first and second networks of switching devices , each of which are an insulated gate bipolar transistor with an intrinsic reverse - biased clamping diode , are controlled to selectively connect a sinusoidal input voltage and an output to different nodes within a series of capacitors during different portions of input and output voltage cycles to produce a stepped sinusoidal output voltage . the topology requires a low part count , produces relatively low harmonics without filtering when powering artificial lift equipment within a borehole , and scales up to medium voltages without a step - up transformer . during variable speed operation of the lift equipment , optimized switching angles for controlling the switching devices during the voltage cycles may be selected based on modulation producing the desired speed and phase measurements .