A time-division multiplexing system and method for an aircraft variable frequency rectifier

Abstract

The application relates to a variable-voltage rectifier multiplexing scheme for RAT system ACMP soft starting and APU alternating current starting, which comprises a variable-voltage rectifier configured to convert input alternating current into high-voltage direct current for output, and a multiplexer configured to switch high-voltage direct current from the variable-voltage rectifier to a corresponding branch of an APU starting branch and an ACMP soft starting branch according to whether a TSC Drive signal is valid; wherein: whether the TSC Drive signal is valid is set according to an instruction from a TRU starting contactor; if the TSC Drive signal is valid, the multiplexer switches the high-voltage direct current from the variable-voltage rectifier to the APU starting branch; and if the TSC Drive signal is invalid, the multiplexer switches the high-voltage direct current from the variable-voltage rectifier to the ACMP soft starting branch.

Description

TECHNICAL FIELD

[0001] The present application relates to the power supply system of civil aircraft, in particular, to the time-sharing multiplexing technology of the transformer rectifier in the soft start ACMP of the RAT system and the APU AC starting. BACKGROUND

[0002] APU (Auxiliary Power Unit), refers to the small auxiliary power unit that can independently output compressed air or power on the aircraft in addition to the main power unit (engine). It is generally a small gas turbine engine. It includes a power output shaft, a compressed air extraction device and an automatic control device, etc. Before take-off, it provides compressed air for the aircraft, which can be used for air conditioning system of the aircraft or for the main engine starter to provide air source start, and can also output power for the aircraft power system before the main engine starts, reducing the dependence of the aircraft on the airport equipment; in flight, when the main engine or its power generation device fails, it can provide emergency energy to the aircraft, improve flight safety; when landing, it can also provide energy for the aircraft. Auxiliary power units are installed on large and medium-sized aircraft and large helicopters.

[0003] Ram Air Turbine (RAT) is an emergency turbine generator set used by the aircraft when the engine is stopped and the auxiliary power system (APU) is completely disabled. Because of its English abbreviation, it is also called "rat". It is driven by the ram pressure generated by the aircraft in flight, providing limited power (mainly for the cockpit) for the cockpit and flight control system (fly-by-wire control system) and hydraulic pressure for the control surfaces of the aircraft.

[0004] In the current typical civil aircraft, the APU and the emergency turbine generator system (hereinafter referred to as "RAT" system) both play an important role in aircraft safety, and the existence of the two greatly improves the safety margin of the aircraft and further reduces the failure rate.

[0005] But for the APU, the starting in cold working conditions requires high mechanical torque, and the power supply requirements are more stringent. A good solution is to use a transformer rectifier to output high-voltage DC power after AC power, and then convert it to AC power through the SGCU (starter generator controller) to start the APU. This method can further reduce the risk of APU starting.

[0006] At the same time, for the RAT system, it needs to restart the ACMP (abbreviation of "Alternating Current Motor Pump") after accessing the power grid, which will also cause a very high instantaneous impact current, causing damage to the generator. Moreover, due to the great impedance of the ACMP at low temperature, there is a risk that the ACMP cannot be started at low temperature, so it is also necessary to use the method of combining the voltage rectifier and the motor controller (MC) to ensure the successful start of the ACMP. The voltage rectifier converts alternating current into high-voltage direct current, and the MC converts high-voltage direct current into alternating current output. Through this conversion mode, the start-up time of the ACMP is extended, thereby reducing the load torque in the load start-up process. Therefore, this mode is also called ACMP soft start.

[0007] In other words, whether it is the start of the APU system or the soft start of the ACMP of the RAT system, both starting modes have common needs for the voltage rectifier. However, at present, both the APU system and the RAT system are equipped with a special voltage rectifier, resulting in an increase in the overall weight and size of the power supply system.

[0008] Therefore, it is desirable to provide a simplified solution to provide multiplexing services for the voltage rectifier for APU start and soft start of the ACMP of the RAT system, so as to reduce the overall weight and size of the power supply system. SUMMARY

[0009] The purpose of the present application is to multiplex the devices for soft starting the ACMP of the RAT system and the devices in the APU alternating current start, thereby reducing the weight of the important devices of the aircraft, while meeting the performance requirements of the original design.

[0010] According to a first aspect of the present application, a voltage rectifier multiplexing system for soft starting the ACMP of the RAT system and the APU alternating current start is provided, comprising:

[0011] a voltage rectifier (TRU) configured to convert input alternating current into high-voltage direct current for output;

[0012] a multiplexer (MUX) configured to switch the high-voltage direct current from the voltage rectifier to a corresponding branch of the APU start branch and the ACMP soft start branch according to whether the TSC Drive signal is valid;

[0013] wherein:

[0014] whether the TSC Drive signal is valid is set according to the signal from the TRU start contactor;

[0015] if the TSC Drive signal is valid, then the multiplexer switches the high voltage DC power from the transformer rectifier to the APU start branch;

[0016] if the TSC Drive signal is invalid, then the multiplexer switches the high voltage DC power from the transformer rectifier to the ACMP soft start branch.

