In order to improve the simulation speed

in the large-scale AC/DC power grid simulation

the details of the action of the power electronic switch inside the converter are usually ignored

and the external characteristics of the converter are focused on. The dynamic phasor（DP） and the shifted frequency analysis（SFA） are often used to model the external characteristics of the converter. The DP performs time-variant Fourier frequency decomposition and frequency shift on the signal to reduce the signal frequency

which can increase the simulation step size. However

due to the harmonic truncation error

the model accuracy is low. The SFA is only applicable to narrow-band signals and not suitable for wide-frequency domain EMT simulation. In order to solve the contradiction between simulation accuracy and speed

the multi-frequency band dynamic phasor（MFBDB） model of line-commuted converter（LCC） converter was established to improve the accuracy and increase the simulation step. Firstly

an improved switching function model of LCC was introduced to include the asymmetry of AC system. Then a coupled and decoupled MFBDP model of LCC were derived respectively. The decoupled MFBDP model can be applied to parallel EMT simulation with multi-core CPU. Finally

an example was given to verify the validity of the MFBDP LCC dynamic phasor model.