Single-tube DESAT protection circuit

Abstract

The utility model discloses a single-tube DESAT protection circuit. The single-tube DESAT protection circuit comprises an optocoupler U2, resistors R2 to R12, capacitors C2 to C8, diodes D2 to D4, triodes T2 to T3 and an IGBT transistor T4, the PWM wave is input to the optocoupler U2 through a resistor R2 and a resistor R3; a pin 5 of the optocoupler U2 is connected with a base electrode of the triode T2 and a base electrode of the triode T3 through a resistor R5; a diode D2 is connected in series with a resistor R8 and then is respectively connected in parallel with a resistor R9, a resistor R10 and a resistor R11, and the other end of the diode D2 is connected with a grid electrode of an IGBT transistor T4; one end of a resistor R12, a capacitor C8 and a diode D4 which are connected in parallel is connected with a grid electrode of the IGBT transistor T4, and the other end of the resistor R12, the capacitor C8 and the diode D4 is connected with an emitting electrode of the IGBT transistor T4 and is connected with a VEUH power supply terminal; and a grid electrode of the IGBT transistor T4 is connected with a VCC18VUH power supply terminal through a diode D6. The single-tube DESAT protection circuit provided by the utility model has the advantages that reliable and effective short-circuit detection protection is realized at lower cost, the safe operation of the IGBT driving module is ensured, and the like.

Description

Technical Field

[0001] The utility model relates to a triode protection circuit, in particular to a low-cost single-tube DESAT (Desaturation) protection circuit. Background Art

[0002] The motor controller is the core component of the motor drive system of new energy electric vehicles, among which the IGBT drive module is the most important power unit. The insulated-gate bipolar transistor (IGBT) combines the advantages of the giant transistor (GTR) and the power field effect transistor (Power MOSFET), has good characteristics, and is widely used. The desaturation of IGBT refers to the current and voltage relationship curve of the IGBT in the saturation region under normal working conditions. At this time, the IGBT is similar to a switch with a very low on-resistance. However, when the current of the IGBT reaches a certain level or its junction temperature exceeds the allowable range, its voltage drop will be significantly higher than the voltage drop during normal operation, resulting in changes in the conduction characteristics of the IGBT, increased power loss, reduced efficiency, and even possible overheating and damage to the equipment. Under vector control, the IGBT drive module converts the high voltage of the power battery into three-phase AC to drive the motor to operate normally. Therefore, the operation of the IGBT drive module requires high reliability, among which the short-circuit fault of the IGBT drive module is an important factor affecting reliability. Therefore, reliable and effective short-circuit detection and protection is an important guarantee for the safe operation of the IGBT drive module. The short-circuit detection protection currently widely used in IGBT driver modules is basically based on a dedicated integrated circuit with three phases and six bridge arms. In some low-cost applications, the existing solutions often bring heavy cost pressure.

[0003] DESAT protection is a protection mechanism used to prevent device damage or burning caused by current or voltage overload. It monitors the saturation of the power switching device and quickly triggers the protection mechanism to prevent device damage. The working principle of DESAT protection includes three steps: monitoring device saturation, triggering protection and protection action. Monitoring device saturation is to measure the saturation of the power switching device through a sensor or circuit. Once the saturation is found to be too high, the protection mechanism is immediately triggered. The protection action is to quickly cut off the current or voltage of the power switching device through the action circuit. The DESAT protection mechanism includes overcurrent protection, overvoltage protection and transient protection, which can effectively prevent current or voltage overload from causing device damage or burning.

