An IGBT driving circuit with adjustable overcurrent threshold
By designing an IGBT driving circuit with adjustable overcurrent threshold, the problem of response delay in the IGBT driving circuit in the prior art under overcurrent conditions is solved, and the driving signal integrity is ensured through the shaping circuit, which can achieve fast response and effective protection of IGBTs in different power segments.
Patent Information
- Application Number
- CN202510022613.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-04-01
AI Technical Summary
The existing IGBT driver circuits are difficult to respond quickly under overcurrent conditions, resulting in short-circuit protection delays, and most power modules lack integrated senseFETs, which increases system costs.
An IGBT driving circuit with adjustable overcurrent threshold is designed. The IGBT overcurrent threshold is adjusted by adjusting the parameters of the voltage-regulating diode ZD1, and a shaping circuit is introduced into the driving circuit to ensure the integrity of the driving signal during long-distance transmission.
It realizes fast response and effective protection on IGBTs in different power segments, reduces system costs, and ensures the integrity of the drive signal during long-distance transmission.
Smart Images
Figure CN119742999A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of IGBT drive circuits, and in particular to an IGBT drive circuit with an adjustable overcurrent threshold. Background Art
[0002] IGBT overcurrent occurs when the loop inductance is large. Compared with a short circuit, the current rises slowly and the IGBT will not desaturate. Therefore, a current sensor is needed to measure the current value to protect the system.
[0003] The short-circuit withstand time of the power module is generally in the microsecond level, so the sampling bandwidth or response time under overcurrent conditions is particularly critical. The short-circuit protection design of the system needs to be able to respond quickly when a short-circuit occurs. Short-circuit detection also requires a blanking time after turning on to avoid false triggering caused by interference during the switching process. Short-circuit protection methods can be divided into two categories: short-circuit current detection and voltage drop detection.
[0004] The common way to detect current is through senseFET or shunt resistor, while voltage detection is desaturation protection. Since most power modules do not have integrated senseFET, adding shunt resistors will increase system cost, so desaturation protection is a more common protection method in the industry. In addition to collecting current through current sensors, overcurrent detection circuits can also be introduced in the drive circuit. Both di / dt detection and VCE saturation voltage drop detection can detect current. Current sensor detection mainly uses closed-loop Hall sensors for sampling. Limited by the bandwidth of the Hall sensor and the delay of the control sampling circuit, the real-time performance may need to be improved; di / dt detection mainly judges the current size based on the parasitic inductance between the power E pole and the drive E pole of the IGBT, and this inductance parameter is not easy to measure; VCE saturation voltage drop detection can use the desaturation DESAT detection function of the IGBT gate driver. Summary of the invention
[0005] The object of the present invention is to provide an IGBT driving circuit with adjustable overcurrent threshold.
[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an IGBT driving circuit with adjustable overcurrent threshold, comprising a driving circuit for adjusting the IGBT overcurrent threshold after outputting a driving signal, the driving circuit comprising a driving chip U2, pull-up resistors R11, R12, a current limiting resistor R17, a voltage zener diode ZD2, and a capacitor C2, wherein: the pull-up resistors R11 and R12 are connected in parallel and connected to the driving chip U2 respectively, the current limiting resistor R17 is connected to the driving chip U2, and one end of the voltage zener diode ZD2 after being connected in parallel with the capacitor C2 is connected to the chip U2, characterized in that the other end of the voltage zener diode ZD2 after being connected in parallel with the capacitor C2 is connected in sequence with a resistor R8, a voltage zener diode ZD1, a diode D1, and D2, one end of D2 is connected to the IGBT, and a resistor R7 is connected between the resistor R8 and the diode ZD1.
[0007] Furthermore, the driving circuit further includes resistors R9, R15, and a capacitor C4. One end of the resistors R9 and R15 connected in parallel is connected to the driving chip U2, and the other end of the resistors R9 and R15 connected in parallel is connected to the capacitor C4.
