JP2015133817A - Backup power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backup power supply device which prevents voltage unevenness and fully supplies electric energy to a load circuit, when supplying electric energy from a plurality of capacitors included in the backup power supply device to the load circuit.SOLUTION: A backup power supply device 1 which includes capacitors charged with power received from a main power supply device 8 and which supplies power to a load circuit 9 from the capacitors when the power supply is stopped. The backup power supply device 1 comprises: a capacitor module 2 configured by connecting a plurality of capacitors; a switch circuit 3 for switching the connection state of the plurality of capacitors to a serial state or a parallel state; and control means 4 for controlling the connection state of the capacitors in a charge mode for charging the capacitor module and a backup mode for supplying power from the capacitor module to the load circuit. In the backup mode, the plurality of capacitors are connected in series to supply power to the load circuit and are periodically connected in parallel to equalize working voltage of the capacitors.

Description

  The present invention relates to a backup power supply device. More specifically, the present invention relates to a backup power supply device that supplies electrical energy stored in a plurality of capacitors to a load circuit while preventing voltage nonuniformity of the capacitors.

2. Description of the Related Art A backup power supply device that accumulates electric energy supplied from a commercial power supply, a power generation device, etc., and supplies power to various machines, devices, facilities, etc. when the main power supply stops is widely used. Conventionally, secondary batteries such as lead batteries, nickel metal hydride batteries, lithium ion batteries have been used as power storage devices for such backup applications, but in recent years, electric double layer capacitors, etc. instead of these secondary batteries, Increasingly, capacitors having a high energy density are applied. For example, an electric double layer capacitor has an energy density that is several tens of times that of a lithium ion battery. However, in recent years, the positive electrode has a structure of an electric double layer and the negative electrode uses lithium chemical reaction. Ion capacitors have also been developed. A lithium ion capacitor has an energy density of several times to several tens of times that of an electric double layer capacitor. In general, these capacitors have a longer life than storage batteries. Further, the capacitor can be charged and discharged in a much shorter time than a secondary battery. As a result, in an application in which a load that consumes a large amount of power is backed up for a relatively short time, it is advantageous to apply a small-sized and long-life capacitor as an electricity storage device.
However, when using a high energy density capacitor, it is important to take measures against charging and discharging so as not to cause overcharging and overdischarging. As an example, in a lithium ion capacitor having an electrostatic capacity of several tens to several hundreds of F, the maximum usable voltage is 3.8 V and the lower limit voltage is 2.2 V, and it is necessary to use within that voltage range. In addition, a plurality of capacitors are often used for power storage, and there is variation in capacitance among the capacitors. Therefore, it is preferable to use the same voltage (inter-terminal voltage) for each capacitor. .

There is known a charging device that rapidly charges a capacitor bank including a plurality of electric double layer capacitors by intermittent charging and equalizes the charging voltage of each capacitor (see, for example, Patent Document 1). In this charging apparatus, the charging voltage of each capacitor is equalized by intermittently charging a capacitor bank provided with a capacitor series-parallel switching circuit and connecting the cells in parallel while charging is stopped.
In addition, a DC power supply device including a capacitor module in which a plurality of capacitors are connected in series is disclosed (see, for example, Patent Document 2). This DC power supply device is provided with a voltage non-equalization suppression circuit in which a normally open switch and a resistor are connected in parallel for each capacitor, and the charging voltage of a plurality of capacitors is more acceptable than the charging voltage of other capacitors. By connecting resistors in parallel for capacitors that are higher than the range, variations in voltage between terminals of each capacitor are suppressed.

JP 2001-309571 A JP2012-115103A

As described above, high energy density capacitors such as electric double layer capacitors and lithium ion capacitors have variations in capacitance from capacitor to capacitor. Therefore, when a backup power supply device is configured using a plurality of such capacitors, a backup period for charging the plurality of capacitors and a backup circuit for supplying electric energy stored in the plurality of capacitors to the load circuit. In the period, it is required to prevent overcharge and overdischarge for each capacitor.
However, in the charging device described in Patent Document 1, even if the charging voltage of each capacitor during charging is equalized, it has not been studied to protect the capacitor from overdischarge in backup applications. In other words, since the voltage between terminals of each capacitor after charging is not equalized, overdischarge occurs due to variations in the capacitance of the capacitor during the backup period in which power is supplied to the load circuit after charging is not performed. There's a problem. In order to prevent such overdischarge, it is necessary to monitor whether or not the working voltage (voltage between terminals) is equal to or higher than the lower limit voltage for each capacitor.
Also in the DC power supply device described in Patent Document 2, the problem of capacitor overdischarge in the backup period is not solved. In addition, in order to detect a capacitor whose charging voltage is higher than the allowable range from the charging voltage of other capacitors among the plurality of capacitors, it is necessary to measure the terminal voltage for each capacitor. Furthermore, in the backup period, if it is attempted to equalize the operating voltage using a configuration in which resistors are connected in parallel as appropriate for each capacitor, there is a problem that power is wasted due to the resistors connected in parallel. .

