Uneven voltage factor in series connection of fast recovery diodes

Uneven voltage factor in series connection of fast recovery diodes

How to deal with the abnormal operation of the fast recovery diode in the series circuit caused by uneven voltage and inability to operate normally?

It is generally divided into self reasons and external reasons. The self reasons are caused by processing technology, differences in raw materials, and the dispersion of various stages in the manufacturing process, which to some extent result in the inconsistency of the diode when subjected to reverse voltage.

The main reasons for this are reflected in:

① Differences in volt ampere characteristics;

② Differences in reverse charge recovery:

③ Inconsistent switch time;

④ The rate of rise of critical voltage varies.

The difference in volt ampere characteristics causes static uneven voltage in diodes, while the difference in reverse recovery charge, switching time, and critical voltage rise rate causes dynamic uneven voltage in diodes. Whether it is static uneven pressure or dynamic uneven pressure, when choosing

When selecting diodes, it is advisable to choose diodes from the same batch number as much as possible to ensure the consistency of their own parameters and achieve approximate voltage equalization of the diodes.

The external cause of uneven voltage in fast recovery diodes is the influence of external circuits, such as the layout of diodes in the circuit and the quality of external leads. In addition, the presence of distributed capacitors in the circuit is also one of the external causes of uneven voltage in diodes. By adjusting

The layout of diodes in a circuit can reduce the impact of peripheral circuits on uneven voltage of diodes, but in high voltage and high frequency rectification environments, the distributed capacitance in the circuit can cause severe uneven voltage of series diodes.