Use of Parasitic Elements to Optimize the IGBT Commutation Process

摘要

This paper presents a unique gate driver technology that demonstrates reduction in switching losses based on experimental results. This technology involves the reuse of parasitic elements of a commutation cell as feedback in order to control the dI/dt in the IGBT as well as the dV/dt across it. The Reflex™ gate driver technology, which use the parasitic inductance of the emitter connection of the IGBT to finely controls the dI/dt during the commutation process, has previously been presented in literature by the author [1]. In summary, it has been demonstrated that the fine control of the dI/dt permitted by Reflex™ is an efficient method of controlling overvoltage across the IGBT at its limit of operation without any risk of failure. It also allows the control of the recovery current of the opposite diode that generates EMI noise as well as false turn-ON. In this paper, the principle of duality in power electronics and the fundamental benefits of Reflex™ gate driver technology are combined to become the starting point for development of a system that will enable us to control dV/dt across the IGBT as well. This control, which keeps the IGBT in the linear region, allows the Reflex™ gate driver technology to react without any delay, improving the dynamic of the closed loop and allowing an even greater reduction in switching losses. [1] Cyr Jean-Marc, TM4 inc.: