Reliable and Flexible Switching System

[MarkE]

Looking at this page http://www.powerguru.org/the-half-bridge-circuit-revealed/ and the circuit in the data sheet pdf below I made these drawings, I must confess using some kinds of IC's confuses me and this is one of them.

Can anyone see any problems with the circuit for the IRS2110 ? I know some gate resistors may be needed, if I could get operation up to about 25 or 30 kHz I would be happy. Even if I could get good operation up to a few hundred Hz I would be satisfied to begin with.

The circuit with the two batteries just signifies a split EMF. The other one with the capacitor in series with the load coil is kinda like the one from the web page above, he uses a different driver chip.

So one thing that you need to make sure of is that the circuit switches low periodically to recharge C4.  I have not looked to see if the driver chip you are using has undervoltage protection for both the high side and low side driver.  Another thing that you should consider is a two resistor and one Schottky diode network in series with each gate to suppress oscillations and optimize the waveshape.  But the BIG thing here is that you have placed your load in series with a capacitor.  The circuit you are deriving from had two stacked power supplies.  If you don't want to have stacked power supplies, and your load isn't across your output capacitor, then build a full bridge.

[Farmhand]

Thanks Mark I appreciate the tips, I think SeaMonkey already tried to school me on this and from memory I think had this IRS2110 Hi-Lo driver chip working with a capacitor voltage doubler but I failed to draw the circuit that worked for me. I'm having issues but I need to work it out myself to learn properly, I think. So I found a couple of application notes pdf's on these drivers, at first glance they might help me, if not I'm missing something, I think I'll check my solderless board for cross rail "shorts", for some reason both mosfets are half on with the circuit not even powered up. I pull em out they turn off.

I'm using the signal splitting/dead time control part of the circuit below to process the picaxe output into two 48% duty out of phase signals at 10000 kHz to test the driving circuit. I can adjust the dead time if need be to keep appropriate dead time at the switches if I can get the driver IC to work properly  signals out of the CD4001 are very good.

Anyway maybe the application notes will help someone else as well.


Driver IC application notes.
http://www.irf.com/technical-info/appnotes/an-978.pdf

http://www.irf.com/technical-info/appnotes/an-1123.pdf

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[MarkE]

Thanks Mark I appreciate the tips, I think SeaMonkey already tried to school me on this and from memory I think had this IRS2110 Hi-Lo driver chip working with a capacitor voltage doubler but I failed to draw the circuit that worked for me. I'm having issues but I need to work it out myself to learn properly, I think. So I found a couple of application notes pdf's on these drivers, at first glance they might help me, if not I'm missing something, I think I'll check my solderless board for cross rail "shorts", for some reason both mosfets are half on with the circuit not even powered up. I pull em out they turn off.

I'm using the signal splitting/dead time control part of the circuit below to process the picaxe output into two 48% duty out of phase signals at 10000 kHz to test the driving circuit. I can adjust the dead time if need be to keep appropriate dead time at the switches if I can get the driver IC to work properly  signals out of the CD4001 are very good.

Anyway maybe the application notes will help someone else as well.


Driver IC application notes.
http://www.irf.com/technical-info/appnotes/an-978.pdf

http://www.irf.com/technical-info/appnotes/an-1123.pdf

..

Those are excellent application notes that cover the subject of the high side bootstrap power supply very well.  10MHz is very fast for power MOSFETs.  Is that your timing resolution, or your cycle time?  A good frequency range to work with MOSFETs without too much worry is between 50kHz and 300kHz.  Slower and the output filter energy starts to get big.  Faster and you have to start paying a lot more attention to layout issues which are much worse using a solderless breadboard than on a circuit board.

[Farmhand]

OK Now I see the problem, I'm sure you'll find it easy to believe that I had the driver chip upside down hahaha, no harm done it works exactly as it should I think in bootstrap mode, it can be used with a floating supply as well.

The drive circuit posted above with the split supply is basically from the data sheet and works ok but I'll check it to be sure.

I used a 1 uF bootstrap capacitor, and the test setup is 12-24 volts supply.

No not 10 mHz, 10 kilohertz from the picaxe to the signal splitter and 5 kHz to each mosfet 48% duty for the test to see if i have the circuit right.  scope capture attached.

Some more reading and I can set to work.

P.S. IRF840's were being driven while the shot was taken.

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[MarkE]

OK Now I see the problem, I'm sure you'll find it easy to believe that I had the driver chip upside down hahaha, no harm done it works exactly as it should I think in bootstrap mode, it can be used with a floating supply as well.

The drive circuit posted above with the split supply is basically from the data sheet and works ok but I'll check it to be sure.

I used a 1 uF bootstrap capacitor, and the test setup is 12-24 volts supply.

No not 10 mHz, 10 kilohertz from the picaxe to the signal splitter and 5 kHz to each mosfet 48% duty for the test to see if i have the circuit right.  scope capture attached.

Some more reading and I can set to work.

P.S. IRF840's were being driven while the shot was taken.

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5kHz sounds much more reasonable.  The waveforms show the dead time that you intend.  It sounds like you are off to the races.