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issue: October 2002 APPLIANCE Magazine

Motors and Air-Moving Devices
Bringing Value to a Mature Market


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by Lisa Bonnema, Editor

With international competition heightening, appliance motor and air-moving device manufacturers are offering sophisticated motor and blower systems and value-added services to differentiate their products from those carrying a low price tag.

Motors That Stand Out In A Crowd

It is certainly no secret that within the last few years, global competition among appliance motor and air-moving device manufacturers has increased considerably. That, coupled with an appliance industry that is stretching out to all corners of the globe, means that motor and blower makers are searching for new ways to make their products attractive to appliance OEMs.

"Motor manufacturers, like everybody else, are under onslaught from imports, primarily the Far East," says Chuck Belanger, manager of Strategic Marketing at Ispat Inland (Chicago, IL, U.S.), a supplier of motor lamination steel to the appliance motor industry. "Some of that is the strong dollar, some of it is the developing countries. Specifically, you have to put China in that category, but others as well are building up their own capabilities for their home markets, and they tend to build up ahead of demand. So in the interim, the excess motors get sent to other parts of the world," he tells APPLIANCE.

According to Mr. Belanger, in the last 2 years, the motor industry has seen the intensity of Asian imports into the U.S. and Europe increase "up another notch." He explains that while the industry first felt the effects of international pressure about 10 years ago, manufacturers are now dealing with it on a new, more severe level.

Research group Frost & Sullivan agrees, adding that North American firms - specifically those within the a.c. integral horsepower motor market - will have to overcome threats from new market entrants. "Foreign competitors from Eastern Europe and Asia are offering competitive products at lower prices within North American markets," says Liliya Santalova, a research analyst for Frost & Sullivan. "These new entrants are seeking large OEMs, which buy in large unit volumes."

According to the research firm, overseas companies are likely to target lower-volume markets in the future, threatening to usurp revenues from North American firms. While price will remain a key issue, North American firms can retain customers by emphasizing other qualities, the research firm says.

"Service, technical expertise, a broad product range, and an understanding of customer demands will help manufacturers compete more effectively in this marketplace," says Ms. Santalova.

She adds that the Mexican sector is showing great promise as an industry participant. Having recently signed a free trade agreement with the European Union, Mexico has open trading abilities unparalleled in North America, according to Frost & Sullivan. The agreement with Europe will reportedly enable Mexican companies to export their products to Europe without penalties. Frost & Sullivan says these less expensive Mexican products are expected to significantly appeal to motor customers.

"The influence of low-cost manufacturing and engineering centers outside of North America is certainly accelerating changes in the electric motor industry," offers George Gulalo, president of Motion Tech Trends (MTT), a consulting group for the electric motor and motion control industry.

Mr. Gulalo explains that while initial industry expectations were that offshore manufacturers would continue to develop products using the lower-end electric motor technologies, in the long-run, this may not be the case. "Initial inroads by low-cost manufacturing countries - primarily Asia - are in the lower technology areas," he says. "However, large companies like GE and Emerson are establishing manufacturing and engineering centers in countries like China and India. The availability of skilled engineers in these countries will mean that both the manufacture and design of even more sophisticated systems will move offshore."

This increased competition, of course, only means good news for appliance producers. As motor and air-moving device suppliers increase R&D efforts to deal with global pressures, the outcome is heightened customer service, advanced motor and control technologies, and, in turn, decreased cost of high-quality materials and sophisticated components such as electronic controls.

The Package Deal In order to deal with the increased price pressure, many motor and air-moving device manufacturers are taking a "system" approach, offering OEMs more than just the core motor or blower. "In many higher volume applications, OEMs are asking critical component suppliers to provide added value by implementing what I would call a sub-system solution," says Mr. Gulalo of MTT. "Motor suppliers need to respond positively to these large-volume OEMs in order to secure their supplier position. Motor manufacturers are adding value by providing a 'motor plus' - the motor plus gears and/or plastic or metal mechanical elements. This relieves the OEM from employing assets in areas outside of the OEMs' expertise," he explains.

Lau Industries, Inc. (Dayton, OH, U.S.) has taken this type of approach and recently introduced a new program for its customers called Motorized Air Products (MAP). "Our traditional business is to supply a customer with an air-moving component - either a propeller fan or a forward curved (FC) blower wheel. The customer would then attach the component to the motor and install the assembly in the final product," Dr. Michael Brendel, Lau's director of Engineering, tells APPLIANCE.

