JP5277711B2 - Power supply device and vehicle power supply device - Google Patents

Abstract

Provided are a power supply apparatus and a power supply apparatus for vehicles capable of suppressing temperature increases in the capacitor and degradation of the capacitor. A secondary battery, a capacitor connected in parallel to the secondary battery, a detection means for detecting the capacitor's temperature and the capacitor's voltage, a switching element which controls the discharge current from the capacitor based on the detected value of the detection means, and a switching element which at least limits or cuts off the charging current to the capacitor based on the detected value of the detection means.

Description

  The present invention relates to a power supply apparatus and a vehicle power supply apparatus that are hybridly configured with a secondary battery and a capacitor.

  Due to recent advances in battery technology, the spread of hybrid vehicles is rapidly progressing. The hybrid vehicle has a system that uses a secondary battery to drive a motor or the like and regenerates energy during deceleration to the secondary battery. Secondary batteries have evolved from sealed lead batteries to Ni-hydrogen batteries and further to Li-ion batteries with the advent of new secondary batteries, miniaturization and weight reduction, and higher output density. In any secondary battery, the development of battery active materials and the development of high-capacity and high-power battery structures have been carried out in order to increase the energy density, and efforts have been made to realize a power source with a high output density and a long usable time. Has been made.

  Efforts are being made to improve fuel efficiency in the automobile field, but it is expected that new fuel efficiency improvement functions will be added to existing vehicles in order to reduce emissions such as carbon dioxide. Therefore, a low-loss power source, that is, a power source with a low internal resistance is required.

  When a power supply with a small internal resistance is realized by a secondary battery, the small maximum output current becomes a problem. Therefore, there is an increasing need for capacitors that do not require a limitation on output current, and an electric double layer capacitor (EDLC) is generally known as an example. In addition, the electric double layer capacitor shows an intermediate characteristic between the capacitor and the secondary battery used for smoothing, etc., whereas the electric double layer capacitor shows an intermediate characteristic between the secondary battery, As a high energy density capacitor, there is a hybrid capacitor (HC) using lithium ions as a negative electrode. Regarding these capacitors, since the energy density is small but the output density is higher than that of the secondary battery, an example applied to an idling stop system that requires instantaneous output is known (see, for example, Patent Document 1). However, since the capacitor generally has a large self-discharge, it is not practical to use the capacitor alone, and a hybrid configuration with the secondary battery is adopted. The secondary battery and the capacitor may be connected using a switch using a mechanical relay or a switch of a semiconductor element such as a MOSFET (metal oxide semiconductor field effect transistor) (see, for example, Patent Document 1). ).

JP 2006-152820 A

  In a power supply device using a capacitor, it is necessary to consider control for preventing abnormality (deterioration, heat generation) and failure of the capacitor. In order to realize starter motor power compensation at the time of restart in an idling stop system with a capacitor, in order to improve fuel efficiency by reducing resistance, it is arranged in the engine room like lead storage batteries to minimize the wiring length. However, it is a very severe condition in terms of temperature. Further, as described above, the capacitor can be expected from the existing secondary battery in terms of output density, but heat generated by the internal resistance and current is present in the same manner as the secondary battery. Therefore, when the capacitor deteriorates and the internal resistance becomes high, or when the capacitor becomes hot due to frequent input / output of current, it is necessary to reduce the heat generated by reducing the capacitor current. In order to reduce the heat generation of the capacitor, a method of cutting off the switch from the capacitor to the secondary battery can be considered.

  However, in such a case, a secondary battery such as a lead storage battery bears the total discharge current of a starter motor or the like, but a secondary battery such as a lead storage battery is prone to deterioration due to a large current charge / discharge. is there. Furthermore, secondary batteries such as lead-acid batteries have to be increased in performance and size so that the total discharge current can be ensured, so that the advantage of using a hybrid capacitor is reduced.

  Accordingly, an object of the present invention is to realize a control of the amount of power supplied to the secondary battery in which the state of the capacitor is matched by using a switching element in order to solve the above-described problem, and suppress the rise in the temperature of the capacitor and the deterioration of the capacitor. An object of the present invention is to provide a power supply device and a vehicle power supply device that can be used.

  In order to achieve the above object, a power supply device according to the present invention comprises a secondary battery and a capacitor connected in parallel to the secondary battery, and a detecting means for detecting the temperature of the capacitor and the voltage of the capacitor; A switching element that limits the discharge current from the capacitor based on the detection value of the detection means, and a switching element that performs at least one of limiting and cutting off the charging current to the capacitor based on the detection value of the detection means It is.

