A position detection device determines the position of the diaphragm or the drive piston of an electric-motor-driven diaphragm pump, in particular, by detecting the upper and lower reversal point (Po, Pu) in the movement curve of the diaphragm of the diaphragm pump. A diaphragm is actuated by a drive connecting rod to close a conveying chamber with valves provided on an inlet and outlet side. The volume can be changed between a minimum and maximum volume. A rotational movement of an electric motor, with a rotor, is converted into the actuation movement of the drive connecting rod via the effect of the eccentrics. The position detection device detects the load curve of the diaphragm pump during the movement of the diaphragm. An evaluation device determines at least the position of the upper and lower reversal point of the diaphragm from the load curve.

In some implementations, a controller may obtain a setting for a maximum discharge pressure associated with a fluid pump that is to be allowed during a hydraulic fracturing operation. The fluid pump may be driven by a motor that is controlled by a variable frequency drive (VFD). The controller may determine a maximum torque for the motor that achieves the maximum discharge pressure. The controller may cause, via the VFD, adjustment to a speed of the motor to maintain a torque of the motor at or below the maximum torque for the motor.

In some implementations, a controller may obtain a setting for a target discharge pressure associated with a fluid pump driven by a motor that is controlled by a variable frequency drive (VFD). The target discharge pressure may be for use in a pressure test of a system that includes the fluid pump. The controller may determine a target torque for the motor that achieves the target discharge pressure. The controller may cause, via the VFD and in connection with the pressure test, adjustment to a speed of the motor to achieve the target torque for the motor.

In some implementations, a controller may monitor, during a ramp up period of a fluid pump driven by a motor that is controlled by a variable frequency drive (VFD), an intake pressure of the fluid pump and a discharge pressure of the fluid pump. The controller may detect, based on monitoring the intake pressure and the discharge pressure, whether the intake pressure satisfies an intake pressure threshold or the discharge pressure satisfies a discharge pressure threshold. The controller may cause, via the VFD, reduction of a torque of the motor based on the intake pressure satisfying the intake pressure threshold or the discharge pressure satisfying the discharge pressure threshold.

A system, method, and computer-readable medium for determining the flow rate and fluid density in an electrical submersible pump (ESP) and controlling the ESP based on the flow rate and density. In one implementation, an ESP system includes an ESP, drive circuitry, a current sensor, a voltage sensor, and a processor. The ESP includes an electric motor. The drive circuitry is electrically coupled to the ESP and is configured to provide an electrical signal to power the ESP. The current sensor is configured to measure a current of the electrical signal. The voltage sensor is configured to measure a voltage of the electrical signal. The processor is configured to calculate speed of a shaft of the electric motor based on a frequency induced by rotation of the motor detected in the current. The processor is also configured to calculate a density of fluid in the ESP based on the speed.

A pump monitoring system may include a sensor for monitoring a parameter of a pump system. The sensor may include at least one of an ammeter in electrical communication with an electric motor driving a pump and a torque sensor on a drive shaft that drives a pump. The system may also include a controller in data communication with the sensor to receive sensor data. The controller may be configured to assess the performance of the respective pump in one or more ways. At least one of the one or more ways may include reliance on the sensor data from only one sensor to identify valve or seat wear or failure. Alternatively or additionally, at least one of the one or more ways may identify valve or seat wear or failure without reliance on pump output pressure.

A method for conveying a fluid of a fluid circuit by means of an electric motor-powered fluid pump of a motor vehicle, in particular an oil pump, wherein by means of the fluid pump a fluid pressure of the fluid circuit is adjusted to a target pressure, and wherein an actual pressure of the fluid is determined without a pressure sensor.

An air compressor includes: a motor; a compression mechanism that is driven by the motor and that is configured to generate compressed air; a tank that is configured to store the generated compressed air; a load acquisition part that is configured to acquire a load applied to the compression mechanism; and a control part that is configured to control a rotation of the motor. The control part is configured to perform control for changing a TN characteristic of the motor in response to the load of the compression mechanism acquired by the load acquisition part.

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

A control arrangement for a variable displacement pump includes a pressure control unit and a separate mechanical control unit, each mounted on a housing of the variable displacement pump. The pressure control unit provides pressure control for the variable displacement pump and the mechanical control unit provides rotary feedback control for the variable displacement pump.