IGBT gate drive circuit based on constant current source and vccs feedback and on-off method thereof

Abstract

This invention discloses an IGBT gate driving circuit and its switching method based on a constant current source and VCCS feedback, relating to the field of integrated circuit technology. The circuit includes a control enable module, a constant current source driving module, a current change rate detection and current extraction feedback module, and a voltage change rate detection and current injection feedback module. The control enable module integrates a Miller window comparator circuit and is connected to the constant current source driving module, the current change rate detection and current extraction feedback module, and the voltage change rate detection and current injection feedback module, respectively. The current output terminal of the constant current source driving module is connected to the IGBT gate. The current change rate detection and current extraction feedback module is connected to the IGBT gate. The Miller window valid signal output terminal of the control enable module is connected to the enable logic terminal of the voltage change rate detection and current injection feedback module. The voltage change rate detection and current injection feedback module is connected to the IGBT gate. This achieves the effect of suppressing turn-on current overshoot and turn-off voltage spikes.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an IGBT gate drive circuit based on a constant current source and VCCS feedback. Background Technology

[0002] Traditional IGBTs generally employ a driving architecture with a voltage source and a fixed gate resistor. The IGBT gate exhibits gate-emitter capacitance and nonlinear Miller capacitance, which are affected by the collector voltage V. CE Due to dynamic changes, the actual gate charging and discharging current fluctuates in real time with the device's operating state. This driving method can only achieve a global compromise adjustment by changing the gate resistance value. Increasing the switching speed can reduce switching losses, but it will bring problems such as turn-on current overshoot, turn-off voltage spikes, and increased electromagnetic interference. Slowing down the switching speed can suppress electrical stress, but it will significantly increase switching losses. It is difficult to achieve the optimal balance between switching losses and device stress. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of the present invention is that traditional voltage source drive cannot achieve fine dynamic control of the IGBT switching process.

[0004] To address the aforementioned problems, this invention discloses an IGBT gate drive circuit based on a constant current source and VCCS feedback, achieving the desired technical effects.

[0005] In a first aspect, the present invention provides an IGBT gate drive circuit based on constant current source and VCCS feedback. The IGBT gate drive circuit based on constant current source and VCCS feedback includes a control enable module, a constant current source drive module, a current change rate detection and current extraction feedback module, and a voltage change rate detection and current injection feedback module. The control enable module integrates a Miller window comparison circuit and is electrically connected to the constant current source drive module, the current change rate detection and current extraction feedback module, and the voltage change rate detection and current injection feedback module, respectively. The current output terminal of the constant current source drive module is connected to the gate terminal of the IGBT and is used to output constant charging current and constant discharging current. The current terminal of the current change rate detection and current extraction feedback module is connected to the gate terminal of the IGBT and is used to extract current from the gate terminal when the current change rate exceeds the threshold. The Miller window valid signal output terminal of the control enable module is connected to the enable logic terminal of the voltage change rate detection and current injection feedback module. The current terminal of the voltage change rate detection and current injection feedback module is connected to the gate terminal of the IGBT, and is used to inject current into the gate terminal when the Miller window is effective and the voltage change rate exceeds the threshold.

[0006] A further technical solution is that the control enable module also integrates a logic control signal generation circuit. The logic control signal generation circuit generates an on enable signal, an off enable signal, switching control signals for each module, and a start / stop control signal for the constant current source branch, based on the input pulse width modulation signal.

[0007] A further technical solution includes a gate end point holding module, wherein the voltage sampling terminal of the gate end point holding module is connected to the gate terminal of the IGBT, and the control output terminal is connected to the constant current source driving module, which is used to cut off the constant current source when the gate voltage reaches a preset upper limit and to cut off the constant current source when the gate voltage reaches a preset lower limit.

[0008] A further technical solution is that the constant current source driving module includes mutually independent constant current source branches for turning on and turning off; The constant current source branch for activation consists of a first operational amplifier, a first P-type MOS transistor, an activation current sampling resistor, and a first controlled switch transmission gate. The input terminal of the first operational amplifier is connected to the activation reference voltage, and the activation current sampling resistor is connected in series in the source power supply circuit of the first P-type MOS transistor. The shutdown constant current source branch consists of a second operational amplifier, a first N-type MOS transistor, a shutdown current sampling resistor, and a second controlled switch transmission gate. The input terminal of the second operational amplifier is connected to the shutdown reference voltage, and the shutdown current sampling resistor is connected in series in the source-to-ground circuit of the first N-type MOS transistor.

[0009] A further technical solution is that the current change rate detection and current extraction feedback module includes a current change rate detection unit and a current extraction type voltage-controlled current source unit. The current change rate detection unit includes a differential detection circuit, a gain amplification circuit, and a half-wave error generation circuit. The differential detection circuit picks up the current change rate sensing voltage by means of the parasitic inductance of the IGBT emitter. The half-wave error generation circuit has a built-in current change rate threshold reference source and a first comparator. It outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage. The current-draining voltage-controlled current source unit consists of a third operational amplifier, a second N-type MOS transistor, and a first sampling resistor, and generates a corresponding amount of drain current based on the error control voltage.

