Energy management method for pulse load-oriented tandem aviation hybrid power system

Abstract

The invention discloses a pulse load-oriented tandem aviation hybrid power system energy management method, and relates to aviation power system energy management. The problems of bus voltage fluctuation, energy storage equipment overload and system efficiency reduction caused by pulse load are solved. The method is implemented on the basis of a tandem architecture comprising a turboshaft power generation system and a hybrid energy storage system, and comprises the following steps of: decomposing pulse load power into a steady-state average power component and a zero-mean pulse power component by adopting moving average filtering; the steady-state average power component is borne by the turboshaft power generation system and is stably output through the PID controller; a zero-mean pulse power component is borne by the hybrid energy storage system and is decomposed into a low-frequency component and a high-frequency component through a low-pass filter; distributing the low-frequency component to the lithium ion battery for bearing, and implementing a battery health protection strategy; and the high-frequency component is distributed to the super capacitor. Multi-energy frequency domain-time domain collaborative management is realized, bus voltage fluctuation is effectively suppressed, the system response speed is increased, the service life of energy storage equipment is prolonged, and safe and reliable operation of the system is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of energy management technology for aviation propulsion systems, and in particular to an energy management method for a series hybrid aviation power system oriented towards pulsed loads, such as laser weapons and electromagnetic bombs. Background Technology

[0002] As aerospace propulsion systems evolve towards higher energy efficiency and lower emissions, electric propulsion technology has become a core path for the development of next-generation aircraft. Compared to all-electric propulsion systems, hybrid electric propulsion systems, combining the high energy density of fuel systems with the aerodynamic advantages of electric propulsion, demonstrate significant potential in terms of range and payload capacity. Based on differences in energy flow topology, existing aerospace hybrid power systems are mainly divided into three configurations: series, parallel, and hybrid. Among them, the series architecture, by completely decoupling the prime mover and the propeller, provides unique space for aerodynamic optimization of the aircraft and has been listed as a key development direction by the European Union.

[0003] High-power laser weapons and electromagnetic bombs are of great significance for series-type hybrid electric propulsion systems in aircraft. As pulsed loads, they require high energy and high peak power. A key challenge in addressing pulsed loads is their abrupt change characteristics; the load state can change instantaneously, with a short duration but high peak power. When a pulsed load acts on an aircraft's power system, it causes a sudden, instantaneous change in the bus voltage, interfering with the normal operation of other loads on the aircraft and posing a threat to the safe and reliable operation of the system.

[0004] Current mainstream solutions for handling pulsed loads have the following limitations: Single energy storage response bottlenecks exist. While lithium-ion batteries possess high energy density, their power response speed is limited by electrochemical reactions, making it unable to track high-frequency pulse components. Supercapacitors, although possessing millisecond-level response capabilities, have insufficient energy density to support continuous pulse sequences. Traditional rule-based energy management methods do not consider pulse spectral characteristics, potentially leading to turbine generator sets being forced to overshoot due to slow dynamic response, resulting in decreased fuel efficiency, overload or deep discharge of energy storage units, accelerated aging, and reduced lifespan. Although hybrid energy storage systems are widely recognized as a solution, existing research focuses on ground vehicles and lacks frequency-time domain coordinated management methods for aviation pulsed loads. The absence of a frequency band separation model for pulse power leads to blurred boundaries between battery and supercapacitor roles, and the lack of a dynamic power coupling mechanism with the turboshaft generator system, hindering source-storage coordinated response. Therefore, there is an urgent need to develop a dedicated energy management architecture tailored to the characteristics of aviation pulsed loads. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing energy management methods for series hybrid power systems in dealing with pulse loads, such as voltage instability, energy storage overload, and efficiency degradation. This invention provides an energy management method for series hybrid power systems oriented towards pulse loads that can effectively suppress bus voltage fluctuations, improve system response speed, and extend the lifespan of energy storage devices, thereby achieving smooth pulse load handling and safe system operation.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solutions.

[0007] An energy management method for a series hybrid aviation power system oriented to pulse loads is disclosed. The system is based on a series hybrid aviation power system and includes a turboshaft generator system and a hybrid energy storage system. The turboshaft generator system consists of a turboshaft engine and a high-efficiency generator, which is connected to the DC bus through a unidirectional DC-DC converter to provide steady-state power. The hybrid energy storage system consists of a lithium-ion battery pack and a supercapacitor pack, both of which are connected to the DC bus through a bidirectional DC-DC converter to receive pulse power.

