CN105445608A

CN105445608A - SIC MOSFET over-current short-circuit detection circuit and detection protection system

Info

Publication number: CN105445608A
Application number: CN201510854460.5A
Authority: CN
Inventors: 凌家树; 胡杰; 周强
Original assignee: Shenzhen Invt Electric Co Ltd
Current assignee: Shenzhen yingweiteng Photovoltaic Technology Co. Ltd.
Priority date: 2015-11-30
Filing date: 2015-11-30
Publication date: 2016-03-30
Anticipated expiration: 2035-11-30
Also published as: CN105445608B

Abstract

The invention provides an SIC (Silicon Carbide) MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) over-current short-circuit detection circuit and detection protection system. The SIC MOSFET over-current short-circuit detection circuit comprises a first resistor, a second resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a 29th resistor, a 30th resistor, a third capacitor, a first diode, a second diode, a fourth diode, a fifth diode, a second triode and a switch current extending device. For the SIC MOSFET over-current short-circuit detection circuit, the switch current extending device is used, and the switching speed of the switch current extending device is higher than the switching speed of a SiC MOSFET; when the SiC MOSFET is completely turned on, the switch current extending device can be quickly turned on so that the detection circuit can quickly give a response and quickly enter into the detection stage and quickly detect whether over-current short circuit occurs in the SiC MOSFET. Therefore, the detection speed is improved so that the speed for the over-current short-circuit protection circuit to protect the SiC MOSFET is improved.

Description

SIC MOSFET overcurrent short-circuit detecting circuit and detection protection system

Technical field

The application relates to field of power electronics, particularly a kind of SICMOSFET overcurrent short-circuit detecting circuit and detection protection system.

Background technology

SIC (silit) MOSFET (metal-oxide half field effect transistor, Metal-Oxide-SemiconductorField-EffectTransistor) be the silicon carbide power switching device comparatively attracted attention at present, its the most obvious advantage is: low on-resistance and speed-sensitive switch, and driving circuit is simple and good with the compatibility of existing power device (silicon power MOSFET and IGBT) driving circuit.

But; present SiCMOSFET cost is higher; in actual applications; due to overload, internal drive mistake, interference or control improper etc. to cause the electric current flowing through SiCMOSFET to be far longer than the requirement of its area of safety operaton SOA; slowly will the SiCMOSFET of permanent damages costliness if do not have corresponding measure to go to protect or protected; therefore need a kind of overcurrent short-circuit detecting circuit at present badly to detect fast SiCMOSFET, to trigger short circuit over-current protection circuit, overcurrent short-circuit protection is timely carried out to SiCMOSFET.

Summary of the invention

For solving the problems of the technologies described above; the embodiment of the present application provides a kind of SICMOSFET overcurrent short-circuit detecting circuit and detects protection system; can detect whether SICMOSFET overcurrent short circuit phenomenon occurs fast to reach; improve detection speed; thus improve the object of overcurrent short-circuit protection short circuit to the protection speed of SICMOSFET, technical scheme is as follows:

A kind of SICMOSFET overcurrent short-circuit detecting circuit, comprising: the first resistance, the second resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, the 29 resistance, the 30 resistance, the 3rd electric capacity, the first diode, the second diode, the 4th diode, the 5th diode, the second triode and switch diffuser part;

The first end of described first resistance is connected with the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected, the first end of described first resistance is connected with the negative electrode of described second diode with the negative electrode of described first diode respectively, second end of described first resistance is connected with the first end of described switch diffuser part with the anode of described first diode, the first end of described second resistance respectively, the second end ground connection of described second resistance;

The first end of described switch diffuser part is connected with the first end of the 6th resistance, second end of described switch diffuser part is connected with the first driving isolation power supply malleation, 3rd end of described switch diffuser part is connected with the second end of described 6th resistance with the first end of the tenth resistance respectively, second end of described tenth resistance is connected with the anode of described 7th resistance with described 5th diode respectively, and the negative electrode of described 5th diode is connected with the drain electrode of described SICMOSFET to be detected;

Second end of described 7th resistance is connected with the anode of described second diode with the first end of described 8th resistance respectively, the first end of the 9th resistance described in the second end of described 8th resistance is connected, the first end of described 9th resistance is connected with the emitter of described second triode with the negative electrode of described 4th diode respectively, the plus earth of described 4th diode, second end of described 9th resistance is connected with the first end of described 29 resistance, second end of described 29 resistance is connected with the base stage of described second triode with the first end of described 30 resistance respectively, second end of described 30 resistance is connected with the second driving isolation power supply malleation, the collector of described second triode is connected with the overcurrent short-circuit protection output circuit of described SICMOSFET to be detected, described 3rd electric capacity and described 29 resistor coupled in parallel.

Preferably, described switch diffuser part is the first triode;

When described switch diffuser part is the first triode, described SICMOSFET overcurrent short-circuit detecting circuit also comprises: the 3rd diode;

The negative electrode of described 3rd diode is connected with the base stage of described first triode, and the anode of described 3rd diode is connected with the emitter of described first triode;

Wherein, the base stage of described first triode is as the first end of described switch diffuser part, and the collector of described first triode is as the second end of described switch diffuser part, and the emitter of described first triode is as the 3rd end of described switch diffuser part.

Preferably, also comprise: the 3rd resistance, the 4th resistance, the 5th resistance and a MOSFET;

The grid of a described MOSFET is connected with the second end of described first resistance, the drain electrode of a described MOSFET is connected with the first end of described 3rd resistance, second end of described 3rd resistance is connected with described first driving isolation power supply malleation, the source electrode of a described MOSFET is connected with the first end of described 5th resistance with the first end of described 4th resistance respectively, second end ground connection of described 4th resistance, the second end of described 5th resistance is connected with the first end of described 6th resistance with the base stage of described first triode, the negative electrode of described 3rd diode respectively.

Preferably, described switch diffuser part is the 3rd MOSFET;

When described switch diffuser part is the 3rd MOSFET, described SICMOSFET overcurrent short-circuit detecting circuit also comprises: the 9th diode, the 4th electric capacity and the 32 resistance;

Wherein, the grid of described 3rd MOSFET is as the first end of described 3rd MOSFET, and the drain electrode of described 3rd MOSFET is as second end of described 3rd MOSFET, and the source electrode of described 3rd MOSFET is as the 3rd end of described 3rd MOSFET;

The negative electrode of described 9th diode is connected with the first end of described 32 resistance with the drain electrode of described 3rd MOSFET respectively, the anode of described 9th diode is connected with described first driving isolation power supply malleation, second end ground connection of described 32 resistance, described 4th electric capacity and described 32 resistor coupled in parallel.

Preferably, also comprise: the 33 resistance, the 34 resistance, the tenth diode and the 2nd MOSFET;

The grid of described 2nd MOSFET is connected with the second end of described first resistance, the drain electrode of described 2nd MOSFET is connected with described first driving isolation power supply malleation, the source electrode of described 2nd MOSFET is connected with the first end of described 34 resistance with the first end of described 33 resistance respectively, second end ground connection of described 33 resistance, second end of described 34 resistance respectively with the grid of described 3rd MOSFET, the negative electrode of described tenth diode is connected with the first end of described 6th resistance, the anode of described 3rd diode is connected with the 3rd end of described first triode.

