Ground test verification platform of hybrid aircraft electric propulsion thermal management system

Abstract

The invention discloses a ground test verification platform for an electric propulsion thermal management system of a hybrid aircraft. The ground test verification platform comprises a liquid cooling source framework and a control module, the liquid cooling source framework comprises a propylene glycol cooling loop group and a lubricating oil cooling loop group; the propylene glycol cooling loop group comprises three independent loops which are respectively used for cooling the rectifier group, the lithium battery group and the motor controller group; the lubricating oil cooling loop group comprises two independent loops which are respectively used for cooling the generator set and the propulsion motor set; and the control module is used for integrating real-time acquisition of temperature, flow and pressure sensors of each node of the liquid cooling source framework, and closed-loop control is carried out by a PID control model. According to the invention, through five independent but complementary cooling loops, the precise temperature control of each key thermal load device of the hybrid aircraft is realized, and the stability of thermal balance under multiple working conditions is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace, and particularly relates to a ground test verification platform for the thermal management system of a hybrid aircraft electric propulsion system. Background Art

[0002] With the global aviation industry's transformation towards green and low-carbon development, hybrid aircraft have gradually become a research hotspot in the aviation field due to their potential for energy conservation and emission reduction. Hybrid aircraft combine the advantages of traditional fuel power and electric propulsion systems, significantly reducing fuel consumption and carbon emissions. However, key components in the electric propulsion system, such as high-power generators, high-energy-density lithium battery packs, and high-thrust propulsion motors, generate a large amount of heat during operation. If the heat cannot be dissipated in a timely and effective manner, it will lead to excessively high component temperatures, thereby affecting their performance, reliability, and service life, and may even cause serious safety problems. Therefore, an efficient thermal management system is one of the key technologies to ensure the safe and stable operation of hybrid aircraft.

[0003] Currently, the thermal management systems of hybrid aircraft mainly rely on single cooling solutions, such as air cooling, liquid cooling, or phase change cooling. However, these traditional cooling methods have the following technical problems:

[0004] Insufficient cooling efficiency: Single cooling methods are difficult to meet the differentiated heat dissipation requirements of different components (such as batteries, motors, generators, etc.). For example, lithium batteries have extremely high requirements for temperature uniformity, while high-power motors require rapid heat dissipation, and traditional cooling solutions are difficult to balance.

[0005] System complexity and high cost: Existing thermal management systems usually adopt independent cooling circuits, resulting in complex system structures, increased weight, and the need for additional control strategies, increasing the R & D and maintenance costs.

[0006] Poor adaptability: The operating conditions of hybrid aircraft are variable, and single cooling solutions are difficult to maintain efficient heat dissipation under different power loads and environmental conditions, affecting the overall reliability of the system.

[0007] Insufficient verification means: Currently, there is a lack of modular and scalable ground verification platforms, making it difficult to fully test and optimize newly designed thermal management systems for hybrid aircraft, restricting the R & D process of new thermal management technologies.

[0008] Therefore, the development of an efficient and modular ground verification platform is of great practical significance for the thermal management system of new hybrid aircraft. Summary of the Invention

[0009] To solve the above technical problems, the present invention proposes a ground test verification platform for the thermal management system of a hybrid aircraft electric propulsion system, which realizes the verification and optimization of each key subsystem of the thermal management system through modular design, ensuring that each component in the aircraft electric propulsion system maintains thermal balance and stable operation under various working conditions, so as to solve the problems existing in the above prior art.

[0010] To achieve the above object, the present invention provides a ground test verification platform for the thermal management system of a hybrid aircraft electric propulsion system, comprising a liquid cooling source architecture and a control module;

[0011] The liquid cooling source architecture includes a propylene glycol cooling circuit group and a lubricating oil cooling circuit group;

[0012] The propylene glycol cooling circuit group includes three independent circuits for cooling the rectifier group, the lithium battery group, and the motor controller group respectively;

[0013] The lubricating oil cooling circuit group includes two independent circuits for cooling the generator set and the propulsion motor group respectively;

[0014] The control module is used to integrate the real-time acquisition of the temperature, flow rate, and pressure sensors at each node of the liquid cooling source architecture, and perform closed-loop control by a PID control model.

[0015] Optionally, the propylene glycol cooling circuit group includes:

[0016] The first circuit includes a first propylene glycol liquid cooling source, a left rectifier, and a right rectifier, and the first propylene glycol liquid cooling source is connected to the left rectifier and the right rectifier through pipelines;

[0017] The second circuit includes a second propylene glycol liquid cooling source, a left lithium battery, and a right lithium battery, and the second propylene glycol liquid cooling source is connected to the left lithium battery and the right lithium battery through pipelines;

[0018] The third circuit includes a third propylene glycol liquid cooling source, a first motor controller, and a second motor controller, and the third propylene glycol liquid cooling source is connected to the first motor controller and the second motor controller through pipelines.

[0019] Optionally, the lubricating oil cooling circuit group includes:

[0020] The fourth circuit includes a first lubricating oil liquid cooling source, a left generator, and a right generator, and the first lubricating oil liquid cooling source is connected to the left generator and the right generator through pipelines;

[0021] The fifth circuit includes a second lubricating oil liquid cooling source, a first propulsion motor, and a second propulsion motor, and the second lubricating oil liquid cooling source is connected to the first propulsion motor and the second propulsion motor through pipelines.

[0022] Optionally, the liquid cooling source architecture adopts a cabinet modular design, and internally integrates a heat exchanger, a fan, a water tank, an electric control box, a filter, a liquid supply pump, and valves.

