JPH0619564A - Power unit - Google Patents

Abstract

PURPOSE:To determine a controlled variable by formulizing fuzzy relation between a parameter and the controlled variable by fuzzy inference. CONSTITUTION:The CPU core 100 of a CPU calculates the degree of adaption of a detected state quantity according to a membership function of a state quantity stored in a ROM 101. Then inference results of respective rules stored in the ROM 101 are found by specific arithmetic from the calculated degree of adaption and a manipulated variable is calculated according to the results to perform the fuzzy inference. Further. the ROM 101 is stored with a sequence control program in addition to the membership function and fuzzy rules. An A/D converter 106 detects an output voltage as a state quantity detecting means and converts various analog quantities into digital quantities which can be processed by the CPU to detect the output voltage of the power unit 107. Namely, the detection of the load current of a low-voltage power source, the current detection of a high-voltage power source, and the detection of the primary-side current and voltage are performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit used in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art In a power supply device used in a conventional copying machine or printer, a power supply output to be supplied to various control circuits for realizing a sequence of an electrophotographic process and various high voltage power supplies for realizing an electrophotographic process. The power output for the exposure lamp and the exposure lamp are obtained from the same transformer in the power supply.

Further, various power supply control circuits for controlling the output of the transformer, such as high voltage and low voltage, are carried out by the same microprocessor as the sequence controller of the copying machine or the printer. By adopting such a configuration, the entire power supply device is downsized.

[0004]

However, since the output of the conventional power supply device having the above configuration is a follow-up output, there are the following problems. That is, the load condition changes greatly according to the sequence for image formation in a copying machine or printer, for example, by turning on / off various solenoids and motors. At the same time, some copiers control the main control voltage to a predetermined voltage when the copy sequence shifts to the standby state at the end of copying. However, at this time, the output of the follow-up windings other than this may decrease more than the above-mentioned control.

This is because the control target is the main control voltage, the motor and solenoid are turned off at the end of the copy sequence, the load of the main control voltage becomes very light, and the discharge amount of the main control system decreases. At this point, the power supply voltage for main control is lowered by shifting from the copy sequence to the standby state, so the output pulse under pulse width control (PWM control) is stopped for a certain period of time, or the pulse width is extremely low. This is because it may become narrower.

In such a state, for example, when the output of the follow-up winding does not change even when the pulse is stopped or the pulse width is narrowed, due to various restrictions, the capacitor alone holds the output. There will be situations where you cannot handle it. Then, when the power supply output from these windings is used to turn on the display, for example, the display disappears when the pulse is stopped, or the control device using this power supply malfunctions. There is a possibility.

With respect to these problems, focusing on the use of a microprocessor for control, a method of preliminarily holding data in a storage unit inside the microprocessor and changing the control constant in accordance with this data may be considered. However, if the control is simple, such a method can be used, but in the conventional power supply device, as described above, when the number of outputs or parameters (state quantities) becomes large or the sequence becomes complicated. Or, if there is an ambiguous relation between the load of the power supply unit and the control state among the parameters, it becomes difficult to formulate the relation between the parameter and the control amount, and they are not calculated by the microprocessor. It cannot be easily shown by the judgment formula.

[0008]

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following structure as one means for solving the above-mentioned problems. That is,
According to a first aspect of the present invention, a part of the output is fed back to perform power supply control, and in a power supply device that supplies a desired voltage, means for detecting a state quantity related to the power supply control, and power control. According to a rule output from the rule means, a rule means for relating the relationship between the state quantity and the operation quantity as a qualitative rule, and a state quantity belonging to a predetermined set. An inference means for inferring the manipulated variable based on the degree, and when changing the current output control voltage to a target control voltage according to a predetermined sequence, the control voltage is set in a preset voltage variable width. The target control voltage is changed while changing.

According to a second aspect of the present invention, a state quantity based on an input voltage or an output current to a load is supplied to a power supply device that feeds back a part of an output to control a power supply and supplies a desired voltage. A means for detecting a state quantity, a means for performing a predetermined process on the state quantity to generate a new state quantity, and a means for generating an operation quantity at the time of power supply control,
A first storage means for storing a membership function in which a new state quantity and an operation quantity are respectively expressed by fuzzy sets, and a rule for storing the new state quantity and operation quantity in a fuzzy proposition form. 2 storage means, a first calculating means for calculating the degree of conformity, which is the degree of belonging to a predetermined set for the new state quantity, based on the membership function, and the second calculating means based on the degree of conformity. The calculation means for calculating the inference result of the rule stored in the storage means, and the second calculation means for calculating a predetermined voltage variable width based on the rule calculated by the calculation means are provided. Control power output based on width.

