Mastering these key technologies can make motors super efficient

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The most important thing about high-efficiency motors is the degree of process assurance. The process of continuous improvement of motor efficiency is a process of continuous product upgrading, and it is also a symbol of the comprehensive level of a country's motor industry.

The key point of designing high-efficiency motors is to reduce various losses and improve motor efficiency. The measures taken include: applying special offline tools to increase the stator slot fill rate and increasing the cross-sectional area of ​​the copper wire; improving manufacturing accuracy, shortening the length of the coil end, and strengthening the manufacturing quality of punching sheets and stator cores, thereby reducing iron consumption and excitation current and the copper loss caused by it; improve the rotor slot insulation process to reduce load miscellaneous losses; rationally select the grade of silicon steel sheets to reduce iron losses and stator copper losses.
1. Factors affecting motor efficiency
Motor losses include stator and rotor copper losses, iron losses, mechanical losses, stray losses, etc. There are many ways to reduce motor losses and improve efficiency:
Measures to reduce stator copper losses mainly include reducing stator resistance and shortening the length of winding ends; thinning insulation, increasing slot fullness, and increasing wires Cross-sectional area, using new materials to reduce the resistivity of electromagnetic wires, etc.;

Measures to reduce rotor aluminum consumption mainly include using a rotor groove shape with a large cross-sectional area, increasing the end ring cross-section, and improving the aluminum purity, reducing rotor resistance, etc.;
Measures to reduce iron loss mainly include using low-loss high-quality cold-rolled silicon steel sheets to reduce the eddy current loss of the motor; adjusting the groove shape and selecting a reasonable magnetic flux density. Reduce the fundamental wave iron loss; increase the length of the iron core and reduce the magnetic flux density to reduce losses; improve the manufacturing quality of the iron core and ensure the insulation of the silicon steel sheet surface;
Measures to reduce mechanical loss, mainly including high-efficiency fans Structure and reasonable air path, improve blade surface roughness, make the air flow smooth, improve fan efficiency, and reduce wind friction loss; use high-quality low-friction bearings and grease to reduce friction loss; improve shape and position tolerance accuracy to ensure the assembly quality of the motor , reduce friction losses, etc.;
Measures to reduce stray losses mainly include using multiple slots in the stator slot, reducing the width of the stator and rotor slots, using non-magnetic conductive materials at both ends of the core; using "sinusoidal" "The winding is to weaken the higher harmonics in the magnetic field, weaken the additional loss, appropriately increase the air gap, use less slots in the rotor, use magnetic slot wedges, accurately control the slope degree, and adopt special slopes and other measures.
2. Key manufacturing technologies to reduce motor losses
2.1 Technical measures to reduce mechanical losses
Part dimensions adopt intermediate tolerances and Improve the precision of geometric tolerances, ensure that parts do not deform during transportation and assembly, and at the same time ensure the assembly quality of the complete motor, thereby reducing friction losses. Production experience shows that the use of bearing chamber rolling technology can effectively improve the machining accuracy of the bearing chamber mating parts and reduce a series of problems caused by the bearing operating accuracy; the use of online quantitative oil injection technology of bearing grease can stably control the injection of grease. manpower to ensure stable mechanical consumption of high-efficiency motors for mass production.
The bearings of small and medium-sized motors generally use rolling bearings and use appropriate high-quality lubricants. The traditional process method is to manually apply lubricating grease into the bearing before assembly, then assemble the bearing, and finally use an oil gun to re-lubricate the motor. The problems with this manual method of adding grease are as follows: the amount of application is difficult to control, which affects the lubrication of the bearing parts and mechanical losses; the lubricating grease is easily contaminated, and there is oil stain around the motor parts after manual application; there are many processes, Inconvenient operation.


Currently there is no device that can quantitatively replenish oil to the motor. In order to effectively control the amount of grease added, after extensive technical verification, it was determined that automatic grease injection machines, oil pipes, quick-change joints, etc. should be used to realize automatic quantitative oil injection during online assembly of motors. This technology sets the oil injection machine at the end of the motor assembly line. The motor does not need to be filled with grease during the assembly process. When the motor goes off the assembly line, connect the quick-change joint of the automatic quantitative oil injection device of the assembly line to the motor oil injection pipe and start the oil injection machine. Automatically and quantitatively grease the motor. This device has the advantages of easy use, accurate quantification, high efficiency and speed. It is currently widely used in high-efficiency motors and other motors, and has obtained a national utility model patent.
2.2 Technical measures to reduce stray losses
The outer circle of the rotor is generally processed by turning technology in motor manufacturers. Due to the influence of the notched aluminum strips, the turning alternates from hard silicon steel sheets to soft aluminum. Due to the poor accuracy of the machine tool, the dimensions of the rotor outer circle after processing are unstable. If one-tool turning is used and the machining allowance of part of the rotor outer diameter is small, the surface quality of the outer diameter of the rotor will be poor, the burrs will be large, or the adhesion between the rotor surface sheets will be serious, resulting in high miscellaneous consumption of the motor, increased temperature, and low efficiency. Therefore, it is particularly important to standardize the rotor cylindrical turning process, parameters, quality inspection standards, etc.
The magnetic field commutation frequency of the rotor is very low. The hysteresis loss and eddy current loss generated by the rotor silicon steel sheet itself can be ignored. The miscellaneous losses mainly come from the aluminum guide bar at the notch and the outer circle of the rotor stamping sheet. The transverse current loss caused by the conduction requires finishing, baking, and special treatment of the outer circle to increase the resistance between the rotor outer circle guide bar and the punched piece, and between the punched piece and the punched piece, and reduce the stray loss caused by the transverse current. . Through analysis, new tools and processes can be promoted and applied during rotor finishing.
Most manufacturers use a 450 positive offset tool when turning the outer circle of the rotor, and the blade inclination angle is a positive value. Under the same cutting parameters, the axial component of the tool is larger, which can easily cause the silicon steel sheet to break. Rewinding and adhesion. The new process uses the 930 positive-bias Sandvik machine tool. Because the axial component of the tool is small, it can reduce the silicon steel sheet rewinding and adhesion, and can effectively improve the surface processing quality of the rotor.