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.

Controllability of a linear motor or a compressor is improved in a linear motor system that includes: an armature having magnetic poles and winding wires; a mover having a permanent magnet; and a power conversion unit that outputs AC power to the winding wires, in which the mover and the armature are relatively movable, and the mover or the armature is connected to an elastic body. The linear motor system further includes: a position detection unit that detects and outputs the position of the mover with respect to the armature, a position estimation, or a current detection unit that outputs the value of current flowing through the winding wires; and a control unit that controls the output of the power conversion unit on the basis of the output of the position detection unit, the output of the position estimation unit, or the output of the current detection unit.

A method for controlling a motor-driven pump in communication with a fluid system is provided. Preferably the method employs a frequency drive system to control the motor-driven pump. The control method is characterized in that the operating frequency of the motor can be adjusted very quickly and it is ensured to be operated in a safe frequency range no more than a rated current.

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 synthetic jet actuator includes a cavity layer having an internal cavity for reception of a fluid volume and an orifice providing a fluid communication between the cavity and an external atmosphere; an oscillatory membrane having a piezoelectric material adapted to deflect the oscillatory membrane in response to an electrical signal; and a controller configured to control delivery of electrical signals to the piezoelectric material for controlling operation of the oscillatory membrane based on input data received from one or more sources that informs on a temperature and/or performance level of a targeted objected for cooling. The actuator may further include a thermal element for affecting modified temperature control; and the actuator may be integrated into a surface of a thermally diffusive structure for dissipating heat from a thermal load.

The invention relates to a method for operating a piston pump (10) which is driven by means of a coil (1) of an electromagnet. A piston (2) of the piston pump (10) can be moved in a cylinder (3) for pumping purposes by means of the electromagnet. A voltage (U) is applied to the coil (1) during a switch-on period such that a current flows through the coil (1) and the piston (2) is accelerated, said voltage being applied by means of an actuation device (11). A time curve of an electric state variable (I, U) of the coil (1) is qualitatively detected, and the curve or a curve derived therefrom is analyzed in order to detect an impact of the piston (2) against a stop. The invention further relates to an actuation device and a piston pump.

A first main plate has a first principal surface and a second principal surface. A second main plate has a third principal surface, a fourth principal surface, and an aperture. A piezoelectric element is provided on the first main plate and vibrates the first main plate. A first frame is disposed outside an outer peripheral end of the first main plate. First connecting portions connect the first main plate and the first frame to each other. Apertures are formed between the first connecting portions and connect a space adjacent to the first principal surface and a space adjacent to the second principal surface to each other. The second frame is disposed outside an outer peripheral end of the first frame. A second connecting portion connects the first frame and the second frame to each other.

A method for controlling a motor-driven pump in communication with a fluid system is provided. Preferably the method employs a frequency drive system to control the motor-driven pump. The control method is characterized in that the operating frequency of the motor can be adjusted very quickly and it is ensured to be operated in a safe frequency range no more than a rated current.

Controllability of a linear motor or a compressor is improved in a linear motor system that includes: an armature having magnetic poles and winding wires; a mover having a permanent magnet; and a power conversion unit that outputs AC power to the winding wires, in which the mover and the armature are relatively movable, and the mover or the armature is connected to an elastic body. The linear motor system further includes: a position detection unit that detects and outputs the position of the mover with respect to the armature, a position estimation, or a current detection unit that outputs the value of current flowing through the winding wires; and a control unit that controls the output of the power conversion unit on the basis of the output of the position detection unit, the output of the position estimation unit, or the output of the current detection unit.

A linear compressor and methods of operation, for example, to control a setpoint and vary cooling capacity of the linear compressor, are provided herein. An appliance may include a linear compressor having a reciprocating piston movable in a negative axial direction toward a chamber and positive axial direction away from the chamber. The appliance may further include a motor operatively coupled to the reciprocating piston, the motor having a resting setpoint, an inverter configured to supply a variable frequency waveform to the motor, and a controller configured to control the variable frequency waveform. The controller may be configured to direct a positive DC voltage to the motor to shift the resting setpoint to increase a cooling capacity of the linear compressor.