An all-electric helicopter energy storage SOC equalization control method based on fine-tuning virtual resistance

Abstract

The application discloses a kind of based on fine tuning virtual resistance's full electric helicopter energy storage SOC equalization control method, belongs to energy storage system control technical field, comprising the following steps: S1, calculating equalization factor;S2, calculating virtual impedance;S3, according to the equalization factor and virtual impedance calculated to obtain adjusted droop coefficient;S4, according to the reference voltage of bus, adjusted droop coefficient and the output current of converter to obtain the reference voltage of converter;S5, using voltage current double closed loop control, the reference voltage of converter is tracked.The application uses the above-mentioned one based on fine tuning virtual resistance's full electric helicopter energy storage SOC equalization control method, by feedback mechanism to fine tune virtual resistance, to ensure that the SoC of each energy storage unit can be consistent in charging and discharging process, significantly improve the equalization performance of energy storage, while reducing the SoC difference caused by line impedance mismatch.

Description

Technical Field

[0001] This invention relates to the field of energy storage system control technology, and in particular to a method for SOC equalization control of all-electric helicopter energy storage based on fine-tuning virtual resistance. Background Technology

[0002] Energy Storage Systems (ESS) are a key component of all-electric helicopter DC architectures. Connected to a DC microgrid via a bidirectional DC / DC converter, they play a crucial role in maintaining power and voltage stability within the microgrid. However, in actual operation, if the State of Charge (SoC) of distributed energy storage units is not balanced, continuous operation may lead to overcharging or over-discharging, significantly reducing the ESS's lifespan. Therefore, to prevent damage from overcharging and discharging, the SoC of the ESS must be coordinated and controlled to achieve balance.

[0003] In DC systems, traditional droop control is a commonly used power distribution method, but it has significant limitations. Traditional droop control can only distribute load power or current to each distributed energy storage unit according to a fixed ratio. If the droop coefficients are inconsistent, it will lead to differences in the System of Cost (SoC) of the energy storage units; even if the droop coefficients are consistent, the SoC will still be inconsistent due to the differences in the characteristics of the energy storage units themselves. To overcome this deficiency of traditional droop control, adaptive droop control for microgrid systems has emerged. This method can achieve good voltage recovery and stable operation of the microgrid by adaptively adjusting state variables such as bus voltage and energy storage system SoC, effectively solving the problem of inconsistent energy storage SoC caused by traditional droop control.

[0004] Currently, in practical applications of all-electric helicopters, line impedance mismatch is quite common due to the unique arrangement of energy storage locations. However, most existing studies have not fully considered the impact of line impedance mismatch on the SoC (System-on-Chips) balancing of energy storage systems. This may lead to the SoC of energy storage units not being completely consistent, thus affecting the stable operation of the DC architecture of the all-electric helicopter and the lifespan of the energy storage system. Therefore, further in-depth research is needed on SoC balancing control of energy storage systems in the DC architecture of all-electric helicopters to solve the line impedance mismatch problem and achieve precise SoC balancing of energy storage units. Summary of the Invention

[0005] The purpose of this invention is to provide a method for equalizing the SOC of an all-electric helicopter energy storage system based on fine-tuning virtual resistance, which can effectively compensate for the effects of line impedance mismatch and achieve error-free equalization of the SOC of the energy storage unit.

[0006] To achieve the above objectives, this invention provides a method for SOC equalization control of all-electric helicopter energy storage based on fine-tuned virtual resistance, comprising the following steps:

[0007] S1. Calculate the equilibrium factor;

[0008] S2. Calculate the virtual impedance;

[0009] S3. Calculate the adjusted droop coefficient based on the calculated equalization factor and virtual impedance;

[0010] S4. The reference voltage of the converter is calculated based on the reference voltage of the bus, the adjusted droop coefficient, and the output current of the converter.

[0011] S5. It adopts dual closed-loop control of voltage and current to track the reference voltage of the converter.

