CN110940848A - Middle-low voltage large current MOSFET pulse current overcurrent detection circuit - Google Patents
Middle-low voltage large current MOSFET pulse current overcurrent detection circuit Download PDFInfo
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- CN110940848A CN110940848A CN201911297342.3A CN201911297342A CN110940848A CN 110940848 A CN110940848 A CN 110940848A CN 201911297342 A CN201911297342 A CN 201911297342A CN 110940848 A CN110940848 A CN 110940848A
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- 239000003990 capacitor Substances 0.000 claims description 10
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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Abstract
The invention belongs to the technical field of switching power supply and motor control, and particularly relates to a low-medium voltage high-current MOSFET pulse current overcurrent detection circuit, which comprises a drive circuit; the MOSFET detection circuit is connected with the output end of the driving circuit; the input end of the comparison circuit is connected with the MOSFET detection circuit; the comparator detects the conduction voltage drop and the reference level of the MOSFET detection circuit. The invention can detect whether the conduction voltage drop of the MOSFET passing through the pulse current exceeds a safety value or not, thereby determining whether the MOSFET is over-current or not and whether the protection circuit needs to start and shut off the MOSFET or not.
Description
Technical Field
The invention belongs to the technical field of switching power supplies and motor control, and particularly relates to a low-medium voltage high-current MOSFET pulse current overcurrent detection circuit.
Background
When the pulse current of the MOSFET operation is large, for example, several tens of amperes to several hundreds of amperes, the conventional series resistor has a very large detection loss when detecting whether the pulse current passing through the MOSFET is overcurrent.
In order to solve the problems, the invention provides a medium-low voltage high-current MOSFET pulse current overcurrent detection circuit.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
The invention also aims to provide a medium-low voltage high-current MOSFET pulse current overcurrent detection circuit to overcome the problem of high detection loss of the traditional general series circuit.
To achieve these objects and other advantages in accordance with the purpose of the invention, the present invention provides a middle and low voltage large current MOSFET pulse current overcurrent detection circuit, comprising:
a drive circuit;
the MOSFET detection circuit is connected with the output end of the driving circuit;
the input end of the comparison circuit is connected with the MOSFET detection circuit;
the comparator detects the conduction voltage drop and the reference level of the MOSFET detection circuit.
Preferably, the MOSFET detection circuit includes a first MOSFET and a second MOSFET, a gate of the first MOSFET is connected to the output terminal of the driving circuit, a gate of the second MOSFET is connected to the output terminal of the driving circuit through an inverter, the second MOSFET is connected to the first MOSFET, and a drain of the second MOSFET is connected to the comparison circuit.
Preferably, the driver further comprises a resistor R1 and a resistor R2, an input end of the resistor R1 is connected to an output end of the driver circuit, an output end of the resistor R1 is connected to a gate of the first MOSFET, an input end of the resistor R2 is connected to an output end of the inverter, and an output end of the resistor R2 is connected to a gate of the second MOSFET.
Preferably, the comparator circuit includes a comparator, a resistor R3, a resistor R4, a resistor R5 and a resistor R6, an input positive terminal of the comparator is connected to an input terminal of the resistor R5, an output terminal of the resistor R5 is connected to an input terminal of the resistor R3, an input terminal of the resistor R3 is further connected to a drain of the second MOSFET, an output terminal of the resistor R3 is connected to a drain of the first MOSFET, input negative terminals of the comparator are respectively connected to input terminals of the resistor R4 and the resistor R6, and output terminals of the resistor R4 and the resistor R6 are connected to an output terminal of the comparator.
Preferably, the comparator further comprises a capacitor C1, one end of the capacitor C1 is connected to the junction of the positive input terminal of the comparator and the resistor R5, and the other end of the capacitor C1 is connected to the output terminal of the comparator.
Preferably, the comparator further comprises a clamping diode D1, wherein an input end of the clamping diode D1 is connected with the drain of the second MOSFET, and an output end of the clamping diode D1 is connected with the output end of the comparator.
Preferably, the driving circuit is a PWM driving circuit.
The invention at least comprises the following beneficial effects:
1. the invention provides a middle-low voltage high-current MOSFET pulse current overcurrent detection circuit which can detect whether the pulse current passing through the MOSFET is overcurrent or not by detecting whether the conduction voltage drop of the MOSFET exceeds a set value or not.
2. The invention provides a middle-low voltage high-current MOSFET pulse current overcurrent detection circuit which can overcome the problem of high detection loss of a traditional general series resistor.
3. The medium-low voltage high-current MOSFET pulse current overcurrent detection circuit provided by the invention has the advantages of simple structure, low cost, market competitiveness and convenience in popularization.
