IGBT protection circuit and chip

Abstract

The present invention relates to the field of integrated circuits, and provides an IGBT protection circuit and chip. The IGBT protection circuit includes a switch tube, a first drive tube and a second drive tube, the gate of the first drive tube is connected to a first input signal, the gate of the second drive tube is connected to a second input signal, the drain of the first drive tube is connected to the drain of the second drive tube as a drive signal output point, and is used to output the drive signal; the gate of the switch tube is connected to an enable signal, the drain of the switch tube is connected to the gate of the second drive tube, the source of the switch tube is connected to the drive signal output point, and a path is formed between the drive signal output point and the gate of the second drive tube through the switch tube. The present invention uses a switch tube to form a path between the drive signal output point and the gate of the second drive tube, and the path can actively charge the gate of the second drive tube, turn on the second drive tube, prevent the IGBT from being mis-turned on, and improve the response speed; the switch tube is turned off by controlling the enable signal to save power consumption.

Description

Technical Field

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

[0002] IGBT (Insulate-Gate Bipolar Transistor) is a composite fully controlled voltage-driven device composed of a bipolar transistor and a MOS tube. It combines the advantages of the power transistor GTR (Giant Transistor) and the field effect transistor MOSFET. It has the advantages of high current density, low saturation voltage drop, and fast switching speed. It is widely used in industries such as industry and automobiles. Usually, the working environment of IGBT is relatively harsh and susceptible to electromagnetic interference, so protection circuits around IGBT have emerged. In industrial applications such as inverters, there are problems of IGBT mis-conduction caused by inconsistent power-on timing or electromagnetic interference, which will further cause the IGBT bridge arm to pass through, causing system failures and other problems.

[0003] An existing IGBT protection circuit for preventing erroneous output at the moment of power-on is Figure 1 As shown, by connecting a resistor R1 with a large resistance in parallel between the output terminal OUT and the gate of the driver tube N1, the gate of the driver tube N1 is actively charged to prevent the IGBT from being mis-turned on at the moment of power-on. However, due to the large resistance of the resistor R1, the response speed will be slow; and when the chip works normally and the output terminal OUT is at a high level, the resistor R1 will always have current passing through it, resulting in high power consumption. Summary of the invention

[0004] In order to solve the above technical defects, the present invention provides an IGBT protection circuit to prevent the IGBT from being mis-turned on at the moment of power-on and to improve the response speed.

[0005] The present invention provides an IGBT protection circuit, comprising: a switch tube, a first drive tube and a second drive tube;

[0006] The gate of the first driving tube is connected to a first input signal;

[0007] The gate of the second driving tube is connected to a second input signal;

[0008] The drain of the first driving tube is connected to the drain of the second driving tube, and a common point where the drain of the first driving tube is connected to the drain of the second driving tube is used as a driving signal output point for outputting a driving signal for driving the IGBT;

[0009] The gate of the switch tube is connected to an enable signal, the drain of the switch tube is connected to the gate of the second drive tube, the source of the switch tube is connected to the drive signal output point, and a path is formed between the drive signal output point and the gate of the second drive tube through the switch tube.

[0010] In an embodiment of the present invention, the IGBT protection circuit further includes a first resistor, and the source of the switch tube is connected to the drive signal output point through the first resistor.

[0011] In the embodiment of the present invention, the drive signal output point is connected to the gate of the IGBT via a second resistor.

[0012] In the embodiment of the present invention, the resistance value of the first resistor is smaller than the resistance value of the second resistor.

[0013] In the embodiment of the present invention, the switch tube is a PMOS tube.

[0014] In an embodiment of the present invention, the IGBT protection circuit further includes a capacitor, and the enable signal and the gate of the switch tube are connected to a reference ground through the capacitor.

[0015] In the embodiment of the present invention, at the moment when the IGBT protection circuit is powered on, the potential of the enable signal is the reference ground; when the IGBT protection circuit is powered on, the enable signal is flipped to a high level to turn off the switch tube.

[0016] In an embodiment of the present invention, the IGBT protection circuit further includes a first inverter and a second inverter;

[0017] The first input signal is connected to the gate of the first driving tube through the first inverter;

[0018] The second input signal is connected to the gate of the second driving tube through the second inverter.

[0019] In the embodiment of the present invention, the first driving tube is a PMOS tube, and the second driving tube is an NMOS tube.

[0020] The present invention also provides a chip, which includes the above-mentioned IGBT protection circuit.

[0021] The present invention utilizes a switch tube to form a path between a drive signal output point and a gate of a second drive tube. When the potential of the drive signal output point rises due to inconsistent power-on timing or electromagnetic interference, the path can actively charge the gate of the second drive tube, thereby turning on the second drive tube, preventing the IGBT from being mis-turned on, and improving the response speed. The switch tube is controlled by an enable signal, so that when the system is powered on and completes normal operation, the switch tube is in an off state, saving power consumption.