  According to the present invention, the temperature rise of the capacitor and the deterioration of the capacitor can be suppressed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram showing a power supply device according to a preferred first embodiment.

  As shown in FIG. 1, the power supply device 10 of this embodiment is connected to a rotating electrical machine 100 that is mounted on a vehicle and functions as an alternator / starter motor (generator / motor), for example. In the following description, when the rotating electrical machine 100 functions as a starter motor, it is referred to as “motor”, and when it functions as an alternator, it is referred to as “alternator”.

  The power supply device 10 includes a secondary battery 1 such as a lead storage battery and a capacitor 2 connected in parallel to each other. The capacitor 2 is formed by connecting a plurality of (four in the figure) capacitor cells 3 in series, and each capacitor cell 3 is an electric double layer capacitor cell.

  A discharge cut-off switching element (third switching element) 5 and a charge control switching unit 6 are connected in series to the current path 4 on the + side of the capacitor 2. The discharge cutoff switching element 5 includes an N-channel MOSFET 7 and a body diode 8 formed between the drain and source of the MOSFET 7 and connected in the direction opposite to the direction of the discharge current flowing from the capacitor 2 to the motor 100 side. The discharge cutoff switching element 5 allows a discharge current from the capacitor 2 to pass when the switch is turned on (gate on), and cuts off the discharge current when the switch is turned off. Further, the discharge cutoff switching element 5 allows a charging current to the capacitor 2 to pass through the body diode 8 regardless of whether the switch is on or off in a charging mode for the capacitor 2 described later.

  The charge control switching unit 6 is connected to the charge cutoff switching element (first switching element) 9, the charge / discharge limiting switching element (second switching element) 11, and the charge / discharge limiting switching element 11 side connected in parallel to each other. The charge limiting resistor 12 is provided. The charge cut-off switching element 9 and the charge / discharge limiting switching element 11 are formed between the N-channel MOSFET 7 and the drain-source of the N-channel MOSFET 7, respectively, and are connected in the direction opposite to the charging current flowing from the alternator 100 to the capacitor 2 side. And a body diode 8. The charge cut-off switching element 9 and the charge / discharge limit switching element 11 each pass a charge current to the capacitor 2 when the switch is turned on (gate on) and cut off the charge current when the switch is turned off. In addition, the charge interruption switching element 9 and the charge / discharge limiting switching element 11 allow the discharge current from the capacitor 2 to pass through each body diode 8 regardless of whether the switch is on or off in the discharge mode to the motor 100 described later. .

  A balance switch element 13 and a balance switch resistor 14 connected in series to the balance switch element 13 are connected to each capacitor cell 3 in parallel with each capacitor cell 3. Each balance switch element 13 includes a MOSFET 7 and a body diode 8 formed between the drain and source of the MOSFET 7 and connected in the direction opposite to the discharge current direction of the capacitor 2.

  The gates of the respective MOSFETs 7 constituting the discharge cutoff switching element 5, the charge cutoff switching element 9, the charge / discharge limiting switching element 11 and the balance switch 13 are connected to a discrimination control means 15 for switch control (ON / OFF) of the MOSFET 7. .

  The discrimination control means 15 monitors the temperature of the capacitor 2 and the deterioration of the capacitor 2 (voltage drop due to internal resistance generated in the capacitor cell 3), and controls each switch element according to the deterioration and temperature of the capacitor 2. It is.

  The discrimination control means 15 is composed of a microcomputer, and includes a boost gate driver for driving the gate of the MOSFET 7 (built in). As the step-up gate driver, any one such as a charge pump type that has a gate driving function of the N-channel MOSFET 7 may be used.

  The microcomputer 15 incorporates an A / D converter for monitoring the voltage of the capacitor 2 and monitors the voltage across the capacitor 2 (total voltage of the capacitor cells 3 connected in series) (path 16). In the figure, reference numeral 17 denotes a voltage measuring resistor. Further, the microcomputer 15 is sequentially switched and connected to each capacitor cell 3 using the multiplexer 18 (path 19), and monitors the voltage of each capacitor cell 3. The microcomputer 15 is connected to the secondary battery 1 (not shown) and also monitors the voltage of the secondary battery 1. In addition to the on / off control function of the MOSFET 7 of each switching element 5, 9, 11, 13 and the voltage monitoring function of the power source (capacitor 2, secondary battery 1), the microcomputer 15 is connected to a host ECU (Electronic Control Unit) provided in the vehicle. Communication function.

