A New Induction Motor V/f Control Capable of Starting With Lower Current and Rated Torque

Variable speed drives (VSDs) employing a V/f control dominate over 60% of industrial and commercial induction motor (IM) applications. This is the simplest VSD adjusted based on the motor nameplate information and obviates the need for complex full-parameter estimates, controller adjustments, or variable observers, which limits it to low starting torque pumping, fans, and air conditioning systems. This article introduces an enhanced V/f control-based VSD for IMs that expands the application range by increasing the starting torque to rated load conditions. Moreover, it significantly reduces the starting stator current, alleviating the electric power system. This is achieved by substituting the boost voltage with a direct current (dc) voltage and incorporating a single stator resistance estimate to consider stator drop voltage. The dc voltage is derived from a novel discrete Taylor series (TS) adaptive control system (ACS), which regulates the rated current during startup. The proposed method was successfully implemented on a VSD utilizing the c2000 TMS320F28388D control platform, requiring no additional hardware but minor algorithm adjustments, with no cost increase. Experimental validation involved two 0.25 kW parallel IMs under a Prony brake setup. A comparative analysis of the results shows significant advantages of the proposed method over some previously enhanced approaches.