CN111276941B

CN111276941B - IGBT drive overcurrent protection and short-circuit protection system circuit

Info

Publication number: CN111276941B
Application number: CN202010109871.2A
Authority: CN
Inventors: 霍煜
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-02-23
Filing date: 2020-02-23
Publication date: 2022-05-03
Anticipated expiration: 2040-02-23
Also published as: CN111276941A

Abstract

The invention discloses an IGBT driving overcurrent protection and short-circuit protection system circuit which comprises a driving optocoupler, an overcurrent protection circuit, a short-circuit protection circuit and an active clamping circuit, wherein the overcurrent protection circuit, the short-circuit protection circuit and the active clamping circuit can be independently applied, and a better IGBT protection effect is achieved when the overcurrent protection circuit, the short-circuit protection circuit and the active clamping circuit are combined. This circuit system can carry out effectively, reliable overcurrent and short-circuit protection to adopt the RC mode to carry out the blind area regularly, adopt pi type to connect to carry out anti-interference processing when necessary, when the voltage that the comparator detected on the RC reaches the settlement voltage, comparator output overturns, sends out unusual signal, detects by the control opto-coupler and seals the purpose that ripples shutoff IGBT reached the protection.

Description

IGBT drive overcurrent protection and short-circuit protection system circuit

Technical Field

The invention relates to the technical field of electronic device protection, in particular to an IGBT driving overcurrent protection and short-circuit protection system circuit.

Background

The IGBT has good characteristics of easy driving, high voltage resistance, large current, high speed, low saturation voltage drop and the like, so the IGBT is widely applied to devices such as frequency converters, SVG, high-power supplies, motor adjustment, soft start, inverter welding machines and the like.

The IGBT is similar to other electronic devices, and besides the device performance that the IGBT can provide, the practicality also depends on the circuit conditions and the switching environment, so how to drive and protect the IGBT to ensure safe and reliable operation of the IGBT is a difficult point and a key of the design of the IGBT driving circuit.

In practical application, because the performance of the over-current and the direct short circuit of the whole machine on the IGBT is obviously different, the current rising speed of the IGBT is relatively slow when the current is over-current, the VCE voltage of the IGBT rises slowly and relatively low, and the lower judgment voltage and the longer blind zone can be adopted for judgment. When short circuit occurs, the rising speed of the IGBT current is relatively fast, the VCE voltage of the IGBT rises relatively high, and high judgment voltage and short judgment time can be adopted for judgment.

The short circuit is a straight-through behavior generated by the power voltage in the IGBT, generally, the straight-through behavior is generated by the simultaneous conduction of the upper IGBT and the lower IGBT in a half-bridge system or the output in a full-bridge or a three-phase bridge, and the working characteristics of the IGBT at the moment are that the current is rapidly increased when the IGBT is conducted, the voltage VCE is rapidly increased, the protection judgment voltage is higher at the moment, and the dead zone time is shorter. The over-current behavior refers to the output with a certain reactance during short circuit, or longer cable, or maladjustment of system control, and the IGBT has the working characteristics that the rising slope of the output current is slower, the VCE voltage rises lower, the judgment voltage during protection is lower, and the dead zone duration is longer;

therefore, an IGBT driving overcurrent protection and short-circuit protection system circuit is provided.

Disclosure of Invention

The invention aims to provide an IGBT driving overcurrent protection and short-circuit protection system circuit, which can effectively and reliably protect an IGBT from overcurrent and short-circuit, adopts an RC mode to carry out dead zone timing, adopts pi-type connection to carry out anti-interference processing if necessary, and when a comparator detects that the voltage on the RC reaches a set voltage, the output of the comparator is turned over, an abnormal signal is sent out, and a control optocoupler is used for detecting and sealing waves to turn off the IGBT to achieve the purpose of protection, so that the problems in the background art are solved.

In order to achieve the purpose, the invention provides the following technical scheme: IGBT drive overcurrent protection and short-circuit protection system circuit, including drive opto-coupler, overcurrent protection circuit, short-circuit protection circuit and active clamp circuit all can be used alone, reach better IGBT guard action during the combination, drive opto-coupler, overcurrent protection circuit, short-circuit protection circuit and active clamp circuit four with the IGBT drive is connected.