  The discrimination control means 15 is connected to a temperature detection means 20 for detecting the temperature of the capacitor 2 and a current detection means 23 for detecting a current flowing through the discharge cutoff switching element 5 and the charge cutoff switching element 9. .

  The temperature detection means 20 includes a PTC thermistor (Positive Temperature Coefficient) 21 connected to an A / D converter built in the microcomputer 15 and a voltage dividing resistor 22. The PTC thermistor 21 Mounted on.

  The current detection means 23 includes a differential amplifier connected to an A / D converter built in the microcomputer 15, and the differential amplifier is provided at both ends of the path from the discharge cutoff switching element 5 to the charge cutoff switching element 9. It is connected.

  Next, a method for controlling the power supply device 10 will be described with reference to FIGS.

(First control method)
In the normal state (while the capacitor 2 is charged and discharged without abnormality), the discharge cutoff switching element 5, the charge cutoff switching element 9, and the charge / discharge limiting switching element 11 are all in the ON state, and the balance switch element Reference numeral 13 denotes an OFF state, and the capacitor 2 is discharged or charged.

  As shown in FIG. 2, whether the temperature of the capacitor cell 3 detected by the temperature detecting means 20 is equal to or higher than a preset first temperature threshold value (lower limit of temperature determined to be abnormal) is determined control means. 15 is discriminated (step S1).

  When the temperature of the capacitor cell 3 does not exceed the first temperature threshold (S1 → N), the discharge cut-off switching element 5, the charge cut-off switching element 9, and the charge / discharge limit switching element are all normally operated while being ON ( Step S2). If the temperature of the capacitor cell 3 is equal to or higher than the first temperature threshold value (S1 → Y), it is determined whether the capacitor cell 3 is deteriorated (step S3). The deterioration of the capacitor cell 3 indicates that the internal resistance generated in the capacitor cell 3 is larger than a preset value (resistance deterioration). The internal resistance of each capacitor cell 3 is obtained by measuring the voltage of the capacitor cell 3 when the balance switch element 13 is turned off and the voltage of the capacitor cell 3 when the balance switch element 13 is turned on, and the difference voltage and the balance switch. It is obtained from the resistance value of the resistor 14 for use. The determination of the temperature and deterioration of the capacitor cell 3 is preferably performed for all the capacitor cells 2, but may be performed for at least one capacitor cell 3.

  When the capacitor cell 3 is not deteriorated (S3 → N), the switching elements 5, 9, and 11 are normally operated while being turned on (step S4).

  When the capacitor cell 3 has deteriorated (S3 → Y), as shown in FIG. 3, the mode in which only the charge cutoff switching element 9 is turned OFF while the discharge cutoff switching element 5 and the charge / discharge limiting switching element 11 remain ON. (Step S5, first control mode). In the first control mode, the discharge current when the capacitor 2 is discharged (when power is supplied to the motor 100) passes through the discharge cutoff switching element 5, and the body diode 8 on the charge cutoff switching element 9 side and the charge / discharge limiting switching element. 11, and after passing through these, they are combined and supplied to the motor 100.

  When the circuit configuration of the power supply device 10 in the first control mode is viewed from the secondary battery 1 side, the forward voltage of the body diode 8 of the charge cutoff switching element 9 is generated as a voltage drop. This circuit is equivalent to an increase in the equivalent series resistance (ESR) of the capacitor 2 as compared with the normal state. Therefore, at the time of discharging, the current balance between the secondary battery 1 and the capacitor 2 changes, and the discharging current of the capacitor 2 decreases.

However, when the capacitor 2 and the secondary battery 1 are discharged, the voltage of the capacitor 2 and the voltage of the secondary battery 1 are monitored, and when the voltage of the capacitor 2 becomes equal to or lower than the voltage of the secondary battery 1, the charge cutoff switching is performed. The switches of the element 9 and the charge / discharge cutoff switching element 11 are turned off. By turning off both the switching elements 9 and 11, the current path in the charging direction to the capacitor 2 is blocked, and the current supplied from the secondary battery 1 can be prevented from flowing to the capacitor 2.
The current path when the capacitor 2 is charged (when power is supplied from the alternator 100 to the capacitor 2) is OFF because the MOSFET 7 of the charge cutoff switching element 9 is OFF and its body diode 8 is in the opposite direction to the charge current direction. The path passes through the charge / discharge limiting switching element 11, the charge limiting resistor 12, and the discharge cutoff switching element 5 without passing through the switching element 9. In this current path, the charging current to the capacitor cell 3 becomes smaller than that during normal operation due to the charging limiting resistor 12.

