What is silicon carbide diode?
Silicon carbide diodes are unipolar devices, so compared to traditional silicon fast recovery diodes (silicon FRDs), silicon carbide diodes have ideal reverse recovery characteristics. When the device switches from forward to reverse blocking direction, there is almost no reverse recovery power, and the reverse recovery time is less than 20ns. Even the reverse recovery time of 600V10A silicon carbide diodes is less than 10ns.
Silicon carbide diode is an ideal device that combines high voltage speed, low power consumption, and high temperature resistance. At present, various silicon carbide devices have been successfully developed worldwide. Silicon carbide SBD, as a zero recovery diode, greatly improves high-frequency power supply circuits. The unique high-temperature characteristics of silicon carbide diodes make them potentially advantageous for power applications in high-temperature environments.
Silicon carbide diodes are widely used in the industrial field for high-frequency power converters in heavy-duty motors and industrial equipment, with the advantages of high efficiency, high power, and high frequency.
Reverse recovery principle of silicon carbide diode
Starting from time T=0, applying a reverse voltage V, it can be seen that the forward current Ifm begins to decrease, and it is known that the forward current will be 0 at T0.
Starting from T=T0, when the current is 0, the current begins to reverse and enters the reverse recovery process. At this point, we can understand that PN itself is still in forward bias.
During the time period from T2 to T0, non-equilibrium charge carriers are discharged from the base region under the action of reverse voltage, and the reverse current of the diode starts to rise from 0. When T=T2, the reverse current reaches its peak Irm, indicating that the charge carriers near the PN junction have already approached 0, forming depletion layers on both sides of the PN, and space charges are established, which is what we call the "diode off".
After T>T2, the stored charge is basically neutralized, the inductance voltage tends to zero, and the diode enters the static reverse voltage stage.
In the case where the rate of current decrease during shutdown remains constant, the peak reverse current and reverse recovery time of the power diode increase approximately exponentially with the magnitude of the forward current before shutdown over a large range.
When the forward current before shutdown is the same, the peak reverse current of the power diode increases approximately exponentially with the magnitude of the rate of decrease in current during shutdown over a large range; The reverse recovery time is approximately a geometric function of the rate of decrease in current during shutdown.
