Energy saving strategy on electric propulsion system integrated with doubly fed asynchronous motors

Electric propulsion system integrated with doubly-fed asynchronous motor contributes efficient characteristics and flexibility in operation. However, in perception of energy saving and full-scale speed variation, the conventional doubly fed asynchronous motor is limited by the ratings of power converters. Generally, the electrical machines are designed to attain maximum efficiency around the full load. To increase energy saving and operating speed range under lightly loaded condition, the proposed strategy injects a low voltage DC supply to the stator winding instead of full rated AC supply. Wherein the DC supply is obtained from the converter's DC-link instead of external source. The proposed system is mathematically modelled using Matlab/Simulink tool and implemented experimentally with a 2.2 kW doubly fed asynchronous motor. In addition to this, the comparative energy conservation analysis of an electric propulsion system (2 MW) with the proposed strategy is carried out as a case study.