JP5615046B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply apparatus in which a plurality of power supply units are connected in parallel.

  Conventionally, in a power supply device, a technique is known in which a plurality of power supply units are connected in parallel, and the efficiency of the power supply device is improved by operating or stopping the power supply unit according to an increase or decrease in output current flowing to a load.

  In Patent Document 1, a plurality of power supply units connected in parallel are configured such that power is supplied in parallel to the control means in the power supply unit from the power supply unit and another power supply unit. Even if an abnormality occurs in the power source, a technique that can be notified to the outside by the control means is described.

JP 2001-178134 A

  However, the conventional so-called stop-type power supply device that operates or stops the power supply unit according to the increase or decrease of the output current has the following problems (1) and (2).

  (1) Since the alarm circuit of each power supply unit does not operate when the power supply unit is stopped, a failure that occurred when the power supply unit is stopped cannot be detected. When the power supply unit resumes operation, the alarm circuit is activated and a failure is recognized only at that time.

  (2) When an erroneous control signal is sent to the power supply unit due to a failure of the monitoring unit, there is a concern that the system of the power supply device may be stopped by stopping a plurality of power supply units.

A power supply device according to a first aspect of the present invention includes a plurality of power supply units connected in parallel to supply output voltage and output current to an external load, and the plurality of power supply units connected in parallel to the external A current measuring unit that measures the output current flowing through the load, and a monitoring unit that gives an operation instruction or a standby instruction to each of the plurality of power supply units according to the measurement result of the output current, and the monitoring unit includes: When the output current decreases, the standby instruction is given to a larger number of the power supply units and the operation instruction is issued to a smaller number of the power supply units, and when the output current increases, the larger number of the power supply units. The operation instruction is given to a power supply unit and the standby instruction is issued to a smaller number of the power supply units, and the power supply unit generates a first output voltage for driving the external load according to the operation instruction from the monitoring unit. And force, by the standby instruction from the monitoring unit, the first output voltage lower than the one in which and for outputting a second higher output voltage than the external load can drive lower limit voltage.
The power supply unit generates an output voltage based on the output voltage detection unit that detects a single output voltage that is a voltage that the power supply unit outputs alone, and the operation instruction and the standby instruction from the monitoring unit. In response to the switching signal, a voltage switching unit that switches a reference voltage, a constant voltage control unit that feeds back a difference between the single output voltage and the reference voltage, and controls the single output voltage to be constant, and the output voltage and An output terminal that outputs the output current; and a rectifier connected to the output terminal to prevent backflow from the output terminal into the power supply unit, wherein the output voltage detection unit includes a first of the output terminals. If the terminal voltage is lower than or equal to the second terminal voltage obtained by subtracting the voltage corresponding to the decrease by the rectifier from the voltage of the terminal opposite to the output terminal of the rectifier, the first terminal voltage is Serial detected as a single output voltage, if the first terminal voltage is higher than the second terminal voltage, and detects the second terminal voltage as the single output voltage.
A power supply device according to a second aspect of the present invention includes a plurality of power supply units that are connected in parallel and supply output voltage and output current to an external load, and the output that flows from the plurality of power supply units connected in parallel to the external load. A current measuring unit that measures current, and a monitoring unit that gives an operation instruction or a standby instruction to each of the plurality of power supply units according to the measurement result of the output current, and the monitoring unit has the output current When the number decreases, the standby instruction is given to a larger number of the power supply units, and the operation instruction is given to a smaller number of the power supply units. The standby instruction is issued to a smaller number of the power supply units, and the power supply unit outputs a first output voltage for driving the external load according to the operation instruction from the monitoring unit, and the monitoring unit By the standby instruction from parts, the first output lower than the voltage, in which and to output the higher than the external load drivable lower voltage second output voltage.
The power supply unit detects a single output voltage that is a voltage output by the power supply unit as a single unit, and outputs an output for switching the amplification factor of the single output voltage according to the operation instruction and the standby instruction from the monitoring unit. A voltage detection unit, a reference voltage output unit that outputs a reference voltage, and a feedback of a difference between the single output voltage amplified by the output voltage detection unit and the reference voltage, thereby controlling the single output voltage constant. A constant voltage control unit; an output terminal that outputs the output voltage and the output current; and a rectifier connected to the output terminal to prevent backflow from the output terminal into the power supply unit, and the output voltage detection The first terminal voltage of the output terminal is less than the second terminal voltage obtained by subtracting the voltage of the rectifier from the voltage at the terminal opposite to the output terminal of the rectifier. If low or equal, the first terminal voltage is detected as the single output voltage, and if the first terminal voltage is higher than the second terminal voltage, the second terminal voltage is detected as the single output voltage. It is detected as an output voltage.

The power supply device of the present invention has the following effects (A) and (B).
(A) By operating the number of power supply units corresponding to the output current at the first output voltage, the output capacity ratio of the power supply units in the operating state is improved, and the efficiency of the power supply device is improved. In addition, the power supply unit in the standby state continues to operate at the second output voltage and can detect a failure even in the standby state.

  (B) Even when the monitoring unit of the power supply device fails and the power supply unit is instructed to erroneously enter the standby state, the second output voltage can be supplied from the power supply device to the load, and the system is stopped. Is not reached. Therefore, a highly reliable power supply device can be provided.

FIG. 1 is a schematic configuration diagram illustrating a power supply device according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing the power supply unit of FIG. FIG. 3 is a circuit diagram showing the voltage detection circuit of FIG. FIG. 4 is a circuit diagram showing the reference voltage circuit of FIG. FIG. 5 is a timing chart showing the operation of the power supply unit of FIG. FIG. 6 is a flowchart showing the operation of the power supply device according to the first embodiment of the present invention. FIG. 7 is a diagram illustrating the constant voltage accuracy of the power supply device according to the first embodiment of the present invention. FIG. 8 is a diagram showing the efficiency characteristics of the power supply device according to the first embodiment of the present invention and the conventional example. FIG. 9 is a diagram illustrating a capacity ratio and the number of units operated for one unit of the power supply device according to the first embodiment of the present invention. FIG. 10 is a diagram illustrating the operation number control and the measurement result of the current measurement unit in the first embodiment of the present invention. FIG. 11 is a diagram illustrating a failure event of the power supply device according to the first embodiment of the present invention and the conventional example. FIG. 12 is a schematic configuration diagram illustrating a power supply unit according to the second embodiment of the present invention. FIG. 13 is a circuit diagram showing the voltage detection switching circuit of FIG. FIG. 14 is a schematic configuration diagram showing a power supply device according to the third embodiment of the present invention. FIG. 15 is a schematic configuration diagram illustrating a power supply device according to a fourth embodiment of the present invention.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIGS. 1A and 1B are schematic configuration diagrams showing a power supply device according to a first embodiment of the present invention. FIG. 1A shows the entire power supply apparatus 10, and FIG. 1B shows between the monitoring unit 30 and the power supply unit 20.

