Abstract
Earlier research demonstrated that a pump-controlled hydraulic system combines the best properties of traditional hydraulics and electric intelligence. Thus, the new system has been proposed as a replacement for conventional valve-controlled systems, to improve the energy efficiency in non-road mobile machinery in particular. One of the pump-controlled systems can be realized via direct control of hydraulic pump/motor by varying speed of prime mover. Electric motor (EM) as a prime mover attract with higher efficiency (more than 90%) and a wide range of speed regulation. These advantages allow to improve the system efficiency and decrease the energy consumption in electric and hybrid non-road mobile machinery. Further EM's efficiency improvement can be achieved by using vector control systems, which provide rotor magnetic flux control proportionally to the shaft's speed. Considering all vector control’s benefits (high accuracy of speed control, smooth~start and smooth rotation of the motor in the entire frequency range, quick response to load changes, increased control range and accuracy of regulation), the electro-hydraulic systems and influence of electric part on hydraulic one is not investigated widely. Therefore, in this paper Field Oriented Control (FOC) is analyzed as One of the most perspective vector control systems for electro-hydraulic actuator application with a Permanent Magnet Synchronous Machine (PMSM) as a prime mover. In~this study, Direct-driven hydraulics (DDH) was considered as a study case. A detailed model of the PMSM control system with DDH was built in MATLAB/Simulink. The behavior of the DDH system was investigated by transient processes analysis of EM, pump, and cylinder in the normal and failure modes. The system demonstrates a difference between reference and simulated speed about 0.33% and 11.75% of average torque fluctuations. The behavior of the system in failure mode demonstrated multiple excesses of rated parameters.
Highlights
Valve – controlled systems are used in various areas [1]
Such types of conventional hydraulic systems are characterized by low efficiency, due to throttle losses, and high energy consumption caused by continuous work of a prime mover [2]
Failure mode demonstrated multiple exceeding the maximum rated as such values as current, electromagnetic torque, pressure, and flow
Summary
Valve – controlled systems are used in various areas (stationary and mobile machinery applications) [1]. Valve – controlled systems utilize a constant speed of prime mover and control a flow of hydraulic system by the directional valves. According to [5] a combination of a pump-controlled system with an electric prime mover increases performance and efficiency. One of the main control methods of PMSM which is called Field oriented control (FOC) is used in this research, because of the smaller transient process time in comparison with other vector control systems. This control method is vector-based, because of the geometrical expression of main control variables, which are represented as vectors into a mathematical space. The behavior will be investigated under normal and failure mode
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