A driving method and device for IGBT

Abstract

The application relates to the technical field of power device driving, in particular to a driving method for an IGBT and a device, the method comprising the following steps: defining a first stage, a second stage, a third stage and a fourth stage of IGBT turn-on in sequence according to a time characteristic curve of IGBT turn-on; in the first stage, a first driving current is used to improve a voltage change rate of a gate-emitter voltage, so as to improve the turn-on rate of the IGBT; in the second stage, a second driving current is used to slow down a current change rate of a collector-emitter current, so as to inhibit the overshoot of the collector-emitter current; in the third stage, a third driving current is used to shorten the duration of a Miller platform; and in the fourth stage, a fourth driving current is used to make the voltage change rate of the collector-emitter voltage tend to be linear. The application has the advantages of improving the turn-on efficiency of the IGBT, providing current overshoot protection and reducing the power loss of the IGBT during the IGBT turn-on process.

Description

Technical Field

[0001] This application relates to the field of power device driving technology, and more specifically, to a driving method and device for IGBTs. Background Technology

[0002] IGBT stands for Insulated-Gate Bipolar Transistor, a type of bipolar device with a MOS structure. IGBTs combine the high-speed performance of MOSFETs with the low resistance of bipolar transistors, possessing advantages over both power transistors and electric field-effect transistors, thus having a wide range of applications. When used for switching control, IGBTs exhibit issues such as turn-on or turn-off delays, current overshoot, and voltage overshoot due to their inherent structural characteristics. Therefore, balancing and addressing the turn-on and turn-off speeds, reducing device losses, improving device reliability, and minimizing electromagnetic interference are core technical challenges in manufacturing high-performance IGBTs.

[0003] In existing technologies, the switching speed of an IGBT is often controlled by connecting a gate resistor in series. For example, by reducing the gate resistance, the equivalent capacitance C of the IGBT can be increased. GC and C GE Improving the charging speed of the IGBT increases its turn-on speed, but reducing the resistance increases the current flowing through the gate. This, combined with the parasitic inductance of the IGBT and the PIN diode, leads to current overshoot during turn-on and voltage overshoot during turn-off, potentially causing IGBT damage and reduced reliability. Increasing the gate resistance, while suppressing current and voltage overshoot and improving reliability, reduces the charging and discharging speed of the IGBT's equivalent capacitance, further decreasing turn-on and turn-off speeds and increasing power loss. Existing technologies also use active clamping to suppress voltage overshoot during IGBT turn-off. This method intervenes when the overshoot voltage exceeds an allowable threshold to prevent further overshoot. While providing overcharge protection, clamping can cause the IGBT to return to the linear region, prolonging the turn-off time and increasing power loss. Furthermore, active clamping cannot actively control voltage overshoot; it only passively activates when the overcharge voltage exceeds the allowable threshold, resulting in weak overshoot control and limited applicability. Therefore, the existing technical solutions cannot simultaneously achieve the reliability, startup efficiency, and device losses of IGBTs. Summary of the Invention

[0004] This application addresses the shortcomings of existing methods by proposing a driving method and device for IGBTs, thereby resolving the technical problem that related technologies cannot simultaneously achieve reliability, startup efficiency, and device losses.

[0005] In a first aspect, embodiments of this application provide a driving method for IGBTs, comprising: Based on the IGBT turn-on time characteristic curve, the first, second, third and fourth stages of IGBT turn-on are defined sequentially. In the first stage, the voltage change rate of the gate-emitter voltage is increased by the first drive current, which is used to improve the turn-on rate of the IGBT. In the second stage, the rate of change of the collector-emitter current is slowed down by the second drive current to suppress the overshoot of the collector-emitter current; In the third stage, the duration of the Miller platform is shortened by a third drive current; In the fourth stage, the collector-emitter voltage change rate is made linear by using a fourth driving current. Wherein, the third driving current is greater than the second driving current, and the first driving current and the fourth driving current are both greater than the third driving current.

[0006] Specifically, the main technical concept of this application is to control the IGBT drive current according to the IGBT turn-on stage, thereby improving the IGBT turn-on speed through a large current such as the first drive current, suppressing the IGBT current overshoot through a small current such as the second drive current, balancing the suppression of overshoot current and shortening the duration of the Miller plateau through a medium current such as the third drive current, and improving the linearity of the collector-emitter voltage change rate through a large current such as the fourth drive current. This improves the IGBT turn-on speed, provides IGBT current overshoot protection, and reduces IGBT device losses. In other words, this application has the advantages of improving IGBT turn-on efficiency, providing current overshoot protection, and reducing IGBT power losses during the IGBT turn-on process. It is understood that the first stage is defined as the time interval from when the IGBT is turned on to when the gate-emitter voltage equals the threshold voltage; the second stage is defined as the time interval from when the gate-emitter voltage reaches the Miller voltage from the threshold voltage or the time interval from when the gate-emitter voltage reaches the threshold voltage and when the collector-emitter voltage begins to generate a falling edge; the third stage is defined as the time interval during which the Miller plateau lasts or the time interval from when the collector-emitter voltage begins to generate a falling edge to when the gate-emitter voltage is greater than the Miller voltage; and the fourth stage is defined as the time interval from when the gate-emitter voltage begins to be greater than the Miller voltage to when the IGBT is fully turned on.