  When the input voltage Vin is input, the power supply device 10 has a function of outputting the output voltage Vout and supplying the output voltage Vout to the load 100. The power supply apparatus 10 includes a plurality of power supply units 20 (= 20-1, 20-2,..., 20-n) that are connected in parallel and supply output voltage and output current to the load 100; A monitoring unit 30 that monitors the state of the power supply device 10, a bus 31 that connects the monitoring unit 30 and the plurality of power supply units 20, and a current measurement that measures an output current Iout flowing from the power supply device 10 to the load 100. Part 40.

  An input terminal of the power supply device 10 is connected to the input side of each power supply unit 20, and an input voltage Vin is applied. An output terminal of the power supply device 10 is connected to the output side of each power supply unit 20 via the current measuring unit 40. The current measuring unit 40 is connected to the monitoring unit 30 and sends out the measurement result of the output current Iout. The monitoring unit 30 and the plurality of power supply units 20 are connected to each other via a bus 31 so that they can communicate with each other.

  The monitoring unit 30 includes a power supply unit control unit 32 that transmits a command to each power supply unit 20 and a power supply unit failure detection unit 33 that detects a failure of each power supply unit 20 and takes measures. Each power supply unit 20 switches a single output voltage Vout1 of the power supply unit 20 based on a central processing unit (hereinafter referred to as “CPU”) 21 that controls the power supply unit 20 and an output voltage switching signal Vsel from the CPU 21. The constant voltage control circuit 23 and an alarm circuit 22 that is a failure detection unit that transmits a failure detection signal Verr when a failure of the power supply unit 20 is detected during operation and standby. The monitoring unit 30 transmits an output voltage switching command Bsel to each power supply unit 20 via the bus 31 according to the measurement result of the output current Iout. Further, when receiving the failure detection information Berr from each power supply unit 20 via the bus 31, the monitoring unit 30 performs a corresponding failure detection process.

  The power supply unit control unit 32 and the power supply unit failure detection unit 33 of the monitoring unit 30 are connected to the CPU 21 of each power supply unit 20 via the bus 31. The CPU 21 is connected to the alarm circuit 22 and the constant voltage control circuit 23.

FIG. 2 is a schematic configuration diagram showing the power supply unit of FIG.
The power supply unit 20 includes a CPU 21 that controls the power supply unit 20, an alarm circuit 22 and a constant voltage control circuit 23 connected to the CPU 21, a transformer T1, and a switching element SW1 that is turned on / off by a drive signal Vdrv. And diodes D1, D2, D3, an inductor L1, and a polar capacitor C1. The power supply unit 20 is connected to the monitoring unit 30 via the bus 31. The bus 31 connects the CPU 21 of the power supply unit 20 and the monitoring unit 30 so that they can communicate with each other.

  The constant voltage control circuit 23 is a circuit that controls the single output voltage Vout1 of the power supply unit 20 to be constant. The constant voltage control circuit 23 switches the reference voltage Vref by the voltage detection circuit 25 that detects the single output voltage Vout1 that is a voltage output by the power supply unit 20 and outputs the detection voltage Vdet, and the output voltage switching signal Vsel. A reference voltage circuit 24 that is a voltage switching unit, an error amplification circuit 26 that amplifies a voltage difference between the detection voltage Vdet and the reference voltage Vref and outputs an error voltage Vdif, and is driven by the switching element SW1 based on the error voltage Vdif. And a drive signal forming circuit 27 that outputs a signal Vdrv. The constant voltage control circuit 23 is a constant voltage control unit that feeds back a difference between the single output voltage Vout1 and the reference voltage Vref and controls the single output voltage Vout1 to be constant.

  Input terminals Vin1p and Vin1m of the power supply unit 20 are connected in series to the primary winding of the transformer T1 and the switching element SW1 through an element group (not shown). The secondary winding of the transformer T1 is connected to a rectification output circuit that rectifies the AC output of the transformer T1.

  The rectified output circuit includes diodes D1, D2, and D3, an inductor L1, and a polar capacitor C1. The secondary winding of the transformer T1 is connected to the rectification output circuit. Output terminals Vout1p and Vout1m of the power supply unit 20 are connected to the output side of the rectification output circuit.

  The diode D1 of the rectification output circuit is connected to the secondary winding of the transformer T1 in the forward direction. The cathode terminal of the diode D1 is connected to the cathode terminal of the diode D2, and the anode terminal of the diode D2 is connected to the ground GND. The cathode terminal of the diode D1 is connected to the positive electrode side of the polar capacitor C1 via the inductor L1, and further connected to the output terminal Vout1p via the diode D3 connected in the forward direction. The ground GND of the rectification output circuit is connected to the output terminal Vout1m.

  The anode terminal and the cathode terminal of the diode D3 and the ground GND of the rectification output circuit are connected to the voltage detection circuit 25. The node ND-D3A is an anode terminal of the diode D3. Node ND-D3C is a cathode terminal of diode D3.

  The voltage detection circuit 25 measures the voltage Va of the anode terminal (= ND−D3A) and the voltage Vc of the cathode terminal (= ND−D3C) of the diode D3, so that the power supply unit 20 outputs a single output. A detection voltage Vdet corresponding to the voltage Vout1 is output.

  The error amplification circuit 26 is a circuit that amplifies the voltage difference between the reference voltage Vref and the detection voltage Vdet and outputs an error voltage Vdif. The error amplifier circuit 26 includes an operational amplifier circuit (hereinafter referred to as “op-amp”) AMP1 and resistors R1 and R2. The detection voltage Vdet is input to the non-inverting input terminal of the operational amplifier AMP1, and the reference voltage Vref is input to the inverting input terminal via the resistor R1. Further, a resistor R2 is connected between the inverting input terminal and the output terminal of the operational amplifier AMP1.

