Method of Current Compensation Based on Division-Sigma Control for DC/DC Converter

摘要

A method is provided for current compensation. The method is based on division-sigma (D-Σ) control for a DC/DC converter. Inductance changes are allowed with D-Σ digital control achieved. Loop gain can be quickly adjusted. The disadvantage of average current-mode control (ACMC) is solved, where the disadvantage is a reduction of the response speed caused by the filter within the current loop. The present invention uses midpoint current sampling to ensure taking an average inductor current value in each switching cycle. By doing so, a lack of fidelity of peak current-mode control (PCMC) is solved, where the lack of fidelity is due to the amount of error value between the peak value and the average value. Besides, the present invention uses a table of the inductance following current changes to achieve compensation of duty cycle ratio, where the table is built in a single chip.

主权项

1. A method of current compensation based on division-sigma (D-Σ) control for a DC/DC converter, comprising steps of:
(a) multiplying a difference between a reference voltage (Vref) and a voltage output feedback (Vof) by a voltage-error compensation (Kp) to obtain a reference current (iref); (b) obtaining an inductor current variation (ΔiL) through said reference current (iref) and obtaining a duty ratio (d) with said inductor current variation (ΔiL) through a characteristic formula of D-Σ digital control; (c) obtaining an inductor current (iL(n+1)) through a transference function (Gp) with said duty ratio (d) in an operation of a system to regulate output with said inductor current (iL(n+1)) and an effective impedance (ZO) outputted from said system; and (d) outputting a voltage (VO(n+1)).