| 摘要 |
PURPOSE:To constitute a controller, which does not require high rating, by providing voltage detector detecting the line voltages of a plurality of linear motors, a differential voltage detector comparing the outputs from the voltage detectors, and means for controlling a variable voltage variable frequency(VVVF) inverter. CONSTITUTION:Linear motors 5A, 5B are fed with current according to a circuit constant determined by a rail 6 and the gap between. When only the linear motor 5A enters into a reaction plate missing part, power factor thereof drops considerably but power factor of the linear motor 5B is maintained at a steady level. At that time, output from a voltage detector 4A drops and output from a voltage detector 4B increases. When the output from a voltage difference detector 7 exceeds a preset level, an excessive voltage is applied on the linear motor 5B. A voltage command subtractor 8 lowers the voltage command of an inverter 3 thus preventing the exciting circuit of the linear motor 5B from saturation. |
