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In order to reduce the switching frequency involved in the traditional three-level model predictive control utilized for permanent magnet synchronous motors(PMSMs), a model predictive torque control scheme associated with the switching frequency optimization is proposed. Firstly, the reason for higher switching frequency in the three-level drive system is analyzed in depth. Then, the vector screening strategy considering switching state restriction is introduced and the switching frequency constraint is constructed in the cost function, which can effectively reduce the switching frequency as well as decrease the number of candidate vectors. Furthermore, the neutral potential is balanced in terms of the opposite effect of positive and negative redundant small vectors on neutral potential. Finally, the validity of the control strategy is verified by the simulation and experiment. The simulated and experimental results prove that the switching frequency of the proposed control strategy is reduced by nearly half of that in traditional strategy;meanwhile, the fluctuation of neutral potential is eliminated.

To investigate the blast resistance of point-supported glass curtain wall, a series of site blast tests were conducted, considering two types of glass thicknesses and different TNT charges from 0. 4 kg to 30 kg. The overpressure and displacement were measured and the failure mode was observed. The tests show the following results. The overpressure suddenly increases and quickly decays within a few milliseconds. The displacement response of the glass curtain wall increases with the increase of TNT charge. The increase of the glass thickness reduces the displacement response of the point-supported glass curtain wall. The failure mode is the tearing off of PVB at the support of the laminated glass panel while the glass shards still adhere to the PVB. Nonlinear dynamic finite element simulation of the blast tests show that, the difference of displacement response obtained by finite element analysis and blast test is less than 35%, severe stress concentration exists at the rim of support hole and finally causes the failure at the support hole, which agrees with the failure mode observed from the blast test. [ABSTRACT FROM AUTHOR]