Power supply overcurrent protection control circuit

Abstract

The invention relates to a power supply overcurrent protection control circuit which is composed of a temperature acquisition circuit unit, a current detection circuit unit, a voltage acquisition circuit unit and a control circuit unit. The temperature acquisition circuit unit acquires the temperature of the whole circuit in operation; the current detection circuit unit completes a current detection function, accurately obtains the internal resistance of the MOSFET at the current temperature according to a curve of the internal resistance of the MOSFET in the circuit changing along with the temperature and the acquired temperature, and accurately converts the detected current into voltage, and the voltage acquisition circuit unit acquires the voltage value and uploads the voltage value to the control circuit unit MCU; the control circuit unit controls the on-off of the MOSFET tube according to the collected voltage value so as to complete the control of the output voltage. The system has the advantages that the power supply overcurrent protection function is completed by combining software and hardware, so that the stability and the anti-interference performance of the system are increased by one order of magnitude; and accurate over-current detection is realized by using a curve graph that the internal resistance of the MOSFET changes along with the temperature.

Description

Technical Field

[0001] This invention belongs to the field of power protection technology, and in particular relates to an overcurrent protection control circuit for an airborne power management unit. Background Technology

[0002] Current research on overcurrent protection circuits, both domestically and internationally, focuses primarily on providing overcurrent protection functionality. However, there is limited attention paid to practical engineering applications such as precise overcurrent point control, short-circuit power dissipation, and capacitive load capacity. Temperature compensation design for overcurrent protection circuits is particularly scarce. Because the on-resistance of MOSFETs is easily affected by external temperature variations, using MOSFET on-resistance sampling to implement overcurrent protection significantly impacts the accuracy of the overcurrent point, leading to poor product reliability and compromising equipment safety. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings and deficiencies of using the on-resistance of a MOSFET to sample and implement overcurrent protection, and to provide a power supply overcurrent protection control circuit.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A power supply overcurrent protection control circuit is characterized by a current detection circuit unit, which is composed of a temperature acquisition circuit unit, a voltage acquisition circuit unit, and a control circuit unit.

[0006] The temperature acquisition circuit unit mainly acquires the temperature during the entire circuit operation process;

[0007] The current detection circuit unit completes the MOSFET current detection function. Based on the curve of the MOSFET internal resistance changing with temperature in the circuit loop and the temperature collected by the temperature acquisition circuit, it accurately obtains the MOSFET internal resistance at the current temperature, and then converts the detected current into voltage.

[0008] The voltage acquisition circuit unit acquires the voltage value output by the current detection circuit and uploads it to the control circuit unit.

[0009] The control circuit unit controls the switching of the MOSFET transistors based on the acquired voltage value to control the output voltage.

[0010] Based on the above technical solution, the following further technical solutions are proposed:

[0011] The current detection circuit unit consists of a common-mode inductor L8, capacitors C15 and C16, resistors R1 and R2, Zener diode V3, diode V2, optocoupler E1, resistor R3, transistor V4, resistor R4, and MOSFET Q1. Two terminals of the common-mode inductor L8 are connected to one end of capacitors C15 and C16 and one end of resistor R1. The other ends of capacitors C15 and C16 are connected to ground. The other end of resistor R1 intersects at one point with one end of resistor R2, the cathode of Zener diode V3, and the anode of diode V2. The other end of resistor R2, the positive terminal of Zener diode V3, and the fourth terminal of common-mode inductor L8 are connected to the source of MOSFET Q1. The negative terminal of diode V2 and the gate of MOSFET Q1 are connected to the collector terminal of optocoupler E1. The two ends of resistor R3 are connected to the power supply and the Anode terminal of optocoupler E1, respectively. The two ends of resistor R4 are connected to the base of transistor V4 and the second pin of microcontroller N1, respectively. The emitter of transistor V4 is connected to the Cathode terminal of optocoupler E1, and the collector is connected to digital ground DGND.

[0012] The control circuit unit mainly consists of a microcontroller N1, an interface J20, and a capacitor. Ports 4 and 6 of the microcontroller N1 are connected to the two ends of the capacitor C6, and the interface J20 is connected to the 9th and 10th ends of N1.

