CN101505560B - Feedback type automatic power control system - Google Patents

Abstract

The invention relates to a feedback type automatic power control system, which is suitable for controlling an electronic element, wherein the electronic element comprises two electrodes, and the system comprises a multiplication unit, a control unit and an adjusting unit. The multiplication unit multiplies a working voltage value corresponding to the voltage difference of the electrodes and a feedback voltage value corresponding to the working current of the electronic element to output a measurement voltage value corresponding to the power of the electronic element. The control unit outputs a control voltage corresponding to the difference between the measured voltage and a set voltage. The regulating unit is electrically connected between the electronic element and the control unit and comprises a transistor connected with the electronic element in series, and the working state of the transistor is changed along with the control voltage of the control unit. The invention can accurately obtain the consumed power of the electronic element, and automatically adjust the power supply amount of the electronic element through the control unit and the adjusting unit according to the change of the consumed power, thereby effectively achieving the function of keeping stable luminous power.

Description

Feedback Automatic Power Control System

technical field

The present invention relates to a power control system, in particular to a system that can accurately obtain the power consumption of electronic components, and then automatically adjust the power supply to electronic components through a control unit and an adjustment unit according to changes in power consumption, which can effectively maintain stable luminous power Functional feedback type automatic power control system.

Background technique

Please refer to FIG. 1 , which is a graph illustrating the relationship between the luminous power and the operating current of an LED at different device temperatures. When semiconductor elements such as light-emitting diodes and laser diodes are in operation, the luminous power will decrease as the temperature of the elements rises. Therefore, when light-emitting diodes are used without power control, the luminous power is likely to be unstable.

Please refer to FIG. 2, which is a schematic diagram illustrating the design structure of an existing control circuit in the past. Therefore, the general light-emitting diode 15 will adopt a circuit 10 disclosed in Taiwan Patent Application No. 92107029 "Automatic Power Controller", so as to To achieve the purpose of stabilizing the luminous power, the circuit 10 mainly uses a light detector 14 to detect the luminous power of the light emitting diode 15, and then adjusts the voltage or current provided to the light emitting diode 15 according to the change of the detection signal, This design is used to achieve the purpose of maintaining stable luminous power.

However, due to the poor directivity of the output light of the light emitting diode 15, the distance between the light detector 14 and the light emitting diode 15, the position, the light pollution of the environment, and the sensitivity of the light detector 14 will all have an impact on the detection signal. , so it is easy to have errors in the control of the luminous power. In addition, the detection signals output by the light detector 14 to the light emitting diode 15 with different wavelengths are also different. The light emitting diode 15 and the light detector 14 When matching with different models, the control effect of the luminous power will be affected. Therefore, the above reasons will make it difficult to maintain the luminous power of the light emitting diode 15 stably in the current technology using the photodetector 14, resulting in poor effect.

It can be seen that the above-mentioned existing automatic power control system obviously still has inconvenience and defects in structure and use, and needs to be further improved urgently. In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and the general products do not have a suitable structure to solve the above-mentioned problems. This is obviously the relevant industry. urgent problem to be solved. Therefore, how to create a new type of feedback-type automatic power control system is one of the current important research and development topics, and it has also become a goal that the industry needs to improve.

In view of the above-mentioned defects in the existing automatic power control system, the inventor actively researches and innovates on the basis of years of rich practical experience and professional knowledge engaged in the design and manufacture of such products, and cooperates with the application of academic theory, in order to create a new type of structure The feedback type automatic power control system can improve the general existing automatic power control system and make it more practical. Through continuous research, design, and after repeated trial-making samples and improvements, the present invention with real practical value is finally created.

Contents of the invention

The purpose of the present invention is to overcome the defects existing in the existing automatic power control system, and provide a feedback type automatic power control system with a new structure. The technical problem to be solved is to make it able to Power control is performed directly by electrical signal detection, which is very suitable for practical use.

