A contactor coil positive terminal control circuit for an aircraft power system

Abstract

The application provides a contactor coil positive terminal control circuit for an aviation power system, comprising: a driving module for driving a contactor coil; a control circuit connected to the driving module for controlling the working of the driving module; a protection circuit connected to the control circuit for short circuit protection of the contactor coil; when the contactor coil is not short-circuited, the control circuit receives a high level signal of a control chip and is turned on, the protection circuit samples a current of the contactor coil, and when the current of the contactor coil does not produce a voltage drop and the voltage of the driving module is greater than a threshold value, the contactor is attracted; when the contactor coil is short-circuited, the control circuit receives a high level signal of a control chip and is turned on, the protection circuit uses the current of the contactor coil in the short-circuit state to produce a large voltage drop of the protection circuit, and then the voltage of the driving module is less than the threshold value and cannot be turned on, the contactor cannot be attracted and is self-locked for protection.

Description

Technical Field

[0001] This application belongs to the field of aviation power systems, and specifically relates to a contactor coil positive terminal control circuit for aviation power systems. Background Technology

[0002] In aviation power supply systems, contactors serve as connecting devices for transmitting electrical energy from generators to busbars and from busbars to high-power electrical equipment. They are used to distribute electrical energy, convert power supply, control load power supply, and protect the electrical system, ensuring the reliable operation of the entire aircraft's power distribution system. As their service life increases, electrical components gradually age. If a contactor fails due to aging, it will affect the normal operation of the power distribution system, potentially leading to a power outage on the aircraft's electrical grid and even posing a threat to flight safety.

[0003] In actual operation of power supply systems, common contactor faults include: the contactor failing to operate or operating abnormally after the coil is energized; the contactor failing to release or experiencing excessively long release times after the coil is de-energized; or short circuits between coil turns or between the drive circuit and ground, leading to coil damage or burnout, and potentially even fire, threatening the safety of other equipment on board. If a contactor coil fault is not isolated promptly, the accident can escalate rapidly, resulting in very serious consequences.

[0004] Therefore, a control circuit is needed to quickly isolate the fault after a short circuit occurs in the contactor coil, preventing the fault from escalating. Summary of the Invention

[0005] The purpose of this application is to provide a contactor coil positive terminal control circuit for an aviation power system to solve or mitigate at least one of the problems in the prior art.

[0006] The technical solution of this application is: a contactor coil positive terminal control circuit for an aviation power system, comprising:

[0007] A drive module for driving contactor coils;

[0008] A control circuit that connects to the drive module and is used to control the operation of the drive module;

[0009] A protection circuit connected to the control circuit for short-circuit protection of the contactor coil;

[0010] When the contactor coil is not short-circuited, the control circuit receives a high-level signal from the control chip and turns on. The protection circuit samples the contactor coil current. When the contactor coil current does not generate a voltage drop that causes the voltage of the drive module to be greater than the threshold and thus turns on, the contactor is engaged.

[0011] When a short circuit occurs in the contactor coil, the control circuit receives a high-level signal from the control chip and turns on. The protection circuit causes the contactor coil current to drop significantly during a short circuit, resulting in a large voltage drop in the protection circuit. This causes the voltage of the drive module to fall below the threshold and prevent it from turning on, thus preventing the contactor from engaging and triggering self-locking protection.

[0012] Furthermore, the driving module is a PMOS transistor, the drain output of the PMOS transistor drives the contactor coil, and the gate and source of the PMOS transistor are respectively connected to the two ends of the Zener diode of the control circuit.

[0013] Furthermore, the control circuit includes resistors R5, R6, and R7, transistor Q2B, and Zener diode VD1. The emitter of transistor Q2B is grounded, and its base is connected to the control chip through resistor R7 and is controlled by the control chip. The collector of transistor Q2B is connected to the gate of the PMOS transistor through resistor R5, and the node between transistor Q2B and resistor R5 is connected to the input power supply through resistor R6.

