CN112468124B

CN112468124B - IGBT driving device and IGBT

Info

Publication number: CN112468124B
Application number: CN202011229564.4A
Authority: CN
Inventors: 刘旭龙; 谭章德; 郑培杰; 李通; 张敏
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2022-02-01
Anticipated expiration: 2040-11-06
Also published as: CN112468124A

Abstract

The invention discloses a driving device of an IGBT and the IGBT, the device comprises: the comparison unit is used for comparing the magnitude relation between the collector voltage of the IGBT and the set voltage under the condition that the IGBT is electrified and operated to obtain a comparison result; the number of the set voltages is more than two; the selection unit selects the gate voltage of the IGBT according to the comparison result of the magnitude relation between the collector voltage of the IGBT and the set voltage so as to adjust the gate voltage of the IGBT according to the collector voltage of the IGBT; and the driving unit is used for driving the IGBT according to the selected grid voltage of the IGBT. According to the scheme, when the voltage of the IGBT collector rises, the switching time of the IGBT is prolonged by reducing the driving voltage of the IGBT grid electrode, so that the IGBT has better safety performance when the IGBT breaks down.

Description

IGBT driving device and IGBT

Technical Field

The invention belongs to the technical field of electronic circuits, particularly relates to an IGBT driving device and an IGBT, and particularly relates to an IGBT grid voltage self-adjusting driving circuit and an IGBT with the driving circuit.

Background

IGBT (Insulated Gate Bipolar Transistor) modules have been used in a variety of fields such as machine tools, electric vehicles, photovoltaic power generation, and the like. The IGBT of the novel power switching device has the advantages of a power triode and a field effect transistor, namely, strong through-current capacity, high switching frequency, large input resistance, low saturation voltage and the like, so that the IGBT is more and more widely applied to industrial control.

The drive circuit of the IGBT is an interface between the main circuit and the control circuit. The design of the drive circuit of the IGBT determines whether the performance of the element can be fully exhibited.

In the related scheme, when the IGBT fails, the IGBT needs to be turned off, but the turn-off time of the IGBT is short, and a large di/dt is generated, and because parasitic inductance exists in a driving circuit of the IGBT, a large voltage spike is generated in the turn-off process of the IGBT, and the voltage may exceed the withstand voltage value of the IGBT, so that the IGBT is damaged.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide an IGBT driving device and an IGBT, and aims to solve the problem that when the IGBT fails, the IGBT is burnt out by surge voltage generated when the IGBT is turned off under the condition that collector current of the IGBT flows greatly, and achieve the effect that when the voltage of the IGBT collector rises, the switching time of the IGBT is increased by reducing the drive voltage of the IGBT grid electrode, so that the IGBT has better safety performance when the IGBT fails.

The present invention provides a driving device of an IGBT, comprising: the device comprises a comparison unit, a selection unit and a driving unit; the comparison unit is configured to compare the magnitude relation between the collector voltage of the IGBT and a set voltage under the condition that the IGBT is powered on and operated, and obtain a comparison result; the number of the set voltages is more than two; the selection unit is configured to select the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage so as to adjust the gate voltage of the IGBT according to the collector voltage of the IGBT; the driving unit is configured to drive the IGBT according to the selected grid voltage of the IGBT.

In some embodiments, two or more of the set voltages include: a first set voltage and a second set voltage.

In some embodiments, in the case where two or more of the setting voltages are a first setting voltage and a second setting voltage: the comparison unit compares the magnitude relation between the collector voltage of the IGBT and the set voltage, and comprises: comparing a magnitude relationship between a collector voltage of the IGBT and the first and second set voltages; the selection unit selects the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage, and comprises: if the collector voltage of the IGBT is smaller than the first set voltage, the grid voltage of the IGBT is the maximum value of the set driving voltage; if the collector voltage of the IGBT is greater than or equal to the first set voltage and less than the second set voltage, the gate voltage of the IGBT is reduced to a first set threshold value from the maximum value of the set driving voltage; and if the collector voltage of the IGBT is greater than or equal to the second set voltage, the grid voltage of the IGBT is reduced from a first set threshold value to a second set threshold value.

In some embodiments, the comparison unit includes: the charging circuit comprises a first comparison module, a second comparison module, a first current limiting module, a second current limiting module, a first charging module, a second charging module, a first switching tube module and a fifth switching tube module; the direct current power supply is connected to the selection unit after passing through the first current source, is connected to the inverting input end of the second comparison module, is grounded after passing through the second charging module, and is connected to the collector of the IGBT after passing through the second current limiting module; the non-inverting input end of the second comparison module is connected with a second reference source, and the output end of the second comparison module is connected to the base electrode of the fifth switching tube module; an emitter of the fifth switching tube module is connected to a common end of the second current source and the first current limiting module, and a collector of the fifth switching tube module is connected to the selection unit; the direct current power supply is connected to the inverting input end of the first comparison module after passing through the second current source, is grounded after passing through the first charging module, and is connected to the collector electrode of the IGBT after passing through the first current limiting module; the non-inverting input end of the first comparison module is connected with a first reference source, and the output end of the first comparison module is connected with the base electrode of the first switch tube module; the emitter of the first switch tube module is connected with a power supply, and the collector of the first switch tube module is connected to the selection unit.

