Hello Everyone,
I came upon AllAboutCircuits while trying to research info about my latest project. There was a similar topic to my problem addressed in bigbigblue's thread, http://forum.allaboutcircuits.com/showthread.php?t=2262. I believe my application and problem is different than his.
To give everyone a little bit of background on the project I'm hoping to build an AC Power generator that can produce 90-260VAC, 45-65Hz, and deliver 2-4Amps to a load. That's very high level and the project details haven't all been worked out and as I've been working the project becomes more defined. Look at http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=64487
to see a history of my progress and what issues I've thought about. The project centers around an Atmega2560, which is why I was posting on the AVRFreaks web site.
My most recent problem is taking a low level pwm signal from my microcontroller to drive high power mosfets in a bridge configuration. I've been working with this issue for over a month now and been getting great use out of my safety glasses. I've tested my sinwave pwm scheme at low power levels and been able to produce a +/-15V sin wave using a full H-Bridge. I'm using FAN73832 Fairchild half bridge drivers for each side of the H-Bridge. At high power I'm using a rectified AC voltage (170VDC) for the top of the H-Bridge. I've been using the SPP04N50C3 MOSFETs from Infineon. At this point I'd simply like to have a working prototype that drives HV through an H-Bridge, regardless of what my specs are. I'm constantly going through the driver chips (which have a rating of up to a 600V rail) and as a result go through MOSFETS as well.
I believe the issue is with the bootstrap capacitor and the sizing on that. I realize that this affects the pwm frequency and duty cycle. At times I simply test a 50% duty cycle to get away from the more complicated sinwave pwm scheme. Could anyone help me with the bootstrap design? Or does anyone know of any discrete MOSFET driver designs I could use with high voltage rather than an IC solution? I've seen the designs on this website, http://www.innovatia.com/Design_Center/High-Side Drivers.htm,
but they are for low power and I haven't seen any elsewhere. I'm really stuck at how to drive my H-Bridge under the 170VDC rail. Any help would greatly be appreciated.
Thanks, Alan
I came upon AllAboutCircuits while trying to research info about my latest project. There was a similar topic to my problem addressed in bigbigblue's thread, http://forum.allaboutcircuits.com/showthread.php?t=2262. I believe my application and problem is different than his.
To give everyone a little bit of background on the project I'm hoping to build an AC Power generator that can produce 90-260VAC, 45-65Hz, and deliver 2-4Amps to a load. That's very high level and the project details haven't all been worked out and as I've been working the project becomes more defined. Look at http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=64487
to see a history of my progress and what issues I've thought about. The project centers around an Atmega2560, which is why I was posting on the AVRFreaks web site.
My most recent problem is taking a low level pwm signal from my microcontroller to drive high power mosfets in a bridge configuration. I've been working with this issue for over a month now and been getting great use out of my safety glasses. I've tested my sinwave pwm scheme at low power levels and been able to produce a +/-15V sin wave using a full H-Bridge. I'm using FAN73832 Fairchild half bridge drivers for each side of the H-Bridge. At high power I'm using a rectified AC voltage (170VDC) for the top of the H-Bridge. I've been using the SPP04N50C3 MOSFETs from Infineon. At this point I'd simply like to have a working prototype that drives HV through an H-Bridge, regardless of what my specs are. I'm constantly going through the driver chips (which have a rating of up to a 600V rail) and as a result go through MOSFETS as well.
I believe the issue is with the bootstrap capacitor and the sizing on that. I realize that this affects the pwm frequency and duty cycle. At times I simply test a 50% duty cycle to get away from the more complicated sinwave pwm scheme. Could anyone help me with the bootstrap design? Or does anyone know of any discrete MOSFET driver designs I could use with high voltage rather than an IC solution? I've seen the designs on this website, http://www.innovatia.com/Design_Center/High-Side Drivers.htm,
but they are for low power and I haven't seen any elsewhere. I'm really stuck at how to drive my H-Bridge under the 170VDC rail. Any help would greatly be appreciated.
Thanks, Alan