The Impact of an Overlaid Ripple Current on Battery Aging: The Development of the SiCWell Dataset

Abstract

Fast-switching semiconductors induce ripple currents on the high-voltage DC bus in the electric vehicle (EV). This paper describes the methods used in the project SiCWell and a new approach to investigate the influence of these overlaid ripples on the battery in EVs. The ripple current generated by the main inverter is demonstrated with a measurement obtained from an electric vehicle. A simulation model is presented which is based on an artificial reference DC bus, according to ISO 21498-2, and uses driving cycles in order to obtain current profiles relevant for battery cycling. A prototype of a battery cycling tester capable of high frequency and precise ripple current generation was developed and is used to cycle cells with superimposed ripple currents within an aging study. To investigate the impact of the frequency and the amplitude of the currents on the battery’s lifetime, these ripple parameters are varied between different test series. Cell parameters such as impedance and capacity are regularly characterized and the aging of the cells is compared to standard DC cycled reference cells. The aging study includes a total of 60 automotive-sized pouch cells. The evaluation of ripple currents and their impact on the battery can improve the state-of-health diagnosis and remaining-useful life prognosis. For the development and validation of such methods, the cycled cells are monitored with a measurement system that regularly measures current and voltage with a sampling rate of 2 MHz. The resulting dataset is suitable for the design of future ripple current aging studies as well as for the development and validation of aging models and methods for battery diagnosis.

Battery Integrated Modular Multilevel Converter Topologies for Automotive Applications

“…Paper IV presents the continuous DC charging capabilities of BI-MMCs assuming the same submodule semiconductor losses during traction at maximum tractive power. Several pieces of research indicate an improvement in battery life with pulsed charging current [76,77]. Therefore, future research will extend the work in Paper IV to pulsed charging.…”

A Comprehensive Review of GaN-Based Bi-directional On-Board Charger Topologies and Modulation Methods

“…Due to the evaluation of battery pack systems, strict dimensional constraints on the OBCs are imposed during vehicle charging. Moreover, high-switching GaN-based OBC is subjected to cause a superimposed high-frequency ripple current on the battery pack system, and studies have depicted that batteries degrade faster under charging and discharging cycles with current ripples [40]. In [40,41], the long-term effects of superimposed current ripple at from 55 Hz up to 20 kHz on battery ageing using 18650 model batteries have been investigated.…”

“…Moreover, high-switching GaN-based OBC is subjected to cause a superimposed high-frequency ripple current on the battery pack system, and studies have depicted that batteries degrade faster under charging and discharging cycles with current ripples [40]. In [40,41], the long-term effects of superimposed current ripple at from 55 Hz up to 20 kHz on battery ageing using 18650 model batteries have been investigated. The results showed that, at the same number of cycles and same ripple current magnitude, the temperature rise of the batteries with highest frequency ripple is higher compared to the other specimens.…”

“…Additionally, the BMS protection ranged in between 10-1 mS and cannot activate voltage protection timely to block the transient overcharge and over-discharge at frequencies above 100 Hz-1 kHz. Though specific requirements are not found in the literature, several requirements are listed from studies [40][41][42][43] for ensuring the proper reliability of a battery pack system: (a) <5% ripple current above 1 kHz frequency, (b) independent AC/DC conversion for lowering the ripple content on DC charge and discharge, and (c) ripple current superposition on various CC/CV charge/discharge modes for battery stack composed of 96 cells, as shown in Figure 2a,b. As lithium-ion batteries (LIB) are prone to lithium plating, it is important to reduce charging currents and ripple, particularly at a high state of charge level (SoC).…”

Review on Non-Isolated Multiport Converters for Residential DC Microgrids

“…High current ripple at the RES input current greatly affects MPP tracking and may lead to reduced power generation [16]. Additionally, even though the lifetime of ESSs (usually batteries) are dependent on many parameters, high current ripple may enhance aging [17].…”