Electric Vehicle (EV) is clearly the future of the automotive industry, given the increasing need for reducing CO2 emissions from fossil fuel combustion. In the wake of a global call to make the planet greener, one of EV’s greatest advantages is a quiet motor, which gives off an average of 100% torque at zero RPM. The EV, in fact, has undergone steady development over the years. Advancements in battery life and efficiency have led to a gradual decline in battery cost that has helped in making the vehicle more affordable to customers.
Today, more and more EVs of all kinds — from e-rickshaws, two-wheelers, cars, and buses to cargo trucks— have gradually begun traversing roads. However, even as the transition from the deeply entrenched Internal Combustion Engine (ICE)) to electric drive train sounds exciting and disruptive, it entails formidable challenges such as optimizing the vehicle’s performance, lifespan, and safety while designing intelligent battery management and charging systems.
This article delves into the ways to enhance the efficiency of electric vehicles as well as challenges confronting the manufacturers to make this new-age vehicle a dependable, user-friendly, viable, and safe proposition.
Smart cell monitoring
In EV battery packs, a variety of cell modules are arranged in series and in parallel. Battery management system (BMS) comprises several components that include monitoring components close to the battery cells, one or more power-conversion stages dictated by the needs of the vehicle, and intelligent controllers or embedded processors placed at strategic locations in the architecture to manage various aspects of EV’s power subsystem.
The voltage of each battery cell, the temperature of various points in the module and other conditions are monitored by the battery monitoring integrated circuit (BMIC). This data is reported to a cell management controller (CMC) and, depending on the complexity of the system, on to higher-order processing elements, such as one or more battery management controllers (BMC).
Smart battery management
Depending on the complexity of Full Electrical Vehicles (FEVs) or Hybrid Electrical Vehicles (HEVs), several intelligent microcontrollers (MCUs) oversee and manage various critical tasks related to the battery and the power subsystem. Usually, these MCUs contain multiple processing cores. Some may consist solely of general-purpose reduced instruction set computing (RISC) processors, while others, equipped with the capability to manage mathematically intensive tasks, usually feature one or more digital signal processing (DSP) core.
CMCs, working in tandem with BMICs, play an essential role in ensuring the performance of the battery and its long life. BMIC helps alert the CMC or higher-level controller about the need for reducing the power drawn from the package to reduce overheating before the situation worsens.
Smart battery charging
To avoid thermal runaways or other conditions that would either reduce the battery’s capacity or its lifespan, it is imperative to charge and discharge the battery efficiently. To ensure this, the controlling MCU responsible for the actual charging of the battery must be able to quickly adjust and adapt in real-time to the battery’s changing properties, like oxidation on the terminals, cell voltages, and others. During charging, the MCU must be able to respond quickly to overvoltage conditions; otherwise, it might cause the battery to catch fire.
Technological innovations
New technologies are emerging for EV onboard charging applications. These technologies, which better accommodate direct connection to AC outlets that tap into the power grid, let EV manufacturers reduce the size and weight of the vehicle’s charger, which translates into a more extended range per charge for the vehicle. Plus, these technologies have improved power efficiencies, so less power is lost during charging and charge times are reduced.
High-performance processing enables certain advanced operating modes in FEVs and HEVs, such as stop/start mode and town and country mode. While stop/start mode allows the gas engine in an HEV to be stopped to save fuel when the vehicle is stopped at a traffic light or stuck in traffic, town and country mode lets an HEV switch back and forth between the gas engine and the electric motor depending on which would be more efficient.
However, even with these advancements, there are still many hurdles that EVs must overcome before their use becomes widespread.
Overcoming the challenges
To begin with, the warranty period of EVs battery is many times less than that of the rest of the parts and equipment of the vehicle. Further, lack of charging stations limits EV use to mainly in-town trips and other local errands. Until charging stations become common, EV use will remain restricted to some extent.
As EV batteries contain the energy equivalent to a small explosive, over-voltage or under-voltage can lead to thermal runaways leading to battery failure. Chief among the safety concerns are thermal runaways which can be brought about by several malfunctions, such as overcharging or discharging too quickly. To help avoid unsafe events, BMS must be able to monitor and detect changing operating parameters continually and notify CMCs or BMCs to take a protective action like shutting down a battery cell that is overheating.
During the charging and discharging of an EV battery, it is imperative that each cell within the battery pack is closely and accurately monitored because any number of out-of-spec conditions may quickly cause internal damage
The BMS must have the ability to verify that alarms/alerts are genuine. It should be equipped with built-in protection functionality capable of instantaneously taking appropriate action to head off a runaway condition before it potentially becomes unsafe.
At a fundamental level, components must be qualified and must support safety capabilities defined in the functional safety standards for EVs. This requires that the BMS must be able to analyze operating conditions and assess the potential risk that any change in a parameter may pose to the vehicle and its passengers.
The future of EV
An intelligent power management system loaded with innovative power-stage components is a pre-requisite to optimize the performance, lifespan, and safety of EV. This system must ensure thorough and frequent monitoring of vital operating parameters, robust communications among all of the nodes on all the control loops, and fast decision making followed by effective control and protection mechanisms.
Thanks to advancements in technology and infrastructure, we can expect the EV industry to continue to grow. While it is true that EV charging stations are quite limited as of now, such facilities are gradually expanding across the world. Also, new technological advancements are underway to leverage the vehicle’s performance and life while minimizing potential risks, costs, and limitations currently associated with EV use.
References:
http://www.towerfast.com/press-room/the-latest-developments-and-advancements-in-electric-vehicle-technology
http://www.ti.com/lit/wp/spry304a/spry304a.pdf
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