CN105490511A

CN105490511A - T-type three-level IGBT drive circuit

Info

Publication number: CN105490511A
Application number: CN201511028961.4A
Authority: CN
Inventors: 何强; 黄辉; 汪之涵; 黄志平
Original assignee: Shenzhen Bronze Technologies Ltd
Current assignee: Shenzhen Bronze Technologies Ltd
Priority date: 2015-12-31
Filing date: 2015-12-31
Publication date: 2016-04-13

Abstract

The invention relates to a T-type three-level IGBT drive circuit, which is used for driving a three-level topology module. The T-type three-level IGBT drive circuit comprises a gate circuit, an over-voltage protection circuit and a secondary side signal processing module, wherein the gate circuit is connected with the three-level topology module and comprises an IGBT gate drive circuit which is used for converting a low-voltage IGBT switch control signal into a voltage signal capable of driving an IGBT switch; the over-voltage protection circuit is connected with the three-level topology module and the secondary side signal processing module respectively; the over-voltage protection circuit comprises an active clamp circuit; the active clamp circuit effectively suppresses a voltage spike when the IGBT is shut down through a transient suppression device with fast response characteristics; and the secondary side signal processing module at least has the function of monitoring a collector voltage. The T-type three-level IGBT drive circuit can suppress a shut-down voltage, and is high in control accuracy and small in system loss.

Description

T-shaped three-level IGBT driving circuit

Technical Field

The invention relates to a T-type three-level IGBT driving circuit, in particular to a T-type three-level IGBT driving circuit applied to a photovoltaic grid-connected inverter.

Background

The photovoltaic grid-connected power generation system mainly comprises a photovoltaic array module, an inverter, an alternating current filter and a power grid. The inverter is a key device for connecting the photovoltaic array module and the power grid, and is used for controlling the photovoltaic array module to operate at a maximum power point and injecting sinusoidal current into the power grid. The photovoltaic grid-connected inverter has extremely high requirements on the aspects of harmonic THD (total harmonic distortion), conversion efficiency, safety and reliability and the like. The traditional photovoltaic inverter adopts a two-level structure, adopts a circuit mode of common optical coupling isolation on an IGBT drive circuit, does not have the functions of overcurrent monitoring and IGBT overvoltage protection, and has certain defects. The power device with the two-level structure has large loss and low conversion efficiency, and the output harmonic THD of the inverter is large, so that a filter with a larger size is required. The common mode voltage variation rate of the two-level structure is large, which causes a large common mode current, and a more complicated EMI (electromagnetic interference) design is required to meet the safety requirement.

Three-level inverters have the following advantages over two-level inverters:

1. when the IGBTs with the same voltage level are used, the three-level inverter can increase the output voltage and power by one time; 2. in the application without high voltage, the three-level inverter allows the use of a lower-voltage IGBT module, so that the switching frequency of the IGBT can be improved; 3. the current on the power supply side of the three-level inverter is closer to sine than the current in the two levels, the sine is better, and the power factor is higher; 4. the collector voltage is not required to be static and dynamic symmetrical, so that the design of IGBT drive is simplified, and an external buffer circuit is avoided; 5. when the same switching frequency is used, the final output frequency can be doubled, which obviously helps to reduce the size of the passive components and to reduce the switching losses.

Although the three-level topology has more advantages than the two-level topology, the conventional three-level topology driving circuit is not perfect, for example, the voltage spike generated when the IGBT is turned off is generally higher than that of the two-level converter, so that more consideration needs to be given to suppressing the turn-off overvoltage.

Disclosure of Invention

The invention aims to provide a T-type three-level IGBT driving circuit capable of restraining turn-off overvoltage.

Therefore, the T-type three-level IGBT driving circuit provided by the invention is used for driving a three-level topological module and comprises a gate circuit connected with the three-level topological module, wherein the gate circuit comprises an IGBT gate driving circuit and is used for converting a low-voltage IGBT switch control signal into a voltage signal capable of driving an IGBT switch; the overvoltage protection circuit is respectively connected with the three-level topology module and the secondary side signal processing module and comprises an active clamping circuit, and the active clamping circuit effectively inhibits a voltage peak when the IGBT is switched off through a transient suppression device with a quick response characteristic; the secondary side signal processing module at least has a collector voltage monitoring function.

