DC control system for three-phase asynchronous motors - uses thyristor static inverters in pole amplitude phase shift method

摘要

The asynchronous, three-phase motor drive system uses the pole-amplitude, phase-shift modification principle. Each of the three-phase windings of a star- or delta -connected motor is fed from a static inverter using thyristor switches (11). These are supplied from a dc source and a regulator. A pulse frequency for switching the respective thyristors is derived from a generator, where frequency is controlled by an electromagnetic impulse unit attached to the motor shaft which provides a sum and difference slip frequency. This control signal can be processed in a 6-bit shoft-register to produce the required commutation sequence for the various phase- windings, the poles of which can be switched in different configurations without the use of mechanical devices.