Efficiency increasing of induction motor scalar control systems

The main peculiarities of the centrifugal fans' and pumps' electric drives are highlighted. The induction motor electric drives are thoroughly described to satisfy the requirements of such applications. The relevance of electric drives with a scalar control system providing the minimum of the induction motor stator current is shown. The scalar control system delivering the search control of the induction motor stator current in the steady state is designed. The search control is implemented by small-magnitude triangular additional voltage injection that increases or decreases the stator voltage and leads to corresponding change of the stator current. The designed system could be implemented by the technical capacity of a standard industrial frequency converter. The simulation results obtained by Matlab for the electric drive with the 11 kW induction motor are presented.