A driving circuit for improving the overcurrent capability of IGBT

Abstract

The present invention discloses a driving circuit for improving the overcurrent capacity of an IGBT, comprising a diode D1, a comparator U1, a transistor Q1, a voltage stabilizing diode ZD1 and a voltage stabilizing diode ZD2, wherein the cathode of the diode D1 is connected to the collector of the IGBT, the negative input terminal of the comparator U1 is connected to the anode of the diode D1, the negative input terminal of the comparator U1 is also connected to the anode of a power supply through a resistor R9, the positive input terminal of the comparator U1 is connected to the anode of a power supply through a resistor R4, the output terminal of the resistor R4 is grounded through a resistor R5, and the output terminal of the comparator U1 is grounded. The output end is connected to the base of the transistor Q1, the positive electrode of the Zener diode ZD1 is connected to the emitter of the IGBT, and the negative electrode is connected to the collector of the transistor Q1. The positive electrode of the Zener diode ZD2 is respectively connected to the negative electrode of the Zener diode ZD1 and the collector of the transistor Q1, and the negative electrode of the Zener diode ZD2 is grounded through the emitter of the transistor Q1. Through the above settings, the present invention can adjust the emitter potential in real time through the Zener diode ZD1 and the Zener diode ZD2 to improve the turn-off current capability and short-circuit tolerance capability of the IGBT.

Description

Technical Field

[0001] The present invention relates to the field of IGBT driving technology, and in particular to a driving circuit for improving the overcurrent capability of an IGBT. Background Art

[0002] The power density of IGBT is getting higher and higher. The IGBT on the market has the characteristics of low on-state voltage drop and small switching loss, but the short-circuit capability and large current shutoff capability are weakened. At present, most of the IGBT drive protection circuits are processed on the drive output circuit, which is costly and complex in structure, and most of them are used for short-circuit protection of high-power motor drive. There are relatively few corresponding solutions for small and medium power and power supply, and the drive protection circuit is not designed for the latest generation of IGBT. Furthermore, most of the current drivers use overcurrent soft shutdown technology and multi-level shutdown technology, which require special drive chips, and even CPU protection IGBT. The structure is complex and the cost is high, which is more suitable for high-power applications and motor applications. In addition, the system stops working after a fault occurs, and software or manual reset and restart are required. It is not suitable for small power and power supply applications. The present invention is mainly for designing a flexible drive optimization circuit for IGBTs with small and medium power and power supply. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems existing in the background technology and propose a driving circuit for improving the overcurrent capacity of IGBT, including a diode D1, a comparator U1, a transistor Q1, a voltage regulator diode ZD1 and a voltage regulator diode ZD2. The cathode of the diode D1 is connected to the collector of the IGBT, the negative input terminal of the comparator U1 is connected to the anode of the diode D1, and is also connected to the anode of the power supply through a resistor R9. The positive input terminal of the comparator U1 is connected to the anode of the power supply through a resistor R4, the output terminal of the resistor R4 is grounded through a resistor R5, the output terminal of the comparator U1 is connected to the base of the transistor Q1, the anode of the voltage regulator diode ZD1 is connected to the emitter of the IGBT, and the cathode is connected to the collector of the transistor Q1, the anode of the voltage regulator diode ZD2 is respectively connected to the cathode of the voltage regulator diode ZD1 and the collector of the transistor Q1, the cathode of the voltage regulator diode ZD2 is grounded through the emitter of the transistor Q1, and the gate of the IGBT is connected to the input signal.

[0004] Furthermore, the power supply includes an isolation transformer T1, a diode D2, a capacitor C3 and a capacitor C4. The live wire end of the secondary side of the isolation transformer T1 is connected to the positive electrode of the diode D2, and the neutral wire end of the secondary side is grounded. The cathode of the diode D2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to one end of the capacitor C4, and the other end of C4 is grounded.

[0005] Furthermore, a middle point between the capacitor C3 and the capacitor C4 is connected to the emitter of the IGBT.

[0006] Furthermore, the cathode of the diode D2 is connected to the resistor R4 and the resistor R9 respectively.

[0007] Furthermore, it also includes a transistor Q2 and a transistor Q3, the collector of the transistor Q2 is connected to the cathode of the diode D2, the emitter of the transistor Q2 is respectively connected to the emitter of the transistor Q3 and the gate of the IGBT, and the collector of the transistor Q3 is grounded.

[0008] Furthermore, the base of the transistor Q2 and the base of the transistor Q3 are used to be connected to an input signal.

[0009] Furthermore, a resistor R8 is included, one end of the resistor R8 is connected to the emitter of the transistor Q2 and the emitter of the transistor Q3 respectively, and the other end of the resistor R8 is connected to the gate of the IGBT.

