Electromagnetic Levitation
Team Members:
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Sami Shalak
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Matthew Smith
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Mohammed Duffuaa
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Yaya Mahamat
Abstract:
In this project, our group built and implemented a basic model of a feedback controlled magnetic levitation system. The magnetic levitation system controls the magnetic field produced by an electromagnet to levitate a small object in midair. The design uses a Hall Effect sensor which produces an output that is proportional to the magnetic flux, the close the magnet gets, and the Hall Effect sensor will produce a greater signal. Then the output of the Hall Effect sensor is feed to a comparator and compared to a reference voltage in order to produce a pulse width modulated signal that drive the operation of the electromagnet which provides the repulsive force to the magnet that is placed on top of the object intended to levitate until a point of stable levitation.
Schematic of the circuit
Power enters through diode D1 with is to protect the circuit in case the power is hooked up backwards. The input voltage was chosen to be 13v after previous testing with the circuit. This voltage is regulated to 5 volts via the voltage regulator U1. This is because the Hall Effect sensor needs at least a supply voltage of 4.5V but no more than 10.5V, this can be seen from the datasheet in the appendix. The resistor R1 limits the current to LED1 and the voltage between them is approximately 3v due to the forward voltage drop of LED1. This allows the potentiometer to act as an adjustable voltage divider from 3-5v, while LED1 acts as a power on indicator. The LM358D operates as a comparator by comparing the output voltage of at pin 3 and the reference voltage at pin 2. The output of the comparator will be a pulse width modulated signal that will control the MOSFET that switches on and off the electromagnet.
The PWM signal
The Pulse width modulation signal output of the comparator which controls the MOSFET that switches the electromagnet on and off.
The magnetic levitation stand with the circuit on the top