JP2009195079A - Dc power supply system and controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an unload loss due to electrical continuity to a commutator unit in unload state in addition to power dissipation due to performance degradation of the commutator unit. <P>SOLUTION: A DC power supply system includes: a rectifying device 3 containing rectifier units 4<SB>1</SB>-4<SB>n</SB>, which are connected in parallel with each other and each of which converts AC power from a commercial power supply 1 or an engine generator 2 to DC power; a working unit number determination circuit 51 for determining the optimum number of working commutator units based on the total output current of the rectifying device 3 and outputting working commands to commutator units in optimum number out of two or more rectifier units 4<SB>1</SB>-4<SB>n</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC power supply system and a control method thereof.

  As a DC power supply system for supplying power to a communication device, a DC power supply system of DC-48V is mainly used.

  In a DC power supply system, a rectifier that converts AC power from a commercial power source into DC power generally includes a plurality of rectifier units in order to make the output capacity variable by increasing or decreasing the number of rectifier units.

  Further, the rectifier has a configuration in which N + 1 redundant configurations, that is, N + 1 rectifier units are mounted in order to ensure high reliability (see, for example, Patent Document 1). Specifically, the number of rectifier units in the rectifier is a number obtained by adding one redundant unit to the number of units (N units) that can supply power even when the communication load reaches the maximum load.

  FIG. 7 is a diagram illustrating a configuration example of a conventional DC power supply system, and illustrates a configuration in a case where power is supplied to a large number of communication devices.

  Referring to FIG. 7, the conventional DC power supply system includes a commercial power source 1, an engine generator 2, a rectifier 3, a monitoring controller 5, and a storage battery 6.

  The commercial power source 1 and the engine generator 2 are AC power sources.

The rectifiers 3 are connected in parallel to each other, and each of a plurality (n units, n = N + 1) of rectifier units 4 ₁ to 4 _n that convert AC power from the commercial power source 1 or the engine generator 2 into DC power. Contains.

The communication device group 7 is fed with the DC power from the rectifier 3, that is, the total power that is the sum of the DC power from the rectifier units 4 ₁ to 4 _n , and this total power is supplied to each communication device. Sorted. Therefore, the amount of power supplied to the communication device group 7 is managed by this total power.

The monitoring control unit 5 monitors the operation state of the plurality of rectifier units 4 ₁ to 4 _n .

  The storage battery 6 stores the DC power from the rectifier 3. Thus, since the storage battery 6 is connected to the output terminal of the rectifier 3, the DC power from the rectifier 3 does not change frequently.

  The DC power supply system shown in FIG. 7 can supply stable power to the communication device even when the commercial power supply 1 is powered off. Specifically, at the time of a power failure of the commercial power source 1, power can be supplied in a short time without interruption by supplying power from the storage battery 6 to the communication device. Moreover, long-time electric power feeding is possible until the fuel of the engine generator 2 stops when the engine generator 2 starts.

Moreover, since the rectifier 3 has an N + 1 redundant configuration and has a sufficient power supply capability with a margin for one rectifier unit, even if one of the rectifier units 4 ₁ to 4 _n fails. The communication device can be instantaneously supplied with power from other rectifier units. Therefore, the DC power supply system shown in FIG. 7 has a highly reliable system configuration.

The monitoring control unit 5 monitors the operation state of the rectifier unit 4 ₁ to 4 _n, the rectifier unit 4 ₁ to 4 _n to quickly monitoring center when an abnormality of the outage or the like occurs in any of To send the signal, the maintenance person can respond.
JP-A-7-99778

By the way, in the conventional DC power supply system shown in FIG. 7, the number of the rectifier units 4 ₁ to 4 _n in the rectifier 3 can be supplied even when the communication device group 7 becomes the maximum load. The number is determined according to the maximum load capacity of group 7.

However, the communication device does not always have a high operation rate, and may have a low operation rate and a small amount of power consumption. In such a case, a current considerably lower than the rated current is passed through each of the rectifier units 4 ₁ to 4 _n .

  In general, as shown in FIG. 8, the efficiency of the rectifier unit is low when the load factor (representing the ratio of the current flowing through the rectifier unit to the rated current) is low, and increases as the load factor increases. have.

