Airborne electronic equipment reverse connection prevention circuit based on 270V power supply and design method thereof

Abstract

The invention relates to an airborne electronic equipment reverse connection prevention circuit based on a 270V power supply and a design method thereof, the airborne electronic equipment reverse connection prevention circuit comprises a resistor R1, a resistor R2, a voltage stabilizing diode D1 and an NMOS field effect transistor Q1, the grid voltage of an NMOS transistor is reduced from 270VDC to 9.5-15V and is stabilized at 15VDC, and therefore it is guaranteed that the NMOS transistor cannot be broken down when the voltage fluctuates; through the resistor R1 and the resistor R2, performance reduction of the airborne electronic equipment caused by voltage drop and power consumption generated by the reverse connection circuit is eliminated, meanwhile, the heating value of the airborne electronic equipment is reduced, the weight of the airborne electronic equipment is reduced, the service life of the airborne electronic equipment is prolonged, and the use safety of the airborne electronic equipment is improved. When the positive electrode and the negative electrode of airborne electronic equipment are reversely connected, the grid voltage of the NMOS field-effect tube is smaller than 2V, so that the NMOS field-effect tube is in a turn-off state, and the ground wire of the power supply is disconnected, so that the effect of protecting a post-stage circuit from being damaged due to breakdown of components caused by reverse connection of the power supply is achieved, and the safety of an all-electric braking system or a cooling system is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of airborne electronic technology of aircraft all-electric brake system or cooling system, and particularly relates to an airborne electronic device anti-reverse connection circuit based on 270V DC power supply. BACKGROUND

[0002] Most airborne electronic devices are powered by 28V DC power supply; with the development of modern aircraft technology and the comprehensive application of all-electric technology, the power supply voltage on the aircraft is getting higher and higher, and 115V AC and 270V DC power supply appear, and even 540V DC high-voltage DC power supply appears; most of the control parts of airborne electronic devices are powered by 28V DC, but the execution part circuit is basically powered by 270V DC and 540V DC; in the design process of airborne electronic devices including all-electric brake system or cooling system, power supply anti-reverse connection design is required.

[0003] The anti-reverse connection protection circuit in the prior art refers to the protection measures for preventing the reverse connection of the power supply in the circuit. In order to realize the damage to the circuit caused by the accidental reverse connection of the DC input, a power diode is usually connected in series on the input line. In general, for airborne electronic devices with a rated current less than 2A, most of them use the unidirectional conductivity of the power diode to realize the anti-reverse connection protection. The power diode has a large volume, and the power loss of the power diode in the circuit is serious. The unidirectional conductivity of the diode is used to realize the anti-reverse connection protection, which is simple and reliable, but the power consumption is very large in the case of large input current. For example, if the input current rating is 2A, the power consumption of the fast recovery diode with a rated voltage drop of 0.7V is at least 1.4W, which is low in efficiency and large in heat generation. However, the voltage drop on the diode will consume energy. For example, when the input current is 2A, the power consumption of the circuit is 2.8W. Especially in the development trend of high-power power supply, the power loss of the power diode is more serious, and in addition, the large-power power diode can also generate a large amount of heat energy. This scheme greatly occupies the circuit board area, has low reliability, and even needs a heat sink.

[0004] If the unidirectional conductivity of the diode is used to realize the anti-reverse connection protection of the 270V DC voltage, the power consumption will increase greatly, which not only puts higher requirements on the voltage drop and heat generation of the diode and the power, but also directly causes the reduction of the actual voltage and power used by the airborne electronic device due to the increase of the power of the diode, which puts higher requirements on the airborne electronic device.

[0005] In the standards HB 20326.8-2016, GJB 181B-2012 and HB 20326.7-2016, LDC602 reverse polarity and HDC602 reverse polarity have been taken as test detection requirements.

[0006] After retrieval, the utility model patent with publication number CN 215498272U proposes a kind of airborne anti-reverse connection protection power module, inside mainly is through the switch of MOS tube, realize input anti-reverse connection protection, when power supply is correctly connected, power supply normally supplies power to load.In the positive and negative electrode of power supply is reversed, disconnect load circuit, to protect the later stage circuit, this scheme greatly reduces the overall power consumption of anti-reverse connection protection circuit, also can reduce the heat energy generated in circuit, meet the current environmental protection concept.But, the input voltage range of this airborne anti-reverse connection protection power module is 18 ~ 36Vdc input, output is 28V;Cannot adapt to the requirement of 270VDC power input anti-reverse connection. SUMMARY

[0007] In order to overcome the deficiencies of high heat dissipation and serious power consumption of 270V DC high-voltage circuit anti-reverse connection in the prior art, the present application proposes an airborne electronic equipment anti-reverse connection circuit based on 270V power supply and a design method thereof.

