CN109185053B - Low-wind-speed power generation algorithm of wind driven generator, implementation method and controller thereof - Google Patents
Low-wind-speed power generation algorithm of wind driven generator, implementation method and controller thereof Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D7/00—Controlling wind motors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2270/00—Control
- F05B2270/30—Control parameters, e.g. input parameters
- F05B2270/32—Wind speeds
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2270/00—Control
- F05B2270/30—Control parameters, e.g. input parameters
- F05B2270/335—Output power or torque
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2270/00—Control
- F05B2270/30—Control parameters, e.g. input parameters
- F05B2270/337—Electrical grid status parameters, e.g. voltage, frequency or power demand
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
The invention discloses a low wind speed power generation algorithm and a realization method of a wind driven generator and a controller thereof. The invention can generate power in breeze state, can not cause the mechanical shaking of the fan or the blocking of the fan, prolongs the service life of the fan, avoids a current sensor, can realize the work effect similar to MPPT only by using a simple BOOST structure, has low cost and improves the product competitiveness.
Description
Technical Field
The invention relates to the field of wind power generation, in particular to a low wind speed power generation algorithm of a wind driven generator, an implementation method and a controller thereof.
Background
When the low-power wind driven generator converts wind energy into electric energy, a controller is required to be connected to carry out charging management on the fan. When the input voltage of the fan is lower than the voltage of the storage battery, a boosting technology is needed to be used, the input voltage is raised, and the battery can be charged.
Boosting is generally done using a BOOST topology. When the characteristics of the fan are not considered, a plurality of manufacturers detect input voltage and current, calculate the input power of the fan, and then adjust the BOOST duty ratio to maximize the input power, namely, the MPPT technology of the fan. The scheme seems to realize power generation at low wind speed, however, the consequence brought by the simple realization method is fatal to the fan, not only is the optimal power generation difficult to realize, but also the MPPT technology is inserted, the power generation amount is worse than the direct charging effect, the fan is caused to operate in a stalled mode for a long time, and the fan is shaken to rotate and is unsmooth, so that the service life of the fan is shortened.
In fact, for a fan, at a wind speed, there is a corresponding optimum operating speed, otherwise the fan will stall. That is, it is necessary to operate at an optimum tip speed ratio to generate electricity at maximum efficiency. For low power wind generators (within 600W), under general wind resource environment, the energy conversion at low wind speed is more important.
And because the input energy is less under low wind speed, even if the real MPPT technology is adopted, the MPPT technology is influenced by cost and material precision, the ideal power generation effect is difficult to achieve, and the cost performance is poor.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a low-wind-speed power generation algorithm of a wind driven generator, an implementation method and a controller thereof. Even very low wind speed can also convert wind energy into electric energy and charge the battery to can realize similar MPPT effect at low wind speed, and the price/performance ratio is also very high.
In order to achieve the technical purpose, the invention adopts the following technical scheme: a low wind speed power generation algorithm of a wind driven generator is characterized by firstly constructing a boost technical topological structure, aiming at achieving the purpose that the wind driven generator stably runs at low wind speed and is close to the optimal power generation state, utilizing the inductance work in the boost technical topological structure to calculate under a DCM mode to obtain the actual dynamic impedance and equivalent input power for a fan, inputting the equivalent input power into a wind speed energy formula to obtain a PWM duty ratio and introducing a correction coefficient, and finally controlling the PWM duty ratio and the correction coefficient to realize the optimal power generation of the fan at low wind speed;
the boost technology topological structure comprises a three-phase rectifier bridge, a filter capacitor C, an inductor L, a diode D, MOS tube Q and a storage battery GB;
the algorithm comprises the following steps:
s1: calculating the average current input by the fan and the equivalent load input by the fan according to an average formula of triangular wave current and an inductance theory;
s2: calculating equivalent input power of the fan according to the average current input by the fan;
s3: comparing the equivalent input power of the fan with the wind speed energy, so that the energy input by the wind speed and the duty ratio of PWM conform to a functional relation:
according to the wind speed energy formula:
W＝(1/2)ρv3⑨
it is known that: the energy generated by the wind speed is proportional to the 3 rd power of the wind speed, where ρ is the air density;
since the controllable parameter in the boost booster is the input PWM duty cycle, that is, Ton is controllable, comparing equation ⑧ with equation ⑨, in order to equate the 3 rd power relationship of wind speed energy to the 3 rd power relationship of PWM duty cycle, the following equation should be satisfied:
formula ⑩ is a calculation formula of the PWM duty ratio, where K is an introduced correction coefficient, a range of the K coefficient is deduced according to a range of the input voltage and the PWM period, and a constraint formula of the K coefficient is:
wherein Umax is the maximum fan input voltage, Uo is the battery voltage, and T is the PWM period;
when the formula ⑩ is satisfied, the equivalent output power of the fan is:
meanwhile, the K coefficient needs to satisfy the following relationship:
from formula ⑨ and formula
It can be seen that the energy input by the wind speed is directly proportional to the duty ratio of the PWM, that is, at a certain wind speed, the fan has an optimal rotation speed to indicate an optimal power generation state;
s4, according to a formula ⑩, a proper K coefficient is selected, and the power generation effect of the fan at low wind speed is close to the MPPT effect.
