Design and optimisation of outer-rotor hybrid excitation flux switching motor

Permanent Magnet Flux Switching Motor (PMFSM) with outer-rotor configuration recently reported in the literature can potentially lead to a very compact in-wheel electric vehicle (EV) drive design and increased cabin space through the elimination of mechanical transmission gears. Nevertheless, the output torque is still insufficient to drive heavier EV especially at starting and climbing conditions. On the other hand, with the permanent magnets placed along the radial V-shaped segmented stator, the PMFSM is prone to excitation flux leakage and demagnetization, making optimisation of the rotor and stator dimensions a difficult objective to achieve, while keeping the PM volume constant. In this thesis, design and optimisation of high torque capability salient stator outer-rotor hybrid excitation flux switching motor (OR-HEFSMs) are investigated. With the additional DC field excitation coil (FEC) as a secondary flux source, the proposed motor offers advantage of flux control capability that is suitable for various operating conditions. The design restrictions and specifications of the proposed motor are kept similar as interior permanent magnet synchronous motor (IPMSM) employed in the existing hybrid electric vehicle (HEV) Toyota Lexus RX400h. The JMAG-Designer ver.14.1 was used as 2D-finite elements analysis (FEA) solver to verify the motor’s operating principle and output torque performance characteristics. The subsequent optimisation work carried out using deterministic optimisation approach (DOA) has produced a very promising 12S-14P OR-HEFSM configuration, where a maximum torque density of 12.4 Nm/kg and power density of 5.97 kW/kg have been obtained. These values are respectively 30% and 68% more than that produced by IPMSM of comparable dimensions. A reduced-scale prototype 12S-14P OR-HEFSM has also been fabricated to minimize the manufacturing cost and no-load laboratory measurements have been carried out to validate the simulation results. The results obtained show that they are in good agreement and has potential to be applied for in-wheel drive EV

Design of FPGA- Based SPWM Single Phase Full-Bridge Inverter

Nowadays power inverters serve as an important emergency power supply system in events of main power supply failure. The AC output voltage of a power electronic inverter is usually non-sinusoidal and hence has a high harmonic content. Sinusoidal Pulse Width Modulation (SPWM) scheme is normally used to convert the DC power supply into AC power supply by comparing the reference voltage waveform with the triangular waveform known as carrier. SPWM provides a way to reduce the total harmonic distortion of load current. The objective of this paper is to demonstrate a SPWM switching scheme by using Altera DE2-70 board. In this SPWM technique, a sinusoidal reference voltage waveform is compared with the triangular carrier voltage to generate the on and off switching states. This switching scheme will trigger the gate of the power switch. In this paper, the SPWM switching strategies implemented using Altera DE2-70 (Cyclone II EP2C35F672C6) with 16 bit serial configuration devices. The switching between reference and carrier waveforms of SPWM is obtained by using Matlab software. Simulation on the design waveform is conducted using Quartus II software tools provided by Altera. The output frequency of SPWM is 50 Hz and the design is limited to two values of modulation indices which are 0.5 and 0.75

A High Torque Segmented Outer Rotor Permanent Magnet Flux Switching Motor for Motorcycle Propulsion

Electric scooters also known as electric motorcycle are viable and personal means of road transportation have been making their ways into the world markets now because in them, combustion engine with the use of fuel oil for propulsion have been completely eliminated for economic and environmental imperatives. Electric motor which converts electrical energy into mechanical energy is used to overcome the complication of combustion engine. As it is, everyone is opting for combustion engine free and fuel-less type of vehicle. For this reason, manufacturers have exhibited interest, making research on electric motor very attractive. Meanwhile, surface permanent magnet synchronous motor (SPMSM) has been successfully developed having output torque of 110 Nm, the assembly of motor lacked mechanical strength between the rotor yoke and the mounted permanent magnet (PM) which heats up during speed operation, resulting to poor performance. To overcome the challenges laced with SPMSM, this paper presents a novel design of 24 stator 14 pole outer rotor-permanent magnet flux switching motor (SOR-PMFSM) capable of high torque and high performance. It employs an unconventional segmented rotor which has short flux path flow. It also embraces alternate stator tooth windings to reduce material cost. Design specifications and restriction with input DC current are the same with SPMSM. The 2D-FEA by JMAG, version 14 is used to examine the performance of the proposed motor in terms of cogging torque, back-emf, average torque, power and efficiency. Preliminary results showed that torque, power output and efficiency of the proposed motor are 1.9Nm times, 5.8kW times more than SPMSM and efficiency of 84% thus, can sustain acceleration for long distance travel

A High Torque Segmented Outer Rotor Permanent Magnet Flux Switching Motor for Motorcycle Propulsion

Electric scooters also known as electric motorcycle are viable and personal means of road transportation have been making their ways into the world markets now because in them, combustion engine with the use of fuel oil for propulsion have been completely eliminated for economic and environmental imperatives. Electric motor which converts electrical energy into mechanical energy is used to overcome the complication of combustion engine. As it is, everyone is opting for combustion engine free and fuel-less type of vehicle. For this reason, manufacturers have exhibited interest, making research on electric motor very attractive. Meanwhile, surface permanent magnet synchronous motor (SPMSM) has been successfully developed having output torque of 110 Nm, the assembly of motor lacked mechanical strength between the rotor yoke and the mounted permanent magnet (PM) which heats up during speed operation, resulting to poor performance. To overcome the challenges laced with SPMSM, this paper presents a novel design of 24 stator 14 pole outer rotor-permanent magnet flux switching motor (SOR-PMFSM) capable of high torque and high performance. It employs an unconventional segmented rotor which has short flux path flow. It also embraces alternate stator tooth windings to reduce material cost. Design specifications and restriction with input DC current are the same with SPMSM. The 2D-FEA by JMAG, version 14 is used to examine the performance of the proposed motor in terms of cogging torque, back-emf, average torque, power and efficiency. Preliminary results showed that torque, power output and efficiency of the proposed motor are 1.9Nm times, 5.8kW times more than SPMSM and efficiency of 84% thus, can sustain acceleration for long distance travel

