Method for controlling hybrid energy storage system of more-electric aircraft based on negative impedance compensation

Abstract

The invention provides a control method for a hybrid energy storage system of a more-electric aircraft based on negative impedance compensation, which belongs to the technical field of aviation electrical engineering, and comprises the following steps: introducing a negative impedance compensation mechanism, and building a second-order feed-forward differentiating circuit model of the hybrid energy storage system with enhanced compensation resistance; based on a dynamic matching load current change rate and a power grid impedance structure, self-adaption of compensation impedance and an integrator upper limit are analyzed and designed, and power distribution is optimized; and designing a hybrid energy storage system control structure based on a second-order feed-forward differential architecture and negative impedance compensation control. The problems of dynamic response lagging and unreasonable power distribution in a traditional hybrid energy storage control method are solved, the output impedance of the direct current source-hybrid energy storage integrated system is changed, collaborative power level-control strategy integration is realized, the voltage recovery performance of the system is improved, the stability and response capability of the system are enhanced, and the system reliability is improved. Reasonable optimization is carried out on frequency domain distribution, and the method is widely applied to scenes needing high-dynamic power compensation management.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aviation electrical engineering, and particularly relates to a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation. BACKGROUND

[0002] The core technical bottleneck of the traditional multi-electric aircraft power architecture is that the power supply system needs to meet the dual requirements of high power density and high energy density. Due to the significant peak-to-average power ratio difference of aircraft loads, a single energy storage technology cannot meet both transient response capability and continuous power supply requirements. Although the existing hybrid energy storage system composed of supercapacitors and lithium ion batteries can theoretically solve this contradiction, there are the following key technical defects in actual application:

[0003] Control architecture mismatch: there is a structural mismatch between the control layer and the power stage of the existing hybrid energy storage system, which causes the power distribution strategy to be unable to achieve optimization. Especially under dynamic load conditions, the direct current power supply and the energy storage component present time-varying impedance characteristics, and the traditional control method fails to establish an effective coordination mechanism.

[0004] Energy conduction defects: in the conventional filter frequency control strategy, the current reference signal of the hybrid energy storage system only comes from the direct current bus voltage loop, completely ignoring the dynamic influence of the generator branch. This control blind area will cause the transient residual energy to conduct reversely to the generator system, causing serious consequences including: bus voltage sag, accelerated deterioration of mechanical components bearings, system cascading failure, etc.

[0005] Adaptive control deficiency: existing solutions such as virtual impedance method and improved droop control have been applied in direct current microgrids, but are limited by the special constraints of aviation power systems: generator regulation strictly prohibits changing the original motor speed, power impedance characteristics are strictly limited by aviation specifications, and transient response requirements are much higher than ground systems.

[0006] In particular, the aviation power system prohibits the use of the virtual impedance reshaping method in traditional microgrids, as it may affect the original motor control characteristics of the generator set. This limitation makes it impossible to directly transplant the control strategies of existing ground microgrids to the aviation field.

[0007] Therefore, it is urgent to develop a new power-independent control framework that should have the following characteristics: system stability is achieved only through impedance reconstruction on the energy storage side, the original control characteristics of the generator set are completely maintained, adaptive power distribution of hybrid energy storage units is achieved, and reverse conduction of transient energy to the power generation system is effectively blocked. This technical gap has become a key bottleneck restricting the performance improvement of multi-electric aircraft hybrid energy storage systems, and is the core technical problem that the application focuses on solving. SUMMARY

[0008] According to the first aspect of the present application, the present application claims to protect a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation, characterized in that the multi-electric aircraft hybrid energy storage system comprises:

[0009] The high-voltage DC generator is connected with the 270V DC bus through a filter capacitor.

[0010] The hybrid energy storage unit is composed of lithium batteries and supercapacitors, and both are connected with the 270V DC bus through independently configured bidirectional DC-DC converters.

[0011] The pulse power load is directly connected in parallel with the 270V DC bus.

