PWM Current Driver Design and Implement for Electric Magnet of Magnetic Suspension System

This research used the pulse width modulation technique to design a switched current driver design for the electric magnets of magnetic suspension system. Dye to the phenomenon of the MOSFET, the driver can operate in the great voltage and under the bigger electric currents than the traditional push-pull linear driver. Furthermore, the relationship of the force slew rate and the supply voltage are proposed. The driver is composed of the interior loop control circuit of the proposed driver made by the operational amplifier, the two-quadrant chopper, and the three-level PWM controller. The experimental results show the proposed driver better than the traditional push-pull linear driver in the response rate, the system bandwidth, the transition response as well as the low current distortion. The experimental results also shown the system bandwidth of the proposed driver may reach several kHz under the different loading condition.