KR102265080B1 - Maximum ppower point tracking apparatus for photovoltaic inverter and its method - Google Patents

Abstract

In the maximum power point tracking device according to the first invention of the present application, when the solar cell array output voltage output from the solar cell array is lower than the DC link command value voltage, it is controlled by the first PWM signal to set the solar cell array output voltage to a predetermined level. a DC/DC boost converter that converts and outputs a DC link voltage (Vdc); a DC/AC inverter controlled by the second PWM signal to convert the smoothed DC link voltage into a commercial grid voltage; a first detector configured to detect an output current and an output voltage of the solar cell array; a maximum power point tracking unit generating a solar cell array reference voltage by using an output current and an output voltage of the solar cell array; a second detector for detecting a grid voltage and a grid current output from the DC/AC inverter; a first PWM generator configured to output the first PWM signal using an output current and an output voltage of the solar cell array and the solar cell array reference voltage when the solar cell array output voltage is lower than a DC link command value voltage; and when the DC link voltage command value is higher than the output voltage of the solar cell array, the DC link command value voltage is used, and when the DC link voltage command value is lower than the output voltage of the solar cell array, the solar cell array reference voltage and a second PWM generator for outputting a second PWM signal using the second PWM signal.

Description

MAXIMUM PPOWER POINT TRACKING APPARATUS FOR PHOTOVOLTAIC INVERTER AND ITS METHOD

The present invention relates to a maximum power point tracking technology, and more particularly, to a maximum power point tracking apparatus and method using the search and omission of a solar inverter under partial shadow conditions.

Photovoltaic (PV) is a method of converting solar energy into electrical energy, and as it can obtain electrical energy anywhere as long as there is sunlight, it is in the spotlight as an energy source without secondary pollution such as noise and vibration, unlike other power generation methods. have. However, solar power generation has a disadvantage that the output power is reduced due to clouds or shade, and it can be used only when the sun is up. Therefore, it is necessary to study the MPPT technique that can use the power of the solar cell to the maximum, and research on it is being actively conducted.

When the solar cell array is partially shaded due to the influence of clouds or buildings, the solar cell characteristic has a number of local maximum power points (LMPPs). At this time, the existing general MPPT techniques, such as P&O, Hill Climbing, and IncCond, do not follow the global maximum power point (GMPP) and stay in the LMPP. Therefore, it is necessary to analyze when multiple LMPPs are generated by partial shading and study the MPPT technique that can track GMPP. Here, GMPP means an actual maximum power point.

MPPT techniques for finding GMPP under partial shade include Particle Swarm Optimization, Two-stage, and Fibonacci search. The Particle Swarm Optimization technique has a disadvantage in that the search time is not constant due to the random variables used for tracking GMPP and the control algorithm is complicated because there are many values selected by the engineer's experience. The two-stage method is a method in which an additional circuit is added to the system, and although there are several LMPPs, it can follow GMPP, but has a disadvantage that an additional circuit is required. The Fibonacci search technique is fast and accurate, but it may miss GMPP in some shading conditions.

Registered Patent No. 10-1403556 Method of estimating maximum power point of grid-connected solar inverter Registered Patent No. 10-1534369 Maximum power point tracking method in solar power generation system Registered Patent No. 10-1138907 Solar cell module using maximum power point tracking technique Registered Patent No. 10-1385692 Maximum power point tracking device and method of solar module

An object of the present invention is to provide a maximum power point tracking device and method using the search and omission of a solar inverter under partial shadow conditions.

In addition, the present invention provides a maximum power point tracking device capable of reducing the loss due to the conversion operation of the DC/DC boost converter by differently controlling the DC/DC boost converter by comparing the DC link voltage command value and the output voltage of the solar cell array. and to provide a method thereof.

The maximum power point tracking device according to the first invention of the present application is controlled by the first PWM signal (PWM1) when the solar cell array output voltage (Vpv) output from the solar cell array is lower than the DC link command value voltage (Vdc*), a DC/DC boost converter 1003 for converting the solar cell array output voltage (Vpv) into a DC link voltage (Vdc) of a predetermined level and outputting it; a smoothing capacitor 1005 for smoothing the DC link voltage Vdc output from the DC/DC boost converter 1003; DC/AC inverter 1007 which is controlled by the second PWM signal PWM2 and converts the smoothed DC link voltage Vdc into a commercial grid voltage Vg; an LC filter 1009 for filtering harmonic components included in the grid voltage Vg output from the DC/AC inverter 1007; a first detection unit 1013 for detecting an output current Ipv and an output voltage Vpv of the solar cell array; a maximum power point tracking unit 1025 for generating a solar cell array reference voltage Vpv_ref by using the output current Ipv and the output voltage Vpv of the solar cell array; a second detection unit 1031 detecting a grid voltage vg applied to the LC filter 1009 and a grid current ig flowing through the LC filter 1009; When the solar cell array output voltage (Vpv) is lower than the DC link command value voltage (Vdc*), the output current (Ipv) and output voltage (Vpv) of the solar cell array and the solar cell array reference voltage (Vpv_ref) are used to a first PWM generator for outputting the first PWM signal PWM1; and when the DC link voltage command value (Vdc*) is higher than the output voltage (Vpv) of the solar cell array, the DC link command value voltage (Vdc*) is used, and the DC link voltage command value (Vdc*) is the solar cell and a second PWM generator that outputs a second PWM signal using the solar cell array reference voltage Vpv_ref when it is lower than the output voltage Vpv of the array.

Preferably, the first PWM generator includes: a first subtractor 1015 for outputting a difference between the output voltage Vpv of the solar cell array and the solar cell array reference voltage Vpv_ref as a solar cell array deviation voltage; a solar cell array deviation voltage gain calculation unit 1017 for multiplying the solar cell array deviation voltage by a gain and outputting a solar cell array deviation voltage gain; a second subtractor 1021 for outputting a difference between the solar cell array deviation voltage gain and an output current Ipv of the solar cell array as a solar cell array deviation current; a solar cell array deviation current gain calculation unit 1021 for multiplying the solar cell array deviation current by a gain and outputting a solar cell array deviation current gain; and a first PWM signal generator 1023 for generating a first PWM signal d1 by using the solar cell array deviation current gain.

