Lifetime extension by varying switching frequency of inverters based on junction temperature estimation

In this paper, a new variable switching frequency algorithm is proposed in which the switching frequency is varied in response to the variation in the operating conditions. The proposed algorithm is based on online junction temperature estimation. The proposed estimation model is based on Foster-type and power loss calculations for PWM IGBT inverter system. The proposed variable switching frequency algorithm can decrease power losses and so increase the efficiency of the inverter without deteriorating the harmonic performance Moreover, the lifetime of the inverter can be increased due to the narrower junction temperature profile that can be achieved by this algorithm when compared to the fixed switching frequency counterpart.