Energy Regeneration Capability Research Articles

A real-time capable method for planning minimum energy trajectories for one degree-of-freedom mechatronic systems

The synthesis of optimal motion profiles has shown to be a successful and virtually inexpensive solution for enhancing energy efficiency of mechatronic systems. A typical application is the design of point-to-point motion profiles for one-degree-of-freedom mechatronic systems. This paper proposes a new method for designing minimum energy trajectories for servo-actuated systems. The problem is solved by exploiting the knowledge of the structure of the optimal solution. That allows to solve the motion design problem by solving a set of nonlinear equations and, if needed, some basic optimization procedures, formulated after some suitable continuity conditions.The herein proposed method applies to systems with and without energy regeneration capability, for maximum adaptability to most industrial applications. The method also handles jerk, acceleration, and velocity constraints, which are typical requirements in many practical applications. The number of equations and thereby the computational time depends on the number of active constraints and on whether negative power is dissipated or regenerated. Overall, the method results to be suitable for Real-Time applications, also in the most challenging case in which all the constraints are active and the system cannot regenerate negative electric power. The accuracy and the effectiveness of the planning method is tested numerically, by comparing the solution to the one obtained by a general purpose optimal control solver and then also experimentally using a lab prototype.

An electrified boom actuation system with energy regeneration capability driven by a novel electro-hydraulic unit

This paper presents a novel electrified solution for linear actuation systems, which has undergone a successful in-vehicle demonstration, marking a significant advancement in this field. Aligned with the growing trend towards electrification, this solution holds promise for a wide range of off-road applications. The showcased electro-hydraulic actuation architecture enables efficient four-quadrant operation and incorporates energy recovery capabilities. At the core of the system lies a distinctive electro-hydraulic unit, integrating a fixed hydraulic pump and a variable-speed electric motor into a compact and powerful entity. A specialized hydraulic system is designed to efficiently transform electrical energy from the electro-hydraulic unit into boom cylinder actuation. The sizing of the system is determined by the boom operation of a commercial compact loader. The maximum power output of the electro-hydraulic system is approximately 15 kW. The components of the proposed system are integrated into the reference vehicle, and comprehensive performance tests are conducted. The results of the tests performed on the vehicle with the boom lifting and lowering cycle indicate an overall system efficiency of 60%. The electrified solution consumes only about one-third of the energy used by the conventional boom actuation system on the reference machine, while exhibiting energy savings exceeding 75% during specific work phases. The energy savings come mainly from energy regeneration and minimal loss from throttling through the specialized hydraulic circuit design. The successful demonstration on the reference vehicle underscores the practicality and effectiveness of the proposed electrified solution in current mobile hydraulic applications.

A Novel Electro-Hydraulic Compound Driving System With Potential Energy Regeneration Capability for Lifting Device

In order to realize the high energy efficiency and high performance motion control of the lifting device of construction machinery, this paper proposes an electro-hydraulic compound driving system that can regenerate the potential energy. In this new system, the high-power density combination of hydraulic cylinder with accumulator is used to balance the self-weight of the lifting device and recycle the gravitational potential energy directly. The green electro-mechanical actuator with high energy efficiency and control performance is used to control the motion of the lifting device. In addition, control valves are added to dynamically adjust the pressure of the two chambers of the hydraulic cylinder and increase the stiffness of the hydraulic system, which can restrain the impact of acceleration and deceleration of large inertia lifting device and rapid charging and discharging of accumulator on electro-mechanical actuator. Finally, a typical construction machinery excavator is structurally modified to build a test platform. The test results show that, under the same working conditions, the proposed electro-hydraulic compound driving system can further reduce energy consumption by 31% and reduce peak power by 15% than that of the high energy efficiency three-chamber hydraulic cylinder driving system with potential energy regeneration. The boom runs smoothly, and the velocity overshoot and fluctuation time are significantly reduced, realizing high performance driving of the lifting device with low energy consumption. The research results also have broad application prospects in missile erection devices, cranes, presses, and other equipment.

A high-efficient solution for electro-hydraulic actuators with energy regeneration capability

This paper proposes a cost-effective, robustly practical solution for a high-efficient electro-hydraulic actuator (EHA) for linear drives. The solution addresses the challenges of high costs and limited efficiency that limit the application of EHA for the electrification of many off-road vehicles. Based on a variable-speed electric motor and a low-cost technology for a fixed-displacement pump, the proposed solution is suitable for a compact implementation and it is capable of energy regeneration under overrunning load conditions. Two different architectures—an open circuit and a closed circuit one—are considered to determine the most practical and efficient configuration as well as the control features. Both architectures minimize throttling losses associated with the conventional regulation of hydraulic actuators. Actuator velocities below the minimum and beyond the maximum allowable pump flow rate are achieved in both architectures using a proportional valve that bypasses the pump flow. The paper describes the design methodology as well as the simulation and experimental activities performed to verify the control strategies as well as energy efficiency. Considering an EHA system of about 20 kW, a complete efficiency map of the system is determined for all the possible four quadrants of operation thus including both resistive and overrunning loads, where energy recuperation is implemented. Simulation and experimental results show that the energy efficiency of the hydraulic systems can reach 84.7% in resistive phases. In assistive phases, the hydraulic system can recover up to 81.8% of the actuator energy. The comparison between open-circuit and closed-circuit structures shows the advantages of the former in terms of energy efficiency. The proposed solution is suitable for electrified hydraulic actuation systems, in both industrial and mobile applications. With the advantages of the low cost of the hydraulic unit and high energy efficiency, it is particularly suitable for mobile applications such as construction machines, that are recently experiencing a significant electrification trend.

