How is electromagnetic interference generated during the operation of a stepper motor?

One of the main sources of electromagnetic interference is the rapid change in current within the motor windings. When current is switched on and off in the windings, it causes a sharp change in the magnetic field. This rapidly changing magnetic field radiates electromagnetic waves, thus generating electromagnetic interference.
Secondly, the contact and separation process between the motor's brushes and commutator also generates spark discharges. These sparks release a large amount of high-frequency electromagnetic energy instantaneously, becoming a significant factor in electromagnetic interference.
Furthermore, the iron core inside the stepper motor may experience magnetic saturation under the influence of a magnetic field. When the iron core reaches magnetic saturation, its permeability changes, leading to uneven magnetic field distribution and generating additional electromagnetic radiation.
In addition, vibration and friction between the motor's mechanical structure and components can also trigger electromagnetic interference. For example, rotor imbalance and bearing wear can cause instability during motor operation, resulting in irregular electromagnetic signals. In practical applications, taking CNC machine tools as an example, strong electromagnetic interference (EMI) generated by the stepper motors used in them can affect surrounding electronic equipment, such as sensors and encoders in the control system, leading to signal transmission errors or instability, and consequently affecting the machining accuracy and reliability of the machine tool.

Rapid changes in current within the motor windings are one of the main sources of EMI. When current is switched on and off in the windings, it causes a sharp change in the magnetic field. This rapidly changing magnetic field radiates electromagnetic waves, thus generating EMI.

Secondly, the contact and separation process between the motor's brushes and commutator also generates spark discharges. These sparks release a large amount of high-frequency electromagnetic energy instantaneously, becoming a significant factor in EMI.

Furthermore, the iron core inside the stepper motor may experience magnetic saturation under the influence of a magnetic field. When the iron core reaches magnetic saturation, its permeability changes, leading to uneven magnetic field distribution and generating additional electromagnetic radiation.

In addition, vibrations and friction between the motor's mechanical structure and components can also trigger EMI. For example, rotor imbalance and bearing wear can lead to instability during motor operation, generating irregular electromagnetic signals.

In practical applications, taking CNC machine tools as an example, strong electromagnetic interference from the stepper motors used in them can affect surrounding electronic equipment, such as sensors and encoders in the control system, causing signal transmission errors or instability, thus impacting the machining accuracy and reliability of the machine tool.

Another example is in medical equipment, such as high-precision imaging diagnostic equipment. Excessive electromagnetic interference from stepper motors can interfere with the normal detection and diagnostic results of the equipment.

To understand this more intuitively, we can imagine the motor as an "electromagnetic wave." When it operates, internal current changes, brush sparks, core magnetic saturation, and mechanical vibrations act like a "launch button," continuously emitting electromagnetic waves that interfere with the surrounding electronic environment.

To reduce the electromagnetic interference generated by stepper motors during operation, we can take various measures. For example, optimizing motor design by using appropriate winding structures and core materials; adding filtering components to the circuit to reduce high-frequency components of the current; providing proper shielding to prevent electromagnetic radiation; and ensuring the motor's installation and operating environment meets electromagnetic compatibility requirements.

In short, understanding the causes of electromagnetic interference during stepper motor operation is crucial for effectively suppressing and reducing its impact. This not only helps improve the motor's own performance and reliability but also ensures its stable operation in various complex electronic systems, promoting continuous development and progress in industry and technology.