In-System Calibration of Position Sensor Offset in PMSM Drives

Permanent magnet synchronous machines (PMSM) are widely utilized in applications demanding high torque output and torque density. Among them are hybrid electric powertrain and electric power steering (EPS) systems used in the transportation sector. Field oriented control (FOC), is one of the preferred methods of control for PMSMs due to the unique advantages. Accurate rotor position measurement is of paramount importance for proper field-oriented control of PMSMs. The relative angle offset between the position sensor zero and rotor zero is a key calibration for each PMSM drive system. However, calibration of the position sensor while the machine is in the system is a challenging problem. Certain powertrain architectures and EPSs with dual machines, facilitate the driving of one machine with the other. This paper proposes a unique approach to calibrate the position sensor offset of a PMSM system, while in-system, in machine-drive architectures that allow in-system rotation of the machine needing calibration with another actuator (i.e. internal combustion engine or second electric machine in dual wound machines). Analysis, simulation, and experimental results are provided that validates the proposed method.