Over-current protection circuits

The implemented prototype is protected against over-current conditions at its input and output by using the circuits shown in figures (a) and (b), respectively. The input protection circuit makes use of the battery current sensor. It simply compares the sensor output with an adjustable voltage reference and generates a pulse that is applied to both main and auxiliary microcontrollers. It should be noted that this circuit only detects an over-current in one direction (in this case, from the battery to the converter).

Over-current protection circuits

The output protection circuit is connected in parallel with the output filter inductor and it is less accurate then the input protection circuit. In fact, it will act only if a fast and large change in the load occurs, such as the case of short-circuit. In this case, the voltage developed across the output filter inductor will be enough to turn on one of the optocouplers, thus generating a quick output pulse.

Auxiliary power supply schematic (flyback converter)

 

Over-current protection circuits

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UF4006

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UF4006

 

Over-current protection circuits

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Over-current protection circuits

Enable from main microcontroller 6N136

 

Over-current protection circuits

E1+

O

 

E1-

O

 

Enable from aux. microcontroller 6N136

E2+

О

 

E2-

О

 

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Over-current protection circuitsOver-current protection circuitsOver-current protection circuitsOver-current protection circuits

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