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LM5170EVM-BIDIR

Anna Edwards
Prodigy 160 points
Other Parts Discussed in Thread: LM5170, LM5122

I am working on a project looking at adding charging to a very small AUV. We are in the lab test phase of the project and are planning to use a Maxon BLDC motor operating in both motor and generation direction. When generating the motor will be producing a maximum of about 10V and charging a battery. When running as a motor power will need to come from the battery.

I am looking for a device to increase the 10V from the motor to high enough to charge a 12V battery. The device needs to be bi-directional in order to take power from the battery to run the motor in the motoring direction.

After the lab testing phase, I would like to also find a solution that can drive the motor and charge and discharge a battery.

  • 0
    TI__Guru* 78400 points

    Hi Anna,

    Thank you for reaching out.  Yes you can consider the LM5170.  How big is your power level?  When you say discharge, would you have to discharge it to down to 0V?

    Thanks,

    Youhao Xi, Applications Engineering. 

  • 0 in reply to Youhao Xi
    Prodigy 160 points

    Are max power produced is about 100w.  When I say discharged I mean taking energy from the battery.

    Anna

  • 0 in reply to Anna Edwards
    TI__Guru* 78400 points

    Hi Anna,

    If you battery is charged up to 12V, then you need to run buck mode when you discharge. However, if you continue to draw current from the battery, then the battery voltage may drop to below 10V.  To support your 10V rail for the motor, you will now operate the circuit is the boost mode.  If this is the case, you will have to use a buck-boost converter instead of the LM5170.  The LM5170 support bi-direction under the following condition:  the voltage on one end is always greater than the other end. 

    If you cannot use the LM5170 because the battery voltage can be higher and lower than the 10V rail, you will need to use a boost controller like the LM5122 to charge the batter to 12V, and used a LM34966 buck-boost to support discharging from the battery to the 10V motor rail.

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 160 points

    Thanks,

    I think that answers my question.