Tsinghua University

Li-Chun Lin

Tsai-Fu Wu

Chih-Hao Chang

Yen-Hsiang Huang

Xin-yu Yu

Tin-Hao Chang

A power converting method for high frequency inverter and low frequency inverter connecting in parallel, which is for converting a direct current power into an alternating current power, includes the following steps. A low frequency inverting module which electrically connected to the direct current power is provided. A high frequency inverting module which is electrically connected to the low frequency inverting module in parallel is provided. A high frequency switching duty ratio of the high frequency inverting module is adjusted to output a second current according to a first current produced by the low frequency inverting module. The second current is for compensating ripples of the first current.

Power converting device containing high frequency inverter and low frequency inverter connecting in parallel and the method thereof

Current of a three-phase multilevel modular converter (MMC) is controlled. The control is a division-summation (D-&#x3a3;) method yet uses integration to replace the two steps of division and summation. Common D-&#x3a3; characteristic equations are used for all areas. Inductance changes are considered in the characteristic equations. Current source is used to control converter. Therefore, the current of the converter can be traced to sinusoidal reference current even when the inductance changes become big. The modulation method and the capacitor-voltage balancing method are submodule unified pulse width modulation (SUPWM) and sorted voltage-balancing method, respectively. The current control directly obtains a law of the current change on each conducting module of an arm. It does not need complex sector judgments and table look-ups. Thus, the amount of computation and memory for a processor can be relatively reduced.

Method of current control of three-phase modular multilevel converter with inductance changes allowed

A method is provided for current compensation. The method is based on division-sigma (D-&#x3a3;) control for a DC/DC converter. Inductance changes are allowed with D-&#x3a3; digital control achieved. Loop gain can be quickly adjusted. The disadvantage of average current-mode control (ACMC) is solved, where the disadvantage is a reduction of the response speed caused by the filter within the current loop. The present invention uses midpoint current sampling to ensure taking an average inductor current value in each switching cycle. By doing so, a lack of fidelity of peak current-mode control (PCMC) is solved, where the lack of fidelity is due to the amount of error value between the peak value and the average value. Besides, the present invention uses a table of the inductance following current changes to achieve compensation of duty cycle ratio, where the table is built in a single chip.

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Taipei, Taiwan

Li-Chun Lin