The Use of Derivative Pressure Feedback in High Performance Hydraulic Servomechanisms

1962 ◽  
Vol 84 (1) ◽  
pp. 8-14 ◽  
Author(s):  
T. R. Welch
Keyword(s):  
Resonant Frequency ◽  
Power Efficiency ◽  
High Performance ◽  
Corner Frequency ◽  
Hydraulic Systems ◽  
Feedback Systems ◽  
Servo Valve ◽  
Fluid Resonance ◽  
Positive Displacement ◽  
Pressure Feedback

Hydraulic servomechanisms are sometimes used to drive a load member which is predominantly inertia. The usual overriding requirements for output disturbance discrimination and high power efficiency dictate a simple closed center, flow type, servo valve, and a positive displacement actuator. The resulting transfer function relating output velocity to servo valve input current invariably includes an underdamped quadratic lag due to fluid compliance. In simple hydraulic servo systems, the corner frequency of this quadratic lag represents the absolute limit to system bandwidth. Pressure feedback systems have been devised to damp the fluid resonance so effectively that bandwidth extension beyond the quadratic corner frequency is entirely feasible. Unfortunately, such a scheme destroys the natural output disturbance discrimination inherent in the closed center hydraulic systems. A hybrid method of compensation is proposed whereby pressure feedback occurs only in the region of the resonant frequency, effectively preserving the natural output disturbance discrimination characteristics at the lower frequencies. The pressure drop across positive displacement type hydraulic actuators is a good measure of acceleration. Therefore, the technique involves feeding back this load differential pressure, sensed by electromechanical transducers, through a simple RC high pass (derivative) filter. The effectiveness of the damping is determined by the filter time constant and loop gain. Experimental results verify linear predictions of the possibility of extending the closed loop bandwidth beyond the uncompensated resonant frequency.

Regulator and Tracking System Design for a Single-Rod Hydraulic Actuator via Pole-Placement Approach

2011 ◽  
Author(s):  
Hamed Moradi ◽  
Kambiz Haji Hajikolaei ◽  
Firooz Bakhtiari-Nejad
Keyword(s):  
High Performance ◽  
Transfer Functions ◽  
Tracking System ◽  
Input Voltage ◽  
Pole Placement ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Tracking Accuracy ◽  
Integral Control ◽  
Servo Valve

Due to the nonlinear dynamics of hydraulic systems, applying high performance closed-loop controllers is complicated. In this paper, a single-rod hydraulic actuator is considered in which load displacement (for positioning purposes) is controlled via manipulation of the input voltage to the servo-valve. Dynamics of the servo-valve is described by first and second order transfer functions (named as Models 1 and 2). Through linearization of the system around its operating points, dynamics of the hydraulic actuator is represented in the state space. A full-order observer is designed for on-line states estimation. Then, feedback control system is designed for both regulation and tracking objectives through pole-placement approach based on general canonical control form (GCCF). For tracking of the desired commands, a modified integral control is required (since the plant has not integrator). Results show that the regulation, states estimation, desired tracking and final tracking accuracy are achieved after applying the controller. Required input voltage and load positioning are compared for the two distinct dynamics of the servo-valve (Model 1 and 2).

scholarly journals High Performance Multistring Converter Topology for Three-Phase Grid Tied 200 kW Photovoltaic Generating System

2017 ◽  
Vol 1 (2) ◽  
Author(s):  
Mohammad Rustam M. L. ◽  
F. Danang Wijaya
Keyword(s):  
Power Efficiency ◽  
High Performance ◽  
Reactive Power ◽  
Simulation Method ◽  
Operating Conditions ◽  
Total System ◽  
Voltage Reference ◽  
Pv System ◽  
Three Phase ◽  
Converter Topology

Under various external conditions, grid connected PV system performance is strongly affected by the topology that is used to connect a PV system with grid. This research aims to design a multistring based converter topology for three-phase grid connected 200 kW PV system that has a high performance in various operating conditions. Research was done by a simulation method using Matlab-Simulink with performance being evaluated including the generated power, efficiency, power quality in accordance with grid requirements, as well as the power flow. In the simulation, multistring converter topology was designed using two dc-dc boost multistring converters connected in parallel to a centralized of three-phase three-level NPC inverter with the size of the string being shorter and more parallel strings as well as the maximum voltage of the PV array of 273.5 V close to dc voltage reference of 500 V. Each dc-dc boost multistring converter have individual MPPT controllers. The simulation results showed that this multistring converter topology had a high performance in various operating conditions. This due to more power generated by the NPC inverter (> 190 kW) at the time of high power generation on the STC conditions (1000 W/m2, 25 oC), the lowest efficiency of the total system is 95.08 % and the highest efficiency of the total system is 99.4 %, the quality of the power generated in accordance with the requirements of grid, as well as the inverter put more active power to the grid and less reactive power to the grid. The response of the inverter slightly worse for loads with greater reactive power and unbalanced.

