JP2011036046A - Power supply backup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain reliability in a power supply backup device having an electric double-layer capacitor. <P>SOLUTION: In the power supply backup device, DC power is supplied from a DC power supply to a load circuit 2 via a first diode D1; boosting is performed by a boosting circuit 5 and the electric double-layer capacitor C1 is charged; and charging voltage of the electric double layer capacitor C1 is supplied to the load circuit 2 via a switching circuit 4 and a second diode D2, when the DC power supply is abnormal. The device is provided with a voltage/current detecting circuit 7 for detecting a charging voltage and a discharging current; a voltage detecting circuit 8 detecting the voltage supplied to the load circuit 2 via the first and second diodes D1 and D2 and a control processing circuit 1 for detecting DC current and DC voltage from the electric double-layer capacitor C1 by the voltage/current detecting circuit 7, by turning on the switching circuit 4; calculating capacitance and internal resistance of the electric double-layer capacitor C1 and determining the presence or the absence of abnormality state of the electric double-layer capacitor C1, based on the capacitance and the internal resistance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply backup device that charges a large-capacity capacitor from a DC power supply for supplying DC operating power to a load circuit, and supplies the operating power from the large-capacitance capacitor to the DC load when a failure occurs in the DC power supply.

  Various configurations have already been proposed and put into practical use for DC power supplies that supply operating power for various DC load circuits such as electronic circuits. Such a DC power source has a configuration in which, for example, an AC voltage from a commercial AC power source is converted to a desired voltage by a transformer or the like and rectified, and converted to an operating voltage of a DC load circuit by switching control or the like. Relatively many applications have been applied. In this case, there may be a case where the operating power cannot be continuously supplied to the DC load circuit due to a failure on the commercial AC power supply side or the DC power supply side. Therefore, various configurations have been proposed in which a power backup device is provided to continuously supply operating power to a DC load circuit even when a failure occurs. In the case of a configuration in which the DC load circuit consumes a relatively large amount of power, a configuration using an engine-driven generator or a large-capacity battery is generally used as a power backup device. The configuration is common. In addition, a configuration using a kind of electric double layer capacitor as a large-capacitance capacitor is known as a backup for a DC power supply that supplies operating power to various electronic circuits.

  This electric double layer capacitor is a large-capacity capacitor that can store electric charge by forming an electric double layer capacitor on both the positive and negative electrodes, and supply the accumulated charge to the load as DC power, and has low internal resistance. In addition, charging / discharging is possible in a short time, and the number of usable charging / discharging cycles is about 100,000 to 1,000,000 times. Various configurations have been proposed in which an electric double layer capacitor having such characteristics is provided on the DC power supply side so that DC voltage supply can be continued. For example, the output voltage of the AC / DC converter is supplied to the DC load via the output switch, and the on / off control of the output switch and the start / stop of the operation of the AC / DC converter are controlled. The operating power of the off-control circuit is supplied from the electric double layer capacitor charged with the output voltage of the AC / DC converter, and when the output switch is turned off and the AC / DC converter is in the sleep state, the electric double layer capacitor When the charging voltage drops, this voltage drop is detected by the on / off control circuit, the AC / DC converter is temporarily operated, the electric double layer capacitor is charged, and the backup by this electric double layer capacitor can be continued. The structure which performs is proposed (for example, refer patent document 1).

  Also, the AC voltage from the commercial AC power supply is rectified to supply the DC operating power to the DC load circuit including the electronic circuit, etc., and the electric double layer capacitor of the DC power supply backup device is charged so that the commercial AC power supply fails. In some cases, a configuration has also been proposed in which operating power necessary for executing the minimum stable operation stop processing of a DC load circuit including an electronic circuit or the like is performed from an electric double layer capacitor of a DC power supply backup device (for example, , See Patent Document 2). In addition, an electric double layer capacitor is connected in parallel with the DC power supply, and the charging voltage of the electric double layer capacitor is supplied to the DC load circuit as a backup when the output voltage of the DC power supply is lowered. Based on the characteristic that the internal resistance of the capacitor decreases with increasing temperature, a means to improve the discharge characteristics of the electric double layer capacitor by connecting the electric double layer capacitor and the reactor that constitutes the resonance circuit to flow the resonance current is proposed. (For example, refer to Patent Document 3).

