1. How to improve the efficiency of the motor?
Someone asked: What are the ways of high-efficiency motors? Is it not as simple as using more materials? I have been selling motors for many years, and I have never been under such great pressure recently. I clearly feel that customers are more and more demanding on motors, especially in terms of high efficiency and energy saving. Yes, after all, each company has cost pressure. High-efficiency motors are indeed more than just using more materials. To some extent, multi-purpose materials may be the main factor restricting efficiency improvement.

The pressure of energy and environmental protection is forcing the motor to upgrade its efficiency
The energy crisis and environmental protection issues have become the barometers of the normal operation of various industries, and people are paying more and more attention to the efficiency of energy utilization. Although electric motors are already very efficient at converting electrical energy into mechanical energy, there is no end to achieving maximum efficiency. In order to reasonably match the motor with the application, it is also necessary to continuously carry out design optimization and technological innovation, and even realize high efficiency→super high efficiency→super super high efficiency.

How to improve motor efficiency?
The study of motor efficiency is essentially the process of analyzing various types of losses and figuring out the key factors that affect various types of losses.
●Reduce the loss when the current flows through the winding. One of the most straightforward ways to improve motor efficiency is to reduce armature winding losses. For example, by increasing the slot area so that more copper is used to increase the cross-sectional area of the winding and thereby reduce its resistance, the losses when current flows through the winding are reduced.
●Core loss control. The core loss is related to two factors: the magnetic flux density and the frequency in the core. Usually the frequency of the power supply is fixed, so in order to reduce the loss of the iron core, the method of lengthening the iron core is generally adopted.
●Efficiency improvement is closely related to material consumption. In order to achieve the required energy consumption level, it is inevitable to increase the amount of copper used and the volume of the iron core. But the reduction in loss is not always positively correlated with the increase in copper and iron consumption. When the cross section of the iron core and coil increases to a certain extent, the loss will increase instead, because the increase in the volume of the iron core will also increase the loss of the iron core and coil. If it exceeds the reduction caused by the decrease in resistance and the unsaturated iron core, the efficiency On the contrary, it decreases. There may be a point beyond which losses actually increase when the core volume is increased. Similarly, for a given flux density, eddy current losses can be reduced by using thinner laminations.
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●Technological innovation improves efficiency. Break through the closed-slot rotor and cast copper rotor and other technical forbidden areas, and the efficiency level of the motor will achieve a qualitative leap.

Efficiency improvement is not as simple as using multiple materials

Efficiency improvement will indeed come at the cost of more effective material consumption, but due to the existence of effective materials such as copper wires and iron cores, various losses are inevitable. The product of the loss value per unit of material and the total amount of material consumption is relatively certain There is always a minimum value under stable conditions. The process of achieving the minimum value or optimizing the design is a traditional method of improving efficiency. How to improve relatively stable conditions or improve material grades and break through the bottleneck of traditional technology depends on innovative technologies.

2. Analysis of the reasons for the low efficiency of the motor
Large stator copper loss
● Stator winding resistance is high: (1) The wire resistivity is large or the wire diameter is small, the wire diameter is uneven or the number of parallel windings is small; (2) The wiring is wrong or the welding is not firm; (3) The actual number of turns is more than the design value.
● Large stator current: (1) Other losses are large; (2) The three-phase imbalance is caused by the asymmetry of the stator winding; (3) The air gap between the stator and the rotor is seriously uneven; When the resistance will be less than the normal value; (5) winding wiring is not correct.

Large rotor copper loss

● The resistance of the rotor winding (or guide bar) is high: (1) the resistivity of aluminum (copper) is relatively high; Thin strip problem; (3) The stator slot is not neat (expressed as notch sawtooth), there are wrong pieces and reversed pieces, resulting in insufficient effective area of the rotor slot; (4) The structure of aluminum is loose due to improper selection of cast aluminum parameters, directly This leads to an increase in resistivity; (5) The material does not meet the requirements, such as the use of alloy aluminum for ordinary aluminum rotors; (6) The use of wrong rotors, etc.
● The rotor current is large; (1) The wrong rotor is used; (2) The wrong aluminum is used when casting aluminum, for example, the alloy aluminum rotor uses ordinary aluminum; Cause excessive rotor transverse current.

Large stray loss

● Improper choice of stator winding type or pitch;

● Improper selection of stator and rotor slot fit;
● The air gap is too small or seriously uneven;
● Serious short circuit between the rotor guide bar and the iron core;
● Stator winding ends are too long, etc.

Large iron loss

● The quality of silicon steel sheets is poor or the materials are used incorrectly, for example, 600 materials are used instead of 800 grades; motor factories that purchase iron cores should pay special attention to this problem.

● Insulation between stator core sheets is not good: (1) The insulation treatment is not carried out or the treatment effect is not good; (2) When the iron core is laminated, the pressure is too high, which damages the insulation between the sheets; (3) The bore of the stator is turned or the file is repaired When the iron core is removed, it will cause a short circuit between the core pieces and the pieces (this problem exists in most iron core manufacturers).
● Insufficient number of iron core pieces and insufficient iron weight: (1) Insufficient number of chips (missing pieces); (2) The stacking pressure is small and not compacted, and the direct result is insufficient iron weight; (3) The burr on the punched sheet is large , The iron weight cannot be guaranteed when the iron length meets the requirements; (4) The paint is too thick, which is a direct quality problem of the silicon steel sheet.
● The magnetic circuit is too saturated, and the relationship curve between no-load current and voltage is seriously bent.
● The no-load stray loss is relatively large, because it is included in the iron loss during the test, which makes the iron loss appear larger.
● When the winding is removed by fire or electric heating, the iron core will be overheated, the magnetic conductivity will be reduced and the inter-chip insulation will be damaged. This problem mainly occurs when the winding is taken out by fire after the winding is faulty; some motor manufacturers have found a way to take out the winding by soaking in lye.

Large mechanical loss
● The quality of the bearing or bearing assembly is not good. At this time, the bearing will be seriously heated or rotate inflexibly.
● The external fan is used wrongly (for example, a 4-pole fan is used for a 2-pole motor) or the blade angle is wrong; according to the conventional design, the fan of a 2P motor is relatively small, and the method of reducing loss by adjusting the fan is very effective, but the premise is that Ensure the temperature rise performance of the motor.
● The machine base and the bearing chambers of both end covers are not in the same axis.
● The diameter of the bearing chamber is small, which causes the outer ring of the bearing to deform under pressure, resulting in increased friction loss of the bearing; this situation may also lead to overheating and failure of the bearing.
● There is too much lubricating grease in the bearing chamber or the quality of the lubricating grease is not good. This problem is obvious on high-voltage motors. Ms. Shen once did a test, and the highest point of the bearing cap temperature was 10K higher than the lowest point. Open it and check that there is indeed a lot of grease accumulation at this position.
● Stator and rotor rub against each other, which is what we call sweeping. When the stator and rotor rub against each other, it will not directly cause the motor to stop rotating, but the loss of the motor will increase significantly.
● The axial size of the rotor is not correct, causing the two ends to be stuck, making the rotation inflexible.
● Oil seals or water throwing rings and other components are improperly installed or deformed, resulting in large frictional resistance.
● With fan motor, the fan rubs against the associated parts, causing the rotation to be difficult.