Design And Realization Of Calibrator For Speed Sensor On Locomotive

This thesis introduces a special calibrator aiming at solving the problem of calibrating speed sensor on locomotive. On the basis of Power Electronic and electric motor speed adjusting technology, the calibrator designs a speed adjusting system in which Pulse Width Modulation(PWM) controlling technology is used to control D.C. motor. Dual closed loop controlling technic is alse adopted so that the sysetem has satisfactory steady-state and dynamic characters. The system uses single chip microcomputer as an auxiliary unit which can realize the function of speed measuring together with photoelectronic speed sensor, and at the same time, can serve as an interface between calibrator and human.Insulated Gate Bipolar Transistor(IGBT) is selected as power semiconductor on-off element in the system. The important facets about IGBT's application are discussed in details , what's more, a special IGBT driving chip-M57962L is introduced here, the internal structure of it, as well as its applying circuit, are presented in this thesis.The thesis explains the principle of PWM controlling. The special integreted PWM controller-SG3525 which can help us realize PWM control easily is eleborated, this chip's internal structure and its peripheral circuit are analyzed, and its applying example in this system is given.The photoelectronic speed sensor and Hall current sensor used in the system are also introduced. As far as singel chip microcomputer is concerned, this thesis gives the designing process of the hardware and software in this specific system.Finally, thesis analyzes the steady-state and dynamic characters of the system, the result manifests that dual closed loop control apparently improves system's performance. The system has quick response, and is very stable in steady state.