In some embodiments, the first charging module comprises: a first capacitor; the second charging module includes: a second capacitor; the first current limiting module includes: the anode of the first diode is connected to the fifth current-limiting resistor, and the cathode of the first diode is connected to the collector of the IGBT; the second current limiting module comprising: the IGBT driving circuit comprises a sixth current-limiting resistor, a second diode and a voltage-regulator tube, wherein the anode of the second diode is connected to the sixth current-limiting resistor, the cathode of the second diode is connected to the anode of the voltage-regulator tube, and the cathode of the voltage-regulator tube is connected to the collector of the IGBT.

In some embodiments, the selection unit includes: the second switch tube module, the third switch tube module and the fourth switch tube module; the collector of the first switch tube module is connected to the base of the second switch tube module, the collector of the second switch tube module is connected to a grid voltage source, and the emitter of the second switch tube module is connected to the driving unit; a collector of the fifth switching tube module is connected to a base of the third switching tube module, a collector of the third switching tube module is connected to a grid voltage source, and an emitter of the third switching tube module is connected to the driving unit; the first current source is connected to the base of the fourth switching tube module, the collector of the fourth switching tube module is connected to the grid voltage source, and the emitter of the fourth switching tube module is connected to the driving unit.

In some embodiments, further comprising: the first current limiting module, the second voltage dividing module, the third voltage dividing module and the fourth voltage dividing module; the collector of the first switch tube module is connected to the base of the second switch tube module after passing through the first current limiting module; the collector electrode of the third switching tube module is connected to a grid voltage source after passing through the second voltage division module; and the collector electrode of the fourth switching tube module is connected to a grid voltage source after passing through the third voltage division module and is also connected to a negative grid voltage source after passing through the fourth voltage division module.

In some embodiments, the driving unit includes: the optical coupling module, the sixth switching tube module, the seventh switching tube module and the grid resistor are connected with the grid resistor; the base electrode of the sixth switching tube module is connected to the output end of the optical coupling module; the collector of the sixth switching tube module is respectively connected to the emitter of the second switching tube module, the emitter of the third switching tube module and the emitter of the fourth switching tube module; the emitter of the sixth switching tube module is connected to the grid of the IGBT after passing through the grid resistor and is also connected to the collector of the seventh switching tube module; and the emitter of the seventh switching tube module is connected with another negative grid voltage source.

In accordance with the above apparatus, another aspect of the present invention provides an IGBT including: the above-described IGBT driving device.

Therefore, according to the scheme of the invention, the gate driving voltage is correspondingly adjusted according to the change of the collector voltage when the IGBT operates, so that the switching time of the IGBT is changed, and the IGBT can be in a relatively safe working state when the collector voltage is increased; therefore, when the voltage of the IGBT collector rises, the switching time of the IGBT is prolonged by reducing the driving voltage of the IGBT gate, so that the IGBT has better safety performance when in failure.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of a driving device of an IGBT according to the present invention;

FIG. 2 is a schematic flow chart of the whole IGBT along with the adjustment of collector voltage;

FIG. 3 is a diagram illustrating variation of gate voltage parameters;

FIG. 4 is a schematic diagram of a collector voltage adjustment process of an embodiment of an IGBT driving circuit;

FIG. 5 is a schematic structural diagram of an embodiment of an IGBT driving circuit;

fig. 6 is a schematic structural diagram of another embodiment of the IGBT driving circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an embodiment of the present invention, there is provided a driving apparatus of an IGBT. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The driving device of the IGBT may include: the device comprises a comparison unit, a selection unit and a driving unit.

The comparison unit is configured to compare the magnitude relation between the collector voltage of the IGBT and a set voltage under the condition that the IGBT is powered on and operated, and obtain a comparison result; the number of the set voltage is more than two.

The selection unit is configured to select the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage, so as to adjust the gate voltage of the IGBT according to the collector voltage of the IGBT.

The driving unit is configured to drive the IGBT according to the selected grid voltage of the IGBT.

From this, make corresponding adjustment to gate drive voltage through the change according to collector voltage when the IGBT operation, and then change IGBT's on-off time for the IGBT can be in a relatively safe operating condition when collector voltage risees, thereby can make corresponding adjustment to collector voltage's change, with the drive performance who improves the IGBT.

