Answer Posted / gaurav

Ac drives ,or VVVF i.e variable voltage variable frequency
drive works on converting A.c into D.C through converter
(rectifier circuit),then storing the D.C voltage in dc bus
bar and through proper switching of the inverter circuit
(basically IGBTs)this D.C is converted into A.C of required
voltage and frequency,hence it saves power.
there is nothing like D.C VVVF. yes in case of D.C drive we
have to convert A.C into D.C and provide armature and field
voltage to the motor.conversion of A.c to D.C is through
SCRs as we require control dc output.

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