Rack Server Solution in Data Center

2015 ◽  
Author(s):  
Sheng Kang ◽  
Guofeng Chen ◽  
Chun Wang ◽  
Ruiquan Ding ◽  
Jiajun Zhang ◽  
...  
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
Power Supply ◽  
Data Center ◽  
Power Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
High Growth ◽  
General Purpose ◽  
Power Supplies

With the advent of big data and cloud computing solutions, enterprise demand for servers is increasing. There is especially high growth for Intel based x86 server platforms. Today’s datacenters are in constant pursuit of high performance/high availability computing solutions coupled with low power consumption and low heat generation and the ability to manage all of this through advanced telemetry data gathering. This paper showcases one such solution of an updated rack and server architecture that promises such improvements. The ability to manage server and data center power consumption and cooling more completely is critical in effectively managing datacenter costs and reducing the PUE in the data center. Traditional Intel based 1U and 2U form factor servers have existed in the data center for decades. These general purpose x86 server designs by the major OEM’s are, for all practical purposes, very similar in their power consumption and thermal output. Power supplies and thermal designs for server in the past have not been optimized for high efficiency. In addition, IT managers need to know more information about servers in order to optimize data center cooling and power use, an improved server/rack design needs to be built to take advantage of more efficient power supplies or PDU’s and more efficient means of cooling server compute resources than from traditional internal server fans. This is the constant pursuit of corporations looking at new ways to improving efficiency and gaining a competitive advantage. A new way to optimize power consumption and improve cooling is a complete redesign of the traditional server rack. Extracting internal server power supplies and server fans and centralizing these within the rack aims to achieve this goal. This type of design achieves an entirely new low power target by utilizing centralized, high efficiency PDU’s that power all servers within the rack. Cooling is improved by also utilizing large efficient rack based fans for airflow to all servers. Also, opening up the server design is to allow greater airflow across server components for improved cooling. This centralized power supply breaks through the traditional server power limits. Rack based PDU’s can adjust the power efficiency to a more optimum point. Combine this with the use of online + offline modes within one single power supply. Cold backup makes data center power to achieve optimal power efficiency. In addition, unifying the mechanical structure and thermal definitions within the rack solution for server cooling and PSU information allows IT to collect all server power and thermal information centrally for improved ease in analyzing and processing.

Resource Allocation for a Cooperative Broadband MIMO-OFDM System

2010 ◽  
pp. 382-398
Author(s):  
Ibrahim Y. Abualhaol ◽  
Mustafa M. Matalgah
Keyword(s):  
Resource Allocation ◽  
Power Distribution ◽  
Power Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
Ofdm System ◽  
Frequency Space ◽  
Input Multiple Output ◽  
Power Loading ◽  
Mimo Ofdm

In this chapter, a cooperative broadband relay-based resource allocation technique is proposed for adaptive bit and power loading multiple-input-multiple-output/orthogonal frequency division multiplexing (MIMO-OFDM) system. In this technique, sub-channels allocation, M-QAM modulation order, and power distribution among different sub-channels in the relay-based MIMO-OFDM system are jointly optimized according to the channel state information (CSI) of the relay and the direct link. The transmitted stream of bits is divided into two parts according to a suggested cooperative protocol that is based on sub-channel-division. In this protocol, the first part is sent directly from the source to the destination, and the second part is relayed to the destination through an indirect link. Such a cooperative relay-based system enables us to exploit the inherent system diversities in frequency, space and time to maximize the system power efficiency. The BER performance using this cooperative sub-channel-division protocol with adaptive sub-channel assignment and adaptive bit/power loading are presented and compared with a noncooperative ones. The use of cooperation in a broadband relay-based MIMO-OFDM system showed high performance improvement in terms of BER.

scholarly journals Transformerless Quasi-Z-Source Inverter to Reduce Leakage Current for Single-Phase Grid-Tied Applications

