Zarafi Ahmad

2D-FEA Based Design Study of Salient Rotor Three-Phase Permanent Magnet Flux Switching Machine with Concentrated Winding

This paper presents a new structure of permanent magnet flux switching machine (PMFSM) with multiple different sizes of rotor pole width. A robust single piece salient rotor is used to modulate and switch the flux linkage polarity in the armature winding and become the fundamental mechanism of these types of machines. The methodology of two-dimensional (2-D) finite element analysis (FEA) is used to evaluate the electromagnetic performance of coil test including flux line distributions, three phase flux linkage, cogging torque as well as induced emf. The resulting performances are analysed based on the variety of rotor pole width to meet the requirement of direct drive propulsion of Electric Vehicles (EVs).

FEA-Based Design Study of 12-Slot 14-Pole Outer-Rotor Dual Excitation Flux Switching Machine for Direct Drive Electric Vehicle Applications

This paper presents an investigation into feasibilities design of 12-Slot 14-Pole outer-rotor dual excitation flux switching machine (ORDEFSM) for direct drive electric vehicle (EV) applications. The stator of the proposed machine consists of iron core made of electromagnetic steels, armature coils, permanent magnet (PM) and field excitation coils (FECs). The FECs in this proposed machine is used as a secondary field mmf source to support the main flux source from PM. Therefore, the proposed machine has extra advantage of variable flux control capability as compared with the conventional flux switching machines (FSMs). The rotor is composed of only stack of iron and hence, it is robust and suitable for high speed operation. The design target for the maximum torque and power density, and the maximum speed are more than 333 Nm, 3.5 kW/kg, and 20,000 r/min, respectively. The results obtained from two-dimensional (2-D) FEA study show that the initial design of the proposed machine has achieved the maximum torque, power density and maximum speed of 244.76 Nm, 3.47 kW/kg, and 20,000 r/min, respectively. Thus, it is expected that the proposed machine potentially to achieve the target performances by implementing optimization process using deterministic optimization method.

A Simple Overmodulation Strategy in Direct Torque Control of Induction Machines

A fast dynamic torque and high speed operations are so important especially in electric vehicle applications. In principle, there are two approaches to obtain these conditions. One is the use of mechanical gears and the other one is the use of overmodulation strategy. Through overmodulation strategy, the inverter voltage can be increased beyond its linear modulation range, thus full utilization of DC-linked voltage is achieved. This paper presents a simple overmodulation strategy that is well- suited in a constant frequency torque controller-based of direct Torque control (DTC) of induction motor drives. The simple overmodulation strategy is constructed based on torque and flux errors and flux position which are readily available; as required in conventional DTC scheme. The simulation results showed that the drive system is capable of operating in overmodulation and field weakening regions without resolving to the common approach of space vector modulation (SVM) based approach.

H ∞ speed control for Permanent Magnet Synchronous Motor

This paper describes the H∞ control design for robust speed control for the Permanent Magnet Synchronous Motor. The speed feedback control is used to maintain the speed during load changing. Due to the load changing it will create the disturbance to the motor. To solve this problem the H∞ control theory has been used to determine the robustness of the controller and to have good tracking performance for the speed. The model and the controller value have been developed in MATLAB/Simulink where the results show the controller able to maintain the speed despite the load is changed.

Topologies of single-phase outer-rotor hybrid excitation flux switching motor for in wheel drive applications

Most of commercial Hybrid Electric Vehicle (HEV)used single motor and transmission gears coupled to the wheels. This system leads to the transmission losses and reduce the efficiency and reliability of the motor. Therefore, in-wheel direct drive mechanism is introduced to overcome this problem. In-wheel direct drive eliminates the mechanical transmission, differential gears and drive belts. Thus, in-wheel direct drive provides quick torque response, higher efficiency, weight reduction, and increased vehicle space. As one of alternative, a new design of hybrid excitation flux switching motor (ORHEFSM) for in-wheel drive EV is proposed. First coil arrangement tests are analyzed to confirm the phase of each armature coil phase. Then, flux comparison of PM with DC FEC, flux linkage at various FEC current densities, cogging torque, induced voltage/back EMF of PM with DC FEC, torque and power versus FEC current density at various armature coil current densities are also analyzed. The generated results show that the appropriate combination of stator slot-rotor pole configurations are 8S-4P and 8S-8P respectively, which initially provide highest torque performance and power density. By further design modification and optimization it is expected that the low cost motor will successfully achieved the target performances.