[0013] The temperature acquisition circuit unit consists of resistors R163, R164, and R165, capacitor C218, temperature acquisition chip N35, and microcontroller N1. One end of resistors R163, R164, R165, and capacitor C218 intersects at a point and is connected to the positive terminal of the power supply. The other end of capacitor C218 is connected to the negative terminal of the power supply. The other end of R163 intersects at a point with terminal 6 of temperature acquisition chip N35 and is connected to pin 18 of microcontroller N1. The other end of R164 intersects at a point with terminal 3 of temperature acquisition chip N35 and is connected to pin 16 of microcontroller N1. The other end of R165 intersects at a point with terminal 1 of temperature acquisition chip N35 and is connected to pin 17 of microcontroller N1.

[0014] The voltage acquisition circuit unit consists of resistors R37, R30, R31, and R32, capacitor C33, diodes D3 and D4, and microcontroller N1. One end of resistor R37 is connected to the drain of MOSFET Q1 and the power supply output ground. The other end of resistor R37 is connected to one end of resistor R30. The other end of resistor R30 intersects with one end of capacitor C33, one end of resistor R31, and one end of resistor R32 at a point. The other end of resistor R31 intersects with the other end of capacitor C33 and the anode of diode D4 at a point and is connected to the negative terminal of the power supply. The other end of resistor R32 intersects with the cathode of diode D4 and the anode of diode D3 at a point and is connected to terminal 1 of microcontroller N1. The cathode of diode D3 is connected to the positive terminal of the power supply.

[0015] Compared with existing technologies, the present invention has the following advantages:

[0016] 1. This invention uses a combination of hardware and software to complete the power supply overcurrent protection function, which increases the system's stability and anti-interference ability by an order of magnitude;

[0017] 2. This invention utilizes the curve of MOSFET internal resistance changing with temperature to select different on-resistance of MOSFETs according to different temperatures in the circuit to achieve accurate overcurrent detection. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic block diagram of the overcurrent protection control circuit of the present invention.

[0019] Figure 2 This is the schematic diagram of the current detection circuit unit of the present invention;

[0020] Figure 3 This is a schematic diagram of the temperature acquisition circuit unit of the present invention;

[0021] Figure 4 This is a schematic diagram of the voltage acquisition circuit unit of the present invention;

[0022] Figure 5 This is the schematic diagram of the control circuit unit of the present invention;

[0023] Figure 6 The diagram shown is a waveform diagram of the overcurrent protection circuit of the present invention during operation. Detailed Implementation

[0024] like Figure 1 As shown, this invention designs a power supply overcurrent protection control circuit, mainly used in the field of airborne power supply, which consists of a temperature acquisition circuit unit, a current detection circuit unit, a voltage acquisition circuit unit and a control circuit unit;

[0025] The temperature acquisition circuit unit mainly collects the temperature during the entire circuit's operation.

[0026] The current detection circuit unit mainly performs the function of MOSFET current detection. Based on the curve of MOSFET internal resistance changing with temperature in the circuit loop and the temperature collected by the temperature acquisition circuit, it accurately obtains the MOSFET internal resistance at the current temperature, and then accurately converts the detected current into voltage.

[0027] The voltage acquisition circuit unit acquires the voltage value output by the current detection circuit and uploads it to the MCU;

[0028] The voltage acquisition circuit unit acquires the voltage value output by the current detection circuit and uploads it to the MCU; the control circuit unit mainly controls the switching of the MOSFET transistor to control the output voltage based on the acquired voltage value.

[0029] The control circuit unit mainly controls the switching of MOSFETs based on the acquired voltage value to control the output voltage.

[0030] like Figure 2 As shown, the current detection circuit unit consists of a common-mode inductor L8, capacitors C15 and C16, resistors R1 and R2, Zener diode V3, diode V2, optocoupler E1, resistor R3, transistor V4, resistor R4, and MOSFET Q1. The second terminal of the common-mode inductor L8 is connected to one end of capacitors C15 and C16 and one end of resistor R1. The other ends of capacitors C15 and C16 are connected to ground. The other end of resistor R1 is connected to one end of resistor R2, the cathode of Zener diode V3, and the cathode of diode V2. The positive terminals intersect at one point. The other end of resistor R2, the positive terminal of Zener diode V3, and the fourth terminal of common-mode inductor L8 are connected to the source of MOSFET Q1. The negative terminal of diode V2 and the gate of MOSFET Q1 are connected to the collector terminal of optocoupler E1. The two ends of resistor R3 are connected to the power supply and the Anode terminal of optocoupler E1, respectively. The two ends of resistor R4 are connected to the base of transistor V4 and pin 2 of microcontroller N1, respectively. The emitter of transistor V4 is connected to the Cathode terminal of optocoupler E1. — The collector is connected to DGND (the zero-potential reference of the digital circuit).

