Diesel engine sequential supercharging structure and control method thereof

The invention aims to provide a diesel engine sequential supercharging structure and a control method thereof. The diesel engine sequential supercharging structure comprises a diesel engine, air inlet pipes, exhaust pipes, turbochargers, an air vent valve, an air valve and a gas valve, the turbochargers comprises a basic turbocharger and a controlled turbocharger; the air inlet pipes comprise an A column of air inlet pipes, a B column of air inlet pipes, a compressor connected with the basic turbocharger and a compressor connected with the controlled turbocharger; the exhaust pipes comprise an A column of exhaust pipes, a B column of exhaust pipes, a turbine connected with the basic turbocharger and a turbine connected with the controlled turbocharger; the A column of exhaust pipes and the B column of exhaust pipes are communicated through exhaust connecting pipes; the gas valve is installed on the B column of exhaust pipes; the air valve and the air vent valve are installed on the B column of air inlet pipes; and the air vent valve is located between the air valve and the compressor of the controlled turbocharger. According to the invention, a phenomenon of zero flow with non-zero rotating speed of the compressor can be avoided; surge phenomenon of the superchargers can be eliminated; and usage conditions of the supercharger are improved effectively.