Patent ID: 8169797
Filing Date: 2012-05-01
Classification: H02M,Y02B,Y02P

Abstract:
1. An AC/DC intermediate-circuit converter having a very wide AC input voltage range with a ZVS three-level DC/DC resonant converter, which has four primary switches that are arranged in series between first and second DC intermediate-circuit connections and that include a first and a second outer primary switch, and a first and a second inner primary switch, the AC/DC intermediate-circuit converter comprising: a transformer having a primary winding; an LLC series-resonant circuit having a resonant inductance connected to a common connection point between the two inner primary switches; a magnetization inductance connected in parallel with the primary winding of the transformer and a resonant capacitor to a common connection point between the second outer primary switch and the second DC intermediate-circuit connection; an input capacitor connected between a common connection point between the first outer primary switch and the first inner primary switch and a common connection point between the second inner primary switch and the second outer primary switch; two intermediate-circuit capacitors being connected in series between the first and second DC intermediate-circuit connections with a common connection point between the two intermediate-circuit capacitors forming a DC intermediate-circuit centre connection; a rectifier having, on a DC side thereof, DC connections connectable to the first and second DC intermediate-circuit connections, and, on an AC side thereof, AC connections being configured to have an AC input voltage applied thereto; and a range changeover switch arranged between an AC input connection and the DC intermediate-circuit centre connection, wherein: the range changeover switch is configured to be closed in a lower AC input voltage range, when the ZVS three-level DC/DC is operated in accordance with a two-level operating mode in which, according to a first level of the two-level operating mode, the first outer primary switch and the first inner primary switch are driven jointly, and, according to a second level of the two-level operating mode, the second inner primary switch and the second outer primary switch are driven jointly, such that the LLC series-resonant circuit has the full DC input voltage, which is present between the first and second DC intermediate-circuit connections, applied thereto; the range changeover switch is configured to be open in a central AC input voltage range when the ZVS three-level DC/DC resonant converter is operated according to the two-level operating mode; the range changeover switch is configured to be open in an upper AC input voltage range when the ZVS three-level DC/DC resonant converter is operated according to a three-level operating mode, in which, according to one level of the three-level operating mode, the first outer primary switch and the second inner primary switch are operated in a complementary manner, and, according to another level of the three-level operating mode, the first inner primary switch and the second outer primary switch are operated in a complementary manner, such that the LLC series-resonant circuit has only half the DC input voltage, which is present between the first and second DC intermediate-circuit connections, applied thereto.