IGBT control circuit with soft start protection function

Abstract

The invention relates to an IGBT control circuit with a soft start protection function. The input end is connected with the base electrode of the triode Q7, the emitter electrode of the triode Q7 is grounded, the collector electrode of the triode Q7 is connected with starting voltage, and the input end is further connected with the IGBT tube; the base electrode of the triode Q1 is connected with the collector electrode of the triode Q7, the emitter electrode of the triode Q1 is grounded through a capacitor C19, and the collector electrode of the triode Q1 is connected with starting voltage; a base electrode of the triode Q5 is connected with a starting signal and a starting voltage, an emitter electrode of the triode Q5 is grounded, and a collector electrode of the triode Q5 is connected with the starting voltage; the base electrode of the triode Q2 is connected with the starting voltage, the emitter electrode is connected with the control end of the IGBT tube, and the collector electrode is connected with the starting voltage; the base electrode of the triode Q3 is connected with the starting voltage, the emitting electrode of the triode Q3 is connected with the control end of the IGBT tube, and the collecting electrode of the triode Q3 is connected with the emitting electrode of the triode Q2; the base electrode of the triode Q6 is connected with the starting voltage, the collector electrode is grounded, and the emitter electrode is connected with the collector electrode of the triode Q3.

Description

Technical Field

[0001] The present invention relates to the field of heating cooker circuits, and particularly to an IGBT control circuit with a soft start protection function. Background Art

[0002] In the control circuit of an IGBT, a triode push-pull circuit is often used as an electronic switch to drive the IGBT. In the switching circuit, two triodes work alternately. One triode is responsible for connecting the circuit to +18V, and the other triode is responsible for connecting the circuit to ground. The on-off of the G pole of the IGBT drive circuit board is realized through the control of the main chip PPG pin. However, in the current industry solution, when driving and turning on the IGBT, there is no soft start before turning on the IGBT and then detecting the pot for heating. Instead, 18V is directly turned on or off instantaneously. The peak current at the moment when the IGBT is turned on will be very high (far exceeding the peak current range of the IGBT), and the IGBT will heat up and be damaged, resulting in quality hazards such as short circuit tripping and fire in the whole machine due to the damage of the IGBT. Summary of the Invention

[0003] To solve the above problems, the present technical solution provides an IGBT control circuit with a soft start protection function.

[0004] To achieve the above object, the present technical solution is as follows:

[0005] An IGBT control circuit with a soft start protection function, comprising:

[0006] An input terminal, which is connected to the base of triode Q7, the emitter is grounded, the collector is connected with a startup voltage, and the input terminal is also connected to the IGBT tube;

[0007] Triode Q1, whose base is connected to the collector of triode Q7, the emitter of triode Q1 is grounded through capacitor C19, and the collector of triode Q1 is connected to the startup voltage;

[0008] Triode Q5, whose base is connected with a startup signal, this base is also connected to the startup voltage, the emitter is grounded, and the collector is connected to the startup voltage;

[0009] Triode Q2, whose base is connected to the startup voltage, the emitter is connected to the control end of the IGBT tube, and the collector is connected to the startup voltage;

[0010] Triode Q3, whose base is connected to the startup voltage, the emitter is connected to the control end of the IGBT tube, and the collector is connected to the emitter of triode Q2;

[0011] A triode Q6, whose base is connected to the startup voltage, collector is grounded, and emitter is connected to the collector of the triode Q3.

[0012] In some embodiments, the input terminal is grounded successively through resistors R16, R17, R18, R19, R20, R39, R44, and R48, and the common connection point between the resistor R44 and the resistor R48 is connected to the base of the triode Q7 through a resistor R49.

[0013] In some embodiments, the base of the triode Q5 is connected to the startup signal through a resistor R34, and the resistor R34 is also connected to the startup voltage through a resistor R29.

[0014] In some embodiments, the base of the triode Q1 is connected to the collector of the triode Q7 successively through a diode D10 and a resistor R53. The emitter of the triode Q1 is connected to the capacitor C19 through a resistor R33, and this emitter is also connected to the base of the triode Q6. The collector of the triode Q1 is connected to the startup voltage through a resistor R54.

[0015] In some embodiments, the base of the triode Q2 is connected to the startup voltage through a resistor R10, the collector is connected to the startup voltage through a resistor R23, and the emitter is connected to the emitter of the triode Q6 through a resistor R24.