[0004] The existing IGBT drive module short circuit detection protection circuit is as follows Figure 3As shown, it mainly consists of an IGBT drive dedicated integrated circuit U1, an IGBT tube T1 in an IGBT drive module, a high-voltage diode D1, a high-voltage resistor R1 and a blanking capacitor C1. The integrated circuit U1 is provided with circuits such as a current source and a comparator. When the IGBT tube T1 is turned off, the current source is bypassed internally, the potential of the blanking capacitor C1 is clamped at a low potential, the internal comparator will not flip, and the short-circuit fault signal will not be fed back; when the IGBT tube T1 is turned on, it gradually enters the saturated conduction state, the current source flows through the high-voltage resistor R1, the high-voltage diode D1 and the IGBT tube to form a loop, and the comparator will not flip and feed back the fault signal; and when the IGBT tube T1 is short-circuited, desaturation will occur, the working voltage quickly rises from the saturation voltage drop to the DC bus voltage, the high-voltage diode D1 will immediately reverse and cut off, the current source charges the blanking capacitor C1, and the potential of the blanking capacitor C1 rises linearly. When the threshold voltage value set inside the integrated circuit U804 is reached, the comparator flips and feeds back the fault signal, so as to safely shut down the faulty IGBT tube T1, which plays a protective role.

[0005] In the prior art, the six bridge arms of the three phases all use an IGBT drive dedicated integrated circuit U1 with short-circuit detection protection. Figure 3 In the embodiment, the model of the IGBT driver dedicated integrated circuit U1 is ACFJ-3439T. Since the IGBT driver dedicated integrated circuit U1 is expensive, the overall cost of the circuit is high, which will form a considerable cost pressure in the low-cost product design. Utility Model Content

[0006] The utility model aims to avoid the deficiencies existing in the above-mentioned prior art and provides a single-tube DESAT protection circuit, which can realize reliable and effective short-circuit detection protection and ensure the safe operation of the IGBT drive module at a relatively low cost.

[0007] The utility model adopts the following technical solutions to solve the technical problems.

[0008] The utility model is a single-tube DESAT protection circuit, which is characterized by comprising an optical coupler U2, resistors R2-R12, capacitors C2-C8, diodes D2-D4, transistors T2-T3 and an IGBT transistor T4;

[0009] The PWM wave is input to the optocoupler U2 through the resistor R2 and the resistor R3; the resistor R2 is connected to the pin 1 of the optocoupler U2, and the resistor R3 is connected to the pin 3 of the optocoupler U2; one end of the resistor R4 is connected to the pin 1 of the optocoupler U2, and the other end of the resistor R4 is connected to the pin 3 of the optocoupler U2;

[0010] One end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the pin 6 of the optocoupler U2, and the other end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the VE_UH power supply terminal; the pin 6 of the optocoupler U2 is connected to the VCC18V_UH power supply terminal;

[0011] One end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the pin 4 of the optocoupler U2, and the other end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the VE_UH power supply terminal; the pin 4 of the optocoupler U2 is connected to the VE_UH power supply terminal;

[0012] Pin 5 of the optocoupler U2 is connected to the base of the transistor T2 and the base of the transistor T3 through the resistor R5, and the resistor R5 is connected to the emitter of the transistor T2 through the resistor R7; the collector of the transistor T2 is connected to the VCC18V_UH power supply terminal, and the collector of the transistor T2 is connected to the VE_UH power supply terminal through the capacitor C6;

[0013] The resistor R5 is connected to the collector of the transistor T3 through the resistor R6; the collector of the transistor T3 is connected to the VEE5V_UH power supply terminal, and the collector of the transistor T3 is connected to the VE_UH power supply terminal through the capacitor C7; the emitter of the transistor T3 is connected to the emitter of the transistor T2;

[0014] The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and one end of the diode D2 is connected to the emitter of the transistor T3 and the emitter of the transistor T2. The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and the other end of the diode D2 is connected to the gate of the IGBT transistor T4.

[0015] One end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the gate of the IGBT transistor T4, and the other end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the emitter of the IGBT transistor T4 and to the VE_UH power supply terminal;

[0016] The gate of the IGBT transistor T4 is connected to the VCC18V_UH power supply terminal via a diode D6.

[0017] The structural features of a single-tube DESAT protection circuit of the utility model are also as follows:

[0018] Furthermore, the optical coupler U2 is ACPL-W341.

[0019] Furthermore, the diode D4 is a bidirectional voltage regulator diode.

