Electronic Design
Viable Mass Electric Transportation Needs A Systems Approach

Viable Mass Electric Transportation Needs A Systems Approach

A few decades ago, we believed we would be living in cities above the clouds and commuting in flying electric-powered vehicles someday, as popularized by the cartoon show The Jetsons. For some reason, though, we aren’t. Why not? Overlooking for a moment the inevitable delays caused by legal, regulatory, and governmental intervention, it’s because we lack the infrastructure, economics, and inertia to support that futuristic lifestyle.

Also, and equally importantly, we don’t look at the big, complete picture right from the start. When business parks and housing developments are built, they seldom have the infrastructure to support their long-term growth. For example, we don’t upgrade our roads until traffic is congested enough to overload what’s already there and we have enough data to warrant tearing them up and expanding them. It seems to be how people operate—with little or no advanced planning. 

The EV Conundrum

The electric vehicle (EV) market is a lot like road construction. First, the market won’t see mainstream success without modifications to our infrastructure, which will include upgrading the power delivery system. That’s because there are more than 120,000 filling stations in the U.S. with a significant supply-chain infrastructure to deliver fuel.

Unless the physical replacement for gasoline is faster to distribute and cheaper to make, and unless it’s some kind of liquid fuel like gasoline, its adoption is going to take a long time. That means this replacement should look a lot like, well, gasoline—but it also should be better for us all somehow and sustainable. At first glance, the EV looks like the instant winner for weaning us off hydrocarbon-based fuels.

However, the EV may simply push the problem to a different location. Coal provides almost 50% of U.S. power plant fuels. Due to the economics of coal, this share likely will increase. Recharging your electric vehicle, then, probably will require hydrocarbon-based non-sustainable or non-renewable resources depending on where you live. If a lot of people simultaneously have their EVs plugged in, the coal plants will have to work very hard to recharge them.

Even so, let’s say 100% of the power where you live is nuclear, solar, wind, geothermal, or hydroelectric—as sustainable and as green as we can make it. But still, what happens when everyone comes home from work with their electric vehicles and plugs them in at the same time? As engineers we must consider this worst-case situation and still make the system work.

Think of the energy delivery rate of those 120,000 filling stations. Can we increase the grid enough to match that? Approximately 6% to 8% of the energy generated is wasted as heat getting to your electric vehicle, so losses are high to start with.

Once this energy is delivered, and everyone on your street plugs in their EV at once, the breaker protecting the transformer on your street is going to cut out. If enough people plug in at the same time, the EVs will take out the grid as it exists today because plugging one EV in to recharge is like adding one new house to the grid. How soon do we think the electric companies will be installing new power services at their expense on your block to accommodate EVs?

I’m not going to even get into the cost and disposal issues of EV batteries here, but let’s just say we can overcome all of them with enough R&D dollars. The good news for power electronics is that various technologies our industry is developing separately, if implemented together, actually may have a chance to support the needed infrastructure.

The Electric Ruins

Here around Phoenix, Ariz., I see rows of EV refueling stations left over from the 1990s when General Motors developed the EV1 (see the figure). The cars had lead-acid and nickel-hydride batteries that needed to be recharged. Outlets were wired into buildings in the area, and these recharging stations stand as distinct reminders of something we thought would take off yet didn’t.

These stations cost someone real money. They stand today taunting us like Mayan ruins reminding us to be careful not to implement new technologies too quickly. If some archeologists uncover these charging stations in the future, they may wonder what they were and what we did with them.

In fact, they were installed too early. We weren’t even discussing the Smart Grid or alternative energy sources or thinking about EVs at a systems level then. Since the grid as it stands today can’t accommodate very many EVs and I don’t anticipate the electric utilities installing something else, we have to use what we have more efficiently.

The utility must be able to recoup its investment by saving or making money from the installation. For instance, energy theft is estimated to be a $6 billion problem in the U.S. It’s a big issue in India and other parts of the world too. To put this in perspective, credit card fraud is about an $11 billion problem in the U.S., and auto theft is approximately an $8 billion issue.

Many of the Smart Grid initiatives are all about reducing or eliminating energy theft via anti-tampering technologies. If we can also install some system-level intelligence in the Smart Grid to monitor the load conditions and the time of day where available capacity can be used to charge EVs, then we will be on to a solution that won’t cost billions to install unless absolutely necessary, and the payback model is there. 

We are going to see a progression here. In the near term, we’ll have a not-so-dumb grid. After that we’ll have an incrementally more intelligent grid. Then maybe 10 years after that we will have the Smart Grid. Keep in mind that change like this, especially in the utility business, takes a very long time even when the industry is in a hurry!

Potential Solutions

We need to combine existing wired and wireless communications, smart metering, and microprocessor-controlled power electronics in our charging systems. Recent developments in digitally controlled power supplies enable the power system to interact with a processor. They also let the processor control the power supply and read telemetry data from it for measurement and control.

The EV will be able to communicate its energy needs and the time of day to the grid via wireless technologies such as cellular or ZigBee. The utility can use this data to determine the off-peak load it can accommodate and deliver energy by controlling the charging, using power electronics on board the EV so you and your neighbors don’t overload the system. A processor will interactively communicate with and control the power-supply system while reading and reporting data.

One of the recent developments of digitally controlled power supplies, Exar’s Power technology, allows the power system to interact with a processor. It also enables the processor to control the system power supply and read telemetry data from the power supply so measurement and control can take place.

While we have more than 120,000 filling stations in the U.S., we will need to invest proportionally in smart power electronics, communications technologies, smart metering, and Smart Grid technologies too. This is all very good for us in the power electronics community, because the infrastructure isn’t going to work without this technology.

What remains to be seen is if consumers will tolerate not having the instant gratification of filling up their vehicle in minutes and being able to hit the road when they want to. With the exception of public 480-V Level 3 fast charging stations, which haven’t seen widespread deployment yet, charging an EV takes time regardless of how efficient, smart, and viable it is. Hopefully with the appropriate application of technology, our future will look like the Jetsons and not like the Flintstones!

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