Mission Profile Based Adaptive Carrier Frequency Control for Modular Multilevel Converters for Medium Voltage Applications

In order to increase the efficiency and to improve the reliability of modular multilevel converters in medium voltage applications, this paper proposes an adaptive control method to choose an optimal carrier frequency dynamically according to power loading conditions of the modular multilevel converter. By evaluating the impact of the carrier frequency on the output current harmonic performance and the capacitor voltage ripple analytically, the proposed adaptive control can reduce the power loss and the thermal stress on the power semiconductors. Meanwhile, the electrical operation requirements can still be fulfilled. One-year mission profile is utilized to assess the energy efficiency and the reliability performance between the proposed and the traditional control scheme. Moreover, theoretical analysis and simulation results are presented to demonstrate the effectiveness of the proposed control.