| At present,the development direction of power electronic technology application is power electronics integration technology.The input series output parallel(input-series output-parallel,ISOP)inverter combination system is constructed by connecting the n standard inverter modules in series at the input side and in parallel at the output side.The system needs to achieve two objectives:power balance and redundancy control,which is suitable for high-voltage DC input and high current AC output.In this thesis,the ISOP combination system is studied and the control strategy is studied.The specific research content includes the following sections:Firstly,the basic module of the system adopts the two-level structure of high frequency isolation,the front stage is full bridge DC/DC converter,and the rear stage is full bridge DC/AC inverter.The working principle and switching mode of the two-level circuit are analyzed,which provides the control basis for the system design of the latter text.Secondly,the idea of compound control is put forward by controlling the input voltage sharing of each module and the output inductance current phase equal,the output of each module can be realized.On the basis of this,the distributed architecture is constructed,that is,the internal structure of each module is identical,all of them have their own independent input voltage sharing regulating loop,output voltage regulating loop and current inner loop.And the modules are connected through three bar buses.By deducing the transfer function of input voltage sharing regulating loop and output voltage regulating loop of ISOP inverter system,the decoupling relationship between each loop in the system is proved.So the two loops is designed separately,the proportional regulator is adopted as the controller of input voltage sharing regulating loop,and PI regulator is adopted as the controller of output voltage regulating loop.Thirdly,the control scheme of redundant operation is put forward,when a module in the system fails,the DSP control fault module exits from the system,and the standby module is put into the system.The corresponding switch control time sequence is given,thus the smooth switching between the fault module and the standby module is ensured.Fourthly,the main circuit and control circuit of ISOP inverter system are designed.The UCC3895 control chip which is adopts as the front-stage DC/DC converter control the on-off of the switch tube,in order to realize the phase-shifting Full-bridge ZVS control.And the DC/AC inverter adopts DSP TMS320F2812 as the main control chip to realize the single pole frequency doubling SPWM control.The program flow chart of the control system is given.Finally,through MATLAB/Simulink simulation software,the simulation model of two module and three module ISOP inverter system is built.And in the case of no-load,resistive half load,resistive full load and inductive full load,the simulation results show that the control method presented in this paper realizes the input voltage sharing and output current sharing of each module.The simulation has good dynamic response characteristics that the maximum error of input voltage of each module is about ±0.5 V,the maximum error of output current is about ±0.6 A,the response time is less than 0.45ms in the system input voltage mutation and load mutation,and the redundancy control process of fault module is approximately 2ms,which indicates the validity and correctness of distributed control and redundancy control. |