[0012] Preferably, in S1, the formula for calculating the equilibrium factor is:

[0013]

[0014] Where q is the equilibrium factor; n is the acceleration factor; and SOC is the state of matter. i Let DOD be the current charge of the i-th energy storage unit. i =1-SOC i , is the amount of charge used; SOC ave The average charge of each energy storage unit; DOD ave This represents the average charge used by each energy storage unit.

[0015] Preferably, in S2, the formula for calculating the virtual impedance is:

[0016]

[0017] Among them, R m,i For virtual impedance; k p k is the proportionality coefficient. o λ is the integral coefficient; i Let λ be the droop voltage drop of the i-th converter, including λ1 and λ2; λ ave This represents the average droop voltage drop of each converter;

[0018]

[0019] In the formula, λ1 is the droop voltage drop of the first converter, and λ2 is the droop voltage drop of the second converter. u is the reference voltage for the bus. dc I is the actual voltage of the bus. o1 I is the output current of the first converter. o2R1 is the output current of the second converter, R2 is the resistance of the line between the first converter and the bus, and R3 is the resistance of the line between the second converter and the bus. v1 R is the droop factor of the first converter. v2 This is the droop coefficient of the second converter.

[0020] Preferably, in S3, the formula for calculating the adjusted droop coefficient is:

[0021] R' v,i =qR Vi +R m,i ;

[0022] Among them, R' v,i R is the adjusted droop coefficient for the i-th converter. Vi Let be the droop coefficient of the i-th converter.

[0023] Preferably, in S4, the formula for calculating the converter's reference voltage is:

[0024]

[0025] Among them, U ref,i Let be the reference voltage of the i-th converter. I is the reference voltage of the bus. oi Let be the output current of the i-th converter.

[0026] Preferably, in S5, for the i-th converter, its reference voltage U is... ref,i With output voltage u C The voltage error is obtained by subtracting the voltage from the input voltage. This voltage error is then input into the PI controller, which outputs a reference current for the inductor current. The reference current of the inductor current With inductor current i L The difference is calculated to obtain the current error, which is then input into the PI controller to output the duty cycle. The duty cycle is then input into the PWM module to obtain the switching signal S1. If the converter is a unidirectional converter, only one switching signal is needed, and the switch is driven by the switching signal S1. If the converter is a bidirectional converter, two switching signals are needed, namely S1 and the inverted signal S2 of S1.

[0027] Therefore, the present invention adopts the above-mentioned all-electric helicopter energy storage SOC equalization control method based on fine-tuning virtual resistance, which significantly improves the energy storage equalization performance and reduces the SoC difference caused by line impedance mismatch.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a simplified diagram of a two-distributed energy storage all-electric helicopter system;

[0030] Figure 2 This is a control principle diagram of an all-electric helicopter energy storage SOC equalization control method based on fine-tuning virtual resistance according to the present invention;

[0031] Figure 3 This is a flowchart of a method for equalizing the SOC of an all-electric helicopter energy storage system based on fine-tuning virtual resistance, according to the present invention.

[0032] Figure 4 This is the control logic diagram of the voltage and current dual closed-loop control in the all-electric helicopter energy storage SOC equalization control method based on fine-tuning virtual resistance of the present invention;

[0033] Figure 5 This is a diagram illustrating the SOC balancing effect under the condition of no load disturbance in an embodiment of the present invention;

[0034] Figure 6 This is a diagram of the DC / DC converter output current under the condition of no load disturbance in an embodiment of the present invention;

[0035] Figure 7 This is a fine-tuned virtual impedance diagram under the condition of no load disturbance in the embodiments of the present invention;

[0036] Figure 8 This is a bus voltage diagram under the condition of no load disturbance in an embodiment of the present invention;

[0037] Figure 9 This is a diagram illustrating the SOC balancing effect under load disturbance conditions in an embodiment of the present invention.

[0038] Figure 10 This is a diagram of the DC / DC converter output current under load disturbance conditions in an embodiment of the present invention.

