Energy Efficiency in Motor Systems

Inhaltsverzeichnis

1. Frontmatter

2. Novel Design of Delta-Connected PM Synchronous Machines Considering Rotor Skewing

   Juergen Redlich, Anton Suchan, Bernd Ponick

   Abstract

   In the design process of electrical machines – especially those with challenging performance requirements like traction motors – an individual adaption of the number of turns per phase plays an important role. Choosing a delta-connected winding instead of a Y-connection gives an additional degree of freedom in design. This can be of special importance in case of hairpin windings with their tightly restricted choice of the number of conductors per slot, as it allows to find a better match of flux, rated speed, and given voltage level. Although delta-connected windings are common in low voltage industrial applications, they are still underrepresented in traction applications. This chapter presents the most suitable design options for delta-connected PM synchronous machines and discusses their performance and efficiency in traction applications. Moreover, a new calculation method for a skewed rotor is presented. Instead of FEM calculations of several rotor slices, just one slice needs to be calculated by FEM. The flux density in all other slices is then derived from this result analytically.

3. EC-Motors in a Fan Application: A Case Study

   Kurt Stockman, Jasper De Viaene, Steve Dereyne, Pieter Defreyne

   Abstract

   Since a few years, Electronically Commutated motors (EC-motors) have gained interest in industry and more specifically in industrial fan applications. The EC-motor has become a serious competitor for induction motor speed controlled applications in the lower power ranges (up to several kW). Currently, EC-motors can be driven by standard voltage source frequency converters and come with better efficiency values compared to induction motors in the same power range. In this chapter, first the efficiency of such EC-motors is studied and lab measurements on commercial machines are performed to identify their potential with respect to energy savings. Efficiency/loss maps are presented and compared to those of speed-controlled induction machines. Next, based on this input, a case study on an industrial small fan application is performed. This techno-economic analysis shows the feasibility with respect to energy savings and also addresses the implementation effort and the barriers to convince the more traditional fan industry in order to consider the use of EC-motors in the near future.

4. A Global Update on the Markets for Motors, Drives, and Motor-Driven Equipment

   Preston Reine

   Abstract

   This chapter highlights the findings of the latest analysis by IHS Markit on the global markets for low-voltage (LV) motors, variable frequency drives (VFDs), and motor-driven equipment, such as pumps, fans, and compressors. It will summarize how these markets are segmented by technology, geographic region, industry sector, and other emerging trends. In addition to presenting market data, the presentation will include an analysis of the current competitive environment for these products, including market shares of leading suppliers. A discussion on the impact of recent and impending energy-efficiency regulation initiatives will also be included in this presentation. Specifically, emerging and lesser-used technologies like permanent magnet motors, sensors, and other energy-saving methods will be assessed in order to show how commonplace these promising products are adopted. The main goal of this presentation will be to help the reader understand how much of a disconnect exists between government-led agendas and market-generated demand. Has the Industrial Internet of Things (IIoT) and similar initiatives such as Industry 4.0 become more pressing a topic for end users compared to a more efficient component or even a more efficient motor-driven system?

5. Increasing the Energy Savings of Motor Applications: The Extended Product Approach

   Benno Weis, Benoit Leprettre, Martial Patra, Norbert Hanigovszki, Preben Holm, Tim Schuman, Michael Könen, Niels Bidstrup, Kirk Anderson

   Abstract

   Motor applications account for about 45% of the global electricity consumption and represent one of the greatest opportunities for energy savings. The cost of the energy used by a motor represents about 95% of the Total Cost of Ownership leaving the purchase cost at only about 5%. Therefore, optimizing the energy consumed by motor applications is important to minimize both CO₂ emissions and operational costs.

   However, using energy-efficient components does not guarantee the overall efficiency of the application (or Extended Product). The latter depends essentially on the architecture (which components are implemented) and on the operating point(s) of each component.

   The Extended Product Approach (EPA) developed in the IEC 61800-9 series of standards is a methodology for assessing the energy efficiency of an extended product (i.e., motor system and driven equipment) in the context of an application, considering the actual operating points.

   The main principle of the EPA is to provide means of determining the power losses of all components at any operating point. The resulting losses of the complete application can be calculated by weighting the losses at each operating point with its operating time. This approach is very generic and can be generalized to the other components of the motor application (transmission, mechanical load, process).

   This chapter provides a high-level view of the EPA to stakeholders who are not familiar with it. It also describes how the EPA could be applied to other parts of motor applications (power supply, mechanical components) to provide a consistent framework for assessing overall energy efficiency.

