CN106130000A - Take into account the system ambiguous control method of parallel operation of efficiency and current-sharing index - Google Patents

Abstract

The invention relates to a fuzzy control method for a parallel power supply system that takes into account both efficiency and current-sharing indicators. The expression η=Φ(i) between the efficiency η and the load current i of the power supply module and the mathematical expected average value θ of the current-sharing relative deviation and The expression θ=Ψ(i) between the load current i of the power module and the corresponding optimal point and On the basis of , taking the current average current value I _share of the system as input, calculate I _share and The output μ ^Φ (I _share ) and I _share and The output μ ^Ψ (I _share ) of the membership function of the degree of deviation, and according to the fuzzy control rule table, the expected average current adjustment value ΔI is obtained, and then the number of modules is adjusted to ensure that the system works in a high efficiency and comprehensive performance index of current average Level, to ensure that the system efficiency and current-sharing comprehensive performance are at a high level target, by calculating the mathematical expectation of the deviation between the output current of each power module and the current-sharing target value I _share , the online power modules and backup power supplies that do not meet the performance requirements The modules are optimized and dispatched to realize that both the parallel power supply system and the online power supply modules work near the optimal point of performance.

Description

Fuzzy Control Method for Parallel Power Supply System Considering Efficiency and Current Sharing Index

technical field

The invention relates to a fuzzy control method for a parallel power supply system that takes into account both efficiency and current sharing indicators, and is used for the optimal control of the operating quantity of power supply modules in the parallel power supply system and the optimal scheduling of the power supply modules, ensuring that the efficiency and current balance synthesis of the parallel power supply system are taken into account under different load conditions performance, this method is also applicable to the requirements of efficiency and current sharing performance indicators for parallel operation of other electronic equipment.

Background technique

The high-power parallel power supply is a parallel output structure of multiple power modules. Because of its strong compatibility, N+m redundant backup, strong reliability, high cost performance, low design difficulty, and easy management, it has become a solution One of the preferred solutions for high-power output power supply design, current sharing technology has become the core technology of parallel power supply. The current sharing technology refers to that when multiple power modules are connected in parallel to supply power, the load current of each power module is evenly distributed with high precision under the premise of satisfying the steady-state accuracy and dynamic response of the output voltage. Therefore, the current sharing performance of the parallel power supply system is directly related to the safety, reliability and high performance of the whole system.

Due to the time-varying and random nature of the load current in the parallel power supply system, the traditional current sharing control scheme is adopted (that is, the number of power modules running online remains unchanged, and the output current of each power module is adjusted through the current sharing control algorithm to achieve the current sharing target and load matching. The working range of the power module in the parallel power supply system of the target scheme) covers light load, half load, rated load and overload and other working conditions. On the one hand, there are certain differences in the current sharing performance of the parallel power supply system when it is running under different load conditions, so it is necessary to optimize the control of the parallel power supply system to ensure that the system can always achieve high current sharing performance under different load current conditions; On the other hand, power modules have different working efficiencies under different load conditions. Therefore, it is necessary to optimize the number of online power modules in the parallel power supply system to ensure that each online power module works near the highest efficiency point, ensuring that the system is Optimum system efficiency under any load condition. Therefore, a new control strategy is needed, which can take into account the comprehensive index of parallel power supply system efficiency and current sharing performance.

The existing parallel power supply system current sharing control strategy can ensure that the load current of the parallel power supply system is evenly distributed among all online working power modules. However, there are three problems as follows: 1. The current sharing performance of the parallel power supply system cannot be achieved in a good state; 2. The parallel power supply system cannot achieve high efficiency; 3. The evaluation and optimal scheduling of the operating performance of each power module cannot be realized. It cannot be guaranteed that the current sharing performance of each power module meets the requirements. Therefore, in order to take into account that the comprehensive performance index of efficiency and current sharing effect of the parallel power supply system is at a high level under different load conditions, it is necessary to establish a comprehensive performance evaluation index of efficiency and current sharing to obtain the corresponding output current of the power module when the comprehensive performance index is high. value. As long as the output current of the power module of the parallel power supply system is controlled to be close to the optimal output current, it can ensure that the comprehensive performance index of the efficiency and current sharing effect of the parallel power supply system is optimal under different load conditions. At the same time, on the basis of optimizing and controlling the number of online power modules in the parallel power supply system, so that the power modules of the parallel power supply system always work near the optimum point of the comprehensive performance index, it is also necessary to carry out dynamic current sharing performance indicators for each online power module. Evaluate and optimize scheduling to ensure that each module and parallel power supply system are in the optimal state, ensuring efficient, reliable and long-life operation of the parallel power supply system.

However, by retrieving existing papers and patents, a reliable and practical parallel power supply system control method has not been found to achieve the optimization of system efficiency and current sharing comprehensive performance indicators and the optimal scheduling of each online power module. Therefore, a reliable and practical parallel power supply system control method is particularly important, which has an important impact on the reliable operation of the parallel power supply system.

Contents of the invention

The purpose of the present invention is to overcome the above disadvantages and propose a fuzzy control method for a parallel power supply system that takes into account both efficiency and current sharing index.

