MCT8316Z: How to achieve smooth braking on a downhill slope

Chu Allen

Part Number: MCT8316Z

Tool/software:

Hello,
I am using MCT8316Z for BLDC control and inspecting the car. When the car works normally on flat and uphill roads, it moves steadily forward.
When the car is going downhill and needs to use the brake, it will shake and cannot be stably controlled to stop. Is there any recommended solution to achieve downhill speed control and braking?
thank you!

over 1 year ago

0 Joshua Horlander Cruz over 1 year ago

TI__Mastermind 24470 points

Hi Chu,

If possible, could you provide a capture of the phase current and VM when the car is downhill and braking?

Regards,

Joshua

0 Chu Allen over 1 year ago in reply to Joshua Horlander Cruz

Intellectual 820 points

Hi Joshua，

I provide MCT8316Z circuit below, plears help check. The waveform will be provided later.

0 Chu Allen over 1 year ago in reply to Joshua Horlander Cruz

Intellectual 820 points

Hi Joshua,

How does MCT8316Z achieve uniform speed under external forces (thrust and resistance)?

0 Joshua Horlander Cruz over 1 year ago in reply to Chu Allen

TI__Mastermind 24470 points

Hi Chu,

I am waiting for a reply from our systems team on the original braking question.

For your second question: since the MCT8316Z does not have a speed loop, the output speed of the MCT8316Z can very when external force is applied. To have the speed be uniform across varying external force, a speed loop will need to be implemented externally. Example code for an external speed loop is provided in the following reference design: https://www.ti.com/tool/TIDA-01496

Regards,

Joshua

0 Joshua Horlander Cruz over 1 year ago in reply to Joshua Horlander Cruz

TI__Mastermind 24470 points

Hi Chu,

We believe the issue you are having with downhill braking maybe cause by the MCT8316Z uses low-side braking. This braking method does not have the strongest braking torque to hold or control the load which is likely leading to the motor shaking. You could try first reducing the input speed command and then enabling the Brake signal after the motor slows down.

We also recommend taking a look at the MCF8316C. This device offers different braking methods other than low-side braking. For this application case, Align Braking maybe a more suitable option since it can provide a higher braking torque. For more information about Align Braking, see section 7.3.19.5 of the MCF8316C-Q1 datasheet.

Regards,

Joshua

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MCT8316Z: How to achieve smooth braking on a downhill slope