[0031] like Figure 3 As shown, the temperature acquisition circuit unit consists of resistors R163, R164, and R165, capacitor C218, temperature acquisition chip N35, and microcontroller N1 (see [link to diagram]). Figure 5 The circuit consists of resistors R163, R164, and R165, and capacitor C218, which intersect at one point and are connected to the positive terminal of the power supply (+3.8V). The other end of capacitor C218 is connected to the negative terminal of the power supply. The other end of R163 intersects with terminal 6 of the temperature acquisition chip N35 and is connected to pin 18 of the microcontroller N1. The other end of R164 intersects with terminal 3 of the temperature acquisition chip N35 and is connected to pin 16 of the microcontroller N1. The other end of R165 intersects with terminal 1 of the temperature acquisition chip N35 and is connected to pin 17 of the microcontroller N1.

[0032] like Figure 4 As shown, the voltage acquisition circuit unit consists of resistors R37, R30, R18, R31, and R32, capacitor C33, diodes D3 and D4, and microcontroller N1 (see [link to microcontroller]). Figure 5The circuit consists of: one end of resistor R37 is connected to the drain of MOSFET Q1 and the power supply output ground; the other end of resistor R37 is connected to one end of resistor R30; the other end of resistor R30 intersects with one end of capacitor C33, one end of resistor R31, and one end of resistor R32 at a point; the other end of resistor R31 intersects with the other end of capacitor C33 and the anode of diode D4 at a point and is connected to the negative terminal of the power supply; the other end of resistor R32 intersects with the cathode of diode D4 and the anode of diode D3 at a point and is connected to terminal 1 of microcontroller N1; and the cathode of diode D3 is connected to the positive terminal of the power supply.

[0033] like Figure 5 As shown, the control circuit unit mainly consists of a microcontroller N1, an interface J20, and a capacitor. Ports 4 and 6 of the microcontroller N1 are connected to the two ends of the capacitor C6, and the interface J20 is connected to the 9th and 10th ends of N1. The MCU is an STM32F103 microcontroller.

[0034] like Figure 2 As shown, when the circuit system is working, taking an input voltage of 18V and a maximum output current of 30A as an example, when the input voltage is 18V, the circuit system operates normally with an output current less than 30A. The microcontroller provides I / O1 port with a high level, the PNP transistor V4 is not conducting, the LED in optocoupler E1 is not conducting, and the transistor is also not conducting. The input voltage is filtered by capacitors C15 and C16 and then divided by resistors R1 and R2 to obtain a voltage value. By adding a Zener diode V3, the gate voltage of MOSFET Q1 is prevented from being too high and burning out MOSFET Q1. The voltage divided by resistors R1 and R2 is applied to the gate of MOSFET Q1 through diode V2, making the voltage VGS greater than the conduction threshold voltage of MOSFET Q1, so that MOSFET Q1 conducts and the power supply outputs normally.

[0035] When the circuit system operates with an output current greater than 30A (i.e., under overcurrent conditions), the input voltage is filtered by capacitors C15 and C16, then divided by resistors R1 and R2 to obtain a voltage value, which is applied to the gate of MOSFET Q1 through diode V2. The temperature sensor N35 collects the temperature and uploads it to the microcontroller N1. The microcontroller N1 determines the current on-resistance of MOSFET Q1 based on the collected temperature, thereby accurately determining the overcurrent voltage threshold of the circuit. The voltage acquisition circuit uploads the collected voltage to the microcontroller N1 and compares it with the overcurrent voltage threshold set internally by the microcontroller N1. If it is greater than the overcurrent voltage threshold, the microcontroller N1 provides I / O1 port to low level, PNP transistor V4 conducts, which turns on the LED in optocoupler E1, thus turning on the transistor in optocoupler E1. The gate voltage VGS of MOSFET Q1 is less than the on-resistance threshold voltage of MOSFET Q1, so MOSFET Q1 does not conduct, and there is no power output, thus achieving the overcurrent protection function.

