P
P E Schoen
- Jan 1, 1970
- 0
I'm looking into a battery-powered small vehicle (tractor) design which will
use a three-phase motor and VF controller, and I want to create the DC bus,
or link, voltage from several 12V SLA batteries. I will need 360 or 720 VDC
for 208/240 or 480 VAC motors.
I thought about using some of the inexpensive modified sine wave inverters
available from Harbor Freight and other companies, where a 2000W inverter
can be obtained for about $150. My first thought was to rectify the output
and filter it, to get about 180 VDC and then use two or four in series for
the higher voltages. But I think these inverters create their own DC bus
using a switching power supply and then use high voltage transistors or
IGBTs in a bridge which produces the modified sine wave.
I have searched for schematics but most of them are for simple inverters
using a 60 Hz power transformer driven with a square wave, but that's not
what I want. And other schematics are like the reference designs for UPS
systems, which are probably similar to what I want, and they can have either
modified sine wave or true sine (PWM) outputs. It's probably not hard to
design and build my own, but if I can use off-the-shelf inverters then I'll
be ahead of the game.
My next step is to open up one of the small inverters I have to see how they
are made, and maybe discover and measure the DC bus voltage, but if anyone
has the actual schematics for one of these, I'd appreciate a look at it.
Otherwise, I'll let you know what I find.
Thanks,
Paul
use a three-phase motor and VF controller, and I want to create the DC bus,
or link, voltage from several 12V SLA batteries. I will need 360 or 720 VDC
for 208/240 or 480 VAC motors.
I thought about using some of the inexpensive modified sine wave inverters
available from Harbor Freight and other companies, where a 2000W inverter
can be obtained for about $150. My first thought was to rectify the output
and filter it, to get about 180 VDC and then use two or four in series for
the higher voltages. But I think these inverters create their own DC bus
using a switching power supply and then use high voltage transistors or
IGBTs in a bridge which produces the modified sine wave.
I have searched for schematics but most of them are for simple inverters
using a 60 Hz power transformer driven with a square wave, but that's not
what I want. And other schematics are like the reference designs for UPS
systems, which are probably similar to what I want, and they can have either
modified sine wave or true sine (PWM) outputs. It's probably not hard to
design and build my own, but if I can use off-the-shelf inverters then I'll
be ahead of the game.
My next step is to open up one of the small inverters I have to see how they
are made, and maybe discover and measure the DC bus voltage, but if anyone
has the actual schematics for one of these, I'd appreciate a look at it.
Otherwise, I'll let you know what I find.
Thanks,
Paul