[0016] In some embodiments, the base of the triode Q3 is grounded through a resistor R32, and this base is also connected to the startup voltage through a resistor R25. The collector is connected to the triode Q6, and the emitter is connected to the IGBT tube successively through a diode D11, a bead B1, and a resistor R58.

[0017] In some embodiments, the resistor R58 is grounded respectively through a resistor R28 and a zener diode ZD1.

[0018] The beneficial effects of this application are as follows:

[0019] This application realizes that the IGBT must be soft-started first and then the pot detection is carried out for startup. It effectively prevents the risk of overheating and damage of the IGBT caused by excessive peak current at the moment when the IGBT is turned on in the first waveform of pot detection and startup heating, greatly improves the service life of the IGBT, and avoids quality hazards such as short-circuit tripping and fire caused by the damage of the IGBT in the whole machine. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments.

[0021] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0022] Figure 2 is a schematic waveform diagram of the standby idle state of an embodiment of the present invention;

[0023] Figure 3 is a schematic waveform diagram of the pot detection and start heating state of an embodiment of the present invention;

[0024] Figure 4 is a schematic waveform diagram of the normal heating state of an embodiment of the present invention. Detailed implementation manners

[0025] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Please refer to Figures 1-4 as shown, an IGBT control circuit with a soft start protection function includes;

[0027] An input terminal, the input terminal is connected to the base of the triode Q7, the emitter is grounded, the collector is connected with a startup voltage, and the input terminal is also connected to the IGBT tube;

[0028] A triode Q1, its base is connected to the collector of the triode Q7, the emitter of the triode Q1 is grounded through a capacitor C19, and the collector of the triode Q1 is connected to the startup voltage;

[0029] A triode Q5, its base is connected with a startup signal, this base is also connected to the startup voltage, the emitter is grounded, and the collector is connected to the startup voltage;

[0030] A triode Q2, its base is connected to the startup voltage, the emitter is connected to the control terminal of the IGBT tube, and the collector is connected to the startup voltage;

[0031] A triode Q3, its base is connected to the startup voltage, the emitter is connected to the control terminal of the IGBT tube, and the collector is connected to the emitter of the triode Q2;

[0032] A triode Q6, its base is connected to the startup voltage, the collector is grounded, and the emitter is connected to the collector of the triode Q3.

[0033] Reference Figure 2, the voltage at point D is 311V, the voltage at point E is 0.76V. At this time, the triode Q7 is turned on and conducting, the voltage at point F is 0V, and the triode Q1 is cut off and turned off; the voltage at point A is 2V, the triode Q5 is turned on and conducting, the voltage at point B is 0V, the triode Q2 is cut off and turned off, the voltage at point C is 0V, and the IGBT is turned off;

[0034] Reference Figure 3 , (1) For the first time, the voltage at point A is pulled down, the triode Q5 is turned off, 18V charges C19 through R10 and R33, the voltage at point B gradually rises, the triode Q2 is turned on, and the voltage at point C also rises; (2) When the voltage at point C is 9V, the voltage at point H is 8V, the triodes Q3 and Q6 are turned on and conducting, the rising speed of the voltage at point C slows down, the IGBT is turned on, the coil disk is charged, and the voltages at points D and E gradually decrease. (3) After 4us, the voltage at point A is pulled up, the drive circuit returns to the idle state, the IGBT has been soft-started once, and the voltage at point D is close to 0; (4) For the second time, the voltage at point A is pulled down, the triode Q5 is turned off, and when the voltage at point E drops to turn off Q7, the voltage at point F rises, Q1 is turned on, 18V charges C19 through R10, R54, and R33. At this time, the charging is faster than the first time, the voltage at point C can reach 18V, and the IGBT is fully turned on, and the coil disk continues to store energy; (5) After 4us, the voltage at point A is pulled up, the drive circuit returns to the idle state. At this time, the coil disk has stored energy and can perform pot detection and start heating operations;

[0035] Reference Figure 4 , when the voltage at point A is pulled down, the triode Q5 is turned off and Q7 is also turned off in time, and the voltage at point C can quickly rise to 18V.

[0036] In summary, through the optimization of the IGBT drive scheme design, this solution realizes that the IGBT must be soft-started first and then pot-detected and turned on, effectively preventing the risk of overheating and damage of the IGBT caused by excessive peak current at the moment when the IGBT is turned on in the first waveform of pot detection and start heating, greatly improving the service life of the IGBT, and avoiding quality hazards such as short-circuit tripping and fire caused by IGBT damage in the whole machine.

