Design and Verification of a New Hydraulic Soft Switching Transformer Based on an Auxiliary Fluid Delivery System

The hydraulic switching transformer is a pressure conversion device similar to a dc/dc converter in electronic switching mode. However, the energy efficiency of the system is reduced by the throttling loss generated by switching on/off valves. Therefore, this article proposes a new hydraulic soft-switching scheme to reduce the switching throttling loss and improve the energy efficiency of the hydraulic switching transformer system, which is similar to the zero-current conversion technology in the electronic switching mode. By setting up a temporary flow path to the tank at the valve port, introducing an auxiliary control system in the system to control the opening of the temporary flow path when the switching valve is switched, reducing the fluid passing through the valve port when the switching valve is switched, and decreasing the pressure difference between the two ends, thus reducing the throttling loss of the switching valve and improving the energy efficiency of the system. Simulation and experimental results show that, after the addition of the auxiliary fluid delivery system, the switching throttling loss of the on/off valve is greatly reduced, and the energy efficiency of the system is improved; in the experiments, the energy efficiency of the system can be improved by up to 11%.