  As described above, in applications where a plurality of capacitors are connected in series to supply power to the load circuit, even if charging voltage unevenness for each capacitor is suppressed during the charging period, power is transferred from the capacitor to the load circuit after charging. In the backup period in which the voltage is supplied, the voltage used by each capacitor is uneven. A method of monitoring the voltage between terminals for each capacitor and stopping the supply of power when one of the capacitors drops to the lower limit voltage is conceivable. The use is limited by the small capacitor, and there is a problem that the electric energy stored in the plurality of capacitors cannot be fully utilized.

  The present invention has been made in view of the above situation, and at the time of backup supplying electric energy stored in a plurality of capacitors to a load circuit, voltage non-uniformity for each capacitor is prevented and stored in the capacitors. It is an object of the present invention to provide a backup power supply device that can supply electric energy without any excess.

1. A backup power supply device that receives power from the main power supply device to charge the capacitor, and supplies power from the capacitor to the load circuit when power supply from the main power supply device is stopped,
A capacitor module configured by connecting a plurality of capacitors;
A switch circuit that switches a connection state of the plurality of capacitors in series or in parallel;
Control for controlling connection states of the plurality of capacitors by the switch circuit in a charging mode in which power is supplied from the main power supply device and charging the capacitor module, and in a backup mode in which power is supplied from the capacitor module to the load circuit. Means,
With
In the backup mode, the control means supplies the power to the load circuit by connecting the plurality of capacitors in series, and equalizes the voltage used for each capacitor by connecting them in parallel at a predetermined cycle. A backup power supply characterized by that.
2. a use voltage detection circuit for detecting a voltage between terminals of the two capacitors;
In the backup mode, the control means stops power supply to the load circuit when a voltage detected by the use voltage detection circuit becomes a predetermined value or less when the plurality of capacitors are connected in parallel. The above 1. The backup power supply described.
3. A voltage conversion circuit comprising an inductor inserted in series between the capacitor module and the load circuit; and an output voltage detection circuit for detecting an output voltage of the voltage conversion circuit,
The control unit controls at least one of a period and a period of connecting the plurality of capacitors in parallel so that a voltage detected by the output voltage detection circuit falls within a predetermined range in the backup mode. Or 2. The backup power supply unit described in 1.
4). In the charging mode, the control unit connects the plurality of capacitors in parallel to perform charging. To 3. The backup power supply apparatus in any one of.
5. The control means switches to operate in the charging mode while a voltage supplied from the main power supply device is equal to or higher than a predetermined value, and switches to operate in the backup mode when the voltage falls below the predetermined value. 1. To 4. The backup power supply apparatus in any one of.
6). The main power supply is supplied with commercial power,
A power failure detection circuit for detecting at least one of a power failure and a voltage drop of the commercial power supply,
The control unit is switched to operate in the backup mode when a power failure or a voltage drop is detected by the power failure detection circuit. To 4. The backup power supply apparatus in any one of.

  According to the backup power supply device of the present invention, the backup power supply device that receives power from the main power supply device to charge the capacitor and supplies power from the capacitor to the load circuit when the power supply from the main power supply device is stopped. A capacitor module configured by connecting a plurality of capacitors, a switch circuit that switches a connection state of the plurality of capacitors in series or in parallel, and charging that receives power from the main power supply device and charges the capacitor module And a control means for controlling connection states of the plurality of capacitors by the switch circuit in a backup mode for supplying power from the capacitor module to the load circuit. In the backup mode, the control means includes the A plurality of capacitors are connected in series to In order to equalize the voltage used for each capacitor by supplying power to the capacitor and connecting them in parallel at a predetermined cycle, the use is limited by the capacitor having the smallest capacitance among the capacitors connected in series. Therefore, the electrical energy stored in the plurality of capacitors can be supplied to the load circuit without any excess. In addition, it is not necessary to monitor the voltage for each capacitor, and wasteful power is not consumed by the resistance element or the like in order to equalize the operating voltage.

A voltage detection circuit that detects a voltage between terminals of one of the capacitors; and the control unit detects a voltage detected by the voltage detection circuit when the plurality of capacitors are connected in parallel in the backup mode. If the power supply to the load circuit is stopped when the value becomes equal to or less than a predetermined value, overdischarge can be reliably prevented while fully utilizing the capacities of all capacitors.
A voltage conversion circuit comprising an inductor inserted in series between the capacitor module and the load circuit; and an output voltage detection circuit for detecting an output voltage of the voltage conversion circuit; In the backup mode, when controlling at least one of a period and a period of connecting the plurality of capacitors in parallel so that a voltage detected by the output voltage detection circuit falls within a predetermined range, A DC-DC converter can be configured very simply using switching of parallel connections, and a stable power supply can be supplied to the load circuit.
In the charging mode, when the charging is performed by connecting the plurality of capacitors in parallel in the charging mode, the control means performs charging without causing unevenness in the charging voltage of each capacitor by an extremely simple circuit configuration and control. Monitoring and control can be easily performed so that the charging voltage does not exceed the maximum working voltage of the capacitor.

