M. Z. Ahmad

Design improvement and performance analysis of 12Slot-10Pole permanent magnet flux switching machine with field excitation coils

Permanent magnet flux switching machine (PMFSM) with additional field excitation coil (FEC) has several attractive features compared to conventional permanent magnet (PM) machines because of its variable flux control capability and robust rotor structure suitable to apply for high speed applications. However, the original machine has a limitation of operating in high current condition due to nonessential magnetic saturation that prevents the machine from extracting the maximum performances. To overcome this problem, some design refinements are conducted by using deterministic optimization method to gain a better performance in the maximum torque and power production. The results simulated by finite element analysis (FEA) show that the machine with the improved design increases by 11.6% of the maximum torque and 16.3% of the maximum power compared to the original design.

Performance comparison of 24S-10P and 24S-14P field excitation flux switching machine with single DC-Coil polarity

Flux switching machines (FSMs) that consist of all flux sources in the stator have been developed in recent years due to their advantages of single piece and robust rotor structure suitable for various speed applications. They can be categorized into three groups that are permanent magnet (PM) FSM, field excitation (FE) FSM, and hybrid excitation (HE) FSM. Both PMFSM and FEFSM has only PM and field excitation coil (FEC), respectively as their main flux sources, while HEFSM combines both PM and FECs. Among these FSMs, the FEFSM offers advantages of low cost, simple construction and variable flux control capabilities suitable for various performances. In this paper, design study and flux interaction analysis of a new 12S10P and 12S-14P FEFSM with single direction of DC FEC winding are presented. Initially, design procedures of the FEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Then, coil arrangement tests are examined to confirm the machine operating principle and position of each armature coil phase. Finally, flux interaction between DC FEC and armature coil, FEC flux capabilities at various current condition, induced voltage and initial torque are also analyzed.

Design studies on high torque and high power density hybrid excitation flux switching synchronous motor for HEV applications

This paper presents design study of high torque and high power density hybrid excitation flux switching synchronous motor (HEFSSM) as a candidate for traction drives in hybrid electric vehicle (HEV). Firstly, the construction, the basic working principle and the design concept of the proposed HEFSSM are overviewed. Then, under some design restrictions and specifications for the target HEV applications, the initial drive performances of the proposed HEFSSM are evaluated based on 2D-FEA. As the initial motor fails to achieve the target performances, design parameters are set and treated by using deterministic design optimization approach. After several cycles of optimization, the proposed motor makes possible to obtain the target performances of 333Nm torque and 123kW power similar to that used in existing interior permanent magnet synchronous motor (IPMSM) for LEXUS RX400h.

Design improvement of a new outer-rotor hybrid excitation flux switching motor for in-wheel drive EV

Research and developments of in-wheel motors applied in pure electric vehicles (EVs) propulsion systems have attracted great attention recently. This is due to their definite advantages of great controllability for each independent wheel as well as the availability of more cabin space due to removal of conventional mechanical transmission and differential gears. Moreover, more series batteries can be installed to increase the driving distance. Since the motors are attached directly to the wheel, the major requirements are to have high torque density and efficiency. As one of alternative candidates with high torque possibility, a new design of outer-rotor hybrid excitation flux switching motor for in-wheel drive EV is proposed in this paper. The proposed motor consists of 12 slots of stator poles, and 10 rotor poles, with all active parts are located on the stator. In addition, it has a robust rotor structure which only comprises a single piece of rotor and has a wide range flux control capabilities. Under some design restrictions and specifications for the target EV drive applications, the performance of the proposed machine on the initial design and improved design are analyzed based on 2-D finite element analysis (FEA). The performance of the improved design motor shows that the maximum torque achieved is 81.5% of the target performance, whereas the maximum power has achieved 143.6 kW which is greater than the target value. Thus, by further design refinement and optimization it is expected that the motor will successfully achieve the target performances.

Investigation of field excitation switched flux motor with segmental rotor

In this paper a three-phase field excitation switched flux (FESF) motor where both armature coil and field excitation (FE) coil placed on the stator is investigated. The rotor is design with separately segmental pole so that flux generated from FE Coil can be fundamentally placed in adjacent with flux of armature coil. Thus, the coil end length of both FE Coil and armature coil are reduced, hence increasing the motor efficiency when compared with FESF motor with single piece rotor, and overlapped FE Coil and armature coil windings. In this paper design investigation and analysis of 12S-8P and 24S-10P FESF motor with segmental rotor are investigated. Moreover, coil test analysis, FE Coil flux characteristics, flux interaction between FE Coil and armature coil, flux distribution, and torque characteristics are also compared. As conclusion, the 24S-10P FESF motor with segmental rotor gives much higher performance when compared with 12S-8P FESF motor.

