Energy Saving in Electro-Hydraulic System Using a MIMO Fuzzy Controller

Abstract

Energy saving in the electro-hydraulic system (EHS) that currently exists in most inverter used to adjust speed of the asynchronous motor (ASM) which drive a fixed displacement pump. The most controller commonly used control system such as PID and multi-input single-output (MISO) fuzzy controller. In this paper, a multi-input multi-output (MIMO) fuzzy controller is used to improve the energy saving performance of the EHS. The proposed controller is designed to control the pressure of the EHS to suit the actual needs of the load. The two inputs of controller received signals from the error and change in error of the load pressure of the EHS. For the two outputs of the controller, one output is used to control the inverter to adjust speed of an ASM which drive hydraulic pump, and one output that is used for control proportional pressure relief valve. The proposed controller was implemented to pressure control of compression machine. The experimental result showed that using a proposed controller can reduce power consumption was higher than compared with PID and MISO fuzzy controllers. Particularly, a MIMO fuzzy controller can reduce power consumption by up to 70.22% when compared to the conventional system.

A Hybrid of Force and Position Control with Energy Saving in the Electro-Hydraulic System

“…Since the basic equation that's hydraulic power is equal to pressure multiplied by the flow rate (P H = p⋅Q), whose value is equal to the input power of the EM (P E = √3⋅E⋅I⋅Cosθ). Thus, when the flow rate in a hydraulic system decreased as mention in the above, resulted the power of the EM is reduced by as well [3]. This can save considerable energy in a hydraulic system.…”

“…The all transfer function of the position and force control can be represented respectively as: [6] From the relevant of the variables in equations, when force to the desired value, then it is unnecessary to supply a flow of oil to the system, in this condition need only maintain a constant pressure. Pump is used to reduce the flow of oil to replace the PDCV due to the loss reduction [3]. When the flow rate of pump (Q P ) depends on the speed, which can be computed as: where V is displacement, η v is volumetric efficiency, and n is speed is used to drive the pump.…”

“…The EM is coupled to a fixed displacement pump and the relevant speed variation allows to obtain a variable flow rate according to actual needs of circuit, thus reducing the overall power consumption [2]. In addition, the system included a PPRV also, because the interaction between the electric motor speed control and pressure control of a PPRV to control the loading pressure to reduce losses as well [2], [3].…”

Review of Hydro-Pneumatic Accumulator Models for the Study of the Energy Efficiency of Hydraulic Systems

“…In hydraulic systems, various methods to improve energy efficiency are used, consisting of effective control, reduction in energy losses, energy regeneration, and the hybridisation of the drive [10]. Energy-saving hydraulic systems are obtained thanks to the new direct driven hydraulic (DDH), controlled electric motors, and electronic control systems [11][12][13][14][15][16]. With the wide use of hydraulically driven machinery, especially highpowered hydraulic mobile machinery, there is great interest in research on energy-saving measures and strategies due to energy costs, environmental regulations, etc.…”

Design, modeling, and pressure control of a 300-kW-class hydraulic pump/motor loading system with energy regeneration

“…So the relief flow rate cannot be effectively governed for energy recovery. 14,15 A closed-loop controller is beneficial for relief flow rate regulation. However, it requires a flow meter to detect the relief flow rate, which makes the system structure more complicated.…”