[0008] The method includes the following steps:

[0009] 1) Pulse load decomposition and basic allocation: The moving average filtering method is used to decompose the power demand of the pulse load into a steady-state average power component and a zero-mean pulse power component; the steady-state average power component is allocated to the turboshaft generator system and a stable output is maintained by a PID closed-loop controller; the zero-mean pulse power component is allocated to the hybrid energy storage system.

[0010] 2) Frequency domain decoupling and energy storage synergy: The zero-mean pulse power component is decomposed into low-frequency and high-frequency components by low-pass filtering; the low-frequency component is assigned to the lithium-ion battery and a battery health protection strategy is implemented; the high-frequency component is assigned to the supercapacitor bank.

[0011] In step 1), the window width of the moving average filter can be adaptively adjusted according to the periodic characteristics of the pulse load; preferably, the window width of the moving average filter is 1 / 2 of the pulse load period.

[0012] The PID closed-loop controller adjusts the fuel supply of the turboshaft engine in real time based on the deviation between the actual output power of the turboshaft generator system and the steady-state average power component, so as to maintain stable power output. Preferably, the parameters of the PID closed-loop controller are set as follows: the proportional coefficient Kp ranges from 2.0 to 3.0, the integral coefficient Ki ranges from 0.5 to 1.0, and the derivative coefficient Kd ranges from 0.05 to 0.2.

[0013] In step 2), the low-pass filtering method uses a first-order low-pass filter, and its filtering time constant is determined according to the dynamic response characteristics of the lithium-ion battery and the supercapacitor; preferably, the cutoff frequency of the low-pass filtering method can be 3 to 8 Hz, and the corresponding filtering time constant can be 0.5 to 1.5 s.

[0014] The battery health protection strategy includes: limiting the charging and discharging current of the lithium-ion battery, maintaining its state of charge (SOC) within a preset safe range, and monitoring the temperature. Specifically, the battery health strategy requires: maintaining the lithium-ion battery SOC in the range of 20% to 80%, a discharge rate ≤1C at -20℃ to 0℃, a discharge rate ≤2C at 0℃ to 50℃, and cutting off the charging and discharging circuit when the voltage is >4.2V or <2.7V.

[0015] The power components allocated to the lithium-ion battery and the supercapacitor are controlled by their respective bidirectional DC-DC converters. Preferably, the bidirectional DC-DC converter is controlled by a fuzzy adaptive PI controller, which adjusts its control parameters in real time according to the DC bus voltage deviation and the rate of change of the deviation.

[0016] Furthermore, the reference voltage of the DC bus can be set to 540V, and the bus voltage fluctuation can be controlled within ±5% of the rated value using this method.

[0017] The rated power of the turboshaft power generation system can be 50-100kW, and the generator efficiency is ≥92%; the cycle life of the supercapacitor bank is ≥100,000 cycles, and the response delay is <1ms.

[0018] This invention, based on a given power demand curve of a pulsed load, decomposes the pulsed load power into a steady-state average component and a zero-mean pulse component using a dynamic window moving average filtering method. The steady-state average component is handled by the turboshaft generator system and maintained with a PID controller for stable output, while the zero-mean pulse component is handled by the energy storage system and separated by a low-pass filter. The low-frequency range is handled by the lithium-ion battery, and the high-frequency range by the supercapacitor. Therefore, the energy management method for a series hybrid aero-electric propulsion system dealing with pulsed loads can be understood as follows: given the time-varying and wide-spectrum characteristics of pulsed loads, and based on the pulsed load demand curve, a three-level power flow collaborative framework of "turboshaft-battery-supercapacitor" is constructed to form a hierarchical power allocation system for the propulsion system, rationally planning the energy scheme of the hybrid electric propulsion system. This invention can reduce the impact of pulses on the propulsion system when pulsed loads such as laser weapons and electromagnetic bombs arrive, while maintaining the bus voltage within the normal range, improving the cycle life of the energy storage system, reducing pulse response delay, and increasing system efficiency.

[0019] Compared with the prior art, the advantages and outstanding technical effects of the present invention are as follows:

[0020] 1. This invention achieves frequency-time domain collaborative management of multiple energy sources, solving the response bottleneck problem of a single energy storage unit. It innovatively adopts a three-level collaborative architecture of "vortex shaft-battery-supercapacitor," using two decomposition processes—moving average filtering and low-pass filtering—to precisely allocate pulse power to the most suitable energy unit according to spectral characteristics and time scale. The turboshaft power generation system handles steady-state loads, the battery handles low-frequency pulsations, and the supercapacitor handles high-frequency spikes, fundamentally resolving the contradiction between response speed and endurance.

