| The three-phase PWM rectifier possesses many advantages that it has stabilityoutputting DC voltage, bidirectional freely flowing energy, high inputting powerfactor, little harmonics of AC-side inputting current, and so on. Under thedevelopment of the power and electron technology, it is widely used in industrialapplications such as the DC drive system, the power system, and the energy storagesystem.In this article, the relationships among the active power, the reactive power, theAC-side input current, the grid voltage and the phase terminal voltage are proposedby analyzing the topological structure of the three-phase PWM rectifier, when it runsin rectification state, inverter state, and reactive power compensation state. Besides,the theory and approach of the space vector PWM are presented. The three usualcoordinates of the three-phase PWM rectifier are established and the forward feeddecoupling control algorithm are added into the rotary two-phase dq coordinate modelin order to eliminate the dq axis coupling terms ωL in rotary two-phase dq coordinate.The proportional coefficient and the integral coefficient of the PI regulator are gottenby analyzing the control diagram of the outer voltage loop and the inner current loop.The simulation model of the three-phase PWM rectifier which based on MATLAB isestablished and the result of the simulation model proves the validity of controlalgorithm.In order to solve the problem of startup inrush current, the causes of startupinrush current are analyzed, the theory as well as procedure including the innercurrent loop grading startup and the outer voltage loop grading startup of gradingstartup are proposed, the method of calculating key parameters are reasoned. Thesimulation model of the three-phase PWM rectifier startup which based on MATLABis established and the result of the simulation model proves that it is effective for thegrading startup control way to inhibit the startup inrush current.The experiment platform of the three-phase PWM rectifier is designed. First, thecalculating method of the filter inductance in the AC-side and the capacitance ofDC-link are given. Second, the control panel in which DSP acted as the core includingprotection circuit, power supply circuit, PWM control circuit, sampling circuit and soon are designed. At last, the DSP routine mainly includes master routine, EPWM1base timer underflow interrupt routine, external interrupt1routine, external interrupt2routine, ECAP1interrupt routine. And the flow charts of every routine arepresented and the response processes are introduced. It is proved from experimentsthat the PWM rectifier, using grading startup control way, effectively inhibits thestartup inrush current and the overshoot of the DC-link voltage. |
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