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scr driver circuit for battery charger

Tha fios agaibh

Aug 11, 2014
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I have several 3phase 36volt battery chargers (fork lift battery) with bad control boards. Replacement of these obsolete boards are hard to find and near the cost of replacing the entire charger.

I was wondering if it's feasible to design a simple circuit that could drive the 3 internal scrs to replicate the 40vdc output originally derived by the control board. I assume I would need to trigger the scr gates with pwm at 120deg apart from each other. I am not concerned at this point about a complete charging circuit but more the fundamentals of how the driver section works.

Unfortunately, I have no schematic to work from. I'm hoping to get some ideas here.
 

Arouse1973

Adam
Dec 18, 2013
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Couldn't you bypass the SCRs and just use a 40 Volt PSU instead?
Just a thought.
Adam
 

Tha fios agaibh

Aug 11, 2014
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The combination of 3ph transformer and scr's (thyristors) are what generates the aprox 40vdc power (160amps) for charging battery.
The control board was what generated pwm signals to the scr gates. There are single DC to PWM circuits available that would work, but I need to synchronize the three pulses so to equalize/minimize the primary load.

3 phase power is 120deg apart.

If I could find a chip/circuit that will drive the 3 scr's by pulse width modulation at 120degrees apart I can build a retrofit board.
 
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Tha fios agaibh

Aug 11, 2014
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Something like the IRU3055 might work (3 phase pwm). but without a schematic to work from I'm lost.
 
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