Power supply circuit having balance coil

摘要

Power supplies from the three-phase mains (1) to a DC-voltage load (5), in particular a DC-voltage intermediate circuit, generally consist of a controlled or uncontrolled 6-pulse input power converter (4) which is connected via line reactors (2) to the three-phase mains (1). In order to design such a power supply so as to be "mains-friendly", that is to say to keep the harmonic component of the supply currents of the power converter (4) small, it is proposed to double the pulse number by the use of a three-phase balance-coil circuit (3a) on the mains side between line reactors (2) and power converters (4). The three-phase balance-coil circuit (3a) on the mains side has three magnetic cores (18 to 20, 54 to 62) which are each provided with windings (6 to 17, 21 to 53). In order further to double the pulse number, two 12-pulse balance-coil circuits (3b, 3c) can be connected with the three-phase mains via a further balance-coil circuit (3a) having a turn-number ratio for 24-pulse operation. In order to make an 18-pulse circuit, a three-phase current-divider coil (67) can be provided between three-phase mains (1) and balance-coil circuit (3a). The current-divider coil (67) and the balance coil (3a) on the mains side may consist each of three single-phase cores or each of one three-phase core (four-limb or five-limb). <IMAGE>