JPH04322124A - Protective method and device for power supply circuit - Google Patents

Abstract

PURPOSE:To provide protective method and device for power supply circuit wherein the protective control is determined according to a qualitative rule based on parameters(state quantity) for determining the protective operation of the power supply circuit. CONSTITUTION:Status quantity concerning at least one of the operating state arid the load state of a power supply circuit 105 is detected or inputted, and the adaptability of the inputted status quantity is then calculated based on the membership function 132 or 133 thereof. Inference results are then obtained through operation based on thus calculated adaptability according to fuzzy rules 131 representing the relation between the status quantity and the output operating quantity in the form of fuzzy proposition. Operating quantity is then calculated based on inference results of respective rules and the output of the power supply circuit 105 is regulated according to thus calculated operating quantity thus protecting the power supply circuit 105.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to switching, for example.
The present invention relates to a method and device for protecting power supply circuits such as regulators.

0002

2. Description of the Related Art Conventionally, overcurrent prevention circuits using operational amplifiers and the like are well known as protection circuits for power supply circuits. There are also overheat prevention circuits that cut off the output of the power supply circuit when it detects that the power supply circuit has become abnormally high in temperature. In such a protection circuit, PWM (pulse width modulus) is generated by the output of the current detection circuit.
ion) The power supply circuit is protected by directly controlling the control circuit, or by turning off the output of the power supply circuit when an abnormally high temperature is detected by a temperature detection element such as a thermoswitch.

0003

However, in the above-mentioned conventional example, in the case of a power supply circuit for a copying machine, for example, the current load thereof may vary greatly depending on, for example, the operating state of the motor. In such a case, the protection circuit may malfunction in response to changes in the current load, and the power supply may be cut off. In order to eliminate such malfunctions in the power supply circuit, it is necessary to increase the number of parameters (state quantities) for detecting abnormalities in the power supply circuit, but as the number of parameters to be detected increases, In cases where the corresponding control becomes complex and there are parameters whose relationship with the manipulated variable is ambiguous, it is necessary to formulate the relationship between these parameters and the control of the power supply circuit. The problem is that even if many parameters are detected, protection control cannot be performed accordingly.

The present invention has been made in view of the above-mentioned conventional example, and is based on parameters (
It is an object of the present invention to provide a protection method and apparatus for a power supply circuit, in which protection control of the power supply circuit is determined based on rules related as qualitative rules based on state quantities).

[0005]

Means for Solving the Problems In order to achieve the above object, the power supply circuit protection device of the present invention has the following configuration. That is, a protection means that protects the power supply circuit by adjusting the output of the power supply circuit according to the amount of operation; a state quantity input means that detects or inputs a state quantity of the power supply circuit related to protection of the power supply circuit; a rule means for associating the relationship between the state quantity and the manipulated variable as a qualitative rule; and in accordance with the rule output from the rule means, the manipulated variable is inferred based on the degree to which the state quantity belongs to a predetermined set. and inference means to do so.

In order to achieve the above object, the power supply circuit protection method of the present invention has the following configuration. That is, a step of detecting or inputting a state quantity related to at least one of the operating state of the power supply circuit and the load state of the power supply circuit;
The process of calculating the fitness of these input state quantities based on the membership function of the state quantities, and the process of calculating the fitness of the input state quantities according to rules expressing the relationship between the state quantities and the manipulated variables to be output in the form of fuzzy propositions. A step of obtaining an inference result by a predetermined calculation based on the calculated fitness degree, a step of calculating the operation amount based on the obtained inference result of each rule, and an output of the power supply circuit according to the operation amount. and adjusting the power supply circuit to protect the power supply circuit.

[0007]

[Operation] In the above configuration, the state quantity related to at least one of the operating state of the power supply circuit or the load state of the power supply circuit is detected or input, and the fitness of the input state quantity is calculated based on the membership of the state quantity. Calculate based on a function. Then, according to rules expressing the relationship between the state quantity and the manipulated variable to be output in the form of fuzzy propositions, inference results are obtained by predetermined calculations based on the calculated fitness, and each of the obtained rules is The operation amount is calculated based on the inference result, and the output of the power supply circuit is adjusted according to the operation amount to protect the power supply circuit.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of a power supply device according to an embodiment of the present invention.

In FIG. 1, reference numeral 100 denotes a CPU such as a microprocessor, which converts the goodness of fit of the state (state quantity) of the power supply circuit detected by each sensor described later into the membership function of the state quantity stored in the ROM 101. Calculated based on Then, based on this calculated fitness,
The fuzzy inference of the power supply circuit 105 is performed by obtaining inference results based on each fuzzy rule stored in the ROM 101 through predetermined calculations, and calculating the operation amount according to the inference result of each of the obtained rules. 121 is a counter, 122
is a timer, and these counter 121 and timer 122 are respectively used when calculating the rate of change in the output voltage of current from the detected state quantity of the power supply 105, for example, the output voltage of the power supply 105.