FIG. 3 is a circuit diagram showing the voltage detection circuit of FIG.
The voltage detection circuit 25 is an output voltage detection unit, and outputs a detection voltage Vdet corresponding to a single output voltage Vout1 that is a voltage output by the power supply unit 20 as a single unit. The voltage detection circuit 25 includes resistors R10, R11, R12, R13, R14, and R15, and diodes D10 and D11. The voltage detection circuit 25 is connected to the node ND-D3A (= the anode terminal of the diode D3), the node ND-D3C (= the cathode terminal), and the ground GND. The anode voltage Va is input from the node ND-D3A, and the cathode voltage Vc is input from the node ND-D3C. An error amplification circuit 26 is connected to the output terminal of the voltage detection circuit 25.

  The node ND-D3A is connected to the ground GND through a diode D10 connected in the forward direction and resistors R10 and R15 connected in series. The diode D10 has a characteristic in which the forward voltage drop is equal to or very close to that of the diode D3. The node ND-D3C is connected to the ground GND via resistors R11, R12, R13, and R14 connected in series. Furthermore, a diode D11 is connected in the forward direction between the resistors R11 and R12 and between the resistors R10 and R15. The detection voltage Vdet is output from between the resistors R13 and R14. The detection voltage Vdet is a voltage corresponding to the single output voltage Vout1 output by the power supply unit 20 as a single unit, and is input to the error amplification circuit 26.

FIG. 4 is a circuit diagram showing the reference voltage circuit of FIG.
The reference voltage circuit 24 is a reference voltage output unit that outputs a reference voltage Vref. The reference voltage circuit 24 includes resistors R20, R21, R22, R23 and a photocoupler PC1. The reference voltage circuit 24 is connected to the output terminal of the output voltage switching signal Vsel from the CPU 21 and is supplied with a constant voltage Vcc from a power source (not shown). An error amplification circuit 26 is connected to the output side of the reference voltage circuit 24.

  The output terminal of the output voltage switching signal Vsel from the CPU 21 is connected to the ground GND2 via the resistor R20 and the light emitting element of the photocoupler PC1 connected in series. A resistor R23 is connected in parallel to the light receiving element of the photocoupler PC1 and connected to the ground GND, and is pulled up to a constant voltage Vcc by resistors R21 and R22 connected in series. The reference voltage Vref is output from between the resistors R21 and R22 and is input to the error amplifying circuit 26.

(Operation of Example 1)
A data flow between the monitoring unit 30 and the power supply unit 20 will be described with reference to FIG.

  The power supply unit control unit 32 operates each power supply unit 20 via the bus 31 so as to operate the number of power supply units 20 (= 20-1, 20-2,... 20-n) according to the output current Iout. The output voltage switching command Bsel is transmitted to each. The transmitted output voltage switching command Bsel is received by the CPU 21 in the power supply unit 20. The CPU 21 outputs an output voltage switching signal Vsel corresponding to the output voltage switching command Bsel to the constant voltage control circuit 23.

  Each power supply unit 20 includes an alarm circuit 22. When the alarm circuit 22 detects a failure of its own power supply unit 20, it outputs a failure detection signal Verr to the CPU 21. The CPU 21 transmits failure detection information Berr corresponding to the failure detection signal Verr to the monitoring unit 30. When receiving the failure detection information Berr, the power supply unit failure detection unit 33 of the monitoring unit 30 performs processing when a failure occurs in the power supply unit 20. The processing when the failure of the power supply unit 20 is, for example, notifying the host device of the failure and displaying the fact that the power device 10 is faulty on the display device. An operation instruction or standby instruction may be given to another power supply unit 20 other than the power supply unit 20 in which the failure has occurred, and the operation of the power supply apparatus 10 may be continued.

The operation of the power supply unit 20 will be described with reference to FIG.
A DC voltage is applied to the power supply unit 20 between the input terminals Vin1p and Vin1m. When the switching element SW1 is turned on, a direct current flows to the primary winding of the transformer T1 via an element group (not shown), is discharged to the rectification output circuit via the secondary winding of the transformer T1, and further supplies power to the load 100. Is done.

  In the power supply unit 20, a diode D3 is connected to the output terminal Vout1p in order to prevent backflow from the output terminal Vout1p to the inside. The voltage detection circuit 25 detects a detection voltage Vdet corresponding to the single output voltage Vout1 from the anode voltage Va of the diode D3 and the cathode voltage Vc of the diode D3. The error amplifying circuit 26 amplifies the difference between the detection voltage Vdet and the reference voltage Vref and outputs it as an error voltage Vdif. The drive signal forming circuit 27 outputs the drive signal Vdrv so that the error voltage Vdif is constant, and performs feedback control so that the single output voltage Vout1 is constant. Further, by switching the output voltage switching signal Vsel, the reference voltage Vref applied to the error amplifying circuit 26 is switched, and either the rated voltage Vo or the standby voltage Vs is switched to the single output voltage Vout1. The rated voltage Vo is a voltage that drives the load 100. The standby voltage Vs is a voltage that is lower than the rated voltage Vo and higher than the lower limit voltage VL that can drive the load 100.

  The voltage detection circuit 25 illustrated in FIG. 3 is a circuit that detects a detection voltage Vdet indicating the single output voltage Vout1 of the power supply unit 20.

  In the power supply unit 20 of the first embodiment, a diode D3 that is a rectifier is connected to the output terminal Vout1p in order to prevent backflow from the output terminal Vout1p to the inside. The cathode terminal of the diode D3 is a node ND-D3C. The anode terminal of the diode D3 is a node ND-D3A.

  The node ND-D3C is connected to the ground GND via resistors R11, R12, R13, and R14. That is, the cathode voltage Vc is divided by the resistors R11, R12, R13, and R14.

Node ND-D3A is connected to the ground GND via the diode D 10 and a resistor R10, R15. A voltage obtained by subtracting a voltage that falls by the diode D3 (= a voltage that falls by the diode D10) from the anode voltage Va is divided by resistors R10 and R15. Furthermore, a diode D11 is connected in the forward direction between the resistors R11 and R12 and between the resistors R10 and R15.