[0010] A further technical solution is that the voltage change rate detection and current injection feedback module includes a voltage change rate detection unit and a current injection type voltage control current source unit. The voltage change rate detection unit includes an RC differential sampling circuit, an overvoltage clamping circuit, and a half-wave error generation circuit. The RC differential sampling circuit consists of a high-voltage capacitor and a sampling resistor connected in series. The overvoltage clamping circuit consists of two diodes connected in reverse parallel and in parallel at the output of the RC differential sampling circuit. The half-wave error generation circuit has a built-in voltage change rate threshold reference source and a second comparator, and outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage. The current injection type voltage-controlled current source unit consists of a fourth operational amplifier, a second P-type MOS transistor, and a second sampling resistor, and generates an injection current of a corresponding magnitude according to the error control voltage. The enable signal of the voltage change rate detection and current injection feedback module is generated by AND logic operation on the turn-off enable signal output by the control enable module, the Miller window valid signal, and the voltage change rate over-limit signal output by the voltage change rate detection unit.

[0011] A further technical solution is that the Miller window comparison circuit inside the control enable module includes a voltage divider resistor network, a bidirectional voltage clamping diode, a Miller upper limit reference voltage source, a Miller lower limit reference voltage source, a third comparator, and a fourth comparator. The gate voltage of the IGBT is divided by a voltage divider network and clamped by a bidirectional voltage clamping diode, and then input to the inverting input of the third comparator and the non-inverting input of the fourth comparator, respectively. The non-inverting input of the third comparator is connected to the Miller upper limit reference voltage source, and the inverting input of the fourth comparator is connected to the Miller lower limit reference voltage source. The outputs of the third and fourth comparators are ANDed to output the Miller window valid signal.

[0012] A further technical solution is that the gate endpoint holding module includes a gate upper limit reference voltage source, a gate lower limit reference voltage source, a fifth comparator, and a sixth comparator; The non-inverting input of the fifth comparator is connected to the gate of the IGBT, the inverting input is connected to the gate upper limit reference voltage source, and the output generates an upper limit lock signal. The inverting input of the sixth comparator is connected to the gate of the IGBT, the non-inverting input is connected to the lower limit reference voltage source of the gate, and the output generates a lower limit lock signal. The upper limit lock signal is connected to the enable logic AND gate of the constant current source branch, and the lower limit lock signal is connected to the enable logic AND gate of the constant current source branch.

[0013] Secondly, the present invention provides an IGBT turn-on driving method, applied to the IGBT gate driving circuit based on constant current source and VCCS feedback described in any of the above embodiments, the method comprising: The control enable module outputs an on-control signal to drive the constant current source drive module to output a constant charging current to the IGBT gate. The current change rate detection and current extraction feedback module collects the IGBT turn-on current change rate in real time. When the current change rate exceeds the preset threshold, it extracts compensation current from the IGBT gate to adjust the net gate charging current.

[0014] Thirdly, the present invention provides an IGBT turn-off driving method, applied to the IGBT gate driving circuit based on constant current source and VCCS feedback described in any of the above embodiments, the method comprising: The control enable module outputs a turn-off control signal to drive the constant current source drive module to draw a constant discharge current from the IGBT gate. The control enable module acquires the gate voltage of the IGBT in real time through its integrated Miller window comparator circuit. When the gate voltage falls into the voltage range corresponding to the Miller platform and the voltage change rate exceeds the preset threshold, the voltage change rate detection and current injection feedback module injects compensation current into the IGBT gate to adjust the net gate discharge current.

[0015] Compared with the prior art, the technical effects achieved by the embodiments of the present invention include: By combining constant current source main drive with dual-channel VCCS segmented feedback control, dynamic and precise adjustment of IGBT gate current is achieved, effectively suppressing turn-on current overshoot and turn-off voltage spikes while ensuring low switching losses. By integrating the Miller window comparator circuit into the control enable module, precise segmented control of feedback during the turn-off stage is achieved, avoiding invalid feedback in non-critical stages. The overall system adopts a fully analog MOS + operational amplifier architecture, eliminating the need for digital sampling units. The circuit structure is simple, with low temperature drift and strong anti-interference capability, and is compatible with the integration process of high-voltage monolithic power drive chips. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the IGBT gate drive circuit structure based on constant current source and VCCS feedback; Figure 2 This is the circuit diagram of the constant current source driver module; Figure 3 This is a schematic diagram of a current-extracting voltage-controlled current source unit circuit. Figure 4 This is the circuit schematic of the current change rate detection unit; Figure 5 This is a schematic diagram of a current injection type voltage-controlled current source unit circuit. Figure 6 This is the circuit schematic of the voltage change rate detection unit; Figure 7 This is a schematic diagram of a Miller window comparator circuit. Figure 8 Schematic diagram of the gate endpoint holding module circuit. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Similar component reference numerals in the drawings represent similar components. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0020] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] This invention provides an IGBT gate drive circuit based on a constant current source and VCCS feedback. The IGBT gate drive circuit includes a control enable module, a constant current source drive module, a current rate of change detection and current extraction feedback module, and a voltage rate of change detection and current injection feedback module. The control enable module integrates a Miller window comparator circuit and is electrically connected to the constant current source drive module, the current rate of change detection and current extraction feedback module, and the voltage rate of change detection and current injection feedback module, respectively. The current output terminal of the constant current source drive module is connected to the IGBT gate terminal to output a constant charging current and a constant discharging current. The current terminal of the current rate of change detection and current extraction feedback module is connected to the IGBT gate terminal to extract current from the gate terminal when the current rate of change exceeds a threshold. The Miller window valid signal output terminal of the control enable module is connected to the enable logic terminal of the voltage rate of change detection and current injection feedback module. The current terminal of the voltage rate of change detection and current injection feedback module is connected to the IGBT gate terminal to inject current into the gate terminal when the Miller window is valid and the voltage rate of change exceeds a threshold.

