Dear All,

I am trying to construct an inverter circuit using IR2113 gate driver and IRFB7546 mosfets and eventually drive a BLDC. I've constructed a circuit following the schematics from Tahmid's blog on a solderless breadboard (I am using a 22uF tantalum capacitor and UF4007 as my bootstrap circuit).



My PWM signals with dead-band are generated from the TI F28027 Launchpad, LIN and HIN.


I am expecting the my HO to follow my HIN and LO to follow my LIN but it is not the case. From the oscilloscope, the HO at below does fully turn off and I am afraid of cross conduction.



My VCC is supplied with 15V and VDD with 5V from the microcontroller, all grounds are connected together.

May I know what is wrong with my circuit? Let me know if additional information are needed, many thanks in advance.

 

Dear All,

I am trying to construct an inverter circuit using IR2113 gate driver and IRFB7546 mosfets and eventually drive a BLDC. I've constructed a circuit following the schematics from Tahmid's blog on a solderless breadboard (I am using a 22uF tantalum capacitor and UF4007 as my bootstrap circuit).

View attachment 101211

My PWM signals with dead-band are generated from the TI F28027 Launchpad, LIN and HIN.
View attachment 101210

I am expecting the my HO to follow my HIN and LO to follow my LIN but it is not the case. From the oscilloscope, the HO at below does fully turn off and I am afraid of cross conduction.

View attachment 101217

My VCC is supplied with 15V and VDD with 5V from the microcontroller, all grounds are connected together.

May I know what is wrong with my circuit? Let me know if additional information are needed, many thanks in advance.

Are you testing it without the FETs? If so you need to add a resistor from HO to ground.

 

Unless the high-side FET source is being pulled low by the low-side FET the bootstrap circuit won't work, so the HO voltage won't be high enough to turn the high-side FET on. Are you seeing a VB voltage of about 312V?

 

Are you testing it without the FETs? If so you need to add a resistor from HO to ground.

Unless the high-side FET source is being pulled low by the low-side FET the bootstrap circuit won't work, so the HO voltage won't be high enough to turn the high-side FET on. Are you seeing a VB voltage of about 312V?

Thanks for the reply, I am testing with the MOSFETS in place and my VB voltage is about 20V. I have connected two of these circuits to form a H-bridge and to a 9V motor as below,





I am applying a complementary PWM with dead-band to HIN of U1 and LIN of U2,



This should allow current to flow from Q1 to Q4 right (or vice versa)? But the motor does not move, and this is the waveform I get from Q1 HIN and HO,



My question now is, even though I did not have any input to HIN of U2, my HO still has an output as the following I am not sure why.

 

HIN of U1 and LIN of U2 should be driven together, for turning on Q1 & Q4. With a complementary PWM, Q1 and Q4 are never on together, and no voltage is applied to the motor. During dead time, both Q1 & Q4 are off. And, when Q1 is on, Q4 is off and Q4 is on, Q1 is off.
Similiarly Q2 & Q3 should be driven together.

 

HIN of U1 and LIN of U2 should be driven together, for turning on Q1 & Q4. With a complementary PWM, Q1 and Q4 are never on together, and no voltage is applied to the motor. During dead time, both Q1 & Q4 are off. And, when Q1 is on, Q4 is off and Q4 is on, Q1 is off.
Similiarly Q2 & Q3 should be driven together.

First and foremost, thank you for your reply. Yes, that is exactly what I have applied to my circuit, complementary PWM to HIN of U1 and LIN of U2 as seen in this image,

But for some reason, even though I have not applied any input to HIN of U2, the HO of U2 is giving me some output and my motor just wont run.

 

I have connected two of these circuits to form a H-bridge and to a 9V motor as below,

The source of Q1 needs to toggle high and low rapidly in order for C1 to act as a charge pump and create the correct boost voltage VB (about 12V above the voltage applied to Q1 drain). Similarly for Q3/C5.
Incidentally, is your supply really 300V? I don't think a 9V motor will last long if so .

 

The source of Q1 needs to toggle high and low rapidly in order for C1 to act as a charge pump and create the correct boost voltage VB (about 12V above the voltage applied to Q1 drain). Similarly for Q3/C5.
Incidentally, is your supply really 300V? I don't think a 9V motor will last long if so .

Thank you for your reply, I am terribly sorry for not clarifying, the schematic is taken from http://tahmidmc.blogspot.my/2013/01/using-high-low-side-driver-ir2110-with.html. I am actually supplying 9V to the motor and my switching frequency is 20kHz.

I believe I might have solved the problem by opto-isolating the microcontroller to the gate driver, and using a external 5V+ to supply VDD instead of the 5V output from the microcontroller. I will use the oscilloscope to confirm my findings soon.

Once again thanks for all the inputs.