Therefore, when the load factor of each of the rectifier units 4 ₁ to 4 _n is low, the efficiency of each of the rectifier units 4 ₁ to 4 _n is reduced, and the power loss as a whole of the rectifier 3, and consequently the rectifier 3 and the communication device group 7. There is a problem that the power loss of the power generation cable between the two becomes large.

Moreover, even when each rectifier unit 4 ₁ to 4 _n is in a no-load state, there is a problem that no-load loss occurs due to energization of each rectifier unit 4 ₁ to 4 _n .

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a DC power supply system and a control method thereof that can reduce power loss due to efficiency reduction of a rectifier unit and reduce no-load loss due to energization of a rectifier unit in a no-load state. There is.

In order to achieve the above object, the DC power supply system of the present invention includes:
A rectifier including a plurality of rectifier units connected in parallel to each other, each of which converts AC power from an AC power source into DC power;
An output detector for detecting the total output current of the rectifier;
Based on the total output current of the rectifier detected by the output detector, an optimum operating number determination unit that determines the number of operating rectifier units;
A command unit that outputs an operation command to the rectifier units corresponding to the number of operating units determined by the optimum operating number determining unit among the plurality of rectifier units.

  According to this configuration, the optimum operating number of rectifier units is determined based on the total output current of the rectifier, and the rectifier units for the determined operating number are operated.

  In this way, by reducing the number of operating rectifier units, the rectifier units in the operating state can be maintained at a high load factor, so that it is possible to reduce power loss due to a decrease in efficiency of the rectifier units. .

  In addition, by operating the optimal number of rectifier units and waiting for the other rectifier units to operate, it is possible to avoid energizing the rectifier units in the no-load state, thus reducing the no-load loss. Is possible.

And an efficiency curve data storage unit for storing efficiency curve data representing current-efficiency characteristics of each of the plurality of rectifier units,
The optimum operation number determining unit is configured to detect a current total output current of the rectifier detected by the output detection unit and efficiency curve data of each of the plurality of rectifier units stored in the efficiency curve data storage unit. It is good also as determining the operation number of the said rectifier unit by comparing with.

  According to this configuration, the number of operating rectifier units can be determined so that the rectifier units in the operating state maintain high efficiency.

  Further, the optimum operation number determination unit compares the current total output current of the rectifier detected by the output detection unit with the rated current of each of the plurality of rectifier units, so that the rectifier It is also possible to determine the number of operating units.

  According to this configuration, it is possible to determine the number of operating rectifier units so that the rectifier units in the operating state have a current close to the rated current.

Each of the plurality of rectifier units is
A switch that is connected to the AC power source and that is closed when the operation command is received from the command unit;
It is good also as having an AC / DC converter arrange | positioned in the back | latter stage of the said switch, and converting the alternating current power from the said alternating current power source into direct-current power when the said switch becomes a closed state.

  According to this configuration, the rectifier unit that has received the operation command can be controlled to the operation state by the switch operation.

  As described above, according to the DC power supply system of the present invention, the optimum number of rectifier units to be operated is determined based on the total output current of the rectifier, and the rectifier units for the determined number of operations are operated. Yes.

  In this way, by reducing the number of operating rectifier units, it is possible to maintain a high load factor for the rectifier units in the operating state, thereby reducing the power loss due to the reduced efficiency of the rectifier units. Is obtained.

  In addition, by operating the optimal number of rectifier units and waiting for the other rectifier units to operate, it is possible to avoid energizing the rectifier units in the no-load state, thus reducing the no-load loss. The effect of being able to be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration example of a DC power supply system according to a first embodiment of the present invention, and illustrates a configuration when power is supplied to a large number of communication devices.

Referring to FIG. 1, the DC power supply system according to the present embodiment is different from the conventional example shown in FIG. 7 in that an operating number determination circuit 51 is provided in the monitoring control unit 5 and the rectifier units 4 ₁ to 4. _{The difference} is that an AC / DC converter 41 and a control circuit 42 are provided in _n .

