Charging method for sub-module based hybrid converter

A charging method for a hybrid converter based on half bridge sub-modules and full bridge sub-modules, wherein the method comprises the steps:

• step (1):
• performing, by a converter, a charging process;
• step (2):
• powering a self-powered supply of the full bridge sub-modules and half-blocking the full bridge sub-modules, half-blocking the full bridge sub-modules comprising the steps of:
• turning on a first turn-off device of the full bridge sub-modules, turning off a second, third and fourth turn-off devices or turning off the first, second and third turn-off devices, and turning on the fourth turn-off device, then
• based on a sequence from high to low of a voltage of each of the full bridge sub-modules, starting with a full bridge sub-module having a greatest voltage of the full bridge sub-modules, and continuing with other full bridge sub-modules, after a powering succeeds, the full bridge sub-modules being half-blocked one by one or multiple at a time, and during the process, other full bridge sub-modules that are not bypassed being blocked, and all half bridge sub-modules being maintained in a blocked state;
• and
• step (3):
• performing, by the converter, a full-controlled charging process after all the full bridge sub-modules are half-blocked.