[0008] Furthermore, the driving circuit also includes an NPN transistor Q1 and a PNP transistor Q2. The base of the NPN transistor Q1 is connected to the base of the PNP transistor Q2 and then connected to the other end of the resistors R9 and R15 connected in parallel. The collector and base of the PNP transistor Q2 are connected via a capacitor C4.
[0009] Furthermore, the driving circuit also includes resistors R10, R13, and a switching diode D3. One end of the resistor R10 is connected to the emitter of the NPN transistor Q1, one end of the resistor R13 is connected to the emitter of the PNP transistor Q2, and the other ends of the resistors R10 and R13 are connected and connected to the collector of the NPN transistor Q1 through the switching diode D3.
[0010] Furthermore, the driving circuit further includes a resistor R14 and a capacitor C3, and one end of the resistor R14 and the capacitor C3 connected in parallel is connected to a switching diode D3.
[0011] Furthermore, the driving circuit further includes a transient suppression diode TVS1, and the transient suppression diode TVS1 is connected to the other end of the resistor R14 and the capacitor C3 connected in parallel.
[0012] Furthermore, the invention also includes a shaping circuit for ensuring the integrity of the driving signal output by the driving circuit, the shaping circuit includes an inverter U1, pull-up resistors R1, R2, current limiting resistors R3, R5, and a filter capacitor C1, one end of the pull-up resistor R1 is connected to the inverter U1 through the current limiting resistor R5, one end of the pull-up resistor R2 is connected to the inverter U1 through the current limiting resistor R3, and the filter capacitor C1 is connected to the inverter U1.
[0013] Furthermore, the model of the driver chip U2 is NSI6651ASC.
[0014] Furthermore, the inverter U1 has a model of 74HC14D.
[0015] It can be seen from the above technical solution that the present invention has the following beneficial effects: The IGBT drive circuit with adjustable overcurrent threshold can adjust the value of VCE (DESAT) by adjusting the ZD1 parameter, that is, adjust the IGBT overcurrent threshold to adapt to IGBTs of different power ranges; adding a shaping circuit to the drive circuit can ensure the integrity of the drive signal in the case of long-distance transmission, and is suitable for high-power drivers. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a driving circuit diagram of the present invention; Figure 2 This is the shaping circuit diagram of the present invention. DETAILED DESCRIPTION
[0017] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0020] See also Figure 1-2 The present invention provides an IGBT driving circuit with adjustable overcurrent threshold, comprising a driving circuit and a shaping circuit. The driving circuit is used to adjust the IGBT overcurrent threshold after outputting a driving signal. The driving circuit comprises a driving chip U2, pull-up resistors R11, R12, R8, R7, a current limiting resistor R17, voltage zener diodes ZD2, ZD1, a capacitor C2, diodes D1, D2. The pull-up resistors R11 and R12 are connected in parallel and connected to the 14th and 12th pins of the driving chip U2 respectively. The current limiting resistor R17 is connected to the 10th pin of the driving chip U2. One end of the voltage zener diode ZD2 connected in parallel with the capacitor C2 is connected to the 2nd pin of the chip U2. The other end of the voltage zener diode ZD2 connected in parallel with the capacitor C2 is connected in sequence to the resistor R8, the voltage zener diode ZD1, the diodes D1, and D2. The cathode of the diode D2 is connected to the IGBT, and one end of the resistor R7 is connected between the resistor R8 and the diode ZD1. The model of diodes D1 and D2 is HFM108, the model of voltage regulator diode ZD2 is ISMA5925A, the model of driver chip U2 is NSI6651ASC, and C2 is a blanking capacitor.
