Desaturation protection circuit

Abstract

The invention relates to the technical field of integrated circuits, in particular to a desaturation protection circuit, which comprises a high-integration module, a detection unit and a resistor R, the driving end of the high-integration-level module is electrically connected with the grid electrode of the IGBT, the collector electrode of the IGBT is electrically connected with the input end of the detection unit, the emitting electrode of the IGBT is electrically connected with the ground end of the detection unit, and the output end of the detection unit is electrically connected with the desaturation detection end of the high-integration-level module; the detection unit is used for receiving CE voltage between a collector electrode and an emitter electrode of the IGBT and generating trigger voltage in a delayed manner; the high-integration-level module is used for receiving the trigger voltage; when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference turn-off signal is generated for turning off the IGBT; therefore, false triggering is effectively avoided, and the IGBT protection circuit is more suitable for IGBT protection driven by a high-integration-level module.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a desaturation protection circuit. Background Art

[0002] Highly integrated modules, such as intelligent power modules that integrate rectification circuits, PFC and inverter circuits, may easily cause damage to the driven ICBG when driving IGBTs due to their complex internal integration environment.

[0003] Specifically, the working state of IGBT is divided into three parts: cut-off region, saturation region and linear region. The formation of these three working regions is mainly because IGBT and MOSFET have similar device structures. The drain D in MOSFET is equivalent to the collector C of IGBT, and the source S of MOS is equivalent to the emitter E of IGBT. Therefore, desaturation phenomenon will occur in both IGBT and MOSFET. When a positive voltage VGE greater than the threshold is applied to the gate, a strong inversion layer will appear under the gate oxide layer to form a conductive channel. At this time, if a positive voltage VCE is applied to the collector C, the electrons in the emitter will flow continuously from the emitter E to the collector C under the action of the electric field, and the holes in the collector will flow from the collector C to the emitter E, forming a current, and the current increases linearly with the increase of the CE voltage. As the CE voltage increases, the device (IGBT and MOSFET) works in the saturation region; when the CE voltage increases further, the potential at the end of the MOS channel increases with VCE, making the voltage difference between the gate and the silicon surface very small, and thus unable to maintain the strong inversion of the silicon surface. At this time, the channel pinches off, and the current no longer grows proportionally with the increase in GE voltage. At this time, we say that the device has exited the saturation region, that is, a desaturation fault; at this time, the CE voltage rises to the bus voltage, and the current is generally 4-8 times the rated current (see the specifications of each device), the power increases abnormally, and the junction temperature rises sharply. If the device is not turned off in time, it may burn out. At this time, a desaturation protection circuit is needed; especially for highly integrated modules, because the influencing factors of the internal integrated circuit are more complicated, the desaturation fault of the driven IGBT is more complicated.

[0004] At present, the desaturation protection circuit often uses a high-speed comparator to judge the critical value of the CE voltage to achieve protection action; however, due to the high internal noise of the highly integrated module, the driving signal that drives the IGBT will have noise, which will cause the high-speed comparator to cross the critical voltage back and forth many times, resulting in abnormal conversion of the positive and negative states of the comparator and malfunction. As a result, the output signal of the high-speed comparator cannot be used as a signal to trigger the protection action, and the desaturation failure problem of the highly integrated module cannot be solved. Summary of the invention

[0005] In view of the above-mentioned defects, the purpose of the present invention is to provide a desaturation protection circuit, which can effectively avoid false triggering and is more suitable for protecting IGBTs driven by highly integrated modules.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A desaturation protection circuit comprises a highly integrated module, a detection unit and a resistor R2; a driving end of the highly integrated module is electrically connected to a gate of an IGBT, a collector of the IGBT is electrically connected to an input end of the detection unit, an emitter of the IGBT is electrically connected to a ground end of the detection unit, and an output end of the detection unit is electrically connected to a desaturation detection end of the highly integrated module;

[0008] The detection unit is used to receive the CE voltage between the collector and emitter of the IGBT and generate a trigger voltage with a delay;

[0009] The highly integrated module is used to receive the trigger voltage; when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference shutdown signal is generated to shut down the IGBT.