[0012] Further, the following core control architecture is further included:

[0013] The negative impedance compensation mechanism is integrated in the generator, lithium battery and supercapacitor control loop;

[0014] A hybrid energy storage system second-order feedforward differential circuit model enhanced by compensation resistance is constructed;

[0015] The adaptive compensation parameters are designed based on dynamic matching of load current change rate and grid impedance structure.

[0016] Further, the following is further included:

[0017] Step 1: Introduce the negative impedance compensation mechanism in the generator, lithium battery and supercapacitor control loop, and build a hybrid energy storage system second-order feedforward differential circuit model enhanced by compensation resistance;

[0018] Step 2: Based on dynamic matching of load current change rate and grid impedance structure, analyze and design adaptive compensation impedance and integrator upper limit, and optimize power distribution of the generator, lithium battery and supercapacitor;

[0019] Step 3: Design the control structure of the hybrid energy storage system based on the second-order feedforward differential architecture and negative impedance compensation control.

[0020] Further, the step 1 further includes:

[0021] The negative impedance compensation mechanism reduces the output impedance of the equivalent input power supply system, and makes the system dynamic power compensation ability increase by 20%-40% for pulse load conditions with current change rate exceeding 100A / ms.

[0022] Further, the step 1 includes:

[0023] The power distribution of the hybrid energy storage system is based on a three-frequency-band frequency division, in which the low-frequency component is allocated to the generator, the medium-frequency component is allocated to the lithium battery, the high-frequency component is allocated to the super capacitor, and the coordinated control is performed through an improved second-order feedforward differential filter frequency division architecture.

[0024] The negative impedance compensation mechanism reduces the output impedance of the equivalent input power supply system and enhances the dynamic power compensation capability of the high-current change rate load.

[0025] The low-frequency component is 0.01-0.1 Hz, the medium-frequency component is 0.1-10 Hz, and the high-frequency component is >10 Hz.

[0026] Further, the step 2 comprises:

[0027] The negative impedance compensation mechanism introduces an adaptive compensation resistance R com , which dynamically adjusts according to the change rate and instantaneous value of the load current, and performs voltage recovery.

[0028] The adaptive compensation resistance R com uses an integral upper limit constraint to maintain the stability of the hybrid energy storage system and prevent system instability caused by excessive negative impedance.

[0029] Further, the adaptive compensation parameter design comprises:

[0030] The dynamic adjustable compensation resistance R com has a resistance range of -0.5Ω to -2.5Ω.

[0031] The real-time updated integral upper limit constraint condition is expressed as:

[0032] |Rcom|≤K·(di / dt)max

[0033] Where K is the system stability coefficient, and (di / dt)max is the maximum allowed current change rate.

[0034] Further, the adjustment process of the compensation resistance R com comprises:

[0035] The DC bus voltage fluctuation ΔV is monitored in real time by a high-speed sampling circuit.

[0036] When ΔV exceeds the threshold value, the fast response mode of negative impedance compensation is started.

[0037] The compensation strength of R com is adjusted according to the voltage deviation level.

[0038] Further, the second-order feedforward differential circuit model comprises:

[0039] The parallelly connected differential compensation branch and the inertial delay branch;

[0040] The RC network with adjustable time constant, and the time constant is set to 0.1ms-10ms adjustable range;

[0041] The load current change rate detection precision reaches ±5A / μs.

[0042] Further, the dynamic stability guarantee measure is further included:

[0043] The priority response channel is set in the super capacitor control loop;

[0044] When di / dt>50A / ms is detected, the response delay of the super capacitor is controlled within 100μs;

[0045] The lithium battery loop is provided with a 5ms smoothing filter link.

[0046] Further, the control strategy of the bidirectional DC-DC converter comprises:

[0047] The generator side converter adopts double-loop control of voltage outer loop + current inner loop;

[0048] The energy storage unit side converter adopts an improved droop control based on negative impedance compensation;

[0049] The high-frequency communication synchronization mechanism above 10kHz is set between the converters.

