I am designing an inductance coupling circuit for long-distance wireless charging. I'm using an IR2184 MOSFET driver and a 555 to generate a 115kHz square wave for its input. The MOSFETs drive a 300cm 10 turn Coil with an inductance of 81.5uH. (see attached schematic).

When I don't have the MOSFETs attached to the circuit I get what looks correct on my scope with Channel 1 probe to the input pin of the IR2184 w/ a 115kHz square wave and voltage of 6v. (see attached picture). Channel 2 is probed to LO output. I realize without the MOSFETS in the circuit I cannot read HO.

Now when I hook up the MOSFETs things get crazy and the IR2184 eventually shuts down and then tries to restart. The Second image below is what my scope looks like with Channel 1 = input of ir2184, Channel 2 probed at the Gate of Lower MOSFET, and Channel 3 probed at the gate of the Upper MOSFET. In the case above my PS was not drawing a lot of current but in In some cases, my PS draws an excessive amount of current because evidently (as my Scope shows the MOSFETs are not synced correctly and shorting out.

Any ideas about what I'm doing incorrectly or what is going on here?

Thanks in advance.

Mark

 

First, we need to see the actual circuit, because without understanding the connection points or the voltage reference it is a challenge to know what the wave forms show.

And second, wireless charging is terribly inefficient, and even worse at any distance. It is also a source of electronic airwave pollution.

 

Have you correctly calculated the value for the Vboost capacitor ?

 

I am designing an inductance coupling circuit for long-distance wireless charging. I'm using an IR2184 MOSFET driver and a 555 to generate a 115kHz square wave for its input. The MOSFETs drive a 300cm 10 turn Coil with an inductance of 81.5uH. (see attached schematic).

When I don't have the MOSFETs attached to the circuit I get what looks correct on my scope with Channel 1 probe to the input pin of the IR2184 w/ a 115kHz square wave and voltage of 6v. (see attached picture). Channel 2 is probed to LO output. I realize without the MOSFETS in the circuit I cannot read HO.

Now when I hook up the MOSFETs things get crazy and the IR2184 eventually shuts down and then tries to restart. The Second image below is what my scope looks like with Channel 1 = input of ir2184, Channel 2 probed at the Gate of Lower MOSFET, and Channel 3 probed at the gate of the Upper MOSFET. In the case above my PS was not drawing a lot of current but in In some cases, my PS draws an excessive amount of current because evidently (as my Scope shows the MOSFETs are not synced correctly and shorting out.

Any ideas about what I'm doing incorrectly or what is going on here?

Thanks in advance.

MarkView attachment 296245View attachment 296246

 

I have found one significant issue with my design that was one of those "Dah" moments. If you look at my physical breadboard below, can you see the issue? I have my MOSFET drains tied together on a single heatsink - so no wonder I got the result I had. I have since separated them but still get some strange readings on my scope.

@MisterBill2 - although I stated "long-distance" the practical application is within the 300cm coil. @MaxHeadRoom - I'm assuming you are referring to C1, the capacitor that makes up the bootstrap part of the circuit? I did not calculate this value but am using its value from what others have used in their circuits. The coupling capacitors C2,C3,C8 sum is derived from the formula to calculate Resonant frequency with a given the target frequency and inductance coil. I cannot explain why i'm getting 0 volts on the lower MOSFET gate and 29 Volts on the Upper MOSFET gate. I'm wondering if my IR2184 is damaged and that is my issue.

 

I have found one significant issue with my design that was one of those "Dah" moments. If you look at my physical breadboard below, can you see the issue? I have my MOSFET drains tied together on a single heatsink - so no wonder I got the result I had. I have since separated them but still get some strange readings on my scope.

@MisterBill2 - although I stated "long-distance" the practical application is within the 300cm coil. @MaxHeadRoom - I'm assuming you are referring to C1, the capacitor that makes up the bootstrap part of the circuit? I did not calculate this value but am using its value from what others have used in their circuits. The coupling capacitors C2,C3,C8 sum is derived from the formula to calculate Resonant frequency with a given the target frequency and inductance coil. I cannot explain why i'm getting 0 volts on the lower MOSFET gate and 29 Volts on the Upper MOSFET gate. I'm wondering if my IR2184 is damaged and that is my issue.View attachment 296290View attachment 296291View attachment 296292

correction to above, I had my scope's scale set incorrectly. The Lower MOSFET gate is at 1.4V while the Upper MOSFET is at 12.2V.

 

I have found one significant issue with my design that was one of those "Dah" moments. If you look at my physical breadboard below, can you see the issue? I have my MOSFET drains tied together on a single heatsink - so no wonder I got the result I had. I have since separated them but still get some strange readings on my scope.

@MisterBill2 - although I stated "long-distance" the practical application is within the 300cm coil. @MaxHeadRoom - I'm assuming you are referring to C1, the capacitor that makes up the bootstrap part of the circuit? I did not calculate this value but am using its value from what others have used in their circuits. The coupling capacitors C2,C3,C8 sum is derived from the formula to calculate Resonant frequency with a given the target frequency and inductance coil. I cannot explain why i'm getting 0 volts on the lower MOSFET gate and 29 Volts on the Upper MOSFET gate. I'm wondering if my IR2184 is damaged and that is my issue.View attachment 296290View attachment 296291View attachment 296292

According to the datasheet the input to the Driver chip is Only 5 Volt logic compatible, so by driving it with 12 Volts from the 555 you've probably killed it.

 

According to the datasheet the input to the Driver chip is Only 5 Volt logic compatible, so by driving it with 12 Volts from the 555 you've probably killed it.

You are probably right. I've ordered a few new ones and put a LM7805 (5V) on the 555 and LM7812 (12V) on the IR2184 VCC.

 

According to the datasheet the input to the Driver chip is Only 5 Volt logic compatible, so by driving it with 12 Volts from the 555 you've probably killed it.

You are probably right. I've ordered a few new ones and put a LM7805 (5V) on the 555 and LM7812 (12V) on the IR2184 VCC.

I noticed again in the datasheet that it does say that both the Input and the /SD pins are internally clamped to 5.2 Volts by a zener, but don't state how much current it can absorb. So the chip may have survived?
Sorry if I've made you shell out for I.C's that you didn't need. But my guess is that there's something wrong with the current one.