The noise of hydraulic oil pump motor can be basically summarized as electromagnetic noise, mechanical noise and ventilation noise, but how to distinguish various noises requires long-term experience accumulation. The editor of Dalan Motor mainly elaborated on electromagnetic noise suppression today.
1. Slot matching selection
For asynchronous motors, we must first select the appropriate number of stator and rotor slots. Generally speaking, the difference between the number of rotor slots and the number of stator slots is large, that is, when the so-called far slot is matched, the electromagnetic noise is small.
2. Slot slope
For slotted motors, skewed grooves can cause phase displacement in the radial direction along the axis of the motor, thus reducing the axial average radial force, thereby reducing noise. If the double chute structure is adopted, the noise reduction effect is better. The double inclined groove structure divides the rotor into two sections in the axial direction, and the skew direction of each section is opposite. There is also an intermediate ring between the two sections.
3. Winding type
In order to reduce the magnetomotive force harmonics, double-layer short-torque windings can be used; and fractional slot windings are prevented; sinusoidal windings should be used in single-phase motors.
Fourth, slot wedge material adjustment
In order to reduce the electromagnetic noise caused by the cogging, the magnetic slot wedge or the width of the slot of the stator and rotor can be reduced until the open slot is used.
V. Voltage requirements
Three-phase motors should maintain voltage symmetry as much as possible, and single-phase motors should operate in a nearly circular rotating magnetic field.
Sixth, parts quality control
In the manufacturing process of the motor, the ellipticity of the inner circle of the stator and the outer circle of the rotor should be reduced and the stator and rotor should be concentric to make the air gap uniform. Reducing the air gap flux density and using a larger air gap can reduce noise.
7. Structural stability
In order to prevent the electromagnetic force from resonating with the natural frequency of the cabinet, an appropriate elastic structure may be used.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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