A ROM 101 includes membership function storage sections 132 and 133, and a storage section 131 for storing fuzzy rules shown in FIG. 2, for example. The membership function 132 stores, for example, a membership function of a temperature margin and a load current, which will be described later, and the membership function 133 stores, for example, a membership function of a duty ratio of a PWM control pulse width for controlling the power supply circuit 105. I remember. Note that this ROM 101 includes fuzzy rules 131, membership functions 132,
133, control programs for the CPU 100 and various data are stored. A RAM 102 is used as a work area when performing fuzzy inference or when the CPU 100 operates.

103 is a power supply circuit 105 from the CPU 100.
An interface (I/O) unit for transferring output signals to the CPU converts a digital signal from the CPU 100 into an analog signal and outputs the analog signal to the driver 104. 104 is a driver, which is calculated and outputted by the CPU 100 by fuzzy inference, and an analog value (operated amount) that is D/A converted.
Accordingly, the power supply circuit 105 is controlled. A power supply circuit 105 is controlled based on fuzzy inference, and supplies power to the load 106 based on a signal from the driver 104.

[0013] Reference numeral 106 is a load, for example, a motor in this case. A temperature sensor 107 detects the temperature of the components of the power supply circuit 105 and the room temperature. An output voltage sensor 109 detects the output voltage of the power supply circuit 105. 11
A sensor 1 detects the load current, and detects the value of the current flowing through the load 106. 108, 110 and 112 are A
The /D converter converts analog signals from the temperature sensor 107, output voltage sensor 109, and load current detection sensor 111 into digital signals, and outputs the digital signals to the CPU 100.

In this embodiment, the state quantities include the output voltage of the power supply circuit 105, the rate of change of the output voltage of the power supply circuit 105, the load current of the power supply circuit 105, the rate of change of the load current of the power supply circuit 105, and the power supply circuit. Among the temperatures of the components 105, the rate of change in temperature of those components, the operating current of the components, etc., for example, the temperature of the components of the power supply circuit 105 and the load current of the power supply circuit 105 are adopted, and the manipulated variables are , for example, the rate of change in the duty ratio of the PWM control pulse width output to the driver 104.

FIG. 2 shows how PWM is calculated from temperature margin and load current.
FIG. 3 is a diagram illustrating an example of a fuzzy rule for determining the rate of change in the duty ratio of the control pulse width. Note that when actually setting the membership function, the difference between the maximum operating temperature of the components of the power supply circuit 105 and the operating temperature of the components is determined, and this is taken as the temperature margin.

FIG. 3(a) is a diagram showing the membership function of temperature margin, FIG. 3(b) is a diagram showing the membership function of load current, and FIG. 3(c) is a diagram showing the pulse width duty ratio change rate of PWM control. It is a figure showing the membership function of.

As can be seen from FIG. 3, the sets of temperature margin, load current, and pulse width duty ratio change rate of PWM control each have three fuzzy sets.

For example, three fuzzy sets of temperature margins (
ML, MM, MH), respectively “M
Fuzzy labels of ``L'', ``MM'', and ``MH'' are attached.
w); Fuzzy set representing “small temperature margin”.

MM (Margin Middle);
A fuzzy set that represents “medium temperature margin”.

MH (Margin High): A fuzzy set representing "a large temperature margin."

[0021] The degree of belonging to each set is “0”
In the case of a fuzzy set that takes any value between `` and 1'' and is labeled with the fuzzy label MM shown in FIG. 3(a),
The degree to which the temperature margin belongs to the set of 30°C, that is, the degree of conformity, is “1.0”, and the degree of conformity to the temperature margin of 15°C or 45°C is “0”.

To determine the pulse duty ratio change rate of PWM control, among the fuzzy rules shown in FIG. 2, for example, <Rule 5> and <Rule 6> fuzzy regulations are used. <Rule 5> IF (M=MM AND I
=IM) THEN D=DM <Rule 6> IF(M=MM AND I
=IH) THEN D=DL where M=temperature margin, I=load current, and D=change rate of pulse width duty ratio of PWM control.

Next, the pulse width duty ratio change rate D of PWM control is determined by the above-mentioned <Rule 5><Rule6>
We will explain how to make a decision based on the inference method.