Preferably, the second PWM generator is configured to convert the grid voltage (vg) and the grid current (ig) to a d-axis voltage (vde), q-axis voltage (vqe), d-axis current (ide), q of a synchronized coordinate system. a stop/synchronous coordinate conversion unit 1033 that converts the axial current iqe; a third subtractor 1035 for outputting a deviation between the DC link voltage Vdc and a condition voltage according to Equation 7 as a DC deviation voltage; a DC deviation voltage gain calculator 1037 for multiplying the DC deviation voltage output from the third subtractor 1035 by a DC deviation voltage gain to output a reference current iref; a fourth subtractor 1039 for outputting the deviation between the reference current iref output from the DC deviation voltage gain calculator 1037 and the q-axis current iqe of the synchronous coordinate system as a q-axis deviation current; a q-axis deviation voltage gain calculation unit 1041 for outputting a q-axis deviation voltage by multiplying the q-axis deviation current by the q-axis deviation current gain; an adder 1043 for adding the q-axis deviation voltage and the synchronous coordinate system q-axis voltage (vqe) to output a synchronous coordinate system q-axis command value voltage (vqe*); a fifth subtractor 1045 for outputting the deviation between 0 and the d-axis current ide of the synchronous coordinate system as the d-axis deviation current; a d-axis setpoint voltage calculator 1047 for multiplying the d-axis deviation current by a d-axis deviation current gain and outputting a d-axis command value voltage (vde*) in the synchronous coordinate system; Synchronous/stationary coordinate conversion unit converting the q-axis setpoint voltage (vqe*) of the synchronous coordinate system and the d-axis setpoint voltage (vde*) of the synchronous coordinate system into q-axis and d-axis setpoint voltages (vqs*, vds*) of the stationary coordinate system (1049); and a second PWM signal generator 1051 for generating a second PWM signal d2 by using the d-axis command value voltage vds*.

formula

mode 1:

mode 2:

Preferably, the maximum power point follower 1025 detects the array open circuit voltage (Voc_arr) of the solar cell array, and divides the array open circuit voltage (Voc_arr) by the number of series modules (Ns). a first step of setting Voc_mod) and setting a voltage corresponding to a predetermined ratio of the module open circuit voltage (Voc_mod) as a solar cell array reference voltage (Vpv_ref); and comparing the solar cell array current power Ppv with the solar cell array maximum output power Pm (S920) to perform a second step of updating the solar cell array current voltage Vpv.

)만큼 증가시키고, 상기 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 높은 지를 판단하여 최대 전력점의 추적을 종료하고, 전력 변동분(

)이 0.1보다 작거나 같으면, 상기 태양 전지 어레이 기준 전압(Vpv_ref)을 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 유지하고, 상기 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 낮으면, 상기 태양 전지 어레이 출력 전류(Ipv)가 섹션 분할 시점(SDP: Section Dividing Point)인지 판정하는 제3 단계를 더 수행할 수 있다.Preferably, the maximum power point follower 1025 is configured to convert the solar cell array reference voltage Vpv_ref to a predetermined voltage (

), and determining whether the solar cell array reference voltage (Vpv_ref) is higher than the tracking end voltage (Vend) ends the tracking of the maximum power point, and the power variation (

) is less than or equal to 0.1, maintaining the solar cell array reference voltage (Vpv_ref) as the solar cell array tracking maximum output voltage (Vm), and the solar cell array reference voltage (Vpv_ref) is lower than the tracking end voltage (Vend) , a third step of determining whether the solar cell array output current Ipv is a section dividing point (SDP) may be further performed.

Preferably, the maximum power point follower 1025, when the solar cell array output current Ipv is a section division time, the next short-circuit current I _{sc( j+1} ) is the solar cell array output current ( I _pv ) and compare whether the next short-circuit voltage (P _m /I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ) to obtain a predetermined voltage a fourth step of storing the solar cell array reference voltage (V _{pv_ref );} The solar cell array reference voltage (V _{pv_ref} ) is compared with the tracking termination voltage (Vend), and when the solar cell array reference voltage (V _{pv_ref} ) is less than or equal to the tracking termination voltage (Vend), the solar cell array output current (I) _{a fifth step of comparing whether pv} ) is greater than the maximum power point current (0.85I _scj ) and whether a value obtained by dividing the power variation (dp) by the voltage variation (dv) is larger than 0; and if the solar cell array output current (I _pv ) is greater than the maximum power point current (0.85I _scj ), and the value obtained by dividing the power variation (dp) by the voltage variation (dv) is greater than 0, the second step is A sixth step of returning may be further performed.

)이 글로벌 최대전력점의 0.1을 초과하면, 상기 제1 단계로 복귀하는 제9 단계를 더 수행할 수 있다.Preferably, the maximum power point follower 1025, the solar cell array output current (I _pv ) is less than the maximum power point current (0.85I _scj ), or the power variation (dp) is the voltage variation ( dv) is less than 0, the current short-circuit current ( I _{sc j} ) a seventh step of storing the next short-circuit current I _{sc( j+1 )} and returning to the fourth step; If the solar cell array reference voltage (V _{pv_ref} ) is higher than the tracking end voltage (V _end ), the solar cell array reference voltage (V _{pv_ref} ) is the solar cell array tracking maximum output voltage at the global maximum power point (P _{m )} an eighth step of setting (Vm); and power fluctuations during the operation period (

) exceeds 0.1 of the global maximum power point, a ninth step of returning to the first step may be further performed.

Preferably, in the second step, if the solar cell array current power (Ppv) is greater than the solar cell array maximum output power (Pm), the solar cell array current power (Ppv) to the solar cell array maximum output power (Pm) , updating the solar cell array current voltage (Vpv) to the solar cell array tracking maximum output voltage (Vm); and if the solar cell array maximum output power (Pm) is greater than the solar cell array current power (Ppv), maintaining the solar cell array maximum output power (Pm) and the solar cell array tracking maximum output voltage (Vm). .

)은 상기 태양 전지 어레이 현재 전력(Ppv)과 상기 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차를 태양 전지 어레이 추적 최대 출력 전력(Pm)으로 나눈 값이다.Preferably, in the third step, the power variation (

) is a value obtained by dividing the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) by the solar cell array tracking maximum output power (Pm).

