calculates the capacitance value Csc using Equation 1, based on the measured start voltage value V1 and end voltage value V2, and time T. Note that the resistance value R is the resistance value of the discharge resistance R_discharge.

[0079] (Step S268) Next, the power control unit 50 calculates the equivalent series resistance value ESR using Equation 3, based on the termination voltage value V2 and the measured non-conductive voltage value V3. Note that the resistance value R is the resistance value of the discharge resistance R_discharge.

[0080]

number

[0081] The power supply device 1 according to this embodiment can measure the capacitance value and equivalent series resistance value of the energy storage circuit 10 during discharge when current is released from the energy storage circuit 10. Furthermore, by measuring the capacitance value and equivalent series resistance value of the energy storage circuit 10, the power supply device 1 according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0082] <Measurement of terminal voltage Vtc> After step S20 is completed, the power control unit 50 determines whether the voltage value of the terminal voltage Vtc is equal to or greater than the storage voltage value Vsc_stg (step S30).

[0083] If the terminal voltage Vtc is greater than or equal to the storage voltage Vsc_stg (YES in step S30), proceed to the equivalent processing in step S40. If the terminal voltage Vtc is less than the storage voltage Vsc_stg (No in step S30), proceed to step S60.

[0084] [Equalization process] Next, the equalization process in step S40 will be described. Figure 10 is an equivalent circuit diagram of the circuit that performs the equalization process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment.

[0085] Figure 11 is a flowchart of the equivalent processing of the energy storage circuit 10 in the power supply device 1 according to the first embodiment.

[0086] (Step S41) When the equalization process begins, the power control unit 50 turns off (opens) switches SW1 and SW2.

[0087] (Step S42) Next, the power control unit 50 measures the voltage values ​​of terminal voltage Vtc1 and terminal voltage Vtc2.

[0088] (Step S43) Next, the power control unit 50 calculates the capacitance voltage value Vsc1 of the electric double-layer capacitor 11 and the capacitance voltage value Vsc2 of the electric double-layer capacitor 12. Specifically, the capacitance voltage value Vsc1 is the voltage value obtained by subtracting the terminal voltage value Vtc2 from the terminal voltage value Vtc1. The capacitance voltage value Vsc2 is the voltage value of terminal voltage Vtc2.

[0089] (Step S44) Next, the power control unit 50 determines whether the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is higher than the threshold voltage value Vth. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is higher than the threshold voltage value Vth (Yes in step S44), it determines that equalization processing is necessary. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is less than or equal to the threshold voltage value Vth (No in step S44), it terminates the equalization processing.

[0090] (Step S45) Next, the power control unit 50 determines whether the capacitance voltage value Vsc1 is higher than the capacitance voltage value Vsc2. If the capacitance voltage value Vsc1 is higher than the capacitance voltage value Vsc2 (Yes in step S45), the power control unit 50 proceeds to step S461. If the capacitance voltage value Vsc1 is lower than the capacitance voltage value Vsc2 (No in step S45), the power control unit 50 proceeds to step S466.

[0091] (Step S461) If the capacitance voltage value Vsc1 is higher than the capacitance voltage value Vsc2 (Yes in step S45), the power supply control unit 50 turns on (closes) switch SW1. When switch SW1 is turned on (closed), the charge stored in the electric double-layer capacitor 11 is discharged by the resistor 45. Therefore, the capacitance voltage value Vsc1 gradually decreases.

[0092] (Step S462) The power control unit 50 determines whether the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is lower than the threshold voltage value Vth. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is lower than the threshold voltage value Vth (Yes in step S462), the power control unit 50 proceeds to step S463. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is greater than or equal to the threshold voltage value Vth (No in step S462), the power control unit 50 repeats the process in step S462. Note that the threshold voltage value Vth may be a voltage range with a certain width, rather than a predetermined voltage value.

[0093] (Step S463) If the absolute value of the difference between capacitance voltage value Vsc1 and capacitance voltage value Vsc2 is lower than the threshold voltage value Vth (Yes in step S462), the power supply control unit 50 turns off (opens) switch SW1. When switch SW1 is turned off (opens), the electric double-layer capacitor 11 is disconnected from resistor 45. Alternatively, if the threshold voltage value Vth is defined as a voltage range, switch SW1 may be turned off (opened) when the voltage falls within that range.

[0094] (Step S466) If the capacitance voltage value Vsc1 is lower than the capacitance voltage value Vsc2 (No. in step S45), the power supply control unit 50 turns on (closes) switch SW2. When switch SW2 is turned on (closed), the charge stored in the electric double-layer capacitor 12 is discharged by the resistor 46. Therefore, the capacitance voltage value Vsc2 gradually decreases.

[0095] (Step S467) The power control unit 50 determines whether the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is lower than the threshold voltage value Vth. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is lower than the threshold voltage value Vth (Yes in step S467), the power control unit 50 proceeds to step S468. If the absolute value of the difference between the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 is greater than or equal to the threshold voltage value Vth (No in step S467), the power control unit 50 repeats the process in step S467. Note that the threshold voltage value Vth may be a voltage range with a certain width, rather than a predetermined voltage value.

[0096] (Step S468) If the absolute value of the difference between capacitance voltage value Vsc1 and capacitance voltage value Vsc2 is lower than the threshold voltage value Vth (Yes in step S467), the power supply control unit 50 turns off (opens) switch SW2. When switch SW2 is turned off (opens), the electric double-layer capacitor 12 is disconnected from resistor 46. Alternatively, if the threshold voltage value Vth is defined as a voltage range, switch SW2 may be turned off (opened) when the voltage falls within that range.

