Decentralized Control for the Cell Power Balancing of a Cascaded Full-Bridge Multilevel Converter

Abstract

In modern inverter applications, multilevel converters are used thanks to their capability of reducing the passive fi lter volumes, improving the overall THD, sharing the power sources across the several converter cells, and providing a reconfi guration ability in case of failure. However, increasing the number of cells makes more complex the control of the converter. This article proposes a decentralized control technique based on the use of elementary modular controllers, associated with each converter cell and communicating with their close neighbors to obtain the balancing of the powers they supplied. Each modular controller can be dynamically removed or added to allow reconfi guration of the converter for functional safety purpose. This method is applied to a 240V/3A 5-cells Cascaded Full-Bridge Multilevel Converter. The response of the system to load transients and cell voltage disturbances demonstrates the robustness of the proposed decentralized control method. Thanks to the use of modular controllers, the number of levels of the converter can be extended to the order N without adding complexity to its control.

Decentralized Control of DC–DC Converters for Redundant Onboard Power Supply Based on Artificial Swarm Intelligence Approaches

“…A decentralized controller to balance the capacitor voltages in a flying-capacitor converter architecture is investigated in [12]. It is stated that this method can be scaled up to any number of cells.…”

Decentralized Control for the Cell Power Balancing of a Cascaded Full-Bridge Multilevel Converter

“…Depending on the connection of these cells (series or parallel), the current or voltage is divided. Within the family of multicellular converters, one can mention the following, among others: the Flying Capacitor Multilevel Converter (FCMC) [3][4][5][6][7], CFBMC [8][9][10][11][12][13] and the Multiphase Buck Converter [14][15][16]. They distribute, respectively, the input voltage, the output voltage and the output current.…”

“…In contrast, MCCs bring some complex subjects that need to be analyzed, such as the control of the cells that guarantees an equilibrium of the power delivered by each cell or the secure operation of the switches, avoiding overvoltage or overcurrent. For instance, in FCMC the capacitor voltages are the variables to balance [3,4,21], also improving the output voltage ripple. In the Multiphase Buck Converter, the sharing must be ensured in the output current of each leg [16].…”

“…The modularity of MCCs also offers the opportunity to propose fault-tolerant solutions. Here, one challenge is to insert or remove cells during operation [3,15,21,23], which additionally provides the possibility to increase the power of the system without interruption. There exist many controllers that satisfy all these specifications.…”

Real-Time Adaptive Selective Harmonic Elimination for Cascaded Full-Bridge Multilevel Inverter

“…They distribute the power in sub-cells and reduce the size of the passive elements of the converter. This characteristic is due to the apparent frequency observed at the output voltage that is proportional to the switching frequency of the semiconductor devices multiplied by the number of cells [1][2][3][4][5][6][7]. For DC/AC conversion, the cascaded topology is an alternative when multiple independent voltage sources are available [8][9][10][11].…”