Systems and methods are provided for improving the accuracy of fuel metering for a motor-driven fuel pump, without the need for a matched-set controller. A characterization resistor value specific to the fuel pump or motor is used to calculate a fuel pump motor speed to regulate fuel delivery to an engine.

A control system comprising: a liquid ring pump; a motor configured to drive the liquid ring pump; and a controller configured to: determine an electrical current within the motor; determine a speed of the motor; calculate a value of a function, the function being a function of the determined electrical current within the motor and the determined speed of the motor; and output one or more control signals based on the calculated value of the function.

A pump having a fluid driver disposed within the interior volume of the pump and to a method of delivering fluid from an inlet of the pump to an outlet of the pump using the fluid driver. The fluid driver includes a variable-speed and/or a variable torque prime mover and a fluid displacement assembly. The pump can be used in a fluid pumping system to provide fluid to an actuator that is operated by the fluid. At least one of a speed and a torque of the pump is controlled so as to adjust at least one of a flow and a pressure in the fluid pumping system to a desired set point, without the aid of another flow control device.

The control section controls the electric motor to be driven such that the number of revolutions becomes equal to the target number of revolutions. If the control section sets the target number of revolutions to a number of revolutions of the electric motor requested by another control section, the control section changes the number of revolutions of the electric motor at an increase rate lower than or equal to the upper limit value of the increase rate or at a decrease rate lower than or equal to the upper limit value of the decrease rate. If the control section sets the target number of revolutions to a number-of-revolutions limit value, which is determined based on the voltage of a vehicle battery, the control section is able to decrease the number of revolutions of the electric motor at a decrease rate exceeding the upper limit value.

An in-vehicle motor-driven compressor includes a temperature rise estimator configured to estimate a temperature rise of the diode based on an expected reverse current, an on-voltage of the diode, and a heat resistance of the diode. The in-vehicle motor-driven compressor further includes a rotation speed controller configured to set a rotation speed limit of the electric motor, based on the estimated temperature rise of the diode so that a temperature of the diode does not exceed a junction temperature of the diode even when the electric motor is stopped and the reverse current flows through the diode, and limit a rotation speed of the electric motor to lower than or equal to the rotation speed limit.

A system for noise and vibration management of a smoke evacuation system includes a pump that compresses air and produces a pressure differential within an airflow path. The pump may be a sealed, positive displacement pump. The system includes vibration absorption mechanisms disposed between inner and outer housings, as well as on the outside surface of the outer housing. Methods of controlling and regulating a motor of the system to preserve the lifespan of the motor and maintain consistent airflow rates throughout the smoke evacuation system include varying a supply of electrical current to the motor so that it can operate at variable performance levels. Orifices are opened and closed in order to relieve resistance pressures within the airflow path due to clogging and blockages.

Repeated cycles each consist of a pump down phase and a holding phase, wherein a start timepoint of each cycle is the timepoint when a rise in an inlet pressure of the pump is sufficiently large and the time extending between two consecutive cycle start timepoints is a cycle time. A control method includes determining a start of a next cycle during a present cycle, wherein it is preferable that the present cycle directly precedes the next cycle. The method further includes controlling the pump to accelerate to a maximum allowed speed during the holding phase of the present cycle before the start of the next cycle such that at the start of the next cycle full pump capacity is available.

A hydraulic system, for example a seal oil system, includes a hydraulic feeding pump having a motor, a hydraulic motor having a generator, a cooler and a storage tank for receiving hydraulic fluid. The hydraulic feeding pump is configured to draw hydraulic fluid from the reservoir and to direct the fluid to one or more consumers (for example mechanical seals). The hydraulic motor installed downstream of the consumer drives an electric generator. The generator can be coupled to a VFD which controls the speed of the hydraulic motor. The electric power, generated by the generator, is fed back into the power grid.

A control method includes: a detection step of: detecting a vibration amplitude of the compressor; a determination step of: determining whether the detected vibration amplitude of the compressor is greater than or equal to a predetermined threshold; and a speed adjustment step of changing a switching frequency of a frequency converter or/and modulate a frequency of the compressor if the detected vibration amplitude of the compressor is greater than or equal to the predetermined threshold. A compressor system is also provided by an embodiment. The control method and the compressor system make it convenient to know whether abnormal vibration of the compressor occurs, and can avoid the resonance frequency range.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.