[0010] Furthermore, the high-integration module includes a response unit, a protection action unit and a driving unit; the input end of the response unit is used as a desaturation detection end of the high-integration module, and the output end of the driving unit is used as a driving end of the high-integration module;

[0011] The output end of the response unit is electrically connected to the input end of the protection action unit, and the output end of the protection action unit is electrically connected to the action protection end of the drive unit;

[0012] The response unit is used to receive the trigger voltage; when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference protection action signal is generated;

[0013] The protection action unit is used to enable the driving unit to generate the anti-interference shutdown signal for shutting down the IGBT when receiving the anti-interference protection action signal.

[0014] Furthermore, the anti-interference protection action signal is a step signal.

[0015] Further, the detection unit includes a capacitor C1, a resistor R1 and a diode D1; the cathode of the diode D1 is used as the input end of the detection unit, one end of the capacitor C1 is used as the output end of the detection unit, and the other end of the capacitor C1 is used as the ground end of the detection unit;

[0016] One end of the capacitor C1 is electrically connected to one end of the resistor R1 , and the other end of the resistor R1 is electrically connected to the anode of the diode D1 .

[0017] Furthermore, the response unit is a Schmitt trigger, the input end of the Schmitt trigger is used as the input end of the response unit, and the output end of the Schmitt trigger is used as the output end of the response unit.

[0018] Further, the Schmitt trigger includes MOS tube M2, MOS tube M3, MOS tube M4, MOS tube M5, MOS tube M6 and MOS tube M7; the gate of the MOS tube M6 is used as the input end of the Schmitt trigger, and the drain of the MOS tube M6 is used as the output end of the Schmitt trigger;

[0019] The gate of the MOS tube M2, the gate of the MOS tube M3, and the gate of the MOS tube M5 are all electrically connected to the gate of the MOS tube M6, the source of the MOS tube M5 and the drain of the MOS tube M4 are all connected to the VCC power supply, the source of the MOS tube M2 and the drain of the MOS tube M7 are all connected to the VSS power supply, the source of the MOS tube M6 and the drain of the MOS tube M5 are all electrically connected to the source of the MOS tube M7, the source of the MOS tube M3 and the drain of the MOS tube M2 are all electrically connected to the source of the MOS tube M4, and the drain of the MOS tube M3, the drain of the MOS tube M6, and the gate of the MOS tube M7 are all electrically connected to the gate of the MOS tube M4.

[0020] Further, when the protection action unit is used to receive the anti-interference protection action signal and multiple protection action signals; whenever the anti-interference protection action signal is received, the driving unit is enabled to generate the anti-interference shutdown signal for shutting down the IGBT.

[0021] The technical solution provided by the present invention may include the following beneficial effects: using a detection unit to connect the collector and emitter of an IGBT driven by a high-integration module, real-time monitoring of the CE voltage between the collector and the emitter, and delaying the generation of a trigger voltage; when no desaturation fault occurs in the IGBT, the trigger voltage received by the high-integration module is always less than the desaturation trigger voltage, and only when the trigger voltage is greater than or equal to the desaturation trigger voltage, will the high-integration module be triggered to generate an anti-interference shutdown signal for shutting down the IGBT; and because the detection unit generates the trigger voltage with a delay, even if the trigger voltage is greater than or equal to the desaturation trigger voltage, the high-integration module will not be triggered immediately, thereby avoiding false triggering of the desaturation protection; more importantly, the high-integration module can generate an anti-interference shutdown signal, and its anti-interference performance effectively resists the noise interference inside the high-integration module, avoiding the shutdown signal from being disturbed, resulting in incorrect desaturation protection action; thereby, the protection mechanism of the desaturation protection circuit is composed of the delayed generation of the trigger voltage by the detection unit and the anti-interference shutdown signal generated by the high-integration module, thereby making the desaturation protection circuit more suitable for desaturation fault protection of the IGBT driven by the high-integration module. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a desaturation protection circuit according to one embodiment of the present invention.

[0023] Figure 2 Yes Figure 1 Waveform diagram of the response unit shown.

