Design Solutions April 2022

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FEATURE

POWER

The power of harmonic filTers

The adoption of electric vehicles is

growing, but with a greater number of charging points needed, what impact will this have on electricity

consumption? Steve Hughes, managing director of REO UK, looks into how

technologies like harmonic filters will help B

etween 2019 and 2020, electricity demand for road transport is estimated to have increased by 50% in the UK, according to a

government report on energy consumption. In fact according to Next Green Car, in the UK electric passenger car sales increased by 74% in 2020. But with the ban on the sale of new petrol

and diesel cars set for 2030, there is expected to be a huge increase in electric vehicles (EV) and therefore a greater number of charging stations needed. But is the National Grid powerful enough to handle this? The National Grid reported average cold spell

(ACS) demand peaking at 58GW in 2020/21, with this rising to 59.5GW in the following two years. To balance electricity supply and demand close to real-time, it uses the balancing mechanism. When a discrepancy is predicted in the amount of electricity produced and the amount demanded, the National Grid can either accept a ‘bid’ or ‘offer’ to increase or decrease generation. This is necessary as demand for electricity rises and falls depending on temperature, current events and time of day. The balancing mechanism can be illustrated

by the TV pick-up effect, where a major TV event draws large audiences and produces a surge in electricity demand during breaks as viewers operate electrical devices like kettles and microwaves. For example, during the England vs Germany EURO 2020 match, there was a 1GW hike in electricity demand at half- time and a 1.6GW hike after full-time. According to an article in Forbes, sceptics

of electric cars argue that if all the UK’s 32.7 million cars were electric, they would need 229GW to fully charge, despite the National Grid’s capacity being 75.8GW in 2020. However, this calculation makes the assumption that all cars will be charging at the exact same time. One solution could be incentivising off-peak charging or giving discounted rates to those who charge overnight instead of during the day. However, the balancing mechanism cannot

solve more technical issues like complex waveforms and harmonics.

3 design solutions APRIL 2022 8 harmonic filTers

EVs require various power electronics equipment that convert AC power to DC for vehicle systems like heating and ventilation. Harmonics are unwanted higher frequencies that create a distorted wave pattern that can lead to the overheating of conductors and cause faults in the operations of protection relays. These failures have a knock-on effect and can create problems for the wider grid, causing blackouts, particularly in small and densely populated areas. One way to reduce the total harmonic

distortion (THD) in the EV charging system is to use harmonic filters, which are often active, passive or hybrid. Active harmonic filters monitor harmonic currents and generate corresponding waveforms to counter the original harmonic current; passive harmonic filters use inductors

and capacitors to shunt or block harmonics. Harmonic filters can offer a number of benefits.

Those produced by REO, for example, can reduce the THD to less than 5%. They are also capable of reducing the power bill and maintenance costs for EV charger owners. Overall, they can improve energy efficiency and power quality. So, while the adoption of EVs is increasing, it

is at a pace where the National Grid will have time to grow with this demand. Minimising the risks of a power outage can be achieved by incentivising off-peak charging, making use of the balancing mechanism, and using technologies like harmonic filters to reduce THD.

reo (uK) t: 01588 673411 www.reo.co.uk

new power supply design uses gan hemt devices to achieve 95% efficiencies

Innoscience Technology has announced a new ultra-high density 140W power supply demo that uses its high- and low-voltage GaN HEMT devices to achieve efficiencies of over 95% (230VAC; 5V/28A). Measuring just 60 x 60 x 22mm (2.4 x 2.4 x 0.9in) the PSU is said to have a class-leading power density of 1.76W/cm3

(29W/in3 ). The 140W 300kHz AC/DC adapter uses a CRM Totem Pole PFC + AHB

topology. It features Innoscience’s INN650DA140A, a 650V /140mΩ GaN HEMT in the 5 x 6mm DFN package, for switches S1 and S2, the 650V/240mΩ, 8 x 8mm DFN-packaged INN650D240A for S3, and the INN650DA240A, a 5 x 6mm DFN 650V/240mΩ device for S4. S5 and S6 are delivered by the INN150LA070A, a 150V/7mΩ, 2.2 x 3.2mm LGA part within Innoscience’s low-voltage GaN HEMT range. Dr. Denis Marcon, general manager of Innoscience Europe and marketing manager for the

USA and Europe, commented: “By using GaN switches for both the high- and low-voltage functions on this design, we are maximising efficiency rather than compromising it with lossy silicon devices. This is possible thanks to Innoscience’s cost-effective and high-volume manufacturing processes and capabilities.” Yi Sun, general manager of Innoscience America and Sr VP of Product and Engineering added:

“This design, which targets USB PD3.1 notebooks and power tools, is a full 2% more efficient than silicon designs. This proves what can be achieved if GaN FETs are used everywhere, even in a relatively simple design.”

innoscience technology www.innoscience.com

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