Hydraulic Regenerative Braking System Research Articles

Regenerative Braking Algorithm for Parallel Hydraulic Hybrid Vehicles Based on Fuzzy Q-Learning

The use of regenerative braking systems is an important approach for improving the travel mileage of electric vehicles, and the use of an auxiliary hydraulic braking energy recovery system can improve the efficiency of the braking energy recovery process. In this paper, we present an algorithm for optimizing the energy recovery efficiency of a hydraulic regenerative braking system (HRBS) based on fuzzy Q-Learning (FQL). First, we built a test bench, which was used to verify the accuracy of the hydraulic regenerative braking simulation model. Second, we combined the HRBS with the electric vehicle in ADVISOR. Third, we modified the regenerative braking control strategy by introducing the FQL algorithm and comparing it with a fuzzy-control-based energy recovery strategy. The simulation results showed that the power savings of the vehicle optimized by the FQL algorithm were improved by about 9.62% and 8.91% after 1015 cycles and under urban dynamometer driving schedule (UDDS) cycle conditions compared with a vehicle based on fuzzy control and the dynamic programming (DP) algorithm. The regenerative braking control strategy optimized by the fuzzy reinforcement learning method is more efficient in terms of energy recovery than the fuzzy control strategy.

A Cooperative Control Strategy for a Hydraulic Regenerative Braking System Based on Chassis Domain Control

In order to solve the problems of wheel locking and loss of vehicle control due to understeering or oversteering during the braking energy-recovery process of the hydraulic regenerative braking system (HRBS), aiming at the characteristics of chassis domain control that can realize coordinated work among various chassis systems, a cooperative control strategy of HRBS based on chassis domain control was proposed. Firstly, a HRBS test bench was built, and the accuracy of the simulation model was verified by comparing it with the test. Next, the proposed cooperative control strategy was designed, which coordinates the wheel anti-lock actuation system (WAAS) to adjust the wheel cylinder pressure to solve the wheel locking problem of HRBS in the process of braking energy recovery and coordinate the vehicle anti-loss control actuation system (VACAS) to generate a yaw compensation moment to solve the vehicle loss of the control problem of HRBS in the process of braking energy recovery by detecting the wheel slip ratio, yaw rate and sideslip angle. Finally, the established control strategy was verified through the co-simulation of Carsim and Matlab software, and the results showed that the control strategy proposed in this paper could not only avoid wheel locking and loss of vehicle control during turning braking on low-adhesion roads, but also improve the energy-recovery efficiency by 29.64% compared with a vehicle that only controls the slip ratio.

Experimental Investigation on Effects Accumulator Initial Pressure, Pump Displacement and Vehicle Speed on Regeneration Efficiency of the Hydraulic Regenerative Braking System

Recently researchers are focus on evaluation of hydraulic regenerative braking systems for improving fuel economy and reducing pollutant emissions. Present work is oriented to study effects of variation in vehicle speed at braking, accumulator initial pressure and pump displacement on regeneration efficiency of hydraulic regenerative braking system (HRBS) on the school van conveyance in Vadodara city. The results show that the HRBS regeneration efficiency improves between 1.7 to 10% with reduction in initial pressure from 110 to 90bar. Increase in pump displacement from 16 LPM to 23 LPM results in rise in regeneration efficiency of the HRBS between2.6 to 16.7%. While increasing initial speed at braking from 20 to 35 KMPH, regeneration efficiency of the HRBS system rises by 48%. This is the maximum rise in regeneration efficiency while varying the initial braking speed.

Hydraulic regenerative braking system studies based on a nonlinear dynamic model of a full vehicle

To obtain a reasonable match of the main parameters of a hydraulic regenerative braking system and to improve the energy recovery efficiency, this paper establishes the corresponding mathematical models and testbed for a hydraulic regenerative braking system. The proposed system is analysed and verified through simulation and experiments. Then, the linear and nonlinear mathematical models of a full vehicle are built, with joint simulation of the hydraulic regenerative braking system, and the influence of the hydraulic regenerative braking system on braking performance under different running conditions is discussed. The results indicate that the deviations in the simulation results between the linear and nonlinear dynamic models are very small. When the brake deceleration and road adhesion coefficient are 0.2, deviations are within 1.38 %. With an increase in the braking deceleration and road adhesion coefficient, the deviations in braking time and distance between the systems become larger and larger. When the braking deceleration and road adhesion coefficient are 0.7, the deviation reaches 30 %. Finally, with braking energy recovery efficiency and braking distance as the optimization objectives, the nonlinear braking energy recovery system parameters are optimized. After optimization, the energy recovery efficiency of the nonlinear system reaches 76.3 %, and the braking distance is 22.8 m.

