Battery Management for the Electric Hydraulic Pump System of a Lifting Trolley

This study proposed a battery management approach for the electric hydraulic pump system of a lifting trolley.The pump system was powered by two 12-V lead-acid batteries in series.Because direct measurement of the actual battery state of charge is unlikely,it has mostly been determined through estimation based on the measured open-circuit voltage.A discharge current will result in a voltage drop and hence a lower voltage during discharge;however,the battery voltage will return to the original open-circuit voltage once the discharge stops.The operating current of the electric hydraulic pump system employed in this study was associated with three factors:the lifting height,lifting load,and battery state of charge.The operating current remained constant during the first half of the lifting phase and increased gradually with the lifting height in the second half.The operating current peaked when the lifting height reached the maximum.The power management approach for the electric hydraulic pump system featured the following basic functions:overcharge protection,overdischarge protection,short-circuit protection,overload protection,and an operating timer established in accordance with the system’s operating current variation.According to the manufacturer-defined maximum lifting load and lifting height of the lifting trolley,this study conducted experiments to obtain the maximum required operating time.An operating time greater than the maximum required operating time indicates the occurrence of an unexpected event,discharge should be stopped until the fault is resolved.

Modeling and experimental tests of hydraulic electric inerter

As a newly proposed two-terminal mechanical element, there are many realizations of inerter such as ball-screw, rack and pinion,hydraulic, fluid and mechatronic inerter. This paper concerns about a novel mechatronic inerter, which is consisted of a hydraulic piston inerter and linear motor, called hydraulic electric inerter(HEI). Firstly, the structural components and the working principles of two types HEI device are introduced, and the dynamic model of the HEI is established. Then, three classifications of mechatronic inerter, namely, the single motor type, the linear inerter-motor type and the rotary inerter-motor type are presented,and in the meanwhile, some comparisons among the three types mechatronic inerter are analyzed. Subsequently, a methodology of designing and experimental tests of the HEI device is proposed by considering the rated working conditions of the linear motor and the electric elements. At last, the HEI device is conducted, and the force tests of the non-loaded HEI and loaded HEI are tested in order to validate their properties. The experimental results are analyzed, and the discrepancies are also further discussed.

Review on signal-by-wire and power-by-wire actuation for more electric aircraft

The huge and rapid progress in electric drives offers new opportunities to improve the performances of aircraft at all levels：fuel burn,environmental footprint,safety,integration and production,serviceability,and maintainability.Actuation for safety-critical applications like flight-controls,landing gears,and even engines is one of the major consumers of non-propulsive power.Conventional actuation with centralized hydraulic power generation and distribution and control of power by throttling has been well established for decades,but offers a limited potential of evolution.In this context,electric drives become more and more attractive to remove the natural drawbacks of conventional actuation and to offer new opportunities for improving performance.This paper takes the stock,at both the signal and power levels,of the evolution of actuation for safety-critical applications in aerospace.It focuses on the recent advances and the remaining challenges to be taken toward full electrical actuation for commercial and military aircraft,helicopters,and launchers.It logically starts by emphasizing the specificity of safety-critical actuation for aerospace.The following section addresses in details the evolution of aerospace actuation from mechanically-signaled and hydraulically-supplied to all electric,with special emphasis on research and development programs and on solutions entered into service.Finally,the last section reviews the challenges to be taken to generalize the use of all-electric actuators for future aircraft programs.