Patent ID: 6995609

Claim:
A switching circuit comprising: N (N is an integer of at least 2) switching circuit units, each having first to fourth switching elements connected in a loop in this order, and a DC power source, one end of which is connected to a node between said first and fourth switching elements, and the other end of which is connected to a node between said second and third switching elements, wherein a node between said first and second switching elements in said switching circuit unit on the n-th stage (n is from 2 to N) is connected to a node between said third and fourth switching elements in said switching circuit unit on the (n−1)th stage, a node between said first and second switching elements in said switching circuit unit on the first stage is connected to one terminal of a load, and a node between said third and fourth switching elements in said switching circuit unit on the N-th stage is connected to the other terminal of the load, said first and third switching elements in all of said switching circuit units are switched on or off in response to a first on-off control signal, and said second and fourth switching elements in all of said switching circuit units are switched on or off in response to a second on-off control signal, which is in a complementary relation with said first on-off control signal, and said DC power source in each of said switching circuit units comprises respective secondary windings in a transformer having one primary winding to which AC power is applied and N secondary windings, and rectifying and smoothing means for rectifying and smoothing induced electromotive voltage of the secondary windings.