"An emerging trend in the large appliance arena is for the supplier to provide a complete motorized package. This is particularly attractive when an FC wheel, housing, drive, and motor are involved since there is a high cost associated with labor and floor space needed to assemble these units," he explains. "This trend to purchase a complete 'module' is similar to the one that started in the automotive industry about 15 years ago."

Dr. Brendel adds that Lau's MAP program has been especially popular with smaller customers that do not have the expertise or infrastructure to assemble components. He adds, "Larger OEMs like this approach because it eliminates purchasing and logistic issues associated with buying many smaller parts and then assembling them in-house."

Dr. Brendel says that Lau has seen several accelerated design strategies develop out of its MAP program. "The MAP program requires the OEM to work closely with us when developing a new product. The traditional approach was to size the air-moving device well after the OEM had pretty much settled on a final design for the product," explains Dr. Brendel. This, he says, often involved a lengthy trial-and-error test program to find the right air-moving component.

"This new strategy requires us to collaborate early in the design process so that the air-moving package is tailored to specific performance objectives," he says. "Overall, this approach compresses the design cycle since air-moving package development occurs in parallel with the rest of the product."

While it has offered its customers stepper motors and motor controls for more than 15 years, Malborough, CT, U.S.-based Intelligent Motion Systems, Inc. (IMS) recently decided to offer an integrated motor plus driver package called the MDrive for medical device applications such as blood analysis equipment. The product is offered in four standard NEMA motor frame sizes - 14, 17, 23, and 34 - with an onboard 12-48 V d.c. half/full step drive, or a 12-48 V d.c. or 24-75 V d.c. microstepping drive.

"Our product is fairly unique in that we've coupled a step motor with the actual electronic controls," says Sue DalPonte, manager of communications. "By combining them, we meet our customers' 'noise' considerations. Specifically for our product, it's electrical noise emissions that we're concerned about. In coupling the motors and the controls, you eliminate running wires through the machinery. So any noise that does exist, doesn't cause interference with the operation of our product. In addition, this gives OEMs a much more compact package that is a plug-and-play type of device."

By integrating the electronics onto the motor, the company says it was able to save a considerable amount of space by removing the drive from the control panel. This, in turn, offers manufacturers the opportunity to reduce the end product size.

Ms. DalPonte explains that coupling the motor and electronics meant finding a material that would be lightweight, but still be able to deal with increased temperatures. The solution, she says, was using a thermally-conductive plastic housing made of CoolPoly®‚ polymer from Cool Polymers, Inc. (Warwick, RI, U.S.). The material kept the product lightweight and compact, without the need for an additional external cooling device.

Keith Hallenbeck, director of Sales at Ametek Rotron (Kent, OH, U.S.), notes that in order for system solutions to be successful, a supplier needs to be sure it fully understands the application. "There is a high degree of resources put into having in-depth technical understandings of the customer's application and use of the product," he explains. "That's really been the trick to it. Once you take over integrating the three technologies - the blower or pump, the motor, and the controller - you really need to know the system requirements."

Mr. Hallenbeck adds that often times Ametek Rotron is able to develop a higher efficient product than if the customer was trying to integrate the three technologies. "A customer could go out and get the most efficient motor it could buy, and let's say we couldn't compete with that. And then he purchases an efficient impeller and the electronics, and puts them all together. But they aren't perfectly 'matched' for the highest overall efficiency," he explains. "This means the speed torque curve isn't perfectly matched to the aerodynamic load, which isn't matched perfectly with the electronics - all because he bought them at three different places. The advantage is realized when it is integrated by one company."

Ken Lechner, director of Engineering at Ametek Rotron adds, "It also enables us to take ownership and responsibility for what the customer is looking for and take that burden off of them. They can supply the end requirements, and we deal with the details of the motor, controller, and blower or pump that is appropriate."

Mr. Hallenbeck says that this is a rising trend among OEMs, as more companies are becoming less vertically integrated. "They like to pass this responsibility off to us," he says.

Passing the Test Many appliance producers are also asking their motor and blower suppliers to take on the additional responsibility of testing. While this can be costly for the supplier, most are quickly adapting to the trend, building test facilities or offering on-site technicians to help with this crucial, but time-intensive, part of the motor design process.