Drawings
FIG. 1 is a schematic diagram of the operation of a low-voltage high-current MOSFET pulse current overcurrent detection circuit according to the present invention;
FIG. 2 is a waveform diagram of the signals of Q1G, Q2G, Q2D, VREF, and OUT of the present invention;
wherein, Q1: first MOSFET, Q2: second MOSFET, Q1B: inverter, U2: comparator, D1: clamping diode, U2: comparator, Q1G: signal waveform of gate Q1, Q2G: signal waveform of gate Q2, Q2D: signal waveform of the drain of Q2, VREF: the comparator U2 inputs the waveform of the negative side reference voltage, OUT: comparator U2S outputs a waveform.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
In the present specification, when an element is referred to as being "connected to" or coupled to "or" disposed in "another element, it may be" directly connected to "or coupled to" or "directly disposed in" the other element. Or be connected or coupled to or disposed in another element with other elements interposed therebetween, unless it is volumetrically "directly coupled or connected to" or "directly disposed in" the other element. Further, it will be understood that when an element is referred to as being "on," "over," "under" or "under" another element, it can be "in direct" contact with the other element or in contact with the other element interposed therebetween, unless it is referred to as being in direct contact with the other element.
The invention provides a medium-low voltage high-current MOSFET pulse current overcurrent detection circuit, which comprises:
a drive circuit;
the MOSFET detection circuit is connected with the output end of the driving circuit;
the input end of the comparison circuit is connected with the MOSFET detection circuit;
the comparator detects the conduction voltage drop and the reference level of the MOSFET detection circuit.
The comparison circuit of the invention compares the conduction voltage drop of the switch in the detection MOSFET circuit with the reference level, if the conduction voltage drop is lower than the reference level, the low level is output to indicate that the pulse current of the main power tube is not over-current, and if the conduction voltage drop is higher than the reference level, the comparator outputs the high level to indicate that the main power tube exceeds the set maximum current.
In view of the above, in yet another embodiment, as shown in fig. 1, the MOSFET detection circuit includes a first MOSFET and a second MOSFET, a gate of the first MOSFET is connected to the output terminal of the driving circuit, a gate of the second MOSFET is connected to the output terminal of the driving circuit through an inverter, the second MOSFET is connected to the first MOSFET, and a drain of the second MOSFET is connected to the comparison circuit.
The first MOSFET is an MOSFET to be detected with pulse current, namely a main power tube, and the second MOSFET is an auxiliary detection MOS tube;
specifically, the driver circuit further comprises a resistor R1 and a resistor R2, an input end of the resistor R1 is connected with an output end of the driving circuit, an output end of the resistor R1 is connected with a gate of the first MOSFET, an input end of the resistor R2 is connected with an output end of the inverter, and an output end of the resistor R2 is connected with a gate of the second MOSFET.
The output of drive circuit divides into two the tunnel, is connected with drive resistor R1's input all the way, and drive resistor R1's output is connected with main power tube (first MOSFET) Q1's grid, another way with inverter Q1B's input is connected, inverter Q1B's output is connected drive resistor R2's input, drive resistor R2's output and the grid connection of supplementary sense tube Q2 (second MOSFET).
The driving resistors R1 and R2 are used to match the switching speed of the MOSFET.
As shown in FIG. 2, Q1G is the signal waveform of the gate of the first MOSFET, Q2G is the signal waveform of the gate of the second MOSFET, and Q2D is the signal waveform of the drain of the second MOSFET, which fully illustrates the operation of each MOSFET in a pulse state)
In addition to the above embodiments, in yet another embodiment, the comparison circuit includes a comparator, a resistor R3, a resistor R4, a resistor R5, and a resistor R6, the positive input terminal of the comparator is connected to the input terminal of the resistor R5, the output terminal of the resistor R5 is connected to the input terminal of the resistor R3, the input terminal of the resistor R3 is further connected to the drain of the second MOSFET, the output terminal of the resistor R3 is connected to the drain of the first MOSFET, the negative input terminal of the comparator is connected to the input terminals of the resistor R4 and the resistor R6, respectively, and the output terminals of the resistor R4 and the resistor R6 are connected to the output terminal of the comparator.
As shown in fig. 2, VREF is the waveform of the negative terminal reference voltage input by the comparator U2; OUT is the output waveform of the comparator U2S, i.e. the overcurrent output signal, and when the MOSFET exceeds the pulse current for safe operation, its on voltage drop is higher than VREF, and the comparator outputs high level.
