Development Of The Motor Power Quality Analyzer

With the day by day expansion of industry scale and the rapid development of science and technology, the electrification level of industrial equipments is higher and higher; the requirement on power quality is then more and more strict as well. Moreover, many new model of electric equipments bring electromagnetic interference into power network when they are running, problem of power quality is stressed day by day, on which more and more attentions are paid by both electric departments and consumers. Thus, it is quite important to measure and analyze on power quality, and exactly under this circumstance this design was put forwarded.Firstly, theoretical analysis and derivation on basic parameters of power quality were performed. The methods of measurement on all parameters were introduced based on the principles of power quality; furthermore the implementation of the parameters was also analyzed from the aspect of mathematics. Frequency measurement and harmonic analysis with their implementation with FFT algorithm were introduced in detail, from which other power quality parameters such as three-phase imbalance can be obtained.Secondly, circuit and software design of power quality analyzer was introduced in detail based on the measurement principles of power quality. The circuit is divided into two parts from logic, AD IC based analog circuit and DSP IC based control circuit. Simultaneous sampling AD converter IC was used to reduce the phase differential between all channels of signal. Programmable logic device was used to simplify the external control circuit. Digital signal processor was used as to ensure the real-time of calculation and analysis. Software synchronous sampling method was used to reduce the deviation in measurement. Bottom-up programming method was used in software design; modular design method was used from low level code of system drive to the high level code of application program. The implementations of synchronous sampling, FFT algorithm and system software structure were discussed in detail.Finally, experimental results of this three-phase power analyzer based on DSP and CPLD were analyzed, this design was proved to be correct by the results, which lay a good foundation for the further improvement of this equipment.