Research And Development Of Reciprocal Power-fed Automatic Control System

Not only can the reciprocal power-fed automatic control system test both AC drive system and its components,but also can offer an experimental platform for researching on energy-saving strategy by simulating various power feedback electromechanical systems,such as power feedback pumping units and distributed energy generation.This testing system is suitable for studying on AC/DC conversion,DC/AC conversion,electromechanical energy conversion,energy-saving control and reactive power(and harmonic)compensation.Furthermore,the system consists of two sets of inverter and motor with back-to-back design.Also,it has the advantages of high energy utilization and flexible system control.Besides,united control strategy is the key to achieving reliable operation,excellent dynamic performance and high control precision.Firstly,this paper implements in-depth study on two kinds of united control schemes,including the slip frequency variable voltage variable frequency(VVVF)united control and united control scheme by combining slip-type rotor field oriented control(FOC)and direct torque control(DTC).Secondly,a main control board of TMS320F28335 is designed,and then program design and system debugging of the whole of first united control scheme and part of second one are completed.In addition,a monitoring system of host computer based on CAN bus communication is constructed,and operating parameters of the system can be set and presented directly.Adopting the first united control,the testing system has good steady-state performance,which is suitable for applications where the better dynamic performance is not necessary;by the second one,the traction motor obtains a better speed regulation and fast dynamic response under FOC,and the generator achieves excellent torque response and control accuracy under DTC.Nowadays,the testing system mainly adopts traditional hard-switching inverters.To improve efficiency of hard-switching inverters,this paper investigates a novel topology of bail-charge-transferring zero-current-switching(CT-ZCS)inverter.The optimal ZCS frequency and design guidelines of resonace parameters are indicated.Also,a reduced-order modeling method of time-charge discretization is put forward to simplify topology.Additionally,a three-level relay control with high-frequency pulse modulation(HFPM)is recommended to suppress total harmonic distoration(THD)and improve power density.Finally,CT-ZCS prototype experiment verifies the feasibility of parameter design guideines,reduced-order modeling method and three-level relay control.Through a comprehensive simulation and experiment on the testing platform,the validity of theoretical analysis and feasibility of united control schemes are certified.