6. High-Efficiency IE4 Line-Start Synchronous Reluctance Motors

   Francesco Parasiliti, Marco Villani

   Abstract

   The demand for energy saving and the new policies on the efficiency of motors for constant speed applications have shifted the interest of designers from conventional induction motors (IMs) towards alternative high-efficiency motors such as the line-start synchronous reluctance motor (LSSynRM). This type of motor is very cost-effective and can compete with the robustness and the low price of the IM. LSSynRM critical aspects are the rough starting transient, limitations in terms of pull-in (synchronization) capability and low power factor. In this chapter, a specific design procedure for LSSynRMs has been used in order to reach the desired balance between the pull-in capability, starting behaviour, and steady-state performance. It is the combination between finite-element (FE) analyses and optimization algorithms. The procedure is applied to design two LSSynRMs, 3 kW-2 pole and 4 kW-4 pole, 400 V, 50 Hz. The simulation results are compared with those of the IMs of the same size. A prototype of the 4 kW-4pole motor has been realized and tested. Then, its performance is presented in comparison with the IM counterpart. The LSSynRM proved to be a cost-effective, mass production-ready solution for super-premium efficiency IE4 motors, and it can effectively replace the conventional IM in a vast panorama of industrial applications.

7. Coordination of IEC and ISO Standards for Energy-Efficient Electric Motor-Driven Systems

   Conrad U. Brunner, Maarten van Werkhoven, Franco Bua, Kirk Anderson

   Abstract

   Electric Motor-Driven Systems (EMDS) are currently responsible for some 53% of global electricity consumption (International Energy Agency, World energy outlook 2016, IEA, Paris, 2016). Optimizing the selection of the respective components (motor control, motor, mechanical equipment, and application) is a strategic prerequisite to realize the energy savings potential at system level; moving the optimization from component level to system level can realize extra energy savings with a factor 2 to 5 (van Werkhoven M, Werle R, Brunner CU (IEA 4E Electric Motor Systems Annex), Policy guidelines for motor driven units, part 1: analysis of standards and regulations, Zurich, Switzerland, 2016; Policy guidelines for motor driven units, part 2: recommendations for aligning standards and regulations for pumps, fans and compressors, Zurich, Switzerland, 2018). The design of the components, their sizing and selection, and their combination to form an optimal motor system together with a well-controlled operation need a system approach to optimize EMDS energy performance. Such system approach is not only needed at design level but also when it comes to standardization.

8. Surface Eddy Current Suppression on Additively Manufactured Solid Rotor Active Parts

   Max Hullmann, Stefan Urbanek, Bernd Ponick

   Abstract

   This paper describes the development process, 3D finite element analysis, and resulting design guidelines for reducing eddy current effects on solid rotor surfaces of electrical machines considering the three-dimensional freedom when designing parts that are suitable for additive manufacturing technologies. Today’s metal additive manufacturing technologies allow the processing of soft magnetic ferrosilicon alloys, which results in solid, non-laminated rotor active parts. With respect to permanent magnet rotors with buried magnets as in the present paper, it is necessary to groove the rotor surface in various manners to suppress eddy current effects. In a first step, a 3D finite element abstracted model, which optimally represents the rotor surface eddy current effects caused by higher spatial harmonics in a permanent magnet synchronous machine, is presented and numerically and analytically examined to find and describe an optimal rotor grooving method, in order to reduce eddy current losses and to derive specific design guidelines. In a second step, a test bench design is presented and numerically investigated in preparation for a validation of the theoretical results.

9. Energy Scorecard: One of the Key Executions to Transform the Market for Energy-Efficient Motors

   Hakan Gedik

   Abstract

   Turkey has an important place in Europe with the market size of 240 billion dollars in low-voltage electric motors. It is also estimated that there are approximately 15 million electric motors in the field. Most of these electric motors used in the field are inefficient motors. The motor regulation applied in Turkey is the same as regulation of European Union. Besides, a project named Promoting Energy-Efficient Motors in SMEs in Turkey that is TEVMOT has been initiated for the replacement of inefficient electric motors used in the field. Thanks to the TEVMOT project implemented by the Directorate-General for Industry and Productivity of the Republic of Turkey Ministry of Industry and Technology in cooperation with the United Nations Development Programme (UNDP) Country Office Turkey with the financial support of Global Environment Facility (GEF), it is desirable to create a sustainable model for the replacement of inefficient motors. In addition to giving full support to this project, Electric Motor Industrialists Association (EMOSAD) recommends the implementation of the energy scorecard model in order for the study to be successful.

