The Pulse Witdh Modulation strategy (PWM) is a fundamental technique in power electronics. It is used to control the Energy transfer by modifying the pulse width of the control signals in a power converter. In an automotive traction inverter, this PWM strategy applied to a transistor phase leg allows to convert the DC current from the battery to an AC current adapted to the motor windings. The impact of the PWM on the performances and the reliability of the engine have been widely studied in the litterature. However, the impact of the PWM strategy on the reliability and the ageing of the semiconductor devices inside the power modules has not been adressed. This is particularly true for the power modules intagrating wide bandgap semiconductors (eg: SiC) which are widely used for 10 years. The main objective of this thesis is to understand and model the impact of several PWM strategies on the ageing of SiC power semiconductor devices.
The thesis targets to define a link between the stress on the semicondcutor devices and the shift of its key parameters offering the possibility to define a PWM strategy able to maximize the long term performances and the lifetime of the power electronics system. By combining experimental and theroretical approaches, this thesis will contribute to improve the PWM strategies in power electronics systems.