Power electronics: the hidden technology that makes the modern world run

2013-05-14 - The systems and machines of the modern world increasingly depend on power electronics to run efficiently and sustainably. Without this technology, electric motors would always run at full speed and renewables, such as solar and wind power, could not be fed into the electricity grid.

By ABB Communications

Around 40 percent of the world’s power needs are currently met by electrical energy and that proportion is expected to rise as countries cut carbon emissions and shift to renewable energy sources. As the trend towards electrification and renewable energies increases, enabling technologies such as power electronics are becoming ever more important.

Power electronics is an umbrella term that encompasses the systems and products involved in converting and controlling the flow of electrical energy. Simply charging a laptop, for example, requires modifying the alternating-current (AC) voltage from the electricity mains to a lower voltage direct current (DC). And if that current originally came from a solar panel, it will have already been converted from DC voltage to the (European) standard 230 volts, 50 hertz AC voltage, using a power electronics-based converter called a solar inverter.

Motor drives
The traditional application area of power electronics is variable speed drives for electrical motors. Power-electronics technologies are able to vary the speed of motor drives, making processes more efficient and reducing the amount of energy consumed. An obvious example is heating, ventilation and air conditioning (HVAC) systems. Without power-electronics inverters, the motors running these systems would continually be running at full throttle, consuming vast amounts of unnecessary energy.

Variable speed drives slow down or speed up motors, depending on the load of work that must be performed. They also control the process to ensure a consistent level of quality. Applied to HVAC systems, machinery in factories, and on planes, trains and ships, the motors deliver precisely the right amount of power needed at any given time, conserving energy and also permitting trains and elevators to accelerate and decelerate gently.

In electric vehicles, power electronics allows braking energy to be stored and supplied to the battery as needed
Electric vehicles
Electrification is opening up more applications for power electronics such as drive trains for electric vehicles (EVs) and hybrids, as well as DC fast-charging stations, which can charge EV batteries in a matter of 15-30 minutes, compared with the many hours it takes using standard residential charging ports. In the case of electric vehicles, power electronics can be used to store braking energy and to supply it back to the battery as needed.

Data centers
Another area where power electronics can deliver significant energy savings is data centers, which now account for over two percent of electricity consumption in the US and Europe. More than a third of the energy used in data centers goes on cooling. By applying variable speed drives to air conditioners and pumps, the speed of these systems can be adjusted to match the amount of cooling needed. The resulting energy savings are substantial: a (centrifugal) pump or fan running at 80% speed, for instance, consumes only half as much energy as a unit running at full speed.

Efficient electricity transmission
As well as variable drives to control the speed of motors, power electronics makes it possible to transport electricity over huge distances with minimal losses. This is accomplished by power-electronics converters, which transform alternating current (AC) into high-voltage direct current (HVDC) and vice-versa.

Being able to convert current is important because while power stations generate AC and the power delivered to consumers is also AC, HVDC is better for transmitting electricity, especially underground and under the sea. One reason is environmental – an HVDC transmission line is much smaller and needs less space than AC lines for the same power capacity – the other has to do with control over the power flow. A third reason HVDC is useful is because it can be used to connect power from different systems, such as wind turbines and solar panels.

In the case of solar energy, power-electronics inverters make it possible to transform DC energy produced by a solar panel into AC, which can then be fed into a commercial electricity grid. A similar conversion from DC to AC is needed for wind energy, which must also be fed into the grid at a constant frequency, despite fluctuating wind conditions.

The electronics behind the power
The core technology behind power electronics is the power semiconductor. One of the world’s most important competence clusters for power electronics is run by ABB in Switzerland, where the company develops and manufactures semiconductors and integrates them into power electronics-based products and systems.

ABB currently has around 1,800 employees working in its power electronics cluster in Switzerland. In March 2013, ABB announced plans to expand its research laboratory with an 18 million Swiss franc ($19 million) facility in Dättwil, Switzerland, to develop the next generation of power semiconductors.

As this article has highlighted, such investments make sense both technologically and commercially because the world is increasingly relying on electricity from diverse energy sources, and power electronics is the key technology when it comes to efficiently running electrical motors.

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    Power semiconductors, the core technology in power electronics, are manufactured by ABB in Lenzburg, Switzerland
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