Live condition monitoring of switching devices using SSTDR embedded PWM sequence: A platform for intelligent gate-driver architecture

In this paper, Spread Spectrum Time Domain Reflectometry (SSTDR) has been implemented for the first time across the gate and the source of a power metal oxide semiconductor field effect transistor (MOSFET) to perform the online degradation monitoring of switching devices as well as the overall converter. To accomplish this, the SSTDR test signal is superimposed with the pulse width modulated (PWM) sequence and the reflected signals from the impedance discontinuities were processed to measure the degradation level of the MOSFET. This superimposed signal can provide device degradation information in a live circuit without altering the circuit's normal operation, and this is the most attractive feature of SSTDR. This unique feature makes this system very efficient for in-situ condition monitoring of power converters in a live circuit especially where high voltages are involved. The aim of this research is to present a platform for intelligent gate-driver architecture that enables real-time health monitoring of high-power semiconductor switches in addition to providing conventional current buffering and protection features. Finally, this in-situ monitoring was conducted on a DC-DC Buck converter, and multiple sets of test data were analyzed to verify the feasibility of the proposed technique. The experimental results demonstrate that the SSTDR test data are consistent with the aging of the power MOSFETs and do not affect the switching performance of the modulation process. The developed technique can also be applied to other power devices such as insulated gate bipolar transistors (IGBTs) and silicon carbide (SiC) MOSFETs.