A switch device includes first and second switch units that are coupled respectively to first and second output terminals. Each of the first and second switch units includes a plurality of diodes and at least one semiconductor-controlled rectifier (SCR), where at least one of the diodes and one of the at least one SCR cooperatively permit a current to flow therethrough to a corresponding one of the first and second output terminals when each thereof operates in an ON state, and where at least one of the diodes and one of the at least one SCR cooperatively permit a current to flow therethrough from a corresponding one of the first and second output terminals when each thereof operates in an ON state.

A thyristor-based dc solid state circuit breaker (SSCB) named Y-type includes a new complementary commutation circuit including a capacitor-capacitor pair, which features three advantages. First, a fast commutation is achieved using a countercurrent pulse injection by the capacitor-capacitor pair structure. Second, metal-oxide varistors (MOVs) are disconnected from the power line when SSCB is OFF, which solves the reliability issue due to the MOV degradation and enhances the voltage utilization rate of the main switch. Third, benefiting from the capacitor-capacitor pair structure, reliable reclosing and rebreaking are obtained for practical applications.

A thyristor-based dc solid state circuit breaker (SSCB) named Y-type includes a new complementary commutation circuit including a capacitor-capacitor pair, which features three advantages. First, a fast commutation is achieved using a countercurrent pulse injection by the capacitor-capacitor pair structure. Second, metal-oxide varistors (MOVs) are disconnected from the power line when SSCB is OFF, which solves the reliability issue due to the MOV degradation and enhances the voltage utilization rate of the main switch. Third, benefiting from the capacitor-capacitor pair structure, reliable reclosing and rebreaking are obtained for practical applications.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.

Disconnection of a circulation path through which a circulation current flows is detected while suppressing an increase in circuit scale. A battery monitoring device includes switching circuits that control currents flowing through coils of main contactors by being controlled to be turned on and off, freewheeling diodes that are connected to the coils of the main contactors to form circulation paths for circulating the currents, and a control unit. The control unit measures output voltages of the freewheeling diodes at an input terminal, and detects the disconnection of the circulation paths based on the output voltages of the freewheeling diodes.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.

A semiconductor relay device includes a conversion circuit configured to receive an input signal from outside and pass a first current to a first node based on the input signal. A zener diode has an anode coupled to a second node and a cathode coupled to the first node. A resistor is coupled between the second node and a third node. A number n of diodes are serially coupled. A thyristor has an anode coupled to the first node, a cathode coupled to the second node, and a control terminal coupled to the third node. A transistor has a gate coupled to the first node. An anode of a diode at a first end of the n diodes is coupled to the first node, and a cathode of a diode at a second end of the n diodes is coupled to a third node.