Calculation Of Electromagnetic Parameters And Analysis Of Performance For Canned Motor With Solid Rotor

Canned motor is a special electric machine for complement of canned electric pump. For the motor is immerse in the liquid, so there are cans on the surfaces of stator and rotor, which is effective in electric insulating and resistance corrosion. The can usually is made of stainless steel which has high electric resistivity, high mechanical intensity and non-magnetic conductivity. The usage of cans increases the length of air gap, greatly affect the motor's performance, and bring some problems in design and analysis of motor, such as parameter calculation, magnetic saturation, and loss computation.This paper summarizes canned motor's development and research situations. Arming requirements of canned motor's structure characteristics and engineering design, the paper deeply studies the electro- magnetic design and performance analysis of laminated rotor and solid rotor canned motor by computing magnetic field.Firstly, two double-speed and double-winding canned motors are taken for example, whose performance parameters are calculated under different conditions, such as starting, ideal no-load, non-ideal no-load and full load by the 2D Finite Element Method of eddy current field. The results are compared with test values and the cans'effect on results is analyzed. Secondly, the paper deserves the motor's dynamic performance curves (such as current, electromagnetic torque, load torque and speed) under no-load starting and full-load starting by dynamic finite element method. In the same time, the maps of magnetic flux density distribution at different time are gained. Mathematic model of load torque and equivalent torque for friction loss are built in the computation and the relations between amplitude and speed are considered which make the starting performances more accordant with practice. At last, because many designers of my country are willing to study canned motor with equivalent circuit, the paper presents a method of extracting the equivalent impedances of stator's and rotor's cans and solid rotor by 2D eddy current field calculation, and builds the canned motor's equivalent circuit with lumped parameters. The paper analyzes the effect of the can's relative permeability's variation on the motor's performance and cans'losses, which provided theory gist for engineering design. The design formulas of general three-phase induction motor are modified and electromagnetic design software for canned motor is compiled.