Preferably, in the boost technology topological structure, an input end of the three-phase rectifier bridge is connected with the fan, one output end of the three-phase rectifier bridge is grounded, and the other output end of the three-phase rectifier bridge is connected with the anode of the filter capacitor C; the positive pole of filter capacitor C connects the inductance L anodal, inductance L negative pole connects the diode D anodal, the diode D anodal connects MOS pipe Q anodal, diode D negative pole connects storage battery GB anodal, filter capacitor C negative pole, MOS pipe negative pole, battery negative pole all ground connection.
Preferably, in step S1, the average formula of the triangular wave current is:
Idc＝(D*Im)/2 ①
wherein D is a PWM duty ratio, and Im is an inductance peak current;
and D ═ T ② (Ton + Toff)/T
Wherein Ton is an opening time, Toff is a time when the current follow current section is reduced to 0, and T is a PWM period;
the theory of the inductance is as follows:
Ton＝(Im*L)/Uin ③
Toff＝(Im*L)/(Uo-Uin) ④
wherein, L is inductance, Uin is input voltage after the fan rectifies, Uo is output voltage, and Uo is storage battery voltage for an off-grid charging system;
and (3) combining the ①②③④ formulas to obtain the average current of the fan input:
the effective constraint of equation ⑤ is:
according to the input load being equal to the input voltage divided by the equivalent average current, namely: r is equal to Uin/I,
calculating to obtain the equivalent input load of the air outlet machine as follows:
preferably, in step S2, since the input power is equal to the input voltage multiplied by the equivalent average current, that is: w ═ Uin |,
the equivalent input power is calculated according to equation ⑤ as:
a method for implementing a low wind speed power generation algorithm of a wind power generator, the method using the low wind speed power generation algorithm of the wind power generator as claimed in any one of claims 1-4, comprising the steps of:
the method comprises the following steps of firstly, introducing two parameters, namely a maximum load ratio of the fan, a maximum ratio value allowed to be output by PWM duty ratio under a limited input voltage, namely a K coefficient of an equation ⑩, and secondly, MPPT starting voltage, introducing algorithm PWM boosting when the input voltage is higher than the parameter value, namely starting power generation when a certain wind speed is reached, and avoiding the stop of the fan;
secondly, sampling the input voltage of the fan and the voltage of the storage battery;
thirdly, calculating the PWM duty ratio according to the parameter I of the first step and the sampling result of the second step and a formula ⑩;
step four, verifying whether a formula ⑥ is established or not, substituting the result of the step three into a formula ⑥, if the formula ⑥ is not established, taking the maximum Ton value which enables the formula ⑥ to be established, namely the maximum PWM duty ratio, and if the formula ⑥ is established, continuing the step five;
and fifthly, outputting the PWM duty ratio obtained in the previous step to an MOS tube.
A controller, the controller being a wind turbine controller or a wind-solar hybrid controller, the wind turbine controller or the wind-solar hybrid controller using the low wind speed power generation algorithm of the wind turbine generator as claimed in claim 1.