The resistor is used for voltage division, and the comparator is used for comparing the conduction voltage drop of the main power tube Q1 with a reference level, if the conduction voltage drop is lower than the reference level, the comparator outputs a low level to indicate that the pulse current of the main power tube is not overcurrent, and if the conduction voltage drop is higher than the reference level, the comparator outputs a high level to indicate that the main power tube exceeds the set maximum current.
On the basis of the above embodiment, in a further embodiment, the comparator further includes a capacitor C1, one end of the capacitor C1 is connected to a junction of the positive input terminal of the comparator and the resistor R5, and the other end of the capacitor C1 is connected to the output terminal of the comparator.
The capacitor C1 can remove interference with a delay.
On the basis of the above embodiment, a further embodiment further includes a clamping diode D1, an input terminal of the clamping diode D1 is connected to the drain of the second MOSFET, and an output terminal of the clamping diode D1 is connected to an output terminal of the comparator.
The driving circuit provided by the invention is a PWM driving circuit.
The embodiment of the invention provides a medium-low voltage high-current MOSFET pulse current overcurrent detection circuit, wherein one path of a PWM (pulse-Width modulation) driving circuit is connected to a grid electrode of a Q1 of a main power tube through a driving resistor R1, the other path of the PWM driving circuit is connected to an input end of an inverter Q1B, and an output end of the PWM driving circuit is connected with a driving resistor R2 to a grid electrode of an auxiliary detection tube Q2; the drain of the Q2 is divided into three paths, the first path is connected with a clamping diode D1 to an auxiliary power supply VCC, the second path is connected to the drain of a main power tube Q1 through a voltage detection resistor R3, the third path is connected to the input positive terminal of a comparator U2 after interference is removed through time delay through R5 and C1, the input negative terminal of the comparator U2 is divided by two resistors R4 and R5 to obtain a reference level, and the output end of the comparator U2 outputs an overcurrent detection signal; the drain of the main power tube Q1 is connected with a current-limiting resistor R3, and then connected with a clamping diode D1 to an auxiliary power supply VCC, and the drain voltage of the auxiliary detection tube Q2 (second MOSFET) is clamped to be not more than VCC plus D1 voltage drop at the highest.
In the embodiment of the invention, the comparator compares the conduction voltage drop of the main power tube Q1 with the reference level, if the conduction voltage drop is lower than the reference level, the comparator outputs a low level to indicate that the pulse current of the main power tube is not overcurrent, and if the conduction voltage drop is higher than the reference level, the comparator outputs a high level to indicate that the main power tube exceeds the set maximum current.
The working principle of the invention is as follows: when the PWM driving signal output is high, the main power transistor Q1 is turned on, and the voltage drop of the drain and source thereof is equal to the pulse current multiplied by the internal resistance of the first MOSFET. After the PWM driving signal passes through the inverter Q1B, it outputs low level, the auxiliary sense tube Q2 is turned off, and the clamp diode D1 is turned off due to reverse bias. The positive input terminal of the comparator U2 is the voltage drop of the drain-source of the main power tube, if the voltage drop is lower than the reference level, the voltage drop outputs a low level to indicate that the pulse current of the main power tube is not overcurrent, and if the voltage drop is higher than the reference level, the voltage drop outputs a high level to indicate that the main power tube has exceeded the set maximum current.
When the PWM driving signal output is low, the main power transistor Q1 is turned off, and its drain outputs high. The PWM drive signal goes high after passing through the inverter Q1B, so Q2 is turned on. The high level of the drain of the Q1 is current-limited by the R3 and then shorted by the Q2, and the on-state voltage drop of the Q2 is very low due to the small current on the R3, and the voltage of the positive input terminal of the comparator is close to 0.
The embodiment of the invention discloses a middle-low voltage large-current MOSFET pulse current overcurrent detection circuit, which is applied to the fields of switching power supplies, motor control and the like, and can detect whether the conduction voltage drop of an MOSFET passing through pulse current exceeds a safety value or not so as to determine whether the MOSFET is in overcurrent or not (when the pulse current of the MOSFET RT works is very large, such as dozens of A to hundreds of A, compared with the traditional series resistor detection current, the MOSFET pulse current overcurrent detection circuit has the advantage of small loss), and whether the MOSFET needs to be started and shut down or not is protected.
It is obvious that those skilled in the art can obtain various effects not directly mentioned according to the respective embodiments without trouble from various structures according to the embodiments of the present invention.
While embodiments of the invention have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.
Claims (7)
1. The utility model provides a low-and-medium voltage heavy current MOSFET pulse current overcurrent detection circuit which characterized in that includes:
a drive circuit;
the MOSFET detection circuit is connected with the output end of the driving circuit;
the input end of the comparison circuit is connected with the MOSFET detection circuit;
the comparator detects the conduction voltage drop and the reference level of the MOSFET detection circuit.