[0023] Optionally, the liquid cooling source architecture transports the cooling medium to the heat load device based on the flow rate and head of the liquid supply pump.

[0024] Optionally, the liquid cooling source architecture uses a fan or a compressor refrigeration system to dissipate heat from the cooling medium, ensuring that the temperature of each loop device is always controlled within the set range.

[0025] Optionally, the calculation formula for the flow rate of the liquid supply pump is as follows:

[0026]

[0027] Where Q is the flow rate of the liquid supply pump; is the total heat to be dissipated by the system; ΔT is the temperature difference of the coolant in the heat exchanger; ρ is the density of the coolant; c p is the specific heat capacity of the coolant.

[0028] Optionally, the calculation formula for the head of the liquid supply pump is as follows:

[0029]

[0030] Where H is the total head that the liquid supply pump needs to provide; H 静 is the static height difference that the system needs to overcome; f is the Darcy pipe friction coefficient; L is the total length of the pipeline; D is the inner diameter of the pipeline; v is the average flow velocity of the fluid in the pipe; g is the acceleration due to gravity; K L is the single local loss coefficient, and ∑K L represents the sum of all local loss coefficients.

[0031] Optionally, the calculation formula for the PID control model is as follows:

[0032]

[0033] Where u(t) is the output of the PID control signal; e(t) is the error signal; K p , K i , K d are the proportional, integral, and differential gain coefficients of the PID controller respectively; T set and T act are the set value and the actual measured value of the temperature respectively; P set and P act are the set value and the actual measured value of the pressure respectively; and are the set value and the actual measured value of the mass flow rate respectively; t and τ are time variables.

[0034] Optionally, it further includes a communication module, which is used to achieve dual control of remote monitoring by the host computer and local operation through an Ethernet communication interface.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] Through five independent but complementary cooling circuits, the present invention realizes precise temperature control of each key heat load device of a hybrid aircraft, ensuring the stability of thermal balance under multiple working conditions.

[0037] The present invention utilizes temperature, pressure, flow sensors and PID closed-loop control technology to realize real-time monitoring and precise management of the platform state, improving the automation level and fault response ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0039] Figure 1 is the overall architecture diagram of the ground test verification platform for the electric propulsion thermal management system of a hybrid aircraft according to an embodiment of the present invention;

[0040] Figure 2 is the schematic diagram of the internal cooling channels of a single liquid-cooled device according to an embodiment of the present invention;

[0041] Figure 3 is the control mode flow chart of the electric control system of the liquid-cooled device according to an embodiment of the present invention;

[0042] Figure 4 is the temperature control flow chart according to an embodiment of the present invention;

[0043] Figure 5 is the principle block diagram of the data acquisition and control system according to an embodiment of the present invention;

[0044] Figure 6 is the PLC circuit diagram of the control system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail this application.

[0046] It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0047] Example 1

[0048] As Figure 1 shown, in this embodiment, a ground test verification platform for the thermal management system of a hybrid aircraft electric propulsion system is provided. This platform integrates multiple cold sources and their corresponding control systems, has high adaptability and scalability, aims to improve the overall heat dissipation efficiency of the thermal management system, reduce the system complexity and cost, and at the same time meet strict industrial and environmental requirements.

[0049] The technical pain points of the thermal management of the hybrid aircraft electric propulsion system to be solved in this embodiment are as follows:

[0050] Thermal load differences of heterogeneous devices: The thermal characteristics of key devices such as motors, batteries, and electronic control units are significantly different under different working conditions, and it is necessary to provide thermal management for the above devices under full flight profile conditions.

[0051] Difficulties in multi-medium collaborative control: Key devices such as motors, batteries, and electronic control units use different cooling cycle media, and there are physical property differences between propylene glycol solution and aviation lubricating oil. It is necessary to establish a flow and heat transfer model for different cooling cycle media to achieve precise temperature control of the thermal management system.

[0052] Dynamic working condition response requirements: Under flight simulation conditions, the thermal loads of motors, batteries, and electronic control units are transient and variable. It is necessary to develop a highly robust control heat absorption to achieve precise control of the temperature fluctuation range.

[0053] To address the above technical pain points, the platform proposed in this embodiment includes a liquid cold source architecture and a control module;

[0054] The liquid cold source architecture includes a propylene glycol cooling circuit group and a lubricating oil cooling circuit group;

[0055] The propylene glycol cooling circuit group includes three independent circuits for cooling the rectifier group, lithium battery group, and motor controller group respectively; the lubricating oil cooling circuit group includes two independent circuits for cooling the generator set and the propulsion motor group respectively;

[0056] The control module is used to integrally collect the real-time temperature, flow rate, and pressure sensors of each node of the liquid cold source architecture and perform closed-loop control by a PID control model.

[0057] Implementable, the propylene glycol cooling circuit group includes:

[0058] The first circuit includes a first propylene glycol liquid cold source, a left rectifier, and a right rectifier. The first propylene glycol liquid cold source is connected to the left rectifier and the right rectifier through pipelines;

[0059] The second circuit includes a second propylene glycol liquid cooling source, a left lithium battery, and a right lithium battery. The second propylene glycol liquid cooling source is connected to the left lithium battery and the right lithium battery through pipelines.

[0060] The third circuit includes a third propylene glycol liquid cooling source, a first motor controller, and a second motor controller. The third propylene glycol liquid cooling source is connected to the first motor controller and the second motor controller through pipelines.