In conclusion, the invention achieves the following beneficial effects:
1. the fan can generate power in a breeze state;
2. the invention can not cause the mechanical shaking of the fan or the blocking of the fan, thereby prolonging the service life of the fan;
3. a current sensor is eliminated, and the work effect of approximate MPPT can be realized only by using a simple BOOST structure;
4. the cost is low, and the product competitiveness is improved;
drawings
FIG. 1 is a circuit diagram of a boost topology of the present invention;
fig. 2 is a schematic diagram of a PWM wave filter circuit;
FIG. 3 is a graph of the current voltage waveform of the inductor of the present invention;
FIG. 4 is a parameter one in an embodiment;
FIG. 5 is parameter two in the example;
in the figure, 1 is a fan, 2 is a three-phase rectifier bridge.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Example (b):
a low wind speed power generation algorithm of a wind driven generator is characterized by firstly building a boost technical topological structure, aiming at achieving the purpose that the wind driven generator stably runs at low wind speed and is close to the optimal power generation state, utilizing inductance work in the boost technical topological structure to calculate under a DCM mode to obtain actual dynamic impedance and equivalent input power for a fan, inputting the equivalent input power into a wind speed energy formula to obtain a PWM duty ratio and introducing a correction coefficient, and finally controlling the PWM duty ratio and the correction coefficient to achieve the optimal power generation of the fan at low wind speed;
the boost technology topological structure comprises a three-phase rectifier bridge, a filter capacitor C, an inductor L, a diode D, MOS tube Q and a storage battery GB;
the algorithm comprises the following steps:
s1: calculating the average current input by the fan and the equivalent load input by the fan according to an average formula of triangular wave current and an inductance theory;
s2: calculating equivalent input power of the fan according to the average current input by the fan;
s3: comparing the equivalent input power of the fan with the wind speed energy, so that the energy input by the wind speed and the duty ratio of PWM conform to a functional relation:
according to the wind speed energy formula:
W＝(1/2)ρv3⑨
it is known that: the energy generated by the wind speed is proportional to the 3 rd power of the wind speed, where ρ is the air density;
since the controllable parameter in the boost booster is the input PWM duty cycle, that is, Ton is controllable, comparing equation ⑧ with equation ⑨, in order to equate the 3 rd power relationship of wind speed energy to the 3 rd power relationship of PWM duty cycle, the following equation should be satisfied:
formula ⑩ is a calculation formula of the PWM duty ratio, where K is an introduced correction coefficient, a range of the K coefficient is deduced according to a range of the input voltage and the PWM period, and a constraint formula of the K coefficient is:
wherein Umax is the maximum fan input voltage, Uo is the battery voltage, and T is the PWM period;
when the formula ⑩ is satisfied, the equivalent output power of the fan is:
meanwhile, the K coefficient needs to satisfy the following relationship:
from formula ⑨ and formula
It can be seen that the energy input by the wind speed is directly proportional to the duty ratio of the PWM, that is, at a certain wind speed, the fan has an optimal rotation speed to indicate an optimal power generation state;
s4, according to a formula ⑩, a proper K coefficient is selected, and the power generation effect of the fan at low wind speed is close to the MPPT effect.
In the boost technology topological structure, the input end of the three-phase rectifier bridge is connected with the fan, one path of the output end is grounded, and the other path is connected with the anode of the filter capacitor C; the positive pole of filter capacitor C connects the inductance L anodal, inductance L negative pole connects the diode D anodal, the diode D anodal connects MOS pipe Q anodal, the diode D negative pole connects the battery GB anodal, filter capacitor C negative pole, MOS pipe negative pole, the equal ground connection of battery negative pole. A current sensor is not installed in the circuit, the MOS tube is controlled by the MCU to boost and generate power, the MCU obtains an output duty ratio after algorithm, and the output duty ratio is output to a drive circuit of the MOS tube through an output pin, so that the MOS works in a PWM state.