A kind of SICMOSFET overcurrent short circuit detection and protection system, comprising: controller, drive circuit unit, overcurrent short-circuit protection output unit, power-switching circuit and the SICMOSFET overcurrent short-circuit detecting circuit as described in above-mentioned any one;

Described controller, output PWM drive singal to described drive circuit unit, and exports clearing and reset signal extremely described overcurrent short-circuit protection output unit, and receives the false trigger signals of described overcurrent short-circuit protection output unit output;

Described drive circuit unit, receives the PWM drive singal that described controller exports, drives SICMOSFET to be detected;

Described SICMOSFET overcurrent short-circuit detecting circuit carries out overcurrent short-circuit detecting to the SICMOSFET to be detected in described drive circuit unit and false trigger signals is exported to described overcurrent short-circuit protection output unit;

Described overcurrent short-circuit protection output unit, carries out overcurrent short-circuit protection according to described false trigger signals to the SICMOSFET in described drive circuit unit;

Described power-switching circuit, the first driving isolation power supply positive-pressure rotary used by described SICMOSFET overcurrent short-circuit detecting circuit is changed to the second driving isolation power supply malleation, and powers for described SICMOSFET overcurrent short circuit detection and protection system.

Preferably, described drive circuit unit comprises: driving isolation optocoupler, the 16 resistance, the 4th triode, the 5th triode, the 17 resistance, the 18 resistance, the 6th diode, the 7th diode, the 8th diode, the first electric capacity, the 19 resistance, SiCMOSFET to be detected, the first driving isolation power supply malleation and driving isolation power supply negative pressure;

The first input end of described driving isolation optocoupler is connected with described controller, second input end grounding of described driving isolation optocoupler, first output terminal of described driving isolation optocoupler is connected with described driving isolation power supply malleation, second output terminal of described driving isolation optocoupler is connected with described 16 resistance with described SICMOSFET overcurrent short-circuit detecting circuit respectively, and the 3rd output terminal of described driving isolation optocoupler is connected with described driving isolation power supply negative pressure;

Second end of described 16 resistance is connected with described overcurrent short-circuit protection output unit with the base stage of described 4th triode, the base stage of described 5th triode respectively;

The collector of described 4th triode is connected with described first driving isolation power supply malleation, the emitter of described 4th triode is connected with the first end of described 17 resistance with the emitter of described 5th triode respectively, and the collector of the 5th triode is connected with described driving isolation power supply negative pressure;

The first end of described 17 resistance is connected with the negative electrode of described 6th diode, and the anode of described 6th diode is connected with the first end of described 18 resistance, and the second end of described 18 resistance is connected with the second end of described 17 resistance;

Second end of described 17 resistance is connected with the grid of described SICMOSFET to be detected with the anode of described 7th diode, the negative electrode of described 8th diode, the first end of described 19 resistance respectively;

The negative electrode of described 7th diode is connected with described driving isolation power supply malleation, the anode of described 8th diode is connected with described driving isolation power supply negative pressure, second end ground connection of described 19 resistance, described first electric capacity and described 19 resistor coupled in parallel, the drain electrode of described SICMOSFET to be detected is connected with described SICMOSFET overcurrent short-circuit detecting circuit, the source ground of described SICMOSFET to be detected.

Preferably, described overcurrent short-circuit protection output unit comprises: the 9th diode, the 20 resistance, the 21 resistance, the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the second triode, the 3rd triode, DQ trigger, the 25 resistance, the 26 resistance, the first isolation optocoupler, the second isolation optocoupler, the 27 resistance, the 28 resistance and the 31 resistance;

The anode of described 9th diode is connected with described SICMOSFET overcurrent short-circuit detecting circuit, the negative electrode of described 9th diode is connected with the first end of described 20 resistance, second end of described 20 resistance is connected with the CLK pin of described DQ trigger with the first end of described 21 resistance respectively, the second end ground connection of described 21 resistance;

The D pin of described DQ trigger is connected with the second driving isolation power supply malleation, described DQ trigger pin is connected with the first end of described 31 resistance, and the second end of described 31 resistance is connected with described second driving isolation power supply malleation, described DQ trigger pin is connected with the described first first input end of isolating optocoupler, and the second input end of described first isolation optocoupler is connected with the first end of described 25 resistance, and the second end of described 25 resistance is connected with described second driving isolation power supply malleation; First output terminal of described first isolation optocoupler is connected with described controller with the first end of described 26 resistance respectively, second output head grounding of described first isolation optocoupler, the second end of described 26 resistance is connected with the 3rd driving isolation power supply malleation;

Described DQ trigger the first output terminal that pin isolates optocoupler with the first end and described second of described 27 resistance is respectively connected, second end of described 27 resistance is connected with described second driving isolation power supply malleation, second output head grounding of described second isolation optocoupler, second input end of described second isolation optocoupler is connected with the first end of described 28 resistance, second end of described 28 resistance is connected with described controller, the first input end ground connection of described second isolation optocoupler;

The collector of described 3rd triode is connected with described drive circuit unit, the base stage of described 3rd triode is connected with the first end of described 15 resistance, the grounded emitter of described 3rd triode, second end of described 15 resistance is connected with the emitter of described second triode with the first end of described 14 resistance respectively, second end ground connection of described 14 resistance, the collector of described second triode is connected with the first end of described 12 resistance, second end of described 12 resistance is connected with described first driving isolation power supply malleation, the base stage of described second triode is connected with the first end of described 13 resistance with the first end of described 11 resistance respectively, second end of described 11 resistance is connected with the Q pin of described DQ trigger, second end ground connection of described 13 resistance.

Preferably, described power-switching circuit comprises: the 22 resistance, the 23 resistance, the 24 resistance, the second electric capacity and controllable accurate source of stable pressure;

The first end of described 22 resistance is connected with described first driving isolation power supply malleation, second end of described 22 resistance is connected with the negative electrode of described controllable accurate source of stable pressure, the plus earth of described controllable accurate source of stable pressure, the negative electrode of described controllable accurate source of stable pressure is connected with the first end of described 23 resistance, second end of described 23 resistance is connected with the first end of described 24 resistance with the reference pole of described controllable accurate source of stable pressure respectively, second end ground connection of described 24 resistance, the first end of described second electric capacity is connected with the first end of described 23 resistance and exports described second driving isolation power supply malleation, second end ground connection of described second electric capacity.

Compared with prior art, the beneficial effect of the application is:

In this application; SICMOSFET overcurrent short-circuit detecting circuit can use the switch diffuser part had than SicMOSFET switching speed faster; because the switching speed of switch diffuser part is fast; therefore after SicMOSFET opens completely; switch diffuser part can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs fast; improve detection speed, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the embodiment of the present application, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is a kind of electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 2 is the another kind of electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 3 is a kind of course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 4 is the another kind of course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 5 is the another kind of electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 6 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 7 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 8 is another electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Fig. 9 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Figure 10 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Figure 11 is another electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Figure 12 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Figure 13 is another course of work schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides;

Figure 14 is a kind of electronic schematic diagram of the SICMOSFET overcurrent short circuit detection and protection system that the application provides;

Figure 15 is a kind of electronic schematic diagram of the drive circuit unit that the application provides;

Figure 16 is a kind of electronic schematic diagram of the overcurrent short-circuit protection output unit that the application provides;

Figure 17 is a kind of electronic schematic diagram of the power-switching circuit that the application provides;

Figure 18 is a kind of logical specification figure of the DQ trigger that the application provides;

Figure 19 is a kind of work schedule schematic diagram of the SICMOSFET overcurrent short circuit detecting system that the application provides.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present application, be clearly and completely described the technical scheme in the embodiment of the present application, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.