When the cathode voltage Vc is lower than or equal to the voltage obtained by subtracting the decrease due to the diode D3 from the anode voltage Va, the voltage obtained by dividing the cathode voltage Vc by the resistors R11, R12, R13, and R14 is the detection voltage Vdet. Is output. When the cathode voltage Vc is higher than the voltage obtained by subtracting the decrease due to the diode D3 from the anode voltage Va, the voltage obtained by increasing the increase of the diode D11 to the voltage obtained by subtracting the decrease due to the diode D10 and the resistor R10 from the anode voltage Va. Is divided by the resistors R12, R13, and R14 , and is output as the detection voltage Vdet.

  When this power supply unit 20 is instructed for operation together with other power supply units 20, the rated voltage Vo is output to the output terminal Vout1p. The single output voltage Vout1 of the power supply unit 20 is the rated voltage Vo. The voltage detection circuit 25 resistance-divides the rated voltage Vo at the node ND-D3C and outputs it as a detection voltage Vdet.

When another power supply unit 20 is instructed to operate and this power supply unit 20 is instructed to stand by, the rated voltage Vo is output to the output terminal Vout1p. However, the single output voltage Vout1 of the power supply unit 20 is the standby voltage Vs, and this voltage Vs is also the voltage of the node ND-D3A . The voltage detection circuit 25 divides the voltage obtained by increasing the rising amount of the diode D11 from the anode voltage Va of the node ND-D3A to the falling amount of the diode D10 and the resistor R10 by the resistors R12, R13, and R14. and outputs as a detection voltage Vdet.

  The reference voltage circuit 24 shown in FIG. 4 is a circuit that outputs different reference voltages Vref in accordance with the output voltage switching signal Vsel.

When the output voltage switching signal Vsel is at a low level (hereinafter referred to as “L level”), the light emitting element of the photocoupler PC1 does not emit light, and the light receiving element of the photocoupler PC1 is off. Therefore, the reference voltage Vref is a value obtained by dividing the constant voltage Vcc by the resistors R21 to R23.
Vref = (Vcc × (R22 + R23) / (R21 + R22 + R23))

When the output voltage switching signal Vsel is at a high level (hereinafter referred to as “H level”), the light emitting element of the photocoupler PC1 emits light, and the light receiving element of the photocoupler PC1 is turned on and becomes conductive. When the impedance of the light receiving element of the photocoupler PC1 is a value close to 0, the reference voltage Vref is a value obtained by dividing the constant voltage Vcc by the resistors R21 and R22.
Vref = (Vcc × (R22) / (R21 + R22))

In the first embodiment, an analog circuit and a photocoupler are used. However, a CPU having a digital / analog converter (hereinafter referred to as a “D / A converter”) is provided in each power supply unit, and this CPU outputs an output voltage switching signal. A reference voltage Vref corresponding to Vsel may be output.

  FIG. 5 is a timing chart showing the operation of the power supply unit of FIG. 2, and the horizontal axis indicates time.

  FIG. 5 shows temporal changes in the single output voltage Vout1 and the single output current Iout1 when different output voltage switching signals Vsel are applied to the power supply units 20-1 and 20-2, respectively. When the output voltage switching signal Vsel of the power supply unit 20-1 remains in the operation instruction, and the output voltage switching signal Vsel of the power supply unit 20-2 is switched from the operation instruction to the standby instruction at time t1, and further to the operation instruction at time t2. It is shown.

  The single output voltage Vout1 of the power supply unit 20-1 remains unchanged at the rated voltage Vo. The single output current Iout1 has a heavy load between times t1 and t2. This is because the power supply unit 20-2 is in a standby state and the load is concentrated on the power supply unit 20-1.

  The single output voltage Vout1 of the power supply unit 20-2 is initially the rated voltage Vo, but changes to the standby voltage Vs only between times t1 and t2, and returns to the rated voltage Vo again at time t2. The single output current Iout1 is unloaded between times t1 and t2.

FIG. 6 is a flowchart showing the operation of the power supply device according to the first embodiment of the present invention.
When the process is started, the power supply apparatus 10 starts all the n power supply units 20 (= 20-1, 20-2,..., 20-n) in step S1, and causes the current measuring unit 40 to start in step S2. To measure the current.

  The power supply apparatus 10 performs the process of step S5 if it is determined in step S3 that the current can be measured normally, but if it cannot measure the current normally, the power supply apparatus 10 waits for n power supply units 20 in step S4. Command. With this command, all the power supply units 20 supply the standby voltage Vs to the load 100. If the process of step S4 is complete | finished, it will return to the process of step S2.

  In step S5, the power supply device 10 compares the output current Iout with a value obtained by multiplying the rated Io by the coefficient α. Hereinafter, this value is referred to as “a rating for one power supply unit 20”. If the output current Iout is less than the rating of one power supply unit 20, one power supply unit 20 (for example, 20-1) is commanded to operate in step S6. The single output voltage Vout of the single power supply unit 20 becomes the rated voltage Vo, and the single power supply unit 20 supplies current to the load 100. In step S7, all the power supply units 20 (for example, 20-2, 20-3,..., 20-n) other than the one in operation are instructed to stand by. The single output voltage Vout of all the power supply units 20 other than the one unit in operation becomes the standby voltage Vs, and these power supply units 20 do not supply current to the load 100. When the process of step S7 ends, the process of step S16 is performed.

  In step S8, if the output current Iout is the rated current for one to two power supply units 20 in step S8, the power supply apparatus 10 in step S9 has two power supply units 20 (for example, 20-1, 20). -2) command to drive. In step S10, all the power supply units 20 (for example, 20-3, 20-4,..., 20-n) other than the two units in operation are instructed to stand by, and the process of step S16 is performed. Do.

  If the output current Iout is the rated current for two to three power supply units 20 in step S11, the power supply device 10 has three power supply units 20 (for example, 20-1, 20) in step S12. Command -2, 20-3) to drive. In step S13, all the power supply units 20 (for example, 20-4, 20-5,..., 20-n) other than the three units in operation are instructed to stand by, and the process of step S16 is performed.

  Hereinafter, in the same manner, whether or not the output current Iout is the rated current for 3 to 4 units, and then whether or not it is the rated current for (n-2) units to (n-1) units. Determine and repeat the same process.

  If the output current Iout is greater than or equal to the (n-1) rated currents of the power supply unit 20 in step S14, the power supply device 10 determines that all n power supply units 20 (= 20-1, 20-2,..., 20-n) are instructed to operate, and the process of step S16 is performed.

