Fast high-voltage, high-current switching using stacked IGBTs By: Zarir Ghasemi Supervisor: Prof. S. J. Macgregor Institute for Energy and Environment University of Strathclyde Glasgow

Pulsed Power System with Examples of System Components

Comparison of solid-state switching devices

An X2 Non-Inverting Blumlein Cable Generator

Problems associated with stacking IGBTs Signal synchronisation Signal isolation (Magnetic or Optical ) Voltage sharing (Passive or Active snubbers) Current sharing Stack configuration Diagnostic Protection

Photograph of 55 IGBT stack with voltage and current ratings of 2 Photograph of 55 IGBT stack with voltage and current ratings of 2.5 kV and 250 A, respectively.

Voltage across the device and output pulse for two 1.2 kV IGBTs

Photograph of 10 kV, 400 A stack of IGBT modules consisting of 105 1 Photograph of 10 kV, 400 A stack of IGBT modules consisting of 105 1.2 kV IGBTs.

Photograph of 10 kV, 400 A stack of IGBT modules, optically triggered

Photograph of 3 kV, 2 kA Marx generator

Conclusion The IGBT was determined to be the preferred device for stacking IGBT’s can handle a peak current of five times their normal rating during short-pulse conducting, if they are driven by fast gate pulses. The dual degradation of the collector-emitter voltage exists in some of available IGBT devices. A prototype stack at voltage and current ratings of 10 kV and 400 A, with a voltage fall-time of about 45 ns was successfully tested. An optically-coupled stack of IGBTs with voltage and current ratings of 10 kV and 400 A was built and operated in a generator, used for Pulsed Electric Field (PEF) inactivation of microorganisms. A modular Marx generator, having an output voltage rating of 3 kV and a peak current rating of 2 kA, was designed and evaluated.