Innovative electric motor drive centrifuge produces rapid onset/decay rates

Since approximately 1970, the Sandia Weapons Evaluation Test Laboratory used hydraulic motor/gear train driven centrifuges to provide high onset/decay rate g-environments to test nuclear weapons subassemblies. To eliminate safety hazards and vibration associated with hydraulics and gear trains, these units were replaced with innovative electric motor driven centrifuges. The drive units for these new centrifuges are identical and each consists of multiple permanent magnet (PM) brushless motors directly coupled to the centrifuge spindle and driven by pulse width modulated (PWM) servo controllers. This paper describes the design, development, and test results of new technologies combining unique PM brushless motors, PWM controllers, and system control to synchronously commutate multiple motors. These new centrifuges have extremely high pulse-torque to inertia ratios, ratios which in the past could only be attained by the use of multiple hydraulic motors and gear train drives.