| It is efficiently energy-saving to apply speed-adjusting technology on the occasion with centrifugal load such as pump and fan, thus permanent magnet adjustable speed drive(PMASD) is getting more widely applied for its good performance of speed-adjusting. However, eddy current heating is an unavoidable problem which PMASD will face. Therefore, it is necessary to control the temperature rise by cooling PMASD, in order to ensure normal working.By electromagnetic field finite element analysis of PMASD, eddy current distribution under different working conditions and the state eddy current moves in the copper rings is known. Then thermal analysis is done which acquire the thermal field distribution directly from eddy current loss, and the reason why that distribution forms is analyzed.The flow of air near PMASD is simulated, and the velocity vectors and path-lines of air is known from the simulation. Based on simulation of air flow, thermal-fluid coupled analysis considering eddy current loss as heat source is done to get distribution of thermal field, and the contours of temperature, heat flux and heat transfer coefficient are analyzed. Then the cooling effect is analyzed by implementing thermal-fluid coupled simulation with varying parameters of heat sink.Last, experiment is conducted to measure the output torque of PMASD, air velocity near the conductor rotor and the temperature of copper ring to check the result of simulations. The difference between values of output torque obtained by simulation and experiment is allowable in engineering, which proves the credibility of electromagnetic finite element method. Trend and peak of air velocity in flow field analysis is the same as that of data measured in experiment. Compared with the temperature from directly solving the thermal field, thermal-fluid coupled result is closer to the values measured in experiment, which shows that thermal field analysis considering fluid field is more practical and accurate. |
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