【作者】 冯丽娟；

【导师】 沈建国； 张磊；

【作者基本信息】 天津大学 ， 控制工程， 2012， 硕士

【摘要】 油田近井处理所需要的大功率超声电源具有容量大、频率稳定、输出功率因数高、保护全面的特点。在实际应用中,由于储存石油的地层条件复杂,不同沉积环境下所形成的砂岩声学参数变化大,所以不同地区、不同地层的套管井所构成的声学系统差异比较大。为了有效地将井内激发的大功率超声振动能量通过套管井的井内液体、套管和水泥环送入声学参数不同的地层,套管井的声学参数需要随时测量,作业参数需要实时的调整。为满足以上需求,本文选择了数据处理功能比较强的STM32单片机作为电源系统的主控芯片。基于其精确的定时器实现PWM输出,提供IGBT工作所需的波形;用其双路A/D同时采集作业时的电流和电压波形;用数字信号处理的方法快速处理电压和电流波形的相位差及幅值比,以此为基础调节发射波形的频率,使其与套管井条件下探头的谐振频率一致,实现频率跟踪和有效激发;借助于理论模型进一步处理电压和电流波形,可得套管井条件下的声阻抗,以便监测作业过程中套管井的声阻抗变化。本文首先给出了电源系统的整体设计方案,然后根据系统的结构依次介绍了各部分的硬件电路设计及软件的实现方案。重点介绍了电源变压器的设计,通过对磁芯进行开气隙,增大了磁感应强度达到饱和时的磁场强度,使变压器能承受更大电流;通过并联磁芯,增加了磁路的有效面积,满足了大功率传输的要求。基于磁路基本定律,对相关参数进行了数学计算。并用matlab对开气隙后磁芯的磁滞回线进行了仿真。在论文的最后,给出了实验的结果。从结果可看出,IGBT的门极输出波形比较稳定;当给电源系统接上电缆和换能器后,测量可得从电源中输出的最大电流达到了94A,电压达到了565V,实际输出的电功率达到了53kW。更多还原

【Abstract】 The high-power ultrasonic power supply needed by former oil well processing near borehole zones has the characteristics of large capacity、stable frequency、high output power factor and comprehensive protect. In actual work, we find the key parameters of the system need real-time measurement and so related parameters need to be adjusted in real time due to complex formation condition. In actual work, due to complex conditions of formation which can storage oil, the acoustic parameters of sandstone in different sedimentary environment are different, so that acoustic system formed in different region and different strata has large differences. In order to send the high power ultrasonic vibration energy, which is stimulated in the well, into different strata with different acoustic parameters through the well fluids、casing and cement of the well casing, the key parameters of the system need real-time measurement and so related parameters need to be adjusted in real time.To meet these needs, the MCS STM32 is selected as the core of the system. Based on its precise timer, PWM output can be realized so as to provide waveform which makes IGBT work; Using the method of digital signal processing, MCS STM32 can automatically process the phase difference and amplitude ratio information of current and voltage waveforms, which are collected by STM32’s dual AD converter at the same time. Take this as the foundation, we can adjust the frequency of the transmitted waveform to the resonance frequency of probe. Ultimately frequency track and effective stimulation can be realized. Otherwise, with the help of the theoretical model,we can obtain the acoustic impedance in cased well from further processing of voltage and current.So that the acoustic impedance change during the actual work can be monitored.First, the overall design of the power system is introduced. Second the design of every part of the hardware is presented in turn according to the structure of the system, and the software implementation is described. Then the design process of the power transformer is demonstrated in detail. Increase the saturation magnetic flux density when the magnetic induction is saturated by opening air gap on the core,so that the transformer can withstand more current;Increase the effective area of the magnetic circuit,so that to meet the power transmission requirements. Calculate relevant parameters based on the basic law of magnetic circuit. Simulate the hysteresis loop of the core with air gap using matlab. At the end, the result is given. It shows that the output waveform of the IGBT gate is relatively stable. If connecting cable and transducer to the power system, the maximum current of the system can reach 94A and the voltage can reach 565V,so that the actual output electric power can reach 53kV.更多还原