When the control means switches to operate in the charging mode while the voltage supplied from the main power supply device is equal to or higher than a predetermined value, and to operate in the backup mode when the voltage falls below the predetermined value. In this case, it is possible to quickly supply power from the capacitor module to the load circuit when a decrease in the output voltage of the main power supply device is detected without using a separate means.
The main power supply device is supplied with commercial power, and includes a power failure detection circuit that detects at least one of a power failure and a voltage drop of the commercial power source, and the control means detects a power failure or a voltage drop by the power failure detection circuit. When switching to operate in the backup mode when detected, an uninterruptible power supply can be configured very simply.

The present invention will be further described in the following detailed description with reference to the drawings referred to, with reference to non-limiting examples of exemplary embodiments according to the present invention. Similar parts are shown throughout the several figures.
It is a block diagram showing the structure of a backup power supply device. It is a timing chart for demonstrating the change of an output voltage when the connection of a capacitor is switched in backup mode. 5 is a timing chart for explaining the operation of the backup power supply device. It is a block diagram showing the structure of the backup power supply device provided with the voltage conversion circuit. It is a timing chart for demonstrating the operation | movement as a DC-DC converter in the state in which the capacitor of the backup power supply device is fully charged. It is a timing chart for demonstrating operation | movement as a DC-DC converter in the state which discharge of the capacitor of the backup power supply device advanced. It is a block diagram showing another structure of a backup power supply device. It is a block diagram showing the structure of the uninterruptible power supply using a backup power supply device.

Hereinafter, the present invention will be described in detail with reference to the drawings.
The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

The configuration of the backup power supply apparatus according to this embodiment is shown in FIG. In the figure, the input side of the backup power supply 1 is connected to the main power supply 8 and the output side is connected to the load circuit 9.
The main power supply device 8 is a DC power supply for charging at least a capacitor built in the backup power supply device 1, and supplies a power supply DCin to the backup power supply device 1. The voltage of the power source DCin is not limited as long as the capacitor can be charged, and is not necessarily stabilized. The type of the main power supply device 8 is not particularly limited, and may be, for example, an AC-DC converter that receives a commercial power supply to generate a DC voltage, or power generation using natural energy such as a generator or a solar cell. It may be a device, a dynamic energy recovery device, or the like.

  The load circuit 9 is a target to which power is supplied from the backup power supply device 1 when the power supply that normally receives power supply is stopped. The load circuit 9 can be configured to supply normal power from the main power supply device 8. The type of the load circuit 9 is not limited, and examples thereof include various electronic devices, information processing devices, machines, lighting equipment, and electric appliances. In FIG. 1, a DC power supply DCout is output from the backup power supply device 1 to the load circuit 9. The voltage of the power supply DCout is not particularly limited. The power supply DCout can be configured to be supplied via a voltage smoothing circuit, a DC-DC converter, an inverter, or the like according to the type and characteristics of the load circuit 9.

  The backup power supply device 1 is configured to receive power from the main power supply device 8 to charge a built-in capacitor and to supply power to the load circuit 9 from the capacitor. The backup power supply device 1 includes a plurality of capacitors (2a, 2b, 2c, etc., hereinafter collectively referred to as “capacitor 2”. Also, the entire configuration constituted by connecting a plurality of capacitors is referred to as “capacitor module 2” ), A switching circuit 3 (31, 32) for switching the connection state between the plurality of capacitors in series or in parallel, a charging mode for receiving power from the main power supply device 8 and charging the capacitor module 2, and the capacitor module And a control means 4 for controlling the connection state of the plurality of capacitors 2 by the switch circuit 3 in a backup mode in which power is supplied from 2 to the load circuit 9.

  The type of the capacitor 2 is not particularly limited, and examples thereof include an electric double layer capacitor and a lithium ion capacitor having a high energy density. Although three capacitors (2a, 2b, 2c) are shown in FIG. 1, the number of capacitors 2 is not limited and may be determined according to the power supply voltage and capacity required for the load circuit 9. For example, in the case of using a capacitor having a power supply voltage of 5 to 10 V for the load circuit 9 and one maximum usable voltage of 4 V, the working voltage of the capacitor having at least three capacitors and connected in series is used. Is preferably higher than the power supply voltage of the load circuit 9. In this case, the load circuit 9 can be configured to supply power via a voltage conversion circuit that steps down the output voltage of the capacitor module 2. Further, when the power supply voltage of the load circuit 9 is high, the load circuit 9 can be connected to the load circuit 9 via a voltage conversion circuit that boosts the output voltage of the capacitor module 2.