[0022] In this embodiment, the constant current source drive is a driving method that charges and discharges the IGBT gate with a constant current rather than a constant voltage. The gate current is not affected by the instantaneous gate voltage and Miller capacitance changes of the IGBT. VCCS (Voltage Controlled Current Source) refers to a current source whose output current is controlled by the input voltage. In this invention, it is divided into two types: current extraction type and current injection type. The Miller window, also known as the Miller window, refers to the voltage range where the gate voltage is in the Miller plateau during IGBT switching. During this stage, the collector voltage changes rapidly, which is the main stage for the generation of turn-off overshoot.

[0023] In a specific embodiment, see Figure 1 , Figure 1This diagram illustrates the structure of an IGBT gate drive circuit based on a constant current source and VCCS feedback. The current rate of change detection and current extraction feedback module includes a dV / dt detection module and a dV / dt feedback injection current VCCS. The voltage rate of change detection and current injection feedback module includes a di / dt detection module and a di / dt feedback extraction current VCCS. The control enable module integrates a Miller window comparator circuit, whose outputs are connected to the control terminals of the constant current source drive module, the current rate of change detection and current extraction feedback module, and the voltage rate of change detection and current injection feedback module, respectively, to output the enable signals and valid Miller window signals for each module. The current output terminal of the constant current source drive module is connected to the IGBT gate terminal VGR. During the turn-on phase, it outputs a constant charging current to charge the IGBT gate capacitor, and during the turn-off phase, it outputs a constant discharging current to extract charge from the IGBT gate. The current terminal of the current rate of change detection and current extraction feedback module is connected to the IGBT gate terminal VGR, acquiring the collector current change rate of the IGBT in real time. When the current change rate exceeds a preset threshold, it extracts current from the VGR node to reduce the net gate charging current. The Miller window valid signal output terminal of the control enable module is connected to the enable logic terminal of the voltage change rate detection and current injection feedback module. The current terminal of the voltage change rate detection and current injection feedback module is connected to the gate terminal VGR of the IGBT. Current is injected into the VGR node only when the Miller window is valid and the collector voltage change rate exceeds the preset threshold, thereby reducing the net gate discharge current.

[0024] It achieves an organic combination of constant current main drive and dual-channel VCCS feedback, fundamentally solving the contradiction between switching losses and electrical stress in traditional voltage source drive. By using Miller window to control the turn-off feedback in segments, it avoids ineffective feedback in non-critical stages and improves the stability of circuit operation.

[0025] Furthermore, the control enable module also integrates a logic control signal generation circuit, which generates an on enable signal, an off enable signal, switching control signals for each module, and a start / stop control signal for the constant current source branch based on the input pulse width modulation signal.

[0026] In this embodiment, the pulse width modulation (PWM) signal refers to the input control signal used to control the on / off state of the IGBT, and serves as the timing reference for the entire drive circuit. The enable signal refers to the logic level signal that controls the start or stop operation of the control circuit module; a high level indicates normal module operation, and a low level indicates module stop operation.

[0027] In a specific embodiment, the logic control signal generation circuit integrated within the control enable module uses the externally input PWM signal as the sole timing reference. It generates multiple control signals through internal logic gates: when the PWM signal is high, it generates an enable signal and outputs it to the constant current source drive module's constant current source branch, while simultaneously generating a current rate of change feedback enable signal and outputting it to the current rate of change detection and current extraction feedback module; when the PWM signal is low, it generates a disable enable signal and outputs it to the constant current source drive module's disable constant current source branch, while simultaneously inputting the disable enable signal to the enable logic AND gate of the voltage rate of change detection and current injection feedback module. Furthermore, the logic control signal generation circuit also generates control signals for the switches within each module and start / stop control signals for the constant current source branch, achieving timing coordination of the entire drive circuit.

[0028] All control signals are generated based on a single PWM signal, simplifying the external interface of the circuit; timing control is achieved through logic circuits, eliminating the need for a digital processor and improving the circuit's response speed and anti-interference capability.

[0029] Furthermore, it also includes a gate end point holding module, wherein the voltage sampling terminal of the gate end point holding module is connected to the gate terminal of the IGBT, and the control output terminal is connected to the constant current source driving module, which is used to cut off the constant current source when the gate voltage reaches a preset upper limit and to cut off the constant current source when the gate voltage reaches a preset lower limit.

[0030] In this embodiment, the gate end-holding module is used to automatically cut off the constant current source when the IGBT gate voltage reaches the upper limit of turn-on or the lower limit of turn-off, thus preventing the gate from being overcharged or over-discharged.