[0010]

In the above configuration, fuzzy reasoning formulates an ambiguous relationship between parameters and control amount in power supply control, and functions to determine the control amount.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. [Configuration of Power Supply Device] First, the configuration of the power supply device used in the copying machine or the printer according to the embodiment of the present invention will be described.

5 and 6 are block diagrams showing an example of the overall configuration of the power supply unit for the copying machine and printer according to this embodiment. In the figure, the primary charger A, the developing device B, the transfer charger C, the photosensitive drum D, and the fluorescent lamp E correspond to the main parts of the copying machine or printer, and these are around the electrophotographic process of the copying machine or printer. Are configured. Hereinafter, the power supply device of the copying machine or the printer having the above configuration will be described.

5 and 6, a microprocessor (hereinafter referred to as CPU) 1 is a processor for performing sequence control, process control, or various power supply control, and a power supply control driver block 2 is an output of a pulse output terminal MOUT of the CPU 1. In response to this, insulation between the primary side and the secondary side of the power supply and boosting are performed, and the power MOSFET (Q
3) is converted into a level for switching. This power MOSFET (Q3) has a pulse transformer CT1
Is connected to detect the current on the primary side of the power supply.

The commercial AC input / rectifier unit 3 is composed of an input filter and a rectifier unit consisting of a diode bridge and a rectifying capacitor. The main transformer T1 generates various power supply voltages, one end of which is a commercial side. AC input
The primary side power supply is connected via the rectification unit 3. At the other end, power MO via the power control driver block 2.
The SFETs are connected to perform switching, and voltages corresponding to these are output to the secondary side of the main transformer T1 to supply power to each unit.

On the secondary side of the main transformer T1, a high voltage output HVPT composed of a diode D7, a capacitor C10, a high voltage discharge resistor Rh1, etc., a transfer charger C, and a resistor R.
The primary charger A is connected via h6. The shield of the transfer charger C is grounded to the ground of the secondary side circuit,
The shield of the primary charger A is connected to the ground via resistors Rh7, Rh8 and a capacitor Ch1. Also, the diode D8, the capacitor C11, and the diode D
Various low-voltage output rectifier circuits including the capacitor 6 and the capacitor C9, the capacitors C5 to C8 and the diode D5, and the three-terminal regulator Q6 are supplied to various electronic circuits and loads such as solenoids as V _S , V _CC3 , and V _CC2 , respectively.

High voltage output HVB from the rectifying / output adjusting circuit composed of capacitor C12, diode D9, resistors Rh2, 3, 4, 5 and control transistor Q7.
Is superposed on the AC output by the developing bias AC superimposing circuit 15 and output to the developing device B. Further, the fluorescent lamp E is a fluorescent lamp for exposing the original, and a sensor PC1 for detecting the light amount of the fluorescent lamp E is located in the vicinity of the fluorescent lamp E, and the output of this sensor causes the level conversion unit 10 to be detected. Through CPU1
Connected to the AD4 terminal.

To the fluorescent lamp E, a choke coil L1 connected to the winding of the transformer T1 and capacitors C9 and C1.
0, the power source constituted by the fluorescent lamp driver block 12 is supplied, and the sensor output is input to the CPU 1 via the level conversion unit 10, and the CPU 1 lights up in response to the ON / OFF signal so that the desired light amount is obtained. Or operates as a driver for controlling the light amount according to the light amount of the sensor PC1 described above.

This power supply device is provided with detection means for detecting various state quantities. For example, a current transformer CT1 as current detection means is connected to the primary side together with the power supply control driver 2 described above. This current transformer C
The output of T1 is output via the output holding / level converting unit 16.
The current is input to the analog input terminal AD7 of the CPU 1 and the current on the primary side of the power supply is detected. Also, the diode D
High voltage output circuit HVP consisting of 7, capacitor C10, etc.
At T, the current detection resistor RS is connected between the low voltage side of the winding and the ground.
1 for detecting the high voltage output HVPT current. The voltage V _PT between the connection point of the resistor Rh1 and the resistor RS1 and the ground is the voltage holding / level converting unit 9
And is input to the analog input terminal AD3 of the CPU1.

