The Study Of Four Phase Parallel Asymmetric Coupled Inductor

Based on the structural characteristics of four-phase parallel asymmetric coupled inductor,this paper analyzes working characteristics of the coupled inductor in Buck working mode for interleaving and magnetic integrated bi-directional DC converter.The duty cycle is analyzed at0<D<1/4,and the expression of the equivalent inductance is also obtained.Then,the steady-state equivalent inductance and transient equivalent inductance which affect the output performance under the steady-state and transient-state are analyzed,and the relationship between the coupling coefficient and the equivalent inductance is also established.Taking the converter's steady-state performance and transient-state performance as the goal at the same time,this paper gives the design method of the four-phase parallel asymmetric coupled inductors.The Boost working mode has the same analysis method and using the same design method as the Buck mode.Then,a four-phase ladder-shaped coupled inductor is proposed.The establishment of the equivalent circuit model and magnetic circuit model are based on the distribution of magnetic flux.And the magnetic circuit model is optimized on the basis of the established preliminary magnetic circuit model.The relationships between inductor's size,air gap and self-inductance,leakage inductance are also obtained.By using simulation and experiment,the validity of the theoretical analysis is verified.It is proved that the optimized magnetic circuit model has higher accuracy,and can be used to design the coupled inductors' dimension more accurately.Finally,in order to prove the ladder-shaped inductor performance better,the experiment compared to Pulse of the other two similar structure of the inductor.The conclusion is that the ladder-shaped inductor has a higher degree of symmetry,which can effectively reduce the current ripple,improve the efficiency of the converter and so on.