Liew Hui Fang
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Preferred name
Liew Hui Fang
Official Name
Hui Fang, Liew
Alternative Name
Fang, Liew Hui
Liew, Hui Fang
Liew, H. F.
Fang, L. H.
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Scopus Author ID
55987930400
Researcher ID
AAF-4915-2021

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  • Publication
    Direct torque control of induction motor with different energy storage for electrical vehicle (EV) application
    ( 2021-12-01)
    Aazmi M.A.
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Muhammad Zaid Aihsan
    ;
    Liew Hui Fang
    ;
    Mohd Saifizi Saidon
    Energy demand worldwide is rising at an unprecedented pace. This has already shown its impact on the depletion of energy sources and environmental issues (global warming and the weakening of the ozone layer). This growing pattern of energy insufficiency will, of course, intensify in the future. Referring to the literature, significant energy savings can be achieved by controlling the speed of the electric motor system using variable frequency drives (VFDs). Efficient control of induction motor drives provides an excellent opportunity for energy savings. As a result, research into the optimal operation of induction motor drives is escalating and mainly focuses on the Direct Torque Control (DTC) control technique on improving the dynamic operation of torque control. However, the study on the type of energies on improving the dynamic response is least reported. This paper will study the effect of different energy supplies on the dynamic response of torque performance. The standard DC battery and supercapacitor will be used to energize the induction motor through the three-phase inverter and controlled with the DTC control scheme. The results are validated through MATLAB Simulink and it shows the supercapacitor has the better dynamic response in torque response compared to the standard DC battery. The comparative results are presented in a proper mannered way.
  • Publication
    Review Article: Voltage Balancing Method for Battery and Supercapacitor
    ( 2023-02-01)
    Nordin N.N.S.
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Liew Hui Fang
    ;
    Muhammad Zaid Aihsan
    ;
    Mohd Saifizi Saidon
    This paper examines several existing voltage equalizers techniques for energy storage system, with a focusing on batteries and supercapacitors. Due satisfy the demands, energy storage cells are often coupled in series/parallel. However, divergence of voltage distributed among cells produces the problems of voltage imbalance that affecting the ageing of energy storage system and solved through equalizers. Several assessments from features of topologies in voltage balancing circuit supplied primarily based total on a few attentions’ just like the effectiveness in balance and components. Voltage balancing is essentially separated into two categories: passive and active equalizers. Therefore, this paper studied and reviewed several topologies from both equalizer types with the sample result to verify the topology performance.
  • Publication
    Piezoelectric Array Configuration Technique into Enhance Power Catchment for Sound Energy Harvester System
    ( 2020-11-18)
    Liew Hui Fang
    ;
    Rosemizi Abd Rahim
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Mohamad Zhafran Zakariya
    ;
    Junaidah Ali Mohd Jobran
    ;
    Norhanisa Kimpol
    The objective of this study is to explore the harvest maximum output changes occurs in piezoelectric transducer when connected in different configuration to produce highest electricity consumption and generate sound energy harvesting system. Acoustic energy is a type of environmental energy source that can be extracted and converted into electrical energy for small-scale energy applications. In this study, the corresponding load resistance for single piezoelectric transducer is 4.5 k$\Omega$, together with a constant vibration source at a frequency of 68 Hz and a 1-g acceleration. The performance of output voltage and power of piezoelectric are evaluated and the optimum output is measured by depending on the connection of the piezoelectric transducer arrangement into series, parallel and series, and parallel which stimulated using Proteus software. The experiment result presented that, when have single piezo, 5 piezo connected in series, and 5 piezo connected in parallel, the output powers are 1.664 mW, 1.671mW and 7.676 mW, respectively. During the combination series and parallel connections, the output power of 3S1P piezo increases to 5.05mW. In a parallel configuration, the output voltage that produced is much higher than a piezoelectric transducer arrangement connected in series connection. The piezoelectric transducer that connected in parallel configurations increases its voltage output from 2.83 V to 13.05 V with the same polarity. The arrangement of piezoelectric transducer in parallel configuration is affordable, with its higher production of a higher power output compared to the arrangement of piezoelectric transducer in series connection. Whereas in terms of power output, the maximum power remains constant in the range of 1.665 to 1.671 mW when three transducers are in series configuration connection with the same polarity. In conclusion, the proper implementation of the piezoelectric array configuration is needed in order to operate the minimum energy for low load devices and promise to accomplish generated optimum power output in harvester system.