According to Stu Gatley, director of Engineering at Jakel, Inc. (Highland, IL, U.S.) the main reason for this trend is lack of personnel at OEM facilities. "Because a lot of manufacturers are cutting back on their engineering staff, they are relying more on their suppliers to provide that service," he explains.

In a recent development project with International Comfort Products Corporation (USA) (ICP), Jakel provided an on-site technician to help with the testing of ICP's 90-percent condensing furnace products. While Jakel was initially brought in to develop an inducer assembly, it ended up providing ICP with 6-months worth of testing assistance. In fact, according to ICP, Jakel's willingness to offer this "value-added" service was the main reason the OEM chose to work with the supplier. As a result, the two companies now have a purchasing agreement. (For more information on this relationship, see the article, "Meeting Design Demands" on page M-4.)

Ignacio Santa Cruz, business development director for FASCO Motors (St. Louis, MO, U.S.), says that in order to successfully meet the increased demands from appliance OEMs, motor and blower suppliers are required to have extensive design, prototyping, and testing capabilities. This is why, he explains, FASCO recently completed a six-station testing laboratory with full capability for performance and emissions testing of gas appliances.

The company's additional testing capabilities were especially helpful, Mr. Santa Cruz explains, when one of its HVAC customers asked FASCO engineers to reduce its costs and remove operations from its facility. "We were to include the inducer exhaust transition, which had always been added by our customer," he says. "The change required the inducer restriction to be at the inlet of the blower instead of at the exhaust. The many sample iterations would have only been possible if the engineer had been directly involved in the product testing."

Meeting Efficiency Demands Most appliance engineers would agree that any "advancement" in motor technologies has more or less been in the application of these technologies within the appliance industry. Demands such as increased efficiency, for example, have led to the implementation of technologies such as brushless d.c. and electronically commutated (EC) motors into appliance designs.

According to Mike Delwiche, product manager, Ventilation & Refrigeration at A.O. Smith (Tipp City, OH, U.S.), when suppliers can offer their customers smaller, more efficient motor designs, many times cost becomes less important. "Any new development that a supplier may give [to appliance producers] that addresses these issues is a competitive advantage," he says. "This may be seen in the implementation of brushless d.c. motors used in refrigerators. These motors are more costly than a.c. induction c-frame motors, but they offer energy-saving benefits."

Mr. Delwiche adds that in the specific case of refrigerators, brushless d.c. motors offer approximately 30-percent better performance than a standard a.c. induction c-frame motor. "Through the brushless d.c. motor is more expensive, it offers a new technology that allows the refrigerator manufacturers the ability to meet EPA minimums, meet Energy Star requirements, or use less-expensive materials in other areas of the refrigerator."

Roger E. Hollis, vice president of Business Development for Arkansas General Industries (Bald Knob, AR, U.S.) agrees. "For refrigeration applications, i.e., evaporator and condenser fan motors, the trend is slowly moving…toward EC motors. This is really a brushless d.c. motor that has the electronics built into the motor package or alternately built into a circuit board inside the unit," he explains. "In many cases, it is designed around the configuration of the a.c. motor for best-fit purposes."

Mr. Hollis says that while motor costs will always be lower for the old technology designs, reduced price tags will move into the higher-end motor designs. "Even the new technology motors (EC motors), while higher in cost at present, are expected to reduce in cost as volume increases," he says.

Efficiency mandates have also contributed to the increased use of brushless permanent magnet motor technologies in the HVAC segment, according to Mike Eberlein, furnace product manager for HVAC equipment maker ICP. "There are market forces that are slowly driving the U.S. and Canadian market to higher efficiencies," he says. "The federal government put in place minimum efficiencies in 1992 that required gas furnace efficiencies to go to 78 percent. The least efficient furnace we make right now is rated at 80 percent, and we have units that go all the way up to 92 percent. We have also incorporated very efficient blower motors into our furnaces. Most designs use a permanent split capacitor motor, but we also have a line of 90-percent furnaces that use a brushless permanent magnet motor that's very, very efficient. Most other manufacturers have introduced lines of 90+ efficient furnaces, and most have included models with permanent magnet motors."