[0061] Implementable, the lubricating oil cooling circuit group includes:

[0062] The fourth circuit includes a first lubricating oil liquid cooling source, a left generator, and a right generator. The first lubricating oil liquid cooling source is connected to the left generator and the right generator through pipelines.

[0063] The fifth circuit includes a second lubricating oil liquid cooling source, a first propulsion motor, and a second propulsion motor. The second lubricating oil liquid cooling source is connected to the first propulsion motor and the second propulsion motor through pipelines. In this embodiment, through five independent but complementary cooling circuits, precise temperature control is achieved for each key heat load device of the hybrid aircraft, ensuring the stability of thermal balance under multiple working conditions.

[0064] Furthermore, each circuit uses propylene glycol or lubricating oil as the cooling medium, and heat removal is achieved through forced air cooling or compression refrigeration methods, thereby achieving the purpose of efficient thermal balance.

[0065] Implementable, the liquid cooling source architecture adopts a cabinet modular design, with units such as heat exchangers, fans, water tanks, electric control boxes, filters, liquid supply pumps, and valves integrated inside. The liquid supply and return interfaces are arranged on the left side of the unit for easy connection and operation. This embodiment adopts a cabinet modular design, which is convenient for installation, commissioning, and later maintenance, and at the same time meets the requirements for use in harsh outdoor environments, improving the adaptability and reliability of the system.

[0066] Implementable, the insulation layer in the liquid cooling source architecture uses rubber and plastic sponge wrapped with non-woven fabric to ensure stable heat transfer performance of the system in both high-temperature and low-temperature environments.

[0067] Implementable, heat is cyclically transferred between liquid cooling source architectures through liquid supply pumps and heat exchangers, and the cooled medium is dissipated by a fan or a compression refrigeration system to ensure that the temperature of each circuit device is always controlled within the set range.

[0068] Furthermore, the liquid cooling source architecture transports the cooling medium to the heat load device based on the flow rate and head of the liquid supply pump.

[0069] As Figure 2 shown, it is a schematic diagram of the internal cooling channels of a single liquid cooling device in this embodiment, and its system composition and working principle are described as follows:

[0070] Cooling medium circuit: The system forms a closed loop in which the cooling medium circulates continuously.

[0071] Coolant reservoir (water tank): As the main liquid storage unit of the system, it is used to store the cooling medium and plays a role in expansion compensation and gas separation to a certain extent. It is equipped with a liquid level indicator / sensor for monitoring the coolant volume. The upper pipeline is used for exhaust and liquid filling. The valve at the bottom is used for emptying and maintenance.

[0072] Circulation pump: Located downstream of the reservoir, it is the power source of the loop. This pump provides the necessary head and flow rate for the cooling medium, driving it to circulate forcibly throughout the loop. A check valve is usually installed at the pump outlet to prevent the medium from flowing back when the machine stops.

[0073] Heat exchanger: Located downstream of the pump, it is the main heat dissipation unit of the system. The high-temperature cooling medium flows through here, transferring the heat it carries to the air flowing through the radiator, thereby achieving the cooling of the cooling medium.

[0074] Fine filter: Installed on the main pipeline after the heat exchanger and before entering the load. Its function is to filter out possible solid particle impurities (such as metal chips, sealing material debris, etc.) in the cooling medium to protect the downstream precision and high-cleanliness-required load components (such as the cooling channels of power electronic devices) from being blocked or worn. Pressure sensors (P) are equipped before and after the filter for monitoring the pressure drop of the filter to judge whether it is blocked and needs maintenance or replacement.

[0075] Heat load: Represents the heat-generating components in the hybrid aircraft electric propulsion system that need to be cooled, such as the three parallel loads shown in the figure. These may include motors, inverters, battery packs, or other power electronic units. The cooling medium flows through the cooling channels or cold plates inside these loads, absorbing the heat generated by them. The parallel structure allows multiple components to be cooled simultaneously, and the flow rate can be adjusted or isolated through the valves of each branch. An isolation valve is provided for each load branch, and a differential pressure sensor is equipped to monitor the pressure drop across the load, which can indirectly reflect the flow rate or whether there is a blockage.

[0076] Pipeline system and valves: The pipelines connecting all the above components form the flow path of the cooling medium. In addition to the isolation valves of the load branches and the valves of the reservoir / pump, a main regulating valve or isolation valve is set before entering the load distribution pipeline.

[0077] Measurement and monitoring instruments: A variety of sensors are arranged in the system to monitor the operating status:

[0078] Temperature sensor (T): At least distributed at key positions such as the reservoir outlet / pump inlet, heat exchanger outlet, and before entering the load, for measuring the temperature of the cooling medium, which is a key parameter for evaluating the cooling performance of the system and for control and regulation.

[0079] Pressure sensor (P): Installed before and after the filter, used to monitor the system pressure and pressure drop across components.

[0080] Differential pressure sensor (dp / d): Connected across each load, used to monitor the pressure drop across the load.

[0081] Liquid level sensor / indicator: Located in the storage tank, monitors the coolant inventory.

[0082] Workflow:

[0083] The cryogenic cooling medium flows out from the bottom of the storage tank, is pressurized by the circulation pump, and then flows to the heat exchanger. In the heat exchanger, if the medium temperature is higher than the temperature of the heat dissipation medium (air), heat exchange occurs and the medium is cooled. The cooled medium flows through the fine filter to remove impurities. Subsequently, it is branched through the distribution pipeline to each parallel heat load. The medium absorbs heat and warms up inside the load. The high-temperature medium leaving each load mixes in the confluence pipeline and then returns to the top or upper part of the storage tank through the main return pipe, completing one cycle. The system monitors parameters such as temperature, pressure, flow rate (indirectly through pressure drop), and liquid level through sensors, and can achieve automatic control (such as adjusting pump speed, fan speed, or bypass valve opening) to maintain the load temperature within the set range.

