Impact of the gate driver voltage on temperature sensitive electrical parameters for condition monitoring of SiC power MOSFETs

Abstract

Condition monitoring using temperature sensitive electrical parameters (TSEPs) is widely recognized as an enabler for health management of power modules. The on-state resistance/forward voltage of MOSFETs, IGBTs and diodes has already been identified as TSEPs by several researchers. However, for SiC MOSFETs, the temperature sensitivity of on-state voltage/resistance varies depending on the device and is generally not as high as in silicon devices. Recently the turn-on current switching rate has been identified as a TSEP in SiC MOSFETs, but its temperature sensitivity was shown to be significantly affected by the gate resistance. Hence, an important consideration regarding the use of TSEPs for health monitoring is how the gate driver can be used for improving the temperature sensitivity of determined electrical parameters and implementing more effective condition monitoring strategies. This paper characterizes the impact of the gate driver voltage on the temperature sensitivity of the on-state resistance and current switching rate of SiC power MOSFETs. It is shown that the temperature sensitivity of the switching rate in SiC MOSFETs increases if the devices are driven at lower gate voltages. It is also shown, that depending on the SiC MOSFET technology, reducing the gate drive voltage can increase the temperature sensitivity of the on-state resistance. Hence, using an intelligent gate driver with the capability of customizing occasional switching pulses for junction temperature sensing using TSEPs, it would be possible to implement condition monitoring more effectively for SiC power devices.

An Investigation of Temperature-Sensitive Electrical Parameters for SiC Power MOSFETs

“…In [16], harmonic analysis of an IGBT converter output is used as a TSEP whereas in [17,18] the temperature dependency of the gate current in MOSFETs and IGBTs has been used as a TSEP for condition monitoring with promising results demonstrated. In the case of Si MOSFETs, the switching rate during turn ON was evaluated as a TSEP in [19], and the characteristics of SiC MOSFETs [20][21][22] suggest that the dynamic properties of SiC during turn ON can be a suitable TSEP.…”

Impact of the Gate Oxide Reliability of SiC MOSFETs on the Junction Temperature Estimation Using Temperature Sensitive Electrical Parameters

“…For the investigation presented in this paper, accelerated stress tests have been performed as the objective is characterizing the impact of the threshold voltage shift on the electrical parameters. In addition, low gate driver voltages and high gate resistances have been used to improve the temperature sensitivity of the electrical parameters as indicated in [15,16].…”

“…The on-state resistance of a MOSFET RDS-ON is comprised of 3 main components as defined in [3,15] and it is given by (1).…”

“…In the case of SiC MOSFETs, the contribution of Rch to the total on-state resistance is higher [3,15] as a thinner drift layer is required for blocking the same voltage. The channel resistance is given by (3) [3], where it can be observed that it is affected by the gate driver voltage and temperature (threshold voltage and mobility).…”

Enabling high reliability power modules: A multidisciplinary task

“…Intelligent gate drivers, like that described in reference [8] from Amantys, sensors embedded in the power module, such as micro Rogowski coils [9], and the ability to monitor the gate voltage and current are the key areas of research in order to achieve the reliable switching unit, as well as expanding the knowledge about TSEPs for silicon devices to SiC devices, despite the disadvantages of the lower temperature sensitivity of this wide bandgap semiconductor. An initial consideration on TSEPs for SiC MOSFETs has been presented in [10], but further research on the practical implementation of the proposed TSEPs has to be done.…”