[0021] 2. This invention significantly improves the dynamic response speed and stability of the system, effectively suppressing bus voltage fluctuations. By allowing the millisecond-level response hybrid energy storage system to directly offset pulse disturbances and decoupling the vortex-shaft system from the pulse component, it enables the system to operate in a stable state. Experiments show that after applying this method, the bus voltage fluctuation range is significantly narrowed from ±12.7% to ±3.9% (relative to a 540V reference), a reduction of approximately 70.1%, greatly improving power supply quality and system safety and reliability.

[0022] 3. This invention optimizes the operating mode of the energy storage unit, extending the service life of key equipment. By frequency domain decoupling, this invention avoids the battery dealing with high-frequency pulse currents, allowing it to operate in a low-frequency band with gentler charge and discharge levels. Combined with battery health management strategies (such as current limiting and SOC window management), it significantly reduces the battery's electrochemical and thermal stress, thereby effectively extending its cycle life. Simultaneously, it leverages the long cycle life advantage of supercapacitors, improving the overall economics of the energy storage system. This is of great significance for the safe, reliable, and economical operation of series-connected hybrid electric propulsion systems in aviation. Attached Figure Description

[0023] Figure 1 A flowchart of the energy management method provided by the present invention;

[0024] Figure 2 This is a schematic diagram of the application objects in an embodiment of the present invention;

[0025] Figure 3 This is a diagram showing the application results of the energy management method according to an embodiment of the present invention. Detailed Implementation

[0026] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0027] The embodiments of the present invention include the following steps, as shown in the flowchart below. Figure 1 As shown:

[0028] 1) Pulse load decomposition and basic allocation:

[0029] 1.1) Real-time acquisition of pulse load power P_Load. The pulse load demand power signal is smoothed by using a moving average filtering method, and the power signal is decomposed into two parts: the average power component P_avg and the pulse power component P_pulse. The steady-state average power component reflects the long-term stable trend of the load, while the zero-mean pulse power component represents the short-term rapid fluctuation of the load.

[0030] 1.2) Turboshaft generator systems are suitable for providing continuous and stable power output. While they possess higher energy density, their dynamic response is relatively poor, exhibiting a relatively slow response to rapid load fluctuations. Therefore, the steady-state average power component P_avg is allocated to the turboshaft generator system, and its output is adjusted using a PID closed-loop controller to maintain power stability. The PID closed-loop controller automatically adjusts the control input of the generator system based on the output power error, further improving output stability.

[0031] 1.3) The hybrid energy storage system can respond quickly to load fluctuations. Therefore, the zero-mean pulse power component P_pulse is entirely allocated to the hybrid energy storage system to buffer rapid power changes in the load. The hybrid energy storage system can quickly absorb or release power pulsations, effectively suppressing the impact of rapid load changes on the system.

[0032] 2) Frequency domain decoupling and energy storage synergy:

[0033] 2.1) The pulse power components are processed by low-pass filtering to decompose them into a low-frequency component P_bat and a high-frequency component P_SC. The low-frequency component corresponds to slowly changing power demand, while the high-frequency component corresponds to rapid power fluctuations.

[0034] 2.2) In hybrid energy storage systems, lithium-ion batteries have high energy density, low power density, and limited cycle life. Therefore, allocating low-frequency components to lithium-ion batteries and monitoring and managing them through the implementation of battery health protection strategies can extend battery life.

[0035] 2.3) Supercapacitor banks are characterized by low energy density, high power density, and long cycle life. Therefore, high-frequency components are allocated to supercapacitor banks to meet the power demands of rapid response. The rapid charging and discharging characteristics of supercapacitor banks can effectively absorb or release high-frequency power fluctuations, further enhancing the adaptability of the energy storage system to load fluctuations.

[0036] The following example uses a series hybrid aviation system as an application case, specifically including a turboshaft generator system and a hybrid energy storage system. The turboshaft generator system consists of a turboshaft engine and a high-efficiency generator, while the hybrid energy storage system comprises lithium-ion batteries and a supercapacitor bank, connected to a DC bus via a bidirectional DC-DC converter. The bus reference voltage is 540V. Figure 2 As shown.

[0037] This implementation method includes the following steps:

[0038] 1) Decomposition of pulse load and basic energy distribution

[0039] 1.1) When the power system is running stably under normal load, a load demand power signal with obvious pulse characteristics is input. The peak power of this pulsed load is 30kW, the pulse period is 1s, and the duty cycle is 50%. The moving average filtering method is used to process it, effectively decomposing the original load power signal into two parts: a steady-state average power component and a zero-mean pulse power component. The steady-state average power component obtained after decomposition is 15kW, and the remaining part is the zero-mean pulse power component.

