The most important thing for ultra-efficient motors is the degree of process assurance. The process of continuously improving the efficiency of the motor is the process of continuously updating the product, and it is also a symbol of the comprehensive level of the national motor industry.
The design point of high-efficiency motors is to reduce various losses and improve motor efficiency. The measures taken include: applying special off-line tools, increasing the stator slot full rate, increasing the cross-sectional area of the copper wire; improving manufacturing precision, shortening the length of the coil end, enhancing the manufacturing quality of the punch and stator core, thereby reducing the iron loss And the excitation current and the copper loss caused by it; improve the rotor slot insulation process and reduce the load miscellaneous consumption; reasonably select the grade of the silicon steel sheet to reduce the iron loss and the stator copper loss.
1. Factors affecting motor efficiency
Motor losses include stator copper loss, iron loss, mechanical losses, stray losses, and more. There are many ways to reduce motor losses and improve efficiency:
The measures to reduce the copper loss of the stator mainly include reducing the stator resistance and shortening the length of the winding end; reducing the insulation, increasing the groove full rate, increasing the cross-sectional area of the wire, and reducing the resistivity of the electromagnetic wire by using a new material;
The measures to reduce the aluminum consumption of the rotor mainly include adopting a rotor groove shape with a large cross-sectional area and increasing the end ring cross section, improving the purity of the aluminum, reducing the rotor resistance, and the like;
The measures to reduce iron consumption mainly include the use of low-loss high-quality cold-rolled silicon steel sheets to reduce the eddy current loss of the motor; adjust the groove shape, select a reasonable magnetic flux density, reduce the fundamental iron loss; increase the core length and reduce the magnetic flux density to reduce the loss. Measures to improve the quality of the core manufacturing and ensure the insulation of the surface of the silicon steel sheet;
Measures to reduce mechanical consumption mainly include high-efficiency fan structure and reasonable air path, improve blade surface roughness, smooth air flow, improve fan efficiency, reduce wind and wear; select high-quality low-friction bearings, grease, reduce friction loss; The tolerance of the bit tolerance ensures the assembly quality of the motor and reduces the friction loss;
Measures to reduce stray loss mainly include the use of multiple slots in the stator slot, reducing the width of the stator and the slot of the rotor, and using non-magnetic materials at both ends of the core; using "sinusoidal" windings to weaken the higher harmonics in the magnetic field and weakening the additional losses. Appropriately increase the air gap, the rotor adopts fewer slots, adopts magnetic slot wedges, precisely controls the chute, and adopts special chutes.
2. Key manufacturing techniques to reduce motor losses
2.1 Technical measures to reduce mechanical consumption
The dimensions of the components are adjusted to the intermediate tolerances and the tolerances of the geometrical tolerances to ensure that the components are not deformed during transportation and assembly, and the quality of the motor assembly is ensured, thereby reducing the friction loss. Production experience shows that the bearing chamber rolling process can effectively improve the machining accuracy of the bearing chamber fitting parts and reduce the series of problems caused by the bearing running accuracy. The on-line quantitative oil filling technology of bearing grease can stably control the grease injection. The quantity of people to ensure the high-efficiency motor consumption of mass production is stable.
Rolling bearings are commonly used for bearings for small and medium-sized motors, using suitable high-quality lubricants. The traditional method is to manually apply grease to the bearing before the bearing is assembled, then assemble the bearing, and finally refill the motor with the oil gun. The problems of the method of manually adding grease are as follows: the amount of application is not easy to control, and the lubrication of the bearing parts and the mechanical loss are affected; the lubricating grease is easily contaminated, and there is oil stain around the motor parts after manual application; Inconvenient operation.
There is currently no device capable of quantitatively filling the motor. In order to effectively control the amount of grease added, after a large number of technical verifications, it is determined that the automatic grease filling machine, the oil pipe, the quick-change joint, etc. can be used to realize the automatic quantitative oil filling of the motor online assembly. The technology sets the oiling machine at the lower line of the motor assembly line. The motor does not need to be greased during the assembly process. When the motor is off the line, the quick-change joint of the automatic quantitative fueling device of the assembly line is connected with the motor oil-filling pipe, and the oil-filling machine can be started. Automatic quantification adds grease to the motor. The device has the advantages of convenient use, accurate quantitative, high efficiency and quickness, and is widely used in high-efficiency motors and other motors, and has obtained national utility model patents.
2.2 Technical measures to reduce stray loss
The outer circumference of the rotor is generally used in motor manufacturers. Due to the influence of the aluminum strips in the slot, the turning alternates from a hard silicon steel sheet to a soft aluminum. Due to the poor precision of the machine tool, the outer circumference of the rotor is unstable after processing. If a cutter is used and a part of the rotor outer diameter is small, the surface quality of the outer diameter of the rotor is poor, the burr is large, or the adhesion between the rotor surface is severe, resulting in large motor consumption, high temperature, and low efficiency. Therefore, it is particularly important to standardize the processing technology, parameters and quality inspection standards of the rotor outer round.
The magnetic field commutation frequency of the rotor is very low, and the hysteresis loss and eddy current loss generated by the rotor silicon steel sheet are negligible. The miscellaneous loss is mainly caused by the lateral current loss caused by the conduction between the aluminum strip and the outer circumference of the rotor punch. It is necessary to finish the car, roast, and special treatment of the outer circle to increase the resistance between the outer guide bar of the rotor and the punch, the punch and the punch, and reduce the stray loss caused by the lateral current. Through analysis, new tools and processes can be promoted in the finishing of rotors.
Most manufacturers use 450 positive and negative knives for the outer circumference of the rotor. The blade inclination is positive. Under the same cutting parameters, the axial component of the knives is large, which makes it easy to rewind and stick silicon steel sheets. The new process uses the 930 positive partial Sandvik machine clamping knife. Because the axial component of the tool is small, the silicon steel sheet can be reduced and stuck, which can effectively improve the surface quality of the rotor.