As shown in fig. 1, for the wind turbine, the load is a BOOST-structured PWM chopper, and the PWM wave is filtered into a direct current after passing through a filter capacitor C and an inductor, as shown in fig. 2. For the PWM wave, from the microcosmic, every chopping cycle all can bring the current variation, follows inductance current change law, and the current voltage waveform of inductance is as shown in fig. 3, and at the beginning of PWM wave cycle, when MOS pipe switches on promptly, fan input voltage passes through the inductance, charges inductance energy storage, and inductance current slope rises, forms the triangle current wave IL of cycle, and the MOS pipe is closed when the current rises to IM, and inductance current slope descends, and the decline terminal has two kinds of condition: 1. when the current is not reduced to 0, the next PWM wave starts, namely, the inductor current is in a continuous state, and the CCM mode is adopted; 2. after the current drops to 0, the next PWM wave starts, i.e. the inductor current is discontinuous, which is in DCM. For the first case, without discussing the scope herein, only the case when the inductor is operating in DCM is discussed herein. The invention artificially utilizes the inductor to work in a DCM state to obtain the actual dynamic impedance for the fan, and controls the dynamic impedance to realize the stable power generation of the fan at low wind speed.
In step S1, the average formula of the triangular wave current is:
Idc＝(D*Im)/2 ①
wherein D is a PWM duty ratio, and Im is an inductance peak current;
and D ═ T ② (Ton + Toff)/T
Wherein Ton is an opening time, Toff is a time when the current follow current section is reduced to 0, and T is a PWM period;
the theory of the inductance is as follows:
Ton＝(Im*L)/Uin ③
Toff＝(Im*L)/(Uo-Uin) ④
wherein, L is inductance, Uin is input voltage after the fan rectifies, Uo is output voltage, and Uo is storage battery voltage for an off-grid charging system;
and (3) combining the ①②③④ formulas to obtain the average current of the fan input:
the effective constraint of equation ⑤ is:
according to the input load being equal to the input voltage divided by the equivalent average current, namely: r is equal to Uin/I,
calculating to obtain the equivalent input load of the air outlet machine as follows:
in step S2, since the input power is equal to the input voltage multiplied by the equivalent average current, that is: w ═ Uin |,
the equivalent input power is calculated according to equation ⑤ as:
the above calculation is true only after the input voltage and the wind speed of the fan are clear, that is, the input voltage of the fan is used to replace the detection of the wind speed. Neglecting the influence of other factors, after a wind driven generator is determined, the characteristics of the wind driven generator are fixed, and at a certain wind speed, the wind driven generator has an optimal rotating speed to indicate an optimal power generation state.
The power drawn according to the current load is:
in the above equation, Kp is the wind energy conversion coefficient, i.e. it represents how much wind power is converted into electrical power. As can be seen from the equation, KP is not fixed, and changing the load R also changes the value of KP, i.e., KP is a function of the load R. The input voltage and the fan power output are not linearly related.
When BOOST power generation is carried out by using a BOOST structure, a reasonable K coefficient is preferably selected, PWM duty ratio is calculated according to fan input voltage and a formula ⑩, the PWM duty ratio is enabled to meet the condition that the inductor works in a DCM state, namely the formula ⑥ is met, when the formula ⑥ is not met, a maximum Ton value which can enable the formula ⑥ to be established is selected, output power is adjusted continuously according to the input voltage and the output voltage, the output power is enabled to be in direct proportion to a specific wind speed, the output power is enabled to be close to the power obtained by an MPPT algorithm at the moment, the calculated PWM duty ratio is output to a control MOS (metal oxide semiconductor) tube and a PWM (pulse width modulation) switch of the BOOST, and the optimal working.
It can be seen from the above calculations that a reasonable K-factor is preferred, the duty ratio of the current operation can be calculated according to the formula ⑩, and the output power can be proportional to the specific wind speed according to the continuous adjustment of the input and output voltages, and the output power is also close to the power obtained by the MPPT algorithm.
According to the invention, boost power generation is realized by adopting a boost technology topological structure, dynamic impedance and equivalent input power of the fan working in a DCM mode through an inductor are shown as a formula ⑦, the equivalent input power is shown as a formula ⑧, the equivalent input power of the fan is compared with wind speed energy, a K coefficient is introduced after the wind speed input energy and the PWM duty ratio conform to a functional relation, the PWM duty ratio is obtained by calculation, and the optimal working state of the fan is obtained in real time after continuous adjustment according to input and output voltages.
