Research And Design Of Switching Power Converetr For Cathodic Protection

Metal electrochemical anticorrosion technique occupies an important position inapplications such as anticorrosion engineering of modern industry equipments, metalstructures, ships and port facilities. With the wide use of impressed current cathodicprotection technique, higher requirements for anticorrosive power supply, whichemploys impressed cathodic protection technique has been put forward. The progressof power electronics technology has promoted the development of switching powersupply, while the traditional anticorrosive power supply has gradually changed fromphase-controlled method which regard thyristor as the main switching devices to highfrequency switching power supply with fully controlled devices. In this thesis, thedigital controlled phase-shifted full-bridge soft switching converter with currentdoubler rectifier is applied to cathodic protection based on the application backgroundof the metal anticorrosion, which makes anticorrosive power supply volume smallerand more efficient.This thesis firstly introduces the research background and the significance of theswitching power supply for cathodic protection, expounds the working principle ofcathodic protection, the research status and development direction of the switchingpower supply for cathodic protection, analyzes the working status in each switchingmode about the phase-shifted full-bridge ZVS with CDR in detail, and comparesdifferences in how to realize ZVS between the lead MOSFETs and the lag MOSFETs.Secondly a novel small signal modeling method is used to establish the small signalmodel for phase-shifted full-bridge ZVS converter with CDR. Then the hardwarecircuit is designed in detail, including main power circuit (high frequency transformer,main power switching devices, output rectifier diodes, output filter inductor andblocking capacitor), driving circuit, signal processing circuit and auxiliary powersupply. Meanwhile, parameters are carefully calculated. In addition, simulationsbased on PSPICE of the main power circuit are demonstrated to verify the circuitdesign. Moreover, the theory of zero-pole compensation is applied to design thecompensator. According to the designed compensator, Bode diagrams of the systemcan be drawn and analyzed using MATLAB to see whether the static and dynamicperformance can meet the requirements or not. Finally, a500W prototype using dsPIC33FJ16GS504as the main controller is developed to verify the design, and theexperimental waveforms and analysis are also given.