  In addition, it is necessary to always apply DC voltage to electronic circuits such as calendar clocks (real-time clocks) installed with various devices. For this reason, in the configuration using the charging voltage of the electric double layer capacitor, When supplying DC voltage for the operation of the main body of various devices, it charges the electric double layer capacitor on the power supply side and supplies it as the operating voltage of the calendar clock, and when the DC voltage supply is stopped, the charging voltage of the electric double layer capacitor on the power supply side Therefore, a configuration is proposed in which a circuit configuration for charging an electric double layer capacitor on the calendar watch side is provided, and a charging voltage of the electric double layer capacitor on the calendar watch side is supplied as an operating voltage of the calendar watch (for example, a patent) Reference 4).

JP 2006-254655 A JP 2006-341555 A JP 2007-288986 A JP 2009-81904 A

  As described above, in the power backup device that charges the electric double layer capacitor from the DC power supply side and supplies the charging voltage of the electric double layer capacitor to the DC load circuit when the DC voltage supply from the DC power supply is stopped. The characteristics of the electric double layer capacitor may be deteriorated mainly due to deterioration with time, and the desired backup characteristics may not be maintained. It is necessary to determine whether such characteristics of the electric double layer capacitor have deteriorated, and when the characteristic deteriorates, it is necessary to replace the electric double layer capacitor in use with a new electric double layer capacitor and maintain the backup characteristic at the desired characteristic. It is.

  For this purpose, for example, a characteristic test configuration of the power backup device shown in FIG. 6 has been proposed. In the figure, D1 and D2 are backflow blocking diodes, C1 is an electric double layer capacitor, 31 is a calculation circuit, 32 is a DC load circuit such as an electronic circuit, 33 is a constant voltage circuit, 34 is a switch circuit, Reference numeral 35 denotes a booster circuit, 36 denotes a switch circuit, 37 denotes a voltage detection circuit, 38 denotes a pseudo load circuit, and 39 denotes a timer. The load circuit 32 is generally a variety of electronic circuits and operates at a relatively low voltage. The constant voltage circuit 33 is for supplying a constant operating voltage to the load circuit 32. The DC power input indicates, for example, an input DC voltage obtained by converting an AC voltage from a commercial AC power source into a desired voltage and rectified, and the power interruption information is a power failure detection information of the commercial AC power source. The switch circuit 34 that is normally off is turned on according to the power-off information, the charge of the electric double layer capacitor C1 is input to the constant voltage circuit 33, and the operating voltage for the load circuit 32 is continued. Supply. Although the electric double layer capacitor C1 is illustrated as a single capacitor, since the withstand voltage characteristic is as low as several volts, a configuration in which a plurality of capacitors are connected in series is generally common. In order to supply a backup current corresponding to the current capacity of the load circuit 32, it is also common to have a configuration in which a plurality of them are connected in parallel. The booster circuit 35 boosts the DC voltage of the DC power supply input in the normal state to charge the electric double layer capacitor C1. The diodes D1 and D2 charge the electric double layer capacitor C1 to the DC power supply side so that the DC power input is not directly applied to the electric double layer capacitor C1 and the switch circuit 34 is turned on. This is to prevent it from happening.

  The timer 39 is for supplying time information to the calculation circuit 31. For example, the timer 39 is for supplying time information for periodically conducting a characteristic test of the electric double layer capacitor C1 and time information during the characteristic test. At the time of a characteristic test at a preset time interval, the switch circuit 36 is turned on under the control of the calculation circuit 31, and the pseudo load circuit 38 is connected to the electric double layer capacitor C1. As a result, the charge charge is supplied from the electric double layer capacitor C1 to the pseudo load circuit 38. The voltage detection circuit 37 detects the terminal voltage of the electric double layer capacitor C1 and inputs it to the calculation circuit 31. The calculation circuit 31 determines whether or not the characteristic is in a deteriorated state based on the change characteristic of the voltage of the electric double layer capacitor C1 over time from the start of the test. When the voltage drop from the start of the test to the end of the test is equal to or less than a predetermined value, it can be determined that the characteristic is deteriorated. Alternatively, it can be determined whether or not the characteristics are deteriorated according to the difference between the standard discharge characteristics of the electric double layer capacitor C1 and the difference.

