Hello folks,
I have not found anyone else who has attempted to do what I'm going to try and describe here:
Take an off the shelf vfd programmed for a 0-10 volt input across the intended rpm range of the induction motor
Then take a dc tachometer setup directly driven by the motor so that it generates the same dc volts, as does the vfd require, to command the motor to run at a given speed.
In theory, the VFD will not run the motor, as the slip will be zero, and if the motor is run up to speed by some other means, the vfd will follow, lagging behind due to the time required for the vfd to increase the frequency.
Now what you do is take a +/- 1 volt supply and add it to the tachometer, using a joystick and a potentiometer. Now you are leading or lagging the motor and the acceleration limit is the vfd software and the slip (nominally 1 volt is 6hz to a vfd)
So anyhow to limit the current:
Take a portion of the dc current on the VFD and run it through a solenoid such that it resists the joystick. you now have force feedback...
I have not had time to put this together yet but I have a battery pack capable of 10kw at 100 cells in series (lifepo) and I have a 5hp 1750 rpm motor that I can wire in delta for 138volts ac
I would like to belt drive it 2:1 to my pickup truck engine... going to test the concept out on a fuji 1/2hp vfd i bought and a 90 watt induction motor, I only need to look around for a good choice for a tachometer at this point.
I'm intending to use the igbt block and most of the circuit board off of 4-5 ton heat pumps and just run a ribbon cable from the 1/2hp vfd to the bigger igbt. if the concept works what i'm thinking i would do to get more power out is to have 1 igbt module drive each set of 3 phase windings. the 4-5 ton pumps are nominally 20 amps at 240v so they typically have 30 amp rated igbts.
For efficiency purposes, at and below idle speed on the gas engine the vfd would have a very low volts/hz curve programmed.
I have not found anyone else who has attempted to do what I'm going to try and describe here:
Take an off the shelf vfd programmed for a 0-10 volt input across the intended rpm range of the induction motor
Then take a dc tachometer setup directly driven by the motor so that it generates the same dc volts, as does the vfd require, to command the motor to run at a given speed.
In theory, the VFD will not run the motor, as the slip will be zero, and if the motor is run up to speed by some other means, the vfd will follow, lagging behind due to the time required for the vfd to increase the frequency.
Now what you do is take a +/- 1 volt supply and add it to the tachometer, using a joystick and a potentiometer. Now you are leading or lagging the motor and the acceleration limit is the vfd software and the slip (nominally 1 volt is 6hz to a vfd)
So anyhow to limit the current:
Take a portion of the dc current on the VFD and run it through a solenoid such that it resists the joystick. you now have force feedback...
I have not had time to put this together yet but I have a battery pack capable of 10kw at 100 cells in series (lifepo) and I have a 5hp 1750 rpm motor that I can wire in delta for 138volts ac
I would like to belt drive it 2:1 to my pickup truck engine... going to test the concept out on a fuji 1/2hp vfd i bought and a 90 watt induction motor, I only need to look around for a good choice for a tachometer at this point.
I'm intending to use the igbt block and most of the circuit board off of 4-5 ton heat pumps and just run a ribbon cable from the 1/2hp vfd to the bigger igbt. if the concept works what i'm thinking i would do to get more power out is to have 1 igbt module drive each set of 3 phase windings. the 4-5 ton pumps are nominally 20 amps at 240v so they typically have 30 amp rated igbts.
For efficiency purposes, at and below idle speed on the gas engine the vfd would have a very low volts/hz curve programmed.
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