Servo Drive vs VFD – What’s your choice?

Posted on 27th Aug 2022

Servo Drives & variable frequency drive (VFD) are used in machines for driving motors and controling motion.  Both do the same thing, however, still their requirement can be different in many ways. Here Darwin Motion explain Servo drive vs VFD – What should be your choice? in easier way.

Servo Drives and Variable Frequency Drive

Conventionally, servo drives operate with lasting magnet motors and are utilized in applications, which requireexact velocity or position control.  Animportanttrait of servo systems is using feedback to attain precision and accuracy. Servo drives are proficient of fast acceleration and deceleration and can follow precise motion route whether point to point or with distinct contouring.

VFDs instead are combined with induction motors and are utilized in applications, which require velocity control.  A distinctive trait of VFD systems is controlling velocity by managing the frequency of the voltage send to the motor.  Also VFD don't utilize feedback on the motor so the speed control is open loop.  That means Variable Frequency Drive won't recompense if there's a stand or if the load varies. It results in velocity control better than servos.  Variable frequency Drive can be establishing to ramp up to a specified velocity and then drive at that similarpace for long period.

When to Pick a Servo Drive vs a Variable Frequency Drive?

In most condition the decision is completely based on the requirement of the application but the selection can turn outambiguous when both can do the work. 

In applications such as robot arms when synchronized motion is required between multiple axes, servo drives are the first choice.  Also when quick acceleration and deceleration is required, you can pick servo drive. In addition,for exact velocity control to develop a silicon ingot, or when precise sub-micrometer positioning is required for semiconductor applications, you can directly pick Servo Drive.

Variable Frequency Drives are definite choice for conveyor belts when the velocity required to be set to a firm speed.  Also for hydraulic pumps, air blowers and some electric vehicles where exact control is not required, you can directly choose VFD.

Features & Performance

Consider systems including the features that you required or exactly want.  What motion the system required for accomplishing and what features will make the last product improve or more efficient?


After narrowing down your choice based on performance, you can now compare the cost of both the drives.  Servo systems oftenprice more than VFD.  Servo motors utilize permanent magnets that add to the material and making price vs induction motors.  Moreover, the servo drives include more features, therefore the cost is high. 


Many applications of mobile depend on batteries for power as you can't plug them into the wall.  For system designer, efficacy become a main concern, when power source are batteries. Since enhancingthe efficacy permitthe machine to run long between charges thus improving the system uptime.


For minor mobile applications the component sizeis an important consideration. First smaller components make it simpler for system designers to incorporate the parts within their design. Also smaller parts weigh less that cut down the total weight of the machine.  Less weight offers better acceleration performance and long battery life.


Power is crucial for big machines.  Servo drives can be sized up to maximum hundred kilowatts, but induction drive can go beyond the megawatts.


Overall the choice between a servo drive and variable frequency drive seems to be quite straight forward.  Servo drives having benefits when comparing it to performance and features, while Variable frequency drives have benefit with cost. So, Darwin Motion – VFD & Servo Drive Manufacturer recommend choosing the drive considering all the points mentioned above.