Further, between the low voltage side of the low voltage power source and the ground
Similarly, a resistor R for current detection _S2Is connected,
Voltage V_S2Through the voltage holding / level conversion unit 7 to the CPU
1 is input to the analog input terminal AD1. Auxiliary power supply
Lock 6 uses the power required to start the power supply such as CPU1.
Source V_CC1 Value that is proportional to the input voltage on the primary side of the power supply
Are taken into CPU1.

Further, a capacitor C11 and a diode D
And a low voltage output circuit composed of 8 outputs a voltage V _S ,
After the output voltage is converted to a level that can be taken into the CPU 1 by the voltage detection unit 5, the analog input terminal A of the CPU 1
Input to D0. The voltage holding / level conversion unit 7,
9. The level conversion unit 10 has an input protection circuit (not shown) as in the level conversion blocks 8, 11 and 14 described later. [Basic Operation of Power Supply Device] Next, the basic operation of the power supply device according to the present embodiment will be described.

The power supply control in this power supply device is performed by the CPU 1, and as described above, the output voltage V from the low voltage output circuit composed of the capacitor C11 and the diode D8.
_{When S} is input to the analog input terminal AD0 of the CPU 1 via the voltage detection unit 5, the CPU 1 causes the divided value of the output voltage V _{S and} the predetermined value held in the internal data holding means (not shown). The pulse width control (PWM) output signal based on the pulse width control is performed by comparing with MOUT.
It is output from the terminal. As a result, the power supply control driver 2 is driven to form a feedback loop, and the transformer T
The output of 1 is PWM-controlled.

The high voltage output HVB is obtained by rectifying the output of the transformer T1 as a developing bias power source into a DC voltage by a rectifying / output adjusting circuit composed of a diode D9 and a capacitor C12, and this output is obtained. , AC is superposed by the developing AC superposing circuit 15 as described above, and the developing device B
Is supplied to. In a copying machine or a printer which receives power supply from the power supply device according to this embodiment, the density of the original is adjusted by the developing bias. DC of this developing bias power supply
The voltage control is performed by inputting the output VB divided by the resistors Rh4 and Rh5 to the level conversion block 8 and inputting the level-converted output to the AD2 terminal of the CPU1, and
The value of the density adjusting volume (VR1) 13 is taken into the AD6 terminal of the CPU 1 via the level conversion unit 14, and AD2
Is performed by comparing the values of AD6 and AD6 and controlling to a desired bias value.

In the power supply device according to the present embodiment, the above-mentioned comparison result is PWM-controlled and output as a pulse to the BOUT terminal of the CPU 1, and this is output to the transistor Q.
7. The voltage is controlled by the driver composed of the resistors Rh2 and Rh3. A voltage proportional to the primary voltage of the power supply is taken out from the auxiliary power supply block 6 and input to the AD5 terminal of the CPU 1 via the level conversion block 11. Further, as described above, the output voltage V _PT of the resistor RS1 between the low voltage side winding of the high voltage output HVPT and the ground is input to the AD3 terminal of the CPU 1 via the level conversion block 9. Regarding the voltage across the resistor RS2 between the transformer low voltage side winding and the ground of the low voltage output circuit. It is input to the AD1 terminal of the CPU 1 via the level conversion block 7. Further, the shield of the primary charger A is grounded via a circuit composed of resistors Rh7 and Rh8 and a capacitor Ch1, and the divided voltage value V _HVS by these resistors is sent to the CPU 1 via the level conversion block 17. Of the AD8 terminal.

The power supply device of this embodiment controls from the following viewpoints. (1) It is used to prevent overshoot when the power supply voltage rises when the low-voltage output shifts from the predetermined standby mode to the copy mode. Also, the same control is performed during the startup operation when the power is turned on. (2) It is also used for the voltage drop sequence when the low voltage output shifts to the standby mode. (3) The control of (1) and (2) is performed by changing the control value of the power supply control. That is, a predetermined power supply voltage variable width is set between the current control value and the next target value to be changed and gradually changed. (4) There are a wide variety of power output, such as various high voltage output and low voltage output for feeding various electrophotographic processes. Each output performs complicated operation according to the sequence of equipment, and the load also changes depending on the sequence of equipment. Since it is complicated, it cannot be simply formulated. Therefore, in this power supply device, fuzzy inference is performed on the control amount of the power supply (in this case, the variable range of the power supply voltage) based on various output voltages, various states such as current and input voltage on the primary side of the power supply to determine the control amount I will do it. [Description of Main Control Unit] Next, the main control unit of the power supply device according to the present embodiment will be described.