  In step S16, the power supply apparatus 10 determines whether or not the failure detection information Berr is received from any of the power supply units 20 (= 20-1, 20-2,..., 20-n). If the failure detection information Berr is received from any one of the power supply units 20, processing at the time of occurrence of the failure of the power supply unit 20 is performed in step S17. The processing when the failure of the power supply unit 20 is, for example, notifying the host device of the failure and displaying the fact that the power device 10 is faulty on the display device. Furthermore, an operation instruction or standby instruction may be given to another power supply unit 20 other than the power supply unit 20 in which the failure has occurred, and the operation of the power supply apparatus 10 may be continued. If no failure detection information Berr has been received from any power supply unit 20, the process returns to step S2.

  FIG. 7 is a diagram illustrating the constant voltage accuracy of the power supply device according to the first embodiment of the present invention. The vertical axis represents the output voltage Vout, and the horizontal axis represents the output current Iout.

  The standby voltage Vs is lower than the rated voltage Vo. The lower limit voltage VL that can drive the load 100 is lower than the standby voltage Vs. As the output current Iout increases, the output voltage Vout gradually decreases, but the output voltage Vout is always higher than the standby voltage Vs.

  FIG. 8 is a diagram illustrating the efficiency characteristics of the power supply device according to the first embodiment of the present invention and the conventional example, where the horizontal axis indicates the output capacity ratio [%] and the vertical axis indicates the efficiency [%]. .

  The efficiency of a power supply device that does not perform conventional stop control is indicated by a one-dot chain line. It can be seen that the efficiency of a conventional power supply device that does not perform stop control is reduced particularly in the case of a so-called light load with a low output capacity ratio. The efficiency of the power supply device 10 according to the first embodiment is indicated by a solid line. It can be seen that the efficiency of the power supply device 10 of the first embodiment is improved in the case of a so-called light load as compared with the conventional power supply device that does not perform stop control.

  FIG. 9 is a diagram showing the capacity ratio and the number of units operated for one unit of the power supply device in Embodiment 1 of the present invention, where the horizontal axis shows the output capacity ratio [%], and the vertical axis shows the one unit capacity. The ratio and the number of units in operation are shown. FIG. 9 shows an example of switching at 100% of the 1 unit capacity rating.

  The unit operation number refers to the operation number of the power supply units 20, and is indicated by a broken line in FIG. When the output capacity ratio decreases to 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, or 87.5% or less, the number of units operating is one unit each. The number of standby units increases by one each. Conversely, when the output capacity ratio increases and exceeds 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, and 87.5%, respectively, the unit operation number is 1 each. As the number of units increases, the number of standby units decreases by one.

  That is, when the output current Iout decreases, the monitoring unit 30 issues a standby instruction to a larger number of power supply units 20 and issues an operation instruction to a smaller number of power supply units 20. When the output current Iout increases, the monitoring unit 30 gives an operation instruction to a larger number of power supply units 20 and issues a standby instruction to a smaller number of power supply units 20.

  The ratio with respect to 1 unit capacity means the ratio of the load with respect to the capacity | capacitance of the power supply unit 20 in operation. As the output capacity ratio approaches from 0% to 12.5%, the ratio to 1 unit capacity increases from 0.0 to 1.0, and decreases to 0.5 immediately after exceeding 12.5%. As the output capacity ratio approaches 12.5% to 25%, the ratio to 1 unit capacity increases toward 1.0, and decreases to 0.666... Immediately after exceeding 25%. Similarly, when the number of operating units is n, as the output capacity ratio approaches (n × 12.5)% from ((n−1) × 12.5)%, the ratio to 1 unit capacity is 1 respectively. To 0. When the output capacity ratio exceeds (n × 12.5)%, the number of operating units is (n + 1) units, and the ratio to one unit capacity is reduced to (1.0−1.0 ÷ (n + 1)).

  FIG. 10 is a diagram showing the operation number control and the measurement result of the current measuring unit in the first embodiment of the present invention, showing an example in which one unit capacity rating is set to 100A and one unit capacity rating is switched at 100%. Yes.

  In Example 1 of the present invention, the rating for one power supply unit 20 is 100 [A]. FIG. 10 shows the relationship between the measurement result of the output current Iout by the current measuring unit 40 and the number of operating power supply units 20 based on this rating.

  When the measurement result of the current measuring unit 40 is 0 [A] to 100 [A], the number of operating power supply units 20 is one. When the measurement result of the current measuring unit 40 is 100 [A] to 200 [A], the number of operating power supply units 20 is two. Similarly, when the measurement result of the current measuring unit 40 is ((n−1) × 100) [A] to (n × 100) [A], the number of operating power supply units 20 is n.

  FIG. 11 is a diagram illustrating a failure event of the power supply device according to the first embodiment of the present invention and the conventional example. The vertical axis represents the output voltage Vout, and the horizontal axis represents the output current Iout.

  It is assumed that the power supply device 10 according to the first embodiment of the present invention instructs the seven power supply units 20 to operate and instructs the two power supply units 20 to wait at timing T20. At this time, compared with the case where the conventional power supply apparatus of the stop method instructs the seven power supply units to operate at the timing T20A and stops at the two power supply units, the reliability at the time of occurrence of an abnormality in the monitoring unit is higher. Different.

  Consider a case where the power supply apparatus 10 according to the first embodiment instructs the standby of eight power supply units 20 and instructs the operation of only one power supply unit 20 due to an abnormality of the monitoring unit 30 at timing T21. At this time, since only 100 [A] can be supplied by only one power supply unit 20 instructed to operate, the output voltage Vout drops. However, when the output voltage Vout drops to the standby voltage Vs, current is supplied from each of the other eight power supply units 20. One power supply unit 20 instructed for operation and eight power supply units 20 instructed for standby can supply up to 900 [A] in total. The output voltage Vout does not drop below the standby voltage Vs, and therefore the system does not stop.

  Consider a case where a conventional power supply apparatus of a stop method instructs stop of eight power supply units and instructs operation of only one power supply unit due to abnormality of the monitoring unit at timing T21A. At this time, only 100 [A] of one power supply unit instructed to operate is supplied, and the output voltage Vout becomes lower than the lower limit voltage VL that can drive the load. Therefore, the load cannot be driven and the system is stopped.

(Effect of Example 1)
The power supply device 10 according to the first embodiment has the following effects (A) and (B).

