JP2012210029A - Dc power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply capable of supplying a current which is a nominal value or larger during a normal operation at the time of startup, with a specification that is required for the normal operation used as it is.SOLUTION: In the DC power supply, a DC power supply unit and a charge/standby unit (CH-U) perform a pendant operation for pending an output voltage to increase an output current at the time of startup. Then, in the case where such condition occurs as the pendant voltage cannot be restored to the output voltage (nominal voltage) in normal operation, a relay contact point Rya is caused to be conductive, and a relay contact point Ryb is caused to be non-conductive. In other words, an output terminal of the charge/standby unit (CH-U) is directly connected to a load wiring (DCL1). Consequently, an output current of the charge/standby unit (CH-U) is caused to flow directly to the load wiring (DCL1), and further, by causing the load wiring (DCL1) and a storage battery to be non-conductive, the load is isolated from the storage battery, for raising a load voltage.

Description

  The present invention relates to a DC power supply device.

  Some DC power supply apparatuses are provided with a plurality of DC power supply units to constitute a DC power supply apparatus of a parallel redundant operation system. In this type of DC power supply, even if one power supply unit fails, the spare DC power supply unit is activated so as not to affect the operation of the load system.

  FIG. 24 is a diagram illustrating an example of a DC power supply of a parallel redundant operation method. The DC power supply device 101B shown in this figure is equipped with N DC power supply units (RF-U) and one charging / spare unit (CH-U). Each of N and the charge / spare unit (CH-U) is a DC power supply device that converts an input AC voltage (AC input) into a DC voltage and supplies DC power to the load RL. Each DC power supply unit (RF-U) and charging / standby unit (CH-U) are connected to the primary side of the output transformer in response to the difference between the output voltage and the output voltage reference signal. The DC / DC converter circuit controls the ON width of the switching element (see FIG. 5).

In the normal operation, the DC power supply device 101B shown in this figure operates n DC power supply units (RF-U) 1 to N to supply power to the load RL. In the event of a failure, the charging / spare unit (CH-U) is used as a replacement unit for the failed unit. In addition, the DC power supply device 101B includes a power storage device 60 including a storage battery 61 so that the supply of power to the load RL can be continued even in the event of a power failure. When AC input is lost due to a power failure, power is supplied from the storage battery 61 to the load RL through the diode DX1.
In the DC power supply device 101B, the charging / spare unit (CH-U) is used as a spare power supply unit and also serves as a charger for the storage battery 61.

  There are related DC / DC converters and DC power supply systems (see Patent Document 1). The DC / DC converter described in Patent Document 1 provides a DC / DC converter that determines a power supply unit failure when the output voltage of the DC / DC converter falls below the rated voltage except in the case of drooping. It is aimed.

JP 2010-88254 A

  In the DC power supply device 101B of the parallel redundant operation method shown in FIG. 24, each of the DC power supply units (RF-U) 1 to N and the charging / spare unit (CH-U) generally includes an overcurrent protection circuit (output current limiter). Circuit). When the overcurrent state of the load is detected by a current detector or the like, this overcurrent protection circuit performs a so-called constant current drooping operation that reduces the output voltage and limits overcurrent. For example, as shown in FIG. 2B, when an overcurrent flows through the load, the output voltage (load voltage VL) is reduced so that a current higher than the rated current Imax0 does not flow. As described above, each of the DC power supply units (RF-U) 1 to N and the charge / spare unit (CH-U) has a constant current drooping characteristic.

By the way, when driving a load RL such as an inverter having constant power characteristics (for example, an inverter that converts a DC voltage into an AC voltage) by the DC power supply device shown in FIG. 24, during the discharge of the storage battery 61 at the time of an input power failure. When power is restored, the constant current drooping characteristic may become a problem.
That is, when power is supplied from the storage battery 61 to the load RL having constant power characteristics, the voltage of the storage battery 61 gradually decreases due to the discharge, so that the current flowing through the load RL increases and exceeds the rated current Imax0 of each DC power supply unit. Current may flow. When power is restored in a state where a current of the rated current Imax0 or more is flowing through the load RL, the DC power supply unit is activated and continues to supply current to the load RL as it is. A constant current drooping operation for restriction is performed, and the output current is limited to the rated current Imax0. For this reason, the supply current to the load RL becomes insufficient, and the DC power supply unit cannot be restored to the rated voltage.

  For example, as a specific example, the number n of DC power supply units is 7, the rated output voltage is 383 V, and the load is gradually discharged in the case of an inverter having a constant power characteristic with a load of 100 KW. When the power is restored from an input power failure before 270V, the required current to flow through the load RL is 370.4 A (≈100 kW / 270 V). That is, immediately after the input power is restored, it is necessary to supply a current of 52.9 A (≈370.4 A / 7) from each DC power supply unit to the load RL.

  However, the rated output power of each unit is “100 KW / 7”, and the rated output voltage is 383 V. Therefore, the rated current is 37.3 A (≈100 kW / (383 V × 7)), and each DC power supply unit has a constant current drooping characteristic with a current limit value (37.3 A) as its overcurrent protection function. Designed. Therefore, when the DC power supply unit is restored, the overcurrent protection function (constant current drooping characteristic) is activated as the output voltage rises, and the output current is limited to the rated current (37.3 A) (output voltage). Will continue to be lowered), and there will be a situation where the rated output voltage (383 V) cannot be restored.

  In order to solve this problem, conventionally, there is a method of giving each DC power supply unit a constant power drooping characteristic. That is, it is a method of providing a function of changing the output voltage according to the magnitude of the load current. For example, in the above-described example, when a current of 52.9 A (≈370.4 A / 7) is supplied from the DC power supply unit to the load, the output voltage is controlled to be 270 V, and then the output voltage is gradually increased. Increase (at the same time decrease the output current).

  However, in the conventional method described above, the DC power supply unit needs to have a constant power drooping characteristic, and a unit for constant power drooping is designed in consideration of the fact that the constant power drooping operation occurs continuously. There must be. As a result, the current flowing during the constant power drooping operation increases, so that it is necessary to select a switching element (such as a switching transistor) having a current capacity corresponding to this (upsizing of the switching transistor or the like). In addition, a thermal design corresponding to the increase in drooping current is required. For example, it is necessary to make the winding of the output transformer thicker, and it is necessary to have a heat dissipation design (enlargement of heat sink and cooling fan) corresponding to an increase in heat loss of the switching transistor. For this reason, the dimension of a DC power supply unit increases and the problem that manufacturing cost also arises arises.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to maintain specifications (for example, selection of switching elements and thermal design specifications) required during normal operation, at the time of startup, etc. , A DC power supply that can supply a current that exceeds the rated current during normal operation to the load, and that can reliably start up the output voltage drooped by the drooping operation to the output voltage (rated voltage) during normal operation To provide an apparatus.

  The present invention has been made to solve the above problems, and the direct-current power supply device of the present invention performs a constant current drooping operation for limiting the output current to a predetermined value, and a current greater than the predetermined value in a load. When there is a need to output a plurality of DC power supply units that perform a drooping operation that causes the output voltage to drop to increase the output current, and when no input power is supplied to the DC power supply unit, power is supplied to the load. A storage battery that supplies the storage battery when one of the DC power supply units fails and is used as a substitute unit for the failed DC power supply unit, and during normal operation, A first power line for commonly connecting the output terminals of the DC power supply units and supplying power to the load; and A switching unit that switches between current conduction or non-conduction between a second power supply line connected to the power terminal and a third power supply line connected to the output terminal of the storage battery, and operation of the DC power supply unit And a monitoring unit that controls the switching unit, and when the DC power supply unit performs the drooping operation, the monitoring unit controls the switching unit to control the first power line. And the second power supply line are made conductive, and the first and second power supply lines and the third power supply line are made nonconductive.

  In the DC power supply device of the present invention, the load is a load having a constant power characteristic, and the DC power supply unit and the charging / spare unit are connected to the load at start-up and when a predetermined instruction is given. When it is necessary to supply a current greater than or equal to the predetermined value, a constant power drooping operation is performed to droop the output voltage so that the product of the output current and the output voltage is constant, and the current greater than or equal to the predetermined value is It is characterized by supplying a load.

  Further, in the DC power supply device according to the present invention, the monitoring unit controls the switching unit when at least one DC power supply unit fails, so that the first power line and the second power line are connected. The first and second power supply lines and the third power supply line are made nonconductive.

  In the DC power supply device of the present invention, the monitoring unit detects a load voltage of the load and a load current flowing through the load, and operates the load voltage, the load current, and the DC power supply unit. If the DC power supply unit that performs the drooping operation can restore the drooping output voltage to the output voltage during normal operation based on the state, and determines that the drooping operation cannot be restored, the switching unit is Controlling to make the first power supply line and the second power supply line conductive and to make the first and second power supply lines and the third power supply line nonconductive. Features.

  Further, in the DC power supply device of the present invention, the determination as to whether or not the DC power supply unit performed in the monitoring unit can restore the drooped output voltage to the output voltage at the time of normal operation is performed at the time of startup after power recovery. It is executed at any or all timings when a faulty unit occurs in the DC power supply unit or when a predetermined instruction is given.

  The DC power supply device of the present invention is characterized in that the rated output voltage of the charging / spare unit is set lower by a predetermined voltage than the rated output voltage of the DC power supply unit.

  Further, in the DC power supply device according to the present invention, the monitoring unit controls the switching unit to establish conduction between the first power supply line and the second power supply line, and the first and second power supply lines. When it is detected that the output current of the charging / spare unit has become 0 after non-conduction between the power supply line and the third power supply line, the first power supply line and the second power supply line are detected. The power supply line is made non-conductive, and the second power supply line and the third power supply line are made conductive.

  Further, in the DC power supply device according to the present invention, the switching unit includes a diode whose anode side is connected to the storage battery via the third power line, and whose cathode side is connected to the first power line, A first switching element that switches between the first power supply line and the second power supply line between conduction and non-conduction; and a second switching element that switches between the second power supply line and the third power supply line between conduction and non-conduction. And a switching element.

  Further, in the DC power supply device of the present invention, the monitoring unit detects a load voltage VL and a load current IL of the load to calculate a load power PL (= VL × IL), and each DC power supply unit Among them, a first procedure for detecting the number n of normally operating units, a maximum rated current Imax1 in the constant power drooping operation of the DC power supply unit and the charging / spare unit, and the maximum rated current Imax1 flow. A second procedure for determining whether or not the load voltage VL satisfies the condition of VL ≧ Vcp based on the constant power droop voltage Vcp at the time and the rated current Imax0 in the constant current drooping operation; In the procedure of 2, when it is determined that the load voltage VL is equal to or higher than the constant power droop voltage Vcp (VL ≧ Vcp), the load power PL is PL <Vcp × Imax1 × n. When the load voltage VL is determined to be less than the constant power droop voltage Vcp (VL <Vcp) in the third procedure for determining whether or not the above condition is satisfied and the second procedure, the load power PL Is determined to satisfy the condition “PL> Vcp × Imax1 × n” in the fourth procedure and the third procedure in which it is determined whether or not the condition PL <VL × Imax1 × n is satisfied Or in the fourth procedure, when it is determined that the condition “PL> VL × Imax1 × n” is satisfied, the first power supply is controlled by the first switching element by controlling the switching unit. A fifth step of making the line electrically conductive between the second power line and making the second switching element non-conductive between the second power line and the third power line. Characterized by performing To.

  In the DC power supply device of the present invention, when the monitoring unit determines that the condition of “PL <Vcp × Imax1 × n” is satisfied in the third procedure, or “PL < VL × Imax1 × n ”, and when one of the DC power supply units has failed, PL / PL is determined based on the voltage Vobat when the discharge of the storage battery is stopped. A sixth procedure for determining whether or not a condition of Vobat <Imax0 × n ′ (where n ′ is a total number of normally operating DC power supply units and charging / spare units) is satisfied; When it is determined by the sixth procedure that the condition of “PL / Vobat> Imax0 × n ′” is satisfied, the first power supply line and the second power supply are detected by the first switching element. And a seventh step of performing conduction between the second power supply line and the third power supply line by the second switching element. .

In the direct current power supply device of the present invention, by giving a constant power drooping characteristic, a current of a predetermined value or more (for example, a current of a rated current or more during normal operation) can be temporarily passed through the load. Further, when the DC power supply unit performs a drooping operation, the monitoring unit controls the switching unit to establish conduction between the first power supply line and the second power supply line, and the first and second power supply lines and the third power supply line. No electrical connection to the power line. That is, the monitoring unit directly connects the charge / spare unit and the load, and disconnects the storage battery from the charge / spare unit and the load.
As a result, the current more than the rated current during normal operation is supplied to the load during startup, etc. while maintaining the specifications required during normal operation (for example, switching element selection and thermal design specifications). In addition, the output voltage drooped by the drooping operation can be reliably raised to the output voltage (rated voltage) during normal operation.

It is a block diagram which shows the structure of the direct-current power supply unit concerning 1st Embodiment. It is a figure for demonstrating a constant power drooping characteristic and a constant current drooping characteristic. It is a figure which shows the structure of a drooping reference signal generation part. It is a figure which shows a starting operation sequence. It is a figure which shows the structure of a DC / DC converter circuit. It is a figure which shows operation | movement of a DC / DC converter circuit. It is a figure which shows the image of a drooping reference | standard. It is a block diagram which shows the structure of the DC power supply device concerning 1st Embodiment. It is a block diagram which shows the structure of the DC power supply device concerning 2nd Embodiment. It is a figure which shows the structural example of a switching part. It is a figure for demonstrating operation | movement of the DC power supply device of 2nd Embodiment. It is a flowchart which shows the flow of a process in the direct-current power supply device of 2nd Embodiment. It is a 1st time chart which shows starting operation of a direct-current power supply device. It is a 2nd time chart which shows starting operation | movement of a DC power supply device. It is a block diagram which shows the example of another structure of the switch part shown to FIG. 10 (B). It is a block diagram which shows the other structural example of the switching part. It is a figure for demonstrating the drooping characteristic of a DC power supply unit. It is a figure for demonstrating the power recovery operation | movement at the time of normal. It is a figure which shows the 1st example of the power recovery operation at the time of one DC power supply unit failure. It is a figure which shows the 2nd example of the power recovery operation at the time of one DC power supply unit failure. It is a time chart which shows the starting operation at the time of power recovery (normal time). It is a time chart which shows the starting operation at the time of power recovery (at the time of abnormality). It is a time chart which shows the starting operation at the time of power recovery at the time of unit failure. It is a figure which shows the example of the DC power supply device of a parallel redundant operation system.

