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Karthik DM
Karthik DM
Associate III
February 24, 2021
Solved

Current limiting in STM32 for the motor controller

  • February 24, 2021
  • 2 replies
  • 1491 views

Hello,

I'm working with a BLDC motor controller, I'm currently facing an issue with my current limiting algorithm.

Can anyone please help me with how the current limiting works in the motor controller.

and whats the relationship between RMS current and torque.

This topic has been closed for replies.
Best answer by Cristiana SCARAMEL

Hi @Karthik DM​,

Besides the microcontroller, what other devices are you using to drive the BLDC motor?

For example, motor driver with integrated power stage, or gate drivers with discrete power stage.

In both cases, you can implement a peak current control monitoring the voltage across the shunt resistor (Rs). This power resistor must be connected in a common point with the three low-side power source.

0693W000008vvSSQAY.png 

The shunt resistor voltage is compared to a reference voltage (Vref) that is proportional to the target current (Ipk-target) with the following equation:

Vref = Rs x Ipk-target

I hope these info can help you.

2 replies

Cristiana SCARAMEL
Cristiana SCARAMEL
Technical Moderator
March 3, 2021

Hello @Karthik DM​,

for a better support, could you share more details about your application?

Which hardware are you using?

Which control algorithm are you implementing?

The output torque is directly proportional to the motor current (RMS value) through the KT (constant torque) that is specific to the motor.

Let us know these details and any other information that may be helpful in answering your question.

"If you feel a post has answered your question, please click ""Accept as Solution"""
Karthik DM
Karthik DMAuthor
Associate III
March 3, 2021

Hello @Cristiana SCARAMEL​ 

Currently, I'm working with the STM32F302R8Tx controller.

I'm developing six-step motor control logic.

Please tell me more information on current limiting in function

thanks

Cristiana SCARAMEL
Cristiana SCARAMELAnswer
Technical Moderator
March 3, 2021

Hi @Karthik DM​,

Besides the microcontroller, what other devices are you using to drive the BLDC motor?

For example, motor driver with integrated power stage, or gate drivers with discrete power stage.

In both cases, you can implement a peak current control monitoring the voltage across the shunt resistor (Rs). This power resistor must be connected in a common point with the three low-side power source.

0693W000008vvSSQAY.png 

The shunt resistor voltage is compared to a reference voltage (Vref) that is proportional to the target current (Ipk-target) with the following equation:

Vref = Rs x Ipk-target

I hope these info can help you.

"If you feel a post has answered your question, please click ""Accept as Solution"""
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