Research And Realization Of The Control Strategy For Three-Phase AC-DC Isolated Bidirectional Converter

In the power supply and distribution system of the special vehicle,energy storage and energy transfer control is always a difficult problem.As the country vigorously promote the development of clean and environmentally friendly vehicles,which requires us to take the two-way flow of energy into consideration when design a distribution system for a vehicle.In the whole vehicle power supply and distribution system,it is important to consider the problem of limited vehicle space,high voltage environment,power density,energy density and bidirectional flow of energy.In this paper,based on the energy storage system of the special vehicle,a three-phase AC/DC converter is designed based on the DC/DC converter which has been designed and completed,which can solve the problem of the special vehicle power supply and distribution system.The main contents of this paper include the storage energy converter system condition analysis and topology selection,establish AC/DC converter mathematical model,design and Simulation of double closed loop controller based on feed forward decoupled,selection of key parameters of the system and construction of experimental platform.In the overall design of the vehicle energy storage system topology and the AC/DC converter topology selection,first of all,through access to a large number of documents to get a variety of options.After that,according to the various operating modes of the vehicle system,selection of overall structure is fully taken into account in limited vehicle space,high system reliability and so on.In the modeling process of the converter,the operation principle of the four quadrant operation of the converter and the change of the physical quantity of the circuit during the normal operation are analyzed,according to the relationship between physical variables,the mathematical model of abc three-phase static coordinate system is established.After that,the high frequency and low frequency model of the dq coordinate are established by the coordinate transformation,and the working principle of the DC/DC converter is also explained.Because there are many cross coupling terms in the AC/DC converter,it is very difficult to design the controller.In this paper,the decoupling control of active power and reactive power is realized by decoupling the dq mathematical model of the converter by using the state feedback of the current and feed-forward of grid-voltage.Then a double close loop control system is designed according to the reasonable approximate equivalent,and the simulation analysis is carried out under the DQ model and the power electronic device model respectively.At the end of this paper,the selection principle of the key parameters in the system is analyzed and the experimental platform is built.