Mr. Santa Cruz of FASCO Motors adds that energy efficiency demands have prompted the use of more variable speed motors and blowers in residential furnaces and commercial water heater products.

He also says that "venters" are increasingly being used in commercial and residential water heaters, as well as other gas appliances, to improve their efficiencies. "Venters are blowers used to vent the gas exhaust of an appliance - in this case, a water heater," explains Mr. Santa Cruz. "Presently, very few water heaters use these venters. In most gas water heaters, the exhaust goes up through the pipe naturally since most pipes go straight up. A venter is sometimes needed when you need to vent vertically through a wall, but it is also used for higher efficiency and to achieve lower emissions." He adds that as the U.S. government, for example, continues to dictate higher efficiencies and lower emissions, the use of these types of blowers in gas water heaters will only increase.

Dave Harvanek, director of Business Development for Ametek Rotron says there has been an increased demand for variable speed, premix gas burner blowers in applications such as commercial furnaces and boilers, gas-fired foodservice equipment, and water heaters. "With the emphasis on greater combustion efficiency and lower NOx and CO emissions, designers of gas-fired systems increasingly are considering the use of variable speed premix blowers," says Mr. Harvanek.

To address this need, the company recently released a new line of brushless d.c. premix gas blowers. "Previously, the only options available were fixed-speed or two-speed blowers, intake damper systems on fixed-speed blowers, or inverter-driven variable speed blowers," explains Mr. Harvanek. When used in conjunction with a modulating gas valve, he says that Ametek Rotron's new line of blowers can give designers a range of design options, as one of the new blowers can serve the needs of several different burners by simply adjusting performance output.

The new line, consisting of eight models, features variable speed control and comes in two options: an internally adjusted speed control with onboard potentiometer and an external d.c. control that actively varies blower performance.

Available in 120 and 240 V a.c. models, the premix blowers use brushless d.c. motor blowers, but feature an a.c. input. According to the company, the long-life and low-maintenance features of the brushless d.c. blower motor offers increased reliability. In addition, the product line is available in two different output flanges that are said to cover most burner designs. This adjustable performance, the company says, permits the elimination of complex air intake damper systems.

Achieving Results The methods used to meet appliance OEMs' demands for efficient motor and blower designs seem to depend on the specific application. Emerson Motor Technologies (St. Louis, MO, U.S.), for example, implemented additional active materials to its extreme-E™ line of premium efficiency pool and spa motors. "[These] motors are designed with additional active material - magnet wire, stator/rotor iron, rotor aluminum - to increase the electrical efficiency in converting electrical power into the motor to mechanical power out of the motor at the shaft," explains John Schrader, senior engineer. "Less electrical power is required to supply the same mechanical power when using a premium efficiency motor over a standard efficiency motor. This increased efficiency results in a motor with lower losses, cooler running temperature (increased life), and considerably lower operating costs."

A key to designing this premium efficient motor line, according to Mr. Schrader, was the use of computer software. "Motor designs are optimized by computer calculation/simulation of performance, which includes an analysis of the stator (stationary armature) and rotor (rotating armature) magnetic fields during various critical operating points in the motor performance curve," he explains. "By determining such things as magnetic line density in the annealed/processed electrical steel, current density in winding conductors and rotor bars, and operating voltages on capacitors, the electrical efficiency can be optimized before the design is built and tested when the performance is confirmed."

He adds that in this application, particular attention is paid to the magnetic permeability characteristics on the annealed stator steel, the properties of the electrical grade rotor aluminum, and the magnet wire used in the motor. "Specific engineered plastics, bearing selection, and other mechanical design selections support the overall achievements in upgrading to the premium efficient motor," he explains. "Electrical and mechanical finite element analysis (FEA) are also used when more advanced design tools are required."

Lamb Electric, a Kent, OH, U.S.-based blower supplier to the floor care industry, was able to increase the efficiency of a mature vacuum motor technology by incorporating a new fan design.

According to Peter Pavlick, director of Marketing and Sales for Ametek Lamb Electric, the floor care industry has gone nearly 20 years with little or no change in existing motor technology. The last major development, he explains, was seen in the Sebo commercial cleaner, in which the commercial/institutional upright vacuum used a high-performance vacuum motor that provided the required suction to drive the appliance's beater bar. "This unit needed to match the suction of the canister vacuum motors in a much smaller diameter. These goals were achieved by using a 4.2-inch (108-mm) diameter clean air fan system that allowed the motor to be mounted in the vacuum cleaner base, while still minimizing the vacuum's height to allow cleaning under furniture," he explains.