[0008] The airborne electronic equipment anti-reverse connection circuit based on 270V power supply proposed by the present application comprises a power supply, a power supply ground terminal, a power supply output terminal, a power supply ground terminal output terminal, a resistor R1, a resistor R2, a voltage stabilizing diode D1 and an NMOS field effect tube Q1. Among them, the resistor R1 is 200KΩ, the resistor R2 is 10KΩ, and the voltage stabilizing diode D1 has a voltage stabilizing voltage of 15V.

[0009] One end of the resistor R1 is connected between the power supply 1 and the power supply ground terminal output terminal;The other end of the resistor R1 is in communication with the G pole of the NMOS field effect tube. The negative terminal of the voltage stabilizing diode D1 is connected in parallel between the resistor R1 and the NMOS field effect tube Q1;The positive terminal of the voltage stabilizing diode D1 is connected between the power supply ground terminal and the power supply output terminal. The S pole of the NMOS field effect tube Q1 is in communication with the power supply output terminal, and the D pole of the NMOS field effect tube Q1 is in communication with the power supply ground terminal. One pin of the resistor R2 is connected in parallel between the S pole of the NMOS field effect tube Q1 and the power supply output terminal, and the other pin is connected in parallel between the resistor R1 and the voltage stabilizing diode D1.

[0010] The resistance value of the resistor R1 is 200KΩ, and the resistance value of the resistor R2 is 10KΩ.

[0011] The voltage stabilizing voltage of the voltage stabilizing diode D1 is 15V.

[0012] The threshold voltage power of the NMOS field effect tube Q1 is 2V-5V.

[0013] The specific process of designing the anti-reverse connection circuit proposed by the present application is as follows:

[0014] Step 1, determine the resistance parameter

[0015] The resistance comprises R1 and R2

[0016] Since the working voltage is 270VDC, the threshold voltage of the NMOS field effect transistor is 2V-5V, in order to ensure that the NMOS field effect transistor is successfully opened, the resistance value of R1 is determined as 200KΩ, and the resistance value of R2 is determined as 10KΩ.

[0017] The voltage U2 of R2 is R1U / (R1+R2).

[0018] Step 2, determining the parameters of the stabilizing diode;

[0019] The stabilizing voltage of the stabilizing diode D1 is determined as 15V.

[0020] Step 3, determining the parameters of the NMOS field effect transistor:

[0021] The threshold voltage power of the NMOS field effect transistor is 2V-5V.

[0022] The control process of the anti-reverse connection circuit used in the application is:

[0023] When the input voltage is 270V, the gate-source voltage of the NMOS field effect transistor is 12.85V, which is greater than the threshold voltage 2V-5V, and the NMOS field effect transistor is in a fully open state;

[0024] When the input voltage is 400V, the gate-source voltage of the NMOS field effect transistor is 19V, at this time, the voltage is stabilized to 15V through the stabilizing tube, which is greater than the threshold voltage 2V-5V, and the NMOS field effect transistor is in a fully open state;

[0025] When the input voltage is 200V, the gate-source voltage of the NMOS field effect transistor is 9.5V, which is greater than the threshold voltage 2V-5V, and the NMOS field effect transistor can be normally opened.

[0026] When the input voltage is reversed, the gate-source voltage of the NMOS field effect transistor is <2V, and the NMOS field effect transistor is in an off state, and the power ground is disconnected, so that the effect of protecting the rear-stage circuit from being damaged by the reverse connection voltage is achieved.

[0027] The anti-reverse connection circuit is based on the switching circuit of the NMOS field effect transistor, and the main feature is small on-state impedance and small size. The main principle is to divide the voltage through R1 and R2 resistors. The power consumption of the reverse connection circuit is reduced from 2.8W to <0.35W through the anti-reverse connection circuit, which eliminates the performance reduction of the airborne electronic equipment caused by the voltage drop and power consumption of the reverse connection circuit, at the same time, the heat of the airborne electronic equipment is reduced, which does not cause pressure on the equipment heat dissipation, prolongs the service life and safety of the airborne electronic equipment.

[0028] When the input voltage is 270VDC, the NMOS is fully open, and the 270VDC power supply meets the normal power supply requirements. When the input voltage is 400V, the gate voltage of the NMOS is 19V. At this time, the 15V Zener diode works to regulate the voltage to 15V, and the NMOS is fully open. When the input voltage is 200V, the gate voltage of the NMOS is 9.5V, which is greater than the threshold voltage of 5V, and the NMOS field-effect transistor can be turned on normally.