The overcurrent protection circuit can independently send an overcurrent protection signal, the short-circuit protection circuit can independently send a short-circuit protection signal, and in the short-circuit protection circuit and the overcurrent protection circuit, the signals of the short-circuit protection circuit and the overcurrent protection circuit are sent to a system in an AND relationship, and the signals are uniformly identified as IGBT fault states by the system.

The over-current protection circuit and the short-circuit protection circuit take out pulse signals from the IGBT driving side to set dead zone time, and the over-current protection circuit controls the dead zone time of the IGBT when the IGBT is conducted by utilizing the pulse signals driven by the IGBT to form a pi-shaped charging mode through an RC charging mode or an RCRC charging mode.

The short-circuit protection circuit also utilizes the RC to control the duration of a dead zone when the IGBT is conducted, and the difference is that a driving pulse signal in the protection circuit mainly plays a discharging role and clamps the voltage on the voltage division side to inhibit the voltage on the voltage division side of the IGBT.

By adopting the technical scheme, the circuit system can effectively and reliably protect the IGBT from overcurrent and short circuit, dead zone timing is carried out by adopting an RC mode, anti-interference processing is carried out by adopting pi-shaped connection when necessary, when the comparator detects that the voltage on the RC reaches the set voltage, the output of the comparator is overturned, an abnormal signal is sent out, and the purpose of protecting the IGBT by controlling the optocoupler to detect wave-sealing turn-off is achieved.

Preferably, the overcurrent protection circuit and the short-circuit protection circuit both adopt comparators for voltage comparison, and adopt drive signals of the IGBTs for controlling the dead zone duration, and the dead zone duration is set by adjusting the RC value.

Preferably, the active clamp circuit adopts the transient conduction of the MOS transistor to generate a voltage drop on the driving resistor so as to transiently conduct the IGBT driving, thereby effectively suppressing a spike voltage on the VCE on the IGBT driving.

Preferably, the used circuits can be independently applied to any driving circuit or can be separately combined together, and the short-circuit protection circuit judgment signal and the overcurrent protection circuit judgment signal can be sent out independently or can be sent out to a detection point of the driving optocoupler and a detection point of a system by performing an and or logic operation.

Preferably, as the RC in the used circuit adopts a pi-type resistance-capacitance connection mode, the filtering processing can be carried out on the interference from the IGBT side while the duration of the dead zone is controlled.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides an IGBT driving protection circuit and application of active clamping, which can effectively and reliably protect an IGBT from overcurrent and short circuit.

The overcurrent protection circuit mainly comprises voltage acquisition, utilizes a driving signal to carry out synchronization, adopts an RC mode to carry out blind area timing, and adopts pi-shaped connection to carry out anti-interference processing when necessary. When the comparator detects that the voltage on the RC reaches the set voltage, the output of the comparator is inverted, and an abnormal signal is sent out. The IGBT is cut off by detecting the sealing wave through the control optocoupler to achieve the purpose of protection.

The short-circuit protection circuit mainly controls voltage acquisition, utilizes a driving signal to carry out synchronization, adopts an RC charging mode to carry out blind area setting, and utilizes a resistance voltage division mode to set the detection of VCE of the IGBT. When the comparator detects that the voltage on the RC reaches the set voltage, the output of the comparator is inverted, and an abnormal signal is sent out. The optical coupler detects the sealed wave and turns off the IGBT to achieve the purpose of protection.

The active clamping circuit mainly adopts a TVS group for voltage detection, when the TVS group is transiently broken down by peak voltage, the MOS transient state is conducted, the power voltage in the system is added to the driving resistor side to improve the IGBT transient state conducting voltage, the IGBT transient state is conducted, the VCE peak voltage on the IGBT is restrained, after the peak voltage disappears, the TVS recovers a turn-off state, the MOS is cut off, and the IGBT returns to the turn-off state again.

The invention adopts an optical coupler A332J for driving, and because the A332J has only one detection point, a fault signal is processed by two diodes and sent to the detection point, and wave-sealing protection is carried out by the A332J.

The invention can adopt a relatively universal optical coupler for driving, can send out overcurrent and short-circuit signals through other optical couplers respectively, and can carry out wave sealing treatment by an external system. Whether the short-circuit behavior or the overcurrent behavior is classified can be refined.