Specifically, a circuit adjustment flowchart may be provided in which only 2 thresholds a, b are set, and the gate driving circuit is constantly adjusting as long as the IGBT does not trigger protection.

Of course, the critical voltage and the divider resistance can be expanded to 3, 4 or even more according to actual conditions. a is a gate voltage first threshold value, b is a gate voltage second threshold value, and a gate voltage third threshold value c and an nth threshold value z … … may be set according to actual conditions, where n is a natural number. It requires Vss > a > b > c > … … > z. If a plurality of thresholds a, b, c, d … … are set, the corresponding thresholds should be set as V1, V2 and V3 … ….

In some embodiments, in the case that two or more of the setting voltages are the first setting voltage and the second setting voltage, for example, the first setting voltage is the voltage V1, and the second setting voltage is the voltage V1+ VD3, the specific working conditions of the comparing unit and the selecting unit can be referred to the following exemplary description.

The comparison unit compares the magnitude relation between the collector voltage of the IGBT and the set voltage, and comprises: comparing a magnitude relationship between a collector voltage of the IGBT and the first and second set voltages.

The selection unit selects the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage, and comprises: if the collector voltage of the IGBT is smaller than the first set voltage, the grid voltage of the IGBT is the maximum value of the set driving voltage; if the collector voltage of the IGBT is greater than or equal to the first set voltage and less than the second set voltage, the gate voltage of the IGBT is reduced to a first set threshold value from the maximum value of the set driving voltage; and if the collector voltage of the IGBT is greater than or equal to the second set voltage, the grid voltage of the IGBT is reduced from a first set threshold value to a second set threshold value.

Specifically, the IGBT drive voltage operates at a maximum value Vss of the drive voltage, at which time the IGBT losses are lowest and the switching speed is fastest. When the collector voltage > V1, the gate voltage is lowered to the first threshold a, so that IGBT losses increase and the switching speed becomes slow. When the collector voltage is greater than V1+ VD3, the gate voltage is decreased to the second threshold b, so that the IGBT loss increases again and the switching speed slows down again. When the collector voltage is lower than the threshold value V1 or V1+ VD3, the gate voltage will rise correspondingly, so that the IGBT loss is reduced and the switching speed is increased.

When the IGBT works in a saturation region, collector current and voltage are in a linear relation, so that the collector current is increased, the collector voltage is also increased, when the collector voltage is increased, the grid driving voltage is reduced, the turn-on time Ton of the IGBT is increased, the di/dt is reduced, and the peak voltage of the IGBT is increased

The safety of the IGBT is increased due to the reduction.

The IGBT collector voltage is reduced, the gate driving voltage can be increased, and the IGBT conduction time Ton is shortened, so that the IGBT switching loss is reduced.

In some embodiments, the comparison unit includes: the charging circuit comprises a first comparison module, a second comparison module, a first current limiting module, a second current limiting module, a first charging module, a second charging module, a first switching tube module and a fifth switching tube module.

And the direct current power supply is connected to the selection unit after passing through the first current source, is connected to the inverting input end of the second comparison module, is grounded after passing through the second charging module, and is connected to the collector of the IGBT after passing through the second current limiting module. The non-inverting input end of the second comparison module is connected with a second reference source, and the output end of the second comparison module is connected to the base electrode of the fifth switching tube module. An emitter of the fifth switching tube module is connected to a common end of the second current source and the first current limiting module, and a collector of the fifth switching tube module is connected to the selection unit.

And the direct current power supply is connected to the inverting input end of the first comparison module after passing through the second current source, is grounded after passing through the first charging module, and is connected to the collector electrode of the IGBT after passing through the first current limiting module. The non-inverting input end of the first comparison module is connected with a first reference source, and the output end of the first comparison module is connected with the base electrode of the first switch tube module. The emitter of the first switch tube module is connected with a power supply, and the collector of the first switch tube module is connected to the selection unit.

In some embodiments, the first charging module comprises: a first capacitor, such as capacitor C1. The second charging module includes: a second capacitor, such as capacitor C2. The first current limiting module includes: a fifth current limiting resistor (e.g., resistor R5) and a first diode (e.g., diode D1), an anode of the first diode being connected to the fifth current limiting resistor, a cathode of the first diode being connected to the collector of the IGBT. The second current limiting module comprising: the IGBT driving circuit comprises a sixth current-limiting resistor (such as a resistor R6), a second diode (such as a diode D2) and a voltage regulator tube (such as a voltage regulator diode D3), wherein the anode of the second diode is connected to the sixth current-limiting resistor, the cathode of the second diode is connected to the anode of the voltage regulator tube, and the cathode of the voltage regulator tube is connected to the collector electrode of the IGBT.

