JPH05122848A - Power supply - Google Patents

Abstract

PURPOSE:To enhance response of the entire control system for power supply by increasing the calculation speed of fuzzy control. CONSTITUTION:A CPU 100 comprises means for calculating the adaptability of detected state amount based on the membership functions 102, 103 of state amount stored in an SRAM 120, means for determining the inference result of each rule in fuzzy rules 101 stored in the SRAM 120 through predetermined operation, means for calculating an operating amount based on thus determined inference result of each rule, and means for rewriting and deciding a rule means (or inference means). The fuzzy rules 101 and the membership functions 102, 103 stored in the SRAM 120 while having a function as rewrite executing means for the rule means (or inference means) are rewritten by means of the CPU 100 according to a state amount or an operating amount. A driver 106 drives a power supply 107 according to an actual operating amount calculated through fuzzy inference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device used in, for example, a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, voltage control in a power supply device has been
Pulse width control (PWM control) using an operational amplifier or the like is used. In this control, the gain of the entire control unit is
It is mainly determined by the gain of the operational amplifier peripheral circuit, and this gain determines the rising / falling characteristics of the power supply and the characteristics at steady time (for example, at constant voltage). However,
When the gain of the operational amplifier is low, a voltage overshoot occurs when the power supply rises or falls, and thus the rise / fall time of the voltage is delayed. In addition, when the load of the power supply, for example, the motor changes over time, and the load fluctuates due to it, or its torque fluctuates due to the temperature rise of the motor, the power supply rises and falls depending on this fluctuation. The characteristics change or the optimum voltage that the power supply should change.

That is, when the number of parameters (state quantities) that determine the rising / falling characteristics, the optimum voltage, etc. is large, or when there is a parameter whose relationship with the control quantity is ambiguous, Since it is difficult to formulate the relationship between the parameters and the controlled variable, the conventional power supply device adopts the method of controlling the rising / falling characteristics of the voltage and the steady-state characteristics using fuzzy inference control. is doing.

[0004]

However, in the power supply control by the fuzzy control in the above-described conventional power supply device, once the membership function and the fuzzy rule are set, they cannot be changed. There are the following problems. For example, in order to prepare for the case where the load of the power supply, the torque of the motor fluctuates with time, or the torque fluctuates due to the temperature rise of the motor, the load current of the power supply, the rate of change of the load current of the power supply, The load condition of the power supply is detected as the state quantity. However, even if they try to control continuously after they have fluctuated, the load current of the power supply, the rate of change of the load current of the power supply, the load status of the power supply, etc. are always detected as state quantities. I have to continue.

As described above, since the membership function and the fuzzy rule cannot be changed, the calculation for obtaining the manipulated variable must be performed every time these state quantities are fetched as data. There is a problem that the calculation speed by fuzzy control cannot keep up with the speed required for the entire control type. That is, if it takes time to calculate the degree of conformance and the operation amount, there is a problem that the response speed required for the entire system cannot be obtained.

[0006]

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,
The invention according to claim 1 is a qualitative relation between a detection means for detecting a state quantity related to power supply control, a means for generating an operation quantity at the time of power supply control, and a relationship between the state quantity and the operation quantity. Rule means for associating with each other as a rule, and an inference means for inferring the operation amount based on the degree to which the state quantity belongs to a predetermined set according to the rule by the rule means, the state quantity or the inference means The rule in the rule means or the inference in the inference means is rewritten according to the operation amount inferred by.

According to a second aspect of the present invention, a detection means for detecting a state quantity relating to at least one of a power supply control state and a power supply load state, and a predetermined process for the state quantity, Means for generating a new state quantity, first storage means for storing a membership function in which the new state quantity and the operation quantity are expressed in the form of fuzzy sets, respectively.
Means for rewriting the membership function in accordance with the new state quantity and operation quantity; second storage means for storing rules expressing the new state quantity and operation quantity in the form of fuzzy rules; Means for rewriting the rule according to a state quantity and an operation quantity; and first calculating means for calculating a goodness of fit, which is a degree of belonging to a predetermined set for a new state quantity, based on the membership function. A calculating means for obtaining the inference result of the rule stored in the second storage means based on the matching degree; and a second operation amount for calculating the operation amount based on the inference result of the rule obtained by the calculating means.
And a power supply control based on the operation amount calculated by the second calculation means.

