Appliance Design - October 2007 - (Page 26)

MOTORS Extending Efficiency A Microchip dsPIC digital signal controller. Advanced control methods more accessible to wider range of appliances. A by jorge zambada Jorge Zambada is senior applications engineer, Digital Signal Controller Div., Microchip Technology, Chandler, Ariz. 26 applianceDESIGN October 2007 dvanced motor-control techniques are a practical necessity because they enable more efficient and quieter appliances. In the past, these advanced control techniques were only available as proprietary solutions, and hence were limited in scope to a few highend appliances. Given the drive toward efficient appliances running on “green” power, which is mandated by regulations and customer preferences, these motorcontrol algorithms are now being sought by designers of all classes of appliances. Thanks to the new generation of digitalsignal-controllers (DSCs), the cost-effective implementation of advanced motorcontrol algorithms has become a reality. From the slew of advanced motor-control techniques available today, the FieldOriented Control (FOC) algorithm has solid claims on being the leading technique for helping to save energy and building quieter appliances. DSC-based FOC control over a Permanent-Magnet Synchronous Motor (PMSM) will serve as an example. Sensorless FOC control has advantages over the sensor-based version, because it overcomes impediments in some applications that cannot afford to deploy position or speed sensors. In certain compressor applications, for example, the motor is flooded in oil, making wire-harness placements difficult. Today’s motor-control solutions rely on costly custom ASICs to implement a FOC algorithm. Further compounding the difficulty is the fact that these ASICbased FOC algorithms and related libraries are inflexible — users cannot tailor the FOC algorithm based on the application requirements. Additionally, delivering green power to the appliance requires the addition of a Power Factor Correction (PFC) circuit. Existing appliance power stages are also dependent on costly custom www.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - October 2007

Contents Editorial Shipments/Forecasts News Watch Applying Powder Coatings to Plastic Parts is No Longer a Pipe Dream New Technology Platform Provides the Ability for a single IC to Control Two- Motors in a Single Appliance, Simplifying Motor Control Design Advanced Motor-Control Techniques have Become More Accessible to a Wider Array of Appliances, Helping to Improve Efficiency and Reduce Noise Adding USB Host Capability to Appliances Permits In-Field Programming and Acquisition of Test Data ZigBee Modules Make it Easier to Design Wireless Connectivity into Applications New Concepts such as Rapid Tooling and Rapid Injection Molding Provide Stepping Stones Between Prototyping and Full Scale Production A Number of Factors and New Developments Affect the Decision on Whether to Build Prototypes In-House or Outsource to a Service Bureau DesignMart Advertiser’s Index Association Report: CEA

Appliance Design - October 2007

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