In the present embodiment, the operating number determination circuit 51 detects the total output current of the rectifier 3 and compares the total output current with the efficiency curve data of each of the rectifier units 4 ₁ to 4 _n to optimize the rectifier unit. Determine the number of units to be operated, and issue operation commands to the rectifier units for the optimum number of units to be operated.

In each of the rectifier units 4 ₁ to 4 _n , the control circuit 42 outputs an operation signal to the AC / DC converter 41 when receiving an operation command from the operation number determination circuit 51. The AC / DC converter 41 converts AC power from the commercial power source 1 or the engine generator 2 into DC power when an operation signal from the control circuit 42 is input.

  FIG. 2 is a functional block diagram showing the configuration of the operating number determination circuit 51.

  Referring to FIG. 2, the operation number determination circuit 51 includes an operation number storage unit 511, an efficiency curve data storage unit 512, an output detection unit 513, an optimum operation number determination unit 514, an ON / OFF command unit 515, have.

The operating number storage unit 511 stores the current operating number M (M = 1, 2,..., N) of the rectifier units 4 ₁ to 4 _n .

The efficiency curve data storage unit 512 stores the efficiency curve data f (m) of the rectifier units 4 ₁ to 4 _n . The efficiency curve data f (m) is a mathematical expression representing a current-efficiency characteristic that becomes an efficiency curve as shown in FIG. The rectifier units 4 ₁ to 4 _n are the same rectifier unit, and the efficiency curve data is also the same.

  The output detection unit 513 detects the total output current Iall of the rectifier 3.

Optimal operation number determination unit 514, the current total output current Iall of rectifier 3, the rectifier unit ₄₁ to the current operating number M of _n, and each rectifier unit 4 ₁ to 4 _n the efficiency curve data f ( The optimum operation number m of the rectifier unit is determined by comparing and calculating m).

The ON / OFF command unit 515 transmits an operation signal serving as an operation command to the rectifier units for the number m of operation units determined by the optimum operation number determination unit 514 among the rectifier units 4 ₁ to 4 _n and operates. Transition to. Further, a standby signal is transmitted to the other rectifier units. For example, the operation / standby of the rectifier units 4 ₁ to 4 _n can be operated from a rectifier unit with a small mounting number and can be standby from a rectifier unit with a large mounting number.

  FIG. 3 is a flowchart for explaining the operation flow of the optimum operation number determining unit 514.

Optimal operation number determination unit 514, as follows, current total output current Iall of the rectifier device 3, the current number of operating units M, and each rectifier unit 4 ₁ to 4 _n of the rectifier unit 4 ₁ to 4 _n The optimum operation number m of the rectifier units is calculated by comparing and calculating the efficiency curve data f (m).

Referring to FIG. 3, the optimum operation number determination unit 514 first inputs the current operation number M to the operation number m in step 301. Next, in step 302, the current total output current Iall is divided by the number m of operating units to obtain an output current value per rectifier unit, and the output current value is substituted into the efficiency curve data f (m) to rectifier. Calculate unit efficiency η _m . Next, in step 303, similarly, the efficiency η _m-1 of the rectifier unit in the case of the operating number _m-1 is calculated. Next, in step 304, the efficiency η _m for the operating number m is compared with the efficiency η _m-1 for the operating number m-1. If η _m-1 is larger, the number of operating units is changed to m-1 in step 305, and if η _m is larger, the number of operating units is not changed in step 306 and remains m units. . The operating number m obtained in steps 305 and 306 is notified to the ON / OFF command unit 515.

In step 307, the ON / OFF command unit 515 operates the rectifier unit obtained by adding one redundant portion to the operating unit number m notified from the optimum operating unit determining unit 514, for example, the rectifier units 4 ₁ to 4 _{m + 1.} A signal is transmitted, and a standby signal is transmitted after the rectifier unit 4 _{m + 2} . Thereby, the optimal number of operating rectifier units is maintained.

  The above-described flow is repeated, and the optimum operation number determination unit 514 always notifies the ON / OFF command unit 515 of the optimum operation number m.

(Second Embodiment)
FIG. 4 is a diagram illustrating a configuration example of a DC power supply system according to the second embodiment of the present invention, and illustrates a configuration when power is supplied to a large number of communication devices.

