Emerging Multiport Electrical Machines and Systems: Past Developments, Current Challenges, and Future Prospects

Abstract

Distinct from the conventional machines with only one electrical and one mechanical port, electrical machines featuring multiple electrical/mechanical ports (the so-called multi-port electrical machines) provide a compact, flexible, and highly-efficient manner to convert and/or transfer energies among different ports. This paper attempts to make a comprehensive overview of existing multi-port topologies, from fundamental characteristics to advanced modeling, analysis, and control, with particular emphasis on the extensively investigated brushless doubly-fed machines for highly-reliable wind turbines and power split devices for hybrid electric vehicles. A qualitative review approach is mainly adopted but strong efforts are also made to quantitatively highlight the electromagnetic and control performance. Research challenges are identified and future trends are discussed.

Controller Strategy for Open-Winding Brushless Doubly Fed Wind Power Generator With Common Mode Voltage Elimination

“…Advantages of the multiphase machines over the traditional three-phase machines, such as capabilities in starting and continue running even with one or more of stator phases open-circuited or short-circuited, reduction in the torque pulsation and rotor copper loss hence result in improving overall performance and increasing power rating without enhancing every phase voltage, which make they be suitable for naval vessel propulsion systems and so on. However, the multi-phase machines still face many important technical challenges which need to be overcome as comprehensively addressed in [26]. In this paper, the proposed open-winding BDFRG fed with dual two-level converters can also improve the reliability, redundance, reduce the rating in single converter but can increase the output level, which makes OW-BDFRG easier to implement in VSCF and MPPT by only adjusting the f c amplitude and its phase sequence along with different rotor speed (sub-synchronous, synchronous or supersynchronous mode).…”

Recent developments and comparative study of magnetically geared machines

“…Unlike the conventional electrical machines with one electrical port and one mechanical port, most MGd machines can have more than one mechanical port, providing additional degrees of freedom [13][14][15]. The multi-port characteristic of MGd machines makes them possible to achieve specific functions, such as continuously variable transmission (CVT) and power split, which are inherently suitable for HEVs and wind power generations, Fig.…”

Novel Dual-Stator Machines With Biased Permanent Magnet Excitation

“…Therefore, many researchers attempted to find utility methods for torque density enhancement for PM machines. As a common practice, doubling the stator [4] [5] or rotor [6]- [20], namely, dual-mechanical-port machine [4], is normally employed to increase the torque density within limited overall dimension. The dual rotor (DR) machines usually require sophisticated efforts for handling two rotating parts, which leads to relatively low mechanical reliability.…”

“…The dual rotor (DR) machines usually require sophisticated efforts for handling two rotating parts, which leads to relatively low mechanical reliability. The dual stator (DS) machine was relatively structurally simpler by using an additional stator as a torque booster, and better control flexibility can be achieved [4].…”