The DC converter control for deceleration profile in energy recovery from landing aircraft

This paper discuss about the H∞control strategy for DC converter in the energy recovery from landing aircraft. The energy from landing aircraft can be changed to electrical energy by using several power electronics converters combine with the linear generator. To have this effect the controllers must able to control the mechanical and electrical outputs. The mechanical outputs are such as the force, speed of the linear generator while the electrical outputs are the voltage and current. By using the H∞ control strategy at the specific location especially at the converter side it hopes that all the outputs stated above can be controlled. The goals for this paper are to maintain the dc voltage value at the converter and to have constant deceleration speed and force at the linear generator in order to change the kinetic energy from landing aircraft to electrical energy. All the models and the simulations have been done in MATLAB software package.

Comparison study in various controllers in single-phase inverters

This paper explains the comparison of the controllers that suitable to be used in single phase inverter for studying purposes. This controller can easily been developed and tested using MATLAB/Simulink and implemented on the real time application. The controllers that have been developed are the Proportional Integration (PI)-dq controller, Proportional Resonant (PR) controller, and PR- Repetitive controller. The controller output will be connected to the pulse width modulation (PWM) generator to generate signal to the single phase inverters. All these controllers have been tested with the same load and simulation time.

Review of Switched Flux Wound-Field Machines Technology

ABSTRACT This paper explains the state of art of switched flux wound-field machines (SFWFMs). The main advantage of these SFWFMs when compared with induction machines, synchronous machines, direct current machines, etc. is that all the active parts such that armature coil and field excitation coil are located on the stator while the rotor part consists of only iron material without windings. This makes the machine more robust, simple structure, and more suitable to be used for high-speed applications, compared to induction machine which has low mechanical strength, less torque desnity, and low power factor. Theories, numerical and technical literature of different SFWFM are described and analysed. Merits and demerits of different SFWFM structure are discussed. This paper categorized SFWFM topologies on the basis of their structure, flux linkage, cogging torque, average torque, and efficiency.

Design optimization of single-phase outer-rotor hybrid excitation flux switching motor for electric vehicles

Nowadays, in-wheel motors applied in pure electric vehicles (EVs) propulsion systems have attracted great attention in advance research and development. In-wheel direct drive eliminates the mechanical transmission, differential gears and drive belts. Thus, in-wheel direct drive provides quick torque response, higher efficiency, weight reduction, and increased vehicle space. As one of alternative, a new design of hybrid excitation flux switching motor (ORHEFSM) for in-wheel drive EV is proposed. In this paper, the optimization design of single-phase 8S-4P outer rotor HEFSM is analysed. Open and close circuit of initial and final design is compared based on 2-D finite element analysis (FEA). The optimized design motor has produced higher torque which is 138.18Nm with 22.2% improvement compared to initial design motor which is 107.5Nm and has achieved the target value which 111Nm. The initial maximum power achieved was 17.02kW, while for the improved design motor, it has increased to 41.81kW, since the target maximum power is 41kW. The design optimization has been made on the initial design machine shows that there is great enhancement on torque and power.

Control of power generated from linear generator

This paper explains the power generation profile of the linear generator by controlling the 3-phase rectifier as a control converter when it is attached to the linear generator. Normally, the linear generator without control converter will produce decreasing power profile when the time is increased. By controlling the converter, the power profile can be changed to more suitable profile which is applicable for the load. In order to change this power profile at the linear generator, the controller that can operate in the robust condition will be used due to the disturbances inputs of the linear generator. Here, the H∞ control theory will be implemented in order to change the output power profile of the linear generator.