Design Optimization of Coreless Axial-flux PM Machines with Litz Wire and PCB Stator Windings

A systematic review on current research and developments on coreless axial‐flux permanent‐magnet machines

“…Findings Application area [126] High compactness and lightness of the machine structure along with high efficiency and acceptable voltage regulation because of the lack of the iron core Ships, aircrafts or hybrid-electric vehicles [92] A possible solution for energy conversion from a charged battery to a wheel of an optimised vehicle Electric vehicles [115] Proposed an efficient topology of a disc-type multi-air gap machine for land transport and aeronautical applications…”

“…In Ref. [126], researchers presented a preliminary design of a permanent magnet axial-flux machine (PMAFM) with a coreless stator for the power management of a small-scale flywheel energy storage system (FESS). Parametric analysis was carried out to optimise the PMAFM electromagnetic design, mainly focussing on the reduction of the ohmic losses and the torque ripple.…”

Design and Analysis of Coreless Axial Flux Permanent Magnet Machine with Novel Composite Structure Coils

“…The analytical expression for estimating the eddy current loss has been summarized in a large number of the literature. It is assumed that the waveform of air gap flux density is completely sinusoidal, and the eddy current loss of the coil ends is neglected; the eddy current loss can be expressed as follows [14,20]:…”

“…The significant loss of the coreless AFPM machine is the DC copper loss and eddy current loss in windings, of which the former is generated when the stator current flows through the conductor, and the latter is generated because the coils are directly exposed to the air magnetic field [3,14], especially when operated at a high electric frequency. A number of works have been performed in recent years [15][16][17][18][19][20], that the trapezoidal coils or optimized trapezoidal coils are mostly used in the coreless stator [9,16], compared with the other special shapes such as the circular coils [10] and rhomboidal coils [15], to improve the winding factor The number of turns and width of the conductor can be synchronously optimized, and the structure of unequal width winding is proposed and applied in [16]. The coreless AFPM machine with a type of block coil using 3D printing technology is applied in the collaborative robot to achieve higher output power and efficiency [17].…”

“…In [18], with a limited outer diameter of the stator, the length of effective conductors is increased by the improved ends of windings, resulting in the space utilization of the coreless stator and the efficiency of the machine can be improved. In addition, some design optimization procedures are proposed to calculate and reduce the winding losses for ordinary copper wires [19], Litz wires, and PCB traces [20].…”