Hello everyone,

We are testing electric motors in our production facility and would like to recover the energy generated during testing instead of dissipating it as heat.

The test bench power is approximately **11 kW**.

We are looking for practical advice on the best way to implement an energy regeneration system. For example:

* Returning energy back to the AC grid.
* Charging a battery energy storage system.
* Using a common DC bus with multiple drives.
* Other reliable and cost-effective solutions.

Our main goals are improving energy efficiency, ensuring reliable operation, and keeping the system practical for industrial use.

If you have experience with similar projects, could you share your recommendations? Which architecture would you choose for an 11 kW test bench, and what are the main advantages and disadvantages?

Thank you in advance for your suggestions.

 

I presume you are just testing the motor, anything used for mechanical load is not part of the test. A modular drive system should be able to be set up to achieve what you want. One drive for the test motor and one drive connected to another motor, maybe servo, maybe with forced cooling. The test motor would be mechanically coupled to the second second motor, this would be used as the load, it would be applying a torque in one direction but be driven in the opposite by the test motor, regenerating power into the modular drive which would have a common DC bus bar. No battery or feed to grid required, this would be mostly self sustaining with a small draw from the grid due to losses.

 

1.) couple a discarded / decommissioned wind turbine to your motor & you can synch it to grid. These are still good working ones, only the tower structure & blades will be end of life, the generators and converters will be good to reuse.

2.) Or like GMcc said use a Drive (AC/DC) which have regeneration mode to leverage the inertia to generate power and send it back to the grid. But don't forget to have a Dynamic Breaking resistor as protection, if the DC Bus voltage exceeds the safe voltage limits of your drive.

 

I presume you are just testing the motor, anything used for mechanical load is not part of the test. A modular drive system should be able to be set up to achieve what you want. One drive for the test motor and one drive connected to another motor, maybe servo, maybe with forced cooling. The test motor would be mechanically coupled to the second second motor, this would be used as the load, it would be applying a torque in one direction but be driven in the opposite by the test motor, regenerating power into the modular drive which would have a common DC bus bar. No battery or feed to grid required, this would be mostly self sustaining with a small draw from the grid due to losses.

We're testing frequency converters.
The test is lengthy.
During the test, we use heavy loads.
Therefore, energy recovery is necessary.

 

Or like GMcc said use a Drive (AC/DC) which have regeneration mode to leverage the inertia to generate power and send it back to the grid. But don't forget to have a Dynamic Breaking resistor as protection, if the DC Bus voltage exceeds the safe voltage limits of your drive.

We're thinking of connecting a test motor to a DC motor.
Using the motor's power, we'll charge the batteries.
Once they're charged, we'll conduct further tests using the batteries.

Perhaps someone has done something similar and could share their experience or a rough outline.

 

We're testing frequency converters.
The test is lengthy.
During the test, we use heavy loads.
Therefore, energy recovery is necessary.

Your original post was about testing motors, if you are actually testing frequency converters then that is a different problem. Could use the similar solution but with just one drive for the load motor that can do regeneration and active front end, this would feed back into the mains supply which the test frequency convertor would also be connected to, no batteries required.

 

I had gone through this several decades back.

What we used is Drive (Under Test) -> Motor -> Generator/Motor -> Drive(In regeneration mode) ->Grid !

PS: We used a DC Motor as Generator with General Electric's Innovation series 2000 HP rated Drive.
It had built in regeneration mode which we leveraged.
Not sure of its availability in market now, since almost the entire world moved towards AC Drives.

 

For an 11 kW test bench, active front-end drives excel. They return regenerated energy directly to the grid. This delivers excellent efficiency and reliable industrial performance. Common DC buses are another strong option. Regenerated energy powers other connected drives efficiently. Excess energy still needs safe management. Battery storage works when grid export isn't allowed. However, batteries increase cost, maintenance, and system complexity. Braking resistors remain the simplest solution. Unfortunately, they waste regenerated energy as heat. My preferred architecture combines an active front-end with a common DC bus. Keep a braking resistor for emergency overvoltage protection.