Research on the Pressure Impact Mechanism and Suppression of Digital Hydraulic Transformer

With the development of digital hydraulic technology, digital hydraulic transformer appears as a new type of hydraulic component, which is an important attempt to make hydraulic technology intelligent and energy-saving. The digital variable output of the digital hydraulic transformer is achieved by switching the control valve group. It has the advantages of small throttling loss, fast response speed and strong anti-interference ability. However, due to the step fitting method used by the discrete variable control method to achieve displacement adjustment, there is flow discontinuity during the step change process, which resulting in pressure shock and vibration, and it affecting the stability and control performance of hydraulic system. In order to solve this problem, in this paper, the impact mechanism of digital hydraulic transformer is studied, the mathematical model of discrete variable control system for digital hydraulic transformer is established. The influence of transient pressure and pressure transformation ratio of digital hydraulic transformers is investigated by changing parameters such as variable switching frequency and variable step length. The formation mechanism of pressure impact in digital hydraulic transformer is revealed. The working performance of digital hydraulic transformer is determined to improve its characteristics. The suppression effect of parameters such as accumulator volume and charging pressure on the variable pressure impact of digital hydraulic transformer is studied. The matching mechanism between digital hydraulic transformer variable and accumulator is clarified. Under the selected operating conditions, the maximum reduction in pressure impact is 42.4% through optimization of the control method. The pressure impact is reduced by 18.0% at the control valve response frequency of 50Hz compared to that of 5Hz. The parameters of the accumulator group are selected reasonably based on the system. Compared to not installing the accumulator, the average pressure shock is reduced by 30.8%. The research results of this project can provide a theoretical basis for the development of digital hydraulic transformer.