  However, as a test of the power backup device using the electric double layer capacitor C1, the pseudo load circuit 38 is connected to the electric double layer capacitor C1 and discharged, and the characteristics of the pseudo load circuit 38 are expressed by the constant voltage circuit 33. Therefore, there is a problem that it is difficult to match the characteristics of the load circuit 32 including the normality of the power supply backup circuit including the normality of the diode D2. Therefore, a test configuration of the power backup device shown in FIG. 7 has been proposed. In the figure, D1 and D2 are backflow prevention diodes, C1 is an electric double layer capacitor, 41 is a calculation circuit, 42 is a load circuit, 43 is a constant voltage circuit, 44 is a switch circuit, 45 is a boost circuit, 46 Indicates a current limiting circuit, 47 indicates a voltage detection circuit, 48 indicates a voltage detection circuit, and 49 indicates a timer.

  The switch circuit 44 is always on, and is controlled to be off during the characteristic test by the calculation circuit 41. The current limiting circuit 46 is for limiting the charging current in the case of initial charging of the electric double layer capacitor C1 so that it does not become an excessive value. The booster circuit 45 is for boosting and inputting the voltage to the constant voltage circuit 43 because the charging voltage of the electric double layer capacitor C1 is approximately equal to or less than the voltage of the DC power supply input. The calculation circuit 41 periodically performs a characteristic test based on time information from the timer 49. During the characteristic test, the switch circuit 44 is turned off, and the terminal voltage of the electric double layer capacitor C1 is detected by the voltage detection circuit 47. The electric double layer capacitor C1 is based on the value and the value detected by the voltage detection circuit 48 when the voltage of the terminal voltage of the electric double layer capacitor C1 is input to the constant voltage circuit 43 via the booster circuit 45 and the diode D2. Regularly test C1 backup function. In this case, the test including the normality of the diode D2 can be performed.

  However, before determining whether or not the electric double layer capacitor C1 is normal, the normal DC power input is turned off by the switch circuit 44, the terminal voltage due to the charge of the electric double layer capacitor C1 is boosted by the boost circuit 45, Since the voltage is input to the constant voltage circuit 43 via the diode D2, there is a problem that the operating voltage cannot be supplied to the load circuit 42 when the characteristics of the electric double layer capacitor C1 deteriorate.

  The present invention aims to solve the above-mentioned conventional problems, and determines whether or not the characteristics are deteriorated based on parameters such as capacitance and internal resistance of the electric double layer capacitor, and normal power backup is possible. Whether it is possible or not can also be determined, and the reliability of the power backup device using the electric double layer capacitor can be maintained.

  The power backup device of the present invention supplies DC power from a DC power supply to a load circuit via a first diode, and boosts the DC power supply by boosting from the DC power supply by a booster circuit. A power backup device for supplying a charging voltage of the electric double layer capacitor to the load circuit via a switch circuit and a second diode when an abnormality occurs, wherein the charging voltage and discharging current of the electric double layer capacitor are A voltage / current detection circuit for detection, a voltage detection circuit for detecting a voltage supplied to the load circuit via the first and second diodes, and a preset period based on time information from a timer The switch circuit is turned on, and the charging voltage of the electric double layer capacitor is supplied to the load circuit via the second diode, A DC current and a DC voltage supplied from the electric double layer capacitor are detected by a current detection circuit to calculate the capacitance and internal resistance of the electric double layer capacitor, and the calculated capacitance and internal resistance And a control processing circuit for determining whether or not there is an abnormality in the electric double layer capacitor.