Optimization of outer-rotor hybrid excitation FSM for in-wheel direct drive electric vehicle

Research on flux switching machines (FSMs) has been an attractive topic recently due to tremendous advantages of robust rotor structure, high torque, and high power capability that suits for intense applications. However, most of the investigations are focusing on inner rotor structure which incongruous for direct drive applications. In this paper, the design optimization and performance analysis of 12Slot-14Pole hybrid excitation flux switching machine (HEFSM) with outer-rotor configuration are conducted for in-wheel direct drive electric vehicle (EV). Similar with conventional inner-rotor HEFSMs, two magnetic flux sources of permanent magnet (PM) and field excitation coil (FEC) have extra advantage of variable flux control capability, while the outer-rotor configuration has ability to provide much higher torque and power density suitable for in-wheel EV drives. Based on some design restriction and specification, design refinements are conducted on the initial design machine by using deterministic optimization approach. The final design machine has achieved maximum torque and power density of 335.08Nm and 5.93kW/kg, respectively, slightly better than inner rotor HEFSM and interior permanent magnet synchronous machine (IPMSM) design for EV.

Coil test analysis of Wound-field three-phase flux switching machine with non-overlapping winding and salient rotor

Topologies for three-phase salient rotor flux-switching machines having DC field winding are presented and coil test analysis, peak armature flux linkage, cogging torque, induced emf and average torque are examined. Salient rotor is used to modulate and switch the polarity of the flux linkage in the armature winding and this is the basic principle of operation of these types of machines. Non-overlapping winding and toothed-rotor are the clear advantages of these topologies as the copper losses gets reduce and rotor becomes more robust. Finite Element Analysis (FEA) is used to examine the three phase topology of proposed Wound-field flux switching motor with non-overlapping winding and salient rotor.

Design Refinement and Performance Analysis of 12Slot-8Pole Wound Field Salient Rotor Switched-Flux Machine for Hybrid Electric Vehicles

Design parameter sensitivity study and performance analysis of 12Slot-8Pole wound field salient rotor (WFSalR) switched-flux machine (SFM) for hybrid electric vehicle (HEV) applications is presented in this paper. The proposed WFSalR SFM consists of 6 armature slots, 6 field excitation coil (FEC) slots and 8 rotor poles. The main advantage of these SFMs when compared with induction machines, synchronous machines, direct current (DC) machines etc is that all the active parts such that armature coil and FEC coil are located on the stator while the rotor part consists of only single piece iron. This makes the machine more robust, simple structure and more suitable to be used for high speed HEV applications. Non-overlap armature and field windings at the stator reduces the copper consumption and also the copper losses. First of all, the initial performance, the main structure and analysis based on two-dimensional Finite Element Analysis under certain limitations and specifications are discussed. Since the initial design fail to attain the maximum torque and power, therefore the performance of machine is enhanced by refinement of several design parameters defined in rotor, FEC and armature slot area. After design refinement, WFSalR FSM has achieved the maximum torque of 22.34 Nm and power of 5.27 kW at maximum field current density, Je of 30 A/mm2 and armature current density, Ja of 30Arms/mm2 which is approximately 3 times the torque and 2 times the power of initial design.

Design study and analysis of hybrid excitation flux switching motor with DC excitation in radial direction

Research and development of hybrid excitation flux switching motors (HEFSMs) that combined both permanent magnet (PM) and DC field excitation coil (FEC) as their main flux sources have been an attractive investigation recently due to their overwhelming performances as well as flux control capabilities. Among different types of HEFSMs, the motor with both PM and FEC located on the stator has the advantage of robust rotor structure due to their high mechanical stress suitable for high-speed applications. In this research, design and performance of a three-phase 12-slot 10-pole HEFSM in which the DC FEC in radial direction on the stator are investigated. Initially, coil arrangement test is analyzed to all armature coil slots to confirm the polarity of the phase. Then, flux interaction analysis is performed to investigate the flux capabilities at various current densities. Finally, torque and power performances are investigated at various armature and FEC current densities. The results show that the proposed motor has proportional increment of torque and power with respect with the current density suitable for various applications.

Analysis of High Torque and Power Densities Outer-Rotor PMFSM with DC Excitation Coil for In-Wheel Direct Drive

In recent years, flux switching machines (FSMs) have been an attractive research topic owing to their tremendous advantages of robust rotor structure, high torque, and high power capability suitable for intensive applications. However, most of the investigations are focusing on the inner-rotor structure, which is incongruous for direct drive applications. In this study, high torque and power densities of a new 12S-14P outer-rotor permanent magnet (PM) FSM with a DC excitation coil was investigated based on two-dimensional finite element analysis for in-wheel direct drive electric vehicle (EV). Based on some design restrictions and specifications, design refinements were conducted on the original design machine by using the deterministic optimization approach. With only 1.0 kg PM, the final design machine achieved the maximum torque and power densities of 12.4 Nm/kg and 5.93 kW/kg, respectively, slightly better than the inner-rotor HEFSM and interior PM synchronous machine design for EV.