VFD Control for Industrial Machines using PLC and LC Filter

Abstract

Variable frequency drive (VFD) and servo drive usage in the industrial application are increased in a large amount. The control of VFD can be done using a programmable logic controller (PLC). The apparatus includes a main controller i.e. VFD and first interface PLC. The motor controller (VFD) is coupled to the PLC and controls the electric motor according to the application. PLC is further coupled to Human Machine Interface (HMI) to show the operation visually. An input to VFD is given from the PLC to run the motor and outputs from the VFD is controlled frequencies, which control the speed and torque of a motor. Harmonics, motor bearing damage, motor noise, electromagnetic interference are observed in the pulse width modulated (PWM) VFD fed induction motor. A sinusoidal LC filter is placed between the VFD and motor to smoothen the pulse width modulated waves into sinusoidal waves, which basically reduces the noise and effectively improve the overall efficiency of VFD.