  In addition, a temperature sensor that detects the ambient temperature of the electric double layer capacitor is provided, and the control processing circuit corrects the calculated values of the capacitance and internal resistance of the electric double layer capacitor based on the temperature detected by the temperature sensor. It has. In addition, the control processing circuit controls the switch circuit to turn on and discharges the charging voltage of the electric double layer capacitor to the load circuit, and controls the switch circuit to turn off and boosts the electric double layer capacitor by the boost circuit. It is possible to provide a function of performing a charge test for charging with a DC voltage for each preset period according to time information from a timer. The control processing circuit includes a memory for calculating and storing the capacitance and the internal resistance of the electric double layer capacitor for each preset period based on the time information from the timer, and stored in this memory. A function is provided for estimating the remaining usable period of the electric double layer capacitor based on the changing tendency of the capacitance and internal resistance of the electric double layer capacitor.

  A power backup device equipped with an electric double layer capacitor detects the voltage and current of the electric double layer capacitor to determine the capacitance and internal resistance of the electric double layer capacitor, and changes between the capacitance and internal resistance Based on the tendency, the remaining usable period can be estimated, and the reliability of the power backup device can be improved.

It is explanatory drawing of Example 1 of this invention. It is charging / discharging characteristic explanatory drawing of the electric double layer capacitor of Example 1 of this invention. It is characteristic explanatory drawing of the electrostatic capacitance and internal resistance of an electric double layer capacitor. It is explanatory drawing of the remaining life determination process of Example 1 of this invention. It is explanatory drawing of Example 2 of this invention. It is explanatory drawing of a prior art example. It is explanatory drawing of a prior art example.

  Referring to FIG. 1, the power supply backup device of the present invention supplies DC power from a DC power supply to the load circuit 2 via the first diode D1 or via the constant voltage circuit 3, and from the DC power supply to the booster circuit. 5 to charge the electric double layer capacitor C1 and supply the charging voltage of the electric double layer capacitor C1 to the load circuit 2 via the switch circuit 4 and the second diode D2 when an abnormality occurs in the DC power supply. A power supply backup device that supplies a voltage / current detection circuit 7 for detecting a charging voltage and a discharging current of the electric double layer capacitor C1 and a voltage supplied to the load circuit 2 via the first and second diodes D1 and D2. Based on the voltage detection circuit 8 to be detected and the time information from the timer 9, the switch circuit 4 is controlled to be turned on for each preset period to charge the electric double layer capacitor C1. The voltage is supplied to the load circuit 2 through the second diode D2, and the DC / DC voltage supplied from the electric double layer capacitor C1 is detected by the voltage / current detection circuit 7 to detect the static voltage of the electric double layer capacitor C1. A control processing circuit 1 is provided that calculates electric capacity and internal resistance, and determines whether or not the electric double layer capacitor C1 is abnormal based on the calculated electrostatic capacity and internal resistance.

  FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention, where 1 is a control processing circuit, 2 is a load circuit such as an electronic circuit, 3 is a constant voltage circuit, 4 is a switch circuit, 5 is a booster circuit, and 6 is a current. A detection circuit, 7 is a voltage / current detection circuit, 8 is a voltage detection circuit, 9 is a timer, 10 is a temperature sensor, C1 is an electric double layer capacitor, and D1 and D2 are first and second diodes. When the DC voltage indicated as the DC power supply input is normal, the switch circuit 4 is controlled to be in the OFF state, and the DC voltage is input to the constant voltage circuit 3 via the first diode D1, and the load circuit 2 has a predetermined constant voltage. A DC voltage controlled to a voltage is supplied and boosted by the booster circuit 5 to charge the electric double layer capacitor C1. When the DC power input is cut off, the switch circuit 4 is turned on according to the power cut-off information, and the voltage charged in the electric double layer capacitor C1 is input to the constant voltage circuit 3 via the second diode D2, thereby A predetermined DC voltage is continuously supplied to the circuit 2 to function as a power backup device. The constant voltage circuit 3 controls the DC voltage supplied to the load circuit 2 to a constant value. If the load circuit 2 has a configuration capable of continuing operation even when the applied voltage changes, this constant voltage circuit 3 The constant voltage circuit 3 can be omitted.

