Research On VVVF Power Supply Controller Based On FPGA

Along with the development of power electronic frequency converter, the controlmethod of power electronic converter becomes more and more complex. According tothe development of microprocessor of peripheral equipment, issues due to digitalcontrol are constantly improved, and demonstrating the trend to replace analog circuitdesign. Comparing with SCM and DSP, FPGA has special advantages, the thesisanalyses theory and method of SPWM controller based on FPGA, a scheme of VVVFpower supply is achieved by FPGA, SPWM-wave generation circuit、AD samplecontrol and control methods are all focused on FPGA, the complex degree is largelyreduced.The whole thesis discussed matters that are harmonic’s production andcontrolling、control strategies、dead-time compensation、repeat control and operationalreliability of power supply, and detailed analysis、plan、simulation and experimentchecking are carried out.Firstly, VVVF’s presentation background and application are introduced, thedevelopment direction is analyzed. Digital design based on FPGA is discussed, theadvantages compared with SCM and DSP are detail explained. The power system’smajor structure is worked out as the format of AC-DC-AC, controller are planed andrealized based on FPGA.Secondly, harmonic production and the caused damage are analyzed. And theconditions when harmonic occurs in VVVF are analyzed, analyzing some suppressionmethods. Then VVVF’s control strategies are discussed. As control signals are planed,SPWM is adopted. Adopting bipolar pattern to sample, and making a comparison bynature sampling pattern to obtain final control signal, then it’s loaded into the maincircuit after handled by drive part.Lastly, because the up and down switches on a arm may be on at the same, iedirect connection. Dead time is added into the drive signals, however, harmonicincreases accordingly, therefore dead-time compensation is planed and simulated. Inorder to reduce THD, among the numerous methods, the connected method of PIDcontrol and repetitive control is adopted, the harmonic can be reduced immensely. Asthe system runs under steady state, repetitive plays main control action; But themutations occurs on voltage and load, PID plays main control action. At last thecontrol effects of control method is proved by simulation, which are perfect. Thewhole controller is planed in the interior of FPGA, the plan of supplement modules isdiscussed in the detail, and waves under simulation are introduced.