Overcurrent detection circuit

Abstract

The utility model discloses an over-current detection circuit, and belongs to the technical field of over-current detection. Comprising a transformer, a pin 1 and a pin 2 of a primary side of the transformer are connected in series with a circuit to be detected, a pin 3 and a pin 4 of a secondary side of the transformer are connected with an input end of a commutator circuit, an output end of the commutator circuit is connected with an input end of a filtering sub-circuit, and an output end of the filtering sub-circuit is connected with an input end of a control module. The output end of the control module is connected with the input end of the on-off control module, the output end of the on-off control module is connected with a pin 1 of the primary side of the transformer, the voltage of the output end of the filtering sub-circuit is obtained through the control module, and the control module sends a signal to the on-off control module. And the on-off control module is used for controlling the on-off of the transformer. According to the utility model, complete electrical isolation is realized, interference of a strong current signal to a new weak current signal can be effectively prevented, and the safety and reliability of a system are improved.

Description

Technical Field

[0001] This utility model belongs to the field of overcurrent detection technology, and specifically relates to an overcurrent detection circuit. Background Technology

[0002] Overcurrent detection circuit is an important component of switching power supply. When the input or output current of the switching power supply is too high, the control module of the overcurrent detection circuit turns off the bridge arm power devices (MOSFET or IGBT) of the switching power supply, and the main power circuit of the switching power supply stops working, thereby protecting the switching power supply itself and its load.

[0003] However, existing overcurrent detection circuits detect current by sampling resistors. When the current in the circuit under test is large, the resistors generate significant heat, dissipate high power, and occupy a large space. Utility Model Content

[0004] Purpose of the utility model: To provide an overcurrent detection circuit that solves the above-mentioned problems existing in the prior art.

[0005] Technical solution: An overcurrent detection circuit includes a transformer. Pins 1 and 2 of the primary side of the transformer are connected in series with the circuit to be detected. Pins 3 and 4 of the secondary side of the transformer are connected to the input terminal of a rectifier circuit. The output terminal of the rectifier circuit is connected to the input terminal of a filter circuit. The output terminal of the filter circuit is connected to the input terminal of a control module. The output terminal of the control module is connected to the input terminal of a switching control module. The output terminal of the switching control module is connected to pin 1 of the primary side of the transformer. The voltage at the output terminal of the filter circuit is obtained through the control module. The control module sends a signal to the switching control module, which is used to control the switching of the transformer.

[0006] Preferably, the rectifier circuit includes diodes D1, D2, D3, and D4, and resistor R2. Pin 3 of the transformer is connected to both the anode of diode D1 and the cathode of diode D3. Pin 4 of the transformer is connected to both the anode of diode D2 and the cathode of diode D4. The anode of diode D3 is connected to both the anode of diode D4 and one end of resistor R2. The cathode of diode D1 is connected to both the cathode of diode D2 and the other end of resistor R2. The other end of resistor R2 is connected to the input terminal of the filter circuit.

[0007] Preferably, diodes D1, D2, D3 and D4 are all LBAT54SLT1G type diodes.

[0008] Preferably, the filter sub-circuit includes a resistor R3 and a capacitor C1. One end of the resistor R3 is connected to the output terminal of the rectifier bridge sub-circuit, and the other end of the resistor R3 is connected to both one end of the capacitor C1 and the control module. The other end of the capacitor C1 is connected to the control module.

[0009] Preferably, the on / off control module includes a field-effect transistor Q1, the drain of the field-effect transistor Q1 is connected to pin 1 of the transformer, the source of the field-effect transistor is grounded, and the gate of the field-effect transistor is connected to the signal output terminal of the control module.

[0010] Preferably, it also includes a resistor R1, one end of which is connected to pin 2 of the transformer. The resistor R1 is used for current limiting protection of the transformer. The transformer is a CT2 type transformer, and the resistor is an EWWR0010J10R0T9 type resistor.

[0011] Preferably, the control module uses an AVP32F335-176 chip.

[0012] Preferably, the field-effect transistor Q1 is an LG90N3K5GJ type field-effect transistor.

[0013] Beneficial effects: This utility model relates to an overcurrent detection circuit, which uses a transformer connected to the power to be detected. With the cooperation of the rectifier circuit and the filter circuit, the current signal is converted into a voltage signal and then transmitted to the control module, realizing complete electrical isolation. This can effectively prevent strong electrical signals from interfering with weak electrical signals and improve the safety and reliability of the system.

[0014] After using a transformer to acquire the signal from the circuit under test, the current signal can be converted into a voltage signal through a rectifier circuit and a filter circuit, which simplifies the signal conversion circuit and improves the performance and reliability of the current detection and protection system. Attached Figure Description

[0015] Figure 1 This is a system block diagram of the present invention;

[0016] Figure 2 This is the overall circuit diagram of this utility model. Detailed Implementation

