Axial Flux Permanent Magnets (AFPM) machines are a new kind of permanent magnet machines receiving more attention in the two recent decades. Many different structure of this machine was made. Axial flux machine has better "power to weight ratio", "efficiency", "smaller size" and "adjustable air gap" in compare whit radial flux machine. This article tries to describe some important structures of this machine and explain the main defect of it's and suggest an inventive structure to improve efficiency. Single phase equivalent circuit model of these machines are presented for performance analysis and thermal analysis.