[0084] As an implementable method, the design and selection of the liquid supply pump are based on the following calculation formulas:

[0085] 1) Calculation of the liquid supply pump flow rate:

[0086] The design of the liquid supply pump flow rate Q is based on the system heat load and the temperature difference of the cooling medium. The formula is:

[0087]

[0088] Where: represents the total heat to be dissipated by the system (unit: W); ΔT is the temperature difference of the coolant in the heat exchanger (unit: K); ρ is the density of the coolant (unit: kg / m 3 ); c p is the specific heat capacity of the coolant (unit: J / (kg·K)).

[0089] 2) Calculation of the head:

[0090] The calculation formula for the head of the liquid supply pump is as follows:

[0091] The total head H of the pump is to overcome the static height difference in the system and compensate for the total energy loss generated when the fluid flows in the pipeline (usually expressed as head loss). The calculation is divided into the following steps:

[0092] ① Calculate the total system pressure drop ΔP 系统: The total pressure drop of the system ΔP is caused by the frictional pressure drop ΔP along the pipeline 沿程 and the pressure drop ΔP caused by the local resistance caused by pipeline components (such as elbows, valves, reducers, inlets and outlets, etc.). 局部 It consists of

[0093] Frictional pressure drop:

[0094] Local pressure drop:

[0095] Total pressure drop of the system:

[0096] ② Convert the total pressure drop ΔP 系统 into a head loss:

[0097] Expand it to:

[0098] ③ Calculate the total head H of the pump: The total head is equal to the sum of the static head difference and the total head loss:

[0099] H = H 静 + H 损失 ;

[0100] Substitute the expression of H 损失 to get:

[0101] Among them, the physical meanings of each parameter are as follows:

[0102] H is the total head that the liquid supply pump needs to provide, representing the total energy imparted by the pump to the fluid; H 静 is the static head difference that the system needs to overcome, that is, the vertical height difference between the liquid outlet and the liquid inlet; H 损失 is the total head loss of the fluid flowing through the entire pipeline system (including straight pipes and local components); ΔP 系统 is the total pressure drop of the pipeline system, which is composed of the frictional pressure drop ΔP 沿程 and the local pressure drop ΔP 局部 ; f is the Darcy pipeline friction coefficient, which is related to the flow regime and the wall roughness; L is the total length of the pipeline; D is the inner diameter of the pipeline; ρ is the fluid density; v is the average flow velocity of the fluid in the pipe; g is the acceleration due to gravity; K L is the single local loss coefficient, and ∑K L represents the sum of all local loss coefficients.

[0103] 3) Calculation of pump power:

[0104] The power P of the liquid supply pump 泵 is calculated according to the following formula:

[0105]

[0106] where: g is the acceleration due to gravity (9.81 m / s 2 ); η 泵 is the efficiency of the pump (usually between 0.5 and 0.8).

[0107] As a specific implementation, the design and selection of the heat exchanger are based on the following calculation formulas:

[0108] 1) Heat power calculation:

[0109]

[0110] where: is the mass flow rate of the coolant (unit: kg / s); c p is the specific heat capacity of the coolant (unit: J / (kg·K)); ΔT is the temperature difference of the coolant in the heat exchanger (unit: K).

[0111] 2) Heat transfer rate calculation:

[0112] Q = U·A·ΔT m ,

[0113] where: U is the overall heat transfer coefficient of the heat exchanger (unit: W / (m 2 ·K)); A is the heat transfer area (unit: m 2 ); ΔT m is the logarithmic mean temperature difference (unit: K).

[0114] 3) Logarithmic mean temperature difference (LMTD) calculation:

[0115]

[0116] where: ΔT1 is the temperature difference between the hot fluid and the cold fluid at the inlet; ΔT2 is the temperature difference between the two fluids at the outlet.

[0117] 4) Heat transfer coefficient calculation:

[0118] The calculation of the heat transfer coefficient takes into account the internal and external heat transfer resistances and the tube wall thermal resistance, and its formula is:

[0119]

[0120] where: h i is the convective heat transfer coefficient inside the tube (unit: W / (m 2 ·K)); h o is the convective heat transfer coefficient outside the tube (unit: W / (m 2 ·K)); δ is the wall thickness of the tube (unit: m); k is the thermal conductivity of the tube material (unit: W / (m·K)).

[0121] 5) Heat transfer area calculation:

[0122]

[0123] 6) Calculation of convective heat transfer coefficient:

[0124] Using the Nusselt number formula, the convective heat transfer coefficient inside the pipe is expressed as:

[0125]

[0126] For the turbulent flow state, the Dittus - Boelter equation can be adopted:

[0127] Nu=0.023·Re 0.8 ·Pr n

[0128] Where: Re is the Reynolds number (describing the fluid flow characteristics); Pr is the Prandtl number (describing the fluid heat transfer characteristics); n takes 0.4 for the heating fluid and 0.3 for the cooling fluid; D is the pipe diameter (unit: m); k is the fluid thermal conductivity (unit: W / (m·K)).

[0129] 7) Pressure drop calculation:

[0130] The pressure drop inside the heat exchanger is also calculated using the Darcy - Weisbach formula:

[0131]

[0132] The definitions of the variables are the same as those described above.

[0133] Implementably, the liquid cooling source device is equipped with two control modes: remote control and local control.

