A Novel Hysteresis Current Control Strategy for Switching Power Amplifiers in Active Magnetic Bearings

A switching power amplifier with hysteresis current control strategy in active magnetic bearings has the characters of a simple implementation, a high dynamic response and a good performance on small signal sensitivity. However, for the frequency limit of switch element, the hysteresis band can’t be too small. In this paper, a novel double band hysteresis current control strategy is proposed, where an additional hysteresis band is brought in the conventional hysteresis band current control strategy. The proposed method can realize tri-state modulation, and reduce the switching frequency at the same hysteresis band. Theoretical analysis, simulations and experiments have verified that the switching power amplifier with double band hysteresis current control strategy has lower switching frequency and smaller current error.