Design and topology selection method for brushless motors in regenerative dampers

Abstract

The objective of this thesis is to demonstrate the hypothesis that a regenerative damper will be able to fulfill efficient comfort and road holding constraints for a vehicle suspension if a proper method to design the electric motor is implemented and a suitable machine topology is selected. Previous is justified on the problem that the state of art in regenerative dampers is not clear which brushless permanent magnet rotor topology is appropriate nor a unified method that covers all the processes to develop this motor for regenerative dampers exists. The unified method includes the geometry parametrization and winding design, cross-section optimization to maximize torque, losses/efficiency characterization, and field-oriented control using MATLAB and FEMM, an open-source finite element program to promote its availability. The process is applied for a surface-mounted and two interior permanent magnet rotor topologies named single magnet and V-shape. Additionally, an analytical model for the surface mounted is presented based on literature due to a stable flux distribution is present. Moreover, the present method can be extended to other fields which use these types of motors as electric vehicles. The most suitable machine configuration is the surface-mounted permanent magnet since the torque is the highest combined with a low torque ripple and low permanent magnet mass compared with the interior magnets. The motor is validated in an appropriately designed regenerative suspension intended for a C-class vehicle. Optimal suspension control is applied to evaluate vehicle dynamics under two optimal operational modes: comfort and road holding. The regenerative suspension fulfills the expected behavior, even when a force compensation term is included to account for inertia and viscous damping, friction. Moreover, the device is energy-self sufficient in both operating modes, but energy recovery decreases when inertia is considered.