Industrial electronics
Explainer
Freewheeling Diodes: Giving Inductor Current a Path
Switch off an inductive load and its voltage can spike to hundreds of volts.
Quick check · tap an answer to continue
Lesson notes
Key points
- An inductor resists any change in current, so when a switch opens, it forces current to keep flowing somehow.
- A freewheeling diode is placed in reverse across the load, giving that stored current a safe loop to decay through.
- While the switch conducts, the diode is reverse biased and idle; it only conducts once the supply voltage disappears or reverses.
- In a phase-controlled rectifier, it also stops output going negative, improving power factor and protecting the thyristors.
Takeaway: A freewheeling diode lets inductive current decay safely.
Quick check: When does a freewheeling diode conduct?
- When the supply is on
- When the supply cuts off
- Only during SCR triggering
Inductive kickFreewheeling diodeConduction statesRectifier benefit
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