Research On The Influence Of The PWM On The Loss In The Asynchronous Traction Motor

With the development of power electronic technology and computer control technology, the asynchronous traction motor controlled by inverter in all walks of life, especially widely used in railway. In general, the electric locomotive traction asynchronous motor works on the frequency of 50 Hz to 60 Hz, but the output voltage of the inverter usually contain much harmonic components, and under different modulation strategies, the harmonic components vary differently. These harmonic components can cause much more loss of traction motor, low efficiency. So the research of the pulse width modulation strategy on the influence of the loss of traction motor is useful for how to improve the electric locomotive converter control method.This article first introduces several harmonic calculation and harmonic development and research status of the asynchronous motor loss. And with S VPWM modulation technology as the main research object, using mathematical analysis method, it is concluded that the inverter output line voltage harmonic calculation expression, and M program edit file function of MATLAB, run the program to get harmonic distribution. Through MATLAB/Simulink modeling for inverter circuits, using FFT harmonic analysis toolbox, verify the accuracy of the calculation method for the above. On this basis, put forward two kinds of optimal modulation strategy based on SVPWM modulation, and the corresponding harmonic content is obtained by harmonic calculation. The influence of harmonic loss of asynchronous motor are introduced, emphatically elaborated several currently the main method of calculating harmonic losses in asynchronous motor and the calculation formula. Through analyzing the equivalent circuit of the theory of asynchronous motor, the equivalent circuit model of harmonic loss is determined. And based on harmonic equivalent circuit model, deduces every harmonic content as the input voltage of the formula of calculating iron loss and copper loss. Harmonic is discussed, the calculate every harmonic content is the input voltage, the formula for computing the loss of calculating every harmonic under the size of the iron loss and copper loss and the harmonic equivalent circuit simulation model was established based on MATLAB, verify the accuracy of the data. Comparative data relations, thus it is concluded that different pulse width modulation strategy of asynchronous traction motor loss.