One-line detection of rotor position for vector controlled IPMSM: Topic number: T2

Conventional vector control of IPMSM requires a motor position sensor to correctly orient the current vector orthogonally to the flux. Thus, a high degree of torque control over a wide speed range can be achieved. Rotor speed position is measured using shaft encoder which is fixed manually on the rotor such that positive edge of the home signal per one revolution Z of the shaft encoder coincides with the zero reference position of phase-A. However, shaft encoder placement may be significantly inaccurate due to human mechanical error during fixing. This paper shows that misplaced the shaft encoder not only leads to unbalance operation of the inverter and motor phases, which increases the low frequency harmonics in torque ripple and degrades the overall drive performance but also, reduces the overall torque obtained from the vector controlled drive system due to the reduction of the quadrature-axis component of current. However, a novel technique is theoretically proposed and experimentally applied to determine on-line the value of error angle between positive edge of home signal Z of the shaft encoder and zero position of phase-A, to achieve a better dynamic performance. The proposed method can be implemented online and does not require any additional hardware.