Phase-Shift High-Speed Valve for Switch-Mode Control

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
James D. Van de Ven ◽  
Allan Katz
Keyword(s):  
Phase Shift ◽  
High Speed ◽  
Viscous Friction ◽  
Duty Ratio ◽  
Switching Frequency ◽  
Full Potential ◽  
Hydraulic Actuator ◽  
Mode Control ◽  
Switch Mode ◽  
Variable Displacement

Hydraulic applications requiring a variation in the speed or torque of actuators have historically used throttling valve control or a variable displacement pump or motor. An alternative method is switch-mode control that uses a high-speed valve to rapidly switch between efficient on and off states, allowing any hydraulic actuator to have virtually variable displacement. An existing barrier to switch-mode control is a fast and efficient high-speed valve. A novel high-speed valve concept is proposed that uses a phase shift between two tiers of continuously rotating valve spools to achieve a pulse-width modulated flow with any desired duty ratio. An analysis of the major forms of energy loss, including throttling, compressibility, viscous friction, and internal leakage, is performed on a disk spool architecture. This analysis also explores the use of a hydrodynamic thrust bearing to maintain valve clearance. A nonoptimized design example of a phase-shift valve operating at 100 Hz switching frequency at 10 l/min demonstrates an efficiency of 73% at a duty ratio of 1 and 64% at 0.75 duty ratio. Numerous opportunities exist for improving this efficiency including design changes and formal optimization. The phase-shift valve has the potential to enable switch-mode hydraulic circuits. The valve has numerous benefits over existing technology yet requires further refinement to realize its full potential.

Development of a High-Speed On-Off Valve for Switch-Mode Control of Hydraulic Circuits With Four-Quadrant Control

2010 ◽  
Author(s):  
Jeslin J. Wu ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Average Power ◽  
Viscous Friction ◽  
Valve Design ◽  
Rotating Disc ◽  
Mode Control ◽  
Switch Mode ◽  
Variable Displacement ◽  
Four Quadrant ◽  
Hydraulic Circuits

Hydraulic circuits are typically controlled by throttling valves or variable displacement pump/motors. The first method throttles fluid for a desired pressure output and excess energy is lost through heat. While variable displacement pumps are more efficient, they are often large and expensive. An alternate method is the switch-mode control of hydraulic circuits through high-speed on-off valves. The proposed on-off valve design makes use of a continuously rotating disc to modulate flow between on and off states; the average power output or pulse duration is determined by the relative phase shift between the input and output ports. The addition of a directional valve to the the high-speed three-way valve allows any fixed displacement actuator to behave like a virtually variable displacement unit that is capable of four-quadrant control. In this paper a mathematical model focusing on the throttling, compressibility, internal leakage and viscous friction losses is developed and utilized to optimize the valve design for highest efficiency.

Design of a Crank-Slider Spool Valve for Switch-Mode Circuits With Experimental Validation

2017 ◽  
Vol 140 (6) ◽  
Author(s):  
Shaun E. Koktavy ◽  
Alexander C. Yudell ◽  
James D. Van de Ven
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Experimental Validation ◽  
Viscous Friction ◽  
Transition Time ◽  
Switching Frequency ◽  
Experimental Demonstration ◽  
High Switching Frequency ◽  
Switch Mode ◽  
Spool Valve

A challenge in realizing switch-mode hydraulic circuits is the need for a high-speed valve with fast transition time and high switching frequency. The work presented includes the design and modeling of a suitable valve and experimental demonstration of the prototype in a hydraulic boost converter. The design consists of two spools driven by crank-sliders, designed for 120 Hz maximum switching frequency at a flow rate of 22.7 lpm. The fully open throttling loss is designed for <2% of the rated pressure of 34.5 MPa. The transition time is less than 5% (0.42 ms at 120 Hz) of the total cycle and the duty cycle is adjustable from 0 to 1. Leakage and viscous friction losses in the design are less than 2% of the rated hydraulic energy per cycle. The experimental results agreed well with the model resulting in a 3% variation in transition time. The use of the high-speed valve in a pressure boosts converter demonstrated boost ratio capabilities of 1.08–2.06.

