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Current regulation of a DC motor

Tihomir Zilic
Intellectual 350 points
Other Parts Discussed in Thread: DRV8833, TMS320F28377D, DRV8301, DRV8850, LM629

Dear,
I need your professional suggestion how to do a current regulation of a DC motor. I have Delfino TMS320F28377D microcontroller in wich I calculate a motor current reference. Signal from the microcontroller goes to the driver (DRV8833 H-bridge) and then to the electromotor (Faulhaber Coreless DC Motor (2338S006)). To make current regulation I need motor current sensing (measure how much current is motor draining).  As I can see that driver DRV8833 can not sense current, it can only limit it.

My questions are:

1. How to have current sensing of motor armature?

2. Is there some chip which does current regulation? 

3. What do you propose to make current regulation?

Thank you!

  • 0
    TI__Guru** 114905 points
    Hi Tihomir,

    Sensing current can be done with a current sense amplifier of a VPROPI circuit.

    An example of a current sense amplifier can be seen in the DRV8301 datasheet. Although internal to the device, external components can be used to create the circuit. An example of a VPROPI can be seen in the DRV8850 datasheet.

    In both of the cases shown, the current is monitored when actively driving the outputs. When in current regulation, the current is not monitored. If you desire to monitor the current during regulation, extra steps need to be taken.
  • 0 in reply to Rick Duncan
    Intellectual 350 points
    Hi Rick,
    thanks for the answer and suggestions.
    a) I need to monitor the current during regulation
    b) I want to use this monitored current as a feedback for a PID current controller. Could you tell me is there some chip that is the PID controller with input (a difference between reference current and monitored current) and with output (PWM voltage for the motor driver )?
    Thank you!
  • 0 in reply to Tihomir Zilic
    TI__Guru** 114905 points
    Hi Tihomir,

    You may need external circuitry to monitor the current during regulation. The current shunt (correction from original reply) amplifier is a good choice. It can be set for both positive and negative currents. The DRV8301 datasheet example (Figure 6) shows the connections.
  • 0 in reply to Rick Duncan
    Intellectual 350 points

    Hi Rick,
    thank you again.
    Could you help me with one more question.
    If I measure armature current using some of your proposed methods, and now I want to use some controller like LM629 to make a feedback current control, is there some controller like LM629 I could use.

    Note: LM629 takes position measurement from encoder (and proceeds it to its internal PID control), but I want a similar chip which takes current measurement instead position.

    Thank you!