The technical solution of the present invention is: a fuzzy control method for a parallel power supply system taking into account both efficiency and current sharing index, the steps are as follows:

(1) Obtain the load current I _out of the parallel power supply system composed of K power modules from at intervals of equally spaced to , each power module operates at different load currents In the case of collecting V output current Data _curr (m')(i)(j), output voltage Data _volt (m')(i)(j) and input power P(m')(i)(j); where : m' is the serial number of the power module; i is the serial number value corresponding to the load current value; j is the serial number of the output current collection data; m', i, j satisfy m'={1,...K}, i={1,...U },j={1,…V}; I _N is the rated current of the power module;

(2) Obtain the output current and expected current of the power module with the serial number m' Relative deviation and the absolute value of the mathematical expectation Obtain the expected current of K power modules in current sharing as The mean value of E _{m'i at} Obtain the expected current of the power module with serial number m' as time efficiency and the efficiency mathematical expectation Obtain the expected current of K power modules in current sharing as Average efficiency under working conditions

(3) For U data points respectively and Fitted The relationship between the load current i of the power module And the relationship η=Φ(i) between efficiency η and power module load current i;

(4) Within the allowable output current range, obtain the satisfaction biggest and satisfied the smallest

(5) Calculate the number M of online power supply modules in the parallel power supply system at intervals of T _s , and collect the output currents of M online power supply modules, and mark the output current data of the mth online power supply module as Curr(m ), m is the serial number of the current online power module;

(6) Obtain the output current data array of the online power module whose serial number is m: Curr_store(m)(n)=Curr_store(m)(n+1), Curr_store(m)(T)=Curr(m); where: n=1,...T-1; m=1, 2, 3,...M; T is a positive integer greater than 2, and n is the current sampling times of the same online power module;

(7) Obtain the average output current of the online power module with serial number m: Among them: m=1, 2, 3, ... M;

(8) Obtain the load current of the parallel power supply system composed of M online power supply modules Sharing load current with in-line power modules

(9) Take I _share as input, obtain I _share and The output μ ^Φ (I _share ) of the degree of deviation membership function and the output μ ^Ψ (I _share ) of I _share and the degree of deviation membership function;

(10) Taking μ ^Φ (I _share ) and μ ^Ψ (I _share ) as inputs, the corresponding control rules are obtained according to the fuzzy control rule table and fuzzy inference, and the fuzzy calculation is performed according to the principle of fuzzy control center of gravity method, and the online The exact value of the output current adjustment ΔI of the membership function μ(ΔI) of the current adjustment amount of the power module:

(11) Judging whether |ΔI|≤σ is established;

(12) If |ΔI|≤σ is not established in step (11), then obtain the expected current-sharing load current of the online power supply module in the parallel power supply system: I _share = I _share + ΔI;

(13) Obtain the number N ^* of online power supply modules when the output current of the online power supply modules is the reference current I _share ,

(14) If N ^* ≤ 1, set N ^* = 2; otherwise, to obtain a parallel power supply system, it is necessary to adjust the number of power modules ΔN ^* = N ^* -M; and according to the positive or negative value of ΔN ^* , the centralized controller increases or decreases |ΔN ^* |one online power supply module;

(15) In step (11), |ΔI|≤σ holds true; then obtain the deviation θ(m)(n) between the output current Curr_store(m)(n) of the online power module with serial number m and the current sharing target value I _share =Curr_store(m)(n)-I _share ; Wherein: n=1,...T; m=1,2,3,...M;

(16) Obtain the mathematical expectation of the online power module deviation θ(m)(n) with the serial number m Among them: n=1,...T; m=1,2,3,...M;

(17) Then continue to the next online power module detection, otherwise, the current sharing performance of the online power module marked with serial number m does not meet the requirements, and C _θ is maximum allowable value;

(18) Offline the Num online power modules whose current sharing performance does not meet the requirements, and start the Num power modules from the backup power supply; continue the operation of step (5), where Num is marked as the current sharing performance does not meet the requirements Number of online power modules.

Step (3) apply polynomial fitting and curve fitting methods to U data points respectively and Perform fitting processing.

In step (9), pass

Get I _share with The output μ ^Φ (I _share ) of the degree of deviation membership function and the output μ ^Ψ (I _share ) of I _share and the degree of deviation membership function,

Where: s={NM,NS,O,PS,PM}, unit: unit: unit:

In step (10), by

Obtain the membership function μ(ΔI) of the current adjustment value of the online power module,

Where: s={NM,NS,O,PS,PM}, unit: unit: unit:

In step (1)-step (4),

(1) At t∈((i-1)T,iT], (U≥i≥1), the electronic load current is When , obtain the current-sharing target reference current of the power module:

(2) Obtain the output current sampling data of the power module with serial number m': Data _curr (m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1) , and obtain the relative deviation δ(m')(i)(j):

(3) Obtain the power module with serial number m' in The absolute value E _m'i of relative deviation δ(m')(i)(j) with respect to j's mathematical expectation under the condition:

E _m'i indicates that the power module with serial number m' is in The absolute value of the mathematical expectation of the relative deviation under the condition;

(4) Obtain the expected current of K power modules in current sharing as The mean of the absolute value of the mathematical expectation of the relative deviation:

(5) For U data points processed to get The relationship with the load current i of the power module: And within the allowable output current range, get to meet load current

(6) Obtain the power module with serial number m' in Conditional efficiency η(m')(i)(j):

(7) Obtain the power module with serial number m' in The mathematical expectation of η(m')(i)(j) about j under the condition η _m'i :

η _m'i means that the power module with serial number m' is in The average value of the efficiency under the condition;

(8) Obtain K power supply modules with expected current of current sharing as Average efficiency under working conditions:

(9) For U data points Process to obtain the relationship between efficiency η and power module load current i: η=Φ(i), and within the allowable output current range, obtain the satisfaction load current

