CN201345539Y

CN201345539Y - Serial connection IGBT pressure-equalizing protection and control circuit

Info

Publication number: CN201345539Y
Application number: CNU200920142787XU
Authority: CN
Inventors: 张兴; 蒲道杰; 孙荣丙; 刘淳
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2009-01-22
Filing date: 2009-01-22
Publication date: 2009-11-11
Anticipated expiration: 2019-01-22

Abstract

A serial connection IGBT voltage-equalizing protection and control circuit is structurally characterized in that a voltage change ratio control circuit and a terminal voltage clamping control circuit are arranged; the voltage change ratio control circuit consists of a one-way conducting diode D2, a charging/discharging capacitor C1 and a resistor R2; when an IGBT is turned off, the conducting diode D2 and the charging capacitor C1 form parallel connection with the IGBT exterior capacitor at the CG terminal of the IGBT; when the IGBT is turned on, the capacitor C1 takes the resistor R2 as a discharging channel; and the terminal voltage clamping control circuit consisting of triodes T1 and T2 charges the grid capacitor of the IGBT through the triodes T1 and T2 with direct current when in the clamping state. The utility model uses simple analog elements to form the control circuit, realizes similar specification curve IGBT switching voltage waveform, and realizes different voltage change ratios at different stages during the switching process.

Description

Voltage equalizing protection control circuit for series IGBT

Technical field

The utility model relates to the IGBT control circuit, more specifically say so a kind of be applicable to the high-vol in the HVDC (High Voltage Direct Current) transmission system and close based on the high-voltage fields such as high voltage converter of IGBT series connection in the IGBT control circuit.

Background technology

Insulated gate bipolar transistor (Insolated Gate Bipolar Transistor---IGBT) is the beginning of the eighties in last century for the high break-over voltage that solves MOSFET, be difficult to make the not enough two-shippers that occur such as the operating frequency that has high voltage and large current characteristic and GTR concurrently is low, drive circuit power is big manages multiple device (Double Mechanism Device).Because it rolls into one the advantage of MOSFET and GTR, both had input impedance height, fast, the Heat stability is good of speed, and advantages such as drive circuit is simple, drive current is little have little, the withstand voltage height of on-state voltage drop again and bear advantages such as electric current is big, and therefore development is very fast.The capacity of IGBT has surpassed GTR at present.In Electric Machine Control, intermediate frequency and Switching Power Supply, and require in quick and low-loss field, IGBT has the trend that replaces MOSFET and GTR.

The flexible DC power transmission current transformer requires the device for power switching in the brachium pontis to have higher withstand voltage (10KV-150KV), and the gate-controlled switch device withstand voltage value of commercially producing at present has only 6000V, therefore must adopt the method at same brachium pontis tandem tap device to realize high withstand voltage.IGBT not only has voltage control input characteristics, low-resistance on-state output characteristic, also have advantages such as high input impedance, driven, no second breakdown and safety operation area be wide, can substitute devices such as GTR and power MOSFET in various fields, simultaneously, because its architectural characteristic, determine it to have the ability of speed-sensitive switch, can satisfy the requirement of PWM technology.

The flexible DC power transmission current conversion station is the voltage source structure, adopt PWM technology control device switch, and the characteristics that the voltage current transformer of using IGBT mainly has comprise: higher system operating frequency, circuit structure power loss compacter, buffer circuit reduce, and drive circuit is simple.

But because the difference of IGBT switching device individuality, the series connection of IGBT has a lot of problems to solve in using:

1, the difference of device parameters

The characteristic of the absorption circuit of device wire distributed inductance and cascade device is inconsistent, thereby can cause different switching characteristics and due to voltage spikes, series IGBT is in turn off process, the device that turn-offs will bear very high overvoltage earlier, and can cause the quiescent voltage imbalance, the device of back conducting will bear the overvoltage that may be higher than the normal voltage several times in opening process.And in the moment of switching device conversion, also can show different switching characteristics, thereby the dynamic electric voltage of the device that can cause connecting is unbalance.

