JP2009165257A - Dc power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC power system capable of enhancing a utilization rate of an apparatus by effectively using a charger even while the apparatus is not in a charging state. <P>SOLUTION: This DC power system includes: a battery pack 4 composed of a combination of one or more secondary cells; a rectifier 2 for converting AC power to DC power and supplying electric power to a load 6; a charger 3 having a rectifying function; and switching means composed of switching devices 17a, 17b as a constituent component. The charger 3 converts the AC power to DC power for output. The switching means executes switching between connection for supply of an output of the charger 3 to the battery pack 4 and connection for supply of an output of the charger 3 to the load 6. The battery pack 4 supplies DC power to the load 6 through a diode 5 which allows DC power to pass an electric current in a discharge direction alone if the AC power has a power failure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC power supply system, and more particularly, to a DC power supply system that includes a storage battery that converts AC power into DC power and supplies the power to a load and serves as a backup during a power failure.

  In general, a power supply system that supplies power to a DC load device uses a rectifier that receives commercial AC power and outputs DC power such as DC 48V. Furthermore, a storage battery and a charger for charging the storage battery are provided in order to continue power supply to the load device even when the commercial power fails. When a storage battery is applied to a DC power supply system, an assembled battery in which one or more storage batteries called single cells are connected in parallel is used.

Patent Documents 1 and 2 below describe a battery system that supplies power output from a plurality of assembled batteries to a load via a discharger. Patent Document 1 describes a battery system and a converter in the discharger. Are described as being electrically connected to each other by a common conductor, and Patent Document 2 describes that each operation of the discharger is performed based on the same operation signal transmitted by the control unit. ing.
JP 2007-143266 A JP 2007-143291 A

  FIG. 6 is a diagram illustrating the basic configuration of the DC power supply system. In the figure, AC power from a commercial power source 1 is supplied to a rectifier 2, and the rectifier 2 converts the AC power into predetermined DC power and supplies it to a load 6. The assembled battery 4 is an assembled battery formed by combining a plurality of storage batteries. When the commercial power source 1 is effective, the assembled battery 4 is charged via the charger 3 and to the load 6 via the discharger 14 when the commercial power source 1 is interrupted. Discharge.

  The charger 3 stops when the assembled battery 4 is fully charged, and does not charge again until the assembled battery 4 is discharged and the amount of stored power is reduced. For this reason, the charger 3 operates only when the assembled battery 4 is charged, and there is a problem that the utilization factor of the device is lowered.

  The present invention has been made in view of the problem that the charger can be used only during charging, and the problem to be solved by the present invention is to use the charger effectively even when the charger is not charged. An object of the present invention is to provide a DC power supply system capable of improving the power. That is, in the prior art, the rectifier and the charger function are integrated, and the rectifier and the charging function are integrated by operating the rectifier provided in the charger and the power supply rectifier in a coordinated manner. The problem to be solved is to increase the efficiency of the rectification function and reduce the redundancy of the rectifier.

In the present invention, in order to solve the above problem, as described in claim 1,
A DC power supply system including a battery pack including one or more storage batteries, a rectifier that converts AC power into DC power and supplies power to a load, a charger having a rectification function, and switching means. The charger converts the AC power into DC power and outputs the power, and the switching means includes a connection for supplying the output of the charger to the assembled battery, and a connection for supplying the output to the load. The battery pack is configured to supply DC power to the load via a diode that passes current only in the discharge direction when the AC power is interrupted. .

In the present invention, as described in claim 2,
2. The DC power supply system according to claim 1, wherein an output voltage of the charger is equal to or lower than a first voltage equal to or lower than an output voltage of the rectifier, and an output current of the charger is equal to or lower than a current value set as an upper limit. When the connection by the switching means is a connection for supplying the output of the charger to the assembled battery, when the output voltage of the charger becomes equal to or higher than a second voltage equal to or lower than the first voltage, The switching means switches the connection to a connection for supplying the output of the charger to the load, and when the connection by the switching means is a connection for supplying the output of the charger to the load, the voltage of the assembled battery When the battery voltage becomes equal to or lower than a third voltage lower than the second voltage, or when the storage capacity of the assembled battery decreases below a certain amount, the switching means connects the charger to the charger. Configuring the DC power supply system and switches the output to the connection supplied to the battery pack.