[First Embodiment]
(Description of the configuration of the DC power supply unit)
FIG. 1 is a block diagram showing a configuration of a DC power supply unit 10 provided in the DC power supply apparatus 101 according to the first embodiment. The DC power supply unit 10 shown in this figure is a DC power supply unit 10 that can be suitably used when power is supplied to a load RL having constant power characteristics in conjunction with the power storage device 60. That is, the DC power supply device 101 supplies power to the load RL from the storage battery 61 in the power storage device 60 in the event of a power failure, and supplies power to the load RL from the DC power supply unit 10 after power recovery. . Note that a load having a constant power characteristic is a load having a characteristic that power consumption of the load is constant regardless of a change in voltage (for example, an inverter that converts a DC voltage into an AC voltage).

  The DC power supply unit 10 includes a power factor correction circuit (PFC) 20 on the AC input side, and a DC / DC converter circuit 50 is connected to the output side thereof. The power factor correction circuit 20 serves as a DC power source E for the DC / DC converter circuit 50. The power factor improving circuit 20 rectifies an AC voltage by a rectifier circuit, and controls switching of an internal switching element (not shown) to bring the AC voltage waveform and current waveform close to improve the power factor. Circuit. The operation of the power factor correction circuit 20 is controlled by the PFC control unit 30. Note that the configuration and operation of the power factor correction circuit 20 are well known and are not directly related to the present invention, and thus description thereof is omitted.

Further, the DC power supply unit 10 includes a D / D control circuit 40 that controls the operation of the DC / DC converter circuit 50. The D / D control circuit 40 includes a D / D controller 41 that outputs a control signal for controlling the operation of the DC / DC converter circuit 50, a drooping operation that indicates a constant power drooping characteristic that will be described later, and a constant current drooping characteristic. And a drooping reference signal generation unit 42 that generates a reference signal used when performing a drooping operation.
The D / D control circuit 40 is configured using a microcontroller, microcomputer, or the like having a CPU, ROM, RAM, etc. (A / D converter, D / A converter, counter, etc. if desired). The same applies to the PFC control unit 30. Further, the PFC control unit 30 may be included in the D / D control circuit 40. The D / D control circuit 40 and the PFC control unit 30 may be realized by dedicated hardware.

  The DC power supply unit 10 shown in FIG. 1 is a DC power supply unit having a so-called constant current drooping characteristic that droops the output voltage Vo when the output current exceeds the rated current Imax0 for overcurrent protection during normal operation. Yes (see FIG. 2B).

  In addition to the constant current drooping characteristic, the DC power supply unit 10 has a constant power drooping characteristic that operates only temporarily at startup. In the DC power supply unit 10, when power supplied from the input power supply (AC input) is interrupted due to a power failure and then activated by power recovery, it is necessary to supply a current equal to or higher than the rated current Imax0 to the load RL. In addition, a constant power drooping operation is temporarily performed. In this constant power drooping operation, when a current greater than the rated current Imax0 is supplied from the DC power supply unit 10 to the load RL, the output voltage is drooped so that the product of the output current Io and the output voltage Vo is constant, A current is supplied to the load RL.

(Explanation of constant power droop characteristics and constant current droop characteristics)
Here, the constant power drooping characteristic and the constant current drooping characteristic of the DC power supply unit 10 shown in FIG. 1 will be supplementarily described. FIG. 2 is a diagram for explaining the constant power drooping characteristic and the constant current drooping characteristic. In FIG. 2A, the horizontal axis represents the output current Io and the vertical axis represents the output voltage Vo, and the constant power drooping characteristic is shown. Similarly, FIG. 2B shows constant current drooping characteristics. As described above, the constant power drooping operation is a current having a constant power characteristic equal to or higher than the rated current Imax0 (the rated current during the normal operation of the DC power supply unit 10) at the time of power recovery after a power failure. This is a drooping operation performed when the current Ia shown in FIG. On the other hand, the constant current drooping operation is a drooping operation performed in order to limit the output current Io to the rated current Imax0 in order to limit overcurrent during the normal operation of the DC power supply unit 10.

  As shown in FIG. 2A, in the constant power drooping operation, the DC power supply unit 10 is configured to output the output voltage Vo and the output current Io when a current (for example, a current Ia) of the rated current Imax0 or more flows through the load RL. The output voltage Vo is drooped so that the product of becomes constant (for example, rated output capacity). Note that if the output current Io becomes too large, it exceeds a rated current capacity (for example, a maximum current value in a short-time rating) of a switching element Q1 (see FIG. 5) to be described later. The current is limited by the current Imax1.

  The constant power drooping operation in the DC power supply unit 10 described above is a drooping operation that is temporarily performed when the DC power supply unit 10 is activated at the time of power recovery. For example, this constant power drooping operation is performed when the current flowing through the load RL is equal to or higher than the rated current Imax0 shown in FIG. In the case of Ia). This is because if the DC power supply unit 10 performs a constant current drooping operation shown in FIG. 2B when the DC power supply unit 10 is restored and started, the output current is limited to the rated current Imax0, and the current Ia necessary for the load RL is reduced. This is because the supply voltage cannot be supplied and the output voltage Vo of the DC power supply unit 10 cannot rise to the required rated voltage. In order to avoid this situation, the DC power supply unit 10 temporarily performs a constant power drooping operation when starting up at the time of power recovery.

  Returning to FIG. 1 again, the D / D controller 41 outputs an output voltage reference signal Vref for controlling the voltage level of the output voltage Vo of the DC / DC converter circuit 50 to the DC / DC converter circuit 50. Is done. The DC / DC converter circuit 50 controls the voltage level of the output voltage Vo to be constant based on the output voltage reference signal Vref input from the D / D controller 41.

  Further, the signal I_KIND is output from the D / D controller 41 to the drooping reference signal generator 42 as a distinction signal between the constant power droop / constant current droop. Further, the D / D controller 41 outputs a voltage signal Iref_M for generating a reference signal having a constant power drooping characteristic to the drooping reference signal generator 42. The D / D controller 41 sets the signal I_KIND to the high level (I_KIND = 1) when the constant power is drooping, and sets the signal I_KIND to the low level (I_KIND = 0) when the constant current droops. These signals I_KIND and Iref_M are input signals to the drooping reference signal generator 42. The drooping reference signal generation unit 42 generates a secondary droop reference signal Iref2 and a primary droop reference signal Iref1 based on the signal I_KIND and the signal Iref_M input from the D / D controller 41, and supplies them to the DC / DC converter circuit 50. Output.

(Description of the drooping reference signal generation unit 42)
FIG. 3 is a diagram illustrating a configuration of the drooping reference signal generation unit 42. This drooping reference signal generation unit 42 generates a signal I_KIND input circuit shown in FIG. 3A and a second drooping reference signal Iref2 for performing a constant power drooping operation shown in FIG. 3B. A second droop reference generation circuit and a first droop reference generation circuit for generating a primary droop reference signal Iref1 for limiting the maximum output current (instantaneous overcurrent value) shown in FIG. Note that specific usage examples of the primary droop reference signal Iref1 and the secondary droop reference signal Iref2 will be described together with the description of the DC / DC converter circuit 50 shown in FIG.

  The input circuit for the signal I_KIND shown in FIG. 3A is configured by connecting a primary side PR_A of a photoMOS relay and a primary side PC_A of a photocoupler to a resistor R101 in series, and one terminal A of the resistor R101. To the signal I_KIND. With this configuration, when the constant power is drooped (the signal I_KIND is at a high level (I_KIND = 1)), the primary side PR_A of the photoMOS relay and the primary side PC_A of the photocoupler are turned on (light emitting element emits light).

The secondary droop reference generation circuit shown in FIG. 3B includes a secondary droop reference voltage signal Iref_M output from the D / D controller 41, and a negative signal (output voltage (−)) of the output voltage Vo. Thus, a circuit for generating the secondary droop reference signal Iref2.
The secondary droop reference generation circuit amplifies the voltage signal Iref_M output from the D / D controller 41 by the voltage amplifier 71. The voltage level of the voltage signal Iref_M is switched depending on whether the DC power supply unit 10 performs a constant power drooping operation or a normal operation (constant current drooping operation). That is, the voltage level Iref_M2 when performing the constant power drooping operation is set to be higher than the voltage level Iref_M1 when performing the normal operation (constant current drooping operation) (Iref_M2> Iref_M1) (see FIG. 4). ). As a result, the DC power supply unit 10 can flow an output current equal to or higher than the rated current Imax0 during normal operation to the load RL during the constant power drooping operation.

  In addition, a series circuit of a resistor R102 and a resistor R103 is connected between the output side of the voltage amplifier 71 and the ground G. The resistor R102 and the resistor R103 constitute a resistor voltage dividing circuit, and a secondary droop reference signal Iref2 is output from a connection point (resistance voltage dividing point) A between the resistor R102 and the resistor R103. Further, the anode side of the diode D101 is connected to the connection point A, and the resistors R111 and R112 and the secondary side PR_B of the photo MOS relay are connected in series to the cathode side of the diode D101. Further, a negative signal (output voltage (−)) of the output voltage Vo is input to one end of the secondary side PR_B of the photo MOS relay (terminal opposite to the terminal to which the resistor R112 is connected). The negative signal (output voltage (−)) of the output voltage Vo is a negative polarity (−) signal, and the voltage level decreases as the output voltage Vo increases.

  With the configuration of the secondary droop reference generation circuit shown in FIG. 3B described above, during normal operation, the secondary side PR_B of the photo moss relay is turned off, and the secondary droop reference signal Iref2 is a constant current droop operation. A signal having a constant value (for example, Iref2 ′) generated by the voltage amplifier 71 and the resistors R102 and R103 based on the voltage signal Iref_M1 output from the D / D controller 41 at times. The constant value signal Iref2 ′ can be set to a desired value by changing the voltage level of the signal Iref_M1.

  On the other hand, the secondary side PR_B of the photo MOS relay is turned ON during the constant power drooping operation, and the voltage level of the secondary droop reference signal Iref2 is the voltage level of the signal Iref_M2 output from the D / D controller 41 during the constant power drooping operation. And the output voltage Vo. That is, the signal Iref_M2 is amplified by the voltage amplifying unit 71 and is output to the connection point A of the resistors R102 and R103. The connection point A includes the diode D101, the resistor R111, the resistor R112, and the photoMOS relay. A negative signal (output voltage (−)) of the output voltage Vo is input via the secondary side PR_B. For this reason, the voltage at the connection point A (secondary droop reference signal Iref2) changes linearly (linearly) with the change in the output voltage Vo, and becomes a signal for causing the constant power drooping operation.

For example, in a state where the voltage level of the output voltage Vo is low, the voltage level of the secondary droop reference signal Iref2 increases, and the voltage level of the secondary droop reference signal Iref2 decreases as the voltage level of the output voltage Vo increases. Thereby, the secondary drooping reference signal Iref2 for realizing the constant power drooping characteristic (characteristic that the output voltage Vo × the output current becomes constant) is generated.
Note that the maximum current that can flow in the constant power drooping operation can be set to a desired value by changing the voltage level of the signal Iref_M2. Further, the slope of the constant power drooping characteristic (the ratio of the change in the output voltage Vo to the change in the output current Io) can be set by the resistance values of the resistors R102, R103, R111, and R112.

  In the primary droop reference generation circuit shown in FIG. 3C, a resistor R121 and a Zener diode ZD1 are connected in series between a circuit power supply terminal (+ 15V) and the ground G (the anode of the Zener diode ZD1 is grounded). G). As a result, a predetermined constant voltage Vz is generated at the connection point A between the resistor R121 and the Zener diode ZD1. A series circuit of a resistor R122, a resistor R123, and a resistor R124 is connected between the terminals of the Zener diode ZD1, and a resistance voltage dividing circuit is formed for the constant voltage Vz generated by the Zener diode ZD1. A primary droop reference signal Iref1 is output from a connection point B between the resistors R122 and R123. One end of the resistor R132 is connected to the connection point C between the resistors R123 and R124, the other end of the resistor R132 is connected to the collector of the transistor Tr1, and the emitter of the transistor Tr1 is connected to the ground G.

  Further, a series circuit of the resistor R131 and the secondary side PC_B of the photocoupler is connected between the circuit power supply terminal (+ 15V) and the ground G. A series circuit of a resistor R133 and a Zener diode ZD2 is connected between a connection point D between the resistor R131 and the secondary side PC_B of the photocoupler and the base of the transistor Tr1 (the anode of the Zener diode ZD2 is a transistor). Connected to the base of Tr1).

  In the above configuration, during the constant current drooping operation, the secondary side PC_B of the photocoupler is turned off (the transistor Tr1 is turned on), and the resistor R124 and the resistor R132 are connected in parallel. The voltage at the connection point B of the resistor R124 and the resistor R132 in the series circuit (resistor voltage dividing circuit) of the resistor R122, the resistor R123, and the resistor R124 // R132 (a parallel circuit of the resistors R124 and R132) is primary. It is output as a drooping reference signal Iref1 ′.

  On the other hand, during the constant power drooping operation, the secondary side PC_B of the photocoupler is turned on (transistor Tr1 is turned off), and the resistor R122 and the resistor in the series circuit (resistor voltage dividing circuit) of the resistor R122, the resistor R123, and the resistor R124. The voltage at the connection point B with R123 is output as the primary droop reference signal Iref1. Therefore, the primary droop reference signal Iref1 during the constant power drooping operation is larger than the primary droop reference signal Iref1 ′ during the constant current drooping operation. That is, at the time of constant power drooping operation, in order to flow an output current equal to or higher than the rated current Imax0 of the unit, the primary droop reference signal Iref1 at constant power drooping operation is It becomes larger than Iref1 ′.

  FIG. 4 is a diagram showing an operation sequence in the DC power supply unit 10. FIG. 4 shows the passage of time in the horizontal direction, and in the vertical direction, the DC power supply unit 10 is started / stopped (D / D_ON / OFF) (high level is turned on (started)), and a constant power drooping operation is performed. The signal I_KIND, the voltage signal Iref_M, and the output voltage Vo are shown side by side.

  As shown in FIG. 4, when the DC power supply unit 10 is turned on (started up) at time t1, the output voltage Vo (and output current Io) is avoided in order to prevent a rush current (inrush current) from flowing on the input side and the output side. ) Is gradually moved to the current walk-in operation mode (soft start). Thereafter, the DC power supply unit 10 performs constant power drooping operation by increasing the signal I_KIND to ON (high level) and increasing the signal Iref_M to Iref_M2 at time t2 when the output voltage Vo rises to some extent due to the current walk-in. Start. Next, when the output voltage Vo rises to the required rated voltage in this constant power drooping operation state (time t3), the DC power supply unit 10 turns off the signal I_KIND (low level) after a few seconds (time t4), Further, the signal Iref_M is lowered to Iref_M1, and the constant current drooping operation is started.

