Continuous-working low-power-consumption current limiting system

Abstract

The utility model discloses a continuous work low power consumption current limiting system, including PTC, MOSFET, control circuit and current limiting resistor, the PTC and MOSFET are connected in series and then are connected in parallel with current limiting resistor, the MOSFET is also connected with the control circuit. According to the utility model, two impact current suppression settings based on the PTC and the MOSFET are combined, the two impact current suppression settings complement each other, and the current limiting of the airborne equipment in the whole process from power-on to power-off is realized. And the problem of high power consumption of a passive impulse current suppression circuit is solved by utilizing the advantage of low power consumption of the MOSFET impulse current suppression circuit during the steady-state working period. Meanwhile, the MOSFET circuit and the PTC resistor which are designed and adopted are small in size, so that the circuit is more practical for miniaturized airborne electronic equipment.

Description

Technical Field

[0001] The utility model belongs to the field of aviation electrical technology, and in particular relates to a continuous operation low power consumption current limiting system. Background Art

[0002] When airborne electronic equipment is powered on, it generates inrush currents due to factors such as capacitor charging and discharging and chip startup. Excessive inrush currents are not only harmful to the electronic products themselves but also to the quality of the power supply system. GJB181B, "Aircraft Power Supply Characteristics," requires: "Unless otherwise specified, when a power-consuming device (excluding incandescent lamps) with a power greater than 200W is suddenly subjected to rated voltage, the peak inrush current generated shall not exceed five times the rated current and shall return to the rated current within 0.1s." Currently, specific airborne specifications rarely distinguish between power-consuming devices and require that "the peak inrush current generated by airborne electronic equipment shall not exceed five times the rated current and shall return to the rated current within 0.1s." Therefore, this inrush current performance requirement has been extended to all airborne equipment.

[0003] Common inrush current suppression methods for airborne electronic equipment include those based on passive devices and those based on MOSFETs. One type of inrush current suppression circuit relies on passive devices. This method connects a passive current-limiting device, such as a fixed resistor of appropriate value or an NTC, in series with the power line to limit the current to no more than the theoretical value of the current-limiting device. This method features a simple circuit and is effective throughout the entire operating period. However, since the series-connected device is an energy-consuming device, it continuously consumes power during operation, resulting in high power consumption. Another type of inrush current suppression circuit relies on MOSFETs. This circuit generally achieves current limiting by controlling the switching state of a MOSFET connected in series with the power line. This effectively addresses the shortcomings of passive device-based inrush current suppression circuits, while offering flexible design and a wide range of applications. MOSFET-based inrush current suppression circuits are categorized as active and passive. Active types utilize an independent digital control circuit to control the MOSFET gate, effectively controlling the output current. However, due to the need for an independent power supply control circuit, these devices suffer from drawbacks such as large size, independent power supply, and complex circuitry, making them unsuitable for small, high-reliability applications. Examples include: CN113067464A "NMOS Power Tube Gate Driver Module, Driver Circuit, and Switching Power Supply," CN109861356A "Inrush Current Suppression Module, On-Board Bidirectional Charger, and Control," CN111244882A "Overcurrent Protection Circuit and Self-Test Method," CN111697806A "A Power Supply Inrush Current Suppression Circuit," CN113328660A "A Control Circuit with Inrush Current Suppression," and CN215871172U "An Inrush Current Protection Circuit." Passive devices do not require independent digital control circuitry and offer low power consumption and a small size, making them suitable for increasingly miniaturized airborne electronic equipment. However, these circuits, which rely on the charging and discharging of resistor-capacitor circuits to achieve inrush current suppression, are only effective during power-up and cannot provide current limiting protection during steady-state operation. During the steady-state process, if the product's rear-end load is abnormal or a short-circuit fault occurs, it will still cause harm to the aircraft's power supply system, such as: CN212033769U "Inrush current suppression circuit", CN212163158U "A surge current peak and rising slope suppression circuit", CN213879275U "A surge current limiting circuit", CN215498261U "Start-up surge current suppression device and suppression system".

[0004] A PTC (positive temperature coefficient) thermistor (PTC) is a resistor whose resistivity increases with increasing temperature. Widely used in overcurrent protection circuits, this device is also known as a "resettable fuse." PTCs sense current throughout the circuit's full operating time. When the current exceeds the rated value, they self-heat and initiate current limiting protection. However, due to their slow response speed and the need for cooling during the recovery process, they do not meet the real-time startup requirements of airborne electronic equipment. Therefore, they cannot be directly connected in series to airborne equipment power lines as inrush current suppression devices or overcurrent protection devices. Utility Model Content

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a continuous operation low-power current limiting system which solves the problem of high power consumption of passive inrush current suppression circuits.

[0006] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a continuous working low-power current limiting system, including a PTC, a MOSFET, a control circuit and a current limiting resistor, wherein the PTC and the MOSFET are connected in series and in parallel with the current limiting resistor, and the MOSFET is also connected to the control circuit.

