System and method for comprehensive protection of TRU failure in an aircraft power distribution system

Abstract

This invention relates to a system and method for comprehensive protection against TRU (Truck Unit) faults in an aviation power distribution system. A battery and a second current sensor are connected in series on a DC emergency busbar. A first current sensor is connected in series at the TRU output terminal, and a voltage sensor is connected in parallel at the TRU output terminal. A speed sensor is installed on the TRU fan. Temperature sensors are installed on the upper and lower arms of the voltage rectifier inside the TRU. A three-phase circuit breaker is connected in series at the TRU input terminal. The signals collected by the two current sensors, voltage sensor, speed sensor, and two temperature sensors are input to a controller. The controller's control signals are output to a first contactor and a second contactor. A battery fuse is connected in series between the battery and the second current sensor. By isolating faults under various conditions such as TRU input overcurrent, output overcurrent, and internal faults, protection is achieved for the TRU itself or the power distribution system, promptly reducing harm to the entire power distribution system and ensuring safe and stable system operation.

Description

Technical Field

[0001] This invention belongs to the field of aviation power distribution technology, and relates to a system and method for comprehensive protection of TRU faults in aviation power distribution systems. Background Technology

[0002] In aviation power distribution systems, TRUs (Transport Units) act as DC power supplies to DC loads. When a TRU fails, it can cause short circuits or damage to electrical equipment. However, most fault detection methods for TRUs only include input overcurrent protection and output voltage protection. As the functions of modern TRUs become increasingly complex and the testability and safety requirements of the system are also increasing, the above two fault detection methods can no longer meet the current system design requirements.

[0003] Faults in aviation power distribution systems include TRU fan failures, over-temperature faults, undervoltage output faults, overcurrent output faults, and open-circuit output faults. It is crucial to determine protection priorities based on the severity and impact of the fault on the system, and then report the fault information or isolate the fault source from the power grid to prevent short circuits or damage to electrical equipment. Summary of the Invention

[0004] Technical problems to be solved

[0005] To avoid the shortcomings of existing technologies, this invention proposes a system and method for comprehensive protection of TRU faults in aviation power distribution systems.

[0006] Technical solution

[0007] A system for comprehensive protection against TRU (Truck Unit) faults in an aviation power distribution system includes a TRU, a DC busbar, a DC emergency busbar, a first contactor 1, and a second contactor 2; characterized in that it also includes a battery, two current sensors, a voltage sensor, a speed sensor, two temperature sensors, a three-phase circuit breaker, and a controller; a battery and the second current sensor are connected in series on the DC emergency busbar, the first current sensor is connected in series at the TRU output terminal, the voltage sensor is connected in parallel at the TRU output terminal, a speed sensor is installed on the TRU fan, and a temperature sensor is installed on the upper and lower bridge arms of the voltage rectifier inside the TRU; a three-phase circuit breaker is connected in series at the TRU input terminal; the acquisition signals of the two current sensors, voltage sensors, speed sensors, and two temperature sensors are input to the controller, and the control signals of the controller are output to the first contactor 1 and the second contactor 2.

[0008] A battery fuse is connected in series between the battery and the second current sensor.

[0009] A method for implementing TRU fault integrated protection in the aviation power distribution system, characterized in that:

[0010] State 1: When the TRU output voltage signal detected by the voltage sensor is lower than the normal power supply characteristic range, an undervoltage fault occurs. Contactor 1 and contactor 2 are disconnected, and the DC emergency busbar is temporarily powered by the battery.

[0011] State 2: When the TRU output current detected by the current sensor exceeds the overcurrent threshold, an overcurrent fault is detected. The controller sends a control signal: first disconnect contactor 2. If the fault disappears, the fault is located on the DC emergency busbar, and the second contactor 2 is locked, and the DC busbar is powered normally. If the fault does not disappear, the first contactor 1 is disconnected. If the fault disappears, the fault is located on the DC busbar, and the first contactor 1 is locked.

[0012] State 3: When the current sensor detects that the output current of the TRU is zero, a short circuit fault has occurred inside the TRU, and the three-phase circuit breaker opens to provide short circuit protection.

[0013] State 4: When either of the two temperature sensors detects that the temperature of the TRU bridge arm exceeds the set value, and the voltage sensor detects that the TRU output voltage is normal, in order to protect the TRU from being burned out, the controller sends a control signal to disconnect the first contactor 1, and the TRU is unloaded.

[0014] State 5: When the temperature difference between the two temperature sensors on the two bridge arms is greater than the set value, it indicates that the TRU output voltage is distorted but still within the normal range. The load is powered normally, and the controller sends a control signal to alarm the TRU fault. It is not necessary to disconnect the load. After the flight mission is completed, the TRU is removed and repaired according to the alarm information.

