SINE WAVE INVERTERS

Theory

If a step function voltage (DC) is applied to a tank circuit (parallel resonant) the result is a damped sinusoidal current.  The self-switching sinewave inverter circuit shown on drawing EASW obtains a continuous sine wave by switching polarity after each first half cycle.  The transistors perform as switches.  This switching occurs when the instantaneous current is zero.  For specific applications this circuit has the following advantages.

Inverter

1. Very low harmonics since the sine wave is generated directly instead of a square-wave with load sensitive filters.  Subsequently, low EMI.
2. Self-switching at high frequencies if frequency is not critical.
3. Can be separately switched if frequency is critical.

Converter

1. Best topology for high voltage outputs.  Minimizes problem of high distributed capacitance reflected to primary.
2. Sine-wave suitable for voltage multiplier circuits.  This results in lower voltage diodes, capacitors, and transformers which have lower cost.
3. Automatically provides power-factor correction for the load with self-switching circuit.
4. Very high reliability experience in military applications.

Contact an MCE application engineer for more information concerning a specific application.  A design can be accomplished rapidly and engineering sample magnetic component can be supplied from materials in stock.

Rev 0644A

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