  When the discharge current and the charge current of the capacitor cell 3 become small, the heat generation of the capacitor cell 3 is suppressed and the temperature of the capacitor cell 3 is lowered. The capacitor cell 3 is discharged and charged with the charge cutoff switching element 9 turned OFF, and the charge cutoff switching element 9 remains OFF until the temperature of the capacitor cell 3 becomes lower than a preset second temperature threshold. (Step S6 → Y).

  When the temperature of the capacitor cell 3 becomes lower than the second temperature threshold (S6 → N), the charge cutoff switching element 9 is turned on and normal operation is resumed (step S7). The second temperature threshold is set lower than the first temperature threshold in order to give hysteresis to the response of the charge cutoff switching element 9.

  As described above, with the configuration using the first control method, in this power supply device, when the temperature of the capacitor cell 3 rises and the internal resistance of the capacitor cell 3 increases (deteriorates), the capacitor Since both the discharge current and the charging current of the cell 3 are reduced, the temperature rise of the capacitor cell 3 can be suppressed. Further, since both the discharge current and the charge current of the capacitor cell 3 are reduced, the deterioration of the capacitor cell 3 (increase in internal resistance value) can be suppressed.

(Second control method)
A second control method by the power supply apparatus will be described with reference to FIGS.

  The second control method is a method in which, in the first control method, the voltage of the capacitor cell 3 is further monitored (measured), and each switching element is controlled when the voltage shows an abnormal value.

  As shown in FIG. 4, when there is no deterioration of the capacitor cell 3 (S3 → N), the voltage of the capacitor cell 3 is set to a preset first voltage threshold value (lower limit of voltage determined to be abnormal). Compare (step S8).

  When the voltage of the capacitor cell 3 is lower than the first voltage threshold (S8 → N), each switching element is normally operated while being turned on (step S9).

  When the voltage of the capacitor cell 3 is equal to or higher than the first voltage threshold (S8 → Y), as shown in FIG. 5, the charge cutoff switching element 9 and the charge cutoff switching element 11 are turned OFF while the discharge cutoff switching element 5 remains ON. (Step S10, second control mode).

  In the second control mode, the current path in the discharge direction from the capacitor cell 3 passes through the discharge cutoff switching element 5 and is shunted to the body diode 8 on the charge cutoff switching element 9 side and the charge / discharge limiting switching element 11 side. After passing through, they merge and head toward the motor 100.

  When the circuit configuration of the power supply device 10 when charging the capacitor 100 from the capacitor 2 in the second control mode is viewed from the secondary battery 1 side, the order of the body diode 8 of the charge / discharge limiting switching element 11 as well as the charge cutoff switching element 9 is as follows. Since each directional voltage is generated as a voltage drop, the circuit when the capacitor 2 is discharged is equivalent to an increase in the equivalent series resistance (ESR) of the capacitor 2 compared to that in the first control mode. Therefore, the discharge current of the capacitor cell 3 is further reduced than in the first control mode.

  In the charging mode, that is, the current path in the charging direction from the alternator 100 to the capacitor 2, the MOSFET 7 of the charge cutoff switching element 9 and the charge / discharge limiting switching element 11 is OFF, and the body diode 8 of both switching elements 9, 11 is in the charging current direction. Since it is the opposite direction, it is blocked.

In a state in which the charge cutoff switching element 9 and the charge / discharge limiting switching element 11 are turned off, the discharge current of the capacitor cell 3 becomes small and the charging current does not flow, so the voltage of the capacitor cell 3 gradually decreases. The voltage of the capacitor cell 3 is monitored by the discrimination control means 15, and the charge cut-off switching element 9 and the charge / discharge limiting switching element 11 are kept OFF until the voltage of the capacitor cell 3 becomes lower than a preset second voltage threshold. (Step S11 → Y)
When the temperature of the capacitor cell 3 becomes lower than the second voltage threshold (S11 → N), the charge cutoff switching element 9 and the charge / discharge limiting switching element 11 are turned on, and normal operation is started (step S12). The second voltage threshold value is set lower than the first voltage threshold value so that the response of the switching elements 9 and 11 has hysteresis.

