Desenvolvimento de um circuito de instrumentação para equalização híbrida

Abstract

With the growth of the electric mobility sector and the increasing demand for Battery Management Systems (BMS), cell voltage balancing has become one of the most important functions for ensuring the performance, safety, and service life of energy storage systems. In this context, this work presents the development of an instrumentation circuit for hybrid balancing of lithium-ion batteries, combining passive and active balancing techniques. The developed system consists of a current, voltage, and temperature measurement module, as well as balancing circuits. In the measurement system, cell voltages were monitored through voltage divider circuits connected to the ADS1115 analog-to-digital converter. The current was measured using the LAH50-P current sensor, while the temperature was monitored using the DS18B20 temperature sensor. The passive balancing circuit was implemented using 5 W resistors for cell balancing, 20 W resistors for module balancing, and TIP31C transistors as switching devices. The active balancing circuit was based on a half -bridge buck-boost converter employing IR2112 gate drivers to drive the P60N06 MOSFETs. This configuration enables energy transfer from the module with the higher state of charge to the one with the lower state of charge, improving the balancing process. The prototype was validated through discharge tests conducted at a 0.5 C current using an electronic load. The results demonstrated the performance of the proposed system and highlighted the differences between passive and hybrid balancing methods. The tests showed that the hybrid strategy achieved a shorter balancing time and a lower standard deviation of cell voltages, resulting in more uniform cell balancing and demonstrating its suitability for lithium-ion battery energy storage applications.