  The control processing circuit 1 can be configured by a processor including a memory, and charges the electric double layer capacitor C1 with the temperature detection value of the electric double layer capacitor C1 by the temperature sensor 10 and the voltage boosted by the booster circuit 5. Charge current detection value detected by the current detection circuit 6, detection value of the terminal voltage and discharge current of the electric double layer capacitor C1 detected by the voltage / current detection circuit 7 when the switch circuit 4 is turned on, voltage detection The input voltage detection values to the constant voltage circuit 3 are input by the circuit 8 via the diode D2. Also, time information by the timer 9 is input. Based on the time information from the timer 9, the control processing circuit 1 tests the power supply backup device including the electric double layer capacitor C1 at a preset time interval. When testing this power backup device, the switch circuit 4 is turned on, and the charging voltage of the electric double layer capacitor C1 is input to the constant voltage circuit 3 via the diode D2. At this time, the terminal voltage of the electric double layer capacitor C1 is boosted and charged by the booster circuit 5, and therefore is higher than the DC input voltage. Therefore, the constant voltage circuit 3 from the electric double layer capacitor C1 through the diode D2 is used. The charging power of the electric double layer capacitor C1 is supplied at a constant voltage to the load circuit 2. At this time, the control processing circuit 1 determines that the voltage detection value input to the constant voltage circuit 3 via the diode D2 by the voltage detection circuit 8 is the voltage detection value by the voltage / current detection circuit 7 and the forward voltage of the diode D2. If the voltage difference corresponds to the drop, it can be determined that the backup by the electric double layer capacitor C1 when the power is cut off is normally performed.

  Further, as described above, the control processing circuit 1 performs a test at a predetermined time interval according to the time information from the timer 9, and the voltage drop of the electric double layer capacitor C1 due to the start of the test with the switch circuit 4 turned on. Based on Vd, that is, the voltage difference before and after the switch circuit 4 is turned on by the terminal voltage of the electric double layer capacitor C1 by the voltage / current detection circuit 7 and the current Ic supplied to the load circuit 2 side, the electric double layer The internal resistance R of the capacitor C1 is obtained by R = Vd / Ic. The capacitance of the electric double layer capacitor C1 is based on a certain time Δt after the start of the test, a voltage change ΔVt of the electric double layer capacitor C1 before and after the time Δt, and a current Ic from the electric double layer capacitor C1. Can be obtained by C = Ic · Δt / ΔVt. The control processing circuit 1 stores the discharge current of the electric double layer capacitor C1, the terminal voltage, the temperature by the temperature sensor 10, the calculated internal resistance R, the capacitance C, and the like in an internal memory for each periodic test. The characteristic change of the double layer capacitor C1 is monitored. In addition, the test processing time is set to a time sufficiently short compared with the continuation time that can be backed up by the electric double layer capacitor C1, and the control processing circuit 1 starts from the timer 1 so as not to adversely affect the actual backup due to power interruption. Control test duration based on time information.

  In addition, although the test of the power supply backup function by the control processing circuit 1 is performed based on the discharge characteristics of the electric double layer capacitor C1, it can also be performed based on the charge characteristics of the electric double layer capacitor C1. It is. FIG. 2 is an explanatory diagram of the charge / discharge characteristics of the electric double layer capacitor C1 shown in FIG. 1, and the output voltage is the voltage output to the load circuit 2 side via the diode D2, that is, the voltage detected by the voltage detection circuit 8. The capacitor voltage indicates a terminal voltage of the electric double layer capacitor C1, that is, a voltage detected by the voltage / current detection circuit 7. When the test is started with the switch circuit 4 turned on, the electric double layer capacitor C1 is charged with a voltage higher than the input voltage by the booster circuit 5, and therefore the output voltage becomes higher by the voltage boosted by the booster circuit 5. The terminal voltage of the electric double layer capacitor C1 is a charging voltage boosted by the booster circuit 5. When the discharge test is started with the switch circuit 4 turned on, the terminal voltage of the electric double layer capacitor C1 is Vd. As the discharge test continues, the terminal voltage gradually decreases. Further, after the discharge test, the charging test is performed, that is, the switch circuit 4 is turned off, and the electric double layer capacitor C1 is charged with the voltage boosted by the booster circuit 5 to gradually increase. A change in the terminal voltage of the electric double layer capacitor C1 during the charging test is detected by the voltage / current detection circuit 7, the charging current is detected by the current detection circuit 6, and the internal resistance R is determined by the control processing circuit 1. As described above, R = Vd / Ic, and the capacitance C can be similarly obtained as C = Ic · Δt / Δv.

