Active gate drive circuits for IGBTs

Applications of IGBTs in high power converters have been expanding rapidly with the introduction of high voltage IGBTs. This thesis deals with an active gate drive technique to optimize the utilization of high power IGBTs, based on a combination of several requirements that are necessary for good switching performance under hard switching conditions. Specifically, the scheme combines together the slow drive requirements for low noise and switching stress and the fast drive requirements for high speed switching and low switching energy loss. The resulting circuit is called a three-stage active gate drive and its performance has been studied under a variety of operating conditions. These experiments bring out the conflicting requirements of a conventional gate drive circuit design and demonstrate that the proposed three-stage active gate drive technique can be an effective solution.; Reliability of the power converter is a fundamental concern in high power applications. Protection requires identification of faults during the operation of a power semiconductor switch and the activation of suitable remedial actions. An active protection circuit for the fast and precise clamping and safe shutdown of fault current in IGBTs has been investigated. This circuit allows the operation of the IGBT with a higher on-state gate voltage, which can thereby reduce the conduction loss in the device, without compromising the short circuit protection characteristics. Fault current limiting gate control can considerably improve the fault endurance capability of IGBTs.; The combination of active gate drive and fault current limiting protection technology can be used to obtain high performance switching and protection characteristics in IGBTs. The proposed three-stage active gate drive technique has been verified to operate under the wide range of temperature conditions experienced by the devices. Experimental results with conventional and three-stage active gate drive circuits have been obtained and analyzed with punch-through and non-punch-through high voltage IGBTs.; The proposed active gate driving techniques will allow the design of a more flexible gate drive that can be optimized for individual IGBTs. Such a gate drive hardware will be universal in nature and can be integrated into the Power Electronic Building Block.