The switch circuit 3 includes switch elements 31, 32 and the like, and is a circuit for mainly switching the connection state between the plurality of capacitors 2 in series or in parallel. A plurality of switch elements 31 and 32 are provided corresponding to the number of capacitors 2. In the example of FIG. 1, a total of five switch elements 31 are provided, three between the power source DCin and the positive terminals of the three capacitors, and two between the negative terminal of each capacitor and the reference potential 0V. ing. Further, the positive terminals and the negative terminals of the three capacitors 2 are connected via two switch elements 32.
All switch elements 31 and all switch elements 32 can be configured to be switched simultaneously. In the switch circuit 3, when the switch element 31 is closed (on) and 32 is open (off), all capacitors 2 are connected in parallel, and when the switch element 31 is open (off) and 32 is closed (on) , All the capacitors 2 are connected in series.

The switch circuit 3 can include a separate switch element such as the switch element 311 as necessary. For example, the switch element 311 can be used to control the power supply to the load circuit 9 side. When the switch element 311 is opened (off), the power supply from the capacitor 2 to the load circuit 9 side is stopped. can do. A diode D1 may be placed instead of the switch element 311 so that current flows only in the direction from the capacitor 2 toward the load circuit 9 side.
All switch elements are configured to be controllable by the control means 4. As the switch element, a switching transistor (eg, FET) can be used.

The control unit 4 uses the switch circuit 3 to perform a plurality of operations in the charging mode in which the power is supplied from the main power supply device 8 to charge the capacitor 2 and in the backup mode in which power is supplied from the charged capacitor 2 to the load circuit 9. This is means for controlling the connection state of the capacitor 2. Further, the control unit 4 includes a PWM (pulse width modulation) control unit, and the backup power supply device can function as a DC-DC converter in the backup mode (a backup power supply device 11 described later).
The control means 4 may be configured by either hardware or software, or may be configured by combining them. For example, the control means 4 can be configured using a microcomputer (microcontroller) and peripheral circuits.

  The backup power supply device 1 is provided with a power supply (7) required for its operation (not shown). The configuration of the power supply (7) necessary for the operation of the backup power supply device 1 such as the control means 4 and the switch circuit 3 is not particularly limited. For example, when the main power supply 8 is in operation (charging mode), power is supplied from the main power supply 8 (81), and when the main power supply 8 is stopped (when operating in the backup mode), a voltage conversion circuit ( 6) etc., it can be configured to receive supply of electric power stored in the capacitor 2 (see FIG. 8). Moreover, you may provide the storage battery for operating the control means 4, etc. as needed.

The “charging mode” intends an operation mode during a period (charging period) in which the backup power supply device 1 is supplied with power from the main power supply device 8. During the charging mode, the capacitor 2 is charged. Meanwhile, the load circuit 9 can be configured to be supplied with power (normal power) from the main power supply 8 or a separate power supply.
The “backup mode” is an operation during a period (backup period) in which the power supply device that supplies normal power to the load circuit 9 stops and the power of the capacitor 2 stored in the charge mode by the backup power supply device 1 is supplied to the load device 9. Intended aspects.

FIG. 2 is a timing chart showing changes in the voltage of the capacitor module 2 when the switch circuit 3 is switched. (A) shows the on / off state of the switch elements 31 and 32, and (b) shows the voltage generated between both ends of the capacitor module 2 connected in series or in parallel (in FIG. A voltage at point “A”) Va.
In the series connection period Ts in which the switch element 31 is off and 32 is on, the capacitor 2 is connected in series. Then, at every cycle T1, the switch element 31 is turned on and 32 is turned off, and the capacitor 2 is connected in parallel (parallel connection period Tp).
The voltage Va is a voltage output from the output DCout of the backup power supply device 1 while the switch element 311 is on during the backup period, and is hereinafter referred to as “the output voltage of the capacitor module 2”.

It is assumed that the capacitor module 2 includes n capacitors, and the voltage between the terminals of one capacitor is Vc. In the series connection period Ts, n capacitors are connected in series, and the value Vs of the voltage Va at this time is n × Vc. In the parallel connection period Tp, n capacitors are connected in parallel, and the value Vp of the voltage Va at this time is equal to Vc. Even if there is variation in the capacitance of each capacitor, the unevenness of the used voltage is eliminated by the charge transfer between the capacitors in the state of being connected in parallel.
The “operating voltage” refers to the voltage between the terminals of one capacitor 2 and is also referred to as “charging voltage” in the charging mode.

  The backup power supply device 1 includes a use voltage detection circuit 41 that detects a voltage between the terminals of one capacitor 2, and the detection result can be obtained by the control means 4. The control means 4 can periodically switch the capacitors 2 connected in series to the parallel connection, and detect the equalized use voltage of the capacitor 2 in the parallel connection period Tp (“M” point in FIG. 2). In the charging mode, the control means 4 can be configured to prevent overcharging by comparing the detected use voltage with the maximum use voltage defined for one capacitor 2. In the backup mode, the control means 4 can be configured to prevent overdischarge by comparing the detected use voltage with the lower limit voltage defined for one capacitor 2.