[0050] Further, the system protection method is further included:

[0051] The emergency exit condition of negative impedance compensation is set: when the oscillation signal lasting more than 10ms is detected, the traditional PID control is automatically switched;

[0052] The multi-stage TVS protection device is configured at the DC bus;

[0053] When the super capacitor SOC is lower than 20%, the deep discharge compensation is prohibited.

[0054] Compared with the prior art, the above technical scheme has the following technical effects:

[0055] The impedance of the generator and the hybrid energy storage system is combined to realize more reasonable power distribution between the lithium battery and the super capacitor, solve the problems of dynamic response lag and unreasonable power distribution in the traditional hybrid energy storage control method, fundamentally change the output impedance of the DC source-hybrid energy storage integrated system, realize the integration of collaborative power level-control strategy, significantly improve the voltage recovery performance of the system, and enhance the stability and response ability of the system.

[0056] The DC bus voltage fast recovery control based on negative impedance compensation is introduced, which optimizes the dynamic power compensation capability of high current rate load by reducing the output impedance of equivalent input power system.

[0057] The transient negative impedance is adapted to different load current rates, and different load power requirements are better met. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 A multi-electric aircraft power supply system schematic diagram with a hybrid energy storage system of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0059] Figure 2 A two-order feedforward differential filter frequency division circuit model diagram of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0060] Figure 3 Detailed bus voltage change diagrams under different negative impedance compensation resistances of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation are provided for the embodiments of the application.

[0061] Figure 4 DC bus voltage behavior diagrams with or without adaptive negative impedance compensation resistance of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation are provided for the embodiments of the application.

[0062] Figure 5 A two-order feedforward differential filter frequency division control structure diagram of a hybrid energy storage system based on negative impedance compensation of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0063] Figure 6 A DC bus voltage simulation result diagram of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0064] Figure 7 A system current simulation result diagram of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0065] Figure 8 A transient response time diagram of DC bus voltage under different Rref of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application.

[0066] Figure 9 A comparison result diagram of bus voltage recovery time under the control of the application and the traditional control of a multi-electric aircraft hybrid energy storage system control method based on negative impedance compensation is provided for the embodiments of the application. Detailed Implementation

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are included within the scope of protection of this application.

[0068] The terms "first," "second," and "third" in this application are used for descriptive purposes only and should not be construed as representing or implying relative importance or implicitly indicating the number of technical features represented. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional representations (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and motion state between components in a specific posture (as shown in the figures). If the specific posture changes, the directional representation also changes accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0069] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0070] According to the first embodiment of the present invention, referring to Figure 1 This invention claims protection for a control method for a hybrid energy storage system for multi-electric aircraft based on negative impedance compensation. The hybrid energy storage system for multi-electric aircraft includes a high-voltage DC generator, a hybrid energy storage unit, and a pulsed power load. The high-voltage DC generator is connected to a 270V DC bus via a filter capacitor. The hybrid energy storage unit consists of a lithium battery and a supercapacitor. The lithium battery and the supercapacitor are respectively connected to the 270V DC bus via corresponding bidirectional DC-DC converters. The pulsed power load is directly connected to the 270V DC bus.

[0071] Further, the method further comprises:

[0072] Step 1: Introducing a negative impedance compensation mechanism in the generator, lithium battery, and supercapacitor control loop, and building a second-order feedforward differential circuit model of the hybrid energy storage system with enhanced compensation resistance;

[0073] Step 2: Based on the dynamic matching of the load current change rate and the grid impedance structure, analyzing and designing the adaptive compensation resistance and the integrator upper limit, and optimizing the power distribution of the generator, lithium battery, and supercapacitor;

[0074] Step 3: Designing the control structure of the hybrid energy storage system based on the second-order feedforward differential architecture and the negative impedance compensation control.

