Electrical – Protect power supply from regenerative drive

batterieshigh-currentmotorpower supply

I am running a 3KW motor on a big 24Vdc power supply (Meanwell RST-5000), through a frequency drive.
When stopping the motor, however, I occasionally get a regenerative backcurrent that trips the internal overvoltage protection in my power supply. The voltage ramps up to about 28.5V. The supply is protected against this, but it does have to be manually reset and breaks the workflow.

What is a good solution to prevent this? Can I just hook up a big (+- 100Ah) Lead-acid battery in parallel to the power supply? Or will this give me other issues?

Please keep in mind that there are huge currents involved (+- 125 A)

Best Answer

I've implemented 3 solutions to this problem:

  1. A capacitor bank sized large enough to absorb the worst-case regen energy without tripping the OVP. In your case it might be expensive and huge, but has minimal losses.
  2. A resistor bank with a comparator. Also big, less expensive but you waste the energy. Easy to implement and the "standard" solution when a capacitor bank would be too big or expensive.
  3. For really large regen energy that happens often, a grid-tie inverter that takes the regen energy and puts it back into the grid. You may need a backup resistor bank in case the transfer switch is down (due to power failure) to avoid damage or shutdown from large regen energy. This is the most expensive and complicated solution but also has low losses.