With reference to FIG. 3, a series of operations of the backup power supply device 1 through the charging mode and the backup mode will be described. 4A shows the voltage of the DC power supply DCin supplied from the main power supply device 8, FIG. 4B shows the on / off state of the switch elements 31 and 32, and FIG. Represents the voltage Va. In the figure, the time _t 0 ~t ₁ operation of the charging mode, the time _t 1 ~t ₂ represents the operation of the backup mode.

If the time t ₀ from the primary power supply apparatus 8 supplies the DC power supply is started, the backup power supply unit 1 operates in charge mode. In the charging mode, the backup power supply device 1 charges the capacitor 2 without supplying power to the load circuit 9. In order to cut off the power supply to the load circuit 9, for example, the switch element 311 may be turned off.
The charging method of the capacitor 2 in the charging mode is not particularly limited. For example, according to the circuit configuration shown in FIG. 1, the control means 4 can be configured to perform charging by always connecting a plurality of capacitors 2 in parallel (see “A” in FIG. 3). Further, the capacitor 2 can be connected in series and charged with a small current by another circuit configuration (see “B” in FIG. 3). Further, the capacitors 2 can be connected in series to perform charging, and in order to prevent the charging voltage from becoming uneven due to variations in the capacitors 2, the capacitors 2 can be connected in parallel at an appropriate period.

  When charging the capacitor 2 in either a serial state or a parallel state, it is necessary to prevent overcharging by controlling the charging voltage of the capacitor 2 so as not to exceed the maximum operating voltage by monitoring the charging voltage. is there. In any case, the control means 4 can detect the charging voltage by the use voltage detection circuit 41 during the period in which the capacitors 2 are connected in parallel. And, for example, by performing constant current charging until the detected charging voltage reaches a predetermined voltage (for example, 80% of the maximum use voltage), and controlling to switch to constant voltage charging after exceeding the predetermined voltage, Capacitor 2 can be sufficiently charged and overcharge can be prevented.

When the power supply from the time t ₁ to the main power supply 8 is stopped, the operation of the backup power supply device 1 is switched to immediately backup mode by the control unit 4. The method for determining the stop of the power supply from the main power supply device 8 is not limited. For example, as shown in FIG. 1, the backup power supply device 1 includes an input voltage detection circuit 43 that detects the voltage (Vin) of the input DCin, and the control means 4 receives the voltage Vin received from the main power supply device 8. Can be switched to operate in the charging mode when the voltage is greater than or equal to a predetermined value, and to operate in the backup mode when the voltage Vin falls below the predetermined value.

  In addition, the switching timing from the charging mode to the backup mode can be selected by an external switch signal or the like. For example, when a generator is used as the power source, even if the generator is stopped for a short time, it can be switched to the backup mode by the stop signal and power can be supplied from the capacitor module 2 to the load circuit 9. Further, if the load circuit 9 is an electric device that uses a commercial power source, the capacitor module 2 can be switched to the backup mode by switching to the backup mode even if the commercial power source is turned off or the electric device is disconnected from the commercial power source. Can be supplied with power.

  In the backup mode, the control means 4 connects the plurality of capacitors 2 in series to supply power to the load circuit 9, and periodically connects them in parallel for a predetermined time (Tp). Since the plurality of capacitors 2 are periodically connected in parallel, the non-uniformity in the voltage used for each capacitor that occurred in the period (Ts) connected in series due to variations in each capacitor was connected in parallel. It is eliminated by the charge transfer. The length of the period Tp in which the capacitor 2 is in the parallel connection state and the period T1 for switching to the parallel connection state can be set as appropriate.

  In the backup period, a plurality (n) of capacitors 2 are connected in series during the period Ts, and are connected in parallel during the period Tp with the period T1. When the voltage between terminals (use voltage) per capacitor at a certain point in time is Vc, the voltage Vs = n × Vc of the capacitor modules 2 connected in series and the voltage Vp = Vc of the capacitor modules 2 connected in parallel are obtained. Since current is supplied from the capacitor module 2 to the load circuit 9, as shown in FIG. 3, the voltages Vs and Vp decrease due to discharge over time. The control means 4 can detect the voltage Vp by the use voltage detection circuit 41 during the parallel connection period Tp.

Therefore, when the value of the use voltage Vp detected in the parallel connection state reaches the lower limit voltage Ve defined for the capacitor 2 (time t ₂ ), the control unit 4 stops the power supply to the load circuit 9. be able to. Since the voltage used for each capacitor 2 is equalized, overdischarge can be prevented for all the capacitors, and the energy stored in the n capacitors can be used without any excess. That is, one capacitor reaches the lower limit voltage Ve due to the variation of each capacitor, while the other capacitors are equal to or higher than the lower limit voltage Ve and the electric energy that can be used as a whole remains, but the lower limit voltage Ve. The problem that the backup must be terminated to protect the capacitor that has reached the voltage Ve is solved.
Means for stopping the power supply to the load circuit 9 is not limited. For example, the switch element 311 may be opened, but all the switch elements 31 and 32 may be opened (see FIG. 1). A separate blocking means may be provided.

