Premium (IEC IE3 Class) efficiency Motors are now mandatory in North America. Super-Premium (IEC IE4 Class) and IE5 Ultra-Premium efficiency classes are defined in the second edition of Standard IEC 60034-30. For line-start fixed-speed applications, Super-Premium IE4-Class Line-Start Permanent-Magnet Motors and Squirrel-Cage Induction Motors are recent entrances in the industrial motor market. For variable-speed applications, IE4-Class Variable-Reluctance Synchronous Motors are also a recent entrance in the market. For the low power range, moving from IE4 to IE5 class, may require moving away from radial-flux induction motor technology, into to the permanent magnet and reluctance technology, either using Rare-Earth or Ferrite magnets. In this paper, efficiency analysis on the best available electric motors and emerging motor technologies, such as axial-flux permanent-magnet synchronous motors, is presented. The potential efficiency gain associated with several design options as well as a study on the theoretical efficiency limit achievable taking into account those existing design options are described.

Beyond induction motors — Technology trends to move up efficiency

A comprehensive review on energy efficiency enhancement initiatives in centrifugal pumping system

High-efficiency electric drive systems claim not only optimally designed electric machines but also efficiency-oriented control strategies. Taking machines and drives into synergetic consideration, this paper proposes a novel vector control algorithm named maximum efficiency per ampere (MEPA) control, aiming to maximize the efficiency of permanent-magnet synchronous machines (PMSMs) during operation. Different from conventional $i_{d} =0$ or maximum torque per ampere control, MEPA fully considers the cross effect and iron loss from which the full-order loss model of PMSMs is built. Due to the proposed concise and accurate analytical approach to iron loss calculation, the optimal current phasor angle for MEPA can be quickly found, and the estimation of efficiency is consistent with measurement. Comparison among different control algorithms is drawn from both analytical and experimental results, from which the effectiveness of MEPA is verified.

Maximum Efficiency Per Ampere Control of Permanent-Magnet Synchronous Machines

Premium efficiency motors are now mandatory in North America, but new higher efficiency classes are being introduced. Motors of IE4 Super-Premium Efficiency Class are already available in the market, and a new IE5 Ultra-Premium Efficiency Class is being considered. Within the IE4 Super-Premium Class, line-start permanent-magnet motors (LSPMs) are a recent entrance in the industrial motor market. Its steady-state performance is outstanding, but as in all technologies, there are some associated issues, both for retrofitting or new applications. The LSPM efficiency can be measured according to the input-output (or direct) method specified in the IEEE 112 or IEC 60034-2-1 standards, but if the losses are to be segregated, for example, to allow proper temperature correction, it is important to evaluate if the specified test methods can be applied to this sort of machine. Due to the significant promotion and penetration of variable-speed drives (VSDs) in industrial motor driven systems, the motor tolerance and operation limits to such devices are addressed in this paper. The proposed IEC 60034-2-3 Standard specifies test methods for determining harmonic losses of VSD-fed motors, supplementing the methods intended for operation on sinusoidal supply. In this paper, the referred issues will be addressed in detail, and experimental results on the application of the IEC 60034-2-1 and IEC 60034-2-3 standards to IE2, IE3, and IE4 class motors are presented and discussed, with the focus on the LSPM Super-Premium technology. A comparative technical and economical analysis of commercial IE2, IE3, and IE4 class motors is presented, including an in-field example of replacement of a squirrel-cage induction motor by an LSPM.

Technical and economical considerations on super high-efficiency three-phase motors

Electronic variable-speed drives (VSDs) can produce large energy and environmental savings in variable-load variable-speed applications when compared with other conventional technologies. There are a very large number of applications (e.g., fluid motion, materials handling, and materials processing) which would benefit, both in terms of process improvement and energy savings, through the use of speed control. Previous studies have shown that the variable-flow fluid motion applications (pumps, fans, and compressors) have the largest savings potential. In this paper, an ecodesign analysis of two different technologies for the flow regulation in pumping systems - constant-speed pump with an output throttle valve (motor directly fed from the line) and variable-speed pump without an output throttle valve (motor fed by a variable-speed drive) - is presented. A European standard methodology for the ecodesign analysis of energy-using products is used in this paper. This paper includes a comparative analysis of the environmental impacts and life-cycle costs. The identified large environmental benefits on top of the energy savings provide a strong argument for an increased use of VSDs. The presented analysis is of major importance for industrial electronics manufacturers, designers, and users, widening their awareness to the importance of taking into account the energy and environmental issues when evaluating different system design options.

Ecoanalysis of Variable-Speed Drives for Flow Regulation in Pumping Systems

In this article, feasible minimum limits for IE4 class are analyzed, taking into account the estimated efficiency limits and rated efficiency for emergent or commercially best available line-start PMSM technologies. The presented results can be useful to set up future international standard super-premium or IE4-class levels/limits. The practicability and technical limits associated with the IE4-class efficiency levels are addressed, taking into account technical and economical limitations. It is expected that advanced technologies will enable manufacturers to design motors for the IE4-class efficiency levels, with mechanical dimensions compatible with the existing IMs of lower efficiency classes (e.g., flanges, shaft heights, or frame sizes as defined in standards EN 50347 and NEMA MG1). NEMA frames sizes are larger than the IEC frame sizes, allowing the use of more active materials. In addition, 60-Hz operation enables higher power density and higher efficiency levels with the same frame sizes.

Standards for Efficiency of Electric Motors

Higher efficiency electric motors can lead to significant reductions in the energy consumption and also reduce the environmental impact. In order to promote a competitive motor market transformation, a new international standard, the IEC 60034–30 has been approved. This standard globally harmonizes motor energy-efficiency classes in general-purpose, line-fed, three-phase, squirrel-cage, induction motors (IMs). In this standard, four efficiency classes are proposed, namely Standard Efficiency (IE1), High-Efficiency (IE2) equivalent to EPAct, Premium Efficiency (IE3) equivalent to NEMA Premium and Super-Premium Efficiency (IE4). IE1, IE2 and IE3 classes were normative, and IE4 class was intended to be informative, since no sufficient market and technological information is available to allow IE4 standardization. The IE4 Super-Premium class, under discussion, can be applied both to line-fed motors and to inverter plus motor units. In fact, for low-power levels (up to 10 hp) it is clear that moving away from IM technology, and considering emergent or best-available technologies such as permanent-magnet synchronous motors (PMSMs) can achieve efficiency levels considerably significantly higher than those defined by Premium IE3 class. In this paper, feasible limits for IE4 class are analysed taking into account the efficiency levels of commercial and expected best available technology. The presented results can be useful to define future international standard “Super-Premium” or IE4-class levels as well as to set market transformation strategies.

Joao A. C. Fong

Papers

Standards for Efficiency of Electric Motors

Standards for Super-Premium Efficiency class for electric motors