Abstract: This disclosure discloses a control unit comprising a plurality of controllers, each controller having a bus bar portion having: a left and a right bus bar holder; an upper and an lower common bus bar; an upper and an lower rotating bus bar; a upper and a lower connecting body; wherein each bus bar holder has protrusions forming a gap, the upper and the lower rotating bus bar are configured to be changed between a first mode that the upper and the lower rotating bus bar engages rotatably with the left bus bar holder, and a second mode that the upper and the lower rotating bus bar are tightened and secured to the left bus bar holder, and the upper and the lower rotating bus bar of one controller in the second mode is connected in close contact with the upper and the lower common bus bar of another controller.