[0097] In this embodiment, the power supply unit 1 compares the capacitance voltage value Vsc1 and the capacitance voltage value Vsc2 and discharges the electric double-layer capacitor with the higher capacitance voltage value. Therefore, compared to methods such as setting a high resistance value for the equalization circuit and operating it continuously, setting a low resistance value and performing the equalization operation by simultaneously turning on SW1 and SW2 while continuing to charge, or setting a low resistance value for the equivalent circuit and intermittently turning each SW of the equivalent circuit on and off individually as needed, the time and power required for the equalization process can be reduced.

[0098] [Discharge treatment] Next, the discharge process in step S50 will be described. Figure 12 is a flowchart of the discharge process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. The discharge process will be explained using the equivalent circuit diagram in Figure 10. In the discharge process, the voltage value related to the energy storage circuit 10 is set to a storage voltage value Vsc_stg or less, which is lower than the operating voltage value Vact, which will be described later when using it normally.

[0099] (Step S51) First, the power control unit 50 measures the terminal voltage Vtc. Then, the power control unit 50 determines whether the measured terminal voltage Vtc is higher than the storage voltage Vsc_stg. If the terminal voltage Vtc is higher than the storage voltage Vsc_stg (Yes in step S51), the power control unit 50 proceeds to step S52. If the terminal voltage Vtc is less than or equal to the storage voltage Vsc_stg (No in step S51), the power storage circuit 10 is considered to have been sufficiently discharged and has a low voltage, and the discharge process is terminated.

[0100] (Step S52) Next, the power control unit 50 turns on (closes) switches SW1 and SW2, connecting resistors 45 and 46, which are discharge resistors, to the energy storage circuit 10, i.e., the electric double-layer capacitors 11 and 12. That is, switches SW1 and SW2 conduct a path from node N1 to ground via resistors 45 and 46. By connecting resistors 45 and 46, which are discharge resistors, to the energy storage circuit 10, the charge stored in each of the electric double-layer capacitors 11 and 12 is discharged. Therefore, the terminal voltage Vtc gradually decreases.

[0101] (Step S53) Next, the power control unit 50 measures the terminal voltage Vtc. The power control unit 50 then determines whether the voltage value of the terminal voltage Vtc is less than or equal to the storage voltage value Vsc_stg. If the voltage value of the terminal voltage Vtc is higher than the storage voltage value Vsc_stg (No in step S53), the power control unit 50 repeats step S53. If the voltage value of the terminal voltage Vtc is less than or equal to the storage voltage value Vsc_stg (Yes in step S53), the power control unit 50 proceeds to step S54.

[0102] (Step S54) Next, the power control unit 50 turns off (opens) switches SW1 and SW2, disconnecting the discharge resistors 45 and 46 from the energy storage circuit 10, i.e., the electric double-layer capacitors 11 and 12. In other words, switches SW1 and SW2 open the path from node N1 to ground via resistors 45 and 46. Then, the power control unit 50 terminates the discharge process.

[0103] Electric double-layer capacitors degrade over time. The rate of degradation varies depending on the operating temperature and capacitance voltage. For example, the lower the voltage applied to the electric double-layer capacitor, the slower the degradation process will be.

[0104] In the power supply device 1 according to this embodiment, when it is determined that the device is transitioning to a stopped state, the voltage applied to the electric double-layer capacitor is reduced to or below the storage voltage value Vsc_stg, thereby suppressing the deterioration of the electric double-layer capacitor.

[0105] Furthermore, the discharge of the electromagnetic double-layer capacitor is not limited to the discharge process described above. For example, discharge may be performed by an equalization process, or by a process of supplying power to a load such as the load device 200 (power supply process). In other words, when the power supply control unit 50 detects a transition to a sleep state, it may perform a discharge of the energy storage circuit 10 by executing at least one of the power supply process, discharge process, and equalization process. The power supply control unit 50 may also perform a discharge of the energy storage circuit 10 by arbitrarily combining the power supply process, discharge process, and equalization process. For example, the power supply control unit 50 may first perform a discharge process until the terminal voltage Vtc reaches a predetermined reference voltage (first reference voltage), and then perform a power supply process until the voltage becomes even lower (second reference voltage).

[0106] Furthermore, during the discharge process, the discharge and stopping of discharge may be repeated multiple times. For example, the procedure of starting the discharge, stopping the discharge after a certain period of time, measuring the terminal voltage Vtc, and if it is greater than the storage voltage value Vsc_stg, starting and stopping the discharge again may be repeated multiple times.

[0107] Furthermore, the discharge process is not limited to the use of the equalizing discharge circuit 40; a separate discharge circuit with a discharge resistor may also be provided in addition to the equalizing discharge circuit 40.

[0108] [Transition to stopped state] Once the discharge process is complete, the vehicle transitions to a stopped state (step S60). The stopped state is a state in which systems such as electric latches stop operating and the entire vehicle consumes low power. In transitioning to the stopped state, the power control unit 50 obtains information from the vehicle control unit 300 regarding the vehicle's status, for example, whether it is in use or stopped. The power control unit 50 then determines whether the vehicle is in use or stopped (step S70).

[0109] If the vehicle is not in use (No in step S70), the power control unit 50 repeats step S70. If it determines that the vehicle is in use (Yes in step S70), the power control unit 50 proceeds to the process in step S75. Instead of the power control unit 50 repeatedly making the determination in step S70 when the vehicle is not in use, the determination of whether the vehicle is in use may be made by startup information, vehicle information, etc., sent from the vehicle control unit 300, etc., to the power control unit 50.

[0110] (Step S75) The power control unit 50 measures the terminal voltage Vtc. The power control unit 50 then determines whether the voltage value of the terminal voltage Vtc is lower than the threshold voltage value Vsc_th2. If the voltage value of the terminal voltage Vtc is greater than or equal to the threshold voltage value Vsc_th2 (No in step S75), the power control unit 50 proceeds to step S90. If the voltage value of the terminal voltage Vtc is lower than the threshold voltage value Vsc_th2 (Yes in step S75), the power control unit 50 proceeds to step S80.

