Switchmode Hydraulic Power Supply Theory

2005 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Minxiu Qiu
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Power Supply ◽  
Power Loss ◽  
High Speed ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
Supply Pressure

Switchmode hydraulic power supply is a new kind of energy-saving pressure converting system, which is originally proposed by the authors. It is mainly applied in multiple-actuator hydraulic systems, and installed between hydraulic pump and actuators (one switchmode hydraulic power supply for one actuator). It can provide pressure or flow rate that is adapted to the consumption of each actuator in the system by boosting or bucking the pressure, with low power loss, and conveniently, through high-speed switch valves, just like a hydraulic pressure transformer. There are two basic types of switchmode hydraulic power supply: pressure boost and pressure buck. Their structures and working principles are introduced. The dynamic characteristics of two typical types of switchmode hydraulic power supply, the pressure boost type and the pressure buck type, were analyzed through simulations and experiments. The performances were evaluated, and improvements on the efficiency of switchmode hydraulic power supply were proposed.

Research on the Principle and Characteristic of Compound Switch-Mode Hydraulic Power Supply

2006 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Ying Chen
Keyword(s):  
Flow Rate ◽  
Power Supply ◽  
High Speed ◽  
Low Pressure ◽  
Power Supplies ◽  
Duty Ratio ◽  
Hydraulic Pressure ◽  
Hydraulic Power ◽  
Load Pressure ◽  
Switch Mode

Switch-mode hydraulic power supply is a hydraulic pressure converting unit made of some distributed hydraulic components, which can boost or buck hydraulic pressure steplessly, with low power loss (about 20%) and continuous flow-rate[1][2]. There are two types of switch-mode hydraulic power supply. One is pressure boost type and the other is pressure buck type. For the pressure boost power supply, changing of the pressure is realized through instantaneous braking of the large inertia load in the hydraulic inductor. For the buck power supply, changing of the pressure is realized through pulse flow-rate and low-pressure hydraulic complement (see "Switch-mode Hydraulic Power Supply Theory", 2005 ASME, IMECE-FPST No.79019)[2]. Because the output pressure is determined by the load, pressure buck is still requisite in pressure boost power supply. At the same time the system is unstable and with low efficiency. To deal with the problem that the pressure boost type switch mode hydraulic power supply is unfit for the low pressure load, the principle and the structure of a compounded switch-mode hydraulic power supply are proposed in this paper. In the compounded switch-mode hydraulic power supply, a pressure buck power supply is cascaded after a pressure boost power supply. At the same time, the output hydraulic capacitor of the pressure buck power supply and the input hydraulic capacitor of the pressure boost power supply are removed, which leads to the direct connection of the hydraulic inductors of the two power supplies Because of the same working principles of the two power supplies, one of the hydraulic inductors can be removed. Pressure boost and pressure buck are realized through the synchronically control of the two high - speed switch valves using PWM signal. No matter the outer load determined pressure is higher or lower than the pump pressure, compounded switch-mode hydraulic power supply can provide the proper power (not flow rate) matching actuators' consumption through regulating the duty ratio of the control signal. Therefore the optimal energy -saving is realized. Experimental research shows that the compounded switch-mode hydraulic power supply can realize a continuous bucking and boosting pressure with different duty ratio and the whole efficiency is at least 80%.

Research on Electro-Hydraulic Control of Propellers of the Underwater Vehicles With Switch-Mode Hydraulic Power Supply

2006 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Ying Chen
Keyword(s):  
Control System ◽  
Power Supply ◽  
High Speed ◽  
Weight Ratio ◽  
Pulse Frequency ◽  
Hydraulic Pressure ◽  
Hydraulic Control ◽  
Pulse Frequency Modulation ◽  
Hydraulic Power ◽  
Switch Mode

Switch-mode hydraulic power supply is a hydraulic pressure converting unit made of some distributed hydraulic components, which can boost or buck hydraulic pressure continuously with low power loss (about 20%)and continuous flow-rate. There are two types of switch-mode hydraulic power supply, pressure boost and pressure buck. (see "Switch-mode Hydraulic Power Supply Theory", 2005 ASME, IMECE-FPST No.79019)[1]. This paper introduces a new propeller driving system using the motor of the switch-mode hydraulic power supply for the underwater vehicle. And PFM (Pulse Frequency Modulation) control of high-speed switch-valves is applied to adjust the rotation speed of the propeller. The system has advantages over the widely used servo-valve valve-control system and pump-control system on the energy-weight ratio, anti-contamination performance and energy-saving capacity.

