| 摘要 |
A brushless permanent-magnet motor is controlled by sequentially exciting and freewheeling a winding of the motor. The winding is freewheeled for a predetermined period of time in response to current in the winding exceeding a current-limit threshold. A current-rise period corresponding to an interval between the start or end of freewheeling and the time at which current in the winding exceeds the current-limit threshold is measured and compared against a rise-time threshold. The rotor is deemed to be at a predetermined position when the current-rise period is less than or greater than the rise-time threshold and the winding is then commutated in response. The motor may comprise a four-pole permanent-magnet rotor that rotates relative to a four-pole stator. Conductive wires may be wound about the stator 6 and are coupled together (e.g. in series or parallel) to form a single phase winding. |