The IGBT power supply circuit has the advantages that the voltage spike when the IGBT is turned off is effectively restrained through the transient restraining device with the rapid response characteristic through the active clamping circuit, and the turn-off overvoltage can be restrained.

In the preferred scheme of the invention, the invention is easy to manufacture into a plug-and-play type, and has high control accuracy and small system loss.

Other advantages of the present invention are further illustrated by the examples.

Drawings

FIG. 1 is a circuit block diagram of an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of an embodiment of the present invention.

Fig. 3 is a schematic diagram of the plug and play principle of the embodiment of the present invention.

Fig. 4-1 is an application block diagram of the chip QD2011 in the embodiment of the present invention.

Fig. 4-2 is a schematic block diagram of the chip QD2011 in the embodiment of the present invention.

Fig. 4-3 are logic diagrams of input and output pins of the QD2011 according to embodiments of the present invention.

Fig. 4-4 are schematic block diagrams illustrating short-circuit protection of the chip QD2011 according to embodiments of the present invention.

Fig. 4 to 5 are schematic diagrams illustrating determination of the IGBT emitter voltage of the chip QD2011 in the embodiment of the present invention.

Fig. 4-6 are waveform diagrams of Fault port of the chip QD2011 in accordance with embodiments of the present invention.

Fig. 4-7 are schematic block diagrams of gate driving of the die QD2011 according to embodiments of the present invention.

Fig. 4-8 are schematic diagrams of active clamping operation of the chip QD2011 in an embodiment of the present invention.

Detailed Description

The following embodiments of the invention mainly aim to provide a plug-and-play T-type three-level IGBT driving circuit which is applied to a photovoltaic grid-connected inverter and has the advantages of high safety reliability, high control accuracy, low system loss and plug-and-play.

The technical problems to be solved are as follows:

1. through the active clamping circuit, the voltage spike of Vce (voltage between a collector and an emitter) generated in the turn-off process of the IGBT can be effectively inhibited, and the instantaneous voltage is prevented from exceeding the withstand voltage value of the IGBT;

2. the short-circuit protection circuit has a short-circuit protection function, and the short-circuit protection response time is adjusted by connecting a charging capacitor between the voltage monitoring port VCE of the collector of the chip and the ground terminal GND, and the longer the charging time of the capacitor is, the corresponding short-circuit response time is also increased;

3. the arranged gate pole protection circuit has a gate pole protection function, so that the voltage of the IGBT gate pole is ensured within a safety value range;

4. the provided gate driving circuit has a gate driving function, so that a low-voltage signal output by the chip is converted into a voltage signal which can be used for driving the IGBT to be switched on and switched off;

5. possesses plug-and-play function, according to IGBT module appearance structure, but the drive plate PCB lug weld of design uses on the IGBT pin.

Specifically, as shown in fig. 1, the plug-and-play T-type three-level driving circuit according to the embodiment of the present invention sequentially includes the following modules:

the plug-and-play functional module (fig. 3) is a driving installation mode which is simple to operate and compact in structure and can be used by directly welding a PCB (printed circuit board) of the plug-and-play functional module on an IGBT pin according to the corresponding IGBT module structure after a complete driving circuit and a protection circuit are designed;

the secondary side signal processing chip is combined with a peripheral circuit to form a secondary side signal processing module, and can realize a signal processing function, a short-circuit protection function, a collector voltage monitoring function, an IGBT (insulated gate bipolar transistor) on-off voltage regulation function, an under-voltage protection function, a fault management function, an IGBT gate driving signal conversion function, an active clamping function and the like;

the gate pole circuit is formed by jointly constructing an IGBT gate pole driving circuit, an IGBT on-off resistance separation circuit and an IGBT gate pole protection circuit;

the IGBT gate driving circuit is used for converting a low-voltage IGBT switch control signal in the chip into a voltage signal capable of driving an IGBT switch in a mode of improving the capacity of driving peak current by using an externally-connected MOSFET;

