High-efficiency, three-level, single-phase inverter

A method of inverting DC power to AC power with a grid-connectable inverter including first and second DC input nodes, first and second AC output nodes, first, second, third, and fourth switches, and first and second diodes, the method comprising:

• receiving DC input at the first and second DC input node;
• controlling the first, second, third, and fourth switches to create a positive current path for a positive half-cycle;
• closing the first switch and the fourth switch to create a first free-wheel current path for the positive half-cycle, wherein the first free-wheel current path includes the first AC output node, the first switch, the first diode, the fourth switch, and the second AC output node, and wherein no additional diode is connected in series with the first diode between the first and fourth switch;
• controlling the first, second, third, and fourth switches to create a negative current path for a negative half-cycle;
• and
• closing the second switch and the third switch to create a second free-wheel current path for the negative half-cycle, wherein the second free-wheel current path includes the second AC output node, the second switch, the second diode, the third switch, and the first AC output node, and wherein no additional diode is connected in series with the second diode between the second and third switch.