Minimum Energy-Loss Control of Electro- and Hydro-Mechanical Modulated Convertor Drives

1981 ◽  
Vol 103 (1) ◽  
pp. 48-53 ◽  
Author(s):  
D. Karnopp
Keyword(s):  
Energy Loss ◽  
Control Strategies ◽  
Minimum Energy ◽  
Optimum Control ◽  
Good Efficiency ◽  
Hydraulic Motors ◽  
Variable Displacement ◽  
Line Pressure ◽  
Dynamic Braking ◽  
Loss Control

Most servomechanism drives optimized for speed of response are incapable of returning any of the energy stored in a reactive load to the source. Even transmissions incorporating dynamic braking are often not fully optimized with respect to energy recovery. In this paper, drives based on modulated convertors such as separately excited d.c. motors and variable-displacement hydraulic motors are studied to discover optimum control strategies for operation in all four quadrants of the torque-speed plane, i.e., for power supply and recovery. Quite different results are found for the two nominally analogous types of converters. Although several types of energy loss are not considered in the simplified mathematical models used, the effects of electrical armature resistance and hydraulic line pressure loss together with constant voltage and constant pressure accumulators indicate basically different optimum control strategies. For the types of systems studied, it is found that gyrotors such as electric motors have good efficiency for sustained high speeds while transformer systems such as hydraulic motors are relatively more efficient for transient operation near zero speed. Naturally, the absolute efficiency of a practical drive system depends on a number of additional factors not considered here.

Optimization-Based Design of a Leg Mechanism via Combined Kinematic and Structural Analysis

1994 ◽  
Author(s):  
W. B. Shieh ◽  
S. Azarm ◽  
L. W. Tsai ◽  
A. L. Tits
Keyword(s):  
Energy Loss ◽  
Degrees Of Freedom ◽  
Controller Design ◽  
Minimum Energy ◽  
Problem Formulation ◽  
Minimal Energy ◽  
Interactive Optimization ◽  
Joint Forces ◽  
Four Bar Linkage ◽  
Optimization Based Design

Abstract We study a recently proposed compound two degrees of freedom planar leg mechanism consisting of a four-bar linkage and a pantograph. In this mechanism, one degree of freedom is used for normal walking to provide an ovoid path which emulates that of humans while the other is used only when necessary to walk over obstacles. Potential advantages of such a compound mechanism are fast locomotion, minimal energy loss, simplicity in controller design, and slenderness of the leg. To exploit these to the fullest, a multiobjective optimization-based design problem formulation is proposed with the following four design objectives: (i) minimum leg height, (ii) minimum of the maximum joint forces, (iii) minimum leg mass, and (iv) minimum energy loss for a walking cycle. In addition, this problem formulation takes into account a combination of mechanism requirements and structural requirements. Several tradeoff solutions are obtained using the Consol-Optcad interactive optimization-based design package.

Energy Efficient Cam-Follower Systems

1983 ◽  
Vol 105 (4) ◽  
pp. 681-685 ◽  
Author(s):  
F. Freudenstein ◽  
M. Mayourian ◽  
E. R. Maki
Keyword(s):  
Energy Efficiency ◽  
Energy Loss ◽  
Energy Efficient ◽  
Energy Savings ◽  
Functional Dependence ◽  
Minimum Energy ◽  
Optimization Strategy ◽  
Cam Follower ◽  
Return Spring ◽  
Rating Factor

The energy loss in cam-follower systems due to friction between moving parts can be a significant contributor to the power loss in machinery. Considering the total number of cam-operated machines in manufacturing and other operations, the energy savings obtainable by improving the efficiency of the average cam-follower system by even a small percentage would be significant. In this investigation a new rating factor—an energy-loss coefficient proportional to the energy loss at the cam-follower interface—has been defined and evaluated. The rating factor relates to energy efficiency in a manner analogous to the way in which the well-known rating factors for velocity, acceleration, and shock relate to the kinematic characteristics of the cam-follower system. Two cam-follower configurations have been considered: 1) a follower motion governed by both cam and return spring, and 2) a follower positively driven by the cam. In both cases it was found that cam curves with identical rise and rise times can differ substantially in energy efficiency thereby demonstrating the significance of an energy-optimization strategy in the design of cam-follower systems. The nature of the functional dependence of the energy loss on system parameters has been identified and a minimum energy-loss limit established.

scholarly journals Optimal Control Strategy Design Based on Dynamic Programming for a Dual-Motor Coupling-Propulsion System

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Shuo Zhang ◽  
Chengning Zhang ◽  
Guangwei Han ◽  
Qinghui Wang
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Energy Loss ◽  
Control Strategy ◽  
Control Strategies ◽  
Propulsion System ◽  
Dynamic Features ◽  
Optimal Control Strategy ◽  
Control Rules ◽  
Electric Bus

A dual-motor coupling-propulsion electric bus (DMCPEB) is modeled, and its optimal control strategy is studied in this paper. The necessary dynamic features of energy loss for subsystems is modeled. Dynamic programming (DP) technique is applied to find the optimal control strategy including upshift threshold, downshift threshold, and power split ratio between the main motor and auxiliary motor. Improved control rules are extracted from the DP-based control solution, forming near-optimal control strategies. Simulation results demonstrate that a significant improvement in reducing energy loss due to the dual-motor coupling-propulsion system (DMCPS) running is realized without increasing the frequency of the mode switch.

A Study of the Internal Forces in a Variable-Displacement Vane-Pump—Part II: A Parametric Study

1986 ◽  
Vol 108 (2) ◽  
pp. 233-237 ◽  
Author(s):  
A. M. Karmel
Keyword(s):  
Parametric Study ◽  
Analytical Study ◽  
Design Criterion ◽  
Vane Pump ◽  
Continuous Components ◽  
Variable Capacity ◽  
Variable Displacement Vane Pump ◽  
Variable Displacement ◽  
Internal Forces ◽  
Line Pressure

This is the second part of an analytical study of the internal forces in a variable-displacement vane-pump. It presents a parametric study of the forces and torques applied to the mechanism and the shaft of this pump, as functions of line pressure, the eccentricity, and the design geometry. It is shown that the continuous components of the torque and of the direction of the radial shaft-load vary as a sawtooth wave at twice the vane-frequency while the magnitude of the radial shaft-load varies as a square wave at vane-frequency. The design criterion developed in the first part of this study is used to demonstrate the elimination of the magnitude variations in the radial shaft-load. The intermittent components of the internal forces vary as a pulse train at vane frequency and may produce high-peak pressure pulses which must be closely controlled. The variable-capacity feature of variable-displacement vane-pumps has a significant effect on the torque applied to the mechanism, but only a secondary effect on the overall radial shaft-load.

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.

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