Bidirectional semiconductor circuit breaker
The present disclosure relates to a bidirectional semiconductor circuit breaker including a primary circuit unit connected between a power supply and a load and in which a first semiconductor switch and a second semiconductor switch are arranged in series and a snubber circuit unit of which one end is connected to the front end of the first semiconductor switch and the other end is connected to the rear end of the second semiconductor switch, in parallel. The snubber circuit unit includes a first circuit line, a second circuit line, and a third circuit line of which one end and the other end are connected to the first circuit line and the second circuit line, respectively, and in which a first resistor and a second resistor are arranged in series, and provide a snubber circuit which is applicable to a bidirectional fault current and satisfies semiconductor protection and current restraining performance.
1. A bidirectional semiconductor circuit breaker, comprising:
a main circuit unit connected between a power supply and a load, and having first and second semiconductor switches arranged in series; and
a snubber circuit unit having one end connected with a front end of the first semiconductor switch and another end connected with a rear end of the second semiconductor switch,
wherein the snubber circuit unit comprises:
a first circuit line in which a first capacitor and a first diode are arranged in series;
a second circuit line connected in parallel with the first circuit line, and in which a second capacitor and a second diode are arranged in series; and
a third circuit line having one end connected to the first circuit line and another end connected to the second circuit line, and in which a first resistor and a second resistor are arranged in series.
2. The circuit breaker of claim 1 , further comprising a first freewheeling circuit that is provided at an input portion of the circuit breaker to be made up of a third diode and a third resistor, and suppresses an overvoltage generated during trip operation of the circuit breaker,
wherein the first freewheeling circuit comprises:
the third diode connected in with the power supply at a power supply node of the first semiconductor switch; and
the third resistor connected in series between the third diode and ground.
3. The circuit breaker of claim 2 , further comprising a second freewheeling circuit that is provided at an output portion of the circuit breaker to be made up of a fourth diode and a fourth resistor,
wherein the second freewheeling circuit comprises:
the fourth diode connected with the load at a load node of the second semiconductor switch; and
the fourth resistor connected in series between the fourth diode and ground.
4. The circuit breaker of claim 1 , wherein the power supply includes a power supply side inductor component, and the load includes a load side inductor component.
5. The circuit breaker of claim 4 , wherein a voltage of the first capacitor of the snubber circuit is maintained the same as a voltage of the power supply before a time point t 1 at which a short circuit event occurs so that a fault current flowing in a power supply node or a load node does not increase further from a time point t 2 at which the first and second semiconductor switches are turned off.
6. The circuit breaker of claim 5 , wherein the first and second semiconductor switches are turned off by receiving a turn-off signal from a current sensor at the time point t 2 when current flowing in the first and second semiconductor switches reaches a protection level after the time point t 1 of the short circuit event occurs.
7. The circuit breaker of claim 6 , wherein a fault current I fw starts to flow at the time point t 2 through the second freewheeling circuit,
wherein current flowing from a first inductor through the first circuit line of the snubber circuit unit becomes zero at a time point b after the time point t 2 , and
wherein the fault current I fw increases to the time point t 3 and then decreases from the time point t 3 .
8. The circuit breaker of claim 1 , wherein the first semiconductor switch is configured such that a first metal-oxide-semiconductor field effect transistor (MOSFET) and a first parallel diode are connected in parallel,
wherein the second semiconductor switch is configured such that a second MOSFET and a second parallel diode are connected in parallel,
wherein the first MOSFET and the second MOSFET are N-channel MOSFETs,
wherein one end and the other end of the first parallel diode are connected to a source and a drain of the first MOSFET, respectively, and
wherein one end and the other end of the second parallel diode are connected to a drain and a source of the second MOSFET, respectively.
9. The circuit breaker of claim 1 , wherein the first circuit line is connected in series in the order of the first capacitor and the first diode, and the second circuit line is connected in series in the order of the second diode and the second capacitor.
10. The circuit breaker of claim 1 , wherein one end of the third circuit line is connected to another end of the first capacitor and one end of the first diode, and the other end of the third circuit line is connected to one end of the second diode and another end of the second capacitor.
11. The circuit breaker of claim 1 , wherein the first resistor and the second resistor are connected to a ground point therebetween, and the snubber circuit unit is point symmetric with respect to the ground point.
12. The circuit breaker of claim 11 , wherein the first resistor and the second resistor cause an increase in voltage drop generated when a fault current flows into the snubber circuit unit, and
wherein the ground point, which is a ground path through which the fault current flows, is provided at a connection point between the first resistor and the second resistor.
13. The circuit breaker of claim 1 , wherein one end of the first resistor is connected to a connection point between the first capacitor and the first diode, and the other end of the first resistor is connected to a connection point between the second capacitor and the second diode, and
wherein one end of the second resistor is connected in series with the first resistor at the connection point between the second capacitor and the second diode, and the other end of the second resistor is connected to a ground point.
14. The circuit breaker of claim 1 , wherein the first resistor and the second resistor are configured as non-linear resistor elements, and are connected in series with each other.
15. The circuit breaker of claim 1 , wherein the circuit breaker has a circuit structure in which a mechanical switch is connected in series with the circuit breaker to left and right contacts or one contact, so as to provide physical insulation and overvoltage protection after interruption is completed, and
wherein, the mechanical switch, after the first and second semiconductor switches are turned off, is opened through a separate signal or a time delay to maintain physical insulation of the circuit breaker.
16. The circuit breaker of claim 1 , further comprising a metal oxide varistor (MOV) arranged in parallel with the first and second semiconductor switches, so as to suppress an overvoltage, and
wherein the MOV is configured to dump current flowing in the first and second semiconductor switches to another path when a voltage applied to the first and second semiconductor switches is greater than or equal to a predetermined voltage.