A system comprising an external circuit and a component structure configured to connect a power module and the external circuit, the component structure comprising: a first bus bar (410, 710, 1310), having one end extending to a first plane to form a first connecting terminal (415, 715, 1315); and a second bus bar (420, 720, 1320), comprising a front portion of the second bus bar (421, 721, 1321) and a rear portion of the second bus bar (422, 722, 1322), wherein the front portion of the second bus bar is laminated in parallel with the first bus bar, and the rear portion of the second bus bar is extended to a second plane to form a second connecting terminal (425, 725, 1325); wherein the external circuit comprises a third bus bar (430, 730, 1330), one end of the third bus bar (430, 730, 1330) is provided with an input terminal (445, 1335) stacked and connected with the second connecting terminal (425, 1325), and another end of the third bus bar (430, 730, 1330) is provided with an output terminal (435, 735), wherein the third bus bar is settled in parallel with the rear portion of the second bus bar, thereby reducing a parasitic inductance between the first connecting terminal and the second connecting terminal; wherein the first connecting terminal (415, 715, 1315) overlaps the second bus bar (420, 720, 1320); wherein the system is characterized in that, the output terminal (435, 735) is stacked and connected with the first connecting terminal (415, 715), wherein the component structure and the external circuit are positioned such that a current of the external circuit successively flows through the third bus bar (430, 730, 1330), the output terminal (435, 735), the first connecting terminal (415, 715, 1315), the first bus bar (410, 710, 1310), the power module, the front portion of the second bus bar (421, 721, 1321), the rear portion of the second bus bar (422, 722, 1322), the second connecting terminal (425, 725, 1325), and the input terminal (445, 1335), and flows into the external circuit, wherein a conducting direction of said current in the rear portion of the second bus bar is in parallel with that of the third bus bar, and is opposite to that of the third bus bar. a first bus bar (410, 710, 1310), having one end extending to a first plane to form a first connecting terminal (415, 715, 1315); and a second bus bar (420, 720, 1320), comprising a front portion of the second bus bar (421, 721, 1321) and a rear portion of the second bus bar (422, 722, 1322), wherein the front portion of the second bus bar is laminated in parallel with the first bus bar, and the rear portion of the second bus bar is extended to a second plane to form a second connecting terminal (425, 725, 1325); wherein the external circuit comprises a third bus bar (430, 730, 1330), one end of the third bus bar (430, 730, 1330) is provided with an input terminal (445, 1335) stacked and connected with the second connecting terminal (425, 1325), and another end of the third bus bar (430, 730, 1330) is provided with an output terminal (435, 735), wherein the third bus bar is settled in parallel with the rear portion of the second bus bar, thereby reducing a parasitic inductance between the first connecting terminal and the second connecting terminal; wherein the first connecting terminal (415, 715, 1315) overlaps the second bus bar (420, 720, 1320); wherein the system is characterized in that, the output terminal (435, 735) is stacked and connected with the first connecting terminal (415, 715), wherein the component structure and the external circuit are positioned such that a current of the external circuit successively flows through the third bus bar (430, 730, 1330), the output terminal (435, 735), the first connecting terminal (415, 715, 1315), the first bus bar (410, 710, 1310), the power module, the front portion of the second bus bar (421, 721, 1321), the rear portion of the second bus bar (422, 722, 1322), the second connecting terminal (425, 725, 1325), and the input terminal (445, 1335), and flows into the external circuit, wherein a conducting direction of said current in the rear portion of the second bus bar is in parallel with that of the third bus bar, and is opposite to that of the third bus bar.