FIG. 1 is a block diagram showing the configuration of a microprocessor (CPU) which is the main control part of the power supply device of this embodiment. As shown in the figure, the CPU core 100, which is the core of the CPU, serves as a fitness calculating means to calculate the fitness of the detected state quantity based on the membership function of the state quantity stored in the ROM 101. calculate. Then, the RO is calculated by a predetermined calculation based on the calculated compatibility.
The inference result of each rule stored in M101 is obtained, the operation amount is calculated based on the result, and fuzzy inference is performed.

The counter 100a and the timer 100b are
It is used respectively when the rate of change is detected from the detected state quantity, for example, the output voltage of the power supply. ROM
Reference numeral 101 is a memory for storing membership functions and fuzzy rules.
In addition to a and the membership functions 101b and 101c, a sequence control program and the like are also stored. Further, the RAM 102 is used as a work area (work area) when performing fuzzy inference.

The serial I / O 103 is an I / O for enabling communication with the outside, and also the I / O 104.
Is an interface for transferring the output signal, and C
It has a function of outputting a signal from the PU core 100 to the outside. Then, the pulse width control unit 105 controls the power supply device 1
A circuit block for controlling 07, which corresponds to a control circuit for various low-voltage power supplies and high-voltage power supplies in the power supply device, and outputs various pulses.

In the power supply device 107, the driver 10
7a drives the transformer (not shown) in the power supply device by the control output from the pulse width control unit 105. That is, the power supply device 107 is the power supply control driver 2 shown in FIGS.
And outputs power to various loads 109 in response to a signal from the driver 107a. The load 109 is, for example, a solenoid, and if it has a high voltage, it corresponds to a charger or a developer in an electrophotographic process.

The A / D converter 106 detects the output voltage as state quantity detecting means, and outputs various analog quantities as C
The power supply device 10 after converting into a digital amount that can be processed by the PU
The output voltage of 7 is detected. That is, the A / D converter 106
5 detects the load current of the low-voltage power supply, the current of the high-voltage power supply, and the current and voltage of the primary side.
Output V _S2 of the output V _PT and R _S2 of R _S1 shown in, voltage corresponding to each voltage such as a voltage V _CP output at the output holding level converter 16 via a current transformer CT1 is input It

In the power supply device according to this embodiment, the CPU
Core 100, counter 100a, timer 100b, R
OM101, RAM102, serial I / O103, I
The / O port 104, the pulse width control unit 105, and the A / D converter 106 are assumed to be configured on the same chip. [Explanation of Fuzzy Control] In the fuzzy control in the power supply device of the present embodiment, the input voltage on the primary side of the power supply as the state quantity,
Among the difference between the current control voltage value and the control voltage value that changes next, that is, the power supply voltage difference, the output current of the low voltage power supply, the output voltage of the low voltage side, etc., for example, (a) the power supply input voltage of the primary side ( b) The power supply voltage difference is used, and (C) the voltage control change amount of the main control of the power supply device is used as the operation amount.

FIG. 3 shows the membership functions of the above set. FIG. 3 (a) is a membership function of the power supply input voltage on the primary side of the power supply device, and FIG. 3 (b) is the power supply voltage. Membership function of difference, and Figure 3 (c)
Indicates a voltage control change amount of main control of the power supply device. As is apparent from FIG. 3, the power supply input voltage on the primary side, the power supply voltage difference, and the main control change amount (output of the pulse output terminal MOUT) of the power supply device each have three fuzzy sets.

For example, for three fuzzy sets of the primary side power supply input voltage, "EL",
"EM" and "EH" are attached, respectively. EL: Fuzzy set representing "the power supply input voltage on the primary side is small" EM: Fuzzy set representing "the power supply input voltage on the primary side is medium" EH: A fuzzy set representing “the primary side power supply input voltage is large”.

The degree of belonging to each set takes an arbitrary value between "0" and "1", and in the case of the fuzzy set with the fuzzy label EM shown in FIG. The degree of belonging to the set of input voltage 100V, that is,
The suitability is “1.0”, and the suitability when the power supply input voltage on the primary side is small (90 V) or large (120 V) is “0.5”.