While this development advanced floor care technology, it also posed some challenges for increasing the efficiency of the motor and, in turn, the end product, according to Mr. Pavlick. "Increased air performance and high efficiency are a must to keep up with market needs," he says. "However, typical approaches for increasing the operational speeds to increase efficiency and performance cannot be applied in this instance since the motor drives the beater bar, and that speed cannot be increased." An increase in the speed of the beater bar, he explains, would result in undesirable noise levels.

Therefore, Lamb engineers had to find a new method to increase the motor efficiency, Mr. Pavlick says. "By concentrating on fan design and applying a patented tuned port diffusion system, we were able to increase the overall system efficiency by 40 percent - from 28 percent to 39 percent. The air power increased by 63 percent - from 281 air Watts to 460 air Watts - and the input rating increased by 50 percent - from 800 Watts to 1,200 Watts," he explains.

According to Mr. Pavlick, in the new design, the fan selection is matched to the required flow rates, and air is routed through tuned port exhaust chambers matched to the flow rates to optimize the efficiency and output at the operational point of the cleaner.

"These remarkable increases were accomplished within the same unit size and the same motor speed range so that the beater bar speed was not compromised," he says. "The resulting units supply the performance to enhance cleaning performance and supply commercial vacuum cleaner manufacturers the opportunity to upgrade their product and product ratings."

At the core of any motor or blower design is the equipment or method used to build it. Sometimes, manufacturing methods can even lead to a higher performance motor design. According to Mark Carter, international marketing manager for Fort Wayne, IN, U.S.-based Advanced Machine & Tool (AMT), that may indeed be the case with its new high-production brushless d.c. stator winder.

Mr. Carter says that AMT has developed a new method for winding simple 3-phase stators that may increase the efficiency of brushless d.c. motor designs. According to Mr. Carter, most companies are currently taking a nine-pole stator and cutting it into nine separate segments that are wound individually. While this method gives a decent fill factor, Mr. Carter says it may be hard to maintain the stator's concentricity and connections.

"We have taken an approach where we actually connect all of those nine segments together in a strip stator. That is exactly how we wind it," Mr. Carter explains. "In fact, we can wind the A phases in all three phases at the same time. So you are winding in slots 1, 2, and 3 and then you index over and you wind 4, 5, and 6, and then index and wind 7, 8, 9. So you have only three start leads and three finish leads."

Aside from the simplicity of the method, Mr. Carter adds that the stator can actually achieve 100+ percent fill factor, which, in turn increases the stator's flux density and adds efficiency to the overall motor design. "If you have studied physics, that doesn't seem possible," notes Mr. Carter. "However, the industry standard for calculating fill factor is squaring the enameled wire diameter and dividing that into what the usable area of the slot is. Basically, there still is going to be losses even though these wires nest well."

In AMT's winding process, however, after the stator is "rolled" back up, it actually winds and overfills the slot and compresses the wire slightly. "You basically roll it up, press it, and the core is welded," says Mr. Carter. "The wires will slightly deform to fill in any gaps left between the wires."

The Personal Approach Many motor and blower suppliers say that their most advanced designs have resulted from close collaboration with the OEM. In fact, some industry professionals believe that customization may be one way suppliers can overcome the threat of motors and blowers becoming a low-cost, "throw-away" product.

In a recent development project with appliance maker BSH Group, German supplier Motoren Venilatoren Landshut GmbH (mvl) was able to create a completely new air-moving device while trying to meet BSH's specific requests for its new platform cooker. The result was a custom hot air convection system and cooling system that brought the OEM substantial cost savings.

"When BSH started the new development of an oven, it requested a cost reduction," explains Stefan Brandl, sales director at mvl. "Therefore, we suggested the option of combining the crossflow fan and the radial fan into only one device."

BSH then sent mvl a prototype oven, and the supplier began investigating how it could develop an optimized fan solution. After overcoming challenges such as meeting air performance requirements and space restrictions, mvl developed one of its newest product offerings, the AL108, a shaded-pole motor with two impellers on the shaft ends.

