Synchronization of the distributed PWM carrier waves for modular multilevel converters

Current control of modular multilevel converters with phase‐shifted pwm using a daisy‐chained distributed control system

“…To reduce the number of fibers effectively, distributed control systems have been proposed, which consist of an upper‐level controller (primary controller) and lower‐level controllers (cell controllers) . The cell controllers are implemented in all the cells independently.…”

“…Figure shows the possible network topologies of the controllers, including (a) star, (b) bus, and daisy‐chained [(c) line and (d) ring] topologies . The star topology corresponds to the conventional centralized control system.…”

“…To reduce the number of fibers effectively, distributed control systems have been proposed, which consist of an upper-level controller (primary controller) and lower-level controllers (cell controllers) [10][11][12][13][14][15][16][17][18][19][20][21][22][23] distributed among the controllers; for example, the cell controllers contain carrier comparators, and voltage references are transmitted from the primary controller. A hierarchal topology that includes a middle-level controller for the function of intercell balance control can also be applied [19][20][21][22].…”

“…A hierarchal topology that includes a middle-level controller for the function of intercell balance control can also be applied [19][20][21][22]. Figure 1 shows the possible network topologies of the controllers, including (a) star, (b) bus, and daisy-chained [(c) line and (d) ring] topologies [12][13][14][15][16]18,24,25]. The star topology corresponds to the conventional centralized control system.…”

“…Promising network systems for the controller communication include 'EtherCAT' [12][13][14][15][16]26], CAN [11,17], and 'PROFINET IRT' [12,26]. 'EtherCAT' offers a high-speed realtime communication, the ring-type daisy-chained topology, and cell synchronization.…”