2, the delay of the signal of series IGBT

The delay of signal has greatly influenced the imbalance of voltage, and signal postpones different can causing in the opening process and produce due to voltage spikes on the device of holding slowly, and the device that turn-offs earlier in the turn off process produces overvoltage and causes quiescent voltage unbalance.The delay of the signal of series IGBT also can cause the imbalance of dynamic electric voltage, signal postpones difference and can cause the switch motion of device inconsistent, in the opening process after produce due to voltage spikes on the device opened, the device that turn-offs earlier in the turn off process produces overvoltage and also causes quiescent voltage unbalance.

In the past few years, high-power IGBT and IGCT begin to use. but its application still has been subjected to bigger restriction, particularly in very high-tension equipment, series connection is used and is seemed necessary. yet original power device series connection technology can not be directly used in the series connection of IGBT and use, because the common turn-off time of IGBT, therefore traditional all pressures measure was impracticable at 0.3～0.5us.It is the overvoltage of each IGBT to be kept in balance at shutdown moment in order to guarantee that coupled in series IGBT carries out the purpose of all pressing, thereby to require the response of control circuit be fast; The switching frequency that does not allow to produce more loss and reduce system; Be cost-effective on engineering simultaneously.Therefore it is very necessary to design effective voltage-equalizing control circuit.

The control method of series IGBT can be divided into passive absorption process, drive signal and regulate method, the grid ACTIVE CONTROL method of calibration curve is arranged and do not have the grid ACTIVE CONTROL method of calibration curve.

Passive absorption process is passed through RC in parallel or RCD absorption circuit at the IGBT two ends, the rate of change of terminal voltage in the limit switch process, thus the switch motion difference of series connection device is diminished, reduce the unbalance factor of the device terminal voltage of connecting.But this method can influence the switching speed of series circuit, and produces bigger switching loss, therefore is of limited application.

The drive signal control method comprises synchrotrans method and turn-off time adjusting method.The synchrotrans method is coupled the grid of series IGBT in twos by transformer, reduces the delay of drive signal, the switch motion of series connection device is tending towards synchronously, thereby reduces the inconsistent influence to the balance of voltage of drive signal.Though the method can have good inhibitory effect to the unbalanced-voltage-division that drive signal postpones to cause, the terminal voltage imbalance that the dispersiveness because of device parameters is caused is without any the control effect; Turn-off time is regulated method and the trailing edge of drive signal is adjusted accordingly in next switch periods according to the unbalance factor of series connection device terminal voltage, the method just can work in the next switch periods that exveral phenomena about voltage imbalance occurs, and the control effect has bigger delay.

Passive absorption process, drive signal are regulated method and all can not effectively be controlled the reverse recovery voltage of fly-wheel diode.

It is by feedback loop the IGBT terminal voltage to be fed back to control circuit that the grid ACTIVE CONTROL method of calibration curve is arranged, with given standard switch curve ratio, according to comparative result the IGBT grid voltage is adjusted accordingly.Make the IGBT terminal voltage follow the tracks of calibration curve.The method control circuit partly is made up of feedback loop, reference voltage generating circuit etc., the control circuit complexity, and reliability is relatively poor and be difficult to realize.

The grid ACTIVE CONTROL method of no calibration curve comprises the dynamic clamp circuit based on voltage stabilizing didoe and miller electric capacity, based on dynamic driver circuit of resistance, electric capacity and diode etc.This class control circuit all is made up of simple analog element, by injecting the Control current relevant with the Voltage unbalance rate to the IGBT grid, makes the terminal voltage of series IGBT keep balance.This type of control method control circuit is simple, is easy to realize.But the control loss of the switching loss of series IGBT and control circuit is all bigger.

The utility model content

The utility model is the weak point for avoiding above-mentioned prior art to exist; a kind of voltage equalizing protection control circuit for series IGBT is provided; advantage by comprehensive outside Miller (miller) electric capacity and voltage-stabiliser tube clamp control method; form control circuit with simple analog element; to realize being similar to standard curve I GBT switching voltage waveform, at the different voltage change ratio of different phase realization of switching process.

