If you use a StayAwake routine, this is very easy to do using a Label, the LocationSensor and setting the Location.TimeInterval to 3 minutes ( 180000 ms). A little bit fancier way to build an app is
How to broadcast a GPS location and share the information on a map with others in real time..CloudDB. When your app goes to sleep, the sharing stops. 
OK. You probably need to use Google Map's api location sharing and it might work OK (as long as your App Inventor app is in the foreground). When your app goes into the background, I expect it would no longer work. Do I know that for a fact. No, so experiment. 