CN1215940A

CN1215940A - Device for multi-threshold monitor and multi-slope drive protection of insulation bank tube and its control method

Info

Publication number: CN1215940A
Application number: CN 97119190
Authority: CN
Inventors: 崔扬
Original assignee: Beijing Power And Electronic New Tech Research Dev Center
Current assignee: Beijing Power And Electronic New Tech Research Dev Center
Priority date: 1997-10-28
Filing date: 1997-10-28
Publication date: 1999-05-05

Abstract

A drive protection device for insulated gate bipolar transistor (IGBT) is composed of comparators, AND gates, NPN transistors, Zener diode, diodes, resistors, capacitors, buffer, delay network, reference voltage, IGBT, positive power supply (+15V), negative power supply (-7V), input switch control signal, short-circuit alarm signal,and power bus and load outputs. It features that two reference voltage sources are used to divide the Vce-Ice curve of IGBT into three areas: normal work, over-current protection and short-circuit holding and the two protective cut-off methods: soft shutoff and lowering gate voltage are combined.

Description

The device and the control method of multi-threshold monitor, many slope drive protection insulation bank tube

The present invention relates to a kind of by comparator 3,20; with door 4,21; NPN transistor 5,23; Zener diode 6;

diode

10,12,14;

resistance

9,11,13,16,17,18,22;

electric capacity

15,19,24, buffer 8, time delay network 1,

reference voltage

2,29, igbt (IGBT) 7; and positive supply (+15) 30; and negative supply (7) 31, input switch control signal 25, short-circuit alarming output signal 26; power generatrix or load output 28, (IGBT) 7 Drive Protecting Circuit devices that load or power generatrix output 27 connect to form.It is suitable for driving various (IGBT) 7 and works under the on off state; monitoring to (IGBT) 7 working conditions is provided simultaneously; when overcurrent or short circuit appear in (IGBT) 7 under the conducting situation; this device is taked corresponding protection immediately; to prevent that (IGBT) 7 from burning, send alarm signal to main system simultaneously.It is safe and reliable that this invention has the method that monitoring is accurate, antijamming capability is strong, protection driving response is rapid and turn-off (IGBT) 7; this device circuit is simple; (IGBT) 7 products that different manufacturers is produced all can provide effective driving protection; and can be assembled into intelligent object with (IGBT) 7, be widely used.

Existing driving protection monitoring technology is: obtain monitoring voltage signal (perhaps obtaining signal from the conducting electric current of IGBT7) from the Vce (collector emitter voltage) of (IGBT) 7, compare with a fiducial value that pre-sets.If in (IGBT) 7 turn-on cycles, the Vce voltage (the perhaps conducting current signal of (IGBT) 7) that monitors (IGBT) 7 surpasses this fiducial value that pre-sets, and then begins to take protection to drive, and prevents that (IGBT) 7 from burning.Its shortcoming that unity reference value only is set in advance is: in fact do not have so reasonable fiducial value point, single fiducial value point only is set, resolution is low, error is big, promptly can not effectively utilize the anti-overcurrent service area of (IGBT) 7, can not satisfy the discreteness of (IGBT) 7 characteristics, and be easy to be interfered, misoperation appears.Existing protection drives to turn-off to be had soft shutoff again respectively and falls two kinds of methods such as grid voltage.Soft turn-off protection can not produce big dI/dt (current time ratio), but drives conducting from positive voltage, is converted to negative voltage driving by soft shutoff and turn-offs, and its process is long, and response speed is slow, and (IGBT) 7 protected fast; Require the time of overcurrent is counted and fall the grid voltage driving, its time is difficult to choose at different overcurrent conditions, and circuit is tending towards the complicated realization that is difficult for.

The objective of the invention is: a kind of multi-threshold monitor is provided, the device of many slope drive protection (IGBT) 7, it simple in structure, and can provide the method for a kind of more reasonable accurate monitoring (IGBT) 7 operating currents, this method promptly can be utilized the anti-overcurrent service area of (IGBT) 7 fully, can prevent from again to disturb to cause misoperation; Provide a kind of shutoff to drive guard method, speed is fast, can turn-off (IGBT) 7 safely.

