How to attenuate noise in the MC power supply loop of a motion controller?

To attenuate noise in the MC power supply circuit of the motion controller, a multi-stage filtering network and optimized PCB layout are required. At the power module input, a first-stage EMI filter is installed, including a CMZ series common-mode choke, X capacitors, and Y capacitors to suppress noise from the mains power. At the DC output of the switching power supply, a second-stage LC filter is configured, using high-frequency characteristic ferrite beads or PBZ series power inductors, and a combination of low-ESR MLCCs and electrolytic capacitors to cover a wide frequency band.

Decoupling capacitors are placed at each power pin of the controller core chips such as DSPs and FPGAs, forming a third-stage filter from the chip to the board level. During layout, filtering components must be placed close to noise sources or power inputs, and grounding pins should be connected to the ground plane with the shortest path. High-current paths, such as motor drive power supplies, should use wide traces and be isolated from other sensitive lines. The attenuation effect is evaluated by measuring the power supply ripple and noise spectrum. If noise is prominent at specific frequencies, ferrite beads can be added or capacitor values adjusted accordingly. For noise from the switching power supply itself, modules with soft-switching technology can be considered.