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科华蓄电池交流恒流源的设计

2018-04-17 11:17:44      点击:
成功检测科华蓄电池状态的前提是可以提供需要的交流恒流源。恒流源是能够向负载提供恒定电流的电源装置。它是一个电源内阻非常大的电源。为了保证内阻有较高的测量精度及较好的重现性,要求恒流电流源有足够的稳定度,并且波形失真度要小。这里所需交流信号幅度为40mV,频率为1KHZ。
The premise of successful detection of battery state is that it can provide the needed AC constant current source. The constant current source is a power supply that can provide a constant current to the load. It is a power supply with a very large internal resistance. To ensure that the internal resistance has high measurement accuracy and good reproducibility, constant current source is required to have enough stability and waveform distortion is small. The magnitude of the AC signal required here is 40mV and the frequency is 1KHZ.
但是传统的低频交流信号发生器设计中存在很多的不足:应用通用电路,元器件多,尤其是电容的体积大,且波形的稳定性差、失真大,调节也极不方便;应用专用电路,如ICL8038、MAX038等,其失真和稳定性方面有明显提高,但低频应用时不合适,调节不方便,成本也较高。
But there are many shortcomings in the traditional low frequency AC signal generator design: the application of general circuit, many components, especially the volume of the capacitance, and the poor stability and distortion of the waveform, and very inconvenient to adjust. The application of special circuit, such as ICL8038, MAX038 and so on, has obviously improved the distortion and stability, but it is used in low frequency. It is not suitable, the adjustment is inconvenient, the cost is also high.


3.1 设计原理
3.1 design principle


本文采用了数字式信号发生器产生标准正弦波和电流负反馈法产生精确交流恒流源法, 交流恒流源实现原理如图2所示。
In this paper, a digital signal generator is used to produce a standard sine wave and a current negative feedback method to produce an accurate AC constant current source method, and the principle of AC constant current source realization is shown in Figure 2.


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精确测量科华蓄电池内阻方法的研究
Study on the method of accurately measuring the internal resistance of the battery




电路组成框图如图2所示:这是一个闭环控制系统,电流负反馈电路。标准正弦波产生一个频率稳定、对称、失真度低的1KHz正弦波信号。驱动电路把正弦波放大,去推动功放电路,得到正弦交流电流输出。恒流控制电路从功放输出中得到的信号,通过与给定的信号相比较,来调节驱动电路的信号,从而使输出电流保持稳定。
The block diagram of the circuit is shown in Figure 2: This is a closed loop control system and a current negative feedback circuit. The standard sine wave produces a 1KHz sine wave with stable frequency, symmetry and low distortion. The driving circuit amplifies the sine wave to drive the power amplifier circuit, and obtains the sinusoidal AC current output. The signal obtained from the output of the power amplifier by the constant current control circuit, by comparing with the given signal, adjusts the signal of the driving circuit, so that the output current is kept stable.


3.2 标准正弦波的产生原理
The principle of the generation of 3.2 standard sine wave


标准正弦波信号的产生采用数字式信号发生器。首先将正弦表数据存储在如图3所示的正弦信号存储器中,晶振产生振荡频率f,经过整型电路变为完整方波频率,再经过R分频电路得到频率为f/R,再经过鉴相器FD和环路滤波器LF电路锁相分频后,读取存储在正弦信号存储器中的正弦值,经过D/A转换电路和经低通有源滤器滤波电路,生成图2 所需的标准正弦波。
The standard sine wave signal is generated by digital signal generator. First, the sinusoidal data is stored in the sinusoidal signal memory as shown in Figure 3. The oscillator produces an oscillating frequency f, after the integral circuit is transformed into a complete square wave frequency, and then the frequency is f/R through the R frequency division circuit, and then after the phase discriminator FD and the loop filter LF circuit are locked in phase, the reading stored in the sinusoidal signal memory is read. String value, through D/A conversion circuit and low-pass active filter filter circuit, generate standard sine wave required for Figure 2.