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.

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.

Energy-saving design of variable-displacement bi-directional pump-controlled electrohydraulic system

2020 ◽  
pp. 095965182097389
Author(s):  
Samir Kumar Hati ◽  
Nimai Pada Mandal ◽  
Dipankar Sanyal
Keyword(s):  
Energy Saving ◽  
Absolute Error ◽  
Fast Response ◽  
Maximum Energy ◽  
Radial Clearance ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Axial Piston

Losses in control valves drag down the average overall efficiency of electrohydraulic systems to only about 22% from nearly 75% for standard pump-motor sets. For achieving higher energy efficiency in slower systems, direct pump control replacing fast-response valve control is being put in place through variable-speed motors. Despite the promise of a quicker response, displacement control of pumps has seen slower progress for exhibiting undesired oscillation with respect to the demand in some situations. Hence, a mechatronic simulation-based design is taken up here for a variable-displacement pump–controlled system directly feeding a double-acting single-rod cylinder. The most significant innovation centers on designing an axial-piston pump with an electrohydraulic compensator for bi-directional swashing. An accumulator is conceived to handle the flow difference in the two sides across the load piston. A solenoid-driven sequence valve with P control is proposed for charging the accumulator along with setting its initial gas pressure by a feedforward design. Simple proportional–integral–derivative control of the compensator valve is considered in this exploratory study. Appropriate setting of the gains and critical sizing of the compensator has been obtained through a detailed parametric study aiming low integral absolute error. A notable finding of the simulation is the achievement of the concurrent minimum integral absolute error of 3.8 mm s and the maximum energy saving of 516 kJ with respect to a fixed-displacement pump. This is predicted for the combination of the circumferential port width of 2 mm for the compensator valve and the radial clearance of 40 µm between each compensator cylinder and the paired piston.

Robust Nonlinear Control of a Novel Indexing Valve Plate Pump: Simulation Studies

2002 ◽  
Vol 124 (4) ◽  
pp. 613-616 ◽  
Author(s):  
X. Zhang ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Pressure Control ◽  
Plate Motion ◽  
Nonlinear Simulation ◽  
Response Characteristics ◽  
Model Free ◽  
Swash Plate ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Robust Adaptive ◽  
Improved Performance

A robust adaptive pressure control strategy is proposed for a novel indexing variable-displacement pump. In the proposed approach, parametric uncertainties and unmodeled dynamics are identified to the extent possible using a model free learning network and used to decouple the dynamics using physical insights derived from careful reduced order modeling. The swash plate motion control is then carefully designed to provide the desired pressure response characteristics showing improved performance with learning. The proposed control framework and designs are validated using a detailed nonlinear simulation model.

scholarly journals A Study of ZVS, ZCS and ZVZCS Techniques in Reducing the Energy Loss and Improving the Soft Switching Range

2020 ◽  
Author(s):  
Ratil H Ashique ◽  
Zainal Salam
Keyword(s):  
Energy Loss ◽  
Loss Factor ◽  
Recent Literature ◽  
Soft Switching ◽  
Low Loss ◽  
Turn On ◽  
Switching Losses ◽  
Extended Range ◽  
Simulation Results ◽  
Switch Voltage

This paper presents a comparative analysis of the ZVZCS soft switching technique with the ZVS and the ZCS counterpart. The generalization of the voltage-current crossover or the energy loss factor obtained from simulation of the prototype converter shows that the ZVZCS significantly reduces the loss and helps to improve the efficiency of the converter as compared to the ZVS or the ZCS. On the other hand, it is also found that the soft switching range of operation of the ZVS and the ZCS are largely affected by the maximum switch voltage and switch current respectively. In contrary, these factors have a negligible effect on the ZVZCS operation which results in an extended range of soft switching operation. Additionally, a detailed LTPICE simulation is performed for selected ZVS, ZCS and ZVSCS topologies from the recent literature and the switching losses in the main switches of the converters are measured. It is observed that the energy losses in the ZVZCS mode are reduced on average by approximately 26 % at turn on and 20 % at the turn off as compared to the ZVS and the ZCS. Besides, the low standard deviation in this mode confirms a stable low loss profile which renders extended soft switching range. An experimental test is also conducted by building the prototype converter to verify the simulation results. It is found that the switching losses are minimum while the converter is operated in the ZVZCS mode. Besides, the efficiency drop remains consistently low as compared to the ZVS and the ZCS in the whole operating range. Resultantly, the simulation and the experimental results are both found to be consistent.

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.

An Improved Alternative to the Three-Dimensional, Swash Plate Mechanism

1983 ◽  
Vol 105 (3) ◽  
pp. 468-470 ◽  
Author(s):  
T. E. Shoup ◽  
D. Chi
Keyword(s):  
Theoretical Analysis ◽  
Mechanism Design ◽  
Research Effort ◽  
Three Dimensional ◽  
Design Technique ◽  
Force Transmission ◽  
Swash Plate ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Crank Mechanism

This paper presents a theoretical analysis and a design technique for the use of a special type of adjustable spatial slider crank mechanism to replace the swash plate device commonly used as a variable displacement pump or compressor. This paper is an extension of a previous research effort utilizing the RSSP mechanism [7] and considers the influence of geometric proportions of a device on stroke size, velocity fluctuation, and force transmission effectiveness. The device is shown to have significant kinematic advantages over the traditional form of the swash plate mechanism. Design curves are presented and an example application is provided.

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