CONTROL OF MULTI-PRESSURE HYDRAULIC SUPPLY LINE USING DIGITAL HYDRAULIC POWER MANAGEMENT SYSTEM

Multi-pressure hydraulic supply line, i.e., hydraulic bus enables efficient use of energy in multi-actuator systems of off-road machinery. Number of constant pressure supply lines, each providing unique pressure level, are routed to every actuator in the machine. Significant amount of the power losses related to conventional load sensing systems are avoided by enabling energy recuperation and reduction of total throttling loss. Pressure control of such multi-pressure hydraulic supply line can be realized using hydraulic accumulators, which are charged using conventional pump and logic valves. However, more advanced features are available if Digital Hydraulic Power Management System DHPMS is utilized. The DHPMS is in essence, a digital pump/motor/transformer with multiple outlets. Controller design of DHPMS in hydraulic bus application is described in the paper and simulation results show the system's ability to simultaneously control the supply line pressures and input power of the DHPMS. By controlling the input power, the prime mover such as Diesel engine can be driven in optimal operation point or it can be even downsized. If electric motor is used as prime mover, smaller and therefore less expensive motor can be used.