基于级联多模块的永磁同步电机驱动系统传导EMI建模与预测

With the increase of the switching frequency of semiconductor devices, conducted electromagnetic interference (EMI) problems in pulse width modulation (PWM) based motor drive system become more serious. The components of this system, such as filters, cables, motors, and motor drive units, are typically cascaded in practical applications. Meanwhile, in system-level EMI modeling, it is not necessary to acquire complete EMI information for each branch/node. Taking these factors into account, this work proposed a modular EMI modeling method based on the cascaded matrix T. The interference source was established by using the substitution theorem to consider the PWM switching behavior in ac motor drive system. Besides, the impedance of each part was represented by a two-port network "black box", and the matrix T was utilized to describe these units to avoid the problem that the matrix Z cannot be directly applied to the cascade system. Furthermore, the cascaded units can be modularly split without any theoretical approximations since they were not bound by EMI standards, and matrix T based calculation was employed to simplify it. Theoretical analysis shows that when filter units are added or changed in the EMI optimization processing, only the relevant cascaded matrix T has to be divided and recalculated in the EMI prediction. Finally, a permanent magnet synchronous motor (PMSM) drive system was employed to analyze and verify the proposal, and the experimental comparison results suggest that the model proposed has the advantages of modularity and low complexity.