Evaluation of a fuel-efficient urban delivery vehicle

A novel fuel-efficient articulated urban delivery vehicle is developed and tested. The vehicle has a path-following steering system on the semitrailer which improves its manoeuvrability in narrow city streets. This enables the payload to be increased from 39.4 m3 of freight on a conventional rigid delivery vehicle to 84.2 m3 on this articulated counterpart, leading directly to up to 33% fuel saving per unit of freight task. The vehicle is also equipped with a hydraulic regenerative braking system which stores energy in hydraulic accumulators during braking events and releases this energy back to accelerate the vehicle in subsequent motion. The design of this system and the field testing programme are described. The experimental tests are used to determine the hydraulic losses and to validate a mathematical model of the vehicle and the regenerative braking system. Finally, the validated mathematical model is used to perform a parametric study for the vehicle operating in various standard driving cycles. It is found that operating the regenerative braking system with an engine stop–start system and optimized accumulator precharge pressures can reduce the fuel consumption by 9–18% in comparison with that of the baseline vehicle, depending on the driving cycle. When combined with the performance improvements due to the trailer steering system and additional payload, this gives an overall reduction in the fuel consumption of 35–42%.

Investigation of energy efficiency for electro-hydraulic composite braking system which is based on the regenerated energy

A novel structure of the combined braking system based on the regenerative braking energy has been proposed to achieve simplified structure and energy-saving capability simultaneously, which includes the hydraulic regenerative braking system, electro-hydraulic braking system, and the power coordinate module. Theoretical contributions and managerial implications of the developed system are discussed. The corresponding mathematic models are developed, a fuzzy control method which can fulfill the power coordinate between the high-pressure and low-pressure accumulators is proposed, and the correctness of the model is verified with the utilization of the test bench. The dynamic characteristics and efficiency are further investigated in various parameters based on MATLAB/Simulink, such as the vehicle initial braking speed, the upper pressure, the liquid capacity, and the state-of-charge (SOC) of the regenerative braking accumulator. The results of the simulations which provide strong evidence for the liquid capacity and initial SOC of the regenerative braking accumulator are the key factors that affect the energy recovery efficiency, and the initial braking speed is the key point that affects the total energy. The results can provide analytical references to practical applications.

Control of a hydraulic regenerative braking system for a heavy goods vehicle

This paper investigates the fuel consumption of an articulated vehicle with a hydraulic regenerative braking system. The vehicle is a four-axle tractor–semitrailer with a volume-limited payload. It is equipped with hub-mounted hydraulic pump–motor units that pump fluid from a low-pressure reservoir to a high-pressure reservoir during braking events and generate a propulsive torque when high-pressure fluid flows through them to the low-pressure reservoir during acceleration. Several possible control strategies are proposed and simulated using a validated mathematical model of the fuel consumption of the vehicle. A global optimisation calculation indicates that the maximum possible reduction in fuel consumption due to the regenerative braking system is 11–22%, depending on the driving cycle. The simulations indicate that the simple ‘greedy’ algorithm decreases the fuel consumption by 9–17% for the same conditions. Two heuristic algorithms and a model predictive control approach were also investigated. Although these more sophisticated controllers were able to improve on the greedy controller slightly for some conditions, they may not be implementable in practice.

Experiment for a Parallel Hydraulic Hybrid Terminal Tractor

Hydraulic hybrid technology of vehicle has the potential to significantly improve fuel economy and reduce emission, and increasingly aroused the attention of the research institutions and automotive manufacturers all over the world. The main of this work is to design a parallel hydraulic hybrid system for a heavy terminal tractor. Firstly, overall scheme design, construction design, and hydraulic regenerative braking system (HRBS) for terminal tractor are designed. Furthermore, the hydraulic hybrid terminal tractor is refitted successfully. The test results show that the sample vehicle is credible and in good operation, a fuel economy improvement of the new scheme is 38.1%~61.6% more than conventional baseline. Experimental study has very important value in the hydraulic hybrid terminal tractor real application.