  FIG. 3 is an explanatory diagram of the characteristics of the capacitance and internal resistance of the electric double layer capacitor. (A) The capacitance indicates a change in the capacitance with respect to temperature, and (b) the internal resistance indicates the resistance with respect to temperature. Indicates the rate of change. Capacitance has a tendency to decrease with decreasing temperature, and internal resistance has a tendency to increase rapidly with decreasing temperature. Accordingly, the temperature of the electric double layer capacitor C1 is measured by the temperature sensor 10 shown in FIG. 1, and the control processing unit 1 determines the reference temperature with respect to the measured values of the internal resistance and the capacitance based on the measured temperature information. Characteristic judgment can be made in terms of.

  When the current of the load circuit 2 is supplied through the diode D1 and when the current is supplied through the diode D2, the voltage / current detection circuit 7 It is also possible to adopt a configuration having only a voltage detection function. The control processing circuit 1 determines whether the backup function including the electric double layer capacitor C1 is good or not according to the time information from the timer 9 every hour, every month, and so on. Therefore, it is possible to predict the remaining usable period. For example, as shown in FIG. 4, by setting the threshold value with the horizontal axis as time, the vertical axis as the above-described capacitance, internal resistance, and the like, the past characteristic change and the current characteristic can be obtained. The remaining period indicated as the life can be estimated, and when the remaining time is equal to or less than a predetermined value, an alarm can be sent to notify the maintenance manager.

  FIG. 5 is an explanatory diagram of a second embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same parts, 1a is an arithmetic circuit, 1b is an A / D converter, 1c is a memory, and 7a is voltage detection. Circuit, 7b is a current detection circuit, 11 is a power supply circuit, 12 is an AC / DC conversion circuit, 13 is a disconnection detection circuit, 14 is an abnormality occurrence notification terminal, 15 is a status information notification terminal, and AC is a 100V or 200V commercial AC power supply Indicates. Further, as the electric double layer capacitor C1, a configuration in which a plurality of single electric double layer capacitors are connected in series and connected in parallel is shown. The power supply circuit 11 converts AC 100V or 200V into a DC voltage corresponding to the operating voltage of the load circuit 2 by the AC / DC conversion circuit 12, and supplies the DC voltage to the constant voltage circuit 3 via the first diode D1. The constant voltage circuit 3 stabilizes and supplies the operating voltage of the load circuit 2. Further, the electric double layer capacitor C1 is charged by being boosted by the booster circuit 5, and the charging current is detected by the current detection circuit 6 and input to the control processing circuit 1. Further, the disconnection detection circuit 13 of the power supply circuit 11 turns on the switch circuit 4 when a power failure of the commercial AC power supply AC is detected, and supplies the charge of the electric double layer capacitor C1 to the constant voltage circuit 3 via the second diode D2. Then, the stabilized DC voltage is continuously supplied to the load circuit 2.