  In the example shown in FIG. 4, the DC power supply unit 10 switches from the constant power drooping operation to the constant current drooping operation after a few seconds after detecting that the output voltage Vo has risen to the rated voltage at time t3. However, it is not limited to this. For example, after the DC power supply unit 10 is turned on (started) at time t1, a predetermined time is measured by a timer or the like, and after the predetermined time has elapsed, the constant power drooping operation is switched to the constant current drooping operation. Also good. Further, in the case of the parallel redundant operation method in which a plurality of DC power supply units 10 are operated in parallel, after detecting that the output voltage Vo has risen to the required rated voltage in each DC power supply unit 10, the constant power drooping operation is started. You may make it switch to constant current drooping operation.

(Description of configuration and operation of DC / DC converter circuit 50)
Next, the DC / DC converter circuit 50 will be described. FIG. 5 is a diagram showing a configuration of the DC / DC converter circuit 50. The DC power supply unit 10 shown in this figure has a main circuit constituted by a forward converter (forward switching power supply).
In FIG. 5, Tx1 is an output transformer, Q1 is a switching element connected to the primary side of the output transformer Tx1, E is a DC power source (power source generated by the power factor correction circuit 20), RL is a load having a constant power characteristic, EA1 and EA2 are error amplifiers (operational amplifiers), CMP1 and CMP2 are comparators (comparators), CT is a current sensor (for example, a current transformer that detects the primary current of the output transformer Tx1), and the shunt SH is a secondary current detection. It is an element.

  The DC / DC converter circuit 50 includes an output constant voltage control circuit 51, an output constant current control circuit (secondary droop circuit) 52, and an instantaneous overcurrent control circuit (primary droop circuit) 53. . The output sides of the circuits 51, 52 and 53 are connected to the cathode sides of the diodes D11, D12 and D13, respectively, and the anode sides of the diodes D11, D12 and D13 are commonly connected to the node N1. The node N1 is connected to the power supply terminal (Vcc) via the resistor R41, and the node N1 is connected to the non-inverting input terminal (+) of the comparator CMP2.

  Therefore, due to the action of the diodes D11, D12, and D13, the output signal AVR_V of the output constant voltage control circuit 51, the output signal AVR_I2 of the output constant current control circuit 52, and the output signal of the instantaneous overcurrent control circuit 53 are connected to the node N1. The signal having the lowest signal level among AVR_I1 is selected and output to the node N1. The signal output to the node N1 is compared with the power supply operating frequency carrier triangular waveform by the comparator CMP2, and a drive signal (PWM signal) of the switching element (switching transistor) Q1 is generated. When the switching element Q1 is turned ON / OFF, a current flows from the power source E to the primary side coil of the output transformer Tx1, and the current flows to the secondary side coil by being electromagnetically induced by the primary side current. A rectifier circuit unit 54 is connected to the secondary side of the output transformer Tx1. In this rectifier circuit unit 54, the current flowing through the secondary coil is rectified by a rectifier circuit including diodes D1 and D2, and is smoothed by a smoothing circuit including a reactor L1 and a capacitor C1, and a DC voltage (output voltage Vo) is generated. Generated. This output voltage Vo is applied to the load RL through the shunt SH. Note that the DC / DC converter circuit 50 shown in FIG. 5 is configured such that the connection point (terminal of the output voltage V (+)) between the shunt SH and the load RL is on the ground (G) side of the control circuit.

(Description of output constant voltage control circuit 51)
The output constant voltage control circuit 51 shown in FIG. 5 corresponds to the difference between the detection signal of the output voltage Vo and the output voltage reference signal Vref (see FIG. 1) input from the D / D controller 41. This is a control circuit for controlling the ON width. The output constant voltage control circuit 51 includes an output voltage detection unit configured by a resistance voltage dividing circuit in which resistors R11 and R12 are connected in series, and includes an error amplifier EA1. One end of the resistor R11 is connected to the positive output voltage (+) terminal, the other end of the resistor R11 is connected to one end of the resistor R12, and the other end of the resistor R12 is connected to the negative output voltage (−) terminal. Is done. The connection point between the resistors R11 and R12 is connected to the non-inverting input terminal (+) of the error amplifier EA1 through the resistor R13. The output voltage reference signal Vref output from the D / D controller 41 is input to the inverting input terminal (−) of the error amplifier EA1.

  A resistor R14 (proportional element) is connected between the non-inverting input terminal (+) and the output terminal of the error amplifier EA1, and a series circuit (component element) of the capacitor C11 and the resistor R15 is connected. Therefore, the error amplifier EA1 becomes a proportional integration circuit (first-order lag circuit), and the difference between the output voltage Vo (more precisely, the detection signal of the output voltage V (−)) and the output voltage reference signal Vref has a predetermined time constant. The differentially amplified signal AVR_V is output. For this reason, since the output of the error amplifier EA1 gradually changes with a predetermined time constant, the response is delayed as compared with an instantaneous overcurrent control circuit 53 described later.

  During normal operation, that is, when the output voltage drooping operation by the output constant current control circuit 52 and the instantaneous overcurrent control circuit 53 is not performed, the output signal AVR_V of the output constant voltage control circuit 51 is output to the node N1. The output signal AVR_V is compared with the power supply operating frequency carrier triangular waveform by the comparator CMP2, and an ON / OFF drive signal (PWM signal) of the switching element Q1 is generated.

  For example, FIG. 6 is a diagram illustrating the operation of the DC / DC converter circuit 50. The horizontal axis indicates the passage of time, and the voltages (AVR_V, V) output from the circuits 51, 52, and 53 to the node N1 in the vertical direction. AVR_I2 or AVR_I1), the carrier triangular waveform, the output of the comparator CMP2 (the switching element Q1 is ON at a high level), and the output voltage Vo are shown side by side.

  In this figure, as shown in FIG. 6A, during normal operation (during normal output voltage range control), the output voltage of the node N1 is the output voltage from the output constant voltage control circuit (error amplifier EA1) 51. The output signal AVR_V is output to the node N1. The output signal AVR_V is compared with the power supply operating frequency carrier triangular waveform by the comparator CMP2, and an ON / OFF drive signal for the switching element Q1 is generated from the comparator CMP2. As a result, the output voltage Vo is controlled to be a constant value.

(Description of output constant current control circuit 52)
The output constant current control circuit 52 shown in FIG. 5 is a control circuit that controls a constant power drooping operation (secondary drooping operation that detects and droops the output current flowing from the DC power supply unit 10 to the load RL). The output constant current control circuit 52 is also a circuit that performs a constant current drooping operation during normal operation (at the time of constant current drooping operation), as will be described later. In this output constant current control circuit 52, the output current detection signal C detected by the shunt SH that is a detection element of the output current Io is input to the inverting input terminal (−) of the error amplifier EA2 via the resistor R21. Further, the secondary droop reference signal Iref2 (see FIG. 3B) output from the droop reference signal generation unit 42 is input to the non-inverting input terminal (+) of the error amplifier EA2. As described above, in the output constant current control circuit 52, the detection signal C of the output current Io and the secondary droop reference signal Iref2 are input to the error amplifier EA2, and the signal AVR_I2 differentially amplified by the error amplifier EA2 is output. To do.

A resistor R22 (proportional element) is connected between the inverting input terminal (−) and the output terminal of the error amplifier EA2, and a series circuit (integrating element) of the capacitor C21 and the resistor R23 is connected. Yes. Accordingly, the error amplifier EA2 becomes a proportional integration circuit (primary delay circuit), and the difference between the output current value signal C and the secondary drooping reference signal Iref2 is differentially amplified with a predetermined time constant. That is, the output of the error amplifier EA2 gradually changes with a predetermined time constant, and the response of the error amplifier EA2 is set so that the response is delayed as compared with an instantaneous overcurrent control circuit 53 described later.
With the configuration of the output constant current control circuit 52, when the output current Io increases, the output signal AVR_I2 of the differentially amplified EA2 gradually decreases. When the output signal AVR_V and the signal AVR_I1 become lower, the output signal AVR_I2 is output to the node N1. Is done.

FIG. 6B shows the circuit operation of the output constant current control circuit 52. As shown in FIG. 6B, in the output constant current control circuit 52, when the detection signal C of the output current Io exceeds the voltage level of the secondary droop reference signal Iref2, the output signal AVR_I2 of the error amplifier EA2 gradually decreases. When the signal is lower than the signal AVR_V, the output signal AVR_I2 is output to the node N1, the signal AVR_I2 is compared with the power supply operating frequency carrier triangular waveform by the comparator CMP2, and a drive signal (PWM signal) for the switching element Q1 is generated.
Thus, as the output current Io increases, the output signal AVR_I2 gradually decreases, and the secondary drooping operation is started.

(Description of the instantaneous overcurrent control circuit 53)
The instantaneous overcurrent control circuit 53 shown in FIG. 5 is a control circuit that controls a constant current drooping operation (primary drooping operation that detects and droops the primary current of the output transformer Tx1) for instantaneous overcurrent protection. In the instantaneous overcurrent control circuit 53, the current signals A and B detected by the current sensor CT which is the primary current detection element of the output transformer Tx1 are rectified by the diode D31 and the resistor R31 to generate the primary current detection signal Is. The generated signal Is is input to the inverting input terminal (−) of the comparator CMP1. The signal Is is a pulsed voltage signal. The primary droop reference signal Iref1 (see FIG. 3C) generated by the droop reference signal generator 42 is input to the non-inverting input terminal (+) of the comparator CMP1.

  With the configuration of the instantaneous overcurrent control circuit 53, when the primary current of the output transformer Tx1 increases and the signal Is exceeds the primary droop reference signal Iref1 (signal Is> Iref1), the output signal AVR_I1 of the comparator CMP1 is immediately low. Level signal. The low level signal AVR_I1 output from the comparator CMP1 is always set so that the signal level is lower than the output signal AVR_V of the output constant voltage control circuit 51 and the output signal AVR_I2 of the output constant current control circuit 52. When the instantaneous overcurrent control circuit 53 detects an overcurrent, the signal AVR_I1 is immediately output to the node N1.

  As described above, when the DC / DC converter circuit 50 enters the drooping operation due to the instantaneous overcurrent, the signal Is of the current value detected by the current sensor CT and the primary droop reference signal Iref1 are compared in the instantaneous overcurrent control circuit 53. When the comparison is made by the comparator CMP1 and the signal Is exceeds the primary droop reference Iref1, the output signal of the comparator CMP1 is immediately set to the low level to lower the output voltage. The instantaneous overcurrent control circuit 53 operates faster than the output constant current control circuit (secondary droop) 52, and protects the power supply by performing transient overcurrent limiting.

  FIG. 6C shows the circuit operation of the instantaneous overcurrent control circuit 53. As shown in FIG. 6C, in the instantaneous overcurrent control circuit 53, when the primary-side current detection signal Is of the output transformer Tx1 exceeds the primary droop reference signal Iref1, the output signal AVR_I1 of the comparator CMP1 is immediately low. The low level signal AVR_I1 is output to the node N1, the signal AVR_I1 is compared with the power supply operating frequency carrier triangular waveform by the comparator CMP2, and the drive signal (PWM signal) of the switching element Q1 is generated. In the case of this drooping operation, the output (pulse width) of CMP2 is significantly narrowed, and the output voltage Vo is greatly reduced.

  As described above, in the DC / DC converter circuit 50, the current limit (secondary drooping operation) in the constant power drooping operation is controlled by the output constant current control circuit 52 (error amplifier EA2). Further, the current limit (primary drooping operation) by the instantaneous overcurrent protection is controlled by the instantaneous overcurrent control circuit 53 (comparator CMP1). Further, the secondary droop reference signal Iref2 is always set to be smaller than the primary droop reference signal Iref1, that is, the relationship of “secondary droop reference signal Iref2 <primary droop reference signal Iref1” is set.

  For example, as shown in FIG. 7, when performing the constant power drooping operation shown in the period T1, the secondary droop reference signal Iref2 is set to the signal level A2 (the maximum value of the output current in the constant power drooping operation is temporarily set to the signal level). The primary drooping reference signal Iref1 is also increased in proportion to the signal level A1 (the current limit value of the primary current of the output transformer Tx1 is temporarily increased to the signal level A1). Further, when performing the constant current drooping operation shown in the period T2, the primary droop reference signal Iref1 is set to the signal level B1 corresponding to the instantaneous overcurrent protection current during normal operation, and the secondary droop reference signal Iref2 is the primary droop. The signal level B2 is smaller than the signal level B1 of the reference signal Iref1.

  Regarding the relationship between the signal level B1 of the primary droop reference signal Iref1 and the signal level B2 of the secondary droop reference signal Iref2 during the constant current drooping operation in the period T2, for example, the signal level B2 of the secondary droop reference signal Iref2 Is set to match the rated current Imax0 (100% current that can flow continuously). Further, for example, the signal level B1 of the primary droop reference signal Iref1 is set to coincide with the instantaneous overcurrent protection current (current that can be passed for a short time rating, for example, 150% of the rated current). Thus, when an overcurrent state occurs, the output current is instantaneously limited to the instantaneous overcurrent limiting current (for example, 150%) by the quick response instantaneous overcurrent control circuit 53, and then the output constant current control circuit 52 Thus, the output current can be limited to the rated current (100%) with a predetermined time constant.

(Description of DC power supply)
Next, a DC power supply device 101 using a plurality of DC power supply units of the present invention will be described. A DC power supply device 101 according to the present embodiment includes a DC power supply unit 10 using the above-described DC / DC converter circuit 50. A plurality of the DC power supply units 10 are provided and connected in parallel. It is configured with a redundant operation method. An example of this is shown in FIG. FIG. 8 shows a block diagram of DC power supply units 10A, 10B, and 10C constituting the DC power supply device 101 in the DC power supply system 100. As shown in FIG. The DC power supply units 10A, 10B, and 10C are configured to use a U-phase, V-phase, and W-phase three-phase alternating current (for example, AC three-phase 200V) as an input power supply. In this example, a three-phase alternating current is used as an input power supply, but the direct-current power supply device 101 of the present invention can be configured even with a single-phase alternating current input.

