Coulomb Counter Research Articles

Battery level A/D conversion with fuel gauge sense voltage cancellation in 40 nm CMOS technology

A new integrated approach for battery voltage conversion inside portable devices is presented. It is specifically suited for latest Fuel Gauge techniques and exploits an A/D converter that operates as a General Purpose ADC inside the system. A peculiar solution for an analog cancellation of the Coulomb counter sense resistor voltage drop on the battery level measurement is disclosed. A prototype made by this battery voltage buffer and a 10-bit A/D converter has been integrated in a 40 nm CMOS process with double oxide option, resulting to a total power consumption of about 950 μW, and an active area of 0.174 mm2.

Energy Efficient Output Regulation with Adaptive Behaviour in a DC-DC UPS

Abstract This paper presents an embeddable and highly customizable DC to DC UPS module in a novel and lightweight approach comparing to dozens of existing semi-industrial grade AC and DC UPS devices. Majority of them are following nearly the same, less flexible and less energy efficient scheme, operating on fixed battery type, fixed output voltage and having a featureless USB link to the host PC. In our vision energy efficiency is critical to achieve maximum performance at output without even moderate energy losses. This is even more important in case of an embeddable UPS device which needs to act as much “transparent” as it could in terms of energy efficiency reported to the primary energy source. This is mostly the main definition of our research area. Thus the main goal is to increase efficiency even with the cost of output precision but in the allowed domain of accepted input voltage range of the powered system. Our proposal, a combination of a mid range RISC MCU and a customizable AFE, power path controller and coulomb counter could result in a simpler but more efficient power converting device, even using low priced, less performing components (digital potentiometers and MOSFETs) where the control software could overcome many of the performance issues by algorithms.

Enhancement of the Coulomb Counter Estimator by the on-board Vehicle Determination of Battery Initial State of Charge

A battery Electric Vehicle (BEV) is a widely used type of Electric Vehicle (EV) that uses chemical energy stored in rechargeable battery packs. BEVs are becoming more attractive with the advancement of new battery technology that has higher power and energy density and allowing matching the requested autonomy and vehicle dynamics as a Lithium battery. The autonomy of the BEV is a key point in the development and commercialization of this kind of vehicle. The requested autonomy is directly linked to the amount of the stored and remaining energy in the battery which is the State Of Charge (SOC). This paper proposes a new formula to estimate in a real operating condition the initial battery SOC which is used in the Coulomb counter estimator. Simulation and comparison with actual data are concluding.