The Study Of The Inverter Energy Feedback Unit

This article compares the uncontrolled rectifier side and controllable frequencyconverter and dual PWM converter, so as to realize dual PWM converter has goodenergy feedback function, it can be very good to eliminate of renewable energy topower grid pollution, realize two-way flow of energy, and power factor of device hasalso been improved.For dual PWM converter, rectifier part of it play a key role in energy feedback,energy feedback unit can be parallel to the general uncontrolled rectifier side at bothends of frequency converter, also have the effect of energy feedback, so this topicresearch is the focus of the energy feedback unit.This paper analyzes the energy feedback unit in the working principle of variouswork condition, and carries on the mathematical modeling, for the convenience ofcalculation and the use, transform the mathematical model of three-phase coordinatesystem into dq mathematical model. Specific tells the story of SVPWM controltechnology, and compares the SPWM and SVPWM, and then the generation of PWMwave chose the SVPWM debug mode, and the principle of SVPWM modulation andthe realization of the general way made a concrete analysis and digital implementation.Emphatically introduced the direct current control method of energy feedbackunit, also analyzed the main factors influencing control technology, for example, thegrid side current, switch time of dead zone and dc side voltage, etc. On energyfeedback unit made a double closed loop control system is designed, and the dc sidecapacitor and the inductance of the ac system is presented.Of MATLAB/Simulink simulation platform to do some introduction, and theSVPWM implementation method, and the main circuit module, control module and soon has carried on the simulation of the circuit, and validate the final design to achievelow harmonic and high power factor rectifier and low harmonic inverter. Finally, the software part mainly SVPWM waveform design DSP internal workto produce, which also involves the coordinate transformation, such as A/Dconversion, and digital PI control, zero crossing detection made in such aspects asdesign. Hardware part designs the main circuit, including the selection of powerdevice, the design of the driving circuit, and involved in the process of the hardwareconnection of voltage and current sampling circuit design, design of synchronouscurrent, etc.Energy feedback unit is verified by the experiments not only eliminates therectification of the harmonic, also can improve the power factor, which makes thefrequency converter to realize the two-way flow of energy saving energy, at the sametime reduce the harmonic pollution to power network, make the device performance isalso improved.