JPH05122849A - Power supply system - Google Patents

Abstract

PURPOSE:To easily determine the operating amount of DC power supply system for load bearing control. CONSTITUTION:A CPU 100 calculates the adaptability of detected state amount based on the membership function of state amount stored in a ROM 101 and then determines inference result of each rule stored in a ROM 101 based on thus calculated adaptability thus calculating an operating amount required for fuzzy inference. A D/A converter 103 receives an actual operating amount calculated through fuzzy inference from the CPU 100 and outputs thus received actual operating amount to a driver 104. The driver 104 performs PWM control of a power supply 105 based on fuzzy inference. Consequently, power is fed from the power supply 105 to a load 111.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system for supplying power by parallel operation of power supply devices.

[0002]

2. Description of the Related Art As a load sharing method in a DC power supply system in which a plurality of power supply devices are connected in parallel, an arbitrary sharing method using a so-called drooping type overcurrent protection circuit is conventionally adopted. In this arbitrary sharing system, the respective power supply devices do not interfere with each other and supply power to the load according to their supply capability.

FIG. 7 shows an example of a conventional power supply system, and power supply devices 200, 205, 2 having the same internal configuration.
06 is connected to the load 210 in parallel. For example, when the output current from the power supply 201 in the power supply device 200 exceeds the set value and the voltage drop in the resistor r202 becomes a predetermined value or more, the amplifier 203 detects the voltage and the operation as the overcurrent protection circuit is performed. Started and power 20
It functions to limit the output current to 1.

That is, in each power supply device, when the output current increases and exceeds a preset current value, the overcurrent protection circuit operates to lower the output voltage and limit the current. ing. In other words, each power supply device shares the load by limiting the current.

[0005]

However, in the above-described conventional load sharing method, the load sharing ratio is determined by the output voltage and the set value of the overcurrent protection. Therefore, (1) the load sharing ratio is affected by the change over time. Responsible (2) There is a problem that adjustment is required during use in order to balance the power supplies. When the load sharing becomes unbalanced, the load current of the specific power supply device increases and the reliability of the system decreases. On the other hand, even if an attempt is made to detect and control the load current of each power supply device in order to achieve a balance, if the number of parallel power supply devices is large, the number of detection parameters (state quantities) will be large, and the parameters and operation amount If there is a parameter in which the relationship of [1] becomes ambiguous, there is a problem that it is difficult to formulate the relationship between the parameter and the manipulated variable.

[0006]

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following constitution as one means for solving the above-mentioned problems. That is,
The invention according to claim 1 connects a plurality of power supplies in parallel,
In the power supply system that shares the power supplied to the load by the plurality of power sources, a unit that detects a state quantity based on the load sharing of the power source, a unit that generates an operation amount when the load sharing of the power source is performed, Rule means for relating the relationship between the state quantity and the operation quantity as a qualitative rule, and inference means for inferring the operation quantity based on the degree to which the state quantity belongs to a predetermined set according to the rule by the rule means. With.

The invention according to claim 2 is a power supply system in which a plurality of power supplies are connected in parallel and the power supplied to the load is shared by the plurality of power supplies. Means for detecting a state quantity based on a load state, means for performing a predetermined process on the state quantity to generate a new state quantity, means for generating a manipulated variable for load sharing of a power supply, First storage means for storing a membership function in which each state quantity and operation quantity are expressed by fuzzy sets, and a second storage means for storing a rule in which a new state quantity and operation quantity are expressed in a fuzzy proposition form. Storage means; first calculating means for calculating a degree of conformity, which is a degree of belonging to a predetermined set for the new state quantity, based on the membership function; and second storage means based on the degree of conformity. Remember And a second calculating means for calculating the operation amount based on the rule inference result obtained by the calculating means. The calculating means calculates the operation amount by the second calculating means. Based on the manipulated variable
Shares the power supplied to the load.

[0008]

In the above structure, the operation amount for the load sharing control of the power feeding system is easily determined.

[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 overall configuration of a power supply system (hereinafter referred to as a system) according to an embodiment of the present invention. The system shown in the figure includes n power supply devices, that is, a first power supply device 1, a second power supply device 2, an (n-1) th power supply device, and an nth power supply device. Since all power supply devices perform the same operation, only the first power supply device 1 is shown here for its internal configuration.

The CPU 100 calculates the fitness of the detected state quantity based on the membership function of the state quantity stored in the ROM 101, and performs a predetermined calculation based on the calculated fitness. The inference result of each rule stored in the ROM 101 is obtained, and the operation amount is calculated from the inference result to perform fuzzy inference. Also, the CPU 10
0 is the counter 100 (a) and the timer 100
(B) is built in, and these are used when the rate of change is detected from the detected state quantity, for example, the output voltage of the power supply.

