ELECTRIC SOURCE OF MOTOR-DRIVEN TOOL

摘要

The current supply allows a rectified AC voltage to be converted into arotary current, with variable frequency and amplitude, supplying the asynchronous drive motor. The frequency generator (67) is coupled to a rev. setting source (42) for selecting the appropriate frequency and amplitude values in accordance with a given characteristic. When a limit value corresponding to the peak motor load is reached the working point of the frequency/amplitude characteristic is adjusted to obtain a reduced frequency and voltage. Pref. the characteristic is provided by a function generator (66) coupled to the rev. setting source via a ramp generator (65).