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. A feedback type automatic power control system according to the present invention is suitable for controlling an electronic component, the electronic component includes two electrodes, wherein the system includes a multiplication unit, a control unit, and an adjustment unit, wherein: the The multiplication unit includes a quadratic input terminal and a multiplication output terminal. One of the multiplication input terminals receives an operating voltage value corresponding to the voltage difference of the electrodes, and the other receives a corresponding voltage value of the electronic component. The feedback voltage value of the working current, the multiplication output terminal is to output a measured voltage value corresponding to the power of the electronic component, the measured voltage value is the working voltage value multiplied by the feedback voltage value; the control unit includes Two control input terminals and a control output terminal, one of the control input terminals is to receive the measured voltage value, the other is to receive a set voltage value, the control output terminal is to output a control voltage, the control The voltage changes corresponding to the difference between the measured voltage value and the set voltage value; and the regulating unit is electrically connected between the electronic component and the control unit, and includes a measuring device connected in series with the electronic component A resistor, a transistor connected in series between the electronic component and the measuring resistor, and a third amplifier, the third amplifier has an inverting input terminal electrically connected to the measuring resistor, a non-inverting input terminal receiving the control voltage An inverting input terminal, and an output terminal electrically connected to the transistor, the working state of the transistor changes with the output voltage of the output terminal.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned feedback type automatic power control system, one of the multiplication input terminals of the multiplication unit is electrically connected to the measurement resistor, and the feedback voltage value is obtained from the voltage at one terminal of the measurement resistor.

The aforementioned feedback type automatic power control system also includes an amplifying unit, the amplifying unit includes a first amplifier and a first adjusting resistor electrically connected to the first amplifier, the operating voltage value is determined by the first amplifier output.

The aforementioned feedback type automatic power control system also includes a voltage divider unit, the voltage divider unit includes four voltage divider resistors, every two voltage divider resistors form a voltage divider module, and the voltages on the electrodes are respectively It is input into the first amplifier through the voltage dividing module.

In the aforementioned feedback type automatic power control system, wherein the control unit further includes a second amplifier and a second adjustment resistor electrically connected to the second amplifier, the control input terminal and the control output terminal are formed on on the second amplifier.

In the aforementioned feedback type automatic power control system, the transistor of the adjustment unit is a field effect transistor, and the output terminal of the third amplifier is electrically connected to a gate of the transistor.

In the aforementioned feedback type automatic power control system, wherein the control unit further includes a second amplifier and a second adjustment resistor electrically connected to the second amplifier, the control input terminal and the control output terminal are formed on on the second amplifier.

In the aforementioned feedback type automatic power control system, the transistor of the adjustment unit is a field effect transistor, and the output terminal of the third amplifier is electrically connected to a gate of the transistor.

Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention has at least the following advantages and beneficial effects: In the present invention, when the multiplication unit of the system is operating, the working voltage value is directly corresponding to the voltage difference of the electrodes, and the feedback voltage value is directly corresponding to the voltage difference of the electrodes. The operating current of the electronic component should be used, so the power consumption of the electronic component can be accurately obtained, and then according to the change of the power consumption, the power supply to the electronic component can be automatically adjusted through the control unit and the adjustment unit, so that the light can be effectively achieved. Power maintenance function.

To sum up, the present invention relates to a feedback type automatic power control system, which is suitable for controlling an electronic component, and the electronic component includes two electrodes. The system includes a multiplication unit, a control unit, and an adjustment unit. The multiplication unit multiplies an operating voltage value corresponding to the voltage difference between the electrodes and a feedback voltage value corresponding to the operating current of the electronic component, so as to output a quantity corresponding to the power of the electronic component Measure the voltage value. The control unit outputs a control voltage, and the control voltage changes corresponding to the difference between the measured voltage value and a set voltage value. The regulating unit is electrically connected between the electronic component and the control unit, and includes a transistor connected in series with the electronic component, and the working state of the transistor changes with the control voltage of the control unit. The present invention does not need light detection, but can directly detect electric signals for power control. The present invention has the above-mentioned many advantages and practical value, and it has great improvement no matter in product structure or function, has remarkable progress in technology, and has produced easy-to-use and practical effect, and compared with existing automatic power control The system has enhanced prominent functions, so it is more suitable for practical use, and it is a novel, progressive and practical new design.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a graph illustrating the relationship between luminous power and operating current of a light emitting diode at different device temperatures.

