Electrical machines with higher efficiency through combined star-delta windings

Abstract

Combined windings have higher fundamental winding factors and produce smaller harmonic contents. Therefore, the efficiency can be increased without any additional active mass. This paper presents specifics of the combined windings. Special topics are the higher efficiency in comparison to machines with the same size and classical windings, design and calculation of combined windings, winding technique and experimental results of a 30 kW standard asynchronous motor.

Extremely efficient but compact — A circumferentially cooled induction motor

“…In the authors' opinion, the greatest potential for loss reduction is offered by application of die-cast copper rotors [2] and improved winding design using combined star-delta windings [12]. As most industrial motors operate at partial loading, new technical developments, but also future standards for energy saving electric motors, should focus on loss reduction in a wider range between no-load operation and rated loading.…”

Comparative Study of Short Circuits and Demagnetization in Delta, Star, and Hybrid Winding Connections for Surface-Mounted Permanent Magnet Machines

“…Based on the above analytical models, the largest peak currents for different connections can be obtained. Taking (14) as an example, the star-side current of hybrid connection consists of the steady and transient components. Since the short-circuit peak current increases with angular speed, it is assumed that ω is large enough to get the largest value.…”

“…Nevertheless, experiments still show that 15% higher efficiency can be achieved at light load when the delta connection is changed into a star connection [12]. As for the hybrid connection, despite its increased complexity, it achieves higher winding factor, reduces winding losses, and minimizes torque pulsations [13][14][15][16]. Furthermore, it exhibits superior performance in open-circuit faults [16,17], thereby ensuring safety in practical applications [18].…”

Design and implementation of brushless doubly fed induction machine with new stator winding configuration

“…In Kumaresan and Subbiah (2003), squirrel cage induction generator with delta-star winding is proposed for wind turbine generator to enhance the generation of real power and reduce consumption of reactive power. Onur Misir and Ponick (2014), Misir et al (2016, 2017), Raziee et al (2017), and Kasten and Hofmann (2011) discuss the use of delta-star winding in standard induction motors for industrial purposes for improving efficiency by incrementing the fundamental winding factor. Lei et al (2011) present the impact of delta-star winding in the reduction of spatial harmonics and stray losses in electrical machines.…”