Embodiment one

Refer to Fig. 1, it illustrates a kind of electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides, SICMOSFET overcurrent short-circuit detecting circuit comprises: the first resistance R1, the second resistance R2, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10, the 29 resistance R29, the 30 resistance R30, the 3rd electric capacity C3, the first diode D1, the second diode D2, the 4th diode D4, the 5th diode D5, the second triode Q2 and switch diffuser part Sef.

Wherein, first end (the i.e. described first resistance R1 of the first resistance R1, the common port A of the first diode D1 and the second diode D2) be connected with the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected, the first end of described first resistance R1 is connected with the negative electrode of described second diode D2 with the negative electrode of described first diode D1 respectively, second end of described first resistance R1 respectively with the anode of described first diode D1, the first end of described second resistance R2 is connected with the first end of described switch diffuser part Sef, the second end ground connection of described second resistance R2,

The first end of described switch diffuser part Sef is connected with the first end of the 6th resistance R6, second end of described switch diffuser part Sef is connected with the first driving isolation power supply malleation+VCC1,3rd end of described switch diffuser part Sef is connected with second end of described 6th resistance R6 with the first end of the tenth resistance R10 respectively, second end of described tenth resistance R10 is connected with the anode of described 5th diode D5 with described 7th resistance R7 respectively, and the negative electrode of described 5th diode D5 is connected with the drain electrode of described SICMOSFET to be detected;

Second end of described 7th resistance R7 is connected with the anode of described second diode D2 with the first end of described 8th resistance R8 respectively, the first end of the 9th resistance R9 described in second end of described 8th resistance R8 is connected, the first end of described 9th resistance R9 is connected with the emitter of described second triode Q2 with the negative electrode of described 4th diode D4 respectively, the plus earth of described 4th diode D4, second end of described 9th resistance R9 is connected with the first end of described 29 resistance R29, second end of described 29 resistance R29 is connected with the base stage of described second triode Q2 with the first end of described 30 resistance R30 respectively, second end of described 30 resistance R30 is connected with the second driving isolation power supply malleation+VCC2, the collector of described second triode Q2 is connected with the overcurrent short-circuit protection output circuit of described SICMOSFET to be detected, described 3rd electric capacity C3 is in parallel with described 29 resistance R29.

Wherein, in the present embodiment and in following embodiment; A point is connected with drive circuit unit belonging to SICMOSFET to be detected; D point is connected with the drain electrode of SICMOSFET to be detected in drive circuit unit belonging to SICMOSFET to be detected; C point is connected with overcurrent short-circuit protection output unit; wherein, overcurrent short-circuit protection output unit is used for carrying out overcurrent short-circuit protection to SICMOSFET to be detected.

In this application; SICMOSFET overcurrent short-circuit detecting circuit can use the switch diffuser part had than SicMOSFET to be detected switching speed faster; because the switching speed of switch diffuser part is fast; therefore after SicMOSFET to be detected opens completely; switch diffuser part can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs fast; improve detection speed, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.

In the present embodiment, described switch diffuser part Sef is specifically as follows the first triode Q1, as shown in Figure 2.

When described switch diffuser part Sef is the first triode Q1, described SICMOSFET overcurrent short-circuit detecting circuit also comprises: the 3rd diode.

The negative electrode of described 3rd diode is connected with the base stage of described first triode, and the anode of described 3rd diode is connected with the emitter of described first triode.

When described switch diffuser part Sef is the first triode Q1, the base stage of described first triode Q1 is as the first end of described switch diffuser part Sef, the collector of described first triode Q1 is as second end of described switch diffuser part Sef, and the emitter of described first triode Q1 is as the 3rd end of described switch diffuser part Sef.

In the present embodiment; the switching speed of the first triode Q1 is faster than the switching speed of SicMOSFETTd to be detected; therefore after SicMOSFETTd to be detected opens completely; first triode Q1 can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs, and improves detection speed fast, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.Wherein, the 3rd diode D3 for the protection of first triode Q1 emitter-base stage in order to avoid punctured by reflected voltage.

The course of work of the circuit shown in Fig. 2 is as follows: as shown in Figure 3, when A point in the common port and Fig. 3 of described first resistance R1, the first diode D1 and the second diode D2, during the high level PWM drive singal that the pwm signal output terminal receiving drive circuit unit belonging to SICMOSFET to be detected exports, SicMOSFETTd to be detected is first open-minded.By arranging the first resistance R1, the speed of opening that the second resistance R2 resistance adjusts the first triode Q1 is slower than SicMOSFETTd to be detected.Wherein, the parameter designing of condition by experiment, what make the blanking time (the first triode Q1 opens the difference that moment and SicMOSFETTd to be detected open the moment) adapt to SicMOSFETTd to be detected opens requirement fast.Make a point voltage to be simultaneously: wherein the 6th resistance R6 is comparatively large, makes a point voltage V _a3. flow into loop electric current 4. by loop very little, its synergistic effect almost can be ignored.B point voltage is: V _b=V _a-V _{bE_Q1}(V _{bE_Q1}for the pressure drop between transistor base-emitter, about 0.7V ~ 0.8V).6th resistance R6, the tenth resistance R10 and the first triode Q1 form current amplification circuit, and the electric current guaranteeing 6. to flow through the 5th diode D5 in loop is enough large and the conduction voltage drop that maintains the 5th diode D5 is stablized.The voltage of d point is the conduction voltage drop V of the 5th diode D5 _d5with SicMOSFETTd conduction voltage drop V to be detected _dSsum, i.e. V _d=V _dS+ V _d5, the maximum voltage of d point is controlled in simultaneously (V _{bE_Q1}for the pressure drop between transistor base-emitter, about 0.7V ~ 0.8V).The voltage of f point is: such V _fmaximal value also by V _dmaximal value restriction.Second triode Q2, the 29 resistance R29, the 30 resistance R30, the 3rd electric capacity C3, the second driving isolation power supply malleation+VCC2 constitutes voltage monitoring circuit, and g point voltage is:

V_{g} = \frac{+ V_{c c 2} * R_{29}}{R_{29} + R_{30}} .