  (A) By operating the number of power supply units 20 corresponding to the output current Iout, the output capacity ratio of the power supply unit 20 in the operating state is improved, and the efficiency of the power supply device 10 is improved. At the same time, the power supply unit 20 in the standby state continues to operate at the standby voltage Vs, and the alarm circuit 22 operates, so that a failure can be detected.

  (B) Even when the monitoring unit 30 of the power supply device 10 breaks down and erroneously instructs the power supply unit 20 to enter the standby state, the standby voltage Vs can be supplied and the system is stopped. Absent. Therefore, the highly reliable power supply device 10 can be provided.

(Configuration of Example 2)
FIG. 12 is a schematic configuration diagram illustrating a power supply unit according to the second embodiment of the present invention. Elements common to those in FIG. 2 illustrating the first embodiment are denoted by common reference numerals.

  The power supply unit 20A of the second embodiment is the same as the power supply unit 20 of the first embodiment except that the power supply unit 20A of the second embodiment has a constant voltage control circuit 23A different from the power supply unit 20 of the first embodiment.

  The constant voltage control circuit 23A according to the second embodiment amplifies an error between the voltage detection switching circuit 25A that detects the detection voltage Vdet2 corresponding to the single output voltage Vout1 and the detection voltage Vdet2 and the reference voltage Vref, thereby generating the error voltage Vdif. An error amplifier circuit 26A for outputting and a drive signal forming circuit 27 for outputting a drive signal Vdrv to the switching element SW1 based on the error voltage Vdif are provided.

  Similarly to the constant voltage control circuit 23 of the first embodiment, the constant voltage control circuit 23A of the second embodiment has an output terminal for the output voltage switching signal Vsel of the CPU 21 and an anode terminal (= node ND-D3A) of the diode D3. The cathode terminal (= node ND-D3C) and the output terminal Vout1m of the power supply unit 20 are connected. The switching element SW1 is connected to the output side of the constant voltage control circuit 23A of the second embodiment.

  The output terminal of the output voltage switching signal Vsel of the CPU 21, the node ND-D3A, and the node ND-D3C are connected to the voltage detection switching circuit 25A. An error amplifier circuit 26A is connected to the output side of the voltage detection switching circuit 25A.

  The error amplification circuit 26A is connected to the output terminal of the detection voltage Vdet2 of the voltage detection switching circuit 25A, and to the constant voltage source 28 that is a reference voltage output unit that outputs the reference voltage Vref. A drive signal forming circuit 27 is connected to the output side of the error amplifier circuit 26A. A switching element SW 1 is connected to the output side of the drive signal forming circuit 27.

  FIG. 13 is a circuit diagram illustrating the voltage detection switching circuit of FIG. 12, and elements common to those in FIG. 3 illustrating the first embodiment are denoted by common reference numerals.

  The voltage detection switching circuit 25A according to the second embodiment is different from the voltage detection circuit 25 according to the first embodiment except that it includes a photocoupler PC2 and a resistor R16 in addition to the configuration of the voltage detection circuit 25 according to the first embodiment. It is the same.

  The output terminal of the output voltage switching signal Vsel from the CPU 21 is connected to the ground GND2 via the resistor R16 and the light emitting element of the photocoupler PC2. The light receiving element of the photocoupler PC2 is connected in parallel with the resistor R13.

(Operation of Example 2)
Based on FIG. 12, the operation of the power supply unit 20A will be described.

  A DC voltage is applied to the power supply unit 20A between the input terminals Vin1p and Vin1m as in the first embodiment. When the switching element SW1 is turned on, a direct current flows to the primary winding of the transformer T1 via an element group (not shown), is discharged to the rectification output circuit via the secondary winding of the transformer T1, and further supplies power to the load 100. Is done.

  In the power supply unit 20, a diode D3 is connected to the output terminal Vout1p in order to prevent backflow from the output terminal Vout1p to the inside. The voltage detection switching circuit 25A includes a single output voltage Vout1 and an output voltage switching signal Vsel from the voltage Va of the anode terminal (= node ND-D3A) of the diode D3 and the voltage Vc of the cathode terminal (node ND-D3C) of the diode D3. The error detection circuit 26A and the drive signal forming circuit 27 perform feedback control so that the detection voltage Vdet2 corresponding to the output voltage Vdet2 is detected and the single output voltage Vout1 becomes a constant voltage corresponding to the output voltage switching signal Vsel. According to the output voltage switching signal Vsel, the single output voltage Vout1 is switched to either the rated voltage Vo or the standby voltage Vs.

  A voltage detection switching circuit 25A shown in FIG. 13 is a detection circuit that detects a detection voltage Vdet2 indicating the single output voltage Vout1 of the power supply unit 20A, and a voltage between the single output voltage Vout1 and the detection voltage Vdet2 by the output voltage switching signal Vsel. It has a function to switch the ratio.

  Similarly to the power supply unit 20 of the first embodiment, the power supply unit 20A of the second embodiment has a diode D3 that is a rectifier connected to the output terminal Vout1p in order to prevent backflow from the output terminal Vout1p to the inside. The cathode terminal of the diode D3 is a node ND-D3C. The anode terminal of the diode D3 is a node ND-D3A.

  If the output voltage switching signal Vsel is H level, the light emitting element of the photocoupler PC2 emits light, and thus the light receiving element of the photocoupler PC2 is turned on and becomes conductive. If the output voltage switching signal Vsel is L level, the light emitting element of the photocoupler PC2 does not emit light, and thus the light receiving element of the photocoupler PC2 is turned off.

  The node ND-D3C is connected to the ground GND through resistors R11 and R12, a resistor R13 connected in parallel, a light receiving element of the photocoupler PC2, and a resistor R14. The cathode voltage Vc is divided by resistors R11, R12, R14 or divided by resistors R11, R12, R13, R14 according to the output voltage switching signal Vsel.

Node ND-D3A is connected to the ground GND via the diode D 10 and a resistor R10, R15. A voltage obtained by subtracting a voltage that falls by the diode D3 (= a voltage that falls by the diode D10) from the anode voltage Va is divided by resistors R10 and R15. Furthermore, a diode D11 is connected in the forward direction between the resistors R11 and R12 and between the resistors R10 and R15.

