DC/AC INVERTER W/ IGBT's
DC/AC INVERTER W/ IGBT's
(OP)
Hi,
I'm trying to design a one phase, 2 kVA inverter using a IGBT "H" bridge.
There are two wave shapes for drive the bridge; one generated with PWM method, providing pulses of different width and same amplitude, of course according of the angle of the sine reference.
The other one can be an stteped wave with 4 steps on each half cycle.
I'm not sure wich is the best method, in special for the filtering purpose, because we need a pure sine wave at the output.
Some suggestion??, thanks.
Jorge
I'm trying to design a one phase, 2 kVA inverter using a IGBT "H" bridge.
There are two wave shapes for drive the bridge; one generated with PWM method, providing pulses of different width and same amplitude, of course according of the angle of the sine reference.
The other one can be an stteped wave with 4 steps on each half cycle.
I'm not sure wich is the best method, in special for the filtering purpose, because we need a pure sine wave at the output.
Some suggestion??, thanks.
Jorge





RE: DC/AC INVERTER W/ IGBT's
Is it a single DC voltage, or is it a series of batteries?
RE: DC/AC INVERTER W/ IGBT's
RE: DC/AC INVERTER W/ IGBT's
You'd better define your output better than "pure," ie., some allowable percentage of THD on your output voltage waveform.
A 4-step wave shape won't even get you close to "pure". PWM will likely have to be deep in the kHz range. Either way, you'll still need some heavy filtering. In general, the faster the frequency of your inverter, the less filtering you'll have to do, no matter how it's configured.
Most commercially available inverters do a pretty lousy job at generating a "pure" sine wave.
RE: DC/AC INVERTER W/ IGBT's
RE: DC/AC INVERTER W/ IGBT's
as we will use an step-up transformer to obtain 220 VAC, 60 Hz output.
peebe- Thanks, I'll like 3% THD as much.
Don't you think using PWM (kHz range) I'll need less filtering for 60 Hz. sine wave shape, and much for harmonics.
As I understand this is not a commercial site I'll prefer not ask for inverters brand names.
Jorge.
RE: DC/AC INVERTER W/ IGBT's
RE: DC/AC INVERTER W/ IGBT's
RE: DC/AC INVERTER W/ IGBT's
Melone - at input voltages below about 60 volts, use power FETs. The minimum Vce on IGBTs is about 2.0 volts. Some a little more, some a little less. A good power FET will have an on resistance of about 0.01 ohms. At 100 amps, that is only 1.0 volts drop. Yes, the on resistance will rise slightly with less current, but at absolute worst won't increase more than 50%. So, 1 amp at 0.015 ohms, ain't much loss.