10. A Novel Approach to Predict Reed Critical Frequency of Vertical Motors

    Ravi Musinana, Harendra Singh

    Abstract

    Natural frequencies of vertical machines or structures are termed as reed critical frequencies (RCF). They can be termed as the first natural frequency of the vertical machines in transverse direction. Their calculation becomes critical as they can harmonically interact with the driven component leading to resonance condition causing catastrophic failure during operation. This resonance condition can be eliminated by maintaining adequate separation of margin between RCF and operating speed or excitation frequency. As most of the application demands a constant operating speed, the feasible way to avoid resonance is to move the RCF away from the operating speed.

    Presently, few methods of predicting RCF are available. The first such method is to simulate the full motor assembly using finite element analysis with suitable boundary conditions. This method is extensive and sensitive to various factors. The second method as proposed by National Electrical Manufacturers Association (NEMA) treats the motor as a single degree of freedom system and predicts the frequency with static deflection of motor at Centre of Gravity. This method is very rudimentary, and the third method is to perform bump test on machine, which is time consuming and costly for every motor. In industrial applications, motor manufacturer must submit a motor outline drawing with RCF within ±10% accuracy well before the final stage of design. However, neither of these methods gives accurate and cost-effective solutions.

    This work proposes a methodology for predicting RCF of vertical motors on solid foundation considering it as a two degrees of freedom system, by proposing a mathematical model to predict the natural Frequencies of vertical motor by converting the motor geometry into the equivalent simple structures using Timoshenko beam model. The aim of this work is to reduce resources utilized to predict RCF with an accuracy of ±10%. Frequency of different enclosure motors (WP-I, WP-II, TEFC) is simulated using finite element method and the motor simplification is done as a beam with elastic mass attached over it. The study also includes the behavior of the dynamic system with mass and stiffness contribution for different components in the assembly. Finally, the validation with bump test data proves the concept across different frame sizes and enclosures.

11. Evaluation of High-Tech Electrical Steel in a High-Speed Permanent Magnet Synchronous Machine for an Aircraft Application

    Mina Mirzadeh, Gerrit Narjes, Bernd Ponick

    Abstract

    A major design challenge of high-speed high-power machines is the dissipation of heat resulting from the occurring losses. Higher rotational speeds require a high base frequency of 1 kHz. Thus, such a design will have high hysteresis losses and eddy current losses in its iron paths. Thinner electrical sheets and iron alloys with lower specific loss, e.g., cobalt-iron, are used as one countermeasure. However, given the challenge of an aircraft application with the demands for low weight and a small build volume, further aspects such as the difference in density and the heat transfer characteristics have to be considered as well. This paper compares an already existing machine design built with silicon-iron electrical sheets to further iterated designs based on a very thin cobalt-iron material at the same operational conditions. Furthermore, a new machine with higher pole pair number is designed to take advantage of the low loss coefficients and, consequently, make use of a higher operational frequency. The pros and cons of these machines are evaluated using finite element and numerical simulations for electromagnetic and thermal aspects. The results show the advantage of high-tech thin cobalt-iron alloy electrical steels in the field of electrical machines with a high power-to-weight ratio of 10.31 kW/kg for the active part of the machine compared to 7.35 kW/kg using a silicon-iron material.

12. New Life Calculation Model for Hybrid Bearings

    Author Magnus Arvidsson

    Abstract

    Hybrid bearings are bearings with rings made of steel and rolling elements made of ceramic silicon nitride (S_i3N₄). They are used in demanding application conditions, like compressor (Morales-Espejel, GE, Hauleitner R, Wallin HH, Pure refrigerant lubrication technology in oil free centrifugal compressors. SKF Evolution #1, 2017, pp 26–30), pumps and e-motors. Hybrid bearings are also used for their insulating properties. As a non-conductive material, silicon nitride protects the bearing rings from conducting electric current, thereby preventing damage caused by electrical erosion. This can occur if there is a voltage difference between the rotor and the housing.

    Recently SKF introduced the Generalized Bearing Life Model (GBLM), and since then, work has continued focusing on specialized bearings and experimental validation of the model. In order to take the full advantage of all key factors in the bearing selection. SKF has developed life calculation for hybrid bearings. Due to the higher stiffness of the ceramic, the Hertzian contact area is slightly smaller in a hybrid bearing leading to higher contact pressure and subsurface stress compared to a bearing of equivalent geometry made entirely in steel. In principle this should cause a reduction of the fatigue lifetime of the bearing. However, it has been observed that in typical applications hybrid bearings last longer. How to explain this odd behaviour? How to model it? In this paper these questions are addressed; it is also shown that GBLM can model and explain well the observations in the field.

