CN102651544B - Over-voltage protection method for field-effect transistor - Google Patents
Over-voltage protection method for field-effect transistor Download PDFInfo
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- CN102651544B CN102651544B CN201210084560.0A CN201210084560A CN102651544B CN 102651544 B CN102651544 B CN 102651544B CN 201210084560 A CN201210084560 A CN 201210084560A CN 102651544 B CN102651544 B CN 102651544B
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Abstract
The invention provides an over-voltage protection method for a field-effect transistor. The method comprises the following steps that: step 1, a rectification module, a high-voltage detection control module and a field-effect transistor are provided, wherein the high-voltage detection control module is electrically connected with the rectification module, the grid electrode of the field-effect transistor is electrically connected with the high-voltage detection control module, the source electrode of the field-effect transistor is electrically connected with the rectification module, and the drain electrode of the field-effect transistor is used for connecting a load primary function circuit; step 2, a power supply of the rectification module is switched on, rectification is performed by virtue of the rectification module so as to obtain a direct current voltage, and the direct current voltage is supplied to the high-voltage detection control module; step 3, the high-voltage detection control module carries out comparative judgment according to the direct current voltage and outputs a control level to the grid electrode of the field-effect transistor; and step 4, the field-effect transistor controls the on or off thereof according to the control level of the grid electrode, so as to control the on or off of the primary function circuit.
Description
Technical field
The present invention relates to a kind of overvoltage protection field, particularly relate to a kind of over-voltage protection method adopting field effect transistor to design.
Background technology
Mostly there is no excess voltage protection in general electric equipment products, as shown in Figure 1, once electrical network occurs abnormal, when voltage fluctuation raises, just have the situation generation that electrical equipment damages.
As shown in Figure 2; in order to address this problem; some product have employed relay J as protection switch; closed or the disconnection in control circuit loop; when testing circuit detects that electrical network abnormal voltage raises; control relay cuts off input power, thus protects the danger of electric equipment products internal circuit damage from electrical network abnormal voltage raises.This relay J power is higher, can increase circuit power consumption to a certain extent, and this will cause energy waste, and can produce spark during relay J contact, and useful life reduces relatively, there is certain potential safety hazard.
Summary of the invention
The object of the present invention is to provide a kind of field effect transistor over-voltage protection method; utilize semiconductor field as the protection switch of excess voltage protection; this field effect transistor is noncontacting switch; there is not mechanical action; no-spark produces, long service life, and fail safe is high; and power needed for driving field effect transistor is low, save the energy.
For achieving the above object, a kind of field effect transistor over-voltage protection method provided by the invention, is characterized in that, comprise the following steps:
Step 1, provide rectification module, high pressure detection control module and field effect transistor, described high pressure detection control module is electrically connected at described rectification module, the grid of described field effect transistor is electrically connected at described high pressure detection control module, the source electrode of described field effect transistor is electrically connected at described rectification module, and the drain electrode of described field effect transistor is for connecting load primary function circuit;
Step 2, connect this rectification module power supply, through described rectification module rectification, obtain direct voltage supply high pressure detection control module;
Step 3, high pressure detection module compare judgement according to this direct voltage, and export control level to the grid of field effect transistor;
Step 4, described field effect transistor control conducting or the shutoff of self according to the control level on grid, thus control opening or turning off of primary function circuit.
In described step 3, this direct voltage of high pressure detection control resume module, and compare with the reference voltage of inside modules circuit configuration, if judge, this voltage is less than setting voltage, the control level that then this high pressure detection control module exports is high level, if judge, this voltage is greater than setting voltage, then the control level that this high pressure detection control module exports is low level.
If when the control level in described step 4 in described fet gate is high level, the complete conducting of field effect transistor, the load primary function circuit conducting of the drain electrode and rectification module that are electrically connected at field effect transistor normally works, if when the control level in described fet gate is low level, field effect transistor turns off completely, and this load primary function circuit quits work.
Described rectification module is bridge rectifier.
Beneficial effect of the present invention: field effect transistor over-voltage protection method provided by the invention; utilize semiconductor field as the protection switch of excess voltage protection; conducting and the shutoff that control level controls field effect transistor is exported by the height of high pressure detection control module detection of grid voltage; thus control the closed of primary function circuit and disconnect; this field effect transistor is noncontacting switch; there is not mechanical action; no-spark produces; long service life; fail safe is high; and power needed for driving field effect transistor is low, save the energy.
In order to further understand feature of the present invention and technology contents, refer to following detailed description for the present invention and accompanying drawing, but accompanying drawing only provides reference and explanation use, is not used for being limited the present invention.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, by the specific embodiment of the present invention describe in detail, will make technical scheme of the present invention and other beneficial effect apparent.
