Reconfigurable mmc sub-module unit and control unit thereof

A reconfigurable MMC sub-module unit, characterized in that:

• the reconfigurable MMC sub-module unit comprises an MMC sub-module unit and a reconfigurable mechanism, the reconfigurable mechanism comprises change-over switches, the reconfigurable mechanism is embedded to the MMC sub-module unit through electric connection lines or copper busbar, and a topology of the MMC sub-module unit is converted by switching on or off the change-over switches in the reconfigurable mechanism;
• in the case of a full-bridge sub-module with a bypass switch, the reconfigurable mechanism in the reconfigurable MMC sub-module unit is formed by three change-over switches;
• the full-bridge sub-module comprises four power semiconductor elements, a bypass switch, a voltage equalizing resistor and a capacitor, the power semiconductor elements each comprises an anti-parallel diode, an emitter of a first power semiconductor element and a collector of a second power semiconductor element are connected to a upper end of the bypass switch, an emitter of a third power semiconductor element and a collector of a fourth power semiconductor element are connected to a lower end of the bypass switch, a collector of the first power semiconductor element and a collector of the third power semiconductor element are connected to a positive end of the capacitor, a emitter of the second power semiconductor element and a emitter of the fourth power semiconductor element are connected to a negative end of the capacitor, a upper end of the voltage equalizing resistor is connected to the positive end of the capacitor and the lower end of the voltage equalizing resistor is connected to the negative end of the capacitor;
• the reconfigurable mechanism is embedded to the full-bridge sub-module, one end of a first change-over switch is connected to the negative end of the capacitor of the full-bridge sub-module, the other end of the first change-over switch is connected to the lower end of the bypass switch and one end of a second change-over switch;
• an other end of the second change-over switch is connected to a middle point of a bridge arm of the third power semiconductor element and the fourth power semiconductor element of the full-bridge sub-module, and the one end of the second change-over switch is connected to the lower end of the bypass switch and one end of the first power semiconductor element;
• one end of the third change-over switch is connected to the collector of the first power semiconductor element, the positive end of the capacitor and a negative end of the voltage equalizing resistor of the full-bridge sub-module, and the other end of the third change-over switch is connected to the collector of the third power semiconductor element of the full-bridge sub-module.