| 摘要 |
<p>PURPOSE:To enable to detect the reversely rotating state of an induction motor without providing a rotating direction discriminating pulse generator by detecting the reversely rotating state of the motor by measuring and judging the internal impedance of the motor. CONSTITUTION:A deviation signal between a signal fi obtained by adding a slip frequency fa to a rotor frequency fr, a current instructing value IP and a motor current IM is applied to the frequency control input 5 and the voltage control input 6 of a modulator 4 for controlling an inverter 2. Further, the deviation between a voltage command VP obtained by converting the signal fi via a f/V converter 12 and a motor voltage is applied to a voltage limiting input 7. A pattern generator 10 outputs a signal responsive to the command VP, and a comparator 11 outputs a reverse rotation signal when the output signal of the generator 10 becomes larger than the motor voltage VM.</p> |
