*4.2. Dynamic Performance Comparison*

Next, the *d*-axis current reference step-change test was implemented to investigate the dynamic performance of the proposed MPC method. The *d*-axis current reference *id ref* was suddenly changed from 8 A to 5 A. Meanwhile, it should be noticed that the power factor angle ϕ was maintained as 0 to ensure the unity power factor operation.

The experimental waveforms are illustrated in Figure 8. Four MPC methods can provide a fast transient of the current response. Meanwhile, the unity power factor operation can also be realized under the post-step-change condition. The peak-value of phase currents was about 8 A and 5 A in the two cases, respectively. This comparison indicates that the proposed art does not sacrifice the dynamic performance to generate a better steady-state performance. Indeed, MPC methods determined an optimal control signal to regulate the control variable and the proposed method provided a novel implementation of optimization process while it retained the excellent dynamic performance of the classic MPC method.