Preferably, in the fourth step, if the next short-circuit voltage (P _m /I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the solar The battery array next short circuit voltage (P _m /I _sc(j+1) ) is stored as a solar cell array reference voltage (V _{pv_ref} ), and the next short circuit voltage (P _m /I _sc(j+1) ) is the next short circuit voltage (P m /I sc(j+1) ) If it is lower than the module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ) is converted to the solar cell array reference voltage (V _{pv_ref )} ) is saved as

)만큼 증가시키고, 상기 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 높은 지를 판단하여 최대 전력점의 추적을 종료하고, 전력 변동분(

)이 0.1보다 작거나 같으면, 상기 태양 전지 어레이 기준 전압(Vpv_ref)을 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 유지하고, 상기 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 낮으면, 상기 태양 전지 어레이 출력 전류(Ipv)가 섹션 분할 시점(SDP: Section Dividing Point)인지 판정하는 제3 단계; 상기 태양 전지 어레이 출력 전류(Ipv)가 섹션 분할 시점이면, 차기 단락 전류(I _{sc( j+1)} )를 상기 태양 전지 어레이 출력 전류(I_pv)로 저장하고, 상기 차기 단락 전압(P_m/I_sc(j+1))이 차기 모듈 개방 전압(((j+1)-0.4)*V_{oc_mod})보다 높은지를 비교하여 소정 전압을 태양 전지 어레이 기준 전압(V_{pv_ref})으로 저장하는 제4 단계; 상기 태양 전지 어레이 기준 전압(V_{pv_ref})과 추적 종료 전압(Vend)을 비교하여, 상기 태양 전지 어레이 기준 전압(V_{pv_ref})이 추적 종료 전압(Vend)보다 작거나 같으면 상기 태양 전지 어레이 출력 전류(I_pv)가 최대 전력점 전류(0.85I_scj)보다 크고, 전력 변동분(dp)을 전압 변동분(dv)으로 나눈 값이 0보다 큰지를 비교하는 제5 단계; 상기 태양 전지 어레이 출력 전류(I_pv)가 최대 전력점 전류(0.85I_scj)보다 크고, 상기 전력 변동분(dp)을 상기 전압 변동분(dv)으로 나눈 값이 0보다 크면, 상기 제2 단계로 복귀하는 제6 단계; 상기 태양 전지 어레이 출력 전류(I_pv)가 최대 전력점 전류(0.85I_scj)보다 작거나, 상기 전력 변동분(dp)을 상기 전압 변동분(dv)으로 나눈 값이 0보다 작으면 현재 단락 전류(I _{sc j} )를 차기 단락 전류(I _{sc( j+1 )})로 저장하고, 상기 제4 단계로 복귀하는 제7 단계; 상기 태양 전지 어레이 기준 전압(V_{pv_ref})이 상기 추적 종료 전압(V_end)보다 높으면, 상기 태양 전지 어레이 기준 전압(V_{pv_ref})을 전역 최대 전력 점(P_m)에서의 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 설정하는 제8 단계; 및 동작 구간 동안 전력 변동분(

)이 글로벌 최대전력점의 0.1을 초과하면, 상기 제1 단계로 복귀하는 제9 단계를 포함한다.Further, in the method for tracking the maximum power point according to the second invention of the present application, in the method for tracking the maximum power point of the solar cell array, the array open circuit voltage (Voc_arr) of the solar cell array is detected, and the array open circuit voltage (Voc_arr) A first step of setting a module open circuit voltage (Voc_mod) divided by the number of series modules (Ns), and setting a voltage corresponding to a predetermined ratio of the module open circuit voltage (Voc_mod) as a solar cell array reference voltage (Vpv_ref); a second step of updating the solar cell array current voltage Vpv by comparing the solar cell array current power Ppv with the solar cell array maximum output power Pm (S920); The solar cell array reference voltage (Vpv_ref) is converted to a predetermined voltage (

), and determining whether the solar cell array reference voltage (Vpv_ref) is higher than the tracking end voltage (Vend) ends the tracking of the maximum power point, and the power variation (

) is less than or equal to 0.1, maintaining the solar cell array reference voltage (Vpv_ref) as the solar cell array tracking maximum output voltage (Vm), and the solar cell array reference voltage (Vpv_ref) is lower than the tracking end voltage (Vend) a third step of determining whether the solar cell array output current Ipv is a section dividing point (SDP); When the solar cell array output current Ipv is a section division time, a next short circuit current I _{sc( j+1} ) is stored as the solar cell array output current I _pv , and the next short circuit voltage P _m / A fourth step of storing a predetermined voltage as a solar cell array reference voltage (V _{pv_ref} ) by comparing whether I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod )} ; The solar cell array reference voltage (V _{pv_ref} ) is compared with the tracking termination voltage (Vend), and when the solar cell array reference voltage (V _{pv_ref} ) is less than or equal to the tracking termination voltage (Vend), the solar cell array output current (I) _{a fifth step of comparing whether pv} ) is greater than the maximum power point current (0.85I _scj ) and whether a value obtained by dividing the power variation (dp) by the voltage variation (dv) is larger than 0; If the solar cell array output current (I _pv ) is greater than the maximum power point current (0.85I _scj ), and the value obtained by dividing the power variation (dp) by the voltage variation (dv) is greater than 0, return to the second step a sixth step; If the solar cell array output current (I _pv ) is less than the maximum power point current (0.85I _scj ), or the power variation (dp) divided by the voltage variation (dv) is less than 0, the current short-circuit current ( I _{sc j} ) a seventh step of storing the next short-circuit current I _{sc( j+1 )} and returning to the fourth step; If the solar cell array reference voltage (V _{pv_ref} ) is higher than the tracking end voltage (V _end ), the solar cell array reference voltage (V _{pv_ref} ) is the solar cell array tracking maximum output voltage at the global maximum power point (P _{m )} an eighth step of setting (Vm); and power fluctuations during the operation period (

) exceeds 0.1 of the global maximum power point, and a ninth step of returning to the first step.

Preferably, in the second step, if the solar cell array current power (Ppv) is greater than the solar cell array maximum output power (Pm), the solar cell array current power (Ppv) to the solar cell array maximum output power (Pm) , updating the solar cell array current voltage (Vpv) to the solar cell array tracking maximum output voltage (Vm); and if the solar cell array maximum output power (Pm) is greater than the solar cell array current power (Ppv), maintaining the solar cell array maximum output power (Pm) and the solar cell array tracking maximum output voltage (Vm). .

