How to suppress interference in the PMS electronic switch for electrical force measurement?

Electronic switches (such as MOSFETs and IGBTs) in PMS operate in high-speed switching mode, and their generated dv/dt and di/dt are the main sources of interference. Suppression requires a comprehensive approach involving device selection, drive optimization, and circuit layout. For device selection, prioritize MOSFETs with low gate charge (Qg), low drain capacitance (Coss), and integrated freewheeling diodes to reduce switching losses and oscillations.

Drive optimization: Use an appropriate drive voltage (e.g., 12V) to avoid underdrive; add a series resistor Rg (2-20Ω) to the gate to control the turn-on speed; use an active Miller clamp circuit if necessary.

Circuit layout: Follow the "minimum power loop" principle, minimizing the loop area formed by the switching transistor, freewheeling diode, and input capacitor; separate the drive loop from the power loop.

Simultaneously, add a high-frequency absorption capacitor (e.g., a 1μF ceramic capacitor close to the switching transistor) to the DC bus and an RC snubber (e.g., 100pF + 10Ω) to ground at the switching node. Using soft-switching techniques (e.g., ZVS/ZCS) can fundamentally reduce interference. With suppression, voltage overshoot of electronic switches can be reduced by 70%, switching losses by 25%, and radiated emissions can meet EN 55032 Class B standards.