Design of Hybrid Electric Bus on Regenerative Braking System

In order to improve efficiency of Electro-Hydraulic regenerative braking system on electric bus, this paper will analysis dynamic performance and typical driving condition of electric bus based on ADAMS to establish electric bus simulation model and AMEsim to built hydraulic regenerative braking system simulation model. After simulation, displacement of Pump, volume and working pressure of accumulator, ratio of driving coupler will be optimized. The acceleration performance of electric bus will be enhanced obviously after applying hydraulic regenerative braking system.

Modelling of hydraulic regenerative braking systems for heavy vehicles

A hydraulic regenerative braking system for an articulated heavy vehicle is modelled for an idealised urban driving cycle, consisting of one stop and start from 30 mile/h, in a distance of 700 m. This model is used to guide specification of a hardware system but not to investigate brake blending methods or the torque distribution during braking. The specified system consists of a high-pressure accumulator and a low-pressure accumulator, connected by two fixed-displacement in-wheel pump–motors. One of these systems is fitted to each of the three trailer axles. This system can produce a fuel consumption saving of 21.7% over an idealised stop–start cycle. The same system was simulated over the Heavy Heavy-Duty Diesel Truck transient mode, New York City and Urban Driving Dynamometer Schedule legislative driving cycles, reducing fuel consumption by 11.2%, 17% and 11.7% respectively. Fuel consumption can be further reduced for all these cycles if engine stop–start technology is used. The potential to use the system when traversing hilly terrain was investigated, and the system was found to reduce fuel consumption by 12.6% over a V-shaped valley and by up to 5.3% over a realistic elevation profile.

Analysis of Hydraulic Regenerative Braking System for Electric Vehicle

In order to increase the regenerative braking energy recovery and the dynamic performance of vehicle start and acceleration in the stage of brake, the hydraulic braking energy recovery system was used with the storage battery braking energy recovery system after comparing kinds of regenerative braking recovery plan and energy storage method. The system was used to do simulation and analysis in vehicle dynamic performance and energy recovery efficiency under the PID control and ECE-15 cycle. The system simulation and analysis results show that using hydraulic regenerative braking system in pure electric vehicle can significantly improve the ability of vehicle’s start-acceleration and the increase in vehicle driving range of around 28%.

Load and Stress Analysis for the Swash Plate of an Axial Piston Pump/Motor

In an axial piston pump design, the swash plate plays an important role in controlling the displacement of the pump, especially in a closed loop system. In this paper, the axial piston pump is incorporated into the design of a hydraulic regenerative braking system for hybrid vehicles. The pump in this configuration should function in dual mode, as a pump and as a motor. For this to occur, the swash plate should swing in two opposite directions. The swash plate presented in this paper is designed for stability and ease of control. Analytical analysis of torque and forces were conducted using MATLAB software to verify the motion of the swash plate. Furthermore, finite element analysis was also carried out to evaluate the rigidity and stress in the system. The analytical evaluation has shown that as the swash plate angle increases, the required control force and torque increase almost linearly. However, the change of the plate angle was found to have no effect on the force exerted on the X-axis and the torque exerted on the Z-axis.

Design of a Mechatronic Drive Train with Regenerative Braking

Building a research framework for a Parallel Hydraulic Hybrid (PHH) Prototype with Hydraulic Regenerative Braking and Launch Assist (HRB/HLA) System for small and medium sized vehicles has been attempted. The objective of this work is to capture lost Kinetic Energy during braking and store that captured energy in a pressurized accumulator to be used again to assist accleration. The experimental implementation and validation of the Regenerative Braking System concept for light vehicles has been done using a go-kart powered by a single cylinder Honda engine to demonstrate energy savings in a real life braking scenario. A light weight test system accommodating all the Hydraulic Breaking System components mounted at the rear of the go-kart has been successfully built and tested.