I want to store energy from multi-kW motor fed by VSI in regenerating parts of the cycle to use it during later motoring parts.Flywheel solutions are not attractive due to high cost, maintenance need, etc.
It is not possible to directly store AC for later usage.
Since you don't want to use flywheel solutions (rotational energy storage), you could also use a capacitor (electric field, also expensive) or battery systems (chemical energy storage, charging power is technologically capped).
I don't want to store AC, but energy regenerated back from AC motor connected connected to an voltage source inverter is converted back to DC and accumulated on the DC bus!
So if anybody is working or knows about a cost-effective/commercial solution to this known application when it is not possible to return back energy to the supply.
I have done the exactly same work what you have mentioned.
The regenerative energy is fed back to the dc link. What we have done is we have connected a supercapacitor to the dc link via a high gain bi-directional dc-dc converter.
During regeneration, the energy is stored by the ultracapacitor and later this energy is used to run the motor also providing fault ride-through capabilities. The dc-dc converter would also help to maintain the dc link of the VSI and breaking chopper can be avoided as this inherently provides overcharge protection.
We have already done an evaluation review of storage technologies initially for marine energy harvesting but this review could be helpful for other applications; i am attaching the paper for you.