[0031] In a specific embodiment, a gate end-hold module is added, whose voltage sampling terminal is directly connected to the IGBT gate terminal VGR to acquire the gate voltage in real time. The gate end-hold module internally presets an upper limit value (usually 15V) and a lower limit value (usually -5V) for the gate voltage. When the gate voltage is detected to rise to the upper limit value, an upper limit lock signal is output to the turn-on constant current source branch of the constant current source drive module to cut off the turn-on constant current source and clamp the gate voltage at the turn-on upper limit. When the gate voltage is detected to drop to the lower limit value, a lower limit lock signal is output to the turn-off constant current source branch of the constant current source drive module to cut off the turn-off constant current source and clamp the gate voltage at the turn-off lower limit.

[0032] It effectively protects the IGBT gate insulation layer and extends the device's lifespan; the endpoint hold is achieved through hardware circuitry, resulting in fast response speed and no need for software intervention.

[0033] Furthermore, the constant current source driving module includes an independent turn-on constant current source branch and a turn-off constant current source branch; the turn-on constant current source branch consists of a first operational amplifier, a first P-type MOSFET, a turn-on current sampling resistor, and a first controlled switch transmission gate, with the input terminal of the first operational amplifier connected to the turn-on reference voltage, and the turn-on current sampling resistor connected in series in the source power supply circuit of the first P-type MOSFET; the turn-off constant current source branch consists of a second operational amplifier, a first N-type MOSFET, a turn-off current sampling resistor, and a second controlled switch transmission gate, with the input terminal of the second operational amplifier connected to the turn-off reference voltage, and the turn-off current sampling resistor connected in series in the source grounding circuit of the first N-type MOSFET.

[0034] In this embodiment, the operational amplifier (OTA) refers to a high-gain DC-coupled amplifier, which is used in this invention to form a negative feedback loop to achieve constant current control. The controlled switch transmission gate refers to a bidirectional analog switch composed of MOSFETs, used to control the on / off state of the circuit path.

[0035] In a specific embodiment, see Figure 2 , Figure 2 This is the circuit diagram of the constant current source driver module. The constant current source branch consists of the first operational amplifier OTA1, the first P-type MOSFET PM2, the turn-on current sampling resistor RI_ON, and the first controlled switch transmission gate. The non-inverting input of OTA1 is connected to the turn-on reference voltage (VCC) VREF. I_ON The inverting input is connected to the source of PM2, and the output is connected to the gate of PM2 through the first controlled switch transmission gate. RI_ON is connected in series between the source of PM2 and the power supply VCC. OTA1 adjusts the gate voltage of PM2 through negative feedback, making the voltage drop across RI_ON equal to VREF. I_ON Therefore, the turn-on current I ON =VREF I_ON / RI_ON, this current is determined only by the reference voltage and the sampling resistor, and is not affected by the IGBT gate voltage. The turn-off constant current source branch consists of the second operational amplifier OTA2, the first N-type MOSFET NM1, the turn-off current sampling resistor RI_OFF, and the second controlled switch transmission gate. Its working principle is the same as that of the turn-on constant current source branch, and the turn-off current I... OFF =VREF I_OFF / RI_OFF.

[0036] The constant current source is implemented using an OTA+MOS transistor+sampling resistor architecture, which abandons the traditional BJT solution. It has low temperature drift, good consistency, and is compatible with CMOS / BCD high voltage integration process. The turn-on and turn-off use independent constant current source branches, and the base speed of turn-on and turn-off can be adjusted separately, which is more flexible.

[0037] Furthermore, the current change rate detection and current extraction feedback module includes a current change rate detection unit and a current extraction type voltage-controlled current source unit; the current change rate detection unit includes a differential detection circuit, a gain amplifier circuit, and a half-wave error generation circuit. The differential detection circuit picks up the current change rate induced voltage using the parasitic inductance of the IGBT emitter. The half-wave error generation circuit has a built-in current change rate threshold reference source and a first comparator, and outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage; the current extraction type voltage-controlled current source unit consists of a third operational amplifier, a second N-type MOS transistor, and a first sampling resistor, and generates a corresponding extraction current based on the error control voltage.

[0038] In this embodiment, the half-wave error generation circuit refers to a circuit that outputs an error signal only when the input signal exceeds a preset threshold, used to prevent the feedback branch from malfunctioning under normal operating conditions. Emitter parasitic inductance refers to the inherent parasitic inductance between the emitter pin and the chip inside the IGBT package; its induced voltage is proportional to the rate of change of the collector current.

[0039] In a specific embodiment, see Figures 3-4 , Figure 3 This is a circuit schematic of a current-extracting type voltage-controlled current source unit. Figure 4 This is a circuit diagram of a current change rate detection unit. The current change rate detection unit includes a differential detection circuit, a gain amplifier circuit, and a half-wave error generation circuit. The differential detection circuit collects the induced voltage using the parasitic inductance Le of the IGBT emitter. When the IGBT is turned on, the change in collector current will generate an induced voltage vL = Le·diC / dt across Le. This induced voltage is then processed by a gain of K. OP The differential amplifier OP amplifies to obtain V di_on =K OP ·Le·diC / dt. Half-wave error generation circuit with built-in current change rate threshold reference source VREF. DI_ON And the first comparator, when V di_on ≤VREF DI_ON When the comparator outputs a low level, the error output VERR is displayed. DI =0, the feedback branch is not working; when V = 0, the feedback branch is not working; di_on VREF DI_ON When the comparator outputs a high level, the error amplifier EA outputs VERR. DI =K EA ·(V di_on -VREF DI_ON The current-deposited VCCS unit consists of a third operational amplifier OTA3, a second N-type MOSFET NM3, and a first sampling resistor R1. OTA3 uses negative feedback to make the voltage drop across R1 equal to VERR. DI Therefore, the current I is drawnFB_DI =VERR DI / R1, this current is drawn from the IGBT gate terminal VGR, resulting in a net gate charging current I G_ON =I ON -I FB_DI .

