Electromagnetic Design Elements of Single-Phase Series-Excited Motor

　　

　　In the process of product development, different people to complete the same product design task, there must be different design schemes, but can achieve the purpose of meeting the design requirements. That is to say, product design problem is a multi-solution problem, not a unique solution problem. In the current market economy environment, the market competition is very fierce. In addition to the advantages of product cost performance, there is also an important point that the product development cycle is short, in order to meet the needs of users as soon as possible, otherwise the market will be lost. Therefore, in the process of product development, we should take users as the center, communicate with users in time, and complete the task of product design and development more quickly, better and economically.

　　

　　I. Design Guidelines in Product Development

　　

　　1. Make the best use of the existing similar product process and equipment conditions.

　　

　　2. Make the best use of parts and components of existing similar products.

　　

　　3. Make the best use of the existing stock of raw materials.

　　

　　4. On the premise of meeting the requirements of use, the design scheme should be convenient for mass production, reduce the labor intensity of operators as far as possible, and improve production efficiency and product qualification rate.

　　

　　5. The design scheme should fully consider the possibility of product specification extension, such as power extension, speed extension, voltage level extension, and double insulation extension.

　　

　　2. Design methods adopted in product development according to different situations

　　

　　1. Provision of prototype by users

　　

　　(1) Keep the shape and installation size unchanged, and the performance should not be lower than the design of the user's prototype.

　　

　　Non-destructive mapping and comprehensive analysis of user prototype are carried out.

　　

　　A. Performance test of user prototype. The performance parameters of the user prototype are: voltage, frequency, input power, input current, output power, speed, power factor, efficiency and so on.

　　

　　(B) Measuring the stator winding and rotor winding resistance of the user's prototype.

　　

　　(C) Measure the temperature rise of the user's prototype. The temperature rise is measured according to the working system of the motor required by the user. In addition to the working system, there are several user requirements:

　　

　　A) Keep the input power of the motor unchanged;

　　

　　B) Keep the input current of the motor unchanged;

　　

　　C) Keep the motor output torque unchanged.

　　

　　(D) Measuring the length of stator core and rotor core, the outer circle of rotor core, the inner circle of stator core, the arc angle of stator pole, the length of air gap, the yoke width of stator core, the tooth width of rotor core, the shaft hole of rotor core, and the outer circle and inner hole of commutator; counting the number of slots of rotor core and the number of commutator plates; judging the motor; Whether it is double insulation or not; Measure and estimate the diameter of stator winding and rotor winding of user prototype for reference. The above measurement should be carried out without destroying the user's prototype. If some items can not be measured, they can not be measured.

　　

　　(E) After comprehensive analysis based on the test and measurement results, the existing stamping sheets which are close to the user prototype are selected for electromagnetic design so as to meet the performance requirements of the user prototype without changing the shape and installation dimensions of the motor.

　　

　　(2) Keep the installation dimension unchanged and keep the shape dimension unchanged as far as possible, but users hope that the performance of the design is better than that of the prototype.

　　

　　After comprehensive analysis based on the above test and measurement results, the existing motors close to the user prototype are selected and tested according to the desired performance of the user. According to the test data and results, the electromagnetism design of the motor punch is carried out, but the installation dimension of the user prototype should be kept as constant as possible, and the radial dimension should not exceed the user prototype's dimension, while the axial dimension can be changed slightly with the help of the user's opinions. 。 In short, users should be guaranteed to use the motor.

　　

　　(3) Maintain installation dimension, but users put forward new requirements for performance, allowing slightly adjustable design of shape dimension.

　　

　　In addition to testing and measuring the user prototype like (1), the user prototype should also be tested according to the new performance requirements of the user (including temperature rise test). After comprehensive analysis based on the test and measurement results, the existing motors which are similar to the users are selected, and the performance test (including temperature rise test) is carried out according to the new requirements of the users. Then, maintain the installation size and make necessary adjustments to the outline size. Electromagnetic design is carried out according to the selected motor punch. If through the analysis of electromagnetic design, it is not reasonable to use the selected motor punch, then we should design the motor punch while maintaining the installation size, and make the electromagnetic design to meet the user's requirements.

　　

　　(4) Maintaining the same performance of the prototype and reducing the cost of the product

　　

　　A In the design of motor structure:

　　

　　Replace metal parts with engineering plastics, do not use step shafts at all; try to use fewer cutting or non-cutting parts; improve motor heat dissipation and ventilation.

　　

　　B In the field of electromagnetic design:

　　

　　After improving the ventilation and heat dissipation of the motor, the consumption of the effective material of the motor is reduced; if the effective material of the motor is reduced after improving the insulation grade, the insulation grade of the motor can be increased if the cost is reduced; the stator adopts deep groove structure, which enlarges the inner circle of the stator core and the outer circle of the rotor core, and enlarges the stator core appropriately according to the specific situation. Subpole arc width is used to reduce the amount of effective material used in motor.

　　

　　2. The situation that the user did not provide the prototype

　　

　　(1) Users provide the design of shape and installation dimensions, performance parameters and product cost requirements.

　　

　　Select the existing phase according to the shape and installation size provided by users, performance indicators and product cost requirements.