I have been attempting to build a DC to AC power inverter. My first attempt was to take a 12 V DC source and boost that to 170V DC and then filter it into roughly 120V AC pure sine wave output after going through an H-Bridge. However, the process and cost of creating the DC-DC boost stage was not ideal for me so I got an off the shelf inverter which was of a modified sine wave and noticed they have a huge transformer along with other components that boosted the 12V supply DC into 120V DC and then filtered it into AC then sent into H-Bridge.

My question is, could I just tap into the DC-DC Boost stage of 12 to 120V DC and then filter the 120VDC into a pure sine wave by the use of a low-pass filter and then send it through the H-Bridge. Would this obtain the 120V AC pure sine I am looking for at the output? and would the H-Bridge effectively switch the 120V AC sine wave and feed it to the load? Or will I have to use some type of PWM?

 

"My question is, could I just tap into the DC-DC Boost stage of 12 to 120V DC Maybe and then filter the 120VDC into a pure sine wave by the use of a low-pass filter Nope that won't work and then send it through the H-Bridge. Would this obtain the 120V AC pure sine I am looking for at the output? NO! and would the H-Bridge effectively switch the 120V AC sine wave and feed it to the load? Might work if you actually have a sine wave going into it Or will I have to use some type of PWM? "

 

Since you already now have a modified sine inverter, are you sure you really still need a pure sine inverter? If so, you need to define the level of purity you need. Commercial pure sine inverters may not be cheap, but they're cheaper than anything you can build to the same specs.

 

To generate a pure sine wave with any significant power and with high efficiency you will need to use PWM.