Power supply device, power supply device control method and power supply device control program

Abstract

To safely and quickly start up a post-stage circuit that operates upon receiving output voltage generated by a voltage generation unit based on the fact that the output voltage is stabilized.SOLUTION: A power supply device has: a voltage generating unit that starts generation of output voltage based on a start-up instruction and raises the output voltage to a set voltage; and a control unit that determines whether the amount of change per predetermined time of the output voltage is smaller than a threshold set in advance, and when the amount of change is smaller than the threshold, outputs a control signal for starting up a post-stage circuit that operates upon receiving the output voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply device, a control method for a power supply device, and a control program for a power supply device. [Background technology]

[0002] There is known a power supply circuit including a first DC (Direct Current) / DC converter that generates a first output voltage, and a second DC / DC converter that generates a second output voltage using the first output voltage. In order to stabilize the operation at startup, this type of power supply circuit starts the second DC / DC converter after a predetermined delay time has elapsed after the first output voltage becomes equal to or higher than a threshold voltage after the first DC / DC converter is started (for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0003] However, when starting up the power supply circuit, starting the second DC / DC converter after waiting for a predetermined delay time takes time for the second output voltage to reach a predetermined voltage, which causes a problem of slowing down the startup time of the system in which the power supply circuit is installed.

[0004] The disclosed technology has been developed in consideration of the above-mentioned problems, and aims to safely and quickly start up a downstream circuit that operates in response to the output voltage based on the stabilization of the output voltage generated by the voltage generation unit. [Means for solving the problem]

[0005] In order to solve the above technical problem, a power supply device according to one aspect of the present invention includes a voltage generating unit that starts generating an output voltage based on a startup instruction and increases the output voltage to a set voltage, and a control unit that determines whether a change in the output voltage per predetermined time is smaller than a preset threshold value and, if the change is smaller than the threshold value, outputs a control signal to start a subsequent circuit that operates in response to the output voltage. and the control unit outputs the control signal when the output voltage is higher than an input rated voltage of the subsequent circuit or when the output voltage is lower than or equal to the input rated voltage after determining that the amount of change in the output voltage is smaller than the threshold value. It is characterized by: Effect of the Invention

[0006] Based on the fact that the output voltage generated by the voltage generating section has become stable, the subsequent circuit that operates by receiving the output voltage can be started up safely and quickly. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an example of a power supply device according to a first embodiment. [Diagram 2] 2 is an explanatory diagram showing an example of the operation of the power supply device of FIG. [Diagram 3] 2 is a flow chart showing an example of control of the power supply device by the control unit of FIG. 1. [Figure 4] 1. FIG. 4 is a flow chart showing another example of control of the power supply device by the control unit of FIG. [Diagram 5] 2 is an overall configuration diagram showing an example of an image forming apparatus in which the power supply device of FIG. 1 is installed. [Figure 6] 2 is a block diagram showing an example of a hardware configuration of a control unit in FIG. 1. [Figure 7] 13 is a flow chart showing an example of startup control of the power supply device by a control unit in the power supply device of the second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted. In the following, reference numerals indicating signals are also used as reference numerals indicating signal lines.

[0009] (First embodiment) Fig. 1 is a block diagram showing an example of a power supply device according to a first embodiment. For example, a power supply device 10 shown in Fig. 1 includes an AC (Alternating Current) / DC converter 11, a DC / DC converter 12, a voltage detection unit 13, and a control unit 14. The power supply device 10 generates a direct current voltage DC2 to be supplied to a load 30.

[0010] AC / DC converter 11 is started based on a control signal CNTL1. Once started, AC / DC converter 11 starts generating DC voltage DC1 using AC voltage AC1 supplied from AC power supply 20 such as a commercial power supply, and outputs the generated DC voltage DC1 to DC / DC converter 12. Although not particularly limited, for example, AC / DC converter 11 uses AC voltage AC1 of 100V to increase DC voltage DC1 from 0V to 33V, and then maintains DC voltage DC1 at 33V.

[0011] The DC voltage DC1 is an example of an output voltage, and the DC voltage DC1 of 33V is an example of a set voltage. The AC / DC converter 11 is an example of a voltage generating unit. The control signal CNTL1 is an example of a start-up instruction. The power supply device 10 may have a DC / DC converter instead of the AC / DC converter 11. In this case, the DC / DC converter receives a DC voltage and generates the DC voltage DC1 using the received DC voltage. Hereinafter, the voltage value of the DC voltage DC1 is also referred to as a voltage value DC1.

