| 摘要 |
PURPOSE:To enable the direct phase control of secondary magnetic flux and secondary current of an induction motor by calculating the phase angle of the commutation pulse of a direct inverter without 2-phase to 3-phase conversion, thereby controlling the instantaneous values of the respective phases of the primary current. CONSTITUTION:The phase difference phi, between the secondary magnetic flux and the primary current calculated by the set signal of an exciting current I0 and the primary current I1 (DC current compensated for delay), the phase difference signal alpha, between the commutation pulse signals for each commutation point, and the phase difference signal beta, between the commutation pulse and the primary current I1 are calculated by arithmetic circuits 17, 22, 20 respectively. The phase angles of the prescribed firing pulse signals are determined by these three values phi, alpha, beta, while the thyristor group of an inverter 2 are sequentially commutated by the decided signals, thereby directly controlling the phase so that the secondary magnetic flux and the secondary current always cross with each other rectangularly. |
