JP2010022086A - Dc power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC power system capable of avoiding an overvoltage output to a load. <P>SOLUTION: In the DC power system having a battery pack 4 with one or more storage batteries connected in series and a charger 5 charging the battery pack 4 for supplying power to the load 3, the battery pack 4 is connected either to the load 3 or to the charger 5 through a tri-polar double-throw switch 7. Characteristically, the DC power system is configured such that the tri-polar double throw switch 7 allows the battery pack 4 to be connected to the charger 5 when the battery pack 4 is charged, and that the tri-polar double throw switch 7 allows the battery pack 4 to be connected to the load 3 when the battery pack 4 is not charged. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a DC power supply system.

  Generally, in a DC power supply system that supplies power to a DC load device, a rectifier that receives commercial AC power and outputs DC power such as DC 48V is used. Further, in order to continue power supply to the load device even when the commercial power is interrupted, the output of the rectifier is provided with a storage battery and a charger for charging the storage battery to provide a backup power supply system.

  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, 2, and 3 listed below describe a power supply system that supplies power output from a plurality of assembled batteries to a load via a discharger. Patent Document 1 discloses a battery pack and a converter in the discharger. It is described that the electric circuit between the two is electrically connected to each other by a common conducting wire, and Patent Document 2 allows each operation of the discharger to be performed based on the same operation signal transmitted by the control unit. Patent Document 3 describes that a booster circuit or a step-down circuit operates so that a discharger output voltage is within a set range.
JP 2007-143266 A JP 2007-143291 A JP 2007-31558 A

  Taking the DC power supply system described in Patent Document 3 as an example, the problem of a DC power supply system that supplies power from a storage battery to a load via a discharger during backup will be described.

  In FIG. 6 (same as FIG. 3 of Patent Document 3), the power output from the nickel-metal hydride storage battery 1 is supplied to the load 4 via the booster circuit 2 and the step-down circuit 3. The reason why the step-up circuit and the step-down circuit are necessary is that the voltage when the nickel-metal hydride storage battery 1 is fully charged exceeds the allowable voltage range of the load 4, and the discharge end voltage is below the allowable voltage range of the load 4. is there.

  In the invention described in Patent Document 3, when the voltage of the nickel-metal hydride storage battery 1 fluctuates in a range not less than the seventh set value and not more than the eighth set value, the output voltage of the booster circuit 2 is set to the seventh set value. The switching element 8 of the step-up circuit 2 operates so as not to fall below the ninth set value which is larger than the value and smaller than the eighth set value, and the output voltage of the step-down circuit 3 is larger than the seventh set value and The switching element 9 of the step-down circuit 3 operates so as not to exceed a tenth set value that is smaller than the set value of 8 and larger than the ninth set value.

  With this operation, when the voltage of the nickel metal hydride storage battery 1 exceeds the allowable voltage range of the load 4, the voltage stepped down by the step-down circuit 3 is supplied to the load 4, and when the voltage is below the allowable voltage range, the voltage is boosted by the booster circuit 2. Electric power is supplied to the load 4. That is, it is possible to keep the power supply voltage to the load 4 within an allowable range.

  The reason why the power supply voltage to the load 4 must be within the allowable voltage range is that the load 4 cannot be operated with a power supply voltage that falls below the allowable range, and that the load 4 fails when the power supply voltage exceeds the allowable range. There is a fear. When the power supply voltage falls below the allowable range and the load 4 stops, the load 4 can be operated again by supplying power at a voltage within the allowable range, but a voltage exceeding the allowable range is applied to the load 4. In such a case, a failure of the load 4 occurs, and there is a possibility that the load 4 cannot be operated normally even if a voltage within the allowable range is applied thereafter. Therefore, not applying a voltage exceeding the allowable range to the load 4 is a problem to be considered with priority over not falling below the allowable range.

  However, since the switching element 9 included in the step-down circuit 3 has two states, a short circuit and an open state, when a control failure to the switching element 9 or a failure of the switching element 9 itself occurs, the switching element 9 is short-circuited. It remains unchanged in either open state. When the switching element 9 remains open and no longer changes, the nickel-metal hydride storage battery 1 and the load 4 are disconnected, so that the operation of the load 4 only stops. However, when the switching element 9 remains short-circuited and does not change, the nickel metal hydride storage battery 1 is directly connected to the load 4 through the step-down circuit 3. At this time, when a charger is connected to the nickel metal hydride storage battery 1 and the battery is charged with a voltage exceeding the allowable range of the load 4, a voltage exceeding the allowable range is applied to the load 4. May occur.