[0020] Compared with the prior art, the beneficial effects of the utility model are embodied in:

[0021] The utility model discloses a single-tube DESAT protection circuit, comprising an optical coupler U2, resistors R2-R12, capacitors C2-C8, diodes D2-D4, transistors T2-T3 and an IGBT transistor T4; a PWM wave is input to the optical coupler U2 through the resistor R2 and the resistor R3; a pin 5 of the optical coupler U2 is connected to the base of the transistor T2 and the base of the transistor T3 through the resistor R5; the diode D2 is connected in series with the resistor R8, and the other end thereof is connected to the gate of the IGBT transistor T4 after being respectively connected in parallel with the resistor R9, the resistor R10 and the resistor R11; one end of the resistor R12, the capacitor C8 and the diode D4 is connected in parallel with the gate of the IGBT transistor T4, and the other end is connected to the emitter of the IGBT transistor T4 and is connected to a VE_UH power supply terminal; the gate of the IGBT transistor T4 is connected to a VCC18V_UH power supply terminal through a diode D6.

[0022] The single-tube DESAT protection circuit of the utility model has the advantages of realizing reliable and effective short-circuit detection protection at a relatively low cost, ensuring the safe operation of the IGBT drive module, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The utility model is a circuit schematic diagram of a single-tube DESAT protection circuit.

[0024] Figure 2 It is the IGBT characteristic curve in the utility model.

[0025] Figure 3 The schematic diagram of the circuit of the prior art.

[0026] The present invention is further described below through specific implementation methods in conjunction with the accompanying drawings. DETAILED DESCRIPTION

[0027] See also Figure 1-2 The utility model is a single-tube DESAT protection circuit, which is characterized by comprising an optical coupler U2, resistors R2-R12, capacitors C2-C8, diodes D2-D4, transistors T2-T3 and an IGBT transistor T4;

[0028] The PWM wave is input to the optocoupler U2 through the resistor R2 and the resistor R3; the resistor R2 is connected to the pin 1 of the optocoupler U2, and the resistor R3 is connected to the pin 3 of the optocoupler U2; one end of the resistor R4 is connected to the pin 1 of the optocoupler U2, and the other end of the resistor R4 is connected to the pin 3 of the optocoupler U2;

[0029] One end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the pin 6 of the optocoupler U2, and the other end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the VE_UH power supply terminal; the pin 6 of the optocoupler U2 is connected to the VCC18V_UH power supply terminal;

[0030] One end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the pin 4 of the optocoupler U2, and the other end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the VE_UH power supply terminal; the pin 4 of the optocoupler U2 is connected to the VE_UH power supply terminal;

[0031] Pin 5 of the optocoupler U2 is connected to the base of the transistor T2 and the base of the transistor T3 through the resistor R5, and the resistor R5 is connected to the emitter of the transistor T2 through the resistor R7; the collector of the transistor T2 is connected to the VCC18V_UH power supply terminal, and the collector of the transistor T2 is connected to the VE_UH power supply terminal through the capacitor C6;

[0032] The resistor R5 is connected to the collector of the transistor T3 through the resistor R6; the collector of the transistor T3 is connected to the VEE5V_UH power supply terminal, and the collector of the transistor T3 is connected to the VE_UH power supply terminal through the capacitor C7; the emitter of the transistor T3 is connected to the emitter of the transistor T2;

[0033] The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and one end of the diode D2 is connected to the emitter of the transistor T3 and the emitter of the transistor T2. The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and the other end of the diode D2 is connected to the gate of the IGBT transistor T4.

[0034] One end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the gate of the IGBT transistor T4, and the other end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the emitter of the IGBT transistor T4 and to the VE_UH power supply terminal;

[0035] The gate of the IGBT transistor T4 is connected to the VCC18V_UH power supply terminal via a diode D6.