[0111] In a stationary state, the terminal voltage Vtc of each of the electric double-layer capacitors 11 and 12 decreases over time due to leakage current in the electric double-layer capacitors and the circuit. Therefore, by measuring the terminal voltage Vtc of the energy storage circuit 10, the period during which it was stationary can be estimated.

[0112] For example, the power supply control unit 50 determines that the period during which the device was in a stopped state is the threshold period when the terminal voltage Vtc of the energy storage circuit 10 is equal to the threshold voltage value Vsc_th2. In other words, the power supply control unit 50 determines that the period during which the device was in a stopped state is longer than the threshold period if the terminal voltage Vtc is lower than the threshold voltage value Vsc_th2.

[0113] If the period of inactivity is prolonged, the characteristics of electric double-layer capacitors 11 and 12 may differ from those measured in step S20. Therefore, in the power supply device 1 according to this embodiment, if the terminal voltage Vtc is lower than a predetermined threshold voltage Vsc_th2, the characteristics of the energy storage circuit 10 are measured assuming that the inactivity has continued for a long period of time.

[0114] [Rechargeable characteristic measurement process] The rechargeable characteristic measurement process of the energy storage circuit 10 in the power control unit 50 of the power supply device 1 according to the first embodiment will be described. Figure 13 is a flowchart illustrating the rechargeable characteristic measurement process of the power supply device 1 according to the first embodiment. The rechargeable characteristic measurement process includes a capacity value measurement process (step S82) and an equivalent series resistance value measurement process (ESR value measurement process) (step S84). The power control unit 50 determines the capacity value and equivalent series resistance value of the energy storage circuit 10 as characteristics of the energy storage circuit 10.

[0115] [Capacitance value and equivalent series resistance value of the energy storage circuit 10] The characteristics of the energy storage circuit 10 in the power supply device 1 according to the first embodiment will be described. Figure 14 is an equivalent circuit diagram of the circuit that performs the rechargeable characteristic measurement processing of the energy storage circuit 10 in the power supply device 1 according to the first embodiment.

[0116] In the energy storage circuit 10 according to this embodiment, the electric double-layer capacitors 11 and 12 connected in series are considered as a single capacitor having an equivalent capacitance value Csc and a single resistor having a resistance value ESRsc connected in series with that capacitor. Then, the characteristics of the energy storage circuit 10 are determined using the capacitance value Csc and the resistance value ESRsc.

[0117] In the energy storage circuit 10 according to the first embodiment, the energy storage circuit 10 is charged from a constant voltage source. The power supply 100 is a constant voltage source. The energy storage circuit 10 is charged at a constant voltage with the power supply voltage Vbat of the power supply 100. The energy storage circuit 10 includes a charging resistor Rc and a switch SWc between the power supply 100 and the energy storage circuit 10. For example, the charging circuit 20 includes a charging resistor Rc and a switch SWc.

[0118] [Measurement of the capacity value of the energy storage circuit 10] Figure 15 is a flowchart of the capacity value measurement process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. When this process is performed, the boost circuit 30 and the equalization discharge circuit 40 stop operating. In other words, the energy storage circuit 10 is not supplying power to the load device 200 or performing equalization discharge operations.

[0119] The processing procedure of the power control unit 50 of the power supply unit 1 and the control method of the power supply unit 1 according to the first embodiment will be explained in accordance with the flowchart in Figure 15.

[0120] (Step S821) First, the power control unit 50 turns on (closes) the switch SWc. When the switch SWc is turned on (closed), the power supply 100 and the charging resistor Rc are connected to the energy storage circuit 10. Once the power supply 100 and the charging resistor Rc are connected to the energy storage circuit 10, the energy storage circuit 10 is charged from the power supply 100 via the charging resistor Rc. When the energy storage circuit 10 is charged, the terminal voltage Vtc of the energy storage circuit 10 begins to rise.

[0121] (Step S822) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10. The power control unit 50 then records (acquires) the measured terminal voltage Vtc as the starting voltage value V4. It also starts the timer count.

[0122] (Step S823) Next, the power control unit 50 determines whether the voltage value of the terminal voltage Vtc of the energy storage circuit 10 has become equal to or greater than the predetermined termination voltage value V5. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is lower than the predetermined termination voltage value V5 (No in step S823), step S823 is repeated. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is equal to or greater than the predetermined termination voltage value V5 (Yes in step S823), the power control unit 50 proceeds to step S824. The termination voltage value V5 is set to a value higher than the starting voltage value V4.

[0123] (Step S824) Next, the power control unit 50 stops the timer count and records the count value. Then, the power control unit 50 calculates and records the time T1 from the count value, from when the timer count started until it stopped. It is desirable that the process in step S824 be performed simultaneously with step S823 or as quickly as possible within the limits of what the power control unit 50 can perform after step S823 has been executed.

[0124] (Step S825) Next, the power control unit 50 turns off (opens) the switch SWc. When the switch SWc is turned off (opens), the power supply 100 and the charging resistor Rc are disconnected from the energy storage circuit 10.

[0125] (Step S826) Next, the power control unit 50 calculates the capacitance value Csc using Equation 4, based on the measured start voltage value V4 and end voltage value V5, and the time T1. Note that the resistance value R is the resistance value of the charging resistance Rc, and Ln represents the natural logarithm.

[0126]

number

[0127] For example, in step S823, if the terminal voltage Vtc of the energy storage circuit 10 becomes equal to or greater than the termination voltage V5, the terminal voltage Vtc may be measured again and set as the termination voltage V5. Alternatively, the set time Ts may be set first, the switch SWc may be turned on (closed), the terminal voltage Vtc may be measured in step S822, and then the terminal voltage Vtc of the energy storage circuit 10 after time Ts has elapsed may be measured as the termination voltage V5. When setting time Ts, time T1 in equation 4 should be time Ts.