The principle of the present invention mainly comprises the following parts: first, obtain the expression η=Φ(i) of the average efficiency η of the power module of the parallel power supply system and the load current i of the power module, and obtain the corresponding load current when Φ(i) is maximum Secondly, obtain the average value of the mathematical expectation of the relative deviation of the current sharing of the power modules in the parallel power supply system The expression between and the load current i of the power module And find the corresponding load current when Ψ(i) is minimum Then, according to the characteristics of Φ(i) and Ψ(i), expert experience knowledge and fuzzy theory, the following (in: )and (in: ) is the input quantity, and the adjusted output current of the power module ΔI is the membership function of the control quantity and the fuzzy control rule table; again, the number of online power modules is adjusted in real time according to the fuzzy control strategy to ensure that the system always works in the optimal working range; finally, Under the condition that the system works in the optimal working range, the output current data of each power module running online is obtained, and the mathematical expectation of the deviation between the output current data and the target average current value is obtained, so as to judge whether each power module running online meets the requirements And optimize scheduling control. Since the characteristics of power modules of the same specification are generally consistent, the current sharing performance index of a parallel power supply system composed of power modules of K (the size of K can be determined by the user, and K is tentatively set as 10 in the present invention) under different load currents is measured. The current sharing performance index of a parallel power supply system composed of any N power supply modules under different load conditions can be obtained. Then, the mathematical expectation of the deviation between the output current of each running power module and the target average current value is obtained. On the premise of ensuring the optimal number of power modules, the scheduling control of the running power modules is carried out according to the mathematical expectation of the deviation to ensure that the performance of each running power module meets the requirements.

The present invention has the following advantages:

(1) The present invention covers the working conditions of the full working range of the load current and has wide applicability;

(2) The present invention can comprehensively take into account the parallel power supply system efficiency and current sharing performance index, and has remarkable economy and system reliability;

(3) The present invention obtains respectively the expression η=Φ(i) between the efficiency η and the load current i of the power supply module and the mathematical expectation average value of the current-sharing relative deviation The expression between and the load current i of the power module and the corresponding optimal point and On the basis of , take the current average current value I _share of the parallel power supply system as the input, and calculate I _share and The output μ ^Φ (I _share ) and I _share and The output μ ^Ψ (I _share ) of the degree of deviation membership function, and according to the fuzzy control rule table of expert knowledge, the expected current average value adjustment value ΔI of the power module in the parallel power supply system is obtained, and then the number of online power modules in the parallel power supply system is adjusted. Ensure that the parallel power supply system works at a high level of comprehensive performance indicators of efficiency and current sharing.

(4) The present invention can dynamically adjust the number of online power supply modules in real time to ensure that the parallel power supply system always works near the optimal operating point of current sharing.

(5) The present invention ensures that the efficiency of the parallel power supply system and the comprehensive performance of current sharing are at a relatively high level, and by calculating the mathematical expectation of the deviation between the output current of each power supply module and the current sharing target value I _share , the performance does not meet the requirements The online power supply module and the backup power supply module are optimally dispatched to realize that both the parallel power supply system and the online power supply module work near the best point of performance;

(6) The fuzzy control method of parallel power supply system that takes into account both efficiency and current sharing index of the present invention has the characteristics of high reliability and strong practicability; it can effectively take into account the current sharing performance and efficiency index of parallel power supply system, and improve the operating economy of the system It provides a reliable guarantee for the safe and efficient operation of the parallel power supply system.

Description of drawings

Figure 1 is a structural diagram of a parallel power supply system efficiency and current sharing comprehensive performance test system.

Figure 2 is a structural diagram of the parallel power supply system.

Figure 3a shows I _share and The degree of deviation is the membership function μ ^Φ (I _share ).

Figure 3b shows I _share and The degree of deviation membership function μ ^Ψ (I _share ).

Fig. 3c is the membership degree function μ(ΔI) of the current-sharing current regulation output.

Figure 4 is a table of fuzzy decision rules.

detailed description

Embodiments of the present invention will be further described below with reference to the accompanying drawings:

The invention provides a fuzzy control method for a parallel power supply system taking into account both efficiency and current sharing index. Figure 1 shows the structure diagram of the parallel power supply system efficiency and current sharing comprehensive performance test system, Figure 2 shows the structure diagram of the parallel power supply system, Figure 3 shows the fuzzy control membership function, and Figure 4 shows the fuzzy rule table. The main function of Figure 1 is to obtain the functional relationship between the efficiency of the parallel power supply system and the load current η=Φ(i) and the mathematical relationship between the mathematical expectation average value of the relative deviation of the module current sharing and the load current and determine the optimum load current for each and Figure 1 mainly includes the upper computer (PC), program-controlled electronic load, power module, power meter, etc. The main functions of the host computer (PC) are to obtain the online module IP address, input power, module output current, output power, control the working current of the program-controlled electronic load, and calculate η=Φ(i) and The corresponding optimal load current and The program-controlled electronic load is used to adjust the load current of the parallel power supply system; the power module is mainly used to receive IP settings, receive command data from the host computer, upload output current, and output power to the host computer; the power meter is mainly used to measure the input power of the online power supply module . Figure 2 mainly includes the centralized controller of the parallel power supply system, power modules and power loads. The centralized controller obtains the IP and output current of the online modules through the communication bus, optimizes the number of online power supply modules and optimizes the scheduling of power modules with unqualified performance according to the fuzzy control principle; Run control commands and upload and output current; electrical loads mainly include various electrical equipment. The implementation of the current sharing adjustment function, whether there is an independent current sharing mode with or without a communication bus and a current sharing mode with a communication bus, is realized by a special current sharing function module, which will not be described in detail in the present invention. Figure 3a, Figure 3b and Figure 3c are fuzzy control membership functions, which are used to give the current average value I _share and The output μ ^Φ (I _share ) and I _share and The output μ ^Ψ (I _share ) of the membership function of the degree of deviation and the membership function μ (ΔI) of the current adjustment value of the current sharing of the power module. Fig. 4 is a fuzzy decision rule table, which is used to make fuzzy decisions on μ ^Φ (I _share ) and μ ^Ψ (I _share ).

