Automotive

Something New about Electric Vehicle Batteries

For decades, the automotive industry has been slowly consolidating while technology and brand differentiation have diminished. The powertrain, the system that converts energy into motion, is arguably the most valuable intellectual property of automakers. It has undergone more than a century of refinement and improvement.

In this context, the emergence of new vehicle manufacturers is remarkable, because it means that powertrain technology is being challenged.

electric-vehicle-batteries

A typical internal combustion engine (ICE) car has a 15-gallon fuel tank. It equates to nearly 500 kilowatt hours of electricity.

15 gallons of gasoline translates into a 375-mile range for an ICE car. 500 kilowatt hours of electricity translates into a 1,450-mile range for an electric car.

This tremendous energy efficiency advantage is what ultimately made the electric car a winner. But the biggest problem is that their battery capacity does not match the range of internal combustion engine cars.

1. The Development of Electric Vehicles Battery

Japan

Research on batteries for pure electric vehicles is mainly focused on lithium batteries. It’s followed by lead-acid batteries, nickel-hydrogen batteries and sodium batteries.

In terms of the total number of patent applications worldwide, Japan has the largest number of patent applications. It’s related to batteries for pure electric vehicles and their management systems.

In terms of the number of patent applications in Japan, more than 90% of the patent applications also come from Japanese applicants.

From the perspective of the number of patent applications in the world,  Japan is the strongest in the field of battery and its management system for pure electric vehicles and controls most of the patented technologies.

In terms of the total number of patent applications worldwide, as of June 2010, the number of patent applications related to the battery and its management system for pure electric vehicles in the United States ranked second after Japan.

In terms of the number of patent applications in the U.S., among the patent applications related to batteries for pure electric vehicles and their management systems.

The largest number of patents came from Japanese applicants, close to 60% of the total, while the number of patent applications from U.S. applicants was second to Japan.

Germany

Research on batteries for pure electric vehicles has focused on lithium batteries, followed by lead-acid batteries, nickel-hydrogen batteries, sodium batteries, and air batteries.

In terms of the total number of patent applications worldwide, as of June 2010, Germany ranked 6th in the world. In terms of the number of patent applications related to batteries for pure electric vehicles and their management systems, which is very different from that of Japan, which ranked first, accounting for only 11% of the number of applications in Japan.

For the number of patent applications in Germany, German applicants hold about 43% of the total number of patents, which is higher than Japan, which ranks second.

On a global scale, Germany’s technological strength in the field of battery and its management system for pure electric vehicles is far inferior to that of Japan, but on a domestic scale, Germany has a strong technological advantage and holds more patents than Japan.

According to a report released in Shanghai on June 7, 2013 by Roland Berger, a leading European consulting firm, the global outlook for electric vehicle manufacturing is not very promising, with the exception of China.

The report compares the electric vehicle markets of seven major car manufacturing countries – Germany, France, Italy, the United States, Japan, China and South Korea – and analyzes in detail the current state of development of the electric vehicle industry in each country in terms of technology, industrial development and market development.

The report points out that the profit margin from the production of electric vehicles is far less than that from the production of conventional vehicles, and this high cost and limited benefit, coupled with the expected stabilization of oil prices in the next few years, makes the cost disadvantage of electric vehicles more and more obvious.

However, among the seven countries mentioned above, only China’s investment in the electric vehicle industry has not declined. According to Jun Shen, a partner at Roland Berger, China’s electric vehicle market will still maintain its upward momentum in the long run

China

In a densely populated country like China, the electric vehicle market has great potential, and there is still a considerable gap compared with developed countries in electric vehicles.

Therefore, we must catch up with the developed countries’ electric vehicle R&D, conduct serious R&D from power supply, integrated circuits, and power supply plates, and make concerted efforts to make the battery industry bigger and stronger.

China’s power batteries for automobiles have begun to enter the industrialization stage from research and development, and the momentum of accelerated development has emerged. The main performance of electric vehicle power battery research and development products has been in the international advanced level, but need to address some weak links.

Domestic vehicle power batteries have shown a more obvious cost advantage, and the cost of energy-based power batteries of some enterprises is only about half of that of Japanese and American enterprises, which means that the commercialization of electric vehicles in China is in a position to accelerate and achieve large-scale exports with cost advantages.

The global power battery industry faces technical constraints and cost constraints, and only when the performance of power batteries is improved, the cost is significantly reduced, and the application is on a large scale, can the vigorous development of other more mature links be driven.

Therefore, the power battery is the most valuable link in the electric vehicle industry chain and is most likely to gain excess returns, while other links such as motor and electric control system have more mature technology and market base, with many competitors, and may only gain average returns.

2. What’s the Challenge of Electric Vehicle?

 

The battery pack of an electric vehicle consists of hundreds of cells working in series, producing voltages from 400 V to 800 V. Overcharging and overdischarging can damage the cells or prematurely age them.

Reducing capacity or life and ultimately leads to battery failure. The electronics of the battery management system are key to maximizing the operating range, life, reliability and safety of the electric vehicle battery system.

It is never easy to accurately and continuously measure all the cells in a long string of high-voltage batteries that are tightly coupled together. Measurements need to be free from the high electrical noise generated by inverters, actuators, switches, relays, etc.