  As described above, when charging an assembled battery with a voltage exceeding the allowable range of the load in order to fully charge the assembled battery, there is a method of interposing a step-down circuit to prevent overvoltage output to the load. There is a problem that an overvoltage generated by the charger may be applied to the load when the switching element included in the circuit is short-circuited and may cause the load to fail.

  The present invention has been made in view of the above-described problem that an overvoltage generated by a charger may be applied to a load when the switching element included in the step-down circuit is short-circuited, and the load may be damaged. The problem to be solved is to provide a DC power supply system that avoids overvoltage output to a load.

In order to solve the above problem, in the present invention, as described in claim 1,
In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load, the assembled battery is operated by a three-pole double-throw switch. The three-pole double-throw switch is connected to the load or the charger and the battery pack is charged, and the three-pole double-throw switch connects the battery pack to the charger and the battery pack is not charged. Connects the assembled battery to the load to constitute a DC power supply system.

In the present invention, as described in claim 2,
In a DC power supply system that includes an assembled battery in which one or more storage batteries are connected in series and a charger that charges the assembled battery, and supplies power to a load, the assembled battery is operated by a three-pole double-throw switch. The battery pack is connected to the load or the charger, and after the three-pole double-throw switch connects the battery pack to the battery charger, charging of the battery pack is started. The three-pole double-throw switch connects the assembled battery to the load when the voltage is equal to or lower than a first voltage that is equal to or lower than an allowable upper limit voltage of the load.

In the present invention, as described in claim 3,
In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load, the assembled battery is operated by a three-pole double-throw switch. A diode that is connected to the load or the charger and passes power only in a discharge direction from the assembled battery to the load between the three-pole double-throw switch and the load; After the switch connects the assembled battery to the charger, charging of the assembled battery is started, and after the end of charging, the voltage of the assembled battery is set to a first voltage that is lower than the allowable upper limit voltage of the load. The DC power supply system is characterized in that the three-pole double-throw switch connects the assembled battery to the load when the voltage becomes equal to or less than a voltage obtained by adding absolute values of directional voltage drops.

In the present invention, as described in claim 4,
In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load, the assembled battery is operated by a three-pole double-throw switch. A diode that is connected to the load or the charger and passes power only in the discharge direction from the assembled battery to the load is inserted between the three-pole double-throw switch and the load, and the AC power is converted to DC power. A rectifier for converting to the load is connected in parallel, the output voltage of the rectifier is less than an allowable upper limit voltage of the load, and after the three-pole double-throw switch connects the battery pack to the charger, Charging of the assembled battery is started, and after completion of charging, when the voltage of the assembled battery becomes equal to or lower than the voltage obtained by adding the absolute value of the forward voltage drop of the diode to the second voltage equal to or lower than the output voltage of the rectifier Tripolar Switch constitutes a DC power supply system, characterized by connecting the assembled battery to the load.

In the present invention, as described in claim 5,
A plurality of DC power supply systems according to any one of claims 1 to 4 are connected in parallel in a power supply line from the three-pole double-throw switch to the load.

In the present invention, as described in claim 6,
6. The DC power supply system according to claim 5, wherein at least one of the three-pole double-throw switches for connecting the assembled battery to the load is always present.

  According to the present invention, since the charger output voltage is not output to the load even if the battery is charged with a voltage exceeding the allowable range of the load in order to fully charge the battery, the failure of the load is avoided. Therefore, it is possible to provide a DC power supply system with high power supply reliability.

  In the present invention, in a DC power supply system that includes an assembled battery in which one or more storage batteries are connected in series and a charger that charges the assembled battery and supplies power to a load, the assembled battery includes three A pole double throw switch is connected to the load or the charger, and when the assembled battery is charged, the three pole double throw switch connects the assembled battery to the charger, and when the assembled battery is not charged, the A three-pole double-throw switch connects the assembled battery to the load.

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

<Embodiment 1>
FIG. 1 is a diagram for explaining an embodiment of the present invention. In the figure, the assembled battery 4 is an assembled battery constructed by connecting a plurality of nickel metal hydride storage battery cells (rated voltage 1.2 V, rated capacity 100 Ah) in series.

  In order for the nickel metal hydride storage battery to be fully charged, a charging voltage of up to 1.6V is required, so the charger 5 inputs AC power from the AC power source 1 and outputs DC power of up to 64V. To do. Further, in order to limit the charging current, the output current of the charger 5 is a maximum of 20A.

  The load 3 is a DC load, and the allowable range of the power supply voltage is 57V to 40.5V.