[0012] DC / DC converter 12 is started based on control signal CNTL2. The started DC / DC converter 12 generates a DC voltage DC2 based on a DC voltage DC1 received from AC / DC converter 11, and outputs the generated DC voltage DC2 to a load 30 connected to power supply device 10. Load 30 operates by receiving DC voltage DC2 as a power supply voltage. Although not particularly limited, for example, DC voltage DC2 output by DC / DC converter 12 is 24V. DC / DC converter 12 is an example of a subsequent circuit that operates by receiving DC voltage DC1.

[0013] The voltage detection unit 13 detects the voltage value DC1 of the direct current voltage DC1 output from the AC / DC converter 11, and outputs voltage information VINF indicating the detected voltage value DC1 to the control unit 14. The control unit 14 outputs a control signal CNTL1 that starts up the AC / DC converter 11 based on a start-up signal ON from a system (not shown) in which the power supply device 10 is mounted.

[0014] Furthermore, control unit 14 determines the start-up timing of DC / DC converter 12 based on voltage information VINF received from voltage detection unit 13. Then, when control unit 14 determines the start-up timing, control unit 14 outputs a control signal CNTL2 for starting DC / DC converter 12 to DC / DC converter 12. An example of the operation for determining the start-up timing is shown in FIG.

[0015] Based on a stop signal OFF from the system, the control unit 14 outputs a control signal CNTL1 for stopping the operation of the AC / DC converter 11 and outputs a control signal CNTL2 for stopping the operation of the DC / DC converter 12. For example, the control unit 14 may be configured by a microcomputer. In this case, at least a part of the functions of the control unit 14 is realized by a central processing unit (CPU) of the microcomputer executing a control program. Furthermore, the control unit 14 may be configured by hardware logic such as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0016] The voltage detection unit 13 may be included in the control unit 14. The power supply device 10 may also have a DC / DC converter (not shown) that generates a DC voltage (5 V) based on the DC voltage DC1 to be supplied to a load that operates on a power supply voltage such as 5 V.

[0017] Fig. 2 is an explanatory diagram showing an example of the operation of the power supply device 10 in Fig. 1. First, the control unit 14 changes the control signal CNTL1 to an active level (e.g., high level) based on a start-up signal ON from the system (Fig. 2(a)). The AC / DC converter 11 is started based on the high-level control signal CNTL1 and starts generating a DC voltage DC1 (Fig. 2(b)).

[0018] The control unit 14 receives voltage information VINF indicating the voltage value DC1 from the voltage detection unit 13. The control unit 14 calculates, for example, the amount of change in the DC voltage DC1 at predetermined time intervals (e.g., 1 ms) based on the voltage information VINF. Here, after being started, the AC / DC converter 11 increases the DC voltage DC1 at a constant rate of increase, and decreases the rate of increase as the DC voltage DC1 approaches a set voltage (e.g., 33 V) (FIG. 2(c)).

[0019] When the calculated change in DC voltage DC1 per predetermined time period becomes equal to or less than a threshold Vth (e.g., 0.5 V), the control unit 14 changes the control signal CNTL2 to an active level (e.g., high level) (FIG. 2(d)). Then, the DC / DC converter 12 is started up based on the high-level control signal CNTL2, and starts generating the DC voltage DC2 (FIG. 2(e)).

[0020] The threshold value Vth is set to a value that is greater than the static voltage accuracy of the DC voltage DC1 increased to the set voltage and smaller than the amount of change (1.0 V) per predetermined time at the increase rate (e.g., 1.0 V / ms) of the DC voltage DC1 during soft start by the AC / DC converter 11. For example, the static voltage accuracy of the DC voltage DC1 is set to 1% (0.33 V) of the set voltage (e.g., 33 V).

[0021] By setting the threshold Vth to a value larger than the static voltage accuracy of the DC voltage DC1, it is possible to prevent the control signal CNTL2 from being erroneously output due to voltage fluctuations within the standard after the DC voltage DC1 reaches the set voltage. Also, by setting the threshold Vth smaller than the amount of change per predetermined time at the rise rate of the DC voltage DC1 during soft start, it is possible to prevent the control signal CNTL2 from being output, for example, immediately after the start of the AC / DC converter 11. That is, the control unit 14 can output the control signal CNTL2 at the timing when the DC voltage DC1 approaches the set voltage and is stably generated, and the amount of change per predetermined time at the rise rate of the DC voltage DC1 begins to decrease.

