Preface: I'm a chemical engineering undergraduate student but as small-time and noob electrical engineering hobbyist. I really only have minimal experience in circuitry and the like. I want to build a series of electromagnets with a variable their strength in order to levitate an opposing circular Halbach Array up to and from a certain height. This array will be separated from the electromagnets so I don't have to worry about it "sticking" to the electromagnets when off. There will also be a guide pole through the center of the array so that it stays balanced. What would be the different factors I should consider when using a either a potentiometer or a MOSFET or PWM or some other kind of voltage variant? Are there other kinds of energy controllers, that I could potentially use? How do they differ from each other? Thank you so much in advance.