[0036] The single-tube DESAT protection circuit of the utility model retains the driving integrated chip and its peripheral circuit of the three lower bridges in the three-phase. Figure 2 The circuit is the same as in the prior art; however, in the utility model, the driver integrated chip with the driver short-circuit detection function and its peripheral circuit are removed from the three-phase upper bridge circuit and replaced with a common optocoupler chip and corresponding peripheral circuits to isolate the primary and secondary sides of the driver, such as Figure 1As shown. The IGBT drive dedicated integrated circuit ACFJ-3439T in the prior art, while the present invention uses an optocoupler U2 and two transistors T2~T3 to replace the IGBT drive dedicated integrated circuit ACFJ-3439T. The price of a single chip in the prior art is about 10 yuan, while the price of the optocoupler U2 of the present invention is about 4 yuan, and the cost of the two transistors T2~T3 is about 1 yuan, that is, the cost of the device that replaces the IGBT drive dedicated integrated circuit ACFJ-3439T in the present invention is 5 yuan, saving 5 yuan. Then the three phases in the entire circuit save 15 yuan, that is, the whole board new solution drive circuit can be reduced by 15 yuan compared with the prior art.

[0037] At the same time, the driving power supply of the upper bridge is increased by 2V compared with the lower bridge. The upper bridge driving power supply adopts +18V power supply, and the lower bridge driving circuit adopts +16V voltage. Such a design scheme can greatly reduce the hardware cost of the driving circuit while still achieving reliable and effective short-circuit detection protection, ensuring the safe operation of the IGBT driving module.

[0038] In a specific implementation, the optical coupler U2 is ACPL-W341.

[0039] The ACPL-P341 / ACPL-W341-500E contains an AlGaAs LED that is optically coupled to an integrated circuit with a power output stage that is ideally suited for driving IGBTs and MOSFETs used in motor control inverter applications. This optocoupler is ideal for driving IGBTs and MOSFETs used in power motor control inverter applications. The high operating voltage range of the output stage provides the drive voltage required for gate control of the device. The voltage and high peak output current provided by this optocoupler make it ideal for directly driving IGBTs rated up to 1200V / 50A. For higher rated IGBTs, this optocoupler can be used to drive a discrete power stage which drives the IGBT gate.

[0040] During specific implementation, the diode D4 is a bidirectional voltage regulator diode.

[0041] A bidirectional voltage regulator diode is a surface contact crystal diode made of silicon material. The voltage regulator diode can be connected in series for use at higher voltages. By connecting in series, more stable voltage can be obtained, which is called a bidirectional voltage regulator tube. A bidirectional voltage regulator diode is a semiconductor device with very high resistance until the critical reverse breakdown voltage. When a bidirectional voltage regulator diode breaks down in reverse, within a certain current range (or within a certain power loss range), the terminal voltage remains almost unchanged, showing a voltage stabilization characteristic, and is therefore widely used in voltage stabilization power supplies and limiting circuits. The main function of a bidirectional voltage regulator diode is to protect the circuit from damage by overvoltage. When an overvoltage occurs in the circuit, the voltage regulator diode will quickly turn on, shunting the overvoltage through the diode to the ground or other circuits, so that other components in the circuit are protected from the influence of overvoltage.

[0042] The existing controller driver integrated circuit usually uses a driver integrated chip with FO protection function in the six bridge arms of the three-phase to perform short-circuit protection of the IGBT. However, when a short-circuit fault occurs, due to the individual differences of the IGBT modules, usually only one bridge arm will trigger the FO fault first. At this time, the driver integrated circuit of the bridge arm will immediately perform protection, while the driver short-circuit detection circuits designed for the other five bridge arms will not work. There is a certain redundancy in the circuit. The use of a driver integrated chip with FO protection function in each lower bridge of each phase can protect the upper and lower bridges of any phase from direct faults.

[0043] For example, when a short circuit occurs between the upper and lower bridges of the U phase, the U phase upper bridge and the U phase lower bridge will pass the short circuit current. As the short circuit current increases to a certain value, it will reach the desaturation current of the IBGT tube. Since the gate voltage of the lower bridge IGBT is lower than the gate voltage of the upper bridge IGBT, each time a short circuit fault occurs, the lower bridge IGBT will first enter desaturation, triggering the DESAT fault, and perform corresponding protection to reduce the current of the entire bridge arm. The same applies to the V and W phases.