Although overcurrent flows more easily at high voltage than at low voltage, the configuration using the second control method allows the temperature of the capacitor cell 3 to be higher than the configuration using the first control method. Deterioration due to the rise and current can be suppressed, and the cell voltage of the capacitor 2 gradually decreases. Therefore, protection to the cell withstand voltage at high voltage and progression of deterioration of the capacitor 2 due to high temperature can be suppressed.
(Third control method)
A third control method by the power supply apparatus will be described based on the flowchart of FIG.

  In addition to the second control method, the third control method includes a step of controlling the switching elements 5, 9, and 11 when the capacitor cell 3 exhibits a voltage (overvoltage) higher than the first voltage threshold. Have. That is, the method includes a step of discriminating the capacitor cell 3 to which the overvoltage is applied and quickly reducing the voltage of the capacitor cell 3.

  Specifically, as shown in FIG. 6, when there is no deterioration of the capacitor cell 3 (S3 → N), the voltage of the capacitor cell 3 is set to a first preset value higher than the first voltage threshold value. Is compared with the overvoltage threshold value (step S13).

  When the voltage of the capacitor cell 3 is lower than the first overvoltage threshold (S13 → N), the voltage of the capacitor cell 3 is compared with the first voltage threshold (step S8), and the steps described in the second control method are performed. Then, the normal operation state is entered (step S9 or steps S10 and S11).

  When the voltage of the capacitor cell 3 is equal to or higher than the first overvoltage threshold (S13 → Y), the balance switch element connected to the capacitor cell 3 indicating the overvoltage is turned on (step S14, third control mode). .

  Since the charge cutoff switching element 9 and the charge / discharge limiting switching element 11 are OFF and the balance switch element 13 is ON, the capacitor cell 3 is not charged and is always discharged from the capacitor cell 3.

  However, in steps S13 and S14, the voltage of the capacitor 2 (total voltage of the capacitor cell 3) is measured, and the voltage is set to be equal to or higher than the first overvoltage threshold value of the capacitor 2 (separately from the overvoltage threshold value of the capacitor cell 3). For example, in the case of the sum of the first overvoltage thresholds of the capacitor cells), all the balance switch elements 13 are turned ON. When all the balance switch elements 13 are ON, all the capacitor cells 3 are always discharged.

  The voltage of the capacitor cell 3 (or the total voltage of the capacitor) is monitored by the discrimination control means 15 and is lower than the preset second overvoltage threshold, which is lower than the first overvoltage threshold, until the charge cutoff switching element 9 is reached. Then, the charge / discharge limiting switching element 11 is turned off and the balance switch element is kept on (step S15 → Y).

  When the voltage of the capacitor cell 3 becomes lower than the second overvoltage threshold (S15 → N), the charge cut-off switching element 9 and the charge / discharge limiting switching element 11 are turned on, and the balance switch element 13 is turned off for normal operation. Is started (step S16).

  The OFF condition (second overvoltage threshold) of the balance switch element 13 is set to be lower than the first voltage threshold, but is set to a smaller value with hysteresis to prevent chattering due to switching of the balance switch element 13. It may be a value.

  By adopting the configuration using the third control method, the voltage of the capacitor cell 3 can be lowered more quickly than in the configuration using the second control method, so that a failure due to an overvoltage of the capacitor cell 3 can be prevented. Since the deterioration state of the capacitor cell 3 due to the high voltage and high temperature can be quickly eliminated, it is effective in extending the life of the capacitor 2.

  As mentioned above, according to the power supply device of this embodiment, the heat_generation | fever and deterioration of the capacitor 2 which arise at the time of discharge and charge of the capacitor 2 can be suppressed. Even when the capacitor 2 is in an abnormal state (heat generation or deterioration state), the discharge voltage from the capacitor 2 is not reduced to 0, so that it is possible to always ensure power to the secondary battery 1. Since the abnormality of the capacitor 2 can be prevented (recovered from the abnormality), the capacity of the secondary battery 1 can be reduced, and the secondary battery 1 can be downsized. In addition, since the burden on the secondary battery 1 is reduced, damage due to an increase in the discharge current of the secondary battery 1 can be suppressed, which is effective in extending the life of the secondary battery 1.

