Rupert Gouws

Performance Analysis of a Permanent Magnet Transverse Flux Generator With Double Coil

One of the disadvantages of permanent magnet (PM) transverse flux machines is high magnetic flux leakage in the stator and rotor cores. To improve the magnetic circuit of this class of machines, a generator with double coil was designed and built to research the problem. The machine topology is different from the topologies previously introduced in the literature. The main difference was in the stator and rotor configurations. The stator of the generator is divided by two parts: 1) outer and 2) inner. Two coils were placed in the inner and outer stators. The rotor with PMs was placed between the two stators. To diminish magnetic flux leakage in the stator and to decrease machines weight, magnetic poles were placed in aluminum housings. This resulted in high-density eddy currents induced in the housings, and a significant raise of the temperature. The housing of the machine was modified. The prototype test showed that the modified version of the stator contributed to a significant decrease in temperature. Electromechanical parameters and cogging torque of the proposed generator is also studied and presented in this paper.

On the role of magnetic shunts for increasing performance of transverse flux machines

This paper presents work completed in order to investigate the importance of magnetic shunts in transverse flux machines. Two types of transverse flux machines with different configurations were designed and tested in the laboratory. The first type of machine is a transverse flux generator with inner rotor. This machine was designed according to one of the patents. The second type of the machine is a transfer flux generator with double coil. Both types of the generators were designed in such a way so that it was possible to implement magnetic shunts inside the machines. Finite-element method analysis and experimental results showed that transverse flux machines without magnetic shunts had a number of disadvantages compared to those with magnetic shunts. These disadvantages are: higher flux leakage in the stator cores, partial cancelation of flux linkage in the coils, higher cogging torque, and increased torque ripple. This paper showed that magnetic shunts played a significant role in the performance of transverse flux machines. As study showed, magnetic shunts complicate a manufacturing process and increase the weight of the machine. However, power to weight ratio of the machines with magnetic shunts is higher than that of the machines without magnetic shunts.

Energy management system for a residential grid-tied micro-grid

With the national power grid under tremendous pressure, there are enormous pressure exerted on residential electricity consumers to cut-back on electricity consumption to ensure a reliable supply. This has led to residential electricity users wanting to generate their own electricity through solar and wind systems, more formally known as distribution energy resources (DERs). The possibility of DERs currently exists within the centralized power grid, but is currently not well supported by Eskom and local municipalities. There are currently very little widely implemented policies regarding net-metering and feed-in tariff structures amongst Eskom and municipalities. Thus, excess generated energy fed into the grid is used elsewhere without any benefit going to the owner of the DER. By implementing an active energy management system (EMS) alongside the grid integrated system, electricity generated by the DER can be consumed locally by the residential loads. The EMS achieves an electricity consumption reduction of 23.4 % compared to a system with no EMS. Further results show that the EMS compensated system shows a cost saving of R19.17 per day which translates to a reduction of 51.4 % compared to a system with no EMS.

Thermal and efficiency analysis of a single phase induction motor with Peltier devices

We present the results obtained from the thermal and efficiency analysis of a single phase induction motor with Peltier devices. A single phase induction motor is completely simulated in SolidWorks® and Matlab® Simulink®. The cooling of the induction motor is done by means of Peltier devices and the corresponding power consumption and stator temperature is recorded. From the SolidWorks® simulation results it can be seen that the temperature of the induction motor under normal operating conditions is cooled from 68°C to 35°C. From the Matlab® Simulink® simulation results show that the efficiency of the induction motor is increased by an average of 3.73% from the normal operating condition to the cooled operating condition with the inclusion of the Peltier devices onto the system.

Analysis of PM transverse-flux outer rotor machines with different configuration

This paper presents the electromagnetic analysis of two permanent magnet transverse-flux outer rotor machines with and without magnetic shunts. The research started with designing and analyzing a permanent magnet transverse-flux machine with an inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying three-dimensional (3-D) finite element method (FEM), the main problem of the machine was detected. The problem was in high flux leakage that weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor, with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. Three-D FEM results are supported by laboratory analysis of the machines’ prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance as compared with the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque.

