|
I think most people will class anything over 200V as high voltage, the industry will class anything below 690V as low voltage so its a bit confusing. the point is to allow the use of standard motors which are cheaper than specials. So 208/240 V should be good for a lot of applications. I would prefer to go with 480V since you can get more power throught the equipment.
I thought about a simple analog control for a cheap off the shelf v/f controller, using a circuit to combine the rotor RPM with the throttle position to move the drive's setpoint around.
for example you could use closed throttle to provide 1% lag (drive setpoint 1% lower than actual rotor RPM, one third throttle could set the setpoint to equal rotor RPM, then full throttle couid move the setpoint to 3% higher RPM than rotor RPM to give full torque. I'm not sure if i am missing something important about how the drives work, but it seems to me this would work.
You could even set the setpoint progressivley slower using the brake pedal before the actusl brakes start to work.
|