  A DC power supply device 101 shown in FIG. 8 includes power factor correction circuits 20A, 20B, and 20C on the input side of the DC power supply units 10A, 10B, and 10C, and DC / DC converter circuits 50A, 50B, and 50C are connected to outputs thereof. ing. That is, the power factor correction circuits 20A, 20B, and 20C serve as a DC power source E for the DC / DC converter circuits 50A, 50B, and 50C. In addition, the DC power supply apparatus 101 includes a D / D control circuit 40A separately from this. The D / D control circuit 40A is a circuit including the D / D controller 41 and the drooping reference signal generator 42 shown in FIG. The D / D control circuit 40A is connected to each of the DC / DC converter circuits 50A, 50B, 50C.

  The configurations and operations of the DC / DC converter circuits 50A, 50B, and 50C are the same as those of the DC / DC converter circuit 50 shown in FIG. Further, the configuration and operation of the D / D control circuit 40A are the same as those of the D / D control circuit 40 shown in FIG. 1, but the D / D control circuit 40A includes a plurality of DC / DC converter circuits 50A. , 50B and 50C are different. The D / D control circuit 40A outputs an output voltage reference signal Vref, a primary droop reference signal Iref1, and a secondary droop reference signal Iref2 to the DC / DC converter circuits 50A, 50B, and 50C. In this case, the primary droop reference signal Iref1 and the secondary droop reference signal Iref2 output to the DC / DC converter circuits 50A, 50B, and 50C are set in accordance with the capacities and characteristics of the circuits 50A, 50B, and 50, respectively. It can also be set for each of the circuits 50A, 50B, 50.

  With the configuration of the DC power supply device 101, when power is supplied to the load RL (load having constant power characteristics) using the plurality of DC power supply units 10A, 10B, and 10C, power is supplied from the storage battery 61 to the load RL due to a power failure. When power is restored during the supply, each DC power supply unit 10A, 10B, 10C temporarily performs a constant power drooping operation. Thus, the output voltage Vo (=) of each DC power supply unit 10A, 10B, 10C is supplied from the DC power supply units 10A, 10B, 10C to the load RL while supplying a current equal to or higher than the rated current Imax0 (maximum current during normal operation). The load voltage VL) can be raised to the required rated voltage.

[Second Embodiment]
In the first embodiment described above, by giving each DC power supply unit in the DC power supply device 101 a constant power drooping characteristic temporarily only when the power is restored (when the DC power supply unit is started), The example in which the power supply to the load device by the storage battery is switched by the power supply from the DC power supply unit has been described. However, even if the DC power supply unit is temporarily given a constant power drooping characteristic, a phenomenon that the storage battery discharge continues may occur depending on conditions such as the storage battery voltage when the power is restored. When this phenomenon occurs, the DC power supply unit is suspended, the output voltage of the DC power supply unit is regulated by the storage battery voltage (pulled by the storage battery voltage), and the load voltage cannot be restored to the rated voltage. As a second embodiment of the present invention, an example of a DC power supply device that can reliably switch the power supply to the load device from the storage battery to the power supply from the DC power supply unit when the power supply is restored will be described.

(Supplementary explanation about constant current drooping characteristics and constant power drooping characteristics)
Here, the constant current drooping characteristics and the constant power drooping characteristics of the DC power supply unit will be described again with reference to FIG. As mentioned above, the DC power supply unit should not output more than a certain current value so that the DC power supply unit itself will not be damaged by excessive current flowing from the DC power supply unit to the point of the accident, such as when a short circuit accident occurs on the output side. It has a drooping characteristic to make it. The drooping characteristics include a constant current drooping characteristic shown in FIG. 17B and a constant power drooping characteristic shown in FIG. The constant current drooping characteristic shown in FIG. 17B has a certain current value (40A in the example in the figure) as an upper limit, and when the current is requested on the load side beyond that, the output voltage of the DC power supply unit is lowered. This is a characteristic for protecting the DC power supply unit itself.

  The constant power drooping characteristic shown in FIG. 17C is a characteristic that increases the output current as the voltage decreases so that the rated capacity can be output up to a certain voltage. In the example shown in the figure, a current of 58 A can flow at an output voltage of 260V. This constant power drooping characteristic is employed in, for example, a DC power supply device of a communication power supply device. In the communication power supply system in which the load RL has a constant power characteristic, the load RL requires a certain amount of power even during the discharge of the storage battery 61. Therefore, when switching from the storage battery discharge state where the voltage has dropped to the power supply from the DC power supply device 101B. Therefore, this constant power drooping characteristic has been considered suitable. However, since the DC power supply unit having the constant power drooping characteristic needs to have a capacity corresponding to the rated voltage × the maximum droop current after all as the capacity of the DC power supply unit, the DC power supply unit (that is, the DC power supply device 101B). The capacity has been increased, and it has become over-spec.

  The reason for this is that the power supply by the DC power supply device 101B is switched to the power supply by the storage battery 61 at the time of commercial power failure. When the commercial power is restored, it is necessary to return from the power supply by the storage battery 61 to the power supply by the DC power supply device 101B. In order to switch from the storage battery 61 to the DC power supply device 101B, the DC power supply device 101B must have a constant power drooping characteristic. In order to return the voltage reduced by the power supply from the storage battery 61 to the normal state, it is necessary to supply a current higher than the storage battery that was the voltage source at the time of power failure from the DC power supply unit, and the DC power supply unit must be the voltage source. Because. When the DC power supply unit has constant power drooping characteristics, the capacity of the DC power supply unit is conventionally designed to satisfy “maximum current × rated voltage”. For this reason, the rated current normally used is smaller than the maximum current. For example, assuming that the rated current (100% continuous current) is 40 A and the maximum rated current is 58 A, the DC power supply unit is normally used at 68% of the actual maximum value. Normally, 68% is used, and the remaining 32% is used only in an emergency, which is inefficient. Depending on the load capacity, the required number of DC power supply units increases and the cost also increases.

  On the other hand, the constant current drooping characteristic is always used, and as shown in FIG. 17D, the constant power drooping characteristic (58 A at 260 V in the example shown in FIG. 17) is limited to a short time. Constant power drooping characteristics. According to this short-time constant power drooping characteristic, the DC power supply unit can output exceeding the rated current (40A in the example in the figure) for a short time, but cannot output for a long time due to temperature restrictions, for example. The capacity of the DC power supply unit (that is, the DC power supply device 101B) can be minimized by using this characteristic only when power supply is switched to the DC power supply unit from the storage battery discharge state where the voltage has dropped.

For example, the effect of the constant power drooping characteristic for a short time is exhibited in the following state.
When the power failure is recovered and the commercial power is restored, the storage battery discharge state must be switched to the supply state by the DC power supply unit. Since the storage battery voltage is considerably lower than the steady-state voltage in the storage battery discharge state, the output currents of the DC power supply units (RF-U) 1 to N are temporarily and collectively shown in FIG. To increase. In this case, as shown in FIG. 18B, the output current of the DC power supply unit (RF-U) increases to 58 A due to the short-time constant power drooping characteristic. Thus, since the full load current can be supplied from the DC power supply units 1 to N, the diode DX1 is turned off (meaning that the diode DX1 shifts from the forward bias to the reverse bias state), and the DC power supply unit (RF− It is possible to return to the load power supply state according to U).

(Explanation of problems to be solved in the second embodiment)
By the way, for example, even when one DC power supply unit is in a failure state, if the constant power drooping operation described in FIG. 17D is performed for a short time, the DC power supply device at the time of power recovery after a power failure (from To be precise, the operation of the DC power supply unit is divided into the following two cases.

As a first case, when a power failure is recovered in a state where one DC power supply unit is faulty (for example, the DC power supply unit 2 shown in FIG. 19A is faulty) and the commercial power supply is restored, Power is supplied to the load RL instead of the one in which the spare unit (CH-U) has failed. In this case, since the charging / spare unit (CH-U) supplies power to the load RL, the diode DX1 is turned on. At this time, the voltage of the power supply line DCL1 (load voltage VL) varies depending on the state of the storage battery voltage (charge voltage) of the storage battery 61.
When the storage battery is substantially equal to the floating charge, “the voltage of the power supply line DCL1 (load voltage VL) = the output voltage of the charging / spare unit” is established, and the storage battery 61 is in the floating charge as shown in FIG. In this case, as shown in FIG. 19B, the output voltage of the charging / spare unit is a floating charging voltage, and the voltage (374V: charging) close to the rated voltage (eg, 380V) of the DC power supply unit (RF-U). And the rated voltage of the spare unit (CH-U)). Therefore, the DC power supply device (a DC power supply unit that operates normally and a charging / standby unit) can output a predetermined load capacity not only during a short-time constant power drooping operation but also when returning to a constant current drooping characteristic.

  As a second case, when the storage battery 61 is in a constant current charge state, “voltage of the power supply line DCL1 (load voltage VL) = storage battery voltage”. In this case, as shown in FIG. 20B, the storage battery voltage is significantly lower than the rated voltage (for example, 380V) of the DC power supply unit (RF-U) and becomes 310V. For this reason, in the DC power supply device 101B, as shown in FIG. 20A, the remaining normal operating DC power supply unit (RF-U) and charging / spare unit (CH-U) Although the load current supplied to the load RL can be temporarily covered by “power supply by unit + short-time constant power drooping operation”, each unit eventually has a constant current drooping characteristic, so that the output capacity of the DC power supply device 101B is Decrease. As a result, the remaining DC power supply unit (RF-U) and the charge / spare unit (CH-U) alone cannot supply the load current, and the battery discharge may continue. Generally, an event may occur in which the storage battery discharge continues when one storage unit 61 fails in a constant current charging state. That is, the diode DX1 remains turned on (the diode DX1 is forward-biased and conductive), and the normal DC power supply unit (RF-U), the charging / spare unit (CH-U), the storage battery 61, To supply current to the load RL.

FIGS. 21, 22, and 23 are time charts for explaining the operation at the time of power recovery after a power failure in the DC power supply apparatus 101B. The time charts shown in FIG. 21, FIG. 22, and FIG. 23 show the passage of time t in the horizontal direction and the power, voltage, and current of each part in the vertical direction. Then, in each of FIGS. 21, 22, and 23, in FIG. (A), the load power PL, and the output power _{P RF-U} of the DC power supply unit (RF-U), the charging and protection unit ( CH-U) output power P _CH-U and storage battery charge / discharge power Pbat. In FIG. (B), the load voltage VL, the anode voltage Vdxa of the diode DX1, and the cathode voltage Vdxk are shown. Further, in FIG. (C), the load current IL, a output current _{I RF-U} of the DC power supply unit (RF-U), the output current _{I CH-U} of the charging and protection unit (CH-U), the storage battery A storage battery current Ibat which is a charge / discharge current to 61 is shown.

  In the above time chart, the following preconditions are assumed. First, the load capacity is 100 KW. Further, the rated output voltage capacity of the DC power supply units (RF-U) 1 to N is 15.2 kW, the rated output voltage is 383 V, the rated output current is 40 A, and the maximum rated current (short) The maximum output current (time) is set to 58A. In the figure, 15.2 KW (rated output capacity) is indicated by “15 KW” for easy viewing of the drawing. Moreover, the rated output capacity of the charging / spare unit (CH-U) is 15.2 kW, the rated output voltage is 374.6 V, the rated output current is 40 A, and the maximum rated current (short-time maximum output current) is 58A.

  Further, the power storage device uses 168 sets of 2V type storage batteries, and is configured to have a floating charging voltage of 374.6 V (2.23 × 168). Further, the maximum charging current (charging current in constant current charging) is limited to 30A. That is, when constant current charging is performed from the charging / spare unit (CH-U) to the storage battery 61, the output current of the charging / spare unit (CH-U) is limited to 30A (constant current drooping characteristic from 40A). 30A). The monitoring unit 81 changes the constant current drooping characteristic in the charging / spare unit (CH-U). The monitoring unit 81 constantly detects the output voltage (load voltage VL) of the DC power supply device and the output voltage and output current of the charging / spare unit (CH-U). When power is not supplied and the storage battery 61 is charged with constant current, the output current of the charging / spare unit (CH-U) is limited to 30A. Note that in the case of rapid charging during a constant power drooping operation, which will be described later, the charging current temporarily becomes 58 A (see times t3 to t4 in FIG. 21C).

  Further, the storage battery voltage when the diode DX1 connected to the storage battery 61 is turned off is set to “310.8 V”. That is, when the DC power supply unit (RF-U) can increase the load voltage VL to 301.8 V or more, the diode DX1 can be turned off. This value (310.8V) is, for example, a set of 168 pieces when the open-circuit voltage (storage battery voltage when not discharging) when the capacity of the 2V lead storage battery is empty is 1.85V. It is a value calculated by “1.85 × 168 pieces = 310.8 V” as the open-circuit voltage of the storage battery. However, this value (310.8 V) is a value that changes according to the storage battery open voltage (storage battery voltage when no load is connected to the storage battery) according to the actual state of charge of the storage battery.

  First, a time chart at the time of power recovery shown in FIG. 21 will be described. The time chart shown in FIG. 21 shows that there are no faulty DC power supply units (RF-U), and seven DC power supply units (RF-U) that operate normally and one charging / spare unit (CH-U). ) And start up after power recovery. Moreover, the storage battery voltage at the time of power recovery is 250V, and the diode DX1 is turned off by the constant power drooping operation of the DC power supply unit (RF-U). That is, the example shown in FIG. 21 is an example during normal operation in which the diode DX1 is turned off.

  Referring to the time chart shown in FIG. 21, between time t0 and time t1, DC power supply device 101B is stopped due to a power failure, and power is supplied from storage battery 61 to load RL. Then, the power is restored at time t1, the DC power supply device 101B is activated from time t2, and the supply of current is started from each DC power supply unit (RF-U) and charging / spare unit (CH-U). Each DC power supply unit (RF-U) and charging / standby unit (CH-U) perform a constant power drooping operation from time t2 to time t4, and from time constant t4 to a constant current drooping operation. Switch to operation. In the constant power drooping operation period from time t2 to time t4, during the period from time t2 to time t3, each DC power supply unit is used in order to avoid a rush current (inrush current) flowing on the input side and output side. This is a current walk-in operation mode (soft start mode) in which the output voltage and output current of (RF-U) and the charging and standby unit (CH-U) are gradually raised.