  • Publication
    Solar Powered Multiple Output Buck Converter
    ( 2020-12-18)
    Muhammad Zaid Aihsan
    ;
    Norhanisa Kimpol
    ;
    Liew Hui Fang
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Wan Azani Wan Mustafa
    ;
    Junaidah Ali Mohd Jobran
    ;
    Mohamed Mydin Hj M.Abdul Kader
    Times have certainly changed over the past few decades, now it seems that technology is getting more compact and efficient. The modern outdoor enthusiast such as hikers, climbers has a problem regarding the lack of power supply to power up electronics when they go for adventure activities. In order to solve this problem, this paper design and develop DC/DC buck converter system to drop down the voltage from the solar photovoltaic (PV) system from 12VDC into 5VDC. This paper is first to start up with design and simulation circuit using simulation to test outcome of this paper in the range of 5VDC & 1.0A and 5VDC & 0.5A. A battery storage is needed to feed electricity independent and battery management of the battery is needed to improve the performance of battery life. This can be done by adding a charge controller unit. The outcome of this paper allows the battery to be charged using the solar panel and at the same time can produce multiple outputs for low voltages used. The software simulation has been done to shows this system produces two different output and the hardware will be developed based on the software results. Software and hardware result, both will be compared and analysed.
  • Publication
    Experimental study of Bipolar PV Inverter for nonlinear load
    ( 2021-07-26)
    Muhammad Zaid Aihsan
    ;
    Fahmi M.I.
    ;
    Liew Hui Fang
    ;
    Wan Azani Wan Mustafa
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Mohd Aminudin Jamlos
    One of the attractive options for converting solar PV DC/AC modules is a bipolar inverter as bipolar technique provide easy control and theoretically low-priced technology. A few drawbacks to this bipolar method, since it has a high voltage DC-link ripple, which can cause high harmonic inverter distortion. A smooth DC voltage is then needed to preserve the unstable voltage of the PV device in such a way that the overall harmonic distortion of the inverter is preserved at the regular stage. This paper will demonstrate the impact of unstable voltage from PV and connecting to the nonlinear load. The performance of the converter in term of efficiency and THD performance are monitored and reported.
  • Publication
    Design new voltage balancing control series connected for HV-IGBT's
    ( 2021-08-01)
    Fahmi M.I.
    ;
    Mukmin M.F.
    ;
    Liew Hui Fang
    ;
    Wai C.L.
    ;
    Aazmi M.A.
    ;
    Syahrun Nizam Md Arshad @ Hashim
    The insulated gate bipolar transistors (IGBTs) are widely used in various applications as they require low gate drive power and gate voltage. This paper proposes an active gain circuit to maintain voltage stability of series-connected IGBTs for high voltage applications. The novel gate driver circuit with closed-loops control amplifies the gate signal while restricting the IGBT emitter voltage below a predetermined level. With the proposed circuit, serial-connected IGBTs can replace high-voltage IGBTs (HV-IGBTs) for high-voltage applications through the active control of the gate signal time delay. Closed-loop controls function is to charged current to the gate to restrict the IGBT emitter voltage to a predetermined level. This paper also presents the experiment on the gate driver capability based on a series-connected IGBTs with three IGBTs and a snubber circuit. The experimental results show a voltage offset with active control with a wide variation in load and imbalance conditions. Lastly, the experimental results are validated with the simulation results, where the simulation results agree with the experimental results.
  • Publication
    Performance Evaluation of Transformerless Inverter based Quadratic Boost Converter
    ( 2021-01-01)
    Muhammad Zaid Aihsan
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Liew Hui Fang
    ;
    Wan Azani Wan Mustafa
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Al-Abbooda K.S.
    This paper presents a single-phase transformerless inverter based high step-up quadratic boost converter (QBC). By removing the conventional isolation transformer in the single-phase inverter system is grants higher efficiency and reduction in size as well as cost-effectiveness. The proposed topology can generate a standard single-phase power rating of 230 Vrms from a small dc voltage. The capability of the quadratic boost converter to perform a single-stage boost operation is guaranteed before inverted to the alternating sequence of Ac voltages as the constant duty cycle and proper unipolar modulation technique are well implemented. Experimental results are presented to verify the proposed topology capability.
      1
  • Publication
    Review of Active Circuit and Passive Circuit Techniques to Improve the Performance of Highly Efficient Energy Harvesting Systems
    ( 2023-06-01)
    Liew Hui Fang
    ;
    Rosemizi Abd Rahim
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Junita Mohd Nordin
    ;
    `Aini Syuhada Md Zain
    In piezoelectric energy harvesting systems, energy harvesting circuits are the interface between piezoelectric devices and electrical loads. The conventional view of this interface is based on the concept of impedance matching. In fact, in the power supply circuit can also apply as an electrical boundary conditions, such as voltage and charge, to piezoelectric devices for each energy conversion cycle. The major drawback of piezoelectric power harvesting have low-power relationships in systems within (in the range of μW to mW), then system also have significantly reduced any potential losses in circuits that make up the EH system, whereas other condition into careful selection of circuits and components can enhanced the energy harvesting performance and electricity consumption. In the study of energy harvesting systems, it is an energy harvesting system approach that using active and passive electronic circuit to control voltage and or charge on piezoelectric devices as proposed and review to mechanical inputs for optimized energy conversion. Several factors in the practical limitation of active and passive energy consumption, due to device limitations and the power efficiency of electronic circuits, will be introduced and have played an important role into to enhance optimum and increase efficiency of energy harvesting system.