Energy regeneration technique for electric vehicles driven by a brushless DC motor

The development of energy regeneration capability in electric vehicles can extend their driving range making them a competent alternative for conventional internal combustion engine vehicles. In this study, a novel energy regeneration technique, called a two-boost method, for electric vehicles driven by a brushless DC (BLDC) motor, a widely used motor in vehicular technology, is proposed. Based on this technique, the BLDC motor driver, which is selected to be a three-phase inverter, is converted into two simultaneous boost converters during energy regeneration periods in order to transfer energy from the BLDC motor into the battery and provide the braking force. Also, this method is compared with the single-boost method. The simulation and experimental results show that the amount of regenerated energy in this method is more than twice of that in the single-boost method. Moreover, it is observed that in the two-boost method, the motor speed changes linearly without any control of the electrical torque. In addition, since the amount of regenerated energy in this method as compared to the single-boost method is higher, the energy regeneration efficiency in this method is increased significantly.

Motor/Generator Applications in Electrified Vehicle Chassis—A Survey

Electrifying the ground vehicles is a promising approach to alleviating the energy and climate issues. The adoption of an electric vehicle (EV) and a hybrid EV (HEV) has introduced significant impacts on various aspects of vehicle design, especially on the chassis systems. When vehicles tend to be lighter, smarter, and autonomous, more electroactuators with a wide-bandwidth control and an energy-regeneration capability are deployed instead of traditional hydraulic ones to improve the vehicle dynamic and energy performance. In this article, an overview of the chassis electrification technologies regarding different configurations of electric/hybrid powertrains, active suspension, and steering systems, along with a comprehensive review of key research fields on the design and control of the discussed systems, is presented. For related technologies, the comparative discussions and design considerations serve as a reference for practical research and development. Although the electric solutions in different subsystems show great potential to further benefit the essential chassis functions, a fully electrified chassis still has a long way to go considering the technical maturity and the cost–performance tradeoff. This article also highlights the technical gaps and supplies future directions for the chassis electrification.

A novel hydraulic excavator boom driving system with high efficiency and potential energy regeneration capability

This paper proposes a new hydraulic excavator boom driving system using novel asymmetric pump to reduce energy consumption. Due to large throttling loss and gravitational potential wasting, conventional hydraulic excavator boom driving system has very low energy efficiency. This paper aims to improve the energy efficiency of the hydraulic excavator by reducing throttling loss and regenerating potential energy directly based on a novel pump controlled system. The system under consideration utilizes a novel asymmetric pump which has three ports, of which two are connected to the hydraulic cylinder, and the other one is connected to an accumulator. Thus, this system can regenerate the potential energy directly and can basically match the unequal flow rates of the single rod cylinder. The structure and working principle of the asymmetric pump controlled single rod cylinder system are studied in depth in this paper. To better demonstrate the performance of the proposed system, the popular independent metering circuit, which has been proposed to improve the efficiency of boom system, is used as a comparison. Moreover, experimental results of the two systems have been obtained based on a real 6-ton hydraulic excavator. The boom driving system of the excavator was first modified to the independent metering circuit to conduct experiment, and afterwards was modified to the proposed system. Experimental results show that, about 82.7% of the potential energy could be regenerated and reutilized by the proposed system. Compared with the independent metering circuit, the electric power consumption of the boom system during moving-up operation can be reduced by 76.1%. Furthermore, if the energy efficiency of the power source is considered, the energy consumption during the entire boom cylinder working cycle can be reduced by 75.0%. Finally, it is worth noting that the proposed system can be applied in all kinds of heavy-duty construction machineries, though only hydraulic excavator is experimented.

Pregled literature iz oblasti skladišnih sistema baziranih na šatl tehnologiji

The last decade brought the blooming of the shuttle-based automated storage and retrieval system (SBS/RS) in many industrial applications. They proved the superiority over the mini-load automated storage and retrieval system mainly due to higher throughput capacity, high flexibility of future extension, much better energy efficiency resulting from lower energy consumption and high energy regeneration capability. A comprehensive literature review on SBS/RS given in the paper pointed out main specifics and crucial approximations and assumptions of the developed system performance estimation models or control strategies, as well as the main conclusions resulting from the obtained results. Presented modeling approaches could be a valuable tool for SBS/RS designers and other related decision makers to estimate the system efficiency in the starting phase of SBS/RS design activities.