)은 상기 태양 전지 어레이 현재 전력(Ppv)과 상기 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차를 태양 전지 어레이 추적 최대 출력 전력(Pm)으로 나눈 값이다.Preferably, in the third step, the power variation (

) is a value obtained by dividing the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) by the solar cell array tracking maximum output power (Pm).

Preferably, in the fourth step, if the next short-circuit voltage (P _m /I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the solar The battery array next short circuit voltage (P _m /I _sc(j+1) ) is stored as a solar cell array reference voltage (V _{pv_ref} ), and the next short circuit voltage (P _m /I _sc(j+1) ) is the next short circuit voltage (P m /I sc(j+1) ) If it is lower than the module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ) is converted to the solar cell array reference voltage (V _{pv_ref )} ) is saved as

According to the present invention, it is possible to track the global maximum power point, which is the actual maximum power point, when a plurality of LMPPs are generated by partial shading without using an additional circuit.

In addition, according to the present invention, a loss due to the conversion operation of the DC/DC boost converter can be reduced by controlling the DC/DC boost converter differently by comparing the DC link voltage command value and the output voltage of the solar cell array.

1 is an IV and PV output curve of a typical PV module;
Figure 2 (a) is a PI output characteristic curve of the PV module according to the irradiance condition,
Figure 2 (b) is a PV output characteristic curve of the PV module according to the irradiance condition,
3 is a PV array composed of 3*2 modules;
4 is an IV, PV output characteristic curve in a 3*2 array;
Fig. 5 shows IV and PV output characteristic curves in the case of some shading in a 3*2 array;
6 (a) is a flow chart of global maximum power point tracking operation when GMPP is on the left;
6(b) is a flowchart of global maximum power point tracking operation when GMPP is in the center;
Figure 6 (c) is a global maximum power point tracking operation flow chart when GMPP is on the right side,
7 is a global maximum power point tracking flowchart according to an embodiment of the present invention;
8 is an ESSJ-GMPPT operation PV output characteristic curve according to the present invention;
9 is a global maximum power point tracking flowchart according to another embodiment of the present invention, and
10 is a block diagram of a grid-connected solar inverter system according to an embodiment of the present invention.

Hereinafter, preferred embodiment(s) of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that only the same components are marked with the same reference numerals as much as possible even though they are displayed on different drawings. In addition, in the following description, many specific details such as components of a specific circuit are shown, which are provided to help a more general understanding of the present invention, and it is understood that the present invention can be practiced without these specific details. It will be obvious to those skilled in the art. In the description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is an I-V and P-V output curve of a typical PV module.

Voc_mod and Isc_mod are the open-circuit voltage and short-circuit current of the solar module, respectively, and Pmpp is the maximum power point of the solar module. As shown in FIG. 1 , the solar module has one maximum power point, which is approximately 80% of the open voltage and around 90% of the short circuit current. Therefore, the open-circuit voltage Voc_mod and the short-circuit current Isc_mod are the same as in Equations 1 and 2, respectively.

FIG. 2(a) is a P-I output characteristic curve of a PV module according to irradiance conditions, and FIG. 2(b) is a P-V output characteristic curve of a PV module according to irradiance conditions.

As shown in FIG. 2 , as the radiation is reduced, the output current and the open-circuit voltage are lowered, and the output power is reduced.

3 is a PV array composed of 3*2 modules. The PV array is configured by connecting photovoltaic modules in series and in parallel. The open-circuit voltage increases with the number of modules connected in series, and the short-circuit current increases with the number of modules connected in parallel. Accordingly, the open-circuit voltage (Voc_arr) and the short-circuit current (Isc_arr) of the PV array are expressed by Equations 3 and 4.

Here, Ns is the number of serial modules and Np is the number of parallel modules.

4 is an I-V, P-V output characteristic curve in a 3*2 array, wherein the open-circuit voltage of the 3*2 PV array is three times the module open-circuit voltage, and the short-circuit current is twice the module short-circuit current.

5 is an I-V, P-V output characteristic curve in the case of some shades in a 3*2 array.

In FIG. 3 , when the shading of PV5 occurs 50% and the shading of PV6 completely occurs, the output current of PV5 is halved and the output current of PV6 becomes 0. Therefore, as shown in Fig. 5, several local maximum power points (LMPPs) occur, and one of them becomes global maximum power points (GMPP). At this time, the position of the most power point fluctuates.

5 shows that the positions of the local maximum power point (LMPP) and the global maximum power point (GMPP) follow the position of the maximum power point of each module. Accordingly, the position of the first maximum point Vmpp1 is approximately 0.8Voc_mod, and the second and third maximum points are approximately 1.8Voc_mod and 2.8Voc_mod, respectively.

Therefore, in the case of partial shading, the position of each maximum point can be expressed as in Equation 5.

6(a) is a flowchart of a search-skip-determining global maximum power point tracking operation according to an embodiment of the present invention when GMPP is located on the left, and FIG. 6(b) is when GMPP is located in the center, this view Search-skip-determining global maximum power point tracking operation flow chart according to an embodiment of the present invention, FIG. 6(c) is a search-skip-determining global maximum power point according to an embodiment of the present invention when GMPP is on the right side It is a flowchart of a tracking operation, and FIG. 7 is a flowchart of global maximum power point tracking according to an embodiment of the present invention.

The search-skip-decision global maximum power point tracking method according to an embodiment of the present invention reduces the search voltage range by skipping unnecessary local maximum power points. According to this method, it is possible to quickly follow the maximum power point without additional circuits or sensors. A search-skip-judgment global maximum power point tracking method according to an embodiment of the present invention is described using a 3*2 PV array. In a 3*2 PV array, it can be described as three different locations.

V _{pv_ref} : Solar cell array voltage setpoint

V _{oc_mod} : Solar cell module open voltage

V _{oc_arr} : Solar cell array open-circuit voltage

P _pv , P _{pv_old} , P _{pv_old2} : Solar cell array current output power, previous output power, previous output power

P _m , P _{m_old} : Solar cell array tracking maximum output power, previous tracking maximum output power

V _m , V _{m_old} : Voltage at the solar cell array tracking maximum output power (solar cell array tracking maximum output voltage), the voltage at the previous tracking maximum output power

The meanings of the symbols written in original characters in FIG. 6 are as follows.

