Development Of Power Parameters Measuring Instrument

It is very important for acquiring the running state and solving the problems of the power supplying system to perform high accurate, multi-parameter, low-cost, portable, real time and stable measurement of power parameters. It is also one major subject on which the researchers have focused for many years.In the aspect of hardware design, High speed LPC2368 is adopted to serve as the main controller. LPC2368 is a general 32-bit CPU from NXP with ARM7TDMI core. High-performance 16-bit simultaneous-sampling ADC(analog to digital converter) and high precise driving operational amplifier are used to provide the resolution and accuracy levels which is needed for the measuring system. An accurate frequency-measuring circuit is also designed to fulfill the synchronous signal-sampling. The EMI of PCB is also taken into account in order to ensure the performance of the measuring system.The key algorithms used in the system application software are explained in detail in the paper. All the algorithms are based on the digital-sampling data and make full use of ARM's excellent mathematic operational capacity to realize real-time measurement.Embedded real-time operational system is the best method to implement modern complex measuring-controlling system. The application of embedded operational system can not only simplify the process of software design but also eliminate the defects of traditional software design that multi-task can not be perfectly supported and managed. The paper elaborates the characteristics of the embedded real-time kernelμC/OS-II and its porting on LPC2368. Optimization is also carried out to improveμC/OS-II performance.The LAN interface has become one standard peripheral of modern measuring-controlling instruments. 10/100Mb/s Ethernet interface which complies with the IEEE 802.3 standards is implemented in this system. The open source embedded TCP/IP stack LwIP is ported to the system successfully with the help of embedded real-time operational systemμC/OS-II. The process model and the networks communicating task designing are also discussed in the paper.