Energy Saving Theory and Approach for Asynchronous Motor Under the Periodically Variable Running Condition

For motors working on periodically variable running condition,the speed regulation approach is difficult to ensure periodicity so that the voltage regulation became a preferable scheme.Since the concept of efficiency is not appropriate for the loss analysis of generating running condition of generation,the minimum total loss is taken as the optimal objective for voltage regulation method which is analyzed and contrasted with several other energy saving approaches.First the new total losses calculation method is implemented by means of the classification of variable loss and invariable loss.Hereby,the optimal voltage curve corresponding to the minimum total losses could be conveniently obtained according to the given torque curve.Then the calculation and implementing method for optimal voltage under every running condition are put forward by use of on-line measured field input quantities.Finally,Several energy saving approaches including for intermittent power supply are comprehensively discussed and compared with the optimal voltage curve.The simulation and field test on beam pump unit show the effect and applicability of these approaches.