  The three-pole double-throw switch 7 is connected to switch the connection of the assembled battery 4 to the charger 5 or the load 3. One of the three poles is connected to the negative terminal of the assembled battery 4, and the other is the charger 5. The negative terminal of the output is connected to the negative terminal of the load 3. In a three-pole double-throw switch, one terminal (referred to as terminal A) can be connected to two terminals (referred to as terminals B and C), but the terminal B and C can be in any state. Never connected. In this embodiment, the terminals A, B, and C are the negative terminal of the assembled battery 4, the negative terminal of the output of the charger 5, and the negative terminal of the load 3, respectively, so that the connection from the charger 5 to the load 3 occurs. I don't get it.

  The three-pole double-throw switch 7 receives the signal from the control unit 9 to connect the battery pack 4 and the charger 5 (charging mode), and the signal from the control unit 9 is reset so that the connection is established. Is an assembled battery 4 and a load 3 (discharge mode). Specifically, such switching can be realized by using a relay 8, for example, as shown in FIG. The relay 8 is a three-pole double-throw relay, and the control unit 9 controls the current to the coil portion of the relay 8, whereby the connection of the assembled battery 4 can be switched between the charger 5 and the load 3.

  When the three-pole double-throw switch 7 enters the charging mode by a signal from the control unit 9, the assembled battery 4 is connected to the charger 5, and the charger 5 charges the assembled battery 4 with DC power (maximum 64V, maximum 20A). . During charging, unless the output voltage of the charger 5 reaches 64V, the voltage of the assembled battery 4 rises while the charging current is maintained constant (20A). The signal to 7 is reset and charging is terminated.

  After the charging is completed, the connection of the three-pole double-throw switch 7 becomes the assembled battery 4 and the load 3 and enters the discharge mode.

  The voltage of the nickel metal hydride battery cell rises up to 1.6 V when fully charged, but in a standby state where it is not charged, the voltage drops to 1.42 V or less even immediately after full charging. That is, the voltage of the assembled battery 4 in the standby state is 56.8V or less. For this reason, the voltage of the assembled battery 4 exceeds the allowable upper limit voltage (57 V) of the load 3 during charging. However, when charging is finished and the discharge mode is set, the voltage is lower than the allowable upper limit voltage (57 V) of the load 3. Therefore, the assembled battery 4 can be fully charged without applying a voltage exceeding the allowable range to the load 3.

  Further, when a failure occurs in the three-pole double-throw switch 7, the assembled battery 4 does not operate while being connected to the charger 5 (case 1), or the assembled battery 4 does not operate while being connected to the load 3. Either (Case 2) or the case where the device does not operate without being connected to either (Case 3) is assumed. In case 1, even if the voltage of the assembled battery 4 exceeds the allowable upper limit voltage of the load 3, overvoltage application to the load 3 does not occur. In case 2, the voltage of the assembled battery 4 has an allowable upper limit voltage. In case 3, the battery pack 4 is not connected to the load 3. That is, no voltage exceeding the allowable upper limit voltage is applied to the load 3 in any state at the time of failure.

  Thus, by switching the connection of the assembled battery between the charger and the load using the three-pole double-throw switch, an overvoltage output to the load can be avoided.

  In the present embodiment, the assembled battery 4 is connected to the load 3 immediately after being fully charged. However, in order to increase the reliability of power supply to the load device, the first battery that is equal to or lower than the allowable upper limit voltage (57 V) of the load 3 is used. A voltage (here, 56V) is set and the output of the charger 5 is stopped after full charge, but the connection of the three-pole double-throw switch 7 remains in the charge mode, and the voltage of the assembled battery 4 is set to the first voltage ( 56V) It is also possible to switch to the discharge mode after waiting for the voltage to become lower.

<Embodiment 2>
FIG. 3 is a diagram for explaining an embodiment of the present invention. 1 except that a backflow preventing diode 6 is inserted on the discharge circuit from the assembled battery 4 to the load 3. The assembled battery 4 is an assembled battery configured by connecting a plurality of nickel-metal hydride storage battery cells (rated voltage 1.2 V, rated capacity 100 Ah) in series with 40 cells.

  The diode 6 passes electric power only in the discharge direction from the assembled battery 4 to the load 3, and the forward voltage drop is 1.0 V (minimum value). The charger 5 receives AC power from the AC power source 1 and outputs DC power of a maximum of 64 V, and the output current of the charger 5 is 20 A at maximum. The load 3 is a DC load, and the allowable range of the power supply voltage is 57 V to 40.5 V, but the upper limit voltage is set to 56 V (first voltage lower than the allowable upper limit voltage of the load 3) in consideration of power supply reliability. It is assumed that The connection and control of the three-pole double-throw switch 7 are the same as in the first embodiment, and the charging mode is set by a signal from the control unit 9, and the discharging mode is set by resetting the signal.

