A simple slip-power recovery system with a DC voltage intermediate circuit and reduced harmonics on the mains

A different circuit configuration for the slip-power recovery system is presented in this paper. A boost chopper is used to connect the diode rectifier to the DC-link voltage, which is composed of a capacitor and a voltage-source inverter (VSI). The diode rectifier gives rise to mains current harmonies of variable frequency, which can present subharmonics, harmonics, and interharmonics that can lead to flicker in the mains. Two simple solutions to this drawback are studied. In the first solution, additional inductances were connected on the AC side of the rotor circuits to increase the overlap angle. In the second solution, the stator current harmonics are compensated by a VSI that can work simultaneously as an inverter and as an active power filter. This system represents a very interesting and useful application for active power filters. The merits of the configuration presented are cost, control simplicity, the possibility of reactive power control over a wide range, and quasioptimum exploitation of the electrical machine. The characteristics of the proposed system and its control are presented in this paper. It is concluded that, although the system proposed is much simpler than others, it has interesting performance.