A High-Frequency Signal Injection-Based Sensorless Control Method Robust to Single and Double Open-Phase Faults for a Dual Three-Phase Motor

Open-phase faults will lead to a large error in the estimated rotor position of the high-frequency signal injection (HFSI) based sensorless method in a dual three-phase motor (DTM) drive system, resulting in unstable performance. The previous research has proposed a senseless control method robust to the single open-phase fault (SOPF) to improve the reliability of the drive system. To further enhance the robustness of the sensorless control system of the DTM, the effect of the double open-phase fault (DOPF) on the HFSI is analyzed and unified with that of the SOPF. It is found that both SOPF and DOPF can cause the varying amplitude and negative sequence harmonics of the high-frequency currents in the alpha beta-subspace. To solve these problems, a transformation method is introduced to transform them into multiple harmonics. Then, an adaptive filter-based rotor position estimation method is proposed. Simulation and experimental results show that the proposed HFSI-based sensorless control method can accurately estimate the rotor position under health, SOPF, and DOPF conditions without any fault-diagnosis method.