Soft Switch Lock-Release Mechanism for a Switch-Mode Hydraulic Pump Circuit

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Soft Switching ◽  
Proper Function ◽  
Energy Losses ◽  
Release Mechanism ◽  
Soft Switch ◽  
Locking Mechanism ◽  
Duty Cycles ◽  
Switch Mode ◽  
Hydraulic Circuits

Switch-mode hydraulic circuits are a theoretically efficient, compact, fast responding, and inexpensive control option. Despite the many potential benefits of switch-mode hydraulic circuits, the control method suffers from large energy losses during transitions of the high-speed valve due to throttling and fluid compressibility. Rannow and Li previously proposed utilizing soft switching to minimize the throttling energy loss (Rannow and Li, “Soft Switching Approach to Reducing Transition Losses in On/Off Hydraulic Valve,” J. Dyn. Syst., Measure. Control (in press)). A major challenge of this approach is a locking soft switch that releases quickly and with precise timing, while under load. In this paper, a novel soft switch locking mechanism is presented that utilizes the pressure signal in the switched volume to trigger the release. A dynamic model is developed of three unique soft switch circuits and two control circuits that create a virtually variable displacement pump. The model is used to perform a grid search optimization of the soft switch parameters for the three circuits. The three soft switch circuits reduce the throttling and compressibility energy losses between 49% and 66% compared with the control circuit. The simulation results demonstrated that the soft switch circuits perform as expected for duty cycles and pressures below the design conditions. At higher duty cycles and pressures, the short time the circuit is connected to tank prevented the soft switches from resetting between cycles, preventing proper function. This novel lock and release soft switch mechanism enables soft switching in switch-mode hydraulic circuits, which significantly reduces throttling and compressibility energy losses during valve transitions. Lower losses during valve transition allow the use of slower switching valves, lowering energy consumption, and cost.

scholarly journals Design and Validation of a Soft Switch for a Virtually Variable Displacement Pump

2017 ◽  
Vol 140 (6) ◽  
Author(s):  
Brandon K. Beckstrand ◽  
James D. Van de Ven
Keyword(s):  
Energy Loss ◽  
Soft Switching ◽  
Cycle Period ◽  
Soft Switch ◽  
Load Pressure ◽  
Locking Mechanism ◽  
Piston Displacement ◽  
Switch Mode ◽  
Displacement Pump ◽  
Variable Displacement

Switch-mode hydraulic control is a compact and theoretically efficient alternative to throttling valve control or variable displacement pump control. However, a significant source of energy loss in switch-mode circuits is due to throttling during valve transitions. Hydraulic soft switching was previously proposed as a method of reducing the throttling energy loss, by absorbing, in a small variable volume chamber, the flow that would normally be throttled across the transitioning high-speed valve. An active locking mechanism was previously proposed that overcomes the main challenge with soft switching, which is a lock mechanism that releases quickly and with precise timing. This prior work demonstrated a reduction in energy losses by 66% compared to a control circuit. In this paper, a numerical model is developed for a switch-mode virtually variable displacement pump (VVDP) circuit, utilizing the proposed soft switch. The model is then used as a means of designing a proof of concept prototype to validate the model. The prototype design includes methods for controlling the soft switch spring preload, travel distance, piston displacement required to unlock the soft switch, valve command duty cycle, switching cycle period, and load pressure. Testing demonstrated that the soft switch circuit performed as expected in a baseline condition. The operating region for this prototype was found to be quite narrow. However, the model does a good job of predicting the displacement of the soft switch.

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.

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.

Soft Switching in Switched Inertance Hydraulic Circuits

2016 ◽  
Author(s):  
Alexander C. Yudell ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Soft Switching ◽  
Power Delivery ◽  
Lumped Parameter Model ◽  
Energy Losses ◽  
Hydraulic Systems ◽  
Zero Voltage Switching ◽  
Lumped Parameter ◽  
Capacitive Element ◽  
Zero Voltage

Switched Inertance Hydraulic Systems (SIHS) use inductive, capacitive, and switching elements to boost or buck a pressure from a source to a load in an ideally lossless manner. Real SIHS circuits suffer a variety of energy losses, with throttling of flow during transitions of the high-speed valve resulting in 44% of overall losses. These throttling energy losses can be mitigated by applying the analog of zero-voltage-switching, a soft switching strategy, adopted from power electronics. In the soft switching circuit, the flow that would otherwise be throttled across the transitioning valve is stored in a capacitive element and bypassed through check valves in parallel with the switching valves. To evaluate the effectiveness of soft switching in a boost converter SIHS, a lumped parameter model was constructed. The model demonstrates that soft switching can improve the efficiency of the circuit up to 42% and extend the power delivery capabilities of the circuit by 76%.

Soft Switching in Switched Inertance Hydraulic Circuits

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Alexander C. Yudell ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Peak Load ◽  
Soft Switching ◽  
Power Delivery ◽  
Lumped Parameter Model ◽  
Energy Losses ◽  
Hydraulic Systems ◽  
Zero Voltage Switching ◽  
Lumped Parameter ◽  
Capacitive Element

Switched inertance hydraulic systems (SIHS) use inductive, capacitive, and switching elements to boost or “buck” (reduce) a pressure from a source to a load in an ideally lossless manner. Real SIHS circuits suffer a variety of energy losses, with throttling of flow during transitions of the high-speed valve resulting in as much as 44% of overall losses. These throttling energy losses can be mitigated by applying the analog of zero-voltage-switching, a soft switching strategy, adopted from power electronics. In the soft switching circuit, the flow that would otherwise be throttled across the transitioning valve is stored in a capacitive element and bypassed through check valves in parallel with the switching valves. To evaluate the effectiveness of soft switching in a boost converter SIHS, a lumped parameter model was constructed. Simulation demonstrates that soft switching improves the efficiency of the modeled circuit by 42% at peak load power and extends the power delivery capabilities by 77%.

