Modeling and Validation of a High Speed Rotary PWM On/Off Valve

2009 ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase
Keyword(s):  
High Speed ◽  
Pulse Width Modulation ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Flow Area ◽  
Output Pressure ◽  
Critical Technology ◽  
Variable Displacement ◽  
Pressure Ripple ◽  
Actuation Power

Efficient high-speed on/off valves are a critical technology for enabling digital control of hydraulic systems via pulse-width-modulation (PWM). High-speed valves, when used in virtually variable displacement pumps (VVDP), increase system bandwidth and reduce output pressure ripple by enabling higher PWM frequencies. Our approach to achieving high speed and large flow area with low actuation power is a unidirectional rotary valve designed specifically for PWM. In comparison to conventional valves, the rotary valve reduces valve actuation power from a cubic dependence on PWM frequency to a square dependence by eliminating motion reversals during transition. This paper presents experimental data that validates the rotary valve concept, valve design equations, and dynamic model of a rotary valve based VVDP. Our unoptimized prototype exhibits 65% efficiency at 50% displacement and 15Hz PWM frequency while the validated model projects that an optimized valve is capable of achieving 85% efficiency at 15Hz and 73% at 75Hz.

Design, Modeling, and Validation of a High-Speed Rotary Pulse-Width-Modulation On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Pulse Width ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Output Pressure ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Actuation Power

Efficient high-speed on/off valves are an enabling technology for applying digital control techniques such as pulse-width-modulation (PWM) to hydraulic systems. Virtually variable displacement pumps (VVDPs) are one application where variable displacement functionality is attained using a fixed-displacement pump paired with an on/off valve and an accumulator. High-speed valves increase system bandwidth and reduce output pressure ripple by enabling higher switching frequencies. In addition to fast switching, on/off valves should also have small pressure drop and low actuation power to be effective in these applications. In this paper, a new unidirectional rotary valve designed for PWM is proposed. The valve is unique in utilizing the hydraulic fluid flowing through it as a power source for rotation. An unoptimized prototype capable of high flow rate (40 lpm), high speed (2.8 ms transition time at 100 Hz PWM frequency), and low pressure drop (0.62 MPa), while consuming little actuation power (<0.5% full power or 30 W, scavenged from fluid stream), has been constructed and experimentally validated. This paper describes the valve design, analyzes its performance and losses, and develops mathematical models that can be used for design and simulation. The models are validated using experimental data from a proof-of-concept prototype. The valve efficiency is quantified and suggestions for improving the efficiency in future valves are provided.

High-Speed 4-Way Rotary On/Off Valve for Virtually Variable Displacement Pump/Motor Applications

2011 ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase ◽  
...  
Keyword(s):  
High Speed ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Hydraulic Pump ◽  
Hydraulic Hybrid ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Pump Valve ◽  
Cycle Efficiency ◽  
Physical Displacement

The application of switched mode control to hydraulic systems has the potential of decreasing component complexity, size, and cost. This is accomplished by enabling variable pump or motor functionality using a single on/off valve paired with a compact, inexpensive fixed displacement machine. A 4-way tandem rotary on/off valve is presented in this paper that extends a novel rotary valve concept (experimentally validated for pump applications) to hydraulic pump/motors. The pump/valve system is referred to as a Virtually Variable Displacement Pump/Motor (VVDPM) since the effective displacement of the system is variable and not the physical displacement of the pump itself. This paper investigates the design and efficiency of the proposed rotary valve when utilizing the VVDPM on a light weight power-split hydraulic hybrid passenger vehicle that is driven over a standard federal drive cycle. Simulated VVDPM efficiency maps are presented for motoring and pumping and the cycle efficiency of an optimized VVDPM is compared to that of a typical bent axis unit. Vehicle fuel economy is also explored through simulation.