[0022] The control unit 14 may determine that the DC voltage DC1 is stable when the amount of change in the DC voltage DC1 per predetermined time period becomes equal to or less than the threshold value Vth multiple times in succession, and may output the control signal CNTL2. The control unit 14 may also determine that the DC voltage DC1 is stable when the amount of change in the DC voltage DC1 per predetermined time period gradually decreases multiple times in succession, and may determine the output of CNTL2 and output the control signal CNTL2.

[0023] The operation shown in brackets at the bottom of Fig. 2 shows an example in which DC / DC converter 12 is started after a predetermined delay time has elapsed since DC voltage DC1 has risen to a preset threshold voltage. In this case, the start-up time of DC / DC converter 12 is delayed compared to the case in which DC / DC converter 12 is started based on the change in DC voltage DC1 becoming equal to or less than threshold Vth. In other words, in this embodiment, by starting DC / DC converter 12 when the change in DC voltage DC1 per predetermined time becomes equal to or less than threshold Vth, DC / DC converter 12 can be started safely and quickly using a stable DC voltage DC1.

[0024] Fig. 3 is a flow diagram showing an example of startup control of the power supply device 10 by the control unit 14 of Fig. 1. Fig. 3 shows an example of a method of controlling the power supply device 10 by the control unit 14. For example, Fig. 3 is realized by the control unit 14 executing a control program.

[0025] 3 is started when the control unit 14 sets the control signal CNTL1 to a high level H and starts up the AC / DC converter 11. First, in step S10, the control unit 14 acquires the voltage value DC1 of the DC voltage DC1 based on the voltage information VINF from the voltage detection unit 13.

[0026] Next, in step S12, the control unit 14 waits for a predetermined time (e.g., 1 ms) to elapse, and when the predetermined time has elapsed, executes step S14. In step S14, the control unit 14 acquires the voltage value DC1 again based on the voltage information VINF. Next, in step S16, the control unit 14 calculates the increase (amount of change) in the voltage value DC1 before and after the predetermined time has elapsed, based on the voltage value DC1 acquired in step S14 and the voltage value DC1 acquired the predetermined time (1 ms) earlier.

[0027] Next, in step S18, if the increase amount is equal to or less than a threshold value Vth (e.g., 0.5 V), the control unit 14 executes step S20. If the increase amount is greater than the threshold value Vth, the control unit 14 returns to step S12 and waits for a predetermined time (1 ms) to elapse. In step S20, the control unit 14 sets the control signal CNTL2 to a high level H, starts up the DC / DC converter 12, and ends the start-up control of the power supply device 10 shown in FIG. 3.

[0028] If the control unit 14 determines that the increase amount is equal to or less than the threshold value Vth, for example, before 500 ms has elapsed since the control unit 14 set the control signal CNTL1 to the high level H, the control unit 14 may set the control signal CNTL2 to the high level H. On the other hand, if the control unit 14 determines that the increase amount is equal to or less than the threshold value Vth, for example, after 500 ms has elapsed since the control unit 14 set the control signal CNTL1 to the high level H, the control unit 14 may end the operation of FIG. 3 without setting the control signal CNTL2 to the high level H.

[0029] That is, if 500 ms or more has elapsed before the control signal CNTL2 is set to the high level H and the control unit 14 determines that the AC / DC converter 11 is not operating normally, the control unit 14 does not set the control signal CNTL2 to the high level H. In this case, the control unit 14 may notify a system or the like that manages the power supply device 10 of the abnormality in the power supply device 10.

[0030] Fig. 4 is a flow diagram showing another example of control of the power supply device 10 by the control unit 14 of Fig. 1. Fig. 4 is the same as the operation of Fig. 3, except that when NO is determined in step S18, the process moves to step S14 instead of step S12.

[0031] In step S18, if the increase is greater than the threshold value Vth, step S14 is performed, so that the increase in the DC voltage DC1 during the predetermined time (1 ms) can be calculated continuously, rather than at predetermined time intervals, thereby making it possible to accurately determine whether the increase in the DC voltage DC1 has become equal to or less than the threshold value Vth.

[0032] Fig. 5 is an overall configuration diagram showing an example of an image forming apparatus 1 equipped with the power supply device 10 of Fig. 1. The image forming apparatus 1 shown in Fig. 5 is, for example, a digital multifunction machine such as an MFP (Multi-Function Peripheral) having a copy function, a printer function, a scanner function, a facsimile function, etc. The image forming apparatus 1 can switch between operation modes that respectively realize the copy function, the printer function, the scanner function, and the facsimile function by using an application switching key or the like on an operation unit (not shown).