[0029] However, when the positive and negative terminals of the input power supply are reversed—that is, the positive terminal of the power input for the all-electric braking system or cooling system is connected to the negative terminal of the power supply, and the negative terminal of the power input for the all-electric braking system or cooling system is connected to the positive terminal of the power supply—when the input voltage of 200V to 400V is reversed, the gate voltage of the NMOS field-effect transistor is <2V. Therefore, the NMOS field-effect transistor is in the off state, and the power supply ground line is open. This can protect the downstream circuit from damage caused by component breakdown due to reverse power connection, thus ensuring the safety of the all-electric braking system or cooling system.

[0030] Compared with existing technologies, this invention uses a resistor voltage divider to reduce the gate voltage of the NMOS transistor from 270VDC to 9.5V~15V, and then stabilizes the voltage at 15VDC using a Zener diode, thus ensuring that the NMOS transistor will not break down during voltage fluctuations; the current through resistors R1 and R2 is 1.29mA, according to I... 2 R = 1.29mA × 1.29mA × 210kΩ ≈ 0.35W, reducing the power consumption of the reverse connection circuit from approximately 2.8W to below 0.35W. This eliminates the voltage drop and power consumption caused by the reverse connection circuit, which leads to a decrease in the performance of airborne electronic equipment. At the same time, it reduces the heat generation of airborne electronic equipment, preventing the need to add heat sinks or even cooling systems due to high heat generation. This indirectly reduces the weight of airborne electronic equipment, extends its lifespan, and improves its safety.

[0031] When the positive and negative terminals of airborne electronic equipment are reversed, the gate voltage of the NMOS field-effect transistor is less than 2V. Therefore, the NMOS field-effect transistor is in the off state, and the power supply ground line is open. This can protect the downstream circuit from damage caused by component breakdown due to reverse power connection, thus ensuring the safety of the all-electric braking system or cooling system. Attached Figure Description

[0032] Figure 1 This is the circuit diagram of the present invention.

[0033] 1. Power supply; 2. Power supply grounding terminal; 3. Power supply output terminal; 4. Power supply grounding terminal output terminal. Detailed Implementation

[0034] This embodiment is a reverse connection protection circuit for airborne electronic equipment based on a 270V power supply. The power supply voltage U of the airborne electronic equipment involved is 270VDC, the aircraft voltage is 240VDC to 300VDC, the minimum voltage is set to 200VDC, and the maximum voltage is set to 400VDC. The set voltage parameters can fully meet the requirements. The operating current of the airborne electronic equipment is no more than 2A.

[0035] This embodiment includes a power supply 1, a power supply ground terminal 2, a power supply output terminal 3, a power supply ground terminal output terminal 4, resistors R1 and R2, a Zener diode D1, and an NMOS field-effect transistor Q1. Specifically, resistor R1 is 200KΩ, resistor R2 is 10KΩ, and the Zener diode D1 provides a regulated voltage of 15V.

[0036] In the reverse connection protection circuit, one end of resistor R1 is connected between power supply 1 and power supply ground output terminal 4; the other end of resistor R1 is connected to the gate (G) of the NMOS field-effect transistor (FET). Resistor R1 is connected in parallel with the negative terminal of Zener diode D1 between NMOS field-effect transistor Q1; the positive terminal of Zener diode D1 is connected between power supply ground terminal 2 and power supply output terminal 3. The source (S) of NMOS field-effect transistor Q1 is connected to power supply output terminal 3, and the drain (D) of NMOS field-effect transistor Q1 is connected to power supply ground terminal 2. One pin of resistor R2 is connected in parallel between the source (S) of NMOS field-effect transistor Q1 and power supply output terminal 3, and the other pin is connected in parallel between resistor R1 and Zener diode D1.

[0037] The resistance of resistor R1 is 200KΩ, and the resistance of resistor R2 is 10KΩ.

[0038] The Zener diode D1 has a Zener voltage of 15V.

[0039] The threshold voltage power of the NMOS field-effect transistor Q1 is 2V to 5V.

[0040] The design process of the airborne electronic equipment reverse connection protection circuit proposed in this embodiment is as follows:

[0041] Step 1, Determine the resistance parameters

[0042] The resistors include R1 and R2.

[0043] Since the operating voltage is 270VDC and the threshold voltage of the NMOS field-effect transistor is 2V to 5V, in order to ensure that the NMOS field-effect transistor can be turned on smoothly, the resistance value of R1 is determined to be 200KΩ and the resistance value of R2 is 10KΩ.

[0044] The voltage U2 of R2 = R1U / (R1+R2).

[0045] In this embodiment, U2 = 10 * 270 / 210 = 12.85V, which fully meets the threshold voltage of 2V to 5V for NMOS field-effect transistors.

[0046] Step 2: Determine the parameters of the Zener diode;

[0047] Since the 270VDC voltage fluctuates between 200VDC and 400VDC, and the voltage across resistor R2 fluctuates between 9.5VDC and 19VDC, the Zener diode D1 is set to 15V to prevent voltage fluctuations from affecting the NMOS transistor.