In the present invention, as described in claim 3,
3. The DC power supply system according to claim 1, wherein the switching unit includes a switching element interposed in an electric path from the charger to the assembled battery, and an electric path from the charger to the load. The DC power supply system is characterized in that switching is performed by the switching means when only one of the switching elements is closed.

In the present invention, as described in claim 4,
4. The DC power supply system according to claim 1, wherein the charger includes a rectifier and a step-down unit, converts the AC power into DC power by the rectifier, and outputs the DC power through the step-down unit. A direct-current power supply system is configured.

In the present invention, as described in claim 5,
5. The DC power supply system according to claim 4, wherein the step-down circuit as the step-down means is provided with a plus-side electric circuit and a minus-side electric circuit connecting the input end and the output end, and one of the two electric circuits is provided. In the electric circuit, the switching element is inserted on the side close to the input terminal, and the reactor is inserted on the side close to the output terminal, respectively, and the electric circuit between the switching element and the reactor is interposed between the electric circuit and the other electric circuit. Indicates that a diode is inserted in a direction that allows current to flow from the negative-side electric circuit to the positive-side electric circuit, and a capacitor is inserted between the electric circuit between the reactor and the output terminal and the other electric circuit. A characteristic DC power supply system is configured.

In the present invention, as described in claim 6,
6. The DC power supply system according to claim 1, wherein when the connection by the switching means is a connection for supplying an output of the charger to the assembled battery, an output current value of the charger is a first value. When the current value falls below the current value, the switching means switches the connection to a connection for supplying the output of the charger to the load.

In the present invention, as described in claim 7,
7. The DC power supply system according to claim 1, wherein a plurality of sets of the assembled batteries are connected in parallel via diodes that pass power only in a discharging direction, and the charger is connected to each of the assembled batteries. The direct current power supply system is configured.

In the present invention, as described in claim 8,
8. The DC power supply system according to claim 7, wherein the number of the assembled batteries to be charged simultaneously is smaller than the total number of the assembled batteries.

  The DC power supply system according to the present invention can provide the following effects.

  When the charger is not charging, it is responsible for supplying the load with the rectifier, so the charger can be effectively used as a spare rectifier, reducing the redundancy of the rectifier and saving cost and space It becomes possible.

  A DC power supply system according to the present invention includes an assembled battery formed by combining one or more storage batteries, a rectifier that converts AC power into DC power and supplies power to a load, a charger having a rectifying function, and switching means. A DC power supply system as a component, wherein the charger converts the AC power into DC power and outputs the power, and the switching means connects the supply of the output of the charger to the assembled battery, Switching between connection to supply output to the load, and the battery pack supplies DC power to the load via a diode that passes current only in the discharge direction when the AC power fails.

  Hereinafter, embodiments of the present invention will be described by taking a DC power supply system in which the storage battery is a lead storage battery or a nickel hydride storage battery as an example, but the present invention is not limited to this.

  FIG. 1 is a diagram for explaining an embodiment of the present invention. In the figure, the rectifier 2 converts AC power input from the commercial power source 1 into DC power, outputs DC 51V, and supplies power to the load 6.

  The assembled battery 4 is an assembled battery (rated voltage 46 V, rated capacity 200 Ah) configured by connecting 23 lead-acid battery cells (rated voltage 2.0 V, rated capacity 200 Ah) in series. When the battery pack 4 is charged, the voltage rises, but the full charge voltage of the lead-acid battery cell is 2.2 V, and the full charge voltage of the battery pack 4 is 50.6 V (first voltage). The first voltage (50.6 V) is set to be equal to or lower than the output voltage (51 V) of the rectifier 2. The assembled battery 4 discharges to the load 6 through a power supply line to which a diode 5 that passes power only in the discharge direction is connected.