[0128] The power supply device 1 according to this embodiment can measure the capacity value of the energy storage circuit 10 during charging when current flows into the energy storage circuit 10. Furthermore, by measuring the capacity value of the energy storage circuit 10, the power supply device 1 according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0129] [Measurement of the equivalent series resistance of the energy storage circuit 10] Figure 16 is a flowchart of the equivalent series resistance measurement process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. When this process is performed, the boost circuit 30 and the equalization discharge circuit 40 are stopped. In other words, the energy storage circuit 10 is not supplying power to the load device 200 or performing equalization discharge operations.

[0130] The processing procedure of the power control unit 50 of the power supply unit 1 and the control method of the power supply unit 1 according to this embodiment will be explained in accordance with the flowchart in Figure 16.

[0131] (Step S841) First, the power control unit 50 turns on (closes) the switch SWc. When the switch SWc is turned on (closed), the power supply 100 and the charging resistor Rc are connected to the energy storage circuit 10. Once the power supply 100 and the charging resistor Rc are connected to the energy storage circuit 10, the energy storage circuit 10 is charged from the power supply 100 via the charging resistor Rc. When the energy storage circuit 10 is charged, the terminal voltage Vtc of the energy storage circuit 10 begins to rise.

[0132] (Step S842) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50 stores (acquires) the measured terminal voltage Vtc as the conduction voltage value Vsc_on1.

[0133] (Step S843) Next, immediately after measuring the terminal voltage Vtc of the energy storage circuit 10 in step S842, the power control unit 50 turns off (opens) the switch SWc. When the switch SWc is turned off (opens), the power supply 100 and the charging resistor Rc are disconnected from the energy storage circuit 10. It is desirable that the process in step S843 be performed simultaneously with step S842 or as quickly as possible within the limits of what the power control unit 50 can perform after step S842.

[0134] (Step S844) Next, the power control unit 50 measures the terminal voltage Vtc of the energy storage circuit 10 after the switch SWc is turned off (open). The power control unit 50 then stores (acquires) the measured terminal voltage Vtc as the non-conductive voltage value Vsc_off1.

[0135] (Step S845) Next, the power control unit 50 calculates the equivalent series resistance value ESR using Equation 5, based on the measured conduction voltage value Vsc_on1 and non-conduction voltage value Vsc_off1. Note that the resistance value R is the resistance value of the charging resistance Rc.

[0136]

number

[0137] The power supply device 1 according to this embodiment can measure the capacitance value and equivalent series resistance value of the energy storage circuit 10 during charging when current flows into the energy storage circuit 10. Furthermore, by measuring the capacitance value and equivalent series resistance value of the energy storage circuit 10, the power supply device 1 according to this embodiment can monitor the characteristic degradation of the electric double-layer capacitor provided in the energy storage circuit 10.

[0138] For example, even if the capacitance value and equivalent series resistance are measured in step S20, if the system is left in a stopped state for a long period of time, the capacitance value and equivalent series resistance measured during discharge may not be valid. Therefore, in step S75, if it is determined that the system has been in a stopped state for a long period of time by measuring the terminal voltage Vtc of the energy storage circuit 10, the capacitance value and equivalent series resistance are measured when transitioning to the operating state in step S80. By measuring the capacitance value and equivalent series resistance when transitioning to the operating state, the capacitance value and equivalent series resistance at the time of transition can be accurately determined. The capacitance value and equivalent series resistance when transitioning to the operating state can be obtained by measuring during charging by the charging circuit, or during discharge by the discharge circuit, or both.

[0139] On the other hand, if the system has been in a stopped state for a short period, the capacitance value and equivalent series resistance value measured during discharge can be used to immediately determine and announce the degradation of these values. Furthermore, during charging, only charging operations are performed and no measurements are taken, thereby reducing the processing load on the power control unit and shortening the charging period of the power supply unit 1. In addition, even in the case of a short-term stopped state, the capacitance value and equivalent series resistance value may be obtained each time or as needed by measuring during charging using the charging circuit, measuring during discharge using the discharge circuit, or measuring in both cases.

[0140] The capacitance value and equivalent series resistance value measured in step S80 are examples of the first capacitance value and the first equivalent series resistance value, respectively, while the capacitance value and equivalent series resistance value measured in step S20 are examples of the second capacitance value and the second equivalent series resistance value, respectively.

[0141] [Charging process] Next, the charging process in step S90 will be described. Figure 17 is a flowchart of the charging process of the energy storage circuit 10 in the power supply device 1 according to the first embodiment. The charging process will be explained using the equivalent circuit diagram in Figure 14.

[0142] (Step S91) First, the power control unit 50 turns on (closes) the switch SWc and connects the power supply 100 and the charging resistor Rc to the energy storage circuit 10. By connecting the power supply 100 and the charging resistor Rc to the energy storage circuit 10, the electric double-layer capacitors 11 and 12 of the energy storage circuit 10 are charged. Therefore, the terminal voltage Vtc gradually rises. At this time, the switch SWc may be turned on (closed) intermittently to perform PWM operation, or the PWM duty cycle may be changed to simulate constant current charging.

[0143] (Step S92) Next, the power control unit 50 measures the terminal voltage Vtc. The power control unit 50 then determines whether the voltage value of the terminal voltage Vtc is higher than the operating voltage value Vact. If the voltage value of the terminal voltage Vtc is less than or equal to the operating voltage value Vact (No in step S93), the power control unit 50 repeats step S92. If the voltage value of the terminal voltage Vtc is higher than the operating voltage value Vact (Yes in step S92), the power control unit 50 proceeds to step S93.