FIG. 2 is a schematic diagram illustrating the design of a conventional control circuit.

FIG. 3 is a circuit diagram illustrating a preferred embodiment of the feedback type automatic power control system of the present invention.

FIG. 4 , FIG. 5 , and FIG. 6 are graphs respectively illustrating the application of the preferred embodiment of the present invention to a blue light, a green light, and a red light emitting diode.

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation, structure, and features of the feedback-type automatic power control system proposed according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. And its effect, detailed description is as follows.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the drawings. Through the description of the specific implementation mode, when the technical means and functions adopted by the present invention to achieve the predetermined purpose can be obtained a deeper and more specific understanding, but the accompanying drawings are only for reference and description, and are not used to explain the present invention be restricted.

Please refer to FIG. 3 , which is a circuit diagram illustrating a preferred embodiment of the feedback type automatic power control system of the present invention. The feedback type automatic power control system 200 of the preferred embodiment of the present invention is suitable for controlling the electric power used by an electronic component 90. The electronic component 90 includes two electrodes A and K. In this embodiment, the electronic component 90 adopts light emitting Diodes, laser diodes can also be used in practical applications. The system 200 includes a voltage dividing unit 20 , an amplification unit 30 , a multiplication unit 40 , a control unit 50 , and an adjustment unit 60 .

The above-mentioned voltage dividing unit 20 includes four voltage dividing resistors R1, R2, R3, R4, and every two voltage dividing resistors form a voltage dividing module 21, 22, and the voltage on the electrodes A, K is respectively passed through the The above-mentioned voltage dividing modules 21 and 22 are input into the amplifying unit 30 .

The above-mentioned amplifying unit 30 includes a first amplifier 31 and a first adjusting resistor R _G1 electrically connected to the first amplifier 31; the first amplifier 31 has two input terminals and an output terminal, and the input terminals are respectively Electrically connected to the voltage divider modules 21, 22, the output end is to output a working voltage value V _LED corresponding to the voltage difference between the electrodes A, K, the first adjustment resistor R _G1 allows the user to perform this The output gain of the first amplifier 31 is adjusted, and the operating voltage value V _LED will produce a voltage change ΔV _LED when the element temperature changes, so when the element temperature changes, the operating voltage value is expressed as:

V _LED +ΔV _LED

The above multiplication unit 40 includes two multiplication input terminals X1, Y1 and a multiplication output terminal W. One of the multiplication input terminals X1, Y1, X1, is used to receive a voltage difference corresponding to the electrodes A and K. The voltage value V _LED , the other Y1 is to receive a feedback voltage value V _RE corresponding to the change of the operating current of the electronic component 90 , and the multiplication output terminal W is to output a measurement corresponding to the power change of the electronic component 90 Voltage value V _P , when the temperature of the element changes so that the operating voltage V _LED produces a ΔV _LED , the measured voltage value V _P is the operating voltage value V _LED +ΔV _LED multiplied by the feedback voltage value V _RE , which is expressed by the equation for:

V _P ＝V _RE ×(V _LED +ΔV _LED )

The above-mentioned control unit 50 includes a second amplifier 51, two control input terminals formed on the second amplifier 51, a control output terminal formed on the second amplifier 51, and an electrical connection to the second amplifier 51. The second adjustment resistor R _G2 , the second amplifier 51 is an operational amplifier, the control input refers to the non-inverting input and the inverting input of the operational amplifier, the inverting input is to receive the measured voltage value V _P , the non-inverting input end receives a set voltage value V _REF , the control output end outputs a control voltage V _C , and the control voltage V _C corresponds to the measured voltage value V _P and the The difference change of the set voltage value V _REF , the set voltage value V _REF is a fixed value adjustable by the user, and is used to change the difference between the measured voltage value V _P and the set voltage value V _REF , the second adjustment resistor R _G2 is used to allow the user to quickly adjust a gain value G of the second amplifier 51, so as to be applicable to electronic components 90 of different wavelengths, models, and types. The control voltage V _C is expressed by the equation Expressed as:

V _C ＝G×(V _REF -V _P )

The above-mentioned adjustment unit 60 is electrically connected between the electronic component 90 and the control unit 50, and includes a measuring resistor R _E connected in series with the electronic component 90, a measuring resistor R E connected in series with the electronic component 90 and the measuring resistor R A transistor Q between _E , and a third amplifier 61; the third amplifier 61 has an inverting input terminal electrically connected to the measuring resistor _RE , a non-inverting input terminal receiving the control voltage V _C , And an output end electrically connected to the transistor Q, the working state of the transistor Q changes with the output voltage of the output end, in this embodiment, the transistor Q of the adjustment unit 60 is a field effect transistor (FET), the The output terminal of the third amplifier 61 is electrically connected to the gate of the transistor Q (the gate is the gate, hereinafter referred to as the gate), and a multiplication input terminal Y1 of the multiplication unit 40 is electrically connected to the measuring resistor _RE , the feedback voltage value is obtained from the voltage V _RE at one end of the measuring resistor _RE .

Based on the description of the above equations, further calculations show that the open-loop gain of the system 200 is:

GM(0)＝A _V0 × g _m

GM(0) is the admittance of the open-loop system, A _v0 is the open-loop gain of the third amplifier 61 , and g _m is the admittance value of the transistor Q.

Considering the measured resistance R _E again:

$\mathrm{<span\; class="notranslate">\; GMf</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; GM</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; GM</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="V"\; filenames="S2008100063005E00011.png,S2008100063005E00051.png"\; state="\{\{state\}\}">V</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="g\; m"\; filenames="S2008100063005E00011.png,S2008100063005E00031.png"\; state="\{\{state\}\}">g</figure-callout></span><figure-callout\; id="1"\; label="g\; m"\; filenames="S2008100063005E00011.png,S2008100063005E00031.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="V"\; filenames="S2008100063005E00011.png,S2008100063005E00051.png"\; state="\{\{state\}\}">V</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; \&cong;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}$

GM _f is the gain of the closed-loop system. It can be seen that the output current is only related to the measured resistance _RE , and has nothing to do with the transistor Q of the active component. Therefore, the influence of the non-ideal parameters of the transistor Q can be minimized, and finally Obtain the current _ILED flowing through the electronic component 90 as:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; led</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; RE</span>}}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; led</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; led</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span>}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; RE</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; led</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; RE</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; led</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}$

Therefore, the present invention can moderately adjust the corresponding current change _ΔI of the current flowing through the electronic component 90 due to the temperature change of the component by adjusting the set voltage value V _REF and the measuring resistance REF to maintain The purpose of stabilizing the power output of light-emitting diodes. When in use, if the light-emitting diodes are affected by temperature and cause the operating voltage V _LED to decrease, the voltage value received by the multiplication unit 40 will also decrease accordingly, so the measured voltage value output V _P will drop and be input to the inverting input terminal of the second amplifier 51. When the set voltage V _REF is fixed, the difference between the measured voltage V _P and the set voltage V _REF will form the The control voltage V _C will increase, thereby increasing the gate electric field of the transistor Q, so that the current I _LED passing through the light-emitting diode increases, and the increased current I _LED cooperates with the operating voltage V _LED decreased by the temperature, The power of the light-emitting diode can be automatically maintained stable, and the purpose of the present invention can be achieved.

Please refer to Fig. 4, Fig. 5, and Fig. 6, which are graphs illustrating respectively the application of the preferred embodiment of the present invention to a blue light, a green light, and a red light-emitting diode. The invention is applied to light-emitting diodes using three materials of blue light, green light, and red light, and when the gain value G of the second amplifier 51 of the present invention is 2 times, 4 times, and 6 times respectively, as the temperature of the element increases , the variation curve of the controlled luminous power corresponding to the temperature in the present invention. Experiments have proved that the luminous power can be controlled quite stably under the operation of the system 200. In terms of control, it is not necessary to pass through a light detector for detection, so the measurement results are not affected by the poor directivity of the light output by the light-emitting diode and the light detection. The influence of factors such as the distance between the light emitting diode and the light emitting diode, the position, the ambient light pollution, and the sensitivity of the light detector; as long as the light emitting diode uses different light emitting materials to emit light of different wavelengths, the corresponding working voltage V _LED or Moderately adjusting the gain value G or the set voltage value V _REF for different types of LEDs can achieve the purpose of automatically maintaining the stability of the luminous power.