When the output voltage switching signal Vsel is at the L level and the cathode voltage Vc is lower than or equal to the voltage obtained by subtracting the decrease by the diode D3 from the anode voltage Va, the cathode voltage Vc is set to the resistors R11, R12, R13, R14. The voltage divided by is output as the detection voltage Vdet2. When the cathode voltage Vc is higher than the voltage obtained by subtracting the decrease due to the diode D3 from the anode voltage Va, the voltage obtained by increasing the increase of the diode D11 to the voltage obtained by subtracting the decrease due to the diode D10 and the resistor R10 from the anode voltage Va. a divided voltage by the resistors R12, R13, R14 is output as a detection voltage Vdet2.

When the output voltage switching signal Vsel is at the H level and the cathode voltage Vc is lower than or equal to the voltage obtained by subtracting the decrease by the diode D3 from the anode voltage Va, the cathode voltage Vc is divided by the resistors R11, R12, and R14. The pressed voltage is output as the detection voltage Vdet2. When the cathode voltage Vc is higher than the voltage obtained by subtracting the decrease due to the diode D3 from the anode voltage Va, the voltage obtained by increasing the increase of the diode D11 to the voltage obtained by subtracting the decrease due to the diode D10 and the resistor R10 from the anode voltage Va. a divided voltage by the resistors R12, R14 is output as a detection voltage Vdet2.

  When this power supply unit 20 is instructed for operation together with other power supply units 20, the rated voltage Vo is output to the output terminal Vout1p. The single output voltage Vout1 of the power supply unit 20 is the rated voltage Vo. The voltage detection switching circuit 25A divides the rated voltage Vo at the node ND-D3C by the resistors R11, R12, R13, and R14, and outputs it as the detection voltage Vdet2.

When another power supply unit 20 is instructed to operate and this power supply unit 20 is instructed to stand by, the rated voltage Vo is output to the output terminal Vout1p. However, the single output voltage Vout1 of the power supply unit 20 is the standby voltage Vs, and this voltage Vs is also the voltage of the node ND-D3A . The voltage detection switching circuit 25A divides the voltage obtained by increasing the rise of the diode D11 from the anode voltage Va of the node ND-D3A to the voltage of the fall by the diode D10 and the resistor R10, using the resistors R12 and R14. It outputs as detection voltage Vdet2.

(Effect of Example 2)
According to the power supply device 10 of the second embodiment, in addition to the effects of the first embodiment, there are the following effects (C).

  (C) Since the reference voltage circuit 24 is not required, the configuration of the power supply unit 20A can be simplified and the cost can be reduced.

(Configuration of Example 3)
FIG. 14 is a schematic configuration diagram illustrating a power supply device according to the third embodiment of the present invention. Elements common to those in FIG. 1A illustrating the first embodiment are denoted by common reference numerals.

  The power supply device 10B of the third embodiment includes a Batt terminal in addition to the power supply device 10 of the first embodiment, and is connected to the output terminal of the current measuring unit 40 of the power supply device 10B. The configuration is the same as that of the device 10.

(Operation of Example 3)
The operation of the power supply apparatus 10B will be described based on FIG.

  The power supply device 10B drives the load 100 by supplying the output voltage Vout to the load 100 through the output terminal, and charges the storage battery 50 by supplying the output voltage Vout to the storage battery 50 through the Batt terminal. When the power supply device 10B is not operating, the load 100 is driven by the output voltage supplied by the storage battery 50.

(Effect of Example 3)
According to the power supply device 10B of the third embodiment, in addition to the effects of the first and second embodiments, the following effect (D) is obtained.

  (D) Since the Batt terminal is provided, the storage battery 50 can be easily connected to the load 100 in parallel.

(Configuration of Example 4)
FIG. 15 is a schematic configuration diagram showing a power supply device according to a fourth embodiment of the present invention, which is the same configuration as the power supply device 10 shown in FIG.

  In the power supply device 10 of the fourth embodiment, the load 100 and the storage battery 50 are connected in parallel to the output terminal.

(Operation of Example 4)
The operation of the power supply device 10 will be described based on FIG.

  The power supply device 10 drives the load 100 and charges the storage battery 50 by supplying the output voltage Vout to the load 100 and the storage battery 50 via the output terminal. When the power supply device 10 is not operating, the load 100 is driven by the output voltage supplied from the storage battery 50.

(Effect of Example 4)
The effect of the power supply device 10 of the fourth embodiment is the same as that of the third embodiment.

(Modification)
The present invention is not limited to the above-described embodiments, and various usage forms and modifications are possible. For example, the following forms (a) to (d) are used as the usage form and the modified examples.

  (A) Although the monitoring unit 30 is provided in the power supply devices 10, 10A, and 10B in the first to fourth embodiments, a plurality of power supply units 20 (= 20-1, 20-2,..., 20-n) The CPU 21 and the current measuring unit 40 are connected to each other, and the plurality of CPUs 21 are connected to each other by a bus. The plurality of CPUs 21 measure the output current Iout and determine whether to operate the power supply unit 20 or wait. You may judge. Thereby, there exists an effect that the monitoring part 30 becomes unnecessary.

  (B) In the first to fourth embodiments, the current measuring unit 40 is provided immediately before the output terminals of the power supply apparatuses 10, 10A, and 10B. However, the power supply unit 20 (= 20-1, 20-2,..., 20-n) is provided with a single current measuring unit that measures the current of each power supply unit 20 and communicates with the monitoring unit 30. May be used to measure the total current of each power supply unit 20. Thereby, there exists an effect that the electric current measurement part 40 becomes unnecessary.

  (C) In the first to fourth embodiments, the current measurement unit 40 is provided immediately before the output terminals of the power supply apparatuses 10, 10 </ b> A, and 10 </ b> B, and the monitoring unit 30 that measures the output current Iout by the current measurement unit 40 is provided. However, a single current measuring unit for measuring the current of each power supply unit 20 is provided, the output current Iout is measured by the CPU 21 provided in each power supply unit 20, and the CPU 21 of the other power supply unit 20 and the bus are connected to each other. The sum of currents of all the power supply units 20 may be obtained by communication, and the output current Iout may be measured. In this case, each CPU 21 determines whether to operate or wait for each power supply unit 20 according to the output current Iout. Thereby, there exists an effect that the monitoring part 30 and the electric current measurement part 40 become unnecessary.

