The FIGURE is a top, front and right side perspective view of a preferred embodiment of the design of the invention. A filler material may be disposed on a top surface and a bottom surface of a stack of coil strands. The inverter is capable of deliberately regulating its ac power output to the load and lowering the lower limit of the output power through control of the intermittent operation, in which an error signal for carrying out the PWM control is reduced to zero during each off-duty period.