Modelling and design of active thermal controls for power electronics of motor drive applications

One of the major factors that affects the overall efficiency and reliability of power electronics systems is the dynamical variation of the thermal stress which occurs in the power semiconductor devices. Therefore, the main objective of this paper consists of designing and implementing a series of active thermal control methods for the power devices of a motor drive application. The motor drive system together with the thermal cycling of the power devices have been modelled, and adverse temperature swings could be noticed during the start-up and deceleration periods of the motor. Based on the electrical response of the system, the junction temperature of the semiconductor devices is estimated, and consequently three active thermal control methods are proposed and practically designed with respect to the following parameters: switching frequency, deceleration slope and modulation technique. Finally, experimental results are provided in order to validate the effectiveness of the proposed control methods.