13. Programme for In-Depth Analyses of Electric Motor Systems in Industry (ProAnalySys)

    Richard Phillips

    Abstract

    All Swiss companies are classified into four main categories based on their energy consumption: small, medium, large and very large companies. The first two categories represent less than 3% of the total number of companies, but account for almost two-thirds of Switzerland’s total electricity consumption. For this reason, both the federal government and the cantons stipulated that these companies must reduce their energy consumption. Consequently, they are required to perform an energy audit in order to evaluate their energy-saving potential and thus define a set of efficiency measures that they undertake to implement over a 3-year or up to a 10-year period. However, these audits are quite superficial and do not indicate whether the output of the operated motor systems corresponds to the effective needs. Replacing an existing motor with a premium or even a super-premium model is a simple measure, but it does not give rise to significant electricity savings. Such mandatory energy audits are not sufficient: what is needed is an in-depth analysis during which certain measurements may also be necessary. These in-depth analyses are expensive and time-consuming and call for special expertise as well as appropriate equipment and software. In view of this, the Swiss Federal Office of Energy (SFOE) decided to launch a subsidised programme aimed at promoting in-depth analyses among energy-intensive companies and large-scale consumers, as well as supporting them with the implementation of their resulting voluntary efficiency measures. This paper presents the framework conditions and objectives of the programme (called ProAnalySys), plus some examples of in-depth analyses performed on swimming pools, cable railways and refrigeration installations.

14. A Review of the United States Process for Developing MEPS, the Benefits, and How Other Economic Regions Could Benefit from Adopting Similar Approaches

    Kirk Anderson, Rob Boteler

    Abstract

    The United States has been at the forefront of developing energy regulations for over four decades. During this time, a Process Rule has been used to create dozens of regulations. This chapter examines how the Process Rule works today, including the various stakeholders typically involved in developing MEPS, rules for developing regulations, and efforts underway to improve the existing process. The chapter also includes two examples of regulations and the outcome of each. Finally, the chapter lists benefits by incorporating the Process Rule as a model.

15. Electromagnetic Design of Propulsion Motors with Superconducting Field Coils for Electrified Aircraft

    Yusuke Ishida, Yutaka Terao, Hiroyuki Ohsaki

    Abstract

    This paper describes the output power density of partially superconducting motors (PSCMs), which have superconducting field coils and copper armature windings, for electrified aircraft propulsion systems (EAPSs). In EAPSs the aircraft’s fans are driven by electric motors. For electrified aircraft with a capability of more than 100 passengers, the electric motors are required to have high output power density of 16 kW/kg or more, whereas the power density of a conventional synchronous motor is limited to around 5 kW/kg. PSCMs have a potential to achieve such a high output power density because of high current density of the superconducting field coils and high magnetic flux density generated by them. The output power densities of 5.5 MW PSCMs were estimated at different operating temperatures of the field coils by analytical equations and FEM analysis. The design results showed that the output power density reached 16.1 kW/kg at 20 K and 12.0 kW/kg at 65 K. From these results we consider that the PSCMs at 20 K have a potential to be adopted in EAPSs in terms of high output power densities. The output power density of PSCMs at 65 K is more than double compared to conventional electric motors, although the required output power density could not be attained.

16. Design Methodology for a PM Electrical Variable Transmission Used in HEV

    Florian Verbelen, Hendrik Vansompel, Ahmed Abdallh, Kurt Stockman, Peter Sergeant

    Abstract

    Designing a permanent magnet electrical variable transmission is a cumbersome task, regardless of the considered application. The main reason for this is the iterative design process using a computationally intensive finite element model calculations that is necessary to model its behaviour. This makes it difficult to study or visualize the impact of design changes on, for example, the fuel consumption or cost of a hybrid electrical vehicle. To solve this, electromagnetic scaling laws are used to set up a performance map of the entire system. This map is able to present the performance (i.e. fuel consumption, cost, maximum acceleration, etc.) as a function of an axial and radial scaling factor. The map thus displays the performance of a series of designs which enable the reader to select the optimal one in a graphical way. Furthermore, feasibility constraints such as maximum weight, are added. These constraints allow to reject designs but make it also possible to study the performance as a function of weight or material cost. This is particularly useful for manufacturers as it gives an idea of how their investment is translated into a reduction in fuel consumption.

