zcv variable Potential conflicting usages of identifier

Hello,

What's a ZCV variable ? I am trying to generate code from a model that contains several referenced models, and I am getting this error:

Potential conflicting usages of identifier 'ZCV_pidController_T': a global identifier from 'speed_controller', and a global identifier from 'current_controller' This conflict may be resolved by either increasing the maximum identifier length on the Identifiers pane of the Configuration Parameters dialog box or by changing the name of the conflicting identifier.

I tried increasing the identifier max length it did not work