Design And Implementation Of Synchro-to-Digital Converter

Synchro is a kind of transducer, resembling micro controlled electric motors, which transmits electrical signals proportional to its shaft angle. It is widely used in navigation, industry and military equipments, and it can not only measure the angular position of remote mechanical devices, but also control the displacement of remote equipments. This thesis introduces a new design and implementation of synchro-to-digital Converter, which involves TMS320F240 as the core micro-controller unit.The operating principle and current digitizer study of synchro are introduced firstly, and then the existing methods of synchro-to-digital conversion are stated. After that, the design of hardware system and software system are presented in detail.The hardware system is mainly composed of sine wave source generating circuit, data acquisition and conversion circuit, TMS320F240 and its peripheral circuit, external memory circuit, 4x4 matrix keyboard circuit, LCD and serial communication circuit. The core unit of the system TMS320F240, which has powerful data-handling capacity and rich control resources, can guarantee the performance of the converter. The 14-bit, four-channel A/D converter MAX1325 is employed to sample the analog input and output voltage of the synchro and then converted them into digital.The software system is mainly implemented with C and assembly language, the subroutine modules consist of SPWM and data acquisition control and processing, LCD and keyboard control, serial communication. The CCS3.1 which is also supplied by TI can support the development, compilation and debugging of the program.This instrument has been tested on the synchro 36KF4A and the results demonstrate that the accuracy is high with the maximum absolute error of =0.01°. The man-machine interface which consists of 4x4 matrix keyboard and LCD provides a method for the real-time data fetching and instrument control, thus the function of synchro is extended. The field voltage is generated by the EVM of DSP and low-pass filter instead of the waveform generator, and the controllable frequency of it can make the instrument available for different synchros, which improves the flexibility and applicability of the system.