[0007] Furthermore: the PTC is provided with a resistor R1, and the model of the resistor R1 is MZ2-7555;

[0008] One end of the resistor R1 is connected to the IN+ terminal of the power input and the current limiting resistor respectively, and the other end of the resistor R1 is connected to the MOSFET and the control circuit respectively.

[0009] Furthermore: the current limiting resistor is provided with a high-power resistor R2, one end of the high-power resistor R2 is connected to the IN+ end of the power input, and the other end of the high-power resistor R2 is connected to the MOSFET.

[0010] Furthermore: the MOSFET is provided with a field effect tube V1, and the model of the field effect tube V1 is CS9130S;

[0011] The drain of the field effect transistor V1 is connected to the other end of the resistor R1, the source of the field effect transistor V1 is connected to the other end of the resistor R2 and the OUT+ end of the load, and the gate of the field effect transistor V1 is connected to the control circuit.

[0012] Furthermore: the control circuit includes a capacitor C1, a resistor R3, a resistor R4 and a voltage stabilizing diode D1;

[0013] Among them, one end of the capacitor C1 is respectively connected to one end of the resistor R3, the cathode of the Zener diode D1 and the drain of the field effect transistor V1, the other end of the capacitor C1 is respectively connected to the other end of the resistor R3, the anode of the Zener diode D1, the gate of the field effect transistor V1 and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to the IN- terminal of the power input and the OUT- terminal of the load.

[0014] The beneficial effects of the utility model are:

[0015] (1) This utility model provides a continuous operation low-power current limiting system. It combines two inrush current suppression devices, PTC and MOSFET, to achieve full current limiting of airborne equipment from power-on to power-off. By utilizing the advantage of the MOSFET inrush current suppression circuit's low power consumption during steady-state operation, it solves the problem of high power consumption of passive inrush current suppression circuits. Furthermore, the MOSFET circuit and PTC resistor used in the design are compact, making them more practical for miniaturized airborne electronic equipment.

[0016] (2) The utility model can achieve current limiting protection for the power circuit during the entire operation process, from power-on to power-off. When the rear-end load is under normal operating conditions, the system circuit has low power consumption; when the rear-end load is under abnormal operating conditions, the circuit can effectively limit the power supply current, ensuring the safety of the aircraft power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a continuous operation low power consumption current limiting system of the utility model.

[0018] Figure 2 This is a circuit schematic diagram of a continuous operation low power consumption current limiting system of the utility model. DETAILED DESCRIPTION

[0019] The specific implementation methods of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific implementation methods. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations conceived using the present invention are protected.

[0020] like Figure 1 As shown, in one embodiment of the present invention, a continuous operation low power consumption current limiting system includes a PTC, a MOSFET, a control circuit and a current limiting resistor, wherein the PTC and the MOSFET are connected in series and in parallel with the current limiting resistor, and the MOSFET is also connected to the control circuit.

[0021] The PTC is installed before and connected to the power input. It limits current during the entire operating period, maintaining the operating current within a specified value from power-on to power-off. If the current exceeds the specified value, the PTC shuts off, directing the operating power path to the current-limiting resistor.

[0022] MOSFETs are used for current limiting during power-up. As a switching device connected in series with the power line, their on / off states are controlled by a control circuit. From power-up to normal operation, the device transitions between the off-state, variable resistance, and saturation regions, limiting the power-up surge current to no more than five times the rated current and returning to the rated current within 0.1s.

[0023] The current limiting resistor is placed before the power input and connected to the power input. It is used to operate when either the PTC or the MOSFET is turned off. At this time, the current value transmitted to the downstream load will not exceed the limit value of the current limiting resistor.

[0024] The control circuit is used to output a control signal and control the switching state of the MOSFET tube by utilizing the charging and discharging principle of the resistance-capacitance circuit when the product is powered on, so that the MOSFET is in the off zone at the beginning of power-on, and the rear-end load is charged with a current not greater than the limit value of the current-limiting resistor. At this time, the circuit power consumption is the largest; in the middle of power-on, the MOSFET is in the variable resistance zone, and the MOSFET gradually releases the current limit. At this time, the circuit power consumption gradually decreases; after power-on is completed, the MOSFET is in the saturation zone, and the circuit power consumption is reduced to a minimum.

[0025] When airborne electronic equipment is powered on, it will generate surge current due to capacitor charging and discharging, chip startup, etc. Excessive surge current is not only harmful to the electronic products themselves, but also to the power supply quality of the power supply system. Airborne electronic equipment also has clear technical requirements for surge current. This utility model addresses the shortcomings of the existing technology and provides a continuous working low power consumption current limiting system. The schematic diagram is as follows: Figure 2 As shown, this circuit is applicable to, but not limited to, DC28V power line inrush current suppression.

[0026] like Figure 2 As shown, the PTC is provided with a resistor R1, and the model of the resistor R1 is MZ2-7555;

[0027] One end of the resistor R1 is connected to the IN+ terminal of the power input and the current limiting resistor respectively, and the other end of the resistor R1 is connected to the MOSFET and the control circuit respectively.

