Research And Design Of Core Circuit Of An IGBT Gate Driver

In the application of medium and high power devices,due to its outstanding electrical characteristics,insulated gate bipolar transistor(IGBT)has always occupied the dominant position,from industrial AC drive control,renewable energy to life-like automotive electronics,it can be seen in all aspects such as consumer electronics.In order to make the application of IGBT more thorough and make the performance of the whole system more perfect,the gate drive circuit is proposed and becomes more and more intelligent.Whether the gate driver can turn on or off the device reasonably,monitor the various working states of the device,and take appropriate protective measures,determines the service life of the device and the safety and stability of the system.In this thesis,an IGBT gate driver is designed to realize the monitoring and protection of each working state of IGBT devices.First,the research significance and development status of IGBT gate drivers are explained,and the working characteristics,driving conditions,and protection measures of IGBT devices are introduced,and then design schemes and specific indicators are given.In view of the problem that the gate drive voltage is too low due to the power supply voltage being too low,an undervoltage protection module is added to the driver to monitor the power supply voltage in real time.When the voltage is too low,the output voltage is forced to be zero to prevent the device from turning on.For the problem of loss during operation,a desaturation over-current detection circuit is added to prevent the device from exiting the saturation zone and entering the amplifying zone to cause unnecessary loss.At the same time,it provides fault reset and fault status feedback.If the IGBT device turns off too fast,transient voltage spikes may occur,which may break down the device or cause mis-turn on.In order to solve this problem,designs such as soft turn-off and active Miller clamp are given to control the speed during the turn-off process and the peak voltage that may be generated after the turnoff.This thesis uses 0.4μm BCD technology to build a circuit in Cadence software,which mainly includes: power supply module,transimpedance amplifier,undervoltage protection,desaturation and overcurrent detection,active Miller clamp,drive output and other modules.The circuit is simulated and verified by Hspice software.The final result shows that at 25℃and TT process angle,the positive threshold of undervoltage protection is 14.195 V,the negative threshold is 13 V,the overcurrent threshold is 6.65 V,and the time for soft turn-off At8.57μs.When the gate voltage is lower than 2V,the clamping function is turned on,instantly pulling down the gate potential,the discharge of Miller current can reach 10 A.All indicators can meet the design requirements,and realize a series of protections such as undervoltage protection,overcurrent detection,active Miller clamp,and soft shutdown,etc.,with good functions.