[0033] The image forming apparatus 1 is in copy mode when the copy function is selected, and in printer mode when the printer function is selected. The image forming apparatus 1 is in scanner mode when the scanner function is selected, and in facsimile mode when the facsimile function is selected. The image forming apparatus 1 may be a copier having only a copy function or a printer having only a printer function.

[0034] Furthermore, the internal state of the image forming device 1 switches between an operating state (operating state), a standby state, a sleep state, or the like, depending on the state of the internal circuit. For example, the operating state is an image forming state (printing state) in which an image or text data, etc. is printed on a paper medium, etc., in a copy mode, printer mode, or facsimile mode. Alternatively, the operating state is an image forming state (scanning state) in which an original document, etc. is scanned, in a scanner mode or facsimile mode. The state of the internal circuit is switched by a user's operation of the operation unit or by control within the image forming device 1.

[0035] For example, image forming apparatus 1 has an automatic document feeder 2 (ADF; Auto Document Feeder), an image reading device 3, a writing unit 4, a printer unit 5, and a power supply device 10. The printer unit 5 has a photoconductor drum 6, a developing device 7, a conveyor belt 8, a fixing device 9, and a storage space for storing a paper feed tray. The printer unit 5 creates a toner image to be transferred to a paper medium or the like based on image information. Below, as an example of the flow of image formation in image forming apparatus 1, a case where the operation mode is set to copy mode will be briefly described.

[0036] In the copy mode, multiple documents to be copied are set in the automatic document feeder 2. When a start button on an operation unit (not shown) is pressed, the automatic document feeder 2 feeds the documents one by one to the image reading device 3. The image reading device 3 reads the image information of each document sent in order from the automatic document feeder 2. The read image information is processed by an image processing unit (not shown).

[0037] The writing unit 4 converts the image information processed by the image processing unit into optical information. The photoconductor drum 6 is uniformly charged by a charger (not shown) and then exposed to laser light containing the optical information converted by the writing unit 4. An electrostatic latent image is formed on the photoconductor drum 6 by the exposure. The developing device 7 develops the electrostatic latent image on the photoconductor drum 6 to form a toner image on the photoconductor drum 6. The conveyor belt 8 transfers the toner image to a paper medium or the like. The fixing device 9 fixes the toner image to the paper medium or the like. The transfer paper on which the image of the original has been copied is then discharged from the discharge section.

[0038] For example, the above-mentioned standby state is the state in copy mode until the start button is pressed, and the operating state is the state from when the start button is pressed until paper media or the like is discharged, in which a load such as a motor is operating. After the operating state ends, the image forming apparatus 1 returns to the standby state, and if the standby state continues for a predetermined time, the image forming apparatus 1 goes into a sleep state. Then, if the operation unit is operated during the sleep state, the image forming apparatus 1 returns to the standby state.

[0039] The power supply device 10 converts an AC voltage AC1 supplied from an AC power supply 20 into a DC voltage DC2 (e.g., 24 V) and supplies the converted DC voltage DC2 to various loads such as the printer unit 5 of the image forming apparatus 1. For example, the loads 30 shown in Fig. 1 include various motors, a charger that charges the photoconductor drum 6, and a developing roller of the developing device 7. The image forming apparatus 1 may have a plurality of power supply devices 10 corresponding to the respective chargers and developing rollers.

[0040] Fig. 6 is a block diagram showing an example of a hardware configuration of the control unit 14 in Fig. 1. For example, the control unit 14 is configured with a microcomputer. The control unit 14 has a CPU 141, a ROM (Read Only Memory) 142, a RAM (Random Access Memory) 143, an input interface unit 144, and an output interface unit 145, which are interconnected via a bus BUS.

[0041] For example, the CPU 141 performs the operation shown in FIG. 3 or FIG. 4 by executing a control program stored in the ROM 142. The CPU 141 is an example of a computer. In addition to the control program, the ROM 142 may store various parameters used for controlling the power supply device 10, such as a threshold Vth. The RAM 143 stores work data and the like used for controlling the power supply device 10. For example, the CPU 141 temporarily stores the voltage information VINF received from the voltage detection unit 13 in the RAM 143. Note that, if the control unit 14 has an ADC (Analog-to-Digital Converter) built in, the ADC may convert the direct current voltage DC1 into a digital value. In this case, the CPU 141 can obtain the digital value converted by the ADC as the voltage information VINF, making it possible to eliminate the need for the voltage detection unit 13 shown in FIG. 1.

