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.
Highlights
The degradation of solder joints and wirebonds in traditional packaging systems usually results in an increase in the thermal resistance and a higher junction temperature [1]
The use of temperature sensitive electrical parameters (TSEPs) for identifying the junction temperature of power semiconductors is one of the main techniques used for the implementation of condition monitoring strategies [2], which can be used for assessing ageing damage, improving the lifetime of the module and defining operational constraints
Due to the impact of parasitic inductance under high dI/dt conditions, the temperature sensitivity was shown to improve when the SiC MOSFET was driven at slower switching speeds
Summary
The degradation of solder joints and wirebonds in traditional packaging systems usually results in an increase in the thermal resistance and a higher junction temperature [1]. Advanced intelligent gate drivers [4] would be a fundamental tool for implementing these techniques, where an advanced gate driver capable of momentarily implementing customized switching pulses as part of a condition monitoring strategy, would be a significant advantage In this sense, a diagnostic pulse can be designed to maximize the temperature sensitivity of the current switching rate and/or on-state resistance of the device during the parameter evaluation and perform multiple measurements to minimize ambient noise. This paper evaluates how the gate driver voltage (VGG) of SiC MOSFETs can be used to maximize the temperature sensitivity of the on-state resistance RDS-ON and the switching rate of the drain current dIDS/dt for more effective junction temperature sensing. Impact of gate driver voltage on temperature sensitivity of the onstate resistance
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