[0044] Based on the above characteristics of the prior art, the utility model reduces the driving voltage of the three bridge arms with the driving short-circuit detection function, so that no matter which phase has a short-circuit fault, the bridge arm with the driving short-circuit detection function is used to trigger the DESAT protection. At this time, the effect of safely and effectively shutting down the IGBT can still be achieved; the driving short-circuit detection function of the three upper bridges is cancelled, and ordinary high and low voltage isolation chips are adopted, which can greatly reduce the hardware cost.

[0045] Depend on Figure 2It can be seen from the IGBT characteristic curve in that, under the condition of certain temperature, the desaturation current of the IGBT is positively correlated with the gate voltage of the IGBT. When a phase has a direct short circuit between the upper and lower bridges, the upper bridge IGBT and the lower bridge IGBT flow through the short circuit current at the same time and enter the desaturation state. The utility model sets a higher gate voltage for the upper bridge of the three-phase and a lower gate voltage for the lower bridge to ensure that when the short circuit current passes, the desaturation current of the lower bridge IGBT is reached first in the process of current increase, and the short circuit detection function of the lower bridge driver integrated chip triggers the FO fault and DESAT protection. The built-in function of the lower bridge driver integrated chip causes it to enter soft shutdown, reducing the short circuit current of the entire circuit, so that the upper and lower bridge IGBTs can be safely and reliably shut down, ensuring the safe operation of the IGBT.

[0046] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0047] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A single-tube DESAT protection circuit, characterized in that: It includes an optical coupler U2, resistors R2 to R12, capacitors C2 to C8, diodes D2 to D4, transistors T2 to T3 and an IGBT transistor T4; The PWM wave is input to the optocoupler U2 through the resistor R2 and the resistor R3; the resistor R2 is connected to the pin 1 of the optocoupler U2, and the resistor R3 is connected to the pin 3 of the optocoupler U2; one end of the resistor R4 is connected to the pin 1 of the optocoupler U2, and the other end of the resistor R4 is connected to the pin 3 of the optocoupler U2; One end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the pin 6 of the optocoupler U2, and the other end of the capacitor C2 and the capacitor C3 connected in parallel is connected to the VE_UH power supply terminal; the pin 6 of the optocoupler U2 is connected to the VCC18V_UH power supply terminal; One end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the pin 4 of the optocoupler U2, and the other end of the capacitor C4 and the capacitor C5 connected in parallel is connected to the VE_UH power supply terminal; the pin 4 of the optocoupler U2 is connected to the VE_UH power supply terminal; Pin 5 of the optocoupler U2 is connected to the base of the transistor T2 and the base of the transistor T3 through the resistor R5, and the resistor R5 is connected to the emitter of the transistor T2 through the resistor R7; the collector of the transistor T2 is connected to the VCC18V_UH power supply terminal, and the collector of the transistor T2 is connected to the VE_UH power supply terminal through the capacitor C6; The resistor R5 is connected to the collector of the transistor T3 through the resistor R6; the collector of the transistor T3 is connected to the VEE5V_UH power supply terminal, and the collector of the transistor T3 is connected to the VE_UH power supply terminal through the capacitor C7; the emitter of the transistor T3 is connected to the emitter of the transistor T2; The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and one end of the diode D2 is connected to the emitter of the transistor T3 and the emitter of the transistor T2. The diode D2 is connected in series with the resistor R8 and then connected in parallel with the resistor R9, the resistor R10 and the resistor R11, and the other end of the diode D2 is connected to the gate of the IGBT transistor T4. One end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the gate of the IGBT transistor T4, and the other end of the resistor R12, the capacitor C8, and the diode D4 connected in parallel is connected to the emitter of the IGBT transistor T4 and to the VE_UH power supply terminal; The gate of the IGBT transistor T4 is connected to the VCC18V_UH power supply terminal via a diode D6.

2. A single-tube DESAT protection circuit according to claim 1, characterized in that: The optical coupler U2 is ACPL-W341.

3. A single-tube DESAT protection circuit according to claim 1, characterized in that: The diode D4 is a bidirectional voltage regulator diode.

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