Predictive DC-link voltage control of permanent magnet synchronous machine drives for hybrid electric vehicles

The goal of this paper is to provide a controller synthesis method for controlling the DC-link voltage in permanent magnet synchronous machine drives employed in hybrid electric vehicles (HEVs). To this end, a model predictive controller based on control Lyapunov functions is used to adjust the torque request in order to obtain fast and monotonic transient DC-link voltage. Moreover, a state and disturbance observer is used to obtain the load current needed by the control structure. The torque reference has to be converted into current references in order to be used by the inner current control loop. Because the torque function is a non-convex non-linear function, a piecewise affine approximation is made by gridding the current and torque spaces. As a result, the current reference generation problem is reduced to a convex optimization problem. The effectiveness of the proposed method is illustrated using a realistic simulation scenario including a comparison with the classical PI approach.