| 摘要 |
A motor (1) with 3 (or more) stator windings (2,3,4) and a rotor (6) excited by permanent magnet (7) receives its supply from a controller (20) comprising a power source (5) and rotor angle sensor (22). The former responds to a control signal (Uo) from the sensor by applying voltages cyclically (Ua,Ub,Uc), to the stator windings, equal in amplitude but differing in phase by 120 deg., thus constituting a 3-phase square-wave system whose rotating field causes the rotor to rotate. For correct switching of the stator voltages the rotor's angular position must be known. A detection unit (24) in the sensor, connected to the motor supply circuits, contains RC circuits which resonate with the motor winding inductances. An output signal (U ), at one frequency, is measured and two of the sampled voltages (Ua,Ub,Uc) are then transposed, providing a second signal (U2) at a different frequency. Opt., the relevant detector circuits are duplicated, allowing the two signals to be measured simultaneously. The output signals are compared in a calculation unit (26), based on a frequency/voltage converter, which derives the required control signal (Uo) for the power unit (5). |
