Hybrid battery system second harmonic compensator self-tuning control method based on sine-cosine algorithm

Abstract

The application discloses a self-adjusting control method for a hybrid battery system secondary harmonic compensator based on a sine-cosine algorithm, and belongs to the technical field of harmonic compensator control. The application aims at the problem that the existing secondary harmonic current compensator has poor tracking and compensation effect due to parameter disturbance under complex working conditions in the secondary harmonic current suppression of a two-stage single-phase DC-AC inverter. The application comprises the following steps: taking the calculated error e as the current loop input signal of the secondary harmonic current compensator; designing a target function; adjusting the error e based on the target function by using a current loop PI regulator; iteratively optimizing and calculating the PI adjustment parameters of the current loop PI regulator based on the sine-cosine algorithm; reducing the transient response oscillation by minimizing the fitness value of the target function; and then calculating the duty cycle d of the switch tube of the secondary harmonic current compensator, so as to realize the self-adjusting control of the secondary harmonic current compensator. The application is used for the secondary harmonic current suppression of a hybrid battery system.

Description

Technical Field

[0001] The invention relates to a self-regulating control method of a hybrid battery system second harmonic compensator based on a sine-cosine algorithm, and belongs to the technical field of harmonic compensator control. Background Art

[0002] The second harmonic current suppression technology in the front-stage DC-DC converter of a two-stage single-phase DC-AC inverter has attracted widespread attention from enterprises and academia due to its broad application prospects and significant advantages, such as in application scenarios such as new energy vehicles and photovoltaic systems, and has become a research hotspot in the field of power electronics technology.

[0003] In a two-stage single-phase DC-AC inverter, the pulsating instantaneous power at the AC port is twice the frequency of the AC voltage. This generates second harmonic currents at the intermediate DC bus port at twice the frequency of the AC voltage. These second harmonic currents are supplied by the preceding DC-DC converter and the intermediate bus capacitor. Once introduced into the preceding DC-DC converter, these second harmonic currents propagate to the DC input source, including batteries and fuel cells. This flow can adversely affect the energy conversion efficiency of batteries and fuel cells, potentially shortening their service life. Furthermore, the second harmonic currents increase the current stress on the power devices in the DC-DC converter, leading to increased conduction losses and reduced energy conversion efficiency. Using a second harmonic current compensator without electrolytic capacitors is a suitable method for maintaining system stability and effectively suppressing second harmonic currents. The control method of the second harmonic current compensator is key to effectively suppressing second harmonic currents, and different control methods have a significant impact on the tracking and compensation performance of the second harmonic current compensator.

[0004] Due to the complex operating conditions, the second harmonic current compensator may be subject to varying degrees of interference. Using an optimization algorithm to iteratively adjust the control parameters of the second harmonic current compensator in a timely manner is an effective method for dealing with second harmonic current compensator parameter disturbances. To improve the practicality of second harmonic current suppression technology, it is of great theoretical significance and practical value to study a second harmonic compensator for a hybrid system with a fuel cell and a battery that is compact, has excellent second harmonic current suppression, and has the ability to self-regulate parameters. Summary of the Invention

[0005] Aiming at the problem of poor tracking and compensation effects of existing second harmonic current compensators due to parameter disturbances in the second harmonic current suppression of two-stage single-phase DC-AC inverters under complex working conditions, the present invention provides a self-regulating control method for the second harmonic compensator of a hybrid battery system based on a sine-cosine algorithm.

[0006] The present invention provides a self-regulating control method for a second harmonic compensator of a hybrid battery system based on a sine-cosine algorithm, comprising:

[0007] A second harmonic current compensator is connected in parallel at the DC-DC converter and the intermediate bus of the DC-AC converter of the two-stage single-phase DC-AC inverter; the second harmonic current compensator includes an inductor L s , capacitor C s , switch tube S1 and switch tube S2; determine the inductor L s and capacitor C s The value of

[0008] The self-regulating control method comprises:

[0009] Based on the capacitor voltage signal Calculate the voltage loop signal of the second harmonic current compensator;

[0010] Based on the intermediate bus current i inv The second harmonic current tracking signal is obtained by calculation;

