Method and apparatus for integrated cable drop compensation of a power converter

Abstract

A controller for a power converter includes a switching control circuit to output a drive signal to control switching of a switch to regulate the output power of the power converter, and output a switching signal representative of the drive signal. A cable drop compensator receives the switching signal, and outputs a compensated reference voltage signal to the switching control circuit. The cable drop compensator further includes a switching coefficient calculator to output a switching coefficient signal in response to the switching signal. The switching coefficient signal is representative of a ratio of a load current to a maximum deliverable load current. A voltage compensation calculator outputs the compensated reference voltage signal in response to the switching coefficient signal. The switching control circuit outputs the drive signal in response to the compensated reference voltage signal.

What is claimed is: 
     
         1 . A controller for a power converter, the controller comprising:
 a switching control circuit coupled to output a drive signal to control switching of a switch to regulate the output power of the power converter, and further coupled to output a switching signal representative of the drive signal; and   a cable drop compensator coupled to receive the switching signal, and coupled to output a compensated reference voltage signal to the switching control circuit, wherein the cable drop compensator further comprises:
 a switching coefficient calculator coupled to output a switching coefficient signal in response to the switching signal, wherein the switching coefficient signal is representative of a ratio of a load current to a maximum deliverable load current; and 
 a voltage compensation calculator coupled to output the compensated reference voltage signal in response to the switching coefficient signal, wherein the switching control circuit is coupled to output the drive signal in response to the compensated reference voltage signal. 
   
     
     
         2 . The controller of  claim 1 , wherein the cable drop compensator is coupled to adjust the compensated reference voltage to compensate for a distribution voltage across a distribution network to be coupled to the power converter. 
     
     
         3 . The controller of  claim 2 , wherein the compensated reference voltage signal is responsive to a sum of the distribution voltage and a load voltage across a load to be coupled to the distribution network. 
     
     
         4 . The controller of  claim 1 , wherein the switching coefficient calculator comprises a low pass filter coupled to generate the switching coefficient signal. 
     
     
         5 . The controller of  claim 1 , wherein the voltage compensation calculator is coupled to receive a current limit adjust signal, and is further coupled to output the compensated reference voltage in response to the current limit adjust signal. 
     
     
         6 . The controller of  claim 5 , wherein the voltage compensation calculator is coupled to determine a current limit ratio of a peak current to a maximum switch current in response to the current limit adjust signal, and is coupled to output the compensated reference voltage in response to the current limit ratio. 
     
     
         7 . The controller of  claim 1 , wherein the switching coefficient signal is a ratio between a number of enabled switching cycles and total switching cycles. 
     
     
         8 . The controller of  claim 1 , wherein the switching coefficient signal is a ratio between an on-time of the switch and total switching period.