Optimum Control of a Five-phase Integrated Modular Permanent Magnet Motor Under Normal and Open-Circuit Fault Conditions

This paper presents optimal control of a five-phase Integrated Modular Permanent Magnet Motor for normal and open-circuit fault conditions. Finite element analysis of the motor is carried out to obtain output torque of the motor. It is found that the output torque ripple of the machine when supplied with sinusoidal currents is considerably high. An optimum control technique is presented to operate the machine with minimum torque ripple and least stator ohmic loss. Furthermore, an optimum fault tolerant control method under open-circuit fault conditions is presented. Due to the half bridge and split capacitor configuration used for this modular motor drive the neutral voltage fluctuates considerably during the fault condition. To solve this problem, a constraint to make the summation of the phase currents to zero is incorporated in the derivation of the fault tolerant optimal control strategy. Optimal currents are calculated for normal and open-circuit fault-tolerant operation of the machine. Simulation results are presented for the verification of the control methods. Although the control techniques discussed in this work are applied for the five phase modular permanent magnet machine, they can be extended for multiphase permanent magnet machines with any number of phases.