[0011] The error e calculated based on the voltage loop signal, the second harmonic current tracking signal and the inductor current of the second harmonic current compensator is used as the current loop input signal of the second harmonic current compensator;

[0012] An objective function is designed, which is an integral function of time and the absolute value of the error e. A current loop PI regulator is used to adjust the error e based on the objective function, and the PI adjustment parameters of the current loop PI regulator are iteratively optimized and calculated based on the sine-cosine algorithm. By minimizing the fitness value of the objective function, the transient response oscillation is reduced, and the duty cycle d of the second harmonic current compensator switching tube is calculated to achieve self-regulating control of the second harmonic current compensator.

[0013] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the fitness value W of the objective function is:

[0014]

[0015] Where t is time.

[0016] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the PI regulating parameters include the proportional coefficient K p and the integral coefficient K i ; Use parameter X as the proportional coefficient K p and the integral coefficient K i Methods for iteratively updating the sine-cosine algorithm include:

[0017]

[0018] In the formula is the current solution of the ith dimension position of the parameter X during the nth iteration, r1, r2, r3 and r4 are the four random factors of the sine-cosine algorithm, P i n-1 is the i-th dimension position target solution of parameter X in the n-1th iteration process; when i=1, Corresponding K p When i=2, X i n Corresponding K i ;

[0019] The current solution obtained in each iteration process The number of is the set number.

[0020] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the random factor r1 is used to represent the current solution. In the previous solution and inside or outside the target solution:

[0021]

[0022] Where a is a constant and N is the maximum number of iterations;

[0023] The random factor r2 is a random number between 0 and 2π, indicating the current solution distance to the target solution;

[0024] The random factor r3 is a random number between 0 and 2, indicating the weight of the target solution; r3>1 indicates emphasis, and r3<1 indicates the opposite;

[0025] The random factor r4 is a random number between 0 and 2π, representing equivalent inverted sine and cosine functions.

[0026] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the initial value X0 of the set number of parameters X is determined according to the following formula:

[0027] X0=lb+rand*(ub-lb),

[0028] Where ub represents the upper bound of parameter X, and lb represents the lower bound of parameter X.

[0029] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the process of optimizing the PI adjustment parameters includes:

[0030] Determine the current global optimal solution according to the fitness value: adjust the error e with all current solutions of the parameter X as candidate solutions, and then calculate the fitness value of the objective function based on the adjusted error e; select the candidate solution corresponding to the minimum current fitness value as the current determined solution, and as the current global optimal solution; judge whether the current global optimal solution is greater than or equal to the corresponding target solution:

[0031] If yes, determine the range of the candidate solution in the next iteration based on the current determined solution, and determine the initial value of the set number in the next iteration within the range of the candidate solution according to the formula of the initial value X0; calculate the set number fitness value of the next iteration based on the initial value of the set number in the next iteration, and determine the next determined solution in the next iteration; if the next determined solution is less than the current determined solution, update the current global optimal solution to the next determined solution; and judge whether the current global optimal solution is greater than the corresponding target solution; until n=N, take the final obtained current global optimal solution as the optimal solution of the proportional coefficient K p and the integral coefficient K i ;

[0032] Otherwise, re-determine the initial value of the current iteration process, and return to the step of determining the current global optimal solution according to the fitness value.

[0033] The hybrid battery system second harmonic compensator based on the self-adjusting control method of the sine-cosine algorithm, the second harmonic current compensator is a Boost type power electronic converter;

[0034] The determination method of the value of the capacitor C s is as follows:

[0035] The determination method of the value of the capacitor C s is as follows:

[0036]

[0037]

[0038] In the formula, E is the energy of the capacitor C s charged or discharged in half cycle, t0 is the starting time of charging or discharging, T ac is the 50Hz AC cycle, i SHCC is the inductance current of the second harmonic current compensator, V bus is the bus voltage, V ac is the DC-AC inverter output voltage amplitude, I ac is the DC-AC inverter output current amplitude, and ω ac is the 50Hz AC angular frequency, and p0 is the DC-AC inverter output power.