[0075] Further, the step 1 comprises:

[0076] The power distribution of the hybrid energy storage system is based on three-frequency band frequency division, wherein the low-frequency component is allocated to the generator, the medium-frequency component is allocated to the lithium battery, and the high-frequency component is allocated to the supercapacitor, and coordinated control is performed through the improved second-order feedforward differential filter frequency division architecture;

[0077] The negative impedance compensation mechanism reduces the output impedance of the equivalent input power supply system and enhances the dynamic power compensation capability of high current change rate loads;

[0078] The low-frequency component is 0.01-0.1 Hz, the medium-frequency component is 0.1-10 Hz, and the high-frequency component is >10 Hz.

[0079] Further, the step 2 comprises:

[0080] The negative impedance compensation mechanism introduces an adaptive compensation resistance Rcom, which is dynamically adjusted according to the change rate and instantaneous value of the load current, and performs voltage recovery;

[0081] The adaptive compensation resistance Rcom adopts an integral upper limit constraint to maintain the stability of the hybrid energy storage system and prevent system instability caused by excessive negative impedance.

[0082] Further, the step 3 comprises,

[0083] A high-pass filter is used to extract the load current change rate;

[0084] An integrator is used to generate a compensation signal;

[0085] An adaptive compensation resistance Rcom adjusts the DC bus voltage;

[0086] A PI controller is used for closed-loop control of the current reference;

[0087] The adaptive compensation resistance adjusting module is used for adjusting the compensation resistance value according to the load current rate of change and the instantaneous value of the adaptive compensation resistance Rcom, so as to optimize the dynamic response and stability of the hybrid energy storage system; the control strategy is used to extract the load current rate of change through the high-pass filter, and the compensation signal is generated through the integral operation, and the compensation signal is controlled through the adaptive compensation resistance Rcom which is adjusted adaptively, so as to optimize the dynamic response of the DC bus voltage and avoid over-compensation or under-compensation.

[0088] As Figure 2 The two-order feedforward differential filter frequency division circuit model diagram of the hybrid energy storage system multi-electric aircraft power supply system based on negative impedance compensation resistance provided by the application is shown, and the load current distribution under different branches is as follows:

[0089]

[0090] Where V ref is the equivalent DC reference voltage of the generator, the lithium battery converter output and the super capacitor converter output. V out is the load voltage. L s is defined as the equivalent inductance of the generator, R S is defined as the equivalent resistance of the generator, R bat is defined as the equivalent resistance of the system based on the lithium battery converter, i bat is the lithium battery output current, C sc is the output impedance of the system based on the super capacitor converter, and s is the complex frequency in Laplace transform. i s , i hbat and i hsc represent the output currents of the generator, the lithium battery converter and the super capacitor converter respectively. Figure 2 It is also guided that:

[0091] io=is+ihbat+ihsc(2)

[0092] Where i o is the load current. Therefore, in order to consider the impedance of the microgrid system, the branch currents from the generator and the HESS can be given by the following formula:

[0093]

[0094] Where Δ` is defined as follows:

[0095]

[0096] Where Z`eq represents the modified output impedance of the DC microgrid in the multi-electric aircraft system. It can be seen that R com is the adaptive compensation resistance value, and R comThe value of R changes the equivalent output impedance Z`eq, thus the dynamic performance of the multi-electric aircraft DC microgrid can be optimized.

[0097] Equation (3) shows that the introduction of compensation resistance R com After that, the system significantly reduces the demand for DC components of the power output current after the load current transient, and instead relies on the lithium battery branch to provide DC component power support to enhance the dynamic performance. In fact, the recommended state is that during the load step change, the transient current demand is fully supported by the hybrid energy storage system output, while the DC source output current remains close to constant to ensure the anti-interference of the DC bus voltage.