[0037] In some embodiments, the input end is grounded through resistors R16, R17, R18, R19, R20, R39, R44, and R48 in sequence. The common connection point between the resistor R44 and the resistor R48 is connected to the base of the triode Q7 through the resistor R49.

[0038] In some embodiments, the base of the triode Q5 is connected to the start signal through the resistor R34, and the resistor R34 is also connected to the start voltage through the resistor R29.

[0039] In some embodiments, the base of the triode Q1 is connected to the collector of the triode Q7 through the diode D10 and the resistor R53 in sequence. The emitter of the triode Q1 is connected to the capacitor C19 through the resistor R33, and this emitter is also connected to the base of the triode Q6. The collector of the triode Q1 is connected to the startup voltage through the resistor R54.

[0040] In some embodiments, the base of the triode Q2 is connected to the startup voltage through the resistor R10, the collector is connected to the startup voltage through the resistor R23, and the emitter is connected to the emitter of the triode Q6 through the resistor R24.

[0041] In some embodiments, the base of the triode Q3 is grounded through the resistor R32, and this base is also connected to the startup voltage through the resistor R25. The collector is connected to the triode Q6, and the emitter is connected to the IGBT tube through the diode D11, the bead B1, and the resistor R58 in sequence.

[0042] In some embodiments, the resistor R58 is grounded through the resistor R28 and the voltage stabilizing diode ZD1 respectively.

[0043] The above are only the preferred embodiments of the present application, and are not used to limit the scope of implementation of the present application. Other embodiments with the same or similar principles and basic structures as the present application are within the protection scope of the present application.

Claims

1. An IGBT control circuit with a soft start protection function, characterized in that including; an input terminal, which is connected to the base of transistor Q7, with the emitter grounded and the collector connected to a startup voltage, and the input terminal is also connected to an IGBT transistor; transistor Q1, whose base is connected to the collector of transistor Q7, the emitter of transistor Q1 is grounded through capacitor C19, and the collector of transistor Q1 is connected to the startup voltage; transistor Q5, whose base is connected to a startup signal and also to the startup voltage, the emitter is grounded, and the collector is connected to the startup voltage; transistor Q2, whose base is connected to the startup voltage, the emitter is connected to the control terminal of the IGBT transistor, and the collector is connected to the startup voltage; transistor Q3, whose base is connected to the startup voltage, the emitter is connected to the control terminal of the IGBT transistor, and the collector is connected to the emitter of transistor Q2; transistor Q6, whose base is connected to the startup voltage, the collector is grounded, and the emitter is connected to the collector of transistor Q3.

2. The IGBT control circuit with a soft start protection function according to claim 1, characterized in that: The input terminal is grounded sequentially through resistors R16, R17, R18, R19, R20, R39, R44, and R48, and the common connection point between resistors R44 and R48 is connected to the base of transistor Q7 through resistor R49.

3. The IGBT control circuit with a soft start protection function according to claim 1, characterized in that: The base of transistor Q5 is connected to the startup signal through resistor R34, and resistor R34 is also connected to the startup voltage through resistor R29.

4. An IGBT control circuit with a soft start protection function according to claim 1, characterized in that: The base of transistor Q1 is connected to the collector of transistor Q7 sequentially through diode D10 and resistor R53, the emitter of transistor Q1 is connected to capacitor C19 through resistor R33, and this emitter is also connected to the base of transistor Q6. The collector of transistor Q1 is connected to the startup voltage through resistor R54.

5. An IGBT control circuit with a soft start protection function according to claim 1, characterized in that: The base of transistor Q2 is connected to the startup voltage through resistor R10, the collector is connected to the startup voltage through resistor R23, and the emitter is connected to the emitter of transistor Q6 through resistor R24.

6. The IGBT control circuit with a soft start protection function according to claim 1, characterized in that: The base of transistor Q3 is grounded through resistor R32 and is also connected to the startup voltage through resistor R25. The collector is connected to transistor Q6, and the emitter is connected to the IGBT transistor sequentially through diode D11, bead B1, and resistor R58.

7. The IGBT control circuit with a soft start protection function according to claim 6, characterized in that: Resistor R58 is grounded respectively through resistor R28 and zener diode ZD1.

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