Magnetic Bearing Controls for a High Speed, High Power Switched Reluctance Machine (SRM) Starter/Generator

The magnetic bearing control system development and integrated system test results are presented for a high speed, high power Switched Reluctance Machine (SRM) Starter/Generator (S/G). The SRM rotor is suspended on magnetic bearings in a single shaft gearless/oilless configuration operating at 42,000 RPM.

The SRM sub-system consists of a 6/4-pole machine with dual-power inverters rated at 250 KW (max), 270Vdc with split bus configuration. The magnetic bearing sub-system actively controls the rotor position in five axes (four radials and one axial). The bearing subsystem consists of homo-polar type magnetic bearing actuators with permanent magnet (PM) bias, inductive position sensors, DSP-based embedded controller and PWM current drivers for each control axis.

The development and implementation of Single Input Single Output (SISO) and Modal control laws are presented. The radial control axes feature Adaptive Vibration Control (AVC) to reduce synchronous magnetic bearing current response due to rotor unbalance.

The integrated SRM/Magnetic Bearing system test results are presented with the SRM operating as a motor and generator under load.