[0042] The input interface unit 144 receives, for example, a start signal ON and a stop signal OFF from the system, and receives voltage information VINF from the voltage detection unit 13. The CPU 141 operates based on the signals and information received by the input interface unit 144. The output interface unit 145 outputs control signals CNTL1 and CNTL2 based on instructions from the CPU 141, for example.

[0043] As described above, in this embodiment, when the amount of change in the DC voltage DC1 per predetermined time becomes equal to or less than the threshold value Vth, the subsequent circuit (DC / DC converter 12) is started, so that the DC / DC converter 12 can be started safely and quickly using the stable DC voltage DC1. That is, in the power supply device 10 having the AC / DC converter 11 and the DC / DC converter 12 which receives the DC voltage DC1 from the AC / DC converter 11 and generates the DC voltage DC2, the DC voltage DC2 can be quickly supplied to the load 30. As a result, for example, the start-up time of the image forming apparatus 1 can be shortened, and also the transition time from the standby state to the operating state of the image forming apparatus 1 can be shortened.

[0044] By setting the threshold Vth to a value greater than the static voltage accuracy of the DC voltage DC1, it is possible to prevent the control signal CNTL2 from being erroneously output due to voltage fluctuations within the standard after the DC voltage DC1 reaches the set voltage. Also, by setting the threshold Vth to a value smaller than the amount of change in the rise rate of the DC voltage DC1 during soft start, it is possible to prevent the control signal CNTL2 from being output, for example, immediately after the start-up of the AC / DC converter 11.

[0045] Second embodiment FIG. 7 is a flow diagram showing an example of startup control of the power supply device by the control unit in the power supply device of the second embodiment. Operations similar to those in FIG. 3 are given the same step numbers, and detailed explanations are omitted. The configuration of the power supply device 10 that performs the operations shown in FIG. 7 is similar to the configuration of the power supply device 10 shown in FIG. 1. For example, the power supply device of this embodiment has the control unit 14 (microcomputer) shown in FIG. 6, and is mounted on the image forming device 1 shown in FIG. 5. FIG. 7 shows an example of a method of controlling the power supply device 10 by the control unit 14. For example, FIG. 7 is realized by the control unit 14 executing a control program.

[0046] In the flow shown in Fig. 7, step S11 is inserted between steps S10 and S12, and step S19 is inserted between steps S18 and S20. The other processes are the same as those in Fig. 3. Note that, similarly to Fig. 4, the process may move to step S14 when a NO determination is made in step S18.

[0047] After step S10, in step S11, control unit 14 determines whether or not the voltage value DC1 of direct current voltage DC1 acquired via voltage detection unit 13 is equal to or greater than the minimum voltage (minimum inputtable voltage) at which DC / DC converter 12 can operate. For example, the minimum inputtable voltage of DC / DC converter 12 is 24V.

[0048] If DC voltage DC1 is equal to or greater than the minimum input voltage, control unit 14 determines that DC / DC converter 12 will be able to operate normally when started, and executes step S12. If DC voltage DC1 is lower than the minimum input voltage, control unit 14 determines that DC / DC converter 12 may not operate normally when started, and returns to step S10. Alternatively, if DC voltage DC1 is lower than the minimum input voltage, control unit 14 determines that DC / DC converter 12 may fail, and returns to step S10.

[0049] On the other hand, after the determination in step S18 is YES, in step S19, control unit 14 determines whether or not the voltage value DC1 acquired via voltage detection unit 13 is equal to or less than the rated input voltage. For example, the rated input voltage is 36 V. If DC voltage DC1 is equal to or less than the rated input voltage, control unit 14 determines that DC / DC converter 12 can operate normally upon startup, and executes step S20.

[0050] If DC voltage DC1 is higher than the rated input voltage, there is a risk that DC / DC converter 12 may not operate normally upon startup, or that DC / DC converter 12 may fail. In this case, control unit 14 repeats step S19 until DC voltage DC1 becomes equal to or lower than the rated input voltage.

[0051] The control unit 14 may perform only one of the determinations of steps S11 and S19. When performing only step S11, the control unit 14 performs step S20 if it determines YES in step S18. When performing only step S19, the control unit 14 performs step S12 after performing step S10.

