| 摘要 |
A sensorless, brushless DC or permanent magnet synchronous motor 2, comprises at least three stator windings U, V, W connected in a star configuration. Two of the motor windings U, V are energized while leaving a third motor winding W unenergized and the back-EMF voltage generated in the unenergized winding is monitored. When the monitored voltage (V1) reaches a local maximum or minimum a commutation occurs to energize two windings U, W while leaving a third winding V unenergized according to a subsequent motor state of the energizing sequence. Alternatively commutation may occur at the end of a first time period (T1), a second voltage (V2) may be measured at a time interval after commutation and a subsequent time period (T2) calculated, based on the first time period T1, the first monitored voltage V1and the second monitored voltage V2. |
