Real-time Model in the Loop analysis of PMSM for electric power steering system based on FPGA implementation

The paper presents a dual analysis of a permanent magnet synchronous machine (PMSM) designed for an electric power steering system (EPS) used in the automotive industry. Preliminary, the existing PMSM is studied using finite element analysis (FEA) in order to check flux linkage, flux density, cogging and electromagnetic torque values for different speed and current values. Structural design dimensions of the machine are given in detail in the paper as well as FEA based identified parameters used in the real-time analysis. The latter is accomplished using two field programmable gate array (FPGA) processors, each mounted on one Rseries platform, hardware tools provided by National Instruments company. One is running the analytic model of the PMSM with the parameters extracted from FEA and the second one is running the field oriented control (FOC) of the machine. The communication between the two platforms is accomplished using analog and digital IOs to mimic the behavior of the physical test bench with a real machine. Hence, the 3-phase currents are acquired using analog inputs, the position is acquired using digital lines and the PWM is sent via other 3 digital channels. Separation of the machine and converter model on one FPGA and the FOC on the second one, minimizes the gap between testing the real machine and the realtime model in the loop (RTMiL) engaged in this study. Comparative analysis of the FEA and RTMiL results will prove the accuracy of the FPGA based modelling of the PMSM and its control