Regenerative braking improves the energy efficiency of railway transportation by converting kinetic energy into electric energy. This paper proposes a method to apply the Bellman-Ford (BF) algorithm to search for the train braking speed trajectory to increase the total regenerative braking energy (RBE) in a blended braking mode with both electric and mechanical braking forces available. The BF algorithm is applied in a discretized train-state model. A typical suburban train has been modeled and studied under real engineering scenarios involving changing gradients, journey time, and speed limits. It is found that the searched braking speed trajectory is able to achieve a significant increase in the RBE, in comparison with the constant-braking-rate (CBR) method with only a minor difference in the total braking time. An RBE increment rate of 17.23% has been achieved. Verification of the proposed method using BF has been performed in a simplified scenario with zero gradient and without considering the constraints of braking time and speed limits. Linear programming (LP) is applied to search for a train trajectory with the maximum RBE and achieves solutions that can be used to verify the proposed method using BF. It is found that it is possible to achieve a near-optimal solution using BF and the solution can be further improved with a more complex search space. The proposed method takes advantage of robustness and simplicity of modeling in a complex engineering scenario, in which a number of nonlinear constraints are involved.

Increasing the Regenerative Braking Energy for Railway Vehicles

The effectiveness of PTFE nanoparticle powder as an EP additive to mineral base oils

Compliant constant-force linear-motion mechanism

This paper presents a new control scheme for longitudinal collision avoidance (CA) systems to improve the safety of four-in-wheel-motor-driven electric vehicles (FIWMD-EVs). There are two major contributions in the design of longitudinal CA systems. The first contribution is a new safety distance model to make vehicle adapt to different driving roads with an adhesive coefficient between tire and road and to conform to drivers' characteristics with a driving intention parameter. The second contribution is a new braking force distribution strategy based on constrained regenerative braking strength continuity (CRBSC). By optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, the safety-brake range could be linearized to simplify the calculation of braking force distribution on the premise of ensuring braking safety. Furthermore, it is the constraint conditions that could solve the coexistence problem of positive and negative braking forces based on regenerative braking strength continuity (RBSC) to conform to actual requirements. The feasibility, effectiveness, and practicality of the proposed safety distance model and braking force distribution strategy are, respectively, verified by computer simulation experiments. Rapid control prototyping (RCP) and hardware-in-the-loop (HIL) simulation experiments using dSPACE are carried out to demonstrate the effectiveness in the control scheme, simplicity in structure, and flexibility in implementation for the proposed longitudinal CA system.

Longitudinal Collision Avoidance Control of Electric Vehicles Based on a New Safety Distance Model and Constrained-Regenerative-Braking-Strength-Continuity Braking Force Distribution Strategy

Effects of four different concentrations of nano-Cu lubrication additives on contact fatigue properties of GCr15 steel friction pairs were evaluated on a ball-rod contact fatigue tester. The anti-fatigue mechanisms of these additives were analyzed by means of scanning electron microscopy and X-ray photo electron spectroscopy. The test results and analyses show that all of these additives can raise the contact fatigue life of steel ball elements to a certain extent. The action of 10% additive is the better. It is confirmed that the main failure of the steel ball element is fatigue desquamation. The anti-fatigue mechanism of lubrication additives mainly accounts for forming a chemical reaction film on the steel rod and ball surface and decreasing in friction between the ball and rod, enhancing the ability of anti-wear.

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Effect of Nano-Cu Lubrication Additive on the Contact Fatigue Behavior of Steel

Regenerative braking system is the own system of electric and hybrid electric vehicle. The system can restore the kinetic energy and potential energy, used during start and accelerating, into battery through electrical machine. The total brake force is composed of friction brake force on front axel, friction brake force on rear axel and regenerative brake force when a vehicle equipped with regenerative braking system brakes. A control strategy, parallel regenerative brake strategy, was proposed to resolve the distribution of the three forces. The parallel regenerative brake strategy was optimized on Saturn SL1 and then simulated under urban 15 drive cycle. As a result, through optimization the parallel brake strategy is not only safe enough but also can restore the largest amount of the brake energy.

Optimization of parallel regenerative braking control strategy

In order to meet the design requirements and characters, the optimum mathematical model of a light carry truckpsilas diaphragm spring clutch is established to decrease its size as far as the engine torque is reliably transferred. The truckpsilas clutch design is optimized by MATLAB optimum toolbox. The 3-D model of the optimized results is established by Pro/E and the finite element analysis is carried out. Itpsilas proved that the design period can be shortened, the clutch size can be decreased and the production cost can be lowered.

Optimum design of automobile diaphragm spring clutch

Regenerative braking system is the characteristic system of electric and hybrid electric vehicle. The system can restore the kinetic energy and potential energy, used during start and accelerating, into battery through electrical machine. A control strategy witch is based on ideal braking force distribution is proposed. Front wheel and rear wheel can make full use of ground adhesion condition with the strategy when the vehicle brakes. More regenerative braking energy is reclaimed on the premise of ensuring braking efficiency. A simulation model is built in ADVISOR, and then put in vehicle model to simulate. The result proves that more effective braking energy is reclaimed and vehicle fuel economy is improved.

The Research of Regenerative Braking Control Strategy for Advanced Braking Force Distribution

To improve the design efficiency of robot arm,a virtual simulation system was built by making full use of the virtual simulation technology First,a three-dimensional model of the robot arm with four-freedom was built in Solidworks software;and then,the model was imported into the dynamic simulation software Adams for kinematic and dynamic simulation;At last,through the interface modular part (Adams/control)of Matlab and Adams,robot arm control system was established by using simulink module of Matlab software and coordinated simulation of four-freedom was successfully implemented The simulation results indicate that the coordinated simulation system of the robot arm has preferable dynamic re-sponse characteristics and nicer locus-tracking ability

Research on coordinated simulation of robot arm based on MATLAB and ADAMS

In a permanent magnet synchronous motor (PMSM) control system, usually, the phase voltage instruction is limited independently to prevent a three-phase pulse width modulation (PWM) wave from overflowing. This method decreases the efficiency of the bus voltage and causes voltage vector direction errors. To solve these problems, we propose a harmonic injection sinusoidal pulse-width modulation (SPWM). This method uses harmonic injected sinusoidal PWM to improve the utilisation ratio of the bus voltage, and consequently improve system performance. In this paper, we analyse the problem in terms of potential difference. The simulation results show that the proposed method can increase the utilisation ratio of the bus voltage up to 15.4%, and the voltage vector mode obtained with the proposed algorithm is larger than that obtained with the conventional one. The method with harmonic injection consequently improves current response, without affecting voltage vector accuracy. The experiment results validate the pr...

Song Bao-yu

Papers

Optimization of parallel regenerative braking control strategy

Optimum design of automobile diaphragm spring clutch

The Research of Regenerative Braking Control Strategy for Advanced Braking Force Distribution

Research on coordinated simulation of robot arm based on MATLAB and ADAMS

A harmonic injection SPWM method for the high-responsive PMSM control system