As Fig. 4, when the pwm signal output terminal output low level PWM drive singal of drive circuit unit belonging to SicMOSFETTd to be detected, A point becomes negative level-VEE, SicMOSFETTd to be detected turns off, now e point voltage through loop 1., is pulled to rapidly A point current potential, and f point is also negative pressure, 4th diode D4 at-VD4 (about-0.5 ~-0.7V), exceeds device required by maximal value to prevent the voltage between second triode Q2 base stage-emitter f point current potential clamper.2. first triode Q1 also turns off rapidly through loop simultaneously.When SicMOSFETTd to be detected turns off, the peak voltage part produced will reflex to inside circuit by the stray capacitance of the 5th diode D5, in order to discharge peak voltage, provides 2. in circuit from d point, 3. 2 loops.The peak voltage produced when the SICMOSFET overcurrent short-circuit detecting circuit that the present embodiment provides can turn off fast on SicMOSFETTd to be detected drops to the minimum object even eliminated on the mode that the reflected voltage of SICMOSFET overcurrent short-circuit detecting circuit is discharged by loop its impact, improves SICMOSFET overcurrent short-circuit detecting circuit reliability in actual applications, antijamming capability and adaptability.

Refer to Fig. 3, the principle of the SICMOSFET overcurrent short-circuit detecting circuit shown in Fig. 2 being carried out to overcurrent short-circuit detecting is described.Specific as follows:

In the present embodiment, SICMOSFET overcurrent short-circuit detecting circuit utilizes SicMOSFETTd On current to be detected larger, and the characteristic that its conduction voltage drop is larger, carries out overcurrent short-circuit detecting to SicMOSFETTd to be detected.If the overcurrent short-circuit protection threshold value of SicMOSFETTd to be detected is I _{dS_th}, the conduction voltage drop threshold value of its correspondence is V _{dS_th}, when SicMOSFETTd conduction voltage drop to be detected is V _{dS_th}time, in corresponding diagram 3, the voltage of d point is V _{d_th}=V _{dS_th}+ V _d5(V _d5conduction voltage drop for D5), the maximum voltage of d point is controlled in the voltage of f point is: v _fmaximal value also by V _dmaximal value restriction.

Second triode Q2, the 29 resistance R29, the 30 resistance R30, the 3rd electric capacity C3, the second driving isolation power supply malleation+VCC2 constitutes voltage monitoring circuit, and g point voltage is:

V_{g_t h} = V_{f_t h} - V_{B E_Q 2} = \frac{(V_{D S_t h} + V_{D 5}) * R_{9}}{R_{7} + R_{8} + R_{9}} - V_{B E_Q 2},

And V _{g_th}voltage is by+VCC2 by the 29 resistance R29, and the 30 resistance R30 dividing potential drop gained, by arranging the 29 resistance R29, the 30 resistance R30 makes

V_{g_t h} = \frac{+ V_{c c 2} * R_{29}}{R_{29} + R_{30}} = \frac{(V_{D S_t h} + V_{D 5}) * R_{9}}{R_{7} + R_{8} + R_{9}} - V_{B E_Q 2} .

Under normal circumstances, when there is not overcurrent or short circuit in SicMOSFETTd to be detected, its conduction voltage drop V _dSbe less than conduction voltage drop threshold value V _{dS_th}, that is: V _dS< V _{dS_th}, the voltage of final f point is: second triode Q2 can not conducting, and C point is low level, not triggered flow short-circuit protection output unit.

Overcurrent or short circuit is there is, its conduction voltage drop V once SicMOSFETTd to be detected _dSbe greater than conduction voltage drop threshold value that is: V _dS> V _{dS_th}, the voltage of final f point is: second triode Q2 conducting, C point voltage becomes V from low level _f-V _{cE_Q2}, and with this signal triggered flow short-circuit protection output unit, to realize the overcurrent short-circuit protection to SicMOSFETTd to be detected.

Further, it is adjustable that the SICMOSFET overcurrent short-circuit detecting circuit that the application provides crosses flow point threshold value.Wherein the SICMOSFET overcurrent short-circuit detecting circuit principle of crossing flow point threshold value adjustable is as follows:

Larger according to SicMOSFETTd On current to be detected, the characteristic that its conduction voltage drop is larger, supposes that the overcurrent short-circuit protection threshold value of SicMOSFET is I _{dS_th}, the conduction voltage drop threshold value of its correspondence is V _{dS_th}, when SicMOSFETTd conduction voltage drop to be detected is V _{dS_th}time, in corresponding diagram 3, the voltage of d point is (V _d5conduction voltage drop for D5), the voltage of f point is:

V_{f_t h} = \frac{V_{d_t h} * R_{9}}{R_{7} + R_{8} + R_{9}} = \frac{(V_{D S_t h} + V_{D 5}) * R_{9}}{R_{7} + R_{8} + R_{9}},

G point voltage is:

V_{g_t h} = V_{f_t h} - V_{B E_Q 2} = \frac{(V_{D S_t h} + V_{D 5}) * R_{9}}{R_{7} + R_{8} + R_{9}} - V_{B E_Q 2},

And V _{g_th}voltage is by the second driving isolation power supply malleation+VCC2 by the 29 resistance R29, and the 30 resistance R30 dividing potential drop gained, by arranging the 29 resistance R29, the 30 resistance R30 makes

V_{g_t h} = \frac{+ V_{c c 2} * R_{29}}{R_{29} + R_{30}} = \frac{(V_{D S_t h} + V_{D 5}) * R_{9}}{R_{7} + R_{8} + R_{9}} - V_{B E_Q 2},

Thus

V_{D S_t h} = (\frac{+ V_{c c 2} * R_{29}}{R_{29} + R_{30}} + V_{B E_Q 2}) * \frac{R_{7} + R_{8} + R_{9}}{R_{9}} - V_{D 5},

Due to the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, V _d5, V _{bE_Q2},+VCC2 is known, overcurrent short-circuit protection threshold value I _{dS_th}the conduction voltage drop of corresponding SicMOSFETTd to be detected is V _{dS_th}, by designing the 29 resistance R29, the resistance of the 30 resistance R30 just can adjust conduction voltage drop V _{dS_th}, thus can adjusted flow short-circuit protection threshold value.

Embodiment two

In the present embodiment, show the another kind of electronic schematic diagram of the SICMOSFET overcurrent short-circuit detecting circuit that the application provides, refer to Fig. 5, the SICMOSFET overcurrent short-circuit detecting circuit that the present embodiment provides also comprises on the basis of the SICMOSFET overcurrent short-circuit detecting circuit shown in Fig. 2: the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5 and a MOSFETT1.

The grid of a described MOSFETT1 is connected with second end of described first resistance R1, the drain electrode of a described MOSFETT1 is connected with the first end of described 3rd resistance R3, second end of described 3rd resistance R3 is connected with described first driving isolation power supply malleation+VCC1, the source electrode of a described MOSFETT1 is connected with the first end of described 5th resistance R5 with the first end of described 4th resistance R4 respectively, the second end ground connection of described 4th resistance R4, second end of described 5th resistance R5 respectively with the base stage of described first triode Q1, the negative electrode of described 3rd diode D3 is connected with the first end of described 6th resistance R6.