[0039] Figure 11 This is a load power diagram under the condition of load disturbance in an embodiment of the present invention;

[0040] Figure 12 This is a bus voltage diagram under the condition of load power disturbance in an embodiment of the present invention. Detailed Implementation

[0041] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0043] Example 1

[0044] This invention provides a method for SOC equalization control of all-electric helicopter energy storage based on fine-tuned virtual resistance, which can achieve the following: Figure 1 The energy storage control of the two distributed energy storage all-electric helicopter systems shown is illustrated in the following diagram. Figure 2 As shown in the figure (where LPF is a low-pass filter and PI represents a PI controller).

[0045] Specific control methods such as Figure 3 As shown, it includes the following steps:

[0046] S1. Calculate the equilibrium factor.

[0047] The formula for calculating the equilibrium factor is:

[0048]

[0049] Where q is the equilibrium factor; n is the acceleration factor; and SOC is the state of matter. i Let DOD be the current charge of the i-th energy storage unit. i =1-SOC i , is the amount of charge used; SOC ave The average charge of each energy storage unit; DOD ave This represents the average charge used by each energy storage unit.

[0050] S2. Calculate the virtual impedance.

[0051] The formula for calculating virtual impedance is:

[0052]

[0053] Among them, R m,i For virtual impedance; k p k is the proportionality coefficient. oλ is the integral coefficient; i Let λ be the droop voltage drop of the i-th converter, including λ1 and λ2; λ ave This represents the average droop voltage drop of each converter.

[0054]

[0055] In the formula, λ1 is the droop voltage drop of the first converter, and λ2 is the droop voltage drop of the second converter. u is the reference voltage for the bus. dc I is the actual voltage of the bus. o1 I is the output current of the first converter. o2 R1 is the output current of the second converter, R2 is the resistance of the line between the first converter and the bus, and R3 is the resistance of the line between the second converter and the bus. v1 R is the droop factor of the first converter. v2 This is the droop coefficient of the second converter.

[0056] S3. Calculate the adjusted droop coefficient based on the calculated equalization factor and virtual impedance.

[0057] The formula for calculating the adjusted sag coefficient is:

[0058] R' v,i =qR Vi +R m,i

[0059] Among them, R' v,i R is the adjusted droop coefficient for the i-th converter. Vi Let be the droop coefficient of the i-th converter.

[0060] S4. The reference voltage of the converter is calculated based on the reference voltage of the bus, the adjusted droop coefficient, and the output current of the converter.

[0061] The formula for calculating the converter's reference voltage is:

[0062]

[0063] Among them, U ref,i Let be the reference voltage of the i-th converter. I is the reference voltage of the bus. oi Let be the output current of the i-th converter.

[0064] S5. It adopts dual closed-loop control of voltage and current to track the reference voltage of the converter.

[0065] like Figure 4 As shown, for the i-th converter, its reference voltage U ref,iWith output voltage u C The voltage error is obtained by subtracting the voltage from the input voltage. This voltage error is then input into the PI controller, which outputs a reference current for the inductor current. The reference current of the inductor current With inductor current i L The difference is calculated to obtain the current error, which is then input into the PI controller to output the duty cycle. The duty cycle is then input into the PWM module to obtain the switching signal S1. If the converter is a unidirectional converter, only one switching signal is needed, and the switch is driven by the switching signal S1. If the converter is a bidirectional converter, two switching signals are needed, namely S1 and the inverted signal S2 of S1.

[0066] In this embodiment, a system was built in Simulink as follows: Figure 1 The model shown is used to verify the energy storage SOC equalization control method. The relevant parameters are shown in Table 1.

[0067] Table 1 Simulation-related parameters

[0068]

[0069]

[0070] ① When the load is undisturbed:

[0071] Three energy storage units are in a discharging state, each initially at 70% state of charge. No control is applied for the first 0-3 seconds. Due to inconsistent circuit resistances, differences in the state of charge appear among the three units after 3 seconds. At this point, energy storage unit equalization control is introduced, and the state of charge of the three units eventually converges. The results are presented in MATLAB / Simulink simulations. Figure 5-8 As shown.

[0072] Depend on Figure 5 It can be seen that the above-mentioned energy storage SOC balancing control method is effective; as shown in Figure 6, a smaller energy storage SOC outputs a lower current through the DC / DC converter, while a larger energy storage SOC outputs a higher current through the DC / DC converter; Figure 7 It can be seen that the virtual impedance corresponding to lower line resistance is larger, and the virtual impedance corresponding to higher line resistance is smaller; from Figure 8 It can be seen that the bus voltage is stable.

