Analysis of the Misunderstanding of Uneven Voltage in Diode Series Connection

Analysis of the Misunderstanding of Unequal Voltage in Diode Series: Circuit Problems Caused by Unequal Voltage in Diode Series. When a circuit problem occurs, an analysis report needs to be made to identify the cause in order to find a solution.
1. Macro analysis of uneven voltage in series connection of diodes
The main consideration is the influence of the diode's own factors. Two diodes are connected in series and an external reverse DC voltage is applied. A diode with a smaller reverse saturation current can withstand a higher voltage because two diodes are connected in series and the reverse saturation current remains constant under the rated external voltage of J. Assuming that there is only a difference in reverse saturation current between two diodes, D2 has a smaller reverse saturation current. The above conclusion can be clearly drawn.
In actual operation, macroscopically, diodes have different voltage drops due to their own differences. When the external voltage U increases and the voltage drop across D2 reaches the critical point, due to the large reverse saturation current of D1, its voltage drop is relatively small. When D2 reaches the critical voltage drop, D1 is still in the safe and stable region. U increases again. According to the above analysis, the voltage drop on D2 will break through the critical transition voltage, causing diode breakdown and a sharp increase in current. However, D1 and D2 are connected in series in the main circuit, and the current on D1 will inevitably increase with D2. However, from the volt ampere curve of D1, it can be seen that the reverse voltage drop of D1 should reach the transition voltage when passing through a large current. Therefore, the sum of u1 and u2 is greater than U, and the speculation is not valid. Therefore, when U increases, the voltage of D2 will not continue to increase, while the voltage of D1 will continue to increase until u exceeds the sum of the reverse withstand voltages of the two diodes, at which point diode breakdown will occur. The analysis of multiple pipes is also the same.
2. Microscopic analysis of uneven voltage in diode series connection
The pins of diodes, the layout of diodes on circuit boards, and so on naturally evolve into stray capacitance and inductance in high voltage and high frequency environments. The introduction of stray capacitance and inductance directly affects the on and off waveforms of diodes. The introduction of capacitors prevents sudden voltage changes, while the introduction of inductors prevents sudden current changes.   The inherent factors of diodes can be approximated by selecting diodes produced in the same batch, with a focus on external factors.