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10 months ago in Power Electronics By Neethi

How do you measure neutral point potential in a 3-level npc inverter?

I'm working on a 3-level diode-clamped inverter. To balance the DC-link, I need the neutral point potential. How do I measure it accurately?

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By Nisha Ali Answered 7 months ago

Two common ways. Direct measurement: Use voltage sensors (resistive dividers or isolated sensors) connected between the neutral point and each DC-link rail. This gives you absolute potentials. Indirect estimation: Monitor the two DC-link capacitor voltages (V_C1, V_C2). The neutral point imbalance is simply V_C1 - V_C2. Either works; direct is more absolute, indirect is simpler. Both need to be accurate and fast enough for your balancing algorithm. The key is real-time, reliable data because imbalance kills capacitors and distorts output.

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