How to suppress circulating current when EPS power devices are connected in parallel?

When multiple power devices are connected in parallel in an EPS (Electric Power Component), circulating currents can occur due to parameter dispersion and differences in drive signals. This not only increases losses and thermal stress but may also trigger additional differential-mode EMI. Measures to suppress circulating currents include:

1. Strict device selection: Devices connected in parallel should ideally be from the same batch, with matched parameters (e.g., Vgs(th), Rds(on)).

2. Drive signal symmetry: Ensure consistent path length and impedance from the drive signal to the gate of each device; use independent gate resistors if necessary.

3. Current-sharing inductor: Connect a small inductor in series in each parallel branch (or utilize PCB trace inductance) to achieve dynamic current sharing using its impedance.

4. Optimized layout symmetry: The layout of the power loop and drive loop should be symmetrical to ensure consistent parasitic parameters in each parallel unit.

5. Independent source/emitter sampling and Kelvin connection: Provide each device with an independent source/emitter connection back to drive ground to avoid voltage differences on the power ground path that introduce drive interference. Suppressing circulating currents helps improve parallel reliability and overall EMC.