[0010] Furthermore, a resistor R7 is included, one end of which is connected to the input signal, and the other end of which is respectively connected to the base of the transistor Q2 and the base of the transistor Q3.

[0011] Compared with the prior art, the present invention has the following beneficial technical effects: Based on the above settings, when the IGBT is normally turned on, the voltage drop is lower than the reference value after the voltage is divided by the resistor R4 and the resistor R5, the comparator U1 outputs a high level, the transistor Q1 is turned on and the voltage regulator diode ZD2 is shielded, at this time only the voltage regulator diode ZD1 works, the IGBT emitter potential is 5V, and the driving voltage is 15V. When the IGBT current is too large, the voltage from the collector to the emitter increases, causing the diode D1 to be cut off, and its anode is affected by the +20V voltage, and the value given to the comparator U1 is higher than the reference voltage. At this time, the output is low, and the transistor Q1 is turned off. At this time, the voltage regulator diode ZD1 and the voltage regulator diode ZD2 both play a voltage stabilizing role, the emitter potential reaches 7-9V, and the driving voltage is 11-13V, so as to improve the IGBT's turn-off current capability and short-circuit tolerance capability. In summary, the present invention utilizes the characteristics of high correlation between the IGBT switching characteristics and the driving voltage. The driving voltage is reduced under high current conditions to achieve reliable switching of the IGBT. Specifically, the emitter potential is adjusted in real time through the Zener diodes ZD1 and ZD2 to improve the turn-off current capability and short-circuit tolerance capability of the IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a circuit schematic diagram of the present invention. DETAILED DESCRIPTION

[0013] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0014] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0015] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or a specific connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0016] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0017] like Figure 1 As shown, the present invention proposes a driving circuit for improving the overcurrent capacity of IGBT, including a diode D1, a comparator U1, a transistor Q1, a voltage regulator diode ZD1 and a voltage regulator diode ZD2, the cathode of the diode D1 is connected to the collector of the IGBT, the negative input terminal of the comparator U1 is connected to the anode of the diode D1, and is also connected to the anode of the power supply through a resistor R9, the positive input terminal of the comparator U1 is connected to the anode of the power supply through a resistor R4, the output terminal of the resistor R4 is grounded through a resistor R5, the output terminal of the comparator U1 is connected to the base of the transistor Q1, the anode of the voltage regulator diode ZD1 is connected to the emitter of the IGBT, and the cathode is connected to the collector of the transistor Q1, the anode of the voltage regulator diode ZD2 is respectively connected to the cathode of the voltage regulator diode ZD1 and the collector of the transistor Q1, the cathode of the voltage regulator diode ZD2 is grounded through the emitter of the transistor Q1, and the gate of the IGBT is connected to the input signal.

[0018] Furthermore, in the present embodiment, the power supply includes an isolation transformer T1, a diode D2, a capacitor C3 and a capacitor C4, the live wire end of the secondary side of the isolation transformer T1 is connected to the positive electrode of the diode D2, the neutral wire end of the secondary side is grounded, the cathode of the diode D2 is connected to one end of the capacitor C3, the other end of the capacitor C3 is connected to one end of the capacitor C4, and the other end of C4 is grounded.

[0019] Furthermore, in this embodiment, the middle point between the capacitor C3 and the capacitor C4 is connected to the emitter of the IGBT.

[0020] Furthermore, in this embodiment, the cathode of the diode D2 is connected to the resistor R4 and the resistor R9 respectively.

[0021] Furthermore, in this embodiment, a transistor Q2 and a transistor Q3 are also included, the collector of the transistor Q2 is connected to the cathode of the diode D2, the emitter of the transistor Q2 is respectively connected to the emitter of the transistor Q3 and the gate of the IGBT, and the collector of the transistor Q3 is grounded.

[0022] Furthermore, in this embodiment, the base of the transistor Q2 and the base of the transistor Q3 are used to be connected to the input signal.

[0023] Furthermore, in this embodiment, a resistor R8 is also included, one end of the resistor R8 is connected to the emitter of the transistor Q2 and the emitter of the transistor Q3 respectively, and the other end of the resistor R8 is connected to the gate of the IGBT.

[0024] Furthermore, in this embodiment, a resistor R7 is also included, one end of the resistor R7 is connected to the input signal, and the other end of the resistor R7 is respectively connected to the base of the transistor Q2 and the base of the transistor Q3.

[0025] It should be noted that the diode D1 of the present invention can also be detected in other ways, such as deleting the diode D1 and replacing it with an error signal input. Furthermore, the transistor Q2 and the transistor Q3 can be equivalently replaced with the comparator U2.