[0039] is the capacitance C s The maximum charging capacitance, is the capacitance C s The minimum charging capacitance, is the capacitance C s The average voltage of half cycle charge or discharge, is the capacitance C s Voltage fluctuation value of half cycle charging or discharging;

[0040]

[0041]

[0042] According to formulas (1) and (2), we can get:

[0043]

[0044] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the inductor L s The method for determining the value of is:

[0045] According to the second balance principle of Boost type power electronic converter, we can get:

[0046]

[0047] Where d S1 (t) is the duty cycle of the switch tube S1;

[0048] The inductor ripple expression of the Boost type power electronic converter is:

[0049]

[0050] Where Δi L is the inductance L s The current change, T is the period of the switch tube, D is the amplitude of the switch tube duty cycle, is the inductance L s Voltage signal;

[0051] According to formulas (4) and (5), we can get:

[0052]

[0053] According to the self-regulating control method of the hybrid battery system second harmonic compensator based on the sine-cosine algorithm of the present invention, the capacitor voltage signal and capacitor voltage reference value After the difference is made, the voltage loop signal is obtained through the PI regulator.

[0054] The mixed battery system secondary harmonic compensator based on the self-adjusting control method of the cosine algorithm adopts a 100Hz band-pass filter to filter the intermediate bus current i inv The filtered secondary harmonic current tracking signal is obtained.

[0055] The sum of the voltage loop signal and the secondary harmonic current tracking signal is subtracted from the inductance current i SHCC of the secondary harmonic current compensator to obtain the error e.

[0056] The method has the following advantages: the method is based on the mathematical model of the cosine algorithm, generates multiple initial random candidate solutions, and makes them move away from the optimal solution or fluctuate around the optimal solution; multiple random variables and adaptive variables are used to calculate the position of the current solution, and the method has a unique optimization principle and good optimization potential.

[0057] In the operation process of the two-stage single-phase DC-AC inverter, the secondary harmonic current compensator is used to absorb the secondary harmonic current; the PI parameters are iteratively calculated by using the cosine algorithm to obtain the optimal K p and K i , and the duty cycle d of the secondary harmonic current compensator switch is obtained through the current loop PI regulator determined by K p and K i for switching control.

[0058] The method uses the cosine algorithm to self-adjust and control the secondary harmonic current compensator, so that the secondary harmonic current generated in the intermediate DC bus port due to the pulsed instantaneous power of the two times of the AC voltage frequency at the AC port is greatly reduced, and the secondary harmonic current compensator has good tracking and compensation performance when the parameters are perturbed. The practicability of the method is improved. Experimental verification shows that under the condition of parameter perturbation and full load, the secondary harmonic current content in the fuel cell front-end DC-DC converter is 0.056%, and the fuel cell current ripple is 3.52%; the battery current is changed from being completely affected by the secondary harmonic current to being basically stable at a stable output value, and the iteration process reaches the optimal solution at the 44th time,

[0059] The method can effectively remove the intermediate bus electrolytic capacitor required in the traditional method or reduce the voltage fluctuation of the intermediate bus capacitor, and improve the application value of the fuel cell and battery coexistence hybrid system.

[0060] The method of the present invention requires sampling circuit signals. By processing these samples, a second harmonic current tracking signal is generated, which is used for closed-loop control of the second harmonic current compensator. Compared with traditional second harmonic current suppression methods, the method of the present invention can effectively reduce the second harmonic content in the system, effectively improve system stability, and greatly enhance the application scenarios and use value of the second harmonic compensator.

