| 摘要 |
<p>PURPOSE:To reduce the overflow amount of the main motor current over the current pattern when the frequency is changed in case of repower running by a a method wherein the switching requirements of the controlling frequency are constituted by either ones of the elapsed time after the gate starting and current flow rate or the main motor generating voltage or the car speed. CONSTITUTION:The timer circuit 11 outputs the signal of ''1'' at the time when the specified time Tc elapses after operating simultaneously with the gate starting in parallel with the time when the current flow rate gamma constantly detected and the switching current flow rate gammac are compared with each other by means of the comparison circuit 15 resulting in gamma>gammac. The memory circuit 13 transfers the transfer driving circuit 14 and the controlling frequency from f1 to the final frequency f2 when the output signal of the timer circuit 11 or the comparison circuit 15 becomes ''1''. Through these procedures, the controlling frequency may be switched before the specified time Tc elapses when the car speed is higher to some extent in case of the repower running and the like.</p> |