The ROM 101 stores membership functions, fuzzy rules, and other control programs. Further, the RAM 102 is used as a work area (work area) when the CPU 100 performs fuzzy inference. The D / A converter 103 receives an actual operation amount calculated by fuzzy inference from the CPU 100 and outputs it to the driver 104. The driver 104 then powers the power supply 105 based on the fuzzy inference.
M control. As a result, power is supplied from the power source 105 to the load 111.

The sensor 106 detects the output voltage, that is, the output voltage of the power supply 105, as the detection of the state quantity. Also,
The sensor 108 detects a load current, that is, a current flowing into the load 111 as the detection of the state quantity. And A / D
The converters 107 and 109 convert the analog signals from the sensors 106 and 108 into digital signals and input the converted signals to the CPU 100.

The interface 110 is an interface for communication with another power supply device, and takes in data such as load current of the other power supply device by the communication. Also, the load 11
1 is connected to the outputs of the power supplies that are operated in parallel with each other. In the fuzzy control in the system according to the present embodiment, the output voltage of the power supply, the output voltage conversion rate of the power supply,
Power supply load current, power supply load current change rate, power supply temperature,
Among the temperature conversion rates of the power source, for example, (a ') output voltage of the power source (b') load current of the power source (b '') load current of another power source device is used, and as an operation amount, for example, (C) The duty ratio change rate of the PWM control pulse width is used.

When actually setting the membership function, the difference between the set reference voltage and the output voltage of the power source (a ') is taken, and this difference is taken as (a) voltage deviation, and (b) above. ') The difference between the load current of the power source and (b'') the load current of another device is calculated, and this is used as the (b) load factor.
FIG. 2 shows the membership functions of these sets.

FIG. 2A is a membership function of voltage deviation, FIG. 2B is a membership function of load factor, and FIG. 2C is a membership function of pulse width duty ratio change rate of PWM control. Indicates a function. As is apparent from FIG. 2, each set of the voltage deviation, the load factor, and the pulse width duty ratio change rate of the PWM control has three fuzzy sets. For example, fuzzy labels for three fuzzy sets of voltage deviation are "VL" and "V".
"M" and "VH" are added (Fig. 2 (a)), respectively. VL (Voltage Low); Fuzzy set representing "small voltage deviation" VM (Voltage Middle); "Voltage deviation is medium" A fuzzy set representing VH (Voltage High); “A voltage deviation is large”.

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 0V, that is, the matching degree is “1”, and the voltage deviation is −0.5V or the voltage deviation is + 0.5V. The degree is “0.5”. The pulse width of the PWM control uses the fuzzy rules of <Rule 5> and <Rule 6> below to determine the duty ratio change rate. <Rule 5> IF (V = VL AND I = IH) THEN D = DH <Rule 6> IF (V = VM AND I = IH) THEN D = DL where V = voltage deviation, I = load factor, D = It is a pulse width duty ratio change rate of PWM control. Note that all fuzzy rules are shown in FIG.

Next, a method of determining the pulse width duty ratio change rate of PWM control based on the inference method of <Rule 5> and <Rule 6> will be described. First, inferring according to <Rule 6>, the voltage deviation x is included in the VM set at a degree of μx from the membership function of the voltage deviation (FIG. 4A), and the load factor y is the load. It is included in the set of IH to the extent of μy by the membership function of the rate (Fig. 4 (b)). Then, the minimum value of the obtained μx and μy is taken, and the minimum value and the MIN calculation of the membership function of the duty ratio change rate of the pulse width of the PWM control are performed. The calculation result has a trapezoidal shape indicated by a set S (hatched portion) shown in FIG. Similarly, when inferred according to <Rule 5>, the calculation result becomes a trapezoid shown by a set T (hatched portion) shown in FIG. When the result of inference based on the obtained rules, that is, the set S and the set T are combined, FIG.
Is a set U (hatched portion). Then, the center of gravity (point P) of this set is calculated to obtain the pulse width duty ratio change rate of the PWM control.

As described above, according to this embodiment,
Optimal operation amount by fuzzy reasoning for output voltage of power supply, output voltage change rate, load current, load current change rate, mutual comparison result of these, and other ambiguous variable factors (state quantities) related to each other. By calculating, the setting value of the load sharing control is not fixed, and there is an effect that the load sharing of the power source can be performed appropriately. Further, since the operation amount is determined based on a plurality of parameters, there is an effect that even if there is an error in a part of the input data, a large error can be prevented from occurring in the operation amount. Furthermore, since each power supply device controls independently, there is no limit to the number of parallel power supply devices, and the power supply system according to the target load can be easily configured.