[0061] The method of the present invention incorporates a self-regulating control method based on the sine-cosine algorithm into the current loop of the second harmonic current compensator. This method can effectively address the problem of second harmonic current compensator parameter perturbations that arise in complex actual operating conditions, thereby improving the stability and robustness of the system. The method of the present invention effectively suppresses second harmonic currents and has the ability to self-regulate parameters, thereby enhancing the practicality of second harmonic current suppression technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the overall block diagram of the second harmonic current compensator connected in parallel at the DC-DC converter and the intermediate bus of the DC-AC converter of the two-stage single-phase DC-AC inverter in the control method of the present invention; SHCC in the figure is the second harmonic current compensator; V dc is the fuel cell supply voltage, I dc is the input current of the DC-DC converter, C bus is the bus capacitance, i ac is the DC-AC inverter output current, v ac is the output voltage of the DC-AC inverter;

[0063] Figure 2 It is a schematic diagram of the circuit structure of a Boost type power electronic converter;

[0064] Figure 3 This is the overall block diagram of the hybrid system where fuel cells and batteries coexist and the second harmonic current compensator;

[0065] Figure 4 Figure 1 is a block diagram of a self-regulating control method for a second harmonic current compensator based on the sine-cosine algorithm. In the figure, SCA stands for sine-cosine algorithm.

[0066] Figure 5 It is a schematic diagram of the influence of random factor r1 on position update; P in the figure represents the target solution;

[0067] Figure 6 This is a schematic diagram of the effect of sine or cosine functions on position updates;

[0068] Figure 7 This is a flow chart of the self-regulating control of the second harmonic current compensator based on the sine-cosine algorithm;

[0069] Figure 8is the convergence curve of the sine-cosine algorithm;

[0070] Figure 9 This is a schematic diagram of the input current of a two-stage single-phase DC-AC inverter in steady state;

[0071] Figure 10 This is a schematic diagram of the fuel cell output current of the second harmonic current compensator;

[0072] Figure 11 This is a schematic diagram of the second harmonic content of the output current of a fuel cell with a second harmonic current compensator. In the figure, DC represents direct current and THD represents harmonic content.

[0073] Figure 12 This is a schematic diagram of the battery output current of the second harmonic current compensator;

[0074] Figure 13 This is a schematic diagram of the intermediate bus voltage of the second harmonic current compensator;

[0075] Figure 14 This is a schematic diagram of the inductor current of the second harmonic current compensator in steady state;

[0076] Figure 15 This is a schematic diagram of the capacitor voltage of the second harmonic current compensator in steady state. DETAILED DESCRIPTION

[0077] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0078] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0079] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0080] Specific implementation method 1. Combination Figures 1 to 7 As shown, the present invention provides a self-regulating control method of a second harmonic compensator of a hybrid battery system based on a sine-cosine algorithm, comprising:

[0081] A second harmonic current compensator is connected in parallel at the DC-DC converter and the intermediate bus of the DC-AC converter of the two-stage single-phase DC-AC inverter; the second harmonic current compensator includes an inductor L s , capacitor C s , switch tube S1 and switch tube S2; determine the inductor Ls and the capacitance C s ;

[0082] The self-adjusting control method comprises:

[0083] calculating the voltage loop signal of the second harmonic current compensator based on the capacitance voltage signal v Cs ;

[0084] calculating the second harmonic current tracking signal based on the intermediate bus current i inv ;

[0085] taking the error e calculated based on the voltage loop signal, the second harmonic current tracking signal and the inductance current of the second harmonic current compensator as the current loop input signal of the second harmonic current compensator;

[0086] designing a target function, which is an integral function of time and absolute value of the error e; adjusting the error e based on the target function by using a current loop PI regulator, and iteratively optimizing and calculating PI adjustment parameters of the current loop PI regulator based on a sine-cosine algorithm, so as to reduce transient response oscillation by minimizing the fitness value of the target function, and then calculating the duty cycle d of the switch tube of the second harmonic current compensator, thereby realizing self-adjusting control of the second harmonic current compensator.

[0087] The embodiment is directed to the problem that, in a current-voltage double-loop controlled second harmonic current compensator, due to parameter perturbation of the inductance L s and the capacitance C s , the tracking and compensation effect of the second harmonic current in the two-stage single-phase DC-AC inverter is poor, and the error is large. The duty cycle d of the switch of the second harmonic current compensator is calculated based on the sine-cosine algorithm under the target function, which is used in the control of the second harmonic current compensator, so as to realize self-adjusting control of the power electronic second harmonic compensator.