Task of the present invention is finished as follows.Among Fig. 1, a kind of by comparator 3, comparator 20, with door 4 and with door 21, NPN transistor 5,23, Zener diode 6,

diode

10,12,14,

resistance

9,11,13,16,17,18,22,

electric capacity

15,19,24, buffer 8, time delay network 1,

reference voltage

2,29, igbt (IGBT) 7, and positive supply (+15V) 30, and negative supply (7V) 31, input switch control signal 25, short-circuit alarming output signal 26, power generatrix or load output 28, the multi-threshold monitor that load or power generatrix output 27 connect to form, many slope drive are protected the device of (IGBT) 7 and the control method of realization thereof, it is characterized in that sending into from the switch controlling signal 25 of system an end of resistance 9, and the other end of resistance 9 connects the input of buffer 8,1 end of the anode of diode 14 and Zener diode 6 negative electrodes and time delay network 1; Buffer 8 has the voltage follow characteristic, and its output connects the grid of (IGBT) 7, provides gate driving control voltage Vgs to (IGBT) 7; Power supply (+15) 30 and power supply (7) 31 are to buffer 8 power supply, and the Vgs amplitude of oscillation that makes buffer 8 outputs is at+15 volts extremely between-7; Diode 10 is connected collector electrode and power generatrix or the load output 28 of (IGBT) 7 with the negative electrode of diode 12; The anode of diode 10 connects an end of resistance 11, the other end of resistance 11 connects in-phase input end, resistance 16 and the electric capacity 15 of comparator 3, the anode of diode 12 connects resistance 13, and the other end of resistance 13 connects in-phase input end, resistance 18 and the electric capacity 19 of comparator 20; The inverting input of comparator 3 connects the positive pole of reference voltage source 2, and the output of comparator 3 connects input 1 pin with door 4; Comparator 20 inverting inputs connect the positive pole of reference voltage source 29, and comparator 20 outputs connect input 1 pin with door 21; 2 ends that are connected time delay network 1 with 2 pin of door 4,21; The base stage that is connected transistor 5 with the output of door 4; The base stage that is connected transistor 23 with the output of door 21 simultaneously as alarm output signal 26, is used for sending the short-circuit alarming signal to system; The collector electrode of transistor 5 connects the anode of Zener diode 6, and the collector electrode of transistor 23 connects resistance 22, and the other end of resistance 22 connects resistance 17 and electric capacity 24; The emitter of transistor 5 and (IGBT) 7 emitter, load or power generatrix output 27 and

electric capacity

15,19,24, the negative pole of

reference voltage source

2,29 connects earth potential, and an end of the emitter of transistor 23 and electric capacity 24 is connected negative supply (7) 31.

Control method of the present invention; it is characterized in that setting the overcurrent condition that two or more fiducial values (being reference voltage) are monitored (IGBT) 7; the A of Fig. 2 is existing method to set up; (IGBT) 7 Vce-Ice curve is divided into two zones by a monitoring criteria voltage Vref: (1) operate as normal district and (2) short-circuit protection district; in the B of Fig. 2; embodiments of the invention use reference voltage 2 (its fiducial value Vref1) and reference voltage 29 (its fiducial value is Vref2), wherein

vref1＜Vref2

Two reference voltage monitoring points become three zones with the Vce-Ice curve segmentation of (IGBT) 7: the operate as normal district, and overcurrent protection district and short-circuit protection district are multi-threshold monitor; Control method of the present invention; it is characterized in that; with soft shutoff with fall two kinds of gate driving turn-off protections of grid voltage method and be combined into the gate driving turn-off protection method (in each zone be different to the variation slope of time to the voltage of the gate driving of IGBT7 protection voltage Vgs) of the many slopes of a cover; compare according to the overcurrent condition of (IG-BT) 7 that monitors and two or more reference voltages of setting; Automatic Combined goes out gate driving turn-off protection voltage slope curve; make the present invention provide monitoring more accurately to (IGBT) 7 in the work; avoid interference; and can provide the turn-off protection of gate driving fast and safely; avoid burning (IGBT) 7, solved the shortcoming that prior art exists.