[0007] Furthermore, the IGBT driving method provided in this application includes: Based on the IGBT turn-off time characteristic curve, the fifth and sixth stages of IGBT turn-off are defined sequentially. In the fifth stage, the voltage change rate of the collector-emitter voltage is increased by the first turn-off current to improve the turn-off rate of the IGBT. In the sixth stage, the rate of change of the collector-emitter current is reduced by the second turn-off current to suppress the overshoot of the collector-emitter voltage. Wherein, the first turn-off current is greater than the second turn-off current.

[0008] Specifically, another technical concept of this application is to control the discharge current of the IGBT according to the IGBT disconnection stage, thereby improving the IGBT disconnection speed through a large discharge current such as the first turn-off current and suppressing the IGBT voltage overshoot through a small discharge current such as the second turn-off current, thus improving the IGBT disconnection speed and providing IGBT voltage overshoot protection. In other words, it simultaneously possesses the advantages of improving IGBT disconnection efficiency and providing voltage overshoot protection during the IGBT disconnection process. It can be understood that the fifth stage is defined as the time interval from the start of IGBT disconnection to the time interval from when the collector-emitter voltage begins to equal the steady-state voltage, and the sixth stage is defined as the time interval from when the collector-emitter voltage begins to equal the steady-state voltage until the IGBT is completely disconnected, with the first turn-off current being greater than the second turn-off current.

[0009] Furthermore, the IGBT driving method provided in this application includes: The drive current of the gate is controlled by the on / off state of the output terminal of the main control circuit connected to the gate, the first power supply circuit, and the second power supply circuit. The gate's turn-off current is controlled by a first discharge circuit and a second discharge circuit connected to the gate. The gate-emitter voltage and collector-emitter voltage used for stage transition are confirmed by the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit. The main control circuit includes an input terminal for receiving the reference voltage of the reference circuit; the main control circuit is connected to and controls the first power supply circuit, the second power supply circuit, the first discharge circuit, the second discharge circuit, the gate-emitter voltage detection circuit, and the collector-emitter voltage detection circuit, respectively.

[0010] Furthermore, the main control circuit controls the IGBT to turn on via the turn-on control module and controls the IGBT to turn off via the disconnection control module.

[0011] Furthermore, the activation control module includes: In the first stage, the output terminal, the first power supply circuit, and the second power supply circuit are simultaneously turned on. In the second stage, the output terminal is turned on; In the third stage, the output terminal and the first power supply circuit or the second power supply circuit are turned on. In the fourth stage, the output terminal, the first power supply circuit, and the second power supply circuit are simultaneously turned on.

[0012] Specifically, another technical concept of this application is that the IGBT can control the drive current in stages through specific circuits such as the main control circuit, the first power supply circuit, and the second power supply circuit.

[0013] Furthermore, the disconnection control module includes: In the fifth stage, both the first discharge circuit and the second discharge circuit are simultaneously turned on; In the sixth stage, the first discharge circuit is turned on; The first discharge circuit is configured as a ground terminal, and the second discharge circuit is configured with an active discharge device.

[0014] Furthermore, the IGBT driving method provided in this application further includes: confirming the collector-emitter current and the gate current by means of a collector-emitter current detection circuit and a gate current detection circuit connected to the main control circuit, respectively.

[0015] Optionally, the IGBT driving method provided in this application further includes: providing a reverse negative voltage through a buffer circuit connected between the output terminal and the gate.

[0016] Specifically, another technical concept of this application is to improve the discharge rate of IGBT disconnection by using the reverse negative voltage of the buffer circuit, thereby improving the IGBT disconnection efficiency.

[0017] Secondly, embodiments of this application provide a driving device for an IGBT, including a control component for driving the IGBT. The control component is used to implement the driving method for the IGBT as provided in any embodiment of the first aspect. The beneficial effects provided by any embodiment of the second aspect can be understood with reference to the beneficial effects provided by any embodiment of the first aspect.

[0018] Furthermore, the control component includes: The main control circuit includes an on-control module, an off-control module, and an output terminal. The output terminal is connected to the gate of the IGBT and is used to provide the first charging current. The reference circuit, connected to the main control circuit, is used to provide a reference voltage; The first power supply circuit is used to provide the second charging current; The second power supply circuit is used to provide the third charging current; The first discharge circuit is configured as the ground terminal of the main control circuit to provide the first discharge current. The second discharge circuit is used to provide the second discharge current; Gate-emitter voltage detection circuit, used to confirm the gate-emitter voltage; Collector-emitter voltage detection circuit, used to confirm collector-emitter voltage; The power-on control module is used to control the output terminal, the first power supply circuit, and the second power supply circuit according to the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit. The disconnection control module is used to control the first discharge circuit and the second discharge circuit based on the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit.

[0019] Specifically, another technical concept of this application is to realize the turn-on and turn-off control of IGBT through the above-mentioned circuit.