[0014] Furthermore, the protection circuit includes resistors R1, R2, R3, and R4, capacitor C1, transistor Q3, and transistor Q2A. Resistors R1 and R2 are connected in parallel to form a contactor coil current sampling resistor. Capacitor C1 is connected in parallel with the sampling resistor. The emitter and base of transistor Q3 are respectively connected to the two ends of the parallel sampling resistor and capacitor C1. The collector of transistor Q3 is connected to the gate G of PMOS transistor Q1 through resistor R4. The collector and base of transistor Q2A are respectively connected to the base and collector of transistor Q3. The emitter of transistor Q2A is connected to the gate G of PMOS transistor Q1.

[0015] Furthermore, the driver chip includes any one of a CPU, DSP, and FPGA.

[0016] Furthermore, when the contactor coil or drive circuit does not experience a short circuit fault but the contactor needs to be turned on, the control chip outputs a high level to control transistor Q2B to conduct. The collector of transistor Q2B is grounded, the voltage drop across the parallel connection of resistors R1 and R2 is small, and the base voltage of transistor Q3 is the same as the voltage drop across the parallel resistor. Transistor Q3 is turned off, and the voltage across the gate and source of the PMOS transistor is the breakdown voltage of Zener diode VD1. At this time, the voltages at the emitter and base of transistor Q2A are the difference between the input power supply voltage and the breakdown voltage of the Zener diode. Therefore, transistor Q2A is turned off, and the voltage across the gate and source of PMOS transistor Q1 is greater than the conduction threshold voltage of PMOS transistor Q1. PMOS transistor conducts, and the rated voltage is sent to the contactor coil, causing the contactor to engage.

[0017] When it is necessary to control the contactor to disconnect, the control chip outputs a low level, which turns off the control transistor Q2B. Transistors Q3, Q2A, and the PMOS transistor are also turned off. The positive terminal drive circuit of the contactor coil has no output, and the contactor is released.

[0018] Furthermore, when a short circuit fault occurs in the contactor coil or drive circuit, the current flowing through the contactor coil is large, and the voltage drop across the parallel resistors R1 and R2 is large. The charging circuit composed of resistor R3 and capacitor C1 charges capacitor C1, and the voltage across capacitor C1 increases. When the voltage reaches the rated value, transistor Q3 turns on. The collector voltage of transistor Q3 is the rated voltage minus the saturation conduction voltage drop of transistor Q3. Consequently, transistor Q2A turns on. The emitter voltage of transistor Q2A is the voltage of transistor Q3 minus the saturation conduction voltage drop of transistor Q3. At this time, the voltage drop across the gate and source of the PMOS transistor is less than the PMOS transistor's conduction threshold voltage, so the PMOS transistor turns off, and the contactor releases, thus providing short circuit protection.

[0019] When the contactor is disconnected, there is no voltage drop across resistors R1 and R2, and the voltage across the parallel resistor is 28V. Since there is no discharge circuit, capacitor C1 maintains its voltage at the rated value. Therefore, transistors Q3 and Q2A remain in the conducting state, and the PMOS transistor remains in the off state, thus playing a self-locking role in short-circuit protection.

[0020] The contactor coil positive terminal control circuit proposed in this application can quickly perform short-circuit protection and lock the contactor to the open state when the contactor coil or drive control line is short-circuited, thereby achieving fault isolation. It has high reliability and safety, can effectively improve the fault diagnosis and health management efficiency of the power supply system, and has strong engineering application value. Attached Figure Description

[0021] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0022] Figure 1 This is a schematic diagram of the contactor coil positive terminal control circuit of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0024] To reduce the occurrence of short-circuit faults in contactor coils during the operation of aviation power supply systems, thereby preventing airborne equipment safety accidents and improving the service life and reliability of contactors, this application proposes a contactor coil positive terminal control circuit. When a short circuit occurs in the contactor coil or drive line, it can quickly perform hardware short-circuit protection, block the control command output of the contactor coil positive terminal, cause the contactor main contacts to release, and lock the contactor to the open state.