the IGBT turn-on and turn-off resistor separation circuit separates the gate resistor into a turn-on resistor and a turn-off resistor, can adjust the turn-on time and the turn-off time of the IGBT by the resistance values of the turn-on resistor and the turn-off resistor respectively, and can play a role in dispersing the power consumption of the switch;

an IGBT gate protection circuit, which connects the gate to the supply potential via a diode, so that the gate voltage is clamped below the supply voltage; the gate pole is connected with the emitting pole through a bidirectional voltage-stabilizing tube, so that V is_GEAt a stable value;

an overvoltage protection circuit comprising an active clamp circuit, a short circuit protection circuit and a voltage monitoring circuit;

the active clamping circuit effectively suppresses the voltage spike when the IGBT is turned off by the transient suppression device with the rapid response characteristic, and avoids the damage of the IGBT caused by overhigh transient voltage spike;

the short-circuit protection circuit judges whether the IGBT has a short-circuit fault by detecting the voltage of the collector in real time, and the short-circuit protection circuit is matched with the chip to output a fault signal and turn off the IGBT once the short-circuit condition occurs;

the voltage monitoring circuit comprises a VCE monitoring circuit and an active clamping monitoring circuit in the short-circuit protection function, and the VCE monitoring circuit and the active clamping monitoring circuit respectively play a role in information feedback in the short-circuit protection function and the active clamping function.

As shown in fig. 2, the Q4 transistor is used as an example, and the driving circuits of the remaining three transistors (Q1, Q2, Q3) are the same. The plug-and-play T-type three-level IGBT driving circuit comprises: the three-level topological module comprises a three-level topological module 1 consisting of 4T-shaped connected IGBT tubes, a secondary side signal processing chip 2, an overvoltage protection circuit 3, a gate pole circuit 4, a chip peripheral circuit 5 and a plug-and-play functional module.

The three-level topology module 1 comprises four IGBT tubes connected in a T shape and matched diodes thereof, wherein the Q1 tube and the Q4 tube are main tubes, the Q2 tube and the Q3 tube are auxiliary tubes, and the main tube is higher in voltage grade than the auxiliary tubes; the T-shaped connection is that the emitter of the Q1 tube is connected with the collector of the Q4 tube, the emitter of the Q2 tube is connected with the emitter of the Q3 tube, and the collector of the Q3 tube is connected with the common end of the Q1 tube and the Q4 tube; and a diode is connected between the emitter and the collector of each of the four IGBT tubes, and the diodes are respectively D1, D2, D3 and D4.

The secondary side signal processing chip 2 uses the QD2011 of shenzhen bronze sword science and technology limited company, and the pin definition is shown in the following table 1 (other detailed descriptions of the chip are shown later), the chip can realize a short-circuit protection function, a collector voltage monitoring function, an IGBT on-off voltage regulation function, an IGBT gate drive signal conversion function, an active clamping function and the like by combining an external circuit, and the specific mode of function realization is detailed in the construction and working principle description of each circuit of the invention.

TABLE 1QD2011 Pin definition (note: there are several differences in the QD2011 chip specifications in the notation used in the Pin definition, but there are no differences in the functionality, e.g., 1CCP, 1VD2 in the specification, 3GON in the specification of 3GH, GOFF in the specification of 4GL, and V in the specification of 5REF_REF8F-SET specification Fault) including an active clamp circuit and a short circuit protection circuit.

The active clamp circuit effectively suppresses voltage spikes when the IGBT is turned off by using the transient suppression device with a fast response characteristic, and a typical circuit can realize an active clamp function by connecting a plurality of TVS (a high-performance protection device in the form of a diode) in series, where the active clamp includes at least one bipolar transient suppressor (as shown in D11 in fig. 2). The active clamp circuit comprises resistors R7, R8, R9, a capacitor C2, diodes D12, D13 and TVS tubes D11, wherein the D11 is formed by connecting at least one bipolar TVS tube and a plurality of unipolar TVS tubes in series, the R9 is a pull-down resistor of a chip port ACL, the R8 is a current-limiting resistor of the chip port ACL, the R7 and the C2 jointly act to quickly transfer change of IGBT collector voltage, the D13 is a clamp diode, and the D12 is used for preventing reverse conduction in a loop formed by a collector and a gate. Under the normal on state, namely when the voltage of the collector does not exceed the value set by the active clamp, the active clamp does not act; when the voltage of the collector is too high, the TVS tube D11 is broken down, the voltage at the two ends of the capacitor C2 changes to form an alternating current signal, the alternating current signal is transmitted to the active clamping monitoring port ACL of the chip through the current limiting resistor R8, at the moment, the chip outputs a short pulse IGBT switching-on signal, and the IGBT is switched on to enable the voltage of the collector to fall.

