| 摘要 |
The output current from the armature to a lift drive motor is sensed and then used to augment the excitation field to compensate for the brush drop. An additional excitation coil may be used to produce roughly equal, but opposite polarity, voltage drop across the brushes, negating the brush drop. By sensing the actual current, this 'correcting voltage' has the same current voltage profile (but of opposite polarity) to that of the armature brush voltage drop since the current that is sensed also follows that characteristic. - When the excitation current to the armature is turned off, the correction voltage polarity is reversed to produce a counteracting field to the residual magnetism in the primary excitation coil. This 'suppressing field' is also proportional to the current that flows between the armature of the motor generator set and the lift drive motor. That current is a direct function of the armature output voltage produced from the residual magnetic field in the primary excitation coil.
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