| 摘要 |
PURPOSE:To improve the vector controllability of an induction motor with a current type inverter by detecting the zero point of positive and negative half waves of each phase current and obtaining the sum of the commutation delay angle and the angle superposed with he delay angle by the detection signal and a firing pulse signal. CONSTITUTION:The zero point of the positive and negative half waves of the each phase current of a motor 1 is detected by comparators 5, 6 and is applied to differentiating circuits 7, 8. The outputs of the circuits 7, 8 and the inverted outputs through inverters 10, 11 of the circuits 7, 8 are applied to OR gates 9, 12, the outputs of which are in turn applied thrugh a flip-flop 13, an AND gate 14 and counters C1, C2 to obtain a communtation delay angle Ud between a firing pulse signals and phase current and the sum of the commutation delay angle Ud and the superposed angle U. Accordingly, since it is obtained based on the zero point detection signal of the phase current, the delay angle and the superposed angle at the commutation time can be produced in high accuracy, thereby accurately obtaining the phase difference between the firing pulses of the thyristor to improve the controllability. |
