The design of the spindle drive is based on autonomous drives, which are supplied with electric power by a common DC link. Fig. 4 shows the schematic diagram of the spindle drives in a textile machine.
The common DC link is fed from the power line by a rectifier. If the auxiliary drives, like these for winding up etc. and the controller of the textile machine are fed from this DC link, the kinetic energies, stored in the spindles could span a failure of the mains. This would be a great advantage for the operation of the textile machine in countries with weak power grids. In case of a failure the whole machine can be shut down correctly even without an emergency power supply.
If the line rectifier is not able to feed power back into the mains, other consumers - like the drives for winding up - have to be fed by the DC link. It might be advantageous to use an AC/DC converter instead of the passive rectifier not only because of regenerative breaking, but the textile machine could easily be adjusted to many different line voltages. An adjustable AC/DC converter might also compensate reactive power in the mains, caused by other consumers .