[0024] Figure 3 Yes Figure 1 Circuit diagram of the response unit shown.

[0025] Among them: highly integrated module 1, detection unit 2, resistor R2, response unit 11, protection action unit 12, drive unit 13, capacitor C1, resistor R1, resistor R2, diode D1, MOS tube M2, MOS tube M3, MOS tube M4, MOS tube M5, MOS tube M6, MOS tube M7. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0027] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] Combine the following Figures 1 to 3 , describing a desaturation protection circuit according to an embodiment of the present invention.

[0030] A desaturation protection circuit comprises a highly integrated module 1, a detection unit 2 and a resistor R2; a driving end of the highly integrated module 1 is electrically connected to a gate of an IGBT, a collector of the IGBT is electrically connected to an input end of the detection unit 2, an emitter of the IGBT is electrically connected to a ground end of the detection unit 2, and an output end of the detection unit 2 is electrically connected to a desaturation detection end of the highly integrated module 1;

[0031] The detection unit 2 is used to receive the CE voltage between the collector and emitter of the IGBT and generate a trigger voltage with a delay;

[0032] The highly integrated module 1 is used to receive a trigger voltage; when the trigger voltage is greater than or equal to a built-in desaturation trigger voltage, an anti-interference shutdown signal is generated to shut down the IGBT.

[0033] The present invention proposes a preferred embodiment of a desaturation protection circuit, such as Figure 1As shown, the detection unit 2 is connected to the collector and emitter of the IGBT driven by the high-integration module 1, and the CE voltage between the collector and the emitter is monitored in real time, and the trigger voltage is generated with delay; when the IGBT does not have a desaturation fault, the trigger voltage received by the high-integration module 1 is always less than the desaturation trigger voltage, and only when the trigger voltage is greater than or equal to the desaturation trigger voltage, the high-integration module 1 will be triggered to generate an anti-interference shutdown signal for shutting down the IGBT; and because the detection unit 2 generates the trigger voltage with delay, even if the trigger voltage is greater than or equal to the desaturation trigger voltage, the high-integration module 1 will not be triggered immediately, thereby avoiding false triggering of the desaturation protection; more importantly, the high-integration module 1 can generate an anti-interference shutdown signal, and its anti-interference performance effectively resists the noise interference inside the high-integration module 1, avoiding the shutdown signal from being disturbed, resulting in incorrect desaturation protection action; thus, the protection mechanism of the desaturation protection circuit is composed of the delayed generation of the trigger voltage by the detection unit 2 and the anti-interference shutdown signal generated by the high-integration module 1, thereby making the desaturation protection circuit more suitable for the desaturation fault protection of the IGBT driven by the high-integration module 1.

[0034] Furthermore, the high-integration module 1 includes a response unit 11, a protection action unit 12 and a drive unit 13; the input end of the response unit 11 is used as a desaturation detection end of the high-integration module 1, and the output end of the drive unit 13 is used as a drive end of the high-integration module 1;

[0035] The output end of the response unit 11 is electrically connected to the input end of the protection action unit 12, and the output end of the protection action unit 12 is electrically connected to the action protection end of the drive unit 13;

[0036] The response unit 11 is used to receive a trigger voltage; when the trigger voltage is greater than or equal to a built-in desaturation trigger voltage, an anti-interference protection action signal is generated;

[0037] The protection action unit 12 is used to enable the driving unit 13 to generate an anti-interference shutdown signal for shutting down the IGBT when receiving the anti-interference protection action signal.

[0038] In this embodiment, the high-integration module 1 is composed of a response unit 11, a protection action unit 12 and a drive unit 13 to generate an anti-interference shutdown signal with anti-interference properties in cooperation with the trigger voltage of the detection unit 2; the response unit 11 mainly receives and judges the trigger voltage, and when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference protection action signal with anti-interference properties is generated, thereby ensuring that the subsequent signal transmission process will not be affected by the internal noise of the high-integration module 1; therefore, when the protection action unit 12 receives the anti-interference protection action signal, it enables the drive unit 13 to generate an anti-interference shutdown signal for shutting down the IGBT, thereby realizing the desaturation fault protection of the IGBT.