[0008]

In the above structure, the calculation speed of fuzzy control is increased, and the response speed of the entire power supply control system is increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a power supply device according to an embodiment of the present invention. In the figure, the CPU 100 includes a fitness calculation means, a calculation means,
The fuzzy chip has a function as a calculation unit, a rewriting determination unit of the rule unit (or inference unit), and a rewriting execution unit of the rule unit (or inference unit).
The function as the matching degree calculating means is to calculate the matching degree of the detected state quantity based on the membership functions 102 and 103 of the state quantity stored in the SRAM 120, and the function as the calculating means is to calculate. The reason is that the inference result of each rule in the fuzzy rule 101 stored in the SRAM 120 is obtained by a predetermined calculation based on the determined matching degree. Further, the function as the calculation means is to calculate the operation amount based on the inference result of each rule obtained.

Further, the CPU 100 has the antecedent part membership function 102 (or the consequent part membership function 103 or the fuzzy rule 10) in the SRAM 120.
1) is rewritten according to the state quantity or the operation quantity obtained via the A / D converters 109 and 112. Then, the counter 100a and the timer 100b are respectively used when obtaining the rate of change of the output voltage of the power supply from the detected state quantity, for example, the output voltage of the power supply. SRAM1
Fuzzy rules (fuzzy proposition) 101 stored in 20
Is rewritten by the CPU 100 according to the state quantity or the operation quantity, as described above. Also, the antecedent part membership function 102 and the consequent part membership function 10
Similar to the fuzzy rule 101, the value 3 is rewritten by the CPU 100 according to the state quantity or the operation quantity.

Interface for output signal transfer (I /
O) 105 receives the signal from the CPU 100 from the driver 10
Output to 6. The driver 106 drives the power supply 107 according to the actual manipulated variable calculated by fuzzy inference. If PWM control is used for this power supply control,
The manipulated variable is, for example, the duty ratio of the pulse. Then, the power supply 107 is controlled based on fuzzy inference, and outputs a predetermined voltage to the load 110 by a signal from the driver 106. Here, the load is, for example, a motor.

The output voltage detector 108, which functions as a state quantity detector, detects the output voltage of the power supply 107. Similarly, the load current detection unit 11 that functions as state quantity detection means
In No. 1, the current value flowing through the load 110 is detected, and the load state such as the rotation speed of the motor (not shown) is detected. Then, the A / D converters 109 and 112 convert the analog signals from the output voltage detection unit 108 and the load current detection unit 111 into digital signals, and transmit them to the CPU 100.

Next, fuzzy control in the power supply device according to this embodiment will be described. [Explanation of operation before rewriting membership function] First,
The operation before rewriting the membership function will be described. Here, for example, (a ') the output voltage of the power supply, (b) the change rate of the output voltage of the power supply is used as the state quantity of the fuzzy control, and (c) the duty ratio of the pulse width of the PWM control is used as the operation quantity. To use. Figures 4 and 5 show the membership functions of those sets. When actually setting the membership function, the difference between the control target voltage and the output voltage of the power source (a ′) is calculated and used as the voltage deviation (a).

FIG. 4A is a membership function of the voltage deviation, FIG. 4B is a membership function of the voltage change rate, and FIG. 4C is a voltage control amount, that is, a pulse width of the PWM control. The membership function of the duty ratio is shown.
As is clear from FIG. 4, the set of the voltage deviation, the voltage change rate, and the duty ratio of the pulse width of the PWM control is
Each has 3 fuzzy sets. For example, fuzzy labels “VL”, “VM”, and “VH” are attached to three fuzzy sets of voltage deviations, and each represents VL (Voltage Low); “voltage deviation is small”. Fuzzy set VM (Voltage Middle); fuzzy set representing “medium voltage deviation” VH (Voltage High); fuzzy set representing “large voltage deviation”.