Drawings

FIG. 1 is a schematic structural diagram of an IGBT overcurrent protection circuit of the invention;

FIG. 2 is a schematic structural diagram of an IGBT short-circuit protection circuit of the present invention;

FIG. 3 is a schematic structural diagram of an IGBT active clamp circuit of the present invention;

FIG. 4 is a schematic structural diagram of the IGBT active clamp circuit transient state reflection of the present invention;

fig. 5 is a schematic structural diagram of the high-power IGBT current-spreading circuit of the present invention.

Detailed Description

In the following, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 5, the present invention provides a technical solution:

IGBT drive overcurrent protection and short-circuit protection system circuit, including drive opto-coupler, overcurrent protection circuit, short-circuit protection circuit and active clamp circuit all can be used alone, reach better IGBT guard action during the combination, drive opto-coupler, overcurrent protection circuit, short-circuit protection circuit and active clamp circuit four with the IGBT drive is connected.

The overcurrent protection circuit can independently send overcurrent protection signals, the short-circuit protection circuit can independently send short-circuit protection signals, and in the short-circuit protection circuit and the overcurrent protection circuit, signals of the short-circuit protection circuit and the overcurrent protection circuit are sent to a system in an AND relationship, and the system is uniformly identified as an IGBT fault state.

The working principle is as follows:

as shown in fig. 2, the overcurrent protection circuit is shown in fig. 3, the short-circuit protection circuit is shown in fig. 3, and since the driving optocoupler a332J is used, the optocoupler has only one fault detection point, short-circuit and overcurrent signals are and-logic-operated by a diode and sent to the fault detection end of the driving optocoupler.

As shown in fig. 2 and 3, a voltage regulator D2 is used as the reference voltage of the comparator, V + is limited by R1, D2 is turned on, D2 is a voltage regulator, and the voltage is limited to the rated voltage of D2.

As shown in fig. 2, D1 is a VCE collection diode of an IGBT in the circuit, when the drive optocoupler emits a high level, the potential at RG point is V + ═ 15V at this time, the IGBT is turned on, the VCE voltage of the IGBT is low, D1 is turned on, the positive voltage of the comparator is the VCE voltage of the IGBT plus the turn-on voltage of D1 at this time, which is less than the reference voltage, the output of the comparator is low, and at this time, the comparator is in a normal operating state. When the drive optocoupler sends out a low level RG of-10V, the IGBT is cut off, the VCE voltage is bus voltage, the D1 is cut off, the positive pole potential of the comparator is pulled to V-by the RG through R2, the positive pole voltage of the comparator is smaller than the negative pole voltage, the output of the comparator is low, and the comparator is in a normal working state. When the driving optocoupler emits a high level, the IGBT is in an overcurrent state at the moment, the VCE of the IGBT is increased, the D1 is changed from a conducting state to a cut-off state, the positive voltage of the comparator is conducted to the C1 through the R2 at the RG point and is in a rising state, the rising rate depends on the RC charging constant, when the positive voltage of the comparator is higher than the negative reference voltage, the output of the comparator is high, and the fault detection point of the driving optocoupler is sent into the D3. The drive optocoupler pulls down the drive voltage and simultaneously reports a fault.

As shown in fig. 3, in the circuit as a short-circuit protection circuit, firstly, the reference point voltage of the comparator is set to be the same as the above, when the IGBT fails, VCE rises rapidly, and when the voltage of the point C where Rn is connected with the IGBT rises to a certain value, the positive input pole voltage of the comparator U2 divides the voltage with R9 through Rn-R6, and the voltage rises rapidly to the reference voltage through the charging of C2, the output of U2 is positive, and the signal is sent to the driving optocoupler through D5, so that the optocoupler performs a protection action. Since the voltage at the junction of R6 and D4 can only rise to RG potential (clamped by D4) at the most, the lowest operating voltage of VCE can be calculated by the resistance voltage-dividing formula, and VF is [15/(R6+ R9) ] × (R9+ R6+ Rn) -V- ] when the lowest operating voltage of VCE is VF.