Prototype monitoring system for power line inspection by means of a PandaBoard

The national energy supplier (Eskom in South Africa) supplies electricity through thousands-of-kilometers of overhead power lines. The current methods of inspection of these overhead power lines are infrequent and expensive. In this paper, the authors present the development of a prototype monitoring system for power line inspection in South Africa. The developed prototype monitoring system collects data (information) from the overhead power lines, is remotely accessible and fits into a power line robot. The prototype monitoring system makes use of a PandaBoard ® (SBC) with GPS receiver and 5 MP camera to collect data. Hardware fatigue is the biggest problem faced on the overhead power lines and is captured by means of the 5 MP camera and is displayed on a website hosted by the PandaBoard ® via Wi-Fi. The monitoring system has low power consumption, is light weight, compact and easily collects data. The data obtained from the prototype monitoring system was satisfactory and provides an improved solution for monitoring power lines for Eskom in South Africa.

Solar power pumping system for domestic appliences

With the world encountering huge pollution problems, use of renewable energy is being encouraged in place of fossils fuels for electricity generation. On such renewable energies is solar power. Solar powered systems are able to generate electricity using photovoltaic (PV) panels, or thermal collectors directly from sunlight. Pool pump electricity consumption has also risen in South Africa. This paper presents the results of the design, and construction of a PV solar system to effect water pumping in rural areas; pool pumping in urban areas. Before the design was completed the load requirement of pump/motor was gathered. PV system software carried out simulations of the design before implementation. A PV solar system prototype was constructed, tested; results verified.

Smart whiteboard for interactive learning

The need for educators conveying information more interactively has increased as we are moving into a more technological era. A need for increasing the efficiency of lectures has become very important. This project addresses the need for improved efficiency in ways of presenting a class. The challenge is to provide an alternative and affordable way to chalkboards and passive Power-point or transparent slides obtaining more interaction from students and improving the efficiency of a lecture. Interactive whiteboard was made possible by using Nintendo Wii remote and PC suite. Replacing the conventional chalkboard makes viewing sessions at another time/place possible. The software suite developed enables any PC display to be used as an interactive whiteboard.

Data logger and companion application for time-of-use electricity

Electricity generation is becoming more expensive, hence Time-of-Use (ToU) electricity tariff structures, such as Eskom Megaflex are implemented. The companion application is an integrated solution designed for use with such schemes. A hardware module logs consumed power from a smart power meter and saves it on an external storage. The logged data is transferred to an Android application where it is displayed visually in the form of graphs. These visual indicators can assist end-users to improve their electricity usage at strategic times, ensuring financial savings, as well as increased grid stability. The proposed design was constructed and implemented on an actual smart-power meter. Results from the tests carried out to ensure compliance with the requirements are presented together with the design overview.

Optimal switching-flux motor design and its cogging effect reduction

This paper presents an optimal switching-flux motor design in terms of cheap cost, simple manufacturing process, and easy maintenance. The high cogging effect and its impact on the performance of the machine is studied by measuring the following electromechanical characteristics of the machine in both generating and motoring regimes: cogging torque, electromagnetic torque and induced voltage. The results showed that high cogging torque negatively affect the performance of the machine. The goal of the research was to reduce the cogging torque of the motor without changing the shapes of permanent magnets and magnetic poles, and to avoid any implementation of the magnetic shunts or magnetic bars into the machine. Parametric analysis of the outer rotor configuration with different air-gap diameters showed the optimal machine design which offered: five times lower cogging torque, 8 percent increase in electromagnetic torque, 24 percent decrease in volume, and 33 percent decrease in copper mass compared to initial design of the machine. Additional recommendations on the motor improvements based on Finite Element Analysis (FEA) are also provided.