17. IE3 Efficiency Class as MEPS for Industrial Motor: How Brazil Got There

    George Alves Soares, Carlos Aparecido Ferreira

    Abstract

    The industrial motor market is huge in Brazil; around 2.7 millions units were commercialized, and the nationally installed motors in industrial plants were estimated in more than 20 million units in 2016. Their electric energy use, only for the industrial sector, is approximately 25% of the total national energy consumption. Due to the relevance of these machines, the government started effective actions to improve their technology and usage in 1992 (Soares G, Pinheiro M, Shindo R et al, The target program for three-phase induction motors. In: Proceedings of energy efficiency in motor drive EEMODS – 05, Heidelberg, Germany, September 2005).

    The first MEPS for industrial motors occurred for IR1 efficiency class, similar to IE1 in 2002. The MEPS were raised to IR2² level in 2010. Two years later, the Brazilian Technical Committee started developing some studies to establish the next step for MEPS, as presented in EEMODS’13 (Soares G, Ferreira CA, Costa EA, Santos MA, Leme AP, IS IE3 efficiency class: a feasible next step for industrial motor’s MEPS in Brazil? In: Proceedings of 8th energy efficiency in motor drive EEMODS – 13, Rio de Janeiro, Brazil, October 2013). However, the market conditions, the global competition of Brazilian OEMs, and the increase of imported motors made the market need more time to absorb the IE2 as MEPS. In 2016 and 2017, some accurate studies were carried out to understand the market barriers and to re-estimate the gains for the society, including the power sector and consumer views. The articulation of representatives from the business sector, public sector, and civil society organizations was carried out to ensure a feasible regulation.

    In August of 2017, a governmental directive was enacted establishing IR3² (IE3) efficiency class for the new MEPS for industrial motors. This measure took effect 2 years after the date of its publication in the Official Journal. Two years were considered the time needed for market preparation. Additionally, in an innovative way, this regulation includes also commercialized repaired motors, another big issue in Brazil.

    This paper presents the national motor market, the gains and the barriers of the IE3 efficiency class as MEPS in Brazil, and all activities that took place for achieving this enacted regulation.

18. A Decision-Making Tool Incorporating Multiple Benefits of Motor Systems’ Retrofits

    Rita Werle, Rolf Tieben, Petar Klingel, Andreas Rothen, Lea Fleischli, Victoria Pyatova, Shaun West, Kurt Ackermann, Richard Phillips

    Abstract

    Investments into energy efficiency in companies are currently considered rather one-sided, for the most part focusing on financial aspects only. Further benefits such as operational security, employee productivity, etc. are not systematically included in the investment analysis.

    According to the final report of the research project Management as a Key Driver of Energy Performance from 2018, ‘Energy efficiency provides numerous benefits to companies, including improvements in worker comfort, product quality, overall flexibility and productivity, as well as reductions in maintenance cost, risk, production time and waste’. The overall benefits of energy efficiency improvements are not only related to energy but also include non-energy aspects and are often referred to as multiple benefits. Non-energy benefits can have more importance than energy benefits only and ultimately help in convincing company management to invest into energy efficiency – having a positive overall impact on companies’ competitiveness. Thus, multiple benefits, which include both energy and non-energy aspects, have a significant potential in triggering the (timely) replacement of existing installations (Management as a key driver of energy performance – final report, 15 November 2017; https://aceee.org/blog/2015/12/multiple-benefits-prove-energy).

    A Swiss project aims to develop a decision-making tool for motor systems that supports decision-makers in small and large companies, incorporating the aspects of multiple benefits. Since electric motor systems are widely used in companies of all sizes across different sectors (primarily in the industrial and services sectors), the market potential of such a decision-making tool is considerable. In addition to a technical approach, socio-economic as well as investment-related aspects will be incorporated, so that the basis for decision-making has the necessary breadth. The final product shall be a web-based tool, which is easily available and applicable for the target group.

    The project is implemented in three phases and concluded by mid-2020:

    1.

    Phase 0: In this preparatory phase, the general approach was established, taking into account technical, behavioural and financial aspects. Interviews were conducted with four organisations, laying down the groundwork.

     

    2.

    Phase I: Following the preparatory phase, relevant multiple benefits will be further elaborated, identified and validated, based on interviews and data analysis. Four applications of motor systems will be analysed, namely, air compressors, cooling compressors, fans and pumps (and in addition as an option variable frequency drives).

     

    3.

    Phase II: The results of Phase I will be integrated into a web-based decision-making tool.

     

    4.

    Phase III: Dissemination of the tool to relevant stakeholders.

     

    This paper focuses on the methodological approach taken and the results so far (Phase 0).