During storage battery discharge from time t0 to time t1, electric power (100 kW) is supplied from the storage battery 61 to the load RL. As shown in FIG. (B), the anode voltage Vdxa and the cathode voltage Vdxk ( As the load voltage VL) gradually decreases, the storage battery current Ibat gradually increases as shown in FIG. At time t2, when the DC power supply unit (RF-U) and the charging / spare unit (CH-U) start operating, the output current I _RF- from the DC power supply unit (RF-U) is started after time t2. _U and the output current I _CH-U from the charging and standby unit (CH-U) start to increase gradually. Further, after time t2, the storage battery current Ibat (discharge current) gradually decreases as the output current from the DC power supply unit (RF-U) and the charging / spare unit (CH-U) increases, and at time t3, the storage battery The current Ibat (discharge current) becomes 0 (zero).

  On the other hand, as shown in FIG. 5B, after time t0, the diode DX1 is in the on state, and after time t2, its anode voltage Vdxa (= load voltage VL) and cathode voltage Vdxk (= load voltage VL) gradually increase. At time t3, it becomes “310.8 V”, and the output current from the DC power supply unit (RF-U) becomes 321.7 A. At this time t3, the condition of “100 kW (load power) <Pmax (15.2 kW) × 7 units” shown in equation (1), which will be described later, is satisfied, so that the diode DX1 is turned off and the load voltage reaches 383V. stand up.

  At time t3, when the diode DX1 is turned off, the load voltage VL increases to 383 V, so that the output current IRF-U of the DC power supply unit (RF-U) is 261.1 A (≈100 kW / 383 V). To drop. Further, the charging / spare unit (CH-U) rapidly charges the storage battery 61 by flowing a storage battery current Ibat (charging current) of 58 A through the storage battery 61 by a constant power drooping operation until time t4. For this reason, as shown to a figure (B), after the time t3, the anode voltage Vdxa (storage battery electric charging voltage) of the storage battery 61 increases gradually.

  Thereafter, at time t4, the constant power drooping operation period ends, and the constant current drooping operation period is switched to. In the constant current drooping operation period, the DC power supply unit (RF-U) supplies power to the load RL, and the charging / spare unit (CH-U) performs constant current charging of the storage battery 61. Note that the charging current for constant current charging to the storage battery 61 in the constant current drooping operation period after time t4 is limited to 30 A for charging current limitation.

  Next, a time chart at the time of power recovery shown in FIG. 22 will be described. The time chart shown in FIG. 22 is similar to the case of FIG. 21, there are no failed DC power supply units (RF-U), and seven DC power supply units (RF-U) that operate normally and one charge. This is an example in which the standby unit (CH-U) is used to start up after power recovery. However, the case of FIG. 22 is an example in which the storage battery voltage at the time of power recovery is as low as 200 V, and the diode DX1 cannot be turned off even by the constant power drooping operation of the DC power supply unit (RF-U). This is different from the case of FIG. That is, the time chart shown in FIG. 22 is an example of an abnormal operation in which the diode DX1 cannot be turned off even though there is no failed DC power supply unit (RF-U). The preconditions are the same as in FIG.

  Referring to the time chart shown in FIG. 22, between time t0 and time t1, DC power supply device 101B is stopped due to a power failure, and power is supplied from storage battery 61 to load RL. Then, the power is restored at time t1, the DC power supply device 101B is activated from time t2, and the supply of current is started from each DC power supply unit (RF-U) and charging / spare unit (CH-U). Each DC power supply unit (RF-U) and charging / standby unit (CH-U) perform a constant power drooping operation from time t2 to time t4, and from time constant t4 to a constant current drooping operation. Switch to operation.

During storage battery discharge from time t0 to time t1, electric power (100 kW) is supplied from the storage battery 61 to the load RL. As shown in FIG. (B), the anode voltage Vdxa and the cathode voltage Vdxk ( = Load voltage VL) gradually decreases, and the storage battery current Ibat (load current IL) gradually increases as shown in FIG. At time t2, when the DC power supply unit (RF-U) and the charging / spare unit (CH-U) start operating, the output current I _RF- from the DC power supply unit (RF-U) is started after time t2. _U and the output current I _CH-U from the charging and standby unit (CH-U) begin to increase gradually. Further, after time t2, the storage battery current Ibat (discharge current) gradually decreases as the output current from the DC power supply unit (RF-U) and the charging / spare unit (CH-U) increases, and at time t3, the storage battery The current Ibat (discharge current) becomes 0 (zero).

On the other hand, as shown in FIG. 5B, after time t0, the diode DX1 is in the on state, and after time t2, its anode voltage Vdxa (= load voltage VL) and cathode voltage Vdxk (= load voltage VL) gradually increase. At time t3, the voltage becomes “240V”. At this time t3, the current supplied to the load RL (100 kW) requires 416 A (≈100 kW / 240 V), and the output current I _RF-U from the DC power supply unit (RF-U) is caused by the constant power drooping operation. 406A (= 58A × 7), and the deficient current (10A) is supplied from the charging and standby unit (CH-U).

  At time t3, the condition of “100 kW (load power) <240V × 58A × 7 units” shown in the equation (2) described later is not satisfied, and the diode DX1 cannot be turned off, so the load voltage VL is equal to the rated voltage ( For example, it cannot rise to 383V) and remains at the storage battery voltage (240V).

Then, at time t4, the constant power drooping operation period is switched to the constant current drooping operation period. When the constant power drooping operation is switched to the constant current drooping operation at the time t4, the DC power supply unit (RF-U) supplies a current of 280A (= 40A × 7 units) to the load RL, and the charge / spare unit (CH-U) supplies a current of 40 A to the load RL. The remaining insufficient current 134A “≈ (100 kW / 240V) −320A” is supplied by the storage battery current Ibat (discharge current) of the storage battery 61.
After time t4, due to the discharge of the storage battery 61, the anode voltage Vdxa of the diode DX1 gradually decreases as shown in FIG. (B), and the storage battery current Ibat (discharge current) also gradually increases as shown in FIG. (C). .

  Thus, even when the DC power supply unit (RF-U) has a constant power drooping characteristic and all of the seven DC power supply units (RF-U) are normal, the storage battery voltage at the time of power recovery is When the voltage is low (for example, 200 V), the diode DX1 cannot be turned off, the discharge current from the storage battery 61 continues to flow, and the load voltage VL may not be increased to the rated voltage (for example, 383 V). .

  Next, a time chart at the time of power recovery shown in FIG. 23 will be described. The time chart shown in FIG. 23 is a time chart showing the start-up operation at the time of power recovery when one unit fails. There is one failed DC power supply unit (RF-U), and the remaining six normal units. This is an example in which a start-up operation after power recovery is performed using a DC power supply unit (RF-U) and one charging / spare unit (CH-U). Moreover, it is an example in case the storage battery voltage at the time of power recovery is 250V, and is an example in which the diode DX1 cannot be turned off even if the DC power supply unit (RF-U) performs a constant power drooping operation. That is, the time chart shown in FIG. 23 is an example of an abnormal operation in which the diode DX1 cannot be turned off when one DC power supply unit (RF-U) fails. The preconditions are the same as in FIG.

  Referring to the time chart shown in FIG. 23, between time t0 and time t1, DC power supply device 101B is stopped due to a power failure, and power is supplied from storage battery 61 to load RL. Then, the power is restored at time t1, the DC power supply device 101B is activated from time t2, and the supply of current is started from each DC power supply unit (RF-U) and charging / spare unit (CH-U). Each DC power supply unit (RF-U) and charging / standby unit (CH-U) perform a constant power drooping operation from time t2 to time t4, and from time constant t4 to a constant current drooping operation. Switch to operation.

During storage battery discharge from time t0 to time t1, power (100 kW) is supplied from the storage battery 61 to the load RL. As shown in FIG. 5B, the anode voltage Vdxa (load voltage VL) is discharged by the discharge of the storage battery 61. In addition, the cathode voltage Vdxk (= load voltage VL) gradually decreases, and the storage battery current Ibat (load current IL) gradually increases as shown in FIG. At time t2, when the DC power supply unit (RF-U) and the charging / spare unit (CH-U) start operating, the output current I _RF- from the DC power supply unit (RF-U) is started after time t2. _U and the output current I _CH-U from the charging and standby unit (CH-U) begin to increase gradually. Further, after time t2, the anode voltage Vdxa and the cathode voltage Vdxk of the diode DX1 start to gradually increase from 250V. Further, after time t2, the storage battery current Ibat (discharge current) gradually decreases as the output current from the DC power supply unit (RF-U) and the charging / spare unit (CH-U) increases, and at time t3, the storage battery The current Ibat (discharge current) becomes 0 (zero).

As shown in FIG. (B), the diode DX1 is in the on state after time t0, and the anode voltage Vdxa (= load voltage VL) and cathode voltage Vdxk (= load voltage VL) gradually increase after time t2. At time t3, it becomes “310.8V”. At time t3, the current supplied to the load RL (100 kW) requires 321.7 A (≈100 kW / 310.8 V), and the output current I _RF-U from the DC power supply unit (RF-U) is constant. The power drooping operation results in 321.7 A “≈ (100 kW / 310.8)”. On the other hand, the charging / spare unit (CH-U) rapidly charges the storage battery 61 by flowing a storage battery current Ibat (charging current) of 58 A to the storage battery 61 by a constant power drooping operation until time t4. For this reason, as shown to a figure (B), after the time t3, the anode voltage Vdxa (storage battery electric charging voltage) of the storage battery 61 increases gradually.

  At this time t3, the diode DX1 cannot be turned off. This is a condition that does not cause storage battery discharge when one unit of the DC power supply unit (RF-U) fails, as shown by the following formula (3), “100 KW (load power) /310.8 V <40 A × 7 units” Since the condition cannot be met, the diode DX1 cannot be turned off. For this reason, the load voltage VL cannot be increased to the rated voltage (for example, 383 V) and remains the storage battery voltage. If it is assumed that the diode DX1 is turned off at time t3, the output voltage of the DC power supply unit (RF-U) instantaneously rises to a rated voltage (for example, 383 V), so the DC power supply unit (RF-U) The maximum output current is 40A. For this reason, even if the load current is supplied from a total of seven units including the DC power supply unit (RF-U) and the charging / spare unit (CH-U), the load current is 280 A (<321.7 A). Since the necessary load current (321.7 A) cannot be provided immediately after the operation, the diode DX1 cannot be turned off.

After time t3, the output current I _{RF-U of} the DC power supply unit (RF-U) gradually decreases as the anode voltage Vdxa of the diode DX1 increases. Then, at time t4, the constant power drooping operation period is switched to the constant current drooping operation period. When the constant power drooping operation is switched to the constant current drooping operation at time t4, the DC power supply unit (RF-U) supplies a current of 240 A (= 40 A × 6 units) to the load RL, and the charging / spare unit (CH -U) supplies a current of 40 A to the load RL. The remaining shortage current 32.5A “= (100 kW / 320V) −280A” is supplied by the storage battery current Ibat (discharge current) of the storage battery 61. After time t4, due to the discharge of the storage battery 61, the anode voltage Vdxa of the diode DX1 gradually decreases as shown in FIG. (B), and the storage battery current Ibat (discharge current) also gradually increases as shown in FIG. (C). .
Thus, when one DC power supply unit (RF-U) fails, even if the DC power supply unit (RF-U) has a constant power drooping characteristic, the storage battery voltage at the time of power recovery is low. The diode DX1 cannot be turned off, and the discharge current from the storage battery 61 may continue to flow.

  As described above, in the DC power supply device 101B, even when the DC power supply unit (RF-U) has a constant power drooping characteristic and all of the seven DC power supply units (RF-U) are normal, When the storage battery voltage at the time of power recovery is low, the diode DX1 does not turn off and the load voltage VL cannot be returned to the rated voltage (for example, 383 V), and the discharge current may continue to flow from the storage battery 61 to the load RL. . In addition, when one DC power supply unit (RF-U) fails, a diode is used when the storage battery voltage at the time of power recovery is low even if the DC power supply unit (RF-U) has a constant power drooping characteristic. DX1 does not turn off, and the discharge voltage may continue to flow from storage battery 61 to load RL without returning load voltage VL to the rated voltage.

  In the DC power supply device according to the second embodiment of the present invention, the specifications required during normal operation (for example, the selection of switching elements and thermal design specifications) remain the same during normal operation. A current exceeding the rated current can be supplied to the load, and the drooped output voltage is reliably raised to the output voltage (rated voltage) during normal operation.

(Description of Configuration of DC Power Supply Device of Second Embodiment)
FIG. 9 is a diagram showing a configuration of a DC power supply device according to the second embodiment of the present invention.
Compared with the DC power supply device 101B shown in FIG. 24, the DC power supply device 101A shown in FIG. 9 includes a monitoring unit 81, a switching unit 82, current sensors (current transformers) CT1, CT2, CT3, and a voltage sensor VT. Is different, and the other configuration is the same as that of the DC power supply device 101B shown in FIG. For this reason, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.
In FIG. 9, the DC power supply units (RF-U) 1 to N and the charging / spare unit (CH-U) always have a constant current drooping characteristic for overcurrent protection, When a trigger occurs, the constant current drooping characteristic is temporarily switched to the constant power drooping characteristic.

  The current sensor CT1 is a sensor that detects a load current that flows from the DC power supply device 101A to the load RL, and the current sensor CT2 is a sensor that detects an output current output from the charging and standby unit (CH-U). The current sensor CT <b> 3 is a sensor that detects the charge / discharge current of the storage battery 61. The current sensors CT1, CT2, and CT3 are, for example, current detectors using Hall elements. The voltage sensor VT is a voltage detector for detecting the output voltage (= load voltage VL) of the DC power supply device 101A, and is a circuit configured by, for example, a resistance voltage dividing circuit.

  The monitoring unit 81 inputs the operation state signals St1 to StN from each of the DC power supply units (RF-U) 1 to N, inputs the operation state signal Stc from the charging and standby unit (CH-U), and receives the DC power supply unit ( RF-U) and the charging / spare unit (CH-U) are detected for their operating state and failure. The monitoring unit 81 receives signals from the current sensors CT1, CT2, CT3 and the voltage sensor VT, and monitors the operating state of the DC power supply device 101A. The monitoring unit 81 controls the charging / spare unit (CH-U), and controls the execution of constant current charging or floating voltage charging from the charging / spare unit (CH-U) to the storage battery 61. Further, the monitoring unit 81 controls the switching unit 82 and connects the output terminal of the charging and standby unit (CH-U) to the anode side of the diode DX1 by a switch unit 83 in the switching unit 82 described later, or Whether to connect to the cathode side of the diode DX1 is switched.