[0040] The current change rate is detected by utilizing the parasitic inductance of the IGBT's own emitter, eliminating the need for additional detection components and reducing circuit cost and size. A half-wave error generation circuit is used, which only activates feedback when the current change rate exceeds the limit, avoiding the impact of feedback on switching speed under normal operating conditions. The gate net current is directly adjusted through VCCS, resulting in fast response and significant suppression effect.

[0041] Specifically, Figure 3 The MOSFETs PM1, NM1, and INV1 form a transmission gate, which, along with NM2 and INV2, are switching circuits controlled by the output of the AND gate AND2. When the AND gate output is high, the transmission gate is open, NM2 is off, and the output voltage of OTA is transmitted to the gate of NM3, causing NM3 to conduct and begin drawing gate current from the IGBT. When the AND gate output is low, the transmission gate is closed, NM2 conducts, the gate voltage of NM3 is pulled low, NM3 is off, and the VCCS circuit is turned off. Figure 4 The differential detection circuit includes resistors R1, R2, R3, and R4; the gain amplifier circuit includes a differential amplifier OP; and the half-wave error generation section includes an error amplifier EA, a comparator CMP, inverters INV1 and INV2, resistors R5, R6, R7, and R9, and MOSFETs PM1, NM1, and NM2.

[0042] Furthermore, the voltage change rate detection and current injection feedback module includes a voltage change rate detection unit and a current injection type voltage-controlled current source unit. The voltage change rate detection unit includes an RC differential sampling circuit, an overvoltage clamping circuit, and a half-wave error generation circuit. The RC differential sampling circuit consists of a high-voltage capacitor and a sampling resistor connected in series. The overvoltage clamping circuit consists of two diodes connected in reverse parallel and in parallel at the output of the RC differential sampling circuit. The half-wave error generation circuit has a built-in voltage change rate threshold reference source and a second comparator, which outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage. The current injection type voltage-controlled current source unit consists of a fourth operational amplifier, a second P-type MOSFET, and a second sampling resistor, which generates an injection current of a corresponding magnitude based on the error control voltage. The enable signal of the voltage change rate detection and current injection feedback module is generated by performing an AND logic operation on the turn-off enable signal output by the control enable module, the Miller window valid signal, and the voltage change rate over-limit signal output by the voltage change rate detection unit.

[0043] In this embodiment, the RC differential sampling circuit is a circuit composed of a resistor and a capacitor connected in series. The output voltage is proportional to the rate of change of the input voltage and is used to detect the rate of voltage change. The overvoltage clamping circuit is a protective circuit that limits the maximum voltage at the circuit node to prevent damage to subsequent circuits due to input overvoltage.

[0044] In a specific embodiment, see Figures 5-6 , Figure 5 This is a schematic diagram of a current injection type voltage-controlled current source unit circuit. Figure 6 This is a circuit diagram of a voltage change rate detection unit. The voltage change rate detection unit includes an RC differential sampling circuit, an overvoltage clamping circuit, and a half-wave error generation circuit. The RC differential sampling circuit consists of a high-voltage capacitor CF and a sampling resistor RF connected in series. One end is connected to the collector of the IGBT, and the other end is grounded. Its output voltage V... dv_det =RF·CF·dV CE / dt. The overvoltage clamping circuit consists of two anti-parallel diodes connected in parallel at the output of the RC differentiating sampling circuit. When V dv_det When the voltage exceeds the diode's forward voltage, the diode conducts, clamping the output voltage within a safe range. The half-wave error generation circuit operates on the same principle as the current rate of change detection unit, and incorporates a built-in voltage rate of change threshold reference source VREF. DV When V dv_det VREF DV Output error voltage VERR DV =K DV ·(V dv_det -VREF DV The current-injection type VCCS unit consists of a fourth operational amplifier OTA4, a second P-type MOSFET PM3, and a second sampling resistor R1, with an injection current I. FB_DV =VERR DV / R1, this current is injected into the IGBT gate terminal VGR, making the net gate discharge current I G_OFF =I OFF -I FB_DV The enable signal for the voltage change rate detection and current injection feedback module is generated by three inputs and logic operations: a shutdown enable signal, a Miller window valid signal, and a voltage change rate over-limit signal. The feedback branch only starts working when all three conditions are met simultaneously.

[0045] An RC differentiating circuit is used for voltage change rate detection, which has a simple circuit structure and fast response speed. An overvoltage clamping circuit is added to effectively protect the subsequent low-voltage circuit. Multiple condition constraints for feedback are implemented through three-input AND logic to ensure that feedback is only initiated during the Miller window of the turn-off phase and when the voltage change rate exceeds the limit, thus avoiding malfunctions and loop interference.