[0073] ②When the load is disturbed:

[0074] Three energy storage units are in a discharging state, each with an initial state of charge of 70%. No control is applied for the first 0-3 seconds. After 3 seconds, energy storage unit equalization control is introduced. The results are obtained through MATLAB / Simulink simulation. Figure 9-12 As shown.

[0075] Depend on Figure 9 It can be seen that the above-mentioned energy storage SOC equalization control method remains effective even in the presence of disturbances; as shown in Figure 10, the presence of disturbances causes a sudden change in the output current of the energy storage unit; Figure 11 It can be seen that impact loads occurred at 5s, 7s, and 9s; Figure 12 It can be seen that the bus voltage remains stable even when subjected to impulsive loads.

[0076] Therefore, the present invention adopts the above-mentioned all-electric helicopter energy storage SOC equalization control method based on fine-tuning virtual resistance. The virtual resistance is fine-tuned through a feedback mechanism to ensure that the SoC of each energy storage unit can remain consistent during charging and discharging, which significantly improves the energy storage equalization performance and reduces the SoC difference caused by line impedance mismatch.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for SOC equalization control of all-electric helicopter energy storage based on fine-tuned virtual resistance, characterized in that, Includes the following steps: S1. Calculate the equilibrium factor; In S1, the formula for calculating the equilibrium factor is: ； in, q As a balance factor; n As an acceleration factor; SOC i For the first i Taiwan's current energy storage capacity; DOD i =1- SOC i , which is the amount of charge used; SOC ave This represents the average charge of each energy storage unit. DOD ave The average charge used by each energy storage unit; S2. Calculate the virtual impedance; In S2, the formula for calculating the virtual impedance is: ； in, R m,i For virtual impedance; k p This is the proportionality coefficient; k o The integral coefficient; For the first i The droop voltage drop of the converter includes and ; This represents the average droop voltage drop of each converter; ； ； In the formula, The droop voltage drop of the first converter. The droop voltage drop of the second converter. The reference voltage for the busbar. u dc This is the actual voltage of the busbar. I o1 This is the output current of the first converter. I o2 This is the output current of the second converter. R 1 represents the resistance of the line between the first converter and the bus. R 2 represents the resistance of the line between the second converter and the bus. R v1 The droop factor for the first converter. R v2 The droop factor for the second converter; S3. Calculate the adjusted droop coefficient based on the calculated equalization factor and virtual impedance; In S3, the formula for calculating the adjusted droop coefficient is: ； in, For the first i The droop coefficient after the converter is adjusted. R Vi For the first i The droop factor of the converter; S4. The reference voltage of the converter is calculated based on the reference voltage of the bus, the adjusted droop coefficient, and the output current of the converter. S5. It adopts dual closed-loop control of voltage and current to track the reference voltage of the converter.

2. The method for SOC equalization control of all-electric helicopter energy storage based on fine-tuned virtual resistance according to claim 1, characterized in that: In S4, the formula for calculating the converter's reference voltage is: ； in, U ref,i For the first i The reference voltage of the converter The reference voltage for the busbar. I oi For the first i The output current of the converter.

3. The method for SOC equalization control of all-electric helicopter energy storage based on fine-tuned virtual resistance according to claim 1, characterized in that: In S5, for the first i The converter, its reference voltage U ref,i With output voltage u C The voltage error is obtained by subtracting the voltage from the input voltage. This voltage error is then input into the PI controller, which outputs a reference current for the inductor current. ; The reference current of the inductor current With inductor current The difference is calculated to obtain the current error, which is then input into the PI controller to output the duty cycle. The duty cycle is then input into the PWM module to obtain the switching signal. S 1; If the converter is a unidirectional converter, only one switching signal is needed. In this case, the switching signal... S 1. Drive the switch; If the converter is a bidirectional converter, then two switching signals are required, namely... S 1 and S Inverted signal of 1 S 2.

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