Flexible supercharging system of diesel engine and control method of flexible supercharging system

The invention aims at providing a flexible supercharging system of a diesel engine and a control method of the flexible supercharging system. The flexible supercharging system comprises the diesel engine, an exhaust gas turbine and a gas compressor, wherein the exhaust gas turbine is connected with the diesel engine through an exhaust pipe; the gas compressor is connected with the diesel engine through an air inlet pipe; the exhaust gas turbine is connected with the gas compressor through a hydraulic coupler; the air inlet pipe is provided with an intercooler; the exhaust pipe is branched to form an exhaust gas control pipe communicated with the atmosphere; the exhaust gas control pipe is provided with an exhaust gas control valve; the air inlet pipe located between the intercooler and the gas compressor is branched to form an air control pipe communicated with the atmosphere; the air control pipe is provided with an air control valve; an outlet of the gas compressor is provided with a pressure sensor; and a shaft where the exhaust gas turbine is connected with the hydraulic coupler is provided with a rotating speed sensor. By using the flexible supercharging system, the aims of outputting a large torque under a low working condition and protecting the rotating speed at a high working condition can be achieved, the efficiency of a complete machine can be increased, and the consumption of fuel oil under a full-working condition can be reduced.