In accompanying drawing,
Fig. 1 is the existing circuit diagram without excess voltage protection;
Fig. 2 is the existing circuit block diagram adding relay protection;
Fig. 3 is the schematic flow sheet of field effect transistor over-voltage protection method of the present invention;
Fig. 4 is the module diagram of field effect transistor over-voltage protection method of the present invention;
Fig. 5 is the circuit diagram of an embodiment of field effect transistor over-voltage protection method of the present invention.
Embodiment
For further setting forth the technological means and effect thereof that the present invention takes, be described in detail below in conjunction with the preferred embodiments of the present invention and accompanying drawing thereof.
Refer to Fig. 3 to 5, the invention provides a kind of field effect transistor over-voltage protection method, it comprises step:
Step 1, provide rectification module 10, high pressure detection control module 20 and field effect transistor Q1, described high pressure detection control module 20 is electrically connected at described rectification module 1, the grid G of described field effect transistor Q1 is electrically connected at described high pressure detection control module 20, the source S of described field effect transistor Q1 is electrically connected at described rectification module 10, and the drain D of described field effect transistor Q1 is for connecting load primary function circuit 30;
In the present embodiment, described high pressure detection control module 20 comprises an a voltage reference chip U1 and voltage-stabiliser tube ZD1, described voltage reference chip U1 input pin R and grounding pin A is electrically connected at rectification module 10, described voltage reference chip U1 output pin K is electrically connected at the grid G of field effect transistor Q1, described voltage-stabiliser tube ZD1 anode is electrically connected at the output pin K of described voltage reference chip U1, and described voltage-stabiliser tube ZD1 negative electrode is electrically connected at the grounding pin A of described voltage reference chip U1.
Described high pressure detection control module 20 also comprises: the first diode D1, second diode D2, first filter capacitor E1, second filter capacitor C1, first resistance R1, second resistance R2, 3rd resistance R3, 4th resistance R4, 5th resistance R5 and the 6th resistance R6, described first diode D1 is electrically connected at rectification module 10 output after connecting with the first filter capacitor E1 forward, described first resistance R1, second resistance R2 and the 3rd resistance R3 is connected to anode and the negative electrode of the first filter capacitor E1 after connecting, the input pin R of described voltage reference chip U1 is electrically connected in the middle of described second resistance R2 and the 3rd resistance R3, described second filter capacitor C1 is electrically connected at input pin R and the grounding pin A of described voltage reference chip U1, described 4th resistance R4 is connected to the negative electrode of the first diode D1 and the grid G of field effect transistor Q1 after connecting with the second diode D2 forward, the output pin K of described voltage reference chip U1 is electrically connected at the anode of described second diode D2, described 5th resistance R5 one end is electrically connected in the middle of the first resistance R1 and the second resistance R2, the other end is electrically connected at the drain D of field effect transistor Q1, described 6th resistance R6 is electrically connected at the grid G of field effect transistor Q1 and the negative electrode of the first filter capacitor E1.
Described rectification module 10 is the bridge rectifier be made up of four diodes, the LM431 that described voltage reference chip U1 adopts National Semiconductor to produce, it obtains the output voltage of 2.5V to 36V by adjusting peripheral resistance, so be not limited thereto, voltage reference chip U1 also can select the chip of the similar functions compatibilities such as TL431, CL431, UTC431, described voltage-stabiliser tube ZD1 reverse breakdown voltage is slightly less than the ceiling voltage of field effect transistor Q1 grid G, is preferably 15V.
Step 2, connect this rectification module 10 power supply, through the rectification of described rectification module 10, obtain direct voltage supply high pressure detection control module 20;
In the present embodiment, the full-wave direct current electricity Vdc that line voltage obtains after rectification module 10 rectification, a more stable direct voltage V1 is formed after the first filter capacitor E1 filtering, this direct voltage V1 mono-aspect provides working power for high pressure detection control module 20, on the other hand as the identification signal of line voltage.
Direct voltage V1 forms a stable voltage V4, for voltage reference chip U1 and field effect transistor Q1 provides operating voltage through the 4th resistance R4, voltage-stabiliser tube ZD1.In circuit, the second filter capacitor C1 is to the further filtering of voltage signal of the input pin R of voltage reference chip U1, improves the precision that high pressure detection control module 20 detects voltage.
Step 3, high pressure detection module 20 compare judgement according to this direct voltage, and export control level to the grid G of field effect transistor Q1;
Described high pressure detection control module 20 processes this direct voltage V1 and obtains comparative voltage, the setting voltage of this comparative voltage and this voltage reference chip compares by voltage reference chip U1, if comparative voltage is less than setting voltage, the control level that then this voltage reference chip U1 output pin K exports is high level, if comparative voltage is greater than setting voltage, then the control level that this voltage reference chip U1 output pin K exports is low level.
