Electronic Design

White Goods Become Smart Goods

The latest home appliances sport features that make their predecessors look as obsolete as washboards and iceboxes.

Watch an LCD TV or surf the Web on your refrigerator. Chat with your washing machine. Let your dishwasher decide when the dishes are done. Enjoy a hot cup of joe with just the right amount of cream and sugar, dispensed by your coffee maker with skill that would put any barista to shame. And you won't need to wait decades for these advances. They're happening right now.

There's a revolution in modern white goods as the industry moves from its electromechanical roots to electronic control, using semiconductor ICs to boost the intelligence of these appliances. As chips see more IC integration, cost effectiveness increases, making their inclusion practical. Now it's not unusual to find appliances with ICs that pack an analog-to-digital converter (ADC), a pulse-width-modulator (PWM) generator, a timer, I/O circuitry, and a watchdog circuit all on a single die. Some of these features may seem esoteric or even questionable. But many consumers demand sleek, modern-looking appliances with premium features, and they're willing to pay a little more for them. According to market research company IMS Research, total semiconductor revenue for white goods is projected to increase to $920.6 million in 2008, compared with $505.3 million in 2003 (Fig. 1).

"Only four to five years ago, the penetration of electronics into white goods appliances was no more than 25% to 30%," says Fraser McHenry, product marketing manager for Freescale Semiconductor's microcontroller division. "Now it is more than 50% and growing. We see 80% levels in the near future."

Considering the stringent requirements white goods manufacturers demand from IC makers and the constantly decreasing price tags of white goods, there seems to be a paradox. Design engineers are being asked to make appliances more intelligent, sleeker, easier to use, and more reliable. But they're also facing constant market pressures to keep prices within consumer expectations.

"You cannot solve the design challenges posed by modern white goods appliances using only hardware in order to obtain high performance at low cost. You must integrate both hardware and software in a design," explains Arafeen Mohammed, systems applications engineer at Texas Instruments. "People simply expect more from an appliance today and want to pay less money for it."

Even with today's features, washing machines now cost a lot less than machines made a few years ago with hardly any intelligence. "Cost is a big issue. It's the perceived value of what you bring to the game," says Claire Jackoski, a strategist with Freescale Semiconductor. She believes that the value proposition of an appliance will be the deciding factor in what features consumers select when buying an appliance.

Design engineers have risen to the challenges by maximizing use of electronics, much of which is embedded. Sensors, DSPs, microcontrollers, power devices, actuators, and flash memory ICs figure heavily in appliance design. They also have let appliance manufacturers offer consumers a wider range of operational features in a given appliance type, with each model (from basic to high end) priced at a different level.

Energy-efficiency legislation has had a big effect on the use of electronics in white goods. So have concerns about water conservation, radio-frequency interference/electromagnetic interference (RFI/EMI) mandates, the Restrictions on Hazardous Substances (RoHS) directive, and quieter appliance operation.

"Today, more households have two working adults (husband and wife) who are more likely to do their household chores (like clothes and dishwashing) at night after work, which means quieter operation. That's why we're seeing a trend toward using brushless dc motors," says Freescale's Fraser McHenry.

Energy efficiency ratings (EERs) are becoming more strict worldwide. For example, every appliance sold now requires an Energy Star label as spelled out by the U.S. Department of Energy (DoE) and Environmental Protection Agency (EPA).

"There's a big demand for greater energy efficiency and water conservation. In Europe, this is a key issue for white goods appliances and is becoming more mandatory in the U.S. with states like California leading the way," says Raúl Figuroa, marketing and applications engineer with Freescale Semiconductor.

And if you can't conserve energy, stay out of the kitchen. A typical modern refrigerator with automatic defrost capability and a top-mounted freezer uses less than 500 kWh/year, while the average 1973 model consumed 1800 kWh/year, according to appliance maker Whirlpool Corp.

Even issues like power-factor correction (PFC) in motor-driven appliances are becoming important for greater electrical energy savings. PFC is mandatory in Europe, Japan, China, and parts of India, and it's expected to become so in the U.S. soon. International Rectifier has designed an iMotion digital controller for maximizing PFC. The IRMCF3xx integrated design platform consists of a controller and a PWM driver with integral insulated-gate bipolar transistors (IGBTs) and FETs (Fig. 2).

The greatest potential for energy and water savings exists in washing machines. According to several major appliance manufacturers, a new washing machine consumes about 14% less electricity and a whopping 87% less water than a unit sold a decade ago. This translates into a 31% drop in operating costs. Surprisingly, one of the main reasons for these savings is the use of a front-loading design instead of top-loading.

In top-loading machines, the water level must rise in the tub to near the top before the agitator wets the clothes. But in front-loading machines, water doesn't completely fill the tub. The tub itself rotates, tumbling the clothes into the water. In addition, the drum in many front-loading models is driven directly by a permanent-magnet synchronous motor with no need for a gearbox or drive belt as top-loading models require.

Dishwashers also are benefiting from electronic controls for energy and water savings. Freescale Semiconductor has shown how far electronics can penetrate dishwasher designs with an all-electronic platform (Fig. 3). The platform includes electric-field (E-field) sensors introduced earlier this year for better water-level sensing and noise resolution (see "Low-G Sensors Mold A New Market," May 11, 2006, p. 37, ED Online 12434).