The degree of belonging to each set takes an arbitrary value between "0" and "1", for example, as shown in FIG.
In the case of the fuzzy set with the fuzzy label VM shown in, the degree of belonging to the set of voltage deviation 2V, that is, the degree of conformity is “1.0”, and the voltage deviation is 1.5V or 2.5.
The suitability of V is “0.5”. Incidentally, FIG. 4 shows a membership function before executing the control according to the present embodiment,
FIG. 5 shows the membership function after execution.

The fuzzy rule shown in FIG. 2 is used to determine the voltage control amount, that is, the pulse width duty ratio of the PWM control. For example, the fuzzy rules of <Rule 5> and <Rule 6> are used. <Rule 5> IF (V = VM AND R = RM) THEN D = DM <Rule 6> IF (V = VM AND R = RH) THEN D = DL where V = voltage deviation, R = voltage change rate, D = Duty ratio of PWM control pulse width.

The duty ratio of the pulse width of the PWM control is determined based on the inference method as follows. For example, voltage deviation, voltage change rate, and PWM
A case where the membership function of the control pulse width duty ratio is given as shown in FIGS. 4A, 4B, and 4C will be described. As shown in FIG. 7, when the voltage deviation x and the voltage change rate y are input, VL is applied to x.
And VM and y correspond to RM and RH.
Among the fuzzy rules shown in <Rule 5> and <Rule 6>
Reasoning based on.

First, when inferring according to <Rule 6>,
The voltage deviation x is included in the VM set at a degree of μx _{0 according to} the membership function of the voltage deviation (FIG. 7A).
For the voltage change rate y, it is included in the set of RH with the degree of μy ₀ by the membership function of the voltage change rate (see FIG. 7B). Then, the minimum value of the obtained μx ₀ and μy ₀ is taken, and the minimum value is taken as the degree to which the condition part of <rule 6> is satisfied, and the MI of the value and the membership function of the pulse width duty ratio of the PWM control is set.
N calculation is performed. The calculation result is the set S in FIG.
It becomes a trapezoid indicated by ₀ (hatched portion).

Similarly, when inferred according to <Rule 5>, the calculation result is the set T ₀ (hatched portion) shown in FIG. 7 (f). Then, when the inference results of the obtained respective rules, that is, the set S ₀ and the set T ₀ are combined, the combined result is
It becomes the set V ₀ (hatched portion) shown in FIG. Therefore,
The center of gravity (point P ₀ ) of the obtained set V ₀ is calculated, and the PWM
Find the control pulse width duty ratio. [Description of Membership Function Rewriting Operation] Next, the membership function rewriting operation will be described.

Here, first, the load state of the power source is directly detected. For example, the number of rotations of the motor is detected, and it is determined whether the membership function or fuzzy rule is rewritten based on the obtained data. Specifically, S shown in FIG.
The motor rotation speed 104 in the RAM 120 holds the rotation speed of the motor previously calculated, and when the difference between the rotation speed of the motor and the newly acquired data of the motor rotation speed exceeds a certain value, the voltage is changed. The VM of the membership function of deviation is set by shifting a predetermined value. The CPU 100 determines the rewriting and executes the rewriting. The situation is shown in FIG. The dotted line part in the figure is the membership function before the change.

Therefore, the process of obtaining the manipulated variable by the membership function shown in FIGS. 5 (a), 5 (b) and 5 (c) will be described.
This will be described with reference to FIG. The rules applied in FIG. 8 are <Rule 3> and <Rule 5>. The method of obtaining the sets S ₁ and T ₁ by inputting the voltage deviation x and the voltage change rate y is the same as the operation before rewriting the membership function shown in FIG. 7, but as described above, in <Rule 5>. Since the VM has changed, the conformity of D = DM increases. Therefore, the area of the set T ₁ is larger than that of the set T ₀ described above (see FIG. 8F), and thus the sets S ₁ and T _{1 are}
The area of V ₁ which is the composition of V becomes larger than V ₀ (FIG. 8).
(See (g)). Finally, the position of the center of gravity P ₁ is shown in FIG.
As shown in, it shifts to the upper right from P ₀ . Since the operation amount also increases, the pulse width duty ratio of the PWM control can be changed as a result.