The short-circuit protection circuit comprises resistors R4, R6 and R10, capacitors C3 and C4 and a diode D10; wherein R6 is defined by variable amountsThe high-voltage resistor or the resistor network connected in series is used for reducing the voltage of the IGBT collector input to the chip port, and the power consumption can be dispersed in a single resistor bearable range; r10 is a current-limiting resistor which can limit the current flowing into the chip port; d10 is used for clamping to protect the chip port input voltage from exceeding the supply voltage at most in case of IGBT failure. The short-circuit protection function is realized by monitoring C, E interelectrode voltage when the IGBT is switched on to judge whether the IGBT has short circuit or not, and once the detected V is detected_CEAnd if the voltage is higher than the preset value, the output level of the comparator inside the chip is turned over, so that the driving signal outputs a low level, and the IGBT is turned off. Mainly through ports REF, V in the chip QD2011_CEThe protection is set. The REF port sets the threshold value of short-circuit protection, V, through an external resistor R4_CEThe port is used for monitoring the actual IGBT turn-on voltage, and the port V can be monitored by the collector voltage_CECharging capacitors C3 and C4 are connected between the ground end GND to adjust the short-circuit protection response time, and the longer the charging time of the capacitors is, the corresponding short-circuit response time is also increased.

The IGBT gate circuit 4 is formed by jointly constructing an IGBT gate driving circuit, an IGBT on-off resistance separation circuit and an IGBT gate protection circuit and comprises an MOSFET Q5 and an internal diode D5 thereof, resistors R1, R2, R3 and R5, a capacitor C1, diodes D6, D8 and D9. Wherein,

the IGBT gate driving circuit is used for converting a low-voltage IGBT switch control signal in the chip into a voltage signal capable of driving an IGBT switch in a mode of improving the capacity of driving peak current through an externally-connected MOSFET Q5; the working principle is that when a pin GH of a secondary side signal processing chip 3 outputs an IGBT (insulated gate bipolar transistor) turn-on signal, an MOS turn-on signal output by a DH enables Q5 to be turned on, and the GH output current and the Q5 output current are overlapped to increase the current flowing into a gate resistor R3, so that the capacity of driving peak current is improved, and the current signal is converted into a voltage signal and then is connected to a gate of the IGBT to control the turn-on and turn-off of the IGBT; c1 is a voltage-stabilizing capacitor for turning on the gate drive power supply of the MOSFET; the drain electrode of the MOSFET is clamped at the ground through a diode D8, and the potential at the point is prevented from becoming negative;

the IGBT turn-on and turn-off resistance separation circuit can respectively adjust the turn-on time and the turn-off time of the IGBT through the resistance values of an external turn-on resistance R3 and a turn-off resistance R2, and plays a role in dispersing power consumption in the turn-on and turn-off process; the working principle is that when the IGBT is switched on, a chip pin GH outputs high level, the high level is input into a gate electrode of the IGBT through a resistor R5 and a switching-on resistor R3, so that the IGBT is switched on, when the IGBT is switched off, a chip pin GL outputs low level, and the low level is input into the gate electrode through a gate electrode switching-off resistor R2, so that the IGBT is switched off. The resistor R5 converts the opening voltage signal output by the chip into a current signal and inputs the current signal into the opening resistor R3; resistor R1 is the pull-down resistor of the gate turn-off output port of the chip IGBT and has the function of providing a low-impedance loop between the gate and the emitter of the IGBT even if the driver is powered down.