An Analysis of Iron Flux Bridges Topologies for 12Slot-14Pole HE-FSM

In this paper, a novel Hybrid Excitation Flux Switching Machine (HE-FSM) with DC-field excitation coil (DC-FEC) wounded in radial direction is proposed. The design is able to generate high torque and power performance because of a few points of interest such as robust rotor structure, non-overlapping windings and reduction of flux cancellation in stator yoke. However, the design with FEC in radial direction required no space between upper FEC and outer stator of machine which is lead to flux loss to surrounding area and flux saturation in stator yoke. As a solution, iron flux bridges have been introduced on the stator core to produce high torque execution. By using JMAG Designer ver. 14, numerous configuration of iron flux bridges have been presented and overviewed. Then, performances of torque at numerous flux bridges is analysed and compared. A design with highest torque is chosen to investigate the other performances of the machine

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 desig

Design and performance analysis of 12Slot-14Pole HEFSM with outer-rotor configuration

This paper presents the performance analysis of 12Slot-14Pole hybrid excitation flux switching machine (HEFSM) with outer-rotor configuration. Nowadays, research on flux switching machines (FSMs) become an attractive research topic due to several excessive advantages of robust rotor structure, high torque and power capability, and low manufacturing cost that suitable for heavy applications. The FSMs that constructed with two flux sources namely permanent magnet (PM) and flux excitation coil (FEC) which also known as hybrid excitation flux has additional advantage of flux controllable. Furthermore, the outer-rotor configuration of the machines can provides higher torque density and appropriate for in-wheel direct drive application. Based on 2-D finite element analysis (FEA), the design improvement has been made on the initial design machine shows that there is great enhancement on torque and power

An Analysis of Iron Flux Bridges Topologies for 12Slot-14Pole HE-FSM

In this paper, a novel Hybrid Excitation Flux Switching Machine (HE-FSM) with DC-field excitation coil (DC-FEC) wounded in radial direction is proposed. The design is able to generate high torque and power performance because of a few points of interest such as robust rotor structure, non-overlapping windings and reduction of flux cancellation in stator yoke. However, the design with FEC in radial direction required no space between upper FEC and outer stator of machine which is lead to flux loss to surrounding area and flux saturation in stator yoke. As a solution, iron flux bridges have been introduced on the stator core to produce high torque execution. By using JMAG Designer ver. 14, numerous configuration of iron flux bridges have been presented and overviewed. Then, performances of torque at numerous flux bridges is analysed and compared. A design with highest torque is chosen to investigate the other performances of the machine

Back Electromotive Force Analysis of Outer-Rotor Hybrid Excitation Flux Switching Motor

Outer-rotor machine installed for in-wheel drive electric vehicles becomes trending nowadays. Previously, outerrotor hybrid excitation flux switching motor (OR-HEFSM) in wheel drive has been proposed to eliminate the transmission gear conventionally used in single drive electric vehicles. However, the back EMF of existing OR-HEFSM is not purely sinusoidal waveform due to harmonic content and high level of cogging torque. This kind of problem might be lead to create noise and tremor in the motor. In this paper, rotor pole skewing technique is adopted to improve back EMF waveform, harmonic content and cogging torque. The analyses carried out based on 2D FEA and 3D FEA using JMAG Designer Version 14.0. Besides, the flux linkage, flux distribution and output performances are also investigated. The results obtained show that the skewing method has improved the back-EMF waveform and reduce the cogging torque. The 3D FEA result indicates the peak to peak value of cogging torque has reduced by 91.42% with skewed rotor method. The torque and power performance of 3D-FEA has maximum values of 248.33Nm with 44.42% and 162.79kW with 33.42%, respectively in which higher when compared with 2D-FEA and skewing

High Torque Flux Switching Permanent Magnet Machine in Segmented Outer Rotor using Appropriate Split Ratio for Electric Scooter Propulsion

Recently, permanent magnet synchronous machine (PMSM) having the diameter of 11inches was successfully developed and installed in electric scooter vehicle (ESV) for propulsion. It consists of segmented stators of 24 armature slots and 100 pieces of permanent magnet of 2 kg weight mounted on rotating rotor. Upon the huge amount of materials and permanent magnet used, PMSM produced 110Nm only. Looking at the size, this torque is low and could not sustain acceleration for long distance travels. To overcome the challenge of low torque, this paper presents a new machine type, flux switching motor (FSM) with 1 kg weight of permanent magnet flux source employing segmented outer rotor.  Six ranges of split ratio of 0.80-0.85 for outer rotor 24slot-14pole FSPM motor configurations were designed and compared. The 2D-FEA by JMAG software version 14 is used to examine its performance in term of flux linkage, cogging torque, back-emf and average torque which the structure with split ratio of 0.85 took lead by securing highest torque profile of 209Nm. It also achieved low cogging torque to operate in safe region. In conclusion, appropriate split ratio significantly enhances high torque capability of permanent magnet flux switching motor for electric scooter propulsion