In some embodiments, the selection unit includes: the second switch tube module, the third switch tube module and the fourth switch tube module.

The collector electrode of the first switch tube module is connected to the base electrode of the second switch tube module, the collector electrode of the second switch tube module is connected to a grid voltage source, and the emitting electrode of the second switch tube module is connected to the driving unit.

The collector electrode of the fifth switching tube module is connected to the base electrode of the third switching tube module, the collector electrode of the third switching tube module is connected to a grid voltage source, and the emitting electrode of the third switching tube module is connected to the driving unit.

The first current source is connected to the base of the fourth switching tube module, the collector of the fourth switching tube module is connected to the grid voltage source, and the emitter of the fourth switching tube module is connected to the driving unit.

In some embodiments, further comprising: the voltage divider comprises a first current limiting module, a second voltage dividing module, a third voltage dividing module and a fourth voltage dividing module.

And the collector of the first switch tube module is connected to the base of the second switch tube module after passing through the first current limiting module.

And the collector electrode of the third switching tube module is connected to a grid voltage source after passing through the second voltage division module.

And the collector electrode of the fourth switching tube module is connected to a grid voltage source after passing through the third voltage division module and is also connected to a negative grid voltage source after passing through the fourth voltage division module.

In some embodiments, the driving unit includes: the optical coupling module, the sixth switching tube module, the seventh switching tube module and the grid resistor.

And the base electrode of the sixth switching tube module is connected to the output end of the optical coupling module. And the collector electrode of the sixth switching tube module is respectively connected to the emitter electrode of the second switching tube module, the emitter electrode of the third switching tube module and the emitter electrode of the fourth switching tube module. And the emitter of the sixth switching tube module is connected to the grid of the IGBT after passing through the grid resistor, and is also connected to the collector of the seventh switching tube module. And the emitter of the seventh switching tube module is connected with another negative grid voltage source. And the emitter of the IGBT is grounded.

Specifically, V1 is the threshold value for collector voltage adjustment (i.e., the potential between diode D1 and resistor R5), and is determined by the selection of parameters of the IGBT driver circuit itself. VD3 is the pressure resistance of a stabilivolt D3. After power-on, the IGBT starts to work, and when the collector voltage IGBT _ IN of the IGBT is smaller than the critical voltage V1: at this time, VCC flows into the collector through the second current source Is2, the resistor R5, the diode D1, the first current source Is1, the resistor R6, the diode D2 and the voltage regulator D3. The negative end of the comparator OP1 is in a low voltage state, the comparator OP1 outputs a low level to turn on the switch tube MP1, the 5V power supply acts on the switch tube MP2 through the switch tube MP1 and the current limiting resistor R1 to turn on the switch tube MP2, and at the moment, the gate voltage source Vss provides a driving voltage for the IGBT through the switch tube MP2, the switch tube MP6 and the resistor R7.

When the collector voltage IGBT _ IN of the IGBT is greater than or equal to the critical voltage V1 and less than the critical voltage V1+ VD 3: since V1 is equal to the potential between resistor R5 and diode D1, when IGWhen the collector voltage of BT Is greater than V1, diode D1 Is turned off, and at this time, the second current source Is2 charges capacitor C1, and as capacitor C1 charges, the voltage at point a (i.e., the inverting input terminal of comparator OP 1) gradually increases, and when the voltage at point a exceeds the reference voltage at the non-inverting input terminal of comparator OP1, the first reference source V Is connected to the first reference source V_ref1When the voltage is "n", the comparator OP1 outputs a high level, and the switching tube MP1 is turned off. Because the collector voltage of the IGBT Is less than V1+ VD3, the first current source Is1 flows to the collector of the IGBT through the resistor R6, the diode D2 and the voltage regulator D3, and the voltage at the point B (i.e., the inverting input terminal of the comparator OP 2) Is lower than the reference voltage at the non-inverting input terminal of the comparator OP2, i.e., the second reference source V_ref2The comparator OP2 outputs a low-potential signal, the switch tube MP5 is conducted, the switch tube MP3 is conducted due to the rise of the potential of the point A, the grid voltage source Vss is divided by the resistor R2 and then provides driving voltage for the IGBT through the switch tube MP3, the switch tube MP6 and the resistor R7, at the moment, the IGBT loss is increased, and the switching speed is reduced.

