Technology analysis of magnetically supported rotors applied to a centrifugal compressor of a high-temperature heat pump
Kepsu, Daria (2022-05-13)
Väitöskirja
Kepsu, Daria
13.05.2022
Lappeenranta-Lahti University of Technology LUT
Acta Universitatis Lappeenrantaensis
School of Energy Systems
School of Energy Systems, Sähkötekniikka
Kaikki oikeudet pidätetään.
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In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of Lappeenranta-Lahti University of Technology LUT's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_ standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-821-8
https://urn.fi/URN:ISBN:978-952-335-821-8
Tiivistelmä
Despite decades of development of high-speed motors, challenges and limitations concerning high-speed powertrains and motors in industrial applications remain. Improved reliability and a smaller footprint together with lower maintenance needs while delivering compressor modules with a high pressure ratio can be offered by an integrated solution where the compressor wheels are directly coupled with a high-speed motor on the same shaft. The solution omits the gearbox and eliminates the ancillary support system and the need for a lubricant as benefits of the magnetically supported powertrain technology.
High-speed powertrains, using active magnetic bearings (AMBs) or a bearingless motor (BLM), are highly sought after not only in centrifugal compressors but also in high precision machine tools, flywheels, and heat pumps. When high-speed, maintenance-free electrical machines are intended for an application of this kind, multidisciplinary know-how and in-depth analyses of the application are essential from the earliest stage of design. Nevertheless, the design process of a magnetically supported high-speed powertrain for a centrifugal compressor of a high-temperature heat pump (HTHP), incorporating various multidisciplinary challenges in the design of magnetically supported rotors, has not yet been reported in the literature. In this doctoral dissertation, a multidisciplinary design process and the challenges involved in the design of a powertrain in an HTHP are presented. Various design aspects, such as mechanical, electromagnetic especially with suspension force analyses, thermal, and cooling constraints are also investigated by finite element analysis (FEA). In this dissertation, a powertrain is defined as a system that includes a magnetically supported rotor, its actuating components, e.g., BLMs, AMBs, and backup bearings, and furthermore, the sensors, the inverters, and other mechanical parts, where the actuators are investigated through the thesis. The compressor powertrain includes the compressor wheels in addition to the powertrain.
Before a compressor powertrain for an industrial application can be manufactured, an accurate design and a multidisciplinary FEA are required. The design of the rotor, comprising the motor and the compressor wheels, commences with the requirements set by the application, i.e., speed, power, and force capacity, that together with electromagnetic, mechanical, and thermal constraints outline a suitable structure for the motor and compressor wheels. A subsequent study of the initial rotor dynamics defines the feasibility of the proposed structure. Next, its electromechanical and suspension performance are addressed, and the system losses analyzed. The losses, acting as thermal loads, are the starting point for the thermal assessment and the subsequent cooling design.
The design of a high-speed actuator for a high-pressure compressor (HPC), intended for an HTHP, involves various interlinked challenges, such as choosing suitable materials that will guarantee structural strength, suitable speed range for the compressor and the actuator, allowing for high speed with good performance in terms of rotor dynamics, cooling, and control. Through case studies of a permanent magnet synchronous motor (PMSM) powertrain with AMBs and a bearingless PMSM (BLPMSM), the performance of the powertrains is investigated and compared by analyzing electromechanical, rotor dynamics, and thermal simulation results. The challenges and differences of the designs are deliberated. In conclusion, a summary of the satisfactory simulation results, fulfilling the speed range with good structural strength and electromagnetic performance and a well-designed way of removing heat, leads to a suitable design for the powertrain of the compressor for a heat pump application. As a conclusion to the multidisciplinary design process, the upcoming manufacturability challenges are elaborated. The efficiencies of the powertrain with AMBs and BLMs for an HTHP application are compared.
High-speed powertrains, using active magnetic bearings (AMBs) or a bearingless motor (BLM), are highly sought after not only in centrifugal compressors but also in high precision machine tools, flywheels, and heat pumps. When high-speed, maintenance-free electrical machines are intended for an application of this kind, multidisciplinary know-how and in-depth analyses of the application are essential from the earliest stage of design. Nevertheless, the design process of a magnetically supported high-speed powertrain for a centrifugal compressor of a high-temperature heat pump (HTHP), incorporating various multidisciplinary challenges in the design of magnetically supported rotors, has not yet been reported in the literature. In this doctoral dissertation, a multidisciplinary design process and the challenges involved in the design of a powertrain in an HTHP are presented. Various design aspects, such as mechanical, electromagnetic especially with suspension force analyses, thermal, and cooling constraints are also investigated by finite element analysis (FEA). In this dissertation, a powertrain is defined as a system that includes a magnetically supported rotor, its actuating components, e.g., BLMs, AMBs, and backup bearings, and furthermore, the sensors, the inverters, and other mechanical parts, where the actuators are investigated through the thesis. The compressor powertrain includes the compressor wheels in addition to the powertrain.
Before a compressor powertrain for an industrial application can be manufactured, an accurate design and a multidisciplinary FEA are required. The design of the rotor, comprising the motor and the compressor wheels, commences with the requirements set by the application, i.e., speed, power, and force capacity, that together with electromagnetic, mechanical, and thermal constraints outline a suitable structure for the motor and compressor wheels. A subsequent study of the initial rotor dynamics defines the feasibility of the proposed structure. Next, its electromechanical and suspension performance are addressed, and the system losses analyzed. The losses, acting as thermal loads, are the starting point for the thermal assessment and the subsequent cooling design.
The design of a high-speed actuator for a high-pressure compressor (HPC), intended for an HTHP, involves various interlinked challenges, such as choosing suitable materials that will guarantee structural strength, suitable speed range for the compressor and the actuator, allowing for high speed with good performance in terms of rotor dynamics, cooling, and control. Through case studies of a permanent magnet synchronous motor (PMSM) powertrain with AMBs and a bearingless PMSM (BLPMSM), the performance of the powertrains is investigated and compared by analyzing electromechanical, rotor dynamics, and thermal simulation results. The challenges and differences of the designs are deliberated. In conclusion, a summary of the satisfactory simulation results, fulfilling the speed range with good structural strength and electromagnetic performance and a well-designed way of removing heat, leads to a suitable design for the powertrain of the compressor for a heat pump application. As a conclusion to the multidisciplinary design process, the upcoming manufacturability challenges are elaborated. The efficiencies of the powertrain with AMBs and BLMs for an HTHP application are compared.
Kokoelmat
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