What is the significance of reverse voltage margin for fast recovery diodes?

How does the reverse voltage of fast recovery diode parameters work in electronic circuits? What is the significance of reverse voltage margin for fast recovery diodes?

fast recovery diodes have a limit voltage for reverse breakdown, which is not included in the data manual by the vast majority of fast recovery diode manufacturers. However, in most cases, in order to save costs, it is impossible to reduce the reverse withstand voltage of the fast recovery diode to about 50%. Therefore, whether the reverse voltage margin is sufficient is meaningful for evaluating how much the reverse withstand voltage of the fast recovery diode should be reduced for safe use. From the table below, it can be seen that the margin of reverse voltage is not 2-3 times the rated reverse voltage as mentioned online.

The knee point reverse voltage is the reverse voltage point when the leakage current suddenly changes. At a certain voltage point at room temperature, the leakage current of a fast recovery diode suddenly increases by tens or hundreds of times. For example, a fast recovery diode has a leakage current of 20 at 78V μ A. But at 79V, the leakage current is 2 mA, and 79V is the knee reverse voltage. Although the knee reverse voltage did not completely breakdown the fast recovery diode, it seriously affected the normal use of the fast recovery diode. At high temperatures, the leakage current is more prone to sudden changes, and the reverse voltage at the knee point is lower. So, what is the correct and reasonable derating value for the reverse voltage of a fast recovery diode? It is more important to test the knee point reverse voltage value from the ambient temperature of the material and the actual conduction current used, and then determine the margin derating value.