The Electromagnetic Compatibility Of PWM DC Motor Controller

In recent years, the DC motor' structure and control mode have taken great ehanges. With the development of power electronics devices and Power-control technology, the PWM mode using fully controlled Power devices already becomes mainstream. At the same time, the electromagnetic interference Problems are more and more serious, it has now become the prominent obstacles of the electrical system and equipments nomal work. There is an urgent need to resolve the teehnical problem that how to make electrieal equipments normally work compatibly without the influence of interference in the common electromagnetic environment, it is the point that the purpose of we study eleetromagnetic eompatibility.Firstly, in the paper, the EMC problems are discussed theoretically. The essence and qualification of EMI are discussed. The main radiation interferences are analyzed. The restraining measures are also discussed. Analysis of the general control system of the Conducted EMI noise source and the coupling is discussed. The electromagnetic interference and EMC design of the control system are analyzed.Secondly,a control system of DC motor is designed. The PWM control principle of DC motor is introduced. The thesis is established inengineering application and specific request for speed regulating system and analyzes the working mode, eondition and existent problems concretely. By researching the function and eonfigurations of main circuit and control sections, a hardware design scheme is presented based on the CW1525A for digital system.In the paper, a PWM control system of DC motor is designed for the study. First of all ,the system which do not have EMC design is tested,the test data showed the very poor electromagnetic compatibility in the system. And then ,analyze each part of the circuit design and join the EMC design. The measures are the applications of the electromagnetic compatibility. The use of small and large capacitors in parallel wides the scope of the frequency. The system which is designed become better in the eletromagnetic compatibility. Finally, controller is tested in the same way about elelctromagnetic compatibility. The test data show a good controller for eletromagnetic compatibility.