Low torque ripple tooth coil windings multi‐3‐phase machines: design considerations and validation

Abstract

In multi‐n‐phase machines, the n‐phases are grouped in separated stars. A particular subcategory of multi‐n‐phase machines is the multi‐3‐phase machines. This study presents the design considerations and their validation for tooth coil wound multi‐3‐phase machines. A generic algorithm to design multi‐3‐phase machines is proposed. Although this study mainly focuses on multi‐3‐phase machines the approach is generalised and is applicable to any multi‐n‐phase machine. The resulting machines exhibit a low torque ripple value, and a mathematical formulation is proposed in order to justify this behaviour. All the multi‐3‐phase machines designed according to the proposed algorithm can be studied, and directly compared, thanks to the generalised harmonic formulation of the stator MMF and the torque performances here proposed. This study is enriched with some design hints useful to realise a machine with low mutual coupling between phases, and some considerations that can help the machine designer in the choice of the number of poles. The design algorithm is applied for the design of a triple‐3‐phase PM‐inset machine solution, with nine slots ten poles. The performances, evaluated by finite element analysis and experimental analysis, demonstrate the effectiveness of the design algorithm proposed in a very simple structure machine.

Evaluation of Magnetomotive Force and Torque Ripples in Modular Type IPMSM With Multi Three-Phase Winding Configurations

“…The detailed guidelines about the selection of MT-SW configurations are presented, starting with the definition of the basic design parameters and rules for the selection of pole numbers, the winding configurations, and the electrical and magnetic axis principles for the modular type multi threephase unit motor machine. [16] discuss a similar type of algorithm but is implemented on multi-n-star type designed machines. However, the developed algorithm and the analysis presented in this section discuss the MT-SW machine design with two different types of multi three-phase sector winding configurations.…”

“…Publication [14] suggests different slots and poles combinations, while [15] uses different FSCW for harmonic compensation and torque ripple reduction in multiphase machines. Tooth coil windings having FSCW design is proposed in [16], presenting a new technique to model harmonic compensation and torque ripple in multi three-phase star-connected machines. Similarly, the FSCW machine with tooth coil windings is also known for its simple and compact structure.…”

Multi Three-Phase Hairpin Windings for High-Speed Electrical Machine: Possible Implementations

“… Lower spatial harmonic content, which results in lower rotor losses and reduced torque ripple [14], [15], [17].…”

“… Possibility of decreasing the converter power rating thanks to the splitting of the feeding current in more than three phases [15]- [17].…”

“… Lower turns per phase, which determines a lower leakage inductance thus leading to higher undesirable harmonic currents and additional Joule losses, in particular when VSIs with a standard PWM are employed [17].…”