An IGBT gate protection circuit, wherein the gate is connected with a power supply potential through a diode D9, so that the gate voltage is clamped below the power supply voltage; the gate electrode is connected with the emitter electrode through a bidirectional voltage regulator tube D6, so that the potential of the gate electrode is at a stable value;

the chip peripheral circuit comprises a diode D7 and a resistor R11, and the voltage of a port GL of the chip is clamped below a power supply potential through the diode D7 so as to prevent the port from being overhigh in abnormal state and damaging the chip; the reference current inside the chip can be set by the resistor R11.

The plug and play structure module is a driving installation mode for directly welding a driving plate on an IGBT, and is shown in the following figure 3.

Attached: chip QD2011 specifies:

QD2011 is a dedicated integrated circuit specially developed by shenzhen bronze sword power electronics technology limited for the secondary edge processing in the IGBT driver core for the current IGBT driver market. The method can be used for replacing the CONCEPT IGBT driver based on scale-2 chips. Fig. 4-1 is an application block diagram thereof, and fig. 4-2 is a functional block diagram thereof.

Pin number and definition

Serial number	Definition of	Description of the invention	Serial number	Definition of	Description of the invention
						1	VD2	MOS gate pole opening driving power supply	9	ON_Pulse	Switching on short pulse signals
2	DH	Turn-on MOS gate drive	10	OFF_Pulse	Off short pulse signal
						3	GON	IGBT gate turn-on output	11	DL	Turn-off MOS gate drive
4	GOFF	IGBT gate turn-off output	12	ACL	Active clamp monitoring
						5	V_REF	Short circuit protection threshold setting	13	GND	Ground
6	VCE	IGBTCE voltage monitoring	14	VISO	Input power supply
						7	BIAS	Reference current setting	15	ST1	Signal condition monitoring
8	Fault	Fault status output	16	VE	IGBTE pole potential setting

TABLE 1QD2011 Pin definition

System performance parameters

The following parameters were tested at VISO 25V and ambient temperature T25 ℃ unless otherwise specified.

TABLE 2QD2011 Primary Performance parameters

Detailed description of functional modules

1. Signal transmission

The chip QD2011 mainly functions to convert a terminal pulse signal input by the transformer into a normal signal for turning on and off the IGBT through logic processing. Fig. 4-3 illustrates the relationship between the ON _ pulse, OFF _ pulse, and IGBTVGE voltages at the input pins.

The input pins ON _ pulse and OFF _ pulse of the QD2011 are both short pulse signals, and meanwhile, the chip has a common mode rejection function, that is, if the two pins are simultaneously input high, the IGBTVGE should be at an OFF level, and meanwhile, the voltage amplitude of the pulse signals input by the two pins is only required to be greater than or equal to 10V.

Not only can the gate pole of the IGBT be turned OFF by OFF _ pulse, but also the IGBT can be turned OFF by modules such as undervoltage protection, short-circuit protection and the like in the chip so as to protect the IGBT.

2. Short circuit protection

The chip QD2011 has a short-circuit protection function. The short-circuit protection is realized by detecting the voltages C and E when the IGBT is switched on to judge whether the IGBT is short-circuited.

As shown in fig. 4-4, the shaded portion is a circuit structure diagram of short-circuit protection inside the chip QD2011, mainly through the port V_REF,V_CEThe protection is set.

1.V_REFThe port is internally provided with a 150uA constant current source output which is connected with a resistor R through the outside_REFTo set a threshold for short circuit protection.

V_REF＝150×R_REF(KΩ)×10^‐3

2.V_CEThe port is used for detecting the voltage when the actual IGBT is switched on.

3. When the IGBT is turned off, the internal logic of the chip can pull down the VCE port to a low level, so that the chip can not perform short-circuit protection when the IGBT is turned off.

4.R_CEConnected to the C-pole of the IGBT for monitoring the voltage at the collector of the IGBT, R_CEThe value of (A) is selected according to the following method, according to different bus voltages, so that R flows through_CEThe current of (A) is 0.6 mA-1 mA, e.g., V_DC‐LinkWhen 1200V, R_CE＝1.2MΩ‐1.8MΩ。R_CEThe high voltage resistor can be selected, or a plurality of resistors can be connected in series, and in any case, the creepage distance is a factor which must be considered.

