a combination switch

Abstract

The invention discloses a combination switch. The combination switch includes a first switch, a second switch and an energy storage capacitor, the first switch and the second switch are connected in series in the same direction, the first end of the first switch is the first output end of the combination switch, and the second The end is connected in series with the first end of the second switch, the second end of the second switch is the second output end of the combination switch, and the energy storage capacitor is connected in parallel with the gate drive end of the first switch and the second end of the second switch. The combination switch of the present invention can combine the advantages of the first switch and the second switch. For example, the first switch is a MOSFET switch, and the second switch is a fast recovery diode or a Schottky diode. Then the combination switch has higher operating voltage capability and faster The performance of reverse recovery or zero reverse recovery, the reverse recovery loss is smaller or the reverse recovery loss is completely eliminated, and the circuit is simple to realize and the cost is reduced.

Description

technical field [0001] The present invention relates to the field of power supplies, and in particular to fast recovery switches. Background technique [0002] Fast recovery diode (FRD for short) is a semiconductor diode with good switching characteristics, short reverse recovery time or zero reverse recovery. It is mainly used in switching power supplies, PWM pulse width modulators, frequency converters and other electronic devices. In the circuit, it is used as a high-frequency rectifier diode, a freewheeling diode or a damping diode. The internal structure of the fast recovery diode is different from the ordinary PN junction diode. It belongs to the PIN junction diode, that is, the base region I is added between the P-type silicon material and the N-type silicon material to form a PIN silicon chip. Because the base region is very thin and the reverse recovery charge is very small, the reverse recovery time of the fast recovery diode is short, the forward voltage drop is ...

AI Technical Summary

Problems solved by technology

Schottky diodes have the advantages of high switching frequency and forward voltage drop, but their biggest disadvantages are their low reverse bias voltage and large reverse leakage current, such as Schottky diodes made of silicon and metal. The reverse bias rated withstand voltage is only up to 200V, there is no Si-based Schottky diode between 200 and 600V, the withstand voltage of SiC Schottky diode is only 600 / 650V / 1200V, and there is no SiC Schottky below 600V Diode, and the forward voltage drop is very high

The reverse leakage current value has a positive temperature characteristic, and it tends to increase rapidly as the temperature rises. It is necessary to pay attention to the hidden danger of thermal runaway in practical design.

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