System and method for electrically-coupled thermal cycle

Abstract

In one embodiment according to the invention, there is provided a method for generating electrical energy using a thermal cycle of a working gas. The method comprises using the motion of a piston in a cylinder, containing the working gas performing the thermal cycle, to electromagnetically induce current in an electrical circuit coupled to the cylinder; using the electrical circuit to store the electrical energy, produced by the current induced in the electrical circuit, in an electrical storage device; and using the electrical energy stored in the electrical storage device to electromagnetically provide a motive force to the piston. Cyclically using the electrical circuit to store the electrical energy and using the stored energy to provide a motive force to the piston effect a net positive average power transfer into the electrical storage device over the course of the thermal cycle.

What is claimed is: 
     
         1 . A device for performing a thermal cycle of a working gas, the device comprising:
 at least one piston movably mounted in a cylinder to form a working chamber between the at least one piston and the cylinder, the working chamber containing the working gas performing the thermal cycle;   an electrical circuit mounted stationary relative to the cylinder, the electrical circuit being electromagnetically coupled to provide a motive force to the at least one piston;   an electronic power converter electrically connected to the electrical circuit and to an electrical bus;   an electrical storage device electrically connected to the electrical bus;   the at least one piston being movably mounted such that its motion electromagnetically induces current in the electrical circuit; and   the electronic power converter being configured to perform closed-loop electronic control of the motion of the at least one piston.   
     
     
         2 . The device according to  claim 1 , wherein the electronic power converter is configured to perform the closed-loop electronic control such that the working gas is cycled through an internal combustion cycle. 
     
     
         3 . The device according to  claim 2 , wherein the at least one piston comprises a first piston and a second piston, the working gas being between the first piston and the second piston; and wherein the electronic power converter is configured to perform the closed-loop electronic control to compress and expand the working gas between the first piston and the second piston. 
     
     
         4 . The device according to  claim 1 , wherein the cylinder comprises at least one heat transfer zone configured to be thermally coupled to an external heat source. 
     
     
         5 . The device according to  claim 4 , wherein the at least one heat transfer zone comprises a heating zone of the cylinder and a cooling zone of the cylinder, the electronic power converter being further configured to perform the closed-loop electronic control to move the working gas along the cylinder to effect successive heat transfer of the working gas across the wall of the heating zone of the cylinder and across the wall of the cooling zone of the cylinder, such that heat is not directly transferred between the heating zone of the cylinder and the cooling zone of the cylinder when the working gas is moved past and away from each of the heating zone of the cylinder and the cooling zone of the cylinder. 
     
     
         6 . The device according to  claim 5 , wherein the at least one heat transfer zone further comprises a neutral zone of the cylinder, the electronic power converter being further configured to perform the closed-loop electronic control to move the working gas between the heating zone of the cylinder, the cooling zone of the cylinder and the neutral zone of the cylinder. 
     
     
         7 . The device according to  claim 1 , wherein the electrical circuit comprises a set of windings coupled to the cylinder, and wherein the at least one piston comprises a first piston and a second piston, a first permanent magnet being attached to the first piston and a second permanent magnet being attached to the second piston. 
     
     
         8 . The device according to  claim 1 , wherein the at least one piston comprises a first piston and a second piston, the first piston and the second piston being mounted around a common centering shaft. 
     
     
         9 . The device according to  claim 1 , wherein the at least one piston comprises a first piston and a second piston, at least part of the shaft of the first piston moving concentrically within a shaft of the second piston. 
     
     
         10 . The device according to  claim 1 , further comprising a second device according to  claim 1 , the second device comprising a second cylinder operated in axial opposition to the cylinder. 
     
     
         11 . The device according to  claim 1 , further comprising a second device according to  claim 1 , a third device according to  claim 1 , and a fourth device according to  claim 1 , the second device comprising a second cylinder, the third device comprising a third cylinder, and the fourth device comprising a fourth cylinder, the cylinder, second cylinder, third cylinder, and fourth cylinder being operated in a bundle with parallel axes of the cylinders, two of the cylinders being operated antiparallel to the other two cylinders of the cylinder, second cylinder, third cylinder, and fourth cylinder. 
     
     
         12 . The device according to  claim 1 , further comprising a mechanical hard stop configured to hold the at least one piston in place during a stationary portion of the thermal cycle. 
     
     
         13 . The device according to  claim 12 , wherein the mechanical hard stop is selected from the group consisting of a mechanical barrier, a permanent magnet and a magnetic pole, the mechanical hard stop being attached to at least one of the cylinder and the at least one piston. 
     
     
         14 . The device according to  claim 1 , wherein the electronic power converter is configured to control timing of the thermal cycle by the control of the motion of the at least one piston. 
     
     
         15 . The device according to  claim 1 , wherein the electronic power converter is configured to perform the closed-loop control based on electrical signals related to the state of the working gas. 
     
     
         16 . The device according to  claim 15 , further comprising at least one of a temperature sensor, a pressure sensor, and a position sensor configured to deliver the electrical signals related to the state of the working gas to the electronic power converter. 
     
     
         17 . The device according to  claim 1 , wherein the electronic power converter is configured to perform the closed-loop control such that when a point of maximum compression of the working gas has been reached, an inlet valve and an outlet valve of the cylinder have been bypassed by the at least one piston. 
     
     
         18 . The device according to  claim 1 , wherein the device is for generating electrical energy using the thermal cycle of the working gas, and wherein the electronic power converter is configured to effect a net positive average power transfer from the working gas to the electrical bus over the course of the thermal cycle. 
     
     
         19 . The device according to  claim 1 , wherein the device is for pumping heat using electrical energy, and wherein the electronic power converter is configured to effect a net positive average power transfer from the electrical bus to the working gas over the course of the thermal cycle.