[0017] According to a second aspect of the present application, there is provided a transformer rectifier multiplexing method for ACMP soft start and APU AC start of a RAT system, comprising:

[0018] determining whether a TSC Drive signal is valid;

[0019] if the TSC Drive signal is valid, then switching the high voltage DC power from the transformer rectifier to the APU start branch;

[0020] if the TSC Drive signal is invalid, then switching the high voltage DC power from the transformer rectifier to the ACMP soft start branch.

[0021] wherein the method further comprises setting whether the TSC Drive signal is valid based on a signal from a TRU start contactor.

[0022] This Summary is provided to introduce some concepts in a simplified form, further descriptions of which follow in the detailed description below. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to describe the manner in which the above-recited and other features and advantages of the application can be obtained, a more particular description will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the application and are not therefore to be considered to be limiting of its scope, the application will be described and explained with additional specificity and detail by the use of the accompanying drawings in which:

[0024] Figure 1 is a simulated current variation curve schematic diagram of ACMP normal start.

[0025] Figure 2 is a simulated current variation curve schematic diagram of ACMP soft start.

[0026] Figure 3 shows a schematic environment block diagram of a transformer rectifier (TRU) multiplexing system for ACMP soft start and APU AC start of a RAT system, according to an embodiment of the present application.

[0027] Figure 4 A schematic flow chart of a method for multiplexing of a TRU in RAT system ACMP soft start and APU AC start is shown according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] As described in the background section, up to now, although researchers have been engaged in the related research of RAT system ACMP start and APU AC start, no one has conducted in-depth research on the multiplexing of the two technical devices, resulting in a relatively large weight of the two independent system devices, which cannot fully utilize the resources of the aircraft.

[0029] Moreover, as mentioned above, whether it is the start of the APU system or the soft start of the ACMP by the RAT system, both starting methods have common requirements for the TRU. Therefore, the present application aims to provide a joint multiplexing scheme for sharing the TRU and the motor controller during the RAT system ACMP start and the APU AC start, so as to meet the requirements of reducing the APU start related risks and the successful start of the ACMP under low temperature conditions at the same time.

[0030] For the convenience of understanding and description, the present application takes a certain large passenger aircraft as an example for specific description. However, it should be understood that the example is only for the purpose of illustration, and is not intended to limit the scheme of the present application to this aircraft model. In fact, any aircraft model that adopts APU and RAT system can apply the scheme of the present application and belongs to the scope to be protected by the present application.

[0031] According to the load analysis report of the large passenger aircraft, the maximum demand of the current aircraft under emergency working conditions is not more than 1.5 times overload (45 kVA) for 5s load overload, and the current RAT system overload design needs to meet 1.5 times overload and 2 times overload design.

[0032] The 2 times overload capability design of the RAT system is basically to solve the problem of instantaneous high power demand during ACMP start design. In most cases other than this, 1.5 times overload capability is actually more than enough for the aircraft load. But because of the problem of "instantaneous high power demand during ACMP start design", the existing RAT cabin and RAT system structure design all need to take 2 times overload design as the main consideration. The higher the overload design requirement of the RAT system is, the more the weight and cost of the aircraft are multiplied.

[0033] To overcome the above-mentioned defects, the inventor finds that the ACMP soft start can effectively solve the problem, so that the RAT with 1.5 times of overload capacity can also successfully start the ACMP. The ACMP soft start refers to the output of the RAT system after the adjustment of the transformer rectifier and the motor controller (MC) to start the ACMP.

[0034] The simulation current change curve of the normal start (re-start) of the ACMP is shown in FIG. 1, and the simulation current change curve of the soft start (adjustment via the transformer rectifier and the motor controller) of the ACMP is shown in FIG. 2. By comparing the current change curves in the two figures, it can be seen that the starting current is obviously smaller in the soft start case. Specifically, when the starting time is increased to 3 times of the original time but is still less than 1s, the 1.5 times of the overload power generation capacity can ensure the smooth starting process, thus reducing the dependence on the 2 times of the overload power generation capacity of the RAT system and having better technical expandability. Figure 1 Figure 2

[0035] Specifically, the RAT system ACMP soft start needs to output direct current via the transformer rectifier first, and the voltage amplitude is large, so it is high-voltage electricity. Then, the high-voltage electricity is output as three-phase alternating current via the motor controller (MC) and then powers the ACMP. After the above-mentioned conversion, the ACMP soft start only needs 1.5 times of the overload capacity of the RAT system to start the ACMP, so it is not necessary to use 2 times of the overload capacity which requires more weight and cost.

