| 摘要 |
678,018. Control of several A.C. motors. ENGLISH ELECTRIC CO., Ltd. Oct. 16, 1950. [Oct. 21, 1949] No. 27083/49. Drawings to Specification. Class 38 (iii). An electric transmission system for an electrically propelled vehicle adapted to operate from an external A.C. source comprises, in combination, a frequency changer arranged to be fed from said source, at least one driving motor of the change-pole induction type and a master controller arranged to effect the following operations in this order : (a) connect the motor to the frequency changer on the highest pole grouping ; (b) raise the frequency of the output from the frequency changer so as to accelerate the motor ; (c) re-connect the motor to the frequency changer on the next lower pole grouping and, whilst the motor is disconnected, reduce the frequency of the frequency changer output to a value corresponding approximately to the frequency required to operate the motor at its instantaneous running speed ; (d) again raise the frequency of the frequency changer output further to accelerate the motor and so on until maximum speed is reached with the motor connected on the lowest pole grouping and with the frequency changer operating at maximum frequency. The system may comprise a plurality of motor groups, each comprising one or more motors, and a frequency changer for each group, the controller being arranged to accelerate the groups of motors simultaneously on each pole grouping by raising the frequency of the output from all the frequency changers together and to effect the changing from one pole grouping to the next on each group of motors in turn whilst the remaining groups are providing a driving torque. Specification 678,016, [Group XXXV], is referred to. |
