Modeling Reverse Recovery Loss

Rescheduled: Jan 31st, 2019 at 1:00 EST.

This webinar concludes a three part series on modeling switching losses in SIMPLIS. You can view recordings and download example files for the first two webinars at the following links:

• MOSFET Switching Losses - A Deep Dive - Part I
• MOSFET Switching Losses - A Deep Dive - Part II

In this one hour webinar, we will discuss reverse recovery loss in diodes. To begin the discussion, we will present waveforms for a diode commutating from an on to off state under an inductive load for the following models:

1. No Reverse Recovery and No Junction Capacitance (ideal, conduction only.)
2. No Reverse Recovery but Including the Junction Capacitance (ideal, capacitance only.)
3. Including Reverse Recovery (conduction, junction capacitance, and reverse recovery as modeled by SPICE).

From this foundation, we will discuss how a typical SPICE model lacks excess charge, leading to a "snappy" recovery where the diode current changes almost instantaneously from the minimum reverse current (IRM) to zero. This model defect can be corrected by using the "Lauritzen and Ma" soft recovery model, which accurately models both phases of reverse current in the diode, the first phase leading up to IRM and the second phase as the diode current recovers to zero after IRM. A SIMPLIS model for the soft recovery diode is presented and the model parameters discussed.

Outline

1. Introduction to diode turn-off waveforms
2. Soft-recovery waveforms including excess charge
3. Lauritzen and Ma soft recovery circuit for SIMPLIS
4. Defining the Lauritzen and Ma model parameters for the SIMPLIS model
5. Comparing losses with and without reverse recovery