[0015] Status 6: When the voltage sensor detects that the voltage ripple of the TRU output voltage signal has increased, it will affect the normal operation of the TRU itself and the load equipment. The controller will issue a ripple protection signal.

[0016] State 7: When the speed sensor detects that the TRU fan speed signal is lower than the set value, an alarm is triggered or the load is disconnected. If the load is less than the load threshold, the TRU can continue to work even after the fan fails, without needing to disconnect the first contactor 1. If the load is greater than the load threshold, the controller sends a signal to disconnect the first contactor 1, and the TRU is unloaded to prevent damage to the TRU.

[0017] State 8: When the voltage sensor detects that the output voltage of the TRU is below the undervoltage threshold, the controller sends a control signal to disconnect the first contactor 1 to perform undervoltage protection. If the current sensor detects whether the output current of the TRU is above the overcurrent threshold, the overcurrent fault protection is executed first. If the overcurrent value is below the overcurrent threshold, the undervoltage fault protection is executed first to ensure that the fault condition has the least impact on the normal operation of the system.

[0018] State 9: When the current sensor detects a reverse current in the output current direction of the TRU, although the TRU displays normally, there is an open circuit in the internal output circuit, and the controller sends a control signal to disconnect the first contactor 1.

[0019] The overcurrent threshold is the rated current of the TRU.

[0020] The increased voltage ripple indicates that the voltage ripple exceeds the requirements of normal power supply characteristics.

[0021] The load threshold is 1 / 2 of the rated current.

[0022] The undervoltage threshold is below the normal power supply characteristic range.

[0023] The overcurrent threshold is the rated current.

[0024] Beneficial effects

[0025] This invention proposes a system and method for comprehensive protection against TRU (Telematics Unit) faults in an aviation power distribution system. A battery and a second current sensor are connected in series on a DC emergency busbar. A first current sensor is connected in series at the TRU output terminal, and a voltage sensor is connected in parallel at the TRU output terminal. A speed sensor is installed on the TRU fan. Temperature sensors are installed on the upper and lower arms of the voltage rectifier inside the TRU. A three-phase circuit breaker is connected in series at the TRU input terminal. The signals collected by the two current sensors, voltage sensor, speed sensor, and two temperature sensors are input to a controller. The controller's control signals are output to a first contactor and a second contactor. A battery fuse is connected in series between the battery and the second current sensor.

[0026] TRU fault detection is a study and summary of typical TRU faults and corresponding fault detection methods in aviation power distribution systems. By isolating faults under various conditions such as TRU input overcurrent, output overcurrent, and internal faults, it can protect the TRU itself or the power distribution system, reduce the harm to the entire power distribution system in a timely manner, and ensure the safe and stable operation of the system. Attached Figure Description

[0027] Figure 1 Schematic diagram of the DC power supply and protection system of this invention

[0028] Figure 2TRU principle block diagram Detailed Implementation

[0029] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

[0030] This invention is based on a DC power supply system configuration for a certain civil aircraft, part of which is as follows: Figure 1 As shown, the TRU is a transformer rectifier that converts the input 3-phase AC power into 28V DC, outputting it to the DC busbar and the DC emergency busbar to power the DC loads connected to the DC busbar. To ensure uninterrupted power supply to the DC emergency busbar, a battery is directly connected to it. Under normal circumstances, when the 28V DC output from the TRU meets the requirements, the controller closes contactors 1 and 2 to supply power to the DC loads on the DC busbar and the DC emergency busbar. In the event of a TRU failure, the system enters emergency power supply mode, disconnecting contactors 1 and 2, and the battery briefly supplies power to the two DC busbars.

[0031] The protection system includes a TRU, a DC busbar, a DC emergency busbar, a first contactor 1, and a second contactor 2; it is characterized by further including a battery, two current sensors, a voltage sensor, a speed sensor, two temperature sensors, a three-phase circuit breaker, and a controller; a battery and a second current sensor are connected in series on the DC emergency busbar, the first current sensor is connected in series at the TRU output terminal, the voltage sensor is connected in parallel at the TRU output terminal, a speed sensor is provided on the TRU fan, a temperature sensor is provided on the upper and lower bridge arms of the voltage rectifier inside the TRU, and a three-phase circuit breaker is connected in series at the TRU input terminal; the acquisition signals of the two current sensors, voltage sensors, speed sensors, and two temperature sensors are input to the controller, and the control signals of the controller are output to the first contactor 1 and the second contactor 2.

[0032] A battery fuse is connected in series between the battery and the second current sensor.

