2results about How to "Reduce capacitor voltage fluctuations" patented technology

The invention provides a capacitor voltage fluctuation suppression method for a modular multi-level matrix converter, and the method comprises the steps: obtaining the capacitor voltage and current of each bridge arm of an M3C under a double alpha beta 0 coordinate system, calculating the three-phase reference voltage of the input side and the output side of the M3C according to the type of an AC system connected with the two sides of the M3C, and carrying out the calculation of the three-phase reference voltage of the input side and the output side of the M3C; the basic output reference voltage of the bridge arm is determined; calculating an injectable common-mode voltage range, and determining a reference value of the injected common-mode voltage; calculating a ring current reference value required for balancing the capacitor voltage, and obtaining a ring current voltage reference value through closed-loop control; the loop current reference voltage of each bridge arm is calculated through inverse double alpha beta 0 conversion, the total bridge arm output reference voltage is obtained by combining the bridge arm basic output reference voltage and the common-mode voltage reference value, the control of the output voltage of each bridge arm is realized through modulation, and a driving signal of a switching device is generated. Compared with a conventional high-frequency sine common-mode injection method, the method can effectively reduce the capacitor voltage fluctuation, and reduces the current amplitude of a bridge arm.

This invention belongs to the field of power electronic converter technology, specifically disclosing a direct optimization model predictive control method and system for an MMC-STATCOM system. The method includes: calculating the differential-mode voltage and common-mode voltage between the upper and lower arms of each phase; injecting third harmonic voltage into the upper and lower arms of each phase to obtain the upper and lower arm voltages of the newly added third voltage component for each phase; based on the obtained upper and lower arm voltages of the newly added third voltage component, determining the number of sub-modules to be engaged in each phase's upper and lower arms using a nearest-level approximation modulation strategy; sorting the sub-modules according to the capacitor voltage of each sub-module in the arm; and determining the engaged sub-modules for each arm according to the current direction. This invention, while maintaining the discrete control structure, achieves direct injection of third harmonic voltage under the MPC framework, exhibiting higher real-time performance and scalability.