Design method for pump displacement non-linear controller for hub hydraulic hybrid power system

Abstract

The invention discloses a design method for a pump displacement non-linear controller for a hub hydraulic hybrid power system, and belongs to the field of hybrid vehicle control. By starting from determination for a pump displacement control target, a state-space equation of a pump displacement execution mechanism is acquired with a least squares identification method, then a steady-state controldemand meeting the pump displacement control target and reference expectation dynamic compensation are calculated respectively, the constructed non-linear dynamic feedback controller is designed by combination with the Lyapunov stability principle, and finally, a final expression form of the pump displacement non-linear controller for the hub hydraulic hybrid power system is obtained. The pump displacement non-linear controller designed with the method takes influence produced by response lag and parameter time-varying of a variable pump displacement regulating mechanism into consideration, has better robustness and resistance to external interference and is quite essential for improvement of displacement tracking control quality of the hub hydraulic hybrid power system.

Description

technical field [0001] The invention belongs to the field of hybrid vehicle control, and in particular relates to a design method for a nonlinear controller of a pump displacement of a hub hydraulic hybrid system. Background technique [0002] With the development of my country's industrialization, heavy-duty commercial vehicles have always played a pivotal role in my country's commercial vehicle field, but their uncertain working environment has high power and demand for the vehicle itself. Although the traditional all-wheel drive solution can effectively use its own gravity to obtain greater driving force, it affects the vehicle economy when the vehicle is driving on a good hard road. In-wheel hydraulic hybrid technology, with its advantages of high power density, fast charging and discharging speed, and high energy recovery efficiency, shows strong competitiveness and good application prospects on heavy-duty vehicles. It can be regarded as a comprehensive solution to the ...

AI Technical Summary

Problems solved by technology

Among them, the parameter time-varying and large-lag nonlinear response characteristics of hydraulic variable pump displacement actuators will have a great impact on the dynamic tracking quality of pump displacement, which will further complicate the coordinated control of the system. Only conventional PID control, or based on the "feedforward + feedback" control structure commonly used in engineering, often uses linear feedback and ignores the nonlinear terms of the system. It is difficult to directly apply to the hydraulic system with strong nonlinear characteristics. intrinsically nonlinear problem

[0003] In the patent "A Variable Pump Displacement Control Method for Wheel Hub Motor Hydraulic Drive System" (authorized announcement number is CN103660915B), a control method based on the combination of PI adjustment and static adjustment is announced, in which the static adjustment is based on the target gear position Look up the table to obtain the static displacement, and then use the difference between the target wheel speed and the actual wheel speed to perform PI adjustment. The method is simple and practical, but it does not consider the influence of the nonlinearity of the hydraulic system on the control quality

[0004] In the patent "A Lyapunov-Based Three-Level Three-Phase Four-Wire System SAPF Nonlinear Control Method" (publication number CN108183483A), a mathematical model based on the control object is announced. By constructing the switch function and the function that can pull the Obtaining the optimal control gain, combined with the use of Lyapunov theory to construct a nonlinear controller to improve the dynamic and static characteristics of the system, the method is theoretically strong and robust, but the system object is an electrical system, and there are few such control methods for hydraulic systems application

Images