PID Algorithm Applied in the Refrigeration of EMBCCD

Abstract

For EMBCCD (Electron Multiplying Back Illuminated CCD) which is low light level imaging device, temperature has an important effect on the imaging performance. When EMBCCD enhances signal, it also amplifies the noise of the dark current. The most effective means of cooling chip is to reduce the noise of the dark current. When the EMBCCD is in the stable environment in low temperature, the signal to noise ratio can be improved. For this problem, the article describes the PID (Proportion Integration Differentiation) control algorithm. The unit step response curve for the controlled object is obtained by absolute refrigeration. As the system unit step response curve meets the requirements of the S-shaped curve, the Ziegler-Nichols method is used and the parameter is obtained from the S-shaped curve. The deviation between the actual temperature and set temperature values according to the proportional, integral and differential linear combination to form the control volume, incremental PID control algorithm. Put the parameters into the algorithm to control the refrigeration temperature. After that, the initial control curve is gotten. By repeated testing, we can get more appropriate parameters, and the temperature can be controlled at the target temperature. And the temperature curve is in the flat, almost with no fluctuation. The corresponding PID parameters and processing strategies are gotten from the debugging process. At last, calculate PID parameters and processing strategies, and implement the PID algorithm, as well as the numerical quantification of the specific applications the basic method are obtained. The experimental results show that the algorithm can make the temperature at 10.5°Cwith error0.5°C.