[0046] Furthermore, the Miller window comparator circuit inside the control enable module includes a voltage divider resistor network, a bidirectional voltage clamping diode, a Miller upper limit reference voltage source, a Miller lower limit reference voltage source, a third comparator, and a fourth comparator. The gate voltage of the IGBT is divided by the voltage divider resistor network and clamped by the bidirectional voltage clamping diode, and then input to the inverting input of the third comparator and the non-inverting input of the fourth comparator, respectively. The non-inverting input of the third comparator is connected to the Miller upper limit reference voltage source, and the inverting input of the fourth comparator is connected to the Miller lower limit reference voltage source. The outputs of the third and fourth comparators are ANDed to output a Miller window valid signal.

[0047] In this embodiment, the voltage divider resistor network, consisting of two or more resistors connected in series, is used to proportionally reduce high voltage to a voltage range suitable for subsequent circuit processing. The bidirectional voltage clamping diode, consisting of two diodes connected in reverse series, can simultaneously limit both forward and reverse overvoltages.

[0048] In a specific embodiment, see Figure 7 , Figure 7 This is a schematic diagram of a Miller window comparator circuit. The Miller window comparator circuit includes a voltage divider resistor network R1 and R2, bidirectional voltage clamping diodes D1 and D2, and a Miller upper limit reference voltage source V. MH_REF Miller lower limit reference voltage source V ML_REF The third comparator is CMP1, and the fourth comparator is CMP2. The IGBT gate voltage VGR is divided by resistors R1 and R2 to obtain VGE. SENSE After being clamped bidirectionally by D1 and D2, the inputs are respectively fed into the inverting input of the third comparator CMP1 and the non-inverting input of the fourth comparator CMP2. The non-inverting input of the third comparator CMP1 is connected to V. MH_REF The inverting input of the fourth comparator CMP2 is connected to V. ML_REF When VGE SENSE <V MH_REF And VGE SENSE >V ML_REF At this time, both the third comparator CMP1 and the fourth comparator CMP2 output a high level, and after an AND logic operation, they output a high-level Miller window valid signal EN. MILLER Otherwise, output a low level, and the Miller window is invalid. Where V... MH_REF and V ML_REF These are the voltage values ​​after the upper and lower limits of the Miller plateau voltage are divided by the same voltage ratio, respectively.

[0049] By using voltage divider and clamping circuits to convert the high-voltage gate voltage into a signal suitable for processing by the low-voltage comparator, compatibility between high-voltage and low-voltage circuits is achieved. The use of dual comparators to implement window detection can accurately identify the Miller plateau stage of the IGBT, providing a reliable timing reference for segmented control of turn-off feedback.

[0050] Furthermore, the gate endpoint holding module includes a gate upper limit reference voltage source, a gate lower limit reference voltage source, a fifth comparator, and a sixth comparator; the non-inverting input of the fifth comparator is connected to the gate of the IGBT, the inverting input is connected to the gate upper limit reference voltage source, and the output generates an upper limit lock signal; the inverting input of the sixth comparator is connected to the gate of the IGBT, the non-inverting input is connected to the gate lower limit reference voltage source, and the output generates a lower limit lock signal; the upper limit lock signal is connected to the enable logic AND gate of the constant current source branch, and the lower limit lock signal is connected to the enable logic AND gate of the constant current source branch.

[0051] In this embodiment, the enable logic AND gate is a logic gate circuit that outputs a high level only when all inputs are high, and is used to implement multi-condition control.

[0052] In a specific embodiment, see Figure 8 , Figure 8 This is a schematic diagram of the gate end-point hold module circuit; the gate end-point hold module includes the gate upper limit reference voltage source VGE. MAX Gate lower limit reference voltage source VGE LOW The fifth comparator CMP5 and the sixth comparator CMP6. The non-inverting input of CMP5 is connected to the IGBT gate VGR, and the inverting input is connected to VGE. MAX When VGR≥VGE MAX At this time, CMP5 outputs a high-level upper limit lock signal H. hold The inverting input of the CMP6 is connected to the IGBT gate terminal VGR, and the non-inverting input is connected to VGE. LOW When VGR≤VGE LOW At this time, CMP6 outputs a high-level lower limit lock signal L. hold H hold With the enable signal EN ON After AND gate operation, a turn-off control signal for the constant current source is generated. When H hold When it is high, regardless of EN ON Regardless of the status, the constant current source was disconnected; L hold With the turn-off enable signal EN OFF After AND gate operation, a turn-off control signal is generated to turn off the constant current source. When L hold When the signal is high, the constant current source is turned off.

[0053] Automatic detection of the gate endpoint and cutoff of the constant current source are achieved through hardware comparators and logic gates, resulting in fast response and high reliability. By performing an AND operation between the latch signal and the enable signal, the endpoint holding is ensured to be triggered only during the corresponding on / off phase, thus avoiding logic conflicts.

[0054] This invention provides an IGBT turn-on driving method, applied to the IGBT gate driving circuit based on constant current source and VCCS feedback described in any of the above embodiments, the method comprising steps S11 to S12: S11, control the enable module to output an on control signal, drive the constant current source drive module to output a constant charging current to the IGBT gate; S12, the current change rate detection and current extraction feedback module collects the IGBT turn-on current change rate in real time. When the current change rate exceeds the preset threshold, it extracts compensation current from the IGBT gate to adjust the net gate charging current.

