I have a DC motor with a voltage of 12V and a power of 550W, using a freewheeling diode 1N5822, but now this diode is often burned. Check the information to see that its maximum instantaneous current reaches 80A, thus I think it can work properly in the circuit. Why this happened? What should this margin be? Is it related to reverse recovery time?
Travis
Best used and new equipment listings https://equipmentradar.com
Philomel
It sounds like this may be a brushed motor and the brushes are burned or the springs are shot.
It sounds like the inductive kick is exceeding the specs of the diode. Replace the brushes and the diode.
The Diode is good for this application. You can parallel two diodes to handle the spikes but replacing the brushes should be a good fix.
qrk
When you turn power off, you will have a current of 46A flowing through the diode for a short time (current ramps down to zero over some time period). If you look at the spec sheet, this diode will dissipate 46 W at that current level.
The thermal resistance is around 50°C/W which means your diode will get up to 2300 °C if the current is continuous. Since we don't know the spin-down time of your motor, hard to say, but if you put your finger on the diode and it burns you, the diode is underrated.
What you need is a diode with higher current capacity (in the 15 to 50A range) that can be attached to a heat sink. Probably in something like a TO220 case, or larger.
異域秦後人
Because its peak voltage is too low, just 40V that ever able to stand the counter EMF is generating from motor while switching on and off. From my past trouble shooting experience on Schottky Barrier rectifier commonly burnt open easily. Replace it with higher voltage type can be avoid this trouble,or parallel a 36v transorb diode to it.
billrussell42
A lot depends on how frequently you turn the motor on/off. The diode prevents arcing in the motor switch when the motor is turned off, thus it only sees current at that time.
But that current persists for a while, how long depends on the motor inductance and resistance. but not instantaneous.
550 w and 12 v is 46 amps. For safety, you would want a 50 amp diode, but those require a large heat sink. The ones I know of require a press fit hole in a large hunk of aluminum.
A compromise may be a 1N3208 which is a type that bolts to a heat sink. It is rated at 15 amps DC and 250 amps repetitive surge.