Embodiments of the invention provide a power device. The power device comprises: a switch mode power conversion circuit with power semiconductors for driving a load in response to a control signal; a controller coupled to the switch mode power conversion circuit to generate the control signal based on a predetermined current profile to be provided to the load and a maximum junction temperature of the power semiconductors; and a current injector coupled to the switch mode power conversion circuit and the controller for generating an offset current. The switch mode power conversion circuit is controlled to output the predetermined current profile or an adjusted current profile in response to the control signal, and the adjusted current profile has an offset with respect to the predetermined current profile. The offset current is equal to the offset between the adjusted current profile and the predetermined current profile and further summed with the adjusted current profile to generate the predetermined current profile to flow through the load if the control signal controls the switch mode power conversion circuit to output the adjusted current profile.