Parametric Design Guidelines for MW Oven Inverter

Focus:

In a modern microwave oven, the magnetron is powered by a resonant inverter driving a high-voltage transformer that feeds a voltage-multiplying rectifier, which supplies 4 to 6 kV to the magnetron. A common choice for the inverter topology is the single-ended resonant inverter, which is the same topology used in low-cost induction heating (IH) applications. However the procedure used to design the inverter in the IH application cannot be applied to microwave ovens because of the impact of the HV transformer and voltage-multiplying rectifier on inverter operation. This article presents a revised design procedure suitable for designing the single-ended resonant inverter for the microwave application. This procedure offers guidelines for specifying the HV transformer and resonant components and approximates the voltage stress across the primary switch and voltage multiplier components. After providing a basic description of a magnetron power supply, the author derives a simplified model of the inverter that accounts for the effects of the transformer and rectifier. Using the equations from the model, a design procedure for the inverter is presented. This procedure is tested with a design example and the calculated results are checked against those obtained using a SPICE simulation. Both of those results are then checked against measurements taken on an actual magnetron power supply.

What you’ll learn:

• How to design single-ended resonant inverters for microwave oven applications using a simplified design procedure

Notes:

No publication date is specified on paper. The May 8, 2012 date shown here is based on reference to PCIM 2012 conference in the URL.

View the Source

Author & Publication:

C.Bocchiola; International Rectifier Corporation, Vendor website, May 08 2012

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