  When the three-pole double-throw switch 7 enters the charging mode by a signal from the control unit 9, the assembled battery 4 and the charger 5 are connected, and the charger 5 charges the assembled battery 4 with DC power (maximum 64V, maximum 20A). . During charging, as long as the output voltage of the charger 5 does not reach 64V, the voltage of the assembled battery 4 rises while the charging current is maintained constant (20 A).

  When the discharge mode is set immediately after full charge as in the first embodiment, the voltage of the assembled battery 4 is 56.8V, and the voltage applied to the load 3 is reduced to 55.8V by reducing the forward voltage drop of the diode 6. It is. Therefore, power can be supplied without exceeding the upper limit voltage (56 V) of the load 3.

  Similar to the first embodiment, since a voltage exceeding the allowable upper limit voltage is not applied to the load 3 in any state at the time of failure, an overvoltage output to the load can be avoided.

  When the first voltage is set to 55 V, which is even lower, the output of the charger 5 is stopped after full charge, but the connection of the three-pole double-throw switch 7 remains in the charging mode, and the voltage of the assembled battery 4 is 56 V. It may be switched to the discharge mode after waiting for (the first voltage + the absolute value of the forward voltage drop of the diode 6) or less.

<Embodiment 3>
FIG. 4 is a diagram for explaining an embodiment of the present invention. 3 except that the output of the rectifier 2 is connected in parallel to the power supply line from the diode 6 to the load 3. The load 3 is a DC load, and the allowable range of the power supply voltage is 57V to 40.5V.

  The rectifier 2 converts AC power input from the AC power source 1 into DC power and outputs the DC power, and the output voltage is set to be equal to or lower than the allowable upper limit voltage of the load 3 (for example, 56 V).

  The assembled battery 4 is an assembled battery configured by connecting a plurality of nickel-metal hydride storage battery cells (rated voltage 1.2 V, rated capacity 100 Ah) in series with 40 cells. The diode 6 passes electric power only in the discharge direction from the assembled battery 4 to the load 3, and the forward voltage drop is 1.0 V (minimum value).

  The charger 5 receives AC power from the AC power source 1 and outputs DC power of a maximum of 64 V, and the output current of the charger 5 is 20 A at maximum. The connection and control of the three-pole double-throw switch 7 are the same as in the first embodiment, and the charging mode is set by a signal from the control unit 9, and the discharging mode is set by resetting the signal. When the three-pole double-throw switch 7 enters the charging mode by a signal from the control unit 9, the assembled battery 4 is connected to the charger 5, and the charger 5 charges the assembled battery 4 with DC power (maximum 64V, maximum 20A). . During charging, as long as the output voltage of the charger 5 does not reach 64V, the voltage of the assembled battery 4 rises while the charging current is maintained constant (20 A).

  When the discharge mode is set immediately after full charge as in the first embodiment, the voltage of the assembled battery 4 is 56.8V, and the voltage applied to the load 3 is reduced to 55.8V by reducing the forward voltage drop of the diode 6. It is. Since the present embodiment is a system in which the output of the rectifier 2 is preferentially supplied to the load 3 and discharged from the assembled battery 4 when the AC power supply 1 is interrupted, the voltage on the assembled battery 4 side is the output voltage of the rectifier 2. For example, if it is set to 56V, the voltage will not be exceeded and the assembled battery 4 will not discharge to the load 3. FIG.

  Similar to the first embodiment, since a voltage exceeding the allowable upper limit voltage is not applied to the load 3 in any state at the time of failure, an overvoltage output to the load can be avoided.

  When the upper limit voltage of the load 3 is set to 56V and the output voltage of the rectifier 2 is set to 55.5V, the output of the rectifier 2 is used as the upper limit voltage on the assembled battery 4 side at the parallel connection point of the rectifier 2 and the assembled battery 4 side. A second voltage (here 55 V) that is equal to or lower than the voltage is set and the output of the charger 5 is stopped after full charging, but the connection of the three-pole double-throw switch 7 remains in the charging mode, and the voltage of the assembled battery 4 Is set to 56 V (second voltage + absolute value of the forward voltage drop of the diode 6) or less, and the discharge mode may be switched.

  In each embodiment of the present invention, the three-pole double-throw switch 7 is connected to the minus terminal, but the same effect can be obtained even if it is connected to the plus terminal.

