Abstract: Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

Abstract: Vibrations of a principal machine are reduced at the fundamental and harmonic frequencies by driving the drive motor of an active balancer with balancing signals at the fundamental and selected harmonics. Vibrations are sensed to provide a signal representing the mechanical vibrations. A balancing signal generator for the fundamental and for each selected harmonic processes the sensed vibration signal with adaptive filter algorithms of adaptive filters for each frequency to generate a balancing signal for each frequency. Reference inputs for each frequency are applied to the adaptive filter algorithms of each balancing signal generator at the frequency assigned to the generator. The harmonic balancing signals for all of the frequencies are summed and applied to drive the drive motor. The harmonic balancing signals drive the drive motor with a drive voltage component in opposition to the vibration at each frequency.

Abstract: Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

Abstract: Vibrations of a principal machine are reduced at the fundamental and harmonic frequencies by driving the drive motor of an active balancer with balancing signals at the fundamental and selected harmonics. Vibrations are sensed to provide a signal representing the mechanical vibrations. A balancing signal generator for the fundamental and for each selected harmonic processes the sensed vibration signal with adaptive filter algorithms of adaptive filters for each frequency to generate a balancing signal for each frequency. Reference inputs for each frequency are applied to the adaptive filter algorithms of each balancing signal generator at the frequency assigned to the generator. The harmonic balancing signals for all of the frequencies are summed and applied to drive the drive motor. The harmonic balancing signals drive the drive motor with a drive voltage component in opposition to the vibration at each frequency.

Abstract: A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

Abstract: A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

Abstract: An electrical power source including a free-piston Stirling engine driving an alternator to supply power through a bus to a user load and controlled by an engine/alternator controller. A bidirectional DC/DC converter is connected between a battery and the bus. The stroke of the engine piston is modulated between a maximum and a minimum stroke to maintain the bus voltage at a design nominal bus voltage (V1), and charge the battery if it is not charged, when and so long as the bus voltage does not fall below a design nominal bus voltage (V1). The Stirling engine is operated at its maximum piston stroke, and the battery is charged if it is not charged, when the bus voltage is in the range between the design nominal bus voltage (V1) and a design minimum battery charging bus voltage (V2).

Abstract: A feedback control method and circuit for inclusion in a control system of an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. An instantaneous value of a variable, Vinternal, is continuously derived from other sensed and computed parameters and used in a negative feedback control loop of the control system to control engine piston stroke in order to maintain the power produced by the engine equal to the power transferred from the engine to the alternator. Vinternal is the sum of the voltage induced on the alternator winding and the voltage across the equivalent circuit lumped resistance of the alternator winding. A switching mode rectifier connects the alternator winding to an energy storage capacitor or battery. A negative feedback, alternator current control loop has an output connected to the pulse width modulator of the switching mode rectifier and has a feedback circuit comprising a current sensor for sensing instantaneous alternator current.

Abstract: An electrical power source including a free-piston Stirling engine driving an alternator to supply power through a bus to a user load and controlled by an engine/alternator controller. A bidirectional DC/DC converter is connected between a battery and the bus. The stroke of the engine piston is modulated between a maximum and a minimum stroke to maintain the bus voltage at a design nominal bus voltage (V1), and charge the battery if it is not charged, when and so long as the bus voltage does not fall below a design nominal bus voltage (V1). The Stirling engine is operated at its maximum piston stroke, and the battery is charged if it is not charged, when the bus voltage is in the range between the design nominal bus voltage (V1) and a design minimum battery charging bus voltage (V2).

Abstract: A feedback control circuit and method for a control system used to control an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. A switching mode rectifier connects the alternator winding to an output circuit that includes an electrical energy storage means and is controlled by a pulse width modulator that controls the rectifier switching duty cycle and phase. The control system controls the pulse width modulator. The improvement computes a voltage across a virtual tuning capacitor and uses the computed voltage to control the switching mode rectifier so that the switching mode rectifier is switched in a manner that makes the alternator circuit operate as if a tuning capacitor were actually present and so that the control system controls the piston of the Stirling engine to maintain balance of the mechanical power generated by the Stirling engine and the electrical power absorbed from the engine by the alternator.

Abstract: A feedback control method and circuit for inclusion in a control system of an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. An instantaneous value of a variable, Vinternal, is continuously derived from other sensed and computed parameters and used in a negative feedback control loop of the control system to control engine piston stroke in order to maintain the power produced by the engine equal to the power transferred from the engine to the alternator. Vinternal is the sum of the voltage induced on the alternator winding and the voltage across the equivalent circuit lumped resistance of the alternator winding. A switching mode rectifier connects the alternator winding to an energy storage capacitor or battery. A negative feedback, alternator current control loop has an output connected to the pulse width modulator of the switching mode rectifier and has a feedback circuit comprising a current sensor for sensing instantaneous alternator current.