[0033] The TRU is both a DC power supply and an AC load. Therefore, if a short circuit fault occurs inside the TRU, it will affect the power supply to other AC loads on the machine. Thus, a three-phase circuit breaker can be added to the TRU input terminal for short circuit protection.

[0034] Similarly, when a load on the DC busbar and the DC emergency busbar is short-circuited, the controller collects the TRU output current through the TRU current sensor. If the current exceeds the overcurrent threshold, it executes the overcurrent isolation algorithm, starting the isolation from the end furthest from the TRU. First, contactor 2 is disconnected. If the fault disappears, the fault is located on the DC emergency busbar, contactor 2 is locked, and the DC busbar supplies power normally. If the fault does not disappear, contactor 1 is disconnected. If the fault disappears, the fault is locked on the DC busbar, and contactor 1 is locked.

[0035] Besides input / output overcurrent faults, the most common faults in TRUs include internal diode faults and fan faults. A TRU block diagram is shown below. Figure 2 As shown.

[0036] To ensure low output voltage ripple in the TRU, two sets of rectifiers are used internally. To separately monitor the diode temperature of these two rectifier sets, two thermistors are installed inside the TRU, mounted on the heat sink of the rectifier on the secondary delta winding of the transformer. Foil resistors are commonly used. These thermistors transmit the temperature signals of the upper and lower rectifier bridge arms inside the TRU to the controller for real-time monitoring of the TRU's internal temperature. When the TRU is operating normally, the temperatures of the two thermistors remain within a certain range. A short circuit in either the upper or lower rectifier bridge arm causes a rapid temperature rise. If the temperature exceeds the set value, contactor 1 needs to be disconnected to unload the TRU and prevent it from burning out.

[0037] In addition, due to reasons such as open circuit of the internal diode of TRU, the temperature difference between the two channels may exceed the normal range. In this case, the output voltage of TRU will be distorted to a certain extent, but it is still within the normal range and can supply power to the load normally. Therefore, TRU fault alarm can be issued without disconnecting the load. After the flight mission is completed, TRU can be disassembled and repaired according to the alarm information.

[0038] When the diode is short-circuited, the capacitor is damaged, or the transformer loses a phase, the output voltage ripple of the TRU increases, which will affect the normal operation of the TRU itself and the load equipment, and ripple protection is required.

[0039] When the TRU fan fails, prolonged operation leading to heat accumulation can cause the TRU to burn out. Therefore, by detecting the TRU fan speed signal, an alarm can be triggered or the load can be disconnected when the fan speed drops below a certain value. The specific alarm or load disconnection depends on the actual load of the TRU. If the load is small, the TRU can continue to operate even after a fan failure without needing to disconnect contactor 1. If the load is large, the controller must disconnect contactor 1 to unload the TRU and prevent damage.

[0040] The output voltage of the TRU also needs to be monitored because when the transformer inside the TRU fails, the TRU will experience an output undervoltage fault, affecting the normal operation of the load. The controller needs to disconnect contactor 1 to activate undervoltage protection. Generally, undervoltage and overcurrent faults will occur simultaneously, and the protection priority can be determined based on the specific overcurrent value. If the overcurrent value is large, to prevent the large current from burning out the line and load in a short time, the overcurrent fault protection will be activated first; if the overcurrent value is small, the undervoltage fault protection will be activated first to ensure that the fault has minimal impact on the normal operation of the system.

[0041] Furthermore, when the TRU is normal but its internal output circuit is open, there is a situation where the TRU fault cannot be detected. Normally, the contactor 1 coil is directly powered by the TRU, and the controller outputs a low / open control signal to the negative terminal of the contactor 1 coil. When the TRU output suddenly opens, the battery will supply power to the TRU output through contactors 2 and 1. The controller's control logic for contactor 1 only checks the TRU output voltage; if the voltage is normal, the controller considers the TRU normal. In reality, the battery is supplying power to the DC busbar and the DC emergency busbar. Once the battery is depleted, the DC loads on both busbars will be disconnected, which is a very serious accident during flight. Therefore, to detect this fault promptly, the TRU output current can be increased in the contactor 1 control logic. When the TRU output current reverses, contactor 1 should be disconnected. Alternatively, a comprehensive judgment can be made based on the battery current value. If contactor 1 is closed and the battery is discharging, then a TRU fault is determined, and contactor 1 should be disconnected.