① Initialization and start (Initialization)

All switches are turned off, the array open-circuit voltage (Voc_arr) is detected, and the module open-circuit voltage (Voc_mod) is set by dividing the array open-circuit voltage (Voc_arr) by the number of series modules (Ns). A voltage corresponding to 60% of the module open-circuit voltage (Voc_mod) is set as the solar cell array reference voltage (Vpv_ref) (S715). The reason for setting the PV reference voltage (Vpv_ref) to 60% of the module open-circuit voltage (Voc_mod) is to consider an open-circuit voltage error due to temperature and irradiance.

② Search

Comparing the solar cell array current power (Ppv) with the solar cell array maximum output power (Pm) (S720), if the solar cell array current power (Ppv) is greater than the solar cell array maximum output power (Pm), the solar cell array current The power Ppv is updated to the solar cell array maximum output power Pm, and the solar cell array current voltage Vpv is updated to the solar cell array tracking maximum output voltage Vm (S722). If the solar cell array maximum output power Pm is greater than the solar cell array current power Ppv, the solar cell array maximum output power Pm and the solar cell array tracking maximum output voltage Vm are maintained (S724).

)만큼 증가시키고(S725) 태양 전지 어레이 기준 전압(Vpv_ref)과 추적 종료 전압(Vend)을 비교한다(S730). Thereafter, the solar cell array reference voltage (Vpv_ref) is converted to a predetermined voltage variation (

) and compares the solar cell array reference voltage (Vpv_ref) with the tracking end voltage (Vend) (S730).

)을 계산한다(S760). 여기서, 추적 종료 전압(Vend)이라 함은 태양 전지 어레이 개방 전압(Voc_arr)의 90%에 해당하는 전압이다. When the solar cell array reference voltage (Vpv_ref) is higher than the tracking end voltage (Vend), the tracking is terminated, the solar cell array reference voltage (Vpv_ref) is designated as the solar cell array tracking maximum output voltage (Vm), and the solar cell array current power The difference between (Ppv) and the solar array tracking maximum output power (Pm) divided by the solar array tracking maximum output power (Pm) is the power variation (

) is calculated (S760). Here, the tracking end voltage Vend is a voltage corresponding to 90% of the solar cell array open-circuit voltage Voc_arr.

)이 0.1보다 크면, 즉, 태양 전지 어레이 현재 전력(Ppv)과 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차이가 태양 전지 어레이 추적 최대 출력 전력(Pm)의 0.1배보다 크면, 단계 S710으로 회귀하고, 전력 변동분(

)이 0.1보다 작거나 같으면, 즉, 태양 전지 어레이 현재 전력(Ppv)과 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차이가 태양 전지 어레이 추적 최대 출력 전력(Pm)의 0.1배 이하이면, 태양 전지 어레이 기준 전압(Vpv_ref)을 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 유지한다(S770). power variation (

) is greater than 0.1, that is, if the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) is greater than 0.1 times the solar cell array tracking maximum output power (Pm), return to step S710 and the power variation (

) is less than or equal to 0.1, that is, if the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) is less than or equal to 0.1 times the solar cell array tracking maximum output power (Pm), the solar cell The array reference voltage (Vpv_ref) is maintained as the solar cell array tracking maximum output voltage (Vm) (S770).

③ Skip

If the solar cell array reference voltage Vpv_ref is lower than the tracking end voltage Vend, it is determined whether the solar cell array output current Ipv is a section dividing point (SDP) (S735). Here, the section dividing point (SDP) refers to a point at which a power change rate (dp/dv) according to a voltage change changes from negative to positive.

The next short-circuit current I _{sc( j+1} ) is stored as the solar cell array output current I _pv ( S738 ).

The next short-circuit voltage P _m /I _sc(j+1) is set as the solar cell array reference voltage V _{pv_ref} as in Equation 6 (S740), and j is increased by one (S745).

By comparing the solar cell array reference voltage (V _{pv_ref} ) and the tracking end voltage (Vend) (S750), if the solar cell array reference voltage (V _{pv_ref} ) is higher than the tracking ending voltage (Vend), tracking is terminated and the global maximum power point _{The flow advances to the} tracking operation (step S760 ), and if the solar cell array reference voltage V pv_ref is less than or equal to the tracking end voltage Vend, the flow advances to the determination operation.

④ Judgment

_{It is compared whether the} solar cell array output current (I _pv ) is greater than the maximum power point current (0.85I scj ) and whether the value obtained by dividing the power change (dp) by the voltage change (dv) is greater than 0 ( S755 ). If both are large, it returns to the search operation (step S720), and if either one is small, the current short-circuit current I _{sc j} The next short-circuit current I _{sc( j+1 )} is stored ( S765 ) and returns to the skip operation (step S740 ). Here, the reason why the maximum power point current _{is set to 0.85I scj} is that the position of the skip operation point exists at 90% of the solar cell module short-circuit current Isc, and a margin for the current fluctuation range is considered.

⑤ Global maximum power point tracking

If the solar array reference voltage (V _{pv_ref} ) is higher than the tracking end voltage (V _end ) (S750), the solar cell array reference voltage (V _{pv_ref} ) is set to the solar array tracking maximum output voltage at the global maximum power point (P _{m ).} (Vm) (S760). The reason is that there is no case where the maximum power point is greater than 90% _{of the array open-circuit voltage (V oc_arr ).}

)이 동작 구간 동안 글로벌 최대전력점의 0.1배를 초과하는지를 판단하고(S770), 새로운 글로벌 최대전력점을 다시 얻기 위하여 상기 절차들이 반복된다. 여기서, 전력 변동분(

)은 현재 전력(Ppv)과 글로벌 최대전력점(Pm) 사이의 차를 글로벌 최대전력점(Pm)으로 나눈 값이다(S760).After that, the power change (

) is more than 0.1 times the global maximum power point during the operation period (S770), and the above procedures are repeated to obtain a new global maximum power point again. Here, the power variation (

) is a value obtained by dividing the difference between the current power Ppv and the global maximum power point Pm by the global maximum power point Pm (S760).

8 is a P-V output characteristic curve by a global maximum power point tracking operation according to another embodiment of the present invention, and FIG. 9 is a global maximum power point tracking flowchart according to another embodiment of the present invention.