Operation principle of the present invention (with the embodiment explanation) is in accompanying drawing 1, input switch control signal 25 from system, its pulse amplitude is+15 volts～-7 volts, process resistance 9 enters the input of buffer 8, provides Vgs to come the grid of drive controlling (IG-BT) 7 by buffer 8 outputs with voltage follow;

Between the off period of switching signal, input switch control signal 25 is a low level-7 volt, enter the input of buffer 8 through resistance 9, the voltage Vgs of output drive controlling (IGBT) 7 grids of buffer 8 is-7 volts, (IGBT) 7 enter cut-off state, simultaneously through time delay network 1 enter two with 4 and 21 2 pin, make two 4,21 to be blocked output low level with door, transistor 5 and 23 remain offs, neat diode 6 ends, diode 14 ends, and the voltage at electric capacity 24 two ends charges to high level through resistance 17;

15-(-7)=22V；

In the conduction period of switching signal, input switch control signal 25 is high level+15 volt, enter the input of buffer 8 through resistance 9, the voltage Vgs of output drive controlling (IGBT) 7 grids of buffer 8 is+15 volts, (IGBT) 7 enter conducting state, latter two is disengaged blockade with door 4 and 21 through the time-delay of time delay network 1, (IGBT) 7 enters degree of depth saturation conduction state fully at this moment, diode 10 and diode 12 are obtained voltage signal from the collector electrode of (IGBT) 7, pass through resistance 11 respectively, 13 deliver to two comparators 3,20 end of oppisite phase, two comparators 3,20 end of oppisite phase connects two reference voltage sources 2 respectively, 29 positive pole, the fiducial value of reference voltage source 2 is Vref1, the fiducial value of reference voltage source 29 is Vref2, and their value of setting is:

Vref1=4.5V～6.5V,

Vref2=7.5V～8.5V, when (IGBT) 7 conducting electric currents just often, (IGBT) 7 Vce voltage is lower than 3.5 volts, promptly

Vce＜Vref1＜Vref2, two comparator 3,20 equal output low levels, two transistors 5 and 23 all end, and Zener diode 6 ends, and diode 14 ends, and (IGBT) 7 drive control voltage Vgs is+15 volts;

In switching signal conduction period, if at a time t1 is owing to certain extraneous reason makes (IGBT) the 7 conducting electric currents in the work increase, the Vce voltage of (IGBT) 7 also can increase thereupon simultaneously, as accompanying drawing 3 (a), two comparators 3, the input terminal voltage of 20 in-phase end also can increase thereupon, when this variation makes comparator 3 reach turn threshold Vref1 and comparator 20 when not reaching turn threshold Vref2 as yet, transistor 5 conductings are also saturated, transistor 23 is still kept and is ended, Zener diode 6 conductings, this moment, resistance 9 provided operating current for Zener diode 6, the input of buffer 8 is clamped at Vz1+Vces1, wherein Vz1 is the voltage stabilizing working value of Zener diode Z1, and Vces1 is the saturation voltage drop of transistor 5;

Vz1=8～12V

Thereby Vces1≤0.3V (IGBT) 7 drive control voltage Vga also from the driven level+15 volts of Vz1+Vces1 that descend and be clamped near owing to fall the effect of grid voltage, (IGBT) 7 entered anti-overcurrent operating state; If producing the outside cause of overcurrent disappears automatically at moment t2, (IGBT) 7 Vce voltage descends again and returns to below the normal saturation voltage value, as accompanying drawing 3 (a), at this moment comparator 3 output low level again, transistor 5 and Zener diode 6 end, the input of buffer 8 returns to high level+15 volt, thereby (IGBT) 7 drive control voltage Vgs also returns to+15 volts of driving outputs, whole grid voltage is fallen and during, (IGBT) 7 is still in running order, whole system work is unaffected, and resistance 16 and electric capacity 15 can filter out narrow peak voltage to be changed.From t1 overcurrent condition generation constantly, Vgs is to the variation slope of time, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level rapidly) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent operating state, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big di/dt, can not make (IGBT) 7 withdraw from the operate in saturation district again; Zero slope variation (being clamped at the Vz1+Vces1 level) stage; Skyrocket (from the Vz1+Vces1 level be raised to rapidly+15 volts) stage, recover the driven state.

