Sensitivity of Torque Control for Seven-phase BLDC Machine with One Opened Phase under Constraints on Voltage and Current

This paper deals with control strategies when a seven-phase axial-flux brushless DC machine operates in one open-circuited phase fault by considering constraints on voltage and current. The constraints are related to the converter and machine design in terms of peak values of non-sinusoidal voltage and current. In addition, the sensitivity of the torque control on parameters of new imposed current references is analyzed under the base speed and in the flux-weakening region. The current references taking into account only first and third harmonics in healthy phases are proposed to ensure the torque optimization while phase currents and voltages are within their limits. The usefulness of the control strategies and the parameter analysis are verified by numerical results.