[0017] like Figures 1 to 2As shown, this utility model provides a technical solution: an overcurrent detection circuit, including a transformer, a rectifier circuit, a filter circuit, a control module, and an on / off control module. The transformer is a CT2 type transformer, and the control module uses an AVP32F335-176 chip. Pins 1 and 2 of the primary side of the transformer are connected in series with the circuit under test. A resistor R1 is connected between pin 2 of the transformer and the circuit under test, and the resistor R1 provides current limiting protection for the transformer. The resistor is an EWWR0010J10R0T9 type resistor. Pins 3 and 4 of the secondary side of the transformer are connected to the input terminal of the rectifier circuit. The transformer obtains the current signal of the circuit under test, and the rectifier circuit converts the current signal into a voltage signal. The output terminal of the rectifier circuit is connected to the input terminal of the filter circuit, and the output terminal of the filter circuit is connected to the input terminal of the control module. The filter circuit filters the converted voltage signal. The signal is then transmitted to the control module. The output of the control module is connected to the input of the on / off control module, and the output of the on / off control module is connected to pin 1 on the primary side of the transformer. The control module obtains the voltage at the output of the filter circuit and sends a signal to the on / off control module. The on / off control module controls the on / off state of the transformer. Specifically, by setting a voltage threshold, when the detected voltage signal exceeds the voltage threshold and the voltage IFB output by the rectifier circuit also reaches the protection value, the control module sends a protection signal to the on / off control module to control the transformer to turn off the current detection of the circuit under test. In other words, by connecting the transformer to the power supply under test, the current signal is converted into a voltage signal and transmitted to the control module in cooperation with the rectifier circuit and the filter circuit. This achieves complete electrical isolation, effectively preventing interference from strong electrical signals to weak electrical signals, improving the safety and reliability of the system, simplifying the signal conversion circuit, and enhancing the performance and reliability of the current detection and protection system.

[0018] In a further embodiment, the rectifier circuit includes diodes D1, D2, D3, and D4, and resistor R2. Diodes D1, D2, D3, and D4 are all LBAT54SLT1G type diodes. Pin 3 of the transformer is connected to both the anode of diode D1 and the cathode of diode D3. Pin 4 of the transformer is connected to both the anode of diode D2 and the cathode of diode D4. The anode of diode D3 is connected to both the anode of diode D4 and one end of resistor R2. The cathode of diode D1 is connected to both the cathode of diode D2 and the other end of resistor R2. The other end of resistor R2 is connected to the input terminal of the filter circuit. Thus, with the cooperation of diodes D1, D2, D3, D4, and resistor R2, the current signal acquired by the transformer is converted into a voltage signal IFB.

[0019] In a further embodiment, the filter sub-circuit includes a resistor R3 and a capacitor C1. One end of the resistor R3 is connected to the output terminal of the rectifier bridge circuit, and the other end of the resistor R3 is connected to one end of the capacitor C1 and the control module. The other end of the capacitor C1 is connected to the control module. The filter sub-circuit built by the resistor R3 and the capacitor C1 removes high-frequency noise and interference components from the voltage signal, ensuring the stability of the signal received by the control module and ensuring the stable operation of the entire detection circuit.

[0020] In a further embodiment, the on / off control module includes a field-effect transistor Q1, which is an LG90N3K5GJ type field-effect transistor. The drain of the field-effect transistor Q1 is connected to pin 1 of the transformer, the source of the field-effect transistor is grounded, and the gate of the field-effect transistor is connected to the signal output terminal of the control module. The field-effect transistor Q1 can quickly change its conduction state according to the signal of the control module, thereby realizing rapid detection and protection of the current of the circuit under test.

[0021] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. An overcurrent detection circuit, characterized in that, The system includes a transformer. Pins 1 and 2 of the primary side of the transformer are connected in series with the circuit under test. Pins 3 and 4 of the secondary side of the transformer are connected to the input of a rectifier circuit. The output of the rectifier circuit is connected to the input of a filter circuit. The output of the filter circuit is connected to the input of a control module. The output of the control module is connected to the input of a switching control module. The output of the switching control module is connected to pin 1 of the primary side of the transformer. The control module obtains the voltage at the output of the filter circuit and sends a signal to the switching control module, which controls the switching of the transformer.

2. The overcurrent detection circuit according to claim 1, characterized in that, The rectifier circuit includes diodes D1, D2, D3, and D4, and resistor R2. Pin 3 of the transformer is connected to the anode of diode D1 and the cathode of diode D3. Pin 4 of the transformer is connected to the anode of diode D2 and the cathode of diode D4. The anode of diode D3 is connected to the anode of diode D4 and one end of resistor R2. The cathode of diode D1 is connected to the cathode of diode D2 and the other end of resistor R2. The other end of resistor R2 is connected to the input terminal of the filter circuit.

3. The overcurrent detection circuit according to claim 2, characterized in that, Diodes D1, D2, D3, and D4 are all LBAT54SLT1G type diodes.

4. The overcurrent detection circuit according to claim 1, characterized in that, The filter sub-circuit includes a resistor R3 and a capacitor C1. One end of the resistor R3 is connected to the output terminal of the rectifier bridge sub-circuit, and the other end of the resistor R3 is connected to one end of the capacitor C1 and the control module. The other end of the capacitor C1 is connected to the control module.

5. The overcurrent detection circuit according to claim 1, characterized in that, The on / off control module includes a field-effect transistor Q1. The drain of the field-effect transistor Q1 is connected to pin 1 of the transformer, the source of the field-effect transistor is grounded, and the gate of the field-effect transistor is connected to the signal output terminal of the control module.

6. The overcurrent detection circuit according to claim 1, characterized in that, It also includes a resistor R1, one end of which is connected to pin 2 of the transformer. The resistor R1 is used for current limiting protection of the transformer. The transformer is a CT2 type transformer, and the resistor is an EWWR0010J10R0T9 type resistor.

7. The overcurrent detection circuit according to claim 1, characterized in that, The control module uses an AVP32F335-176 chip.

8. An overcurrent detection circuit according to claim 5, characterized in that, The field-effect transistor Q1 is an LG90N3K5GJ model field-effect transistor.

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