Compiler/DRV8303: drv8303

Pavel Rzhemovskiy

Part Number: DRV8303

Tool/software: TI C/C++ Compiler

Hello!

My name is Pavel. I'm working with DRV8303 for BLDC-motor control, and have some problem.

I use STM32 processor for PWM-generation. In the attachment I sent 2 screenshots. 1-st - those are pulses from DRV8303 outputs (yellow - high mosfet side, blue - low side).

2-nd - output from half-bridge (yellow) and nOCTW pin (blue).

Power supply - 24V. And if high mosfet opened - on the output should be 24V also. But, you see - it's 24V peak only. Than, output voltage drop to 11-12V.

When I reduce power supply voltage to 11-13V, faul becomes is ok.

I don't understand this situation...

Third picture - schematic of my project. Please, help me to solve this problem...

Thank you!!!

3.pdf

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi Pavel,

What are your register settings? Are you running OCP_MODE report only?

nOCTW is an indication you have an overcurrent condition. Please check the gate to source voltages of the high and low side FETs when transitioning. You may need some additional dead time with the additional resistors in series with the gates.

0 Pavel Rzhemovskiy over 7 years ago in reply to Rick Duncan

Prodigy 50 points

High and Low side FETs voltage you can see on the Pic1 in my attachment. Looks like 24V is present on the gate of high-side FET.
About OCP_MODE - I'm not use SPI-interface in this project.
Dead time I set by software very big)
Which setting do you need?

0 Rick Duncan over 7 years ago in reply to Pavel Rzhemovskiy

TI__Guru** 114905 points

Hi Pavel,

24V is present at the source of the high side FET, and then collapses to 12V. This is a possible indication of an overcurrent event. Monitoring the gate to source voltage of the high side and low side FET can show if you have both FETs on.

0 Pavel Rzhemovskiy over 7 years ago in reply to Rick Duncan

Prodigy 50 points

Hi Rick!
I checked voltage high side and low side FET. I can't add pictures...
Those are the same, like Pic.1

0 Rick Duncan over 7 years ago in reply to Pavel Rzhemovskiy

TI__Guru** 114905 points

Hi Pavel,

The high side gate should be approximately 35V when the FET is enabled (11 V gate to source). If the high side FET is disabled the gate voltage should match the SH_x voltage (0 V gate to source).

Depending on the browser used you should be able to select something like "Insert Code, Attach Files and more ..." to include the scope captures.

0 Pavel Rzhemovskiy over 7 years ago in reply to Rick Duncan

Prodigy 50 points

35V voltage high side gate - between gate and ...?

0 Rick Duncan over 7 years ago in reply to Pavel Rzhemovskiy

TI__Guru** 114905 points

Hi Pavel,

Between high side Gate and GND, assuming VM = 24V

0 Pavel Rzhemovskiy over 7 years ago in reply to Rick Duncan

Prodigy 50 points

Hi Rick!

I made SPI-communication with DRV8303 and increased OC-protection value. After that - everything start work good)))

Thank you! If you will plan visit Ukraine - inform me! I'll buy to you bottle of good whisky)))

Pavel.

0 Rick Duncan over 7 years ago in reply to Pavel Rzhemovskiy

TI__Guru** 114905 points

Hi Pavel,

You are welcome. We are glad to hear everything is working.

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Compiler/DRV8303: drv8303