Abstract
The magnetic levitation reaction flywheel (MLRW) is a novel actuator of spacecraft attitude control because of its significant advantages, including lack of friction and active suppression of vibration. However, in a vacuum environment, the poor heat dissipation conditions make it more sensitive to various losses and rises in temperature. Therefore, increasing temperature is the key issue for components used in space. In this study, the losses of the three kinds of heat-generating areas in the MLRW, namely, the passive magnetic bearing (PMB), the active magnetic bearing (AMB) and brushless DC motor (BLDCM), were analyzed and calculated. Based on the electromagnetic field theory, the loss model of PMB was proposed. Based on the finite element method (FEM) and Bertotti model, the loss power of the AMB and the BLDCM was obtained. The calculated loss values were brought into the FEM to calculate the temperature field distribution of the MLRW system. Then, the key factors affecting the heat dissipation of the flywheel were obtained by combining thermal network analysis with the temperature field distribution. Finally, a prototype was fabricated. The maximum estimated and experimental temperatures were 34.8 °C and 36.8 °C, respectively, both at the BLDCM stator. The maximum error was 5.4%, which validates the calculated model.
Highlights
Reaction flywheels supported by active magnetic bearing (AMB) and passive magnetic bearing (PMB) are very important apparatus in spacecraft attitude adjustment [1,2]
Reaction flywheels supported by AMBs and PMBs are very important apparatus in spacecraft attitude adjustment [1,2]
The magnetically suspended reaction flywheel is driven by a brushless DC motor (BLDCM) and supported by an AMB in two radial-direction degrees-of-freedom (DOFs) and a PMB in the other three
Summary
Reaction flywheels supported by AMBs and PMBs are very important apparatus in spacecraft attitude adjustment [1,2]. In an MLRW, the main losses are the copper and iron losses in the AMB, PMB, and BLDCM. The loss of the flywheel system was calculated to determine the distribution of the main heat source of the system, and an equivalent thermal network model was established based on the whole mechanical topology structure [12]. [14], an analytical model for predicting the iron losses in high-speed shotless PM machines is presented, and was verified by 2-D. [15] presents the analytical method of calculating losses of AMBs based on the reluctance network method. The main contributions of this study are the systematic derivation of the PMB loss model, the loss calculation of the components of the MLRW, thermal analysis, and structural optimization. A prototype was fabricated to verify the calculated model
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