A method for realizing a low wind speed power generation algorithm of a wind driven generator adopts a low wind speed power generation algorithm of the wind driven generator and comprises the following steps:
in the first step, two parameters are introduced, one is the maximum load ratio of the fan, as shown in figure 4,
the parameter is used for defining the maximum proportion value of the PWM duty ratio allowed to be output under a limited input voltage, and as can be seen from equation 7, the parameter is indirectly used for limiting the equivalent input load externally connected with the fan to be not more than a value, for example, for a 24V system, the maximum load proportion of the fan defines the maximum PWM duty ratio under the condition that the input voltage of the fan is 24V, and in fact, the maximum load proportion of the fan represents the relation between the wind speed and the equivalent proportion K of the fan load, namely the K coefficient of equation ⑩.
The second parameter is the MPPT start voltage, as shown in figure 5,
the MPPT starting voltage means that when the input voltage is higher than the parameter value, the algorithm PWM boosting is introduced, namely, the power generation is started when a certain wind speed is reached, and the stop of a fan is avoided; for a 24V system, parameter two defines the range from MPPT turn-on voltage to 24V to execute the present core algorithm.
Secondly, sampling the input voltage and the voltage of the storage battery;
thirdly, calculating the PWM duty ratio according to the parameter I of the first step and the sampling result of the second step and a formula ⑩;
step four, verifying whether a formula ⑥ is established or not, substituting the result of the step three into a formula ⑥, if the formula ⑥ is not established, taking the maximum Ton value which enables the formula ⑥ to be established, namely the maximum PWM duty ratio, and if the formula ⑥ is established, continuing the step five;
and fifthly, outputting the PWM duty ratio obtained in the previous step to an MOS tube.
The inductance is not too large, the inductance is 60uH, the PWM working frequency is 16khz, the MOS tube is RU120N15 model, and the MCU singlechip is R5F21258 model.
Because the theoretical calculation of the K coefficient only has a range value, when the system is actually applied, a wind speed power generation test is carried out according to different wind speeds of different fans to confirm the value of K. Through a large number of tests of 50W, 100W, 200W, 300W and 400W wind driven generators, the load proportion is set to be between 10% and 15% reasonably under the natural wind environment. The fan can generate electricity in a state close to the optimal state at low wind speed; because the input fan voltage is changed slowly, the calculated Ton does not have jump, so the fan runs under natural wind, is smooth and does not bring mechanical jitter.
The controller is a fan controller or a wind-solar hybrid controller, and the fan controller or the wind-solar hybrid controller adopts the low-wind-speed power generation algorithm of the wind driven generator.
The invention can realize low-wind-speed stable power generation close to the MPPT effect by only detecting the input voltage of the fan and the voltage of the storage battery without a current sensor.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the present invention in any way, and all simple modifications, equivalent variations and modifications made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (4)
1. A low wind speed power generation algorithm of a wind driven generator is characterized in that:
firstly, building a boost technical topological structure, aiming at the condition that a wind driven generator stably runs at low wind speed and is close to the optimal power generation state, calculating to obtain the actual dynamic impedance and equivalent input power for a fan by utilizing the inductor in the boost technical topological structure in a DCM (direct current modulation) mode, inputting the equivalent input power into a wind speed energy formula to obtain a PWM (pulse-width modulation) duty ratio and introduce a correction coefficient, and finally controlling the PWM duty ratio and the correction coefficient to realize the optimal power generation of the fan at low wind speed;
the boost technology topological structure comprises a three-phase rectifier bridge, a filter capacitor C, an inductor L, a diode D, MOS tube Q and a storage battery GB;
the algorithm comprises the following steps:
s1: calculating the average current input by the fan and the equivalent load input by the fan according to an average formula of triangular wave current and an inductance theory;
wherein, the average formula of the triangular wave current is as follows:
Idc＝(D*Im)/2 ①
wherein D is a PWM duty ratio, and Im is an inductance peak current;
and D ═ T ② (Ton + Toff)/T