"One shaft end keeps a plastic axial blade as a replacement for the crossflow blower. This fan cools the oven case," explains Mr. Brandl. "The other shaft end holds a stainless steel radial fan surrounded by a die cast scroll housing, which replaces the former radial fan. This fan sucks out the moisture air of the oven cavity. The motor power is adjusted to the required air performance of the fans."

According to Mr. Brandl, the major benefit BSH achieved in this development project was cost reduction, as the OEM has to buy and assemble only one fan instead of two. It also reduced assembly costs and time, as only one fan needs to be assembled, using only three screws. The reduced number of fans also gave BSH a noise reduction, he adds.

Of course, some OEMs might not require such intense customization, especially if it slows down product development time. Even so, suppliers can still offer customers a certain level of customization by fully understanding the end application, offering OEM options that specifically address potential needs that may arise within particular applications.

Dr. Thomas Bertolini, executive technical director at ebm Werke GmbH (Mulfingen, Germany) says that one way suppliers can approach this is by dividing its R&D departments into two parts - platform development and application engineering. "The platform department develops new products as kits, which can then be easily applied to customer-specific needs," he explains. This, he adds, can speed up production development time.

"ebm developed an energy saving motor as a platform development within 18 months," Dr. Bertolini says. "Then it was applied to the first pilot customer within 6 months. Now, while the motor is mass-produced, it is possible to use it in further applications and adapt it to these within a couple of weeks."

Imperial Electric (Akron, OH, U.S.) took a similar approach in its recently-launched FiR a.c. electric pumps by offering customers several design options to meet specific needs. The units are designed primarily for heavy-duty liquid movement in commercial dishwashers, but also have applications in commercial laundry equipment.

The centrifugal pump housings and impellers can be specified in various materials, including polypropylene, BMC (phenolic), and IEXF (polyamide), depending on the needs of the application. Seals can be ordered in NBR, Teflon, or EPDM to withstand high temperatures. In addition, the pumps are designed for use with common detergents and rinse aids (both basic and acid).

"Our experience to date has been primarily with water-based fluids, but additives can change the specification for the pump housings, impellers, and bearings. Temperature of the fluid is also a determining factor as to which material will be used for those components," explains Don Poremski, market development leader, Imperial Electric.

"Detergent/water fluids to be pumped are classified as either acidic or basic (alkaline) by the specifier, along with temperature and electrical motor characteristics. Designers also consider the inherent strength of the material when ordering. How it is connected to other components, the amount of vibration, and location within the unit must all be thought through," he adds. "Imperial/FiR offers engineering assistance to manufacturers considering our pump motors to ensure performance parameters are met, especially in terms of flow rate and pressure."

ebm Industries, Inc. (Farmington, CT, U.S.) found that a large product offering, as well as knowledge of the end application, was especially critical when one of its customers requested ebm's support in developing its first dishwasher product. "We presented them with a wide selection of motor and blower products designed for dishwasher applications," explains Tom Costello, product manager. "This product depth allowed the customer to immediately select a proven, cost-effective design from a known supplier that significantly reduced the OEM's component selection and qualification time line."

According to Mr. Costello, the product selected was a unique, multi-port exhaust fan with integral solenoid vent valve. Its main function was to remove the moist, hot air from the dishwasher compartment at the end of its wash cycle, thereby accelerating the drying process. Although simple in function, the application demanded the fan to be reliable; operate safely in a hot, moist environment; fit in a 2.25-in thick door panel; and be quiet.

To meet these engineering challenges, Mr. Costello explains that the fan was manufactured with a humidity-protected, shaded-pole motor and high-temperature plastics for the scroll housing and radial impeller; packaged in a long, thin-profile housing; and designed and tested to meet the air and noise requirements of the application.

In motor control, many suppliers say that knowledge of the end application is more than just helpful when designing electronic controls for a particular OEM; many times, it is critical.

According to the Motion Control division of Danfoss, Inc. (Ontario, Canada), in designing and building motor control panels, understanding the application is just as important as understanding the control components and assemblies that make up the panel. The company says that OEMs understand the functionality and purpose of the products they manufacture, but when it comes time to source the electrical control panel, they relate to the panel in terms of output and what it should make their product do. Consequently, the supplier explains, it falls upon the control manufacturer to understand the OEM's product as deeply as the control panel itself.

