A DSP-based position sensor elimination method with an on-line parameter identification scheme for permanent magnet synchronous motor drives

This paper presents a digital signal processor-based algorithm with an on-line parameter identification scheme for precision estimation of the rotor position and speed of a permanent magnet adjustable speed drive system by measuring stator currents, voltages and temperature. A modified d-q equivalent circuit model has been obtained to account for the core losses. Machine parameter variations due to saturation and temperature are included in the algorithm, which is valid for any speed, including zero speed. A simple hardware implementation to estimate the initial rotor position during the machine start-up and the implementation of position estimation algorithm, using a TMS320C25 DSP, is discussed. Because the estimation algorithm needs few instructions, it can easily be implemented in real-time vector control of permanent magnet synchronous drives. A complete vector-controlled drive system using an actively clamped resonant DC link inverter with the position estimator has been simulated, and results show that the estimated position is in close agreement with the actual rotor position of the machine.