/library/oar/handle/123456789/27531 2026-06-15T05:54:17Z 2026-06-15T05:54:17Z /library/oar/handle/123456789/27798 2018-03-09T02:25:12Z 2017-01-01T00:00:00Z

Title: Design of a modular half-bridge DC/DC converter Abstract: DC/DC converters are power electronic circuits that translate an input DC voltage to a higher/lower output voltage potential. These are used in a range of applications, from power supplies for portable electronics, telecommunications equipment to DC motor drives. This dissertation presents the design of a modular switch-mode DC/DC converter. The converter topology used is similar to the half-bridge converter, but instead of connecting the output to a passive load it is connected to another voltage source. Thus, the converter is able of being operated in first and second quadrants, supporting current flow in both directions. This is typically used in electric vehicles so to recover energy during regenerative braking. The designed DC/DC converter was initially simulated with open loop and closed loop control to verify the operation of the converter under different conditions. The DC/DC converter was then also implemented experimentally where printed circuit boards (PCBs) for the gate driver, over voltage and current protection, and signal conditioning circuitry of the voltage and current sensing were designed. Experiments were then also performed to verify the operation of the experimental DC/DC converter setup. Description: B.ENG.(HONS)

2017-01-01T00:00:00Z /library/oar/handle/123456789/27564 2018-03-06T11:01:41Z 2017-01-01T00:00:00Z

Title: A cooling fan speed controller for energy efficient temperature control of a race car engine Abstract: From small remote controllers to large vehicles, batteries are found almost in every portable device. Batteries have taken a lot of various shapes and sizes since the invention of the first battery by Alessandro Volta in 1799. They nowadays come in lithium cells, pencil batteries or lead-acid packages among other various forms. However since from they were invented, batteries have always caused some problems with regards to applicability as they lose their charge over time. Moreover the larger the current being drawn, the faster is the discharging process. Hence throughout time, the current required by a battery-powered electronic circuit was always minimised in order to reduce the size of the battery. This concept is quite vital when it comes to automotive applications. Minimising the current required will result in a less energy to weight ratio and hence a lighter battery for a lighter vehicle. Current can be reduced in several ways. One particular method is by developing a variable fan speed controller. Previous designers used to adopt an on-off controller system. Such a control scheme will switch on the fan when the temperature exceeds a specific value and switch the fan off again when the temperature is below a specified threshold. Although it is simple and easy to implement, it is not the most efficient method. Hence the variable fan speed controller, which monitors the engine and the cooling liquid temperature and adjusts the speed accordingly. The objectives of this dissertation are to: 1. Design and build an efficient DC-DC converter to vary the speed of the fan 2. Design and build all temperature measurement circuitry 3. Develop all the control algorithms to regulate the temperature and speed accordingly by generating and applying PWM signals to the DC-DC converter All the aforementioned controllers were modelled and simulated with MATLABR and Simulink application packages. These were then implemented on an Atmel ATmega328P microcontroller. Description: B.ENG.(HONS)

2017-01-01T00:00:00Z