In the present embodiment, only the different operating process of the circuit shown in the circuit shown in Fig. 5 and Fig. 2 be described, the course of work identical with the circuit shown in Fig. 2 repeats no more.As follows:

As shown in Figure 6, when the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected exports high level PWM drive singal, one MOSFETT1 is when opening, first driving isolation power supply malleation+VCC1 is by a MOSFETT1,3rd resistance R3 and the 5th resistance R5 is supplied to the bias voltage needed for base stage-emitter conducting of the first triode Q1, makes the first triode Q1 conducting.Wherein, b point voltage is as the input offset voltage of the first triode Q1, and wherein the 6th resistance R6 is comparatively large, and make Vb point 3. flow into loop electric current 4. by loop very little, its synergistic effect almost can be ignored, and b point voltage is: V _b=V _a-V _{th_T1}(V _{th_T1}be the conducting threshold voltage of a MOSFETT1).5th resistance R5, the 6th resistance R6, the tenth resistance R10 and the first triode Q1 form current amplification circuit, and the electric current guaranteeing 6. to flow through the 5th diode D5 in loop is enough large and the conduction voltage drop that maintains the 5th diode D5 is stablized.The voltage of d point is the conduction voltage drop V of the 5th diode D5 _d5with SicMOSFETTd conduction voltage drop V to be detected _dSsum, i.e. V _d=V _dS+ V _d5.

As Fig. 7, when the pwm signal output terminal output low level PWM drive singal of drive circuit unit belonging to SICMOSFET to be detected, A point becomes negative level-VEE, SicMOSFETTd to be detected turns off, now e point voltage through loop 1., is pulled to rapidly A point current potential, and f point is also negative pressure, 4th diode D4 at-VD4 (about-0.5 ~-0.7V), exceeds device required by maximal value to prevent the voltage between second triode Q2 base stage-emitter f point current potential clamper.2. a MOSFETT1 also turns off rapidly through loop simultaneously, and when a MOSFETT1 turns off, the base stage-emitter of the first triode Q1 is without bias voltage and bias current, so the first triode Q1 also turns off simultaneously.When SicMOSFETTd to be detected turns off; the peak voltage part produced will reflex to inside circuit by the stray capacitance of the 5th diode D5; in order to discharge peak voltage; provide 3. from d point in circuit; 4. two loops, wherein, because loop is 3. through c point; c point is connected with the base stage of the first triode Q1, increases by the 3rd diode D3 and protects first triode Q1 emitter-base stage in order to avoid punctured by reflected voltage.

In the present embodiment, the principle that SICMOSFET overcurrent short-circuit detecting circuit carries out overcurrent short-circuit detecting refers in embodiment one see Fig. 3, the process that the principle of carrying out overcurrent short-circuit detecting to the SICMOSFET overcurrent short-circuit detecting circuit shown in Fig. 2 is described, does not repeat them here.

In the present embodiment, SICMOSFET overcurrent short-circuit detecting circuit adds the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5 and a MOSFETT1 compared to the SICMOSFET overcurrent short-circuit detecting circuit shown in embodiment one Fig. 2, control by a MOSFETT1 dirigibility that the first triode Q1 adds the regulation of electrical circuit, make circuit parameter be more prone to adjustment.

In the present embodiment; the switching speed of the one MOSFETT1 is faster than the switching speed of SicMOSFETTd to be detected equally; therefore after SicMOSFETTd to be detected opens completely; one MOSFETT1 and the first triode Q1 can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs, and improves detection speed fast, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.

Embodiment three

In the present embodiment, show the SICMOSFET overcurrent short-circuit detecting circuit be different from shown in Fig. 2, refer to Fig. 8, the switch diffuser part Sef in the SICMOSFET overcurrent short-circuit detecting circuit that the present embodiment provides can also be the 3rd MOSFETT3.

When switch diffuser part Sef is the 3rd MOSFETT3, compared to the SICMOSFET overcurrent short-circuit detecting circuit shown in Fig. 2, the SICMOSFET overcurrent short-circuit detecting circuit that the present embodiment provides also comprises: the 9th diode D9, the 4th electric capacity C4 and the 32 resistance R32.

Wherein, the grid of described 3rd MOSFETT3 is as the first end of described 3rd MOSFET, and the drain electrode of described 3rd MOSFETT3 is as second end of described 3rd MOSFETT3, and the source electrode of described 3rd MOSFETT3 is as the 3rd end of described 3rd MOSFETT3;

The negative electrode of described 9th diode D9 is connected with the first end of described 32 resistance R32 with the drain electrode of described 3rd MOSFETT3 respectively, the anode of described 9th diode D9 is connected with described first driving isolation power supply malleation+VCC1, the second end ground connection of described 32 resistance R32, described 4th electric capacity C4 is in parallel with described 32 resistance R32.

When being replaced the first triode Q1 in Fig. 2 by the 3rd MOSFETT3, increase by the 9th diode D9, the reason of the 4th electric capacity C4 and the 32 resistance R32 is as follows: have integration diode in the 3rd MOSFETT3, peak voltage when SicMOSFETTd to be detected turns off can by the integrating capacitor of the 5th diode D5, the integration diode of the tenth resistance R10 and the 3rd MOSFETT3 is added on the first driving isolation power supply malleation+VCC1, therefore increase by the 9th diode D9, 4th electric capacity C4 and the 32 resistance R32 absorbs peak voltage when SicMOSFETTd to be detected turns off, avoid the first driving isolation power supply malleation+VCC1 too high, affect circuit normally to work.

In the present embodiment, only the different operating process of the circuit shown in the circuit shown in Fig. 8 and Fig. 2 be described, the course of work identical with the circuit shown in Fig. 2 repeats no more.As follows:

As shown in Figure 9, when the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected exports high level PWM drive singal, b point voltage is: V _b=V _a-V _{th_T3}(V _{th_T3}be the conducting threshold voltage of the 3rd MOSFETT3).Tenth resistance R10 and the 3rd MOSFETT3 forms current amplification circuit, and the electric current guaranteeing 6. to flow through the 5th diode D5 in loop is enough large and the conduction voltage drop that maintains the 5th diode D5 is stablized.The voltage of d point is the conduction voltage drop V of the 5th diode D5 _d5with SicMOSFETTd conduction voltage drop V to be detected _dSsum, i.e. V _d=V _dS+ V _d5, the maximum voltage of d point is controlled in simultaneously

V_{d_m a x} = \frac{V_{b} * (R_{7} + R_{8} + R_{9})}{R_{7} + R_{8} + R_{9} + R_{10}} .

The voltage of f point is:

V_{f} = \frac{V_{d} * R_{9}}{R_{7} + R_{8} + R_{9}},

Such V _fmaximal value also by V _dmaximal value restriction.

As shown in Figure 10, when the low level PWM drive singal that the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected exports, A point becomes negative level-VEE, SicMOSFETTd to be detected turns off, now e point voltage through loop 1., is pulled to rapidly A point current potential, and f point is also negative pressure, 4th diode D4 at-VD4 (about-0.5 ~-0.7V), exceeds device required by maximal value to prevent the voltage between second triode Q2 base stage-emitter f point current potential clamper.2. 3rd MOSFETT3 also turns off rapidly through loop simultaneously.When SicMOSFETTd to be detected turns off, the peak voltage part produced will reflex to inside circuit by the stray capacitance of the 5th diode D5, in order to discharge peak voltage, provides 2. in circuit from d point, 3., and 5. 3 loops.

Equally, it is adjustable that the SICMOSFET overcurrent short-circuit detecting circuit that the present embodiment provides crosses flow point threshold value, SICMOSFET overcurrent short-circuit detecting circuit crosses the adjustable principle of flow point threshold value can cross the adjustable principle of flow point threshold value see SICMOSFET overcurrent short-circuit detecting circuit in embodiment one, does not repeat them here.

