Microcontroller-Based Lead-Acid Battery Balancing System for Electric Vehicle Applications

In application of lead-acid batteries for electrical vehicle applications, 48 V of four 12 V batteries in a series configuration are required. However, the battery stack is repeatedly charged and discharged during operation. Hence, differences in charging and discharging speeds may result in a different state-of-charge of battery cells. Without proper protection, it may cause an excessive discharge that leads to premature degradation of the battery. Therefore, a lead-acid battery requires a battery management system to extend the battery lifetime. Following the LTC3305 balancing scheme, the battery balancing circuit with auxiliary storage can employ an imbalance detection algorithm for sequential battery. It happens by comparing the voltage of a battery on the stack and the auxiliary storage. In this paper, we have replaced the function of LTC3305 by a NUCLEO F767ZI microcontroller, so that the balancing process, the battery voltage, the drawn current to or from the auxiliary battery, and the surrounding temperature can be fully monitored. The prototype of a microcontroller-based lead-acid battery balancing system for electrical vehicle application has been fabricated successfully in this work. The batteries voltage monitoring, the auxiliary battery drawn current monitoring, the overcurrent and overheat protection system of this device has also successfully built. Based on the experimental results, the largest voltage imbalance is between battery 1 and battery 2 with a voltage imbalance of 180 mV. This value is still higher than the target of voltage imbalance that must be lower than 12.5 mV. The balancing process for the timer mode operation is faster 1.5 times compared to the continuous mode operation. However, there were no overcurrent or overtemperature occurred during the balancing process for both timer mode and continuous mode operation. Furthermore, refinement of this device prototype is required in the future to improve the performance significantly.

Influence of displacement and patterning of phase shifters for piston mode operation of temperature compensated surface acoustic wave resonators on SiO2/LiNbO3 structure

This paper discusses influence of displacement and patterning of phase shifters for piston mode operation of the temperature compensated (TC) surface acoustic wave (SAW) resonator on SiO2/LiNbO3 structure. As the phase shifters, Cu metals placed on the top surface of SiO2 are considered. First, the conventional Cu stripes are chosen, and their displacement are considered from IDT aperture edges. It is shown that achievable transverse mode suppression is almost identical when the stripe shape is adjusted for each case. Next, Cu dots are considered as patterned phase shifters. It is shown comparable transverse mode suppression is possible also for this case. However, relatively strong SAW lateral leakage occurs when they are placed above IDT fingers. These results indicate that location and pattern can be added as design parameters for the phase shifters on SiO2. It is favorable for further enhancement of total device performances.

Trade-off Study on Economy and Environmental Aspects of a Dual Fuel Diesel Engine using Diesel Additive and Producer Gas

Experiments are performed on a diesel engine working in single fuel mode using fossil diesel (FD) as well as 5% and 10% (v/v) di-ethyl ether (DEE) additives with FD as fuels as well as in dual fuel mode using the above fuels as pilot fuels along with producer gas (PG) as primary fuel. This study aims to draw comparative analyses of engine combustion, performance and emission characteristics using the above fuel combinations to establish the most suitable fuel strategy for a diesel engine. The study revealed greater control over nitric oxide (NO) and smoke opacity in dual fuel mode compared to single fuel mode operations. Addition of DEE with FD, produced lower HC and CO emissions, comparable NO emissions along with reduced smoke opacity compared to FD in both modes of operation. Further, in dual fuel mode operation, the diesel percentage energy substitution (PES) reduced with increase in DEE content in the blends. The tradeoff study involving engine performance and emissions with respect to the cost of operation revealed that the fuel strategy used in dual fuel mode operation delivered better engine performance along with reduced NO emission and smoke opacity at lower operational cost compared to all the considered fuel strategy in single fuel mode operation. Especially, FD+5% DEE+PG and FD+10% DEE+PG fuel strategies were found to be the most suitable dual fuel mode combinations in a diesel engine in terms of their superior engine performance, lower emissions along with better economy.