[0144] (Step S93) Next, the power control unit 50 turns off (opens) the switch SWc, disconnecting the power supply 100 and the charging resistor Rc from the energy storage circuit 10. Then, the power control unit 50 terminates the charging process.

[0145] <<Second Embodiment>> <Power supply unit 1a> Figure 18 shows an example of the configuration of the power supply unit 1a according to this embodiment. The power supply unit 1a is further equipped with a constant current discharge circuit 48 in addition to the power supply unit 1. Furthermore, the power supply unit 1a is equipped with a charging circuit 20a and a power supply control unit 50a, respectively, instead of the charging circuit 20 and power supply control unit 50 of the power supply unit 1.

[0146] [Constant current discharge circuit 48] The constant current discharge circuit 48 is a circuit that discharges from the energy storage circuit 10 at a predetermined constant current. The constant current discharge circuit 48 is controlled by the power supply control unit 50a. The power supply control unit 50a controls the constant current discharge circuit 48 with the discharge control signal CTL6.

[0147] The power supply device 1a according to the second embodiment differs from the power supply device 1 according to the first embodiment in the content of the discharge-type characteristic measurement process in step S20 and the content of the recharge-type characteristic measurement process in step S80.

[0148] [Discharge-type characteristic measurement process] First, the discharge-type characteristic measurement process of the energy storage circuit 10 in the power control unit 50a of the power supply device 1a according to the second embodiment will be described. Figure 19 is a flowchart illustrating the discharge-type characteristic measurement process of the power supply device 1a according to the second embodiment. The discharge-type characteristic measurement process includes a capacity value measurement process (step S122) and an equivalent series resistance value measurement process (ESR value measurement process) (step S124). The power control unit 50a determines the capacity value and equivalent series resistance value of the energy storage circuit 10 as characteristics of the energy storage circuit 10.

[0149] [Capacitance value and equivalent series resistance value of the energy storage circuit 10] The characteristics of the energy storage circuit 10 in the power supply device 1a according to the second embodiment will now be described. Figure 20 is an equivalent circuit diagram of the circuit that performs the discharge-type characteristic measurement processing of the energy storage circuit 10 in the power supply device 1a according to the second embodiment.

[0150] In the energy storage circuit 10 according to this embodiment, the electric double-layer capacitors 11 and 12 connected in series are considered as a single capacitor having an equivalent capacitance value Csc and a single resistor having a resistance value ESRsc connected in series with that capacitor. Then, the characteristics of the energy storage circuit 10 are determined using the capacitance value Csc and the resistance value ESRsc.

[0151] The constant current discharge circuit 48 comprises a constant current source CCSd and a switch SWd1. When the switch SWd1 is turned on (closed), the constant current source CCSd flows a constant current I_ccsd.

[0152] [Measurement of the capacity value of the energy storage circuit 10] Figure 21 is a flowchart of the capacity value measurement process of the energy storage circuit 10 in the power supply device 1a according to the second embodiment. When this process is performed, the charging circuit 20a and the boost circuit 30 stop operating. That is, the energy storage circuit 10 is not being charged from the power supply 100. Also, the energy storage circuit 10 is not supplying power to the load device 200. Furthermore, switches SW1 and SW2 of the equalization discharge circuit 40 are assumed to be off (open).

[0153] Following the flowchart in Figure 21, the processing procedure of the power control unit 50a of the power supply unit 1a according to the second embodiment and the steps of the control method of the power supply unit 1a will be explained.

[0154] (Step S1221) First, the power control unit 50a turns on (closes) the switch SWd1 of the constant current discharge circuit 48. When switch SWd1 is turned on (closed), the constant current source CCSd is connected to the energy storage circuit 10. When the constant current source CCSd is connected to the energy storage circuit 10, a constant current I_ccsd flows from the energy storage circuit 10 to ground. When a constant current I_ccsd flows from the energy storage circuit 10 to ground, the terminal voltage Vtc of the energy storage circuit 10 begins to decrease.

[0155] (Step S1222) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50a records (acquires) the measured terminal voltage Vtc as the starting voltage value V11. It also starts the timer count.

[0156] (Step S1223) Next, the power control unit 50a determines whether the voltage value of the terminal voltage Vtc of the energy storage circuit 10 has become less than or equal to the predetermined termination voltage value V12. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is higher than the predetermined termination voltage value V12 (No in step S1223), step S1223 is repeated. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is less than or equal to the predetermined termination voltage value V12 (Yes in step S1223), the power control unit 50a proceeds to step S1224. The termination voltage value V12 is set to a value lower than the starting voltage value V11.

[0157] (Step S1224) Next, the power control unit 50a stops the timer count and records the count value. Then, the power control unit 50a calculates and records the time T2 from the count value, which is the time from when the timer count started until when it stopped. It is desirable that the process in step S1224 be performed simultaneously with step S1223 or as quickly as possible within the limits of what the power control unit 50a can perform after step S1223 has been executed.

[0158] (Step S1225) Next, the power control unit 50a turns off (opens) switch SWd1. When switch SWd1 is turned off (opens), the constant current source CCSd is disconnected from the energy storage circuit 10.

[0159] (Step S1226) Next, the power control unit 50a calculates the capacitance value Csc using Equation 6, based on the measured start voltage value V11 and end voltage value V12, and time T2. The current value Ic is the current value of the constant current I_ccsd flowing through the constant current source CCSd.

[0160]

number

[0161] For example, in step S1223, if the terminal voltage Vtc of the energy storage circuit 10 falls below, for example, the termination voltage V12, the terminal voltage Vtc may be measured again and set as the termination voltage V12. Alternatively, the set time Ts may be set first, the switch SWd1 may be turned on (closed), the terminal voltage Vtc may be measured in step S1222, and then the terminal voltage Vtc of the energy storage circuit 10 after time Ts has elapsed may be measured as the termination voltage V12. When setting time Ts, time T2 in equation 6 should be time Ts.

