Research On Three-phase Voltage Source PWM Rectifier Under The Load With Dramatic Changes

As the development of the power semiconductor devices and the computer controlling technology, power electronics research rise to a unprecedented height. This paper do a series of studies with a focus on an extensive use of power electronic equipment — three phase voltage source PWM rectifier, especially analyse the performance under the load with dramatic changes.First, The voltage and current equations of VSR is deduced from the kirchhoff's current law and voltage law. and get the mathematical model in dq rotating coordinate by making uses of coordinate transformation.And then, considering the problem of that the nonlinearity and coupling of voltage equation causing the difficulty in regulating DC voltage, the power equation, equivalent to voltage equation, is derived with the use of mathematical transformation. Through omitting loop resistances energy and the energy consumed by charging and discharging of inductors, the simplified description of power equation is attained. The power control based on simplified description is provided, capacitive energy storage conrtol is adopted in outer loop of the system, and a current control in inner loop. Meanwhile, power compensation of DC-load is also used to control the change rate of capacitor energy storage directly. In inner loop, feedforward decoupling control method with PI regulator have been used to make the loop equivalent to a first-order inertial element. PI control is adopted in outer loop, and the PI parametric calculation method is devised with the use of algebraic analysis and root locus analysis. The whole VSR system is equivalent to a second-order system, and the simulation results show that the controller design method proposed in this paper can bring VSR to an excellent performance and the simplified description of power equation is correct. As for the acquisition of load current signal, The design method of load current observer is analyzed, and the simulation results of observer is provided.Thidly, for a typical load with dramatic changes, we analyse DC motor speed control system in detail. Including the principle of speed and current double closed-loop regulation system, controller design method, and modulation of H-bridge DC-DC converter.Finally, The united simulation of three phase voltage source PWM rectifier and DC motor speed control system is realized on MATLAB. The VSR supply power to speed control system, Command DC-motor to accelerate, reverse and stop rapidly to verify the performance of VSR under the load with dramatic changes. The simulation results show that the mutation of DC voltage is less than 5%, The Total Harmonic Distortion of AC current is less than 3%, and the Power factor is greater than 0.99. the VSR, under the load with dramatic changes, have an excellent dynamic and static performance.