Study On The Measuring And Controlling System Of Train Friction Brake Tester Based On Frequency Variation

With the increase of train speed, it has propounded higher requirements for tribological properties of brake friction materials. While high efficiency test bench is a key element in the investigation of high-performance friction materials. The inertia friction tester is an effective experimental mode for studying fiction materials. However, inertia friction tester's structure complex and the price is high, thus it has restricted the research and development of the materials. Therefore, in the non-inertial test platform, studying on automated measuring and control system, which can measure material properties in conditions of both the constant speed friction and the inertia brake friction, it could accelerate the development pace of researching of high performance friction materials.In this paper, which based on constant speed fiction tester of the principles and methods for both hardware and software work. In the hardware aspect, various part of actuator (such as electric motor, frequency changer, sensor, signal recuperation installment, date acquisition card, etc.) selection that have been carried on and the hardware system main circuit and control circuit have been constructed. In the software aspect, the variable speed model for the train brake condition is established and VVVF technology adopted is used to propose. In addition, a personal computer(PC)-based data acquisition and control system is established by using LabVIEW, a powerful development environment for virtual instrument. It was realized with the non-inertia way to carry on tribological properties of friction materials test in conditions of both the constant speed and the inertia speed. The experimental system draws the following characteristic:(1) When the friction machine's rotational speed is 3000 r/min and the friction radius is 0.15 m, test platform simulation the highest speed of passenger train or the trailer can reach 300 km/h, and the highest speed of motor car and electric locomotive which can be simulated on this testing machine respectively is 205.16 km/h, 236.54 km/h. The test platform can simulate the passenger train to carry on the process of decelerating braking in the different operating mode. Also the variation of friction properties can be revealed in this conditions.(2) The control circuit design has reached two kinds of function requests, which respectively are the hand control and the automatic control. Moreover the hand control priority is higher than the automatic control.(3) The software system is constructed by LabVIEW, which is based on Virtual Instruments developed platform. This system has realized friction model selection, friction data acquisition, graphical display, report form preservation and data replay.(4) This system sets date calibration, which is based on the date regression principle to eliminate system error and the test system precision achieves the request. (5) Under the U/f velocity modulation pattern, the asynchronous machine physical characteristics are hard. The rotational speed precision can satisfy the system request.The testing shows that the developed friction test fully implements the design requirements with both constant speed mode and inertia speed mode. The test results reflect well the material tribology essence and it indicates this testing method is successful.