Freescale's MC34940 E-field touch and noncontact sensor detects an electric field's strength as the capacitance changes between an object being sensed and ground. It can be used in refrigerators for ice-cube detection, the icing/defrosting cycle, and interactive displays, as well as in oven control panels. Other uses include hand detection for kitchen extractor hoods, boil-over load detection in cooking tops, and water-level and load detection in washing machines.

The most noticeable advance in energy savings comes from motors and motor controls. Many of these motors are three-phase induction models. The newer devices are brushless dc and permanent-magnet synchronous motors, which are 30% smaller and 10% to 15% more efficient than induction motors (Fig. 4). Brushless dc and permanent-magnet motors also are beginning to replace traditional high-voltage drivers and IGBTs.

Many microcontroller chips on the market can be used to drive these motors and compressors. As appliances become more sophisticated, though, more microcontrollers are being added. Besides motor control, an appliance might need another microcontroller for the front-panel user interface and yet another for overall machine control. Many of these microcontrollers are replacing discrete components on older appliance designs.

Scalar control, a basic technique that's been in use for motors, applies a given input voltage to the motor, which then produces a known motor speed and direction. It requires modest computation levels that can be accomplished by a microcontroller chip.

Texas Instruments uses field-oriented control (FOC) in its TMS320C2000 DSP-based controller. FOC is very computationally intensive, well beyond the capabilities of microprocessors. The DSP provides a powerful engine for handling the motor's electromagnetic field. The addition of a wide range of peripheral functions integrated into the DSP structure creates a full digital signal controller with a slew of functions.

The chip is quite complex. It contains a 16-channel, 12-bit resolution ADC with dual sample and hold, two general-purpose timers, one motor position/speed sensor, a watchdog timer, 13 digital I/O shared ports, one serial communications interface, and up to 8 kwords of on-chip flash memory for storing motion profiles and other information (Fig. 5).

Italian appliance manufacturer Indesit Co. (formerly Merloni) uses the chip in its line of Ariston Super Saver washing machines. "After considering and testing different technologies, the TI DSP solution was chosen due to the processor's performance and the flexibility of its peripherals," says Stefano Frattesi, a control systems engineer at Indesit.

DSP ICs can be an unnecessary and more expensive solution for appliance control in some applications. STMicroelectronics, though, offers the low-cost 8051-class 8-bit µPSD325x microcontroller, which contains a 16-macrocell programmable-logic device (PLD).

"We've developed a low-cost controller with a macrocell that's optimized for use with brushless dc motors that can also work with three-phase induction motors," says Tom Hopkins, director of the industrial applications lab at STMicroelectronics. "The macrocell handles a lot of the computation timing and sensing functions."

In white goods, the human-machine interface (HMI) is a key factor in customer satisfaction. No matter the appliance's level of operational sophistication, the HMI must be very effective and can make or break market success, since it is the product's"face" that the user sees. A well-designed graphical user interface (GUI) can provide an intimate and stylish look that's also easy to operate.

"Engineers are always busy making products work better with more functions. But they have very little concept of the HMI," explains Ken Klosk, CEO of Amulet Technologies. Amulet is a fabless semiconductor company that focuses on chips and firmware that drive LCD user interfaces. "A big challenge is trying to improve operational features while at the same time make them easier to operate. In addition, the HMI must be as dependable as the appliance itself."

Hardware and software design engineers often use intuition when designing the GUI. They view the appliance user as another person like them, a sophisticated person with technical know-how. But this approach doesn't work when it comes to white goods.

For example, take mobile phones. A study by J.D. Powers and Associates notes that consumers are becoming more frustrated with their mobile phones as more features and services are added. It's often difficult (and sometimes impossible) to navigate the phone's multitude of features and capabilities.

Many of the GUI design factors for some white goods like refrigerators are challenging because the appliances are never turned off. They operate day and night and employ medium-sized micro-controllers that lack the resources to control a GUI and a device at the same time.

In addition, an industrial designer develops the look and feel of the appliance instead of the software programmer. And when the software program is developed, dynamic memory management is required, leading to memory leaks and fragmentation.

This requires more memory. Flash has been a big help in the overall need for higher levels of IC integration. Older microcontrollers used about 16 kbytes of memory. Now they use 32 kbytes or more, and they may go up to 64 kbytes as more intelligence is added. But there's a limit to how much memory can be cost-effectively added when an appliance is operating 24/7.

With Amulet Technologies' Graphical OS in Silicon architecture, OEMs can cost-effectively improve the user experience of their electronic devices with visually appealing, interactive user inter-faces with a high degree of reliability (Fig. 6). The architecture partitions a GUI design into multiple small processors that make software development and testing more manageable and less prone to errors. The GUI can be made as simple as possible, but not so simple that it's ineffective.

Future white goods will be even more intelligent. Indesit is working on washing machines that can determine which RFID-tagged clothes can be washed together and how much detergent can be used on a load. Future refrigerators will be able to propose nutritious meals and recipes using RFID-tagged food while warning consumers which foods are about to expire.

Each home appliance will be one node in a network where they can communicate with each other via the Internet or other means. The entertainment and security systems will be hooked into this network, as well as HVAC systems. This capability will give homeowners remote access to diagnostic, operational, and other information while enabling them to remotely control appliance settings.

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TAGS: Freescale
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