[0055] In this embodiment, the net gate charging current refers to the total current flowing into the IGBT gate during the turn-on phase, which is equal to the charging current output by the constant current source minus the current drawn from the feedback.

[0056] In a specific embodiment, when the externally input PWM signal goes high, the control enable module outputs a turn-on control signal to the constant current source drive module, starting the constant current source branch and outputting a constant charging current ION to charge the IGBT gate capacitor, causing the IGBT gate voltage VGE to rise. The current change rate detection and current extraction feedback module collects the IGBT collector current change rate diC / dt in real time. When diC / dt ≤ a preset threshold, the feedback branch does not work, the net gate charging current equals ION, and the IGBT turns on at the fastest speed. When diC / dt exceeds the preset threshold, the current extraction type VCCS unit extracts a compensation current IFB_DI from the IGBT gate, reducing the net gate charging current to I. ON -I FB_DI The rate of increase of VGE slows down, thus limiting diC / dt within a safe range. When VGE rises to the turn-on limit, the gate endpoint holding module outputs an upper limit lock signal, cutting off the turn-on constant current source, clamping VGE at the turn-on limit, and the IGBT enters a stable conduction state.

[0057] It achieves adaptive dynamic control of the IGBT turn-on process, turning on at the fastest speed under normal operating conditions to reduce switching losses; when the current change rate exceeds the limit, it automatically slows down the turn-on speed to suppress current overshoot and electromagnetic interference, thus balancing efficiency and reliability.

[0058] This invention provides an IGBT turn-off driving method, applied to the IGBT gate driving circuit based on constant current source and VCCS feedback described in any of the above embodiments, the method comprising steps S21 to S22: S21, control the enable module to output a turn-off control signal, drive the constant current source drive module to draw a constant discharge current from the IGBT gate; S22, the control enable module acquires the gate voltage of the IGBT in real time through its integrated Miller window comparator circuit. When the gate voltage falls into the voltage range corresponding to the Miller platform and the voltage change rate exceeds the preset threshold, the voltage change rate detection and current injection feedback module injects compensation current into the IGBT gate to adjust the net gate discharge current.

[0059] In this embodiment, the net gate discharge current refers to the total current flowing out of the IGBT gate during the turn-off phase, which is equal to the discharge current output by the constant current source minus the feedback injection current.

[0060] In a specific embodiment, when the externally input PWM signal goes low, the control enable module outputs a turn-off control signal to the constant current source drive module, starting the turn-off constant current source branch and outputting a constant discharge current IOFF to draw charge from the IGBT gate, causing VGE to begin to decrease. When VGE decreases to the Miller plateau range, the Miller window comparator circuit inside the control enable module outputs a high-level Miller window valid signal. At this time, if the collector voltage change rate dVCE / dt does not exceed the preset threshold, the feedback branch does not work, the net gate discharge current equals IOFF, and the IGBT turns off at the fastest speed; if dVCE / dt exceeds the preset threshold, the current injection type VCCS unit injects a compensation current I into the IGBT gate. FB_DV The net gate discharge current decreases to I. OFF -I FB_DV The rate of VGE decreases slowly, thus limiting dVCE / dt within a safe range and suppressing turn-off voltage spikes. When VGE drops to the lower turn-off limit, the gate endpoint holding module outputs a lower limit lock signal, cutting off the turn-off constant current source and clamping VGE at the lower turn-off limit, allowing the IGBT to enter a stable turn-off state.

[0061] This invention achieves refined segmented control of the IGBT turn-off process, initiating feedback only during the Miller plateau stage where voltage overshoot is most likely to occur. This effectively suppresses turn-off voltage spikes and Miller coupling-induced turn-on, while avoiding excessive influence of feedback on the turn-off speed, thus achieving an optimal balance between turn-off losses and voltage stress.

[0062] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0063] Furthermore, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0067] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0068] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An IGBT gate drive circuit based on a constant current source and VCCS feedback, characterized in that, This includes a control enable module, a constant current source drive module, a current change rate detection and current extraction feedback module, and a voltage change rate detection and current injection feedback module. The control enable module integrates a Miller window comparison circuit and is electrically connected to the constant current source drive module, the current change rate detection and current extraction feedback module, and the voltage change rate detection and current injection feedback module, respectively. The current output terminal of the constant current source drive module is connected to the gate terminal of the IGBT and is used to output constant charging current and constant discharging current. The current terminal of the current change rate detection and current extraction feedback module is connected to the gate terminal of the IGBT and is used to extract current from the gate terminal when the current change rate exceeds the threshold. The Miller window valid signal output terminal of the control enable module is connected to the enable logic terminal of the voltage change rate detection and current injection feedback module. The current terminal of the voltage change rate detection and current injection feedback module is connected to the gate terminal of the IGBT, and is used to inject current into the gate terminal when the Miller window is effective and the voltage change rate exceeds the threshold. The current change rate detection and current extraction feedback module includes a current change rate detection unit and a current extraction type voltage-controlled current source unit. The current change rate detection unit includes a differential detection circuit, a gain amplification circuit, and a half-wave error generation circuit. The differential detection circuit picks up the current change rate sensing voltage by means of the parasitic inductance of the IGBT emitter. The half-wave error generation circuit has a built-in current change rate threshold reference source and a first comparator. It outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage. The current-draining voltage-controlled current source unit consists of a third operational amplifier, a second N-type MOS transistor, and a first sampling resistor, and generates a corresponding amount of drain current based on the error control voltage.

2. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 1, characterized in that, The control enable module also integrates a logic control signal generation circuit, which generates an on enable signal, an off enable signal, switching control signals for each module, and a start / stop control signal for the constant current source branch based on the input pulse width modulation signal.

3. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 1, characterized in that, It also includes a gate end point holding module, wherein the voltage sampling terminal of the gate end point holding module is connected to the gate terminal of the IGBT, and the control output terminal is connected to the constant current source driving module, which is used to cut off the constant current source when the gate voltage reaches a preset upper limit and to cut off the constant current source when the gate voltage reaches a preset lower limit.

4. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 1, characterized in that, The constant current source drive module includes mutually independent constant current source branches for turning on and turning off. The constant current source branch for activation consists of a first operational amplifier, a first P-type MOS transistor, an activation current sampling resistor, and a first controlled switch transmission gate. The input terminal of the first operational amplifier is connected to the activation reference voltage, and the activation current sampling resistor is connected in series in the source power supply circuit of the first P-type MOS transistor. The shutdown constant current source branch consists of a second operational amplifier, a first N-type MOS transistor, a shutdown current sampling resistor, and a second controlled switch transmission gate. The input terminal of the second operational amplifier is connected to the shutdown reference voltage, and the shutdown current sampling resistor is connected in series in the source-to-ground circuit of the first N-type MOS transistor.

5. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 1, characterized in that, The voltage change rate detection and current injection feedback module includes a voltage change rate detection unit and a current injection type voltage control current source unit. The voltage change rate detection unit includes an RC differential sampling circuit, an overvoltage clamping circuit, and a half-wave error generation circuit. The RC differential sampling circuit consists of a high-voltage capacitor and a sampling resistor connected in series. The overvoltage clamping circuit consists of two diodes connected in reverse parallel and in parallel at the output of the RC differential sampling circuit. The half-wave error generation circuit has a built-in voltage change rate threshold reference source and a second comparator, and outputs an error control voltage only when the detected voltage is higher than the threshold reference source voltage. The current injection type voltage-controlled current source unit consists of a fourth operational amplifier, a second P-type MOS transistor, and a second sampling resistor, and generates an injection current of a corresponding magnitude according to the error control voltage. The enable signal of the voltage change rate detection and current injection feedback module is generated by AND logic operation on the turn-off enable signal output by the control enable module, the Miller window valid signal, and the voltage change rate over-limit signal output by the voltage change rate detection unit.

6. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 1, characterized in that, The Miller window comparison circuit inside the control enable module includes a voltage divider resistor network, a bidirectional voltage clamping diode, a Miller upper limit reference voltage source, a Miller lower limit reference voltage source, a third comparator, and a fourth comparator. The gate voltage of the IGBT is divided by a voltage divider network and clamped by a bidirectional voltage clamping diode, and then input to the inverting input of the third comparator and the non-inverting input of the fourth comparator, respectively. The non-inverting input of the third comparator is connected to the Miller upper limit reference voltage source, and the inverting input of the fourth comparator is connected to the Miller lower limit reference voltage source. The outputs of the third and fourth comparators are ANDed to output the Miller window valid signal.

7. The IGBT gate drive circuit based on constant current source and VCCS feedback according to claim 3, characterized in that, The gate endpoint holding module includes a gate upper limit reference voltage source, a gate lower limit reference voltage source, a fifth comparator, and a sixth comparator; The non-inverting input of the fifth comparator is connected to the gate of the IGBT, the inverting input is connected to the gate upper limit reference voltage source, and the output generates an upper limit lock signal. The inverting input of the sixth comparator is connected to the gate of the IGBT, the non-inverting input is connected to the lower limit reference voltage source of the gate, and the output generates a lower limit lock signal. The upper limit lock signal is connected to the enable logic AND gate of the constant current source branch, and the lower limit lock signal is connected to the enable logic AND gate of the constant current source branch.

8. An IGBT turn-on driving method, characterized in that, The method, applied to the IGBT gate drive circuit based on constant current source and VCCS feedback as described in any one of claims 1-7, comprises: The control enable module outputs an on-control signal to drive the constant current source drive module to output a constant charging current to the IGBT gate. The current change rate detection and current extraction feedback module collects the IGBT turn-on current change rate in real time. When the current change rate exceeds the preset threshold, it extracts compensation current from the IGBT gate to adjust the net gate charging current.

9. An IGBT turn-off driving method, characterized in that, The method, applied to the IGBT gate drive circuit based on constant current source and VCCS feedback as described in any one of claims 1-7, comprises: The control enable module outputs a turn-off control signal to drive the constant current source drive module to draw a constant discharge current from the IGBT gate. The control enable module acquires the gate voltage of the IGBT in real time through its integrated Miller window comparator circuit. When the gate voltage falls into the voltage range corresponding to the Miller platform and the voltage change rate exceeds the preset threshold, the voltage change rate detection and current injection feedback module injects compensation current into the IGBT gate to adjust the net gate discharge current.

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