Referring to FIG. 4, the direct current power supply system according to the present embodiment is different from the conventional example shown in FIG. 7 in that an operating number determination circuit 52 is provided in the supervisory control unit 5 and the rectifier units 4 ₁ to 4. _{The difference} is that an AC / DC converter 43 and a switch 44 are provided in _n .

In the present embodiment, the operating number determination circuit 52 detects the total output current of the rectifier 3 and compares the total output current with the rated currents of the rectifier units 4 ₁ to 4 _n , thereby optimizing the rectifier unit. Determine the number of units to be operated and issue an operation command to the rectifier units for the optimal number of units to be operated.

In each of the rectifier units 4 ₁ to 4 _n , the switch 44 is connected to the commercial power source 1 and the engine generator 2, and is closed when an operation command is received from the operation number determination circuit 51. The AC / DC converter 43 converts AC power from the commercial power source 1 or the engine generator 2 into DC power when the switch 44 is closed.

  FIG. 5 is a functional block diagram showing the configuration of the operating number determination circuit 52.

  Referring to FIG. 5, the operating number determination circuit 52 includes an operating number storage unit 521, an output detection unit 522, an optimum operating number determination unit 523, and an ON / OFF command unit 524.

The operating number storage unit 521 stores the current operating number M (M = 1, 2,..., N) of the rectifier units 4 ₁ to 4 _n .

  The output detection unit 522 detects the current total output current Iall of the rectifier 3.

The optimum operation number determination unit 523 compares the current total output current Iall of the rectifier 3 and the predetermined rated current Ir of each of the rectifier units 4 ₁ to 4 _n , thereby calculating the optimum operation number of the rectifier units. Determine m.

The ON / OFF command unit 524 transmits an operation signal serving as an operation command to the rectifier units corresponding to the number m of operation units determined by the optimum operation number determination unit 514 among the rectifier units 4 ₁ to 4 _n , thereby operating the operation state. Transition to. Further, a standby signal is transmitted to the other rectifier units. For example, the operation / standby of the rectifier units 4 ₁ to 4 _n can be operated from a rectifier unit with a small mounting number and can be standby from a rectifier unit with a large mounting number.

  FIG. 6 is a flowchart for explaining the operation flow of the optimum operation number determining unit 523.

The optimum operation number determination unit 523 compares the current total output current Iall of the rectifier 3 and the predetermined rated current Ir of each of the rectifier units 4 ₁ to 4 _n in the following manner, thereby calculating the rectifier. Calculate the optimal number m of units to operate.

Referring to FIG. 6, the optimum operation number determination unit 523 first inputs 1 to the operation number m in Step 601, and then changes the operation number to m + 1 in Step 602. Next, in step 603, the current total output current Iall is compared with (m−1) ^* Ir. For example, when the initial operating number m is 1, if the total output current Iall is smaller than Ir (= (2-1) ^* Ir), the operating number m is determined to be 2 in step 604. On the other hand, if the total output current Iall is larger than Ir, the process returns to step 602 to add 1 to the number of operating units m to 3 and thereafter repeat this calculation. The operating number m obtained in step 604 is notified to the ON / OFF command unit 524. Thereby, the optimum operation number determining unit 523 always notifies the ON / OFF command unit 524 of the optimum operation number m.

In step 605, the ON / OFF command unit 524 transmits an operation signal to the rectifier units of the operating number m notified from the optimum operating number determining unit 523, for example, the rectifier units 4 ₁ to 4 _m , and the rectifier unit 4 _{m. A} standby signal is transmitted after ₊₁ . Thereby, the optimal number of operating rectifier units is maintained.

As described above, in the first and second embodiments, the optimum operating number of the rectifier units 4 ₁ to 4 _n is determined based on the total output current of the rectifying device 3 and the determined operating number. The rectifier unit of the minute is operated.

  In this way, by reducing the number of operating rectifier units, the rectifier units in the operating state can be maintained at a high load factor. Therefore, the power loss of the rectifier 3 due to the efficiency reduction of the rectifier unit and the rectifier 3 And the power loss of the power receiving cable between the communication device group 7 can be reduced.

