Motors are directly related to energy conservation and emission reduction policies. Many national engineering and municipal project bidding motors must meet the IE3 energy efficiency assessment requirements, especially those exported to European countries. These requirements are almost the lowest threshold.

However, for motor manufacturers, it is too difficult to improve efficiency, and there are many bottleneck technologies to be broken through, such as loss measurement, determination of key factors affecting motor efficiency, loss causes and quantitative analysis, etc. The following is a breakdown and analysis of Hino Electric starting from the causes of increased loss.

1. Large stator copper loss

1. The stator winding resistance is large:

(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) Wrong wiring or weak welding;

(3) The actual number of turns is more than the design value.

2. Large stator current:

(1) Other losses are relatively large;

(2) Three-phase unbalance due to stator winding asymmetry;

(3) The air gap between the stator and rotor is seriously uneven;

(4) Because the number of turns is less than the normal value, the resistance will be less than the normal value at this time;

(5) The winding wiring is incorrect.

Second, the rotor copper loss is large

1. The resistance of the rotor winding (or bar) is large:

(1) The resistivity of aluminum (copper) is relatively large;

(2) There are air holes or impurities in the cast aluminum rotor bar or end ring, or there are local thin strip problems due to casting defects;

(3) The stator slots are not neat (shown as notch serrations), and there are staggered and reversed pieces, resulting in insufficient effective area of the rotor slots;

(4) Due to improper selection of cast aluminum parameters, the organization of aluminum is loose, which directly leads to an increase in resistivity;

(5) The material does not meet the requirements, for example, the ordinary aluminum rotor uses alloy aluminum;

(6) Use the wrong rotor, etc.

2. Large rotor current:

(1) Use the wrong rotor;

(2) Wrong aluminum is used when casting aluminum, for example, ordinary aluminum is used for the alloy aluminum rotor;

(3) The lamination of the rotor core is not solid, resulting in a large area of aluminum entering between the sheets, resulting in excessive rotor transverse current.

3. Large stray loss

1. Improper selection of stator winding type or pitch;

2. Improper selection of stator and rotor slots;

3. The air gap is too small or seriously uneven;

4. The rotor bar and the iron core are seriously short-circuited;

5. The ends of the stator windings are too long.

4. Large iron loss

1. The quality of the silicon steel sheet is poor or the material is used incorrectly. For example, the 600 material is mistakenly used to 800. This kind of downgrade is used; the motor factory that purchases the iron core should pay special attention to this problem.

2. The insulation between the 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 stacked, the pressure is too large, so that the insulation between the sheets is damaged;

(3) When the inner bore of the stator is turned or the iron core is repaired, the iron core piece and the piece are short-circuited (this problem exists in most iron core manufacturers).

3. The number of iron cores is insufficient and the iron weight is not enough:

(1) Insufficient number of chips (missing chips);

(2) The stacking pressure is small and not compacted, and the direct result is insufficient iron weight;

(3) The punching burr is large, and the iron weight cannot be guaranteed when the iron length matches;

(4) The paint is too thick, which is a direct quality problem of the silicon steel sheet.

4. The magnetic circuit is too saturated, and the curve of the relationship between no-load current and voltage is more serious.

5. The no-load stray loss is large, because it is included in the iron loss during the test, which makes the iron loss appear larger.

6. When the winding is removed by fire or electric heating, the iron core will be overheated, the magnetic permeability will be reduced, and the insulation between the sheets will be damaged. This problem mainly occurs when the winding is removed by burning after the winding fails; some motor manufacturers have sought a way to remove the winding by lye soaking.

5. Large mechanical loss

1. The quality of the bearing or bearing assembly is not good. At this time, the bearing will be seriously heated or the rotation will be inflexible.

2. The external fan is wrongly used or the angle of the fan blades is wrong; according to the conventional design, the 2P motor fan is relatively small, and the method of reducing the loss by adjusting the fan method is very effective, but the premise is to ensure the temperature rise performance of the motor.

3. The machine base and the bearing chambers of the two end caps are not coaxial;

4. The diameter of the bearing chamber is small, which causes the outer ring of the bearing to be deformed under pressure, resulting in increased friction loss of the bearing; this situation may also cause the bearing to overheat and fail.

5. Too much grease added to the bearing chamber or the quality of the grease is not good. This problem is obvious on high-voltage motors. Ms. Shen has done a test. The highest point of the bearing cover temperature is 10K higher than the lowest point. After opening and checking, there is indeed a lot of grease in this position.

6. The stator and rotor are rubbed, which is what we call the sweeping. When the stator and rotor are rubbed, it will not directly cause the motor not to rotate, but the motor loss will increase significantly.

7. The axial dimension of the rotor is incorrect, causing the two ends to die, making the rotation inflexible.

8. The oil seal or water throwing ring and other components are improperly installed or deformed, resulting in greater frictional resistance.

9. With a fan motor, the fan and the related parts are rubbed and the rotation is not smooth.