[0052] As described above, this embodiment can also provide the same effects as the above-mentioned embodiment. For example, the DC / DC converter 12, which is a subsequent circuit, can be started safely and quickly using a stable DC voltage DC1. This can shorten the start-up time of the image forming apparatus 1 equipped with the power supply device 10, and can also shorten the transition time from the standby state to the operating state.

[0053] Furthermore, in this embodiment, when DC voltage DC1 is lower than the minimum voltage that can be input to DC / DC converter 12, control unit 14 suppresses execution of the start-up determination process for DC / DC converter 12. This allows control unit 14 to prevent abnormal operation or failure of DC / DC converter 12. Similarly, when DC voltage DC1 is higher than the rated input voltage of DC / DC converter 12, control unit 14 suppresses the start-up of DC / DC converter 12, thereby preventing abnormal operation or failure of DC / DC converter 12.

[0054] It should be noted that the device in which the above-described power supply device 10 is mounted is not limited to the image forming device 1 shown in Fig. 5. The power supply device 10 may be mounted in, for example, a PJ (Projector), an IWB (Interactive White Board: a white board having an electronic blackboard function capable of mutual communication), an output device such as digital signage, a HUD (Head Up Display) device, industrial machinery, an imaging device, a sound collection device, medical equipment, a network home appliance, an automobile (Connected Car), a notebook PC (Personal Computer), a mobile phone, a smartphone, a tablet terminal, a game machine, a PDA (Personal Digital Assistant), a digital camera, a wearable PC, a desktop PC, or the like.

[0055] Although the present invention has been described above based on the embodiments, the present invention is not limited to the requirements shown in the above embodiments. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of symbols]

[0056] 1. Image forming device 2 Automatic document feeder 3. Image Scanning Device 4 Write Unit 5 Printer unit 6 Photoconductor drum 7. Developing device 8 Conveyor belt 9 Fixing device 10 Power supply 11 AC / DC converter 12 DC / DC converter 13 Voltage detection section 14 Control section 20 AC power supply 30 Load 141 CPU 142 ROM 143 RAM 144 Input interface section 145 Output interface section AC1 AC voltage CNTL1, CNTL2 control signals DC1, DC2 DC voltage ON Start signal OFF stop signal VINF voltage information [Prior art documents] [Patent documents]

[0057] [Patent Document 1] JP 2010-187481 A

Claims

1. a voltage generating unit that starts generating an output voltage based on a start-up instruction and increases the output voltage to a set voltage; a control unit that determines whether a change amount of the output voltage per predetermined time is smaller than a preset threshold value, and when the change amount is smaller than the threshold value, outputs a control signal to start a subsequent circuit that operates in response to the output voltage; having the control unit, after determining that the amount of change in the output voltage has become smaller than the threshold value, outputs the control signal when the output voltage has decreased to or below the rated input voltage in a case where the output voltage is higher than the rated input voltage of the subsequent stage circuit. A power supply device comprising:

2. When the output voltage becomes equal to or higher than a minimum voltage at which the subsequent stage circuit can operate, the control unit starts to determine whether or not a change in the output voltage per predetermined time period is smaller than the threshold value.

2. The power supply device according to claim 1 .

3. The rear stage circuit is provided. the voltage generating unit is either an AC / DC converter or a DC / DC converter, The latter circuit is a DC / DC converter that generates a power supply voltage to be supplied to a load in accordance with the output voltage.

3. The power supply device according to claim 1 or 2,

4. 1. A method for controlling a power supply device having a voltage generating unit that starts generating an output voltage based on a startup instruction and increases the output voltage to a set voltage, comprising: determining whether or not a change in the output voltage per unit time is smaller than a preset threshold value; If the amount of change is smaller than the threshold value, a control signal is output to start a subsequent circuit that operates in response to the output voltage; and outputting the control signal when the output voltage is lower than the rated input voltage of the subsequent circuit after it is determined that the change in the output voltage is smaller than the threshold value and the output voltage is higher than the rated input voltage of the subsequent circuit. A method for controlling a power supply device comprising the steps of:

5. 1. A control program for a power supply device having a voltage generating unit that starts generating an output voltage based on a startup instruction and increases the output voltage to a set voltage, determining whether or not a change in the output voltage per unit time is smaller than a preset threshold value; If the amount of change is smaller than the threshold value, a control signal is output to start a subsequent circuit that operates in response to the output voltage; a process of outputting the control signal when the output voltage is higher than a rated input voltage of the subsequent circuit after determining that the change in the output voltage is smaller than the threshold value and the output voltage is lower than or equal to the rated input voltage; A power supply device control program executed by a computer installed in the power supply device.

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