[0022] Other features and advantages of the technical solution of the present invention will be described in detail in the specific implementation section below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 It is a schematic diagram of an existing IGBT protection circuit;

[0025] Figure 2 is a schematic diagram of an IGBT protection circuit provided by an embodiment of the present invention;

[0026] Figure 3 It is a schematic diagram of signal waveforms of key nodes in the IGBT protection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0028] In the description of the present invention, it should be understood that the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms such as "connected" and "connection" 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 a mechanical connection, an electrical connection, or can communicate with each other; 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 present invention can be understood according to specific circumstances.

[0030] like Figure 1As shown, an existing IGBT protection circuit actively charges the gate of the driver tube N1 by connecting a resistor R1 with a large resistance in parallel between the output terminal OUT and the gate of the driver tube N1 to prevent the IGBT from being mis-turned on at the moment of power-on. However, due to the large resistance of the resistor R1, the response speed will be slow; and when the chip works normally and the output terminal OUT is at a high level, the resistor R1 will always have current passing through it, and the power consumption is relatively large. In order to solve the defects of the prior art, an embodiment of the present invention provides an IGBT protection circuit to prevent the IGBT from being mis-turned on at the moment of power-on, and the power consumption is relatively small and the response is rapid.

[0031] like Figure 2 As shown, an embodiment of the present invention provides an IGBT protection circuit, including: a switch tube S1, a first drive tube P1 and a second drive tube N1, the gate of the first drive tube P1 is connected to the first input signal DR1, the gate of the second drive tube N1 is connected to the second input signal DR2, the drain of the first drive tube P1 is connected to the drain of the second drive tube N1, and the common point where the drain of the first drive tube P1 and the drain of the second drive tube N1 are connected is used as a drive signal output point OUT, which is used to output the drive signal OUT for driving the IGBT. The gate of the switch tube S1 is connected to the enable signal EN, the drain of the switch tube S1 is connected to the gate of the second drive tube N1, and the source of the switch tube S1 is connected to the drive signal output point. A path is formed between the drive signal output point and the gate of the second drive tube N1 through the switch tube S1 to prevent the IGBT from being mis-conducted at the moment of power-on. In addition, the drain of the first drive tube P1 is connected to the drain of the second drive tube N1, which is used to drive the IGBT, and the rail-to-rail output of the voltage can be achieved.

[0032] In an embodiment of the present invention, the IGBT protection circuit further includes a first resistor R1, and the source of the switch tube S1 is connected to the drive signal output point OUT through the first resistor R1. The drive signal output point OUT is connected to the gate of the IGBT through the second resistor R2. The first resistor R1 is selected to be a resistor with a smaller resistance value, so that at least the resistance value of the first resistor R1 is smaller than the resistance value of the second resistor R2, so that when the path between the drive signal output point OUT to the gate of the second drive tube N1 is opened, a larger current can be obtained to improve the circuit response speed. The source of the switch tube S1 is connected to the drive signal output point OUT through the first resistor R1, so that the response speed of the path is faster and the current handling capacity is stronger.

[0033] In the embodiment of the present invention, the IGBT protection circuit further includes a first inverter NOT1 and a second inverter NOT2, the first input signal DR1 is connected to the gate of the first drive tube P1 through the first inverter NOT1, and the second input signal DR2 is connected to the gate of the second drive tube N1 through the second inverter NOT2. The first drive tube P1 can be a PMOS tube, and the second drive tube N1 can be an NMOS tube.

[0034] In the embodiment of the present invention, the switch tube S1 uses a PMOS tube. The enable signal EN and the gate of the switch tube S1 are connected to the reference ground through a capacitor C. At the moment of power-on, the potential of the enable signal EN is ground. At this time, when the potential of the drive signal output point OUT caused by the power-on timing or electromagnetic interference is raised to a voltage higher than the threshold voltage of the PMOS tube, the switch tube S1 will be turned on immediately. The drive signal output point OUT can charge the gate capacitance of the second drive tube N1 through the path formed by the first resistor R1 and the switch tube S1. When the second drive tube N1 is charged to turn on, the voltage of the drive signal output point OUT is quickly pulled down to ground, effectively preventing the IGBT from being mis-turned on.

[0035] At the moment of power-on, the IGBT protection circuit of the present invention has an enable signal EN whose potential is the reference ground. When power-on is completed, the enable signal EN flips to a high level to turn off the switch tube S1. The enable signal EN is a signal to measure whether the chip has completed power-on. When the chip has not completed power-on, the potential of the enable signal EN is the ground; when the chip has completed power-on, the potential of the enable signal EN is the power supply voltage. When the chip completes power-on and works normally, the enable signal EN turns off the switch tube S1 to save current loss.