[0026] Through the above settings, when the IGBT is normally turned on, the voltage drop is lower than the reference value after the resistor R4 and the resistor R5 divide the voltage, the comparator U1 outputs a high level, the transistor Q1 is turned on and the Zener diode ZD2 is shielded. At this time, only the Zener diode ZD1 works, the IGBT emitter potential is 5V, and the drive voltage is 15V. When the IGBT current is too large, the voltage from the collector to the emitter increases, causing the diode D1 to be cut off. Because of the influence of the +20V voltage, the value given to the comparator U1 is higher than the reference voltage. At this time, the output is low and the transistor Q1 is turned off. At this time, the Zener diode ZD1 and the Zener diode ZD2 both play a role in voltage stabilization, the emitter potential reaches 7-9V, and the drive voltage is 11-13V, so as to improve the IGBT's turn-off current capability and short-circuit tolerance.

[0027] In summary, the present invention utilizes the high correlation between the switching characteristics of the IGBT and the driving voltage. The driving voltage is reduced under high current conditions to achieve reliable switching of the IGBT. Specifically, the emitter potential is adjusted in real time through the Zener diodes ZD1 and ZD2 to improve the IGBT's turn-off current capability and short-circuit tolerance capability.

[0028] The above is one or more implementation methods provided in combination with specific contents, and it is not intended that the specific implementation of the present invention is limited to these descriptions. Any similarity or similarity with the method, structure, etc. of the present invention, or any technical deduction or replacement made on the premise of the concept of the present invention, shall be regarded as the protection scope of the present invention.

Claims

1. A driving circuit for improving the overcurrent capability of an IGBT, characterized in that: It includes a diode D1, a comparator U1, a transistor Q1, a voltage regulator diode ZD1 and a voltage regulator diode ZD2, wherein the cathode of the diode D1 is connected to the collector of the IGBT, the negative input terminal of the comparator U1 is connected to the anode of the diode D1, the negative input terminal of the comparator U1 is also connected to the anode of the power supply through a resistor R9, the positive input terminal of the comparator U1 is connected to the anode of the power supply through a resistor R4, the output terminal of the resistor R4 is grounded through a resistor R5, the output terminal of the comparator U1 is connected to the base of the transistor Q1, the anode of the voltage regulator diode ZD1 is connected to the emitter of the IGBT, and the cathode is connected to the collector of the transistor Q1, the anode of the voltage regulator diode ZD2 is respectively connected to the cathode of the voltage regulator diode ZD1 and the collector of the transistor Q1, the cathode of the voltage regulator diode ZD2 is grounded through the emitter of the transistor Q1, and the gate of the IGBT is connected to the input signal.

2. A driving circuit for improving the overcurrent capability of an IGBT according to claim 1, characterized in that: The power supply includes an isolation transformer T1, a diode D2, a capacitor C3 and a capacitor C4. The live wire end of the secondary side of the isolation transformer T1 is connected to the positive electrode of the diode D2, and the neutral wire end of the secondary side is grounded. The cathode of the diode D2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to one end of the capacitor C4, and the other end of C4 is grounded.

3. A driving circuit for improving the overcurrent capability of an IGBT according to claim 2, characterized in that: The middle point between the capacitor C3 and the capacitor C4 is connected to the emitter of the IGBT.

4. A driving circuit for improving the overcurrent capability of an IGBT according to claim 3, characterized in that: The cathode of the diode D2 is connected to the resistor R4 and the resistor R9 respectively.

5. A driving circuit for improving the overcurrent capability of an IGBT according to claim 4, characterized in that: It also includes a transistor Q2 and a transistor Q3, wherein the collector of the transistor Q2 is connected to the cathode of the diode D2, the emitter of the transistor Q2 is respectively connected to the emitter of the transistor Q3 and the gate of the IGBT, and the collector of the transistor Q3 is grounded.

6. A driving circuit for improving the overcurrent capability of an IGBT according to claim 5, characterized in that: The base of the transistor Q2 and the base of the transistor Q3 are used to be connected to an input signal.

7. A driving circuit for improving the overcurrent capability of an IGBT according to claim 6, characterized in that: A resistor R8 is also included, one end of which is connected to the emitter of the transistor Q2 and the emitter of the transistor Q3 respectively, and the other end of which is connected to the gate of the IGBT.

8. A driving circuit for improving the overcurrent capability of an IGBT according to claim 7, characterized in that: It also includes a resistor R7, one end of which is connected to the input signal, and the other end of which is respectively connected to the base of the transistor Q2 and the base of the transistor Q3.

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