Now, inferring according to <Rule 6>, for the temperature margin . Also, for load current Y,
As shown in FIG. 4A, the load current is included in the set of IH to a degree of μy according to the membership function (I=IH). Then, take the minimum value of the obtained μx and μy, and let the minimum value be the degree to which the condition part of <Rule 6> is satisfied, and the membership of that value and the pulse width duty ratio change rate (DL) of PWM control. Take the MIN operation with the function. The calculation result becomes a trapezoid shown by the hatched part of the set S in FIG. 4(A).

Next, inference is made in the same manner according to <Rule 5>, and the result of this calculation becomes a trapezoid shown by the hatched part of the set T shown in FIG. 4(B).

The inference results for each regulation obtained in this way, that is, the shaded part of set S and the shaded part of set T are combined. The result of this synthesis becomes the shaded part of the set U, as shown at 410 in FIG. Next, the center of gravity (point P) of this set is calculated to determine the rate of change (DP) of the pulse width duty ratio of PWM control. In this example, fuzzy rules, membership functions, control programs, etc. are written in R.
It is stored in the OM 101 and calculated using the RAM 102, but a table storing the manipulated variables corresponding to the input of state quantities is stored in the ROM 101, and the corresponding manipulated variables are output by referring to this table. You can do it like this.

FIG. 5 shows the CPU in the protection device of this embodiment.
100, a control program for executing this process is stored in the ROM 101. First, in step S1, the A/D converters 108, 110
and 112, the temperature information, output voltage, and load current are input. In step S2, among the plurality of fuzzy rules stored in the fuzzy rules 131,
Decide which rules to adopt for reasoning. As a result, the rule to be adopted is determined, and the process proceeds to step S3. In this step S3, for example, as shown in FIG.
The degrees for the data input in step S1 are determined according to the membership function of , and sets (S and T in FIG. 4) corresponding to each rule are determined by MI calculation. In addition,
In FIG. 4, only the temperature margin of the components of the power supply circuit 105 and the load current are used as state quantities, but it goes without saying that inferences may be made by adding output voltage data to these.

Next, the process proceeds to step S4, where the sum of the sets S and T is calculated, and from this the center of gravity P is calculated. Then, the operation amount (in FIG. 4, the rate of change of the duty ratio) corresponding to the center of gravity P is determined. Next, proceed to step S5, and step S
The data to be output to the D/A converter 103 is determined according to the operation amount obtained in step 4, and the output of the power supply circuit 105 is thereby controlled by PWM.

In this embodiment, the state quantity is expressed as the power supply circuit 1.
Although the present invention is not limited to the temperature and load current of the components of the power supply circuit 105, the present invention is not limited thereto; Any state quantity related to the protective operation, such as the rate of change of the load current, can be used as the state quantity in the present invention.

Furthermore, the manipulated variable is not limited to the rate of change of the pulse width duty ratio of PWM control, but may also control on/off of the power supply circuit 105.

Furthermore, it goes without saying that the number of state quantities to be detected is not limited to two, but can be combined in any number.

Note that the above-mentioned fuzzy inference algorithm is just an example, and the algorithm may be modified. For example, instead of taking the center of gravity of the area when composing a plurality of rules, the value on the horizontal axis relative to the value that maximizes the vertical axis may be used as the inference result, or it may be determined by weighted average. In addition, the number and content of fuzzy rules are determined based on experience.
Various modifications are possible.

<Second Embodiment (FIG. 6)> FIG. 6 is a diagram showing fuzzy rules in a second embodiment of the present invention.

In FIG. 6, R indicates the rate of temperature change of the component, and fuzzy labels "RL", "RM", and "RH" are attached to three fuzzy sets, respectively. It is assumed that the fuzzy set of the load current and the rate of change of the duty ratio is the same as in the previous embodiment. The meaning of each of these fuzzy labels is shown below.

RL: A fuzzy set representing "a small rate of temperature change."

RM: A fuzzy set representing "medium rate of temperature change."

RH: A fuzzy set representing "a large rate of temperature change." shall be.

The method for determining the duty ratio change rate of the PWM control pulse width is the same as the method in the first embodiment, so the details will be omitted.

<Third Embodiment (FIG. 7)> FIG. 7 is a diagram showing fuzzy rules in a third embodiment of the present invention.

In FIG. 7, for three fuzzy sets of ambient temperature A, fuzzy labels "AL" and "
It is assumed that the fuzzy sets of the load current and the rate of change of the duty ratio are the same as in the previous embodiment.The meanings of these fuzzy labels are shown below.

AL: A fuzzy set representing "low ambient temperature."

AM: A fuzzy set representing "medium ambient temperature."

AH: Fuzzy set representing "ambient temperature is high". shall be.

The method for determining the duty ratio change rate of the pulse width of PWM control is the same as the method in the first embodiment, so the details will be omitted.

The present invention may be applied to a system made up of a plurality of devices, or to a device made up of one device. It goes without saying that the present invention can also be applied to a case where the present invention is achieved by supplying a program for executing the present invention to a system or device.

