Character Controller and Moving Rigid Bidy

I have a scene with a moving platform and a character controller. I've been using a rigidbody for the platform and have been setting the rigidbody.velocity variable for the movement of it. The character controller moves via the controller.Move() method.

My problem is that any time the character controller stands on top of the platform it forces it to move downward. In addition if the character falls fast enough it will pass through the platform entirely or clip into it.

What is the best way to create a moving platform that a character controller can interact with? Or how can I fix these problems I'm having?

Thanks for any help.