Mechanical parameter estimation of permanent magnet synchronous machines with aiding from estimation of rotor PM flux linkage

This paper proposes a combined parameter estimation for permanent magnet synchronous machines (PMSMs), by which the rotor permanent magnet (PM) flux linkage and mechanical parameters such as the combined moment of inertia and viscous friction coefficient are estimated without the aid from nominal machine parameter values. The proposed estimation of rotor PM flux linkage is based on the addition of position offsets and does not need the information of other machine parameters or injection of currents. With the aid from estimated rotor PM flux linkage, the electromagnetic torque can be consequently calculated for the estimation of mechanical parameters at no load condition and a two-step method is employed to achieve a higher ratio of signal to noise. This combined parameter estimation is finally validated on a surface-mounted PMSM (SPMSM) and an interior PMSM (IPMSM), respectively, and shows good accuracy in tracking the variation of combined moment of inertia.