  The backup power supply device includes a voltage conversion circuit (6) having an inductor inserted in series between the capacitor module 2 and the load circuit 9, and an output voltage detection circuit for detecting an output voltage of the voltage conversion circuit (6). (45). With this configuration, the backup power supply apparatus can have a function as a DC-DC converter in the backup mode.

FIG. 4 shows an example of configuring a step-down DC-DC converter. The backup power supply device 11 includes a voltage conversion circuit 6 in which an inductor 61 (inductance L) is inserted in series with the output circuit of the capacitor module 2. The output of the capacitor module 2 is connected to one end of the inductor 61 via the switch element 311. The switch element 311 is configured to perform the same opening / closing operation as the switch element 32 in the backup mode. That is, the switch element 311 is closed (ON) while the capacitor 2 is connected in series, and the output of the capacitor module 2 is supplied to the voltage conversion circuit 6. On the other hand, while the capacitor 2 is connected in parallel, the switch element 311 is opened (off), and the output of the capacitor module 2 is not supplied to the voltage conversion circuit 6.
The other end of the inductor 61 is connected to the output end (DCout2) of the voltage conversion circuit 6. A capacitor 63 is connected to the other end of the inductor 61 between the reference potential 0V. A voltage Vm obtained by dividing the output voltage of the voltage conversion circuit 6 by the resistors 65 and 66 is input to the output voltage detection circuit 45 for detecting the output voltage of the voltage conversion circuit 6. A diode 62 is connected between the one end of the inductor 61 and the reference potential 0V.

5 and 6 are timing charts for explaining the operation as a DC-DC converter of the backup power supply device 11 including the voltage conversion circuit 6 shown in FIG. FIGS. 5 and 6A are the on / off states of the switch elements 31 and 32, FIG. 5B is the output voltage of the capacitor module 2 (the voltage at the “A” point with respect to 0V) Va, and FIG. The current I _L flowing through 61 (d) represents the voltage of the output DCout2 of the voltage conversion circuit 6. In the following description, it is assumed that three capacitors 2 having a maximum usable voltage of 4 V are used per unit, and the output voltage of the voltage conversion circuit 6 is controlled within a range of 5 V ± 20 mV. For simplicity, it is assumed that the power consumption of the load circuit 9 is always 24 W and the power conversion efficiency is 100%.

First, with reference to FIG. 5, an operation in a state where the capacitor 2 is sufficiently charged will be described. The control means 4 switches the capacitor in a series connection state (period Ts ₁ ) and a parallel connection state (period Tp ₁ ) periodically (period T ₁ ) using the switch circuit 3. If each capacitor is charged to the maximum operating voltage 4V, the value V ₁ of the output voltage Va of the capacitor module 2 periods Ts ₁ to capacitor are connected in series is 12V. Therefore, if the voltage drop due to the diode 62 is ignored, the voltage input to the voltage conversion circuit 6 is about 12 V in the series connection period Ts ₁ and about 0 V in the parallel connection period Tp ₁ .

Since the output voltage of the voltage converter circuit 6 is about 5V, the voltage _{V L} generated across the inductor 61 is approximately in the serial connection period _{Ts 1 (12V-5V =)} 7V, approximately in parallel connection period Tp ₁ (0V −5V =) − 5V. Since the voltage V _L generated between both ends of the inductor 61 and the current I _L flowing therethrough have a relationship of VL = L (dI _L / dt), the current I _L is, as shown in FIG. In the series connection period Ts ₁ , the pulsating flow increases (the increase rate is L (dI _L / dt) = 7V) and decreases in the parallel connection period Tp ₁ (the decrease rate is L (dI _L / dt) = 5V). The average value I _{1 of the} current is about 4.8 A, and thereby, about 24 W of power is supplied to the load circuit 9.

Next, in a state where the discharge of the capacitor 2 has progressed and the use voltage has decreased, the operation of the backup power supply device 11 changes as shown in FIG. In this state, the control means 4 periodically switches between the capacitor serial connection state (period Ts ₂ ) and the parallel connection state (period Tp ₂ ). In this example, the cycle T1 for switching the capacitor to the parallel connection is the same as in the previous figure. In a state where the operating voltage of each capacitor is lowered to 2V (the lower limit voltage of the capacitor is lower than 2V), the value V ₂ of the output voltage Va of the capacitor module 2 in the period Ts ₂ in which the capacitors are connected in series. Is 6V. Therefore, if the voltage drop due to the diode 62 is ignored, the voltage input to the voltage conversion circuit 6 is about 6 V in the series connection period Ts ₂ and about 0 V in the parallel connection period Tp ₂ .