[0162] The power supply device 1a according to this embodiment can measure the capacitance value of the energy storage circuit 10 during discharge when current is released from the energy storage circuit 10. Furthermore, by measuring the capacitance value of the energy storage circuit 10, the power supply device 1a according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0163] [Measurement of the equivalent series resistance of the energy storage circuit 10] Figure 22 is a flowchart of the equivalent series resistance measurement process of the energy storage circuit 10 in the power supply device 1a according to the second embodiment. When this process is performed, the charging circuit 20a and the boost circuit 30 are stopped. That is, the energy storage circuit 10 is not being charged from the power supply 100. Also, the energy storage circuit 10 is not supplying power to the load device 200. Furthermore, switches SW1 and SW2 of the equalization discharge circuit 40 are assumed to be off (open).

[0164] The processing procedure of the power control unit 50a of the power supply unit 1a and the control method of the power supply unit 1a according to this embodiment will be explained in accordance with the flowchart in Figure 22.

[0165] (Step S1241) First, the power control unit 50a turns on (closes) switch SWd1. When switch SWd1 is turned on (closed), the constant current source CCSd is connected to the energy storage circuit 10. When the constant current source CCSd is connected to the energy storage circuit 10, a constant current I_ccsd flows from the energy storage circuit 10 to ground. When a constant current I_ccsd flows from the energy storage circuit 10 to ground, the terminal voltage Vtc of the energy storage circuit 10 begins to decrease.

[0166] (Step S1242) Next, the power control unit 50a waits for a certain period of time. For example, the power control unit 50a waits for a certain period of time until the current I_ccsd stabilizes.

[0167] (Step S1243) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50a stores (acquires) the measured terminal voltage Vtc as the conduction voltage value Vsc_on2.

[0168] (Step S1244) Next, immediately after measuring the terminal voltage Vtc of the energy storage circuit 10 in step S1243, the power control unit 50a turns off (opens) the switch SWd1. When the switch SWd1 is turned off (opens), the constant current source CCSd is disconnected from the energy storage circuit 10. It is desirable that the process in step S1244 be performed simultaneously with step S1243 or as quickly as possible within the limits of what the power control unit 50a can perform after step S1243 has been executed.

[0169] (Step S1245) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10 after the switch SW1 is turned off (open). Then, the power control unit 50a stores (acquires) the measured terminal voltage Vtc as the non-conductive voltage value Vsc_off2.

[0170] (Step S1246) Next, the power control unit 50a calculates the equivalent series resistance value ESR using Equation 7, based on the measured conduction voltage value Vsc_on2 and non-conduction voltage value Vsc_off2. Note that the current value Ic is the current value of the constant current I_ccsd flowing through the constant current source CCSd.

[0171]

number

[0172] The power supply device 1a according to this embodiment can measure the equivalent series resistance of the energy storage circuit 10 during discharge when current is released from the energy storage circuit 10. Furthermore, by measuring the equivalent series resistance of the energy storage circuit 10, the power supply device 1a according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0173] [Rechargeable characteristic measurement process] The rechargeable characteristic measurement process of the energy storage circuit 10 in the power control unit 50a of the power supply device 1a according to the second embodiment will be described. Figure 23 is a flowchart illustrating the rechargeable characteristic measurement process of the power supply device 1a according to the second embodiment. The rechargeable characteristic measurement process includes a capacity value measurement process (step S182) and an equivalent series resistance value measurement process (ESR value measurement process) (step S184). The power control unit 50a determines the capacity value and equivalent series resistance value of the energy storage circuit 10 as characteristics of the energy storage circuit 10.

[0174] [Capacitance value and equivalent series resistance value of the energy storage circuit 10] The characteristics of the energy storage circuit 10 in the power supply device 1a according to the second embodiment will now be described. Figure 24 is an equivalent circuit diagram of the circuit that performs the rechargeable characteristic measurement processing of the energy storage circuit 10 in the power supply device 1a according to the second embodiment.

[0175] In the energy storage circuit 10 according to this embodiment, the electric double-layer capacitors 11 and 12 connected in series are considered as a single capacitor having an equivalent capacitance value Csc and a single resistor having a resistance value ESRsc connected in series with that capacitor. Then, the characteristics of the energy storage circuit 10 are determined using the capacitance value Csc and the resistance value ESRsc.

[0176] In the energy storage circuit 10 according to the second embodiment, the energy storage circuit 10 is charged from a constant current source CCSc. The power supply 101 is a constant current source CCSc. The power supply 101 is configured by combining, for example, a power supply 100 and a charging circuit 20a. The power supply 101 charges the energy storage circuit 10 with a constant current I_ccsc. The power supply device 1a includes a switch SWc1 between the power supply 101 and the energy storage circuit 10. For example, the charging circuit 20a includes a switch SWc1.

[0177] [Measurement of the capacity value of the energy storage circuit 10] Figure 25 is a flowchart of the capacity value measurement process of the energy storage circuit 10 in the power supply device 1a according to the second embodiment. When this process is performed, the boost circuit 30, the equalization discharge circuit 40, and the constant current discharge circuit 48 stop operating. In other words, the energy storage circuit 10 does not supply power to the load device 200, and neither the equalization discharge operation nor the constant current discharge operation is performed.

[0178] Following the flowchart in Figure 25, the processing procedure of the power control unit 50a of the power supply unit 1a and the control method of the power supply unit 1a according to the second embodiment will be explained.

