Maker Pro
Maker Pro

self-induction recuperation diode, what is it???

E

ErikBaluba

Jan 1, 1970
0
Hi,

What is the benefit/usage of a "self-induction recuperation diode" ?

I saw a motor driver schematic with an L298N motor driver, and two diodes
were used at each of the four outputs, connected to VDD and GND
respectively. Is this to clamp negative and positive spikes generated by the
motors to GND and VDD respectively? If so, what does the self-induction mean
in this context?

erik
 
J

John Popelish

Jan 1, 1970
0
ErikBaluba said:
Hi,

What is the benefit/usage of a "self-induction recuperation diode" ?

I saw a motor driver schematic with an L298N motor driver, and two diodes
were used at each of the four outputs, connected to VDD and GND
respectively. Is this to clamp negative and positive spikes generated by the
motors to GND and VDD respectively? If so, what does the self-induction mean
in this context?

erik
Any magnetic (inductive) device stores energy in proportion to the
square of current passing through it. If you break connection to both
ends of the inductive load, you can recover most of the stored energy
back into the supply with two diodes. If you charge up and dump the
inductive load often, this can amount to a considerable energy
savings. The alternative is to just turn that energy into heat to get
rid of it.
 
E

ErikBaluba

Jan 1, 1970
0
....
Any magnetic (inductive) device stores energy in proportion to the
square of current passing through it. If you break connection to both
ends of the inductive load, you can recover most of the stored energy
back into the supply with two diodes. If you charge up and dump the
inductive load often, this can amount to a considerable energy
savings. The alternative is to just turn that energy into heat to get
rid of it.

Thanks for sharing your valuable knowledge John,

I do understand how an inductor behaves but as often happens I got confused
about the terminology. So the self-induction part is not referring to a
special kind of diode, but rather to a specific use of a diode, meaning
recuperating self-induction from a inductive load, in this case the motor.

But what would really happen if the diodes weren't there? Assuming that the
output ports on the 298 driver do not zink any current caused by
self-induction in the motor, without the diodes would the self-induction be
dissipated in the motor's coil-windings? Also, are the diodes there to also
protect the outputs of the 298 driver IC from spikes caused by
self-induction in the motor?

erik
 
J

John Popelish

Jan 1, 1970
0
ErikBaluba said:
I do understand how an inductor behaves but as often happens I got confused
about the terminology. So the self-induction part is not referring to a
special kind of diode, but rather to a specific use of a diode, meaning
recuperating self-induction from a inductive load, in this case the motor.

That is my guess.
But what would really happen if the diodes weren't there?

The inductive load will produce whatever voltage it takes to get the
inductive current to go somewhere, either into driver breakdown
voltage losses or into the stray capacitance of the winding and driver
devices. The voltage across an inductor is proportional to the
inductance and the rate of change of current. In order to have the
current go from some finite value to zero in zero time (an infinite
rate of change of current) requires that there be an infinite voltage
across the inductance. That never happens, because something else
happens, first.
Assuming that the
output ports on the 298 driver do not zink any current caused by
self-induction in the motor, without the diodes would the self-induction be
dissipated in the motor's coil-windings?

No. More likely in the eddy current losses of the iron parts of the
motor (they are just shorted secondaries inside the windings) and in
the switching devices trying to turn off.
Also, are the diodes there to also
protect the outputs of the 298 driver IC from spikes caused by
self-induction in the motor?

Definitely. Putting the energy back into the supply is just a bonus.
 
Top