A Square-Wave Voltage Injection Sensorless Control for Dual Three-Phase IPMs Robust to Open-Circuit Faults

Abstract

Conventional sensorless control methods fail to estimate the accurate rotor position in case of open circuit faults (OCFs) in dual three-phase interior permanent-magnet machine (DT-IPM) drives, resulting in poor stability of the system. OCFs regularly contain open-phase faults (OPFs) and open-switch faults (OSFs). However, the current under OSFs can be considered as a combination of a one-half period of health status with a normal current and the other half period of OPF with zero current. Consequently, OSF is regarded as a generalized OPF. Based on the general solution to OCFs, a novel high-frequency (HF) square-wave voltage injection (HFSVI) sensorless control method is proposed for DT-IPMs at low speed to improve the fault-tolerance ability, which is robust to both OPFs and OSFs. With the help of vector space decomposition, the HFSVI is implemented in the decoupling space, where the effects of OCFs, e.g., varying amplitude and extra negative-sequence component of responded HF currents, can be compensated by HF currents in both αβ- and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -subspaces in the rotor position estimation module. Compared with the non-compensation method, the proposed one is robust to parameter mismatches and only increases the computation burden slightly. Finally, experiments on a prototyped DT-IPM verify the proposed method.