Dc link charging of capacitor in a wireless power transfer pad

Abstract

An apparatus for wireless power transfer may be configured to receive power wirelessly and to output power to a load. The apparatus may include a wireless power transfer pad configured to receive power wirelessly. The apparatus may include a secondary circuit having a rectification section arranged to receive alternating current from the wireless power transfer pad and output rectified current to the load via a positive bus. The rectification section may include a first rectification device connected to the positive bus. The rectification section may include a capacitor connected between the first rectification device and a negative bus connected to the rectification section and arranged for connection to the load. Other examples may be described and claimed.

What is claimed is: 
     
         1 . An apparatus for wireless power transfer, the apparatus configured to receive power wirelessly and to output power to a load, the apparatus comprising:
 a wireless power transfer (“WPT”) pad configured to receive power wirelessly; and   a secondary circuit that includes:
 a rectification section arranged to receive alternating current from the WPT pad and output rectified current to the load via a positive bus; 
 a first rectification device connected to the positive bus; and 
 a capacitor connected between the first rectification device and a negative bus connected to the rectification section and arranged for connection to the load. 
   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 a second rectification device connected between the rectification section and an intermediate node between the first rectification device and the capacitor.   
     
     
         3 . The apparatus of  claim 2 , wherein:
 the first rectification device is forward biased between the positive bus and the capacitor; and   the second rectification device is forward biased between the rectification section and the intermediate node.   
     
     
         4 . The apparatus of  claim 2 , wherein the second rectification device includes a charging diode. 
     
     
         5 . The apparatus of  claim 2 , wherein the second rectification device includes first and second diodes forward biased in parallel between the rectification section and the intermediate node. 
     
     
         6 . The apparatus of  claim 1 , wherein the first rectification device includes a blocking diode. 
     
     
         7 . The apparatus of  claim 1 , wherein the secondary circuit further includes a tuning section that has one or more of an inductor and a capacitor, the tuning section connected between the WPT pad and the rectification section. 
     
     
         8 . An apparatus for wireless power transfer, the apparatus configured to receive power wirelessly and to output power to a load, the apparatus comprising:
 a wireless power transfer (“WPT”) pad configured to receive power wirelessly; and   a secondary circuit that includes:
 a full-bridge rectifier arranged to receive alternating current from the WPT pad and output rectified current to the load via a positive bus; 
 a first impedance device connected to the positive bus; and 
 a capacitor connected between the first impedance device and a negative bus connected to the full-bridge rectifier and arranged for connection to the load. 
   
     
     
         9 . The apparatus of  claim 8 , further comprising:
 a second impedance device connected between the full-bridge rectifier and an intermediate node between the first impedance device and the capacitor.   
     
     
         10 . The apparatus of  claim 9 , wherein:
 the first impedance device has a diode-type function and is forward biased between the positive bus and the capacitor; and   the second impedance device has a diode-type function and is forward biased between the full-bridge rectifier and the intermediate node.   
     
     
         11 . The apparatus of  claim 9 , wherein:
 the second impedance device includes a first charging diode and a second charging diode;   the full-bridge rectifier includes two series-connected diodes in a first leg connected between the positive bus and the negative bus and two series-connected diodes in a second leg connected between the positive bus and the negative bus;   an anode of the first charging diode is connected between the two series-connected diodes of the first leg; and   an anode of the second charging diode is connected between the two series-connected diodes of the second leg.   
     
     
         12 . The apparatus of  claim 8 , wherein the secondary circuit further comprises a tuning section comprising one or more of an inductor and a capacitor, the tuning section connected between the WPT pad and the full-bridge rectifier. 
     
     
         13 . The apparatus of  claim 8 , wherein:
 the WPT pad comprises one or more capacitors in series with one or more windings of the WPT pad; and   the WPT pad is a secondary WPT pad configured to receive power transferred wirelessly from a primary WPT pad across a gap between the primary and secondary WPT pads.   
     
     
         14 . A system for wireless power transfer, comprising:
 a power converter apparatus that includes a primary wireless power transfer (“WPT”) pad configured to transfer power wirelessly; and   a secondary apparatus having a secondary WPT pad configured to receive power wirelessly from the primary WPT pad across a gap therebetween and to output power to a load, the secondary apparatus configured to be mounted to a vehicle and including:   a secondary circuit that includes:
 a rectification section arranged to receive alternating current from the WPT pad and output rectified current to the load via a positive bus; 
 a first rectification device connected to the positive bus; 
 a capacitor connected between the first rectification device and a negative bus connected to the rectification section and arranged for connection to the load; and 
 a second rectification device connected between the rectification section and an intermediate node between the first rectification device and the capacitor. 
   
     
     
         15 . The system of  claim 14 , wherein:
 the first rectification device is forward biased between the positive bus and the capacitor; and   the second rectification device is forward biased between the rectification section and the intermediate node.   
     
     
         16 . The system of  claim 14 , wherein the second rectification device includes a charging diode. 
     
     
         17 . The system of  claim 14 , wherein the second rectification device includes first and second diodes forward biased in parallel between the rectification section and the intermediate node. 
     
     
         18 . The system of  claim 14 , wherein the secondary WPT pad includes one or more capacitors in series with one or more windings of the secondary WPT pad. 
     
     
         19 . The system of  claim 14 , wherein the first rectification device includes a blocking diode. 
     
     
         20 . The system of  claim 14 , wherein the secondary circuit further includes a tuning section that has one or more of an inductor and a capacitor, the tuning section connected between the secondary WPT pad and the rectification section.