Distributed Current-Regulated Vector Control of High-Performance Modular PM Synchronous Machine Drives

摘要

The integrated modular motor drive (IMMD) architecture is based on the concept of a physically integrated motor drive consisting of n identical phase-drive units. Each of these phase-drive units includes a segmented machine stator pole, its winding, and a single-phase inverter to excite the winding. This IMMD architecture opens intriguing opportunities for improved fault tolerance because each of the n phase-drive modules is equipped with its own controller. The objective of this research program has been to design and implement high-performance current regulation and torque control for the IMMD using a modular, distributed control architecture without requiring a dedicated master controller or high-speed synchronized communications. The distributed control architecture poses special challenges for maintaining coordination of the n individual phase controllers since the controllers no longer have the same natural symmetry as conventional motor drives to help limit the effects of asymmetries among the phase modules or machine phases. A combination of closed-form analysis and digital simulation has been used to identify and characterize the most promising distributed control algorithm. This analytical work has shown that it is possible to achieve high-performance current regulation in three-phase machines with floating-wye or delta winding connections using only two measured currents supplied to each phase-drive unit. A closed-loop feedback technique has been developed that uses the neutral point voltage to correct for system asymmetry and provide the required compliance to the over-constrained distributed control problem; this results in stable operation without sacrificing the performance of the complex vector current regulator. A laboratory demonstrator version of the phase-module controller has been used to implement and verify the proposed distributed control algorithm applied to an experimental 3-phase PM motor drive. The distributed control algorithm has been extended to continue controlling the machine torque after open-circuit faults. By adding proportional feedforward functions to the current command generation, the distributed controller can operate post-fault with no change in tuning or structure. The distributed controller has been shown to be compatible with well-known methods for adjusting the current commands to reduce the torque ripple in a faulted motor drive or to restore the original pre-fault average torque value.