High Frequent Digital Electroplate Power System Base On Soft Switching Technology

An electroplating bath is a special load, which requires the electroplating power should provide an alternative direct current with low voltage and high current. It can fulfill the requirements of different plating. Firstly, the article analyzes the development of electroplating power and the recent findings. Secondly, using the basic principles of the switch power, it makes a simple research about the plating power controlling the soft switches of single chip microcomputer and tells us the new design of a soft switch plating power which can output a capacity of 18V/1000A. Referring to a plentiful literature all over the world, it analyzes several typical power converter circuit topology, comparing the differences among them. In the end, zero-voltage and zero-current-switching PWM full-bridge converter (FB ZVZCS PWM) using two diodes in series with the lagging leg is chosen as the main circuit topology. Using 16 digits single chip microcomputer act as the main controller, it can adjust the output voltage and current.A modern power electron power component IGBT ( Insulate-Gate Bipolar Transistor) is used as the main power switch component of power converter. In the whole system, Intel 16 digits single chip microcomputer 80C196KC and EPM7128 EPLD (Erasable Programmable Logic Device) made in Altera Company are used as the controlling center. Thanks to the introduction of CPU, the digitized control of output voltage and circuit is achieved. 80C196KC control system is connected with man machine interface in terms of RS —485 communication, which can achieve system control, state showing, failure warning and so on. 80C196KC outputs a couple of PWM signals of the dead time adaptable and the phase-shifted signals. It outputs 2 pair of mutual complementation phase-shifted PWM wave whose dead-time can be adjusted through the logical calculation of EPLD. The two pair of PWM wave act as driving signals of full-bridge converter's power switches. 80C196KC samples the output voltage and current. The sampling value is compared with standard value. 80C196KC single chip microcomputer system employs digit PI controller. According to output value of PI controller, CPU controls the phase-shifted signal. EPLD controls the phase-shifted when takes over the phase-shifted signal from CPU. It can adjust the output voltage and current of the electroplating power.In the paper, MATLAB6.5 is used of simulating the main circuit and PI controller.