Induction heating inverter frequency requirement Induction heating systems require low-frequency inverters. Is this statement correct?

Introduction / Context:
Induction heating uses alternating magnetic fields to induce eddy currents in a workpiece. The choice of frequency controls the penetration depth (skin depth) and heating distribution, and therefore must match the application (surface hardening, brazing, melting, etc.).

Given Data / Assumptions:

• Induction heating frequency ranges commonly from a few hundred hertz to hundreds of kilohertz.
• Skin depth δ ∝ 1 / sqrt(f), where f is frequency.

Concept / Approach:
Higher frequency results in shallower penetration (good for surface hardening/brazing). Lower frequency gives deeper penetration (useful for bulk heating of larger cross-sections). However, “low frequency” in the context of power electronics often still means >100 Hz up to several kHz, and many induction systems operate in the kHz to hundreds of kHz range—certainly not “low” compared to mains frequency for most applications.

Step-by-Step Solution:
Identify target: surface vs. bulk heating determines f.Typical industrial units: ~1 kHz to 450 kHz (or higher) using resonant inverters.Therefore, the blanket statement “require low frequency” is incorrect.

Verification / Alternative check:
Application notes and catalogs for induction heaters specify medium-to-high frequencies to tailor skin depth; lower frequencies are used only for very deep heating of large workpieces.

Why Other Options Are Wrong:
True (A): Overgeneralization; most systems are medium/high frequency.
Application-specific (C/D): Even these use varied frequencies; not universally low.

Common Pitfalls:
Equating “industrial” with “low frequency.” Induction heating efficiency and process control often favor higher frequencies.

Final Answer:
False