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DRV8312: What's regenerative braking ?

Tiger Chan
Intellectual 290 points
Part Number: DRV8312

Hi, 

Can I just simply TURN OFF all 3 phase HIGH SIDE Mosfets and only TURN ON 3 phase LOW SIDE Mosfets with some duty cycle, and when my bike down-hill it can regenerative energy back to DC bus ? and I can control the LOW SIDE Mosfet's duty cycle to control the value of regenerative energy (of course I will closely monitor both Voltage and Current) ? 

Thanks,

Danny

  • 0
    TI__Mastermind 26046 points

    Hi Danny,

    Yes, this methodology is correct. This is similar to the diagram below. 



    You can use low side shunt resistors from GND_x to GND as well for current feedback with external CSAs and phase resistor dividers at the OUT_x pins for current and phase feedback. 

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    Intellectual 290 points

    Hi Aaron,

    thanks for your quick reply.

    Aaron Barrera said:
    You can use low side shunt resistors from GND_x to GND as well for current feedback with external CSAs and phase resistor dividers at the OUT_x pins for current and phase feedback. 

    you mean phase current feedback for over current protection right ? 

    the pic you enclosed, the blue line are current path on LOW SIDE Mosfet only, do you mean the current will also flow on UPPER SIDE Mosfet's forward diode  (turned off)  then recharge the battery  ?

    Thanks,

    Danny

  • 0 in reply to Tiger Chan
    TI__Mastermind 19590 points

    Hey Danny,

    We are currently out of the office on holiday. We will reply to your post tomorrow when are back in the office. We appreciate your patience!

    Best,

    Isaac

  • 0 in reply to Tiger Chan
    TI__Mastermind 18916 points

    Hi Danny, 

    Will need a bit more time to follow up on this - aiming to give an answer by Tuesday next week. 

    Best Regards, 
    Andrew

  • 0 in reply to Tiger Chan
    TI__Mastermind 18916 points

    Hi Danny, 

    For the implementation of regenerative braking, may be best to consult pages 3-4 of this technical article: 

    I am personally not too familiar with regenerative braking itself, but can help clarify some of the comments above

    • Yes, there's a 'sensing/shunt' resistor in between GND and the low-side FET source of the power stage MOSFET to implement OCP sensing 
    • in cases where you have external CSA's inputs connected across the two ends of each Rsense resistor, it can tell you how much current is flowing between SHx and GND, through the low-side MOSFET. 

    For the steps to implement regenerative braking, please see the article I linked and reference these two tables for the switching sequence: 

    Best Regards, 
    Andrew