Implementation Of Battery Management Unit In MTEM System

Humans are able to predict precisely the time and location of meteor showers in the next five decades, but we can hardly know when and where the next great earthquake causing huge loss of lives would occur. Due to the objective difficulties of study of interior of the earth, humans have a much less understanding of inside the earth than that of outer space. However, the motivation to explore the interior part of the globe is the same. Deeper understanding of inside the earth would make us able to predict earthquakes and other geological disasters, which would significantly reduce casualties, and also give us great help in exploit of oil, gas, ores and other mineral deposits, which would ensure economic development and improve people’s living standards.In order to explore the interior part of the earth, many kinds of geophysical exploration methods have been invented, for example estimating subsurface structure by inversion of vibration waves, electromagnetic waves, etc. To record the surface physical information reflected by subsurface structure, sensors and data acquisition networks are needed. Deeper and more accurate estimating of subsurface structure needs higher-precision and larger amount of sensors, which means lager-scaled and more complicated data acquisition network.In order to solve the problem of central-node complexity bottleneck faced by large-scale data acquisition network, a data acquisition network of distributed-center architecture is designed, in which the central node is much less involved in all the details of the entire system, and instead it distributes the management details of bottom-level nodes to the distributed centers-middle-level nodes of the system. The central node is only in charge of highly abstracted behavior control, significantly reducing its managing pressure.This dissertation mainly presents the design and implementation of Battery Management Station (BMU), which is the distributed center of the entire system. BMU controls and summarizes the management details of Data Acquisition Units (DAU), which are the bottom-level nodes of the system, relieving managing pressure of the host computer, thus turn itself into distributed management center; undertakes tasks distributed from the host, such as time synchronization service, power supply to DAUs and independent debugging of BMU domain, etc., thus turn itself into distributed timing center, distributed power center and distributed debugging center. The design of BMU as distributed center, on one hand prevents the management complexity of the host from increasing linearly while system channel count increases, greatly reducing performance pressure of the host computer, thereby improving expansibility; on the other hand, makes BMU able to do arrangement debugging and most of normal work when it and DAUs of its domain are separated from high level stations, thus improving flexibility and robustness.At the same time, new ideas are brought out on some key aspects of BMU: dynamic adjusting of LVDS drive current offers an adaptive and lower-power solution for twisted-pair data transmission, with drive current as low as2.4%～12.3%of that of standard LVDS; one-way sync frame method for clock synchronization of DAUs has achieved sync accuracy of2μs, higher than other similar systems (for example428XL-FDU,20μs); reliable data transmission module based on hardware acknowledgement mechanism reduces CPU performance pressure of BMU greatly; remote online update of BMU CPU software and FPGA logic greatly improves debugging and maintaining convenience.The dissertation first introduces the background knowledge of geophysical exploration, and then in chapter two discusses the goal and technical specifications of the data acquisition network based on Multi-channel Transient Electromagnetic Method (MTEM). After those it presents the design of the data acquisition network, including brief introduction of distributed-center architecture, distributed management method, and the four layers of nodes of the system-Data Acquisition Unit, Battery Management Unit, Line Management Unit and Host Computer.In chapter four, detailed hardware and software implementation of BMU as distributed center is introduced. Firstly implementation of physical layer, link layer and application layer designed for reliable transmission and forwarding of data and command stream is presented. Then design and implementation of distributed management, distributed timing, distributed power supply, distributed debugging and offline storage is introduced. Finally adaptive adjusting of LVDS drive current and remote online update of CPU/FPGA is introduced as features.In the end testing and analysis for key technical specifications such as data transmission performance and clock synchronizing performance is presented in chapter five, and chapter six is the summary of the work done by myself and prospects for future research.