  The present invention is not limited to the above-described embodiment, and various other types are assumed.

  N-channel MOSFETs are used as the MOSFETs 7 constituting the switching elements 5, 9, 11, and 13, and the resistance is low. However, P-channel MOSFETs are used for at least one of the switching elements 5, 9, 11, and 13. May be.

  Although the discrimination control means 15 is configured using a general-purpose microcomputer, it may be configured using a dedicated IC. The current detection means 23 measures the voltage across the switching elements 5 and 9 using a differential amplifier. In addition, the current detection means 23 is based on detection by a Hall element, voltage measurement of a shunt resistor, and voltage measurement of a current transformer. Current detection may be performed, and other devices may be used as long as they have a function capable of detecting the current flowing through the switching elements 5 and 9. Although the PTC thermistor 21 is used as the temperature detecting means 20, a temperature detection may be made using an NTC (Negative Temperature Coefficient) thermistor and a temperature IC. Although the temperature detection location is the surface of the capacitor cell 3, the temperature detection location may be a circuit board connected to the capacitor 2 and a housing that houses the capacitor 2.

  In this embodiment, the current cut-off switching element 5, the charge cut-off switching element 9, and the charge / discharge limiting switching element 11 are provided in the current path 4 of the capacitor 2. However, the switching element that limits the charging current to the capacitor. In addition, as a switching element that performs at least one of limiting and cutting off the charging current to the capacitor, only the charging cutoff switching element 9 may be provided in the current path 4, or the charging cutoff switching element 9 and the charge cutoff switching element 9 may be provided. The charge / discharge limiting switching element 11 and the charge limiting resistor connected in parallel to each other may be provided in the current path 4.

  Next, a power supply device according to a preferred second embodiment will be described.

  The basic components of the power supply device of the present embodiment are substantially the same as those of the power supply device 10 of FIG. 1 described above, except that the capacitor 2 of the previous embodiment is replaced with an electric double layer capacitor (EDLC) and lithium ions are negatively connected. The difference is that the hybrid capacitor (HC) used in is used.

  Here, a difference in discharge characteristics between a general electric double layer capacitor and a hybrid capacitor will be described with reference to FIG.

  FIG. 7 is a graph showing the relationship between the discharge amount and the voltage for each of the electric double layer capacitor and the hybrid capacitor.

  In the electric double layer capacitor (graph 71 in the figure) and the hybrid capacitor (graph 72 in the figure), the voltage decreases as the discharge amount increases. The hybrid capacitor has a higher discharge voltage than the electric double layer capacitor 2. However, the electric double layer capacitor can be discharged until the discharge voltage becomes 0, whereas the hybrid capacitor has a large discharge amount and deteriorates when discharged to a voltage lower than the discharge limit (lower limit voltage), The deterioration is not recoverable.

  The power supply device of this embodiment includes a hybrid capacitor having a discharge voltage higher than that of the electric double layer capacitor, and includes a step for preventing the voltage of the hybrid capacitor from being equal to or lower than the lower limit voltage (overdischarge voltage). It is a configuration.

  The control method of the power supply device of this embodiment is demonstrated based on FIG.

  As shown in FIG. 8, in this power supply device, when the temperature of the capacitor 2 does not exceed the first temperature threshold in the power supply device (third control method) of the previous embodiment described in FIG. 6 (step S1 → N) When the normal operation is started, the voltage of the capacitor cell 3 is measured and compared with a preset overdischarge voltage threshold (step S21).

  When the voltage of the capacitor cell 3 is larger than the overdischarge threshold (S21 → N), each switching element is normally operated while being turned on (step S22).

  When the voltage of the capacitor cell 3 is equal to or lower than the overdischarge threshold (S21 → Y), as shown in FIG. 4, the charge cutoff switching element 9 and the charge / discharge limiting switching element 11 remain ON and only the discharge cutoff switching element 5 is turned on. The mode is turned off (step S23, fourth control mode).

  In the fourth control mode, the discharge path from the capacitor 2 is cut off because the discharge cut-off switching element 5 is OFF and the body diode 8 of the discharge cut-off switching element 5 is in the opposite direction to the discharge current direction. The charging path to the capacitor 2 passes through the charge cutoff switching element 9 and the charge / discharge limiting switching element 11, passes through the body diode of the discharge cutoff switching element 5, and reaches the capacitor 2. In a state in which the discharge cutoff switching element 5 is turned off, the discharge of the capacitor cell 3 is cut off, so that only the charging can be performed without lowering the voltage, so that the voltage gradually increases. The voltage of the capacitor cell 3 is monitored by the discrimination control means 15, and the discharge cutoff switching element 5 is kept OFF until the voltage of the capacitor cell 3 becomes higher than a preset second overdischarge threshold (step S24). → Y).

