Objectives  In light of the requirement for internal pressure tracking control of a large vessel, in order to meet the demand of rapidly high flow of pressurization section, and improve the tracking performance of pressurization section and depressurization section of pressure vessel,

  Methods  the internal pressure control system for a new type of 75 m³ pressure vessel is developed, in which a high pressure air water tank was used as an energy accumulator. The change of the internal pressure was realized by controlling the liquid volume that comes from the energy accumulator into the large vessel, to achieve accurate tracking of pressurization section. In order to improve the tracking accuracy of the depressurization section, the flow control valve and the high-speed solenoid switch valve were installed on the outlet pipe of the pressure vessel. PID control algorithm with dead zone was used to compensate for phase lag.

  Results  The test results show that the dynamic tracking accuracy of the system can be kept within 0.4 MPa, and the static pressure maintaining accuracy can be kept within 0.1 MPa, which validated the good pressure tracking performance and static pressure accuracy.

  Conclusions  This control method can effectively solve the problem that the instantaneous large flow and pressure control precision of the false sea back pressure can not be ensured simultaneously when the land test simulates the application scenario of underwater vehicle with large inertia and variable depth.