  In each embodiment of the present invention, one battery system includes a system composed of the assembled battery 4, the charger 5, the diode 6, and the three-pole double throw switch 7 (these are collectively referred to as a battery system). Although applied to the system, it can also be applied to a system having a plurality of battery systems as shown in FIG. Each three-pole double-throw switch 7 may be operated and switched by a signal from a control unit 9 (not shown). Although FIG. 5 shows a configuration in which the rectifier 2 is connected in parallel to the load 3 and includes the diode 6, a configuration without the rectifier 2 or a configuration without the diode 6 is also possible. In addition, even if a power failure occurs during the charging mode, the three-pole double-throw switch 7 of each battery system is not set to the charging mode at the same time, and scheduling is performed so that some battery systems are always in the discharging mode. Discharge capability can be maintained. In addition, each battery system is not equipped with a charger 5, but a plurality of battery system chargers 5 are mounted to supply DC power to a plurality of three-pole double-throw switches 7 and connected to the assembled battery 4 to be charged. The three-pole double-throw switch 7 can be charged by performing a switching operation.

  As described above, the embodiment of the present invention has been described by taking the DC power supply system using the nickel-metal hydride storage battery as an example, but the present invention is not limited to this.

  Below, the effect produced by this invention is demonstrated.

  When charging an assembled battery with a voltage exceeding the allowable range of the load in order to fully charge the assembled battery, there is a method of inserting a step-down circuit to prevent overvoltage output to the load, but switching included in the step-down circuit There is a problem that an overvoltage generated by the charger is applied to the load when the element is short-circuited and the load may be broken.

  According to the present invention, the battery pack being charged is electrically disconnected from the load, and even when the three-pole double-throw switch used for disconnection fails, the charger cannot be connected to the load. Output can be avoided.

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 example of embodiment of this 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 an example of the conventional DC power supply system.

Explanation of symbols

  1: AC power source, 2: rectifier, 3: load, 4: battery pack, 5: charger, 6: diode, 7: three-pole double-throw switch, 8: relay, 9: control unit, and so on in FIG. Excluding the sign.

Claims (6)

In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load,
The assembled battery is connected to the load or the charger by a three-pole double-throw switch,
When the battery pack is charged, the three-pole double-throw switch connects the battery pack to the charger;
The DC power supply system, wherein the three-pole double throw switch connects the assembled battery to the load when the assembled battery is not charged. In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load,
The assembled battery is connected to the load or the charger by a three-pole double-throw switch,
After the three-pole double-throw switch connects the assembled battery to the charger, charging of the assembled battery is started, and after completion of charging, the voltage of the assembled battery is equal to or lower than an allowable upper limit voltage of the load. The DC power supply system, wherein the three-pole double-throw switch connects the assembled battery to the load when: In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load,
The assembled battery is connected to the load or the charger by a three-pole double-throw switch,
Between the three-pole double-throw switch and the load, a diode that passes power only in the discharge direction from the assembled battery to the load is inserted,
After the three-pole double-throw switch connects the assembled battery to the charger, charging of the assembled battery is started, and after completion of charging, the voltage of the assembled battery is equal to or lower than an allowable upper limit voltage of the load. The three-pole double-throw switch connects the assembled battery to the load when the voltage is equal to or lower than the voltage obtained by adding the absolute value of the forward voltage drop of the diode to the DC power supply system. In a DC power supply system having an assembled battery formed by connecting one or more storage batteries in series and a charger for charging the assembled battery, and supplying power to a load,
The assembled battery is connected to the load or the charger by a three-pole double-throw switch,
Between the three-pole double-throw switch and the load, a diode that passes power only in the discharge direction from the assembled battery to the load is inserted,
A rectifier that converts AC power to DC power is connected in parallel to the load,
The output voltage of the rectifier is less than the allowable upper limit voltage of the load,
After the three-pole double-throw switch connects the assembled battery to the charger, charging of the assembled battery is started, and after the charging is finished, the voltage of the assembled battery becomes a second voltage equal to or lower than the output voltage of the rectifier. The DC power supply system, wherein the three-pole double-throw switch connects the assembled battery to the load when the voltage becomes equal to or less than a sum of absolute values of forward voltage drops of the diodes.   A DC power supply system comprising a plurality of DC power supply systems according to any one of claims 1 to 4 connected in parallel in a feeder line extending from the three-pole double-throw switch to the load.   6. The DC power supply system according to claim 5, wherein at least one of the three-pole double-throw switches for connecting the assembled battery to the load is always present.

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