In fact, according to Mr. Lechner of Ametek Rotron, sometimes, the motor system's functionality is directly dependent on knowing the details of the application. One such instance is in the development of sensorless motor designs.

Mr. Lechner explains that many appliance OEMs choose sensorless motor technologies because they can offer significant cost savings, as they eliminate the need to run several lead wires to each Hall effect sensor. "You go from 8 leads down to 3, a 3-phase brushless motor," he explains. "However, one of the challenges with sensorless is you have to know exactly what your load is and the characteristics of it, including inertia. And if you don't have control of that, you can set up a sensorless system that doesn't always work."

He continues: "Let's say for example, we have a motor and blower integrated together; we control that system, so sensorless design is easier in that situation. If you just supply a motor into an industry where the customer can apply it to numerous different types of loads, you can have a situation in which sometimes it works, and sometimes it doesn't."

Mr. Hallenbeck of Ametek Rotron adds, "There is a general principle that rolls in here - the more smart or intelligent the motors become, the more application specific they are many times, but they are easily changeable with software. But let's say the motor is not as rugged as the old a.c. induction motor, which would just grunt out the work, regardless of what you stick on the shaft. The only byproduct of the a.c. motor is that it may run hot or less efficient, whereas here, the electronics may become confused and not work."

Gaining More than Control By far the most dramatic advancements in appliance motor technology have been in motion control, with more and more appliance segments adopting the use of electronic controls and software to increase performance and reduce overall system costs.

That, at least, was the goal of fitness equipment manufacturer Life Fitness (Franklin Park, IL, U.S.) when it first decided to incorporate microcontrollers into its cardiovascular products, specifically its stationary bikes, stairclimbers, cross-trainers, and treadmills. The company first switched over to microcontrollers from Austin, TX-based Motorola 4 years ago and since then, has continually updated the motor control of several of its products.

According to Robert Sutkowski, electrical engineer with Life Fitness, the original objective in working with Motorola was to find a cost-effective motor control solution. However, he explains, later redesigns focused on improved performance while maintaining cost effectiveness.

"Since our first Motorola microcontroller-based motor controller design, we have increased the speed range of our treadmills from 1-10 mph to 0.5-15 mph and increased the power capability of the motor controller to improve system life," explains Mr. Sutkowski. "The performance gains made possible by the controller are key to the improved specifications to our latest generation of commercial treadmills."

The microcontrollers have also been able to add special features to the fitness equipment. "The motor controllers communicate with the console and provide information for service personnel," Mr. Sutkowski says. "One example is an on-board watt meter which is useful in determining how close a system is to end of life."

The fitness equipment maker currently uses Motorola's 68HC16 family, 68HC908MR series, and 68HCO5 and 68HC11 families of microcontrollers to control a.c. induction motors supplied by Emerson Electric.

Motorola says that the home appliance industry in general is moving toward incorporating semiconductors instead of traditional analog relay circuitry in order to reduce the complexity of components, while simultaneously gaining new features not possible before. The supplier says that washing machines, for example, can gain features such as high-speed water extraction, gentle and more precise agitation cycles, and out-of-balance correction.

Appliance maker Samsung Electronics recently decided to incorporate a new motor control design into its outdoor air-conditioning units in order to reduce system complexity. The company was previously using a power module and gate driver IC that was too complex to design and manufacture, according to Mr. Sung IL Yong, principal research engineer at Huropec Co. Ltd., Samsung Electronics' design house for air-conditioner controller development.

Mr. Yong says that Samsung switched to the SPM™ (Smart Power Module) from Bucheon, Korea-based Fairchild Semiconductor because it was a simple, low-cost solution that also brought increased reliability to its outdoor air-conditioner.

According to Fairchild, its SPM products provide a complete adjustable package motor drive control and fully integrated circuit protection for a.c. motors found in several appliance applications. The supplier says that compared to discrete IGBT solutions, the integrated SPM device requires less than half the board space, while providing low-voltage control and high-voltage output stage rated at 10~20 A at 230 V a.c.

The module's compact size is also attributable to its built-in, high-speed, high-voltage control circuit (HVIC), which is said to eliminate the need for optocouplers and, instead, allows the IGBTs to be driven by a single-bias supply.

