Three-phase interior permanent magnet synchronous motor (IPMSM) drive systems have gotten widely used in various applications due to their speed regulation characteristics and high power density. Compared with classical field-oriented control (FOC)and flux-weakening control, model predictive control (MPC) technique is more efficient in achieving excellent performance without complicated controller tuning but with explicit constraints. Yet, the optimum application of MPC algorithm in machine control system is in the exploratory stage.In order to lower the current and torque ripples, this paper retains a modulator, but replaces all PI-control loops which are contained in the conventional FOC systems with a single MPC controller. Moreover, we adopt a brand-new linearization approach to tackle the strong coupled nonlinear IPMSM mathematical model, obtaining an improved linear plant model (ILPM) which is suitable for the motor with constant load torque. When it comes to flux-weakening control,the required d-axis current is calculated, after which it is used as the input of the proposed MPC controller, abandoning the previous natural field weakening method. Finally, for the purpose of lowering the dynamic speed and current overshoot, a further constraint in the change rate of manipulated variables is discussed. The improved control algorithm has been verified in simulation and experiment.