Crank-Slider Spool Valve for Switch-Mode Circuits

2015 ◽  
Author(s):  
Alexander C. Yudell ◽  
Shaun E. Koktavy ◽  
James D. Van de Ven
Keyword(s):  
Duty Cycle ◽  
High Speed ◽  
Volumetric Flow Rate ◽  
Viscous Friction ◽  
Total Power ◽  
Design Solution ◽  
Switching Frequency ◽  
Trade Offs ◽  
Switch Mode ◽  
Transition Times

A key component of switch-mode hydraulic circuits is a high-speed two-position three-way valve with a variable duty cycle. This paper presents a new valve architecture that consists of two valve spools that are axially driven by crank-slider mechanisms. By phase shifting the two crank links, which are on a common crankshaft, the duty cycle of the valve is adjusted. The two spools split and re-combine flow such that two switching cycles occur per revolution of the crankshaft. Because the spools move in a near-sinusoidal trajectory, the peak spool velocities are achieved at mid-stroke where the valve land transitions across the ports, resulting in short valve transition times. The spool velocity is lower during the remainder of the cycle, reducing viscous friction losses. A dynamic model is constructed of this new valve operating at 120 Hz switching frequency in a switch-mode circuit. The model is used to illustrate design trade-offs and minimize energy losses in the valve. The resulting design solution transitions to the on-state in 5% of the switching period and the combined leakage and viscous friction in the valve dissipate 1.7% of the total power at a pressure of 34.5MPa and volumetric flow rate of 22.8L/min.

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.

Design of a High-Speed On-Off Valve

2009 ◽  
Author(s):  
Allan A. Katz ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
First Generation ◽  
Viscous Friction ◽  
Input Power ◽  
Future Research ◽  
Switching Frequency ◽  
Efficient Design ◽  
Output Pressure ◽  
Parameter Values ◽  
Valve Control

On-off control of hydraulic circuits enables significant improvements in efficiency compared with throttling valve control. A key enabling technology to on-off control is an efficient high-speed on-off valve. This paper documents the design of an on-off hydraulic valve that minimizes input power requirements and increases operating frequency over existing technology by utilizing a continuously rotating valve design. This is accomplished through use of spinning port discs, which divides the flow into pulses, with the relative phase between these discs determining the pulse duration. A mathematical model for determining system efficiency is developed with a focus on the throttling, leakage, compressibility, and viscous friction power losses of the valve. Parameters affecting these losses were optimized to produce the most efficient design under the chosen disc-style architecture. Using these optimum parameter values, a first generation prototype valve was developed and experimental data collected. The experimental valve matched predicted output pressure and flows well, but suffered from larger than expected torque requirements and leakage. In addition, due to motor limitations, the valve was only able to achieve a 64Hz switching frequency versus the designed 100Hz frequency. Future research will focus on improving the prototype valve and improving the analytical model based on the experimental results.

Experimental Validation of a Soft Switch for a Virtually Variable Displacement Pump

2014 ◽  
Author(s):  
Brandon K. Beckstrand ◽  
James D. Van De Ven
Keyword(s):  
High Speed ◽  
Release Mechanism ◽  
Soft Switch ◽  
Major Drawback ◽  
Switch Operation ◽  
Switch Mode ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Switch Mechanism ◽  
Proper Operation

As an alternative to a variable displacement pump, a fixed displacement pump can be made to function as a virtually variable displacement unit by using a high-speed valve to pulse-width modulate the flow, creating a switch-mode circuit. A major drawback of switch-mode circuits is throttling and compressibility energy losses during valve transitions. One method of minimizing these losses is soft switching, where the flow that would normally be throttled across the high speed valve during transitions is absorbed in a small variable volume chamber. The concept for a novel soft switch mechanism that uses the pressure signal at the exit of the pump to release a lock on the soft switch chamber was previously presented. This paper describes the soft switch concept in more detail and outlines a numerical model used to predict and optimize soft switch operation. Experimental results are presented that demonstrate proper operation of the soft switch lock-release mechanism.