Semi-Active Vortex Induced Vibration Control of an Elastic Elliptical Cylinder with Energy Regeneration Capability

The concept of energy-regenerative damping is adopted in semi-active vortex-induced vibration (VIV) suppression of an elastically supported inclined impenetrable elliptical cylinder modeled as a two degree-of-freedom (DOF) system in laminar cross-flow at low Reynolds numbers (Re = 210). It is based on the intelligent (model free) adaptive fuzzy sliding mode control (AFSMC) strategy in conjunction with switch-based energy regenerating circuit of a tunable electromagnetic (EM) damper. The semi-active damper is linked to the plant model in a multi-field co-simulation framework via MATLAB/Simulink coupled with a user defined function in a CFD package. The AFSM controller initially calculates the desired transverse control force for suppression of the cylinder VIV. Consequently, by smart adjustment of the variable circuit load resistance, the current flow through EM damper circuit is adaptively modulated in such a way that the damping force continually tracks its active counterpart in a semi-active manner. Furthermore, when the damper is operating in the regeneration mode, the mechanical vibration energy that is traditionally dissipated as heat in conventional viscous dampers will be stored as electric charge in a capacitor. Numerical simulations demonstrate that the regenerative semi-active EM-based VIV control system can effectively suppress the cylinder motion while recovering a certain portion of mechanical vibration energy through the cooperative action of two distinct operation modes of the EM damper. Unlike conventional active control systems, the proposed system does not require a large external power supply, and at least part of the required power may be provided by the recovered energy.

Control design and fuel economy investigation of power split HEV with energy regeneration of suspension

This paper explores the impacts of active suspension with energy regeneration capability on the fuel economy of a power split Hybrid Electric Vehicle (HEV). Models of HEV powertrain and suspension are established and, based on their interactions, unified. The impacts of control parameters on the suspension performance are synthetically analyzed. The analyses form a basis for the design of suspension controller. High-level supervisory controller and low-level sub-controllers for HEV powertrain and suspension are designed. Low-level sub-controllers can ensure the performance of each system, whose control parameters are updated by the supervisory controller. The equivalent consumption minimization strategy (ECMS), superior in maintaining charge sustainability, is improved for better application in the proposed system. Simulation results under different conditions demonstrate that both HEV fuel economy and ride comfort are improved. Comparative analyses of various scenarios validate the positive effect of suspension energy regeneration on the energy conservation performance of power split HEV. Meanwhile, the improvement of HEV fuel economy can be highlighted by applying ECMS.

A Bidirectional Boost Converter With Application to a Regenerative Suspension System

This paper proposes an algorithm to control the suspension dynamics with an energy regeneration capability and high conversion efficiency. Central to the concept is the development of a switched-mode rectifier (SMR) that is capable of providing either an equivalent positive or negative damping and alternating between regenerative and motoring modes. Simulation results are presented to demonstrate power flow in regeneration and motoring modes and verify the equivalent damping characteristic and vibration energy harvesting. The studies are conducted on a small-scale proof-of-concept electromagnetic suspension system excited by emulated International Standard Organization (ISO) 8608 road profiles. An autonomous start/stop algorithm is proposed such that autonomously turns on or off the converter. This mechanism mitigates quiescent power consumption of auxiliary integrated circuits (ICs) such as gate drivers and current transducers, therefore increasing the conversion efficiency of the power electronics throughout an ISO standardized variable-speed driving cycle. The autonomous start/stop algorithm is implemented experimentally to demonstrate its feasibility under typical standardized driving cycles.

A Methodology for Optimal Design of a Vehicle Suspension System With Energy Regeneration Capability

This paper proposes a systematic methodology for predicting and optimizing the performance of an energy regenerative suspension system to efficiently capture the vibratory energy induced by the road irregularities. The method provides a graphical design guideline for the selection of stiffness and damping coefficients aimed at either best ride comfort or maximum energy harvesting. To achieve energy regeneration capability, a low-power electronic circuit capable of providing a variable load resistance is developed and fabricated. The circuit is controlled to provide an adjustable damping coefficient in the real-time. A test-bed is utilized to experimentally verify the proposed techniques. The results indicate that the analytical and simulation results concerning the optimal values for dynamic control and power regeneration match the experimental results.

Energy Harvesting and Regeneration from the Vibration of Suspension System

Two conceptual designs of energy regenerative suspension have been developed using commercial computer aided design (CAD) software. The designs are based on the available conventional suspension. They consist of basic magnet and coil for electrical energy regeneration and additional components for magnet support and coil winding circular holder. The selection of the design is based on weighted matrix which consists of reliability, cost, time consumption and weight. The score of the matrix is formulated based on relative weighted factor among the selections. All designs are fabricated using selected and available materials. The actual cost, time consumption and weight of the suspensions are compared with the theoretical weighted scores. Standard processes of cuttings, fittings and welding are performed in fabrication. Suitable magnet design is attached on the suspensions. The other moving part of the suspensions is attached by coil and coil holder. The suspensions are tested with various strokes and frequencies for feasibility studies and energy regeneration capability using suspension test rig. The evaluation of the suspensions is performed based on actual experimental results of voltage and power regenerated.