Electric vehicles

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Electric Vehicles

Researchers : Jesse Teat and Dr Tim Molteno

In recent years the demand for short range travel has increased with the average New Zealander traveling 40km per day, often within urban areas. The Internal Combustion Engine (ICE) is known to be highly inefficient during stop/start (acceleration) and idling periods. In this situation an electric vehicle out performs its fossil fuel counterparts.

Speculation abounds regarding the future of EVs. Effective fuel storage and inefficiencies in generating electricity for storage are viewed as EV short comings.

The Otago Electronics EV

The Otago Electronics Research Group is tailoring an EV for short-range travel. The EV will be the platform for a number of Masters and Postgraduate projects. It will have a max speed of 50km/h and a range of approximately 50km.

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Testbench Vehicle

Testbench Vehicle

The Test vehicle is complete. The current test vehicle utilizes a 2kw in-hub BLDC motor allowing for reduced losses and compact design. As a power source the testbench has an array of 4 12V 40AH sealed lead acid batteries. These can be switched out for 5 12V 20AH lead acid batteries increasing the top speed to 50km/h. The chassis is modeled from a go-kart with numerous application specific alterations. Stability is improved with a low center of mass and front mounted batteries.

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2KW In-hub BLDC Motor

Motor

Hub motors are used for this project to enable simplicity of design and decrease energy losses. The motor used in the test vehicle is a 2kw BLDC model as stated above. This will be tested alongside other in-hub models with a variety of power ratings to identify the most efficient and suitable for our vehicle. The BLDC hub motors are three phase with built in hall effect feedback and use a control method is similar to a three phase AC motor. Each 2kw motor has 54 windings giving a single phase hall effect frequency of 18Hz per revolution.

Power Source

To reduce cost during the initial test period the EV is powered by sealed lead acid batteries. The battery packs are assembled from deep-cycle 12V batteries supplying voltage ranges from 48-60V. The batteries are easily replaceable allowing a swap to lighter technologies in the future.

Controller

The vehicle has a three-phase Brushless DC motor controller. Research on the development of new controllers is under way. Our goal is to provide maximum efficiency, while at the same time maximising torque at low speeds.