Unbalanced Load And Nonlinear Load, The Inverter

Carefully anatoming the reason that conventional three-phase inverter output voltage is bad for unbalanced and nonlinear loads, dissertation sum up the research of predecessor,compare so many kinds of power circuit schemes and control circuit methods, three-phase four-leg inverter and the PID controller are selected.The definition,harm,correlation standard and unbalance degree,nonlinear degree of unbalanced and nonlinear loads are analysed in detail.Basing on the compare of analog control and digital control,DSP digital controller is selected.And corrrlation configuration,principle,the DSP resource distribution of system,software realization of control scheme are analysed.According to the request of experiment production, rectifier bridge,power switch,filter circuits,drive analog circuits,DSP minimum hardware system and the join of two parts are analysed.The switch cycle average method and the rotary coordinate transformation are used to establish continuous invariable system model. According to the transfer function of the inverter, the distribution of expected poles and demand performance, the optimal parameters of the controller can be calculated.Modling all parts ofsystem on matlab software, the stabilization and dynamic performances of the four legs inverter system combined with the optimal PID controller are tested. Experiment of simulation parements is validated,and results is gotted for verifying the proposed method. This method is simple to implement and the design is convenient.