[0020] The beneficial technical effects of the technical solutions provided in this application include: In the IGBT turn-on process, a large first drive current is used in the first stage to increase the gate-emitter voltage change rate and accelerate the IGBT turn-on speed. Then, a small second drive current is used in the second stage to suppress the collector-emitter current change rate and prevent current overshoot. Next, a medium third drive current is used in the third stage to both suppress the collector-emitter current change rate and shorten the duration of the gate-emitter voltage maintenance Miller plateau, thereby reducing IGBT power loss. Finally, a large fourth drive current is used in the fourth stage to reduce the nonlinear effect of the Miller capacitance, making the final stage of the IGBT turn-on process more linear. Therefore, the IGBT driving method provided in this application can simultaneously improve IGBT turn-on speed, prevent current overshoot, and reduce device losses.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A schematic diagram of the composition of a device provided in an embodiment of this application; Figure 2 A flowchart illustrating a driving method for an IGBT provided in an embodiment of this application; Figure 3 A waveform diagram illustrating the IGBT turn-on process provided in an embodiment of this application; Figure 4 A waveform diagram illustrating the disconnection process of an IGBT provided in an embodiment of this application. Detailed Implementation

[0023] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0024] Those skilled in the art will understand that, unless specifically stated otherwise, the terms "described" and "the" as used herein may also include plural forms. It should be further understood that the term "comprising" as used in the specification of this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by this art. The term "and / or" as used herein refers to at least one of the items defined by the term; for example, "A and / or B" can be implemented as "A," or as "B," or as "A and B."

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0026] This application mainly relates to a driving method for IGBTs, which realizes phased control of IGBT turn-on by defining a first driving current, a second driving current, a third driving current and a fourth driving current in a first stage, a second stage, a third stage and a fourth stage respectively. It has the advantages of improving IGBT reliability, improving IGBT turn-on speed and reducing IGBT device losses.

[0027] The research and development approach of this application includes: dividing the IGBT turn-on process into four stages; during the time interval from the start of IGBT turn-on to the gate-emitter voltage equaling the threshold voltage, increasing the voltage change rate of the gate-emitter voltage through a first drive current, thereby improving the initial turn-on speed of the IGBT; during the time interval from the threshold voltage to the Miller voltage, or during the time interval when the gate-emitter voltage reaches the threshold voltage and the collector-emitter voltage begins to generate a falling edge, slowing down the current change rate of the collector-emitter current through a second drive current, thereby avoiding... In the period of current overshoot, or from the time interval of the Miller plateau to the time interval from the falling edge of the collector-emitter voltage to the time interval when the gate-emitter voltage is greater than the Miller voltage, the third drive current is used to both suppress current overshoot and shorten the duration of the Miller plateau, thereby improving the turn-on speed of the IGBT in the middle stage and reducing the device loss of the IGBT. In the time interval from the time when the gate-emitter voltage starts to be greater than the Miller voltage to the time when the IGBT is fully turned on, the fourth drive current is used to improve the linearity of the voltage change rate of the collector-emitter voltage, making the full conduction process of the IGBT more linear and reducing device loss.

[0028] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0029] Alternatively, please refer to Figure 1 This is a schematic diagram of the composition of a driving device for an IGBT provided in an embodiment of this application.

[0030] Specifically, an IGBT includes a gate (G), a collector (C), and an emitter (E). The voltage between the gate and the emitter is called the gate-emitter voltage, abbreviated as V. GE The voltage between the collector and emitter is called the collector-emitter voltage, abbreviated as V. CE The current between the collector and emitter is called the collector-emitter current, or I for short. CE Gate current, abbreviated as I G The collector is configured with a terminal voltage, which is V. DC End, V DC The voltage at the terminal is defined as V. DC Meanwhile, the working principle of IGBT is based on applying a positive drive voltage V between the gate and emitter. GE This allows the collector and emitter to be switched on, thus enabling the IGBT to turn on. Similarly, with the collector and emitter switched on, the drive voltage V between the gate and emitter is removed. GEThis disconnects the collector and emitter, thus enabling the IGBT to turn off; that is, the IGBT has switching characteristics. The driving voltage value at which the collector and emitter begin to turn on is defined as the turn-on threshold, or V for short. TH .

[0031] Optionally, a driving device for IGBTs provided in this application includes: The main control circuit includes an on / off control module, an off / on control module, and an output terminal connected to the gate of the IGBT. The main control circuit is used to control the on / off state of the IGBT. It is understood that the main control circuit can be a microcontroller, integrated circuit, or chip, providing multiple functional pins, including at least input, output, acquisition, and ground terminals, to implement functions such as power supply operation, signal acquisition, signal output, and chassis grounding. In other words, any device in the prior art that can implement the above functions can be used as the main control circuit. Therefore, this application does not limit the specific implementation structure of the main control circuit; as long as the circuit can be used to implement the driving method provided in this application, it can be used as the main control circuit of this application.

[0032] The power-on control module is connected to the output terminal of the main control circuit, the first power supply circuit, and the second power supply circuit, respectively, and is used to control the magnitude of the drive current.

[0033] The control module is disconnected from the second discharge circuit to control the discharge current. It is understood that this application integrates the first discharge circuit into the ground terminal of the main control circuit; that is, the first discharge circuit discharges through ground or through the 0V housing. Therefore, the IGBT driver device provided in this application does not require an additional first discharge circuit; the first discharge circuit is configured as the ground terminal of the main control circuit.