Based on the above descriptions, it can be seen that when the multiplication unit 40 of the system 200 is operating, the operating voltage value V _LED directly corresponds to the voltage difference between the electrodes A and K, and the feedback voltage value V _RE directly corresponds to the electronic component 90 The operating current change I+ΔI, so the power consumption change of the electronic component 90 can be accurately obtained, and then according to the power consumption change, the power supply to the electronic component 90 is automatically adjusted through the control unit 50 and the adjustment unit 60, It can effectively achieve the purpose and effect of automatically maintaining the stability of the luminous power.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solutions of the present invention.

Claims (8)

1. A feedback type automatic power control system, suitable for controlling an electronic component, the electronic component comprises two electrodes, it is characterized in that the system comprises a multiplication unit, a control unit, and a regulation unit, wherein: The multiplication unit includes a quadratic input terminal and a multiplication output terminal. One of the multiplication input terminals receives an operating voltage value corresponding to the voltage difference of the electrodes, and the other receives an operating voltage value corresponding to the electronic component. The feedback voltage value of the operating current, the multiplication output terminal outputs a measured voltage value corresponding to the power of the electronic component, and the measured voltage value is the operating voltage value multiplied by the feedback voltage value; The control unit includes two control input terminals and a control output terminal, one of the control input terminals is to receive the measured voltage value, the other is to receive a set voltage value, and the control output terminal is to output a control voltage, the control voltage changes corresponding to the difference between the measured voltage value and the set voltage value; and The adjustment unit is electrically connected between the electronic component and the control unit, and includes a measuring resistor connected in series with the electronic component, a transistor connected in series between the electronic component and the measuring resistor, and a first Three amplifiers, the third amplifier has an inverting input terminal electrically connected to the measuring resistance, a non-inverting input terminal receiving the control voltage, and an output terminal electrically connected to the transistor, and the working state of the transistor is As the output voltage at this output changes. 2. The feedback type automatic power control system as claimed in claim 1, wherein one of the multiplication input terminals of the multiplication unit is electrically connected to the measuring resistor, and the feedback voltage value is obtained from This measures the voltage across the resistor. 3. The feedback type automatic power control system as claimed in claim 2 , further comprising an amplifying unit, the amplifying unit comprising a first amplifier and a first adjusting resistor electrically connected to the first amplifier, The working voltage value is output by the first amplifier. 4. The feedback type automatic power control system as claimed in claim 3, is characterized in that it also comprises a voltage dividing unit, and this voltage dividing unit comprises four voltage dividing resistors, and every two voltage dividing resistors form a voltage dividing mold group, the voltages on the electrodes are respectively input into the first amplifier through the voltage dividing modules. 5. The feedback type automatic power control system as claimed in claim 4, wherein said control unit further comprises a second amplifier and a second adjustment resistor electrically connected to the second amplifier, said control The input terminal and the control output terminal are formed on the second amplifier. 6. The feedback type automatic power control system as claimed in claim 5, wherein the transistor of the regulating unit is a field effect transistor, and the output terminal of the third amplifier is electrically connected to a gate of the transistor pole. 7. The feedback type automatic power control system as claimed in claim 1, wherein said control unit further comprises a second amplifier and a second adjustment resistor electrically connected to the second amplifier, said control The input terminal and the control output terminal are formed on the second amplifier. 8. The feedback type automatic power control system as claimed in claim 1, wherein the transistor of the regulating unit is a field effect transistor, and the output terminal of the third amplifier is electrically connected to a gate of the transistor pole.

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