Abstract:Variable frequency hydraulic speed control system has high values in low energy consumption, broad speed control range and high control accuracy, which receives more and more attention in industrial circle. But because of it also has more links and control dead zone, quick adjusting characteristic and operation efficiency are decreased, so its applied range is limited. On basis of comprehensively analyzing three kinds of existing typical variable frequency hydraulic speed control system, a scheme of variable frequency hydraulic speed control system with pump and valve parallel connection was put forward. The simulation result shows that the scheme can have both high energy efficiency of pump control and quick adjusting speed characteristic of valve control system, which has certain value in theoretical study and practical application.