Stator  Current Control Methods

The torque  and speed  of an induction motor  can be  controlled  by the  stator  current  the motor  behaviour  is different from that with VSI. A constant current for 3-? induction motor  can be obtained from 3-? current  source inverter but the use of CSI has the  disadvantage that it generates the harmonics in the system. The  circuit  of stator  current  control  methods for controlling  the speed  of induction motor  is shown in figure.

Figure shown 3- phase  controlled  rectifier  gives  controlled  dc voltage  which  converters into constant current by  using  inductor I current  source  inverter  is used to  emulate the output  frequency and therefore  speed of 3-? induction motor. Figure  shown 3-phase uncontrolled rectifier  gives  uncontrolled dc voltage  which is regulated by chopper and then it is converted to constant current  by inductor then CSI controls the  speed 3-phase  induction motor.