High Speed Rotary Pulse Width Modulated On/Off Valve

2007 ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
James D. Van de Ven ◽  
Meng Wang ◽  
Perry Y. Li ◽  
...  
Keyword(s):  
High Speed ◽  
Viscous Friction ◽  
Power Input ◽  
Axial Position ◽  
Reverse Direction ◽  
Duty Ratio ◽  
Concept Design ◽  
Hydraulic Systems ◽  
Output Pressure ◽  
Acceleration And Deceleration

A key enabling technology to effective on/off valve based control of hydraulic systems is the high speed on/off valve. High speed valves improve system efficiency for a given PWM frequency, offer faster control bandwidth, and produce smaller output pressure ripples. Current valves rely on the linear translation of a spool or poppet to meter flow. The valve spool must reverse direction twice per PWM cycle. This constant acceleration and deceleration of the spool requires a power input proportional to the PWM frequency cubed. As a result, current linear valves are severely limited in their switching frequencies. In this paper, we present a novel fluid driven PWM on/off valve design that is based on a unidirectional rotary spool. The spool is rotated by capturing momentum from the fluid flow through the valve. The on/off functionality of our design is achieved via helical barriers that protrude from the surface of a cylindrical spool. As the spool rotates, the helical barriers selectively channel the flow to the application (on) or to tank (off). The duty ratio is controlled by altering the axial position of the spool. Since the spool no longer accelerates or decelerates during operation, the power input to drive the valve must only compensate for viscous friction, which is proportional to the PWM frequency squared. We predict that our current design, sized for a nominal flow rate of 40l/m, can achieve a PWM frequency of 84Hz. This paper presents our valve concept, design equations, and an analysis of predicted performance. A simulation of our design is also presented.

The Application of HPWM in Improving Vehicle Lateral Stability

2014 ◽  
Vol 936 ◽  
pp. 2171-2176
Author(s):  
An Jing Zhang ◽  
Yan Hai Xu ◽  
Xin Lv
Keyword(s):  
High Speed ◽  
Pulse Width Modulation ◽  
Control Unit ◽  
Lateral Stability ◽  
Hydraulic Control ◽  
Output Pressure ◽  
Switching Valve ◽  
High Speed Switching ◽  
Frequency Pulse

The application of the High-frequency pulse width modulation (HPWM) for improving vehicle lateral stability is investigated in the paper. Firstly, a hydraulic control unit (HCU) combined with a high-speed switching valve (HSV) for controlling hydraulic oil pressure by adjusting duty cycle is presented. Then, a typical control strategy is described based on the application of HPWM. Finally, by using a 15dofs vehicle model, a simulation is carried out to investigate the role of HPWM on improving vehicle lateral stability. The results show that HPWM is capable to control the output pressure of HSV accurately and improve vehicle lateral stability effectively.

Analytical Coupled Modeling and Model Validation of Hydraulic On/Off Valves

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
John Mahrenholz ◽  
John Lumkes
Keyword(s):  
High Speed ◽  
Eddy Currents ◽  
Hydraulic Systems ◽  
Coupled Modeling ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Fluid Transients ◽  
Pressure Ripple ◽  
Valve Dynamics ◽  
Fully Coupled

The goal of this paper is to describe a method for modeling high speed on/off valves. This model focuses on the nonlinearities of the electromagnetic, fluidic, and mechanical domains, specifically within solenoid driven poppet style valves. By including these nonlinearities, the model accurately predicts valve transition time for different driving voltages and valve strokes. The model also predicts fluid transients such as pressure ripple. Unique attributes of the model are the inclusion of the effect of eddy currents and fringing while still being fully coupled with the fluid and mechanical domains. A prototype was constructed and used to experimentally validate the model. By developing accurate lumped parameter models, valve dynamics can be applied to hydraulic systems to accurately capture their dynamics.

