Transient Simulation of a 240/120V Step Down Three-Phase to Five-Phase Transformer for Multiphase Drive Applications

Abstract

The increasing adoption of five-phase electrical machines in high-reliability and high-performance applications calls for efficient phase conversion from conventional three-phase utilities. Existing solutions predominantly rely on power electronic converters, which sadly introduce switching losses, electromagnetic interference, and increased system complexity. This paper builds on existing approach for developing a passive three-phase to five-phase transformer system with additional step-down functionality and electromagnetic validation. A generalized transformation matrix is derived to synthesize balanced five-phase voltages with 72° phase displacement from a 120° three-phase source. Winding turn relationships are formulated to integrate step-down voltage functionality without compromising phase symmetry. Magnetic circuit analysis by finite element analysis methods are used to evaluate flux distribution. Results demonstrate that balanced five-phase output stepped down from 240V to 120V can be achieved. The core loss obtained for the system is 2.87% with a symmetric flux distribution around the central limb and a flux density in the linear region of the B-H curve. The output voltage has a THD of 7.66%. These findings validate the proposed passive transformer system as a viable alternative for fixed-frequency multiphase applications requiring high reliability and galvanic isolation.