stepper motor driver constant current under load, motor driver powering off losing brake effect
If your stepper motor driver does this, and there is no way to override it, you have a crappy stepper motor driver.

Most sane stepper drivers have that sort of behaviour as an option, if they have it at all. 

Looking at what documentation I could find for that driver, it claims "In static, current automatically in half", so it's not disabling the motors, merely reducing the power when the axes are static. 

Considering it's a Chinese no-name product, I think the only reasonable options are: 


Switch to a properly supported driver.
Modify your driver to behave properly.


We can possibly help with 2, but you would need to be prepared to damage a driver or two, and possibly not succeed.