  In addition, by operating the optimal number of rectifier units and waiting for the other rectifier units to operate, it is possible to avoid energizing the rectifier units in the no-load state, thus reducing the no-load loss. Can do.

  Moreover, since the power loss is reduced, the number of air conditioners and the running cost for cooling the heat generated by the power loss can also be reduced.

  Moreover, since the storage battery 6 is connected to the output terminal of the rectifier 3, the calculation cycle of the operation flow may be calculated in units of several minutes, and high-speed calculation is not required.

It is a figure which shows the structure of the DC power supply system of the 1st Embodiment of this invention. It is a functional block diagram which shows the structure of the operation number determination circuit shown in FIG. It is a flowchart explaining the operation | movement flow of the optimal driving | operation number determination part shown in FIG. It is a figure which shows the structure of the DC power supply system of the 2nd Embodiment of this invention. It is a functional block diagram which shows the structure of the operating number determination circuit shown in FIG. It is a flowchart explaining the operation | movement flow of the optimal driving | operation number determination part shown in FIG. It is a figure which shows the example of 1 structure of the conventional DC power supply system. It is a figure explaining the current-efficiency characteristic and current-loss characteristic of a rectifier unit.

Explanation of symbols

1 commercial power source 2 engine generator 3 rectifier 4 ₁ to 4 _n rectifier unit 5 monitoring controller 6 battery 7 communication device group 41 AC / DC converter 42 control circuit 43 AC / DC converter 44 switches 51 the number of operating units determining circuit 511 operation number Storage unit 512 Efficiency curve data storage unit 513 Output detection unit 514 Optimal operation number determination unit 515 ON / OFF command unit 52 Operation number determination circuit 521 Operation number storage unit 522 Output detection unit 523 Optimal operation number determination unit 524 ON / OFF command unit

Claims (8)

A rectifier including a plurality of rectifier units connected in parallel to each other, each of which converts AC power from an AC power source into DC power;
An output detector for detecting the total output current of the rectifier;
Based on the total output current of the rectifier detected by the output detector, an optimum operating number determination unit that determines the number of operating rectifier units;
A direct-current power supply system comprising: a command unit that outputs an operation command to the rectifier units for the number of operating units determined by the optimum operating number determining unit among the plurality of rectifier units. An efficiency curve data storage unit for storing efficiency curve data representing current-efficiency characteristics of each of the plurality of rectifier units;
The optimum operation number determining unit is configured to determine a current total output current of the rectifier detected by the output detection unit and efficiency curve data of each of the plurality of rectifier units stored in the efficiency curve data storage unit. The DC power supply system according to claim 1, wherein the number of operating rectifier units is determined by comparing the rectifier unit with each other.   The optimum operation number determination unit compares the current total output current of the rectifier detected by the output detection unit with the rated current of each of the plurality of rectifier units, thereby determining the rectifier unit. The DC power feeding system according to claim 1, wherein the number of operating units is determined. Each of the plurality of rectifier units is
A switch that is connected to the AC power source and that is closed when the operation command is received from the command unit;
The AC / DC converter which is arrange | positioned in the back | latter stage of the said switch, and converts the alternating current power from the said alternating current power source into direct-current power when the said switch becomes a closed state, The any one of Claim 1 to 3 The direct current power supply system according to item. A method for controlling a DC power supply system including a rectifier including a plurality of rectifier units connected in parallel to each other, each of which converts AC power from an AC power source into DC power,
A detection step of detecting a total output current of the rectifier;
A determination step of determining the number of operating rectifier units based on the detected total output current of the rectifier;
And a command step of outputting an operation command to the determined number of rectifier units among the plurality of rectifier units. Storing efficiency curve data representing current-efficiency characteristics of each of the plurality of rectifier units;
In the determining step, by comparing the detected current total output current of the rectifier and the stored efficiency curve data of the plurality of rectifier units, the number of operating rectifier units is determined. The control method according to claim 5, wherein the control method is determined.   The determining step determines the number of operating rectifier units by comparing a current total output current of the detected rectifier with a rated current of each of the plurality of rectifier units. 5. The control method according to 5.   The control method according to any one of claims 5 to 7, further comprising a step of setting the rectifier unit that has received the operation command to an operation state by a switch operation.

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