Improved Performance Li-Ion Battery Management System

07/08/2019

Summary

An improved energy management system is proposed that significantly influences the performance of Li-Ion Battery system leading to the increase of its lifespan. It refers to an active energy dissipative equalization technique based on the proper control of the gate-source voltage of the parallel connected MOSFET to each battery cell, so as, the MOSFET can behave as a controllable current source for the voltage equalization. The proposed technique has been validated in the lab.

Technology Description

An active energy dissipative equalization technique has been developed based on the proper control of the gate-source voltage of the parallel connected MOSFET to each battery cell, so as, the MOSFET can behave as a controllable current source for the voltage equalization.It is well known that in a power switch, as a MOSFET that is commonly used in battery cell equalization schemes, there are two conducting regions. In the ohmic region, the drain current has a linear response to changes of the drain-source voltage (VDS) and if the gate-source voltage VGS exceeds a threshold value Vth (VGS >Vth) and also VDS>VGS-Vth, the MOSFET operation enters to the saturation region, where the drain current ID increases with the increase of the VGS voltage.

In the ohmic region, the MOSFET operates as a constant value resistor and the conduction current ID is controlled by the drain-source voltage VDS. In the saturation region, the MOSFET behaves as a controllable current source and therefore, the conduction current ID is controlled by the gate-source voltage VGS. By exploiting the latter feature, the MOSFET can be employed as a controllable device for smoothly regulating the equalization current for the voltage balancing of battery cells.

Main advantages

The proposed battery cell equalization technique protects the battery lifespan better than the conventional one. Avoiding the series connected resistor it is slightly cheaper and also, slightly smaller in size compared with the other dissipative systems. In addition the proposed cell equalization technique is faster and more effective since the cell equalization is accomplished by a current of variable amplitude. Furthermore in the proposed technique the thermal management is more effective.

Stage of development

The proposed technique has been validated in the lab (TRL4).

Challenge and needs

The challenge for the proposed project consists of collaborating with an industrial partner in order to validate the technology in a relevant environment and proceed to a prototype production demonstrated in an operational environment.

Intellectual property

A relevant patent has been already granted.

Potential markets and targets

Lithium-ion (Li-ion) batteries are rechargeable batteries with high-energy density and are majorly used in portable equipment. The market for these batteries is expected to witness significant growth owing to increase in use in smartphones, tablets/PCs, digital cameras, and power tools. Moreover, the demand for Li-ion batteries in the automobile industry is expected to increase in line with rise in demand for electric vehicles. These batteries have gained popularity among automobile manufacturers as they offer an alternative to nickel metal batteries used in electric vehicles, due to their small size and light weight. Ongoing technological advancements are aimed towards reducing the weight of these batteries, while also maintaining the ability to provide sufficient power for a longer period of use.

Potential partners

Companies specialized in circuit & PCB design, battery management systems, software & firmware development, EMC testing, prototype production and power electronics converters.

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