In order to achieve higher fuel efficiency and better ride comfort, this paper introduces a shock absorber system including Mechanical-Motion-Rectifier (MMR), power converter and its current/force tracking (ICFT) controller.
MMR based shock absorbers has the benefit of higher efficiency and better mechanical reliability than conventional regenerative shock absorbers. However, the one-way clutches and inertia in MMR induce disengagement between input shaft and generator. This nonlinear behavior makes the input current/force of MMR uncontrollable with conventional feedback controller design. To solve this problem, this paper presents an input current/force tracking (ICFT) controller for MMR based suspension system. By adding additional control laws to the conventional controller, ICFT controller successfully solves the nonlinearity problem during MMR control. This ICFT controller is tested by tracking the reference force from skyhook control to improve ride comfort. The vehicle body displacement is simulated under specified speedbump.
By using this ICFT controller, the simulation result show displacement error between skyhook and ICFT-MMR is within 5% and its total harvested energy is 56 joules, as 56 W of average input power. Equivalent circuits used for circuit simulation are proved to have identical performances as mechanical models.