5. When IGBT is turned on, V_CEVoltage greater than V_REFThe QD2011 chip internal comparator level will flip, turning off the IGBT and signaling a fault.

6.C_CEIs used to adjust the response time of the short-circuit protection, and the response time and R_CEAnd R_REFAre all relevant, the detailed parameter list is as follows:

C_CE[pF]	R_REF[kΩ]/V_REF[V]	Response time[μs]
			0	43/6.45	1.2
15	43/6.45	3.2
			22	43/6.45	4.2
33	43/6.45	5.8
			47	68/10.2	7.8
0	68/10.2	1.5
			15	68/10.2	4.9
22	68/10.2	6.5
			33	68/10.2	8.9
47	68/10.2	12.2

TABLE 3 response times (responsetime) and C_CEAnd R_REFIn relation to (2)

IGBT turn-on and turn-off voltage determination

The input power supply of the chip QD2011 is about 25V, and in order to enable the power supply to normally control on and off of the IGBT, the power supply needs to be allocated to the IGBT emitter as a reference potential. If the VISO is 25V relative to the GND input power supply, the QD2011 controls the voltage VE of the emitter to be 10V relative to the GND voltage, so that the voltage VGE is +15V when the IGBT is switched on, and the voltage VGE is-10V when the IGBT is switched off.

Detailed working principle please see the functional block diagrams of fig. 4-5.

As shown in fig. 4-5, the on-off voltage of the IGBT is controlled mainly by the feedback of two operational amplifiers AMP1 and AMP2 inside the chip.

1. In general, the gate voltage VG at the time of turn-on of the IGBT is VISO, and the gate voltage VG at the time of turn-off is 0, that is, GND potential.

2. When the VISO voltage is sufficient (VISO >21V), AMP2 mainly acts, and it can be seen from fig. 4 that VGE ═ 150uA × 100K ═ 15V is the positive electrode voltage of AMP 2.

However, when VISO is less than 21V, the situation that the IGBT is turned off when VGE is 15V when the IGBT is turned on is assumed, and VGE > -6V when the IGBT is turned off, and if the turn-off voltage of the IGBT is too high, the IGBT is turned off continuously. In order to prevent the situation, the voltage of the positive input end of the AMP2 is controlled by AMP1 in the chip to ensure that the VGE voltage is less than-6V when the IGBT is turned off.

4. Undervoltage protection

The QD2011 detects the power supply voltage, and in order to ensure that the on and off voltages of the IGBT are within a range that the IGBT can normally operate, the QD2011 monitors the on voltage VISO-VE and the off voltage VE of the IGBT.

The VISO-VE voltage is the voltage when the IGBT is turned on. When the voltage is lower than 12V, the QD2011 will set the IGBT low and signal a fault in order to ensure that the IGBT will not experience device loss due to excessive back loss when turned on. In this case, the chip can recover from the under-voltage condition only when the voltage is higher than 12.5V.

2. VE is the voltage at which the IGBT turns off. When this VE voltage is less than 5V, QD2011 will lower the IGBT gate and signal a fault. Once the undervoltage state is entered, the chip can automatically recover from undervoltage protection only if the voltage at point VE is higher than 6V.

The under-voltage protection is to ensure that the IGBT can be reliably turned on and off.

5. Fault management

Once the chip QD2011 detects a fault (undervoltage or short), the chip acts as follows:

1. the IGBT is turned off.

2. A short Pulse signal of about 200ns is sent out through an ON _ Pulse pin and is used for transmitting a fault signal to a primary chip through a transformer to receive the fault signal.

3. The Fault port will also output a low level signal; normally the Fault pin should be a high level signal of around 5V with a low pulse spike of around 100ns with the input PWM signal. The pin can be used for transmitting fault signals through optical fibers. As shown in fig. 4-6.

4. The ST1 port may be used to set a fault delay time. Normally, the voltage level is low, and the voltage level is 5V level inside the chip when the fault occurs.