[0025] like Figure 1 As shown, the contactor coil positive terminal drive circuit provided in this application includes:

[0026] A drive module for driving contactor coils;

[0027] A control circuit that connects to the drive module and is used to control the operation of the drive module;

[0028] A protection circuit connected to the control circuit for short-circuit protection of the contactor coil;

[0029] When the contactor coil is not short-circuited, the control circuit receives a high-level signal from the control chip and is turned on. The protection circuit samples the contactor coil current and makes the voltage of the drive module greater than the threshold to turn on, and the contactor is engaged.

[0030] When a short circuit occurs in the contactor coil, the control circuit receives a high-level signal from the control chip and turns on. The protection circuit samples the contactor coil current to make the voltage of the drive module less than a threshold and turns on, preventing the contactor from engaging and providing self-locking protection.

[0031] In this application, the driving module is a PMOS transistor Q1. The drain D of the PMOS transistor Q1 drives the contactor coil. The gate G and source S of the PMOS transistor Q1 are respectively connected to the two ends of the Zener diode VD1 of the control circuit.

[0032] In some embodiments of this application, the driver chip may be a CPU, DSP or FPGA, etc. The driver chip in the figures of this application is a CPU, and the following description will use the CPU as the control chip.

[0033] The control circuit includes resistors R5 to R7, transistor Q2B, and Zener diode VD1. The emitter of transistor Q2B is grounded, and its base is connected to the CPU through resistor R7 and is controlled by the CPU. The collector of transistor Q2B is connected to the gate G of PMOS transistor Q1 through resistor R5. The node E between transistor Q2B and resistor R5 is connected to the 28V input power supply through resistor R6.

[0034] The contactor coil short-circuit protection circuit includes resistors R1 to R4, capacitor C1, transistor Q3, and transistor Q2A. Resistors R1 and R2 are connected in parallel to form the contactor coil current sampling resistor. Capacitor C1 is connected in parallel with the sampling resistor. The emitter and base of transistor Q3 are connected to the parallel sampling resistor and the two ends of capacitor C1, respectively. The collector of transistor Q3 is connected to the gate G of PMOS transistor Q1 through resistor R4. The collector and base of transistor Q2A are connected to the base and collector of transistor Q3, respectively. The emitter of transistor Q2A is connected to the gate G of PMOS transistor Q1.

[0035] Aviation electrical systems typically use 28V as the external power source for aircraft. In this embodiment of the application, the operation of the contactor coil positive terminal control circuit is illustrated using a 28V power supply as follows:

[0036] 1) No short circuit fault occurred in the contactor coil or drive circuit:

[0037] When the contactor needs to be turned on, the CPU outputs a high level to turn on the transistor Q2B, and the collector of the transistor Q2B, i.e., point E, is grounded.

[0038] Under normal circumstances, the current flowing through the contactor coil is relatively small (starting current is 5A, holding current is 0.5A). The voltage drop across the parallel resistors R1 and R2 is small. The voltage at parallel node A is 27.75V at the moment of contactor start-up and 27.975V at the holding voltage. The voltage at point C of the base of transistor Q3 is the same as the voltage at point A, so transistor Q3 is off. The voltage across the gate G and source S of PMOS transistor Q1 is the breakdown voltage of Zener diode VD1, which is 16V. At this time, the voltage between the emitter node B and the base node D of transistor Q2A is approximately 12V, so transistor Q2A is off. The voltage across the gate G and source S of PMOS transistor Q1 is greater than the PMOS transistor Q1 conduction threshold voltage of 3V, so PMOS transistor Q1 conducts and outputs approximately 28V to the contactor coil, causing the contactor to engage.

