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Electronic controller matching engine power to alternator power and maintaining engine frequency for a free-piston stirling engine driving a linear alternator

  • US 20080122408A1
  • Filed: 11/29/2006
  • Published: 05/29/2008
  • Est. Priority Date: 11/29/2006
  • Status: Active Grant
First Claim
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1. An electrical power generating source comprising a free piston Stirling engine, including a power piston, driving a linear alternator, the alternator having an alternator winding, the power source comprising:

  • (a) a switching mode rectifier connecting the alternator winding to an electrical energy storage means and including a pulse width modulator for controlling the rectifier switching duty cycle;

    (b) a negative feedback control loop for controlling alternator current and having a command input connected to a summing junction and an output connected to the pulse width modulator for controlling the operational duty cycle of the switching mode rectifier, the current control loop having a feedback circuit comprising a current sensor connected to the alternator winding for sensing instantaneous alternator current and applying a current feedback signal to the summing junction of the current feedback control loop; and

    (c) a negative feedback control loop for controlling a voltage, Vinternal, which is the sum of the voltage induced on the alternator winding and the voltage across the lumped resistance of the alternator winding, the Vinternal control loop having a command input applied to a summing point and a feedback circuit including a sensor means connected as an input to a computing circuit, the current sensor also being connected as an input to the computing circuit, the computing circuit computing and applying a signal representing Vinternal to the feedback input of the summing point of the Vinternal control loop, the output of the Vinternal control loop being connected as the command input to the current feedback control loop.

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