交直流调速系统(国外英文资料).docVIP

交直流调速系统(国外英文资料)1, variable speed control: frequency following speed frequency control mode and frequency of more than 2, the frequency control mode through the power supply frequency regulation of asynchronous motor, stepless speed regulation of asynchronous motor can be achieved? Why not?. Not only changes the normal speed, in the actual system, adjust the stator voltage is U1 in the regulation of the stator power frequency inverter at the same time, through the coordination of different types of U1 and F1 control by Eg=4.44f1N1KNI of M Te=Cm of MI ^2cos; of type 2 if you ignore the resistance voltage drop on the stator, which is about U1 of M is equal to Eg=4.44f1N1KN1, the main magnetic flux phi m=Eg/4.44f1N1KN1 approximately equal to U1/4.44f1N1KN1 through the analysis, if U1 is constant, the F1 rises, Phi m will decline, so the electromagnetic torque of Te decreased, the motor driving capacity will decrease; if the lower F1 is of M rise, so the electromagnetic torque of Te rise, rise of motor drag the ability. When the frequency at rated frequency below, will cause the main flux saturation, in which the excitation current is increased dramatically, the stator core loss increased sharply, is not allowed in these two kinds of situations in the actual operation, the actual speed often used in the process of the fundamental frequency of the frequency control mode, namely constant torque speed and frequency over the frequency control mode, namely the mechanical characteristics of constant power speed 3, the constant voltage constant frequency asynchronous motor: electromagnetic torque of asynchronous motor for Te=Pm/O1= (3p/w1) *I^2 (subscript 2* R 2/s) when U1 and W1 are constant, the electromagnetic torque of the induction motor Te=3p* (U1/w1) 2/ (sR1+R ^2=sw1R 2) ^2+s^2w1^2 (L11+L 12) ^2 when s is small, Te is approximately equal to 3P (U1/w1) ^2* (sw1/R 2) to s, which is approximately proportional to the torque and mechanical properties of S, Te=f (s) is a linea