As shown in fig. 3, when the IGBT in fig. 3 normally operates, when the optocoupler is driven to be high, RG is at a high level, the IGBT is turned on, VCE is low and is less than VF, and at this time, the voltage of the positive electrode of the comparator is less than the reference voltage, and the output of the comparator is low. When the output of the optocoupler is low, the IGBT is in a turn-off state, at the moment, the voltage of the comparator is pulled to a low level through R6 because the RG is a low level, the positive input voltage of the comparator is smaller than the reference voltage, and the output of the comparator is low. This is the normal operating state.

As shown in fig. 4, the circuit is an active clamp circuit, when the IGBT is turned off at a high current, due to the existence of stray inductance, high peak voltage is generated on both sides of the VCE, and when the voltage exceeds the rated voltage of the IGBT, the IGBT is very easily broken down to cause overvoltage breakdown of the IGBT, and the IGBT is instantaneously turned on to suppress the peak voltage when the IGBT generates the peak voltage. The active clamp circuit is different from other active clamps in that an MOS (metal oxide semiconductor) tube is added, so that the transient response of the IGBT is faster and more timely and effective.

As shown in FIG. 4, the circuit is an active clamp circuit, when the IGBT generates a turn-off voltage spike, Dn, namely TVS tubes, are connected in series and are instantaneously broken down, the voltage is rapidly applied to a gate electrode of U1, U1 is turned on to apply V + voltage to R4, R4 generates a voltage difference to drive the IGBT to be turned on, and when the spike voltage is within a breakdown range of Dn, Dn is turned off, MOS tubes are turned off, and the IGBT is in a cut-off state again.

As shown in fig. 5, when the system is applied to a high-power IGBT, an output plus push-pull circuit may be used to expand the current, without affecting the above protection functions.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

IGBT drive overcurrent protection and short-circuit protection system circuit, including drive opto-coupler, overcurrent protection circuit, short-circuit protection circuit and active clamp circuit, its characterized in that: the overcurrent protection circuit, the short-circuit protection circuit and the active clamping circuit can be independently applied to achieve a better IGBT protection effect when combined, and the driving optocoupler, the overcurrent protection circuit, the short-circuit protection circuit and the active clamping circuit are in driving connection with the IGBT;

the overcurrent protection circuit can independently send overcurrent protection signals, the short-circuit protection circuit can independently send short-circuit protection signals, and in the short-circuit protection circuit and the overcurrent protection circuit, signals of the short-circuit protection circuit and the overcurrent protection circuit are sent to a system in an OR relationship and are uniformly identified as an IGBT fault state by the system;

the over-current protection circuit and the short-circuit protection circuit take out pulse signals from the IGBT driving side to set dead zone time, and the over-current protection circuit controls the dead zone time of the IGBT when the IGBT is conducted by utilizing the pulse signals driven by the IGBT through an RC charging mode or an RCRC forming pi-shaped charging mode;

the short-circuit protection circuit also utilizes the RC to control the duration of a dead zone when the IGBT is conducted, and the difference is that a driving pulse signal in the protection circuit mainly plays a discharging role and clamps the voltage on the voltage division side to inhibit the voltage on the voltage division side of the IGBT.
2. The IGBT-driven overcurrent protection and short-circuit protection system circuit of claim 1, wherein: the overcurrent protection circuit and the short-circuit protection circuit are both voltage-compared by adopting comparators, the dead zone time length is controlled by adopting the driving signal of the IGBT, and the dead zone time length is set by adjusting the RC value.
3. The IGBT-driven overcurrent protection and short-circuit protection system circuit of claim 1, wherein: the active clamping circuit adopts the transient conduction of the MOS tube to generate voltage drop on the driving resistor so as to transiently conduct the IGBT drive, thereby effectively inhibiting the peak voltage on VCE on the IGBT drive.
4. The IGBT driving overcurrent protection and short-circuit protection system circuit according to any one of claims 1 to 3, characterized in that: the circuit is independently applied to any drive circuit or separately combined together, and the short-circuit protection circuit judgment signal and the overcurrent protection circuit judgment signal are sent out independently or are subjected to logical operation or are sent out to a detection point of the drive optocoupler and a detection point of a system.
5. The IGBT-driven overcurrent protection and short-circuit protection system circuit of claim 1, wherein: because the RC in the used circuit adopts a pi-type resistance-capacitance connection mode, the filtering processing can be carried out on the interference from the IGBT side while the time length of the dead zone is controlled.