EMI Solution of Motor
Background analysis:
When the motor is running, the radio frequency of different types of mobile phones will be interfered with：
a. The interference of coreless motor has 3~5dB in the frequency band around 900HZ .
b.The coreless motor has different interference to different frequency band：800MHz:-12dB,900MHz:-12dB,1800MHz:-19dB,2000MHz:-22dB.
c.The coin motor has 3 ~ 20dB interference in all frequency bands.
d.The core motor has no interference at present.
Basic theory of electromagnetic compatibility Electromagnetic compatibility
In the same electromagnetic environment, the equipment can work properly under the interference of other equipment, and at the same time, it does not interfere with other equipment.
Electro Magnetic Compatibility (EMC)。
Three Elements of EMC: Interference Source, Sensitive Equipment and Coupling Path.
Coupling Path: Space Coupling, Wire Coupling (Power Line or Signal Line)
Electromagnetic compatibility evaluation index
Reasons for DC motor interference:
a.Dc motor in the moment of commutation, due to the sudden change of current arc caused by the loop or radiation interference;
b.Dc motor in the moment of commutation, the direction of coil current changes, and the coil inductance causes loop interference;
c.Interference caused by coil inductance and radiated outward through external wires or FPCB;
d.Magnetic field interference caused by leakage of motor magnet steel and alternating magnetic field of coil;
e.The high frequency on and off state of the PWM power supply circuit of the motor produces a wide frequency range and more intense interference.
