Large-capacity power electronic equipment manufacured with standard modular schemes has many advantages

such as simple processing

convenient assembly and capacity expansion. Whereas

in the dc-link busbar structure

the abnormal resonant current leads to thermal failure and insulation problems of capacitors and other components. Due to the complex characteristics of the dc-link impedance network

it is difficult for the existing numerical calculation and instrument testing method to perform the specific resonance suppression

and the improvement effect is limited. In order to solve these problems

a method for extracting the resonance characteristics of high order impedance network is proposed in this paper. The method is based on the structural symmetry of standard power modules and the resonance characteristics inheritance relation between the low order unit and its combined network. Firstly

the unit selection strategy and the relation in the resonant modes between the unit and its combined network are described in detail. Then

the resonant modes of the network are decomposed into the resonant modes of the unit itself and the resonant modes accompanied with the network. The formation rule

the extraction method

the parameters

such as peak damping coefficient of the two kinds of resonant modes

are derived and analyzed in detail. Finally

the effectiveness of the proposed method is verified by experiments. The results show that a complete set of multi-resonant modes of high-order busbar impedance network can be obtained by this method. Besides

the corresponding relationship between the resonant modes and the resonant circuits in the impedance network is an important basis to guide busbar optimization design.