雙閉環(huán)控制精密直流信號源的研究與設計
發(fā)布時間：2018-09-01 13:34
【摘要】：在科學研究或電子產品測試中,需要用到各種信號源,提供電壓或電流信號給被測系統(tǒng)以確定被測系統(tǒng)各項性能參數。本文有針對性地提出了一種輸出范圍在0-10V內任意可調,精度為0.01%的直流信號源設計方法,該方法以4個12位DAC疊加來實現(xiàn)高精度D/A轉換,通過單片機進行輸出控制,并利用片外24位A/D構建了反饋校正模塊,建立了一個閉環(huán)控制系統(tǒng),從而有效提高了系統(tǒng)的整體精度。該信號源在硬件上分為以下幾個模塊:電源模塊、按鍵與顯示模塊、RS232通訊模塊、基準源模塊、D/A轉換模塊、運算放大模塊、A/D轉換模塊及MCU主芯片模塊。文中詳細介紹了各模塊的工作原理及電路設計過程,為保證精度,各模塊采用線性電源供電,A/D及D/A轉換器的參考電壓均由外部具有極低溫漂的基準源提供,閉環(huán)電路由24bit ADC構建,校準數據儲存在外部32KB*8bit的EEPROM中,電路中所有運放均具有極低的失調電壓,確保輸出穩(wěn)定。軟件設計采用模塊化思路設計,使用C語言編寫,包括按鍵與顯示、A/D和D/A控制、電壓校正算法及輸出調整等。主程序設計成狀態(tài)機,分別為校驗模式,輸出模式,停止模式。校驗模式通過采樣80組數據完成校正表的建立;輸出模式主要完成用戶設定值的輸出,通過調用校正表中的數據采用增量式PID控制完成輸出調整并進行OLED顯示;停止模式下通過控制ADC通道關閉,輸出停止。經調試樣機及輸出測試,所設計的直流信號源精度達到了0.01%,性能穩(wěn)定可靠,不僅滿足了設計要求,還節(jié)約了成本,適用于一般的電路測試,也適用于其他需要高精度直流信號的場合。
[Abstract]:In scientific research or electronic product testing, it is necessary to use various signal sources to provide voltage or current signals to the system under test to determine the performance parameters of the system under test. In this paper, a design method of DC signal source with adjustable output range of 0-10V and accuracy of 0.01% is proposed. The method uses four 12-bit DAC superposition to realize high-precision D- A conversion, and the output is controlled by single chip microcomputer. The feedback correction module is constructed by using 24 bit A / D, and a closed loop control system is established, which effectively improves the overall accuracy of the system. The signal source is divided into the following modules: power supply module, key and display module RS232 communication module, reference source module D / A conversion module, operation amplifier module A / D conversion module and MCU main chip module. In this paper, the working principle and circuit design process of each module are introduced in detail. In order to ensure accuracy, the reference voltages of each module are supplied by external reference sources with extremely low temperature drift, which are supplied by the reference voltage of the A / D and D / A converters supplied by linear power supply. The closed-loop circuit is constructed by 24bit ADC and the calibration data is stored in the EEPROM of the external 32KB*8bit. All the operational amplifiers in the circuit have extremely low offset voltage to ensure the output stability. The software design is based on modularization and C language, including the control of key and display, voltage correction algorithm and output adjustment, etc. The main program is designed as a state machine, check mode, output mode, stop mode. The calibration mode completes the establishment of the calibration table by sampling 80 sets of data, the output mode mainly completes the output of the user set value, and the data in the correction table is controlled by incremental PID to complete the output adjustment and OLED display. In stop mode, the output stops by controlling the ADC channel. After debugging the prototype and testing the output, the precision of the designed DC signal source is up to 0.01, and the performance is stable and reliable, which not only meets the design requirements, but also saves the cost, and is suitable for the general circuit test. It is also suitable for other occasions where high precision DC signals are required.
【學位授予單位】：蘇州大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN792
本文編號：2217362
[Abstract]:In scientific research or electronic product testing, it is necessary to use various signal sources to provide voltage or current signals to the system under test to determine the performance parameters of the system under test. In this paper, a design method of DC signal source with adjustable output range of 0-10V and accuracy of 0.01% is proposed. The method uses four 12-bit DAC superposition to realize high-precision D- A conversion, and the output is controlled by single chip microcomputer. The feedback correction module is constructed by using 24 bit A / D, and a closed loop control system is established, which effectively improves the overall accuracy of the system. The signal source is divided into the following modules: power supply module, key and display module RS232 communication module, reference source module D / A conversion module, operation amplifier module A / D conversion module and MCU main chip module. In this paper, the working principle and circuit design process of each module are introduced in detail. In order to ensure accuracy, the reference voltages of each module are supplied by external reference sources with extremely low temperature drift, which are supplied by the reference voltage of the A / D and D / A converters supplied by linear power supply. The closed-loop circuit is constructed by 24bit ADC and the calibration data is stored in the EEPROM of the external 32KB*8bit. All the operational amplifiers in the circuit have extremely low offset voltage to ensure the output stability. The software design is based on modularization and C language, including the control of key and display, voltage correction algorithm and output adjustment, etc. The main program is designed as a state machine, check mode, output mode, stop mode. The calibration mode completes the establishment of the calibration table by sampling 80 sets of data, the output mode mainly completes the output of the user set value, and the data in the correction table is controlled by incremental PID to complete the output adjustment and OLED display. In stop mode, the output stops by controlling the ADC channel. After debugging the prototype and testing the output, the precision of the designed DC signal source is up to 0.01, and the performance is stable and reliable, which not only meets the design requirements, but also saves the cost, and is suitable for the general circuit test. It is also suitable for other occasions where high precision DC signals are required.
【學位授予單位】：蘇州大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN792
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