Evaluation of Sensorless Techniques for Surface Permanent-Magnet Integrated Motor Drive using Current-Source Inverter

Integrated motor drives (IMD) that combine power electronics and a motor into a single enclosure are attractive for a wide range of applications that extend from electric vehicle traction drives to pumps. The current-source inverter (CSI) is well-suited for development of compact and reliable IMDs since it reduces common-mode filters, eliminates dc-link capacitors, which are temperature-sensitive components, and provides higher fault tolerance than conventional voltage-source inverters with permanent magnet (PM) machines. However, the presence of an encoder compromises the reliability of an IMD and can hinder its high power density. Elimination of the encoder using rotor position estimation techniques is investigated for surface permanent magnets (SPM) machines excited by CSIs. Analytical results demonstrate that reliable motor drive operation at low speeds is possible in CSI-based IMDs without encoders.