Design Of A Closed-loop Driver Chip For IGBT

IGBT devices combine the advantages of MOSFETs and bipolar transistors with high input impedance,low turn-on voltage,high voltage tolerance and high current tolerance.Therefore,IGBT devices are widely used in fields such as power electronic.IGBT devices generally operate under high current and high voltage conditions.As the switching frequency increases,the switching loss of IGBT devices accounts for an increasing proportion of the total loss.Compared with the conventional driving circuit,the driving chip adopting the closed-loop control mode can reduce the switching loss and increase the energy saving effect without increasing the stress of IGBT devices.When IGBT devices operate in an undervoltage condition or they are short-circuited,they are easily damaged.Therefore,a protection circuit is required to ensure safe and reliable operation of IGBT devices.In this paper,a closed-loop driving scheme is proposed by analyzing the IGBT switching characteristics.By detecting the rate of the IGBT collector-emitter voltage and the current flowing through the IGBT during the IGBT switching process,we can determine the specific switching process of the IGBT.Therefore,the IGBT gate drive current is controlled in stages to achieve the purpose of reducing switching loss.The undervoltage protection function is realized by detecting the supply voltage of the chip and comparing it with the threshold voltage.When the chip supply voltage is lower than the threshold voltage,the undervoltage protection is triggered and the IGBT is turned off.The desaturation protection function is realized by detecting the IGBT turn-on voltage and comparing it with the threshold voltage.After the IGBT is turned on for 2~3us,the IGBT turn-on voltage is detected.If the IGBT turn-on voltage is lower than the threshold voltage,the desaturation protection is triggered,and the IGBT is turned off.This paper uses HHGrace BCD350 GE process to carry out specific circuit design,including power module,feedback signal processing module,undervoltage protection module,desaturation protection module,logic control module and drive output module.Simulation verification was performed by cadence virtuoso.After completing the overall simulation and layout design of the chip,the tape was developed,and the test platform was built to test the driver chip.The test results show that the driver chip has a maximum output charging current of 2A,the reverse maximum output discharge current is 2.5A,and the undervoltage protection hysteresis comparator threshold width is 0.9V.When the IGBT device is de-saturated,the desaturation protection is completed within 10 us,and the "soft shutdown" function can be realized to meet the design requirements.Compared with the Infineon driver chip 1EDS20I12 SV,the driver chip designed in this paper reduces the switching loss by 25.75% when driving the IGBT while maintaining the same IGBT turn-off voltage overshoot.The loss reduction is obvious.