Enabled by semiconductor technology, vehicle-to-grid (V2G) bidirectional charging can provide battery power to reinforce electric grids during peak demand and power your home when electricity is expensive or out

23 Aug 2022
 

Our wide-bandgap power, sensing and connectivity technologies enable engineers to make V2G energy storage a reality, contributing to more sustainable, efficient and affordable energy management 

Aging electric grids face unprecedented demand around the world and the strain may only grow with vehicle electrification. But what if electric vehicles (EVs) could ease the burden by returning power to the grid?

The concept — known as vehicle-to-grid, or V2G — envisions fleets of EVs providing battery power to reinforce electric grids, particularly during peak demand. The vision is gaining traction as new charging and battery-storage solutions emerge and proven technologies are redeployed.

It is also driven by environmental goals as countries strive to reduce emissions and increase renewable energy sources. While vehicle electrification is part of that journey, managing the power demands of millions of EV owners will be a challenge. The energy required to drive the average EV 100 miles is about the same amount needed to power the average home each day. If everyone charges up at the same time, grids could face serious stress.

“The problem is not the overall capacity of the grid," said Henrik Mannesson, our company’s general manager for grid infrastructure. "It is the peak capacity of the grid that is the challenge. We all know these peaks are getting higher and coming more often as we grow more reliant on power. Extreme weather events add more strain on the grid. With semiconductor technology, V2G bidirectional charging could smooth out these peaks, which would benefit us all."

Semiconductor technologies that enable bidirectional charging can turn EVs and their batteries into energy storage systems that can return power to the grid when required. Wide-bandgap power management, sensing and connectivity technologies can ensure a more reliable, smarter and safer grid by optimizing power load management, potentially paving the way for the expansion of renewable energy sources.

GaN enables faster, more energy-efficient charging

One of the building blocks for creating more efficient V2G solutions is wide-bandgap technology like gallium nitride (GaN). GaN effectively triples the power density — the amount of power managed in a given form factor — of the power supply or power management system in applications such as on-board chargers in EVs, EV charging stations and energy storage systems, compared to traditional silicon devices. That translates into designs with faster charging, reduced system size and lower cost of ownership.

"GaN helps engineers achieve triple the power density of conventional transistors and significantly reduces the size and cost of applications like DC wallboxes,” said David Snook, a manager for GaN products at our company. "Size and weight reduction are the exciting things about GaN for these applications."

Smaller and lighter charging stations enable more flexibility, allowing grid operators to roll them out to more places more easily. And more portable systems, such as DC wallboxes, also mean more convenience at home for EV owners to recharge or power their home when needed.

Current sensing technology brings energy savings

Sensing technology is also key in the pursuit of efficiency when moving energy between EVs and the grid. To implement the voltage and current control loops in power conversion systems, microcontrollers need isolated, fast and accurate voltage and current readings. Our isolated amplifier and analog-to-digital converter (ADC) portfolios work with small current shunt resistors to lower power dissipation and enable high resolution measurements, allowing accurate control when power is returned to the grid.

“Accurate current sensing enables us to turn energy storage in batteries into AC (alternating current) that the grid can use," said Navin Kommaraju, who manages our isolated ADC and amplifier portfolio.

Vehicle-to-grid bidirectional charging diagram

Monitoring the “state of charge” helps EV owners manage their energy more effectively. An accurate monitor can help get up to 20% more capacity out of a battery without risking permanent damage to the cells. For example, some EV owners may not need to keep their cars’ batteries fully charged all the time if they are only commuting to work. The increased accuracy of smart sensing technologies could enable the EV to alert owners about the best time to return power to the grid or charge up their homes. 

While efficiency is important, safety is paramount in producing V2G solutions. EV owners need assurance that shifting power to and from their EVs will be reliable and consistent. Along with sensing technology, battery-management systems can help monitor the “state of health” of batteries by managing the voltage, current, temperature and other performance metrics.

“The battery management system is the first line of defense," said Spencer Hu, who manages automotive battery monitoring products at our company. “If the battery is not healthy, owners may not want to hook it up to the grid because it could accelerate the aging of the battery, which would eventually affect the driving range."

Advanced connectivity solutions to manage power loads

Transforming V2G from concept into reality is ultimately a data-driven undertaking that will require smart communications between EVs, the charging infrastructure and the grid. Advanced connectivity solutions and smart energy metering will be paramount for grid operators to anticipate and adjust the power load required by EVs at different times, places and scenarios. Billing owners for charging their EVs, or compensating them for returning power to the grid, will require reliable and secure real-time communications on a massive scale.

EV owners, meanwhile, will need smart human-machine interfaces (HMIs) like displays and touch-pads that can connect via various protocols, whether Wi-Fi®, Bluetooth® or Sub-1 GHz. Managing a wide variety of communication interfaces while ensuring a high-quality user experience during charging will require application processors that handle multiple functions on a single chip. Our Sitara™ AM62 processors act as a central decision-maker in managing communication across the spectrum of human-machine and EV-to-charger interfaces and communication between charging stations and the cloud. And they enable engineers to meet global standards and protocols for V2G communications such as ISO15118 Plug & Charge and Open Charge Point Protocol (OCPP).

Processors like the AM62 will enable grid operators to optimize power load management, while simultaneously informing EV drivers through smart HMI as to the best time to charge up or return power to the grid. Processors with edge AI features also pave the way for more intelligence to be built into the grid as V2G data is collected over time.

"We can layer AI on top to look for patterns across a year of data," said Artem Aginskiy, our product line manager for Sitara processors. "It could predict the best place to charge tomorrow based on how the grid and chargers are behaving today."

Semiconductor technology can turn V2G into reality

Some events, such as power outages, are harder to predict, but EV users will still stand to benefit from semiconductor technology when the lights go out at home. The same innovations in connectivity that underpin V2G will allow their cars’ batteries to power their homes during disruptions. Such vehicle-to-home (V2H) solutions will complement bidirectional charging between homes and the grid via solar cells and battery storage systems, potentially spurring the adoption of renewable energy sources.

Building infrastructure to drive vehicle electrification will take time. From a technology standpoint, however, the pieces are all in place. The environmental benefits of V2G, through more efficient power-load management, are also compelling.

“Semiconductor technology can help the grid cope with the power needs that come with vehicle electrification," said Henrik. “Smart solutions, meanwhile, can make it easier for EV users to send the power back to the grid."

A passion to create a better world

Helping engineers make V2G energy storage solutions a reality is just one way our innovators are living our company’s passion to create a better world by making electronics more affordable through semiconductors. Each generation of innovation builds upon the last to make technology smaller, more efficient, more reliable and more affordable. We think of this as Engineering Progress. It’s what we do and have been doing for decades.