[0098] In addition, the distribution result in (3) optimizes the two-order FFD characteristics by adjusting the corner frequency and the damping coefficient, thereby further enhancing the adaptability to the load current change. From a theoretical point of view, another form of (4) can be organized as:

[0099]

[0100] where the modified damping coefficient ξ' and the corner frequency ω n1 is defined as:

[0101]

[0102]

[0103] As can be seen from the modified two-order filter characteristic equation in (6), the addition of R com reduces the system damping coefficient and increases the filter corner frequency. Through this operation, the super capacitor branch can respond faster to high-frequency power fluctuations, while the lithium battery branch can more sensitively track low-frequency power. Therefore, the improved dynamic response capability of the hybrid energy storage system to the DC microgrid can be significantly improved.

[0104] Assuming R com = 0, the equivalent resistance R bat and the equivalent capacitance C sc of the lithium battery can be calculated by:

[0105]

[0106] From (8), it is concluded that:

[0107]

[0108] The equivalent inductance L s and the equivalent resistance R sThis is typically determined using traditional parameter identification methods. Meanwhile, to ensure precise distribution of pulsating load power between the power source and the hybrid energy storage system according to predetermined requirements, and considering the transient performance (including dynamic response and overshoot) of the supercapacitor branch, the cutoff frequency and damping coefficient of the second-order filter can be designed as follows:

[0109]

[0110] Among them, f sc This is the mid-frequency boundary of the multi-electric aircraft-hybrid energy storage system, and based on relevant engineering cases, it is designed as f in this invention. sc =0.1Hz. Based on this, the parameters in formula (3) can be obtained.

[0111] like Figures 3-4 The figure shown is a correlation diagram of DC bus voltage variation under different negative impedance compensation resistors. Figure 4 This demonstrates the effect of DC bus voltage on R. com The significant dependence of the compensation state shows that the transient voltage trajectory is affected by R. com Sensitivity to change, and confirmed the optimal R com The choice of resistor is crucial for voltage stability performance. For analytical purposes, consider a pulsed load scenario with a given rise time. The negative resistance compensation design is constructed in two distinct phases consistent with the pulse waveform characteristics: a rising edge compensation phase and a falling edge compensation phase. The rising edge phase addresses two cases: boost transient design and pulsed load steady-state peak design. Similarly, the falling edge phase handles buck transients and post-pulse stability. Crucially, when both the rising and falling edges use R... com At that time, the steady-state power stage compensation parameters remain consistent. This fundamentally positions the transient power step compensation design as R com Key elements of optimization.

[0112] Figure 4 It provides the dynamic response characteristics of DC bus voltage taking into account the rate of change of load current. Figure 4 The red curve in the figure indicates the use of a compensation resistor R during the load step interval. com A solution for the step adjustment strategy. Figure 4 The blue curve shows the compensation resistor R within the load step range. com A solution that adapts in real time to the rate of change of load current. The conclusion is that during load step intervals, the discontinuous R... com This can cause adverse supertransient oscillations on the DC bus. This is mainly because during the initial load change, R... com It has already been embedded in the control system. However, at the same time, the load current is at... Figure 4 The time intervals [t0, t1] and [t2, t3] in the equation cause the control system to be equivalent to R.com The overcompensated state. Figure 4 The phenomenon can also be described from the perspective of impedance, i.e., R. com Discontinuous compensation leads to unexpected transient changes in the DC bus voltage. Therefore, it is crucial to design a continuous impedance compensation method during [t0, t1] and [t2, t3]. Based on the above analysis, this invention introduces R by considering the rate of change of the load current. com In adaptive design, the rate of change of load current can be summarized by the following rules:

[0113]

[0114] Where, ω s It is the cutoff frequency of the rate of change function, k i (i = 1, 2) are defined as correction coefficients for the boost and depressurization processes, respectively, R ref Defined as Figure 5 The reference value at [t1, t2]. In equation (12), k i This represents the proportional relationship between the rate of change of the load current and the transient compensation resistance required. By adjusting the value of ki, the transient time of the compensation resistance can be changed, which typically needs to correspond to the duration of the transient change in the load current. As for the parameter ω... s Adjust ω s The value of ω can modify the recovery time of the DC bus voltage within a specific range. It should be noted that exceeding the optimal ω... s Setting the threshold value too high can lead to harmful voltage overshoot. Typically, ω is set to a value that is too high. s = 2 * pi * 5 rad / s. Meanwhile, R com The changes in value during [t0, t1] and [t2, t3] should satisfy the following formula:

[0115]

[0116] Therefore, by combining formulas (12) and (13), the required resistance value R can be obtained. com Negative impedance compensation can improve the dynamic response speed of DC bus voltage under pulsed loads, but its capacitive characteristics may couple with the inductive impedance of the power grid, generating negatively damped (ζ`<0) oscillations in the low and medium frequency bands. Therefore, when constructing R... com At that time, an upper limit is applied by the integral in equation (7), and the cumulative velocity negative resistance R com It can be constrained to keep the equivalent damping coefficient ζ`>0, which results in:

[0117]

[0118] Therefore, in implementing R through an integrator comIn this case, we can refer to inequality (14) to design the upper limit of the integrator to prevent R from being too large. com An excessively large damping coefficient can lead to unnecessary stability problems. This method maintains a positive damping coefficient while simultaneously enhancing the transient response and ensuring the stability of the global system.

[0119] like Figure 5 The diagram shows the structure of the hybrid energy storage system provided by this invention: a second-order feedforward differential filter frequency division control based on negative impedance compensation. The structure of the adaptive compensation resistor is represented by a red dashed box. First, the rate of change of the load current is extracted using a high-pass filter, then its negative value is taken and integrated. The integrator performs a clearing operation triggered by a rising edge to prevent R from being cleared. com Continues to increase. Subsequently, compensation component I... o ·R com Used to correct the voltage outer loop error, and a total current reference i is obtained through a PI controller to better meet actual requirements. tot Refer to equation (3), where i tot The operation is equivalent to i o i tot A corresponding current reference is assigned to obtain the current for the supercapacitor and lithium battery converter, which is used as the input setpoint value for the different current inner loops for closed-loop control. This mechanism effectively mitigates transient voltage deviations; for example, when encountering pulsed load conditions, the system counteracts the bus voltage drop caused by sudden current surges through precisely calculated reverse transient voltage adjustments.

[0120] like Figures 6-9 The figure shown is a simulation result diagram provided by the present invention, wherein from left to right... Figures 6-7 (a~e)R ref They are: R ref =0ω;R ref =-0.015ω; R ref = -0.025ω; R ref = -0.035ω; R ref = -0.045ω. Simulation results were performed in MATLAB / Simulink to evaluate the overall performance of the control strategy. The simulation framework follows... Figure 1 The architecture shown uses control logic through... Figure 5 The compensation strategy detailed in the paper is implemented. An aerospace-grade 270V DC bus system is simulated as a permanent magnet synchronous generator (PMSG) with passive rectification. To rigorously evaluate transient voltage regulation, this invention applies a pulsed load to the main DC power supply and the hybrid energy storage system.

[0121] To evaluate different compensation resistors R com The impact on the performance of hybrid energy storage systems, using different R comComparative simulations were performed, focusing on the DC bus voltage dynamic recovery characteristics, as shown in Figure 6 For the baseline reference, Figure 6 (a) gives the uncompensated case, showing a significant transient voltage deviation. Subsequent analysis of the compensated cases in Figure 6 (b)-(e) shows that different values of R com significantly affect the bus voltage dynamics. Within the optimal operating boundary, an increase in R com enhances the DC bus voltage responsiveness, as evidenced by the improved transient recovery curves. However, excessive R com values cause over-compensation effects, indicating the need for precise parameter optimization. As exemplified in Figure 6 (c), the optimally tuned compensation scheme, compared to the uncompensated case in Figure 6 (a), embodies superior DC bus voltage regulation.

