Dynamic Simulation of Variable-Speed Valve-Controlled-Motor Drive System with a Power-Assisted Device

Abstract

The variable-speed electrohydraulic drive has been applied in hydraulic machines having power matching means. However, further development has been restricted by its slow response and poor low-speed behavior. Owing to these disadvantages, a novel drive principle comprising a variable-speed valve-controlled-motor drive with an accumulator-based power assisted unit (PAU) is proposed. The PAU is an energy assisting and recycling device, which can release or absorb hydraulic energy according to the system's requirements. With the aid of PAU, the proposed drive is expected to improve response and control precision compared with the variable-speed drive. The proposed drive principle system is a multi-input-multi-output (MIMO) complicated nonlinear system with time-varying, which increases the control difficulty. A mathematical model of the proposed drive was first derived then a hybrid control strategy was presented. The dynamic simulations of three traditional drives and the novel one were performed using AMESim-Simulink co-simulation models. The four drives have been tested using three common variable-load disturbances. Comparisons of simulation results show that the proposed drive principle system demonstrates a good dynamic performance, which can not only achieve the expected energy saving target, but also significantly improve the response and control precision over the existing variable-speed drive system.

Dynamic Behaviour of Different Hydraulic Drive Concepts – Comparison and Limits

“…6 shows responses acquired from simulation (green) and measurement (red), whereas the pressure set-point is shown in blue. Detailed information related to the simulation is available in the literature [7,13,[15][16][17][18][19][20]. A similar conclusion about the dynamics can be made in the case of the use of a variable axial piston pump set to maximal displacement (VC-APP-drive concept).…”

Mathematical simulation and measurement of expansion of hydraulic hose with oil

“…This oil bulk modulus K 2 was evaluated as constant in the range of the measured pressure gradients ∆p. The effective oil bulk modulus K E2 is defined in this case by the formula [9,15,30,31]:…”

Improving the Efficiency of Auxiliary Cooling Water Pump and Auxiliary Sea Water Booster Pump in Thermal Plant using Variable Frequency Drive

“…Variable frequency drive is one of the many well-known energy efficient drives [7]. Frequency Drives are used for variable speed applications reduce the energy consumption of motors and increase the energy efficiency of plants [8]. Many fixed-speed motor load applications that are supplied direct from AC line power can save energy when they are operated at variable-speed, by means of VFD.…”

“…[7,8]. The VFD is a system for controlling the rotational speed or torque of an alternating current (AC) electric motor by controlling the frequency of the electric power supplied to the motor.…”

“…When a centrifugal pump is used with an adjustable speed AC drive, the energy costs can reduce by (10 to 60) % of full energy if the pump is designed to operate between (40 to 80) % of full speed [7,8].…”