A Comparison of GaN Transistors to MOSFETs for Active Magnetic Levitation

Active magnetic bearings have higher efficiency than other bearings because there is no physical contact. However, this benefit is mitigated by the addition of electrical power consumption. It is therefore important for magnetic bearings to have efficient power electronics. Gallium nitride based transistors are a relatively new form of transistor which have shown to be more efficient than MOSFETs. There is insufficient body of literature in the area of application of these transistors for magnetic levitation. This work presents a simple 1 degree-of-freedom voltage controlled levitation experiment in which levitation is achieved with both a gallium nitride transistor and a MOSFET. Voltage losses and current consumption are measured when using each transistor during levitation. In particular, transients during open to closed and closed to open states are measured for PWM pulsing. It is found that the gallium nitride transistor is superior in both switching time and efficiency in situ for magnetic levitation.