Digital Control of Power Converters

Abstract

A system and method for controlling a power converter is presented. An embodiment comprises an analog differential circuit connected to an analog-to-digital converter, a digital pulse generator, and a pre-driver to control the power converter. Another embodiment also includes a digital filter as part of the control loop that may be used to control the loop characteristics of the control circuit. Yet another embodiment replaces the differential circuit with a sigma-delta analog-to-digital modulator and a decimator.

1 . A system for controlling a power converter, the system comprising:
 a differential unit with an input connected to a voltage to be controlled from the power converter;   an analog-to-digital converter communicably coupled to an output of the differential unit;   a digital filter communicably coupled to an output of the analog-to-digital filter; and   a digital pulse generator communicably coupled to an output of the digital filter.   
   
   
       2 . The system of  claim 1 , wherein the digital filter is configured to have an output of between about 1 to about 8 bits. 
   
   
       3 . The system of  claim 1 , wherein the digital filter is configured to control a loop response of the system. 
   
   
       4 . The system of  claim 1 , wherein the analog-to-digital converter comprises a sigma-delta modulator. 
   
   
       5 . The system of  claim 4 , further comprising a decimator and a digital filter communicably coupled between the sigma-delta modulator and the digital pulse generator. 
   
   
       6 . The system of  claim 1 , wherein the differential unit is configured to generate an error signal. 
   
   
       7 . The system of  claim 6 , wherein the analog-to-digital converter is configured to oversample the error signal. 
   
   
       8 . The system of  claim 1 , further comprising a pre-driver communicably coupled to the output of the digital pulse generator. 
   
   
       9 . The system of  claim 7 , further comprising a power converter communicably coupled to the input of the differential circuit, and communicably coupled to the output of the pre-driver. 
   
   
       10 . A system for power conversion control, the system comprising:
 a differential circuit comprising a first input connected to a reference voltage, a second input connected to a voltage to be controlled, and an error output;   an analog-to-digital converter communicably coupled to the error output of the differential circuit; and   a digital pulse generator communicably coupled to an output of the analog-to-digital converter.   
   
   
       11 . The system of  claim 10 , further comprising a digital filter communicably coupled between the analog-to-digital converter and the digital pulse generator. 
   
   
       12 . The system of  claim 11 , wherein the digital filter is configured to control a loop response of the system. 
   
   
       13 . The system of  claim 10 , wherein the analog-to-digital converter is configured to oversample an analog error signal from the differential circuit. 
   
   
       14 . The system of  claim 10 , further comprising a pre-driver communicably coupled to the output of the digital pulse generator. 
   
   
       15 . A power conversion system comprising:
 a power converter configured to operate at a first clock frequency;   an analog-to-digital converter communicably coupled to an output voltage of the power converter, the analog-to-digital converter configured to sample the output voltage at a second clock frequency higher than the first clock frequency;   a first digital filter communicably coupled to the analog-to-digital converter, the first digital filter configured to output a signal at the first clock frequency; and   a digital pulse generator communicably coupled to the first digital filter and the power converter.   
   
   
       16 . The power conversion system of  claim 15 , wherein the analog-to-digital converter comprises a sigma-delta modulator. 
   
   
       17 . The power conversion system of  claim 16 , further comprising a differential circuit communicably coupled between the power converter and the analog-to-digital converter, the differential circuit configured to output an error signal to the analog-to-digital converter. 
   
   
       18 . The power conversion system of  claim 15 , wherein the second clock frequency is a multiple of the first clock frequency. 
   
   
       19 . The power conversion system of  claim 15 , wherein the digital pulse generator comprises a counter. 
   
   
       20 . The power conversion system of  claim 15 , further comprising a second digital filter communicably coupled between the first digital filter and the digital pulse generator.