A multiple look-up table torque controller for improved performance of IPM machines

This paper proposes a multiple lookup table based controller for operation in the complete torque and speed range of an IPM machine. A complete characterization is carried out to determine the machine fluxes for any given current. The fluxes are then used to calculate the nominal controller. A controller is then calculated for each of four sets of flux linkage data with a small flux error introduced; this is to account for small parametric error. An algorithm using airgap power and voltage is used to select a lookup table which reduces error in developed torque. Sensitivity is then used to determine the effectiveness of the proposed controller. From this, the proposed controller leads to reduced torque error and reduced sensitivity of the torque to flux error. Actual characterization data from a 10kW IPM machine is used to develop all controllers and simulations. The nominal and proposed controller is then applied to the actual IPM machine to validate the proposed controller.