[0122] Figure 7 The simulation results shown in Figure 7 are also performed for the system currents, including the source current, hybrid energy storage system current, and load current. The results show that the load demand is collectively met through coordinated current contributions from the hybrid energy storage system and the DC source. The current sharing ratio between the DC source and the hybrid energy storage system exhibits significant dependence on the compensation resistance value. Within the optimal operating boundary, an increase in R com enhances the role of the hybrid energy storage system during transient changes, effectively compensating for the inherent response limitations of the main power source. However, excessive R com values disadvantageously reduce the steady-state current contribution in the DC source, imposing additional energy losses on the hybrid energy storage system. Therefore, this phenomenon emphasizes the critical importance of optimizing R com in the design of multi-electric aircraft power systems. At the same time, Figure 7 the simulation conclusions in Figure 7 also confirm that, in order to ensure high dynamic recovery characteristics of the DC bus voltage, the HESS needs to output all the sudden-on currents required by the load changes, and then the DC source outputs the current basically unchanged.

[0123] Figure 8 The transient response time of the DC bus voltage under different R com compensation values is quantitatively analyzed in com , which shows that optimizing the R com parameterization can significantly improve the voltage dynamic characteristics and greatly shorten the transient response time.

[0124] To verify the control strategy of the proposed adaptive compensation mechanism, multiple test scenarios with different power pulse loads were studied. Figure 9The DC bus voltage deviation load conditions between the traditional method and the proposed method under continuous 30kW and 40kW pulse are compared. The comparative analysis shows that the adaptive negative impedance compensation strategy realizes excellent voltage regulation while optimizing the transient recovery characteristics.

[0125] As can be seen from the drawings and embodiments, the application combines the impedances of the generator and the hybrid energy storage system to achieve a more reasonable power distribution between lithium batteries and supercapacitors, solves the problems of dynamic response lag and unreasonable power distribution in the traditional hybrid energy storage control method, fundamentally changes the output impedance of the DC source-hybrid energy storage integrated system, realizes the integration of the collaborative power level-control strategy, significantly improves the voltage recovery performance of the system, and enhances the stability and response capability of the system. In addition, the DC bus voltage fast recovery control based on negative impedance compensation is introduced. This method optimizes the dynamic power compensation capability of the high current change rate load by reducing the output impedance of the equivalent input power supply system. The design also makes the transient negative impedance adapt to different load current change rates, better meeting different load power requirements.

[0126] In several embodiments provided in the present application, it should be understood that the disclosed systems, systems and methods can be implemented in other ways. For example, the above-described system embodiments are only illustrative, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or data sharing between the presented or discussed systems or units can be indirect coupling or data sharing through some interfaces, systems or units, which can be electrical, mechanical or other forms.

[0127] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The above integrated unit can be realized in the form of hardware or in the form of software functional unit. The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the contents of the present application specification and drawings, or direct or indirect application in other corresponding technical fields, are also included in the patent protection scope of the present application.

[0128] The above detailed description of the application is merely exemplary in nature and, thus, does not limit the application. Any modification and the like that do not depart from the spirit and principles of the application are intended to be within the scope of the application.

Claims

1. A control method for a multi-electric aircraft hybrid energy storage system based on negative impedance compensation, characterized in that, The multi-electric aircraft hybrid energy storage system comprises: A high-voltage DC generator connected to a 270V DC bus through a filter capacitor; A hybrid energy storage unit composed of lithium batteries and supercapacitors, both of which are connected to the 270V DC bus through independently configured bidirectional DC-DC converters; A pulse power load directly connected in parallel to the 270V DC bus.

2. The control method according to claim 1, characterized by, The core control architecture comprises: Integrating a negative impedance compensation mechanism in the generator, lithium battery, and supercapacitor control loops; Building a hybrid energy storage system second-order feedforward differential circuit model enhanced by compensation resistance; Designing adaptive compensation parameters based on dynamically matching load current change rate and grid impedance structure.