1. The variables of the parallel power supply system efficiency and current sharing comprehensive performance test system are explained as follows: K is the number of power modules in the parallel power supply test system, and the specific value of K can be set according to the actual situation. _IN is the rated current of the power module; The rated output current for the parallel power supply system meets U is the number of load current points, that is, the load current I _out of the parallel power supply system is from at intervals of equally spaced to (covering light load, half load, rated load and overload conditions, U must be a positive integer not less than 20, which can be determined by the user according to the maximum load current value of the system); is the output current of the electronic load at the i-th point, where: U≥i≥1; m' is the serial number of the power supply module, satisfying: the IPs of K module power supplies are mapped as m'=1, 2,... K, that is, m'=1 is the serial number of the power supply module with the smallest IP, m'=2 is the serial number of the smallest IP module, ..., and so on, m'=K is the serial number of the module with the largest IP; V is the parallel power supply system at a certain At the load current point, it is necessary to sample the output current, output voltage and input power data of a single online power module, and V can be set according to actual needs. Data _curr (m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1) is the power module with serial number m' in The jth current sampling data under the condition; Data _volt (m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1) is the power module with serial number m' exist The jth output voltage sampling data under the conditions; P(m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1) is the power module with the serial number m' exist The jth input power sampling data under the condition; η(m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1) is the power module with serial number m' exist The jth efficiency data calculated under the condition satisfies: η _m'i is the power module with serial number m' in The mathematical expectation of V η(m')(i)(j) under the condition satisfies: I _ref (i) is the power module in The target reference value of current sharing under the condition satisfies: Among them: U≥i≥1; η _i is the expected current of K power supply modules in current sharing. The average efficiency under the working condition satisfies: δ(m')(i)(j) is the power module with serial number m' in The jth sampling current and current sharing reference target current under the condition The relative deviation value satisfies: E _m'i is the power module with serial number m' in The absolute value of the mathematical expectation of V δ(m')(i)(j) under the condition satisfies: For K power modules in The mathematical expectation average value of the current average relative deviation under the condition satisfies

Define t=0 as the last moment of no-load operation of the parallel power supply system; T is the interval time between two adjacent load currents; then t∈((i-1)T,iT], (U≥i≥1) is the parallel power supply System load current running time. due to During operation, 3V sample data needs to be collected for each power module, therefore, the upper computer needs to collect 3×K×V data in total. Assuming that the time for the host computer to collect a data is T ₁ , the system works in The state requires T _total =3×K×V×T ₁ time, so T≥T _total must be satisfied. And because the reliability of current sharing performance data is related to the number _of sampling points and sampling time T1, it is necessary to comprehensively consider the size _of T and T1 according to actual needs to ensure the reliability of current sharing performance indicators.

First of all, it can be seen from the knowledge of control engineering that the performance of the evaluation system can be measured by the overshoot of the system step response, the adjustment time and the steady-state deviation index. Therefore, in the parallel power supply system, the electronic load consists of Step to , we can also evaluate the current sharing performance of the power module by measuring the dynamic response between the current output of the power module and the current sharing target reference value. It can be seen from the knowledge of mathematical statistics that the mathematical expectation of the relative deviation of current sharing in parallel power supply systems represents the overall consistency between the actual value and the target value, reflects the accuracy of its step response process, and can reflect the current sharing performance index of the power module ; secondly, the parallel power supply system should take into account the economic benefits of system operation while satisfying the current sharing performance index; finally, by obtaining the expression η=Φ(i) between the efficiency η and the load current i of the power module and the current sharing Relative Deviation Mathematical Expected Mean The expression between and the load current i of the power module and its corresponding optimal load current and That Indicates the load current value of the power module when the efficiency of the parallel power supply system is optimal, Indicates the load current value when the current sharing performance of the parallel power supply system is optimal.

At t∈((i-1)T,iT], (U≥i≥1), the electronic load current is Then the current sharing target reference current of the power module is:

Obtain the output current sampling data of the power module with serial number m': Data _curr (m')(i)(j), (K≥m'≥1, U≥i≥1, V≥j≥1), therefore, The relative deviation of the average current δ(m')(i)(j) is:

Find the power module with serial number m' in The absolute value E _m'i of relative deviation δ(m')(i)(j) with respect to j under the condition is:

The physical meaning of E _m'i is: the power module with serial number m' is in The absolute value of the mathematical expectation of the relative deviation under the condition, the smaller the E _m'i indicates that the power module is in The better the consistency between the actual current value and the expected current sharing value under the conditions.

Calculate the current sharing expected current of K power modules as The mean of the absolute value of the mathematical expectation of the relative deviation:

The physical meaning of is: The smaller the power module, the The better the consistency of current sharing under the condition.