[0034] Optionally, the power-on control module and the power-off control module can be configured as connected independent chips, integrated circuits, or microcontrollers. That is, when the power-on control module and the power-off control module are configured independently, the main control circuit is a circuit composed of two independent devices.

[0035] The first and second power supply circuits are configured as DC sources, which can be implemented by replicating a bandgap reference current source using a common-source cascode current mirror. It is understood that any prior art circuit that can provide a DC source can be used as the first and second power supply circuits of this application.

[0036] The second discharge circuit is configured as an active discharge loop. It is understood that any circuit capable of active discharge in the prior art can be used as the second discharge circuit of this application.

[0037] The switching on and off of the first power supply circuit, the second power supply circuit, and the second discharge circuit can be achieved using switching devices. For example: when the first power supply circuit needs to be turned on, the turn-on control module sends a trigger signal to the switching device of the first power supply circuit, causing the switching device to turn on and thus turning on the first power supply circuit. When the trigger signal is removed, the switching device turns off and thus turning off the first power supply circuit. The switching on and off of the second power supply circuit and the second discharge circuit can be understood by referring to the example of the switching on the first power supply circuit.

[0038] A reference circuit, connected to the input of the main control circuit, provides a voltage reference and supplies power to the main control circuit when needed. It can be configured as a reference circuit that cancels out temperature change coefficients by superimposing positive and negative temperature coefficient currents to generate a stable and accurate reference voltage, abbreviated as Vref. It is understood that any existing circuit capable of providing a stable and accurate reference voltage can be used as the reference circuit of this application.

[0039] The buffer circuit and the reverse voltage circuit are located between the main control circuit and the gate. The buffer circuit can charge and discharge the bootstrap capacitor through multi-stage inverter cascade. By utilizing the non-abrupt voltage of the capacitor, the reverse voltage circuit provides a negative voltage between the gate and the main control circuit. This, in turn, increases the voltage difference between the gate and the ground terminal of the main control circuit, thereby accelerating the discharge effect of the first discharge circuit / ground terminal, improving the IGBT's disconnection speed, and further reducing device losses.

[0040] The gate current detection circuit, located at the gate terminal, is used to confirm I. G The gate current detection circuit can be configured with a non-inductive resistor to improve IC. G The sampling accuracy.

[0041] The gate-emitter voltage detection circuit has one end connected to the gate and the other end connected to the emitter, and can be configured as a high-precision resistor.

[0042] Collector-emitter current detection circuit, with an emitter terminal set up, is used to confirm I. CE The collector-emitter current detection circuit can be configured as a dI / dt circuit to confirm I. CE The rate of change of current.

[0043] The collector-emitter voltage detection circuit has one end connected to the collector and the other end connected to the emitter to confirm V. CE .

[0044] Optionally, the collector-emitter voltage detection circuit is equipped with a sampling high-voltage fast recovery diode, with its positive terminal connected to the collector and its negative terminal connected to the sampling terminal of the main control circuit. The sampling high-voltage fast recovery diode can reverse-bias cut off when the IGBT is off, isolating the bus high voltage from subsequent circuits. Simultaneously, it can forward-bias conduct when the IGBT is on, thereby achieving V... CE The detection, thereby achieving V CE Detection of the falling edge.

[0045] Optionally, this application also includes a collector-emitter differentiator circuit, one end of which is connected to the collector and the other end to the emitter, for confirming dV. CE / dt. It is understandable that the collector-emitter differentiator circuit is configured as an RC network to achieve V. CE Detection of voltage change rate.

[0046] It is understood that any circuit that can detect current or voltage in the prior art can be used as the detection circuit included in this application.

[0047] Combination Figure 1 Please refer to Figure 2 and Figure 3 This application describes a driving method for IGBTs. Figure 2 This is a flowchart illustrating a driving method for an IGBT provided in an embodiment of this application. Figure 3 A waveform diagram illustrating the IGBT turn-on process provided in an embodiment of this application.

[0048] Optionally, Figure 3 From top to bottom, they are V. GE Time curve, V CE / I CE Time curve (same as curve V) CE and I CE This allows for a more intuitive display of power consumption between the collector and emitter. G Time curve and P ON Time curve, P ON This refers to the IGBT's turn-on power, i.e., the power consumed between the collector and emitter during the IGBT's turn-on process. The dashed line running vertically through the IGBT indicates the correlation between various parameters at each stage. Therefore, the workflow of the IGBT driving method provided in this application is as follows: After the main control circuit controls the IGBT to turn on, the IGBT drive enters the first stage, driving the gate through the first drive current. The first stage refers to the time interval from t0 to t1, defined as V. GE From 0V to V TH The time interval, since IGBT can be equivalent to C GE CGC and C EC Three capacitors, due to the charging effect of the capacitors, V GE It cannot mutate; it can only grow from 0. (In V) GE The activation threshold V has not been reached. TH At this time, the collector and emitter are in an open state. The longer the first stage lasts, the lower the IGBT's turn-on efficiency. Therefore, in the first stage, the turn-on control module simultaneously controls the output terminal, the first power supply current, and the second power supply circuit to conduct, so that the first drive current I in the first stage... G =I1+I2+I3, which means that the first driving current of the first stage is achieved. Due to the charging effect of the large current, the equivalent capacitance C can be shortened. GE and C GC The charging time, i.e., increasing V GE The rate of change of voltage, shortening V GE From 0V to V TH This allows for adjustments to the IGBT's conduction time, thereby improving its efficiency. Therefore, during the time interval from t0 to t1, according to V... GE Time curve, V GE Increase from 0V to V TH This initiates conduction between the collector and emitter. Since the collector and emitter are not yet conducting in the first stage, according to V... CE Time curve, V CE Maintain at V DC According to I CE Time curve, I CE The value is 0, according to P ON Time curve, P ON The value is 0, and the IGBT does not generate power consumption. Since the gate is charged simultaneously through the output terminal, the first power supply circuit, and the second power supply circuit in the first stage, according to I... G Time curve, I G This refers to a large current. It can be understood that I1 refers to the first charging current at the output of the main control circuit, I2 refers to the second charging current of the first power supply circuit, and I3 refers to the third charging current of the second power supply circuit. It can be understood that I... G The magnitude and direction of the current change with the stage.

