Electric motors

Electric motors are used in almost all buildings, industries, and infrastructure. In fact, they are the largest individual consumers of electricity worldwide. According to the European Commission’s estimates, around eight billion electric motors are in use in Europe alone. Consuming almost 50 per cent of the electricity generated in the EU.

Modernising the world’s motors is essential in the fight against climate change. It will reduce the world’s carbon footprint. Imagine adding seven new Amazon rainforests to the world,” says Ryan Morris, Chairman and CEO of electric-motor manufacturer Turntide Technologies. Turntide has developed a variable-speed motor around 25 per cent more efficient than conventional motors. By combining cutting-edge computer and software control with a switched reluctance motor. Customers have boosted the efficiency of their heating, ventilation, and air-conditioning systems by 65 per cent. This was done, by replacing old, fixed-speed motors with Turntide’s variable-speed models.

Electricity savings of ten per cent

Independent research results show that global electricity demand could be reduced by up to ten per cent. And all of this, by switching inefficient motors for optimised, highly efficient systems. “It is impossible to overestimate the contribution that industry and infrastructure making the switch to these extremely energy-efficient motors. And drive systems would make to a more sustainable society,” emphasises Morten Wierod, President of the Motion Business Area at ABB.

All over the world, there are varying legal requirements and regulatory framework conditions. They should increase the energy efficiency of electric motors. In the European Union, for example, there is the Ecodesign Directive (EU 2019/1781) with strict requirements for the energy efficiency of motors and variable-speed systems. The aim of this directive is to save 110 terawatt-hours annually by 2030. Which is roughly the amount of electricity consumed by the Netherlands. So this would avoid emitting 40 million tonnes of CO2 a year. And also trim annual energy costs for households and industry in the EU by around 20 billion euros by 2030. When it comes to electric motors, the directive differentiates between four efficiency classes. Whose current thresholds range from IE1 (the lowest class) to IE4. As for the motors, various IE classes are defined for inverters, and IES classes for motor-inverter combinations.

Varying speed for higher efficiency

However, the use of high-efficiency components only provides a basis for a drive system that consumes as little energy as possible. The greatest potential can only be leveraged if the design and movement profiles correspond to the actual process requirements. The use of inverters to adapt the power or the infeed of braking energy into the intermediate circuit are further options for optimisation. Variable-speed motors can reduce energy consumption by 30 to 50 per cent by supplying the exact amount of power actually needed.

To name one example, sausage maker Rügenwalder Mühle has replaced the fan motors for its 30 smoking chambers with cutting-edge IE4 packages from ABB. Instead of the old, two-stage, pole-changing asynchronous motors, the fans are now driven by a combination comprising a synchronous reluctance motor and frequency inverter. The motor contains a rotor that does away with magnets or coils, unlike conventional synchronous-motor designs. Power losses due to the rotor, which make up around 40 per cent of an electric motor’s energy losses, are almost entirely avoided for this reason. And enabling total energy savings of almost 50 per cent. For Rügenwalder Mühle, this meant that the investment had already paid for itself after a little over a year.

Saving electricity with power electronics

IE4 designs are also found in many other motor types. Whether three-phase asynchronous motors, motors with permanent magnets, or EC  motors. The motors can all be combined with a frequency inverter, enabling them to function as a variable-speed drive system. Some, such as the EC motor or synchronous reluctance motor, essentially also require an electronic controller for operation. As in many areas of the energy landscape, this means that power electronics play a major part. Especially in the overall system’s energy efficiency. As early as several years ago, market analysts at Navigant recommended that wide-bandgap semiconductors should be used in place of conventional semiconductors for this reason. Especially those wide-bandgap semiconductors with a silicon carbide base.

A motor developed by automotive supplier Marelli in collaboration with the Fraunhofer Institute for Reliability and Microintegration (IZM) for Formula E shows just what this material can do. The extremely compact power stage with a silicon carbide base delivers the same power output as a silicon-based design with a conversion efficiency of up to 99.5 per cent. Furthermore, it reduces the weight and size by half. Additionally, it boasts up to 50 per cent more heat dissipation into the cooling system.

“Compared to other focus areas, industrial energy efficiency has the single greatest potential for fighting the climate emergency,” summarises ABB manager Morten Wierod. “It is essentially the invisible solution for the climate problems our world faces.”


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