UK DC/DC Voltage Conversion

[xpistos]

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Hi Guys,

Looking for a bit of advice for my kids power wheel car.

I have a 24v to 12v converter which I need to use for the steering motor as its still 12v. Currently the controller has 2 wires which connect to the steering motor, the polarity of the wires switches to turn either left of right.

With the polarity switching am I still able to use a regular dc/dc converter?

Thanks

Chris

 

[newfutile]

As long as the switching of polarity is done after the converter I don’t see an issue

 

[xpistos]

As long as the switching of polarity is done after the converter I don’t see an issue

That's the problem, the switching of the polarity happens directly from the controller, so I'm seeing either +24v or -24v immediately. Not sure how to step this down to 12v for the motor

 

[Avo Mk8]

Random idea, but could you use two of the voltage converters, each protected with an appropriate polarity beefy diode in front as a sort of 'or' gate, making one converter for each polarity, then combining the outputs after an appropriate polarity diode on each output. A little bit of voltage drop, but it might work?
Or maybe some sort of dropper? What 12V current are you dealing with?

 

[newfutile]

As long as the startup time for the regulator is longer than any capacitor on the output that might be a good idea , or a large power resistor roughly equivalent to the resistance of the load.

 

[Avo Mk8]

As long as the startup time for the regulator is longer than any capacitor on the output that might be a good idea , or a large power resistor roughly equivalent to the resistance of the load.

Trouble is the load is a motor (might even be the traction motors?) so I thought a purely resistive dropper would not be appropriate the varying mechanical load (meaning a varying electrical load!).
High power zeners (equivalent) on a huge heatsink??!!

 

[Avo Mk8]

Or another way using 24V coil and suitable contact rating relays, and a single 24 to 12V regulator.

Pair of relays (as below) driven from the 24v, one via diode one way round, other via diode the other way round, so with +24V one relay operates, and with -24V the other operates.
The 12V regulator output connected to the +/- input to the relays as per the article below!

Homebuilt Rovs

Homebuilt Remote Operated Vehicles

www.homebuiltrovs.com

 

[xpistos]

I'll be honest that's all way over my head! Looking into it further its more complicated then I thought. After tuning with the remote an opposite voltage is sent via the controller unit to recentre the wheels. This voltage actually steps down gradually from +-24v to 0v, once the voltage drops below +-12v the converter does nothing anyway and the wheels get stuck left or right.

Think the easiest solution will be to find a 24v motor for the steering and go from there

Thanks for all the advice regardless

 

[James]

This might seem like a daft idea, but bear with me.

the original motor is probably rated at 24v continuous rating, if it is only used on and off for steering it has a duty cycle of less then 10% by my estimate.

the thing that kills motors is hear build-up, so just leave the original motor in place and over supply it with 24v and odds are all will be fine. worst case is the motor dies and you have to replace it (what you are looking at doing anyway?)

 

[marconi]

Please post details of the controller, voltage converter and steering motor.