| 摘要 |
PURPOSE:To achieve a highly accurate speed control without a speed detector by employing a double control loop through a slip angular frequency arithmetic unit and an overshooting prevention circuit as a feedback system for speed controlling and frequency controlling amplifiers. CONSTITUTION:A speed command value is passed through a soft starter 2 to obtain a slip angular frequency command signal omegas* and a secondary command signal I2 from a difference beween it and a rotor speed detection value and an angular frequency setting signal Fo is obtained from a difference between a signal omegas from a slip angular frequency arithmetic unit 5 and the command signal omegas*. A signal omegas from a differentiation circuit 9 is added to Fo to form a primary frequency control signal and a difference between a signal of an overshooting prevention circuit 4 and the command signal omegas is used as a rotor speed detection N D to lower the speed command of a soft starter 2 with a stall prevention circuit 17. This eliminates a speed detector enabling a highly accurate control of a slip frequency as a closed loop control. |