[0048] Step 3, determine the parameters of the NMOS field-effect transistor:

[0049] Since the voltage across R2 meets the requirement of a gate-source voltage >6V at low voltages, an NMOS field-effect transistor is selected as the switching controller device. The threshold voltage power of the NMOS field-effect transistor is 2V to 5V. This is to avoid false turn-on due to voltage fluctuations or noise.

[0050] The control process of the reverse connection protection circuit proposed in this embodiment is as follows:

[0051] When the input voltage is 270V, the gate-source voltage of the NMOS field-effect transistor is 12.85V, which is greater than the threshold voltage of 2V to 5V, and the NMOS field-effect transistor is in a fully open state.

[0052] When the input voltage is 400V, the gate-source voltage of the NMOS field-effect transistor is 19V. At this time, the voltage is regulated to 15V by the Zener diode, which is 2V to 5V higher than the threshold voltage. The NMOS field-effect transistor is in a fully open state.

[0053] When the input voltage is 200V, the gate-source voltage of the NMOS field-effect transistor is 9.5V, which is greater than the threshold voltage of 2V to 5V, and the NMOS field-effect transistor can be turned on normally.

[0054] When the input voltage is reversed, the gate-source voltage of the NMOS field-effect transistor is less than 2V, the NMOS field-effect transistor is in the off state, and the power supply ground line is disconnected, thus protecting the subsequent circuit from damage by the reverse voltage.

Claims

1. An anti-reverse connection circuit for an airborne electronic device based on a 270V power supply, characterized in that, The power supply (1), the power supply ground (2), the power supply output (3), the power supply ground output (4), the resistance R1, the resistance R2, the voltage stabilizing diode D1 and the NMOS field effect tube Q1 are included; wherein, the resistance R1 is 200KΩ, the resistance R2 is 10KΩ, and the voltage stabilizing voltage of the voltage stabilizing diode D1 is 15V; One end of the resistance R1 is connected between the power supply 1 and the power supply ground output (4); the other end of the resistance R1 is in communication with the G pole of the NMOS field effect tube; the negative pole of the voltage stabilizing diode D1 is connected in parallel between the resistance R1 and the NMOS field effect tube Q1; the positive pole of the voltage stabilizing diode D1 is connected between the power supply ground (2) and the power supply output (3); the S pole of the NMOS field effect tube Q1 is in communication with the power supply output (3), and the D pole of the NMOS field effect tube Q1 is in communication with the power supply ground (2); one pin of the resistance R2 is connected in parallel between the S pole of the NMOS field effect tube Q1 and the power supply output (3), and the other pin is connected in parallel between the resistance R1 and the voltage stabilizing diode D1.

2. The reverse connection protection circuit for onboard electronic equipment based on 270V power supply according to claim 1, characterized in that, The resistance value of the resistance R1 is 200KΩ, and the resistance value of the resistance R2 is 10KΩ; The voltage stabilizing voltage of the voltage stabilizing diode D1 is 15V; The threshold voltage power of the NMOS field effect tube Q1 is 2V-5V.

3. A method for designing a reverse connection protection circuit for an airborne electronic device based on a 270V power supply as claimed in claim 1, characterized in that, The specific process is: Step 1, determine the resistance parameter The resistance includes R1 and R2 Since the working voltage is 270VDC, the threshold voltage of the NMOS field effect tube is 2V-5V, in order to ensure that the NMOS field effect tube opens smoothly, the resistance value of R1 is determined as 200KΩ, and the resistance value of R2 is determined as 10KΩ; The voltage U2 of R2 is R1U / (R1+R2); Step 2, determine the parameter of the voltage stabilizing diode; The voltage stabilizing voltage of the voltage stabilizing diode D1 is determined as 15V; Step 3, determine the parameter of the NMOS field effect tube: The threshold voltage power of the NMOS field effect tube is 2V-5V.

4. A control method using the reverse connection prevention circuit according to claim 1, characterized by The specific process is: When the input voltage is 270V, the gate-source voltage of the NMOS field effect tube is 12.85V, which is greater than the threshold voltage 2V-5V, and the NMOS field effect tube is in a fully open state; When the input voltage is 400V, the gate-source voltage of the NMOS field effect tube is 19V, at this time the voltage is stabilized to 15V through the voltage stabilizing tube, which is greater than the threshold voltage 2V-5V, and the NMOS field effect tube is in a fully open state; When the input voltage is 200V, the gate-source voltage of the NMOS field effect tube is 9.5V, which is greater than the threshold voltage 2V-5V, and the NMOS field effect tube can normally open; When the input voltage is reversed, the gate-source voltage of the NMOS field effect tube is <2V, the NMOS field effect tube is in an off state, the power supply ground is disconnected, and the effect of protecting the rear stage circuit from being damaged by the reverse voltage is achieved.

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