This paper presents a new method to measure the voltage across the submodule (SM) capacitors in a modular multilevel converter (MMC). The proposed technique requires only one voltage sensor per arm. This reduces the number of sensors required compared to conventional sensor-based methods. Therefore, the cost and complexity of the system are reduced, which in turn improves the converter’s overall reliability. The proposed method employs an exponentially weighted recursive least square (ERLS) algorithm to estimate the SM capacitor voltages through the measured total arm voltage and the switching patterns of each SM. There is thus no need for extra sensors to measure these control signals as they are directly provided from the controller. The robustness of the proposed method is confirmed via introducing deviations for the capacitance values, dynamic load changes, DC voltage change and start-up transient condition. Simulation and experimentally validated results based on a single-phase MMC show the effectiveness of the proposed method in both, steady-state and dynamic operations.
|Number of pages||12|
|Journal||IEEE Journal of Emerging and Selected Topics in Power Electronics|
|Early online date||24 Jan 2018|
|Publication status||Published - 1 Dec 2018|
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Funding: Libyan Ministry of Higher Education and Scientific
Research and Scholar Program of Zawia and Sabratha
- Modular multilevel converter (MMC)
- reduced number of sensors
- pulse width modulation (PWM)
- recursive least square (RLS)
- voltage balancing control algorithm