| 摘要 |
A system for supplying a polyphase a.c. motor from a d.c. supply comprises a pair of switching transistors Q141, Q142, for each phase of the motor, one Q141 of the pair of transistors interconnecting the positive terminal of the d.c. supply B14 to a phase terminal A-I of the motor and the other Q142 of the pair of transistors interconnecting the negative terminal of the d.c. supply B14 to that phase terminal A-I of the motor, the transistors of the pair being switched alternately and the pairs sequentially by a control circuit which can control the rate of switching to control the frequency applied to the motor. The direction of rotation of the motor can be reversed by reversing the sequence of switching of the transistors of the pairs. The d.c. supply is a battery, and when the load over runs the motor it can act as a generator and power can be fed back to charge the battery. <IMAGE> |