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 312 ◽  
Author(s):  
Woo-Young Choi ◽  
Min-Kwon Yang
Keyword(s):  
Leakage Current ◽  
Power Efficiency ◽  
High Performance ◽  
Single Phase ◽  
Power Devices ◽  
Common Mode Voltage ◽  
Control Scheme ◽  
Frequency Components ◽  
The Common ◽  
Current Reduction

The conventional single-phase quasi-Z-source (QZS) inverter has a high leakage current as it is connected to the grid. To address this problem, this paper proposes a transformerless QZS inverter, which can reduce the leakage current for single-phase grid-tied applications. The proposed inverter effectively alleviates the leakage current problem by removing high-frequency components for the common-mode voltage. The operation principle of the proposed inverter is described together with its control strategy. A control scheme is presented for regulating the DC-link voltage and the grid current. A 1.0 kW prototype inverter was designed and tested to verify the performance of the proposed inverter. Silicon carbide (SiC) power devices were applied to the proposed inverter to increase the power efficiency. The experimental results showed that the proposed inverter achieved high performance for leakage current reduction and power efficiency improvement.

Nonlinear Compensation for High Performance Feedback Systems With Actuator Imperfections

2013 ◽  
Author(s):  
Cameron L. Mock ◽  
Zachary T. Hamilton ◽  
Dustin Carruthers ◽  
John F. O’Brien
Keyword(s):  
Performance Feedback ◽  
High Performance ◽  
Vibration Suppression ◽  
Actuator Saturation ◽  
Design Method ◽  
Nonlinear Feedback ◽  
Feedback Systems ◽  
Performance Requirements ◽  
Common Causes ◽  
And Performance

Measures to reduce control performance for greater robustness (e.g. reduced bandwidth, shallow loop roll-off) must be enhanced if the plant or actuators are known to have nonlinear characteristics that cause variations in loop transmission. Common causes of these nonlinear behaviors are actuator saturation and friction/stiction in the moving parts of mechanical systems. Systems with these characteristics that also have stringent closed loop performance requirements present the control designer with an extremely challenging problem. A design method for these systems is presented that combines very aggressive Nyquist-stable linear control to provide large negative feedback with nonlinear feedback to compensate for the effects of multiple nonlinearities in the loop that threaten stability and performance. The efficacy of this approach is experimentally verified on a parallel kinematic mechanism with multiple uncertain nonlinearities used for vibration suppression.

Dynamic impact of hydraulic systems using pressure feedback for active damping

2021 ◽  
Vol 89 ◽  
pp. 454-469
Author(s):  
Min Cheng ◽  
Shaqi Luo ◽  
Ruqi Ding ◽  
Bing Xu ◽  
Junhui Zhang
Keyword(s):  
Active Damping ◽  
Hydraulic Systems ◽  
Dynamic Impact ◽  
Pressure Feedback

Design and Characteristics Analysis of Bourdon Tube Pressure Feedback for 2D Pressure Servo Valve

2018 ◽  
Author(s):  
Xiqing Zuo ◽  
Guowen Liu ◽  
Shouli Zhang ◽  
Sheng Li ◽  
Jian Ruan
Keyword(s):  
Servo Valve ◽  
Characteristics Analysis ◽  
Pressure Feedback

Development of the Servo Valve with High Durability Using Split-Type Sleeve – Reduction of Wear with Ceramic Material –

2019 ◽  
Vol 31 (5) ◽  
pp. 707-714
Author(s):  
Koki Sakakibara ◽  
◽  
Shunya Suzuki ◽  
Kazushi Shibata ◽  
Yuto Sawada ◽  
...  
Keyword(s):  
Ceramic Material ◽  
Ceramic Materials ◽  
Hydraulic Systems ◽  
Servo Valve ◽  
High Durability ◽  
Water Hydraulic

Reduction of leakage is a major problem in water hydraulic systems. With a servo valve, it is possible to reduce the internal leakage by reducing the clearance between a spool and a sleeve. However, because the clearance is reduced, wear tends to occur easily between the spool and sleeves when the servo valve is driven. As a result, the durability of the servo valve is reduced. Attention is paid to the durability against wear of ceramic materials, and the wear can be suppressed by using ceramics as the materials of the spool and sleeve. Thus, one can check whether the wear between the spool and sleeve can be suppressed, thereby improving the durability of the servo valve.

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