① Initialization and start (Initialization)

All switches are turned off, the array open-circuit voltage (Voc_arr) is detected, and the module open-circuit voltage (Voc_mod) is set by dividing the array open-circuit voltage (Voc_arr) by the number of series modules (Ns). A voltage corresponding to 60% of the module open-circuit voltage (Voc_mod) is set as the solar cell array reference voltage (Vpv_ref) (S915). The reason why the solar cell array reference voltage (Vpv_ref) is set to 60% of the module open-circuit voltage (Voc_mod) is to consider an open-circuit voltage error due to temperature and irradiance.

② Search

Comparing the solar cell array current power (Ppv) with the solar cell array maximum output power (Pm) (S920), if the solar cell array current power (Ppv) is greater than the solar cell array maximum output power (Pm), the solar cell array current The power Ppv is updated to the solar cell array maximum output power Pm, and the solar cell array current voltage Vpv is updated to the solar cell array tracking maximum output voltage Vm (S922). If the solar cell array maximum output power Pm is greater than the solar cell array current power Ppv, the solar cell array maximum output power Pm and the solar cell array tracking maximum output voltage Vm are maintained (S924).

)만큼 증가시키고(S925) 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 높은를 판단하고(S930), 태양 전지 어레이 기준 전압(Vpv_ref)이 추적 종료 전압(Vend)보다 높으면 최대 전력점의 추적을 종료하고, 태양 전지 어레이 기준 전압(Vpv_ref)을 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 지정하고, 태양 전지 어레이 현재 전력(Ppv)과 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차를 태양 전지 어레이 추적 최대 출력 전력(Pm)으로 나눈 전력 변동분(

)을 계산한다(S960). 여기서, 추적 종료 전압(Vend)이라 함은 태양 전지 어레이 개방 전압(Voc_arr)의 90%에 해당하는 전압이다. Thereafter, the solar cell array reference voltage (Vpv_ref) is converted to a predetermined voltage (

) is increased (S925) and it is determined that the solar cell array reference voltage (Vpv_ref) is higher than the tracking end voltage (Vend) (S930), and when the solar cell array reference voltage (Vpv_ref) is higher than the tracking ending voltage (Vend), the maximum power point ends the tracking of the solar cell array, and the solar cell array reference voltage (Vpv_ref) is designated as the solar cell array tracking maximum output voltage (Vm), and the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) is the power variation divided by the solar array tracking maximum output power (Pm) (

) is calculated (S960). Here, the tracking end voltage Vend is a voltage corresponding to 90% of the solar cell array open-circuit voltage Voc_arr.

)이 0.1보다 크면, 즉, 태양 전지 어레이 현재 전력(Ppv)과 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차이가 태양 전지 어레이 추적 최대 출력 전력(Pm)의 0.1배보다 크면, 단계 S910으로 회귀한다. 한편, 전력 변동값(

)이 0.1보다 작거나 같으면, 즉, 태양 전지 어레이 현재 전력(Ppv)과 태양 전지 어레이 추적 최대 출력 전력(Pm)의 차이가 태양 전지 어레이 추적 최대 출력 전력(Pm)의 0.1배 이하이면, 태양 전지 어레이 기준 전압(Vpv_ref)을 태양 전지 어레이 추적 최대 출력 전압(Vm)으로 유지한다(S970). power variation (

) is greater than 0.1, that is, if the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) is greater than 0.1 times the solar cell array tracking maximum output power (Pm), return to step S910 do. On the other hand, the power fluctuation value (

) is less than or equal to 0.1, that is, if the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) is less than or equal to 0.1 times the solar cell array tracking maximum output power (Pm), the solar cell The array reference voltage (Vpv_ref) is maintained as the solar cell array tracking maximum output voltage (Vm) (S970).

③ Skip

If the solar cell array reference voltage Vpv_ref is lower than the tracking end voltage Vend, it is determined whether the solar cell array output current Ipv is a section dividing point (SDP) (S935). Here, the section dividing point (SDP) refers to a point at which a power change rate (dp/dv) according to a voltage change changes from negative to positive.

When the solar cell array output current Ipv is a section dividing point (SDP), the next short-circuit current I _{sc( j+1} ) is stored as the solar cell array output current I _pv ( S938 ).

It is compared whether the next short-circuit voltage P _m /I _sc(j+1 ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod ) ( S940 ).}

If the next short-circuit voltage (P _m /I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), then the solar cell array next short-circuit voltage (P _m /I _{sc( j+1)} ) is stored as the solar cell array reference voltage V _{pv_ref} ( S942 ).

If the next short-circuit voltage (P _m /I _sc(j+1) ) is lower than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), then the next module open-circuit voltage (((j+1)- 0.4)*V _{oc_mod} ) is stored as the solar cell array reference voltage (V _{pv_ref} ) (S944), and j is increased by one (S945).

_{Comparing the} solar cell array reference voltage (V pv_ref ) and the tracking end voltage (Vend) (S950), if the solar cell array reference voltage (V _{pv_ref} ) is higher than the tracking ending voltage (Vend), tracking is terminated and the global maximum power point The flow advances to the following operation (step S960).

On the other hand, if the solar cell array reference voltage V _{pv_ref} is less than or equal to the tracking end voltage Vend, the determination operation S955 proceeds.

④ Judgment

_{It is compared whether the} solar cell array output current (I _pv ) is greater than the maximum power point current (0.85I scj ) and whether the value obtained by dividing the power variation (dp) by the voltage variation (dv) is greater than 0 ( S955 ).

If both are large, it returns to the search operation (step S920), and if either one is small, the current short-circuit current I _{sc j} It stores as the next short-circuit current I _{sc( j+1 )} ( S965 ), and returns to the skip operation (step S940 ). Here, the reason why the maximum power point current _{is set to 0.85I scj} is that the position of the skip operation point exists at 90% of the solar cell module short-circuit current Isc, and a margin for the current fluctuation range is considered.

⑤ Global maximum power point tracking

If the solar cell array reference voltage (V _{pv_ref} ) is higher than the tracking end voltage (V _end ) (S950), the solar cell array reference voltage (V _{pv_ref} ) is set to the solar cell array tracking maximum output voltage at the global maximum power point (P _{m ).} (Vm) (S960). The reason is that there is no case where the maximum power point is higher than 90% of the _{array open-circuit voltage (V oc_arr ).}

)이 동작 구간 동안 글로벌 최대전력점의 0.1을 초과하는지를 판단하고(S970), 초과하면, 다시 새로운 글로벌 최대전력점을 얻기 위하여 상기 절차들이 반복된다. 여기서, 전력 변동분(

)은 현재 전력(Ppv)과 글로벌 최대전력점(Pm) 사이의 차를 글로벌 최대 전력점(Pm)으로 나눈 값이다(S960).After that, the power change (

) exceeds 0.1 of the global maximum power point during the operation period (S970), and if it is exceeded, the above procedures are repeated to obtain a new global maximum power point again. Here, the power variation (

) is a value obtained by dividing the difference between the current power Ppv and the global maximum power point Pm by the global maximum power point Pm (S960).

