What percentage should the deviation of inductance values among the three phases of a three-phase common-mode inductor be controlled within?

The typical requirement is ≤±5%, with the following reasons:

Balanced current distribution: Excessive inductance deviation in a three-phase system can lead to neutral point offset, resulting in circulating currents or uneven EMI suppression.

Standard basis: Industrial power supplies or motor drive applications (such as photovoltaic inverters) typically require a deviation of ±3% to 5% to ensure symmetrical filtering performance.

Implementation method: Adopt high-precision winding technology (synchronous winding of three windings) and consistent magnetic core materials. Before leaving the factory, inductance is measured phase by phase and sorted and paired using automated equipment.

Risk warning: Deviations exceeding 10% may lead to failure of zero-sequence current suppression or residual differential mode interference.