[0088] The second harmonic current compensator in the embodiment plays a role of tracking and absorbing the second harmonic current of the DC-AC converter, can prevent the second harmonic current from flowing into the front-stage DC-DC converter and the battery, and further prevent the second harmonic current from flowing into the fuel cell.

[0089] Further, as shown in Figure 4 , a module based on the sine-cosine algorithm is added to the current loop. The target function of the sine-cosine algorithm is designed as an integral function of time and absolute error, so that the transient response oscillation of the control system is small, and the parameters have good selectivity. The setting of the system is to calculate the to-be-determined parameters in the control system, so that the target function is minimized.

[0090] The fitness value W of the target function is:

[0091]

[0092] where t is time.

[0093] The sine cosine algorithm is based on the mathematical model of sine and cosine, generates a number of initial random candidate solutions, and makes it fluctuate towards or away from the optimal solution. It uses multiple random variables and adaptive variables to calculate the position of the current solution, which is very different from population-based optimization.

[0094] The optimization process of the sine cosine algorithm can be divided into two stages. In the exploration stage, the optimization algorithm quickly finds the feasible region in the search space by combining a random solution among all random solutions. In the development stage, the random solution will gradually change, and the change rate of the random solution will be lower than that in the exploration stage. In the sine cosine algorithm, the candidate solution is first randomly initialized, and then the value of the current solution in each dimension is updated according to the sine or cosine function, combined with a random factor.

[0095] In this embodiment, the PI regulation parameters include a proportional coefficient K p and an integral coefficient K i ; the parameter X is used as the proportional coefficient K p and the integral coefficient K i to perform the method of iterative updating of the sine cosine algorithm, which includes:

[0096]

[0097] wherein is the current solution of the i-th dimension of the parameter X in the n-th iteration process, r1, r2, r3 and r4 are four random factors of the sine cosine algorithm, P i n-1 is the target solution of the i-th dimension of the parameter X in the n-1-th iteration process; when i = 1, corresponds to K p ; when i = 2, corresponds to K i ;

[0098] The number of current solutions obtained in each iteration process is a set number.

[0099] wherein the random factor r1 is used to represent whether the current solution is inside or outside the previous solution and the target solution, and a smaller r1 value helps to enhance the local development ability of the algorithm, and a larger r1 value helps to improve the global exploration ability of the algorithm, in order to balance the local development and global search ability of the algorithm, r1 can be represented as:

[0100]

[0101] where a is a constant, and N is the maximum number of iterations;

[0102] The random factor r2 is a random number between 0 and 2π, and represents the current solution X i n The distance from the target solution;

[0103] The random factor r3 is a random number between 0 and 2, and represents giving the target solution a random weight, randomly emphasizing or not emphasizing the role of the target solution when defining the moving distance of the candidate solution; r3>1 represents emphasizing, and r3<1 represents the opposite;

[0104] The random factor r4 is a random number between 0 and 2π, and represents the same conversion sine and cosine functions, that is, the probability of taking sine and cosine is the same, and switching with equal probability.

[0105] Combining Figure 5 and Figure 6 When the value of the cosine function r1cosr2 or the value of the sine function r1sinr2 is greater than 1 or less than -1, the cosine-sine algorithm tends to perform global exploration. When the values of the cosine and sine functions are less than 1, the cosine-sine algorithm is more inclined to perform local development. The parameters r1 and r2 have an impact on the values of the cosine and sine functions. However, since r1 is outside the sine and cosine functions, its value is more decisive for the balance between global search and local development.

[0106] Further, combining Figure 7 , the parameters and positions are initialized, and then the initial values of each solution are randomly set. The initial values X0 of the set number of parameters X are determined according to the following formula:

[0107] X0 = lb + rand * (ub - lb),

[0108] where ub represents the upper limit value of the parameter X, and lb represents the lower limit value of the parameter X.

