Digital Controller Implementation Of Three-Phase Six-Switch Boost PFC Rectifiers

With the development of power electronics technology,many traditional nonlinear equipment such as rectifier and AC motor have been merged into power grid.Because of these non-linear electrical equipments,the grid voltage and current phase become synchronized,and so on,a large number of harmonic interference into the power grid,resulting in pollution of the power grid.With the development of science and technology,improving the power factor of power equipment and reducing reactive power loss have a positive impact on development of society.At present,the research of single-phase power factor correction technology has been gradually improved,but the three-phase power factor correction technology is not yet fully mature.This subject is mainly aimed at the research of the digital control strategy of the three-phase six switch PFC rectifier,and the method of comparing the theoretical modeling simulation with the actual test of the prototype is carried out.In this paper,the operational principle of the main circuit and current flow mode of the three-phase six switch PFC rectifier are analyzed in detail,and the mathematical model based on the different coordinate system is established.On this basis,the three-phase independent PI double closed loop control strategy is analyzed,and the current controller and voltage controller are designed.Because the traditional three-phase PFC control algorithm is sensitive to the changes of system parameters,it is difficult to achieve the best control performance when the parameters change.Because of this problem,we improve the original control algorithm,and propose a two order integral sliding mode adaptive control algorithm based on space vector modulation.The current loop adopts the second order integral sliding mode algorithm,and the voltage loop uses adaptive controlalgorithm,which has a strong adaptability to the parameter change.Based on the algorithm designed above,the above two methods are simulated under different conditions to verify the theoretical analysis result.Finally,based on the simulation result,a prototype system with TMS320F28069 as the main control unit,the AC input of 115 V,the DC output of 360 V and the capacity of 3.3KW are designed.On this basis,load test is carried out on the prototype,and further verify the theoretical analysis of the system.the control algorithm used by the system is three-phase independent PI double loop control algorithm..On this basis,the prototype is tested under different load conditions.The experiment proves that the control strategy designed above can achieve the requirement of three-phase power factor correction.