[0036] like Figure 3 As shown, the working principle of the IGBT protection circuit provided by the embodiment of the present invention is: at the moment of power-on, the enable signal EN is connected to the capacitor C, and the potential cannot change suddenly, so the potential of the enable signal EN is ground. When the potential of the drive signal output point OUT caused by inconsistent power-on timing or electromagnetic interference is raised to a level higher than the threshold voltage VTP of the PMOS tube, the switch tube S1 is turned on immediately. The drive signal output point OUT charges the gate capacitor of the second drive tube N1 through the path formed by the first resistor R1 and the switch tube S1. When the potential at point X is higher than the conduction threshold voltage VTN of the second drive tube N1, the second drive tube N1 is turned on, and the voltage of the drive signal output point OUT is quickly pulled down to ground, effectively preventing the IGBT from being mis-conducted. When the system is powered on and working normally, the enable signal EN flips to a high level to turn off the switch tube S1 to reduce power consumption.

[0037] The IGBT protection circuit provided by the embodiment of the present invention has the following beneficial technical effects:

[0038] 1. The structure is simple. The switch tube S1, the first resistor R1 and the capacitor C are used to prevent the IGBT from being mis-turned on at the moment of system power-on. The circuit structure is simple, which greatly reduces the design cost.

[0039] 2. Active shutdown: A path is constructed between the drive signal output point OUT and the gate of the second drive tube N1. When the potential of the OUT terminal rises due to inconsistent power-on timing or electromagnetic interference, the path can actively charge the gate of the second drive tube N1, thereby turning on the second drive tube N1 to prevent the IGBT from being mis-turned on.

[0040] 3. Fast response speed. The switch tube S1 uses a PMOS tube, and the first resistor R1 uses a small resistor. The path formed by the two opens quickly and has strong current capacity.

[0041] 4. The power consumption is relatively small. By controlling the switch tube S1 through the enable signal EN, when the system is powered on and completes normal operation, no current flows through the first resistor R1, thus saving power consumption.

[0042] An embodiment of the present invention further provides a chip, which includes the above-mentioned IGBT protection circuit.

[0043] The optional implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings. However, the implementation modes of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention. It should also be noted that the various specific technical features described in the above specific implementation modes can be combined in any suitable manner without contradiction, and as long as the combination does not violate the concept of the implementation modes of the present invention, it should also be regarded as the content disclosed in the implementation modes of the present invention.

Claims

1. An IGBT protection circuit, characterized in that: include: A switch tube, a first drive tube and a second drive tube; The gate of the first driving tube is connected to a first input signal; The gate of the second driving tube is connected to a second input signal; The drain of the first driving tube is connected to the drain of the second driving tube, and a common point where the drain of the first driving tube is connected to the drain of the second driving tube is used as a driving signal output point for outputting a driving signal for driving the IGBT; The gate of the switch tube is connected to the enable signal, the drain of the switch tube is connected to the gate of the second drive tube, the source of the switch tube is connected to the drive signal output point, and a path is formed between the drive signal output point and the gate of the second drive tube through the switch tube; at the moment when the IGBT protection circuit is powered on, the potential of the enable signal is the reference ground; when the IGBT protection circuit is powered on, the enable signal flips to a high level to turn off the switch tube.

2. The IGBT protection circuit according to claim 1, characterized in that: The IGBT protection circuit also includes a first resistor; The source of the switch tube is connected to the drive signal output point through the first resistor.

3. The IGBT protection circuit according to claim 2, characterized in that: The driving signal output point is connected to the gate of the IGBT through a second resistor.

4. The IGBT protection circuit according to claim 3, characterized in that: The resistance value of the first resistor is smaller than the resistance value of the second resistor.

5. The IGBT protection circuit according to claim 1, characterized in that: The switch tube is a PMOS tube.

6. The IGBT protection circuit according to claim 5, characterized in that: The IGBT protection circuit also includes a capacitor; The enable signal and the gate of the switch tube are connected to a reference ground through the capacitor.

7. The IGBT protection circuit according to claim 1, characterized in that: The IGBT protection circuit also includes a first inverter and a second inverter; The first input signal is connected to the gate of the first driving tube through the first inverter; The second input signal is connected to the gate of the second driving tube through the second inverter.

8. The IGBT protection circuit according to claim 1, characterized in that: The first driving tube is a PMOS tube, and the second driving tube is an NMOS tube.

9. A chip, characterized in that: The chip comprises the IGBT protection circuit according to any one of claims 1 to 8.

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