Erwan Sulaiman

High Power Density Design of 6-Slot–8-Pole Hybrid Excitation Flux Switching Machine for Hybrid Electric Vehicles

Over the last decade, many automotive companies have been commercializing hybrid electric vehicles (HEVs) as one of candidates for sustainable human life. Some of the recent HEVs employ electric propulsion systems using a combination of reduction gear and interior permanent magnet synchronous motors (IPMSM) operated by relatively high-speed more than 12 000 r/min, resulting in achieving high torque and power densities simultaneously. In the combination, since all rare-earth permanent magnets are embedded in its rotor core, a machine design of high-speed IPMSM tends to be difficult. This is due to a design confliction between keeping enough mechanical strength of the rotor core and bringing out better electromagnetic performances. To cope with this problem, this paper deals with a 6-slot-8-pole hybrid excitation flux switching machine, in which both permanent magnets and wound field excitation are employed as magnetomotive force sources. This machine has all active parts on the stator body and a rugged rotor structure similar to that of switched reluctance motor suitable for high-speed operation. Some design parameter refinements are conducted to the machine in order to elevate maximum torque capability and maximum power density as much as possible under given design requirements and constraints. As a result, it is demonstrated that the machine designed becomes a good candidate for the target HEV drive application.

Design optimization of 12Slot-10Pole hybrid excitation flux switching synchronous machine with 0.4kg permanent magnet for hybrid electric vehicles

Hybrid excitation flux switching synchronous machine (HEFSSM) has several attractive features compared to interior permanent magnet synchronous machines (IPMSM) conventionally employed in hybrid electric vehicles (HEV). Among various types of HEFSSM, the machine with both permanent magnet (PM) and field excitation coil (FEC) on the stator has the advantages of robust rotor structure together with variable flux control capabilities that make this machine becoming more attractive to apply for high-speed motor drive systems. This paper presents an investigation into the design possibility and parameter optimization study of 12Slot-10Pole HEFSSM for traction drives in HEV. The research target is to design a machine with reduced amount of rare-earth magnet, a maximum torque of 210Nm, a maximum power of more than 123kW, and a maximum power density of more than 3.5kW/kg. Extensions in speed and torque ranges are chosen for optimization aims. The deterministic design approach is used to treat ten design parameters in an effort to achieve the target performances. As a result, the designed HEFSSM with 0.4kg PM is able to get much higher power density compared to existing IPMSM installed on a commercial SUV-HEV.

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.

A novel hybrid excitation flux switching synchronous machine for a high-speed hybrid electric vehicle applications

Hybrid excitation machines (HEMs) that consist of permanent magnet (PM) and field excitation coil (FEC) as their main flux sources has several attractive features compared to interior permanent magnet synchronous machines (IPMSM) conventionally employed in hybrid electric vehicles (HEVs). Among various types of HEM, the machine with both permanent magnet and field excitation coil located on the stator has the advantage of robust rotor structure similar as switch reluctance machine (SRM). In addition, the variable flux control capabilities from field excitation coil make this machine becoming more attractive to be applied for high-speed motor drive systems, coupled with reduction gear. This HEM can be categorized as hybrid excitation flux switching synchronous machine (HEFSSM). In this paper, a novel 12Slot-10Pole HEFSSM where the field excitation coil is wounded in radial direction in the stator is proposed for traction drives in HEVs. The design target of the proposed machine is a maximum torque of 210Nm with reduction gear ratio of 4:1, a maximum power of 123kW, a maximum power density more than 3.5kW/kg, and a maximum speed of 20,000r/min with similar restrictions and specifications in IPMSM used for LEXUS RX400h. The deterministic design optimization method based on 2D-FEA is used to treat design parameters defined in rotor, armature coil slot and field excitation coil slot until the target performances are achieved, under maximum current density condition for both armature coil and field excitation coil. The final results show that the final design HEFSSM is able to keep the same torque density in existing IPMSM installed on a commercial SUV-HEV.

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 and performance of 6-slot 5-pole PMFSM with hybrid excitation for hybrid electric vehicle applications

An interest in electric vehicles (EVs) and hybrid electric vehicles (HEVs) from automakers, governments and customers due to concerns on our environment makes it as more attractive research. Since electric motors are the core of both EVs and HEVs, it is a pressing need for researchers to develop advanced electric motors. As one of the candidates, permanent magnet flux switching machine (PMFSM) with additional coil excitation has several attractive features compared to conventional interior permanent magnet synchronous machines (IPMSM) used in HEV. This is because of its variable flux control capability and robust rotor structure that makes it possible to apply for high speed motor drive system with reduction gear. This paper presents an investigation into design possibility of 6-slot 5-pole PMFSM with hybrid excitation for traction drives in HEVs. An improved design is examined in effort to gain a better performance in its maximum torque and power production. As the design results, the designed motor enables to keep the same power density in existing IPMSM installed on a commercial SUV-HEV.

FEA-based design and parameter optimization study of 6-slot 5-pole PMFSM with field excitation for Hybrid Electric Vehicle

Permanent magnet flux switching machine (PMFSM) with additional coil excitation has several attractive features compared to interior permanent magnet synchronous machines (IPMSM) conventionally employed in HEVs. The variable flux control capability and robust rotor structure make this machine becoming more attractive to apply for high speed motor drive system coupled with reduction gear. This paper presents an investigation into design possibility and parameter optimization study of 6-slot 5-pole PMFSM with hybrid excitation for traction drives in HEVs. The design target is the motor with maximum power more than 123kW and maximum power density more than 3.5kW/kg. A reduction of permanent magnet material for a given torque requirement and an extension in speed and torque ranges are chosen as the optimization indices. The designed motor enables to keep the same power density in existing IPMSM installed on a commercial SUV-HEV.

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.