In the above embodiment, fuzzy rules, membership functions, control programs, etc. are stored in the ROM,
Although the calculation is performed using the RAM, the operation amount corresponding to the input of the state amount may be calculated in advance, and the control may be performed using the ROM that outputs this value. By doing so, the processing speed can be improved. The state quantity is not limited to the output voltage and load current, but the output voltage change rate,
Any state quantity related to the load sharing operation, such as the load current change rate of the power supply, the temperature of the power supply, the temperature change rate of the power supply, etc., can be used as the state quantity.

Further, the number of state quantities is not limited, and the number of state quantities larger than those shown in the embodiment may be combined. Further, the above-mentioned fuzzy inference algorithm is an example, and it may be modified. For example, when combining 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 the fuzzy rules can be modified based on experience. Further, in the above embodiment, the case of the DC power supply is shown, but it goes without saying that it can be applied to the AC power supply.

<Modification 1> Next, a first modification of the above embodiment will be described. FIG. 5 shows a fuzzy rule in this modification, and R in the figure shows a voltage conversion rate of the output voltage. The fuzzy labels for the three fuzzy sets of this voltage conversion rate are “RL”, “RM”, and “RH”.
, Respectively, and RL; a fuzzy set representing "a small voltage change rate"RM; a fuzzy set representing "a medium voltage change rate"RH; a fuzzy set representing a "large voltage change rate". The method of obtaining the duty ratio change rate of the PWM control pulse width in this modification is the same as the method in the above-mentioned embodiment, and therefore its explanation is omitted.

<Modification 2> FIG. 6 shows a fuzzy rule in the second modification. In this modification, the state quantity related to the device temperature is used, and in FIG. 6, fuzzy labels “AL”, “AM”, and “AH” are attached to the three fuzzy sets of the device temperature. There is. That is, it is assumed that AL is a fuzzy set representing "the device temperature is low" AM: Fuzzy set representing "the device temperature is medium" AH: A fuzzy set representing the "device temperature is high" Here, also, since the method of obtaining the duty ratio change rate of the PWM control pulse width is the same as the method in the above-mentioned embodiment, the description thereof will be omitted.

[0023]

As described above, according to the present invention,
By calculating an optimum operation amount by fuzzy inference from an ambiguous variable factor related to the power source, there is an effect that it is possible to appropriately share the load of power supply in consideration of a complicated variable factor.

[Brief description of drawings]

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

FIG. 2 is a voltage deviation, load factor, and PWM according to an embodiment.
The figure which shows the membership function of the control pulse width duty ratio change rate,

FIG. 3 is a diagram showing all fuzzy rules according to an embodiment;

FIG. 4 is a diagram for explaining a method of determining a pulse width duty ratio change rate of PWM control in the embodiment,

FIG. 5 is a diagram showing a fuzzy rule in Modification 1;

FIG. 6 is a diagram showing a fuzzy rule in Modification 2;

FIG. 7 is a block diagram showing a conventional power supply system.

[Explanation of symbols]

1, 2, n-1, n, 200, 205, 206 Power supply device 100 CPU 101 ROM 102 RAM 111, 210 Load 202 Resistor 203 Amplifier

Claims (5)

[Claims] 1. A power supply system in which a plurality of power supplies are connected in parallel and the power supplied to a load is shared by the plurality of power supplies, and a detection unit that detects a state quantity based on the load distribution of the power supplies, A means for generating an operation amount when performing load sharing, a rule means for relating the relationship between the state quantity and the operation amount as a qualitative rule, and a state set having a predetermined set according to the rule by the rule means. And an inference unit that infers the operation amount based on the degree of belonging to the power supply system. 2. A power supply system in which a plurality of power supplies are connected in parallel and the power supplied to the load is shared by the plurality of power supplies, and the state quantity based on the operating state of the power supply or the load state of the power supply is detected. A detection unit, a unit that performs a predetermined process on the state quantity to generate a new state quantity, a unit that generates an operation quantity when the load of the power source is shared, and a new state quantity and an operation quantity. First storage means for storing membership functions expressed in fuzzy sets, second storage means for storing new state quantities and rules for expressing operation quantities in the form of fuzzy propositions, and new state quantities A first calculation means for calculating a goodness of fit, which is a degree of belonging to a predetermined set, based on the membership function; and an inference result of the rules stored in the second storage means, based on the goodness of fit. And a second calculation means for calculating an operation amount based on the inference result of the rule obtained by the calculation means, and based on the operation amount calculated by the second calculation means. , A power supply system that shares the power supplied to the load. 3. The method according to claim 1, wherein the detection means detects at least one of the output voltage of the power supply, the load current of the power supply, and the temperature of the power supply as the state quantity. Power supply system. 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 system described in. 5. The power supply system 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.