When the collector voltage IGBT _ IN is greater than or equal to the critical voltage V1+ VD 3: because the potential between the diode D2 and the voltage regulator tube D3 Is V1+ VD3, when the collector voltage of the IGBT Is larger than V1+ VD3, the diode D2 Is cut off, the first current source Is1 charges the capacitor C2 at the moment, the voltage at the point B gradually rises along with the charging of the capacitor C2, the switch tube MP4 Is conducted, and when the voltage at the point B Is higher than the voltage at the second reference source V3_ref2When the voltage is higher than the threshold voltage, the comparator OP2 outputs a high potential, the switch tube MP5 is cut off, at the moment, the grid voltage source Vss is divided by the voltage dividing resistors R2 and R3 and then provides driving voltage for the IGBT through the switch tubes MP4, MP6 and the resistor R7, at the moment, the IGBT loss continues to increase, and the switching speed continues to decrease.

Therefore, the gate driving voltage is correspondingly adjusted according to the change of the collector voltage when the IGBT operates, and the switching time of the IGBT is further changed, so that the IGBT can be in a relatively safe working state when the collector voltage rises. When the voltage of the IGBT collector rises, the switching time of the IGBT is prolonged by reducing the driving voltage of the IGBT grid electrode, so that the IGBT has better safety performance when in failure.

Through a large number of tests, the technical scheme of the invention is adopted, and the gate driving voltage is correspondingly adjusted according to the change of the collector voltage when the IGBT runs, so that the switching time of the IGBT is changed; therefore, when the voltage of the IGBT collector rises, the switching time of the IGBT is prolonged by reducing the driving voltage of the IGBT gate, so that the IGBT has better safety performance when in failure.

According to an embodiment of the present invention, there is also provided an IGBT corresponding to a driving device of the IGBT. The IGBT may include: the above-described IGBT driving device.

Among the relevant side, IGBT drive circuit makes the switch tube switch on and then carries out the voltage limiting to IGBT grid voltage for the signal through software, but can only adjust driving voltage at the process of turn-off, can not make the adjustment in advance, and IGBT still has the risk of damage, and can only adjust a fixed driving voltage, and is very low to different IGBT's suitability, involves the software part also greatly increased the research and development cost, therefore the practicality is relatively poor.

In the related scheme, the driving capability of the IGBT can be changed by changing the gate resistance, but the on/off state of each switching tube is controlled by a large number of I/O signals based on software implementation, which is very difficult to implement and has very high cost.

In some embodiments, the present invention provides a driving circuit for self-adjusting the gate voltage of an IGBT, which can adjust the gate driving voltage according to the change of the collector voltage when the IGBT operates, so as to change the switching time of the IGBT, so that the IGBT can be in a relatively safe operating state when the collector voltage increases, and if the collector voltage decreases, the switching loss of the IGBT can also be reduced to a certain extent.

Specifically, according to the scheme of the invention, when the voltage of the IGBT collector is increased, the switching time of the IGBT is increased by reducing the drive voltage of the IGBT gate, so that the IGBT has better safety performance when in failure. Therefore, the problem that when the IGBT breaks down, under the condition that the collector electrode of the IGBT is large, the IGBT is burnt out by impulse voltage generated when the IGBT is turned off is solved; namely, the problem that when the IGBT is required to be turned off in a driving circuit of the IGBT when the IGBT fails, voltage spikes generated in the turn-off process of the IGBT can exceed the withstand voltage value of the IGBT, and the IGBT can be damaged is solved.

According to the scheme provided by the invention, when the voltage of the IGBT collector is reduced, the switching time of the IGBT is reduced by increasing the drive voltage of the IGBT gate, so that the switching loss of the IGBT is reduced. Therefore, the problem that the IGBT switching loss is overlarge when the IGBT collector voltage is reduced is solved.

In some embodiments, normally, the IGBT operates in a saturation region, and the inter-CE voltage of the IGBT increases linearly with the increase of the collector current, so that if the current becomes larger, the collector voltage increases.

The invention provides an IGBT driving circuit, which can adjust the change of the collector voltage correspondingly, thereby improving the driving performance of the IGBT.

The following describes an exemplary implementation process of the scheme of the present invention with reference to the examples shown in fig. 2 to fig. 6.

Fig. 2 is a schematic flow chart of the whole IGBT adjusting with the collector voltage. As shown in fig. 2, the whole IGBT collector voltage regulation process includes:

step 11, under the condition that the voltage of the IGBT collector electrode is increased, the grid driving voltage of the IGBT is reduced, the IGBT switching time is increased, the di/dt of the IGBT is reduced,

the safety of the IGBT can be improved.

That is, when the IGBT operates in the saturation region, the collector current and the collector voltage increase linearly, and as shown in fig. 2, when the collector voltage increases, the gate driving voltage decreases, so that the turn-on time Ton of the IGBT increases, and further the di/dt decreases, and therefore the peak voltage thereof decreases

The safety of the IGBT is increased due to the reduction. Wherein, V is the peak voltage during switching, L is the parasitic inductance of the bus, and di/dt is the variation of the bus current along with time.

