AC or BLDC. What motor type would you use on your next machine?

With the European Commission Regulation (EU) 2019/1781 (ecodesign requirements for electric motors and speed control systems), new minimum efficiencies for electric motors will be prescribed from July 1, 2021 – Helping you select the best technology to make your machine extremely efficient.

Operating efficiency has a very significant effect on running costs, with a typical IE2, asynchronous AC motor consuming 100 times its purchase price in electricity costs within its lifetime. Nevertheless, Engineers have several options driven by the trend in recent years to improve throughput, reduce maintenance and achieve a higher return on investment (ROI) within a smaller footprint.In some intermittent or light duty applications, it is still more economical to specify a standard AC or brushed DC motor. However, if the duty cycle is higher, then a BLDC motor can quickly meet and exceed its ROI target.

In short, the minimum efficiency level IE2 will then apply to 50/60-Hz three-phase motors (2, 4, 6 or 8 poles) from 0.12 kW and the minimum efficiency level IE3 from 0.75 kW rated output power. The tables for determining the IE classes as well as numerous exceptions and detailed regulations can be found in the regulation.

Dunkermotoren customers can sleep easy as none of the Dunkermotoren range are affected by the requirements. As an example, the BG xx dPro EC motors with integrated motion controller already meet the demanding requirements of the highest energy efficiency classification for electric motors - the Ultra Premium Efficiency Class IE5. In the nominal power range, the motors, together with the integrated control electronics, achieve an efficiency of over 90%, far exceeding the requirements.

An AC motor generally consumes more energy by simply having to produce a magnetic field by inducing a current into the rotor where a BLDC motor, electronically communicated (EC) motor, uses permanent magnets giving it an inherent efficiency advantage. Consequently, AC motors are less efficient than BLDC motors due to the rotor magnetic field being generated from the permanent magnets instead of the copper windings. The BLDC electronics switch the phases in the fixed windings to keep the motor turning and constant analysis of the load angle by the electronics ensures energy-efficient operation, low noise and a reduction in comparable size to an AC motor with no requirement for external fan cooling.