Wherein Ton is an opening time, Toff is a time when the current follow current section is reduced to 0, and T is a PWM period;
the theory of the inductance is as follows:
Ton＝(Im*L)/Uin ③
Toff＝(Im*L)/(Uo-Uin) ④
wherein, L is inductance, Uin is input voltage after the fan rectifies, Uo is output voltage, and Uo is storage battery voltage for an off-grid charging system;
and (3) combining the ①②③④ formulas to obtain the average current of the fan input:
the effective constraint of equation ⑤ is:
according to the input load being equal to the input voltage divided by the equivalent average current, namely: r is equal to Uin/I,
calculating to obtain the equivalent input load of the air outlet machine as follows:
s2: calculating equivalent input power of the fan according to the average current input by the fan;
wherein, since the input power is equal to the input voltage multiplied by the equivalent average current, namely: w ═ Uin |,
the equivalent input power is calculated according to equation ⑤ as:
s3: comparing the equivalent input power of the fan with the wind speed energy, so that the wind speed input energy and the duty ratio of PWM (pulse-width modulation) conform to the functional relationship:
according to the wind speed energy formula:
W＝(1/2)ρv3⑨
it is known that: the energy generated by the wind speed is proportional to the 3 rd power of the wind speed, where ρ is the air density;
since the controllable parameter in the boost booster is the input PWM duty cycle, that is, Ton is controllable, comparing equation ⑧ with equation ⑨, in order to equate the 3 rd power relationship of wind speed energy to the 3 rd power relationship of PWM duty cycle, the following equation should be satisfied:
formula ⑩ is a calculation formula of the PWM duty ratio, where K is an introduced correction coefficient, a range of the K coefficient is deduced according to a range of the input voltage and the PWM period, and a constraint formula of the K coefficient is:
wherein Umax is the maximum fan input voltage, Uo is the battery voltage, and T is the PWM period;
when the formula ⑩ is satisfied, the equivalent output power of the fan is:
meanwhile, the K coefficient needs to satisfy the following relationship:
from formula ⑨ and formulaIt can be seen that the energy input by the wind speed is directly proportional to the duty ratio of the PWM, that is, at a certain wind speed, the fan has an optimal rotation speed to indicate an optimal power generation state;
s4, according to a formula ⑩, a proper K coefficient is selected, and the power generation effect of the fan at low wind speed is close to the MPPT effect.
2. The wind turbine low wind speed power generation algorithm of claim 1, wherein: in the boost technology topological structure, the input end of the three-phase rectifier bridge is connected with the fan, one path of the output end is grounded, and the other path is connected with the anode of the filter capacitor C; the positive pole of filter capacitor C connects the inductance L anodal, inductance L negative pole connects the diode D anodal, the diode D anodal connects MOS pipe Q anodal, diode D negative pole connects battery GB anodal, filter capacitor C negative pole, MOS pipe negative pole, battery negative pole all ground connection.
3. A method for implementing a low wind speed power generation algorithm of a wind power generator, wherein the method adopts the low wind speed power generation algorithm of the wind power generator according to any one of claims 1-2, and comprises the following steps:
the method comprises the following steps of firstly, introducing two parameters, namely a maximum load ratio of the fan, a maximum ratio value allowed to be output by PWM duty ratio under a limited input voltage, namely a K coefficient of an equation ⑩, and secondly, MPPT starting voltage, introducing algorithm PWM boosting when the input voltage is higher than the parameter value, namely starting power generation when a certain wind speed is reached, and avoiding the stop of the fan;
secondly, sampling the input voltage of the fan and the voltage of the storage battery;
thirdly, calculating the PWM duty ratio according to the parameter I of the first step and the sampling result of the second step and a formula ⑩;
step four, verifying whether a formula ⑥ is established or not, substituting the result of the step three into a formula ⑥, if the formula ⑥ is not established, taking the maximum Ton value which enables the formula ⑥ to be established, namely the maximum PWM duty ratio, and if the formula ⑥ is established, continuing the step five;
and fifthly, outputting the PWM duty ratio obtained in the previous step to an MOS tube.
4. A controller, characterized by: the controller is a fan controller or a wind-solar hybrid controller, and the fan controller or the wind-solar hybrid controller adopts the low wind speed power generation algorithm of the wind driven generator according to claim 1.
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