[0039] When it is necessary to control the contactor to disconnect, the CPU outputs a low level, which turns off transistor Q2B. Transistors Q3, Q2A, and Q1 are also turned off, and the positive terminal drive circuit of the contactor coil has no output, thus releasing the contactor.

[0040] 2) A short circuit fault occurs in the contactor coil or drive circuit:

[0041] If a short circuit occurs in the contactor coil or drive circuit during normal contactor operation, the current flowing through the contactor coil will be relatively large, say 15A. At this time, the voltage drop across the parallel resistors R1 and R2 will be large, at 0.5V. The voltage at point A will be approximately 27.5V. The charging circuit consisting of resistor R3 and capacitor C1 charges capacitor C1, increasing the voltage across it. When the voltage reaches 0.7V, the voltage at point C will be 27.3V, and transistor Q3 will conduct. The voltage at point D will be 27.9V, and transistor Q2A will conduct. The voltage at point B will be 27.2V. At this point, the voltage drop across the gate and source terminals of PMOS transistor Q1 will be 0.3V, which is less than the PMOS transistor Q1's conduction threshold voltage. Therefore, PMOS transistor Q1 will disconnect, and the contactor will release, thus providing short-circuit protection.

[0042] When the contactor is disconnected, there is no voltage drop across resistors R1 and R2, and the voltage at point A is 28V. Since there is no discharge circuit, capacitor C1 maintains a voltage of 0.7V across it. Therefore, transistors Q3 and Q2A remain in the conducting state, and PMOS transistor Q1 remains in the off state, thus playing a self-locking role in short-circuit protection.

[0043] The short-circuit protection mechanism of the contactor coil positive terminal control circuit provided in this application is that the coil current increases, which leads to an increase in the voltage drop across resistors R1 and R2, triggering the charging circuit of resistor R3 and capacitor C1 to work. The capacitor C1 is charged to the conduction voltage of transistor Q3 (0.7V), causing Q3 and Q2A to remain in the conducting state and PMOS transistor Q1 to remain in the off state.

[0044] Therefore, the short-circuit protection point for the contactor coil current is calculated as follows:

[0045]

[0046] Among them, u be The forward voltage of transistor Q3 is 0.7V. To maintain the minimum voltage drop required for transistor Q3 to conduct, which is approximately 0.1V, the short-circuit protection current can be calculated as follows:

[0047]

[0048] The short-circuit protection time is the time it takes for capacitor C1 to charge to 0.7V, which is:

[0049] t=5τ=5R3C1=5×0.022×10=1.1ms

[0050] Therefore, when the current flowing through the contactor coil is greater than 12A, the circuit can quickly provide protection within 1.1ms, playing a short-circuit protection self-locking role.

[0051] The contactor coil positive terminal control circuit proposed in this application can quickly perform short-circuit protection and lock the contactor to the open state when the contactor coil or drive control line is short-circuited, thereby achieving fault isolation. It has high reliability and safety, can effectively improve the fault diagnosis and health management efficiency of the power supply system, and has strong engineering application value.

