Dear Manirul islam,
pls ckeck the output & Input voltage in drive terminal and input &output current . you see the voltage difference in input and output side.
the drive control the output voltage and output frequency to control motor flux(V/f Control)(Motor flux =motor torque).
Now you are doing simple mathmatical calculation.
VFD Input Voltage*Input current = VFD Output Voltage*output current
And you see that power of VFD input and output side is aprox. equal.