How to Select the Appropriate Filter for A6 Servo Motors?
I. Definition of a Filter
A filter is an electronic component capable of extracting or suppressing specific frequency components from a complex signal.
II. Why Do Servo Motors Need Filters?
Servo drives use Pulse Width Modulation (PWM) technology to control the motor, outputting a voltage that is a series of high-frequency switching pulses. This creates two main issues:
- Common-Mode Noise: High-frequency noise generated between the motor phase lines and the ground line.
- Differential-Mode Noise: High-frequency noise generated between the motor phase lines themselves.
These noises can lead to:
- Motor Cogging, Abnormal Noise, Overheating: High-frequency noise results in impure current, causing the motor to vibrate minutely instead of rotating smoothly, generating extra heat and audible whining.
- Encoder Interference: Noise can interfere with the precise encoder feedback signals, causing position errors and potentially triggering drive alarms.
- Affecting Other Equipment: High-frequency noise generated by the servo system can travel through power lines or radiate through space, affecting other sensitive equipment (like sensors, PLCs) on the same electrical network.
III. Filter Selection
As shown in the diagram, the filter compatible with our A6 servo motors is an input-side filter used to suppress both common-mode and differential-mode noise. Its primary functions include:
- Preventing transient pulses and noise from the power grid from affecting the normal operation of the drive.
- Blocking the high-frequency switching noise generated by the drive from feeding back into the power grid, thereby meeting Electromagnetic Compatibility (EMC) regulatory requirements.
When selecting a model, pay attention to the following key parameters:
- Rated Voltage: Must match the drive's input power supply voltage.
- Rated Current: Should be greater than or equal to the drive's maximum continuous input current.
- EMC Compliance Level: Select a grade that complies with the standards of the target market.
- Connection Method: Ensure compatibility with the wiring of the power supply and the drive.
During installation, the filter should be placed between the power supply and the drive, close to the power supply, to reduce noise interference and facilitate subsequent maintenance. For equipment requiring grounding, the filter's ground wire must be connected to the equipment's ground line to ensure an effective ground connection.
Updated on: 30/09/2025
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