Step 12, under the condition that the voltage of the IGBT collector electrode is reduced, the grid driving voltage of the IGBT is increased, the switching time of the IGBT is shortened, the di/dt of the IGBT is increased,

the safety of the IGBT can be reduced.

That is, the IGBT collector voltage is lowered, the gate drive voltage can be raised, and the IGBT on time Ton is shortened, thereby reducing the IGBT switching loss.

Fig. 3 is a schematic diagram illustrating variation of gate voltage parameters. As shown in fig. 3, a is a gate voltage first threshold, b is a gate voltage second threshold, and a gate voltage third threshold c and an nth threshold z … … may be set as appropriate, where n is a natural number. It requires Vss > a > b > c > … … > z.

Fig. 4 is a schematic diagram of a collector voltage adjustment process of an embodiment of the IGBT driving circuit. Fig. 4 is a circuit adjustment flow chart for setting only 2 thresholds a and b, the gate driving circuit is constantly adjusting as long as the IGBT does not trigger protection, and V1 in fig. 5 is a critical value for collector voltage adjustment (i.e., the potential between diode D1 and resistor R5) determined by the selection of parameters of the circuit itself; VD3 is the pressure resistance of a stabilivolt D3.

As shown in fig. 4, the collector voltage adjustment process of the IGBT driving circuit includes:

and step 21, when the operation is started, the IGBT driving voltage runs at the maximum value Vss of the driving voltage, at the moment, the IGBT loss is the lowest, and the switching speed is the fastest.

And step 22, when the collector voltage is larger than V1, reducing the gate voltage to a first threshold value a, so that the IGBT loss is increased, and the switching speed is slowed.

And step 23, when the collector voltage is greater than V1+ VD3, reducing the gate voltage to a second threshold b, so that the IGBT loss is increased again, and the switching speed is slowed down again.

Step 24, the whole control process needs to be adjusted continuously, so that continuous judgment is needed. When the collector voltage is lower than the threshold value V1 or V1+ VD3, the gate voltage will rise correspondingly, so that the IGBT loss is reduced and the switching speed is increased.

Similarly, if a plurality of thresholds a, b, c, d … … are set, the corresponding thresholds should be set as V1, V2, and V3 … ….

Fig. 5 is a schematic structural diagram of an embodiment of an IGBT driving circuit. In the example shown in fig. 5, the circuit within the dashed line frame directly gives the voltage signal. The IGBT driving circuit enables the grid voltage to change along with the voltage change on the bus, and improves the switching waveform of the IGBT. As shown in fig. 5, the IGBT drive circuit in which only two thresholds are set includes: a current limiting resistor R1; voltage dividing resistors R2, R3, R4; current limiting resistors R5, R6; a gate resistance R7; switching tubes MP1, MP2, MP3, MP4, MP5, MP6 and MP 7; diodes D1, D2; a voltage regulator tube D3; capacitances C1, C2; comparators OP1, OP 2; a first current source Is1 and a second current source Is 2.

In the example shown in fig. 5, the first current source Is1 and the second current source Is2 are the same size, the resistors R5 and R6 are the same size, and the resistors D1 and D2 are the same size. Vs is a negative gate voltage source, and-8V is a gate voltage source.

In the example shown in fig. 5, the voltage dividing resistors R2, R3, R4 are voltage dividing functions for obtaining a regulated voltage. The first current source Is1 and the second current source Is2 are used for charging the capacitor C1 and the capacitor C2. The resistor R5 and the diode D1 are used for comparing with the reference source of the comparator OP1, and further controlling the on/off of the switch MP 1. The resistor R6, the diode D2 and the voltage regulator tube D3 are used for controlling the on/off of the switch tube MP 4. The switching tubes MP2, MP3, MP4 are used to select the gate voltage. The switching tubes MP6 and MP7 are push-pull structures.

The specific operation flow of the IGBT driving circuit will be exemplarily described below with reference to the examples shown in fig. 2 and 3.

After power-on, the IGBT starts to work, and when the collector voltage IGBT _ IN of the IGBT is smaller than the critical voltage V1: at the moment, VCC flows into the collector through a second current source Is2, a resistor R5, a diode D1, a first current source Is1, a resistor R6, a diode D2 and a voltage regulator D3; the negative end of the comparator OP1 is in a low voltage state, the comparator OP1 outputs a low level to turn on the switch tube MP1, the 5V power supply acts on the switch tube MP2 through the switch tube MP1 and the current limiting resistor R1 to turn on the switch tube MP2, and at the moment, the gate voltage source Vss provides a driving voltage for the IGBT through the switch tube MP2, the switch tube MP6 and the resistor R7.