[0036] At the same time, the APU starting via the SGCU through the transformer rectifier is also a technology that can effectively solve the APU starting related risks in cold working conditions. It can effectively start the APU in a low-temperature environment, thereby reducing the pressure on the battery and improving the service life of the battery.

[0037] Since the transformer rectifier is used in the two improved starting methods, and the functions of the transformer rectifiers are similar, it is possible to further optimize them.

[0038] The purpose of the present application is to reuse the devices for the soft start ACMP of the RAT system and the devices in the APU alternating current starting, so as to reduce the weight of the important devices of the aircraft while meeting the performance requirements of the original design.

[0039] Specifically, the schematic environment block diagram of a transformer rectifier (TRU) reuse system for the RAT system ACMP soft start and the APU alternating current start according to one embodiment of the present application is shown in FIG. 3. Figure 3

[0040] ​​​As mentioned before, the TRU multiplexing system needs to satisfy the TRU requirement of both APU AC starting and ACMP soft starting at the same time, thus, it has two working modes.

[0041] In the first working mode (APU AC starting), under normal condition, the RGLC switch (RGLC = Right Generator Line Contact) is always kept at the L or R AC BUS side to direct the current from, for example, RVFG (Right Variable Frequency Generator) to the R AC BUS (Right AC Busbar) to the AC ESS 3PH (3-Phase AC Essential Busbar). Here, the AC ESS 3PH splits the total current to each consumer including the ACMP BUS (ACMP Busbar). On the ACMP BUS branch, the AC power from the AC ESS 3PH is provided to the TRU and after processing, high voltage DC power is outputted. Here, a multiplexer MUX is provided to implement the time-sharing multiplexing logic of the TRU. The time-sharing multiplexing logic uses the TSC Drive outgoing signal (also referred to as "TRU start contactor drive signal") as the control source to switch the multiplexer MUX. That is, the multiplexer MUX is configured to switch the high voltage DC power from the TRU to the corresponding branch of the APU starting branch and the ACMP soft starting branch according to whether the TSC Drive signal is active or not. Specifically, the TSC Drive signal is set to be active or not according to the instruction from the TRU start contactor (e.g. TSC Drive is set to be active when the instruction from the TRU start contactor is received, e.g. "TSC Drive = 1") to indicate that the TRU is working for APU starting, that is, the multiplexer MUX closes its contact to the following APU starting branch composed of TSC, SGCU and ASG. Thus, the high voltage DC power from the TRU is provided to the TSC (TRU start contactor), and after being controlled and regulated by the SGCU, the high voltage DC power is provided to the ASG (APU starting generator) to implement the starting of the APU.

[0042] In the second operating mode (RAT system ACMP soft start), when the aircraft loses its main AC power and the RAT system provides emergency power, the RGLC switch is switched to the RAT system side to direct current from the RAT system to AC ESS3PH. Here, AC ESS3PH shunts the total current to various electrical devices, including the ACMP BUS. On the ACMP BUS branch, current is supplied to the transformer rectifier (TRU) and processed to output DC power. As mentioned earlier, since APU starting is not required in this operating mode, the TSC Drive output signal is set to invalid, for example, "TSC Drive = 0". Accordingly, the multiplexer MUX closes its contacts to the ACMP starting branch consisting of the MC (motor controller) and ACMP. Therefore, the high-voltage DC power from the transformer rectifier (TRU) is first regulated to three-phase AC power by the MC before supplying power to the ACMP to achieve soft start of the ACMP. By using a transformer rectifier and a motor controller, the active power can be effectively increased, thereby ensuring the successful start-up of the ACMP.

[0043] It is not difficult to understand from the above introduction that, Figure 3 In the overall schematic diagram, the main improvements are in the transformer rectifier (TRU) and multiplexer (MUX), indicated by the dashed boxes. These components enable time-division multiplexing of the transformer rectifier in both operating modes, and therefore, they can be collectively referred to as a transformer rectifier multiplexing system.

[0044] As explained above, the time-sharing multiplexing design of the transformer rectifier allows it to provide services for APU startup and RAT system ACMP startup at different times. This not only increases the success rate of RAT system ACMP startup but also allows for a reduction in RAT system blade size (due to the requirement of only 1.5 times system overload design) and weight. The reduced RAT system weight further reduces the inertial force during release, thereby lowering the impact of ultimate loads on the structure and consequently reducing structural strength requirements. This achieves the goal of significantly reducing the RAT compartment volume and structural weight.

