The Design Of Integrated Inverter Based On Induction Motor The Design Of Integrated Inverter Based On Induction Motor

According to incomplete statistics, in total industrial electricity consumption,electricity consumption of the motors accounts for about65%and the powerconsumption of the fan, pump equipment accounts for30%of the country’s totalelectricity consumption. It can save a lot of energy for using inverter control speed forwater pump load. However, most domestic manufacturers are choosing generalinverter, the existence of the "waste one’s talent on a petty job". Furthermore, theapplication environment of water pump load is quite bad, limiting the use of inverter.Asynchronous motor has the advantages of simple structure, reliable operation, lightweight, cheap price, but the disadvantages of controlling speed. With the developmentof modern power electronic technology and computer technology, the vector controlsystem with high performance has been rapid development. So that the controlperformance of AC asynchronous motor has been close to or even more than the DCmotor. Vector control system requires a speed measuring device installed in the motorused to obtain accurate motor speed to achieve high performance control. But it willnot only destroy the stability of the system, but also will increase the cost. Researchand development of sensor-less vector control solves the problem of speed measuringdevice. Based on these, this paper research the integration inverter based in inductionmotor in the pump applications.This paper briefly expounds the thesis of some classical control methods ofthree-phase induction motor, deduces and analyzes dynamic and static order bookmodel, and points out that the three-phase induction motor is a multivariable systemwith strong coupling nonlinear order. The coordinate change is the key technology ofvector control.This paper also analyzes the concrete mathematical formulas indifferent coordinates of induction motor. This paper researches and explores thesensor-less vector control system, analyzes the key part--flux observation and speed estimation. Flux observation can obtain the position information of rotor flux, which isthe key to the success of coordinate transformation, so the flux observation determinesthe success or not of the whole control system. I also verifies the sensor-less vectorcontrol system basing on the designed hardware system.This paper designs mainly from two parts: software and hardware with referenceof structure. The hardware focus on two phase current sampling circuit, bus samplingcircuit, over-current protection circuit, phase lack protection current, three-phase PWMdrive circuit. All the hardware circuits have been independently validated andcombined debugging with the hardware and software to ensure that the design of thesystem is stable and reliable. Based on hardware, the software uses the difference ofcalculated flux and flux of current model on steady-state model to compensate the backEMF for getting the true flux information. And the software joins the over-currentprotection, over temperature protection, phase lack protection to ensure the reliabilityof the systemAfter rigorous testing and analyzing the result, the integration inverter can meetthe requirements of the pump industry, can achieve very high accuracy of speed. Itsdynamic and static performance can meet the requirements.