Patent ID: 7339803

Claim:
A three-phase multiple-level inverter bridge having three branches, each branch providing one phase of the three-phase output for driving an inductive load, the multiple-level inverter bridge having “L” bus voltage levels (L≧3), wherein two of the L levels are a most-negative bus voltage and a most-positive bus voltage, any intermediate bus voltage levels being differentiated from other bus voltage levels by a difference of the most-positive bus voltage and the most-negative bus voltage, divided by (L−1), each branch comprising two half-branches, a first one-half branch comprising (L−1) switches connected in series between the most-positive bus voltage and the phase output, and a second one-half branch comprising (L−1) switches connected in series between the most-negative bus voltage and the phase output, each half branch comprising: an outermost switch of the (L−1) switches which is the switch connected to the most-positive bus voltage or the most-negative bus voltage; an innermost switch of the (L−1) switches which is the switch connected to the phase output; and if L>3, (L−3) intermediate switches of the (L−1) switches connected in series between the innermost switch and the outermost switch, wherein: each of the (L−1) switches has a transconductance, and is configured to be driven by a control signal, and each outermost switch has a lower transconductance than a transconductance of the innermost switch of the same half branch, and if L>3, each intermediate switch of a half branch has a transconductance that is no greater than that of an inner next switch in the series, connected toward the phase output, and is no less than that of an outer next switch in the series, connected toward the most-negative bus voltage or the most-positive bus voltage.