Inductive power distribution system

Abstract

Inductive power transfer across an extended gap ( 100 ) from a primary conductor ( 119 ) is provided by means of a resonant intermediate loop comprised of capacitor ( 118 ) with inductor ( 117 ) carrying a larger resonating current, that can in turn generate an inductive field to be collected by a pickup coil ( 120 ). This process and device find application in an electroluminescent advertising panel.

1 . An inductive power distribution system including: 
 a primary conductor,    a secondary resonant pick-up circuit for use in conjunction with the primary conductor, the pick-up circuit deriving at least some power from a magnetic field associated with the primary conductor,    an intermediate resonant circuit provided between the primary conductor and the pick-up circuit, the intermediate resonant circuit including inductance means and capacitance means, the magnitude of the capacitance means and the inductance means being chosen so that the intermediate resonant circuit is resonant at a substantially predetermined resonant frequency, and    the presence of the intermediate resonant circuit allowing a given quantity of power to be transferred to the pick-up circuit across a greater distance between the primary conductor and the secondary resonant pick-up than distance over which the given quantity of power can be transferred without the presence of the intermediate resonant circuit.    
     
     
         2 . The inductive power distribution system as claimed in    claim 1   , wherein the inductance means comprises an inductance which is provided as a lumped inductance.  
     
     
         3 . The inductive power distribution system as claimed in    claim 1   , wherein the inductance means comprises an inductance which is a distributed inductance.  
     
     
         4 . The inductive power distribution system as claimed in    claim 1   , wherein the inductance means comprises a lumped inductance and a distributed inductance.  
     
     
         5 . The inductive power transfer system as claimed in    claim 3   , wherein the intermediate resonant circuit comprises a single loop of conductive material and the distributed inductance comprises the inductance of the loop.  
     
     
         6 . The inductive power transfer system as claimed in    claim 4   , wherein the intermediate resonant circuit comprises a loop of conductive material, and the distributed inductance comprises the inductance of the loop, and whereby the loop includes at least one sub loop having one or more turns of the conductive material, the sub-loop comprising the lumped inductance.  
     
     
         7 . The inductive power distribution system as claimed in    claim 1   , wherein the intermediate resonant circuit includes an elongate loop of conductive material so that a plurality of secondary resonant pick-up circuits which are spaced apart from each other along the length of the elongate loop may draw power from the primary conductor via the intermediate resonant circuit.  
     
     
         8 . The inductive power transfer system as claimed in    claim 1   , wherein the intermediate resonant circuit includes current limiting means to limit the amount of resonant current flowing in the intermediate resonant circuit.  
     
     
         9 . The inductive power distribution system as claimed in    claim 8   , wherein the current limiting means includes control means for at least partially decoupling the intermediate resonant circuit from the primary conductor.  
     
     
         10 . The inductive power distribution system as claimed in    claim 1   , wherein the secondary resonant pick-up circuit is provided on an electrically powered vehicle.  
     
     
         11 . The inductive power distribution system as claimed in    claim 10   , wherein the intermediate resonant circuit comprises an elongate loop of conductive material extending over a lateral distance beneath at least a part of a route taken by the vehicle and whereby the intermediate resonant circuit provides power to the vehicle when the vehicle is located adjacent to the intermediate resonant circuit.  
     
     
         12 . The inductive power distribution system as claimed in    claim 2   , wherein more than one lumped inductance is provided within the intermediate resonant circuit and the lumped inductance provide regions of increased power transfer to one or more secondary pick-up circuits.  
     
     
         13 . The inductive power distribution system as claimed in    claim 12   , wherein the secondary pick-up circuits are provided on one or more vehicles which use the secondary pick-up circuits to charge a battery provided on each vehicle and the lumped inductances in the intermediate resonant circuit provide regions for charging the battery of each vehicle when the vehicle is located adjacent to the lumped inductance.  
     
     
         14 . The inductive power distribution system as claimed in    claim 1   , including active frequency adjusting means provided to regulate or adjust the frequency of the resonant intermediate circuit.