Apply relevant calculation methods (such as polynomial fitting, curve fitting, interpolation methods, etc.) to U data points processed to get The expression between and the load current i of the power module:

Solve the load current within the allowable output current range satisfy:

Find the power module with serial number m' in The conditional efficiency η(m')(i)(j) is:

Find the power module with serial number m' in Under the conditions, the mathematical expectation η _m'i of η(m')(i)(j) about j is:

The physical meaning of η _m'i is: the power module with serial number m' is in The average value of the efficiency under the condition, the larger η _m'i indicates that the power module is The better the economic performance under certain conditions, the more energy-saving;

Calculate the current sharing expected current of K power modules as Average efficiency under working conditions:

Apply relevant calculation methods (such as polynomial fitting, curve fitting, interpolation methods, etc.) to U data points The expression between the efficiency η and the load current i of the power module is obtained by processing:

η=Φ(i), (10)

Solve the load current within the allowable output current range satisfy:

2. Variables in the optimal control structure diagram of parallel power supply system are explained as follows:

T _s is the period for the centralized controller to calculate the number of online power modules and collect the output current data of the power modules; M is the number of online power modules; I _out is the load current of the parallel power supply system; Curr(m) is the online power module with serial number m The sampling value of the output current, m=1,2, ┄, M; I _share is the target value of the output current of the online power module when the parallel power supply system is running; ΔI is the adjustment value of the target value of the current sharing; σ is the threshold of ΔI; Curr_store (m)(n) is the output current storage array of the online power supply module with serial number m, m=1,2,┄,M; n=1,2,┄,T; The average value of the array Curr_store(m)(n) is stored for the output current of the online power module with serial number m; θ(m)(n) is the Curr_store(m)(n) and current sharing The deviation of the target value I _share : is the mathematical expectation of θ(m)(n); C _θ is Maximum allowable value; NB: Negative big; NM: Negative middle; NS: Negative small; Z: Zero; PS: Positive small; PM: Positive middle; PB: Positive big; μ ^Φ (I _share ): Parallel power supply system average current value I _share and Membership function of degree of deviation; μ ^Ψ (I _share ): I _share and Membership degree function of deviation degree; μ(ΔI): membership function of online power module current sharing current adjustment ΔI; μ ^Φ (I _share ), μ ^Ψ (I _share ) and μ(ΔI) respectively satisfy the formulas (12)～( 20);

The expression of μ ^Ψ (I _share ) is:

The expression of μ(ΔI) is: The unit of ΔI is:

Where: s={NM,NS,O,PS,PM}, unit: unit: unit:

At t=KT _s , K=0,1,2,3,..., the centralized controller of the parallel power supply system starts to collect the output current Curr(m) of M online power supply modules through the communication bus, m=1,2,┄ , M;

Update the output current data of the online power module with serial number m:

Curr_store(m)(n)=Curr_store(m)(n+1), (21)

Curr_store(m)(T)=Curr(m), (22)

Among them: m=1,2, ┄, M, n=1,2, ┄, T-1;

Calculate the average output current of the online power module with serial number m:

Among them: m=1, 2, 3, ... M;

To calculate the load current I _out of the parallel power supply system, satisfy:

Calculate the target value I _share of the output current of the online power module to satisfy:

Taking I _share as input, substitute into the membership degree function μ ^Φ (I _share ), the formulas (12)~(17) corresponding to μ ^Ψ (I _share ) to obtain the corresponding membership degree, and use μ ^Φ (I _share ), μ ^Ψ (I _share ) is the input, according to the fuzzy decision rule table and fuzzy inference obtained from expert experience, calculate the membership degree of the average current adjustment value μ (ΔI) of the online power supply module, and apply the center of gravity defuzzy control method to solve the on-line power supply Accurate value of module current adjustment amount ΔI:

Judging whether ΔI satisfies the inequality:

|ΔI|≤σ, (27)

If the inequality (27) is not satisfied, it indicates that the number of online power modules in the system is not near the optimal value. Calculate the expected current-sharing load current of the online power modules in the parallel power supply system:

I _share =I _share +ΔI, (28)

Calculate the number of online power modules N ^* when the output current of the online power modules is the reference current I _share , namely

Calculate the adjustment value ΔN ^* of the number of online power supply modules in the parallel power supply system, satisfying:

ΔN ^* =N ^* -M, (30)

The centralized controller increases (decreases) |ΔN ^* | online power supply modules to ensure the optimal efficiency and comprehensive current sharing performance of the parallel power supply system.

When inequality (27) is satisfied, it indicates that the number of online power modules in the system is near the optimal value. At this time, calculate the deviation between the output current storage data Curr_store(m)(n) of the online power module with serial number m and the current sharing target value I _share :

θ(m)(n)=Curr_store(m)(n)-I _share , (31)

Among them: n=1,...T; m=1,2,3,...M;

Calculate the mathematical expectation of the online power module deviation θ(m)(n) whose sequence number is m;

Among them: n=1,...T; m=1,2,3,...M;

Determine whether the standard deviation of the deviation between the output current of the online power module with serial number m and the current sharing target value satisfies the inequality:

If the online power module with serial number m satisfies the inequality (33), it means that the performance of the online power module is qualified; otherwise, the performance of the online power module is unqualified, and the qualified power module needs to be cut in from the spare module to work.

