Even when abnormal heat generation occurs during operation in a state where the temperature of a compressor is not increased, abnormality cannot be detected. A fluid machine includes a fluid machine body; a motor that drives the fluid machine body; a temperature sensor that measures a temperature of the fluid machine body; and a control unit that controls the fluid machine body. The control unit changes a temperature threshold value based on at least one of a pressure of a fluid discharged by the fluid machine body and a frequency of a voltage input into the motor, and issues a notification when the temperature of the compressor body measured by the temperature sensor exceeds the temperature threshold value.

A controller for controlling a frequency inverter of a positive displacement pump motor of a positive displacement pump. The controller comprises a control unit configured to produce a control variable (Ys) for a frequency inverter of a positive displacement pump motor depending on a reference variable (W) and a first actual operating parameter (X). According to the invention, the control unit is associated with logical means having a first threshold value defining means that are designed to determine at least one first threshold value (YGrenzmax, YGrenzmin) depending on the first actual operating parameter (X) and/or at least one further actual operating parameter (XH, YH, YHH) that could lead to a failure state of the positive displacement pump when exceeded or fallen short of.

An apparatus and method for controlling an electric oil pump with a pump control signal generated by an electronic control unit (ECU) of a vehicle. The pump control signal has a variable drive time portion during which the electric oil pump is actuated to supply oil to an engine of the vehicle and a variable cycle time defining a frequency of the pump control signal.

A system for circulating a liquid which comprises at least one pump, connectable to at least one pipe for the flow of a liquid and driven by at least one electric motor; sensors being provide for sensing at least two electrical parameters correlated with the operation of the electric motor and a processor which is functionally connected to the sensors and configured to determine, based on the signals provided by the sensors, at least one fluid-dynamic parameter correlated with the flow of the liquid through the pipe.

The present invention provides a method and system for providing on-site electrical power to a fracturing operation, and an electrically powered fracturing system. Natural gas can be used to drive a turbine generator in the production of electrical power. A scalable, electrically powered fracturing fleet is provided to pump fluids for the fracturing operation, obviating the need for a constant supply of diesel fuel to the site and reducing the site footprint and infrastructure required for the fracturing operation, when compared with conventional systems.

A power conversion circuit board (1) is a board on which a power conversion circuit which converts direct current to alternating current is mounted. A low voltage circuit (10b) to which a low voltage is applied and a high voltage circuit (10a) to which a high voltage is applied are separately disposed in different areas on the same board surface. Further, the high voltage circuit (10a) includes a bus bar in which a part of a wiring is formed on the board surface and another wiring is provided with a predetermined distance from the board surface.

A solvent supply system for supplying a composite solvent is described. The solvent supply system comprises a first supply flow path with a first pump unit, the first supply flow path being adapted for supplying a flow of a first solvent to a mixing unit, the first pump unit operating periodically, and a second supply flow path with a second pump unit, the second supply flow path being adapted for supplying a flow of a second solvent to the mixing unit, the second pump unit operating periodically. The mixing unit is adapted for mixing the first and the second solvent and for supplying a composite solvent. The solvent supply system further comprises a control unit adapted for controlling operation of the first and the second pump unit, the control unit being adapted to prevent at least one of a predefined phase relation and a predefined frequency relation between the first pump unit and the second pump unit.

A system and method for a compressor includes a compressor connected to a condenser, a discharge line temperature sensor that outputs a discharge line temperature signal corresponding to a discharge line temperature of refrigerant leaving the compressor, and a control module connected to the discharge line temperature sensor. The control module determines a saturated condenser temperature, calculates a discharge superheat temperature based on the saturated condenser temperature and the discharge line temperature, and monitors a flood back condition of the compressor by comparing the discharge superheat temperature with a predetermined threshold. The control module increases a speed of the compressor when the discharge superheat temperature is less than or equal to the predetermined threshold.

A method is provided for braking a compressor of a refrigeration appliance, of an air conditioning appliance or of a heat pump in which the compressor has a brushless motor with windings and a controller for braking the motor. The controller is configured to brake the brushless motor by using a braking current in a controlled manner starting from an operating rotational speed, in which the braking current during the controlled braking is dependent on induced voltages determined before the controlled braking. The method for braking includes rotating the motor at an operating rotational speed, receiving a signal for decelerating, braking or slowing down, determining voltages induced in the windings and supplying a braking current having a decreasing frequency to the windings, in which the braking current during the braking is dependent on the previously determined induced voltages. A compressor and a refrigeration appliance having the compressor are also provided.

An apparatus and associated method for operating a pump. A flow controller executes computer instructions stored in memory that define a selected flow rate of the fluid flowing out of the pump based on a flow profile trajectory stored in memory and related to a parameter of the fluid. A motor controller executes computer instructions stored in memory that map the selected flow rate to a selected motor speed via a transformation function stored in memory, and that operate the motor at the selected motor speed.