Electric to mechanical energy conversion of linear ultra-fast electro-mechanical actuators based on stroke requirements

The operational efficiency of ultra fast actuators used as drives in high voltage direct current breakers are at best 5 %. To boost their efficiency, the design of the energizing circuit is crucial. A multi-physics finite element method (FEM) model coupled with a SPICE circuit model that is able to predict the performance of the actuator with an accuracy of at least 95 % has been developed and verified experimentally. Several variants of prototypes and models have been simulated, built, and tested. It was shown that one of the main problems leading to low efficiencies is the stroke of the drive. However, there is a possibility to increase the efficiency of the electric to mechanical energy conversion process of the studied Thomson (TC) and double sided coils (DSC) to a maximum of 54 % and 88 % respectively if their stroke is minimized. This can be done at the expense of increasing the complexity and the cost of the contact system by designing a switch with several series connected contacts that is encapsulated in a medium with a high dielectric strength. Another proposed solution is to design a current pulse with a rise time that is considerably shorter than the mechanical response time of the system. Parametric variations of capacitances and charging voltages show that the TC and the DSC can achieve efficiencies up to 15 % and 23 % respectively. Regardless of the chosen method, the DSC has a superior efficiency compared to a TC.