To determine the voltage control change amount of the main control in the power supply device according to this embodiment, for example, the following <Rule 5 is used.
>, And the fuzzy rules of <Rule 6> are used. <Rule 5> IF (E = EM AND VS = VSM) THEN DV = DVM <Rule 6> IF (E = EM AND VS = VSH) THEN DV = DVL where E = primary power supply input voltage VS = power supply voltage Difference DV = Voltage control change amount of main control of power supply device. Note that all fuzzy rules are shown in FIG.

Next, a method of determining the voltage control change amount of the main control in this power supply device based on the inference method of <rule 5> and <rule 6> will be described. First, <Rule 6>
4A, for the power supply input voltage x on the primary side, the membership function of the power supply input voltage on the primary side is included in the EM set at a degree of μx, and the power supply voltage difference y is On the other hand, it is included in the set of VSH with a degree of μy by the membership function of the power supply voltage difference (FIG. 4B). Then, the minimum value of the obtained μx and μy is taken, and the minimum value is taken as the degree to which the condition part of <Rule 6> is satisfied, and that value and the voltage control change amount of the power supply device that is the main control of the power supply device MI with membership function
Take N operations. The calculation result is the set S shown in FIG.
It becomes the trapezoid shown by (shaded part).

Similarly, when inferring according to <Rule 5>,
The calculation result is a trapezoid shown by a set T (hatched portion) shown in FIG. Then, when the inference result of each rule obtained, that is, the set S and the set T are combined, FIG.
In the set U (hatched portion), the center of gravity (point P) of this set is calculated, and the voltage control change amount of the main control of the power supply device is obtained based on this result.

As described above, according to this embodiment,
Power supply input voltage on the primary side of the power supply, power supply voltage difference,
Then, the fuzzy control is used to calculate the optimum control amount for the voltage control change amount, the mutual comparison result of these, and the ambiguous variable factors (state amounts) that are related to each other. By obtaining the voltage change amount of the main control, there is an effect that output control with less overshoot or undershoot can be performed.

In the above embodiment, fuzzy rules, membership functions, control programs, etc. are stored in the ROM and the RAM is used for calculation. However, the operation amount corresponding to the input of the state amount is calculated in advance. The control may be performed using a ROM that outputs this value. Further, the state quantity is not limited to the power supply input voltage on the primary side or the output current of the low-voltage power supply, but may be, for example, the output voltage of the low-voltage power supply, the output current of the low-voltage power supply, the load current of the high-voltage power supply, or the state quantity related to power supply control. If so, they can be used as state quantities.

Furthermore, the number of state quantities is not limited to two,
A larger number of state quantities may be combined. Further, the above fuzzy inference algorithm is an example, and the algorithm may be modified. For example, when synthesizing a plurality of rules, instead of taking the center of gravity of the area, the value on the horizontal axis with respect to the maximum value on the vertical axis may be used as the inference result. Further, the number and contents of fuzzy rules can be modified based on experience. <Modification 1> A first modification of the above-described embodiment will be described.

When changing the control voltage of the power supply device including the sequence of rising and falling, in order to change the current voltage value to the target voltage value, the sequence is configured to change every predetermined voltage width. Thus, a rising overshoot prevention function using the function of the above embodiment can be added. In the rising sequence, a soft start method is usually used to prevent overshoot. In order to activate by soft start, the control pulse width is gradually increased rather than being maximized at the same time as activation, but in this modification, as shown in FIG. Utilizing the fact that the output can be controlled by changing the set value of software as described above, soft start can be performed by sequentially switching the control voltage.

Specifically, as shown in the flow chart of FIG. 7, the current control value (Va) is read (step S
In step 1), the control value (Vb) to be changed next is set (step S2), and it is determined in step S3 whether the power supply voltage is raised or lowered. If it is at the time of rising, in step S4, Va is calculated by the above fuzzy inference.
The ΔV at which + ΔV becomes Vb is calculated. If it is at the fall, in step S5, ΔV at which Va−ΔV becomes Vb is obtained. That is, the soft start function can be realized by changing the control voltage value to the voltage variable width obtained by fuzzy inference and then shifting to the target control voltage. <Modification 2> In this modification, the output current IL of the low-voltage power supply corresponding to the voltage across the resistor R _S2 in FIG. 5 in the above embodiment is used as the state quantity for fuzzy control.