The Modern Direct-Hydraulic System

1946 ◽  
Vol 154 (1) ◽  
pp. 178-208 ◽  
Author(s):  
F. H. Towler
Keyword(s):  
Hydraulic System ◽  
High Speed ◽  
Hydraulic Press ◽  
Hydraulic Pressure ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
The Press ◽  
Hydraulic Accumulator ◽  
Work Done ◽  
Full Pressure

The first hydraulic press invented by Joseph Bramah in 1795 employed the direct-hydraulic system; i.e. hydraulic pressure was directly supplied to the press cylinder by a hydraulic pump and, therefore, the pressure exerted by the press ram was directly proportional to the pressure supplied by the pump, and the speed of the press ram was directly proportional to the delivery of the pump. Later developments in the use of hydraulic power resulted in the invention of the hydraulic accumulator to store liquid under pressure. With the accumulator system the speed and pressure exerted by the press ram are not controlled by the pump, and in fact they cannot be controlled with any precision; also there is considerable wastage of power when the press ram is operating at less than full pressure. The advent of the high-speed reciprocating ram pump has produced the modern direct-hydraulic system in which the press and pump form one self-contained unit. The power to drive the pump is in direct proportion to the work done by the press, and the speed and pressure exerted by the press ram can be precisely controlled. The author considers that a saving of at least 75 per cent in electric power can be made by conversion from the accumulator system to the direct-hydraulic system. Indicator diagrams are reproduced in the paper to show the saving in power which can be achieved by the direct-hydraulic system, and a comparison is made between the power consumption, in kilowatt-hours, of a direct-hydraulic cartridge-drawing press and a mechanical double-rack press doing the same operation. The paper includes a number of illustrations of direct-hydraulic presses, ranging from those of Bramah to present-day types.

scholarly journals Analysis of the dynamic characteristics of downsized aerostatic thrust bearings with different pressure equalizing grooves at high or ultra-high speed

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110180
Author(s):  
Ruzhong Yan ◽  
Haojie Zhang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Rotation Speed ◽  
Dynamic Stiffness ◽  
Simulation Method ◽  
Perturbation Amplitude ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Ultra High Speed ◽  
Air Film

This study adopts the DMT(dynamic mesh technology) and UDF(user defined functions) co-simulation method to study the dynamic characteristics of aerostatic thrust bearings with equalizing grooves and compare with the bearing without equalizing groove under high speed or ultra high speed for the first time. The effects of air film thicness, supply pressure, rotation speed, perturbation amplitude, perturbation frequency, and cross section of the groove on performance characteristics of aerostatic thrust bearing are thoroughly investigated. The results show that the dynamic stiffiness and damping coefficient of the bearing with triangular or trapezoidal groove have obvious advantages by comparing with that of the bearing without groove or with rectangular groove for the most range of air film thickness, supply pressure, rotation speed, perturbation amplitude, especially in the case of high frequency, which may be due to the superposition of secondary throttling effect and air compressible effect. While the growth range of dynamic stiffness decreases in the case of high or ultra-high rotation speed, which may be because the Bernoulli effect started to appear. The perturbation amplitude only has little influence on the dynamic characteristic when it is small, but with the increase of perturbation amplitude, the influence becomes more obvious and complex, especially for downsized aerostatic bearing.

Monopropellant-Driven Free Piston Hydraulic Pump for Mobile Robotic Systems

2004 ◽  
Vol 126 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Timothy G. McGee ◽  
Justin W. Raade ◽  
H. Kazerooni
Keyword(s):  
Hydrogen Peroxide ◽  
High Temperature ◽  
Thermodynamic Analysis ◽  
Flow Rate ◽  
Power Supply ◽  
Robotic Systems ◽  
Hydraulic Fluid ◽  
Hydraulic Pump ◽  
Free Piston

The authors present a novel power supply for mobile robotic systems. A monopropellant (e.g., hydrogen peroxide) decomposes into high temperature gases, which drive a free piston hydraulic pump (FPHP). The elimination of fuel/oxidizer mixing allows the design of simple, lightweight systems capable of operation in oxygen free environments. A thermodynamic analysis has been performed, and an experimental FPHP has been built and tested. The prototype successfully pumped hydraulic fluid, although the flow rate was limited by the off-the-shelf components used.

Study of Hybrid Lubrication at the Tooth Contact of a Wormgear Transmission: Part 2—Results and Discussion

1998 ◽  
Vol 120 (1) ◽  
pp. 112-118
Author(s):  
Qin Yuan ◽  
D. C. Sun ◽  
D. E. Brewe
Keyword(s):  
Temperature Distribution ◽  
Film Thickness ◽  
Numerical Solution ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Loss ◽  
Oil Film ◽  
Supply Pressure ◽  
Transmission Part

Part 2 begins by describing the numerical solution procedures of the hybrid lubrication problem. Results of the computation are then presented that include the detailed pressure and temperature distribution in the oil film, the required supply pressure for maintaining the prescribed minimum oil film thickness, the fluid friction acting on the worm coil surface, the mass flow rate of supply oil, and the power loss associated with the restrictor flow. The feasibility of the hydrostatically lubricated wormgear transmission is discussed in light of these results.