Since the output of the voltage conversion circuit 6 is about 5V, the voltage _{V L} generated across the inductor 61 is approximately in the serial connection period _{Ts 2 (6V-5V =)} 1V, in the parallel connection period Tp ₂ about (0V- 5V =)-5V. Then, the current I _L flowing through the inductor 61 increases in the series connection period Ts ₂ as shown in FIG. 6C (the rate of increase is L (dI _L / dt) = 1 V), and in the parallel connection period Tp ₂ It becomes a pulsating flow that decreases (decreasing rate is L (dI _L / dt) = 5V). The average value I _{2 of the} current is about 4.8 A, and thereby, about 24 W of power is supplied to the load circuit 9. The series connection period is longer (Ts ₁ <Ts ₂ ) and the parallel connection period is shorter (Tp ₁ > Tp ₂ ) than when the operating voltage of the capacitor 2 is not reduced.
As described above, the backup power supply device 11 controls the time of the series connection period Ts ₁ and the parallel connection period Tp ₁ to stabilize the voltage of the output (DCout2) supplied to the load circuit 9 to about 5 V (5 V). ± 20 mV).

  In the backup power supply device 11 including the voltage conversion circuit 6, even if the operating voltage of the capacitor 2 changes due to the above action, the control means 4 outputs (by changing the series connection period Ts and the parallel connection period Tp) ( The voltage of DCout2) can be stabilized within a certain range. For this purpose, the control means 4 detects the output voltage of the voltage conversion circuit 6 by the output voltage detection circuit 45, and controls the switching timing of the connection state of the capacitor 2 so that the voltage value falls within a predetermined range. can do.

  The control method of the switching timing of the connection state of the capacitor 2 by the control means 4 is not particularly limited. For example, as shown in FIGS. 5 and 6, if the period T1 for switching the capacitor 2 to the parallel connection is constant, the series connection period Ts or the parallel connection period so that the output voltage of the voltage conversion circuit 6 falls within a predetermined range. The length of Tp (ratio between Ts and Tp) can be changed. Further, the output voltage of the voltage conversion circuit 6 may be controlled to be within a predetermined range by changing the period T1 for connecting the capacitors 2 in parallel. In other words, the control means 4 controls at least one of the length of the parallel connection period Tp or the series connection period Ts of the capacitor 2 and the length of the period T1, so that the output voltage of the voltage conversion circuit 6 is predetermined. It can be controlled to be in range. The control means 4 can easily control the period T1, the series connection period Ts, and the parallel connection period Tp by, for example, PWM (pulse width modulation) control. When the drive signal for the switch element 31 or 32 is a pulse signal generated by PWM and the period T1 is constant, the parallel connection period Tp and the series connection period Ts can be changed depending on the duty ratio of PWM.

  Further, the control means 4 can detect the use voltage Vp of the capacitor 2 using the use voltage detection circuit 41 during the parallel connection period Tp of the capacitor 2. When it is detected that the use voltage Vp of the equalized capacitor 2 has decreased to the lower limit voltage Ve in the state in which the discharge of the capacitor 2 has progressed as shown in FIG. The power supply to the side can be stopped.

In this backup power supply device, as described above, the charging method of the capacitor 2 in the charging mode is not particularly limited. For example, using the circuit configuration of the backup power supply device 1 (see FIG. 1), the control unit 4 can always connect the capacitors 2 in parallel during the charging mode and charge the capacitors 2. Further, by opening the switch element 311 during the charging mode, the power supply to the load circuit 9 side can be cut off.
For example, the capacitor 2 can be connected in series in the charging mode to be chargeable by a circuit configuration as shown in FIG. The backup power supply device 12 in this figure includes switch elements 36 and 37, and other configurations are the same as those in FIG. The capacitor 2 can be connected in series and charged with the switch elements 36 and 37 closed (on), the switch element 31 open, and the switch element 32 closed. Further, periodically, the switch element 37 is opened (off), the switch elements 36 and 31 are closed, and the switch element 32 is opened, so that the capacitor 2 is connected in parallel and the charge voltage of each capacitor is reduced. Unevenness can be resolved. In a state where the capacitors 2 are connected in parallel, it is possible to detect the charging voltage of the capacitor 2 using the use voltage measuring circuit 41.

  FIG. 8 illustrates a configuration example of an uninterruptible power supply (UPS) that receives supply of commercial power, to which the backup power supply described above is applied. This uninterruptible power supply device includes a capacitor module 2, a switch circuit 3, a control means 4, a voltage conversion circuit 6, and the like. The main power supply device 8 for charging the capacitor module 2 includes an AC-DC converter 81, a constant current supply circuit 82, a constant voltage supply circuit 83, and a constant current that are supplied with commercial (AC) power and generate DC power. The power supply switch 85 and the like for switching between the supply circuit 82 and the constant voltage supply circuit 83 are configured.