[0109] In this embodiment, the process of optimizing the PI regulation parameters includes:

[0110] Determining the current global optimal solution according to the fitness value: taking all current solutions of the parameter X as candidate solutions to adjust the error e, and then calculating the fitness value of the objective function based on the adjusted error e; selecting the candidate solution corresponding to the minimum value of the current fitness value as the current determined solution, and taking it as the current global optimal solution; judging whether the current global optimal solution is greater than or equal to the corresponding target solution:

[0111] If so, determine the range of candidate solutions in the next round of iteration based on the current determined solution, and determine the initial value of the set number in the next round of iteration within the range of candidate solutions according to the formula of the initial value X0; then calculate the set number fitness value of the next round of iteration based on the initial value of the set number in the next round of iteration, and determine the next round of determined solution in the next round of iteration; if the next round of determined solution is less than the current determined solution, update the current global optimal solution to the next round of determined solution; and determine whether the current global optimal solution is greater than the corresponding target solution; until n=N, the final current global optimal solution is used as the proportional coefficient K p and the integral coefficient K i The optimal solution of

[0112] Otherwise, the initial value of the current iterative process is re-determined, and the process returns to the step of determining the current global optimal solution according to the fitness value.

[0113] The above iterative process can ensure that the duty cycle d of the second harmonic current compensator switch is obtained, which makes the system stable and can accurately track and compensate the second harmonic current when the parameters of the second harmonic current compensator are perturbed.

[0114] According to the sine-cosine algorithm after setting the objective function, the PI parameter K in the current loop is p and K i Optimization iterations are performed to adapt to parameter perturbations of the inductor and capacitor in the second harmonic current compensator, ensuring that the second harmonic current compensator can still accurately track and compensate for the second harmonic current in the hybrid system under parameter perturbations, thereby improving system stability.

[0115] As an example, combined with Figure 2 As shown, the second harmonic current compensator is a Boost type power electronic converter;

[0116] According to the energy conservation formula, the second harmonic current compensator inductor L s and capacitor C s Parameter calculation.

[0117] Capacitor C s The method for determining the value of is:

[0118] Capacitor C s The energy formula for half-cycle charging or discharging is:

[0119]

[0120]

[0121] In the formula is the capacitance C s The energy of half cycle charging or discharging, t0 is the starting time of charging or discharging, T acis a 50Hz AC cycle, i SHCC is the inductor current of the second harmonic current compensator, V bus is the bus voltage, V ac is the output voltage amplitude of the DC-AC inverter, I ac is the output current amplitude of the DC-AC inverter, ω ac is the 50Hz AC angular frequency, p0 is the DC-AC inverter output power, p0=V ac I ac is the output power of the DC-DC converter of the two-stage single-phase converter;

[0122] is the capacitance C s The maximum charging capacitance, is the capacitance C s The minimum charging capacitance, is the capacitance C s The average voltage of half cycle charge or discharge, is the capacitance C s Voltage fluctuation value of half cycle charging or discharging;

[0123]

[0124]

[0125] According to formulas (1) and (2), we can get:

[0126]

[0127] Inductor L s The method for determining the value of is:

[0128] According to the second balance principle of Boost type power electronic converter, we can get:

[0129]

[0130] Where d S1 (t) is the duty cycle of the switch tube S1;

[0131] The inductor ripple expression of the Boost type power electronic converter is:

[0132]

[0133] Where Δi L is the inductance L s The current change, T is the period of the switch tube, D is the amplitude of the switch tube duty cycle, is the inductance L s Voltage signal;

[0134] According to formulas (4) and (5), we can get:

[0135]

[0136] In this embodiment, the capacitor voltage signal and capacitor voltage reference value After the difference is made, the voltage loop signal is obtained through the PI regulator; it is used to generate the compensation current to compensate for the power loss of the second harmonic current compensator.

[0137] The intermediate bus current i is filtered using a 100Hz bandpass filter. inv Filtering to obtain the second harmonic current tracking signal;

[0138] The sum of the voltage loop signal and the second harmonic current tracking signal is subtracted from the inductor current i of the second harmonic current compensator. SHCC , and get the error e.

[0139] The beneficial effects of the present invention are verified below through specific examples: Specific embodiment:

[0141] To verify the effectiveness of the proposed method for a hybrid system, a hybrid system, a second harmonic current compensator, and a sine-cosine algorithm self-regulation module topology were implemented in Simulink. The fuel cell was replaced by a voltage source connected to a two-phase interleaved parallel step-up DC-DC converter. The battery was modeled using a voltage source and a resistor, and the load was modeled using a current source. The hybrid system's second harmonic current compensator operating conditions, based on the sine-cosine algorithm self-regulation module, were simulated.