FIG. 10 is a diagram illustrating a configuration example of the switching unit 82. As shown in this figure, the switching unit 82 includes a switch unit 83 and a diode DX1. The diode DX1 has an anode side connected to the third power supply line DCL3 (connected to the storage battery 61 via the power supply line DCL3) and a cathode side connected to the first power supply line DCL1. The switch unit 83 connects the first power supply line DCL1 and the second power supply line DCL2 to the conductive state or the nonconductive state, the first switching element, the second power supply line DCL2, and the third power supply line DCL3. And a second switching element that switches between conduction and non-conduction.
The configuration example shown in FIG. 10A is an example in which the switch unit 83 is configured by a relay contact (mechanical contact) of a power relay, and the switch unit 83 includes a first power line DCL1 and a second power line. The second switching element that switches the relay contact Rya (make contact) and the second power supply line DCL2 and the third power supply line DCL3 to the conduction or non-conduction as the first switching element that switches the DCL2 to the conduction or non-conduction. As a relay contact Ryb (break contact). In the example shown in FIG. 10A, one end of the relay contact Rya (make contact) in the switch unit 83 is connected to the first power supply line DCL1 (power supply line DCL1 connected to the cathode side of the diode DX1). The other end of the relay contact Rya (make contact) is connected to the positive (+) side output terminal of the charge / spare unit (CH-U) via the second power line DCL2. One end of the relay contact Ryb (break contact) in the switch unit 83 is connected to the third power supply line DCL3 (power supply line DCL3 connected to the anode side of the diode DX1), and the relay contact Ryb (break contact) The other end is connected to the positive (+) side output terminal of the charging and standby unit (CH-U) via the second power line DCL2. Note that the relay contact Rya (make contact) and the relay contact Ryb (break contact) are turned on when a relay coil (not shown) (a coil controlled by the monitoring unit 81) is excited. (Contact), and the relay contact Ryb (break contact) is OFF (non-conduction). Further, the negative (−) side output terminal of the charging and standby unit (CH−U) is connected to the negative (−) side common power line DCL−.

  FIG. 10B shows an example in which the switch unit 83 is configured using two NCh-type MOSFET elements (FETa and FETb). The switch unit 83 includes a first power supply line DCL1 and a second power supply. Diode D1 and FETa as first switching elements that switch the line DCL2 to conduction or non-conduction, and diodes as second switching elements that switch the second power supply line DCL2 and the third power supply line DCL3 to conduction or non-conduction D2 and FETb. In the example shown in FIG. 10B, the source terminal of FETa is connected to the first power supply line DCL1, the drain terminal of FETa is connected to the cathode side of the diode D1, and the anode side of the diode D1 is connected to the second power supply. It is connected to the output terminal on the positive (+) side of the charging and standby unit (CH-U) via the line DCL2. Further, the source terminal of the FETb is connected to the third power supply line DCL3, the drain terminal of the FETb is connected to the cathode side of the diode D2, and the anode side of the diode D2 is connected to the charging / spare unit via the second power supply line DCL2. Connect to the positive (+) output terminal of (CH-U).

  FETa and FETb are turned on (conductive) or turned off (non-conductive) when a control signal output from the monitoring unit 81 is applied to the gate terminal. The FETa and the FETb are interlocked so as not to be turned on at the same time. The diodes D1 and D2 are inserted to prevent current from flowing through body diodes (flywheel diodes) built in the FETa and FETb.

  With the configuration of the switching unit 82, for example, as shown in FIG. 11A, when all of the DC power supply units (RF-U) are normal, the monitoring unit 81 controls the switching unit 82 to charge. The output side of the cum / spare unit (CH-U) can be connected to the anode side of the diode DX1 so that the output current of the charge / spare unit (CH-U) can flow to the storage battery 61. In addition, as shown in FIG. 11B, the monitoring unit 81 controls the switching unit 82 when a failure occurs in the DC power supply unit (RF-U) 2, thereby controlling the charging / spare unit (CH- The output side of U) can be connected to the cathode side of the diode DX1, and the output current of the charging / spare unit (CH-U) can flow to the load RL side.

  For example, when one unit of the DC power supply unit (RF-U) fails while the charging / spare unit (CH-U) is charging the storage battery 61 with constant current, the switching unit 82 After switching the output wiring of the charging / spare unit (CH-U) from the anode side to the cathode side of the diode DX1, the DC power supply unit (RF-U) and the charging / spare unit (CH-U) are fixed for a short time. It is possible to switch to power drooping operation.

That is, the voltage (load voltage VL) during constant current charging of the storage battery 61 is regulated by the storage battery voltage (pulled by the storage battery voltage) when the DC power supply unit is in a suspended state. In order to eliminate the state in which the DC power supply unit is in a suspended state and is regulated by the storage battery voltage (the state in which the storage battery voltage is pulled), it is necessary to turn off the diode DX1. However, as long as the charging / spare unit (CH-U) is connected to the anode side of the diode DX1, the current flowing from the charging / spare unit (CH-U) to the load RL passes through the diode DX1. The current flowing from the charging / spare unit (CH-U) to the load RL makes the diode DX1 conductive (forward bias state), so that the diode DX1 cannot be turned off.
Therefore, the switching unit 82 switches the output wiring of the charging / spare unit (CH-U) to the cathode side of the diode DX1, so that the current flowing from the charging / spare unit (CH-U) does not pass through the diode DX1. To do. Further, the load voltage VL is raised by temporarily increasing the output currents of the DC power supply unit (RF-U) and the charging / standby unit (CH-U) with a short-time constant power drooping characteristic. With this increased load voltage VL, a reverse bias voltage is applied to the diode DX1, and the diode DX1 is turned off.

  The conditions for operating the switch unit 83 of the switching unit 82 are as follows. It is assumed that the voltage of the power supply line DCL1 in a steady state, that is, the output voltage of the DC power supply unit (RF-U) is 383 V, and the floating charging voltage (the output voltage of the charging and backup unit (CH-U)) is 374.6 V.

  First, the condition for switching the output wiring (second power line DCL2) of the charging / spare unit (CH-U) from the anode side to the cathode side of the diode DX1 is that the monitoring unit 81 has a DC power unit (RF-U). ) When a failure is detected, or when a storage battery discharge (continuation of storage battery discharge after a constant power drooping operation) is detected. When this condition is met, the monitoring unit 81 switches the output wiring of the charge / spare unit (CH-U) to the cathode side of the diode DX1. Then, after the output wiring of the charging / spare unit (CH-U) is switched to the cathode side of the diode DX1, all the units are switched to the constant power drooping characteristic for a short time, so that the diode DX1 is turned off and the voltage of the power line DCL1 (Load voltage VL) rises to the rated voltage (383 V) or the rated voltage (374.6 V) of the charging and backup unit (CH-U) when one unit fails.

Second, the condition that the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) is switched back from the cathode side to the anode side is that the monitoring unit 81 is connected to the DC power supply unit (RF-U). This is a case where the failure is recovered and 0 (zero) of the output current of the charging and standby unit (CH-U) is detected. When this condition is met, the monitoring unit 81 switches the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) to the anode side of the diode DX1. That is, when this condition is met, the monitoring unit 81 makes the first power supply line DCL1 and the second power supply line DCL2 non-conductive, and the second power supply line DCL2 and the third power supply line DCL3 Between.
This is a case where the failure of the DC power supply unit (RF-U) is restored, and the voltage of the power supply line DCL1 returns to the rated voltage (383 V) of the DC power supply unit (RF-U). In this case, since the output voltage of the charging / spare unit (CH-U) is 374.6 V, no current is output from the charging / spare unit (CH-U). The monitoring unit 81 switches back the switching unit 82 using the fact that the output current of the charging / spare unit (CH-U) becomes 0 (zero).

(Explanation about processing flow in DC power supply of 2nd Embodiment)
FIG. 12 is a flowchart showing a process flow in the DC power supply apparatus 101A according to the second embodiment of the present invention, and shows a process flow performed in the DC power supply apparatus 101A described above. The process shown in this flowchart is a flowchart that can determine whether or not to activate the switching unit 82 at the time of activation regardless of whether or not the DC power supply unit (RF-U) has failed.

In this flowchart, it is assumed that there are the following preconditions.
The DC power supply unit (RF-U) has a constant power drooping characteristic for a short time. Further, the number of operating DC power supply units (RF-U) is n, and the maximum output capacity (Pmax) of the DC power supply unit (RF-U) is 15.2 kW. Further, the voltage Vovat when the discharge of the storage battery 61 when the discharge from the storage battery 61 to the load RL stops is 310.8V. In addition, this value (310.8V) is, for example, when the open-circuit voltage (storage battery voltage when not discharging) when the capacity of the 2V lead acid battery is empty is 1.85V, as described above. This is a value calculated as “1.85 × 168 = 310.8 V” as the open-circuit voltage of the 168 storage batteries. However, this value (310.8 V) is a value that changes according to the storage battery open voltage (storage battery voltage when no load is connected to the storage battery) according to the actual state of charge of the storage battery.

  In addition, the maximum current (rated current Imax0) at the time of constant current droop of the DC power supply unit (RF-U) and the charging / spare unit (CH-U) is 40A. Further, the maximum output current (maximum rated current Imax1) of the DC power supply unit (RF-U) and the charging / spare unit (CH-U) when the constant power is drooped is set to 58A. The constant power droop voltage (Vcp) when the maximum rated current (Imax1) flows when the constant power droops is 260 V (≈15.2 [KW] ÷ 58 [A]). In addition, when the output voltage of the DC power supply unit (RF-U) and the charging / spare unit (CHG) is about 260 V to 380 V, 15.2 KW power can be output, but less than 260 V is a constant current. The output capacity is reduced.

  Under the above preconditions, the condition that the load voltage VL returns to the rated voltage (for example, 383 V) upon power recovery is as follows when the voltage during the constant power drooping operation of the load voltage VL is 260 V or more (1 ).

  PL (load power) <Pmax (15.2 kW) × n (1)

  This is because when the number of DC power supply units (RF-U) to be operated is “n” and the load power PL is less than the total maximum output power “Pmax × n”, the constant power of the DC power supply unit This means that the load voltage VL can be raised to a rated voltage (for example, 383 V) by the drooping operation. That is, it means that the DC power supply unit (RF-U) can cover the power necessary for the load RL.

  Moreover, under the above preconditions, the condition that the load voltage VL returns to the rated voltage (for example, 383 V) at the time of power recovery is as follows when the voltage during the constant power drooping operation of the load voltage VL is less than 260 V (2 ).

  PL (load power) <VL × Imax1 × n (2)

  This is because when the load voltage VL is less than 260 V (≈15.2 KW ÷ 58 A) at the time of power recovery, the load power PL is operated at the load voltage VL (<260 V). When the maximum power “VL × Imax1 × n” that can be supplied from the DC power supply unit is larger than the load power PL, the load voltage is raised to the rated voltage (eg, 383 V) by the constant power drooping operation of the DC power supply unit. It means that you can.

  Further, the condition that the storage battery does not discharge when one DC power supply unit fails is expressed by the following equation (3).

  L / Vobat <Imax0 (40A) × n ′ (3)

  Here, n ′ is the total number of DC power supply units (RF-U) and charging / standby units (CH-U) that are operating normally. This is because, when one DC power supply unit (RF-U) is out of order, the DC power supply unit (RF-U) is (n-1 units) and the charging and standby unit (CH-U) is one unit. After all, the number of operating units is n ′ = n (= n−1 + 1).

  The determination in equation (3) is that the total output current (Imax0 × n) of the DC power supply device 101A is the load current in order to avoid discharging the storage battery 61 when one DC power supply unit (RF-U) fails. It means that it needs to be higher. That is, since the load RL has constant power characteristics, the current increases when the DC system voltage (= load voltage VL) decreases. For this reason, the value on the left side of equation (3), the current value obtained by dividing the load power PL by the voltage Vovat when the storage battery 61 stops discharging, is one DC power supply unit with the current value “(n−1)” on the right side. Storage battery discharge can be avoided if it is equal to or less than the total current value (Imax0 × n) of the maximum output current with the charging / spare unit. In the above equation (3), “Imax0 (40A) × n” is set when the storage battery 61 is not discharged, that is, when the output voltage of the DC power supply unit (RF-U) is restored to the rated voltage. This is because the maximum output currents of the DC power supply unit (RF-U) and the charging / spare unit (CH-U) are reduced to the rated current Imax0 (40 A).

Hereinafter, the flow of processing in the DC power supply apparatus 101A will be described with reference to the flowchart shown in FIG. The process shown in this flowchart is a process that is started when power is restored after a power failure or when a failure occurs in the DC power supply unit (RF-U).
When the DC power supply 101A is activated by power recovery (step S1), the output voltage (load voltage VL) output to the load RL is measured by the voltage sensor VT (step S2). Further, the output current (load current IL) output to the load RL is measured by the load current sensor CT1 (step S3). Next, the monitoring unit 81 detects the total number n of operating DC power supply units (RF-U) operating normally (step S4).

  Further, the monitoring unit 81 calculates the load power PL supplied to the load RL based on the measurement result of the load voltage VL applied to the load RL and the load current IL flowing through the load RL (step S5).

  Next, the monitoring unit 81 determines whether or not the current load voltage VL is 260 V or higher (step S6). This is because when a constant power drooping operation occurs in the DC power supply unit (RF-U), the maximum output of 15.2 KW is output more than an output voltage of 260 V (the output current is 58 A when the output voltage is 260 V). This determination is performed to determine whether or not the DC power supply unit (RF-U) can output the maximum output (15.2 kW).

  If the current load voltage VL is determined to be 260 V or higher in step S6 (step S6: Yes), the monitoring unit 81 returns the voltage when the power is restored according to the above equation (1) (rated voltage ( For example, it is determined whether the voltage can be increased to 383 V) (step S7A). That is, it is determined whether or not n DC power supply units (RF-U) that can be operated can provide power necessary for the load RL.

  If it is determined in step S7A that the voltage returns when power is restored (step S7A: Yes), the process proceeds to step S8, and the DC power supply unit (RF-U) is set to 1 according to the above-described equation (3). In the case of a stand failure, it is determined whether or not the storage battery is discharged (step S8). In order to avoid discharge from the storage battery 61 when one DC power supply unit (RF-U) fails, the DC power supply unit (RF-U) can be used as shown in the above equation (3). This is because the total output current (40 A × n) of the charging / spare unit (CH-U) needs to exceed the load current IL. If there is no failed unit in the DC power supply unit (RF-U), the determination in step S8 can be omitted and the process can proceed to step S9.

