Thermal regulation as control reference in electric drives

Recognition of technical specification for electric drives thermal sizing is quite challenging in both transportation applications and distributed generating systems. In particular, components of electric drives for hybrid farm equipment, like tractors as well large combines, are often overstressed because of either high ambient temperature or overload working condition. The electric drive components are mainly chosen with reference to average power and energy considerations; however, overload operating conditions can occur for time durations not established in advance, as well quite unpredictable thermal conditions are associated to environment related to diesel engines in hybrid configurations. For this reason, it is convenient to provide the control system of the electric drive unit with a sort of thermal regulation of the electric and electronic equipment, which can be achieved by adjusting some operating conditions, as dc-link voltage, modulation strategy and switching frequency, in order to reduce thermal stress on either power electronic devices or electrical machines windings.