Abstract: A feedback control circuit and method for a control system used to control an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. A switching mode rectifier connects the alternator winding to an output circuit that includes an electrical energy storage means and is controlled by a pulse width modulator that controls the rectifier switching duty cycle and phase. The control system controls the pulse width modulator. The improvement computes a voltage across a virtual tuning capacitor and uses the computed voltage to control the switching mode rectifier so that the switching mode rectifier is switched in a manner that makes the alternator circuit operate as if a tuning capacitor were actually present and so that the control system controls the piston of the Stirling engine to maintain balance of the mechanical power generated by the Stirling engine and the electrical power absorbed from the engine by the alternator.

Abstract: A feedback control method and circuit for inclusion in a control system of an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. An instantaneous value of a variable, Vinternal, is continuously derived from other sensed and computed parameters and used in a negative feedback control loop of the control system to control engine piston stroke in order to maintain the power produced by the engine equal to the power transferred from the engine to the alternator. Vinternal is the sum of the voltage induced on the alternator winding and the voltage across the equivalent circuit lumped resistance of the alternator winding and a switching mode rectifier connects the alternator winding to an energy storage capacitor or battery.

Abstract: A feedback control method and circuit for inclusion in a control system of an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. An instantaneous value of a variable, Vinternal, is continuously derived from other sensed and computed parameters and used in a negative feedback control loop of the control system to control engine piston stroke in order to maintain the power produced by the engine equal to the power transferred from the engine to the alternator. Vinternal is the sum of the voltage induced on the alternator winding and the voltage across the equivalent circuit lumped resistance of the alternator winding. A switching mode rectifier connects the alternator winding to an energy storage capacitor or battery. A negative feedback, alternator current control loop has an output connected to the pulse width modulator of the switching mode rectifier and has a feedback circuit comprising a current sensor for sensing instantaneous alternator current.

Abstract: A piston position sensing circuit for sensing the instantaneous position of a piston of a free piston Stirling machine or a compressor mechanically connected to a reciprocating member of a linear electric motor or alternator. A source of a high frequency, alternating, electrical signal applies a high frequency signal to the winding circuit of the linear alternator or motor. A filter circuit is connected to the winding circuit and passes electrical signals at the frequency of the high frequency source and blocks signals at the operating frequency of reciprocation. A peak detector circuit is connected to the filter circuit and detects the peak of the filter circuit output signal to provide an instantaneous peak magnitude that is proportional to the instantaneous piston position.

Abstract: A piston position sensing circuit for sensing the instantaneous position of a piston of a free piston Stirling machine or a compressor mechanically connected to a reciprocating member of a linear electric motor or alternator. A source of a high frequency, alternating, electrical signal applies a high frequency signal to the winding circuit of the linear alternator or motor. A filter circuit is connected to the winding circuit and passes electrical signals at the frequency of the high frequency source and blocks signals at the operating frequency of reciprocation. A peak detector circuit is connected to the filter circuit and detects the peak of the filter circuit output signal to provide an instantaneous peak magnitude that is proportional to the instantaneous piston position.

Abstract: A cryocooler having two operating modes so that its operating range is broadened, its gas bearing system is maintained in an operable state and it can utilize piston stroke modulation for energy efficiency. A piston stroke modulator modulates the piston stroke when the commanded piston stroke exceeds the minimum stroke and maintains the minimum stroke when the commanded stroke is less than the minimum stroke. A heater applies heater power to the thermal load when the commanded piston stroke is less than the minimum piston stroke. A closed loop feedback control system is used which has two branches of its dynamic leg. One branch controls the modulation of the cryocooler and the second, parallel branch controls the modulation of the heater.

Abstract: The free piston cooler transient temperature control system of the present invention eliminates collisions during the transient cool-down period in a free piston cooler upon start-up. The transient temperature control system incorporates a free piston cooler, having a cold head and a warm end, a cold head temperature sensor, a relational interface, and a temperature controller. The cold head temperature sensor senses the temperature of the cold head and generates a temperature signal. The relational interface is in communication with the temperature signal and contains a predetermined relationship between the cold head temperature and a maximum piston stroke during the transient cool-down temperature range. The relational interface generates a transient range maximum allowable stroke signal from the temperature signal and the predetermined relationship.