  And when it determines with a storage battery not discharging at the time of one DC power supply unit (RF-U) failure in step S8 (step S8: Yes), the present condition is maintained. In other words, the monitoring unit 81 determines that the voltage returns upon power recovery based on the current operating number n of the DC power supply units (RF-U) (step S7A: Yes), and 1 of the DC power supply unit (RF-U). When it determines with the storage battery 61 not discharging at the time of a stand failure (step S8: Yes), the present condition is maintained, without operating the switching part 82. FIG.

  In step S8, when the monitoring unit 81 determines that the storage battery is discharged when one DC power supply unit (RF-U) fails (step S8: No), the process proceeds to step S10. By operating the switching unit 82, the output wiring (second power line DCL2) of the charging / spare unit (CH-U) is connected to the output power line (first power line DCL1).

  In step S7A, when the monitoring unit 81 determines that the output voltage (load voltage VL) does not return to the rated voltage (for example, 383 V) at the time of power recovery (step S7A: No), the process proceeds to step S10. The monitoring unit 81 operates the switching unit 82 to change the output wiring (second power line DCL2) of the charging / spare unit (CH-U) to the output power line (first power line DCL1). Connecting.

  On the other hand, when the monitoring unit 81 determines in step S6 that the current load voltage VL is 260 V or less (step S6: No), that is, the output of the DC power supply unit (RF-U) is 15.2 kW. When the voltage drops below (≈260 V × 58 A), it is determined whether or not the voltage returns to the rated voltage at the time of power recovery according to the above-described equation (2) (step S7B). In step S7B, when the monitoring unit 81 determines that the voltage returns (can increase the voltage to the rated voltage) at the time of power recovery (step S7B: Yes), the process proceeds to step S8, and the above-described (2 ), It is determined whether or not the storage battery is discharged when one DC power supply unit (RF-U) fails (step S8). Note that the processing in step S8 is as described above.

  If it is determined in step S7B that the output voltage (load voltage VL) does not return to the rated voltage at the time of power recovery (step S7B: No), the process proceeds to step S10, and the monitoring unit 81 switches the switching unit 82. Operate.

  In step S10, the monitoring unit 81 operates the switching unit 82 to connect the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) to the cathode side (first power line DCL2) of the diode DX1. Switch to the power line DCL1 side (step S10). Thereafter, the monitoring unit 81 switches the all DC power supply unit (RF-U) and the charging / spare unit (CH-U) to the constant power drooping operation (step S11). Then, after a predetermined time has elapsed (after the constant power drooping operation is completed), the all DC power supply unit (RF-U) and the charging / spare unit (CH-U) return to the constant current drooping operation (step S12).

Next, the monitoring unit 81 measures the output current of the charging / spare unit (CH-U) via the current sensor CT2 (step S13), and the output current I _{CH of the} charging / spare unit (CH-U). It is determined whether or not _−U is 0 (zero) (step S14). That is, the monitoring unit 81 determines whether or not the output voltage (load voltage VL) of the DC power supply unit (RF-U) has risen to the rated voltage. If it is determined in step S14 that the output current I _CH-U is 0 (zero) by the monitoring unit 81 (step S14: Yes), the monitoring unit 81 determines that the faulty DC power supply unit (RF-U ) Is determined (step S15).

  In step S15, when the monitoring unit 81 determines that there is no failed DC power supply unit (RF-U) (step S15: No), the monitoring unit 81 controls the switching unit 82 to charge and charge. The output wiring (second power supply line DCL2) of the spare unit (CH-U) is switched from the cathode side to the anode side of the diode DX1 (step S18), and then the process proceeds to step S1. On the other hand, when the monitoring unit 81 determines in step S15 that there is a failed DC power supply unit (RF-U) (step S15: Yes), the worker replaces the failed unit with a normal unit (step S15: Yes). Step S16). Then, the monitoring unit 81 determines whether or not the DC power supply unit (RF-U) has recovered from the failure by replacing the failed DC power supply unit (RF-U) with a normal unit (step S17). That is, the monitoring unit 81 receives operation state signals from all the DC power supply units (RF-U) and determines whether or not the DC power supply unit (RF-U) is operating normally.

  In step S <b> 17, when the monitoring unit 81 determines that all the DC power supply units (RF-U) are operating normally (step S <b> 17: Yes), the monitoring unit 81 controls the switching unit 82. Then, the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) is switched from the cathode side to the anode side of the diode DX1 (step S18), and then the process proceeds to step S1. On the other hand, if it is determined in step S17 that the failed DC power supply unit (RF-U) has not recovered from the failure (step S17: No), the monitoring unit 81 has failed, for example, after a predetermined time has elapsed. An alarm signal indicating that the DC power supply unit (RF-U) cannot be recovered is output, and the process returns to step S16 again. That is, until the monitoring unit 81 determines that all the DC power supply units (RF-U) are operating normally, the worker performs operations such as replacing the failed unit with a normal unit.

On the other hand, if it is determined in step S14 that the output current I _CH-U is not 0 (zero) by the monitoring unit 81 (step S14: No), that is, the output voltage (load) of the DC power supply unit (RF-U). When the voltage VL) does not rise to the rated voltage (for example, 383 V), the process proceeds to step S19, and the maintenance worker investigates the cause of the malfunction (step S19). The process in step S19 is a process manually performed by a maintenance worker. And when the cause of a malfunction is discovered by the cause investigation in step S19, when this malfunction is eliminated by the maintenance worker (step S20: Yes), the process proceeds to step S13 again. The monitoring unit 81 measures the output current I _CH-U . If the cause of the failure is not resolved in step S20 (step S20: No), the process returns to step S19, and the maintenance worker continuously investigates the cause of the failure.

  According to the above-described processing procedure, when the DC power supply unit (RF-U) has failed after one power failure, the power-up process after the power recovery and when the DC power supply unit (RF-U) has not failed at the time of power-up In this process, it can be avoided that the output voltage of the DC power supply unit (RF-U) cannot be restored to the rated voltage (for example, 383 V). That is, when the diode DX1 cannot be turned off, the monitoring unit 81 uses the switching unit 82 to switch the output wiring (second power supply line DCL2) of the charging and standby unit (CH-U) to the cathode side of the diode DX1. It is possible to reliably turn off the diode DX1 and prevent the discharge current from continuously flowing from the storage battery 61 to the load RL.

  The first procedure in the present invention corresponds to the processing from step S2 to step S5 in the flowchart shown in FIG. The second procedure in the present invention corresponds to the process in step S6, the third procedure in the present invention corresponds to the process in step S7A, and the fourth procedure in the present invention corresponds to the process in step S7B. Correspond. The fifth procedure in the present invention corresponds to the process in step S10, the sixth procedure in the present invention corresponds to the process in step S8, and the seventh procedure in the present invention corresponds to the process in step S10. Correspond.

Next, an example will be described in which the monitoring unit 81 in the present embodiment controls the switching unit 82 to turn off the diode DX1 with respect to the time charts at the time of occurrence of the abnormality shown in FIGS. 22 and 23 described above.
The time charts shown in FIGS. 13 and 14 are the same as the time charts shown in FIGS. 22 and 23, but the output voltage of the DC power supply unit (RF-U) becomes the rated voltage (383V or 374.6V) because the diode DX1 does not turn off. ), I.e., when the current continues to flow from the storage battery 61 to the load RL (when the diode DX1 cannot be turned off), the switching unit 82 causes the output wiring of the charging and standby unit (CH-U) ( This shows an example in which the second power supply line DCL2) is switched to the cathode side (first power supply line DCL1 side) of the diode DX1. That is, an example is shown in which the switching unit 82 is operated at time t6 after the constant current drooping operation of the DC power supply unit (RF-U) is started from time t5.

  In the example shown in FIGS. 13 and 14, in the constant current drooping operation period after time t4 (after executing the normal constant power drooping operation), the monitoring unit 81 executes the process of the flowchart shown in FIG. In this example, the switch switching operation by the switching unit 82 is started from time t6. The start timing or the start condition of the processing of the flowchart shown in FIG. 12 is not limited to the time of activation, but can be arbitrary such as starting with the occurrence of a power recovery signal or a failure signal of the DC power supply unit (RF-U) as a trigger. It can be set to.

  And the example shown in FIG. 13 is an example in case there is no unit which failed in DC power supply unit (RF-U), and the storage battery voltage at the time of power recovery is 200V. In the example shown in FIG. 13, normal startup processing is performed from time t1 to t6 after power recovery as in the case shown in FIG. 22, and switching operation is performed by the switching unit 82 at time t6.

At time t6, the monitoring unit 81 controls the switching unit 82 to connect the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) to the cathode side of the diode DX1. At the same time, the DC power supply unit (RF-U) and the charge / spare unit (CH-U) start a constant power drooping operation for a short time. As a result, the output current I _CH-U of the charging / spare unit (CH-U) flows to the load RL side, and the diode DX1 is turned off.
After time t7, the output voltage of the DC power supply unit (RF-U) returns to the rated voltage (383 V), and the output current I _RF-U of the DC power supply unit (RF-U) becomes 261.1A. Further, the output current I _CH-U of the charge / spare unit (CH-U) is 0 (zero).

  The example shown in FIG. 14 is an example in which one unit of the DC power supply unit (RF-U) fails and the storage battery voltage at the time of power recovery is 250V. In the example shown in FIG. 14, normal startup processing is performed from time t1 to t6 after power recovery, as in the case shown in FIG. 23, and switching operation is performed by the switching unit 82 at time t6.

At time t6, the monitoring unit 81 connects the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) to the cathode side of the diode DX1 by the switching unit 82. At the same time, the DC power supply unit (RF-U) and the charge / spare unit (CH-U) start a constant power drooping operation for a short time. As a result, the output current I _CH-U of the charging / spare unit (CH-U) flows to the load RL side, and the diode DX1 is turned off.
Then, after time t7, the load voltage VL returns to the rated voltage (374.6V) of the charging and standby unit (CH-U), and the output current I _RF-U of the DC power supply unit (RF-U) is 227A. It becomes. Further, the output current I _CH-U of the charging / spare unit (CH-U) is 40A. Note that the load voltage VL becomes 274.6 V due to the constant current drooping operation of the charging / spare unit (CH-U). The cathode voltage Vdxk (storage battery voltage) of the diode DX1 is about 310 V (voltage when the storage battery is opened).

As described above, in the DC power supply device 101A according to the second embodiment of the present invention, it is possible to start up with specifications (for example, selection of switching elements and thermal design specifications) required during normal operation. In this case, a current higher than the rated current during normal operation can be supplied to the load RL. Further, at the time of starting, the diode DX1 is not turned off, and the output voltage of the DC power supply unit (RF-U) is not restored to the rated voltage, that is, the discharge current from the storage battery 61 to the load RL is prevented from continuing to flow. it can.
Note that the switching unit 82 eliminates the FETa shown in FIG. 15 from the configuration of the switch unit 83 using two NCh-type MOSFET elements (FETa and FETb) shown in FIG. The cathode side terminal may be directly connected to the power supply line DCL1. In this case, in the switching unit 82, the diode D1 is configured as a first switching element that switches the first power supply line DCL1 and the second power supply line DCL2 between conduction and non-conduction. In this configuration, for example, when the diode DX1 is not turned off and the load voltage VL is reduced at the time of start-up at the time of power recovery, the monitoring unit 81 controls the switching unit 82 (relay contact Ryb), thereby charging and charging. The connection between the output side of the spare unit (CH-U) and the storage battery 61 can be disconnected, and the output current of the charging / spare unit (CH-U) can be passed to the load RL side via the diode D1. As a result, the DC power supply device 101A can raise the load voltage VL. In addition, when the load voltage VL returns to the rated voltage (383 V) of the DC power supply unit (RF-U), the output current of the charging / spare unit (CH-U) becomes 0 (zero) and the diode D1 is turned off. Thus, the first power supply line DCL1 and the second power supply line DCL2 can be made non-conductive.

  Note that the switching unit 82 shown in FIG. 9 can be changed to a switching unit 82A shown in FIG. This switching unit 82A is an example in which the relay contact Ryc is inserted between the second power supply line DCL2 and the second power supply line DCL3. In the example shown in FIG. 16, the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) is connected to the anode side of the diode DX1. One end of the relay contact Ryc (make contact) is connected to the anode side of the diode DX1, and the other end of the relay contact Ryc (make contact) is connected to the output terminal of the storage battery 61 via the third power line DCL3. The

  With the configuration of the switching unit 82A, for example, when the diode DX1 is not turned off and the load voltage VL is reduced at the time of start-up at power recovery, the monitoring unit 81 controls the switching unit 82A (relay contact Ryc). Thus, the connection between the output side of the charge / spare unit (CH-U) and the storage battery 61 can be disconnected. As a result, the output current of the charging / spare unit (CH-U) can flow to the load RL side via the diode DX1, and the load voltage VL can be raised by disconnecting the storage battery 61 from the circuit.

  Although the second embodiment of the present invention has been described above, the correspondence relationship between the present invention and the second embodiment will be supplementarily described. A DC power supply apparatus according to the present invention corresponds to the DC power supply apparatus 101A shown in FIG. 9, and a DC power supply unit according to the present invention corresponds to a DC power supply unit (RF-U). In addition, the charge / spare unit in the present invention corresponds to the charge / spare unit (CH-U), and the storage battery in the present invention corresponds to the storage battery 61 in the power storage device 60. The monitoring unit in the present invention corresponds to the monitoring unit 81, and the switching unit in the present invention corresponds to the switching unit 82. The first power supply line in the present invention corresponds to the first power supply line DCL1, the second power supply line in the present invention corresponds to the second power supply line DCL2, and the third power supply line in the present invention. Corresponds to the third power supply line DCL3.

  The diode in the present invention corresponds to the diode DX1, and the first switching element in the present invention corresponds to the relay contact Rya (or the FETa and the diode D1, or the diode D1), and the second switching in the present invention. The element corresponds to the relay contact Ryb (or FETb and diode D2). The rated current in the present invention corresponds to the maximum output current (rated current Imax0) during the constant current drooping operation, and the maximum rated current in the present invention corresponds to the maximum output current (maximum rated current Imax1 in the constant power drooping operation). ) Corresponds.