The present invention provides a fuzzy control method for a parallel power supply system that takes into account both efficiency and current sharing indicators, including the following steps:

(1) Obtain the load current I _out of the parallel power supply system composed of K power modules in advance from at intervals of equally spaced to (in order to meet the conditions of light load, half load, rated load and overload, U must be a positive integer not less than 20; I _N is the rated current of the power module), each power module at different load current Collect V output current Data _curr (m')(i)(j), output voltage Data _volt (m')(i)(j) and input power P(m')(i)(j)(V The size can be determined by the user according to the actual situation). Among them: m' is the serial number of the power module; i is the serial number value corresponding to the load current value; j is the serial number of the output current collection data; m', i, j satisfy m'={1,...K}, i={1,... U},j={1,...V};

(2) Calculate the output current and expected current of the power module with serial number m' Relative deviation and the absolute value of the mathematical expectation (The smaller the E _m'i , the better the consistency between the actual current of the power module and the expected current sharing value); calculate the expected current of the K power modules at the current sharing value as The mean value of E _{m'i at} Calculate the current sharing expected current of the power module with serial number m' as time efficiency and the efficiency mathematical expectation (The greater the η _m'i , the higher the efficiency of the power module); calculate the expected current of K power modules in the current sharing as Average efficiency under working conditions

(3) Apply relevant calculation methods (such as polynomial fitting, curve fitting, etc.) to U data points and Fitted The expression between and the load current i of the power module And the expression η=Φ(i) between efficiency η and power module load current i;

(4) Within the allowable output current range, solve satisfy maximum and satisfy minimum;

(5) Calculate the number M of online power modules in the parallel power supply system at intervals of T _s , and collect the output currents of M online power modules, and mark the output current data of the first serial number online power module as Curr(1 ), the serial number of the current online power supply module is m, let m=1;

(6) Update the output current data array of the online power supply module whose serial number is m, namely: Curr_store(m)(n)=Curr_store(m)(n+1), Curr_store(m)(T)=Curr(m); Among them: n=1,...T-1; m=1, 2, 3,...M; T is a positive integer greater than 2;

(7) Calculate the average output current of the online power supply module whose serial number is m: Among them: m=1, 2, 3, ... M;

(8) Calculate the load current of the parallel power supply system composed of M online power supply modules Sharing load current with in-line power modules

(9) Take I _share as input, find I _share and The output μ ^Φ (I _share ) of the degree of deviation membership function and the output μ ^Ψ (I _share ) of I _share and the degree of deviation membership function;

(10) Take μ ^Φ (I _share ) and μ ^Ψ (I _share ) as inputs, obtain the corresponding control rules according to the fuzzy control rule table and fuzzy inference, and perform precise calculations based on the principle of fuzzy control center of gravity method to obtain The precise value of the output current adjustment value ΔI of the online power module current adjustment value membership function μ(ΔI);

(11) Judging whether |ΔI|≤σ holds true? If yes, then enter step (20); otherwise, then enter step (12);

(12) Calculate the expected current-sharing load current of the online power supply module in the parallel power supply system: I _share = I _share + ΔI;

(13) Calculate the number N ^* of online power supply modules when the output current of the online power supply modules is the reference current I _share , namely

(14) Judging that N ^* ≤1? Is it established? If yes, then enter step (15); otherwise, enter step (16);

(15) Set N ^* = 2; this is because when N ^* <2, it is powered by a single power supply module and does not have a current sharing function;

(16) To calculate the parallel power supply system, it is necessary to adjust the number of online power supply modules ΔN ^* = N ^* -M;

(17) Judging that ΔN ^* > 0? Is it established? If yes, then enter step (18); otherwise, enter step (19);

(18) The centralized controller adds ΔN ^* online power supply modules, and then enters step (5);

(19) The centralized controller reduces ΔN ^* online power supply modules, and then enters step (5);

(20) Calculate the deviation θ(m)(n)=Curr_store(m)(n)-I _{share of the output current Curr_store(m)(n) of the online power supply module with the serial number and the current sharing target value I share ;} where : n=1,...T; m=1,2,3,...M;

(21) Calculate the mathematical expectation of the online power module deviation θ(m)(n) with the serial number m Among them: n=1,...T; m=1,2,3,...M;

(22) Initialize m=1;

(23) Initialize the number of unqualified online power supply modules Num=0;

(24) Judgment (C _θ is maximum allowable value) if yes, enter step (27); otherwise, enter step (25);

(25) The current sharing performance of the online power module marked with the serial number m does not meet the requirements;

(26) Update variable Num=Num+1;

(27) update m=m+1;

(28) Judging m<=M? If yes, enter step (24); otherwise, enter step (29);

(29) Offline the Num online power modules whose current sharing performance does not meet the requirements, and start the Num power modules from the backup power supply; then enter step (5).

The embodiment should not be regarded as limiting the invention, but any improvement based on the spirit of the present invention should be within the protection scope of the present invention.

