Enforcement of cost-effective energy conservation on single-fed asynchronous machine using a novel switching strategy

Electric motors consume around 30 to 80% of total energy in industries. Part load operation of which leads to lower efficiency. To improve efficiency and conserve energy under such partial load operating conditions, a novel switching strategy is proposed. Wherein, the stator and rotor windings are alternatively energized (switched) in accordance with the varying load. Adopting this technique with different ratings machine (2.2-150 kW) for linear and non-linear loads, exhibits energy saving of 5-15% and reactive power reduction in the range of 15-70%, over conventional method. Besides energy conservation, the proposed strategy involves less capital cost as well. Sensor fault detection & isolation, stability and overload protection are the additional features addressed in the controller. Techno economic analysis with existing contactor based and power electronic switching strategies are also carried out. In apart, the impact of changes in switchover point on energy savings and payback period is also analyzed.