Designing a generator circuit using BLDC and ESC

Discussion in 'Power Electronics' started by nozelle, Jul 9, 2016.

  1. nozelle

    Thread Starter New Member

    Jun 23, 2016
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    I want to make a battery charging circuit using BLDC motor as a generator.
    Whenever I rotate the motor at high speeds I am getting an increasing voltage and current at the input ends of the ESC. I know these is because of the MOSFETS within ESC configuration acting as a bridge rectifier and conversion from 3 Phase AC to DC is carried out by the Power MOSFETS.
    I want to convert the increasing DC voltage from ESC to a constant DC voltage so i could use it to charge a battery. How do I do this?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    2,379
    How are you using a ESC ? This is a PWM motor driver?
    The output of a BLDC motor is 3 phase when backfed and can be simply rectified with a 3ph bridge.
    You would need to govern the output level, either by rpm control or by regulation.
    Max.
     
  3. nozelle

    Thread Starter New Member

    Jun 23, 2016
    3
    0
    Yes this is a PWM controlled ESC which will perform the 3-phase bridge rectification for me. Now how do I regulate the changing DC voltage so I could use it to charge a Battery I am getting high voltage and current. within the range 0-24V and 0-70 Amps respectively.
     
  4. #12

    Expert

    Nov 30, 2010
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    What is an ESC?
    What is the voltage rating of the battery you want to charge?
    What is the amp-hour rating of the battery you want to charge?
    Do you just want a fast charge? multi-stage? float charge? automatic shut off?
     
  5. nozelle

    Thread Starter New Member

    Jun 23, 2016
    3
    0
    ESC: Electronic Speed Controller.
    I need the voltage output to be a constant 5V and max current output I can get.
    I need fast charging. How do I get this done?
     
  6. #12

    Expert

    Nov 30, 2010
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    If the battery can use all the 70 amps, just connect the battery to the rectifier and the battery will load down the generator to 5 volts.

    If the battery can't use up 70 amps, you will need a 5 volt regulator that can pass 70 amps.
    If you know what kind of battery it is, you can find the voltage to set the regulator for.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,565
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    If you are back feeding a RC BLDC motor you will get a three phase generated voltage, this is very different in nature to the ESC which is used to drive the BLDC only.
    All you would need to do is place a 3ph bridge rectifier on the three motor output leads.
    But this will require some kind of regulation, either electronically or by RPM control.
    Max.
     
  8. tcmtech

    Well-Known Member

    Nov 4, 2013
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    1,671
    Us knowing what you are 'Fast Charging' at 5 volts and its specs would be very helpful.

    I for one know of very few devices that are designed to be charged from a 5 volt based power source that can draw more than 2 amps being that's typically the maximum amperage capability of any USB socket.

    As for a source for a cheap DC- DC converter that has a 5-volt output that will work on a ~8 - 30 volt DC input most any common automotive type USB output power adapter will work.
     
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