[0042] This embodiment utilizes the detection system and protection method for TRU faults in the primary power distribution system of a civil aircraft project. Three-phase circuit breakers are used as input overcurrent protection devices at the input terminals of the three TRUs on the aircraft. Overcurrents caused by loads or busbars are isolated from the nearest fault by the TRU overcurrent protection algorithm of the busbar power controller in the system. Over-temperature protection is provided for over-temperature caused by diode or fan failures within the TRU. Temperature difference alarms are provided for temperature imbalances between the upper and lower bridge arms caused by diode open-circuit faults, without affecting normal system operation. Undervoltage and ripple protection are provided for the TRU output voltage to ensure the safe operation of the electrical load. Furthermore, the priority of overcurrent fault protection and undervoltage protection is determined based on the degree of harm caused to the system by the TRU overcurrent, ensuring that the impact of fault conditions on normal system operation is minimized and improving system reliability.

Claims

1. A method for implementing TRU fault integrated protection in an aviation power distribution system, characterized in that: The system for comprehensive protection of TRU faults in the aviation power distribution system includes a TRU, a DC busbar, a DC emergency busbar, a first contactor (1), and a second contactor (2); it is characterized by further including a battery, two current sensors, a voltage sensor, a speed sensor, two temperature sensors, a three-phase circuit breaker, and a controller; a battery and a second current sensor are connected in series on the DC emergency busbar, the first current sensor is connected in series at the TRU output terminal, the voltage sensor is connected in parallel at the TRU output terminal, a speed sensor is provided on the TRU fan, a temperature sensor is provided on the upper and lower bridge arms of the voltage rectifier in the TRU, and a three-phase circuit breaker is connected in series at the TRU input terminal; the acquisition signals of the two current sensors, voltage sensors, speed sensors, and two temperature sensors are input to the controller, and the control signal of the controller is output to the first contactor (1) and the second contactor (2), the method being: State 1: When the output voltage signal of the TRU detected by the voltage sensor is lower than the normal power supply characteristic range, the output voltage is undervoltage fault. The first contactor (1) and the second contactor (2) are disconnected, and the DC emergency busbar is powered by the battery for a short time. State 2: When the TRU output current detected by the current sensor exceeds the overcurrent threshold, an overcurrent fault is output. The controller sends a control signal: first disconnect the second contactor (2). If the fault disappears, the fault is located on the DC emergency busbar. The second contactor (2) is locked in the open state and the DC busbar is powered normally. If the fault does not disappear, the first contactor (1) is disconnected. If the fault disappears, the fault is locked on the DC busbar and the first contactor (1) is locked in the open state. State 3: When the current sensor detects that the output current of the TRU is zero, a short circuit fault has occurred inside the TRU, and the three-phase circuit breaker opens to provide short circuit protection. State 4: When either of the two temperature sensors detects that the temperature of the TRU bridge arm exceeds the set temperature value, and the voltage sensor detects that the TRU output voltage is normal, in order to protect the TRU from being burned out, the controller sends a control signal to disconnect the first contactor (1) and the TRU is unloaded. State 5: When the temperature difference detected by the two temperature sensors of the two bridge arms is greater than the set temperature difference value on the TRU, it indicates that the TRU output voltage is distorted, but still within the normal range. The load is powered normally, and the controller sends a control signal to alarm the TRU fault. It is not necessary to disconnect the load. After the flight mission is completed, the TRU is removed and repaired according to the alarm information. Status 6: When the voltage sensor detects that the voltage ripple of the TRU output voltage signal has increased, it will affect the normal operation of the TRU itself and the load equipment. The controller will issue a ripple protection signal. State 7: When the speed sensor detects that the TRU fan speed signal is lower than the fan speed signal set value, an alarm is triggered or the load is disconnected. If the load is less than the load threshold, the TRU can still work for a long time after the fan fails, and there is no need to disconnect the first contactor (1). If the load is greater than the load threshold, the controller sends a signal to disconnect the first contactor (1), and the TRU is unloaded to avoid damage to the TRU. State 8: When the voltage sensor detects that the output voltage of the TRU is less than the undervoltage threshold, the controller sends a control signal to disconnect the first contactor (1) to perform undervoltage protection; if the current sensor detects that the output current of the TRU has an overcurrent fault, if the overcurrent value is greater than the overcurrent threshold, the overcurrent fault protection is executed first; if the overcurrent value is less than the overcurrent threshold, the undervoltage protection is executed first to ensure that the fault condition has the least impact on the normal operation of the system. State 9: When the current sensor detects a reverse current in the output current direction of the TRU, although the TRU displays normally, an open circuit appears in the internal output circuit, and the controller sends a control signal to disconnect the first contactor (1).

2. The method of claim 1, wherein: The overcurrent threshold is the rated current of the TRU.

3. The method of claim 1, wherein: The load threshold is 1 / 2 of the rated current.

4. The method of claim 1, wherein: A battery fuse is connected in series between the battery and the second current sensor.

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