Implementation of Magnetic Suspension Control With FPGA

This paper presents a methodology for an alternative implementation of DSP-based controllers typically used for magnetic bearing (MB) levitation and control on FPGA hardware. The approach takes s-domain transfer functions of the controller components and discretizes them using z-transform conversions into discrete time domain expressions. These expressions, which are essentially digital IIR filters, are synthesized and implemented to obtain downloadable bit-stream using Xilinx ISE software packages. In the example presented, the executable code was sent to configure the two FPGAs for control. An equivalent PD with notch filter FPGA-based controller was constructed to replicate an existing two-axis DSP controller used to control a radial magnetic bearing on a vertical rotor in the Dynamic Spin Rig Facility at NASA Glenn Research Center. The FPGA controller was successfully demonstrated on the NASA hardware.