In the present embodiment, direct voltage V1 is after resistance R1, R2, R3 connect dividing potential drop, coating-forming voltage V2 and voltage V3, voltage V3 delivers to the input pin R of voltage reference chip U1, for voltage reference chip U1 provides comparative voltage, the setting voltage of this comparative voltage and this voltage reference chip U1 is made comparisons by this voltage reference chip U1.The setting voltage of described voltage reference chip U1 is 2.5V.
Step 4, described field effect transistor Q1 control conducting or the shutoff of self according to the control level in grid G, thus control opening or turning off of primary function circuit 30.
If when the control level in described field effect transistor Q1 grid G is high level, the complete conducting of field effect transistor Q1, load primary function circuit 3 conducting of the drain D and rectification module 1 that are electrically connected at field effect transistor Q1 normally works, if when the control level in described field effect transistor Q1 grid G is low level, field effect transistor Q1 turns off completely, and this load primary function circuit 30 quits work.
If the control level that voltage reference chip U1 exports is high level, this control level is after the voltage stabilizing of voltage-stabiliser tube ZD1, this control level is sent to the grid G of field effect transistor Q1, control the complete conducting of field effect transistor Q1, load primary function circuit 30 conducting of the drain D and rectification module 10 that are electrically connected at field effect transistor Q1 normally works, if the control level that voltage reference chip U1 exports is low level, this control level is sent to the grid G of field effect transistor Q1, control field effect transistor Q1 to turn off completely, this load primary function circuit 30 quits work.
In the present embodiment, when line voltage is normal, by adjusting the first resistance, second resistance and the 3rd resistance R1, the resistance of R2 and R3 can obtain voltage V3 and be less than 2.5V, that is to say that the voltage at the input pin R place of voltage reference chip U1 is less than 2.5V, the control level that now the output pin K of voltage reference chip U1 exports is high level, add voltage-stabiliser tube ZD1 restriction effect, above-mentioned voltage V4 is 15V, now the grid G voltage Vg of field effect transistor Q1 is about 14.3V (voltage V4 deducts the pipe pressure (about 0.7V) of the second diode D2, obtain 14.3V), so now field effect transistor Q1 is in complete conducting state, load primary function circuit 30 can normally work.
When electrical network abnormal voltage exceedes normal value, relevant voltage voltage V3 can be greater than 2.5V, that is to say that the voltage of the input pin R of voltage reference chip U1 is greater than 2.5V, the control level that the output pin K of voltage reference chip U1 exports is low level, now above-mentioned voltage V4 is 2.5V (minimum output voltage of voltage reference chip U1), now the grid G voltage Vg of field effect transistor Q1 is about 1.8V (voltage V4 deducts the pipe pressure (0.7V) of the second diode D2, obtain 1.8V), so now field effect transistor Q1 is in complete off state, load primary function circuit 30 and electrical network disconnect completely, not by the impact of electrical network abnormally high-voltage, thus achieve the object of protection load primary function circuit 30.
In addition, described 5th resistance R5 plays feedback return difference control action.When voltage V3 is raised to 2.5V, field effect transistor Q1 turns off, and voltage V5 becomes high voltage Vdc, and this high voltage Vdc makes voltage V2 and voltage V3 correspondingly raise further through the 5th resistance R5 positive feedback again, guarantees that voltage V3 is more than 2.5V, the reliable conducting of field effect transistor Q1.Otherwise when voltage V3 drops to 2.5V, field effect transistor Q1 conducting voltage V5 becomes low-voltage, this low-voltage makes voltage V2 and voltage V3 reduce further accordingly through the 5th resistance R5 positive feedback again, and guarantee that voltage V3 is lower than 2.5V, field effect transistor Q1 is reliable turn-off then.
In sum; field effect transistor over-voltage protection method provided by the invention; utilize semiconductor field as the protection switch of excess voltage protection; conducting and the shutoff that control level controls field effect transistor is exported by the height of high pressure detection control module detection of grid voltage; thus control the closed of primary function circuit and disconnect; this field effect transistor is noncontacting switch; there is not mechanical action; no-spark produces; long service life; fail safe is high, and drives the power needed for field effect transistor low, saves the energy.
The above, for the person of ordinary skill of the art, can make other various corresponding change and distortion according to technical scheme of the present invention and technical conceive, and all these change and be out of shape the protection range that all should belong to the claims in the present invention.
