Downhole power generation system and method

A downhole power generation method, comprising:

• driving one or more turbines, by flow of a downhole fluid, to rotate;
• converting one or more rotational energies from the one or more turbines, by one or more generators, to one or more electrical energies respectively;
• converting one or more alternating current voltages from the one or more generators, by one or more AC-DC rectifiers, to one or more direct current voltages respectively;
• converting the one or more direct current voltages, by controlling a first DC-DC converter, to a first power and providing the first power to a load when the load is in a working mode;
• and
• converting the one or more direct current voltages, by controlling a second DC-DC converter, to a second power and providing the second power to the load when the load is in a non-working mode, wherein the second power is less than the first power.