  When the AC power is turned on, the control means 4 is connected to the constant current supply circuit 82 by the power switch 85, and the capacitor module 2 is charged with a constant current. And the control means 4 detects the charging voltage (Vp) of the capacitor 2 using the use voltage detection circuit 41, and when the charging voltage Vp exceeds a predetermined voltage, the power changeover switch 85 is set to a constant voltage supply circuit. Connect to 83 side. Thereby, overcharging of the capacitor 2 can be prevented.

In this example, a power failure detection circuit 47 that detects at least one of a power failure and a voltage drop of the AC power supply is provided, and abnormality (voltage drop, power failure, instantaneous power failure, etc.) of the AC power supplied to the main power supply device 8 is detected. I try to detect it. The specific configuration / function of the power failure detection circuit 47 is not particularly limited. For example, it may be detected that the voltage of the AC power source has become a predetermined value or less (voltage drop). You may make it detect that it interrupted more than predetermined time (power failure or instantaneous power failure). Further, it is possible to detect an abnormality of the AC power source by combining these conditions.
The control means 4 can be switched to operate in the charging mode while the AC power is normally supplied, and to operate in the backup mode when an abnormality in the AC power is detected by the power failure detection circuit 47.
Without being limited thereto, the input voltage detection circuit 43 that detects the voltage of the input power supply DCin of the capacitor module 2 is provided, and the control means 4 determines whether or not the DC voltage supplied from the main power supply device 8 is a predetermined value or more. You may make it switch between charge mode and backup mode.

  Further, in this example, a DC-DC converter 7 that generates a power supply Vcc necessary for the operation of the backup power supply apparatus (control unit 4 or the like) is provided. The input of the DC-DC converter 7 is connected to the outputs of the main power supply device 8 (AC-DC converter 81) and the voltage conversion circuit 6. Thereby, the backup power supply device (the control means 4 and the like) can be supplied with power from the main power supply device 8 in the charging mode, and can be supplied with power from the voltage conversion circuit 6, that is, the backup power supply device itself in the backup mode.

  The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the present invention depending on the purpose and application.

1, 11, 12; backup power supply device, 2 (2a, 2b, 2c); capacitor module (capacitor), 3 (31, 32, 34, 36, 37, 311); switch circuit (switch element), 4; control Means 41: Used voltage detection circuit 43: Input voltage detection circuit 45: Output voltage detection circuit 47: Power failure detection circuit 6: Voltage conversion circuit 61: Inductor 63: Capacitor 7: DC-DC converter 8; Main power supply device, 81; AC-DC converter, 82; Constant current supply circuit, 83; Constant voltage supply circuit, 85; Power supply switch, 9;

Claims (6)

A backup power supply device that receives power from the main power supply device to charge the capacitor, and supplies power from the capacitor to the load circuit when power supply from the main power supply device is stopped,
A capacitor module configured by connecting a plurality of capacitors;
A switch circuit that switches a connection state of the plurality of capacitors in series or in parallel;
Control for controlling connection states of the plurality of capacitors by the switch circuit in a charging mode in which power is supplied from the main power supply device and charging the capacitor module, and in a backup mode in which power is supplied from the capacitor module to the load circuit. Means,
With
In the backup mode, the control means supplies the power to the load circuit by connecting the plurality of capacitors in series, and equalizes the voltage used for each capacitor by connecting them in parallel at a predetermined cycle. A backup power supply characterized by that. A use voltage detection circuit for detecting a voltage between terminals of one of the capacitors;
In the backup mode, the control means stops power supply to the load circuit when a voltage detected by the use voltage detection circuit becomes a predetermined value or less when the plurality of capacitors are connected in parallel. The backup power supply device according to claim 1. A voltage conversion circuit comprising an inductor inserted in series between the capacitor module and the load circuit; and an output voltage detection circuit for detecting an output voltage of the voltage conversion circuit,
2. The control unit controls at least one of a period and a period of connecting the plurality of capacitors in parallel so that a voltage detected by the output voltage detection circuit falls within a predetermined range in the backup mode. Or the backup power supply device according to 2;   4. The backup power supply device according to claim 1, wherein the control unit performs charging by connecting the plurality of capacitors in parallel in the charging mode. 5.   The control means switches to operate in the charging mode while a voltage supplied from the main power supply device is equal to or higher than a predetermined value, and to operate in the backup mode when the voltage falls below the predetermined value. Item 5. The backup power supply device according to any one of Items 1 to 4. The main power supply is supplied with commercial power,
A power failure detection circuit for detecting at least one of a power failure and a voltage drop of the commercial power supply,
The backup power supply device according to any one of claims 1 to 4, wherein the control means is switched to operate in the backup mode when a power failure or a voltage drop is detected by the power failure detection circuit.

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