Powering RoboClaw from boost converter
Powering RoboClaw from boost converter
Hello,
How would you suggest to connect RoboClaw 2x7A to boost converter? Currently it is attached as shown on the picture.
. Boost converter converts from 7.2V to 12V.
However, there are several concerns with this design:
1) Motor Accumulator power is wasted to charge Regen Accumulator.
2) Regen Accumulator is added only to handle regenerated power, but I don't use the regenerated power anyhow. Maybe I can replace Regen Accumulator with some other solution to handle regen power?
3) I guess that at some point in time, the Regen Accumulator will be overcharged.
RoboClaw is used to drive motors of differential steering robot designed to operate on a level surface in a room. I don't expect much regen as the robot is not going to drive downhill. I don't want to connect Motor Accumulator directly to RoboClaw because I don't want to depend on the level of charge of accumulator and I don't want to provide excessive voltage to the motors (which are rated for 12V).
I also asked similar question here http://electronics.stackexchange.com/qu ... controller, but didn't receive any suggestions to improve the schematics.
How would you suggest to connect RoboClaw 2x7A to boost converter? Currently it is attached as shown on the picture.
However, there are several concerns with this design:
1) Motor Accumulator power is wasted to charge Regen Accumulator.
2) Regen Accumulator is added only to handle regenerated power, but I don't use the regenerated power anyhow. Maybe I can replace Regen Accumulator with some other solution to handle regen power?
3) I guess that at some point in time, the Regen Accumulator will be overcharged.
RoboClaw is used to drive motors of differential steering robot designed to operate on a level surface in a room. I don't expect much regen as the robot is not going to drive downhill. I don't want to connect Motor Accumulator directly to RoboClaw because I don't want to depend on the level of charge of accumulator and I don't want to provide excessive voltage to the motors (which are rated for 12V).
I also asked similar question here http://electronics.stackexchange.com/qu ... controller, but didn't receive any suggestions to improve the schematics.
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Basicmicro Support
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- Joined: Thu Feb 26, 2015 9:45 pm
Re: Powering RoboClaw from boost converter
DC motors are usually safe to run at +-50% their rated voltage(too low and you pull too much current which can over heat the motor and too high you can damage the brushes). As suggested in your stackexchange message I would just run the batteries in series instead of parallel, even at full charge those batteries will only output around 8.2-8.4v(and only for a very short time) so worse case you are at 16.8v which is under the 18v max I would recommend for a 12v motor. This also elliminates the regen losses since the regen will go back into the battery(though not nearly as much as is coming out so you dont need to worry about over charge).
Note if you go with this circuit and your regen accu can handle all the regen energy you voltage will go up. Possibly dramatically and damage your electronics.
Alternatively I'd move up to the next size cell count on your battereies. Im assuming these are NiMh so go to 10cell Nihm(1.2v per cell) instead of the 6 cell batteries you are using now.
The circuit looks ok but I wouldnt want to run something so complex for no apparent gain. You are also assuming the boost circuits will function correctly in parallel.
Note if you go with this circuit and your regen accu can handle all the regen energy you voltage will go up. Possibly dramatically and damage your electronics.
Alternatively I'd move up to the next size cell count on your battereies. Im assuming these are NiMh so go to 10cell Nihm(1.2v per cell) instead of the 6 cell batteries you are using now.
The circuit looks ok but I wouldnt want to run something so complex for no apparent gain. You are also assuming the boost circuits will function correctly in parallel.
Re: Powering RoboClaw from boost converter
Thank you for explanations. With this
Now I'm just curious. You wrote
the puzzle got solved and I will do now as you suggest.DC motors are usually safe to run at +-50% their rated voltage
Now I'm just curious. You wrote
How regen accu could damage electronics if it is behind rectifier?Note if you go with this circuit and your regen accu can handle all the regen energy you voltage will go up. Possibly dramatically and damage your electronics.
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Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: Powering RoboClaw from boost converter
can should have been can't
If the regen isnt sunk by the regen accu the voltage will start to rise instead. When using systems that cant sink the regen current(eg power supplies) you usually need to burn the energy off with an active switch to engage a large wattage resistor across B+-. Storing the energy is fine if it can handle all the energy(the big filter caps handle a small amount of this on the board) but the amount of energy is large and it would take an unreasonable amount of capacitance to handle all of it.
If the regen isnt sunk by the regen accu the voltage will start to rise instead. When using systems that cant sink the regen current(eg power supplies) you usually need to burn the energy off with an active switch to engage a large wattage resistor across B+-. Storing the energy is fine if it can handle all the energy(the big filter caps handle a small amount of this on the board) but the amount of energy is large and it would take an unreasonable amount of capacitance to handle all of it.