[0134] As Figure 3 shown is the control mode flow chart of the electric control system of the liquid cooling device in this embodiment. This flow chart details the operation logic and control sequence, explains the state transition, decision - making process, fault handling mechanism from the initial power - on of the system, through different operation modes until shutdown, as well as the interaction method with external interfaces (such as remote control instructions and local human - machine interface). The control logic aims to ensure autonomous and reliable thermal regulation of key propulsion components under variable operating conditions.

[0135] The control process is as follows:

[0136] 1) System initialization (device power - on): The control process starts when the control unit of the thermal management system obtains power supply.

[0137] 2) Power-on Self-test (Equipment Self-test): After power-on, the system forcibly executes a self-diagnosis program. This step aims to verify the integrity and readiness of key hardware components, sensors, actuators, and communication links related to the thermal management system.

[0138] Fault Condition: If any abnormalities or failures (faults) are detected during the self-test process, the system will transfer to a dedicated fault handling program. This program may include recording fault information, issuing an alarm to the maintenance system, entering a safe state, or preventing further system operation until the fault is eliminated.

[0139] Normal Condition: If the self-test sequence is successfully completed and no faults are detected, the control logic enters the next stage.

[0140] 3) Control Mode Selection (Mode Switching): The system determines the current effective control authority. The main modes include remote control and local control, with remote control set as the default mode.

[0141] Remote Control Mode: It is activated when this mode is selected or by default, and when the remote control communication is effective (i.e., the communication link with the superior system is normal). In this mode, the operation of the thermal management system mainly depends on instructions sent via the communication bus from a higher-level system (such as the aircraft main flight control computer or a dedicated energy management system). Control actions generally follow an automatic control process based on remote instructions and sensor feedback.

[0142] Local Control Mode: It is activated when this mode is explicitly selected (e.g., in maintenance or specific operation scenarios). The activation condition is that the local touch screen is effective, indicating that the local human-machine interface (HMI) is in an operable state. This mode allows the execution of automatic / manual control processes, either starting the local automatic control sequence or directly performing manual intervention and parameter adjustment through the touch screen interface.

[0143] 4) Operation Start Judgment (Whether to Start): The system checks whether an instruction to initiate the active thermal management operation has been received (depending on the currently activated mode, it may be from remote or local).

[0144] Standby State: If no start instruction (No) is received, the system enters or remains in the standby state. At this time, the system is powered on and ready, but does not actively execute heating or cooling functions.

[0145] Activated Operation: If it is confirmed that a start instruction (Yes) has been received, the system enters the active operation logic.

[0146] 5) Operation Condition Judgment (Condition Judgment): The controller determines the current required thermal management operation mode based on the temperature sensor input, system status signals, and possibly received instructions.

[0147] Identified Modes: The flow chart clearly lists preheating, refrigeration, and forced cooling as possible operating conditions or modes. The "preheating" function is designed to heat the components to the optimal operating temperature in cold environments. "Refrigeration" represents the standard heat dissipation operation. "Forced cooling" may indicate a high-power cooling mode activated under peak heat load conditions. The specific control algorithms for each mode are executed in the corresponding "automatic / manual control process".

[0148] 6) Fault Monitoring during Operation (Fault Judgment during Operation): During the active operation of the system, the fault status is continuously monitored. This includes internal monitoring and may involve processing fault information transmitted from or co-diagnosed with the upper computer (monitoring computer / main system). Detected faults during operation will trigger corresponding fault handling procedures, which may result in adjustments to operating parameters or system shutdown.

[0149] 7) Shutdown Instruction Judgment (Whether to Shutdown): The system continuously monitors whether it receives an instruction to stop active operation.

[0150] Instruction Shutdown: If a shutdown instruction (yes) is received, the system will initiate the normal shutdown procedure.

[0151] Fault Shutdown: If a serious fault (detected during power-on self-test or operation) requires immediate stop of operation, or if a shutdown instruction is received after a non-serious fault occurs, the system will execute the fault shutdown procedure to ensure a safe transition to the inactive state.

[0152] Continue Operation: If no shutdown instruction is received and there is no serious fault (no), the system implicitly loops back to the previous step, continues to monitor the operating conditions, and executes the corresponding operating logic.

[0153] Implementable, the main functions of the control system include temperature control and flow regulation. Each key parameter (supply liquid temperature, flow rate, pressure) is collected in real-time by temperature, flow rate, and pressure sensors distributed at various nodes of the system, and closed-loop control is performed by the PID regulation module. The multi-variable PID control model is established as follows:

[0154]

[0155] where, u(t) is the output of the PID control signal; e(t) is the error signal (which can be a vector composed of temperature error T set -T act , pressure error P set -P act , flow rate error etc.); K p , K i , K d are the proportional, integral, and derivative gain coefficients of the PID controller respectively; T set and T actare the set value and the actual measured value of temperature; P set and P act are the set value and the actual measured value of pressure respectively; and are the set value and the actual measured value of mass flow rate respectively; t and τ are time variables.

[0156] As Figure 4 shown in the temperature control flowchart of this embodiment, this strategy adopts a closed-loop feedback control mechanism, aiming to accurately maintain the actual temperature of the system at the preset target value.

[0157] The control process starts with setting the target temperature value, i.e., "set temperature Xt", which serves as the reference or "target signal" of the control system. The system monitors and obtains the current actual temperature, i.e., "real-time feedback temperature Xr", through sensors as the "feedback signal".

