Why V/F control instead of sensorless vector control ?

A: Advantages of vector control mode have over V/F control are known. Today's manufacturers provide their products with the option of sensorless vector control mode. In this case, why would one use V/F control instead of vector control ? Some say that if V/F control is adequate for your application why do you want to buy more functionality ? But my question is: why would one use V/F control if their drive has sensorless vector control capability ?

B: I often have the same question. Many drives come with V/F selected as default and the first you do after setting the basic parameters is change it to vector control.

One application I know is where you have two motors connected to the same drive. You cannot use sensor less vector in this case. Applications are on overhead cranes.

Another case may be where the cable is long or in poor shape. I have found times where an old PWM V/F drive works just fine but a new sensorless vector drive has high current problems.

C: Sensorless vector control provides extra torque at low rpm. it is almost as good as closed loop vector in this respect. There are many devices such as fans and pumps that do not need loads of torque at low speed. You must remember that in all drives voltage is free and current is what you pay for in terms of running cost so if you can reduce the start up current on a fan or a pump with V/F control then the customer will be pleased. Suggest that you investigate pump and fan output compared with speed. Both consume little power until half speed and only after that do you need to increase the torque.
Customers always like to save money.