Research On Bi-directional DC/DC Converter In The DC Micro-Grid

With the aggravation of world energy crisis, new energy is getting increasing popularity due to its pollution-free and renewability. DC micro-grid is also getting more attention along with the development of alternative sources and application of new technology. Bi-directional DC/DC Converter, acting as two single-direction DC converter, is operating in bi-quadrants which can alternate the power flowing direction depends on actual situations. The functions of storage system in DC micro-grid are significant, ranging from providing a short power supply, applying in energy relieving, improving power quality, and optimizing micro power supply running to enhancing economic performance. Storage battery, as an efficient, practical, green storage device, is an ideal option for short-term storage appliance. BDC values much in scientific research considering its important role played in battery charging/discharging.The content of this thesis is arranged as follows:Firstly, it mainly introduces the background, research situation of DC micro-grid and characteristics、prospect and topology of BDC. The analyses, including BDC operating mode, analysis process of flowing power, the possibility of bi-direction power flowing and method aimed at DC bias suppression, is discussed in detail. Simulation is completed via PSIM. For no dedicated simulation module in software PSIM, a dedicated phase-shift module is set up in the thesis.Digital bias-suppression method is proposed by adjusting duty ratio as well as phase-shift approach in DSP and the waveforms prove the feasibility.Hardware:1. BDC conditioning board (multiple signal conditioning circuit, filter circuit, protective circuit, serial communication circuit and man-machine interface circuit.etc.);2.BDC driving board(power board, including IGBT, MOSFET and driving circuit, voltage and current sensors,600V DC bus and power leads, transformer, inductance leads);3. A12-output Switching Power Supply with stable output;4. Minimum system based on TMS320F28335,only including circuits working for DSP, possess the characteristics of small size, generality and flexibility.Software:Programs based on TMS320F28335related to timer, I/O interrupt, SCI, PWM, phase-shift PWM, LCD are written and debugged; steady output voltage set to600V was reached by battery charge/discharge control program.