[0040] 1.2) Based on the above decomposition results, considering that the turboshaft generator system has a high energy density and is suitable for stable and continuous power output, the 15kW steady-state average power component obtained from the decomposition is allocated to the turboshaft generator system output. The steady-state output power of this system before the pulse load is connected is 25kW, which is sufficient to handle the allocated power. To ensure stable and reliable output power, a PID closed-loop controller is used to dynamically adjust the turboshaft generator system to achieve stable control of the average power output.

[0041] 1.3) The zero-mean pulse power component is fully distributed to the hybrid energy storage system to meet the rapid response requirements of the load during short-term high power fluctuations, thereby reducing the dynamic impact on the main power supply.

[0042] 2) Frequency domain decoupling and coordinated scheduling of energy storage systems

[0043] 2.1) Frequency domain decoupling is performed on the zero-mean pulse power component. A low-pass filter is used to separate the pulse component by frequency. A low-pass filter with a time constant of 0.8s is used to divide the pulse power component into low-frequency and high-frequency components. The low-frequency component represents relatively slow power fluctuations, while the high-frequency component corresponds to abrupt power changes.

[0044] 2.2) Given that lithium-ion batteries have high energy density, relatively low power density, and limited cycle life, they are suitable for undertaking stable low-frequency energy output tasks. In this embodiment, the lithium-ion battery pack has a rated voltage of 380V and a rated capacity of 24Ah. The aforementioned low-frequency components are distributed to this lithium-ion battery module, and a fuzzy adaptive PI controller with a bidirectional DC-DC converter is used. The PI control parameters are adaptively adjusted according to the target voltage error and its derivative. The input variable error e and its derivative de, as well as the output variable proportional gain change delta_KP and integral gain change delta_KI, are all divided into seven fuzzy subsets {NB, NM, NS, Z, PS, PM, PB}, representing negative large, negative medium, negative small, zero, positive small, positive medium, and positive large, respectively. The parameter change rule table is shown in Table 1. For example, if the error e is NB and the error derivative de is NB, then the proportional-integral change is PB and the integral gain change is NB. A total of 7×7=49 fuzzy logic control rules were designed to improve dynamic response performance. Combined with the battery health protection mechanism, the battery state of charge is maintained in the range of 20% to 80% to avoid overcharging and over-discharging, thereby reducing its electrochemical loss and extending its service life.

[0045] Table 1

[0046]

[0047] 2.3) Due to its high power density, low energy density, and excellent charge-discharge cycle performance, the supercapacitor module is suitable for handling high-frequency and rapidly changing power demands. In this embodiment, the supercapacitor bank has a rated voltage of 650V and a capacity of 3F. The high-frequency components mentioned above are distributed to the supercapacitor module for processing. Similarly, an adaptive fuzzy PI controller is used to control the bidirectional DC-DC converter. The fuzzy rules are the same as those used in the fuzzy adaptive PI controller of the lithium-ion battery pack mentioned above, so as to realize the steady-state support of the system and the rapid response to high dynamic loads.

[0048] The effects of applying the energy management strategy proposed in this invention are as follows: Figure 3 As shown. Before 10 seconds, the energy management strategy uses only the power battery to maintain the bus voltage stability, with the turboshaft generator system and supercapacitor not involved. After 10 seconds, it switches to the energy management method proposed in this invention. It can be seen that, compared with the traditional energy management strategy, the fluctuation range of the power system bus voltage under the energy management strategy proposed in this invention is reduced from 474–611V to 520–561V, a reduction of 70.1%, and is less than the error band of the bus reference voltage of 540V ± 5%, meeting the requirements for the safety and reliability of the power system operation.

[0049] In summary, this invention addresses the problems of severe bus voltage fluctuations, insufficient response capability of single energy storage units, and equipment overload and efficiency degradation caused by traditional energy management methods in series-type aero-hydro hybrid power systems when dealing with pulsed loads such as laser weapons and electromagnetic bombs. It proposes a hierarchical-frequency domain coordinated energy management method. This method first decomposes the pulsed load power into a steady-state average component and a zero-average pulse component using a moving average filter. The average component is handled by a turboshaft generator system with slow dynamic response but high energy density, and stable output is maintained through PID control. The pulse component is handled by a hybrid energy storage system, and further separated into low-frequency and high-frequency components through a low-pass filter. The low-frequency component is allocated to a high-energy-density lithium battery, while the high-frequency component is handled by a fast-response supercapacitor, combined with battery health protection and a fuzzy adaptive PI control strategy. This scheme clarifies the division of labor among the three power flow stages of "turboshaft-battery-supercapacitor" and establishes a dynamic coupling mechanism, successfully suppressing bus voltage fluctuations within ±5% of the rated value. Compared with the traditional energy management strategy that only uses power batteries to maintain bus voltage stability, the fluctuation range of the bus voltage of the series aviation hybrid power system is reduced from 474-611V to 520-561V, a reduction of 70.1%, significantly improving system stability, energy storage life and pulse response efficiency.