In this application; SICMOSFET overcurrent short-circuit detecting circuit employs the 3rd MOSFET had than SicMOSFET to be detected switching speed faster; because the switching speed of the 3rd MOSFET is fast; therefore after SicMOSFET to be detected opens completely; 3rd MOSFET can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs fast; improve detection speed, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.

Embodiment four

In the present embodiment, SICMOSFET overcurrent short-circuit detecting circuit also comprises on the SICMOSFET overcurrent short-circuit detecting circuit basis shown in Fig. 8: the 33 resistance R33, the 34 resistance R34, the tenth diode D10 and the 2nd MOSFETT2, as shown in figure 11.

The grid of described 2nd MOSFETT2 is connected with second end of described first resistance R1, the drain electrode of described 2nd MOSFETT2 is connected with described first driving isolation power supply malleation+VCC1, the source electrode of described 2nd MOSFETT2 is connected with the first end of described 34 resistance R34 with the first end of described 33 resistance R33 respectively, the second end ground connection of described 33 resistance R33, second end of described 34 resistance R34 respectively with the grid of described 3rd MOSFETT3, the negative electrode of described tenth diode D10 is connected with the first end of described 6th resistance R6, the anode of described 3rd diode D3 is connected with the 3rd end of described first triode Q1.

In the present embodiment, only the different operating process of the circuit shown in the circuit shown in Figure 11 and Fig. 8 be described, the course of work identical with the circuit shown in Fig. 8 repeats no more.As follows:

As shown in figure 12, when the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected exports high level PWM drive singal, after 2nd MOSFETT2 opens, b point voltage is as the input queued switches voltage of the 3rd MOSFETT3, wherein the 6th resistance R6 is larger, make Vb point 3. flow into loop electric current 4. by loop very little, its synergistic effect almost can be ignored, and b point voltage is: V _b=V _a-V _{th_T2}(V _{th_T2}be the conducting threshold voltage of the 2nd MOSFETT2).34 resistance R34, the 6th resistance R6, the tenth resistance R10 and the 3rd MOSFETT3 form current amplification circuit, and the electric current guaranteeing 6. to flow through the 5th diode D5 in loop is enough large and the conduction voltage drop that maintains the 5th diode D5 is stablized.The voltage of d point is the conduction voltage drop V of the 5th diode D5 _d5with SicMOSFETTd conduction voltage drop V to be detected _dSsum, i.e. V _d=V _dS+ V _d5, the maximum voltage of d point is controlled in simultaneously (V _{th_T3}be the conducting threshold voltage of the 3rd MOSFETT3).

As shown in figure 13, when the low level PWM drive singal that the pwm signal output terminal of drive circuit unit belonging to SICMOSFET to be detected exports, A point becomes negative level-VEE, SicMOSFETTd to be detected turns off, now e point voltage through loop 1., is pulled to rapidly A point current potential, and f point is also negative pressure, 4th diode D4 at-VD4 (about-0.5 ~-0.7V), exceeds device required by maximal value to prevent the voltage between second triode Q2 base stage-emitter f point current potential clamper.2. 2nd MOSFETT2 also turns off rapidly through loop simultaneously.When SicMOSFETTd to be detected turns off; the peak voltage part produced will reflex to inside circuit by the stray capacitance of the 5th diode D5; in order to discharge peak voltage; provide 3. from d point in circuit; 4.; 5. 3 loops, the 3rd diode D3 also protects the 3rd MOSFETT3 grid-source electrode in order to avoid punctured by reflected voltage simultaneously.

In the present embodiment; the switching speed of the 2nd MOSFETT2 is faster than the switching speed of SicMOSFETTd to be detected; therefore after SicMOSFETTd to be detected opens completely; 2nd MOSFETT2 and the 3rd MOSFETT3 can be open-minded fast; testing circuit is enable to respond fast to enter detection-phase fast; thus can detect whether SICMOSFET overcurrent short circuit phenomenon occurs, and improves detection speed fast, thus improve the protection speed of overcurrent short-circuit protection short circuit to SICMOSFET.

Wherein, in the "×" indication circuit in Fig. 4, Fig. 7, Figure 10 and Figure 13, device is in off state.

Embodiment five

In the present embodiment; show the SICMOSFET overcurrent short circuit detection and protection system that the application provides; refer to Figure 14, SICMOSFET overcurrent short circuit detection and protection system comprises: controller 11, drive circuit unit 12, overcurrent short-circuit protection output unit 13, power-switching circuit 14 and SICMOSFET overcurrent short-circuit detecting circuit 15.

Wherein, described controller 11 is connected with described overcurrent short-circuit protection output unit 13 with described drive circuit unit 12 respectively; for exporting PWM drive singal to described drive circuit unit 12; and export clearing and reset signal extremely described overcurrent short-circuit protection output unit 13, and receive the false trigger signals of described overcurrent short-circuit protection output unit 13 output.

Controller 11 receive described overcurrent short-circuit protection output unit 13 export false trigger signals be high level time; normal output PWM drive singal is to described drive circuit unit 12; when receiving false trigger signals that described overcurrent short-circuit protection output unit 13 exports and being low level, stop exporting PWM drive singal to described drive circuit unit 12.

Described drive circuit unit 12, is connected with described SICMOSFET overcurrent short-circuit detecting circuit 15, for receiving the PWM drive singal that described controller 11 exports, drives SICMOSFET to be detected.

SICMOSFET overcurrent short-circuit detecting circuit 15; be connected with overcurrent short-circuit protection output unit 13, for carrying out overcurrent short-circuit detecting to the SICMOSFET to be detected in described drive circuit unit 12 and false trigger signals being exported to described overcurrent short-circuit protection output unit 13.

The concrete structure of SICMOSFET overcurrent short-circuit detecting circuit 15 and carry out overcurrent short-circuit detecting to the SICMOSFET to be detected in described drive circuit unit 12 and process overcurrent short-circuit detecting result being exported to described overcurrent short-circuit protection output unit 13 refers to the SICMOSFET overcurrent short-circuit detecting circuit 15 shown in embodiment one to embodiment four, does not repeat them here.

Described overcurrent short-circuit protection output unit 13, is connected with described drive circuit unit 12, carries out overcurrent short-circuit protection according to described false trigger signals to the SICMOSFET in described drive circuit unit 12.

Described power-switching circuit 14 is converted to the second driving isolation power supply malleation+VCC2 for the first driving isolation power supply malleation+VCC1 used by described SICMOSFET overcurrent short-circuit detecting circuit 15, and powers for described SICMOSFET overcurrent short circuit detection and protection system.

In the present embodiment, the electronic schematic diagram of drive circuit unit 12 refers to Figure 15, and drive circuit unit 12 comprises: driving isolation optocoupler U1, the 16 resistance R16, the 4th triode Q4, the 5th triode Q5, the 17 resistance R17, the 18 resistance R18, the 6th diode D6, the 7th diode D7, the 8th diode D8, the first electric capacity C1, the 19 resistance R19, SiCMOSFETTd to be detected, the first driving isolation power supply malleation+VCC1 and driving isolation power supply negative pressure-VEE.