  The charger 3 converts AC power input from the commercial power source 1 into DC power and outputs DC 50.6V (first voltage). The current value set as the upper limit of the output current is 10A, When the output current exceeds 10A, the output voltage droops.

  The output of the charger 3 is supplied to the assembled battery 4 for charging or supplied to the load 6 by the operation of the switching elements 7a and 7b which are components of the switching means. When the switching element 7a is closed and 7b is open, the output of the charger 3 is supplied to the assembled battery 4, whereby the assembled battery 4 is charged. When the switching element 7a is open and 7b is closed, the output of the charger 3 can be supplied to the load 6, but the output voltage (51V) of the rectifier 2 is higher than the output voltage (50.6V) of the charger 3. Is higher, the output of the rectifier 2 is preferentially supplied to the load 6. As described above, the switching means including the switching elements 7 a and 7 b switches between the connection for supplying the output of the charger 3 to the assembled battery 4 and the connection for supplying the output to the load 6.

  The charger 3 not only converts the AC power input from the commercial power source 1 into DC power, but also performs voltage control of the DC power. Such voltage control is necessary when charging the assembled battery 4. For this voltage control, for example, the charger 3 includes a rectifier and step-down means, and the rectifier included in the charger 3 converts the AC power input from the commercial power source 1 into DC power and outputs it. The step-down means (for example, step-down circuit) provided in the charger 3 may be stepped down and used as the output of the charger 3.

  An example of the step-down circuit is shown in FIG. In the figure, a plus-side electric circuit (upper horizontal line) and a minus-side electric circuit (lower horizontal line) connecting the input end and the output end are provided, and the switching element on the side closer to the input end is provided on the minus-side electric circuit. 11, the reactor 8 is inserted on the side close to the output end, and a current is passed from the minus-side circuit to the plus-side circuit between the switching element 11 and the reactor 8 and the plus-side circuit. Is inserted, and a capacitor 9 is inserted between the electric circuit between the reactor 8 and the output terminal and the electric circuit on the plus side, but the switching element 11 and the reactor 8 are connected respectively. Even if it moves to the corresponding position on the plus side of the circuit, the operation of the circuit remains unchanged.

  In this case, an enhancement type field effect transistor (FET) is used as the switching element 11. An enhancement-type FET is open between the drain and source when there is no potential difference between the gate and source, and the resistance between the drain and source decreases as the potential difference between the gate and source increases. It is a switching element that can be regarded as a (short circuit state).

  The control unit 12 monitors the output voltage and sets a duty ratio related to a PWM (Pulse Width Modulation) signal to the switching element 11 in order to control the output voltage. Here, the duty ratio is a ratio of the ON time of the PWM signal. In this step-down circuit, since an enhancement type FET is used, decreasing the duty ratio (increasing the OFF time ratio) decreases the output voltage and increasing the duty ratio (increasing the ON time ratio). As a result, the output voltage rises.

  When the commercial power source 1 is active, the rectifier 2 outputs a direct current 51V to supply power to the load 6, closes the switching element 7a and opens 7b, and the charger 3 charges the assembled battery 4. When the voltage of the assembled battery 4 rises due to charging and the output voltage of the charger 3 reaches 50.5 V (second voltage), the switching element 7a is opened, the charging is terminated by closing 7b, and the charger 3 can supply power to the load 6. The second voltage (50.5V) is set to be equal to or lower than the first voltage (50.6V).

  Here, the charger 3 outputs DC 50.6V (first voltage), and since the voltage (50.6V) is lower than the output voltage 51V of the rectifier 2, power is not supplied to the load 6. Acts as a backup rectifier.

  The rectifier 2 is configured by connecting a plurality of rectifier units in parallel. However, when a part of the units stops due to a failure and the remaining units cannot supply power to the load 6, the shortage is charged by the charger 3. As a result, discharge from the assembled battery 4 can be prevented.

