The application of permanent magnet variable frequency submersible electric pumps and permanent magnet synchronous motors in the pump is characterised by: high efficiency, light weight, small size, large flow rate, light movement, adjustable speed, adjustable head height, and flow rate size. At the same time, another feature of permanent magnet synchronous motors is that the speed does not change with the voltage of the power grid, and the HeadFlow rate can still be maintained when the voltage changes, especially when the voltage is low, which is not found in traditional asynchronous motor axial flow pumps.