Digital Control For Parallel DC-DC Modules Based On CAN Bus

With the rapid development of IC integration and manufacture technology, cost of digital signal processors descends and performance enhances, and DSP digital controller has been used more widely. Perfect performance is obtained when it is used in power electronics applications; therefore, digital control has become one of developing trends of power electronics.Differences between analog control and digital control are analyzed in this paper. Based on it, a modeling and simulation method by SABER software is presented, which combines analog and digital control on digital controlled power system. This simulation method embodies characteristics of digital control precisely; therefore, analysis is more effective and control parameters from simulation are more precise. Furthermore, this method can be extended to digital controlled power systems with other control algorithms, and a platform for analysis and design of digital control power systems is presented. In this paper, a simulation example of BUCK mode DC/DC converter is demonstrated using this discrete modeling and mixed analog-digital simulation method, and control parameters is obtained from simulation; rationality is validated by comparing the parameters of simulation and experiment.In this paper, an entire solution of DSP controlled power module is finished with a universal digital signal processor by Freescale company aim to fulfill power module design request, including DSP control,power circuit design and software design etc. A prototype demo is developed, and experiments on demo validate the perfect performance of the DSP controlled power module.With the development of distribution power system, parallel control of DC/DC power supplies has been a main direction of research on DC/DC converter. Digital controlled DC/DC power system is also required to achieve digital parallel control. In this paper, an intelligent master-slave current sharing scheme of digital controlled parallel DC/DC power modules is presented. In the scheme, CAN controller module on DSP is used to communication with each other, and control messages and data messages are transmitted by it. The main module is automatically determined by need, anyone being fault could quit the network without any bad effect. Two loops control is adopted in current sharing algorithm: outer current sharing loop and inner voltage loop to share output current among each module and maintain the stability of output voltage.This scheme realized current sharing control on paralleled DC/DC converter perfectly, which makes this scheme become a universal digital controlled current sharing scheme with bus competition.