Mohd Farriz Basar

A wide-speed high torque capability utilizing overmodulation strategy in DTC of induction machines with constant switching frequency controller

This paper presents a simple overmodulation method employed in Direct Torque Control (DTC)-Constant Switching Frequency (CSF) controller of induction machines. The proposed overmodulation method is utilized to extend a constant torque region and hence produces high torque capability in field weakening region with six-step operation. It will be shown that the overmodulation operation using the DTC-CSF scheme can be established by controlling the stator flux locus from circular to the hexagonal shape. This is achieved by modifying the flux error status produced from flux hysteresis controller, before it is being fed to the look-up table. The main benefit in the proposed strategy is its simplicity and it can be implemented in many electric drive applications to obtain maximum torque capability for a wider speed range operation.

A simple dynamic overmodulation strategy for fast torque control in DTC of induction machine with constant switching frequency controller

This paper presents a simple dynamic overmodulation method to obtain a quick dynamic torque response in Direct Torque Control with constant switching frequency (will be referred as DTC-CSF) induction machines. A fast dynamic torque control can be achieved by applying a voltage vector that produces the largest tangential flux component during the transient condition. To perform this, the flux error status produced from the flux hysteresis comparator is modified before it is being fed to the look-up table, during dynamic condition. The effects of different switching and operating condition on dynamic torque performance are presented. The main benefit of the proposed method is its simplicity since only minor modification is made to the basic DTC hysteresis-based structure.

Simple Realization of 5-Segment Discontinuous SVPWM Based on FPGA

The Space Vector Pulse Width Modulation (SVPWM) is possibly the best among all the PWM techniques for variable frequency drive applications. Unfortunately, the modulation algorithm is mainly implemented with software based on microcontroller or digital signal processors (DSP). These are software-based technique purely and obviously not an ideal solution. Employing Field Programmable Gate Array (FPGA) to realize SVPWM strategies provides advantages that it is considered as an appropriate solution to boost system performance of an SVPWM algorithm. Moreover, although in the literatures the implementation for three-phase SVPWM based on FPGA is not lacking, however all these designs are based on the conventional SVPWM without considering hardware-resource saving and not simple. This paper present a simple realization of 5-segment discontinuous SVPWM with a difference approach based on FPGA, in which the judging of sectors and the calculation of the firing time to generate the SVPWM waveform is simple, and also the switching losses is low. The proposed discontinuous SVPWM has been designed and successfully implemented by using APEX20KE Altera FPGA considering hardware-resource saving and has successfully driven a three phase inverter system with induction machine 1.5 kW as load.

Design and development of green electricity generation system using ocean surface wave

Once the non-renewable energy such as petroleum, coal, gas and nuclear have been used, it cannot be restored. Many countries in the world are heavily dependent on the non-renewable energy and polluting sources to generate electricity. This would cause the greenhouse gas emissions and would have adverse effects on the country due to the climate changes. Generally, 75% of earth is covered by the ocean and for that reason; converting the surface wave energy into electricity essentially is a form of renewable energy available on the earth. Thus, this paper describes the design and development of green electricity generation system using surface wave power for small-scale applications. The generation system is presented by the handy floating box that consists of neodymium iron boron permanent magnets, 1,000 turns of solenoid wires and voltage multiplier system. As oceans waves moves along the floating device, the solenoid rocks back and forth the permanent magnet and hence the relative motion produces electrical power. From the experimental works, it gives a significant result and shows a positive indicator on the effort to harnessing this clean energy.

Analysis of movement for unmanned underwater vehicle using a low cost integrated sensor

This paper presents the development of low cost integrated Smart Sensor for Unmanned Underwater Vehicle (UUV) namely as underwater Remotely Operated Vehicle (ROV). In the underwater industries, the most crucial issues are the sensors that are needed for the underwater task. The sensors that are utilized in this area are quite expensive and sensitive. Every sensors used in the underwater vehicle are not in the form of integrated sensors and most of them based on case to case basis. However, nowadays, a lot of industries are involved in the development of the integrated sensor in order to reduce the production cost as well as to increase accuracies, efficiencies and productivities. Therefore, this research proposes an integrated sensor to be applied in the underwater operations. The integrated sensor is designed based on three goal performances which are; the accuracies; the sensitivities and the cost efficiencies. This integrated sensor is the combination of pressure sensor, inertial measurement unit (IMU), digital compass and temperature sensor that are placed in a waterproof casing. This integrated sensor is targeted to be used to control the movement of ROV to maintain its position called station keeping. The purpose of the station keeping is to ensure the ROV to remain stationary at the desired depth by utilizing the pressure sensor. The experimental studies have been carried out in order to see the responses of each sensor.