Claims (5)

1. the system ambiguous control method of parallel operation taking into account efficiency and current-sharing index, it is characterised in that: its step is as follows:

(1) the parallel operation system load electric current I of K power module composition is obtained_outFromAccording to being spaced apart Equidistantly change toTime, each power module is at different loads electric currentIn the case of gather V output Electric current Data_curr(m') (i) (j), output voltage Data_volt(m') (i) (j) and input power P (m') (i) (j)；Wherein: m' is Power module sequence number；I is the sequence number value that load current value is corresponding；J is output current acquisition data sequence number；M', i, j meet m'= 1 ... K}, i={1 ... U}, j={1 ... V}；I_NRated current for power module；

(2) power module output current obtaining serial number m' expects electric current with current-sharingRelative deviationWith mathematic expectaion absolute valueObtain K power module At current-sharing expectation electric current it isTime E_m'iMeansigma methodsThe power module obtaining serial number m' is expected in current-sharing Electric current isTime efficiencyWith efficiency mathematic expectaionObtaining K power module at current-sharing expectation electric current isOperating mode under average efficiency

(3) respectively to U data pointWithI ∈ [1, U] matching drawsWith power module load current i it Between relationAnd the relation η=Φ (i) between efficiency eta and power module load current i；

(4) in allowing output current scope, obtain and meetMaximumAnd meetMinimum

(5) with cycle T_sFor interval calculation parallel operation system online power module quantity M, and defeated to M online power module Going out electric current to be acquired, it is currently to exist that the output current data of the online power module of m-th sequence number is labeled as Curr (m), m Line power module sequence number；

(6) the output current data array of the online power module of acquisition serial number m: Curr_store (m) (n)=Curr_ Store (m) (n+1), Curr_store (m) (T)=Curr (m)；Wherein: n=1 ... T-1；M=1,2,3 ... M；T is more than 2 Positive integer, n is the current sample number of times of same online power module；

(7) the output current average of the online power module of acquisition serial number m: Wherein: m=1,2,3 ... M；

(8) load current of the parallel operation system of M online power module composition is obtainedWith online power supply Module current-sharing load current

(9) with I_shareFor input, obtain I respectively_shareWithThe output μ of departure degree membership function^Φ(I_share) and I_shareWith The output μ of departure degree membership function^Ψ(I_share)；

(10) with μ^Φ(I_share) and μ^Ψ(I_share) for inputting, draw corresponding control rule according to fuzzy control rule table and fuzzy reasoning Then, and carry out precision calculating according to fuzzy control centroid method principle ambiguity solution, obtain online power module current adjustment and be subordinate to The exact value of the output current adjustment Δ I of genus degree function mu (Δ I):

(11) judge whether≤σ sets up | Δ I |；

(12) in step (11) | Δ I |≤σ is false, then obtain the online power module of parallel operation system the equal current load of expection Electric current: I_share=I_share+ΔI；

(13) obtaining online power module output current is reference current I_shareTime online power module quantity N^*,

(14)N^*≤ 1 arranges N^*=2；Otherwise, then obtain parallel operation system and need to regulate power module amount Δ N^*=N^*-M；And According to Δ N^*Positive and negative, Centralized Controller is increased or decreased | Δ N^*| individual online power module；

(15) in step (11), | Δ I |≤σ sets up；Then obtain the output electric current Curr_ of the online power module of serial number m Store (m) (n) and current-sharing desired value I_shareDeviation θ (m) (n)=Curr_store (m) (n)-I_share；Wherein: n=1 ... T；M=1,2,3 ... M；

(16) mathematic expectaion of online power module deviation θ (m) (n) of serial number m is obtainedWherein: n= 1 ... T；M=1,2,3 ... M；

(17)Then continue the detection of next online power module, otherwise then marking serial numbers is that the online power module of m is equal Fluidity can be undesirable, C_θForMaximum permissible value；

(18) by Num the undesirable online power module off-line of current-sharing performance, and from stand-by power supply, Num electricity is started Source module works；Continuing the operation of step (5), wherein Num is for being labeled as the undesirable online power module of current-sharing performance Quantity.

The system ambiguous control method of parallel operation taking into account efficiency and current-sharing index the most according to claim 1, its feature It is: step (3) application fitting of a polynomial, curve-fitting method are respectively to U data pointWithi∈[1, U] it is fitted processing.

The system ambiguous control method of parallel operation taking into account efficiency and current-sharing index the most according to claim 1, its feature It is: in step (9), pass through respectively

${\mathrm{\&mu;}}_{NB}^{\mathrm{\&Phi;}}\left(I_{share}\right)=\left\{\begin{array}{cc}1& 0\&le;I_{share}<0.1I_{ref}^1\\ \frac{0.4I_{ref}^1-I_{share}}{0.3I_{ref}^1}& 0.1I_{ref}^1\&le;I_{share}<0.4I_{ref}^1\\ 0& I_{share}>0.4I_{ref}^1\end{array}\right.,$

${\mathrm{\&mu;}}_s^{\mathrm{\&Phi;}}\left(I_{share}\right)=\left\{\begin{array}{cc}0& I_{share}<a_s\\ \frac{I_{share}-a_s}{b_s-a_s}& a_s\&le;I_{share}\&le;b_s\\ \frac{c_s-I_{share}}{c_s-b_s}& b_s\&le;I_{share}\&le;c_s\\ 0& I_{share}>c_s\end{array}\right.,$

${\mathrm{\&mu;}}_{NB}^{\mathrm{\&Psi;}}\left(I_{share}\right)=\left\{\begin{array}{cc}1& 0\&le;I_{share}<0.1I_{ref}^2\\ \frac{0.4I_{ref}^2-I_{share}}{0.3I_{ref}^2}& 0.1I_{ref}^2\&le;I_{share}\&le;0.4I_{ref}^2\\ 0& I_{share}>0.4I_{ref}^2\end{array}\right.,$