"By simplifying the circuit, this reduces manufacturing time and allows for high yields, and there are less components to stock. So the total cost is cheaper than a discrete [IGBT] solution," explains Mr. Yong.

He adds that another feature of the SPM product is that it uses ceramic-based package technology that allows for low leakage and high isolation voltage. Fairchild explains that by housing the SPM in a ceramic-based transfer molded-type package, it is able to achieve a 27-percent higher power rating than a conventional TO-220F package.

Mr. Yong notes that because reliability is crucial in a consumer application such as air-conditioning, it was also critical that the SPM offered a dependable design. "Highly effective short-circuit detection and protection is achieved through the advanced current sensing IGBT," Mr. Yong explains. And to bring added reliability, Mr. Yong says that the air-conditioner design also incorporates SPM's optional built-in thermistor for over-temperature monitoring.

Trendy Material Because motor manufacturing is a venerable industry, there are some design areas in which the theory, "If it isn't broke, don't fix it," is applicable. Mr. Belanger of Ispat Inland says that one such example is the use of metal in motor construction. "It's a matter of physics. No other material is quite as magnetic as steel," he explains. "And the wonder of this market - and this is one of the strengths of it - is that motors are everywhere."

Even so, there are certainly a few trends in material use that have surfaced in recent years. According to Andrew Lee, manger of Sales and Marketing for Chiaphua Components Limited (Fanling, Hong Kong), more high-temperature parts such as Class H materials will be used in motors and blowers as appliance designs get more sophisticated. "It is the trend that motors used in the latest appliance designs need to work under an even higher temperature environment," Mr. Lee explains. "Insulation Class H materials for motors means the motor can work close to a 180°C environment."

Within air-moving applications, there seems to be a trend of increased use of plastics over metal. Mr. Santa Cruz of FASCO Motors says that many blower suppliers are using high-temperature plastics because it is freeing designers from several constraints associated with metal, resulting in easier assembly, lower part count, and enhanced performance.

Dr. Brendel of Lau Industries, Inc. agrees that plastics can offer greater design flexibility and performance. "The ability to mold smooth contours, airfloil shapes, and flow passages can result in better performance than metal products, both in efficiency and noise reduction," he explains.

Even so, Dr. Brendel says that presently, aluminum and steel are still the main material choices in blower designs because of cost and reliability issues surrounding the use of plastic. "There are certain UL requirements for flammability, emission of toxic fumes, etc. There are materials that will meet these requirements, but they are expensive," he explains. "The cost savings thought to be brought by moving to plastic evaporate when the material is considered."

According to Dr. Brendel, unless costs can be reduced significantly lower than metal products, it will probably take some sort of regulatory action to force the use of these plastic materials. "This has happened to some extent in Europe, where high energy costs and low noise requirements have a large impact on product designs," he says.

Mr. Santa Cruz adds that the current trend is not necessarily to use exotic or "miracle" plastic materials to achieve higher performance, but to instead focus on creative designs using present materials.

The Deciding Factor In the end, the driving force behind the adoption of advanced motor designs in the highly competitive appliance industry is - and always will be - cost. "For the high-volume OEMs in the refrigeration sector of the appliance industry, cost is the primary consideration no matter what they say," offers Mr. Hollis of Arkansas General Industries.

And while there are certainly many technologies out there that could increase the efficiency and performance of appliance motor designs, as Mr. Hallenbeck of Ametek Rotron notes, there needs to be a significant cost reduction before an OEM will even consider updating to more sophisticated controls or high-quality materials such as rare earth magnets or special lamination materials.

Mr. Hallenbeck explains: "What is obvious is this - high expensive materials that yielded high efficiency were possible 10 years ago, but no one wanted them because they were so expensive." He continues: "We could have had the same efficiency 10 years ago, but the blower would have been twice as much. That sort of 'undoes' all your efficiency gains if it doesn't have a payback. Now, it is providing a payback because those material prices are coming down."

And therein lies the catch 22 - cost doesn't go down until demand goes up. As price pressures from all over the world continue to dominate the industry, motor manufacturers are quickly realizing that the coming years will require a more aggressive stance than in the past. Motor and blower suppliers will need to continue to educate OEMs about long-term savings and benefits of certain motor technologies, while continuing to innovate and expand engineering capabilities and services. Waiting around for the price of advanced technologies to drop will no longer be enough.

 

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