Short Range Electric Vehicle Motor Controller

The recent and steady increase in fuel cost, climate change and pollution has created a public awareness for energy conservation. The Internal Com- bustion Engine (ICE) is known to be highly inefficient during stop/start (acceleration) and idle periods at intersections and traffic lights. These are areas where electric vehicles surpass the efficiency of any ICE powered ve- hicle. Historically public opinion has been that electric vehicles do not have a place in everyday transport needs due to that fact they are limited by range. However a government study recently released figures stating that the average distance travelled by New Zealanders every day was less than 50km. Recent advances in electronic motor control have seen three phase Brushless DC Hub Motors in E-bikes become more readily available. These motors are also being prototyped in four wheel passenger vehicles for mass production. These Brushless Hub Motors are simple compact devices that allow for a reduction in moving mechanical parts and therefore servicing costs. Because a large percentage of New Zealand’s electricity production is via renewable energy resources it was proposed that a short range electric vehicle could be a solution to reducing the average New Zealander’s daily commuting expenditure. This thesis is directed at producing a proof of concept short range electric vehicle that might suit the daily needs of the average New Zealander, promote the clean green image and reduce their carbon footprint. The project covers the design of a vehicle to be classified as a Land Transport New Zealand LB2 vehicle. This includes chassis de- sign, motor selection and motor controller design. The main focus of the thesis is the design of a three phase Brushless DC motor controller and the accompanying firmware required to control it. The design is specifically focused on reduction in motor controller size, reduced cost and component ii count. This includes designing the PCB so that no extra programming or debugging interface is required. The schematic, PCB and firmware will be produced as part of an Open-source project, therefore giving others the opportunity to learn from the author’s mistakes and discoveries. A major discovery made by the author is that motor control design requires effective interfacing techniques. Switching noise is a continuous problem especially induced noise on Hall effect sensor outputs. Therefore correct design practices must be adhered to to achieve the desired goal