基于模拟乘法器的音频数字功率设计

论文编号:JD496  论文字数:11728,页数:32   

摘      要

本文通过对目前电功率测量方法的分析，指出了目前电功率测量主要有四类方法；经过比较四类方法，发现都不能很好的对音频功率进行测量。基于电功率等于电压与电流乘积的基本原理，本文设计了音频数字功率计电路。电路由取样电路、乘积运算电路、电平转换电路、A/D转换电路和LED显示部分组成。本电路既能用于直流电功率测量，又能用于低频交流电功率测量，从直流到音频范围内都能正常工作。通过对电路测试发现不论对正弦单频信号，还是复杂波形信号、语音信号，本电路直接给出的都是负载实际消耗的有功功率，其测量误差不超过±3%。本电路简单可靠，工作频带范围宽，成本低，以有效值方式实现了对有功功率的测量。本设计弥补了目前音频功率测试复杂、精度不高和设备高昂等缺点，功率以数字方式直观显示，既方便读数，又可单独使用，还可以直接内嵌在相关设备中，实现直流到低频电功率的数字测量。通过长时间测试发现：工作时间过长时误差会加大，这是本设计的不足之处。

关键词：
音频电功率  模拟乘法器  数字功率计  设计

Abstract

Through analyzing, this paper points out four main methods which is used today to measure electrical power. By comparison, all of those methods can’t be employed to measure audio-frequency power efficiently. However, considering the basic principle that electrical power is the product of voltage and electrical current, this thesis designed a digital audio measuring circuit which is composed of sampling circuit, product operation circuit, level switching circuit, A/D circuit and LED displaying part to measure both direct current electric power and low-frequency alternating current electric power, in other words, it can work under a wide working range from direct current to audio frequency. To sine-wave single-frequency signals, complex waveform signals and speech signals, the circuit can directly carries out the active power, really consumed by the load, of which the measuring error is not more or less than 3%. This circuit, which is considered to be simple, reliable and low-cost, measures the active power in an effective way within a wild working range. This design overcomes former deficiencies such as the testing complexity, low precision and high-cost equipment. And the power is displayed in digital number which is convenient for reading. In addition, it can not only be single used, but also inner installed in the related equipments, thus it can realize the digital measurement of direct current and low-frequency power. However, one of the shortcomings of this design is that the longer it works, the larger measuring error is.

Key words:
audio-frequency electrical power; analog multiplier; digital power meter; design.

目      录

1绪论 1
1.1课题研究意义   1
1.2目前研究现状   1
1.3小结   4
2.音频数字功率计的设计   4
2.1主要设计指标   4
2.2方案论证   5
2.3总体电路设计  10
2.4电路原理图及印刷板的制作  10
2.5小结  12
3电路板焊接与调试  12
3.1电路板焊接   12
3.2单元电路调试  12
3.4实测功率   15
3.5小结   15
4结论   15
参考文献  17
致      谢   18
附录A    MC1495简介  19
附录B    LM741简介  22
附录C    ICL7107简介   24
附录D    七段LED数码管   27
附录E    电路原理图及印刷板图   28