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Whining VFD
- Thread starter henrya
- Start date
- Replies 11
- Views 2,229
VFDs all whine.
It's the carrier or switching (chopping) frequency you're hearing. If you raise that, it can help to make it less annoying, but the hotter your VFD will run. Some VFDs need to be derated if you operate them at high carrier frequencies, and the ambient air temperature can come into play to further reduce the capability of it. Look in the manual for carrier frequency, and see what it says.
It's the carrier or switching (chopping) frequency you're hearing. If you raise that, it can help to make it less annoying, but the hotter your VFD will run. Some VFDs need to be derated if you operate them at high carrier frequencies, and the ambient air temperature can come into play to further reduce the capability of it. Look in the manual for carrier frequency, and see what it says.
Thanks.
That fixed it, although I don't exactly know what I did except make it stop whining. It would have been easier if the manual contained some remarks on how the settings altered the function in a way that someone not an electrical engineer could understand.
I don't think its just an anti-whine setting. <grin>
I did mess with other programming variables and improved the accel/deccel and braking. What an amazing device.
That fixed it, although I don't exactly know what I did except make it stop whining. It would have been easier if the manual contained some remarks on how the settings altered the function in a way that someone not an electrical engineer could understand.
I don't think its just an anti-whine setting. <grin>
I did mess with other programming variables and improved the accel/deccel and braking. What an amazing device.
Well, think about it like this.
The way it works is it varies the time that it's feeding current into the motor to do different things. Picture your fingers on a switch. Now the whine is how often you flip the switch. The AVERAGE ammount of juice the motor is fed is controlled by how long the switch is left on. The faster you flip the switch, the hotter the switch gets. This is a SUPER SIMPLIFIED explanation, but I think it will do.
The way it works is it varies the time that it's feeding current into the motor to do different things. Picture your fingers on a switch. Now the whine is how often you flip the switch. The AVERAGE ammount of juice the motor is fed is controlled by how long the switch is left on. The faster you flip the switch, the hotter the switch gets. This is a SUPER SIMPLIFIED explanation, but I think it will do.
Jraef
Titanium
- Joined
- Aug 10, 2004
- Location
- San Francisco Bay Area
By the way, technically you didn't really "stop" the whine, you just moved it outside of the range of human perception. Your dog may not like it now though...
As to what else it does, Junkyard already told you. It increases the amount of heat that the drive puts out (and the motor by the way). As he said, some (if not most) VFDs require a decrease in their capacity when you do that because you are heating up the power switching devices. So if you have a 1HP drive and a 1HP motor and you run it at full load most of the time, you are essentially cooking that VFD in exchange for making it less annoying. but if you have a 1HP VFD on a 3/4HP motor running at 80% load, you may never know the difference.. Most VFD manuals have a formula somewhere that tells you how to derate the VFD output when increasing the carrier frequency.
It doesn't really alter the other performance functions significantly.
Dog hearing....
Yes, I figured that I was moving the whine to a point I could not hear.
I have a 2HP rated VFD running a 1.5 HP motor and I did program the VFD so that it is set precisely to the motor specs. Given the parameters of the drive I moved it 2 values off default so its still well within the middle of the range of carrier frequency adjustment.
As for cooking the unit its not running the fan very much at all so I -guess- its not getting too hot or at least not outside if its design specs.
Yes, I figured that I was moving the whine to a point I could not hear.
I have a 2HP rated VFD running a 1.5 HP motor and I did program the VFD so that it is set precisely to the motor specs. Given the parameters of the drive I moved it 2 values off default so its still well within the middle of the range of carrier frequency adjustment.
As for cooking the unit its not running the fan very much at all so I -guess- its not getting too hot or at least not outside if its design specs.
You can program the VFD to run the fan all the time.
My hitachi has settings for turn the fan all the time (default), or run according to temp, or when the motor spins, until 5 minutes after you turn it off. I have mine set for the last setting, works good. It NEVER gets warm. I never screwed with the carrier frequency on mine because it was tolerable, 3hp vfd on a 2hp motor.
My hitachi has settings for turn the fan all the time (default), or run according to temp, or when the motor spins, until 5 minutes after you turn it off. I have mine set for the last setting, works good. It NEVER gets warm. I never screwed with the carrier frequency on mine because it was tolerable, 3hp vfd on a 2hp motor.
Pierce Butler
Hot Rolled
- Joined
- Jun 28, 2007
- Location
- Texas
You aren't going to "cook" any vfd with a temp sensor(s) built in. It will throw a fault long before the drive is damaged. I have yet to see anyone "cook" a vfd that was working properly.
Now maybe Hitachi designed a POS, but somehow I doubt that very much.
Pierce Butler
Hot Rolled
- Joined
- Jun 28, 2007
- Location
- Texas
I agree. Your install will be just fine.
Rody
Aluminum
- Joined
- Aug 7, 2007
- Location
- North Vancouver
PWM Frequency
This sound you hear is PWM frequency which is ajustable. This can be hard on old motors because of the windings. The high frequency flexs the windings so running low PWM say at 1000 should be fine for all motors. I use a pwm of 18,000HZ for silent operation but this is a special aplication. Some controls lower high pwm setting as motor increases in speed so as not to need to derate control. Boldor make great drive and have good support. The new H2 drives are very cool. You should run a line reactor on the input side to protect drive. You can set acceleration rates and decel. Costant torque ect. They are fairly simple to set up.
This sound you hear is PWM frequency which is ajustable. This can be hard on old motors because of the windings. The high frequency flexs the windings so running low PWM say at 1000 should be fine for all motors. I use a pwm of 18,000HZ for silent operation but this is a special aplication. Some controls lower high pwm setting as motor increases in speed so as not to need to derate control. Boldor make great drive and have good support. The new H2 drives are very cool. You should run a line reactor on the input side to protect drive. You can set acceleration rates and decel. Costant torque ect. They are fairly simple to set up.
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