Fully clamped coupled inductors in power conversion circuits

A fully clamped coupled inductor power conversion circuit formed by applying an improvement method to a unclamped coupled inductor power conversion circuit, wherein said unclamped coupled inductor power conversion circuit has at least two operating states, and wherein said unclamped coupled inductor power conversion circuit comprises at least a first coupled inductor having at least a first winding and a second winding, a first inductance connected in series with said first coupled inductor, a second coupled inductor having at least a first winding and a second winding, wherein said first winding of said first coupled inductor and said first winding of said second coupled inductor are connected in a series combination, a second inductance connected in series with said second coupled inductor, and first switch means, wherein said series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor is unclamped in one of said operating states of said unclamped coupled inductor power conversion circuit, said improvement method comprising the following steps,

• Step (1):
• adding an active clamp network such that said active clamp network is coupled to said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor, said active clamp network comprising,
• second switch means, wherein said second switch means are placed in a conducting state during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor was unclamped and wherein said second switch means are placed in a non-conducting state during all other operating states, and
• a capacitor coupled to said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor through said second switch means during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor was unclamped,
• Step (2):
• repeating step (1) for each of said operating states of said unclamped coupled inductor power conversion circuit until said series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor is clamped during all of said operating states,
• Step (3):
• adding an active clamp network such that said active clamp network is coupled to an unclamped second winding of said first coupled inductor, if there exists an unclamped second winding of said first coupled inductor, or coupled to an unclamped second winding of said second coupled inductor, if there exists an unclamped second winding of said second coupled inductor, said active clamp network comprising,
• third switch means, wherein said third switch means are placed in a conducting state during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped second winding was unclamped and wherein said third switch means are placed in a non-conducting state during all other operating states, and
• a capacitor coupled to said unclamped second winding through said third switch means during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped second winding was unclamped,
• Step (4):
• repeating step (3) for each of said second windings and each of said operating states of said unclamped coupled inductor power conversion circuit until all of said second windings are clamped during all of said operating states,
• whereby said fully clamped coupled inductor power conversion circuit becomes fully clamped by application of said improvement method to said unclamped coupled inductor power conversion circuit thereby eliminating ringing and over shoot associated with said inductances.