[0045] After introducing the hardware structure of the transformer-rectifier multiplexing system, combined with Figure 4 Let's take a closer look at the schematic flowchart of the transformer-rectifier multiplexing method corresponding to the above structure. It should be understood that, in combination with... Figure 3 In describing the specific operating modes, the content that truly involves the time-sharing multiplexing of the transformer rectifier only includes... Figure 3the operations performed by the components in the dashed box. The operations of the remaining components are not within the scope of the multiplexing operation and are only given for the purpose of making the description of the two working modes above more clear and easy to understand, and thus they are not included in the flowchart Figure 4 .

[0046] As shown in the figure, after the method starts, first, in step 402, it is determined whether the TSC Drive signal is valid.

[0047] If it is determined that the TSC Drive signal is valid, i.e. “Yes”, it indicates that the transformer rectifier works for APU starting. Therefore, in step 404, the multiplexer MUX switches to the APU starting branch side composed of TSC, SGCU and ASG, so that the current from the transformer rectifier is provided to the branch to realize the starting of the APU.

[0048] On the other hand, if it is determined that the TSC Drive signal is invalid, i.e. “No”, it indicates that the transformer rectifier works for ACMP soft starting. Therefore, in step 406, the multiplexer MUX switches to the ACMP starting branch side composed of MC and ACMP, so that the current from the transformer rectifier is provided to the branch to realize the soft starting of the ACMP.

[0049] In this way, the same transformer rectifier can be used for time-sharing multiplexing in ACMP soft starting and APU starting.

[0050] Advantages of the present scheme:

[0051] 1. The multiplexing of the transformer rectifier can reduce the weight by 9 kg on the basis of the scheme of using two transformer rectifiers for the original RAT system soft starting of the ACMP and the original APU AC starting, which has good economy. At the same time, considering the weight reduction factors of the RAT system and the RAT cabin itself (smaller system overload design requirements), a better weight reduction effect can be achieved in practice.

[0052] 2. Since the auxiliary power generation and the emergency power generation are both non-essential equipment, the multiplexing of the transformer rectifier for these two systems can improve the utilization rate of the equipment, and is also conducive to the starting of the APU and the ACMP in high-cold regions.

[0053] The above embodiments are described by taking a certain type of large passenger aircraft as an example, and thus the voltage, current, weight and other parameters mentioned are applicable to this type of aircraft. However, it should be understood that the scheme can also be applied to other types of aircraft, and only needs to be fine-tuned according to the parameters of each type of aircraft. Therefore, they all belong to the protection scope of the present application.

[0054] While the foregoing describes different embodiments, it will be appreciated that they are presented as examples only and not limitation. As such, those skilled in the art will appreciate that changes can be made in form and detail without departing from the spirit and scope of the application as defined by the appended claims. Accordingly, the breadth and scope of the application disclosed herein should not be limited by any of the above-described exemplary embodiments, but should be defined in accordance with the following claims and their equivalents.

Claims

1. A transformer rectifier multiplexing system for ACMP soft start and APU AC start of RAT system, comprising: a transformer rectifier (TRU) configured to convert input AC power to high voltage DC power for output; and a multiplexer (MUX) configured to switch high voltage DC power from the transformer rectifier to a respective one of an APU start branch and an ACMP soft start branch depending on whether a TSC Drive signal is active; wherein: whether the TSC Drive signal is active is set according to instructions from a transformer rectifier start contactor; if the TSC Drive signal is active, the multiplexer switches the high voltage DC power from the transformer rectifier to the APU start branch; if the TSC Drive signal is not active, the multiplexer switches the high voltage DC power from the transformer rectifier to the ACMP soft start branch. the APU start branch is comprised of a TSC, a SGCU, and an ASG.

2. The transformer rectifier multiplexing system of claim 1, wherein, the ACMP soft start branch is comprised of a motor controller (MC) and an ACMP.

3. The transformer rectifier multiplexing system of claim 1, wherein, the motor controller converts the high voltage DC power from the transformer rectifier to AC power output, and by such conversion extends the start time of the ACMP, thereby reducing load torque during load start.

4. The transformer rectifier multiplexing system of claim 3, wherein, 5. A transformer rectifier multiplexing method for ACMP soft start and APU AC start of RAT system, comprising: determining whether a TSC Drive signal is active; if the TSC Drive signal is active, switching high voltage DC power from a transformer rectifier to an APU start branch; if the TSC Drive signal is not active, switching the high voltage DC power from the transformer rectifier to an ACMP soft start branch; wherein the method further comprises setting whether the TSC Drive signal is active according to instructions from a transformer rectifier start contactor. ​

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