[0049] Therefore, the first stage t0 can be started based on the reference voltage Vref of the reference circuit, while t1 is based on V... GE The beginning is equal to V TH It can be determined that the main control circuit can determine V based on the gate-emitter voltage detection circuit. GE Sampling is performed when V GE =V THAt this time, the main control circuit can cut off the first and second power supply circuits by turning on the control module, allowing the IGBT drive to enter the second stage. GE Is it equal to V? TH This can be achieved using a comparator integrated into the main control circuit.

[0050] After the first stage ends, the second stage begins, where the gate is driven by a second drive current. Because in the second stage, V... GE Start greater than V TH Conduction begins between the collector and emitter, I CE It begins to gradually increase. Simultaneously, based on the reverse recovery current of the IGBT's equivalent PIN diode, it will cause I... CE The current exceeding its own steady-state current, refer to I in the figure. RR The identified spike pulse, I RR It refers to I CE The portion of the current exceeding the steady-state current during the continuous growth process, i.e., I RR This is an overshoot current. Excessive I RR This will lead to damage to the IGBT, causing a decrease in its stability. Furthermore, due to the voltage division effect of the IGBT's equivalent inductance, V... CE The decrease was somewhat observed, but it did not begin to decline significantly. Therefore, the second stage refers to the time interval from t1 to t2, in order to suppress I... CE Due to the rapid overshoot, the turn-on control module disconnects both the first and second power supply circuits, meaning the gate is driven only through the output terminal, causing the second drive current I in the second stage to... G =I1, because I G A smaller value can reduce the charging rate of the equivalent capacitor, which in turn can reduce I. CE The rate of change of current, and thus the effect on I RR Suppress and avoid I RR Excessive voltage can damage the IGBT, thus improving the reliability of the IGBT drive. Therefore, taking the time interval from the threshold voltage to the Miller voltage of the gate-emitter voltage as an example, within the time interval t1 to t2, according to V... GE Time curve, V GE From V TH Increase to V PT V PT This refers to Miller voltage, based on V CE Time curve, V CE Maintain at V DC Nearby, and decreases according to the voltage division of the IGBT's equivalent inductance, according to I CE Time curve, I CE It starts increasing from 0. Because P ON =V DC ×I CE According to PON Time curve, P ON It also starts increasing from 0. Furthermore, in the second stage, the gate is charged only through the output terminal, according to I... G Time curve, I G It is a small current. Understandably, I CE The steady-state current refers to the stable current after the collector and emitter have completed conduction. V PT This refers to the potential difference across the equivalent Miller capacitance of the IGBT. The Miller capacitance is the capacitance connected between the output and input terminals of an amplifier. Based on the characteristics of the Miller capacitance, V... GE In V PT The term "V" refers to a period of time that is sustained, i.e., the Miller plateau phenomenon. GE Maintain at V for a certain period of time PT Meanwhile, the longer the Miller plateau phenomenon lasts, the greater the power loss of the IGBT.

[0051] Optionally, the second stage can also be defined as the time interval between the gate-emitter voltage reaching the threshold voltage and the collector-emitter voltage starting to generate a falling edge. The IGBT power characteristic curve within this time interval can be understood by referring to the IGBT power characteristic curve of the second stage defined as the time interval between the gate-emitter voltage reaching the Miller voltage from the threshold voltage. Figure 3 To understand.

[0052] Therefore, t2 in the second stage can be determined based on V. GE The beginning is equal to V PT It can be determined that the main control circuit can determine V based on the gate-emitter voltage detection circuit. GE Sampling is performed when V GE =V PT At this time, the main control circuit can activate either the first or second power supply circuit via the activation control module, causing the IGBT drive to enter the third stage. Simultaneously, the second stage's t2 can also be adjusted based on V. CE Whether a falling edge has started to occur can be determined by the main control circuit, which can confirm V based on the collector-emitter voltage detection circuit. CE The falling edge, thus when V CE When a falling edge appears, the main control circuit can activate either the first or second power supply circuit via the turn-on control module, causing the IGBT drive to enter the third stage. It is understandable that V... GE =V PT and V CE The appearance of a falling edge can be achieved using a comparator built into the main control circuit.

