Comparative Analysis of the Battery Charging System using Digital and PI Controller

Abstract

Lithium-ion batteries are growing in popularity due to increasing demand and higher energy density; majorly contributed by the ever-advancing technology of portable devices and electric vehicles. A battery charger, or voltage regulator, which is crucial for charging and discharging, therefore must be specifically designed to prevent damages. This study is concerned with designing a digitally controlled charging system using a DC-DC boost converter, which is able to operate with a wide range of input voltage with specific output voltage. All the critical parameters for the proposed design components based on 100kHz switching frequency had been calculated and modeled using MATLAB/Simulink software. Several PI parameters had also been applied in order to verify the effectiveness of the model. The PI controller was simulated with different K_p and K_i, and the results had been analyzed in detail. The digital controller was programmed using Field Programmable Logic Array using Quartus II software. The results showed that with K_p =0.0009 and K_i =11.4 gave better performance than other parameters, with a rise time of 200.45μs, overshoot -1.503%, settling time of 10.40ms with an output voltage ripple less than 1%.  Finally, A digital controller, Altera DE2-70 board with parallel 8-bit ADC, had been used to verify the performance of the proposed digital controller.