Appliance Design - June 2008 - (Page 42)

ELECTRONICS Fig. 2. Sensor signal plus noise in the time domain. Fig. 3. Sensor signal plus noise in the frequency domain. thing in common: they are enabled shifts have been the availability of by progressively more sophisti- cost-effective control, and the time cated electronic control, coupled needed to understand and refine with an economically4/7/06 2:11 PM Page 1 viable con- the technology. AD05062Therm Many underpinnings of those trol solution. The primary impediments delaying these dramatic impediments have been removed with modern DSCs, which offer cost-optimized and applicationoptimized performance coupled with robust applications support. Regulatory add-ons, such as active power factor correction, exacerbate the control workload and accelerate acceptance of the digital solution. As DSCs continue to add capability and performance while prices continue to decrease, new possibilities for product development emerge. This can be illustrated with the example of the merging of digital motor control with digital sensor processing onto one DSC. Digital sensor processing Today, a sensor signal within a typical motor-driven appliance is filtered, level shifted, amplified and fed to the Analog-to-Digital Converter (ADC) of an embedded controller. The performance of the embedded application depends on accurate information coming from the sensor. Sensors can degrade with use, which may accelerate product failure. Analogfilter and gain characteristics can change over time, temperature and manufacturing variations. Digital sensor processing can be employed to provide advanced compensation for a variety of sensor conditions, including sensor degradation, performance reductions in age-sensitive or temperature-sensitive components, failure prediction, substituting a less expensive sensor without performance loss, or improving sensor accuracy. Since DSCs are increasingly being used for motor control, they provide an opportunity to utilize excess resources to also handle digital sensor processing tasks. Fig. 1 illustrates the resource utilization for an advanced sensorless FOC algorithm on a 28-pin 128 KB Enabler Electronic Control Sensorless Control Digital Control Result Elimination of Commutator in Motor Casing Elimination of Hall Effect Sensors Advanced Algorithms for Efficiency & Performance Table 1. Disruptive technology shifts in DC motor control For more Information Enter 114 42 applianceDESIGN June 2008 www.applianceDESIGN.com http://www.thermtrol.com http://www.thermtrol.com http://www.appliancedesign.com

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Appliance Design - June 2008 Contents Editorial Shipments/Forecasts News Watch 21st Annual Excellence in Design Winning Designs Combine State-of-the-art Technology with . . . Meet the Judges Design Marts Fans & Blowers Mother Nature Has Her Own Ideas About Designing for Fluid Flow . . . Using CFD Simulation Software Early in the Product Development . . . Electronics Digital Signal Controllers Enable Digital Motor Control . . . Classifieds Meetings Advertiser’s Index Association Report: AHRI

Appliance Design - June 2008

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