The utility model technical solution problem adopts following technical scheme:

The design feature of the utility model voltage equalizing protection control circuit for series IGBT is that change in voltage rate control circuit and terminal voltage clamp control circuit are set;

Described change in voltage rate control circuit is to be made of unidirectional conducting diode D2, charge and discharge capacitance C1 and resistance R 2, in the turn off process of described IGBT, constitute the IGBT external capacitive of the CG end that is connected in parallel on IGBT by the diode D2 of conducting and the capacitor C 1 under the charged state; In the turn on process of described IGBT, capacitor C 1 is a discharge channel with resistance R 2;

Described terminal voltage clamp circuit is made of triode T1, T2, and clamp state is by triode T2, the diode D3 gate capacitance charges to IGBT with DC source.

The CE termination that design feature of the present utility model also is at described IGBT is gone into static voltage sharing R3, the R4 that series connection is provided with, and feeds back IGBT terminal voltage by voltage-stabiliser tube DZ to clamp circuit with the dividing potential drop of resistance R 3, R4.

Compared with the prior art, the utility model beneficial effect is embodied in:

1, the utility model control circuit is made of analog element, and circuit structure is simple, be easy to realize, is all increasing than prior art aspect efficient and the reliability.

2, the utility model control circuit is in conjunction with outside miller capacitance and voltage-stabiliser tube clamp, IGBT has two stage voltage rates of change when turn-offing, can find balance point all pressing between effect and the switching loss, the switching loss of IGBT is little a lot of because of the control mode of outside miller capacitance.Simultaneously,, make clamp circuit to work more reliably for the control of clamp circuit gains time because the shutoff later stage voltage change ratio of IGBT reduces.

3, in the utility model control circuit, the input voltage of clamp circuit is to be provided by a minute piezoelectricity group, by regulating the ratio of divider resistance, clamp circuit can be realized by single voltage-stabiliser tube, has therefore avoided a plurality of voltage-stabiliser tube series connection to use the circuit reliability problem that may bring.

Description of drawings

Fig. 1 is the utility model circuit theory diagrams;

Fig. 2 is the analogous diagram of the utility model control circuit in the saber simulation software, and simulated conditions is dc voltage 2500V, electric current 125A, resistance sense load;

Fig. 3 is the emulation voltage waveform of two IGBT series circuit switches processes of same model.The drive signal of two IGBT postpones 200ns.

Fig. 4 is two IGBT series circuit IGBT turn off process emulation voltage waveform enlarged drawings of same model.The drive signal of two IGBT postpones 200ns.

Fig. 5 is two IGBT series circuit IGBT opening process emulation voltage waveform enlarged drawings of same model.The drive signal of two IGBT postpones 200ns.

Fig. 6 is the emulation voltage waveform of two IGBT series circuit switches processes of different model.

Fig. 7 is two IGBT series circuit IGBT turn off process emulation voltage waveform enlarged drawings of different model.

Fig. 8 is two IGBT series circuit IGBT opening process emulation voltage waveform enlarged drawings of different model.

Below pass through embodiment, and the utility model is described in further detail in conjunction with the accompanying drawings.

Embodiment

Referring to Fig. 1,, change in voltage rate control circuit and terminal voltage clamp control circuit are set at the IGBT device;

Shown in Figure 1, the change in voltage rate control circuit is to be made of unidirectional conducting diode D2, charge and discharge capacitance C1 and resistance R 2.In the turn off process of IGBT, when the IGBT terminal voltage is higher than voltage on the capacitor C 1, diode D2 conducting, the capacitor C 1 GC two ends of inserting IGBT in parallel, serve as the outside miller electric capacity of IGBT, thereby IGBT terminal voltage climbing reduced, simultaneously since capacitor C 1 much larger than the parasitic miller electric capacity of IGBT, therefore can ignore the inconsistency of IGBT self parameter, reach the effect of electric voltage equalization.Capacitor C 1 discharges into the voltage change ratio breakover point magnitude of voltage of setting in the opening process by resistance R 2.Two stage voltage rates of change have promptly guaranteed shutoff efficient, and the dynamic overvoltage to the IGBT turn off process also has excellent control effect again.