[0158] The core of the control lies in calculating the deviation between the feedback temperature Xr and the set temperature Xt, defined as the control error X0 = Xr - Xt. The programmable logic controller (PLC) makes control decisions based on this error signal. The figure shows that this PLC adopts a proportional-integral-derivative (PID) control algorithm (labeled as "PLC performs PID operation") to process the error signal and generate adjustment instructions.

[0159] The specific control logic makes branch judgments based on the sign and magnitude of the error X0:

[0160] When the real-time feedback temperature Xr is greater than the set temperature Xt (X0 > 0), it indicates that the current temperature of the system is too high, "feedback signal is greater than the target signal". At this time, the PLC increases its control output value (represented as F↑), and this output signal drives the actuator (such as a cooling fan, water pump, or regulating valve), resulting in an "increase in cooling capacity" (represented as n↑) of the system. The enhanced cooling effect causes the "temperature of the system to drop" (represented as T↓), aiming to drive Xr closer to Xt.

[0161] When the real-time feedback temperature Xr is equal to the set temperature Xt (X0 = 0), it indicates that the system has reached the target temperature. Under this steady-state condition, the PLC keeps the "output unchanged", and the current temperature of the system theoretically remains unchanged, maintaining the existing cooling or heating level.

[0162] When the real-time feedback temperature Xr is less than the set temperature Xt (X0 < 0), it indicates that the current temperature of the system is too low, "feedback signal is less than the target signal". The PLC then reduces its control output value (represented as F↓), correspondingly, the "cooling capacity decreases" (represented as n↓), or a heating process may be started in some designs. This causes the "temperature of the system to rise" (represented as T↑), also aiming to drive Xr closer to Xt.

[0163] The whole process is a continuous negative feedback regulation loop. The system continuously compares the actual temperature with the set temperature and dynamically adjusts the control output through the PID algorithm to precisely control the cooling capacity (or heating capacity). The ultimate goal is to stabilize the real-time feedback temperature Xr at the set temperature Xt (i.e., reach the state of Xr = Xt) and "keep the current output unchanged" in this state to achieve precise temperature control.

[0164] Implementably, the platform built in this embodiment further includes a communication module, which is used to achieve dual control of remote monitoring by the upper computer and local operation through the Ethernet communication interface. This embodiment can achieve seamless switching between remote monitoring by the upper computer and operation on the local display control panel. By integrating temperature, pressure, flow sensors and PID closed-loop control technology, the automation level of the system and the ability to respond to faults are improved.

[0165] As Figure 5 shown is the principle block diagram of the data acquisition and control system of the embodiment of the present invention. The system is mainly composed of two core subsystems that cooperate with each other: the "data acquisition and test system" and the "test piece control system".

[0166] The "data acquisition and test system" is responsible for precisely measuring and recording the operating parameters of the test piece. Its bottom layer consists of multiple "sensors", which directly or indirectly sense the physical quantities of the test piece (such as temperature, pressure, flow, etc.). The sensor signals are transmitted to the "lower computer of the data acquisition and test system". This lower computer usually performs tasks such as signal conditioning, analog-to-digital conversion, preliminary real-time data processing and caching. The acquired original or preliminarily processed data is then transmitted to the "upper computer of the data acquisition and test system". The upper computer undertakes more complex data processing, analysis, storage, status monitoring and presenting the test data to the user through the "display device". In addition, this upper computer also has the ability to receive "data from other systems", reflecting the openness and integration of the system.

[0167] The "test piece control system" is responsible for applying predetermined operating conditions to the test piece or executing specific control algorithms. Its core control object is the "test piece" itself, and the operating power required by the test piece is provided by the "simulated power supply". The lower computer of the "test piece control system" is responsible for issuing control instructions and underlying execution, and it directly interfaces with the test piece. The complex control logic, execution of the test sequence, parsing of user control instructions and monitoring of status feedback are managed by the "upper computer of the test piece control system". Similarly, this upper computer is also connected to a "display device" for displaying control status, set parameters and relevant feedback information.

[0168] Both subsystems adopt a hierarchical structure of "host computer - slave computer". This structure assigns hardware interfaces with high real-time requirements and underlying control / acquisition tasks to the slave computer, while placing complex computing, data management, user interaction, and system coordination functions in the host computer, improving the efficiency and reliability of the system. There is a bidirectional communication link between the host computers of the two subsystems, enabling tight coupling of data acquisition and control: the control system can dynamically adjust the control strategy for the test piece according to the data real-time feedback by the data acquisition system to achieve closed-loop testing; at the same time, the data acquisition system can start, stop, or mark data recording synchronously according to the state or instructions of the control system.

[0169] As Figure 6 Shown is the PLC circuit diagram of the control system according to an embodiment of the present invention, which illustrates the electrical wiring principle of an industrial control system with a programmable logic controller (PLC) as the core. This system integrates functions such as signal input, logic processing, control output, human-machine interaction, and sensor interface, aiming to achieve automatic control of a specific industrial process or equipment.

[0170] The core component in the figure is the PLC controller, which has the ability to process input signals, execute user program logic, and drive output devices. The PLC itself requires an AC power supply (AC220V, connected through L and N terminals) to operate. At the same time, a +24V DC power supply (+24V, 0V) is used in the system to supply power to some circuits of the PLC (such as the input common terminal S / S), external sensors, and devices such as the human-machine interface (touch screen).

[0171] On the input side, the PLC is configured with multiple digital input channels (X0, X1, X2,... X17, etc.). External switch signals, such as the "external input" switch shown in the figure, are connected between the input common terminal S / S (connected to +24V here) and specific X input terminals (such as X1, X3). When the switch is closed, the corresponding X terminal is pulled to a low level (0V, through an internal optocoupler or circuit), thus triggering the input signal. This wiring method indicates that the input type is sinking input.