On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part I: Modeling and Analysis

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Computational Experiment ◽  
High Efficiency ◽  
Major Influence ◽  
Hydraulic Fluid ◽  
System Pressure ◽  
Switch Mode ◽  
Entrained Air ◽  
Hydraulic Circuits ◽  
Fluid Compressibility

Fluid compressibility has a major influence on the efficiency of switch-mode hydraulic circuits due to the release of energy stored in fluid compression during each switching cycle and the increased flow rate through the high-speed valve during transition events. Multiple models existing in the literature for fluid bulk modulus, the inverse of the compressibility, are reviewed and compared with regards to their applicability to a switch-mode circuit. In this work, a computational model is constructed of the primary energy losses in a generic switch-mode hydraulic circuit with emphasis on losses created by fluid compressibility. The model is used in a computational experiment where the system pressure, switched volume, and fraction of air entrained in the hydraulic fluid are varied through multiple levels. The computational experiments resulted in switch-mode circuit volumetric efficiencies that ranged from 51% to 95%. The dominant energy loss is due to throttling through the ports of the high-speed valve during valve transition events. The throttling losses increase with the fraction of entrained air and the volume of fluid experiencing pressure fluctuations, with a smaller overall influence seen as a result of the system pressure. The results of the computational experiment indicate that to achieve high efficiency in switch-mode hydraulic circuits, it is critical to minimize both the entrained air in the hydraulic fluid and the fluid volume between the high-speed valve and the pump, motor, or actuator. These computational results are compared with experimental results in Part II of this two part paper series.

scholarly journals INFLUENCE OF FREE-FLOW EXCIPIENTS ON FUNCTIONAL PERFORMANCE OF NOVEONAA1 IN CONTROLLED-RELEASE TABLETS

2016 ◽  
Vol 8 (9) ◽  
pp. 6
Author(s):  
RubÉn Ramos Islas ◽  
Leopoldo Villafuerte Robles
Keyword(s):  
Drug Release ◽  
High Speed ◽  
Functional Performance ◽  
Release Profile ◽  
Free Flow ◽  
Release Mechanism ◽  
Powder Flowability ◽  
Powder Flow Rate ◽  
Controlled Release Tablets ◽  
Better Than

<p><strong>Objective: </strong>The aim of this work is the assessment of an eventual improvement in flowability of free flowing excipients on formulations containing Noveon AA1 and their influence on compactibility and release profile.</p><p><strong>Methods: </strong>Mixtures containing 20% Noveon AA1 and variable proportions of metronidazole and the free flowing excipients Prosolv EasyTab and GalenIQ 720 and 721were tested in their powder flow rate and the tablets compactibility and released profiles.</p><p><strong>Results: </strong>The powder flowability obtained with GalenIQ is about 20% better than that obtained with EasyTab. However, it is lesser than that considered as acceptable for a high-speed tableting machine. EasyTab reduces the drug release up to a half along with a continuing flattening of the release profile. This is attributed to an increasing tortuosity of the drug release path as the proportion EasyTab increases. GalenIQ restricts drug release in about a third with a lesser change in the release mechanism. This is attributed to competition for the available water inside the tablet, between the hydrating Noveon AA1 and the dissolving GalenIQ. The compactibility of the metronidazole/Noveon AA1 mixtures increases after addition of EasyTab in about 3.5 N per unit percentage of the added excipient while GalenIQ does it in about 2.6 N.</p><p><strong>Conclusion: </strong>The powder flowability of mixtures of metronidazole with Noveon AA1 was not suited for direct compression after addition of 40% of the free-flow excipient. The free-flow excipients reduce the metronidazole release rate and increase its compactibility. It was not observed a different clear functioning between both types of GalenIQ.</p>

Optimal Design of Energy-Saving Induction Cooker Power Controller Based on Fuzzy Technology

2014 ◽  
Vol 678 ◽  
pp. 423-428
Author(s):  
Pin Qi Zheng ◽  
Qing Sheng Yu
Keyword(s):  
Fuzzy Control ◽  
Output Power ◽  
Power Supply ◽  
Supply Voltage ◽  
Operating Temperature ◽  
Voltage Regulation ◽  
Soft Switching ◽  
Switch Mode ◽  
Output Efficiency ◽  
Switch Voltage

Application of Soft-switching technique and fuzzy control is discussed to optimize traditional induction cooker controller. Soft-switching technique is used to improve output efficiency of induction cooker. Switch voltage regulation by fuzzy control are used to adjust output power of induction cooker. Soft-switching inverter consists of resonant DC link and LC resonant network. Resonant DC link is used to realize ZVS, and resonant network is used to eliminate harmonics. Fuzzy control based on look-up table is adopted to adjust duty cycle of switch mode regulated power supply, which changes the DC supply voltage, so that amplitude of AC signal inverted by induction cooker is changed to adjust output power of induction cooker according to the requirement, , ensuring the operating temperature aligned with the target temperature.

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.

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