  When the commercial power source 1 fails, the assembled battery 4 supplies power to the load 6 via the diode 5, and when the power supply is restored from the power failure, the switching element 7a is closed and the assembled battery 4 is charged by opening 7b. Do.

  Here, the switching elements 7a and 7b are enhancement-type field effect transistors, which are closed when a voltage is applied to the gate electrode thereof, and opened when the voltage is reset. FIG. The switching elements 7a and 7b are controlled according to

  In FIG. 3, in the initial state, both the switching elements 7a and 7b are open because no voltage is applied to the gate electrodes.

  In step 11 (represented by S11, the same applies hereinafter), the switching element 7a is closed (the assembled battery 4 is charged), and the process proceeds to step 12.

In step 12, if the output voltage (Vc) of the charger 3 is equal to or higher than the second voltage (V ₂ = 50.5V), the process proceeds to step 13; otherwise, the process returns to step 12.

  In step 13, the switching element 7 a is opened, and the process proceeds to step 14.

  In step 14, the switching element 7b is closed, and the process proceeds to step 15.

In step 15, when the voltage (Vb) of the assembled battery 4 is equal to or lower than the third voltage (V ₃ = 50.0V), the process proceeds to step 16, and otherwise, the process returns to step 15. Here, the third voltage _(V 3 = 50.0V) is set to be lower than the second voltage _(V 2 = 50.5V).

  In step 16, the switching element 7 b is opened, and the process returns to step 11. If the commercial power source 1 is valid, charging of the assembled battery 4 is started.

  As described above, since the output of the charger 3 is switched to the load 6 when the assembled battery 4 is almost fully charged and works as a spare rectifier, there is no need to install an extra rectifier, and cost and space are reduced. Can be saved.

  In this embodiment, a lead storage battery is used, but a nickel hydride storage battery can also be used. However, since charging with a constant current is suitable for nickel metal hydride storage batteries, when the charger 3 is charging the assembled battery 4, charging is performed when the output current value falls below 8A (first current value). It suffices to switch the output of the charger 3 to the load 6.

  Further, in the present embodiment, the condition for starting charging by switching the output of the charger 3 to the assembled battery 4 is when the voltage of the assembled battery 4 becomes equal to or lower than the third voltage. The charge / discharge amount of 4 and the self-discharge amount can be estimated, and charging can be started when the storage capacity of the assembled battery 4 falls below a certain amount.

  Further, in the present embodiment, the assembled battery 4 is one set, but as shown in FIG. 4, a system in which a plurality of sets of assembled batteries 4 are connected in parallel via a diode 5 that passes power only in the discharge direction. It can also be applied. Each assembled battery 4 may be provided with a charger 3, and the switching elements 7a and 7b may charge the assembled battery 4 and supply power to the load 6. In FIG. 4, since three chargers 3 can be used as spare rectifiers, if the assembled batteries 4 are charged one by one, two or more spare rectifiers can be secured at all times. Power supply reliability can be increased. That is, the number of battery packs 4 that are charged at the same time is less than the total number of battery packs 4, and the reliability of power supply to the load 6 can be increased, including handling during power outages.

  FIG. 5 is a diagram showing an embodiment in which the integration of the rectifying function and the charging function is further advanced than the above-described embodiment. In the figure, the rectifier 2 has the functions of the charger 3 and the functions of the switching means. That is, the rectifier 2 includes n (plural) rectifier units: 2-1,..., 2-n and switching elements 7a and 7b, and a part of the rectifier unit controller 13 and the rectifier unit 2-n. However, it is comprised so that it may have the same function as the charger 3, and the switching elements 7a and 7b comprise the switching means which performs the same operation | movement by the rectifier unit control part 13. FIG.

  As mentioned above, although the case where the storage battery is a direct current power supply system which is a lead storage battery or a nickel metal hydride storage battery has been described as an example of the embodiment of the present invention, the present invention is not limited to this.

  Below, the effect produced by this invention is demonstrated.