[0039] Furthermore, the anti-interference protection action signal is a step signal.

[0040] In this embodiment, the step signal is used as an anti-interference protection action signal. When it is detected that the trigger voltage is greater than or equal to the desaturation trigger voltage, the signal mutation is more obvious and is less susceptible to noise than other waveforms (such as sine waves).

[0041] Further, the detection unit 2 includes a capacitor C1, a resistor R1 and a diode D1; the cathode of the diode D1 is used as an input end of the detection unit 2, one end of the capacitor C1 is used as an output end of the detection unit 2, and the other end of the capacitor C1 is used as a ground end of the detection unit 2;

[0042] One end of the capacitor C1 is electrically connected to one end of the resistor R1 , and the other end of the resistor R1 is electrically connected to the anode of the diode D1 .

[0043] In this embodiment, when the IGBT is working normally, the voltage drop between the collector and the emitter (i.e., the CE voltage) is very low. When a desaturation fault occurs in the IGBT, the voltage drop between the collector and the emitter increases sharply, the diode D1 is cut off, and only the capacitor C1 can be charged. When the voltage on the capacitor C1 (generally the full-charge voltage) exceeds the desaturation trigger voltage of the response unit 11, the response unit 11 generates an anti-interference protection action signal. The voltage of the fully charged capacitor C1 is the trigger voltage, and the time it takes for the capacitor C1 to charge to the trigger voltage is the delay time, thereby avoiding false action to trigger the desaturation protection.

[0044] Furthermore, the response unit 11 is a Schmitt trigger, the input end of the Schmitt trigger is used as the input end of the response unit 11 , and the output end of the Schmitt trigger is used as the output end of the response unit 11 .

[0045] In this embodiment, Figure 2 As shown, the Schmitt trigger has an upper threshold (VTH1) and a lower threshold (VTH2). The upper threshold is the desaturation trigger voltage. It can flip (step signal) when the trigger voltage is greater than or equal to the upper threshold, and flip (step signal) when the trigger voltage is less than or equal to the lower threshold, which meets the design requirement that the anti-interference protection action signal is a step signal.

[0046] More importantly, a big difference between a Schmitt trigger and an inverter is that the upper threshold (VTH1) and lower threshold (VTH2) of the Schmitt trigger are different, and there is hysteresis. One big advantage of hysteresis is that the Schmitt trigger can use its hysteresis voltage to improve the anti-interference ability of the circuit. If the input noise is within the hysteresis range, the output will not flip, which meets the design requirement that the anti-interference protection action signal has anti-interference properties.

[0047] Furthermore, the Schmitt trigger includes MOS tube M2, MOS tube M3, MOS tube M4, MOS tube M5, MOS tube M6 and MOS tube M7; the gate of MOS tube M6 is used as the input end of the Schmitt trigger, and the drain of MOS tube M6 is used as the output end of the Schmitt trigger;

[0048] The gate of the MOS tube M2, the gate of the MOS tube M3, and the gate of the MOS tube M5 are all electrically connected to the gate of the MOS tube M6, the source of the MOS tube M5 and the drain of the MOS tube M4 are all connected to the VCC power supply, the source of the MOS tube M2 and the drain of the MOS tube M7 are all connected to the VSS power supply, the source of the MOS tube M6 and the drain of the MOS tube M5 are all electrically connected to the source of the MOS tube M7, the source of the MOS tube M3 and the drain of the MOS tube M2 are all electrically connected to the source of the MOS tube M4, and the drain of the MOS tube M3, the drain of the MOS tube M6, and the gate of the MOS tube M7 are all electrically connected to the gate of the MOS tube M4.

[0049] In this embodiment, Figure 3 As shown, the Schmitt trigger is preferably formed by a MOS tube, which has high integration, low power consumption and fast switching characteristics and is more suitable for integration into a high-integration module 1.

[0050] Further, when the protection action unit 12 is used to receive an anti-interference protection action signal and multiple protection action signals, whenever an anti-interference protection action signal is received, the driving unit 13 is enabled to generate an anti-interference shutdown signal for shutting down the IGBT.