APPLICATION OF SLIDING MODE CONTROL TO SWITCH-MODE POWER SUPPLIES

1995 ◽  
Vol 05 (03) ◽  
pp. 337-354 ◽  
Author(s):  
G. SPIAZZI ◽  
P. MATTAVELLI ◽  
L. ROSSETTO ◽  
L. MALESANI
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Variable Structure ◽  
Current Mode ◽  
Power Supplies ◽  
Switching Frequency ◽  
Variable Structure Systems ◽  
Control Techniques ◽  
Mode Control ◽  
Switch Mode

Switch-mode power supplies represent a particular class of variable structure systems (VSS). Thus, they can take advantage of non-linear control techniques developed for this class of systems. In this paper the so called sliding mode control is reviewed and its application to switch-mode power supplies is discussed. Sliding mode control extends the properties of hysteresis control to multi-variable environments, resulting in stability even for large supply and load variations, good dynamic response and simple implementation. Application to dc–dc converters, as well as rectifiers and inverters, is analyzed and provisions to overcome the inherent drawbacks of sliding mode control, i.e. variable switching frequency and possible steady-state errors, are described. Experimental results are also reported, which allow a comparison between the sliding mode approach and other standard control techniques, e.g. current-mode control, showing its effectiveness.

scholarly journals Hybrid-modulation-based control technique for reduction of output voltage ripples in frequency-modulated switch-mode power converters

2018 ◽  
Vol 9 (3) ◽  
pp. 1272
Author(s):  
Deniss Stepins ◽  
Jin Huang ◽  
Janis Audze
Keyword(s):  
Output Voltage ◽  
Power Converters ◽  
Control Technique ◽  
Duty Ratio ◽  
Modulation Scheme ◽  
Switching Frequency ◽  
Hybrid Modulation ◽  
Straightforward Application ◽  
Switch Mode ◽  
Electromagnetic Emissions

<span>In this paper a novel control technique for switching-frequency-modulated switch-mode power converters (SMPC) operating in discontinuous conduction mode is proposed. The use of the technique leads to significant reduction in peak-to-peak output voltage and peak currents increased due to straightforward application of switching frequency modulation (SFM). The technique is based on hybrid modulation scheme in which both switching frequency and duty ratio are modulated simultaneously by the same modulation signal. Theoretical analysis and experimental verification of the proposed technique are presented in details. Both computer simulations and experiments show that switching-frequency-modulated SMPC with the proposed control technique in comparison to SMPC without SFM has appreaciably lower conducted electromagnetic emissions, at the cost of slightly increased peak-to-peak output voltage and peak currents.</span>

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%.

scholarly journals Research on predictive sliding mode control strategy for horizontal vibration of ultra-high-speed elevator car system based on adaptive fuzzy

2021 ◽  
Vol 54 (3-4) ◽  
pp. 360-373
Author(s):  
Hong Wang ◽  
Mingqin Zhang ◽  
Ruijun Zhang ◽  
Lixin Liu
Keyword(s):  
Sliding Mode Control ◽  
High Speed ◽  
Sliding Mode ◽  
Mode Switching ◽  
Parameter Uncertainties ◽  
Horizontal Vibration ◽  
Adaptive Fuzzy ◽  
Mode Control ◽  
System A ◽  
Ultra High Speed

In order to effectively suppress horizontal vibration of the ultra-high-speed elevator car system. Firstly, considering the nonlinearity of guide shoe, parameter uncertainties, and uncertain external disturbances of the elevator car system, a more practical active control model for horizontal vibration of the 4-DOF ultra-high-speed elevator car system is constructed and the rationality of the established model is verified by real elevator experiment. Secondly, a predictive sliding mode controller based on adaptive fuzzy (PSMC-AF) is proposed to reduce the horizontal vibration of the car system, the predictive sliding mode control law is achieved by optimizing the predictive sliding mode performance index. Simultaneously, in order to decrease the influence of uncertainty of the car system, a fuzzy logic system (FLS) is designed to approximate the compound uncertain disturbance term (CUDT) on-line. Furthermore, the continuous smooth hyperbolic tangent function (HTF) is introduced into the sliding mode switching term to compensate the fuzzy approximation error. The adaptive laws are designed to estimate the error gain and slope parameter, so as to increase the robustness of the system. Finally, numerical simulations are conducted on some representative guide rail excitations and the results are compared to the existing solution and passive system. The analysis has confirmed the effectiveness and robustness of the proposed control method.

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