Performances evaluation and comparison of two algorithms for Fuzzy Logic rice cooking system (MATLAB Fuzzy Logic Toolbox and FuzzyTECH)

This paper presents an evaluation of performances rice cooking system with using Intelligent Controller that is Fuzzy Logic Controller (FLC) to meet the special requirements and some limitations of the rice cooking system. A new inference scheme is given to estimate the amount of rice and water to be used, and the temperature will be controlled according to the amount of rice and the time while cooking. The FLC system is designed by using two types of simulation software which are MATLAB Fuzzy Logic Toolbox and FuzzyTECH. The results obtained from the both simulation software are given in this paper. The differences the between both simulation also will be discussed. MATLAB Toolbox gives more specific results compared FuzzyTECH software. The both software meet the special requirements because is not much differ between each other.

Lightning Energy: A Lab Scale System

This chapter which has six subchapters explains the energy storage system in harvesting a lightning return stroke for a lab scale system. Nowadays, the world is facing the energy crisis and consequently a renewable energy is required as an energy contributor to solve the crisis. Hence, it is believed that lightning return stroke has a good future to be a free electricity sources. The main difficulty in harnessing the lightning stroke is to attract and simultaneously to store the energy, which limited in a microsecond. Due to that, the computer simulation works using PSpice is done as the preliminary effort intended for the hardware development as well as to understand and verify the proposed system. A lab scale system is set up based on natural characteristics of lightning to determine the performance of the sample capacitor as energy storage accurately. Hence, the single stroke impulse voltage is used as a mock of lightning. Regarding the energy storage device, the capacitor is employed due to the reliability, cost-effective and it is the most common. In addition, the direct tapping system and the high speed switching is most wanted in order to make the whole system more realistic. The capacitors are subjected to 1.2/50μs, 4,200V single-stroke impulse voltages generated by a single stage impulse generator. In this chapter, the energy of impulse voltage that successfully transferred and stored in the storage capacitors is discussed. Basically, the efficiency of the energy transfer is depends on the capacitance values and the switching times. As a final point, the lab scale system explained in this chapter demonstrates the capability to capture the energy from lightning return strokes that can be a clean energy sources. On the other side, lightning which have extremely high current and high voltage is a gratis electricity energy sources that can be replenished. The lab scales systems for harvesting the energy from lightning return stroke, which discussed in this chaper able to give a new contribution to solve the energy crisis and it will be very challenging. Up until now, the mature technology in harvesting the lightning stroke for the large-scale system is still not yet ready and the relevant scientific literature is not easily found. It noted that the final system proposed in this chapter would provide an understanding of the system principle and additionally provide a noteworthy contribution for further research.

Investigation on the performance of pico-hydro generation system using consuming water distributed to houses

This paper describes the testing conducted that necessary to investigate the performance of pico-hydro generation system using consuming water distributed to houses. Water flow in the domestic pipes has kinetic energy that potential to generate electricity for energy storage purposes in addition to the routine activities such as laundry, cook and bathe. The inherent water pressure and water flow inside the pipe from utilitys main tank that used for those usual activities are used to rotate small scale hydro turbine to drive a generator for electrical power generation. Results from the test significantly show the proposed system is feasible for electrification for energy storage purpose and indicate the prospect of further improvement and future research.

Design and development of a small scale system for harvesting the lightning stroke using the impulse voltage generator at HV lab, UTeM

This paper describes the design and development of a small scale system for harvesting the lightning stroke using the single impulse voltage generator. The testing conducted at high voltage lab at Universiti Teknikal Malaysia Melaka (UTeM). A new source of renewable energy from lightning return stroke is a possible contributor to solve the energy crisis. The main problem in harvesting the lightning energy is to capture and store the energy within a very short time. Hence, computer simulation works is done as the preliminary effort intended for the laboratory set up as well as to understand and verify the operational system principle. A small-scale laboratory is set up based on natural characteristics of lightning to determine the performance and capability of the sample capacitor accurately, since a capacitor nowadays becomes the most widespread, economical and reliable energy storage device. The capacitors are subjected to 1.2/50µs single-stroke impulse voltages generated by a single stage impulse generator. The proposed system shows that the impulse voltage able to transferred and stored the energy in the storage capacitors. Hence, it gives a positive indicator to the proposed system referring to the concept of capturing energy from lightning return strokes, which can be a potential source of renewable energy.