${\mathrm{\&mu;}}_s^{\mathrm{\&Psi;}}\left(I_{share}\right)=\left\{\begin{array}{cc}0& I_{share}<a_s^1\\ \frac{I_{share}-a_s^1}{b_s^1-a_s^1}& a_s^1\&le;I_{share}\&le;b_s^1\\ \frac{c_s^1-I_{share}}{c_s^1-b_s^1}& b_s^1\&le;I_{share}\&le;c_s^1\\ 0& I_{share}>c_s^1\end{array}\right.,$

${\mathrm{\&mu;}}_{PB}^{\mathrm{\&Psi;}}\left(I_{share}\right)=\left\{\begin{array}{cc}0& I_{share}<1.6I_{ref}^2\\ \frac{I_{share}-1.6I_{ref}^2}{0.3I_{ref}^2}& 1.6I_{ref}^2\&le;I_{share}\&le;1.9I_{ref}^2\\ 1& I_{share}>1.9I_{ref}^2\end{array}\right.$

Obtain I_shareWithThe output μ of departure degree membership function^Φ(I_share) and I_shareWith departure degree membership function Output μ^Ψ(I_share),

Wherein: s={NM, NS, O, PS, PM}, Unit: Single Position: Unit:

The system ambiguous control method of parallel operation taking into account efficiency and current-sharing index the most according to claim 1, its feature It is: in step (10), pass through

${\mathrm{\&mu;}}_{NB}\left(\mathrm{\&Delta;}I\right)=\left\{\begin{array}{cc}1& \mathrm{\&Delta;}I<-0.6\\ \frac{\mathrm{\&Delta;}I+0.4}{-0.2}& -0.6\&le;\mathrm{\&Delta;}I\&le;-0.4\\ 0& \mathrm{\&Delta;}I>-0.4\end{array}\right.,$

${\mathrm{\&mu;}}_s\left(\mathrm{\&Delta;}I\right)=\left\{\begin{array}{cc}0& \mathrm{\&Delta;}I<a_s^2\\ \frac{\mathrm{\&Delta;}I-a_s^2}{b_s^2-a_s^2}& a_s^2\&le;\mathrm{\&Delta;}I\&le;b_s^2\\ \frac{c_s^2-\mathrm{\&Delta;}I}{c_s^2-b_s^2}& b_s^2\&le;\mathrm{\&Delta;}I\&le;c_s^2\\ 0& \mathrm{\&Delta;}I>c_s^2\end{array}\right.,$

${\mathrm{\&mu;}}_{PB}\left(\mathrm{\&Delta;}I\right)=\left\{\begin{array}{cc}0& \mathrm{\&Delta;}I<0.4\\ \frac{\mathrm{\&Delta;}I-0.4}{0.2}& 0.4\&le;\mathrm{\&Delta;}I\&le;0.6\\ 1& \mathrm{\&Delta;}I>0.6\end{array}\right.$

Obtain online power module current adjustment membership function μ (Δ I),

Wherein: s={NM, NS, O, PS, PM}, Unit: Single Position: Unit:

The system ambiguous control method of parallel operation taking into account efficiency and current-sharing index the most according to claim 1, its feature It is: in step (1)-step (4),

(1) t ∈ ((i-1) T, iT], (U >=i >=1), electronic load current isTime, obtain the equal of power module Stream target reference current:U≥i≥1；

(2) the power module output current sampled data data of serial number m': Data is obtained_curr(m') (i) (j), (K >=m' >= 1, U >=i >=1, V >=j >=1), and obtain its current-sharing relative deviation δ (m') (i) (j):

$\mathrm{\&delta;}\left(m^{\&prime;}\right)\left(i\right)\left(j\right)=\frac{{\mathrm{Data}}_{curr}\left(m^{\&prime;}\right)\left(i\right)\left(j\right)-I_{ref}\left(i\right)}{I_{ref}\left(i\right)};$

(3) power module obtaining serial number m' existsUnder the conditions of relative deviation δ (m') (i) (j) about the mathematics of j Expect absolute value E_m'i:

E_m'iRepresent that the power module of serial number m' existsUnder the conditions of the mathematic expectaion absolute value of relative deviation；

(4) obtaining K power module at current-sharing expectation electric current isTime relative deviation the meansigma methods of mathematic expectaion absolute value:

(5) to U data pointCarry out process to drawAnd the relation between power module load current i: And in allowing output current scope, obtain and meetLoad current

(6) power module obtaining serial number m' existsCondition efficiency eta (m') (i) (j):

$\mathrm{\&eta;}\left(m^{\&prime;}\right)\left(i\right)\left(j\right)=\frac{{\mathrm{Data}}_{curr}\left(m^{\&prime;}\right)\left(i\right)\left(j\right)\&times;{\mathrm{Data}}_{volt}\left(m^{\&prime;}\right)\left(i\right)\left(j\right)}{P\left(m^{\&prime;}\right)\left(i\right)\left(j\right)}\&times;100\%;$

(7) power module obtaining serial number m' existsUnder the conditions of η (m') (i) (j) about the mathematic expectaion of j η_m'i:

${\mathrm{\&eta;}}_{m^{\&prime;}i}=\frac{1}{V}\underset{j=1}{\overset{V}{\&Sigma;}}\mathrm{\&eta;}\left(m^{\&prime;}\right)\left(i\right)\left(j\right),$

η_m'iRepresent that the power module of serial number m' existsUnder the conditions of the meansigma methods of efficiency；

(8) obtaining K power module at current-sharing expectation electric current isOperating mode under average efficiency:

(9) to U data pointCarry out processing the relation drawn between efficiency eta and power module load current i: η= Φ (i), and in allowing output current scope, obtain and meetLoad current