Fig. 1 illustrates, and IGBT terminal voltage clamp circuit is made of triode T1, T2, goes into static voltage sharing R3, the R4 that series connection is provided with in the CE of IGBT termination, and feeds back IGBT terminal voltage by voltage-stabiliser tube DZ to clamp circuit with resistance R 3, R4 dividing potential drop.When the IGBT terminal voltage was higher than the mean value certain amplitude, voltage-stabiliser tube DZ was breakdown, triode T1, T2 conducting, and 15 volts of DC source are passed through triode T2, diode D3 to the IGBT gate capacitance charges, and the IGBT terminal voltage is dropped to below the clamping voltage.Because the input voltage of clamp circuit is to be provided by bleeder circuit, by regulating the ratio of divider resistance, clamp circuit can be realized by single voltage-stabiliser tube, avoids a plurality of voltage-stabiliser tube series connection to use the functional reliability problem of the control circuit that may bring with this.

Fig. 2 is a saber emulation schematic diagram, and simulated conditions is dc voltage 2500V, electric current 125A, resistance sense load.

Fig. 3 is the switching process emulation voltage waveform of two IGBT series circuits under drive signal delay 200ns condition of same model.The moving static state voltage equipoise of IGBT is respond well as seen from the figure.Prove that this circuit has excellent control effect to the series IGBT electricity unbalanced-voltage-division that postpones because of drive signal to cause.

Fig. 4 is the turn off process emulation voltage waveform enlarged drawing of two IGBT series circuits under drive signal delay 200ns condition of same model, as seen when IGBT turn-offs, have tangible two stage voltage rates of change, can be clamped at set point (emulation is set to 1.3KV) reliably at IGBT shutoff voltage in latter stage, and voltage waveform dead-beat phenomenon.

Fig. 5 is the opening process emulation voltage waveform enlarged drawing of two IGBT series circuits under drive signal delay 200ns condition of same model, as seen from the figure, the IGBT voltage that lags behind can be clamped at the 1.3KV of setting, dead-beat phenomenon simultaneously, and do not influence the speed of opening of IGBT.

Be illustrated in figure 6 as the switching process emulation voltage waveform of IGBT series circuit under drive signal delay 200ns condition of two different models, the moving static state voltage equipoise of IGBT is respond well as seen from the figure.Prove that this control circuit has excellent control effect equally to the unbalanced-voltage-division that causes because of series IGBT parasitic parameter dispersiveness.

Figure 7 shows that the turn off process emulation voltage waveform enlarged drawing of IGBT series circuit under drive signal delay 200ns condition of two different models, as seen when IGBT turn-offs, have tangible two stage voltage rates of change, before the voltage change ratio breakover point, the voltage change ratio of two IGBT shutoffs is obviously different, but when externally miller electric capacity is connected in parallel on the gc end of IGBT, obviously reach unanimity in the change in voltage that two IGBT turn-off; Can be clamped at set point (emulation is set to 1.3KV) reliably at IGBT shutoff voltage in latter stage, and voltage waveform dead-beat phenomenon (engineering proposal 1 all pressing later stage voltage to have oscillatory occurences, has influenced the Electro Magnetic Compatibility of system).

Figure 8 shows that the opening process emulation voltage waveform enlarged drawing of IGBT series circuit under drive signal delay 200ns condition of two different models, as seen from the figure, the IGBT voltage that lags behind can be clamped at the 1.3KV of setting, dead-beat phenomenon simultaneously, and do not influence the speed of opening of IGBT.

Simulation analysis is the result show, this circuit can satisfy the requirement of the moving static state voltage equipoise of IGBT under various different conditions, turn-offing later stage voltage change ratio decline simultaneously, especially at high-power IGBT, can reduce the possibility that it holds up the post effect greatly, improve and turn-off efficient, and the voltage waveform dead-beat, the reliability of series connection improved.

Claims

1, voltage equalizing protection control circuit for series IGBT is characterized in that being provided with change in voltage rate control circuit and terminal voltage clamp control circuit;

2, voltage equalizing protection control circuit for series IGBT according to claim 1; it is characterized in that going into static voltage sharing R3, the R4 that series connection is provided with, and feed back the IGBT terminal voltage by voltage-stabiliser tube DZ to clamp circuit with the dividing potential drop of resistance R 3, R4 in the CE of described IGBT termination.