Wei Zhao

• Zhao, Wei; Ebbesen, Morten Kjeld; Hansen, Michael Rygaard & Andersen, Torben Ole (2024). Enabling Passive Load-Holding Function and System Pressures Control in a One-Motor-One-Pump Motor-Controlled Hydraulic Cylinder: Simulation Study. Energies. ISSN 1996-1073. 17(11). doi: 10.3390/en17112484. Vis sammendrag

  This paper is concerned with a hydraulic cylinder directly controlled by a variable speed motor-driven fixed-displacement pump. The considered configuration is referred to as a one-motor-one-pump (1M1P) motor-controlled hydraulic cylinder (MCC). A 1M1P MCC with a hydraulically driven passive load-holding function enabled by controlled system pressures is proposed. The proposed load-holding functionality works if there is a standstill command, a loss of power supply, or a hose rupture. Additionally, this paper conducts a comprehensive analysis of the proposed system’s operation and load-holding function across four quadrants. The simulation results demonstrate four-quadrant operation and good load-holding performance under the aforementioned scenarios. In conclusion, the proposed 1M1P MCC can be successfully used on practical applications characterized by overrunning loads and four quadrant operation.

• Zhao, Wei & Bhola, Mohit (2023). Comparing Compact and Remote Deployments of a Speed-Controlled Cylinder Drive Unit on an Offshore Knuckle Boom Crane, The Eighteenth Scandinavian International Conference on Fluid Power, SICFP’23. Tampere University of Technology. ISSN 978-952-03-2911-2.
• Zhao, Wei; Ebbesen, Morten Kjeld & Andersen, Torben Ole (2023). Comparative Analysis of Energy Efficiency: Knuckle Boom Crane Driven by Motor-Controlled Cylinders Versus Valve-Controlled Cylinders. I Zhou, Jing (Red.), 2023 11th International Conference on Control, Mechatronics and Automation (ICCMA). IEEE conference proceedings. ISSN 979-8-3503-1568-4. s. 201–207. doi: 10.1109/ICCMA59762.2023.10374706. Vis sammendrag

  When a hydraulic differential cylinder is directly connected to fixed-displacement hydraulic pumps driven by independent electric servo motors, the cylinder motion is manipulated by controlling the velocities of the electric servo motors. This configuration is called a motor-controlled hydraulic cylinder (MCC) in this study. In contrast to valve-controlled hydraulic cylinders (VCCs), MCCs theoretically offer enhanced energy efficiency due to the absence of valve throttling. However, the energy efficiency performance of MCCs in multi-cylinder applications still needs to be explored in the existing research. This paper seeks to bridge this gap by comparing a knuckle boom crane driven by proposed two-motor-two-pump MCCs with a passive load-holding function and VCCs on the crane in energy efficiency. To achieve this, non-linear dynamic models of a knuckle boom crane driven by two-motor-two-pump MCCs and the original VCCs on the crane are created in MATLAB/Simulink. A realistic operation path for lifting a payload is designed, and three load cases are tested. Simulation results demonstrate better performance of the proposed MCCs in energy efficiency than VCCs. In conclusion, this study showcases the viability of the proposed MCCs for practical applications, highlighting their enhanced energy efficiency compared to traditional VCCs.

• Zhao, Wei; Bhola, Mohit; Ebbesen, Morten Kjeld & Andersen, Torben Ole (2023). A Motor-Controlled Hydraulic Cylinder With Cylinder Pressure Control and Load-Holding Function - An Experimental Study. I Barth, Eric J. (Red.), Fluid Power Systems Technology. The American Society of Mechanical Engineers (ASME). ISSN 9780791887431. doi: 10.1115/FPMC2023-111712.
• Zhao, Wei; Bhola, Mohit; Ebbesen, Morten Kjeld & Andersen, Torben Ole (2023). A Novel Control Design for Realizing Passive Load-Holding Function on a Two-Motor-Two-Pump Motor-Controlled Hydraulic Cylinder. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. 44(3), s. 125–139. doi: 10.4173/mic.2023.3.3. Fulltekst i vitenarkiv Vis sammendrag

  When a hydraulic cylinder connects two chambers directly to one or two hydraulic pumps driven by electric servo motors without any control valve in between, it can be called a motor-controlled hydraulic cylinder (MCC). Unlike valve-controlled cylinders, MCCs have no valve throttling, which significantly increases the energy efficiency. Among different MCC topologies, the two-motor-two-pump (2M2P) MCC has several advantages, such as cylinder pressure control and no mode switch oscillations. However, due to state coupling when controlling both piston position and minimum cylinder chamber pressure, the 2M2P MCC is a multi-input-multi-output (MIMO) system that usually requires advanced MIMO controller analysis and design. This paper presents a control algorithm for a 2M2P MCC with the minimum cylinder pressure control and passive load-holding function. This control algorithm is tested on a single-boom crane characterized by overrunning loads. It is designed based on the analysis of the system characteristics, requiring no MIMO controller analysis and design. A non-linear model of a single-boom crane driven by the proposed 2M2P MCC is created in MATLAB/Simulink and experimentally validated. Feedback controllers are designed and verified via simulations to realize position control, minimum cylinder pressure control, and load-holding under standstill command. For a given load and speed profile, the hydraulic system efficiency during pumping and motoring mode is 55-60% and 20-25%, respectively. The system's overall efficiency can be enhanced with electrical regenerative drives, which feeds the generated power from potential energy to the grid or battery and reused in the next working cycle. The experimental results presented in this paper verifies the efficacy of the proposed control algorithm and demonstrates its superior performance in achieving the desired system response under various operating conditions.

Se alle arbeider i Cristin

• Zhao, Wei; Ebbesen, Morten Kjeld & Andersen, Torben Ole (2022). Identifying The Future Research Trend for Using Speed-Controlled Hydraulic Cylinders in Offshore Applications through Literature Survey.

Se alle arbeider i Cristin