IGBT gate drive

The QD2011 gate drive part converts a low-voltage IGBT switch control signal inside a chip into a gate drive signal capable of controlling the on and off of the IGBT through various functional modules, and a power supply module which needs to supply power to the corresponding functional modules.

1. As shown in fig. 4-7, GONGOFF is the output terminal of the driver, and can connect with a resistor for controlling the on and off time of the IGBT. The on-time is determined by the resistor RGON connected to the GON pin, and the off-time is determined by the resistor RGOFF connected to the GOFF pin. The resistance value and power of the selected resistor are determined according to the specific type of the IGBT.

The QD2011 also makes pins (GH, GL) for a control port of a MOSFET (metal-oxide-semiconductor field effect transistor) for internally driving the gate electrode of the IGBT, so that the external MOSFET can be connected to improve the driving peak current capacity under the condition that the internal driving capacity of the QD2011 is insufficient.

3. Q1, Q2 inside the driver are NMOS with peak current 8A. Q1, Q2 has a drive level of 0-10V, i.e., VGS 10V when on and 0 when off. In order to achieve the level, an independent driving power module is arranged in the chip, and meanwhile, an external capacitor C (1-10 nF can be connected) is used for achieving the effect of stabilizing the power.

4. The level conversion module mainly converts an original logic level signal of 5V in the chip into a level required by a driving part.

6. Active clamp

The QD2011 chip has an active clamping function, and can protect the IGBT when the collector voltage is too high.

As shown in fig. 4-8, the peripheral circuit has a TVS or a high voltage regulator to detect the voltage of the collector of the IGBT, and the regulated voltage of the diode is the critical value of the active clamping function.

The normal work is that collector voltage is lower, and the diode is in the off-state, and ACL pin is in the low level, and the chip is in normal on and off-state. When the collector voltage rises to be higher than the regulated voltage value of the diode (generally, the collector voltage is generated under the condition of short circuit), the diode is conducted in the reverse direction, the ACL port is set to be at a high level, and the Q2 is switched off through a gate circuit; meanwhile, the diode current also flows to the IGBT gate, once Q2 is turned off, the gate current flows through, and the IGBT gate potential is raised; when the gate potential is higher than a certain value, the IGBT is turned on, so that the voltage of a collector on the IGBT is correspondingly reduced. The whole process ensures that the IGBT can not be damaged due to overhigh voltage of the collector.

The value selection of the TVS tube or the voltage regulator tube needs to be combined with the IGBT device and the practical application condition to be comprehensively considered, and in addition, protective measures are made for an ACL and an IGBT gate pole to prevent the chip or the IGBT from being damaged due to overhigh voltage from the diode.

The plug-and-play T-type three-level IGBT driving circuit applied to the photovoltaic grid-connected inverter provided by the embodiment of the invention is designed with the functions of active clamping, short-circuit protection, gate protection and the like, has the advantages of high safety and reliability, high control accuracy, small system loss, convenience in use and the like, and is applied to driving the photovoltaic grid-connected inverter.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications, equivalents, and alternatives made by using the contents of the present invention and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A T-shaped three-level IGBT driving circuit is used for driving a three-level topological module (1) and comprises a gate circuit (4) connected with the three-level topological module (1), wherein the gate circuit (4) comprises an IGBT gate driving circuit and is used for converting a low-voltage IGBT switch control signal into a voltage signal capable of driving an IGBT switch; the method is characterized in that: the circuit also comprises an overvoltage protection circuit (3) and a secondary side signal processing module (2). The overvoltage protection circuit (3) is respectively connected with the three-level topology module (1) and the secondary side signal processing module (2), the overvoltage protection circuit (3) comprises an active clamping circuit, and the active clamping circuit effectively inhibits a voltage peak when the IGBT is turned off through a transient suppression device with a quick response characteristic; the secondary side signal processing module (2) at least has a collector voltage monitoring function.

2. The T-type three-level IGBT driving circuit according to claim 1, wherein the secondary side signal processing module (2) comprises a secondary side signal processing chip and its peripheral circuits, and the secondary side signal processing module further implements at least one of the following functions: the device comprises a signal processing function, a short-circuit protection function, an IGBT (insulated gate bipolar transistor) on-off voltage regulation function, an under-voltage protection function, a fault management function and an IGBT gate drive signal conversion function.