[0172] On the output side, the PLC provides multiple digital output channels (Y0, Y1, Y2,... Y17, etc.) for driving external actuators. The output types are differentiated: Y0 and Y1 are clearly marked as "transistor" outputs, usually DC fast-response outputs, suitable for driving DC loads or the input terminals of solid-state relays (SSRs). As shown in the figure, Y0 is connected to the control input terminal of the "heating solid-state relay" (SSR1), and Y1 is connected to the control input terminal of the "humidification solid-state relay" (SSR2). These SSRs then control the corresponding AC heating or humidification loads (through the L, N AC power supply). Other output terminals (such as Y3, Y5, Y7,... Y17) may be inferred to be relay outputs or sourcing transistor outputs based on their connection methods to the common terminals (COM1 to COM5, which are connected to +24V) for driving external relay or contactor coils (such as KM4, KM5, KM6, K7 connected in the figure), thereby controlling equipment with greater power or different voltage levels.

[0173] The human-machine interaction function is realized by a "touch screen" (HMI), which exchanges data with the PLC through an RS485 serial communication interface (connected to the COM2 port of the PLC, marked A+, B-), allowing the operator to monitor the system status, set parameters, and issue operation instructions. The touch screen itself is powered by a +24V DC power supply.

[0174] The system also integrates an analog sensing function for monitoring key process parameters. Two PT100 platinum resistance temperature sensors (RTDs) are respectively used to measure the "filter temperature" and the "tank temperature". The sensors are connected in a three-wire configuration (L+ / L-, LC-), and their signals need to be connected to the analog input module of the PLC (or converted through a transmitter) so that the PLC can obtain accurate temperature feedback values for control algorithms (such as the aforementioned PID control).

[0175] In terms of communication, in addition to the RS485 interface (COM2) for HMI connection, the PLC also has other communication ports (such as COM1 shown at the HMI interface in the figure), which can be used to connect to a "centralized monitoring system" or for other network communications to achieve a higher level of data exchange and remote monitoring.

[0176] As an additional implementation method, the propylene glycol liquid cooling source in this embodiment can be replaced with other cooling media having similar heat transfer performance, such as ethylene glycol aqueous solution, or even a new type of nanofluid in order to obtain higher heat transfer efficiency; the lubricating oil circuit can also use other oils or mixed cooling media to meet different thermal management requirements.

[0177] As an additional implementation, in addition to forced air cooling and compression refrigeration, this embodiment can also consider heat dissipation technologies such as liquid-liquid heat exchange, thermoelectric cooling, or phase change materials to further improve the heat removal efficiency and reduce the energy consumption of the equipment.

[0178] As an additional implementation, the control module of this embodiment can adopt a remote control solution based on wireless communication technology to replace the traditional wired communication mode, thereby improving the flexibility of system layout and the remote control ability. At the same time, the adaptive adjustment of PID control parameters or the introduction of fuzzy control methods can also be used as supplementary solutions to optimize the dynamic response of the system.

[0179] As an additional implementation, the modular liquid cooling source design of this embodiment supports the integration with other thermal management devices in the later stage, such as energy storage systems, heat recovery systems, etc., so as to achieve more extensive energy utilization and environmental adaptability.

[0180] Embodiment Two

[0181] This embodiment uses a 40% propylene glycol solution and Pegasus II lubricating oil as the main cooling media. The working principle of the system is as follows: The high-temperature coolant generated by the heat load flows back to the liquid cooling unit, and is initially cooled through forced air cooling or compression refrigeration, and then the low-temperature coolant is transported to each heat source device by the supply pump.

[0182] The specific implementation is as follows:

[0183] 1. Temperature detection and regulation:

[0184] Temperature sensors are set in each supply branch of the system to monitor the supply temperature of the coolant in real time. The temperature signal is sent to the PLC control unit after A / D conversion and is closed-loop regulated based on the following PID control formula:

[0185]

[0186] Where: T 设 is the target supply temperature; T 供 is the actually measured supply temperature.

[0187] For different working conditions, a dynamic load distribution algorithm is established: the load distribution coefficient for the cold source i, to achieve:

[0188]

[0189] For high heat load conditions, normal temperature conditions, and low temperature conditions, different cold source units and heating units are respectively turned on to achieve dynamic heat load distribution and regulation based on different working conditions.

[0190] 2. Pressure and flow monitoring:

[0191] A pressure and flow sensor is configured in each liquid supply system to collect data for calculating the real-time flow rate and head, ensuring that the pressure of each loop is within a safe range. The pipeline pressure drop is calculated according to the following formula:

[0192]

[0193] 3. Water tank temperature stabilization mechanism:

[0194] The water tank temperature control is set to the temperature required by the user. When the temperature is lower than the lower threshold temperature (adjustable), the system stops starting the compression refrigeration or forced air cooling; when the temperature exceeds the upper threshold temperature (adjustable), the system automatically starts the relevant cooling device. This temperature control logic is realized by the cooperation of the temperature sensor and the PID control module.

[0195] 4. Electric heating stepwise start-stop control:

[0196] To cope with the problem of insufficient liquid supply temperature under low-temperature conditions, a 15kW electric heater is introduced at the initial startup of the system, and three-stage stepwise electric heating control is realized. The start and stop of the electric heater are jointly judged based on the liquid supply temperature and the water tank temperature to ensure that the system can quickly reach the preset liquid supply temperature when the ambient temperature is low.

