| Summary: | Different from ordinary AC machines, the design of a bearingless permanent magnet slice motor (BPMSM) considers not only the torque performance, but also the passive and active suspension properties. In addition, BPMSM for a maglev centrifugal pump has unique design characteristics due to the integration of the pump head and sensors. This paper investigates evaluation and design techniques based on a cluster of performance metrics targeting on developing BPMSM for a maglev centrifugal pump. The cluster of performance metrics for BPMSM, including passive stiffness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>z</mi></msub></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfenced separators="" open="|" close="|"><msub><mi>k</mi><mi>z</mi></msub><mo>/</mo><msub><mi>k</mi><mi>x</mi></msub></mfenced></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfenced separators="" open="|" close="|"><msub><mi>k</mi><mi>z</mi></msub><mo>/</mo><msub><mi>k</mi><mi>y</mi></msub></mfenced></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>α</mi></msub></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>β</mi></msub></semantics></math></inline-formula>) and active factors (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>i</mi></msub></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>c</mi><mi>m</mi></msub></semantics></math></inline-formula>), is first proposed and an evaluation function <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>f</mi><mi>i</mi></msub><mfenced separators="" open="(" close=")"><msub><mi>S</mi><mi>i</mi></msub><mo>,</mo><msub><mi>L</mi><mi>i</mi></msub></mfenced></mrow></semantics></math></inline-formula> is constructed. Then, practical configurations of BPMSM for a maglev centrifugal pump are summarized. Based on the cluster of performance metrics, the finite-element method (FEM) is used to explore the impact of the rotor magnetization (sinusoidal, diametric, and radial method) on motor properties. Subsequently, the complete design process of BPMSM for a maglev centrifugal pump is introduced and key differences (including three crucial geometric parameters: ratio of rotor height to diameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>λ</mi></semantics></math></inline-formula>, magnetic gap length <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>δ</mi></semantics></math></inline-formula>, and stator tooth width <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>α</mi><mrow><mi>s</mi><mi>t</mi></mrow></msub></semantics></math></inline-formula>) in the design considerations between BPMSM and general bearingless motors are analyzed. Finally, the upgraded performance (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>z</mi></msub></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>α</mi></msub></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>β</mi></msub></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>k</mi><mi>i</mi></msub></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>c</mi><mi>m</mi></msub></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>f</mi><mi>i</mi></msub><mfenced separators="" open="(" close=")"><msub><mi>S</mi><mi>i</mi></msub><mo>,</mo><msub><mi>L</mi><mi>i</mi></msub></mfenced></mrow></semantics></math></inline-formula> increased by about 29%, 38%, 33%, 31%, 21%, and 15%, respectively) of the designed candidate is obtained, which verifies the effectiveness of the proposed design methods.
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