      1
  • Publication
    Environmental noise harvester for low voltage power supply
    ( 2018)
    Liew Hui Fang
    There is an increased awareness nowadays regarding the potential shortage of fuel sources for electricity generation in the future, where various studies have been conducted about the usage alternative sources. Currently, the renewable energy has been prioritized for instance, through ambient energy scavenging. To achieve this goal, sound, being the most abundant energy in the environment, is likely the best candidate to fill the slot. The existing rectifying technique that has been used for energy transfer in energy harvesting is ‘switch-only’ and ‘bias-flip’ techniques which is utilize an additional switches or switched inductors for speedy voltage rectification. However, such techniques depend on the timing accuracy and synchronization of the pulses of the switch whenever the changes in the currents' polarity generated by the piezoelectric harvester. The existing acoustics-based energy harvesting systems utilized a self powered active rectifying diode circuitry technique to converts alternating current signal to direct current. The active MOSFET rectifier circuit has extra components and required an external DC supply to powering the rectifying circuit. Thus it is not a good option for small scale harvester system and suffered some drawbacks in the implementation of the circuit. Although synchronous switch harvesting on the inductor(SSHI) and synchronous electric charge extraction (SECE) rectifiers possess high efficiency to extract and harvest the energy available from system, they have drawbacksof SSHI circuits such as the complexity of the circuit which is can contribute to additional losses of power, threshold voltages, frequency selectivity and parasitic bandwidth filters. In this study, the developments of passive circuit including voltage multipliers (Dickson and Villard circuits) and step-up transformer were proposed and designed to rectify the low voltage acoustic voltage. The simulation of the proposed harvesting circuit was performed using Multisim and Portus simulator. For verification purpose, the PZT-5A piezoelectric transducer model has been chosen as the harvester due to the consistency. During the experiment, the resonance frequency of the harvestersystem was at 68 Hz with the 95 dB of acoustic pressure. The experimental results showed that the output closed-circuit voltage and the output power harvester can reach up to 3.894Vrmsand 1.556mW respectively. The passive AC-DC harvesting circuits can probably achieve the overall energy conversion efficiency by 78.9% (Dickson circuit) (1.228mW), 70.5% (Villard circuit) (1.097mW), and 10.1% (step-up transformer) (0.1564mW) respectively. Based on the results presented above, the proposed energy harvesting systems seem to be promising and possess a good potential to be used in low power sensors such as wireless sensor networks.
      7  20
  • Publication
    Development of Highly Efficient Hybrid Kinetic-Solar Energy Harvesting System
    ( 2023-01-01)
    Liew Hui Fang
    ;
    Rosemizi Abd Rahim
    ;
    Muhammad Izuan Fahmi Romli
    ;
    Junita Mohd Nordin
    ;
    `Aini Syuhada Md Zain
    ;
    Mujahidin N.M.D.Z.
    The development of sustainable and efficient energy harvesting systems has become critical in meeting global energy demands. Hence, the goal is to combine the kinetic energy created via footsteps alongside solar energy to maximize energy conversion and develop a sustainable power source. The research entails designing and optimizing the hybrid system, while selecting appropriate materials, and implementing advanced power management techniques for effective energy utilization. Therefore, in order to improve the efficiency of energy harvesting via the system, further research on voltage input for solar panels and piezo buzzer efficiency arrangements on slabs were conducted. Whereby, the tile cells generate electricity when someone walks across it. However, this energy output needs to be regulated using a voltage multiplier and an alternating current into direct current (AC-DC) converter. To accomplish this, an experiment on the outcomes for output parameter with stand-alone photovoltaic (PV) harvesting system in 6 days, piezoelectric (PZ) harvesting system with students weighing 60kg and 70kg in 14 steps and a power hybrid harvesting system was carried out. Overall, the findings of this study indicate that the proposed method is functional and can be verified by the system, with an average output of 9.46 V and 126.6 mA produced. Also, this study demonstrates the significant potential of hybrid kinetic-solar energy harvesting system in improving energy sustainability and promoting self-sufficient power generation for a variety of applications, including remote sensing, wireless sensor networks, and internet of things (IoT) devices, through experimental evaluations and simulations.
      1