Yes; It's possible. We have application for the evelator drive. Csutomer want use this for power supply was failure can use the battary to makes the evelator inposition and open the door . ,makes
people safein evelator when power shut down.

If you fed External DC voltage at DC + and -ve terminal there is no harm ,The internal precharge resistor will take care of cap.charging current. I think most of the standard drives are having this feature. But I don’t know how you will charge these batteries. You can not charge it using internal rectifier of Micromaster (Because it is having uncontrolled DC output and, it can not handle load current as well as charging current if used with Line supply)

Please find out how long this drive should work on Batteries.(consider it Time T ) . Also The DC link should be around 300volts for proper functioning. If you use 12 Volt batteries

You will need 300v/12v = 25 batteries.

For AH calculation of 7.5Kw Inverter

7500 X T = 12 X AH of batteries (7500 will be replace by 11000 for 11kw)

If it is a short time application let us say 10 minute

Then you will need approx. 104 AH batt.

Naturally your AH requirement will increase with Time and KW use.

But always refer Battery data sheet for exact calculations. Also this is considered without efficiency of the drive and o/p power factor.

If you are going to use a separate charger for batteries, you can feed Battery voltage to inverter through an appropriate diode. So when inverter is powered with AC supply there won’t be any charging current going to battery.