[0021] The typical voltage value of the voltage regulator diode ZD2 is 10V. The voltage value of the DESAT pin (pin 2) of the driver chip U2 is generally 9V. The function of this voltage regulator diode ZD2 is to clamp the negative voltage of the DESAT pin. When the IGBT is turned on, the CE voltage of the IGBT drops, the DESAT diode junction capacitance of the driver chip U2 begins to discharge, and the energy begins to transfer to the blanking capacitor C2, causing negative voltage to be generated on the blanking capacitor C2. Then the internal switch is disconnected, and the current source begins to charge the external blanking capacitor C2, and the negative voltage is restored. The larger the junction capacitance, the greater the stored energy, and the greater the negative voltage caused. The negative pressure may damage the DESAT pin of the driver chip U2, increase the extra blanking time, and cause the IGBT to fail to protect in time when a short circuit occurs; the factor that has the greatest impact on the short circuit detection time is C2. The time to charge C2 directly determines the time when the DESAT voltage reaches the threshold. When a short circuit occurs, the voltage drop across VCE will rise rapidly. At this time, the high-voltage diodes D1 and D2 will be reverse biased, and the internal current source current will only flow in one direction, that is, charging C2. When the voltage drop across C2, that is, the VCE (DESAT) voltage, exceeds the threshold voltage, the short circuit protection will be triggered. R7 is a pull-up resistor, and this resistor parameter will also affect the short circuit detection time.
[0022] D1 and D2 are high-voltage diodes. For IGBT, their two ends usually bear very high voltage in the off state, so it is impossible to directly sample the voltage at both ends of the power tube; when it is normally turned on, the pull-up current source inside the chip flows out from the DESAT port and flows to the IGBT through R8, ZD1, D1, and D2. At this time, the VCE voltage when the power module triggers the DESAT protection is: VCE(DESAT) = V(DESAT)-V(ZD1)-V(D1)-V(D2)-I*R8 V (DESAT) is the fixed value of 9V of the driver chip U2, and I is the constant current source current inside U2. When the current passes through the IGBT, it is converted into a voltage signal through the internal resistance of the IGBT.
[0023] When designing a circuit, the value of VCE(DESAT) can be adjusted by adjusting the ZD1 parameter, that is, adjusting the IGBT overcurrent threshold to adapt to IGBTs of different power ranges.
[0024] The driving circuit also includes resistors R9, R15, and capacitor C4. One end of the resistors R9 and R15 connected in parallel is connected to the driving chip U2, and the other end of the resistors R9 and R15 connected in parallel is connected to the capacitor C4. R9, R15, and C4 prevent the output signal of the driving chip U2 from generating ringing. The driving circuit also includes an NPN transistor Q1 and a PNP transistor Q2. The model of the NPN transistor Q1 is ZXTN2010Z, and the model of the PNP transistor Q2 is ZXTP2012Z. The base of the NPN transistor Q1 is connected to the base of the PNP transistor Q2 and then connected to the other end of the resistors R9 and R15 connected in parallel. The collector and base of the PNP transistor Q2 are connected via a capacitor C4. The NPN transistor Q1 and the PNP transistor Q2 form a push-pull circuit to enhance the peak current output capability of the driving chip. The driving circuit also includes resistors R10, R13, and a switching diode D3. The model of the switching diode D3 is LBAV70LTIC. One end of the resistor R10 is connected to the emitter of the NPN transistor Q1, and one end of the resistor R13 is connected to the emitter of the PNP transistor Q2. The other ends of the resistors R10 and R13 are connected and connected to the collector of the NPN transistor Q1 through the switching diode D3. R10 and R13 are gate resistors to prevent false triggering of the driving signal.
[0025] The driving circuit also includes a resistor R14, a capacitor C3, and a transient suppression diode TVS1. The model of the transient suppression diode TVS1 is SMBJI6CAE3. One end of the resistor R14 and the capacitor C3 connected in parallel is connected to the switching diode D3, and the other end of the resistor R14 and the capacitor C3 connected in parallel is connected to the transient suppression diode TVS1. R14 and C3 are RC filters. The transient suppression diode TVS1 can clamp the driving voltage within 20V to prevent the driving voltage from being too high and damaging the IGBT.
