| 摘要 |
An apparatus for controlling commutation of a three-phase variable reluctance machine includes a sensor (17), a sampling circuit, an inductance waveform generating circuit (58), a phase advance circuit (60), a threshold signal generating circuit (62), and an output comparator (88). The sensor includes a stack of several laminations 16s which are identical to the motor laminations (16m) that form the motor stator (12), and is mounted at one end thereof. The motor (10) includes a plurality of stator windings (28) forming a plurality of corresponding machine phases. The sensor (17) also includes a plurality of sensor windings (48i) electrically isolated from the stator windings (28). Each sensor winding (48i) is associated with a corresponding stator winding (28). Each sensor winding (48i) also has an inductance characteristic that varies according to an actual position of the rotor (24). The sampling circuit is coupled to the sensor windings (48i) for selectably energizing at least one of the windings (48i) to generate a plurality of pulses indicative of the current passing through the energized sensor windings (48i). The inductance waveform generating circuit (58) includes a sample and hold device (76) responsive to these pulses and outputs a generally sinusoidal signal indicative of an inductance waveform associated with the sensor winding (48i). The phase advance circuit (60) provides a turn-on signal having a magnitude that is modulated as a function of the motor speed. The threshold generating circuit (62) comprises a switch (90) operated in accordance with machine phase crossover transitions for selecting either the turn-on threshold, or a separately generated turn-off threshold voltage. The threshold voltage is compared with the inductance waveform, and a digital commutation signal is generated for the motor phase corresponding to the sampled sensor winding (48i). <IMAGE> |
