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Diode with Reverse Recovery

Purpose

Behavioral model of a diode with reverse recovery.

Library

Switches

Description

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This component is a behavioral model of a diode which reproduces the effect of reverse recovery. This effect can be observed when a forward biased diode is rapidly turned off. It takes some time until the excess charge stored in the diode during conduction is removed. During this time the diode represents a short circuit instead of an open circuit, and a negative current can flow through the diode. The diode finally turns off when the charge is swept out by the reverse current and lost by internal recombination.

The following figure illustrates the relationship between the diode parameters and the turn-off current waveform. If0   and dIr∕dt   denote the continuous forward current and the rated turn-off current slope under test conditions. The turn-off time trr   is defined as the period between the zero-crossing of the current and the instant when it becomes equal to 10% of the maximum reverse current Irrm  . The reverse recovery charge is denoted Qrr  . Only two out of the three parameters trr  , Irrm  , and Qrr   need to be specified since they are linked geometrically. The remaining parameter should be set to 0. If all three parameters are given, Qrr   is ignored.

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The equivalent circuit of the diode model is shown below. It is composed of a resistance, and inductance, and a controlled current source which is linearly dependent on the inductor voltage. The values of these internal elements are automatically calculated from the diode parameters.

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Parameters and Dialog Box

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Forward voltage
Additional dc voltage Vf    in volts (V) between anode and cathode when the diode is conducting. The default is 0.
On-resistance
The resistance Ron   of the conducting device, in ohms (_O_  ). The default is 0.
Off-resistance
The resistance Roff    of the blocking device, in ohms (_O_  ). The default is inf. If diodes are connected in series (e.g. in a rectifier leg), the off-resistance must have a large finite value.
Continuous forward current
The continuous forward current If0    under test conditions.
Current slope at turn-off
The turn-off current slope dIr∕dt    under test conditions.
Reverse recovery time
The turn-off time t
rr   under test conditions.
Peak recovery current
The absolute peak value of the reverse current Irrm   under test conditions.
Reverse recovery charge
The reverse recovery charge Qrr   under test conditions. If both trr   and Irrm   are specified, this parameter is ignored.
Lrr
This inductance acts as a probe measuring the di∕dt  . It should be set to a very small value. The default is 10e-10.

Probe Signals

Diode voltage
The voltage measured between anode and cathode.
Diode current
The current through the diode flowing from anode to cathode.
Diode conductivity
Conduction state of the internal switch. The signal outputs 0 when the diode is blocking, and 1 when it is conducting.

References

A. Courtay, "MAST power diode and thyristor models including automatic parameter extraction", SABER User Group Meeting Brighton, UK, Sept. 1995.