The electronics themselves also need to be electrically isolated due to the high voltage of the battery pack. Finally, the electronics need to operate for several years under the influence of wear and tear, weather conditions, vehicle age and mileage, etc

Classification of batteries for electric vehicles

 

The current batteries for electric vehicles are ternary lithium batteries, lithium iron phosphate batteries and nickel-metal hydride batteries. Among them, NiMH battery is the most stable, lithium iron phosphate is the safest, and ternary lithium battery is the largest.

Ternary lithium battery: good at cooperation, the same weight has the maximum power. But the temperature of the components packed closely together is a bit high, so ternary lithium batteries have strict requirements for heat dissipation. To ensure safety, each cell must have a safety device.

Lithium iron carbonate battery: Popular with most car companies. The same weight of electricity is not as good as the ternary lithium battery. But the thermal stability is good, not easy to fire, and the cost of heat sink parts is much lower. In addition, it also has the advantages of high energy density, small size, long battery life and good safety.

Hydrogen: Generally used in hybrid vehicles, the performance is worse than lithium batteries. This kind of battery has good memory, and overcharge and overdischarge can be clearly remembered. Therefore, NiMH batteries require high charge and discharge times, and the power must be kept within a fixed range. So the electric gentleman suggests you try to charge after each use, once full. Do not charge after a period of time.

Hydrogen fuel cell: High energy conversion efficiency, zero pollution, long life and low price. In addition, those who have studied chemistry are familiar with:Hydrogen is flammable, and if transported or stored in large quantities, the requirements are high, the risk factor is high, and the safety hazard is high.

As the power source of battery electric vehicles, it has been regarded as an important landmark technology for the development of electric vehicles. An important bottleneck that restricts the development of electric vehicles. Its performance is directly related to the range of the whole vehicle.

 

3. The Core of the Battery Management System of Electric Vehicle

 

As a leading supplier of integrated circuits (ICs) and solutions, ADI’s battery management products focus on several key aspects: individual cell measurements (battery monitors), overall pack measurements (pack monitors), communication networks of interconnected devices (via wires or wireless networks), and software to control these devices.

What’s the Goal of  the Electric Vehicle Battery?

The goal of these electronics is to allow all cells to be safely charged to the highest possible capacity. It ensures that the entire pack receives the maximum storable energy and fully increases the vehicle’s range.

Arguably the most critical device is the high-voltage battery monitor IC, which measures the voltage and temperature of cells connected in series, typically 12 cells per monitor. Cell voltage and temperature are the key parameters; measurement accuracy and synchronization are the key characteristics.

Combined, these parameters allow the battery management system to operate the battery within its maximum safe operating range without stressing the battery.

Therefore, the performance of these battery monitors is critical for the battery management system to fully optimize vehicle range, cost, weight and reliability.

4. How is the ADBMS6815 Of ADI

 

ADI’s recently introduced ADBMS6815 series of precision battery monitors is a more ideal combination of features to achieve safety, performance and cost effectiveness.

The ADBMS6815 series battery monitor features a daisy-chained interconnect design using the isoSPI™ two-wire communication interface.

It is a stable, reliable, EMI-insensitive, electrically isolated network. And it’s capable of synchronously operating, polling and controlling ADI’s battery management system devices from the battery management system microcontroller.

The ADBMS6815 series also supports operation in a wireless battery management system (wBMS), where the wired daisy chain is replaced by a 2.4 GHz wBMS node for the battery monitor.

3 Points of ADBMS6815 of ADI

Safety. Of all the goals of a battery management system, ensuring the safety of the battery pack is paramount. Identifying and remedying potential failures within the IC requires built-in self-test capabilities and redundancy.

These features include redundant measurement paths, improved synchronization between input signals, self-test capability, etc. The ADBMS6815 family of parts is designed to support the ISO 26262 ASIL-D standard.

Low-power cell monitoring. In addition to ensuring a stable, predictable, and reliable energy source for the vehicle, the battery management system must also ensure that the cells themselves are always safe.

Although it is a relatively rare occurrence, a defective cell can cause the battery to shorten its life over time. And lead to thermal runaway, with catastrophic results. For this reason, battery management systems need to monitor for conditions that could signal any potential problems.

Flexibility, Functionality and Cost Effectiveness. The ADBMS6815 family offers a more desirable combination of features to meet a wide range of requirements. And it provides some complementary effects to the safety, reliability and performance described above.

These devices use the same package and pinout. They allow designers to build generic designs with different channel counts (6, 8, 12 individual cells per device monitoring). It’s with different option configurations to meet the configuration needs of more battery packs or battery modules.

These products also contain universal I/Os that can operate as digital inputs, digital outputs, or analog inputs. When operating as analog inputs, they can measure any voltage up to 5 V with the same measurement accuracy.

In addition, these auxiliary measurements, such as temperature or current measurements, can be synchronized with cell measurements.

5. Summary

 

Within the next 30 years, the world will shift from internal combustion engines to electric passenger vehicles. Geopolitical and environmental issues will only accelerate this trend. Electric vehicles are the future, and battery management system technology is a key enabler.\

Leading battery management system products, such as the ADBMS6815 series, are driving the future. Certified to ISO 26262 ASIL-D standards, these ICs are industry-leading in cell voltage and temperature measurement accuracy.

Designers can choose ADI products with confidence that ADI’s market-leading technology will deliver today’s outstanding battery management systems. And it build on an expanding base of innovation to advance the future of leading-edge systems.

erintse

I am Erin Tse, working in a company EmbedIC, which is the one of the best world Electronic Component distributors with over 100,000 different kinds of electronic components.

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