QM Power Motor Technology Featured in Appliance Design
Proactive Technology Adoption Can Be a Key Differentiator
Sometimes a wide range of alternative technologies can make it harder for OEMs to identify true breakthrough technologies.
When it comes to electric fan motor technology, why wouldn’t an OEM consider specifying a more promising, broadly validated, energy-efficient and more reliable technology as soon as it becomes available? The answer is that the costs of internal testing, changing design drawings, recertifying equipment, revising marketing materials, and other factors can delay the decision of selecting a new part, especially when the energy and reliability benefits predominantly accrue to the end user. However, when a new technology provides an overwhelming cost advantage to the end customer that becomes impossible to ignore, OEMs can either be proactive by featuring the latest technologies in their products before their peers do, or act passively, by waiting for their customers to specify the use of those components.
With minimum energy efficiency standards changing an average of two to three times per decade, OEMs can benefit significantly from becoming early adopters of new components with enabling technology. By carrying the latest and most efficient technologies in their products, manufacturers can potentially eliminate a redesign cycle or two, and gain an advantage over their competitors. Energy efficiency is no longer an option; new EU labeling standards and U.S. Energy Star ratings have educated and motivated buyers to consider the energy consumption and total cost of ownership when purchasing equipment. With greater regulatory and market induced pressure on OEMs from domestic and foreign manufacturers, the ability to quickly evaluate, qualify and incorporate new technology into products will increasingly become a key differentiator for the most successful companies.
When New Technology Lives up to its Hype
Over the past decade, there have been a number of technological improvements to both the performance and costs of operating refrigeration equipment. These include but are not limited to environmentally friendly refrigerants, better lighting, electronically commutated motors (ECMs) and advanced controls such as building and device energy management systems and variable frequency drives.
Sometimes a wide range of alternative technologies can make it harder for OEMs to identify true breakthrough technologies. One such new technology is the recently available Permanent Magnet Synchronous Motor (PMSM) for HVACR applications, which are considered by many to be the biggest breakthrough in HVACR fan motor efficiency in over 50 years. Instances of incumbent technologies being displaced by new inventions can be less common, but when they offer a significant reduction to the total cost of ownership without an upfront cost premium, it is important to identify and begin evaluating them as early as possible. Due to their superior design compared to ECMs, the AC-driven PMSMs provide a better solution for OEM equipment and service and retrofit applications where improved efficiency, power factor, reliability, universal compatibility and consistent airflow are required given the design’s inherent advantages compared to incumbent motor types for HVACR applications.
Believe the Hype, But Only When Proven
When a new technology is introduced into the marketplace, it typically undergoes significant evaluation and scrutiny before it ever makes it into an OEM appliance or manufactured product. Since their commercial introduction in 2015, PMSMs have caught the attention of the U.S. Department of Energy (DOE), major utilities and energy intensive businesses such as grocery, retail, and hospitality companies due to their ability to save significant energy by eliminating power conversions and the duty cycle on the electric controller circuit (primary circuit board) used in ECMs. This new class of electric motors has been shown to reduce power and total energy consumption by up to 80% compared to induction motors and by 20-40% compared to the installed base of ECMs in commercial refrigeration display cases. The DOE has named these new motors a “high-impact technology” and has been driving a program to install this technology in grocery sites throughout the U.S., with Oak Ridge National Laboratories (ORNL) measuring the realized energy savings. ORNL’s initial report on the demonstrations concluded that if fully developed and adopted, PMSMs could achieve an annual savings of up to 1 quadrillion btu or more of primary energy, with proportional environmental benefits. That’s about 300 billion kWh or $30 billion a year, representing 1-3% of total domestic electricity consumption, suggesting there are few, if any, other energy conservation measures that can have as great an overall impact; and given there is not a price premium to take advantage of this opportunity, the return on investment (ROI) is effectively infinite.
