David_
Advanced Member level 2
Hello.
I am building a SPWM Variable Frequency Drive that should be able to output at least 240Vrms @ 50Hz to drive a fan that may consume at most 30W, as far as I know for that I need a DC rail of 450Vdc.
What is the simplest/easiest way to achieve a 450Vdc rail?
My first idea was a PFC circuit which I used a online design tool to generate the BOM for but the component required is making me question this idea, the design tool says I need a 11454µH inductor with a peak current of 0,57A. Which is expensive.
Since I know that the maximum current the fan will draw at 240Vrms is 0,125A I put in some margin and used that current for the 450Vdc rail which equates to around 60W, but thinking about the whole situation where the 450Vdc rail supplies what becomes 240Vrms is making me unsure of how much current that 450Vdc rail needs to be able to supply.
Should I just go with a offline flyback-converter? But that creates a lot of reflected voltage on the primary requiring a MOSFET with a very high VDS rating, I think it was the flyback topology that had that characteristic at least.
Regards.
- - - Updated - - -
I am new to the whole VFD thing and changing the speed of a AC motor, but I just realized that I should be able to rectify 230Vrms, chop that into a SPWM sinewave and just adjust the frequency down to a frequency with the correct ratio to whatever the highest sinewave SPWM voltage that would be produced, no?
I am building a SPWM Variable Frequency Drive that should be able to output at least 240Vrms @ 50Hz to drive a fan that may consume at most 30W, as far as I know for that I need a DC rail of 450Vdc.
What is the simplest/easiest way to achieve a 450Vdc rail?
My first idea was a PFC circuit which I used a online design tool to generate the BOM for but the component required is making me question this idea, the design tool says I need a 11454µH inductor with a peak current of 0,57A. Which is expensive.
Since I know that the maximum current the fan will draw at 240Vrms is 0,125A I put in some margin and used that current for the 450Vdc rail which equates to around 60W, but thinking about the whole situation where the 450Vdc rail supplies what becomes 240Vrms is making me unsure of how much current that 450Vdc rail needs to be able to supply.
Should I just go with a offline flyback-converter? But that creates a lot of reflected voltage on the primary requiring a MOSFET with a very high VDS rating, I think it was the flyback topology that had that characteristic at least.
Regards.
- - - Updated - - -
I am new to the whole VFD thing and changing the speed of a AC motor, but I just realized that I should be able to rectify 230Vrms, chop that into a SPWM sinewave and just adjust the frequency down to a frequency with the correct ratio to whatever the highest sinewave SPWM voltage that would be produced, no?