Electrically operated displacement pump control system and method

A method of operating a reciprocating pump to pump a fluid, the method comprising:

• receiving, by a controller, a parameter output setting from a user, the parameter output setting corresponding to a target output parameter for the fluid output by the pump, wherein the controller is configured to regulate current to an electric motor based on the parameter output setting;
• electromagnetically applying a rotational force to a rotor of the electric motor;
• outputting, by the rotor, a rotational output to move a first fluid displacer to cause the fluid displacer to pump the fluid;
• and
• regulating, by the controller, a flow of the current to a stator of the electric motor such that the rotational force is applied to the rotor during both a pumping state and a stalled state, wherein regulating comprises delivering the flow of current to the electric motor to move the first fluid displacer to pump the fluid until a pressure of the fluid stalls the rotor while current is supplied to the electric motor by the controller so that the rotor applies torque while the rotor remains stalled, and the first fluid displacer resumes pumping when the pressure of the fluid drops enough for the rotor to overcome the stall and resume rotating;
• wherein the controller provides a first power signal having a first waveform to the electric motor while the rotor is rotating and provides a second power signal having a second waveform to the electric motor while the rotor remains stalled such that the controller switches from delivering the first waveform during pumping to delivering the second waveform during rotor stall, the first waveform different from the second waveform;
• wherein, in the pumping state the rotor rotates about a pump axis causing the first fluid displacer to move coaxially with the rotor to apply force to the fluid;
• and
• wherein in the stalled state, the rotor applies torque and does not rotate about the pump axis such that the first fluid displacer applies force to the fluid and does not move.