[0179] (Step S1821) First, the power control unit 50a turns on (closes) switch SWc1. When switch SWc1 is turned on (closed), the power supply 101 is connected to the energy storage circuit 10. When the power supply 101 is connected to the energy storage circuit 10, the energy storage circuit 10 is charged by the power supply 101. When the energy storage circuit 10 is charged, the terminal voltage Vtc of the energy storage circuit 10 begins to rise.

[0180] (Step S1822) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50a records (acquires) the measured terminal voltage Vtc as the starting voltage value V13. It also starts the timer count.

[0181] (Step S1823) Next, the power control unit 50a determines whether the voltage value of the terminal voltage Vtc of the energy storage circuit 10 has become equal to or greater than the predetermined termination voltage value V14. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is lower than the predetermined termination voltage value V14 (No in step S1823), step S1823 is repeated. If the voltage value of the terminal voltage Vtc of the energy storage circuit 10 is equal to or greater than the predetermined termination voltage value V14 (Yes in step S1823), the power control unit 50a proceeds to step S1824. The termination voltage value V14 is set to a value higher than the starting voltage value V13.

[0182] (Step S1824) Next, the power control unit 50a stops the timer count and records the count value. Then, the power control unit 50a calculates and records the time T3 from the count value, which is the time from when the timer count started until it stopped. It is desirable that the process in step S1824 be performed simultaneously with step S1823 or as quickly as possible within the limits of what the power control unit 50a can perform after step S1823 has been executed.

[0183] (Step S1825) Next, the power control unit 50a turns off (opens) switch SWc1. When switch SWc1 is turned off (opens), the power supply 101 is disconnected from the energy storage circuit 10.

[0184] (Step S1826) Next, the power control unit 50a calculates the capacitance value Csc using Equation 8, based on the measured start voltage value V13 and end voltage value V14, and the time T3. The current value Ic is the current value of the constant current I_ccsc flowing through the constant current source CCSc.

[0185]

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[0186] For example, in step S1823, if the terminal voltage Vtc of the energy storage circuit 10 becomes equal to or greater than the termination voltage V14, the terminal voltage Vtc may be measured again and set as the termination voltage V14. Alternatively, the set time Ts may be set first, the switch SWc1 may be turned on (closed), the terminal voltage Vtc may be measured in step S1822, and then the terminal voltage Vtc of the energy storage circuit 10 after time Ts has elapsed may be measured as the termination voltage V14. When setting time Ts, time T3 in equation 8 should be time Ts.

[0187] The power supply device 1a according to this embodiment can measure the capacity value of the energy storage circuit 10 during charging when current flows into the energy storage circuit 10. Furthermore, by measuring the capacity value of the energy storage circuit 10, the power supply device 1a according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0188] [Measurement of the equivalent series resistance of the energy storage circuit 10] Figure 26 is a flowchart of the equivalent series resistance measurement process of the energy storage circuit 10 in the power supply device 1a according to the second embodiment. When this process is performed, the boost circuit 30 stops operating. In other words, the energy storage circuit 10 is not supplying power to the load device 200.

[0189] The processing procedure of the power control unit 50a of the power supply unit 1a and the control method of the power supply unit 1a according to this embodiment will be explained in accordance with the flowchart in Figure 26.

[0190] (Step S1841) First, the power control unit 50a turns on (closes) switch SWc1. When switch SWc1 is turned on (closed), the power supply 101 is connected to the energy storage circuit 10. When the power supply 101 is connected to the energy storage circuit 10, the energy storage circuit 10 is charged by the power supply 101. As the energy storage circuit 10 is charged, the terminal voltage Vtc of the energy storage circuit 10 gradually rises.

[0191] (Step S1842) Next, the power control unit 50a waits for a certain period of time. For example, the power control unit 50a waits for a certain period of time until the charging current stabilizes.

[0192] (Step S1843) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10. Then, the power control unit 50a stores (acquires) the measured terminal voltage Vtc as the conduction voltage value Vsc_on3.

[0193] (Step S1844) Next, immediately after measuring the terminal voltage Vtc of the energy storage circuit 10 in step S1843, the power supply control unit 50a turns off (opens) switch SWc1. When switch SWc1 is turned off (opens), the power supply 101 is disconnected from the energy storage circuit 10. It is desirable that the process in step S1844 be performed simultaneously with step S1843 or as quickly as possible within the limits of what the power supply control unit 50a can perform after step S1843 has been executed.

[0194] (Step S1845) Next, the power control unit 50a measures the terminal voltage Vtc of the energy storage circuit 10 after the switch SWc1 is turned off (open). Then, the power control unit 50a stores (acquires) the measured terminal voltage Vtc as the non-conductive voltage value Vsc_off3.

[0195] (Step S1846) Next, the power control unit 50a calculates the equivalent series resistance value ESR using Equation 9, based on the measured conduction voltage value Vsc_on3 and non-conduction voltage value Vsc_off3. Note that the current value Ic is the current value I_ccsc, which is the constant current flowing through the constant current source CCSc.

[0196]

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[0197] The power supply device 1a according to this embodiment can measure the capacity value of the energy storage circuit 10 during charging when current flows into the energy storage circuit 10. Furthermore, by measuring the capacity value of the energy storage circuit 10, the power supply device 1a according to this embodiment can monitor the degradation of the characteristics of the electric double-layer capacitor provided in the energy storage circuit 10.

[0198] <<Third Embodiment>> In the power supply device 1 according to the first embodiment and the power supply device 1a according to the second embodiment, a discharge-type characteristic measurement process was performed in step S20 and a recharge-type characteristic measurement process was performed in step S80. However, in each of steps S20 and S80, a characteristic measurement process combining the discharge-type characteristic measurement process and the recharge-type characteristic measurement process may be performed.

