Switch system

Patent metadata

Field	Value
Publication number	US-12418287-B2
Application number	US-202218563242-A
Country	US
Kind code	B2
Filing date	Mar 24, 2022
Priority date	May 27, 2021
Publication date	Sep 16, 2025
Grant date	Sep 16, 2025

Abstract

In a switch system, a voltage clamping element is connected to a semiconductor switch in parallel. An active clamping circuit is connected between a control terminal and a first main terminal of the semiconductor switch. The active clamping circuit includes a first diode, a second diode, and a control switch. A second anode of the second diode is connected to a first anode of the first diode. The control switch is connected between the first anode of the first diode and the control terminal of the semiconductor switch. A second control unit controls the control switch. A breakdown voltage of the first diode is smaller than a clamp voltage of the voltage clamping element.

First claim

The invention claimed is:

1. A switch system comprising:
a semiconductor switch having a control terminal, a first main terminal, and a second main terminal;
a voltage clamping element connected to the semiconductor switch in parallel;
an active clamping circuit connected between the control terminal and the first main terminal of the semiconductor switch;
a first control unit configured to control the semiconductor switch;
a second control unit configured to control the active clamping circuit; and
a NOT circuit,
the active clamping circuit including:
a first diode having a first anode and a first cathode and causing breakdown upon application of voltage between the first main terminal and the second main terminal of the semiconductor switch;
a second diode having a second anode and a second cathode, the second anode of the second diode being connected to the first anode of the first diode; and
a control switch connected between the first anode of the first diode and the control terminal of the semiconductor switch,
the second control unit being configured to control the control switch,
a breakdown voltage of the first diode being smaller than a clamp voltage of the voltage clamping element,
wherein
the control switch is a first field effect transistor having a first gate, a first drain, and a first source,
the active clamping circuit further includes a second field effect transistor having a second gate, a second drain, and a second source and connected between the first gate of the first field effect transistor and the second main terminal of the semiconductor switch,
the second control unit is configured to control the second field effect transistor,
the NOT circuit is connected between a signal path that connects the first control unit to the control terminal of the semiconductor switch and the first gate of the first field effect transistor, and
the second control unit is connected to the second gate of the second field effect transistor.

2. The switch system of claim 1 , wherein
the second control unit includes a delay circuit, and
the delay circuit is connected between an output terminal of the NOT circuit and the second gate of the second field effect transistor.

3. The switch system of claim 2 , further comprising a first drive circuit having a first gate resistor connected between the output terminal of the NOT circuit and the first gate of the first field effect transistor, wherein
the delay circuit is implemented as a second drive circuit, the second drive circuit including:
a second gate resistor connected between the output terminal of the NOT circuit and the second gate of the second field effect transistor; and
a capacitor connected between the second gate and the second source of the second field effect transistor.

4. The switch system of claim 3 , further comprising a third drive circuit connected between the first control unit and the control terminal of the semiconductor switch, wherein
the NOT circuit includes:
a power supply;
a resistor connected to the power supply in series;
a third field effect transistor having a third gate, a third drain, and a third source and connected to the resistor in series; and
a fourth drive circuit connected between the first control unit and the third gate of the third field effect transistor.

5. The switch system of claim 3 , further comprising a third drive circuit connected between the first control unit and the control terminal of the semiconductor switch, wherein
the NOT circuit includes:
a power supply;
a resistor connected to the power supply in series; and
a third field effect transistor having a third gate, a third drain, and a third source and connected to the resistor in series,
the third drive circuit has:
a first path configured to turn the semiconductor switch on; and
a second path configured to turn the semiconductor switch off,
the first path includes:
a third diode having a third anode and a third cathode, the third cathode of the third diode being connected to the control terminal of the semiconductor switch; and
a third gate resistor connected to the third diode in series,
the second path includes a resistor connected between the first control unit and the control terminal of the semiconductor switch and having a smaller resistance value than the third gate resistor, and
the first field effect transistor of the active clamping circuit being configured to turn on before the semiconductor switch turns off.

6. A switch system comprising:
a semiconductor switch having a control terminal, a first main terminal, and a second main terminal;
a voltage clamping element connected to the semiconductor switch in parallel;
an active clamping circuit connected between the control terminal and the first main terminal of the semiconductor switch;
a first control unit configured to control the semiconductor switch;
a second control unit configured to control the active clamping circuit;
a detection circuit connected between the control terminal and the second main terminal of the semiconductor switch to detect a voltage between the control terminal and the second main terminal of the semiconductor switch; and
a switch element connected between the control terminal and the second main terminal of the semiconductor switch,
the active clamping circuit including:
a first diode having a first anode and a first cathode and causing breakdown upon application of voltage between the first main terminal and the second main terminal of the semiconductor switch;
a second diode having a second anode and a second cathode, the second anode of the second diode being connected to the first anode of the first diode; and
a control switch connected between the first anode of the first diode and the control terminal of the semiconductor switch,
the second control unit being configured to control the control switch,
a breakdown voltage of the first diode being smaller than a clamp voltage of the voltage clamping element,
wherein
the switch element is configured to turn on when the voltage detected by the detection circuit exceeds a threshold voltage.

7. The switch system of claim 6 , wherein
the semiconductor switch is a junction field effect transistor,
with respect to a gate voltage of the junction field effect transistor, the threshold voltage is larger than a gate voltage of the junction field effect transistor in on state and smaller than an output voltage of a DC power supply included in the first control unit.

8. The switch system of claim 1 , wherein
the semiconductor switch is made up of a plurality of field effect transistors that are connected in parallel,
each of the plurality of field effect transistors has a gate, a drain, and a source,
the first main terminal of the semiconductor switch is connected to respective drains of the plurality of field effect transistors,
the second main terminal of the semiconductor switch is connected to respective sources of the plurality of field effect transistors,
the switch system further includes a plurality of gate resistors associated one to one with respective gates of the plurality of field effect transistors and connected between the first control unit and the respective gates, and
the plurality of gate transistors are connected to the active clamping circuit.

9. The switch system of claim 1 , comprising:
a first switch element having a first gate terminal, a first drain terminal, and a first source terminal; and
a second switch element having a second gate terminal, a second drain terminal, and a second source terminal and connected to the first switch element in series, wherein
in the semiconductor switch, the first drain terminal of the first

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Kinoshita Yusuke
• Maeda Ryosuke
• Nakazawa Satoshi

Classifications

• H03K17/16

  Modifications for eliminating interference voltages or currents · CPC title

• H03K17/081

  without feedback from the output circuit to the control circuit · CPC title

• H03K17/08

  Modifications for protecting switching circuit against overcurrent or overvoltage · CPC title

• H03K17/6871 Primary

  the output circuit comprising more than one controlled field-effect transistor · CPC title