Digital Pulse Width Modulation Generation Using 8051 for DC DC Buck Converter

Abstract

The research on digital control of DC-DC converters is mainly focused on two areas. One is the methods to generate digital PWM (DPWM) signals to meet the output voltage requirement precisely. Various techniques have been developed to meet the requirement of output voltage and at the same time it is also necessary to get more resolution to increase precision. The other is to develop new control methods that can utilize the advantages of the digital controller so as to improve the dynamic performance of the switching power converters. The objective of this thesis is to study current techniques of DPWM generation and to develop new techniques using 8051 for low cost implementation. In this thesis a new way is proposed for PWM generation, which uses the Timers and Interrupts of 8051. Motivation behind selecting 8051 microcontroller is its low cost and ease of programming, despite its disadvantages, like low clock frequency (33 MHz for 89C51RD2, which in internally divided by 12), no inbuilt ADC or DAC. Initially different techniques are validated in NI Multisim environment and also the proposed method is validated on the same platform for a dc-dc buck converter. This thesis also compares the designed new approach with the delay line method of DPWM generation with simulation result. The delay line method is also implemented in 8051 for comparison with the new designed method.