Patent ID: 8890361

Claim:
An electrically powered horizontal directional drilling machine comprising: a machine frame; at least one electric motor supported on the machine frame; an electric power assembly operatively connected to the electric motor, wherein the electric power assembly conditions an incoming current for use by the electric motor, the electric power assembly comprising: a plurality of inverters for converting a direct current to an alternating current; and a control unit operatively connected to each inverter wherein the control unit sends control signals to each inverter to maintain a timing relationship between the plurality of inverters, a drive system supported on the machine frame and powered by the at least one electric motor; a drill string comprising a first end and a second end; a coupling device to engage the first end of the drill string to the drive system; a downhole tool connected to the second end of the drill string; and an actuator powered by the at least one electric motor to apply thrust and retract the drill string and downhole tool.