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Power Supply Design


ekoppes
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I'm using a Geo Brick LV 8-axis controller (GBD8-C0-442-10T00000) to drive 5 DC Brush Motors (rating on motor is 30W 24V 2.1A 2000rpm). Since the controller is capable of far more power output than these 5 motors will draw (capabilities listed are 50A peak, 25A continuous, 60VDC Nominal, 80VDC Max), I would like to design a power supply that would allow me to do higher power functions in the future if needed. My questions:

 

1. Are there any suggestions as to a preferred power supply?

 

2. I assume the controller is capable of modifying a higher volt supply (say 45V 60V) before sending it to the lower volt motor (here 24V). Is this correct?

 

3. This project has a limited budget. Would it be advised to purchase a smaller supply that is designed for parallel connection (sized to work for this project) and then purchase additional power supplies to hook up in parallel when future projects arise?

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Hi,

 

The only requirements are listed on page 16 of the Geo Brick LV manual, which I will reprint here for you:

 

1971762496_powersupplyGeoBrickLV.thumb.png.6114bba422d0ab017e3a702fe5a53eb5.png

 

Regarding your desire to use parallel power supplies in the future, some manufacturers design their power supplies to be used like this (e.g. Omron), but be careful you use the correct power supply, because "load current imbalance may cause the rated output current for one Power Supply to be exceeded" (http://www.ia.omron.com/product/cautions/22/precautions_for_correct_use.html).

 

Please let us know if you have additional questions.

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  • 5 weeks later...

Thank you for your help! I found a power supply that I would like to use:

 

http://www.alliedelec.com/images/products/datasheets/bm/Mean_Well/70069759.pdf

 

Ideally, I would use the 48 volt version to power the Bus (we have a 24V DC supply for the Logic). This would allow us to use higher voltage devices in the future if necessary. The current project has the controller running 24V motors on 5 of the axis now. Unfortunately, I cannot find anywhere in the manual where it states that the controller is capable of converting this 48V input to a 24V output. Does anyone have experiences that show this is possible (or let me know if I just missed it in the manual)?

 

As before, thank you for the help!

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Hi,

 

There is a difference between the Bus Voltage that you supply to the drive, and the amount of voltage the drive is capable of putting out. Basically, the drive can put out an essentially continuous range of voltages up to and including the applied Bus Voltage. It does not always output the same voltage as the Bus Voltage, but varies as you command different output magnitudes either through Open Loop or Closed Loop commands. Does that answer your question?

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We highly advise against using the same power supply for both logic and bus:

 

- You never want to power-up the logic and bus simultaneously, this can cause issues.

- You definitely do not want the bus power to come up before the logic (safety purposes).

- If your bus fluctuates due to back emf, it might sag the power supply and flicker or temporarily kill the logic side (not good).

- Please review the Power on/off procedure described in the manual on page 25.

 

I strongly recommend that you keep them separate.

 

The bus voltage level is up to you to decide/design. Smaller motors can always operate with higher bus voltage, Ixx66 (page 194 for DC Brush motors) is used to scale/limit the voltage for a particular channel.

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These answered my questions perfectly, thank you!

 

I appreciate the warning with about the logic power being separate. We do have a separate 24VDC supply for the logic power on hand and this is for just the Bus Power.

 

Thank you for pointing me to Ixx66 as this fits perfectly with what we're doing here. I have also bookmarked Ixx69 for use if we start using a motor of that type.

 

Thank you for all the help!

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