Study On The Parameter Test System Of Permanent-Magnet DC Motor With No-Coupling Method

The no-coupling test system which can test the parameters and performances of permanent-magnet DC motor is designed by the theory of virtual measure system. Software is the core department of the test system .Only dealt with the collected data of no-coupling armature current, the rotational speed and other motor parameters can be obtained. This paper is base on the research of the no-coupling test system. And the simple experiment platform is designed. It also analyses deeply on the problems of the existing system, such as the input voltage which is not the ideal step, the singleness of test type, the interferential frequency and so on.Firstly, to reduce the error of the parameter identification between the current model and the actual current, the paper analysis the differences between the current model and the actual current waveform of the step voltage input. Base on the model of the permanent magnet DC motor, the current response under the trailing edge and the ramp input are obtained. Finally the emulation and experiments are made.Secondly, the expression between the fluctuating frequency of the component and the rotational speed is corrected for the problem of the singleness of the motor type. So the uniform equation for all types of DC motor. To solve the wrong frequency problem in speed testing experiment, the paper discusses the factors of the fluctuating current, such as the effect of slot and the rotor eccentricity fault. At last it proves that the reason of the 1/2 frequency is the brush moving. So the method of limiting the frequency range is used to get the exact rotational speed.Finally, the simple test system is designed, which actualizes the collection of the motor current data and automatic identification of the parameters. The result proves the speediness and the veracity of this test system.