Field-oriented current control for a permanent-magnet brushless motor used in regenerative shock absorbers

In the recent years, mechatronic devices with energy harvesting features are becoming key elements in the automotive industry. These technologies lead to emission reduction, comfort and handling improvements. The aim is to push the related industry towards the electrification of powertrain and chassis, making it, as far as possible, environmentally friendly. The present work focuses its attention on regenerative shock absorbers: systems able to set damping or active forces to the vehicle suspension, allowing the efficient management of comfort-handling trade-offs, while also enabling energy recovery from road irregularities. The addressed regenerative dampers in this work arise from a long-term project, whose goal is to provide the design of a regenerative damper for automotive suspensions. The contribution of this thesis aims at the development of the motor control system and the ECU programming. The project implements a standard field-oriented control algorithm (FOC) with quadrature current control. Starting from this basis, many features and refinements have been added: the central aspects are the introduction of the flux weakening control, the regenerative phase management and the implementation on a Texas Instruments development kit. The method utilized to achieve the goals follows a Vshaped development flow. The work started from the analysis of the requirements and functional specification of the system and its power components. Successively, a high-level and low-level design of the algorithm have been done in the MATLAB/Simulink environment: this phase dealt with accurate modelling of every stage of the motor control and numerical validation through simulation. Then, the study evolved into the integration and prototype testing of the power stage on a test bench. During the experimental campaign the power electronic components have been set to work properly. A benchmarking analysis of the possible battery pack solutions has been done, while the 3- phase inverter and the connected DSP have been tested under several working conditions to validate them and their robustness. Finally, the functionality of the motor control system design has been verified, by investigating different operating points of the electric machine.