  When the voltage of the capacitor cell 3 becomes higher than the second overdischarge threshold (S24 → N), the discharge cutoff switching element 5 is turned on and normal operation is started (step S25). The second overdischarge threshold is set higher than the first overdischarge threshold. By setting the second overdischarge threshold value higher than the first overdischarge threshold value indicating the lower limit voltage of the capacitor cell 3, the voltage of the capacitor cell 3 does not immediately reach the abnormal voltage even when normal operation is resumed. It is to make it.

  According to this power supply apparatus, by using the hybrid capacitor 2, a higher discharge output can be obtained than when the electric double layer capacitor 2 is used. However, although the hybrid capacitor 2 can obtain a high discharge output, the hybrid capacitor 2 is severely deteriorated in an overdischarge state. The power supply apparatus can prevent the capacitor cell 3 from being broken due to overdischarge by detecting that the voltage of the capacitor cell 3 has become low and performing control to stop the discharge of the capacitor cell 3. This power supply apparatus can prevent the hybrid capacitor from being overdischarged and can extend the life of the hybrid capacitor.

  Next, a power supply device according to a preferred third embodiment of the present invention will be described.

  As shown in FIG. 10, the basic components of the power supply device 30 of the present embodiment are substantially the same as those of the power supply device 10 of FIG. 1 described above, and the same reference numerals as in FIG. Although another capacitor is connected in parallel with the capacitor 2 of FIG. 1, the same discharge cutoff switching element and charge control switching unit as those of the previous embodiment are connected to the current path of the capacitor 2, and both capacitors are connected. The difference is that the switching elements connected to 2 and 32 are connected to one discrimination control means.

  Specifically, the power supply device 30 includes a first capacitor 2 and a second capacitor 32 respectively connected in parallel to the secondary battery 1.

  The first discharge cutoff switching element 5, the first charge cutoff switching element, the first charge / discharge limiting switching element 11 and the charge limiting resistor 12 are connected to the current path on the + side of the first capacitor 2, The second discharge cut-off switching element 33, the second charge cut-off switching element 34, the second charge / discharge limit switching element 35, and the second charge limit resistor 36 are also provided in the current path on the + side of the second capacitor 32. Similarly connected. A balance switching element, temperature detection means, and current detection means are also provided on both the first capacitor side and the second capacitor 2 side (not shown).

  The discrimination control means 36 is connected to the first switching elements 5, 9, 11 and the second switching elements 33 to 35. Specifically, the discrimination control means 36 includes a first gate driver 37 that drives the switching elements 5, 9, and 11 on the first capacitor 2 side, and switching elements 33 to 35 on the second capacitor 32 side. And a CPU 39 connected to the first and second gate drivers 37 and 38 for controlling the switch. In addition, the discrimination control unit 36 is also connected to a temperature detection unit and a current detection unit (not shown) as in the previous embodiment.

  According to the power supply device 30 of the present embodiment, in addition to the operational effects of the first and second embodiments, even if one capacitor 2 is abnormal or fails, the other capacitor 32 can maintain charge / discharge. Therefore, it is possible to prevent the discharge voltage from the capacitors 2 and 32 from becoming 0, and to ensure the power security to the secondary battery 1. Since the burden on the secondary battery 1 is reduced, the capacity of the secondary battery 1 can be reduced and the size can be reduced. In addition, since the burden on the secondary battery 1 is reduced, damage due to an increase in the discharge current of the secondary battery 1 can be suppressed, which is effective in extending the life of the secondary battery 1.

