低成本多用途可調式精密電子負載之研究

A Study on a Low Cost, Multiple-Usage, and Adjustable Precision Electronic Load

陳聰明(Tsorng-Ming Chen)

可調式精密電子負載 ； 電源系統負載電流值測試 ； 交換式電源 ； adjustable precision electronic load ； load current testing of power systems ； switching power supply

萬能學報

40期（2018 / 07 / 01）

121 - 126

繁體中文

本論文介紹一低成本多用途0.85安培可調式精密電子負載之研究。在研製多種電子裝置時，例如交換式電源，研究者為測試其功能是否符合設計要求，常須針對負載電流的設計要求，逐一製作可以產生符合負載電流要求的電阻網路。對某些應用而言，這些電流值準確度的要求頗高，因而需用價格每瓦約一美元的低誤差低阻值電阻器，來組成測試所需的電阻網路，才可以進行系統效能的測試。然而，反覆製作這些電阻網路，頗為費時，而且需耗用許多價格不貲的低誤差低組值電阻器。因而，研究製作此一可調式精密電子負載，頗具有實用上的價值。本裝置使用市電，經變壓、整流、濾波後，供應精密參考電壓源模組所需之電源;配合低偏壓電流的運算放大器，作為電壓隨耦器，來將精密可變電阻所供應的精準電壓，供應至低誤差的負載電阻。最後，透過此低誤差的電阻器，來供應精準的可調整的電流，作為測試電流負載之用。經以可靠的數位多用表儀器量測，與該儀表所顯示數值之間的誤差平均值為千分之二點五安培，標準差為千分之一點七，尚可符合基本的精密度要求。

This paper introduces the research on a low-cost and multiple-usage adjustable precision electronic load at 0.85 amperes. While making various kinds of electronic devices, such as a switching power supply, in order to test whether their load currents fulfill the requirements, researchers need to make different resistive networks to test them. For some applications, the precision of these currents is high, therefore high-precision resistors, whose prices are generally at one US dollar per watt, are necessary to make the resistor networks to carry out testing for the systems. However, to repetitively make these resistive networks is quite time consuming and require many pieces of high-precision resistors. As a result, the aim to make this adjustable precision electronic load is of high practical value. This device makes use of power from the power plant, after the 110 volt ac voltage being transformed, rectified and filter, the dc voltage supplies the power source for the precision reference voltage source; together with the operation amplifier of low bias current that works as a voltage follower to produce a precise voltage on the precision load resistor. Finally, through this low-tolerance resistor, a precise and adjustable current is supplied for testing the load current, By using a reliable digital multimeter to measure the data, the researcher finds that the average of the measuring difference between the data from this electronic load and those from the digital multimeter is 25/1000 and their standard deviation is 17/1000. The results basically meet the requirement of an electronic load.

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