Power converter with distributed cell control

• Main Authors: HARNEFORS LENNART, SILJESTROEM ROLAND, PETTERSSON ANDERS J, ASPLUND GUNNAR, DOEFNAES LARS
• Format: Patent
• Language: English
• Published: 19.03.2013
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION

A device for converting a DC voltage into an AC voltage and vice versa comprises a control system to control the voltage conversion and at least one phase leg (1) with a first (Uvp1) voltage source connected in series between a first DC terminal (4) and a first AC terminal (6) and with a second (Uvn1) voltage source connected in series between the first AC terminal (6) and a second DC terminal (5). Each of the voltage sources comprises at least a first and a second submodule (15) in series-connection, where each submodule (15) comprises at least two power electronic switches (16) connected in parallel with at least one capacitor (17). The control system comprises a central control unit (19) and at least two subunits (20), where the central control unit (19) transmits to each subunit (20) a reference AC voltage (ua_ref) and a switching carrier signal (s_sw) and where each subunit (20) controls the switching of the power electronic switches (16) of one of the submodules (15) according to a PWM pattern so that each time the switching carrier signal (s_sw) crosses the reference AC voltage (ua_ref) either the voltage across the capacitor (17) or a zero voltage are applied to output terminals (26, 27) of the corresponding submodule (15).