Claims (2)
1. a field effect transistor over-voltage protection method, is characterized in that, comprises the following steps:
Step 1, provide rectification module, high pressure detection control module and field effect transistor, described rectification module is bridge rectifier; Described high pressure detection control module is electrically connected at described rectification module, the grid of described field effect transistor is electrically connected at described high pressure detection control module, the source electrode of described field effect transistor is electrically connected at described rectification module, and the drain electrode of described field effect transistor is for connecting load primary function circuit;
Step 2, connect this rectification module power supply, through described rectification module rectification, obtain direct voltage supply high pressure detection control module;
Step 3, high pressure detection module compare judgement according to this direct voltage, and export control level to the grid of field effect transistor;
Step 4, described field effect transistor control conducting or the shutoff of self according to the control level on grid, thus control opening or turning off of primary function circuit;
In described step 3, this direct voltage of high pressure detection control resume module, and compare with the reference voltage of inside modules circuit configuration, if judge, this voltage is less than setting voltage, the control level that then this high pressure detection control module exports is high level, if judge, this voltage is greater than setting voltage, then the control level that this high pressure detection control module exports is low level;
Wherein, the detection control of high pressure described in step 1 module, comprise: a voltage reference chip (U1) and a voltage-stabiliser tube (ZD1), described voltage reference chip (U1) input pin (R) and grounding pin (A) are electrically connected at rectification module, described voltage reference chip (U1) output pin (K) is electrically connected at the grid of field effect transistor (Q1), described voltage-stabiliser tube (ZD1) anode is electrically connected at the output pin (K) of described voltage reference chip (U1), described voltage-stabiliser tube (ZD1) negative electrode is electrically connected at the grounding pin (A) of described voltage reference chip (U1), also comprise: the first diode (D1), second diode (D2), first filter capacitor (E1), second filter capacitor (C1), first resistance (R1), second resistance (R2), 3rd resistance (R3), 4th resistance (R4), 5th resistance (R5) and the 6th resistance (R6), described first diode (D1) is electrically connected at the output of rectification module after connecting with the first filter capacitor (E1) forward, described first resistance (R1), second resistance (R2) and the 3rd resistance (R3) are connected to anode and the negative electrode of the first filter capacitor (E1) after connecting, the input pin (R) of described voltage reference chip (U1) is electrically connected in the middle of described second resistance (R2) and the 3rd resistance (R3), described second filter capacitor (C1) is electrically connected at input pin (R) and the grounding pin (A) of described voltage reference chip (U1), described 4th resistance (R4) is connected to the negative electrode of the first diode (D1) and the grid of field effect transistor after connecting with the second diode (D2) forward, the output pin (K) of described voltage reference chip (U1) is electrically connected at the anode of described second diode (D2), it is middle with the second resistance (R2) that described 5th resistance (R5) one end is electrically connected at the first resistance (R1), the other end is electrically connected at the drain electrode of field effect transistor, described 6th resistance (R6) is electrically connected at the grid of field effect transistor and the negative electrode of the first filter capacitor (E1).
2. field effect transistor over-voltage protection method as claimed in claim 1; it is characterized in that; if when the control level in described step 4 in described fet gate is high level; the complete conducting of field effect transistor; the load primary function circuit conducting of the drain electrode and rectification module that are electrically connected at field effect transistor normally works; if when the control level in described fet gate is low level, field effect transistor turns off completely, this load primary function circuit quits work.
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| CN201210084560.0A CN102651544B (en) | 2012-03-27 | 2012-03-27 | Over-voltage protection method for field-effect transistor |
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| CN201210084560.0A CN102651544B (en) | 2012-03-27 | 2012-03-27 | Over-voltage protection method for field-effect transistor |
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| CN102651544B true CN102651544B (en) | 2015-04-15 |
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| CN110165630A (en) * | 2019-05-05 | 2019-08-23 | 广东美的制冷设备有限公司 | Air conditioner over-voltage detection circuit, air conditioner electric control gear and air conditioner |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1592019A (en) * | 2003-08-30 | 2005-03-09 | 华为技术有限公司 | Power supply overvoltage protecting method and power circuit thereof |
| CN201674212U (en) * | 2010-04-30 | 2010-12-15 | 深圳市博源电子有限公司 | Overvoltage protection circuit of a switch power supply and its corresponding switch power supply |
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| CN202084901U (en) * | 2011-06-03 | 2011-12-21 | 石家庄开发区天远科技有限公司 | Vehicle-mounted high-voltage turn-off circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1592019A (en) * | 2003-08-30 | 2005-03-09 | 华为技术有限公司 | Power supply overvoltage protecting method and power circuit thereof |
| CN201674212U (en) * | 2010-04-30 | 2010-12-15 | 深圳市博源电子有限公司 | Overvoltage protection circuit of a switch power supply and its corresponding switch power supply |
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