FIG. 8 shows all fuzzy restrictions according to the present modification. In the figure, ILL, ILM, and ILH are respectively: ILL: Fuzzy set representing "small load current of high-voltage power supply" ILM: "high voltage" A fuzzy set representing "the load current of the power supply is medium" ILH: A fuzzy set representing "the load current of the high-voltage power supply is large".

Since the method of obtaining the voltage variable width in the power supply device according to this modification is the same as the method in the above-mentioned embodiment, its explanation is omitted here. <Modification 3> In this modification, the output voltage VF of the low-voltage power supply is used as the state quantity for fuzzy control.

FIG. 9 shows an all fuzzy regulation according to this modification, in which VFL, VFM, and VFH are respectively a fuzzy set VFM: "low output voltage of low-voltage power supply" VFM: "low voltage" A fuzzy set representing "the output voltage of the power supply is medium" VFH: A fuzzy set representing "the output voltage of the low voltage power supply is large".

The method of obtaining the voltage variable width in the power supply device according to this modification is also the same as the method in the above-mentioned embodiment, and therefore its explanation is omitted. The present invention may be applied to a system including a plurality of devices or an apparatus including a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0046]

As described above, according to the present invention,
The output control of the power supply with less overshoot and undershoot is performed by formulating the optimum control amount by fuzzy reasoning based on the load state and output of the power supply and other ambiguous fluctuation factors (state quantities) that are related to each other. The effect is that you can.

Further, since the control amount is determined based on a plurality of parameters, even if there is an error in a part of the input data,
It is possible to prevent a large error in the control amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a microprocessor (CPU) that is a main control unit of a power supply device of this embodiment,

FIG. 2 is a diagram showing all fuzzy regulations in an embodiment,

FIG. 3 is a diagram showing a membership function according to an embodiment,

FIG. 4 is a diagram for explaining a method of obtaining a voltage control change amount of main control in the power supply device of the embodiment;

FIG. 5 is a block diagram showing an example of the overall configuration of a power supply device for a copying machine or printer according to an embodiment;

FIG. 6 is a block diagram showing an example of the overall configuration of a power supply device for a copying machine or printer according to an embodiment;

FIG. 7 is a flow chart showing a soft start control in Modification 1.

FIG. 8 is a diagram showing an all-fuzzy regulation according to a modified example 2,

FIG. 9 is a diagram showing an all-fuzzy regulation according to a modification example 3.

[Explanation of symbols]

 3 Commercial AC input / rectifier 7,9 Voltage holding / level converter 10 Level converter 8,11,14 Level conversion block 12 Fluorescent lamp driver block 15 Development bias AC superimposing circuit 16 Output holding / level converter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H02J 1/00 306 B 7373-5G H02M 3/00 H 8726-5H // G05B 13/02 N 9131 -3H

Claims (2)

[Claims] 1. A power supply device for feeding back a part of an output to control a power supply and supplying a desired voltage, and a means for detecting a state quantity related to the power supply control and an operation amount for performing the power supply control. A means for generating, a rule means for relating the relationship between the state quantity and the operation quantity as a qualitative rule, and according to a rule output from the rule means, based on the degree to which the state quantity belongs to a predetermined set. , An inference means for inferring the manipulated variable, and changing the current output control voltage to a target control voltage according to a predetermined sequence while changing the control voltage with a preset voltage variable width. A power supply device characterized in that the control voltage is changed. 2. A means for detecting a state quantity based on an input voltage or an output current to a load in a power supply device for supplying a desired voltage by feeding back a part of the output to control the power supply, and the state quantity. To generate a new state quantity by performing a predetermined process on, a means to generate a manipulated quantity for power supply control, and a new state quantity and a manipulated quantity represented by fuzzy sets. A first storage means for storing a function, a second storage means for storing a rule expressing a new state quantity and an operation quantity in the form of a fuzzy proposition, and a degree of belonging to a predetermined set for the new state quantity First calculating means for calculating the goodness of fit based on the membership function, and computing means for obtaining the inference result of the rule stored in the second storing means based on the goodness of fit. Based on the rules determined by the computing unit and a second calculating means for calculating a predetermined voltage variable width, power supply and controls the power output based on the calculated voltage variable width.