DRV8302: Issue when connecting to load

Thibaut Milson

Part Number: DRV8302
Other Parts Discussed in Thread: DRV8301

Hi everyone !

I'm currently trying to use the DRV8302 in order to develop an ESC, but I am having issue when connecting the motor.

I'm in the first stage of development and still trying to have my motor turn. So I'm not using the buck and current amplifier for now.

For the schematic I followed the example in the datasheets with a few variation considering my choice of transistor and load.

I'm using the IRFB7530PbF as transistor (Kind of heavy Qg=271, but my frequency of commutation is between 10k and 20k so taking in account the datashit it should be fine).

My motor is a 2200W BLDC.

The alimentation is a 36V battery pack.

I uploaded:

One in which the load is just resistive. We can see that the transistor does commute correctly.
Another one in which the load is the motor, where the commutation stops
The schematics

I looked at the previous post to find a solution and tried some modification however I'am still unable to make the motor turn.

Do you have any suggestions for me?

(Yes the power pad is soldered to the ground)

TI-forum.zip

IRFB7530PbF

over 5 years ago

0 Thibaut Milson over 5 years ago

Prodigy 175 points

*Sorry by uploaded I meant in the zip are the plots and schematics

0 Thibaut Milson over 5 years ago

Prodigy 175 points

New information !

Both the fault and OCTW are low even if no mosfet are connected to the output of the driver. (The driver is still able to create the output PWM)
I checked the value of GVDD, AVDD and PVDD to see if it matched the fault and report warning but it is not the case. The value of AVDD is quite above 3.3V (5.2V to be precise) is it okay ?

0 Hector Hernandez Luque over 5 years ago in reply to Thibaut Milson

TI__Expert 8980 points

Hi Thibaut,

Errdata to consider on this device. Please verify your power sequencing:

8.1.1 Gate Driver Power Up Sequencing Errdata

The DRV8301 gate drivers may not correctly power-up if a voltage greater than 8.5 V is present on any SH_X
pin when EN_GATE is brought logic high (device enabled) after PVDD1 power is applied (PVDD1 > PVDD_UV).
This sequence should be avoided by ensuring the voltage levels on the SH_X pins are less than 8.5 V when the
DRV8301 is enabled through EN_GATE.

Verify capacitor values between your design and Section 8.2 Typical Applications of datasheet.

Transistor charge is high. It can cause a problem when combined with motor vs. resistor. We can continue on this subject after verifying first two suggestions.

0 Thibaut Milson over 5 years ago in reply to Hector Hernandez Luque

Prodigy 175 points

Hi !

First of all, thank you for your quick answer.

I Checked the power up sequence and no voltage are present on the the SH_X pin before En_GATE is enabled.

Do you think I should increase the value of my bootstrap capacitor ?

0 Thibaut Milson over 5 years ago in reply to Thibaut Milson

Prodigy 175 points

Also, I was also wondering if the software could be an issue.
I am working with someone developing the control software.

In order for the bootstrap capacitor to charge, the low side transistor need to be driven right ?

0 Thibaut Milson over 5 years ago in reply to Thibaut Milson

Prodigy 175 points

One thing that I am really worried about is the value of DVDD (not AVDD my bad) which is way higher than 3.3V

0 Thibaut Milson over 5 years ago in reply to Thibaut Milson

Prodigy 175 points

Hi,

So i did try to modify the value of the bootstrap capacitor (220 nF -> 320nF)

All it changed is that now I have more spikes for my pwm, It inscreased their frequency. (See previous posted pictures)

After each spike, the fault pin goes low until the next spike.

0 Hector Hernandez Luque over 5 years ago in reply to Thibaut Milson

TI__Expert 8980 points

Hi Thibaut,

When the DVDD value is higher than 3V3, it can be that your ground reference is not 0 V. Please get a scope capture of both DVDD and AVDD to see if they are at 0 V.

0 Thibaut Milson over 5 years ago in reply to Hector Hernandez Luque

Prodigy 175 points

Hi hector,

I checked the value of DVDD and AVDD when EN-gate is High and Low.
En-gate high, DVDD = 5.60V and AVDD=7

I have a new issue, I had to change driver since the previous one failed. However since I changed when en-gate geet high all the out put (GH, SH, GL, SL) also get high.

I tried checking if my board had an issue but it seems fine.

0 Thibaut Milson over 5 years ago in reply to Thibaut Milson

Prodigy 175 points

Forgot to precise that when en-gate is low, both DVDD and AVDD are at 0

0 Hector Hernandez Luque over 5 years ago in reply to Thibaut Milson

TI__Expert 8980 points

Do you have separate grounds?

Also, with Enable high, please capture scopes of your grounds. I think your ground is not connected.

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DRV8302: Issue when connecting to load