3. A T-type three-level IGBT driving circuit according to claim 2, characterized in that: the gate circuit (4) further comprises an IGBT on-off resistance separation circuit and an IGBT gate protection circuit, wherein the IGBT on-off resistance separation circuit is used for separating the gate resistance into an on-resistance and an off-resistance, the on-time and the off-time of the IGBT can be adjusted through the resistance values of the on-resistance and the off-resistance respectively, and the IGBT gate protection circuit can play a role in dispersing the power consumption of the switch; the IGBT gate pole protection circuit connects the gate pole with the power supply potential through a diode, so that the gate pole voltage is clamped below the power supply voltage; the gate is connected to the emitter through a bi-directional regulator tube so that VGE is at a stable value.

4. A T-type three-level IGBT driving circuit according to claim 2, characterized in that: the overvoltage protection circuit (3) also comprises a short-circuit protection circuit, whether the IGBT has short-circuit fault or not is judged by detecting the voltage of a collector in real time, and once the short-circuit condition occurs, the short-circuit protection circuit is matched with the chip to output a fault signal and turn off the IGBT; the overvoltage protection circuit (3) further comprises a voltage monitoring circuit, wherein the voltage monitoring circuit comprises a VCE monitoring circuit and an active clamping monitoring circuit in the short-circuit protection function, and the VCE monitoring circuit and the active clamping monitoring circuit respectively play a role in information feedback in the short-circuit protection function and the active clamping function.

5. A T-type three-level IGBT driving circuit according to claim 1, characterized in that: the T-type three-level IGBT driving circuit further comprises a plug-and-play function module which is used for forming a driving board for the T-type three-level IGBT driving circuit and directly connecting the driving board to the IGBT.

6. A T-type three-level IGBT driver circuit according to claim 2, characterized in that: the active clamping circuit realizes an active clamping function by connecting a plurality of TVS tubes in series, and the active clamping at least comprises a bipolar transient suppressor.

7. A T-type three-level IGBT drive circuit as claimed in claim 6, characterized by: the active clamp circuit comprises first to third resistors (R7, R8, R9), a capacitor (C2), first and second diodes (D12, D13) and a TVS tube (D11), wherein the TVS tube (D11) is formed by connecting at least one bipolar TVS tube and a plurality of unipolar TVS tubes in series, the third resistor (R9) is a pull-down resistor of an active clamp monitoring port (ACL) of a secondary side signal processing chip, the second resistor (R8) is a current-limiting resistor of the active clamp monitoring port (ACL) of the secondary side signal processing chip, the first resistor (R7) and the capacitor (C2) act together and are used for rapidly transmitting changes of IGBT collector voltage, the second diode (D13) is a clamp diode, and the first diode (D12) is used for preventing reverse conduction in a loop formed by a collector and a gate.

8. A T-type three-level IGBT drive circuit as claimed in claim 4, characterized by: the short-circuit protection circuit comprises fourth to sixth resistors (R4, R6 and R10) and a third diode (D10); the fifth resistor (R6) is composed of a variable number of high-voltage resistors or a resistor network connected in series, so that the IGBT collector voltage input to the chip port is reduced, and the power consumption can be dispersed in a single resistor bearable range; the sixth resistor (R10) is a current-limiting resistor which can limit the current flowing into the chip port; the third diode (D10) is used for clamping to protect the chip port input voltage from exceeding the supply voltage at most in case of IGBT failure.

9. A T-type three-level IGBT driver circuit according to claim 3, characterized in that: the IGBT turn-on and turn-off resistance separation circuit can respectively adjust the turn-on time and the turn-off time of the IGBT through the resistance values of an external turn-on resistance (R3) and a turn-off resistance (R2).

10. A T-type three-level IGBT driver circuit according to claim 3, characterized in that: the gate protection circuit connects the gate to the supply potential through a diode (D9) so that the gate voltage is clamped below the supply voltage; the gate is connected to the emitter through a bi-directional regulator (D6) so that the gate potential is at a steady value.