[0052] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A contactor coil positive terminal control circuit for an aviation power system, characterized in that, include: A driving module for driving a contactor coil, wherein the driving module is a PMOS transistor, the drain output of the PMOS transistor drives the contactor coil, and the gate and source of the PMOS transistor are respectively connected to the two ends of the Zener diode of the control circuit. A control circuit connected to the drive module for controlling the operation of the drive module, the control circuit includes resistors R5, R6, and R7, transistor Q2B and Zener diode VD1, the emitter of transistor Q2B is grounded, the base is connected to the control chip through resistor R7 and is controlled by the control chip, the collector of transistor Q2B is connected to the gate of PMOS transistor through resistor R5, and the node between transistor Q2B and resistor R5 is connected to the input power supply through resistor R6; A protection circuit for short-circuit protection of the contactor coil, connected to the control circuit, includes resistors R1, R2, R3, and R4, capacitor C1, transistor Q3, and transistor Q2A. Resistors R1 and R2 are connected in parallel to form a contactor coil current sampling resistor. Capacitor C1 is connected in parallel with the sampling resistor. The emitter and base of transistor Q3 are respectively connected to the two ends of the parallel sampling resistor and capacitor C1. The collector of transistor Q3 is connected to the gate G of PMOS transistor Q1 through resistor R4. The collector and base of transistor Q2A are respectively connected to the base and collector of transistor Q3. The emitter of transistor Q2A is connected to the gate G of PMOS transistor Q1. One end of the parallel sampling resistor and capacitor C1 is connected to the input power supply, and the other end of the parallel sampling resistor is connected to the other end of capacitor C1 through resistor R3. When the contactor coil is not short-circuited, the control circuit receives a high-level signal from the control chip and is turned on. The protection circuit samples the contactor coil current. When the contactor coil current does not generate a voltage drop that causes the voltage of the drive module to be greater than the threshold and thus be turned on, the contactor is engaged. When a short circuit occurs in the contactor coil, the control circuit receives a high-level signal from the control chip and turns on. The protection circuit samples the contactor coil current to make the voltage of the drive module less than the threshold so that it cannot turn on, and the contactor cannot be energized and self-locks for protection.

2. The contactor coil positive terminal control circuit for an aviation power system as described in claim 1, characterized in that, The control chip includes any one of CPU, DSP and FPGA.

3. The contactor coil positive terminal control circuit for an aviation power system as described in claim 2, characterized in that, When the contactor coil or drive circuit does not have a short circuit fault and the contactor needs to be turned on, the control chip outputs a high level to control transistor Q2B to conduct. The emitter of transistor Q2B is grounded, the voltage drop across the parallel connection of resistors R1 and R2 is small, and the base voltage of transistor Q3 is the same as the voltage drop across the parallel resistor. Transistor Q3 is turned off, and the voltage across the gate and source of the PMOS transistor is the breakdown voltage of Zener diode VD1. At this time, the voltages at the emitter and base of transistor Q2A are the difference between the input power supply voltage and the breakdown voltage of the Zener diode. Therefore, transistor Q2A is turned off, and the voltage across the gate and source of PMOS transistor Q1 is greater than the conduction threshold voltage of PMOS transistor Q1. PMOS transistor conducts, and the rated voltage is sent to the contactor coil, and the contactor is energized. When it is necessary to control the contactor to disconnect, the control chip outputs a low level, which turns off the control transistor Q2B. Transistors Q3, Q2A, and the PMOS transistor are also turned off. The positive terminal drive circuit of the contactor coil has no output, and the contactor is released.

4. The contactor coil positive terminal control circuit for an aviation power system as described in claim 2, characterized in that, When a short circuit fault occurs in the contactor coil or drive circuit, the current flowing through the contactor coil is large, and the voltage drop across the parallel resistors R1 and R2 is large. The charging circuit composed of resistor R3 and capacitor C1 charges capacitor C1, increasing the voltage across capacitor C1. When the voltage reaches the conduction voltage of transistor Q3, transistor Q3 turns on. The collector voltage of transistor Q3 is the input power supply voltage minus the saturation conduction voltage drop of transistor Q3. Consequently, transistor Q2A turns on. The emitter voltage of transistor Q2A is the base voltage of transistor Q3 minus the saturation conduction voltage drop of transistor Q2A. At this time, the voltage drop across the gate and source of the PMOS transistor is less than the conduction threshold voltage of the PMOS transistor, so the PMOS transistor turns off, and the contactor releases, thus providing short circuit protection. When the contactor is disconnected, there is no voltage drop across resistors R1 and R2, and the voltage across the parallel resistor is 28V. Since there is no discharge circuit, capacitor C1 maintains its voltage at the rated value. Therefore, transistors Q3 and Q2A remain in the conducting state, and the PMOS transistor remains in the off state, thus playing a self-locking role in short-circuit protection.

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