| 摘要 |
<p>A brushless DC motor which is used as a drive source of a refrigerant compressor for a refrigerating apparatus or of a blower. A position detecting means (28), which generates a control signal by detecting terminal voltages at the input/output terminals through which the electric currents flow into three-phase coils (23a, 23b, 23c), comprises filters (111, 121, 131) for converting terminal voltages into smoothed signals, synthesizing means (118, 128, 138) for producing three kinds of synthetic signals from the smoothed signals, and comparing means (119, 129, 139) which produce control signals to switch the current path to the three-phase coils based upon signals formed by comparing the synthetic signals with the smoothed signals. The current path to the coils (23a, 23b, 23c) is switched in turn by a switch drive unit (29) in response to control signals generated by said position detecting means (28). According to the above structure, it is possible to provide a brushless DC motor which is capable of switching the current path to the coils without using any particular position detecting element.</p> |
