Active roll compensation for automotive applications using a brushless direct-drive linear permanent magnet actuator

There is a growing interest in employing brushless permanent magnet actuators in direct-drive linear automotive applications. In these applications, the combination of low voltage (typically 12V) and high force levels, inevitably gives rise to very demanding actuator designs. This paper describes the design of such a linear actuator for active roll control. Notable features of this linear actuator are the relatively high force and limited volumetric space envelope, this in turn has a marked influence on the performance requirements for the electrical linear actuator, hence the specific force density. Numerous authors have commented on more electrical loads resulting in the next significant change for the current 12V standards to increase in working voltage to 42V. Such a system will provide higher power, enabling a range of new technologies, although the cost of converting to 42V is clearly a major challenge for the automotive industry. This paper describes the electromagnetic semi-active suspension requirements. An analytical design study is described for the specific force level. Further, an optimized design is investigated, by using an optimization algorithm, which reduces the specific space envelope requirements. Finally, these designs are thermally evaluated using various convection coefficients, which show the applicability of electromagnetic actuation in semi-active suspension systems.