[0053] After the second stage, the third stage begins, where the gate is driven by the third drive current. Due to the Miller plateau phenomenon in the third stage, V... GEMaintain at V PT The collector and emitter are continuously connected, V CE It began to gradually decrease, I CE After the reverse recovery current of the equivalent PIN diode ends, the current remains at a steady state. That is, the longer the Miller plateau lasts, the higher the P... ON The longer the duration, the greater the power loss of the IGBT. Therefore, the second stage refers to the time interval from t2 to t3, in order to suppress I... CE To mitigate overshoot and shorten the duration of the Miller plateau phenomenon, the control module activates either the first or second power supply circuit. This is achieved by driving the gate through the output terminal and the first or second power supply circuit, which is the third drive current I in the third stage. G =I1+I2 / I3, since I G Maintaining a medium current state can simultaneously suppress Ic CE This reduces overshoot and enhances the charging effect of the equivalent Miller capacitance, shortening the duration of the Miller plateau phenomenon, thereby shortening the IGBT's turn-on time and reducing its power consumption. Therefore, taking the time interval from the threshold voltage to the Miller voltage of the gate-emitter voltage as an example, within the time interval t2 to t3, according to V... GE Time curve, V GE Continue to maintain at V PT Meanwhile, the IGBT remains on, according to V. CE Time curve, V CE The current continues to decrease, and after the equivalent PIN diode reverse recovery current ends, I... CE To restore the steady-state current, according to I CE Time curve, I CE After the pulse spike ends, maintain the steady-state current. According to P... ON Time curve, P ON It begins to gradually decrease from the peak value. Furthermore, in the third stage, the gate is charged through the output terminal and either the first or second power supply circuit, according to I... G Time curve, I G It is a medium current.

[0054] Therefore, t3 in the third stage can be determined based on V. GE Start greater than V PT It can be determined that the main control circuit can determine V based on the gate-emitter voltage detection circuit. GE Sampling is performed when V GE >V PT At this time, the main control circuit can simultaneously turn on the first and second power supply circuits by activating the control module, causing the IGBT drive to enter the fourth stage. It can be understood that V GE >V PTThe determination can be achieved through the comparator built into the main control circuit.

[0055] Optionally, the current in the first power supply circuit and the second power supply circuit can be the same or different.

[0056] After the third stage ends, the fourth stage begins, where the gate is driven by the fourth drive current. Because in the fourth stage, V... GE Start greater than V PT A deep conductive connection begins between the collector and emitter, V CE Continue to drop to 0V, I CE The current remains at steady state. Due to the nonlinear characteristics of the IGBT's equivalent Miller capacitance, V CE The reduction also exhibits nonlinearity. To make the IGBT conduction process linear, the turn-on control module controls the first and second power supply circuits to turn on simultaneously. That is, the gate is driven simultaneously through the output terminal, the first power supply circuit, and the second power supply circuit, which is the fourth drive current I in the fourth stage. G =I1+I2+I3, since I G Maintaining a high current state can reduce the nonlinear effect of the IGBT's equivalent Miller capacitance, making the IGBT's conduction process more linear. Therefore, within the time interval from t3 to t4, according to V... GE Time curve, V GE From greater than V PT The saturation voltage is reached. Simultaneously, the IGBT is fully turned on, according to V... CE Time curve, V CE The voltage drops to 0V, according to I CE Time curve, I CE Maintain steady-state current. According to P ON Time curve, P ON Reduced to 0. Furthermore, the fourth stage charges the gate through the output terminal and the first and second power supply circuits, according to I... G Time curve, I G This refers to a large current. It's understandable that the saturation voltage refers to V... GE The maximum supply voltage, i.e., VCC as shown in the diagram.

[0057] Therefore, the fourth stage is the deep conduction stage of the IGBT, and its duration is determined by the IGBT's disconnection time. When the IGBT begins to disconnect according to Verf, the fourth stage ends, and the IGBT enters the disconnection stage.

[0058] Optionally, combined Figure 1 Please refer to Figure 4 A waveform diagram illustrating the disconnection process of an IGBT provided in an embodiment of this application.

