Collector-Emitter Voltage Based Health Monitoring of Bond Wire in IGBT at Low Gate Voltage

Online health monitoring of the IGBT in power converters of electric vehicles (EVs) is necessary to enhance the system reliability. On-state collector emitter voltage,
$V_{\mathbf{CE}}$
is a commonly used health sensitive parameter (HSP) of bond wire degradation in IGBT. However, its low sensitivity with bond wire degradation makes it difficult to accurately estimate the health of bond wire. This paper proposes a health monitoring technique of bond wire degradation in IGBT by using the HSP, collector-emitter voltage in saturation region at low gate voltage
$(V_{\mathbf{CES,L}})$
. The improved sensitivity of
$V_{\mathbf{CES,L}}$
with bond wire degradation allows the accurate monitoring of the bond wire health. The mathematical analysis on the sensitivity of
$V_{\mathbf{CES,L}}$
is presented in this paper. The criteria of low gate voltage selection to determine
$V_{\mathbf{CES,L}}$
for the proposed scheme is also discussed. Further, the effect of junction temperature on
$V_{\text{CES,L}}$
value is suitably taken care of in order to represent the bond wire health correctly. Finally, the effectiveness of proposed technique is experimentally validated on an inverter prototype which is developed in the laboratory.