  In a DC backup power supply system combining a rectifier and a storage battery, in order to ensure power supply capability even in the event of a rectifier failure, more rectifiers are installed (redundant configuration) than necessary, but in the present invention, a charger using a storage battery Can be effectively utilized as a spare rectifier by connecting the output to a load when it is not necessary to charge the battery, it is possible to reduce the redundancy of the rectifier.

It is a figure explaining the example of embodiment of this invention. It is a figure explaining an example of a step-down circuit. It is a figure explaining the control flowchart in the example of an embodiment of the invention. It is a figure explaining the example of embodiment of this invention. It is a figure explaining the example of embodiment of this invention. It is a figure explaining the direct-current power supply system which combined the rectifier, the storage battery, the charger, and the discharger.

Explanation of symbols

1: commercial power supply, 2: rectifier, 3: charger, 4: assembled battery, 5: diode, 6: load, 7a, 7b: switching element, 8: reactor, 9: capacitor, 10: diode, 11: switching element , 12: controller, 13: rectifier unit controller, 14: discharger.

Claims (8)

A DC power supply system including a battery pack including one or more storage batteries, a rectifier that converts AC power into DC power and supplies power to a load, a charger having a rectification function, and switching means. And
The charger converts the AC power into DC power and outputs it,
The switching means performs switching between a connection for supplying the output of the charger to the assembled battery and a connection for supplying the output to the load,
The assembled battery supplies DC power to the load through a diode that allows current to flow only in a discharging direction when the AC power is interrupted. The DC power supply system according to claim 1,
The output voltage of the charger is less than or equal to a first voltage less than or equal to the output voltage of the rectifier;
The output current of the charger is below the current value set as the upper limit,
When the connection by the switching means is a connection for supplying the output of the charger to the assembled battery, when the output voltage of the charger is equal to or higher than a second voltage equal to or lower than the first voltage, the switching is performed. Means switches the connection to a connection that supplies the output of the charger to the load;
When the connection by the switching means is a connection for supplying the output of the charger to the load, when the voltage of the assembled battery becomes equal to or lower than a third voltage lower than the second voltage, or The DC power supply system according to claim 1, wherein when the storage capacity of the battery decreases below a certain amount, the switching means switches the connection to a connection for supplying the output of the charger to the assembled battery. The DC power supply system according to claim 1 or 2,
The switching means includes a switching element inserted in an electric path from the charger to the assembled battery and a switching element inserted in an electric path from the charger to the load, and the switching element The DC power supply system is characterized in that switching by the switching means is performed by closing only one of the elements. In the DC power supply system according to claim 1, 2, or 3,
The charger includes a rectifier and a step-down unit, and converts the AC power into DC power by the rectifier and outputs the DC power through the step-down unit. The DC power supply system according to claim 4, wherein
The step-down circuit, which is the step-down means, is provided with a plus-side electric circuit and a minus-side electric circuit connecting the input end and the output end, and one of the two electric circuits has a side closer to the input end. The switching element is inserted with a reactor on the side closer to the output end, and a negative-side electric circuit is connected to a positive-side electric circuit between the electric circuit between the switching element and the reactor and the other electric circuit. A direct current power supply system, wherein a diode is inserted in a direction to pass a current to the power source, and a capacitor is inserted between the electric circuit between the reactor and the output terminal and the other electric circuit. The DC power supply system according to any one of claims 1 to 5,
When the connection by the switching means is a connection for supplying the output of the charger to the assembled battery, when the output current value of the charger falls below a first current value, the switching means A DC power supply system, wherein the output of the charger is switched to a connection for supplying to the load. The DC power supply system according to any one of claims 1 to 6,
A DC power supply system, wherein a plurality of sets of the assembled batteries are connected in parallel via diodes that pass power only in the discharging direction, and the charger is connected to each of the assembled batteries. In the DC power supply system according to claim 7,
The direct-current power supply system characterized in that the number of the assembled batteries charged simultaneously is smaller than the total number of the assembled batteries.

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