2. The medium-low voltage high-current MOSFET pulse current overcurrent detection circuit as set forth in claim 1, wherein the MOSFET detection circuit comprises a first MOSFET and a second MOSFET, a gate of the first MOSFET is connected to the output terminal of the drive circuit, a gate of the second MOSFET is connected to the output terminal of the drive circuit through an inverter, the second MOSFET is connected to the first MOSFET, and a drain of the second MOSFET is connected to the comparison circuit.
3. The medium and low voltage large current MOSFET pulse current overcurrent detection circuit of claim 2, further comprising a resistor R1 and a resistor R2, wherein an input terminal of the resistor R1 is connected to the output terminal of the drive circuit, an output terminal of the resistor R1 is connected to the gate of the first MOSFET, an input terminal of the resistor R2 is connected to the output terminal of the inverter, and an output terminal of the resistor R2 is connected to the gate of the second MOSFET.
4. The medium and low voltage large current MOSFET pulse current overcurrent detection circuit as claimed in claim 2, wherein the comparison circuit comprises a comparator, a resistor R3, a resistor R4, a resistor R5 and a resistor R6, the positive input terminal of the comparator is connected with the input terminal of the resistor R5, the output terminal of the resistor R5 is connected with the input terminal of the resistor R3, the input terminal of the resistor R3 is further connected with the drain of the second MOSFET, the output terminal of the resistor R3 is connected with the drain of the first MOSFET, the negative input terminals of the comparator are respectively connected with the input terminals of the resistor R4 and the resistor R6, and the output terminals of the resistor R4 and the resistor R6 are connected with the output terminal of the comparator.
5. The medium-low voltage high current MOSFET pulse current overcurrent detection circuit as set forth in claim 4, further comprising a capacitor C1, wherein one end of the capacitor C1 is connected to a junction of the positive input terminal of the comparator and the resistor R5, and the other end of the capacitor C1 is connected to the output terminal of the comparator.
6. The medium-low voltage high current MOSFET pulse current overcurrent detection circuit of claim 4, further comprising a clamping diode D1, wherein an input terminal of the clamping diode D1 is connected to the drain of the second MOSFET, and an output terminal of the clamping diode D1 is connected to the output terminal of the comparator.
7. The medium-low voltage high current MOSFET pulse current overcurrent detection circuit as recited in any one of claims 1 to 6, wherein the drive circuit is a PWM drive circuit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911297342.3A CN110940848A (en) | 2019-12-17 | 2019-12-17 | Middle-low voltage large current MOSFET pulse current overcurrent detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911297342.3A CN110940848A (en) | 2019-12-17 | 2019-12-17 | Middle-low voltage large current MOSFET pulse current overcurrent detection circuit |
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| CN110940848A true CN110940848A (en) | 2020-03-31 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103575964A (en) * | 2012-07-19 | 2014-02-12 | 快捷半导体(苏州)有限公司 | Over-current detection circuit and method for power switch tube |
| JP2014154669A (en) * | 2013-02-07 | 2014-08-25 | Denso Corp | Overcurrent detection circuit |
| CN105977905A (en) * | 2016-07-04 | 2016-09-28 | 西安电子科技大学 | Over-current and over-voltage and under-voltage drive protection system based on SiC MOSFET |
| CN108322033A (en) * | 2018-03-29 | 2018-07-24 | 西安理工大学 | The overcurrent protective device of SiCMOSFET converters and guard method |
| CN211652985U (en) * | 2019-12-17 | 2020-10-09 | 华羿微电子股份有限公司 | Middle-low voltage large current MOSFET pulse current overcurrent detection circuit |
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2019
- 2019-12-17 CN CN201911297342.3A patent/CN110940848A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103575964A (en) * | 2012-07-19 | 2014-02-12 | 快捷半导体(苏州)有限公司 | Over-current detection circuit and method for power switch tube |
| JP2014154669A (en) * | 2013-02-07 | 2014-08-25 | Denso Corp | Overcurrent detection circuit |
| CN105977905A (en) * | 2016-07-04 | 2016-09-28 | 西安电子科技大学 | Over-current and over-voltage and under-voltage drive protection system based on SiC MOSFET |
| CN108322033A (en) * | 2018-03-29 | 2018-07-24 | 西安理工大学 | The overcurrent protective device of SiCMOSFET converters and guard method |
| CN211652985U (en) * | 2019-12-17 | 2020-10-09 | 华羿微电子股份有限公司 | Middle-low voltage large current MOSFET pulse current overcurrent detection circuit |
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