The first input end of described driving isolation optocoupler U1 is connected with described controller 11, second input end grounding of described driving isolation optocoupler U1, first output terminal of described driving isolation optocoupler U1 is connected with described driving isolation power supply malleation, second output terminal of described driving isolation optocoupler U1 is connected with described 16 resistance R16 with described SICMOSFET overcurrent short-circuit detecting circuit 15 respectively, and the 3rd output terminal of described driving isolation optocoupler U1 is connected with described driving isolation power supply negative pressure-VEE.

Second end of described 16 resistance R16 is connected with described overcurrent short-circuit protection output unit 13 with the base stage of described 4th triode Q4, the base stage of described 5th triode Q5 respectively.

The collector of described 4th triode Q4 is connected with described first driving isolation power supply malleation+VCC1, the emitter of described 4th triode Q4 is connected with the first end of described 17 resistance R17 with the emitter of described 5th triode Q5 respectively, and the collector of the 5th triode Q5 is connected with described driving isolation power supply negative pressure-VEE.

The first end of described 17 resistance R17 is connected with the negative electrode of described 6th diode D6, the anode of described 6th diode D6 is connected with the first end of described 18 resistance R18, and second end of described 18 resistance R18 is connected with second end of described 17 resistance R17.

Second end of described 17 resistance R17 is connected with the grid of described SICMOSFET to be detected with the anode of described 7th diode D7, the negative electrode of described 8th diode D8, the first end of described 19 resistance R19 respectively.

The negative electrode of described 7th diode D7 is connected with described first driving isolation power supply+VCC1 malleation, the anode of described 8th diode D8 is connected with described driving isolation power supply negative pressure-VEE, the second end ground connection of described 19 resistance R19, described first electric capacity C1 is in parallel with described 19 resistance R19, the drain electrode of described SICMOSFET to be detected is connected with described SICMOSFET overcurrent short-circuit detecting circuit 15, the source ground of described SICMOSFET to be detected.

In the present embodiment, the electronic schematic diagram of overcurrent short-circuit protection output unit 13 refers to Figure 16, overcurrent short-circuit protection output unit 13 comprises: the 9th diode D9, 20 resistance R20, 21 resistance R21, 11 resistance R11, 12 resistance R12, 13 resistance R13, 14 resistance R14, 15 resistance R15, second triode Q2, 3rd triode Q3, DQ trigger U2, 25 resistance R25, 26 resistance R26, first isolation optocoupler U3, second isolation optocoupler U4, 27 resistance R27, 28 resistance R28 and the 31 resistance R31.

The anode of described 9th diode D9 is connected with described SICMOSFET overcurrent short-circuit detecting circuit 15, the negative electrode of described 9th diode D9 is connected with the first end of described 20 resistance R20, second end of described 20 resistance R20 is connected with the CLK pin of described DQ trigger U2 with the first end of described 21 resistance R21 respectively, the second end ground connection of described 21 resistance R21.

The D pin of described DQ trigger U2 is connected with the second driving isolation power supply malleation+VCC2, described DQ trigger U2's pin is connected with the first end of described 31 resistance R31, and second end of described 31 resistance R31 is connected with described second driving isolation power supply malleation+VCC2, described DQ trigger U2's pin is connected with the described first first input end of isolating optocoupler U3, second input end of described first isolation optocoupler U3 is connected with the first end of described 25 resistance R25, and second end of described 25 resistance R25 is connected with described second driving isolation power supply malleation+VCC2.

First output terminal of described first isolation optocoupler U3 is connected with described controller 11 with the first end of described 26 resistance R26 respectively, second output head grounding of described first isolation optocoupler U3, second end of described 26 resistance R26 is connected with the 3rd driving isolation power supply malleation+VCC3, described DQ trigger U2's the first output terminal that pin isolates optocoupler U4 with the first end and described second of described 27 resistance R27 is respectively connected, second end of described 27 resistance R27 is connected with described second driving isolation power supply malleation+VCC2, second output head grounding of described second isolation optocoupler U4, second input end of described second isolation optocoupler U4 is connected with the first end of described 28 resistance R28, second end of described 28 resistance R28 is connected with described controller 11, the first input end ground connection of described second isolation optocoupler U4.

The collector of described 3rd triode Q3 is connected with described drive circuit unit 12, the base stage of described 3rd triode Q3 is connected with the first end of described 15 resistance R15, the grounded emitter of described 3rd triode Q3, second end of described 15 resistance R15 is connected with the emitter of described second triode Q2 with the first end of described 14 resistance R14 respectively, the second end ground connection of described 14 resistance R14, the collector of described second triode Q2 is connected with the first end of described 12 resistance R12, second end of described 12 resistance R12 is connected with described first driving isolation power supply malleation+VCC1, the base stage of described second triode Q2 is connected with the first end of described 13 resistance R13 with the first end of described 11 resistance R11 respectively, second end of described 11 resistance R11 is connected with the Q pin of described DQ trigger U2, the second end ground connection of described 13 resistance R13.

Wherein, the B arrow in Figure 14 represents the B input point of the B output point in Figure 16 to Figure 15.

In the present embodiment, the electronic schematic diagram of power-switching circuit 14 refers to Figure 17, and power-switching circuit 14 comprises: the 22 resistance R22, the 23 resistance R23, the 24 resistance R24, the second electric capacity C2 and controllable accurate source of stable pressure U5.

The first end of described 22 resistance R22 is connected with described first driving isolation power supply malleation+VCC1, second end of described 22 resistance R22 is connected with the negative electrode of described controllable accurate source of stable pressure U5, the plus earth of described controllable accurate source of stable pressure U5, the negative electrode of described controllable accurate source of stable pressure U5 is connected with the first end of described 23 resistance R23, second end of described 23 resistance R23 is connected with the first end of described 24 resistance R24 with the reference pole of described controllable accurate source of stable pressure U5 respectively, the second end ground connection of described 24 resistance R24, the first end of described second electric capacity C2 is connected with the first end of described 23 resistance R23 and exports described second driving isolation power supply malleation+VCC2, the second end ground connection of described second electric capacity C2.

In the present embodiment, the course of work of SICMOSFET overcurrent short circuit detection and protection system is described.Specific as follows:

Under normal circumstances, when controller 11 becomes low level from high level to the input ClearInputsignal of DQ trigger U2 (namely resetting and reset signal), DQ trigger U2's pin with pin by become complete and reset foresee steps (DQ trigger U2 logic is shown in Figure 18).Now the Q pin of DQ trigger U2 exports as low level, and the second triode Q2, the 3rd triode Q3 end, and B point voltage is not by the impact of the 3rd triode Q3, and drive circuit unit 12 normally works. pin exports as high level, and the LED cut-off of the first isolation optocoupler U3, it is high level that Tripoutputsignal (i.e. false trigger signals) signal exports to controller 11.The CLK pin monitoring C level point of DQ trigger U2, without under overcurrent or short-circuit conditions, C level point is low level, DQ trigger U2 is failure to actuate, when SICMOSFET overcurrent short-circuit detecting circuit detects overcurrent or short circuit and makes C point export high level, C point high level is through the 9th diode D9, 20 resistance R20, 21 resistance R21 voltage division processing trigger control end CLK, after control end CLK catches rapidly level rising edge, Q pin is exported and becomes high level from low level, second triode Q2, 3rd triode Q3 conducting, B point is pulled to GND1 rapidly, the 4th triode Q4 of drive circuit unit 12 is made to end like this, the drive singal of SicMOSFETTd to be detected is cut off.Pin simultaneously export and become low level from high level, Tripoutputsignal becomes low level from high level and acts on controller 11, and controller 11 turns off PWM drive singal, avoids drive circuit unit 12 the 16 resistance R16 to damage after bearing excessive power consumption for a long time.

