Fan Assembly Driven by Magnetic Fields Senior Design Project – Fall 2013

Introduction Problem Statement In some operating environments, it can be desirable to rotate a fan without directly contacting the fan. For example, it may be desired to position a fan in an environment that is inhospitable to a motor, such as a high temperature environment.

Introduction Proposed Solution Magnetic fields are generated by permanent magnets and electromagnets. Numerous variations of motors exist that apply different configurations of positioning permanent magnets relative to electromagnets to capitalize on the resulting repulsive magnetic forces. Our proposal applies these principles to drive a fan in rotation.

Background Information Current solutions to the problem: Remote motor-driven fans Motor-driven fans are positioned at location remote from the precise position at which flow inducement is desired. This can compromise the efficiency of the system since the fluid must be forced to move over a greater distance. Heater Technology Heat is directed to the fluid with the hope of inducing desired flow. This approach is unreliable.

Project Objectives Electromagnetics Technology Air Flow User Controls Feedback Control

Overview of Project Modules Power Supply Microcontroller Current Amplifier LCD Electromagnetic Coil

Power Supply Purpose Design Convert 120 VAC, at 60 Hz, to 5 VDC and 12 VDC Make the system operable to be powered by a standard American outlet Power the electronics of the system Design Influenced by IEEE Standard 355-1992 Step-down transformer Full bridge rectifier Filter Voltage regulator

Power Supply Schematic

Microcontroller Purpose Design Control the logic of the system Control LCD Interface the switches and sensor Design Microchip PIC18F46K44 16 MHz Oscillator speed 36 I/O pins Internal AD and DA converters Program Memory: 64k (bytes flash) Data Memory: 3896 (bytes SRAM) EEPROM: 1024 (bytes EEPROM)

Microcontroller Schematic

Microcontroller Microcontroller Software Initialize pins to desired configuration Algorithm to determine rpm Logic to actively monitor and display status of the system Logic to display various user menus Allows for three different run times and three different speed options Allows the user to terminate operation of the system at any time

Microcontroller Microcontroller Software Sample Code:

Current Amplifier Purpose Design Drive the output load (the electromagnetic coil) Convert 0 – 5 V input signal to 0 – 5 A. A buffer between the Microcontroller and the output load Design TI-OPA549 Operational Amplifier High current, high voltage amplifier Gain of 2 Powered by 12 VDC

Current Amplifier Schematic

LCD Purpose Design To communicate with the user To facilitate user control To display current system status Design Based on Hitachi HD44780 4 X 20 display Communicates with Microcontroller by the serial port

LCD Pin out:

Electromagnetic Coil Purpose: Generate a magnetic field to interact with a magnetic field generated by a permanent magnet mounted on a fan blade. Induce repulsive interaction between the magnetic fields. Maintain a fixed magnetic field to repulse the magnetic field generated by a permanent magnet mounted on the moveable fan blade. Impose movement of the fan blade and rotate the fan.

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design: Circular Coil Assembly surrounding the Fan

Electromagnetic Coil Design First Design Failure: Blades did not move Applied 1 – 5 A of current through the coil assembly. Observed extremely low magnetic field from the wires of the coil assembly. Did not test with Gauss meter, but filings sprinkled on the coil did not stick to the wires of the coil assembly.

Electromagnetic Coil Design Second Design: Coil wrapped around a rod positioned transverse to the blades.

Electromagnetic Coil Design Second Design Failure: Blades did not move Applied 1 – 5 A of current through the coil assembly. Observed a stronger magnetic field from the electromagnet relative to the first design, but still relatively weak. The magnetic field generated by the permanent magnet over-powered the field induced by the current running through the coil.

Electromagnetic Coil Design Prospective Action We will build a simple DC motor to allow the project to progress. We will further analyze the failures of the first two designs to determine if a third design can be constructed and tested in the available time.

Work Completed Power Supply Microcontroller hardware LCD hardware Successfully output 12VDC and 5 VDC Microcontroller hardware Successfully interfaced all switches and Hall Effect sensor LCD hardware Successfully interfaced with the Microcontroller Displays multiple menus Board Layout All components mounted on a single board Current Amplifier Successfully converts voltage to current

Plans to Complete the Project Build a simple DC motor The motor will allow us to test and fine tune the other modules. Implement Sensor for Feedback Controls Monitor Rotation Finalize Control Logic Add Timer and Speed Controls Finalize Enclosure Mount Board and LCD together in single enclosure

Conclusions Overview of Project Goal Build an electromagnetically- propelled fan having a high- level of user control. Summary of Completed Work Power Supply Microcontroller hardware LCD hardware Board Layout Current Amplifier Final expectations for the project We expect all modules to be functioning as desired, except the electromagnetic coil assembly.