Because the value of setting of Vref1 is lower than the value that a benchmark monitoring point only is set in the past, (IGBT) 7 are beginning to fall grid voltage under slight overcurrent condition, thus its anti-overcurrent operating time tolerance prolong greatly, so do not need timing circuit to interrupt whole system;

If at a time certain outside cause of t1 increases (IGBT) 7 conducting electric currents, short-circuit conditions appears, when this variation increases the Vce voltage of (IGBT) 7 and has surpassed comparator 20 turn threshold Vref2, as accompanying drawing 3 (b), but because the time constant of resistance 18 and electric capacity 19 is greater than the time constant by resistance 16 and electric capacity 15, so remain comparator 3 upset earlier, transistor 5 at first enters saturation conduction, transistor 23 remain offs of this moment, circuit still repeats the above-mentioned grid voltage process of falling, if the duration of short-circuit conditions is enough short, when the voltage of electric capacity 19 is not charged to the turn threshold Vref2 of comparator 20 as yet, at a time the t2 short-circuit conditions just is through with, then circuit still repeats above-mentioned process and finishes to fall grid voltage, the input of buffer 8 returns to high level+15, thus (IG-BT) 7 drive control voltage Vgs also returns to normally+15 volts of driving outputs.From f1 short-circuit conditions generation constantly, Vgs is to the variation slope of time, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level rapidly) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent operating state, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big di/dt, can not make (IGBT) 7 withdraw from the operate in saturation district again; Zero slope variation (being clamped at the Vz1+Vcea1 level) stage; Skyrocket (from the Vz1+Vces1 level be raised to rapidly+15 volts) stage, recover the driven state.Whole grid voltage is fallen and during, (IGBT) 7 is still in running order, whole system work is unaffected, as accompanying drawing 3 (b);

If at a time certain outside cause of t1 increases (IGBT) 7 conducting electric currents, short-circuit conditions appears, when this variation increases the Vce voltage of (IGBT) 7 and surpasses the turn threshold Vref2 of comparator 20, as accompanying drawing 3 (c), but because the time constant of resistance 18 and electric capacity 19 is greater than the time constant by resistance 16 and electric capacity 15, so remain comparator 3 upset earlier, transistor 5 at first enters saturated and conducting, transistor 23 remain offs of this moment, circuit still repeats the above-mentioned grid voltage process of falling, if the duration of short-circuit conditions surpasses the time constant of being set by resistance 18 and electric capacity 19, the voltage of electric capacity 19 at a time is charged to behind the t2 and when surpassing the turn threshold Vref2 of comparator 20, short-circuit conditions does not still disappear, as accompanying drawing 3 (c), also overturn at t2 moment comparator 20, short-circuit alarming output signal 26 is sent to system and is interrupted instrument number, while transistor 23 saturation conductions, the collector potential of transistor 23 descends near the level of negative supply (7) 31, diode 14 forward conductions, conducting voltage is 0.7 volt, the input current potential of buffer 8 is from being clamped at the level of Vz1+Vces1, beginning descends with diode 14 negative electrode level, because resistance 22 and electric capacity 24 are formed the effect of discharge time delay network, make this decline have the software switching-off characteristic, because soft shutoff is from beginning than+15 volts of much lower Vz1+Vces1 level, so response speed is fast, because the change in voltage slope ratio of soft off-phases Vgs is less, when opening threshold point through (IGBT) 7, can not make (IGBT) 7 produce big di/dt, can turn-off (IGBT) 7 safely in time, make it avoid burning.Vgs is to the variation slope of time, from t1 short-circuit conditions generation constantly, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent working condition, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big dl/dt, can not make (IGBT) 7 withdraw from the operate in saturation district again; In zero slope variation (being clamped at the Vz1+Vces1 level) stage, prevent narrow pulse interference; And t2 three slope variation of soft off-phases after the moment.

Below in conjunction with accompanying drawing the present invention is further described;

Fig. 1 is an electrical schematic diagram of the present invention;

Fig. 2 is the Vce-Ice performance diagram of igbt (IGBT) 7;

Fig. 3 is the monitoring driving control curve synoptic diagram of (IGBT) 7.