Main time working mechanism following (as Figure 19):

In the t0 moment; controller 11 control ClearInputsignal signal becomes low level from high level; complete clearing and the reset of DQ trigger U2, the signal Tripoutputsignal signal that overcurrent short-circuit protection output unit 13 circuit exports to controller 11 maintains high level.In the t1 moment, controller 11 sends the PWM drive singal of SicMOSFETTd to be detected, signal is at t2 moment drive circuit unit 12 circuit A point and B point voltage VA after the time delay of driving isolation optocoupler U1, and VB becomes high level by low level, drives SicMOSFETTd to be detected to start open-minded.In the t3 moment, SicMOSFETTd to be detected opens complete, SICMOSFET overcurrent short-circuit detecting circuit starts to detect, because the electric current SicMOSFETCurrent of SicMOSFETTd to be detected itself does not also reach predetermined mistake flow point, it is low level that SICMOSFET overcurrent short-circuit detecting circuit exports C point voltage.Δ t1=t3-t2 is the front end blanking time of testing circuit, and within this time, SicMOSFETTd to be detected has needed to open action completely.

In the t4 moment, drive circuit unit 12 circuit A point and B point voltage VA, VB becomes low level from high level due to the impact of the signal by PWMinputsignal, SICMOSFET overcurrent short-circuit detecting circuit stops detecting, now SicMSOFETTd switch OFF to be detected, SicMOSFETCurrent starts to decline, and in the t5 moment, SicMSOFETTd to be detected turns off completely.Δ t2=t5-t4 is the rear end blanking time of SICMOSFET overcurrent short-circuit detecting circuit.

In the t6 moment, controller 11 sends the PWM drive singal of SicMOSFET, signal is at t7 moment drive circuit unit 12 circuit A point and B point voltage VA after the time delay of driving isolation optocoupler U1, and VB becomes high level by low level, drives SicMOSFETTd to be detected to start open-minded.In the t8 moment, SicMOSFETTd to be detected opens complete, and SICMOSFET overcurrent short-circuit detecting circuit starts to detect.Now SicMOSFETTd to be detected is short-circuited or over-current phenomenon avoidance, its electric current SicMOSFETCurrent rises rapidly, the maximum permission threshold current preset is exceeded in the t9 moment, SICMOSFET overcurrent short-circuit detecting circuit triggered flow short-circuit protection output unit 13 circuit, C point voltage VC becomes high level by low level, cause DQ trigger U2 action, drive circuit unit 12B point voltage VB is made to be pulled to 0 rapidly, SicMOSFETTd to be detected is turned off, its electric current SicMOSFETCurrent declines and turns off completely at t10 moment SicMOSFETTd to be detected.In the t11 moment, the signal Tripoutputsignal that overcurrent short-circuit protection output unit 13 circuit exports to controller 11 becomes low level by high level, and due to circuit impact, VC voltage keeps high level state.

In the t12 moment; controller 11 stops getting pwm signal; in the t13 moment after driving isolation optocoupler U1 time delay; drive circuit unit 12 circuit A point and B point voltage VA; VB becomes low level from high level due to the impact of the signal by PWMinputsignal; SICMOSFET overcurrent short-circuit detecting circuit stops detecting, and now VC voltage becomes low level by high level, and whole protection period terminates.

In the t14 moment; controller 11 control ClearInputsignal signal becomes high level by low level; low level is become from high level again in the t15 moment; complete clearing and the reset of DQ trigger U2; the signal Tripoutputsignal signal that overcurrent short-circuit protection output unit 13 circuit exports to controller 11 becomes high level again, and circuit normally works after t16.

It should be noted that, the A point in the present embodiment and the A point in above-described embodiment, the C point in C point and above-described embodiment, the D point in D point and above-described embodiment.

It should be noted that, each embodiment in this instructions all adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar part mutually see.For device class embodiment, due to itself and embodiment of the method basic simlarity, so description is fairly simple, relevant part illustrates see the part of embodiment of the method.

Finally, also it should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operational zone, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.

A kind of SICMOSFET overcurrent short-circuit detecting circuit above the application provided and detect protection system and be described in detail, apply specific case herein to set forth the principle of the application and embodiment, the explanation of above embodiment is just for helping method and the core concept thereof of understanding the application; Meanwhile, for one of ordinary skill in the art, according to the thought of the application, all will change in specific embodiments and applications, in sum, this description should not be construed as the restriction to the application.

Claims

1. a SICMOSFET overcurrent short-circuit detecting circuit, it is characterized in that, comprising: the first resistance, the second resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, the 29 resistance, the 30 resistance, the 3rd electric capacity, the first diode, the second diode, the 4th diode, the 5th diode, the second triode and switch diffuser part;

2. SICMOSFET overcurrent short-circuit detecting circuit according to claim 1, is characterized in that, described switch diffuser part is the first triode;

3. SICMOSFET overcurrent short-circuit detecting circuit according to claim 2, is characterized in that, also comprise: the 3rd resistance, the 4th resistance, the 5th resistance and a MOSFET;

4. SICMOSFET overcurrent short-circuit detecting circuit according to claim 1, is characterized in that, described switch diffuser part is the 3rd MOSFET;

5. SICMOSFET overcurrent short-circuit detecting circuit according to claim 4, is characterized in that, also comprise: the 33 resistance, the 34 resistance, the tenth diode and the 2nd MOSFET;

6. a SICMOSFET overcurrent short circuit detection and protection system, it is characterized in that, comprising: controller, drive circuit unit, overcurrent short-circuit protection output unit, power-switching circuit and the SICMOSFET overcurrent short-circuit detecting circuit as described in claim 1-5 any one;

7. SICMOSFET overcurrent short circuit detecting system according to claim 6, it is characterized in that, described drive circuit unit comprises: driving isolation optocoupler, the 16 resistance, the 4th triode, the 5th triode, the 17 resistance, the 18 resistance, the 6th diode, the 7th diode, the 8th diode, the first electric capacity, the 19 resistance, SiCMOSFET to be detected, the first driving isolation power supply malleation and driving isolation power supply negative pressure;

8. SICMOSFET overcurrent short circuit detecting system according to claim 6, it is characterized in that, described overcurrent short-circuit protection output unit comprises: the 9th diode, the 20 resistance, the 21 resistance, the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the second triode, the 3rd triode, DQ trigger, the 25 resistance, the 26 resistance, the first isolation optocoupler, the second isolation optocoupler, the 27 resistance, the 28 resistance and the 31 resistance;

9. SICMOSFET overcurrent short circuit detecting system according to claim 6, it is characterized in that, described power-switching circuit comprises: the 22 resistance, the 23 resistance, the 24 resistance, the second electric capacity and controllable accurate source of stable pressure;