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AC Regulator for Bike Lamps

Discussion in 'General Electronics Discussion' started by abuhafss, Dec 17, 2016.

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  1. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    Hi

    I am looking to build an AC voltage regulator for motorbikes. I have posted a thread here.
    http://forum.allaboutcircuits.com/threads/motorcycle-voltage-regulator-ac-regulation.129921/

    Alec, who is also a member of this forum, has helped me to some extent, but the issue is still unresolved. I summarize the discussions below.

    Most of the bikes have dual stator coils for single phase AC generation. One coil supplies AC voltage which is rectified/regulated to 14.4V for battery charging and other electrical system (excluding Head Lamps and Tail Lamps). The second coil is connected in parallel to the lamps and an AC regulator circuitry. Please see the diagram below for better understanding.
    4-pin Regulator (B) Wiring.png

    The DC regulator and the AC regulator are housed in a single unit, as shown.
    20161128_151602.jpg

    The Chinese unit has a larger cavity for the PCB than the OEM unit which means the latter has fewer components. Both units barely get warm on operation. I have built the Chinese circuit which works fine, but according to my experience they are not reliable because they fail after sometime. Here is the schematic of the Chinese circuit for reference.
    2016-12-06 (2).png

    I want to build something reliable with minimum components, like the OEM. I failed to rip off the OEM unit but was successful enough to find two SCRs BT151 which were not even attached to the body (means they didn’t required heatsink).

    The inductance of the coil is 1.635mH and resistance 1.2Ω.
    Without regulator, the output is 7V RMS at idle and 75V RMS at 6000RPM.
    With OEM regulator & no load, the output is 7V RMS at idle and 12V RMS at 6000RPM.
    With OEM regulator & lamps on, the output is 6V RMS at idle and 12.1V RMS at 6000RPM.
    All measurements with a moving coil voltmeter.

    I have tried following circuits but could not get the desired result i.e. 12-14V RMS.

    2016-12-16 (1).png
    The triac got hot at idle, so I could not get proper reading at 6000RPM.

    2016-12-16 (2).png
    The zener and the darlington were very hot, D4 was hot..output was 12.2V at 6000RPM with lamps on.

    2016-12-16 (3).png
    The SCR was hot and output was 7.5V at 6000RPM with lights on.

    2016-12-16.png
    Not yet tried this.

    I shall appreciate if anybody can help me out. I have attached the asc files of all the schematics.
     

    Attached Files:

  2. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    I think I should simplify my issue.
    Forget all the circuits which I have worked on. Can anybody suggest me a circuit which can regulate 12-75VAC RMS from the generator to 12-14VAC RMS? The circuit should have minimum possible components and most important of all, the input wire will be the output. Please see the diagram below:

    2-Pin Regulator Wiring.png
     
  3. Alec_t

    Alec_t

    2,939
    799
    Jul 7, 2015
    That restricts the regulator to being a shunt one, with inevitable high heat dissipation (in the regulator and/or the coil). A series regulator could be more efficient, but would be more complex.
     
  4. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    Yes, you are right. A series regulator would not be compatible to the wiring on the bike which restricts the regulator to have a shunting device, be it a SCR, Triac or a BJT. The heat dissipation can be shared between two parallel shunting devices.
     
  5. Colin Mitchell

    Colin Mitchell

    1,417
    313
    Aug 31, 2014
    Firstly, you should consider switch-mode as it will produce very little heat.
    How much current do the lamps take?
     
  6. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    Hi Uncle Colin

    Nice to hear from you.
    The Head Lamp (dual filament) is 35+35W and the Tail Lamp (dual filament) is 8.5+8.5W.
    As discussed in post #4, I am restricted to use shunt type regulator because the Input and Output share a common wire. Please see the diagram in post #2.
     
  7. Colin Mitchell

    Colin Mitchell

    1,417
    313
    Aug 31, 2014
    You are killing up to 60v and 7 amps.
     
  8. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    I have to because, the bike's electrical system is designed that way. Even the OEM unit does it.
     
  9. abuhafss

    abuhafss

    348
    11
    Aug 3, 2010
    I removed the aluminum body of Honda (OEM) unit.
    The whole circuit is concealed inside the epoxy measuring 30x18x6mm.
    The circuit has 2 x BT151 (SCRs). And it includes both DC regulator and AC regulator circuitry, as shown in the diagram in post #1.

    20161222_142246.jpg
     
    Last edited: Dec 22, 2016
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