When the collector voltage IGBT _ IN of the IGBT is greater than or equal to the critical voltage V1 and less than the critical voltage V1+ VD 3: since V1 Is equal to the potential between the resistor R5 and the diode D1, when the collector voltage of the IGBT Is greater than V1, the diode D1 Is turned off, and the second current source Is2 charges the capacitor C1, the voltage at the point a (i.e. the inverting input terminal of the comparator OP 1) gradually increases with the charging of the capacitor C1, and when the voltage at the point a exceeds the reference voltage at the non-inverting input terminal of the comparator OP1, the first reference source V Is connected to the first reference source V_ref1When the voltage is lower than the threshold voltage, the comparator OP1 outputs a high level, and the switching tube MP1 is turned off; because the collector voltage of the IGBT Is less than V1+ VD3, the first current source Is1 flows to the collector of the IGBT through the resistor R6, the diode D2 and the voltage regulator D3, and the voltage at the point B (i.e., the inverting input terminal of the comparator OP 2) Is lower than the reference voltage at the non-inverting input terminal of the comparator OP2, i.e., the second reference source V_ref2The comparator OP2 outputs a low-potential signal, the switch tube MP5 is conducted, the switch tube MP3 is conducted due to the rise of the potential of the point A, the grid voltage source Vss is divided by the resistor R2 and then provides driving voltage for the IGBT through the switch tube MP3, the switch tube MP6 and the resistor R7, at the moment, the IGBT loss is increased, and the switching speed is reduced.

When the collector voltage IGBT _ IN is greater than or equal to the critical voltage V1+ VD 3: because the potential between the diode D2 and the voltage regulator tube D3 Is V1+ VD3, when the collector voltage of the IGBT Is larger than V1+ VD3, the diode D2 Is cut off, the first current source Is1 charges the capacitor C2 at the moment, the voltage at the point B gradually rises along with the charging of the capacitor C2, the switch tube MP4 Is conducted, and when the voltage at the point B Is higher than the voltage at the second reference source V3_ref2When the voltage is higher than the threshold voltage, the comparator OP2 outputs a high potential, the switch tube MP5 is turned off, and the grid voltage source Vss is divided by the voltage dividing resistors R2 and R3 and then provided to the IGBT by the switch tubes MP4, MP6 and the resistor R7And driving voltage is supplied, the IGBT loss continues to increase at the moment, and the switching speed continues to decrease.

The critical voltage and the divider resistance can be expanded to 3, 4 or even more according to the actual situation.

Fig. 6 is a schematic structural diagram of another embodiment of the IGBT driving circuit. As shown in fig. 6, the IGBT driving circuit includes: the circuit comprises an optocoupler module, a switch tube MP6, a switch tube MP7, a resistor R7, a power tube IGBT, a grid voltage selection module, a grid voltage acquisition module, a logic judgment part and a voltage threshold setting part.

The optical coupling module is respectively connected to the gates of the switching tube MP6 and the switching tube MP7, and the collector of the switching tube MP6 is connected to the gate voltage selection module. The emitter of the switching tube MP6 is connected to the collector of the switching tube MP7, and is also connected to the gate of the power tube IGBT through the resistor R7. The emitter of the switching tube MP7 is connected to the-8V gate voltage source. The collector of the power tube IGBT is connected to the voltage threshold setting section. The IGBT power supply comprises a grid voltage selection module of the power tube IGBT, a grid voltage acquisition module and a logic judgment part which are respectively connected with the grid voltage selection module, and a voltage threshold setting part connected with the logic judgment part.

In the example shown in fig. 6, in the voltage threshold setting section, D₁＜D₂＜……D_n. The number of circuit branches within each block in fig. 6 is the same.

Since the processing and functions of the IGBT of this embodiment are basically corresponding to the embodiment, principle and example of the device shown in fig. 1, the description of this embodiment is not detailed, and reference may be made to the related description in the foregoing embodiment, which is not described herein again.

Through a large number of tests, the technical scheme of the embodiment is adopted, and the gate driving voltage is correspondingly adjusted according to the change of the collector voltage when the IGBT operates, so that the switching time of the IGBT is changed, and the IGBT can be in a relatively safe working state when the collector voltage is increased; when the IGBT collector voltage decreases, the switching time of the IGBT is reduced by raising the IGBT gate drive voltage, so that the switching losses of the IGBT decrease.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A drive device of an IGBT, characterized by comprising: the device comprises a comparison unit, a selection unit and a driving unit; wherein the content of the first and second substances,