[0028] The current limiting resistor is provided with a high-power resistor R2, one end of the high-power resistor R2 is connected to the IN+ end of the power input, and the other end of the high-power resistor R2 is connected to the MOSFET.

[0029] The MOSFET is provided with a field effect tube V1, and the model of the field effect tube V1 is CS9130S;

[0030] The drain of the field effect transistor V1 is connected to the other end of the resistor R1, the source of the field effect transistor V1 is connected to the other end of the resistor R2 and the OUT+ end of the load, and the gate of the field effect transistor V1 is connected to the control circuit.

[0031] The control circuit includes a capacitor C1, a resistor R3, a resistor R4 and a voltage stabilizing diode D1;

[0032] Among them, one end of the capacitor C1 is respectively connected to one end of the resistor R3, the cathode of the Zener diode D1 and the drain of the field effect transistor V1, the other end of the capacitor C1 is respectively connected to the other end of the resistor R3, the anode of the Zener diode D1, the gate of the field effect transistor V1 and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to the IN- terminal of the power input and the OUT- terminal of the load.

[0033] In this embodiment, the model of the capacitor C1 is CT41-1210-2R1-100V-10, the model of the resistor R3 is RMK3216-HB-2492-BM, the model of the resistor R4 is RMK3216-KB-223-FM, and the model of the Zener diode D1 is 1N4742.

[0034] The working process of the system of the utility model is as follows: the continuous operation low-power current limiting system is turned on. During the system power-on process, the current limiting resistor works so that the current value transmitted to the back-end load will not exceed the limit value of the current limiting resistor. Under the control of the control circuit, the MOSFET realizes the conversion process from the shutdown region → the variable resistance region → the saturation region. The above process limits the maximum current during the power-on process while gradually reducing the overall power consumption of the current circuit, and finally stabilizes to the lowest power consumption state. At the same time, because the PTC and MOSFET are connected in series on the line, when the back-end load experiences a long-term overcurrent due to load changes, short circuits, etc., the PTC is turned off, and the maximum current is limited by the current limiting resistor, ensuring that the power supply quality of the power supply system is not damaged.

[0035] The beneficial effects of this utility model include: providing a continuous-operation, low-power current-limiting system that combines PTC and MOSFET-based inrush current suppression, leveraging their strengths to overcome their weaknesses and achieving full current limiting for airborne equipment from power-up to power-down. Utilizing the low power consumption of MOSFET inrush current suppression circuits during steady-state operation, this system overcomes the high power consumption of passive inrush current suppression circuits. Furthermore, the MOSFET circuit and PTC resistor employed in this design are compact, making them more practical for miniaturized airborne electronic equipment.

[0036] This utility model provides current-limiting protection for the power circuit throughout its entire operating cycle, from power-up to power-down. Under normal operating conditions, the system's circuit consumes minimal power. Under abnormal operating conditions, the circuit effectively limits the power supply current, ensuring the safety of the aircraft's power system.

[0037] In the description of the present invention, it should be understood that the terms "center", "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "radial", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying the relative importance or the number of technical features implicitly specified. Therefore, the features defined by "first", "second", and "third" may explicitly or implicitly include one or more of such features.

Claims

1. A continuous working low power consumption current limiting system, characterized in that: The invention comprises a PTC, a MOSFET, a control circuit and a current-limiting resistor, wherein the PTC and the MOSFET are connected in series and then connected in parallel with the current-limiting resistor, and the MOSFET is also connected to the control circuit.

2. The continuous operation low power consumption current limiting system according to claim 1, characterized in that: The PTC is provided with a resistor R1, and the model of the resistor R1 is MZ2-7555; One end of the resistor R1 is connected to the IN+ terminal of the power input and the current limiting resistor respectively, and the other end of the resistor R1 is connected to the MOSFET and the control circuit respectively.

3. The continuous operation low power consumption current limiting system according to claim 2, characterized in that: The current limiting resistor is provided with a high-power resistor R2, one end of the high-power resistor R2 is connected to the IN+ end of the power input, and the other end of the high-power resistor R2 is connected to the MOSFET.

4. The continuous operation low power consumption current limiting system according to claim 3, characterized in that: The MOSFET is provided with a field effect tube V1, and the model of the field effect tube V1 is CS9130S; The drain of the field effect transistor V1 is connected to the other end of the resistor R1, the source of the field effect transistor V1 is connected to the other end of the resistor R2 and the OUT+ end of the load, and the gate of the field effect transistor V1 is connected to the control circuit.

5. The continuous operation low power consumption current limiting system according to claim 4, characterized in that: The control circuit includes a capacitor C1, a resistor R3, a resistor R4 and a voltage stabilizing diode D1; Among them, one end of the capacitor C1 is respectively connected to one end of the resistor R3, the cathode of the Zener diode D1 and the drain of the field effect transistor V1, the other end of the capacitor C1 is respectively connected to the other end of the resistor R3, the anode of the Zener diode D1, the gate of the field effect transistor V1 and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to the IN- terminal of the power input and the OUT- terminal of the load.

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