As explained above, according to this embodiment, the load current of the power supply circuit, the temperature of the components of the power supply circuit, the operating current of the components, the ambient temperature, and many other ambiguous fluctuation factors that are mutually related to each other can be controlled. In the protection operation of the power supply device that operates according to the (state quantities), the optimum operation amount can be calculated from these plurality of state quantities, and the power supply circuit protection operation can be performed.

In other words, in conventional power supply circuits, the reference value for the protection operation of the power supply is fixed against changes in the environment such as the ambient temperature, the load current of the power supply, the operating temperature of the component parts, etc. , using fuzzy inference as shown in this example,
Accurate protection operation is possible by performing control that takes into account complex factors.

Furthermore, since the manipulated variable is determined based on a plurality of parameters, even if there is an error in some of the input data, it is possible to prevent a large error from occurring in the manipulated variable. .

[0049]

[Effects of the Invention] As explained above, according to the present invention, the protection control of the power supply circuit is determined based on the parameters (state quantities) for determining the protection operation of the power supply circuit, based on the rules related as qualitative rules. This has the effect of accurately protecting the power supply circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a power supply device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing fuzzy rules of the first embodiment of the present invention.

FIG. 3 shows membership functions of temperature margin, load current, and duty change rate in the first embodiment of the present invention.

FIG. 4 Fuzzy rule 5 in the first embodiment of the present invention
FIG. 6 is a diagram for explaining the principle of inferring the rate of change in duty ratio from temperature margin and load current using equations 6 and 6.

FIG. 5 is a flowchart showing the control operation of the CPU in the first embodiment of the present invention.

FIG. 6 is a diagram showing fuzzy rules of a second embodiment of the present invention.

FIG. 7 is a diagram showing fuzzy rules of a third embodiment of the present invention.

[Explanation of symbols]

100 CPU 101 ROM 103 D/A converter 104 Driver 105 Power supply circuit 106 Load 107 Temperature sensor 108-112 A/D converter 109 Output voltage sensor 109 Load current sensor 131 Fuzzy rule storage section

Claims (6)

[Claims] 1. A protection means that protects the power supply circuit by adjusting the output of the power supply circuit according to the operation amount, and a state quantity input that detects or inputs a state quantity of the power supply circuit related to protection of the power supply circuit. a rule means for associating the relationship between the state quantity and the manipulated variable as a qualitative rule; and a rule means for determining the operation based on the degree to which the state quantity belongs to a predetermined set according to the rule output from the rule means. A protection device for a power supply circuit, comprising: inference means for inferring a quantity. 2. A protection means that protects the power supply circuit by adjusting an output of the power supply circuit according to an operation amount, and detecting a state quantity related to at least one of an operating state of the power supply circuit or a load state of the power supply circuit, or A state quantity input means for inputting, a membership function storage means expressing the state quantity and the manipulated quantity as fuzzy sets, and a rule expressing the relationship between the state quantity and the manipulated quantity in the form of a fuzzy proposition. a rule storage means for storing, and a suitability calculation means for calculating the suitability of the state quantity input by the state quantity input means based on the membership function of the state quantity stored in the membership function storage means; calculation means for calculating an inference result according to the rules stored in the rule storage means by a predetermined calculation based on the degree of suitability calculated by the degree of suitability calculation means; Protection of a power supply circuit characterized by comprising: a calculation means for calculating the operation amount based on the operation amount; and a control means for controlling the operation amount output to the protection means based on the operation amount calculated by the calculation means. Device. 3. The state quantity input means detects or inputs at least one value among a load current of a power supply circuit, a temperature of a component of the power supply circuit, and an operating current of the component as a state quantity. The power supply circuit protection device according to claim 1 or 2, characterized in that: 4. The power supply circuit protection device according to claim 1, wherein the manipulated variable is a rate of change in a pulse width duty ratio of PWM control that controls the output of the power supply circuit. 5. The power supply circuit protection device according to claim 1, wherein the manipulated variable is a frequency change rate of PFM control that controls the output of the power supply circuit. 6. Detecting a state quantity related to at least one of the operating state of the power supply circuit or the load state of the power supply circuit,
Alternatively, the process of inputting, the process of calculating the fitness of these input state quantities based on the membership function of the state quantities, and the relationship between the state quantities and the manipulated variables to be output in the form of fuzzy propositions. a step of obtaining an inference result by a predetermined calculation based on the calculated fitness according to the expressed rule; a step of calculating the operation amount based on the inference result of each rule; A method for protecting a power supply circuit, comprising the step of adjusting the output of the power supply circuit accordingly to protect the power supply circuit.