Influence of Gear Ratio on the Performance of Fractional Slot Concentrated Winding Permanent Magnet Machines

Abstract

Fractional slot concentrated winding (FSCW) permanent magnet synchronous machines (PMSMs) have been a research hotspot over the past few decades. Recently, the magnetic gearing effect in FSCW PMSMs is revealed along with its gear ratio which is a function of slot/pole number combination. At the design stage of FSCW PMSMs, one of the key issues is the selection of the slot/pole number combination. This paper shows that the gear ratio can contribute to a proper slot/pole number selection in any multi-phase FSCW PMSMs by acting as a unified index for a quick overall performance comparison. In the paper, firstly, the magnetic gearing effect in FSCW PMSMs is explained and the gear ratio is further discussed. The advantages of adopting gear ratio as the overall performance index over other indices are revealed. The influence of the gear ratio on the winding factor, torque output, cogging torque, inductance and rotor losses of 3-and 6-phase FSCW PMSMs are analyzed and validated by experiments, thus proving the analyses. Index Terms-concentrated winding, fractional slot, gear ratio, inductance, losses, magnetic gearing effect, permanent magnet machines, winding factor. Yue Liu (S'16) received the B.Eng. and M.Sc. degrees in electrical and electronic engineering from Harbin Institute of Technology, Harbin, China, in 2013 and 2015, respectively. He is currently working toward the Ph.D. degree in the

On-line measurement method of transmission backlash based on angular velocity and double-end angular position information

“…The waveforms of the change of the driving gear angle position and the driven gear angle position are all triangular waves, and the change rules of the driving gear angle position and the driven gear angle position from increase to decrease or from decrease to increase are consistent. 21,22 According to the physical process described above, the driven gear is out of contact with the driving gear due to backlash after the driving gear moves in reverse direction. Due to the inertia, the driven gear still keeps its original direction for rotation until it contacts again and then rotates in reverse with the driving gear.…”

Contribution of winding space harmonics to average torque in fractional‐slot concentrated permanent magnet machines with equal/unequal teeth

“…Although all the harmonics in (8) and (9) share the same frequency as the fundamental PM airgap flux density, only those having the same pole pair number as the fundamental PM airgap flux density can have average torque production. When v = p , the first component in (8) and (9) will produce average torque, which is called the conventional torque T con , as given in [15, 16]. When v = p ± N s is satisfied, the second component in (8) and (9) can also produce average torque, which is the modulated torque T mod by the stator modulation effect, as shown in (10) and (11).…”

“…It is demonstrated in [14] that the FSCW PM machine also belongs to the PM vernier machine family due to the similar modulation effect. In [15], the contribution of modulation effect to the average torque in FSCW PM machines with different slot and pole number combinations is analysed, whilst the number of phase is also considered in [16].…”

“…The magnetic gear effect is found to be prevailing in the flux switching machines [6, 7], flux reversal machines [8], vernier machines [9–11], and even DC machines [12] and induction machines [13]. In addition, the magnetic gearing effect or modulation effect in FSCW PM machines has also been revealed in [14–16]. It is demonstrated in [14] that the FSCW PM machine also belongs to the PM vernier machine family due to the similar modulation effect.…”

Effect of time‐harmonic current on the harmonic leakage inductance of fractional slot concentrated winding permanent magnet synchronous motor

“…Compared with traditional distributed winding permanent magnet synchronous motors (PMSMs), fractional slot concentrated winding PMSMs (FSCW-PMSMs) have the advantages of the short end winding, high slot fill factor, low cogging torque and high fault tolerance, which are gaining popularity within the field of motion control in recent years [1][2][3][4].…”