[0051] In this embodiment, the protection action unit 12 in the high-integration module 1 is often used to aggregate and receive signals of all fault detections in the high-integration module 1, and then comprehensively judge to execute the shutdown of the IGBT to implement the protection action. However, based on the huge damage caused by the desaturation protection fault to the IGBT, the desaturation protection is set as the highest priority. When a desaturation fault occurs, the IGBT shutdown action is immediately executed without participating in the comprehensive judgment of other fault protections.

[0052] Other structures and operations of a desaturation protection circuit according to an embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0053] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0054] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A desaturation protection circuit, characterized in that: It includes a high-integration module, a detection unit and a resistor R2; the driving end of the high-integration module is electrically connected to the gate of the IGBT, the collector of the IGBT is electrically connected to the input end of the detection unit, the emitter of the IGBT is electrically connected to the ground end of the detection unit, and the output end of the detection unit is electrically connected to the desaturation detection end of the high-integration module; The detection unit is used to receive the CE voltage between the collector and emitter of the IGBT and generate a trigger voltage with a delay; The highly integrated module is used to receive the trigger voltage; when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference shutdown signal is generated to shut down the IGBT.

2. A desaturation protection circuit according to claim 1, characterized in that: The high-integration module includes a response unit, a protection action unit and a driving unit; the input end of the response unit is used as a desaturation detection end of the high-integration module, and the output end of the driving unit is used as a driving end of the high-integration module; The output end of the response unit is electrically connected to the input end of the protection action unit, and the output end of the protection action unit is electrically connected to the action protection end of the drive unit; The response unit is used to receive the trigger voltage; when the trigger voltage is greater than or equal to the internal desaturation trigger voltage, an anti-interference protection action signal is generated; The protection action unit is used to enable the driving unit to generate the anti-interference shutdown signal for shutting down the IGBT when receiving the anti-interference protection action signal.

3. A desaturation protection circuit according to claim 2, characterized in that: The anti-interference protection action signal is a step signal.

4. A desaturation protection circuit according to claim 1, characterized in that: The detection unit includes a capacitor C1, a resistor R1 and a diode D1; the cathode of the diode D1 is used as the input end of the detection unit, one end of the capacitor C1 is used as the output end of the detection unit, and the other end of the capacitor C1 is used as the ground end of the detection unit; One end of the capacitor C1 is electrically connected to one end of the resistor R1 , and the other end of the resistor R1 is electrically connected to the anode of the diode D1 .

5. A desaturation protection circuit according to claim 2, characterized in that: The response unit is a Schmitt trigger, the input end of the Schmitt trigger is used as the input end of the response unit, and the output end of the Schmitt trigger is used as the output end of the response unit.

6. A desaturation protection circuit according to claim 5, characterized in that: The Schmitt trigger includes MOS tube M2, MOS tube M3, MOS tube M4, MOS tube M5, MOS tube M6 and MOS tube M7; the gate of the MOS tube M6 is used as the input end of the Schmitt trigger, and the drain of the MOS tube M6 is used as the output end of the Schmitt trigger; The gate of the MOS tube M2, the gate of the MOS tube M3, and the gate of the MOS tube M5 are all electrically connected to the gate of the MOS tube M6, the source of the MOS tube M5 and the drain of the MOS tube M4 are all connected to the VCC power supply, the source of the MOS tube M2 and the drain of the MOS tube M7 are all connected to the VSS power supply, the source of the MOS tube M6 and the drain of the MOS tube M5 are all electrically connected to the source of the MOS tube M7, the source of the MOS tube M3 and the drain of the MOS tube M2 are all electrically connected to the source of the MOS tube M4, and the drain of the MOS tube M3, the drain of the MOS tube M6, and the gate of the MOS tube M7 are all electrically connected to the gate of the MOS tube M4.

7. The desaturation protection circuit according to claim 1, characterized in that: When the protection action unit is used to receive the anti-interference protection action signal and multiple protection action signals; whenever the anti-interference protection action signal is received, the driving unit is enabled to generate the anti-interference shutdown signal for shutting down the IGBT.

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