[0026] The shaping circuit is used to ensure the integrity of the driving signal output by the driving circuit. The shaping circuit includes an inverter U1, pull-up resistors R1, R2, current limiting resistors R3, R5, and a filter capacitor C1. One end of the pull-up resistor R1 is connected to the inverter U1 through the current limiting resistor R5, and one end of the pull-up resistor R2 is connected to the inverter U1 through the current limiting resistor R3. The filter capacitor C1 is connected to the inverter U1. The model of the inverter U1 is 74HC14D. When the 1A pin input of U1 is a high level, the 1Y pin output of U1 is a low level. Adding a shaping circuit to the driving circuit can ensure the integrity of the driving signal in the case of long-distance transmission, which is suitable for high-power drivers.
[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. An IGBT drive circuit with adjustable overcurrent threshold, comprising a drive circuit for adjusting the IGBT overcurrent threshold after outputting a drive signal, the drive circuit comprising a drive chip U2, pull-up resistors R11, R12, a current limiting resistor R17, a voltage zener diode ZD2, and a capacitor C2, wherein: the pull-up resistors R11 and R12 are connected in parallel and connected to the drive chip U2 respectively, the current limiting resistor R17 is connected to the drive chip U2, and one end of the voltage zener diode ZD2 connected in parallel with the capacitor C2 is connected to the chip U2, characterized in that: The other end of the voltage zener diode ZD2 connected in parallel with the capacitor C2 is connected in sequence with a resistor R8, a voltage zener diode ZD1, diodes D1 and D2, one end of D2 is connected to the IGBT, and a resistor R7 is connected between the resistor R8 and the diode ZD1.
2. The IGBT driving circuit with adjustable overcurrent threshold according to claim 1, characterized in that: The driving circuit further includes resistors R9, R15 and a capacitor C4. One end of the resistors R9 and R15 connected in parallel is connected to the driving chip U2, and the other end of the resistors R9 and R15 connected in parallel is connected to the capacitor C4.
3. The IGBT driving circuit with adjustable overcurrent threshold according to claim 2, characterized in that: The driving circuit also includes an NPN transistor Q1 and a PNP transistor Q2. The base of the NPN transistor Q1 is connected to the base of the PNP transistor Q2 and then connected to the other end of the resistors R9 and R15 connected in parallel. The collector and base of the PNP transistor Q2 are connected via a capacitor C4.
4. The IGBT driving circuit with adjustable overcurrent threshold according to claim 3, characterized in that: The driving circuit also includes resistors R10, R13, and a switching diode D3. One end of the resistor R10 is connected to the emitter of the NPN transistor Q1, one end of the resistor R13 is connected to the emitter of the PNP transistor Q2, and the other ends of the resistors R10 and R13 are connected to the collector of the NPN transistor Q1 through the switching diode D3.
5. The IGBT driving circuit with adjustable overcurrent threshold according to claim 4, characterized in that: The driving circuit further includes a resistor R14 and a capacitor C3, and one end of the resistor R14 and the capacitor C3 connected in parallel is connected to a switching diode D3.
6. The IGBT driving circuit with adjustable overcurrent threshold according to claim 5, characterized in that: The driving circuit further includes a transient suppression diode TVS1, and the transient suppression diode TVS1 is connected to the other end of the resistor R14 and the capacitor C3 connected in parallel.
7. The IGBT driving circuit with adjustable overcurrent threshold according to claim 1, characterized in that: It also includes a shaping circuit for ensuring the integrity of the driving signal output by the driving circuit. The shaping circuit includes an inverter U1, pull-up resistors R1 and R2, current limiting resistors R3 and R5, and a filter capacitor C1. One end of the pull-up resistor R1 is connected to the inverter U1 through the current limiting resistor R5, one end of the pull-up resistor R2 is connected to the inverter U1 through the current limiting resistor R3, and the filter capacitor C1 is connected to the inverter U1.
8. The IGBT driving circuit with adjustable overcurrent threshold according to claim 2, characterized in that: The model of the driver chip U2 is NSI6651ASC.
9. The IGBT driving circuit with adjustable overcurrent threshold according to claim 7, characterized in that: The model of the inverter U1 is 74HC14D.