| Nowadays, environmental pollution and energy crisis have become urgent problems which threaten human’s survival. After several years of burst development,the environmental pollution brought by the development of our country is dreadful to our mind. Until recent years, the government has drafted some policies of energy saving and emission-reduction. As a kind of common construction vehicle, the loader is widely used but high oil-consuming. Therefore, there exists significant meaning to research the technology to save energy and reduce emission. To make up the disadvantages, low energy usage rate and high polluting air emission of traditional loaders, the construction vehicle makers both here and abroad have launched new hybrid loaders but sold no many. Luckily, as the rapid development of new energy vehicle, the technical progress of motors and the controllers has cut off costs of hybrid loaders and provided better market prospects.Based on former research, this paper made further research on the series hybrid loader control strategy based on fuzzy controller and braking energy recovery and adopted multiple target optimal methods to optimize critical parameters, which resulted in better oil economy of the engine.Main research contents and conclusions includes:Firstly, put forward new system structural blue print of series hybrid loader based on electric drive technique. This paper analyzed the background and meaning of hybrid loader, concluded the worldwide research progress of hybrid loader and the energy-saving methods, then come up with the system structural blue print of series hybrid loader used in this paper. The blue print used electric drive system, made of a generator, a motor and several capacitors instead of torque converter and used electric actuator instead of hydraulic actuator.Secondly, built joint simulation platform of series hybrid loader energy management strategy based on fuzzy controller and braking energy recovery.According to the system structural blue print, this paper matched main components’ parameters with design needs and built joint simulation platform with AMESim andSimulink software. This platform is able to simulate braking energy recovery experiment and build control strategy models with Simulink conveniently. The control strategies improved by the simulation experiments provided reliable reference to bench tests.Thirdly, put forward series hybrid loader intelligent control strategy based on fuzzy control and braking energy recovery. Research of engine constant speed and varied speed multiple work points control strategies resulted in the come-up of best engine work point lower limit curve to restrict the engine’s work points in oil economic area. Fuzzy control method realized the smooth change of the engine’s work points and the reasonable allocation of the braking force between the motor and the brakes. Through simulation experiments, we could see clearly the influence of different control strategies to shock force of the engine, engine oil consumption and depth of discharge of the capacitor, which were used to evaluate the strategies.Fourthly, made use of improved genetic algorithm and multiple target optimization methods to optimize dynamic system parameter and intelligent control strategy parameters. This paper researched the theory of improved genetic algorithm,established multiple targets including lesser engine oil consumption, lesser super capacitor volume and the control strategy more matching with the working condition,optimized the volume of the super capacitor and fuzzy controller parameters,decreased the oil consumption and costs of the capacitor, improved the reliability of the control strategy.Fifthly, performed bench tests to the energy management control strategies.Utilized changeable hybrid loader test bench to perform traditional loader work experiment, several series hybrid energy management control strategy experiments which validated the exactness and practicality of the control strategies.The results of simulations and bench tests showed: the series hybrid loader energy management intelligent control strategy could maintain the super capacitor volt in reasonable range and provide ample electricity to electric drive system and working electric actuators; the best engine work point lower limit curve obligated enough power to hydraulic system, and through fuzzy control the torque and speed ofthe engine varied smoothly, which reduced the shock load; through controlling the engine work point in the economic area by canceling the torque converter, acquired less oil consumption; the simulation result showed that, the braking energy recovery function based on fuzzy control could reduce the engine’s oil consumption further and improve the series hybrid loader’s practicality and oil economy. |