  The control processing circuit 1 converts input signals from the current detection circuit 6, the voltage detection circuit 7a, the current detection circuits 7b and 8 and the temperature sensor 10 into digital signals by the A / D converter 1b, Input to the arithmetic circuit 1a. The arithmetic circuit 1a has an arithmetic function and a control function such as a processor. The arithmetic circuit 1a inputs time information from the timer 9, boosts the booster circuit 5 at a predetermined time interval, and charges the electric double layer capacitor C1. The charging current is detected by the current detection circuit 6, the charging voltage is detected by the voltage detection circuit 7a, and each is input to the control processing circuit 1 to monitor the charging characteristics of the electric double layer capacitor C1. When a backup function test set in advance is performed, the switch circuit 4 is turned on. The terminal voltage of the electric double layer capacitor C1 at that time is detected by the voltage detection circuit 7a, the current supplied to the load circuit 2 side is detected by the current detection circuit 7b, and the voltage input to the constant voltage circuit 3 via the diode D2 is detected. The voltage detection circuit 8 detects the temperature, the temperature sensor 10 detects the temperature, and each detection signal is input to the arithmetic circuit 1a via the A / D converter 1b, and the internal resistance of the electric double layer capacitor C1 is reduced. An electric capacity measurement calculation is performed, and data of the calculation result is stored in the memory 1c. In addition, referring to past measurement data held in the memory 1c, a determination process for the remaining usable period of the electric double layer capacitor C1 is performed. If normal, the measurement calculation result information is transmitted from the status information notification terminal 15 to the maintenance manager's device via a network or the like. When the remaining usable period of the electric double layer capacitor C1 is small, or the voltage detection value by the voltage detection circuit 8 is compared with the voltage detection value by the voltage detection circuit 7a, compared with the forward voltage drop of the diode D2. If the abnormal state is determined to be abnormally low, emergency state information is transmitted from the abnormality occurrence notification terminal 14 to the alarm device or the like. Information from the abnormality occurrence notification terminal 14 and the state information notification terminal 15 can be obtained by various known communication means.

DESCRIPTION OF SYMBOLS 1 Control processing circuit 2 Load circuit 3 Constant voltage circuit 4 Switch circuit 5 Booster circuit 6 Current detection circuit 7 Voltage / current detection circuit 8 Voltage detection circuit 9 Timer 10 Temperature sensor C1 Electric double layer capacitor D1, D2 First, second diode

Claims (4)

DC power is supplied from the DC power source to the load circuit via the first diode, and the electric double layer capacitor is charged by boosting from the DC power source by a booster circuit. When an abnormality occurs in the DC power source, the electric double layer In a power backup device for supplying a charging voltage of a capacitor to the load circuit via a switch circuit and a second diode,
A voltage / current detection circuit for detecting a charging voltage and a discharging current of the electric double layer capacitor;
A voltage detection circuit for detecting a voltage supplied to the load circuit via the first and second diodes;
Based on the time information from the timer, the switch circuit is controlled to be turned on every preset period, the charging voltage of the electric double layer capacitor is supplied to the load circuit via the second diode, A DC current and a DC voltage supplied from the electric double layer capacitor are detected by a voltage / current detection circuit, and an electrostatic capacity and an internal resistance of the electric double layer capacitor are calculated. And a control processing circuit for determining whether or not the electric double layer capacitor is abnormal based on a resistance.   A temperature sensor for detecting the ambient temperature of the electric double layer capacitor is provided, and the control processing circuit corrects the calculated values of the capacitance and internal resistance of the electric double layer capacitor based on the temperature detected by the temperature sensor. 2. The power backup apparatus according to claim 1, further comprising a function.   The control processing circuit controls the switch circuit to turn on and discharges the charge voltage of the electric double layer capacitor to the load circuit, and controls the switch circuit to turn off the electric double layer capacitor. 2. The power backup apparatus according to claim 1, further comprising a function of performing a charge test for charging with a DC voltage boosted by the booster circuit for each preset period in accordance with time information from the timer. .   The control processing circuit includes a memory that calculates and stores the capacitance and internal resistance of the electric double layer capacitor for each preset period based on time information from the timer, and stores the memory in the memory 2. The power backup apparatus according to claim 1, further comprising a function of performing an estimation process of a remaining usable period of the electric double layer capacitor based on the change tendency of the capacitance and the internal resistance. .

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