Duty Cycle based Condition Monitoring of MOSFETs in Digitally-Controlled DC-DC Converters

In this work, a duty cycle ratio-based condition monitoring method is proposed for the MOSFETs in digitally-controlled DC-DC power converters. It is demonstrated and proved with an example of buck converter. Theoretically, the average value of duty cycle ratio is positively related to the on-state resistance of MOSFET. Therefore, the proposed method enables the condition monitoring of the degradation of MOSFET. The impact of other factors, such as input voltage, temperature, loading and other components in buck converter, on the duty cycle ratio is also investigated. Experimental tests are performed in different situations. Both theoretical and experimental results indicate the feasibility of the proposed method for DC-DC converter applications. Compare to the conventional methods, the proposed method features non-invasive, without additional hardware and easily implementing.