DC Motor Control Using IR2104 Driver

[MangoBear]

Hello,

I am currently designing a DC motor control circuit using two IR2104 drivers and four IRF3205 MOSFETs. The MOSFETs are oriented in an H-bridge configuration, the motor I want to control is rated for 24V, and my logic voltage Vcc is set to 12V. The bootstrap diode I chose is the 1N4007 and I am operating at a 1kHz pwm signal with a min/max duty cycle of 10% to 90%. My gate resistors are at 10 ohms.

During initial testing using a 1uF bootstrap capacitor, I was reading output pulses out of LO and HO, but LO was pulsing from +6V to -6V instead of from 12V to 0V. And, HO was not getting a high enough voltage on its pulses, which I would assume means that my bootstrap capacitor is inadequate.

I've been looking at a lot of different websites and articles, but it looks like everyone has a different equation to calculate bootstrap capacitance. Is there a generally accepted equation I can use with the specifications I have provided?

 

[danadak]

Do you have a schematic of your circuit ?


Regards, Dana.

 

[MangoBear]

Absolutely, here you go.

 

[Delta Prime]

Welcome to Maker Pro.

I am currently designing a DC motor control circuit using two IR2104 drivers and four IRF3205 MOSFETs

Could you please provide the manufacturer data sheet of your motor?
Could you please provide a link to the source of this schematic?Thank You.

I've been looking at a lot of different websites and articles, but it looks like everyone has a different equation to calculate bootstrap capacitance. Is there a generally accepted equation I can use with the specifications I have provided?

Here's an additional resource. How to choose the bootstrap components. The equation can be transposed;
examples are given, it's a very good read.

 

[Alec_t]

but LO was pulsing from +6V to -6V instead of from 12V to 0V.

Did you have your measuring device ('scope?) AC-coupled or DC-coupled to the circuit?

 

[MangoBear]

Welcome to Maker Pro.

Where are your motors? (Ma & Mb).
Could you please provide the manufacturer data sheet of your motors?
Could you please provide a link to the source of this schematic?Thank You.

Here's an additional resource specific to your design, along with how to choose the bootstrap components. The equation can be transposed;
examples are given, it's a very good read.

Thank you!

I'm sorry for any confusion. I made the schematic myself in KiCad, which is a software I am still getting used to. The designators Ma and Mb refer to two sides of the same motor, so only one motor is being used in the design between those points.

I'll attach the data sheet of the motor I'm using.

I'll attach a pdf of my schematic as well.

Thanks for the link, I'll make sure to give it a read!

 

[MangoBear]

Did you have your measuring device ('scope?) AC-coupled or DC-coupled to the circuit?

That is a good question, I didn't think to check that. I'll make sure to do so tomorrow, thanks!