Lossless commutation during operation of a power converter

Abstract

A method for operating a DC-DC converter. The method comprises: matching, based on a turns ratio of a transformer of the DC-DC converter, a primary side capacitance of the DC-DC converter and a secondary side capacitance of the DC-DC converter to result in a matched capacitance; and operating the DC-DC converter with at least one operating parameter set to cause a primary current to oscillate between a peak value and zero such that a valley of the primary current coincides with a zero crossing of a secondary switching element voltage.

1 .- 20 . (canceled) 
     
     
         21 . Apparatus for power conversion, comprising:
 a power conversion circuit having a switching voltage that has no overshoot.   
     
     
         22 . The apparatus of  claim 21 , wherein the power conversion circuit comprises:
 a transformer having a primary winding and a secondary winding; and   a current control switch coupled to the transformer for controlling current flow through the primary winding, wherein (i) a primary capacitance of the power conversion circuit and a secondary capacitance of the power conversion circuit are matched, and (ii) at least one operating parameter of the power conversion circuit is based on the matched capacitance such that the switching voltage has no overshoot, wherein the switching voltage is the drain-source voltage of the current control switch.   
     
     
         23 . The apparatus of  claim 22 , further comprising a secondary-side switching element coupled to the secondary winding, wherein the at least one operating parameter is set to cause a primary current waveform to have a value of zero and a slope of zero when a voltage of the secondary-side switching element has a zero-crossing. 
     
     
         24 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a DC-DC converter. 
     
     
         25 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a flyback converter. 
     
     
         26 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a boost converter. 
     
     
         27 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a buck-boost converter. 
     
     
         28 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a forward converter. 
     
     
         29 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a full-bridge converter. 
     
     
         30 . The apparatus of  claim 21 , wherein the power conversion circuit is part of a DC-AC inverter. 
     
     
         31 . The apparatus of  claim 23 , wherein the primary capacitance comprises a first parasitic capacitance of the current control switch and the secondary capacitance comprises a second parasitic capacitance of the secondary-side switching element. 
     
     
         32 . The apparatus of  claim 22 , wherein the at least one operating parameter is a peak primary winding current value. 
     
     
         33 . Apparatus for power conversion, comprising:
 a power conversion circuit having a primary capacitance and a secondary capacitance that are matched based on a transformer turns ratio.   
     
     
         34 . The apparatus of  claim 33 , wherein the primary capacitance comprises a parasitic capacitance of a current control switch and the secondary capacitance comprises a parasitic capacitance of a secondary-side switching element. 
     
     
         35 . The apparatus of  claim 34 , wherein (i) the primary capacitance comprises the parasitic capacitance of the current control switch and an effective capacitance of at least one capacitor coupled to the power conversion circuit in a manner electronically equivalent to being coupled across the current control switch, and (ii) the secondary capacitance comprises the parasitic capacitance of the secondary-side switching element and an effective capacitance of at least one capacitor coupled to the power conversion circuit in a manner electronically equivalent to being coupled across the secondary-side switching element. 
     
     
         36 . The apparatus of  claim 33 , wherein the primary capacitance and the secondary capacitance are matched by dynamically adjusting a capacitance of the power conversion circuit. 
     
     
         37 . The apparatus of  claim 36 , wherein dynamically adjusting the capacitance comprises at least one of (i) tuning one or more of at least one capacitor of the power conversion circuit, (ii) switching one or more of the at least one capacitor into the power conversion circuit, or (iii) switching one or more of the at least one capacitor out of the power conversion circuit. 
     
     
         38 . The apparatus of  claim 33 , wherein an inductance of the power conversion circuit is set based on the matched capacitance. 
     
     
         39 . The apparatus of  claim 38 , wherein the inductance is set by dynamically adjusting at least one inductor of the power conversion circuit. 
     
     
         40 . The apparatus of  claim 39 , wherein dynamically adjusting the at least one inductor comprises at least one of (i) tuning one or more of at least one inductor of the power conversion circuit, (ii) switching one or more of the at least one inductor into the power conversion circuit, or (iii) switching one or more of the at least one inductor out of the power conversion circuit.