1 is a circuit diagram illustrating a power supply device according to a preferred first embodiment of the present invention. 2 is a flowchart for explaining a first control method in the power supply device of FIG. 1. FIG. 3 is a circuit diagram during switch control in step S5 of FIG. 2. 4 is a flowchart for explaining a second control method in the power supply device of FIG. 1. It is a circuit diagram at the time of switch control of step S10 of FIG. 6 is a flowchart for explaining a third control method in the power supply device of FIG. 1. It is a graph which shows the discharge characteristic of an electric double layer capacitor and a hybrid capacitor. It is a flowchart for demonstrating the control method in the power supply device of suitable 2nd Embodiment which concerns on this invention. It is a circuit diagram at the time of switch control of step S23 of FIG. It is a circuit diagram which shows the power supply device of suitable 3rd Embodiment based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Capacitor 3 Capacitor cell 5 Discharge interruption | blocking switching element 6 Charge control switching part 7 MOSFET
DESCRIPTION OF SYMBOLS 8 Body diode 9 Charge interruption | blocking switching element 10 Power supply device 11 Charging / discharging restriction | limiting switching element 12 Charge limiting resistance 13 Balance switch element 15 Discrimination control means (microcomputer)
20 Temperature detection means 30 Power supply device 32 Second capacitor

Claims (12)

In a power supply device comprising a secondary battery and a capacitor connected in parallel to the secondary battery,
Detecting means for detecting the temperature of the capacitor and the voltage of the capacitor;
A switching element for cutting off a discharge current from the capacitor based on a detection value of the detection means;
A switching element unit that performs at least one of limiting and cutting off the charging current to the capacitor based on the detection value of the detection unit;
The switching element unit that performs at least one of limiting and blocking the charging current,
A first switching element comprising: a MOSFET connected to the current path of the capacitor; and a diode connected in parallel to the MOSFET and in a direction opposite to the charging current direction of the capacitor;
Said first MOSFET connected in parallel with the switching element, a second switching element comprising a diode connected in parallel and charge current direction opposite to the capacitor to the MOSFET,
A charge limiting resistor connected in series to the second switching element,
A power supply apparatus configured to turn off the first switching element when an internal resistance of the capacitor and a temperature detected by the detection unit are higher than a preset threshold value. The power supply device according to claim 1 , wherein
When the temperature of the capacitor detected by the detection means is higher than a preset temperature threshold and the voltage of the capacitor detected by the detection means is higher than a preset voltage threshold, the first A power supply apparatus configured to turn off both the switching element and the second switching element. The power supply device according to claim 1 or 2 ,
The capacitor is composed of one or a plurality of capacitor cells connected in series with each other, and the detection means is a power supply device connected to each capacitor cell so that the voltage of any capacitor cell can be detected. The power supply device according to claim 3 , wherein
A balance switch element and a resistor connected in series with each other are connected in parallel to each capacitor cell, and the balance switch element is a MOSFET and a diode connected in parallel to the MOSFET and in the opposite direction to the discharge current direction to the capacitor. A power supply unit consisting of The power supply device according to claim 4 ,
When the temperature of at least one capacitor cell exceeds a preset temperature threshold and the voltage of the capacitor cell exceeds an overvoltage threshold set higher than a preset voltage threshold, the balance switch element is A power supply configured to be turned on. The power supply device according to any one of claims 1 to 5 ,
The switching element that cuts off the discharge current is a third switching element that includes a MOSFET connected to the current path of the capacitor and a diode connected in parallel to the MOSFET and in a direction opposite to the discharge current direction of the capacitor. Configured power supply. The power supply device according to any one of claims 1 to 6 ,
The power supply device, wherein the capacitor is an electric double layer capacitor. The power supply device according to any one of claims 1 to 7 ,
The said capacitor is a power supply device which is a hybrid capacitor which used lithium ion for the negative electrode. The power supply device according to claim 8 , wherein
A power supply apparatus in which a third switching element comprising a MOSFET and a diode connected in parallel to the MOSFET and in a direction opposite to the discharge current direction to the capacitor is connected to the current path of the capacitor. The power supply device according to claim 9 , wherein
A power supply apparatus configured to turn off the third switching element when an overdischarge voltage threshold of the hybrid capacitor is set and a discharge voltage of the hybrid capacitor becomes lower than the overdischarge voltage threshold. The power supply device according to any one of claims 1 to 10 ,
Another capacitor connected in parallel with the capacitor, another detection means for detecting a temperature of the another capacitor and a voltage of the other capacitor, and the other capacitor based on a detection value of the another detection means Another switching element that limits the discharge current from the other capacitor, and another switching element that performs at least one of limiting and cutting off the charging current to the other capacitor based on the detection value of the other detection means. A power supply device characterized by that. A vehicle power supply device in which a motor and an alternator are connected to the power supply device according to any one of claims 1 to 11 .

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