Energy flow analysis and hybrid controller design for non-linear electromagnetic suspension

In this paper, a mathematical model for the developed electromagnetic suspension actuator is established based on measured parameters and test data. A main/inner-loop control strategy is proposed for its active control and the inner loop undertakes the control of a three-phase motor by applying a hysteresis current control method to track the calculated signal by the main loop. With the simplification of the inner-loop control system, the achievable range of control current and energy flow states of the actuator are analysed. Then, owing to the non-linear damping characteristic of the actuator, a hybrid system model which involves real and integer variables is built up for the main loop and optimal control to improve vehicle ride comfort is carried out based on a model predictive control method. Simulations are carried out with bump impulse and random uneven road inputs and the results demonstrate that the electromagnetic suspension with the designed hybrid controller can improve vehicle ride comfort compared with a corresponding passive suspension while energy is consumed from the battery.