As described above, the membership function of the parameter of the antecedent part of the fuzzy rule (or the membership function of the parameter of the consequent part, the fuzzy rule itself)
The calculation for rewriting is performed when the control system of the power supply is not operating. This is the load current of the power supply,
The rate of change of the load current of the power supply, the state of the load of the power supply (for example,
This is because the parameters for detecting changes over time, such as the number of revolutions of the motor, do not change rapidly and the rate of change is sufficiently small, so there is no need to perform calculations each time they are detected. It is performed at regular intervals.

As described above, according to this embodiment,
When controlling the power supply using fuzzy control, the voltage deviation detected as the state quantity and the load status of the power supply are not treated as one parameter of the antecedent part of the fuzzy rule, but other antecedent parts. By treating the membership function of the parameter as a parameter for rewriting, the number of parameters in the antecedent part of the fuzzy rule can be substantially reduced, the calculation time by the fuzzy rule can be shortened, and the response speed of the power supply system as a system can be improved. There is an effect that it can be improved.

That is, such a method of increasing the calculation speed of fuzzy control can be applied to a system requiring a high response speed for the entire power supply control system. Even if a general microprocessor is used to perform fuzzy control calculations such as the calculation of the center of gravity without using a fuzzy chip as the CPU that controls the control, by reducing the number of parameters in the antecedent part, the entire calculation is performed. The time can be greatly reduced. On the other hand, even when the fuzzy chip is used, a large proportion of the chip area is involved in the calculation of the center of gravity, and if the center of gravity calculation is simplified, the entire chip area of the fuzzy chip can be made very small. ..

In the above embodiment, the voltage deviation or the voltage change rate is used as the state quantity, but the state quantity is not limited to these, and any state quantity related to power supply control can be used as the state quantity. Therefore, it goes without saying that the output voltage detection unit 108 in FIG. 1 may be a room temperature sensor, a humidity sensor, or another sensor depending on the state quantity handled. Further, the operation amount is not limited to the pulse width duty ratio of the PWM control, and may be the change rate thereof. Furthermore, the number of state quantities is not limited to two, and a larger number may be combined. Further, the fuzzy inference algorithm described above is an example, and modifications of the algorithm may be used. 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.

<Modification 1> A modification of the present embodiment will be described. Although the membership function of the antecedent part is changed in the above embodiment, the membership function of the consequent part is changed in this modification. That is, in the membership function shown in FIG. 6, the membership function is changed as shown in FIG. The dotted line portion in FIG. 6C is the membership function before the change. FIG. 9 shows FIG. 6 (a), (b),
A process of obtaining an operation amount by the membership function shown in (c) will be shown. The method for obtaining this manipulated variable is the same as in the above-described embodiment (shown in FIGS. 7 and 8), but in this modification, the area of the set T ₂ was obtained in the above-mentioned embodiment. It becomes larger than the set T ₀ , and finally the center of gravity P ₂ becomes P _0.
Since it shifts to the upper right, the amount of operation can be changed.

<Modification 2> Next, a case where the fuzzy rule itself is changed will be described. FIG. 3 shows a fuzzy rule according to the present modification, and when compared with the fuzzy rule (FIG. 2) in the above embodiment, V = VL, R = RM.
, DL → DM, V = VM, R = RM, DM → DH
Further, V = VM and R = RH are changed from DL to DM. In this modified example, the membership function is not changed and is the same as the above-described embodiment (see FIG. 4).