the comparison unit is configured to compare the magnitude relation between the collector voltage of the IGBT and a set voltage under the condition that the IGBT is powered on and operated to obtain a comparison result; the number of the set voltages is more than two; the comparison unit includes: the charging circuit comprises a first comparison module, a second comparison module, a first current limiting module, a second current limiting module, a first charging module, a second charging module, a first switching tube module and a fifth switching tube module; the direct current power supply is connected to the selection unit after passing through the first current source and is also connected to the inverting input end of the second comparison module; the direct current power supply passes through the first current source and then the second charging module and then is grounded; the direct current power supply is connected to the collector electrode of the IGBT after passing through the first current source and the second current limiting module; the non-inverting input end of the second comparison module is connected with a second reference source, and the output end of the second comparison module is connected to the base electrode of the fifth switching tube module; an emitter of the fifth switching tube module is connected to a common end of a second current source and the first current limiting module, and a collector of the fifth switching tube module is connected to the selection unit; the direct current power supply is connected to the inverting input end of the first comparison module after passing through the second current source; the direct current power supply is grounded after passing through the second current source and the first charging module; the direct current power supply is connected to the collector electrode of the IGBT after passing through the second current source and the first current limiting module; the non-inverting input end of the first comparison module is connected with a first reference source, and the output end of the first comparison module is connected with the base electrode of the first switch tube module; the emitter of the first switch tube module is connected with a power supply, and the collector of the first switch tube module is connected to the selection unit;

the selection unit is configured to select the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage so as to adjust the gate voltage of the IGBT according to the collector voltage of the IGBT;

2. The IGBT driving device according to claim 1, wherein two or more of the set voltages include: a first set voltage and a second set voltage.

3. The IGBT driving device according to claim 2, wherein when the two or more setting voltages are a first setting voltage and a second setting voltage:

the comparison unit compares the magnitude relation between the collector voltage of the IGBT and the set voltage, and comprises: comparing a magnitude relationship between a collector voltage of the IGBT and the first and second set voltages;

the selection unit selects the gate voltage of the IGBT according to a comparison result of a magnitude relation between the collector voltage of the IGBT and a set voltage, and comprises:

if the collector voltage of the IGBT is smaller than the first set voltage, the grid voltage of the IGBT is the maximum value of the set driving voltage;

if the collector voltage of the IGBT is greater than or equal to the first set voltage and less than the second set voltage, the gate voltage of the IGBT is reduced to a first set threshold value from the maximum value of the set driving voltage;

and if the collector voltage of the IGBT is greater than or equal to the second set voltage, the grid voltage of the IGBT is reduced from a first set threshold value to a second set threshold value.

4. The IGBT driving device according to claim 1, wherein,

the first charging module includes: a first capacitor;

the second charging module includes: a second capacitor;

the first current limiting module includes: the anode of the first diode is connected to the fifth current-limiting resistor, and the cathode of the first diode is connected to the collector of the IGBT;

the second current limiting module comprising: the IGBT driving circuit comprises a sixth current-limiting resistor, a second diode and a voltage-regulator tube, wherein the anode of the second diode is connected to the sixth current-limiting resistor, the cathode of the second diode is connected to the anode of the voltage-regulator tube, and the cathode of the voltage-regulator tube is connected to the collector of the IGBT.

5. The IGBT driving device according to claim 1 or 4, wherein the selection unit comprises: the second switch tube module, the third switch tube module and the fourth switch tube module; wherein the content of the first and second substances,

the collector of the first switch tube module is connected to the base of the second switch tube module, the collector of the second switch tube module is connected to a grid voltage source, and the emitter of the second switch tube module is connected to the driving unit;

a collector of the fifth switching tube module is connected to a base of the third switching tube module, a collector of the third switching tube module is connected to a grid voltage source, and an emitter of the third switching tube module is connected to the driving unit;

6. The IGBT driving device according to claim 5, further comprising: the first current limiting module, the second voltage dividing module, the third voltage dividing module and the fourth voltage dividing module; wherein the content of the first and second substances,

the collector of the first switch tube module is connected to the base of the second switch tube module after passing through the first current limiting module;

the collector electrode of the third switching tube module is connected to a grid voltage source after passing through the second voltage division module;

7. The IGBT driving device according to claim 5, wherein the driving unit comprises: the optical coupling module, the sixth switching tube module, the seventh switching tube module and the grid resistor are connected with the grid resistor; wherein the content of the first and second substances,

the base electrode of the sixth switching tube module is connected to the output end of the optical coupling module; the collector of the sixth switching tube module is respectively connected to the emitter of the second switching tube module, the emitter of the third switching tube module and the emitter of the fourth switching tube module; an emitter electrode of the sixth switching tube module is connected to a grid electrode of the IGBT after passing through the grid electrode resistor; the emitter of the sixth switching tube module is also connected to the collector of the seventh switching tube module; and the emitter of the seventh switching tube module is connected with another negative grid voltage source.

8. An IGBT, characterized by comprising: the drive device of the IGBT according to any one of claims 1 to 7.