| 摘要 |
An inverter for supplying a grid, where the inverter comprises a DC link comprising two capacitor units in series and a neutral point (V DC0 ) between the capacitor units, and a first and a second inverter leg. Both inverter legs are connected between the poles (V DC+ and V DC- ) of the DC link and comprise four switching devices (S n 1 - S n 4 ) connected in series, each switch having a conductive state and a non-conductive state and the switches together forming a low resistance route from the positive pole of the DC link to the negative pole of the DC link when all are in the conducting state. Both inverter legs comprise an upper connection point (V n 12 ) between the two topmost switching devices (S n 1 , S n 2 ), a lower connection point (V n 34 ) between the two bottommost switching devices (S n 3 , S n 4 ), and an output (V n 23 ) between the two middle switching devices (S n 2 , S n 3 ). Both inverter legs comprise a first rectifier device connected between the DC link neutral point (V DC0 ) and the leg upper connection point (V n 12 ) allowing flow of current in the direction of the leg upper connection point (V n 12 ), and a second rectifier device connected between the DC link neutral point (V DC0 ) and the leg lower connection point (V n 34 ) allowing flow of current in the direction of the DC link neutral point (V DC0 ). Both inverter legs further comprise a third rectifier device connected between the upper connection point (V n 12 ) of the leg and the output (V n 23 ) of the other leg allowing flow of current in the direction of the leg upper connection point (V n 12 ), and a fourth rectifier device connected between the output (V n 23 ) of the leg and the lower connection point (V n 34 ) of the other leg allowing flow of current in the direction of the output (V n 23 ) .
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