FIG. 10 shows a process of obtaining the manipulated variable according to the fuzzy rule shown in FIG. In addition, the method of obtaining this operation amount is as follows in the above-mentioned embodiment shown in FIGS. 7, 8 and 9.
And the same as the first modification, but with respect to x, VL and V
RM and RH correspond to M and y. Since three combinations DL, DM, and DH correspond to these combinations, here, in the fuzzy rule shown in FIG.
Inference is performed based on Rule 3>, <Rule 5>, and <Rule 6>.

The goodness of fit obtained in this modification is shown in FIG.
The hatched portions S ₃ , T ₃ and U ₃ shown in (c), (f) and (i)
Becomes Then, when these sets are combined, FIG.
(J) becomes V ₃ (hatched portion), the center of gravity P _{3 of} this set is calculated, and the pulse width duty ratio of PWM control is obtained. Note that the P _3, since shifted to the right than P ₀ determined in the above embodiments, it is possible to change the result, the operation amount.

[0030]

As described above, according to the present invention,
By rewriting the membership function according to the state quantity and the operation amount related to the control of the power supply, the number of parameters of the fuzzy rule is substantially reduced, and the calculation time required to finally obtain the operation amount is significantly increased. There is an effect that it is possible to reduce the power consumption and realize a power supply control system having a high response speed.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a fuzzy rule according to an embodiment,

FIG. 3 is a diagram showing a fuzzy rule according to Modification 2;

FIG. 4 is a diagram showing a membership function before rewriting,

FIG. 5 is a diagram showing a membership function after execution of rewriting,

FIG. 6 is a diagram showing a membership function according to Modification 1;

FIG. 7 is a diagram for explaining a process of obtaining an operation amount before rewriting the membership function according to the embodiment;

FIG. 8 is a diagram for explaining a process of obtaining an operation amount after rewriting the membership function according to the embodiment;

FIG. 9 is a diagram showing a process of obtaining a manipulated variable in Modification 1;

FIG. 10 is a diagram showing a process of obtaining a manipulated variable in Modification 2.

[Explanation of symbols]

 100 CPU 108 Output voltage detection unit 109, 112 A / D converter 111 Load current detection unit 120 SRAM

Claims (5)

[Claims] 1. A detection means for detecting a state quantity related to power supply control, a means for generating an operation quantity at the time of power supply control, and a relationship between the state quantity and the operation quantity as a qualitative rule. And a reasoning unit that infers the operation amount based on the degree to which the state quantity belongs to a predetermined set according to the rule by the rule means. A power supply device characterized in that the rule by the rule means or the inference by the inference means is rewritten according to the operation amount. 2. A detection means for detecting a state quantity relating to at least one of a power supply control state and a power supply load state, and means for performing a predetermined process on the state quantity to generate a new state quantity. A first storage unit that stores a membership function that represents the new state quantity and the operation quantity in the form of a fuzzy set, and the membership function according to the new state quantity and the operation quantity. Means for rewriting, the second storage means for storing a rule expressing the new state quantity and the operation quantity in the form of fuzzy rules, respectively, and the rule according to the new state quantity and the operation quantity. And a first calculating means for calculating a goodness of fit, which is a degree of belonging to a predetermined set for the new state quantity, based on the membership function; Based on the inference result of the rule stored in the second storage means, the second calculating means for calculating the operation amount based on the inference result of the rule obtained by the calculating means. A power supply device, comprising: power supply control based on an operation amount calculated by the second calculation means. 3. The detection means, as the state quantity, the input voltage of the power supply, the change rate of the input voltage of the power supply, the output voltage of the power supply, the change rate of the output voltage of the power supply, room temperature, humidity, the load current of the power supply, the power supply The power supply device according to claim 1, wherein at least one of a rate of change of the load current and a load state of the power supply is detected. 4. The operation amount is a duty ratio of a pulse in pulse width modulation control, or a rate of change of the duty ratio, or claim 2.
The power supply device according to. 5. The power supply device according to claim 1, wherein the manipulated variable is a frequency in the pulse frequency modulation control or a rate of change of the frequency.