Efficiency Testing of an Adjustable Linkage Triplex Pump

2014 ◽  
Author(s):  
Shawn R. Wilhelm ◽  
James D. Van De Ven
Keyword(s):  
Second Generation ◽  
High Efficiency ◽  
Mechanical Efficiency ◽  
Operating Conditions ◽  
Hydraulic Systems ◽  
Wide Range ◽  
Potential Applications ◽  
Work Input ◽  
Variable Displacement ◽  
Pressure Ripple

Current state of the art variable displacement pumps suffer from poor efficiency at low volumetric displacement. Additionally, their performance is strongly dependent on operating conditions. A new variable displacement linkage pump architecture has been developed which can achieve high efficiency across a wide range of operating conditions. Previous work has described the kinematics, energy loss modeling, and experimental validation of a low power single cylinder prototype as well as the design of a second generation prototype. The second generation pump employs roller element bearings in its joints to minimize friction losses and the three cylinder design reduces the pressure ripple. In this paper, experimental characterization is presented of the new 21 MPa, 6.75 cc/rev pump. High mechanical efficiency is achieved at low volumetric displacements at partial loads as low as 0.6% of maximum power. Poorly performing cartridge check valves result in low volumetric efficiencies at low displacements. Close agreement was obtained between the model and predicted work input using measured cylinder data as an input into the model. This work shows that the presented pump with properly functioning valves can achieve high efficiency across a wide range of operating conditions. Having such versatile pump performance can greatly improve the performance of hydraulic systems as well as expand their potential applications.

scholarly journals Sensorless LC Filter Implementation for Permanent Magnet Machine Drive Using Observer-Based Voltage and Current Estimation

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3596
Author(s):  
Chia-Ming Liang ◽  
Yi-Jen Lin ◽  
Jyun-You Chen ◽  
Guan-Ren Chen ◽  
Shih-Chin Yang
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Output Current ◽  
Current Harmonics ◽  
Pwm Inverter ◽  
Current Estimation ◽  
Filter Output ◽  
Lc Filter ◽  
Parameter Error

For pulse width modulation (PWM) inverter drives, an LC filter can cascade to a permanent magnet (PM) machine at inverter output to reduce PWM-reflected current harmonics. Because the LC filter causes resonance, the filter output current and voltage are required for the sensorless field-oriented control (FOC) drive. However, existing sensors and inverters are typically integrated inside commercial closed-form drives; it is not possible for these drives to obtain additional filter output signals. To resolve this integration issue, this paper proposes a sensorless LC filter state estimation using only the drive inside current sensors. The design principle of the LC filter is first introduced to remove PWM current harmonics. A dual-observer is then proposed to estimate the filter output current and voltage for the sensorless FOC drive. Compared to conventional model-based estimation, the proposed dual-observer demonstrates robust estimation performance under parameter error. The capacitor parameter error shows a negligible influence on the proposed observer estimation. The filter inductance error only affects the capacitor current estimation at high speed. The performance of the sensorless FOC drive using the proposed dual-observer is comparable to the same drive using external sensors for filter voltage and current measurement. All experiments are verified by a PM machine with only 130 μH phase inductance.

Dynamic vacuum pressure tracking control with high-speed on-off valves

2018 ◽  
Vol 232 (10) ◽  
pp. 1325-1336 ◽  
Author(s):  
Gang Yang ◽  
Kai Chen ◽  
Linglong Du ◽  
Jingmin Du ◽  
Baoren Li
Keyword(s):  
Mass Flow ◽  
Pulse Width ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Sliding Mode ◽  
Tracking System ◽  
Vacuum Pressure ◽  
Chamber Pressure ◽  
Asymmetric Structure ◽  
The Impact

A vacuum pressure tracking system with high-speed on-off valves is a discontinuous system due to the discrete nature of high-speed on-off valves. Chamber pressure changes in the system are determined by the mass flow rates during the processes of charging and discharging. Here, a sliding mode controller with an asymmetric compensator based on average mass flow rate is designed for accurate vacuum pressure tracking. The controller output signal is converted into the duty cycles of the high-speed on-off valves via a pulse width modulation pulsing scheme. Owing to the extreme asymmetry of the processes, an asymmetric structure comprising one high-speed on-off valve in the charging unit and three high-speed on-off valves in the discharging unit is applied to weaken the impact of asymmetry. In addition, an asymmetric compensator is also designed to modify the pulse width modulation pulsing scheme to further eliminate the asymmetry. Experimental results indicate that the proposed controller achieves better performance in pressure tracking with the asymmetric compensator overcoming process asymmetry and enhancing system robustness.

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.

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