[0142] The component parameters in the second harmonic current compensator simulation model are set as follows: the output power p0 of the front-stage converter of the two-stage single-phase converter is 3kW, the average voltage V during the half-cycle charging or discharging of the second harmonic current compensator capacitor is Cs_av The voltage fluctuation range of the second harmonic current compensator capacitor during half-cycle charging or discharging is 150V. For 100V, the second harmonic current compensator inductor L s The second harmonic current compensator capacitor C is 163.2uF (1±5%). s The capacitor is 0.6mF (1±5%). Assume that the PFC of the single-phase inverter is 1 and the initial phase is 0. The capacitor voltage is initially set to 200V. The sine-cosine algorithm search agent is 10 and the maximum number of iterations is 150.

[0143] Figures 8 to 15 The simulation results of the performance of a hybrid battery system when applying a second harmonic current compensator module based on the self-regulating control of the sine-cosine algorithm are presented.

[0144] Figure 8As shown, after the parameter perturbation of the second harmonic current compensator in the hybrid battery system, the optimal value of the objective function obtained in 150 iterations is 0.030386; according to the sine-cosine algorithm, the optimal PI parameters K p and K i are 0.00223367 and 65 respectively, and the optimal parameters are converged in the 44th iteration.

[0145] Figure 9 As shown, the input current of the inverter.

[0146] As shown by Figure 10 and Figure 11 , the Fourier transform results clearly show that the second harmonic current compensator can accurately track and compensate the second harmonic current in the fuel cell output current in the case of parameter perturbation, and the content of the second harmonic current is 0.056%.

[0147] As shown by Figure 12 , in the case of parameter perturbation, the battery output current is flat.

[0148] Figure 13 The DC bus voltage waveform of the hybrid system applying the second harmonic current compensator module based on the sine-cosine algorithm self-adjustment under parameter perturbation, and the DC bus voltage ripple is 0.002%.

[0149] As shown by Figure 14 , the second harmonic current compensator port can accurately track the second harmonic current from the inverter load; and Figure 15 indicates that the second harmonic current compensator capacitor voltage ripple is consistent with the design value, and the capacitor voltage is stable. Figures 8 to 15 The effectiveness and robustness of the second harmonic current compensation by the second harmonic current compensator module based on the sine-cosine algorithm self-adjustment control are demonstrated.

[0150] Although the present application is described herein with reference to particular embodiments, it is to be understood that these examples are merely illustrative of principles and applications of the present application. It should therefore be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It should be understood that the different dependent claims and features described herein can be combined with each other in different ways than those described in the original claims. It should also be understood that features described in relation to one embodiment can be used in other described embodiments.