[0197] 5. Liquid cooling source modularization and communication control:

[0198] The platform consists of five independent cooling loops, and each loop adopts an independent liquid cooling source module. The module mainly includes:

[0199] Heat exchange unit: Realize heat exchange by using a fan or compression refrigeration;

[0200] Liquid supply unit: Calculate the flow rate and head of the liquid supply pump and transport the cooling medium to the heat load equipment:

[0201] Electric control unit: Integrate the acquisition of temperature, pressure, and flow signals and PID regulation, and realize dual control of remote monitoring by the upper computer and local operation through the Ethernet communication interface.

[0202] 6. Cooling mode regulation logic:

[0203] In the cooling mode, the electric control unit performs PID regulation based on the difference ΔT = T T between the target value T of the liquid supply temperature and the actually measured value T M . The specific logic is as follows: T -T M When ΔT > 0 (indicating that the temperature is too low), the fan speed is reduced to reduce heat exchange;

[0204] When ΔT < 0 (indicating that the temperature is too high), the PID calculation output is increased, and the fan speed is increased to enhance heat exchange;

[0205] When ΔT < 0 (indicating that the temperature is too high), the PID calculation output is increased, and the fan speed is increased to enhance heat exchange;

[0206] When ΔT = 0, maintain the current operating state.

[0207] The corresponding PID adjustment formula is:

[0208]

[0209] After the control signal passes through the data conversion module, it is converted into a specific fan speed adjustment command.

[0210] This embodiment can achieve seamless switching between the upper computer remote monitoring and the local display control panel operation. By integrating temperature, pressure, flow sensors and PID closed-loop control technology, the automation level of the system and the ability to respond to faults are improved.

[0211] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A ground test verification platform for the thermal management system of a hybrid aircraft's electric propulsion, characterized in that, It includes a liquid cooling source architecture and a control module; The liquid cooling source architecture includes a propylene glycol cooling circuit group and a lubricating oil cooling circuit group; The propylene glycol cooling circuit group includes three independent circuits for cooling a rectifier group, a lithium battery group, and a motor controller group respectively; The lubricating oil cooling circuit group includes two independent circuits for cooling a generator set and a propulsion motor group respectively; The control module is used to integrate the real-time acquisition of temperature, flow rate, and pressure sensors at each node of the liquid cooling source architecture, and perform closed-loop control by a PID control model.

2. The platform according to claim 1, characterized in that The propylene glycol cooling circuit group includes: The first circuit includes a first propylene glycol liquid cooling source, a left rectifier, and a right rectifier, and the first propylene glycol liquid cooling source is connected to the left rectifier and the right rectifier through pipelines; The second circuit includes a second propylene glycol liquid cooling source, a left lithium battery, and a right lithium battery, and the second propylene glycol liquid cooling source is connected to the left lithium battery and the right lithium battery through pipelines; The third circuit includes a third propylene glycol liquid cooling source, a first motor controller, and a second motor controller, and the third propylene glycol liquid cooling source is connected to the first motor controller and the second motor controller through pipelines.

3. The platform according to claim 1, characterized in that The lubricating oil cooling circuit group includes: The fourth circuit includes a first lubricating oil liquid cooling source, a left generator, and a right generator, and the first lubricating oil liquid cooling source is connected to the left generator and the right generator through pipelines; The fifth circuit includes a second lubricating oil liquid cooling source, a first propulsion motor, and a second propulsion motor, and the second lubricating oil liquid cooling source is connected to the first propulsion motor and the second propulsion motor through pipelines.

4. The platform according to claim 1, characterized in that The liquid cooling source architecture adopts a cabinet modular design, and internally integrates a heat exchanger, a fan, a water tank, an electric control box, a filter, a liquid supply pump, and valves.

5. The platform according to claim 4, characterized in that The liquid cooling source architecture transports the cooling medium to the heat load equipment based on the flow rate and head of the liquid supply pump.

6. The platform according to claim 5, characterized in that The liquid cooling source architecture uses a fan or a compressor refrigeration system to dissipate heat from the cooling medium, ensuring that the temperature of each circuit equipment is always controlled within the set range.

7. The platform according to claim 5, characterized in that The calculation formula for the flow rate of the liquid supply pump is as follows: Among them, Q is the flow rate of the liquid supply pump; is the total heat to be dissipated by the system; ΔT is the temperature difference of the coolant in the heat exchanger; ρ is the density of the coolant; c p is the specific heat capacity of the coolant.

8. The platform according to claim 5, characterized in that The calculation formula for the head of the liquid supply pump is as follows: Among them, H is the total head that the liquid supply pump needs to provide; H 静 is the static head difference that the system needs to overcome; f is the Darcy pipe friction coefficient; L is the total length of the pipeline; D is the inner diameter of the pipeline; v is the average flow velocity of the fluid in the pipe; g is the acceleration due to gravity; K L is the single local loss coefficient, and ∑K L represents the sum of all local loss coefficients.

9. The platform according to claim 1, characterized in that The calculation formula for the PID control model is as follows: Among them, u(t) is the output of the PID control signal; e(t) is the error signal; K p , K i , K d are the proportional, integral, and derivative gain coefficients of the PID controller respectively; T set and T act are the set value and the actual measured value of the temperature respectively; P set and P act are the set value and the actual measured value of the pressure respectively; and are the set value and the actual measured value of the mass flow rate respectively; t and τ are time variables.

10. The platform according to claim 1, characterized in that It further includes a communication module, and the communication module is used to achieve dual control of remote monitoring by the upper computer and local operation through an Ethernet communication interface.

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