  (D) In Example 1, when the monitoring unit 30 commands the operation to the x power supply units 20, the monitoring unit 30 commands the operation in the order of the numbers of the power supply units 20 (= 20-1 to 20-x), When instructing the power supply unit 20 to wait, the standby is instructed in descending order of the power supply unit 20 numbers. However, the operation command and the standby command for the power supply unit 20 (= 20-1 to 20-n) may be randomly issued regardless of the number of the power supply unit 20. In order to randomly issue an operation command and a standby command regardless of the number of the power supply unit 20, for example, a random number is generated every time the operation is commanded to the power supply unit 20, and any of the standby power supply units 20 is determined by this random number. Decide and order. Specifically, when 7 power supply units 20 are in a standby state, when a new operation is instructed to one power supply unit 20, a random number is generated and a remainder of 7 corresponding to the number of standby units is obtained. Calculate, and determine one of the seven power supply units 20 according to any of the remainders 0 to 6, and command the operation. The same applies to the standby command. Thereby, the usage rate of each power supply unit 20 can be leveled, and thus the failure rate of the power supply device 10 can be reduced.

10, 10A, 10B Power supply 20, 20A Power supply unit 21 CPU
22 Alarm circuit 23, 23A Constant voltage control circuit 24 Reference voltage circuit 25 Voltage detection circuit 25A Voltage detection switching circuit 26, 26A Error amplification circuit 27 Drive signal formation circuit 28 Constant voltage source 30 Monitoring unit 31 Bus 32 Power supply unit control unit 33 Power supply Unit failure detection unit 40 Current measurement unit 50 Storage battery 100 Load

Claims (7)

A plurality of power supply units connected in parallel to supply output voltage and output current to an external load;
A current measurement unit that measures the output current flowing from the plurality of power supply units connected in parallel to the external load; and
A monitoring unit that gives an operation instruction or a standby instruction to each of the plurality of power supply units according to the measurement result of the output current, and
When the output current decreases, the monitoring unit issues the standby instruction to a larger number of the power supply units and performs the operation instruction to a smaller number of the power supply units, and the output current increases as the output current increases. The operation instruction is given to the power supply units of the number of units and the standby instruction is issued to a smaller number of the power supply units,
The power supply unit outputs a first output voltage for driving the external load according to the operation instruction from the monitoring unit, and is lower than the first output voltage according to the standby instruction from the monitoring unit, And a power supply apparatus that outputs a second output voltage higher than a lower limit voltage capable of driving the external load,
The power supply unit is
An output voltage detection unit for detecting a single output voltage which is a voltage output by the power supply unit alone;
A voltage switching unit that switches a reference voltage in accordance with an output voltage switching signal generated based on the operation instruction and the standby instruction from the monitoring unit;
A constant voltage control unit that feeds back a difference between the single output voltage and the reference voltage and controls the single output voltage to be constant;
An output terminal for outputting the output voltage and the output current;
A rectifier connected to the output terminal to prevent backflow from the output terminal into the power supply unit, and
The output voltage detector is
If the first terminal voltage of the output terminal is lower than or equal to the second terminal voltage obtained by subtracting the voltage corresponding to the decrease by the rectifier from the voltage of the terminal opposite to the output terminal of the rectifier, A first terminal voltage is detected as the single output voltage, and if the first terminal voltage is higher than the second terminal voltage, the second terminal voltage is detected as the single output voltage. Power supply. A plurality of power supply units connected in parallel to supply output voltage and output current to an external load;
A current measurement unit that measures the output current flowing from the plurality of power supply units connected in parallel to the external load; and
A monitoring unit that gives an operation instruction or a standby instruction to each of the plurality of power supply units according to the measurement result of the output current, and
When the output current decreases, the monitoring unit issues the standby instruction to a larger number of the power supply units and performs the operation instruction to a smaller number of the power supply units, and the output current increases as the output current increases. The operation instruction is given to the power supply units of the number of units and the standby instruction is issued to a smaller number of the power supply units,
The power supply unit outputs a first output voltage for driving the external load according to the operation instruction from the monitoring unit, and is lower than the first output voltage according to the standby instruction from the monitoring unit, And a power supply apparatus that outputs a second output voltage higher than a lower limit voltage capable of driving the external load,
The power supply unit is
An output voltage detection unit that detects a single output voltage that is a voltage that the power supply unit outputs alone, and that switches an amplification factor of the single output voltage according to the operation instruction and the standby instruction from the monitoring unit;
A reference voltage output unit for outputting a reference voltage;
A constant voltage control unit that feeds back a difference between the single output voltage amplified by the output voltage detection unit and the reference voltage, and controls the single output voltage constant;
An output terminal for outputting the output voltage and the output current;
A rectifier connected to the output terminal to prevent backflow from the output terminal into the power supply unit, and
The output voltage detector is
If the first terminal voltage of the output terminal is lower than or equal to the second terminal voltage obtained by subtracting the voltage corresponding to the decrease by the rectifier from the voltage of the terminal opposite to the output terminal of the rectifier, A first terminal voltage is detected as the single output voltage, and if the first terminal voltage is higher than the second terminal voltage, the second terminal voltage is detected as the single output voltage. Power supply. The power supply unit is
When a failure of the power supply unit itself is detected during operation and standby, a failure detection unit that transmits failure detection information is provided,
The monitoring unit
3. The power supply device according to claim 1, wherein when the failure detection information is received, an abnormality is notified to a host device. The power supply unit is
When a failure of the power supply unit itself is detected during operation and standby, a failure detection unit that transmits failure detection information is provided,
The monitoring unit
3. The power supply according to claim 1, wherein if the failure detection information is received from a first power supply unit, the standby instruction and the operation instruction are given to the power supply units other than the first power supply unit. apparatus. The plurality of power supply units connected in parallel are:
5. The power supply device according to claim 1, wherein the output voltage and the output current are supplied to the external load and the secondary battery that are connected in parallel. The monitoring unit
The power supply apparatus according to any one of claims 1 to 5, wherein the CPUs of the plurality of power supply units are connected to each other by a bus. The current measuring unit is
It is composed of a plurality of single current measuring units that measure the output current flowing through the external load that each of the plurality of power supply units connected in parallel has,
The monitoring unit
The operation instruction or the standby instruction is given to each of the plurality of power supply units according to the total of the measurement results of the output current, and when the total of the output currents is reduced, the standby unit is supplied to a larger number of the power supply units. The operation instruction is given to a smaller number of the power supply units, and when the sum of the output currents is increased, the operation instruction is given to a larger number of the power supply units and a smaller number of the power supply units are provided. The power supply apparatus according to claim 1, wherein the standby instruction is performed.

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