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Inverter PCB IGBT Module Burnout (E6/H6 Error)

Likely causes

IGBT module thermal breakdown from overcurrent (exceeds 600V/15A rating)

Check: Measure IGBT G-S terminals in multimeter diode mode — normal: tens of kΩ, burned: 0Ω or short circuit. Diagnosis possible in 30 seconds. Also check for gate resistor damage.

What to do: 1) Replace IGBT module (after measuring G/S resistance). 2) Clean heatsink and reapply thermal grease (≤0.5°C/W product). 3) Install surge protector (SPD) or verify existing SPD operation. 4) When replacing entire inverter PCB, always verify manufacturer S/N compatibility.

Dried thermal grease between heatsink and IGBT → overheating

Check: Remove IGBT module and inspect heatsink contact surface — dried or discolored grease (yellow→brown) requires reapplication. Measure IGBT external temperature — above 75°C during operation indicates overheating.

What to do: Completely degrease contact surfaces with IPA (isopropyl alcohol), then apply new grease uniformly (thickness ≤0.3mm). Use product with thermal resistance ≤0.5°C/W. Monitor IGBT temperature after reassembly.

Aging DC link electrolytic capacitors → unstable voltage → IGBT stress

Check: Measure DC link voltage: normal range 280–320V DC (220V system). Measure ripple with oscilloscope — above ±15V indicates capacitor failure. Measure capacitance with LCR meter (replace if below 80% of rated).

What to do: Replace with same voltage and capacitance, upgraded to ≥105°C temperature rating. Before replacement, wait 5 min after power off — verify DC link voltage below 50V before touching. After replacement, re-verify ripple with oscilloscope.

Field tip

IGBT G-S short check in multimeter diode mode takes 30 seconds — always measure before replacing. Replacing IGBT module alone is more cost-effective than replacing the entire PCB.

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