[0050] This invention proposes a hierarchical-frequency domain decoupled energy management strategy suitable for series aviation hybrid power systems. It deconstructs and dynamically matches the pulse load signal, and implements a multi-level energy distribution and controller adjustment mechanism based on the performance differences of each component. This ensures system stability while significantly improving energy utilization efficiency and power response capability, and has good engineering application prospects.

[0051] The above embodiments are merely preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. An energy management method for a series hybrid aviation power system oriented to pulsed loads, wherein the series hybrid aviation power system includes a turboshaft generator system and a hybrid energy storage system, the turboshaft generator system being connected to a DC bus via a unidirectional DC-DC converter, and the hybrid energy storage system consisting of a lithium-ion battery pack and a supercapacitor pack being connected to the DC bus via a bidirectional DC-DC converter, characterized in that, The method includes the following steps: 1) Pulse load decomposition and basic allocation steps: The pulse load demand power is decomposed into steady-state average power component and zero-mean pulse power component using the moving average filtering method; the steady-state average power component is allocated to the turboshaft generator system and its stable output is maintained by a PID closed-loop controller; the zero-mean pulse power component is allocated to the hybrid energy storage system. 2) Frequency domain decoupling and energy storage synergy steps: The zero-mean pulse power component is decomposed into low-frequency and high-frequency components by low-pass filtering; the low-frequency component is assigned to the lithium-ion battery pack and a battery health protection strategy is implemented; the high-frequency component is assigned to the supercapacitor pack.

2. The energy management method for a series hybrid power system for pulsed loads as described in claim 1, characterized in that... In step 1), the window width of the moving average filter is adaptively adjusted according to the periodic characteristics of the pulse load.

3. The energy management method for a series hybrid power system for pulsed loads as described in claim 2, characterized in that... The window width of the moving average filter is set to 1 / 2 of the pulse load period.

4. The energy management method for a series hybrid power system for pulsed loads as described in claim 1, characterized in that... In step 1), the parameters of the PID closed-loop controller are set as follows: the proportional coefficient Kp ranges from 2.0 to 3.0, the integral coefficient Ki ranges from 0.5 to 1.0, and the derivative coefficient Kd ranges from 0.05 to 0.

2.

5. The energy management method for a series hybrid power system for pulsed loads as described in claim 1, characterized in that... In step 2), the low-pass filtering method uses a first-order low-pass filter, whose filtering time constant is determined based on the dynamic response characteristics of lithium-ion batteries and supercapacitors.

6. The energy management method for a series hybrid aviation power system oriented towards pulsed loads as described in claim 5, characterized in that... The cutoff frequency of the low-pass filtering method is 3 to 8 Hz, and the corresponding filtering time constant ranges from 0.5 to 1.5 s.

7. The energy management method for a series hybrid power system for pulsed loads as described in claim 1, characterized in that... In step 2), the battery health protection strategy includes: limiting the charging and discharging current of the lithium-ion battery, maintaining its state of charge (SOC) within a preset safe range, and monitoring the temperature. Specifically, the battery health protection strategy requires: maintaining the lithium-ion battery SOC in the range of 20% to 80%, discharging rate ≤1C at -20℃ to 0℃, discharging rate ≤2C at 0℃ to 50℃, and cutting off the charging and discharging circuit when the voltage is >4.2V or <2.7V.

8. The energy management method for a series hybrid power system for pulsed loads as described in claim 1, characterized in that... In step 2), the power components allocated to the lithium-ion battery and the supercapacitor are controlled by their respective bidirectional DC-DC converters. The bidirectional DC-DC converters are controlled by a fuzzy adaptive PI controller, which adjusts its control parameters in real time according to the DC bus voltage deviation and the rate of change of the deviation.

9. The energy management method for a series hybrid power system for pulsed loads as described in any one of claims 1 to 8, characterized in that... The reference voltage of the DC bus is 540V, and the bus voltage fluctuation is maintained within ±5% of the rated value by the method described.

10. The energy management method for a series hybrid power system for pulsed loads as described in any one of claims 1 to 8, characterized in that... The rated power of the turboshaft generator system is 50-100kW, and the generator efficiency is ≥92%; the cycle life of the supercapacitor bank is ≥100,000 cycles, and the response delay is <1ms.

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