[0036] like Figure 6 The diagram shows the waveform of the overcurrent protection control circuit during operation. In the overcurrent state, the microcontroller N1 provides a low level for I / O1, and the control power supply has no output. Then, the microcontroller N1 checks for overcurrent again, which is a cyclic process. The program detection and execution have a certain delay, so there is a spike when the power supply has no output in the overcurrent state.

Claims

1. A power supply overcurrent protection control circuit, characterized by The current detection circuit unit, the temperature acquisition circuit unit, the voltage acquisition circuit unit and the control circuit unit are composed; The temperature acquisition circuit unit mainly acquires the temperature in the whole circuit working process; The current detection circuit unit completes the MOSFET current detection function, according to the curve diagram of the MOSFET internal resistance changing with temperature in the circuit loop and the temperature acquired by the temperature acquisition circuit, the MOSFET internal resistance at the current temperature is accurately obtained, and then the detected current is converted into voltage; The voltage acquisition circuit unit acquires the voltage value output by the current detection circuit and uploads it to the control circuit unit; The control circuit unit controls the on-off of the MOSFET according to the acquired voltage value to complete the control of the output voltage.

2. The power overcurrent protection control circuit according to claim 1, characterized in that: The current detection circuit unit is composed of a common mode inductor L8, a capacitor C15, a capacitor C16, a resistor R1, a resistor R2, a voltage stabilizing diode V3, a diode V2, an optical coupler E1, a resistor R3, a triode V4, a resistor R4 and a MOSFET Q1, the two ends of the common mode inductor L8 are connected with the capacitor C15, the capacitor C16 and one end of the resistor R1, the other ends of the capacitor C15 and the capacitor C16 are connected with the ground, one end of the resistor R1, the other end of the resistor R2, the negative electrode of the voltage stabilizing diode V3 and the positive electrode of the diode V2 are connected at a point, the other end of the resistor R2, the positive electrode of the voltage stabilizing diode V3, the four end of the common mode inductor L8 and the source electrode of the MOSFET Q1 are connected, the negative electrode of the diode V2 and the gate electrode of the MOSFET Q1 are connected with the Collector end of the optical coupler E1, the two ends of the resistor R3 are respectively connected with the power supply and the Anode end of the optical coupler E1, the two ends of the resistor R4 are respectively connected with the base electrode of the triode V4 and the 2 pin of the single-chip microcomputer N1, the emitter electrode of the triode V4 is connected with the Cathode end of the optical coupler E1, and the collector electrode is connected with the digital ground DGND.

3. The power overcurrent protection control circuit according to claim 2, characterized in that: The control circuit unit is mainly composed of a single-chip microcomputer N1, an interface J20 and a capacitor, the 4 port and the 6 port of the single-chip microcomputer N1 are connected with the two ends of the capacitor C6, and the interface J20 is connected with the 9 end and the 10 end of N1.

4. The power overcurrent protection control circuit according to claim 3, characterized in that: The temperature acquisition circuit unit is composed of a resistor R163, a resistor R164, a resistor R165, a capacitor C218, a temperature acquisition chip N35 and a single-chip microcomputer N1, one end of the resistor R163, the resistor R164, the resistor R165 and the capacitor C218 is connected with the positive electrode of the power supply, the other end of the capacitor C218 is connected with the negative electrode of the power supply, the other end of R163, the 6 end of the temperature acquisition chip N35 is connected with the 18 pin of the single-chip microcomputer N1, the other end of R164, the 3 end of the temperature acquisition chip N35 is connected with the 16 pin of the single-chip microcomputer N1, the other end of R165, the 1 end of the temperature acquisition chip N35 is connected with the 17 pin of the single-chip microcomputer N1.

5. The power overcurrent protection control circuit according to claim 4, characterized in that: The voltage acquisition circuit unit is composed of resistor R37, resistor R30, resistor R31, resistor R32, capacitor C33, diode D3, diode D4 and single-chip microcomputer N1. One end of resistor R37 is connected with the drain of MOSFET tube Q1 and the output ground of the power supply, the other end of resistor R37 is connected with one end of resistor R30, the other end of resistor R30 is connected with one end of capacitor C33, one end of resistor R31 and one end of resistor R32, the other end of resistor R31 is connected with the other end of capacitor C33 and the anode of diode D4, the other end of resistor R32 is connected with the cathode of diode D4 and the anode of diode D3, and the other end of diode D3 is connected with the 1 end of single-chip microcomputer N1, the cathode of diode D3 is connected with the positive pole of the power supply.

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