【作者】 孙锋；

【导师】 徐平原； 徐军明；

【作者基本信息】 杭州电子科技大学 ， 微电子学与固体电子学， 2010， 硕士

【摘要】 作为开关电源重要组成部分的脉冲变压器磁芯,其性能的优劣与开关电源的性能密切相关。与电参数测量相比,磁参数测量要复杂的多。由于生产工艺所限,目前市场上可得到的脉冲变压器磁芯性能一致性很难得到保证。困惑开关电源生产企业的磁芯一致性问题还未得到很好地解决,能够满足开关电源生产企业对磁芯筛选需求的脉冲变压器磁芯测试仪还不多见。本论文工作设计了一款能够测量脉冲变压器磁芯参数的磁性能测量系统,可用于企业对磁芯产品的筛选。论文分析了国内外动态磁性测量仪器的现状和发展趋势,从动态磁性测量的基本原理出发,阐述了脉冲变压器磁芯测试系统的设计方法。系统由交流程控励磁电源、数据采集电路、数据传输电路和上位机软件组成。交流程控励磁电源由可调信号源和高频功率放大器组成,功能是使磁芯达到饱和,其中:可调信号源采用AD9851 DDS芯片和AD8400数字电位器组成,高频功率放大器采用2SA1930/2SC5171高频中功率对管和2SA1943/2SC5200高频大功率对管组成;数据采集电路由FPGA和TLC5540高速A/D转换器组成,实现对H路和B路信号的采样及对采样数据的存储;数据传输电路由FPGA和USB微处理器组成,完成把采集到的数据传输到PC机的缓冲区;上位机软件采用LabVIEW编程,实现对采集到的数据进行处理,并通过USB微处理器输出控制信号用以控制交流程控励磁电源。根据企业对开关电源使用频率的要求,所设定的系统测试频率范围为10kHz-200kHz,输出的励磁电流范围为0.05A～4A,能够单匝测量磁芯参数,可以满足一般灯具用开关电源磁芯测试要求;系统采用数值积分代替传统的硬件积分,简化了电路,避免了硬件积分相移难以控制的缺点。所设计的系统能够快速、准确地测量出磁芯的最大磁感应强度B_m,最大磁场强度H_m,剩余磁感应强度B_r,矫顽力H_c,幅值磁导率μ_α和矩形比B_r/ B_m等磁芯参数,能够在PC机上绘制出磁滞回线。论文给出了测试过程中遇到的问题及其解决方法。系统对标准的MnZn铁氧体磁芯进行实际测试,并将测试数据与日本岩崎通讯株式会社的SY8232B-H回线测试仪的测试结果进行比对,结果表明该系统达到了预期的设计目标。更多还原

【Abstract】 As an important component of switching power supply, the performance of pulse transformer magnetic core is closely related to the one of switching power supply. Comparing with the measurement of electrical parameters, the magnetic parameter measurement is more complicated. As the limitation of technology, the pulse transformer core in current market has difficulty in consistency, which is a big problem to the manufacturers, and the pulse transformer core tester which can meet the requirements of magnetic core screening is also uncommon. In this paper, a magnetic measurement system is designed to measure the magnetic core parameters of the pulse transformer, and can be used in enterprises for the screening of magnetic core products.The paper analyzes the status quo and development trend of dynamic magnetic measurement instrument at home and abroad, which describes the design method of intelligent testing system of pulse transformer core based on the basic principle of dynamic magnetic measurement. The system consists of AC programmable excitation power, data acquisition circuit, data transmission circuit and host computer software component. AC programmable excitation power consists of the adjustable signal source and the high-frequency power amplifier, whose function is to allow core saturated. Adjustable signal source adopts AD9851 DDS chip and AD8400 digital potentiometer and high-frequency power amplifier adopts high- frequency and middle-power pair tubes 2SA1930/2SC5171 and high- frequency and high-power pair tubes 2SA1943/2SC5200. Data acquisition circuit is composed of FPGA and TLC5540 high-speed A/D converter, whose achievement is to realize signal sampling and data storage of H Road and B Road. Data transmission circuit consists of FPGA and USB microprocessor, which transfers the collected data to PC-Buffer. Host computer software is programmed with LabVIEW, which realizes the process of the collected data and through the USB microprocessor outputting controlling signals to control the AC programmable excitation power.According to the requirement of usage frequency in enterprises, the settled frequency scope of system testing is between 10kHZ to 200kHZ, and the scope of outgoing magnetizing current is between 0.05A to 4A, which can measure the magnetic core paremeters in single turn, and also meet the requirement of general lighting devices of measuring by switching power supply magnetic core.; the system adopts digital integration to replace the traditional hardware integration, not only simplifies the circuit to avoid the phase-shift of hardware integration difficult to control, but also improves the testing accuracy and speed. The designed system can test maximum magnetic induction intensity B_m, maximum magnetic field strength H_m, remnant magnetization B_r, coercive force H_c, Amplitude Permeabilityμ_αand squareness ratio B_r/B_m, and be able to draw out the hysteresis loop on the PC.The paper gives the problems of testing process and their solutions. The system tests MnZn ferrite ring, and the test results compares with the testing data of Japanese Iwasaki Corporation SY8232B-H loop tester, whose result shows that the system achieves the desired goal.更多还原