Comparison of two alternative power supply strategies for an electromagnetic tilting actuator

In this article, two power supplies including measurements on a prototype are presented, intended for use with a novel electromagnetic tilting actuator (ETA) concept. The concept of the ETA is based on cylindrical elements tilting around a fixed axis. It is composed of a bevelled ferromagnetic core with a kidney-shaped coil inside. Possible applications of such manipulators sequenced in chain are in the field of medical or veterinary engineering and robots used for confined spaces. For the purpose of tilting, short peak currents are needed at each coil; in the simplest option, this energy is supplied by a capacitor. After reaching its new position, smaller stationary holding currents ensure the fixation of position against manipulation forces. To provide both functionalities from a single source, a control board has been designed using Pulse Width Modulation (PWM) to regulate to the desired holding current. Due to the oscillation around the specified holding current, this solution suffers from additional losses through eddy currents in the core. But it provides higher controllability allowing to set the current in two directions. In this article, the design of a PWM-based supply option is described and compared to a two-level DC solution. Moreover, electrical and thermal measurements are presented.