Why Choose VFD Better Than Soft Starters?

Do you have an AC motor at your workplace? Surprisingly, the motor is present in most heavy machines. As no enterprise would like to lose profit, they implement some strategies to improve their productivity. Higher profit margins, lower costs, and optimum production is their primary goal. The question is, do they really achieve this goal? Yes or no, but the production depends on the AC motor.

Minimal power wastage can significantly cover all their goals. That’s why most workplaces have variable frequency drives to control their motor power. Now, you might wonder what a variable frequency drive is? In this article, you will get all that you need to know.

Chapter 1: VFD vs. Soft Starter: Which one is best?

Variable frequency drive and soft starter both serve the same purpose. And what is that purpose in the true sense? It is to control the AC motor speed and direction. But, they are different in their controls, pricing, and many other aspects to highlight.

Internal Working Mechanism

The internal working mechanism is a prime aspect of difference. No matter the goal is identical, the internal structure determines how both are different.

In the case of VFDs, you have:

  • Rectifier— receive the AC and convert them to the DC.
  • Filter— clean the DC to make it smoother.
  • Inverter— converts the DC to AC at the required frequency to regulate the speed

That’s how exactly a VFD works relying on critical components.

In the case of soft starters, the scenario is a bit different. It comprises six thyristors or Silicon-controlled rectifiers. The following functional component is a thyristor that has three parts:

  • Logic Gate— receives internal pulse and processes it to the Anode and Cathode
  • Anode— receives pulses from Logic and transfers them to the Cathode
  • Cathode— final component to obtain the internal pulses and sends current to the motor.

The final output determines the speed changes of the AC motor.

Speed control

Speed control determines how you can speed up and down your motor. Simply put, a crucial aspect of AC motor control. So, differentiating both devices can be effective at this point.

Speed control is thousands of times better in the variable frequency drive. Variable frequency drive allows you to alter your motor speed extensively. That’s not the case with the soft starter.

Soft starter flows in the large current but doesn’t let you fix the speed to a greater extent.


While settling on the decision, you must keep the price as a factor also. As far as we discuss the price, VFDs are more expensive than soft starters. But, that is due to extensive facilities for controlling systems in the VFDs.


As per size expectations, soft starters are smaller than VFDs. Again the reason is low operational systems and less ease to regulate the system.

Which one is better for you?

To decide the better equipment, you must know several aspects of its working. Can you infer which is better from the above discussion? It doesn’t seem to be complicated. You know, why? Because the VFD provides more extensive control on your machine. You can keep your AC motor speed, direction, and frequency at the desired level.

So, I would simply recommend the Variable Frequency drive over the soft starter.

Chapter 2: Applications of the VFDs

VFDs serve several purposes related to AC motors and several industries. I would highlight the number of applications of VFD.

  • Air compressor
  • CNC machine
  • Textile Machine
  • Food machine
  • Crane
  • Pump

There are hundreds of other VFDs applications, all depending on the requirements of a given industry.

This is one of our project used for machinery in vanguard in processing high quality Calcium Carbonate and Calcium Magnesium Carbonate.

Chapter 3: How to choose your VFD device?

You have learned all about the VFDs. Can you choose a suitable VFD? Maybe not. If it is the case, no problem at all. I will help you select the VFD device for you.

Here are some factors to look for choosing your VFD.

Type of Load

There are two fundamental types of torque operating in the VFD. The first is constant torque, and the second is variable torque. So, you need to assess the situation and define the torque type for your device.

Not all devices require variable torque VFDs. And the opposite is true in either case. For example, centrifugal equipment such as a fan or pump requires variable torque. Moreover, energy savings are maximum for the variable torque.

Other devices like displacement pumps, punch presses, and extruders require constant torque.

Before choosing your ideal type of VFD, make sure it is compatible with the kind of task.

Control of Speed range

Speed range determines the significant aspects of the VFD. Usually, a VFD must not run below 20% of its speed. Otherwise, the motor will overheat. The opposite occurs when you put extra load and keep the speed maximum.

Since the primary objective is to govern the speed of the motor, check the speed range provided by your VFD. If it allows for complete flexibility to change the speed, that’s great. Choose it without a second thought.

Control System

The Control system is essential, especially if you have future objectives. Does it be controlled with the door-mounted keypad or a PLC?

For automation of the systems, PLC control can be a good opportunity. Some inexpensive devices don’t have a PLC control system. For advanced system planning, you must keep this aspect in focus while landing on your ideal VFD device.


Who wants to buy equipment at higher prices? I suppose no one has such ideas in mind. You know, why? Because everyone looks for economical options to get the best for themselves. At this point, you must know the price of your VFD.

One more thing to mention here. Never compromise on quality for the sake of price. Otherwise, it would help if you bought the equipment again and again until it fits best for your work. So, be wise to keep a balance between price and quality. Choose your VFD right away!

Chapter 4: Where to find the VFD devices in China suppliers?

USFULL can be a top choice to provide you with VFDs worldwide. We have all the solutions for your motor control system. Our products like given are a complete solution.

  • FU9000D General Type Inverter
  • FU9000MD Mini Type Inverter
  • FU9000C Air Compressor Solution
  • FU9000P Water Proof Solution
  • USFULL Control Cabinet

Hit us a message or call to get your items around the globe. We offer products in Chile, Argentina, Dominica, Malaysia, Indonesia, and so on, where there is less number of Chinese suppliers.

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