Claims

1. A self-regulating control method for a second harmonic compensator of a hybrid battery system based on a sine-cosine algorithm, characterized in that: include: A second harmonic current compensator is connected in parallel at the DC-DC converter and the intermediate bus of the DC-AC converter of the two-stage single-phase DC-AC inverter; The second harmonic current compensator includes an inductor ,capacitance , switch tube and switch tube ; Determine the inductance and capacitors The value of The self-regulating control method comprises: Based on the capacitor voltage signal Calculate the voltage loop signal of the second harmonic current compensator; Based on the intermediate bus current The second harmonic current tracking signal is obtained by calculation; The error calculated based on the voltage loop signal, the second harmonic current tracking signal and the inductor current of the second harmonic current compensator As the current loop input signal of the second harmonic current compensator; Design objective function, the objective function is time and error Absolute value integral function; the current loop PI regulator is used to adjust the error based on the objective function Adjust the PI adjustment parameters of the current loop PI regulator based on the sine-cosine algorithm, and reduce the transient response oscillation by minimizing the fitness value of the objective function, and then calculate the duty cycle of the second harmonic current compensator switch tube. , realizing self-regulating control of the second harmonic current compensator; PI adjustment parameters include proportional coefficient and the integral coefficient ; With parameters As a proportionality factor and the integral coefficient Methods for iteratively updating the sine-cosine algorithm include: ， In the formula It is Parameters during the iteration The current solution of the i-th dimension position, , , and are the four random factors of the sine-cosine algorithm, It is -1 parameters during the iteration The i-th dimension position target solution; when i=1, correspond ; When i=2, correspond ; The current solution obtained in each iteration process The number of is the set number; Random Factor Used to indicate the current solution In the previous solution and inside or outside the target solution: ， In the formula is a constant, is the maximum number of iterations; Random Factor 0 to A random number between , indicating the current solution distance to the target solution; Random Factor is a random number between 0 and 2, indicating the weight of the target solution; To emphasize, To express the opposite; Random Factor 0 to Random numbers between , representing equivalent transformed sine and cosine functions; The process of optimizing PI tuning parameters includes: Determine the current global optimal solution based on the fitness value: All current solutions are used as candidate solutions to the error Adjustment is performed, and then based on the adjusted error Calculate the fitness value of the objective function; select the candidate solution corresponding to the current minimum fitness value as the current determined solution and the current global optimal solution; determine whether the current global optimal solution is greater than or equal to the corresponding target solution: If so, the range of candidate solutions in the next iteration is determined based on the current solution, and the initial value is used to determine the range of candidate solutions in the next iteration. The formula determines the initial value of the set number in the next round of iteration within the range of candidate solutions; then calculates the fitness value of the set number in the next round of iteration based on the initial value of the set number in the next round of iteration, and determines the next round of determined solution in the next round of iteration; if the next round of determined solution is smaller than the current determined solution, the current global optimal solution is updated to the next round of determined solution; and determines whether the current global optimal solution is larger than the corresponding target solution; until n=N, the final current global optimal solution is used as the proportional coefficient and the integral coefficient The optimal solution of Otherwise, the initial value of the current iterative process is re-determined, and the process returns to the step of determining the current global optimal solution according to the fitness value.

2. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 1 is characterized in that: Objective function fitness value for: ， In the formula For time.

3. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 2 is characterized in that: parameter The initial value of the number of settings Determined according to the following formula: ， In the formula Representation parameters The upper bound value of Representation parameters The lower bound value of .

4. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 1 is characterized in that: The second harmonic current compensator is a Boost type power electronic converter; capacitance The method for determining the value of is: capacitance The energy formula for half-cycle charging or discharging is: （1）， （2）， In the formula Capacitor The energy of half cycle charging or discharging, is the charging or discharging start time, For a 50Hz AC cycle, is the inductor current of the second harmonic current compensator, is the bus voltage, is the DC-AC inverter output voltage amplitude, is the output current amplitude of the DC-AC inverter, is the angular frequency of 50Hz AC, Output power for DC-AC inverter; Capacitor The maximum charging capacitance, Capacitor The minimum charging capacitance, Capacitor The average voltage of half cycle charge or discharge, Capacitor Voltage fluctuation value of half cycle charging or discharging; ， ， According to formulas (1) and (2), we can get: （3）。 5. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 4 is characterized in that: inductance The method for determining the value of is: According to the second balance principle of Boost type power electronic converter, we can get: （4）， In the formula For the switch tube Duty cycle; The inductor ripple expression of the Boost type power electronic converter is: （5）， In the formula For inductance The current change, is the period of the switch tube, D is the amplitude of the switch tube duty cycle, For inductance Voltage signal; According to formulas (4) and (5), we can get: （6）。 6. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 5 is characterized in that: Capacitor voltage signal and capacitor voltage reference value After the difference is made, the voltage loop signal is obtained through the PI regulator.

7. The self-regulating control method of the second harmonic compensator of the hybrid battery system based on the sine-cosine algorithm according to claim 6 is characterized in that: Use 100Hz bandpass filter to filter the intermediate bus current Filtering to obtain the second harmonic current tracking signal; The sum of the voltage loop signal and the second harmonic current tracking signal is subtracted from the inductor current of the second harmonic current compensator. , and get the error .

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