[0059] Based on the reference voltage, the main control circuit controls the IGBT to begin disconnecting. After this, the IGBT drive enters the fifth stage. The turn-on control module controls the output terminal, the first power supply circuit, and the second power supply circuit to disconnect simultaneously. The disconnection control module controls the buffer circuit, the reverse voltage circuit, and the second discharge circuit to turn on simultaneously. At this time, the first and second discharge circuits discharge the gate simultaneously. Since the IGBT disconnection is the reverse process of the IGBT turn-on, according to V... GE The time curve shows that the IGBT will first exit the deep conduction state, i.e., V. GE Reduce from VCC to V PE Then it reaches a continuous conduction state, i.e., V GE Maintain V PE The state remains unchanged, and finally, it begins to disconnect from the continuously conducting state until the IGBT is completely disconnected, i.e., V. GE From V PE Start descending until V EE Accordingly, according to V CE Time curve, V CE After the IGBT exits the deep conduction state, the voltage increases from 0V. Due to the influence of the IGBT's parasitic inductance, V... CE After reaching the steady-state voltage, a pulse spike will appear, which is the overshoot voltage V. OV After the effect of parasitic inductance ends, V CE It will recover to the steady-state voltage V. DC At the same time, according to I CE The time curve shows that, within the IGBT deep conduction and continuous conduction states, I... CE The steady-state current will remain constant. When the IGBT begins to disconnect, ICE gradually decreases to 0, and the IGBT is completely disconnected. According to P... OFF Time curve, P OFF In V CE It is generated when it begins to increase, I CE It gradually decreases as it begins to decline. That is, P... OFF Will follow V CE V increases with the increase of V CE The longer the voltage increase from 0V to the peak value, the greater the power loss of the IGBT. Additionally, V OV The larger the value, the greater the likelihood of damage to the IGBT. Based on the parasitic inductance of the IGBT, V... OV The size is also related to I CE It is related to the rate of change of current; the greater the rate of change of current, the higher V. OV The larger. Therefore, the fifth stage refers to Figure 4 The middle term refers to the time interval from t0 to t2, i.e., V. CE The time at which the voltage begins to equal the steady-state voltage or V GE The time of the start and end of the plateau phenomenon or I CEThe time when the descent begins. In the fifth stage, the disconnect control module controls the simultaneous activation of the first and second discharge circuits, i.e., the first shutdown current I in the fifth stage. G =I4+I5, discharge is achieved through a large discharge current such as the first turn-off current, according to I G Time curve, I G With a large discharge current, charge flows out through the gate at an accelerated rate, thereby shortening V. CE The time to reach steady-state voltage reduces the IGBT's turn-off power loss. Simultaneously, the reverse voltage circuit can increase the discharge rate of the first discharge circuit, further reducing the IGBT's turn-off power loss. It can be understood that V... PE This refers to V during the IGBT disconnection process. GE Platform voltage, V EE This refers to V when the IGBT is completely disconnected. GE The potential difference, P OFF This refers to the power loss between the collector and emitter when the IGBT is turned off; the steady-state voltage refers to V. CE The stable voltage during IGBT disconnection depends on V. DC I4 refers to the first discharge current of the first discharge circuit, and I5 refers to the second discharge current of the second discharge circuit. The current directions of I4 and I5 are opposite to the current directions of I1, I2, and I3.

[0060] Therefore, t2 in the fifth stage can be determined according to V. CE The beginning is equal to V DC It can be determined that the main control circuit can determine V based on the collector-emitter voltage detection circuit. CE Sampling is performed when V CE =V DC At this time, the main control circuit can disconnect the second discharge circuit through the disconnection control module, causing the IGBT disconnection to enter the sixth stage. It can be understood that V CE =V DC The determination can be achieved through the comparator built into the main control circuit.

[0061] Alternatively, t2 in the fifth stage can also be based on I. CE The appearance of a falling edge confirms the start of I, meaning the main control circuit can determine I based on the collector-emitter current detection circuit. CE Sampling is performed when I CE When the falling edge begins to appear, the main control circuit can disconnect the second discharge circuit through the disconnection control module, so that the IGBT disconnection enters the sixth stage.

[0062] Alternatively, t2 in the fifth stage can also be based on V. GE Start End V PEThe plateau phenomenon or VGE is confirmed when a falling edge occurs during the VPE sustaining phase; that is, the main control circuit can detect the current based on the gate-emitter voltage to adjust VGE. GE Sampling is performed when I GE Starting less than V PE At this time, the main control circuit can disconnect the second discharge circuit by disconnecting the control module, so that the IGBT disconnection enters the sixth stage.

[0063] After the fifth stage, the sixth stage begins, during which the gate is discharged through the first discharge circuit / ground terminal. Because in the sixth stage, I... CE It begins to decrease, according to the parasitic inductance, I CE The greater the rate of change of current, the greater the parasitic inductance, V OV The larger the value, the more it is needed to prevent V from becoming larger. OV Excessive current can damage the IGBT. The main control current disconnects the second discharge circuit through the disconnect control module, which is the second turn-off current I in the sixth stage. G =I4, based on the small discharge current such as the second turn-off current, I can be suppressed. CE The rate of change of current, thus causing V OV This reduces costs, protects the IGBT, and improves the reliability of the IGBT driver.

[0064] In summary, this application provides a control method for IGBT turn-on, controlling the IGBT turn-on process through the drive currents corresponding to the first to fourth stages. Simultaneously, this application controls the IGBT turn-off process through the discharge currents corresponding to the fifth and sixth stages. The IGBT turn-on control circuit provided in this application includes a reference circuit, a turn-on control module, an output terminal, a first power supply circuit, a second power supply circuit, a gate-emitter voltage detection circuit, and a collector-emitter voltage detection circuit, used to control the IGBT turn-on. The IGBT turn-off control circuit provided in this application includes a reference circuit, a turn-off control module, a first discharge circuit, a second discharge circuit, and a collector-emitter voltage detection circuit, used to control the IGBT turn-off. That is, the circuit excluding the IGBT is the IGBT drive circuit, including a reference circuit, a main control circuit, an output terminal, a first power supply circuit, a second power supply circuit, a first discharge circuit, a second discharge circuit, a gate-emitter voltage detection circuit, a collector-emitter voltage detection circuit, a gate current detection circuit, a collector-emitter current detection circuit, a buffer circuit, and a reverse voltage circuit, used to control the IGBT turn-on and turn-off. The device provided in this application includes both IGBTs and control circuits, and is used to form integrated products, such as modules, chips or integrated circuits.

