Model Predictive Thrust Force Control for 3L-NPC Fed Linear Synchronous Motor of Maglev Train

The thrust force ripple of a maglev linear synchronous motor (LSM) would reduce comfort and even cause resonance; moreover, the neutral point voltage of the three-level neutral point clamped (3L-NPC) inverter will also affect the safety. In order to reduce the thrust force and neutral point voltage ripple, a traction control scheme based on the model predictive thrust control (MPTC) method for maglev is proposed in this article. First, the control of thrust force and stator flux is transformed into the control of flux vector, eliminating the weighting factor of flux in the cost function. Then, a three-stage selection scheme is applied to determine four effective voltage vectors (VVs). Additionally, the concept of deadbeat control is introduced to allocate the durations of each vector in every control period, which is based on thrust force, stator flux, and neutral point voltage difference parameters. Finally, the experimental results are validated based on a hardware-in-the-loop (HIL) system. The comparative experimental results show that compared with the traditional control methods, the proposed MPTC could significantly reduce the thrust force and neutral point voltage ripple under matched parameters. In cases of parameter mismatch, the suppressive capability of neutral point voltage remains superior to other methods.