Soft Switching Multichannel Magnetic Bearing Amplifier with Reduced Number of Switches

In a magnetic bearing system, the levitation coils or electromagnets are typically controlled by a multichannel switching amplifier which drives every coils with a hard-switching H-bridges to control coil currents and achieve stable rotor levitation. As a magnetic bearing system typically includes multiple coils to control multiple degrees of freedom of the rotor, large number of channels is required in order to drive every coil. While soft switching converter has certain advantages in comparing with hard switching ones, such as lower power dissipation and low electromagnetic interference, existing soft switching topology for magnetic bearing amplifier application requires additional auxiliary switches for every coil, which dramatically increase size and cost of the converter, making soft switching topology unattractive for magnetic bearing amplifier application. In this paper, a multichannel soft switching magnetic bearing amplifier topology with reduced number of switches is proposed to address the drawbacks of existing hard and soft switching magnetic bearing amplifier topologies. The proposed topology is verified with simulation as well as hardware implementation and testing.