IGBT power amplifiers for active magnetic bearings of high speed milling spindles

Active magnetic bearings used in high speed milling spindles require high dynamic performance and high reliability. In this paper, a new power amplifier using insulated gate bipolar transistors (IGBTs) is described. A three-level pulsewidth modulation (PWM) scheme and a dead-beat current controller are used to reduce the switching frequency and current harmonics. The experimental results with the newly developed IGBT amplifier show that the total power losses are obviously reduced without any negative influence on the dynamics of the control system.