VFD vs Soft Starter - Which One Should You Use? In motor control systems, two devices often confuse even experienced engineers: VFD (Variable Frequency Drive) and Soft Starter. Both control motor starting, but their purpose, performance and impact on the plant are completely different. 1. Soft Starter -Smooth Startup, Simple Control A soft starter reduces the inrush current during motor starting. It only helps the motor start smoothly, not control the speed. Best For Pumps Fans Compressors Conve