Switching circuit and power converter
A switching circuit including: a switching device configured to conduct or open a state between a drain terminal and a source terminal; a drive circuit including a first switch element and a second switch element, the drive circuit being configured to open and close the first switch element and the second switch element, and output a drive voltage for driving the switching device to the gate terminal via an output end; a clamp circuit including a third switch element configured to conduct between a reference potential of the drive circuit and a connection point of a path connecting the output end of the drive circuit and the gate terminal; and a ferrite inductor provided immediately near the output end of the drive circuit, and having one end connected to the output end and the other end connected to the connection point.
1 . A switching circuit comprising:
a switching device configured to conduct or open a state between a drain terminal and a source terminal based on a voltage applied between a gate terminal and the source terminal;
a drive circuit including a first switch element having one end connected to a positive electrode side of a control power supply and an other end connected to an output end, and a second switch element having one end connected to the output end and an other end connected to a reference potential to which a negative electrode side of the control power supply is connected, the drive circuit being configured to open and close the first switch element and the second switch element in accordance with a predetermined control signal, generate a drive voltage for driving the switching device, and output the generated drive voltage to the gate terminal of the switching device via the output end;
a clamp circuit including a third switch element configured to conduct between the reference potential of the drive circuit and a connection point of a path connecting the output end of the drive circuit and the gate terminal of the switching device based on a comparison result between a threshold potential generated based on the reference potential of the drive circuit and a potential at the connection point; and
a ferrite inductor provided immediately near the output end of the drive circuit, and having one end connected to the output end and an other end connected to the connection point,
wherein the ferrite inductor is disposed in series between the output end of the drive circuit and the connection point,
wherein the connection point is located on a gate terminal side of the ferrite inductor, and
wherein when the third switch element conducts, a closed loop is formed through the gate terminal of the switching device, the connection point, the third switch element, and the reference potential, and the ferrite inductor is physically disposed outside the closed loop to separate a propagation path of an oscillation noise and a propagation path of mirror noise.
2 . The switching circuit according to claim 1 , further comprising a resistance element connected in series with the ferrite inductor between the output end of the drive circuit and the connection point.
3 . The switching circuit according to claim 1 , further comprising a diode element having an anode connected to the reference potential of the drive circuit and a cathode connected to the connection point.
4 . The switching circuit according to claim 2 , wherein a capacitor element is connected in parallel to the resistance element connected in series with the ferrite inductor.
5 . The switching circuit according to claim 1 , wherein the ferrite inductor comprises an equivalent circuit having an inductor and a resistor.
6 . The switching circuit according to claim 1 , wherein the switching device includes a wide bandgap semiconductor including at least a SiC semiconductor or a GaN semiconductor.
7 . A power converter comprising a switching circuit according to claim 1 in a configuration.