Further support for the efficacy of PMSM technology was conducted by Alternative Energy Systems Consulting (AESC) and prepared for a Southern California utility to determine energy savings and demand reduction. (http://etcc-ca.com/reports/energy-savings-permanent-magnet-synchronous-motors-refrigerated-cases) The report chronicles savings achieved from the replacement of 173 case motors (9-12 watt) at a San Diego Vons Store (owned by Albertsons-Safeway). The PMSM fan assemblies showed an average savings of 73.6 kWh per fan, per year relative to the baseline ECM; demand was reduced by 8.5 watts per motor, or by 37%. According to the report: “The 173 fan retrofits showed clear and consistent improvements in power factor and consumption without negatively impacting case operation.” It was further proposed that, “The effectiveness, market potential, and ease of replacement suggest that this technology should be considered for further study or immediate rebate program inclusion.” Several utilities and Public Utility Commissions across the country are now rapidly evaluating rolling out new measures for higher rebates to spur faster adoption of PMSMs to curtail the continued use of lower performing (more costly) shaded pole and ECM alternatives.
Why PMSMs Exceed ECMs in Efficiency
The current “state-of-the-art” motor technology that is being specified in most OEM refrigeration equipment is the ECM, an innovation from the 1960s that has only meaningfully penetrated the commercial refrigeration market in the past 5-10 years, predominantly driven by increased regulation, utility incentives and just simple awareness that a better option was available. ECMs require continual conversions between AC and DC power to operate, and require nonstop electrical input to the controllers that electronically commutate the motors (through a process called pulse width modulation) to provide the required rotating magnetic fields for operation. These shortcomings not only waste energy, but make the design susceptible to variations in voltage and energy spikes that can cause uneven performance and premature failure. In comparison, the PMSM operates at the AC line frequency of grid-supplied power, thereby eliminating the need for power conversion after the motor starts. Once the motor reaches its targeted speed (within a matter of seconds), its innovative circuitry efficiently switches its higher energy consuming circuit to a simpler one that allows the motor’s operation to be sustained by AC power supplied directly from the grid.
By eliminating the power conversions found in ECMs, PMSMs typically use about 30% less power to generate the same output (airflow in the case of fans) and as much as 80% versus shaded pole alternatives, which represent about two-thirds of the installed base. Moreover, the elimination of the electronics typically increases motor power factor by about 50%, allowing for significant reductions in current (amp) draw. The stability and performance of airflow in the refrigeration applications is further improved by operating at the AC line frequency. Whereas ECMs can vary speed and airflow by about 10% when following normal daily voltage fluctuations, PMSMs will not vary in speed or airflow as they are synchronized to the line frequency (60hz in the U.S.) instead of voltage. OEMs can take advantage of this more consistent airflow by designing cases that do not require as much tolerance to ECM airflow changes and allow for lower, more consistent airflows and less power requirements while still optimizing refrigeration performance. Furthermore, field coils, not the electronic circuit board, are energized first in PMSMs, affording significantly better in-rush current and surge protection. Thus, besides using less energy to do the same work, PMSMs are expected to have much greater reliability and longer expected lives versus ECMs. The warranty of PMSMs is typically double that offered by ECM alternatives.
Do Variable Speeds Help in Commercial Refrigeration Case Applications?
Case refrigeration applications typically favor a single speed fan motor operation to maintain optimum refrigeration performance. ECM motors, which can be programmed to operate at different speeds, have more recently been configured to be programmable to run at different speeds at the manufacturer to provide potentially fewer SKUs (minimizing the need for different fan blades to optimize the air flow performance) which can be used in multiple products with different airflow requirements. However, this convenience comes at the cost of energy efficiency because motors can typically only be wound to operate at their peak efficiency at a single point/operating speed. Despite multi-speed or variable speed functionality, peak efficiency is only achieved at one of the speed options. The implication is that the motor cannot be optimized for individual applications running at different speeds. The electronics to regulate speed and the AC to DC power conversions further add to the efficiency loss in these types of motors. The data suggests that these additional energy costs can be several orders of magnitude more than the potential supply chain savings afforded by the potential SKU reduction, while the complexity of the custom offerings challenges the end users’ ability to service and maintain them going forward. Simply put, the most efficient, practical and cost effective solution for the OEMs to minimize the total cost of ownership for their end users is to utilize the existing industry best practices to optimize application performance utilizing a more efficient and reliable motor and other superior components.
The motor technology described in this article is an example of how a single component could have significant impacts to both an OEM’s product and the energy efficiency and cost savings that would ultimately be realized by the end user of their equipment. As manufacturers develop their next design iterations of new and more efficient products for their customers, there remains a significant opportunity for them and their customers to take advantage of the latest technological innovations.
Original article located at http://www.appliancedesign.com/articles/95165-proactive-technology-adoption-can-be-a-key-differentiator?