3. The control method of claim 1, wherein, The core control architecture comprises: Step 1: Introducing a negative impedance compensation mechanism in the generator, lithium battery, and supercapacitor control loops, and building a hybrid energy storage system second-order feedforward differential circuit model enhanced by compensation resistance; Step 2: Based on dynamically matching load current change rate and grid impedance structure, analyzing and designing adaptive compensation impedance and integrator upper limit to optimize power distribution of the generator, lithium battery, and supercapacitor; Step 3: Designing the control structure of the hybrid energy storage system based on the second-order feedforward differential architecture and negative impedance compensation control.

4. The control method of claim 1, wherein, The step 1 further comprises: The negative impedance compensation mechanism reduces the output impedance of the equivalent input power supply system, and makes the dynamic power compensation capability of the system increase by 20%-40% for pulse load conditions with a current change rate exceeding 100A / ms.

5. The control method of claim 2, wherein, The step 1 comprises: The power distribution of the hybrid energy storage system is based on three-frequency-band frequency division, in which low-frequency components are allocated to the generator, medium-frequency components are allocated to the lithium battery, and high-frequency components are allocated to the supercapacitor, and coordinated control is performed through an improved second-order feedforward differential filter frequency division architecture; The negative impedance compensation mechanism reduces the output impedance of the equivalent input power supply system, and enhances the dynamic power compensation capability of high-current change rate loads; The low-frequency components are 0.01-0.1Hz, the medium-frequency components are 0.1-10Hz, and the high-frequency components are >10Hz.

6. The control method of claim 2, wherein, The step 2 comprises: The negative impedance compensation mechanism introduces an adaptive compensation resistance R com According to the change rate and instantaneous value of the load current, the voltage recovery is dynamically adjusted and performed. The adaptive compensation resistance R com The integral upper limit constraint is adopted to maintain the stability of the hybrid energy storage system and prevent system instability caused by excessive negative impedance.

7. The control method of claim 2, wherein, The adaptive compensation parameter design comprises: A dynamic adjustable compensation resistor R is introduced com with a resistance range set to -0.5Ω to -2.5Ω; Using a real-time updated integral upper limit constraint condition, and the constraint condition expression is: |Rcom|≤K·(di / dt)max Where K is the system stability coefficient, and (di / dt)max is the maximum allowed current change rate.

8. The control method of claim 7, wherein, The compensation resistance R com The adjustment process includes: Real-time monitoring of DC bus voltage fluctuation ΔV through a high-speed sampling circuit; When ΔV exceeds the threshold value, a fast response mode of negative impedance compensation is started; R is adjusted according to the degree of voltage deviation classification com of the compensation intensity.

9. The control method of claim 2, wherein, The second-order feedforward differential circuit model comprises: A parallelly connected differential compensation branch and an inertial delay branch; An RC network with adjustable time constant, and the time constant is set to an adjustable range of 0.1ms-10ms; The load current change rate detection accuracy reaches ±5A / μs.

10. The control method of claim 9, wherein, Further comprising dynamic stability guarantee measures: Setting a priority response channel in the supercapacitor control loop; When di / dt>50A / ms is detected, the response delay of the supercapacitor is controlled within 100μs; The lithium battery loop is provided with a 5ms smoothing filter link.

11. The control method of claim 1, wherein, The control strategy of the bidirectional DC-DC converter comprises: The generator-side converter adopts double-loop control of voltage outer loop and current inner loop; The energy storage unit-side converter adopts improved droop control based on negative impedance compensation; A high-frequency communication synchronization mechanism above 10 kHz is set between each converter.

12. The control method of claim 11, wherein, The system protection method is also included: Set the emergency exit condition of negative impedance compensation: automatically switch to traditional PID control when an oscillation signal lasting more than 10 ms is detected; Configure multi-stage TVS protection devices at the DC bus; When the super capacitor SOC is lower than 20%, deep discharge compensation is prohibited.

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