一种功率开关管的过流保护电路及功率变换器
By designing a combination of isolation drive circuit, conduction voltage drop detection circuit and signal isolation circuit, overcurrent protection for power switching transistors is achieved, solving the problems of complex detection and high loss in the existing technology, and improving the reliability of switching transistors and the efficiency of converters.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- BEIJING SUPLET
- Filing Date
- 2025-08-04
- Publication Date
- 2026-07-17
AI Technical Summary
In the existing technology, the circuit for detecting overcurrent in power switches is complex and has losses, which makes the power switches prone to damage.
An overcurrent protection circuit is designed, comprising an isolation drive circuit, a conduction voltage drop detection circuit, a signal isolation circuit, and a drive signal control circuit. The circuit detects overcurrent by detecting the conduction voltage drop of the power switch and promptly shuts off the power switch in case of overcurrent to protect it from damage.
It achieves timely protection against overcurrent in the power switch, reduces the risk of damage to the power switch, improves its reliability, and reduces power consumption and improves the overall power conversion efficiency of the power converter because there is no need for resistor detection.
Smart Images
Figure CN224520654U_ABST
Abstract
Claims
1. An overcurrent protection circuit for a power switch tube, characterized by comprising: include: Isolation drive circuit, on-state voltage drop detection circuit, signal isolation circuit, and drive signal control circuit; The first terminal of the isolation drive circuit is used to connect to the drive signal, and the second terminal of the isolation drive circuit is connected to the gate of the power switch. The first terminal of the on-state voltage drop detection circuit is connected to the second terminal of the isolation drive circuit, the second terminal of the on-state voltage drop detection circuit is connected to the second terminal of the power switch, the third terminal of the on-state voltage drop detection circuit is connected to the control terminal of the signal isolation circuit, and the fourth terminal of the on-state voltage drop detection circuit is connected to the first terminal of the power switch. The on-state voltage drop detection circuit is used to control the signal isolation circuit to turn on when the on-state voltage drop of the power switch is greater than a preset value. The output terminal of the signal isolation circuit is connected to the input terminal of the drive signal control circuit. When the signal isolation circuit is turned on, the output terminal of the drive signal control circuit is connected to the first terminal of the isolation drive circuit. When the signal isolation circuit is turned on, the drive signal control circuit connects the first terminal of the isolation drive circuit to ground.
2. The protection circuit of claim 1, wherein The on-state voltage drop detection circuit includes: a pull-up resistor, a voltage divider circuit, and a diode; The first terminal of the voltage divider circuit is connected to the second terminal of the isolation drive circuit through the pull-up resistor; the second terminal of the voltage divider circuit is connected to the second terminal of the power switch transistor; the output terminal of the voltage divider circuit is connected to the input terminal of the signal isolation circuit; the anode of the diode is connected to the first terminal of the voltage divider circuit; and the cathode of the diode is connected to the first terminal of the power switch transistor.
3. The protection circuit of claim 2, wherein, The on-state voltage drop detection circuit also includes: a controllable precision voltage regulator; The control terminal of the controllable precision voltage regulator is connected to the output terminal of the voltage divider circuit, the first terminal of the controllable precision voltage regulator is connected to the input terminal of the signal isolation circuit, and the second terminal of the controllable precision voltage regulator is connected to the second terminal of the power switch.
4. The protection circuit according to any one of claims 1 to 3, characterized in that, The signal isolation circuit is an optocoupler.
5. The protection circuit of claim 1, wherein The drive signal control circuit includes a comparator and a transistor; The output terminal of the signal isolation circuit is connected to the negative input terminal of the comparator, the positive input terminal of the comparator is connected to the reference voltage, the output terminal of the comparator is connected to the base of the transistor, the emitter of the transistor is grounded, and the collector of the transistor is connected to the input terminal of the isolation drive circuit.
6. The protection circuit of claim 5, wherein, The drive signal control circuit also includes: a charging resistor and a charging capacitor; The first end of the charging resistor is connected to the operating voltage, the second end of the charging resistor is connected to the negative input terminal of the comparator, and the second end of the charging resistor is grounded through the charging capacitor.
7. The protection circuit according to any one of claims 1 to 3, characterized in that, Also includes: First resistor and second resistor; The first terminal of the isolation drive circuit is connected to the drive signal through the first resistor, and the second terminal of the isolation drive circuit is connected to the gate of the power switch through the second resistor.
8. The protection circuit of claim 2, wherein, The voltage divider circuit includes: a first voltage divider resistor and a second voltage divider resistor; The first end of the first voltage dividing resistor is connected to the second end of the isolated driving circuit through the pull-up resistor, the second end of the first voltage dividing resistor is connected to the second end of the power switch tube through the second voltage dividing resistor, and the second end of the first voltage dividing resistor serves as an output end of the voltage dividing circuit.
9. The protection circuit according to claim 5 or 6, characterized in that, The driving signal control circuit further comprises a third resistor, a fourth resistor and a fifth resistor. The base of the triode is connected to the output end of the comparator through the fourth resistor, the output end of the comparator is connected to a working voltage through the third resistor, and the fifth resistor is connected between the base and the emitter of the triode.
10. A power converter, characterized by, The overcurrent protection circuit comprising the power switch tube of any one of claims 1-9 further comprises at least one power switch tube.