  In the above embodiment, the DC power supply device 101A performs a constant current drooping operation that limits the output current to a predetermined value, and outputs an output voltage when it is necessary to output a current greater than a predetermined value to the load RL. Supply power to load RL when input power is no longer supplied to multiple DC power supply units (RF-U) and DC power supply units (RF-U) that perform a drooping operation that causes the output current to drop When either one of the storage battery 61 and the DC power supply unit (RF-U) fails, the storage battery 61 is used as a substitute unit for the failed DC power supply unit (RF-U) and to the storage battery 61 during normal operation. The charge / spare unit (CH-U) for charging and the output terminals of each DC power supply unit (RF-U) are connected in common and power is supplied to the load RL. The first power line (DCL1), the second power line (DCL2) connected to the output terminal of the charging and standby unit (CH-U), and the third power line connected to the output terminal of the storage battery (DCL3) and a switching unit 82 that switches between conduction and non-conduction of current between, and a monitoring unit 81 that monitors the operating state of the DC power supply unit (RF-U) and controls the switching unit 82. When the direct current power supply unit (RF-U) performs the drooping operation, the monitoring unit 81 controls the switching unit 82 so that the first power supply line (DCL1) and the second power supply line (DCL2) are connected. Conduction is performed, and the first and second power supply lines (DCL1 and DCL2) and the third power supply line (DCL3) are disconnected.

In the case of the DC power supply device 101A having such a configuration, for example, the DC power supply unit (RF-U) performs a drooping operation to droop the output voltage at the time of start-up at the time of power recovery, and then the DC power supply unit (RF When the voltage at which -U) droops cannot be restored to the output voltage (rated voltage) during normal operation, the monitoring unit 81 controls the switching unit 82 to output the second wiring (second-charge) of the charging and standby unit (CH-U). And the load wiring (first power line DCL1) connected to the load RL. Further, the switching unit 82 makes the connection between the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) and the third power supply line DCL3 connected to the storage battery 61 non-conductive. Further, the switching unit 82 makes the output wiring (first power line DCL1) connected to the load RL non-conductive between the third power line DCL3 connected to the storage battery 61. That is, the output current of the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) is directly supplied to the load wiring (first power supply line DCL1), and the load wiring (first power supply line DCL1) is passed. The line RL1 and the storage battery 61 are disconnected by disconnecting the line DCL1) from the storage battery 61.
As a result, the DC power supply device 101 </ b> A remains in the specifications required during normal operation (for example, switching element selection and thermal design specifications), for example, at the time of start-up exceeding the rated current during normal operation. Current can be supplied to the load, and the output voltage drooped by the drooping operation can be reliably raised to the output voltage (rated voltage) during normal operation.

Further, in the above embodiment, the load RL is a load having a constant power characteristic, and the DC power supply unit (RF-U) and the charging / spare unit (CH-U) are started up and when a predetermined instruction is given. In addition, when it is necessary to supply a current of a predetermined value (rated current Imax0) or more to the load RL, a constant power drooping operation is performed to droop the output voltage so that the product of the output current and the output voltage is constant. A current equal to or higher than a predetermined value (rated current Imax0) is supplied to the load.
As a result, even when it is necessary to supply a current of a predetermined value (rated current Imax0 during normal operation) or more to the load RL having a constant power characteristic, such as when the DC power supply device 101A is started up, this current is loaded. While being able to supply to RL, the output voltage drooped by drooping operation can be reliably raised to the output voltage (rated voltage) during normal operation.

In the above embodiment, the monitoring unit 81 controls the switching unit 82 when at least one DC power supply unit (RF-U) has failed, and controls the first power supply line (DCL1) and the second power supply. The line (DCL2) is made conductive, and the first and second power lines (DCL1 and DCL2) and the third power line (DCL3) are made non-conductive.
As a result, when the DC power supply unit (RF-U) breaks down, for example, at the time of start-up, the current exceeding the rated current during normal operation can be supplied to the load, and the output voltage drooped by the drooping operation Can be reliably started up to the output voltage (rated voltage) during normal operation.

In the above embodiment, the monitoring unit 81 detects the load voltage of the load RL and the load current IL flowing through the load RL, and the load voltage VL, the load current IL, and the DC power supply unit (RF-U). When the DC power supply unit (RF-U) that performs the drooping operation determines whether or not the drooping output voltage can be restored to the output voltage during normal operation based on the operation state of In addition, the switching unit 82 is controlled so that the first power supply line (DCL1) and the second power supply line (DCL2) are electrically connected, and the first and second power supply lines (DCL1 and DCL2) are connected to the third power supply line (DCL1). The power supply line (DCL3) is made non-conductive.
In the case of the DC power supply device 101A having such a configuration, at the time of startup or the like, the monitoring unit 81 causes the DC power supply unit (RF-U) that performs the drooping operation to use the drooped output voltage as the output voltage during normal operation ( It is determined whether or not it can be recovered to the rated voltage), and when it is determined that it cannot be recovered, the switching unit 82 is controlled to conduct between the first power supply line (DCL1) and the second power supply line (DCL2). The first and second power supply lines (DCL1 and DCL2) and the third power supply line (DCL3) are made non-conductive.
As a result, when the DC power supply unit (RF-U) that performs the drooping operation cannot restore the drooping output voltage to the output voltage (rated voltage) during normal operation, the monitoring unit 81 controls the switching unit 82. The output voltage of the DC power supply unit (RF-U) can be reliably raised to the output voltage (rated voltage) during normal operation.

In the above embodiment, the determination as to whether or not the DC power supply unit (RF-U) performed in the monitoring unit 81 can restore the drooped output voltage to the output voltage (rated voltage) during normal operation is performed. It is executed at any or all timings when a failure unit occurs in the DC power supply unit (RF-U), or when a predetermined instruction is given at the time of start-up after electricity.
With the DC power supply device 101A having such a configuration, the DC power supply device 101A monitors at a desired timing such as when a failure unit occurs in the DC power supply unit (RF-U) at the time of startup after power recovery. The unit 81 determines whether or not the drooped output voltage can be restored to the output voltage (rated voltage) during normal operation. Thus, the DC power supply device 101A can reliably raise the output voltage of the DC power supply unit (RF-U) to the output voltage (rated voltage) during normal operation.

In the above-described embodiment, the rated output voltage of the charging / spare unit (CH-U) is set lower by a predetermined voltage than the rated output voltage of the DC power supply unit (RF-U).
In the DC power supply device 101A having such a configuration, when the output voltage of the DC power supply unit (RF-U) rises to the output voltage (rated voltage) during normal operation, the charging / spare unit (CH-U) loads the load RL. The power supply to can be automatically stopped.

In the above-described embodiment, the monitoring unit 81 controls the switching unit 82 to make the first power line (DCL1) and the second power line (DCL2) conductive, and the first and second power lines When it is detected that the output current of the charging and standby unit (CH-U) has become 0 after the non-conduction between the power supply lines (DCL1 and DCL2) and the third power supply line (DCL3), The first power supply line (DCL1) and the second power supply line (DCL2) are made non-conductive, and the second power supply line (DCL2) and the third power supply line (DCL3) are made conductive.
As a result, the supply of current from the charging / spare unit (CH-U) to the load RL is stopped, that is, the output voltage of the DC power supply unit (RF-U) is the output voltage (rated voltage) during normal operation. And the connection destination of the charging / spare unit (CH-U) can be switched from the load side (first power line) to the storage battery side (third power line).

In the above embodiment, the switching unit 82 includes the diode DX1 whose anode side is connected to the storage battery 61 via the third power line (DCL3) and whose cathode side is connected to the first power line (DCL1). The first switching element (Rya) for switching the first power supply line (DCL1) and the second power supply line (DCL2) between conduction and non-conduction, the second power supply line (DCL2), and the third power supply line (DCL3) and a second switching element (Ryb) that switches between conduction and non-conduction.
In the case of the DC power supply device 101A having such a configuration, when the DC power supply unit (RF-U) that has performed the drooping operation cannot restore the drooping output voltage to the output voltage (rated voltage) during normal operation. The monitoring unit 81 controls the switching unit 82 to switch the connection destination of the output wiring (second power supply line DCL2) of the charging / spare unit (CH-U) from the anode side to the cathode side of the diode DX1. Thus, the diode DX1 is turned off (non-conducting) by biasing the diode DX1 in the reverse direction.
As a result, the monitoring unit 81 controls the switching unit 82 when the DC power supply unit (RF-U) that has performed the drooping operation cannot recover the drooping output voltage to the output voltage (rated voltage) during normal operation. Thus, the output voltage of the DC power supply unit (RF-U) can be reliably raised to the output voltage (rated voltage) during normal operation.

  Although the embodiments of the present invention have been described above, the DC power supply apparatus of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. Of course.

10, 10A, 10B, 10C ... DC power supply units 20, 20A, 20B, 20C ... Power factor correction circuit 30 ... PFC control unit 40, 40A ... D / D control circuit 41 ... D / D controller 42 ... drooping reference signal generator 50, 50A, 50B, 50C ... DC / DC converter circuit 51 ... output constant voltage control circuit 52 ... output constant current control circuit (secondary droop circuit )
53 ... Instantaneous overcurrent control circuit (primary drooping circuit)
54 ... Rectifier circuit unit 60 ... Power storage device 61 ... Storage battery 71 ... Voltage amplification unit 81 ... Monitoring unit 82, 82A ... Switching unit 83 ... Switch unit 100 ... DC Power system,
101, 101A, 101B ... DC power supply devices CT, CT1, CT2, CT3 ... current sensor DCL1 ... first power supply line DCL2 ... second power supply line DCL3 ... third power supply line Rya: Relay contact (first switching element)
Ryb ... relay contact (second switching element)
DX1 ... Diode Imax0 ... Rated current Imax1 ... Maximum rated current VT ... Voltage sensor

Claims (10)

Performs a constant current drooping operation that limits the output current to a predetermined value, and performs a drooping operation that increases the output current by drooping the output voltage when it is necessary to output a current greater than the predetermined value to the load. A plurality of DC power supply units;
A storage battery for supplying power to the load when input power is no longer supplied to the DC power supply unit;
When one of the DC power supply units fails, it is used as a replacement unit for the failed DC power supply unit, and during normal operation, a charging / spare unit that charges the storage battery,
A first power line for commonly connecting the output terminals of the DC power supply unit and supplying power to the load; a second power line connected to the output terminal of the charging and standby unit; and A switching unit that switches between conduction and non-conduction between the third power supply line connected to the output terminal,
While monitoring the operating state of the DC power supply unit, a monitoring unit for controlling the switching unit,
With
When the DC power supply unit performs the drooping operation, the monitoring unit controls the switching unit to establish conduction between the first power supply line and the second power supply line. A DC power supply device characterized in that the second power supply line and the third power supply line are made non-conductive. The load is a load having a constant power characteristic,
When the DC power supply unit and the charge / spare unit need to supply a current equal to or greater than the predetermined value to the load at start-up and when a predetermined instruction is given, an output current and an output voltage The DC power supply device according to claim 1, wherein a constant power drooping operation for drooping an output voltage is performed so that a product of the two is constant, and a current equal to or greater than the predetermined value is supplied to a load. The monitoring unit
When at least one DC power supply unit fails, the switching unit is controlled so that the first power supply line and the second power supply line are electrically connected, and the first and second power supply lines are connected. The DC power supply device according to claim 1, wherein the third power supply line is made non-conductive. The monitoring unit
Detecting a load voltage of the load and a load current flowing through the load;
The load voltage, the load current, the operating state of the DC power supply unit,
The DC power supply unit that performs the drooping operation determines whether or not the drooping output voltage can be restored to the output voltage at the time of normal operation. The first power supply line and the second power supply line are made conductive, and the first and second power supply lines and the third power supply line are made nonconductive. The direct-current power supply device according to any one of claims 1 to 3. The determination whether the DC power supply unit performed in the monitoring unit can restore the drooped output voltage to the output voltage during normal operation,
5. The process according to claim 4, wherein the process is executed at any or all timings when a failure unit occurs in the DC power supply unit or when a predetermined instruction is given at the time of startup after power recovery. DC power supply. The rated output voltage of the charging / spare unit is
6. The DC power supply device according to claim 1, wherein the DC power supply device is set lower by a predetermined voltage than a rated output voltage of the DC power supply unit. The monitoring unit
By controlling the switching unit, the first power supply line and the second power supply line are made conductive, and the first and second power supply lines and the third power supply line are made nonconductive. When it is detected that the output current of the charging / spare unit becomes 0,
The first power supply line and the second power supply line are made non-conductive, and the second power supply line and the third power supply line are made conductive. The DC power supply device according to any one of 6. The switching unit is
A diode whose anode side is connected to the storage battery via the third power line and whose cathode side is connected to the first power line;
A first switching element that switches the first power supply line and the second power supply line between conduction and non-conduction;
A second switching element that switches the second power supply line and the third power supply line between conduction and non-conduction;
The DC power supply device according to any one of claims 1 to 7, further comprising: The monitoring unit
The load voltage PL (= VL × IL) is calculated by detecting the load voltage VL and the load current IL of the load, and the number n of normally operating units among the DC power supply units is detected. The first procedure;
Based on the maximum rated current Imax1 in the constant power drooping operation of the DC power supply unit and the charging / spare unit, the constant power drooping voltage Vcp when the maximum rated current Imax1 flows, and the rated current Imax0 in the constant current drooping operation. In addition,
The load voltage VL is
VL ≧ Vcp,
A second procedure for determining whether or not the condition is satisfied,
In the second procedure, when it is determined that the load voltage VL is equal to or higher than the constant power droop voltage Vcp (VL ≧ Vcp), the load power PL is
PL <Vcp × Imax1 × n,
A third procedure for determining whether or not the condition is satisfied,
In the second procedure, when it is determined that the load voltage VL is less than the constant power droop voltage Vcp (VL <Vcp), the load power PL is
PL <VL × Imax1 × n,
A fourth procedure for determining whether or not the condition is satisfied,
When it is determined in the third procedure that the condition “PL> Vcp × Imax1 × n” is satisfied, or in the fourth procedure, it is determined that the condition “PL> VL × Imax1 × n” is satisfied. In this case, by controlling the switching unit, the first switching element makes the first power supply line and the second power supply line conductive, and the second switching element makes the second switching element conductive. A fifth procedure for non-conduction between a power line and the third power line;
The DC power supply device according to claim 8, wherein: The monitoring unit
When it is determined that the condition “PL <Vcp × Imax1 × n” is satisfied in the third procedure, or when the condition “PL <VL × Imax1 × n” is determined in the fourth procedure And when one of the DC power supply units has failed,
Based on the voltage Vobat when the discharge of the storage battery is stopped,
PL / Vovat <Imax0 × n ′ (where n ′ is the total number of normally operating DC power supply units and charging / spare units),
A sixth procedure for determining whether or not this condition is satisfied;
When it is determined by the sixth procedure that the condition “PL / Vobat> Imax0 × n ′” is satisfied, the first switching element and the second power supply line are Between the second power supply line and the third power supply line by the second switching element,
The DC power supply device according to claim 9, wherein:

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