A linear compressor includes, a cylinder, a piston configured to reciprocate inside the cylinder, a motor configured to supply driving force to the piston, a detector configured to detect a motor current and a motor voltage that are applied to the motor, and a controller configured to estimate a stroke of the piston based on the motor current and the motor voltage and to determine a phase difference between the stroke and the motor current. The controller is configured to detect operation information of the linear compressor, determine whether to perform a resonance operation based on the operation information, and control operation of the motor to allow the phase difference to be within a preset phase range.

Provided are a linear compressor and a linear compressor control system that do not require a sensor for detecting a position of a mover, and can compute a mover position with high accuracy, in consideration of position dependency of an induced voltage constant. A linear compressor 20 includes a field element 11 having a first end connected to elastic bodies (201a and 201b) and including a permanent magnet 111, an armature 12 having a winding 122 wound around a magnetic pole 121, and a linear motor 10 that causes the field element 11 and the armature 12 to reciprocate relatively in an axial direction. A stroke of a piston is controlled so that a portion where a gradient of an induced voltage when the induced voltage computed on the basis of a voltage command value output to the linear motor 10 and a value of a current flowing through the winding 122 is at a predetermined value is within a predetermined range corresponds to a top dead center and/or a bottom dead center of a stroke of a piston 212 connected to a second end of the field element 11.

A linear compressor includes a cylinder, a piston, a linear motor configured to drive the piston, a current detection unit configured to sense a current in the linear motor, a relay configured to change an operation mode of the linear motor, and a control unit configured to set at least one parameter for determining a stroke of the piston according to the operation mode. The control unit is configured to: determine a first magnitude of a first current in the linear motor based on a state of the relay being in a first state, determine a second magnitude of a second current in the linear motor based on the relay being switched to a second state from the first state, compare the first magnitude to the second magnitude, and based on the comparison of the first magnitude to the second magnitude, determine whether the relay fails to operate.

Adaptive control of a Free Piston Mover (1, 19), wherein a Control Parameter Set (COPS′) for closed loop control of a Target Control Variable (CV.sub.t) is adapted using a Future-Stroke Controller (20) to respond to Input Demand (21) signals whilst ensuring a sufficient current control margin and compensating for system changes over time. The Control Parameter Set (COPS′) is transmitted to an In-Stroke Controller (23) in advance of the start of a stroke to be controlled, and the In-Stroke Controller (23) transmits a Current Demand (Qt) to a Current Controller (25) of the Free Piston Mover (119).

Disclosed is a method for managing a piston pump using a computer of a vehicle, the pump including a guide, a piston slidably mounted in the guide, and a solenoid, suitable for moving the piston, the method including, as long as the fuel pressure in the compression chamber of the pump is below a predetermined pressure threshold, a step of the computer controlling the solenoid in order to move the piston to its high position, and a step of the computer detecting that the predetermined pressure threshold has been exceeded when the current value, measured after a predetermined period, is greater than or equal to a predetermined reference value so that the computer ceases to control the solenoid.

A driving device includes a voltage regulation circuit, a driving signal generation circuit, a current limiting circuit, and a voltage control circuit. The voltage regulation circuit regulates a power supply voltage and outputs a driving voltage. The driving signal generation circuit generates a driving signal to a piezoelectric element of a piezoelectric pump by using the driving voltage. The current limiting circuit limits a driving current corresponding to the driving voltage to a specified current or less, and generates a current control voltage. The voltage control circuit limits the driving voltage based on the current control voltage.

A pulsatile fluid pump system for driving a fluid pump assembly includes a reciprocating linear motor having a magnet and a coil, the magnet moving in relation to the coil, the coil having an electrical input. The pulsatile fluid pump system further includes a controller system having an electrical output coupled to the electrical input of the coil, and the controller system is configured to execute a waveform program defining an electrical waveform at the electrical output. The waveform program is configured to control operation of the linear motor by modification of a feature, selected from the group consisting of amplitude, frequency, shape, and combinations thereof, of the electrical waveform at the electrical output. The waveform program is further configured to accept a set of user-specifiable parameters defining the performance of the linear motor and to modify the electrical waveform in response to such parameters.

A linear compressor includes a cylinder, a piston disposed in the cylinder and reciprocating along an axis of the cylinder, a stator core disposed outside the cylinder, a coil winding body that is disposed in the stator core and includes first to fourth coils that are spaced from each other in a circumferential direction, a mover connected to the piston and reciprocating along the axis by an electromagnetic interaction with the coil winding body, and a switch unit configured to connect the first and second coils and the third and fourth coils in series or in parallel depending on a magnitude of a load. The first and second coils are connected in series, and the third and fourth coils are connected in series. The first to fourth coils each have the same inductance.

A control system may include circuitry configured to: a deterioration level estimation unit configured to estimate deterioration levels of pumping devices based on information about driving forces of the pumping devices; a selection unit configured to select a pumping device from the pumping devices based on a comparison of the estimated deterioration levels estimated by the deterioration level estimation unit; and a pumping control unit configured to control the selected pumping device selected by the selection unit to pump fluid.

An oscillating positive displacement pump with at least one mobile part arranged to be movable relative to a fixed part. The mobile part is driven and drives a displacement element of the positive displacement pump. An electrodynamic drive is provided as a drive, on which a plurality of coils and permanent magnets are provided that are arranged on the mobile part of the drive respectively, and at least one guide member is provided on the drive, which allows the mobile part to move only along a degree of translation freedom. The positive displacement pump is designed as a diaphragm pump, which is associated with a measurement and control unit with a data storage and data processor, which processes a position signal of the mobile part and the strength of the drive current as a measured and/or control variable. An arrangement of a plurality of such positive displacement pumps and a method of operating at least one such oscillating positive displacement pump are also provided.