The Dynamic Optimization Analysis of High-Speed Hybrid Thrust Bearing

2010 ◽  
Vol 118-120 ◽  
pp. 507-511
Author(s):  
Kai Sun ◽  
Lan Wang ◽  
Xin Jun Zhao
Keyword(s):  
Dynamic Optimization ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Thrust Bearing ◽  
Orifice Diameter ◽  
Optimization Analysis ◽  
Angular Misalignment ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Dynamic Moment

In this paper, the dynamic characteristics of high-speed hybrid thrust bearing with four-recesses are optimized for different orifice diameter and supply pressure at a given speed condition, the dynamic moment coefficients of hybrid thrust bearing are analyzed, considering the thrust collar angular misalignment case to determine the optimization of orifice diameter and supply pressure under a given speed. The results provide certain reference to the hybrid thrust bearings used in high speed precision spindle.

The Effect of Incomplete Ionization on SiC Devices during High Speed Switching

2017 ◽  
Vol 897 ◽  
pp. 467-470 ◽  
Author(s):  
Kohei Ebihara ◽  
Koutarou Kawahara ◽  
Hiroshi Watanabe ◽  
Shuhei Nakata ◽  
Satoshi Yamakawa
Keyword(s):  
Dynamic Characteristics ◽  
Power Loss ◽  
High Speed ◽  
Deep Level ◽  
Deep Levels ◽  
Acceptor Level ◽  
Fast Switching ◽  
Switching Condition ◽  
Tcad Simulation ◽  
High Speed Switching

SiC devices such as MOSFETs and SBDs reduce power loss in fast-switching condition as compared to Si devices. However, shallow and deep levels in SiC significantly affect dynamic characteristics of SiC devices. We already reported that high densities of deep levels were discovered in Al+-implanted samples other than the shallow Al acceptor level. In this work, we applied the deep level to the TCAD simulation, and examined the behavior of the carriers at high dV/dt conditions.

Development of Test System for Subsea Tree Equipment

2013 ◽  
Vol 440 ◽  
pp. 222-227
Author(s):  
Bao Ping Cai ◽  
Yong Hong Liu ◽  
Yan Ting Zhang ◽  
Jiang Tao Ma ◽  
Yun Wei Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Test System ◽  
Acceptance Testing ◽  
Hydraulic Pressure ◽  
Hydraulic Pump ◽  
Test Procedures ◽  
Hydraulic Power ◽  
Hydraulic Unit ◽  
Pressure Cycling ◽  
Function Testing

A test system for subsea tree equipment is developed for tree function testing after repair. The test system mainly consists of hydraulic unit and electric unit. The hydraulic unit is developed by revamping an old hydraulic power unit, which consist of six components, including reservoir, flush/fill pump circuit, high pressure hydraulic pump circuits, accumulator group, hydraulic supply circuits and fluid return circuit. The electric unit for subsea tree is developed by using NI Compact DAQ system, In order to control the hydraulic unit and acquire the pressure signals easily. The test procedures for flowloops, valve, and hydrostatic hydraulic pressure cycling are proposed based on the factory acceptance testing of subsea tree. A test for a repaired subsea tree is performed by using the developed test system. The results show that the repaired subsea tree is good enough after repair, and verify that the developed test system works well.

Influence of RBD Palm Olein on Hydraulic Pump Performance

2014 ◽  
Vol 931-932 ◽  
pp. 403-407
Author(s):  
Weerapong Chanbua ◽  
Unnat Pinsopon
Keyword(s):  
Energy Efficiency ◽  
Flow Rate ◽  
Hydraulic System ◽  
Palm Olein ◽  
Potential Candidate ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Hydraulic Oil ◽  
Rbd Palm Olein ◽  
Accredited Laboratory

At the present time, researchers try to find alternative fluids for being used as lubricants or hydraulic fluids that are biodegradable and environmental friendly. In this study, Refined-Bleached-Deodorized (RBD) palm olein was investigated whether it is such a potential candidate. RBD palm olein could be easily acquired since it is of the type used as cooking oil. The physical properties of both conventional hydraulic oil and RBD palm olein were tested and compared by an accredited laboratory. The performance of the hydraulic systems when using both fluids as working mediums were also tested and compared. The experimental results show that temperature significantly affected the performance of the hydraulic system when using conventional hydraulic oil, whereas the performance of the hydraulic system when using RBD palm olein barely changed with temperatures. At the temperatures below 60 °C, the RBD palm olein yielded less flow rate and less energy efficiency. However, for the temperatures above 60 °C, the RBD palm olein yielded slightly more flow rate and slightly more energy efficiency. It can be confirmed from this study that RBD palm olein can be used as an alternative hydraulic fluid.

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