Design Of Dry Resistor Load Test System For Diesel Locomotive And Research On Its Experiment

The purpose of locomotive load test is to examine and adjust the capability of locomotive more in its non-driving state, and it is an important standard and means to estimate the quality of repairing locomotive in railway locomotive depot. There are two means of load test at present. One is the water-resistor load, and the other is the dry resistor-load. Because the dry resistor-load does not pollute the environment and need area less, its developing foreground is immense. Therefore, there are some handicap such as the regulation and control of load, the control of the speed of motor with air-blower, the degree of automation and so on existed in original locomotive dry resistor-load test system, which restrict it to be applied. To upgrade the original locomotive resistor-load test system in Jiang'an Locomotive Depot, this dissertation mainly studies the application of high-power semiconductor IGBT to locomotive load test system, and designs a new type locomotive load test system. All tasks having be finished are briefly shown below:1. The problem that how to turn on or turn off the large current in dry resistor-load test system is studied. According to the characteristic of IGBT, we study the problem of current balance on the condition of several IGBTs in paralleling and the technique of protection and driving circuit of IGBT.2.Based on the request and characteristic of all types of locomotives constant power load test, the form of resistor connection is studied to be adapted locomotive load test including type of DF₇A, DF₇B, DF₇C, DF4A and DF₄B. and the realization of how to adjust the current continuously is studied.3. In the case of the voltage largely fluctuating, the technique of speed of direct current motor with air-blower running with constant current is studied. According to the technics of locomotives constant power load test. The technique of computer measurement and control which is applied to locomotive load test and the control algorithm of load adjustment are researched.4. According to actual work status of IGBT, the multi-IGBTs thermal resistance coupling model and the thermal radiation are researched. By the way of numerical calculation, the IGBT radiation system is analyzed theoretically, which can provide evidence for IGBT thermal protection.Based on the research, the main resulted are as flow:1. we put forward to apply IGBT as switched element for the first time. As the current of the load circuit is too large, the problem of current balance on the condition of several IGBTs in paralleling is deeply studied. And the research result is that that the positive temperature coefficient of IGBT can eliminate or restrain the occurrence of current non-balance. The protection and snubbers circuit of IGBT is designed and the parameter of the circuit has been researched according to the snubbers circuit model.2. To solve the difficulty that the current cannot be freely regulated continuously, for the first time, the model of weightier resistor network in digital circuit is applied to the locomotive dry resistor-load test system, which solve the problem of dry resistor-load test theoretically. It is proved by theory and test that the precision of dry resistor means can meet the request of locomotives constant power load test and reach the standard of water-resistor, therefore, it can serve the application of the dry resistor-load test system.3. The control technique of PWM had been applied by IGBT and PWM. In the case of the voltage largely fluctuating, we realize that the motor with fan for resistor can run with constant current, so that the motor can run safely and smoothly. The model of motor with air-blower is studied and the pulse current by PWM is calculated.4. The scheme of measurement and control by computer of dry resistor-load test is designed and introduced, and the locomotives load test bed is built. The test process can be monitored and controlled, and the data can be collected, analyzed, processed and stored. The control arithmetic, which is made up of fuzzy algorithm and binary algorithm, realizes the fast and exact regulation for load.5. On the basis of theory of fluid similarity, the relationship between surface coefficient of heat transfer and air speed. Under the computer virtual reality environment, we simulate the temperature field of the radiator, which can almost accord with experiment data. Through the temperature of the radiator, we can calculate the temperature of the node temperature, and can realize IGBT thermal protection so that system can safely work.