[0065] In summary, this application provides a driving method and device for an IGBT. The driving method includes: during the IGBT turn-on process, increasing the voltage change rate of the gate-emitter voltage through a first driving current in a first stage, thereby increasing the initial turn-on speed of the IGBT; slowing down the current change rate of the collector-emitter current through a second driving current in a second stage, thereby avoiding current overshoot; combining current overshoot suppression and shortening the duration of the Miller plateau through a third driving current in a third stage, thereby increasing the turn-on speed of the IGBT in the middle stage and reducing the device loss of the IGBT; and improving the linearity of the voltage change rate of the collector-emitter voltage through a fourth driving current in a fourth stage, making the full conduction process of the IGBT more linear and reducing device loss.

[0066] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in related technologies that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0067] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0068] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0069] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0070] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0071] The above description is only a partial implementation of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A driving method for IGBTs, characterized in that, include: Based on the IGBT turn-on time characteristic curve, the first, second, third and fourth stages of IGBT turn-on are defined sequentially. In the first stage, the voltage change rate of the gate-emitter voltage is increased by the first drive current, which is used to improve the turn-on rate of the IGBT. In the second stage, the rate of change of the collector-emitter current is slowed down by the second drive current to suppress the overshoot of the collector-emitter current; In the third stage, the duration of the Miller platform is shortened by a third drive current; In the fourth stage, the collector-emitter voltage change rate is made linear by using a fourth driving current. Wherein, the third driving current is greater than the second driving current, and the first driving current and the fourth driving current are both greater than the third driving current.

2. The IGBT driving method according to claim 1, characterized in that, include: Based on the IGBT turn-off time characteristic curve, the fifth and sixth stages of IGBT turn-off are defined sequentially. In the fifth stage, the voltage change rate of the collector-emitter voltage is increased by the first turn-off current to improve the turn-off rate of the IGBT. In the sixth stage, the rate of change of the collector-emitter current is reduced by the second turn-off current to suppress the overshoot of the collector-emitter voltage. Wherein, the first turn-off current is greater than the second turn-off current.

3. The IGBT driving method according to claim 2, characterized in that, include: The drive current of the gate is controlled by the on / off state of the output terminal of the main control circuit connected to the gate, the first power supply circuit, and the second power supply circuit. The gate's turn-off current is controlled by a first discharge circuit and a second discharge circuit connected to the gate. The gate-emitter voltage and collector-emitter voltage used for stage transition are confirmed by the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit. The main control circuit includes an input terminal for receiving the reference voltage of the reference circuit; the main control circuit is connected to and controls the first power supply circuit, the second power supply circuit, the first discharge circuit, the second discharge circuit, the gate-emitter voltage detection circuit, and the collector-emitter voltage detection circuit, respectively.

4. The IGBT driving method according to claim 3, characterized in that, include: The main control circuit controls the IGBT to turn on via the turn-on control module and controls the IGBT to turn off via the disconnect control module.

5. The IGBT driving method according to claim 4, characterized in that, The activation control module includes: In the first stage, the output terminal, the first power supply circuit, and the second power supply circuit are simultaneously turned on. In the second stage, the output terminal is turned on; In the third stage, the output terminal and the first power supply circuit or the second power supply circuit are turned on. In the fourth stage, the output terminal, the first power supply circuit, and the second power supply circuit are simultaneously turned on.

6. The IGBT driving method according to claim 5, characterized in that, The disconnection control module includes: In the fifth stage, both the first discharge circuit and the second discharge circuit are simultaneously turned on; In the sixth stage, the first discharge circuit is turned on.

7. The IGBT driving method according to claim 6, characterized in that, Also includes: The collector-emitter current and gate current are confirmed by the collector-emitter current detection circuit and the gate current detection circuit connected to the main control circuit, respectively.

8. The IGBT driving method according to claim 3, characterized in that, Also includes: A reverse negative voltage is provided by a buffer circuit connected between the output terminal and the gate.

9. A driving device for an IGBT, comprising a control component for driving the IGBT, characterized in that, The control component is used to implement the driving method for IGBTs according to any one of claims 1-8.

10. The driving device for IGBT according to claim 9, characterized in that, The control component includes: The main control circuit includes an on-control module, an off-control module, and an output terminal. The output terminal is connected to the gate of the IGBT and is used to provide the first charging current. The reference circuit, connected to the main control circuit, is used to provide a reference voltage; The first power supply circuit is used to provide the second charging current; The second power supply circuit is used to provide the third charging current; The first discharge circuit is configured as the ground terminal of the main control circuit to provide the first discharge current. The second discharge circuit is used to provide the second discharge current; Gate-emitter voltage detection circuit, used to confirm the gate-emitter voltage; Collector-emitter voltage detection circuit, used to confirm collector-emitter voltage; The power-on control module is used to control the output terminal, the first power supply circuit, and the second power supply circuit according to the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit. The disconnection control module is used to control the first discharge circuit and the second discharge circuit based on the gate-emitter voltage detection circuit and the collector-emitter voltage detection circuit.

Images