On-state voltage drop based derating/uprating on a MW converter to improve reliability

Power semiconductor devices are the most fragile components limiting reliability of power converters, where major stresses are temperature dependent parameters. Typically, the operating virtual maximum junction temperature is specified by a manufacturer for each individual device. The thermal system and operating load are designed based on this number. Online monitoring of an on-state collector-emitter voltage (υce,on) and a junction temperature is necessary to ensure the design performance within a safe limit and also to make this method applicable for derating/uprating power. This paper presents the real time measurement of υce,on and thereby the junction temperature estimation in high power converters. Knowing these parameters online, the maximum power capability can be detected. The operating maximum junction temperature is selected and thereby based on the operating condition the derating of power is shown for a megawatt (MW) converter. An experimental setup including online monitoring is described and the measurement of power derating is presented at the specified conditions.