Title :
Design of an oscillator with off-time modulation for AC-DC converter
Author :
Geng, Yongtao ; Wu, Guoying ; Zhang, Bo
Author_Institution :
Dept. of Electr. & Comput. Eng., Clemson Univ., Clemson, SC, USA
Abstract :
An oscillator with off-time modulation (OTM) for AC-DC converter is designed in this paper. For the oscillator, capacitor and current sources are the key elements. The charging current source is constant while discharging current decreases in OTM mode. A feedback voltage, which is the output of voltage-loop error amplifier, is taken as an index of load. In light load and no load conditions, the feedback voltage modulates the discharge current, and then the off-time and the frequency of clock signal changes linearly with load. The function verification and the electrical characteristics simulation are performed with HSPICE. From the simulation results, the frequency of oscillator linearly decreases from 42.5 kHz to 455 Hz according to the output load, which means the function of OTM is realized.
Keywords :
AC-DC power convertors; capacitors; constant current sources; oscillators; AC-DC converter; HSPICE; capacitor; charging current source; clock signal; electrical characteristics are simulation; feedback voltage; function verification; off-time modulation; oscillator; voltage-loop error amplifier; Frequency modulation; Magnetic flux density; Pulse width modulation; Switches; Voltage-controlled oscillators; AC-DC converter; Off-time modulation; Oscillator; Switching mode power supply;
Conference_Titel :
Power Modulator and High Voltage Conference (IPMHVC), 2010 IEEE International
Conference_Location :
Atlanta, GA
Print_ISBN :
978-1-4244-7131-7
DOI :
10.1109/IPMHVC.2010.5958360
