Master of Science (MS)
Electrical and Computer Engineering
The currently used electric drive for a wheelchair consists of brush permanent magnet DC motor and mechanical transmission that drives the wheels. The overall efficiency of this kind of drive usually does not exceed 60%. At present there is under study much more effective drive that consists of brushless DC motor which embedded into the wheel rim directly drives the wheelchair. This type of high efficiency gearless drive is the object of this thesis project. The particular brushless DC motor is a torus - type motor with a high energy rare - earth magnets and ferromagnetic teeth that fill in the space between the coils of Gramme's winding. The objectives of the project were to determine by computer simulation and laboratory test the electromechanical characteristics of the motor prototype in steady - state and dynamic conditions. For this purpose the measurement stand has been built and measurements were carried out in variable load conditions. To analyze the motor characteristics theoretically the mathematical models of the motor were developed one for steady - state and one for dynamic operation. The simulation of the motor drive was done using MATLAB/ SIMULINK software package. The results obtained from simulation confirm the requirements put on the gearless wheelchair drive and the determined motor ratings are as follows: supply voltage - 24 V, input current - 8.7 A, torque - 9.7 Nm, speed - 161 rpm, efficiency, 78 %. The cogging torque is practically unnoticeable. The results obtained from the test practically do not differ from those obtained from simulation. It means the calculation model used in simulation of steady - state and dynamic conditions has been verified positively.
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Chikkam, Deepti Rao, "Performance of disc brushless DC motor applied as gearless drive for wheelchair" (2005). LSU Master's Theses. 3284.
Ernest A. Mendrela