High Performance Controllers Based on Real Parameters to Account for Parameter Variations due to Iron Saturation

Abstract : With the increase in electric power on military ground vehicle platforms, electrically driven accessories are replacing existing hydraulic, belt, and gear-driven loads. Permanent Magnet Synchronous Machines (PMSM) are often selected to drive these accessories, and are under consideration for the main engine generator, due to their torque density and efficiency being among the highest available. To maximize the efficiency of a PMSM, accurate knowledge of its parameters is required across the entire operating range. Efficient control of the onboard electric drives will help reduce fuel consumption in the ground vehicle fleet. This paper presents the effects of iron saturation on the performance of a PMSM drive. Iron saturation depends on the amount of current injected into the motor and it restricts the amount of flux linkage that can be generated. PMSMs are controlled using a two axis space vector representation. Ideally, the control is decoupled, such that the flux linkage production in one axis is not affected by the current in the other axis. However, iron saturation alters this behavior and the flux linkages become dependent on both axis currents. This paper demonstrates this phenomenon by parametric experimental characterization of two permanent magnet synchronous motors. A simple but dependable method to approximate and include all the saturation effects, based on real parameters, is proposed. The effectiveness of the proposed method is validated through a simulation using the experimentally extracted parameters.