10 is a block diagram of a grid-connected solar inverter system according to an embodiment of the present invention.

A grid-connected solar inverter system according to an embodiment of the present invention includes a solar cell array 1001, a DC/DC boost converter 1003, a smoothing capacitor 1005, a DC/AC inverter 1007, and an LC filter 1009. , grid voltage 1011 , first detection unit 1013 , first PWM generation unit 1025 , 1027 , 1029 , 1021 , 1023 , maximum power point follower 1025 , second detection unit 1031 , second PWM and generating units 1033 , 1035 , 1037 , 1039 , 1041 , 1043 , 1045 , 1047 , 1049 , 1051 .

The DC/DC boost converter 1003 is controlled by the first PWM signal PWM1 output from the first PWM generator when the solar cell array output voltage Vpv is lower than the DC link command value voltage Vdc* to control the solar cell array The solar cell array output voltage Vpv output from 1001 is converted into a DC link voltage Vdc of a predetermined level and output.

The smoothing capacitor 1005 smoothes the DC link voltage Vdc output from the DC/DC converter 1003 .

The DC/AC inverter 1007 is controlled by the second PWM signal PWM2 output from the second PWM generator to convert the smoothed DC link voltage Vdc into a commercial grid voltage Vg.

The LC filter 1009 filters harmonic components included in the grid voltage Vg output from the DC/AC inverter 1007 .

The first detector 1013 detects the output current Ipv and the output voltage Vpv of the solar cell array 1001 .

The first PWM generator (1025, 1027, 1029, 1021, 1023) is a first subtractor (Vpv) for outputting the difference between the solar cell array output voltage (Vpv) and the solar cell array reference voltage (Vpv_ref) as a solar cell array deviation voltage ( 1015), a solar cell array deviation voltage gain calculation unit 1017 for outputting a solar cell array deviation voltage gain by multiplying the solar cell array deviation voltage by a gain, the solar cell array deviation voltage gain and the output current (Ipv) of the solar cell array A second subtractor 1021 for outputting the deviation of the solar cell array deviation current as a solar cell array deviation current, a solar cell array deviation current gain calculation unit 1021 for outputting a solar cell array deviation current gain by multiplying the solar cell array deviation current by a gain; and a first PWM signal generator 1023 for generating a first PWM signal d1 using the battery array deviation current gain.

The maximum power point follower 1025 generates a solar cell array reference voltage Vpv_ref by using the output current Ipv and the output voltage Vpv of the solar cell array 1001 .

The second detector 1031 detects a grid voltage vg applied to the LC filter 1009 and a grid current ig flowing through the LC filter 1009 .

The second PWM generator (1033, 1035, 1037, 1039, 1041, 1043, 1045, 1047, 1049, 1051) synchronizes the grid voltage (vg) and the grid current (ig) output from the second detector 1031 in a synchronous coordinate system. DC applied to the d-axis voltage (vde), q-axis voltage (vqe), d-axis current (ide), and q-axis current (iqe) of the stationary/synchronous coordinate converter 1033, smoothing capacitor 1005 of The third subtractor 1035, which outputs the deviation of the link voltage Vdc and the condition voltage according to Equation 7 as the DC deviation voltage, multiplies the DC deviation voltage output from the third subtractor 1035 by the DC deviation voltage gain The q-axis deviation of the difference between the reference current (iref) output from the DC deviation voltage gain calculator 1037 outputting the reference current (iref) and the DC deviation voltage gain calculator 1037 and the q-axis current (iqe) of the synchronous coordinate system The q-axis deviation voltage gain calculation unit ( 1041), an adder 1043 that adds the q-axis deviation voltage output from the q-axis deviation voltage gain calculation unit 1041 and the synchronous coordinate system q-axis voltage (vqe) to output the synchronous coordinate system q-axis command value voltage (vqe*); The fifth subtractor 1045, which outputs the deviation of the d-axis current (ide) of the synchronous coordinate system as the d-axis deviation current, is multiplied by the d-axis deviation current gain by the d-axis deviation current output from the fifth subtractor 1045. Synchronous coordinate system q-axis setpoint voltage (vqe*) and d-axis setpoint voltage calculation unit 1047 output from the d-axis setpoint voltage calculation unit 1047, the adder 1043 for outputting the d-axis setpoint voltage (vde*) of the synchronous coordinate system Synchronous/stationary coordinate conversion unit 1049, which converts the synchronous coordinate system d-axis setpoint voltage (vde*) output from the synchronous coordinate system into the q-axis and d-axis setpoint voltages (vqs*, vds*) of the stationary coordinate system (1049) from (1049) and a second PWM signal generator 1051 for generating a second PWM signal d2 by using the output d-axis command value voltage vds*.

, mode 2

, mode 2

1) mode 1

As shown in Equation 7, when the DC link voltage command value (Vdc*) is higher than the output voltage (Vpv) of the solar cell array, the first PWM generator (1025, 1027, 1029, 1021, 1023) is the maximum power point follower ( The solar cell array output voltage Vpv is controlled by generating a first PWM signal using the solar cell array reference voltage Vpv_ref output from 1025 . In addition, the second PWM generator (1033, 1035, 1037, 1039, 1041, 1043, 1045, 1047, 1049, 1051, 1053) generates a second PWM signal and converts the DC link voltage (Vdc) to the DC link command value voltage ( Vdc*).

2) mode 2

On the other hand, if the DC link voltage command value (Vdc*) is lower than the output voltage (Vpv) of the solar cell array, the first PWM generator (1025, 1027, 1029, 1021, 1023) does not output the first PWM signal, The second PWM generator (1033, 1035, 1037, 1039, 1041, 1043, 1045, 1047, 1049, 1051, 1053) generates a second PWM signal and converts the DC link voltage (Vdc) to the solar cell array reference voltage (Vpv_ref) ) to control

The reason for operating in two modes is as follows. To produce power, the DC link voltage (Vdc) must be higher than the peak voltage in the system. Therefore, mode 1 is required when the solar cell array output voltage (Vpv) is lower than the peak voltage in the system.

