Low-speed Permanent-magnet Submersible Motor’s Design And Research

Progressive cavity pump oil well systems has the advantages that other mechanical systems do not have, which is especially suitable for the oil recovery in the heavy oil wells, sand wells, gas wells, horizontal wells and directional wells. In order to improve the stability of the system, to achieve the direct drive capability of the submersible motor, the main purpose of the paper is to design a low speed permanent magnet direct drive submersible motor. The low speed permanent magnet submersible motor is a special motor, and its design method is different from conventional permanent magnet synchronous motor. In this paper, based on the basic electromagnetic relationship of permanent magnet synchronous motor, the problems and issue of low-speed direct-driven permanent magnet motor in design are derived and analyzed, and the finite element verification is carried out.The performance requirements of the permanent magnet motor with low speed and high torque require the use of fractional slot concentrated winding design. Due to the difficulty of the submersible motor’s coil assembly, the number of conductors per slot is generally not more than 12. For this purpose, the method of solving the supply voltage of the motor is derived based on the basic electromagnetic relation of the permanent magnet motor. By comparing the performance of the motor with three different slot number combinations, this paper chooses the best performance combinations as the design blue print of the motor in this paper. In the process of motor design, the relationship between inner diameter of the stator and the performance of the motor are analyzed, motor axial length and the optimal stator inner diameter is obtained. The influence of the length of the permanent magnet on the performance of the permanent magnet is analyzed. In this paper, the circuit’s calculation model of the permanent magnet eddy current loss of the permanent magnet synchronous motor with fractional slot is established, which can calculate the eddy current loss of the permanent magnet rapidly and accurately, suitable for engineering calculation. The general design blue print and topological was settled based on the above calculation and analysis, To obtain the optimum designing of the stator, motor slot parameters is analyzed and calculated.The no-load and rate load characteristics of the designed motor are analyzed by using the finite element software ANSYS Maxwell, and the rationality of the design is verified.