[0199] [Characteristic measurement process] Figure 27 is a flowchart illustrating a characteristic measurement process that combines a discharge-type characteristic measurement process and a recharge-type characteristic measurement process. The characteristic measurement process that combines a discharge-type characteristic measurement process and a recharge-type characteristic measurement process includes a discharge-type characteristic measurement process (step S201) and a recharge-type characteristic measurement process (step S202).

[0200] The discharge-type characteristic measurement process in step S201 is, for example, the discharge-type characteristic measurement process for the power supply unit 1 according to the first embodiment (see Figures 5 and 9), and the discharge-type characteristic measurement process for the power supply unit 1a according to the second embodiment (see Figure 19). The recharge-type characteristic measurement process in step S202 is, for example, the recharge-type characteristic measurement process for the power supply unit 1 according to the first embodiment (see Figure 13), and the recharge-type characteristic measurement process for the power supply unit 1a according to the second embodiment (see Figure 23).

[0201] Then, in step S203, the power supply control unit 50a combines the measurement results from the discharge-type characteristic measurement process in step S201 and the recharge-type characteristic measurement process in step S202 to determine the capacity value and equivalent series resistance value of the energy storage circuit 10 as characteristics of the energy storage circuit 10.

[0202] For example, the power supply control unit 50a may use the average or weighted average of the capacity value obtained in the discharge-type characteristic measurement process in step S201 and the capacity value obtained in the recharge-type characteristic measurement process in step S202 as the capacity value of the energy storage circuit 10. Alternatively, the power supply control unit 50a may use the average or weighted average of the equivalent series resistance value obtained in the discharge-type characteristic measurement process in step S201 and the equivalent series resistance value obtained in the recharge-type characteristic measurement process in step S202 as the equivalent series resistance value of the energy storage circuit 10.

[0203] Furthermore, for example, the power supply control unit 50a may select the capacity value obtained in the discharge-type characteristic measurement process in step S201 and the capacity value obtained in the recharge-type characteristic measurement process in step S202, which is estimated to be more reliable, and use that as the capacity value of the energy storage circuit 10. Alternatively, the power supply control unit 50a may select the equivalent series resistance value obtained in the discharge-type characteristic measurement process in step S201 and the equivalent series resistance value obtained in the recharge-type characteristic measurement process in step S202, which is estimated to be more reliable, and use that as the equivalent series resistance value of the energy storage circuit 10.

[0204] <Effects and Actions> In this embodiment, the power supply device can acquire the characteristics of the electric double layer capacitor that are effective at the start of use by acquiring the characteristics of the electric double layer capacitor when it is determined that the period of shutdown is longer than the threshold period.

[0205] Although the power supply device has been described above with reference to embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements, such as combinations or substitutions with some or all of other embodiments, are possible within the scope of the present invention.

[0206] The power supply device according to this embodiment is not limited to a backup power supply for an electric latch system, but may also be used as a backup power supply for, for example, a brake system (including an electric parking brake) or an airbag system. Furthermore, the power supply device according to this embodiment is not limited to a backup power supply, but may also be used as a main power supply (a power supply used under normal conditions). [Explanation of symbols]

[0207] 1, 1a power supply 10 Energy storage circuit 11, 12 Electric double-layer capacitors 20A charging circuit 30 Boost Circuit 40 Equalization discharge circuit 41 switches 41a 1st terminal 41b 2nd terminal 42 switches 42a Terminal 1 42b 2nd terminal 45 Resistors 46 resistors 48 Constant current discharge circuit 50, 50a Power Control Unit 300 Vehicle Control Unit

Claims

1. A power storage circuit having a first node connected to a battery and a second node grounded, with an electric double-layer capacitor between the first node and the second node, A charging circuit connected to the first node and used to charge the energy storage circuit, A discharge circuit connected to the first node and used to discharge the energy storage circuit, The system includes a power control unit that measures the voltage of the first node and controls the charging circuit and the discharging circuit, The power supply control unit, A procedure for determining if the vehicle is stationary for a period longer than a threshold period, causing the charging circuit to charge the energy storage circuit, and calculating the first capacitance value and first equivalent series resistance value of the electric double-layer capacitor based on the measured voltage of the first node, A procedure for calculating the second capacitance value and the second equivalent series resistance value of the electric double-layer capacitor based on the voltage at the first node while discharging in the discharge circuit, Execute, The power supply control unit, If it is determined that the stop period is longer than the threshold period, the deterioration of the electric double-layer capacitor is determined based on the first capacitance value and the first equivalent series resistance value. If it is determined that the stop period is shorter than the threshold period, the deterioration of the electric double layer capacitor is determined based on the second capacitance value and the second equivalent series resistance value. power supply.

2. The power supply control unit, The shutdown period is estimated based on the voltage of the first node. The power supply device according to claim 1.

3. A power storage circuit having a first node connected to a battery and a second node grounded, with an electric double-layer capacitor between the first node and the second node, A charging circuit connected to the first node and used to charge the energy storage circuit, A discharge circuit connected to the first node and used to discharge the energy storage circuit, A control method for a power supply device comprising: A procedure for determining if the vehicle is stationary for a period longer than a threshold period, causing the charging circuit to charge the energy storage circuit, and calculating the first capacitance value and first equivalent series resistance value of the electric double-layer capacitor based on the measured voltage of the first node, A procedure for calculating the second capacitance value and the second equivalent series resistance value of the electric double-layer capacitor based on the voltage at the first node while discharging in the discharge circuit, Includes, If it is determined that the stop period is longer than the threshold period, the deterioration of the electric double-layer capacitor is determined based on the first capacitance value and the first equivalent series resistance value. If it is determined that the stop period is shorter than the threshold period, the deterioration of the electric double layer capacitor is determined based on the second capacitance value and the second equivalent series resistance value. A method for controlling a power supply unit.

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