FULL SPEED AHEAD
Electric vehicles (EVs) and the wider electric transportation has gone from strength to strength in the past decade. Over the next five years, a total of eight million drivers in the UK will switch to hybrid and electric vehicles (HEVs) according to CompareTheMarket, driving demand for robust charging infrastructure. Here, Steve Hughes, managing director of transport power quality specialist REO UK, explores how the industry is shaping up for the 2020s
• • • ELECTRIC VEHICLES • • •
registered in the UK. By the close of the decade, this number had risen to approximately 255,000. There are several factors steering this change. For
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automotive manufacturers, it’s becoming cheaper to manufacture EVs due to reduced component costs, substantial developments in battery technology and wider availability of large-volume manufacturing for parts such as powertrains. According to Bloomberg NEF, the accelerating rate of these changes will make EVs cheaper upfront than combustion vehicles by as soon as 2022. Then of course there are the environmental
factors, in terms of air pollution and carbon emissions. EVs are widely seen to be cleaner alternatives to conventional vehicles due to the substantial difference in carbon emissions from use, with EVs generating only 42 per cent of the carbon emissions of a conventional vehicle. Although EV manufacturing has attracted criticism from detractors for producing more carbon emissions — 15 per cent according to a report by The Union of Concerned Scientists — than their gasoline-powered counterparts, these differences disappear when EVs are in operation.
CHARGING: FASTER BUT LONGER
The growing adoption of EVs is an undeniable win for environmentalists, but it is something of a double-edged sword for energy systems operators and electrical experts going into 2020. EV charging points are split into three main categories: slow, fast and rapid. Slow chargers,
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Vs have proven themselves to be one of the top technological success stories of the early 21st century so far. In 2013, a mere 3,500 EVs were
which typically are rated up to 3 kW, are best suited for home charging as they can take 6–12 hours to fully recharge. Fast charging units are rated either 7 kW or 22 kW depending on whether they are single- or three-phase. Rapid charging, as the name implies, is the fastest. Units are generally rated 43 kW for alternating current (AC) units or 50 kW and above for direct current (DC) chargers. Understandably, users want the fastest charging experience possible. It’s for this reason that many automotive manufacturers are investing heavily in developing faster charging infrastructure, such as Porsche’s electric pit stop that promises to suitably charge EV batteries in as little as 20 minutes. This trend for faster charging points comes as no surprise. It’s very possible that slow charging points will largely disappear over the next few years in favour of 7 kW units. This will likely be a slow process as several EV models are only now moving to onboard chargers capable of effectively using 7 kW. Latest models of the Nissan Leaf, for example, have onboard chargers with a capacity of 6.6 kW — almost able to make full use of the 7 kW capacity of a fast point.
GRID STRAIN
If we imagine that hundreds of thousands of electric vehicles plug in to charge at units rated between 7 and 43 kW, it becomes apparent that grid infrastructure must be robust to handle the demand. However, it becomes more complicated when we
account for the rectification that must take place to convert the AC power of many charging points to the DC required for EV batteries. This process introduces harmonic currents into the mains AC
signal that, if left untreated, cause higher losses, signal interference and accelerated electrical component wear — none of which are ideal for any connected devices, let alone charging EVs. This is arguably the biggest challenge facing the
adoption of EVs and the growing usage of EV charging infrastructure, and it’s one that we explore in detail in our recent eBook R30. Unless these harmonic currents are accounted for and mitigated, the electrical grid will face a harmfully noisy electrical signal on top of sudden surges in demand. Fortunately, electrical contractors can play a crucial
role in minimising the risk by ensuring that any EV charging projects include suitable harmonic filtration components in the surrounding infrastructure. For example, installing one of REO UK’s mains line filters or harmonic filters ensures that harmful currents are attenuated and filtered out to avoid damaging the integrity of the mains power. The inclusion of filtering components seems like a
common sense solution, yet it remains one that can make a significant difference in overcoming one of the fundamental challenges in EV adoption. In fact, we believe that the consideration of such harmonic mitigation strategies at a grid level will be a key trend in EV infrastructure over the coming years. If we are to see eight million drivers make the
jump to EVs in the next five years, we must begin to reinforce our infrastructure now to cope with demand. 2020 will be in a pivotal year in ensuring charging infrastructure is up scratch to meet user expectations, both in terms of charging speed and overall system reliability.
REO UK 01588 673 411
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ELECTRICAL ENGINEERING • NOVEMBER 2020 21
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