Research On Power Electrical Load Of The Motor Simulator

As a major load, motors of all kinds consume more than60percents of the powerenergy in the world. In order to improve the technical performance and economicefficiency, various power sources, such as starters-brakes and motor drives, are widely usedin industry. Traditionally, in the testing progress of the power sources, a scheme of “thetested motor power+the controlled motor+mechanical load” was usually employed.There were many disadvantages existed in it, mainly were complicacy，large energyconsumption and inflexible on characteristics simulating. In order to overcome thesedisadvantages, a method of emulating motor character using power electronic converters ispresent, called the motor simulator.The structure and principle of motor simulator was defined firstly, which consists of aSampling Unit, a Real-time motor emulator, a Power converter.The sampling Unitacquires the input voltages of the motor, which are as well the output voltages of thetested power source. The real-time motor emulator calculates exactly the real-time motorstates. The power converter is controlled to follow the reference currents calculated by thereal-time motor emulator.The dynamic mathematical model of three-phase induction motor was derived indifferent coordinate systems, and then state equations of three-phase squirrel-cage inductionmotor were built, which laid the theoretical foundation of solving motor model.Variousnumerical integration methods were analyzed, the calculation accuracy and computationunder different step were compared. Then the first-order Adams method was employed，which had the acceptable accurately and the lest operation. It provided technical solutionsfor the real-time motor emulator.The back to back PWM converters were employed. Based on the results of the motoremulator, simulator converter simulated the current characteristics of the motor. Tomaintain the DC voltage, grid converter recovered the power energy absorbed by simulatorconverter to the AC source. Simulator converter employed the single current controlscheme under αβ coordinate system. Grid converter employed double loops control schemeof hysteretic voltage loop, transient PI current loop under dq coordinate systemAn Experimental platform was build, The function of real-time motor emulator, thecontroller of Simulator converter and the controller of and Grid converter is realized in a digital control system around the DSP2812.On the experimental platform, the comparisonexperiment of the real-time motor emulator and validation experiments of motoremulator were carried out in succession. The results show that: the motor simulator canaccurately simulate the electrical characteristics of motor in various conditions, thusconfirmed the feasibility and effectiveness of the motor simulator.