With reference to Fig. 1, a kind of by comparator 3, comparator 20, with door 4,21, NPN transistor 5,23, Zener diode 6,

diode

10,12,14,

resistance

9,11,13,16,17,18,22,

electric capacity

15,19,24, buffer 8, time delay network 1,

reference voltage

2,29, igbt (IGBT) 7, and positive supply (+15) 30 and negative supply (7) 31, input switch control signal 25, short-circuit alarming output signal 26, power generatrix or load output 28, the multi-threshold monitor that load or power generatrix output 27 connect to form, the device of many slope drive protection (IGBT) 7 and the control method of realization thereof, it is characterized in that sending into from the switch controlling signal 25 of system an end of resistance 9, the other end of resistance 9 connects the input of buffer 8,1 end of the anode of diode 14 and Zener diode 6 negative electrodes and time delay network 1; Buffer 8 has the voltage follow characteristic, and its output connects the grid of (IGBT) 7, provides gate driving control voltage Vgs to (IGBT) 7; Power supply (+15) 30 and power supply (7) 31 are to buffer 8 power supply, and the Vgs amplitude of oscillation that makes buffer 8 outputs is at+15 volts extremely between-7; The anode of diode 10 is connected (IGBT) 7 with the negative electrode of diode 12 collector electrode and power generatrix or load input terminal 28, diode 10 is connected resistance 11, and the other end of resistance 11 connects in-phase input end, resistance 16 and the electric capacity 15 of comparator 3; The anode of diode 12 connects resistance 13, and the other end of resistance 13 connects in-phase input end, resistance 18 and the electric capacity 19 of comparator 20; The inverting input of comparator 3 connects the positive pole of reference voltage source 2, and the output of comparator 3 connects input 1 pin with door 4; Comparator 20 inverting inputs connect the positive pole of reference voltage source 29, and comparator 20 outputs connect input 1 pin with door 21; 2 ends that are connected time delay network 1 with 2 pin of door 4,21; The base stage that is connected transistor 5 with the output of door 4; The base stage that is connected transistor 23 with the output of door 21 simultaneously as alarm output signal 26, is used for sending the short-circuit alarming signal to system; The collector electrode of transistor 5 connects the anode of Zener diode 6; The collector electrode of transistor 23 connects resistance 22, and the other end of resistance 22 connects resistance 17 and electric capacity 24; The emitter of transistor 5 and (IGBT) 7 emitter, load or power generatrix output 27 and

electric capacity

15,19,24, the negative pole of

reference voltage source

With reference to Fig. 2; the A of Fig. 2 is the Vce method to set up of existing monitoring (IGBT) 7; (IGBT) 7 Vce-Ice curve is divided into two zones by a monitoring criteria voltage Vref: (1) operate as normal district and (2) short-circuit protection district; in the B of Fig. 2; embodiments of the invention use reference voltage 2 (its fiducial value is Vref1) and reference voltage 29 (its fiducial value is Vref2), wherein

Vref1＜Vref2

Two reference voltage monitoring points become three zones with the Vce-Ice curve segmentation of (IGBT) 7: operate as normal district, overcurrent protection district and short-circuit protection district are multi-threshold monitor.

With reference to Fig. 3, Fig. 3 (a) is the conduction period in switching signal, if at a time t1 is owing to certain extraneous reason makes (IGBT) the 7 conducting electric currents in the work increase, the Vce voltage of (IGBT) 7 also can increase thereupon simultaneously, two comparators 3, the input terminal voltage of 20 in-phase end also can increase thereupon, when this variation makes comparator 3 reach turn threshold Vref1 and comparator 20 when not reaching turn threshold Vref2 as yet, transistor 5 conductings are also saturated, transistor 23 is still kept and is ended, Zener diode 6 conductings, this moment, resistance 9 provided operating current for Zener diode 6, the input of buffer 8 is clamped at Vz1+Vces1, wherein Vz1 is the voltage stabilizing working value of Zener diode 6, and Vces1 is the saturation voltage drop of transistor 5:

Vz1=8-12V；

Vces1≤0.3V

Thereby (IGBT) 7 drive control voltage Vgs also from the driven level+15 volts of Vz1+Vces1 that descend and be clamped near owing to fall the effect of grid voltage, (IGBT) 7 entered anti-overcurrent operating state; If producing the outside cause of overcurrent has disappeared automatically at moment t2, (IGBT) 7 Vce voltage is returned to below the normal saturation voltage value by decline, at this moment comparator 3 output low level again, transistor 5 and Zener diode 6 end, the input of buffer 8 returns to high level+15 volt, thereby (IGBT) 7 drive control voltage Vgs also returns to+15 volts of driving outputs, whole grid voltage is fallen and during, (IGBT) 7 is still in running order, whole system work is unaffected, and resistance 16 and electric capacity 15 can filter out narrow peak voltage to be changed.From t1 overcurrent condition generation constantly, Vgs is to the variation slope of time, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level rapidly) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent operating state, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big dI/dt, can not make (IGBT) 7 withdraw from the operate in saturation district again; Zero slope variation (being clamped at the Vz1+Vces1 level) stage; Skyrocket (from the Vz1+Vces1 level be raised to rapidly+15 volts) stage, recover the driven state.

Fig. 3 (b), increase if at a time certain outside cause of t1 makes (IGBT) 7 seek galvanization, short-circuit conditions appears, when this variation increases the Vce voltage of (IGBT) 7 and surpasses the turn threshold Vref2 of comparator 20, but because the time constant of resistance 18 and electric capacity 19 is greater than the time constant by resistance 16 and electric capacity 15, so remain comparator 3 upset earlier, transistor 5 at first enters saturation conduction, transistor 23 remain offs of this moment, circuit still repeats the above-mentioned grid voltage process of falling, if the duration of short-circuit conditions is enough short, when the voltage of electric capacity 19 is not charged to the turn threshold Vref2 of comparator 20 as yet, at a time the t2 short-circuit conditions just is through with, then circuit still repeats above-mentioned process and finishes to fall grid voltage, the input of buffer 8 returns to high level+15 volt, thus (IGBT) 7 drive control voltage Vgs also returns to normally+15 volts drive output.From t1 short-circuit conditions generation constantly, Vgs is to the variation slope of time, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level rapidly) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent operating state, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big dI/dt, can not make (IGBT) 7 withdraw from the operate in saturation district again; Zero slope variation (being clamped at the Vz1+Vces1 level) stage; Skyrocket (from the Vz1+Vces1 level be raised to rapidly+15 volts) stage, recover the driven state.Whole grid voltage is fallen and during, (IGBT) 7 is still in running order, whole system work is unaffected.

Fig. 3 (c) is, if at a time certain outside cause of t1 increases (IGBT) 7 conducting electric currents, short-circuit conditions appears, when this variation increases the Vce voltage of (IGBT) 7 and surpasses the turn threshold Vref2 of comparator 20, but because the time constant of resistance 18 and electric capacity 19 is greater than the time constant by resistance 16 and electric capacity 15, so remain comparator 3 upset earlier, transistor 5 at first enters saturation conduction, transistor 23 remain offs of this moment, circuit still repeats the above-mentioned grid voltage process of falling, if the duration of short-circuit conditions surpasses the time constant of being set by resistance 18 and electric capacity 19, the voltage of electric capacity 19 at a time is charged to behind the t2 and when surpassing the turn threshold Vref2 of comparator 20, short-circuit conditions does not still disappear, also overturn at t2 moment comparator 20, short-circuit alarming output signal 26 is sent interrupt signal to system, while transistor 23 saturation conductions, the collector potential of transistor 23 descends near the level of negative supply (7) 31, diode 14 forward conductions, conducting voltage is 0.7 volt, the input current potential of buffer 8 is from being clamped at the level of Vz1+Vces1, beginning descends with diode 14 negative electrode level, because resistance 22 and electric capacity 24 are formed the effect of discharge time delay network, make this decline have soft turn-off characteristic, because soft shutoff is from beginning than+15 volts of much lower Vz1+Vces1 level, so response speed is fast, because the change in voltage slope ratio of soft off-phases Vgs is less, when opening threshold point through (IGBT) 7, can not make (IGBT) 7 produce big dI/dt, can turn-off (IGBT) 7 safely in time, make it avoid burning.Vgs is to the variation slope of time, from t1 short-circuit conditions generation constantly, experienced suddenly and fallen (the dropping to the Vz1+Vces1 level) stage from+15 volts, make (IGBT) 7 enter anti-overcurrent operating state, because the Vz1+Vces1 level is far above the unlatching threshold point of (IGBT) 7, so promptly can not produce big dI/dt, can not make IGBT7 withdraw from the operate in saturation district again; In zero slope variation (being clamped at the Vz1+Vces1 level) stage, prevent narrow pulse interference; And t2 three slope variation of soft off-phases after the moment.

