What is base voltage , base frequency , maximum output voltage and maximum output fre

[danishdeshmuk]

What is base voltage , base frequency , maximum output voltage and maximum output frequency ?

How to calculate these values so that i could easily parameterize the VFD ? for any type of control whether v/f control , open loop control or closed loop control/vector control etc.
thanks

 

[Besoeker]

What is base voltage , base frequency , maximum output voltage and maximum output frequency ?
How to calculate these values so that i could easily parameterize the VFD ? for any type of control whether v/f control , open loop control or closed loop control/vector control etc.

Base voltage and frequency are usually the same as your supply. Usually the VFD comes with those as default parameters. That gives you the nominal V/f ratio,
Note that the maximum output voltage is the same as the supply voltage.
Maximum rated output frequency is specified by manufacturer. Note that if you increase the frequency beyond base frequency you will get reduced torque from the motor. Operation in this region is sometimes called the constant horsepower mode.

 

[Jraef]

...
Note that the maximum output voltage is the same as the supply voltage.

Well, yes, generally it ends up that way, but there is a reason it is programmable. If, for example, you have a motor that is designed for 380V and your supply is 480V, you can program the drive to never output more than 380V to the motor even though it is capable of more.

Maximum rated output frequency is specified by manufacturer. Note that if you increase the frequency beyond base frequency you will get reduced torque from the motor. Operation in this region is sometimes called the constant horsepower mode.

Danish,
In general Besoeker is explaining to you that although these parameters seem redundant, and they are for the majority of cases so you would leave them at the factory default values (after checking them against your conditions of course), once you get deeper into the capabilities of playing with the voltages and frequencies and motor ratings, these parameters become more important. However unless you can afford to make mistakes, doing so is something that takes an experienced hand.

Many of us got the experience by making the mistakes, but please don't tell our former bosses...:jawdrop:

 

[Besoeker]

Well, yes, generally it ends up that way, but there is a reason it is programmable. If, for example, you have a motor that is designed for 380V and your supply is 480V, you can program the drive to never output more than 380V to the motor even though it is capable of more.

But never more than the input supply (for standard units).

 

[danishdeshmuk]

Base voltage and frequency are usually the same as your supply. Usually the VFD comes with those as default parameters. That gives you the nominal V/f ratio,
Note that the maximum output voltage is the same as the supply voltage.
Maximum rated output frequency is specified by manufacturer. Note that if you increase the frequency beyond base frequency you will get reduced torque from the motor. Operation in this region is sometimes called the constant horsepower mode.

It means that :

Base Voltage is 400V as the input supply voltage for 3 phase is 400v , right ?
Base Frequency is 50 Hz as the input supply frequency is 50 Hz (here), right ?

Also, Base Voltage = Maximum Output Voltage always , right ?
And is Maximum Output frequency specified by the manufacturer of motor or the manufacturer of VFD ???

thanks

 

[Besoeker]

It means that :

Base Voltage is 400V as the input supply voltage for 3 phase is 400v , right ?
Base Frequency is 50 Hz as the input supply frequency is 50 Hz (here), right ?

Also, Base Voltage = Maximum Output Voltage always , right ?

Yes to the above.

And is Maximum Output frequency specified by the manufacturer of motor or the manufacturer of VFD ???

These are two different limits. Most VFDs have a switching frequency of several kHz can operate up to a few hundred Hz fundamental output frequency.
Standard motors, at least those I've dealt with, are more limited. The fastest I run them was in a steel mill roller table application and that was at 100Hz - twice nameplate frequency.
We've done some at higher speeds for textile applications but the motors were designed for the application.


Here are the first few lines of a typical specification for variable frequency inverters that we commonly supply:

Input voltage 380 -500 Vac 3 phase
Output voltage 0 ? Uin three phase
Input frequency 45 ? 66 Hz
Output frequency 0 ? 320 Hz

This is fairly standard stuff.