Power control apparatus for sub-module of mmc converter

A power control apparatus for sub-modules in a Modular Multilevel Converter (MMC), comprising:

• at least one first resistor (210) connected between P and N buses of the MMC;
• a second resistor (220) connected in series with the first resistor (210);
• at least one third resistor (230) connected in parallel with the first resistor (210) and the second resistor (220), which are connected in series;
• a Zener diode (240) connected in series with the third resistor (230);
• a switch (250) connected between a junction of the first resistor (210) and the second resistor (220) and a junction of the third resistor (230) and the Zener diode (240);
• and
• a DC/DC converter (260) connected between both ends of the Zener diode (240) and configured to convert voltage across both ends of the Zener diode (240) and transmit a resulting voltage to sub-modules,
• wherein a magnitude of current flowing through the Zener diode (240) is controlled depending on ON/OFF switching of the switch (250).