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Delvis Gonzalez

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Senior Motor &amp; Magnetic Specialist

Danfoss

Integrating magnetic technology into high-speed centrifugal compressors delivers exceptional efficiency with enduring performance that remains uncompromised throughout the product's lifespan

High-speed direct-drive centrifugal turbo-compressors have demonstrated its great value proposition in HVAC industry because its simple structure, compact size and higher efficiency, compared to traditional centrifugal, scroll or screw compressors. To maximize these features, the design of the compressor needs to be matched with the right electromagnetic systems. The high- speed permanent magnet (HSPM) motors had become the common driver in centrifugal compressors due to their reliable and robust control over a wide speed range. HSPM motors are well known for a constant and higher efficiency compared to induction electric motors. The high- speed rotating machineries are commonly developed with magnetic bearings (MB) levitation systems. Because the contactless nature of the magnetic bearings, lubrication oil is not required, extending the operating speed of centrifugal compressor.


This presentation will explain the implementation of the permanent motors and magnetic bearing system in high-speed, oil-free centrifugal compressors. The HSPM motors are optimized to maintain efficiency of 97.0% up to 40,000 rpm. The motor control strategy is based on maximum torque per amp (MTA) up to the nominal voltage, and then field weakening (FW) is applied to maintain robust control over the complete operating range. The magnetic bearing system is based on five-axis control, homopolar actuators. During operation, the shaft of the compressor is kept levitated with no mechanical contact between the stationary and rotary components.


The unparalleled energy efficiency and consistent capacity with an oil-free magnetic bearing turbo-compressor, delivering over a decade of performance without degradation. This translates into substantial energy cost savings compared to traditional scroll or screw compressors. By preventing the common performance dips associated with oil-lubricated systems, we also achieve reductions in CO2 emissions. Discover the exceptional reliability and low-maintenance nature of these compressors, delivering a prolonged like-new performance that significantly extends the lifespan of your chillers for many years ahead.

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