Claims

1, a kind of by comparator 3, comparator 20, with door 4,21, NPN transistor 5,23, Zener diode 6, diode 10,12,14, resistance 9,11,13,16,17,18,22, electric capacity 15,19,24, buffer 8, time delay network 1, reference voltage 2,29, igbt (IGBT) 7, and positive supply (+15) 30, and negative supply (7) 31, input switch control signal 25, short-circuit alarming output signal 26, power generatrix or load output 28, the multi-threshold monitor that load or power generatrix output 27 connect to form, the device of many slope drive protection (IGBT) 7 and the control method of realization thereof, it is characterized in that sending into from the switch controlling signal 25 of system an end of resistance 9, the other end of resistance 9 connects the input of buffer 8,1 end of the anode of diode 14 and Zener diode 6 negative electrodes and time delay network 1; Buffer 8 has the voltage follow characteristic, and its output connects the grid of (IGBT) 7, provides gate driving control voltage Vgs to (IGBT) 7; Power supply (+15) 30 and power supply (7) 31 are to buffer 8 power supply, and the Vgs amplitude of oscillation that makes buffer 8 outputs is at+15 volts extremely between-7; Diode 10 is connected collector electrode and power generatrix or the load output 28 of (IGBT) 7 with the negative electrode of diode 12; The anode of diode 10 connects the in-phase input end of the other end connection comparator 3 of resistance 11, resistance 11, resistance 16 and electric capacity 15; The anode of diode 12 connects resistance 13, and the other end of resistance 13 connects in-phase input end, resistance 18 and the electric capacity 19 of comparator 20; The inverting input of comparator 3 connects the positive pole of reference voltage source 2, and the output of comparator 3 connects input 1 pin with door 4; Comparator 20 inverting inputs connect the positive pole of reference voltage source 29, and comparator 20 outputs connect input 1 pin with door 21; 2 ends that are connected time delay network 1 with 2 pin of door 4,21; The base stage that is connected transistor 5 with the output of door 4; The base stage that is connected transistor 23 with the output of door 21 simultaneously as alarm output signal 26, is used for sending the short-circuit alarming signal to system; The collector electrode of transistor 5 connects the anode of Zener diode 6; The collector electrode of transistor 23 connects resistance 22, and the other end of resistance 22 connects resistance 17 and electric capacity 24; The emitter of transistor 5 and (IGBT) 7 emitter, load or power generatrix output 27 and electric capacity 15,19,24, the negative pole of reference voltage source 2,29 connects earth potential, and an end of the emitter of transistor 23 and electric capacity 24 is connected negative supply (7) 31.

2, control method of the present invention, it is characterized in that setting the overcurrent condition that two or more fiducial values (being reference voltage) are monitored (IGBT) 7, in embodiments of the present invention, use two reference voltage monitoring points that the Vce-Ice curve segmentation of (IGBT) 7 is become three zones: operate as normal district, overcurrent protection district and short-circuit protection district are multi-threshold monitor;

3, according to claim 1 and claim 2; it is characterized in that soft shutoff and the gate driving protection cut-off method that falls two kinds of (IGBT) 7 of grid voltage are combined into the gate driving protection cut-off method of (IGBT) 7 of the many slopes of a cover; compare according to the overcurrent condition of (IGBT) 7 that monitors and the reference voltage source of setting; Automatic Combined goes out the gate driving protection shutoff voltage slope curve of (IGBT) 7, is many slope drive protections.