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| Dynamic Braking with minimal components [SOLVED] |
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| spec:
H anishkgt, I would suggest that, instead of electronic breaking, you go for a mechanical brake as used on many petrol lawn mowers. All you need is a spring operated drum or disk brake and a hold-off solenoid. The brake could possibly be salvaged from a car or motorbike. This approach has the potential for quicker and more positive breaking of the saw blade. |
| bson:
Is there some kind of special graduated engagement required here or something? What's wrong with something very basic? Basically, let it flywheel freely (D2 can be any rectifier) by bypassing the load using the switch. Starting with a naive, simple approach often works well, then improve and refine it to address shortcomings. The problem is these shortcomings are often use case or application specific, such as the specific motor and mechanical load, and when you co-opt someone else's finalized circuit you don't know what their use case or application is, or how well their approach fits your needs. So you end up reverse engineering it to find its operational limits, response times, dissipation, etc. Or, their circuit is general purpose enough to handle all imaginable shortcomings, in which case it's going to be ridiculously complicated, over engineered, and takes forever to reverse engineer and understand. |
| Dave:
Shorting the motor will not make it freewheel, but brake very hard. It could fry the motor, the diode and fuse together the relay contacts, if the mechanical part has enough inertia. |
| amyk:
--- Quote from: bson on January 01, 2019, 11:34:26 pm ---Is there some kind of special graduated engagement required here or something? What's wrong with something very basic? Basically, let it flywheel freely (D2 can be any rectifier) by bypassing the load using the switch. --- End quote --- What's wrong with something that doesn't work? |O It's called back-emf for a reason... :palm: |
| T3sl4co1l:
D2 is backwards. It's not inductive flyback, it's more like a capacitor equivalent to the rotor's inertia (and anything else hanging off it). Tim |
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