However, if the solar cell array output voltage Vpv is higher than the peak voltage in the system, the DC link voltage Vdc is higher than the peak voltage in the system. In this case, the DC/DC boost converter 1003 does not need to operate, and losses due to the conversion operation of the DC/DC boost converter 1003 can be reduced in mode 2 .

The embodiments described in this specification and the accompanying drawings are merely illustrative of some of the technical ideas included in the present invention. Therefore, since the embodiments disclosed in the present specification are for explanation rather than limitation of the technical spirit of the present invention, it is obvious that the scope of the technical spirit of the present invention is not limited by these embodiments. Modifications and specific embodiments that can be easily inferred by those skilled in the art within the scope of the technical idea included in the specification and drawings of the present invention should be interpreted as being included in the scope of the present invention.

1001: solar cell array
1003: DC/DC boost converter
1005: smoothing capacitor
1007: DC/AC inverter
1009: LC filter
1011: grid voltage
1013: first detection unit
1021, 1023, 1025, 1027, 1029: first PWM generator
1025: maximum power point follower
1031: second detection unit
1033, 1035, 1037, 1039, 1041, 1043, 1045, 1047, 1049, 1051, 1053: second PWM generator

Claims (14)

delete When the solar cell array output voltage Vpv output from the solar cell array is lower than the DC link command value voltage Vdc*, it is controlled by the first PWM signal PWM1 to convert the solar cell array output voltage Vpv to a predetermined level of direct current. DC/DC boost converter 1003 for converting and outputting the link voltage (Vdc);
a smoothing capacitor 1005 for smoothing the DC link voltage Vdc output from the DC/DC boost converter 1003;
DC/AC inverter 1007 which is controlled by the second PWM signal PWM2 and converts the smoothed DC link voltage Vdc into a commercial grid voltage Vg;
an LC filter 1009 for filtering harmonic components included in the grid voltage Vg output from the DC/AC inverter 1007;
a first detection unit 1013 for detecting an output current Ipv and an output voltage Vpv of the solar cell array;
a maximum power point tracking unit 1025 for generating a solar cell array reference voltage Vpv_ref by using the output current Ipv and the output voltage Vpv of the solar cell array;
a second detection unit 1031 detecting a grid voltage vg applied to the LC filter 1009 and a grid current ig flowing through the LC filter 1009;
When the solar cell array output voltage (Vpv) is lower than the DC link command value voltage (Vdc*), the output current (Ipv) and output voltage (Vpv) of the solar cell array and the solar cell array reference voltage (Vpv_ref) are used to a first PWM generator for outputting the first PWM signal PWM1; and
When the DC link voltage command value (Vdc*) is higher than the output voltage (Vpv) of the solar cell array, the DC link command value voltage (Vdc*) is used, and the DC link voltage command value (Vdc*) is the solar cell array and a second PWM generator for outputting a second PWM signal by using the solar cell array reference voltage (Vpv_ref) when it is lower than the output voltage (Vpv) of
The first PWM generator,
a first subtractor 1015 for outputting a difference between the output voltage Vpv of the solar cell array and the solar cell array reference voltage Vpv_ref as a solar cell array deviation voltage;
a solar cell array deviation voltage gain calculation unit 1017 for multiplying the solar cell array deviation voltage by a gain and outputting a solar cell array deviation voltage gain;
a second subtractor 1021 for outputting a difference between the solar cell array deviation voltage gain and an output current Ipv of the solar cell array as a solar cell array deviation current;
a solar cell array deviation current gain calculation unit 1021 for multiplying the solar cell array deviation current by a gain and outputting a solar cell array deviation current gain; and
A first PWM signal generator 1023 for generating a first PWM signal d1 by using the solar cell array deviation current gain
A maximum power point tracking device comprising a.
The method according to claim 2, The second PWM generator,
Stop/Synchronize converting the grid voltage (vg) and the grid current (ig) into d-axis voltage (vde), q-axis voltage (vqe), d-axis current (ide), and q-axis current (iqe) of a synchronous coordinate system coordinate conversion unit 1033;
a third subtractor 1035 for outputting a deviation between the DC link voltage Vdc and a condition voltage according to Equation 7 as a DC deviation voltage;
a DC deviation voltage gain calculator 1037 for multiplying the DC deviation voltage output from the third subtractor 1035 by a DC deviation voltage gain to output a reference current iref;
a fourth subtractor 1039 for outputting the deviation between the reference current iref output from the DC deviation voltage gain calculator 1037 and the q-axis current iqe of the synchronous coordinate system as a q-axis deviation current;
a q-axis deviation voltage gain calculation unit 1041 for outputting a q-axis deviation voltage by multiplying the q-axis deviation current by the q-axis deviation current gain;
an adder 1043 for adding the q-axis deviation voltage and the synchronous coordinate system q-axis voltage (vqe) to output a synchronous coordinate system q-axis command value voltage (vqe*);
a fifth subtractor 1045 for outputting the deviation between 0 and the d-axis current ide of the synchronous coordinate system as the d-axis deviation current;
a d-axis command value voltage calculation unit 1047 for multiplying the d-axis deviation current by a d-axis deviation current gain to output a d-axis command value voltage (vde*) in the synchronous coordinate system;
Synchronous/stationary coordinate conversion unit converting the q-axis setpoint voltage (vqe*) of the synchronous coordinate system and the d-axis setpoint voltage (vde*) of the synchronous coordinate system into q-axis and d-axis setpoint voltages (vqs*, vds*) of the stationary coordinate system (1049);
A second PWM signal generator 1051 for generating a second PWM signal d2 by using the d-axis command value voltage (vds*)
A maximum power point tracking device comprising a.
formula
mode 1:

mode 2:

The method according to claim 3, The maximum power point follower (1025),
Detects the array open circuit voltage (Voc_arr) of the solar cell array, sets the module open circuit voltage (Voc_mod) obtained by dividing the array open circuit voltage (Voc_arr) by the number of series modules (Ns), and sets a predetermined value of the module open circuit voltage (Voc_mod) a first step of setting a voltage corresponding to the ratio as a solar cell array reference voltage (Vpv_ref); and
A second step of updating the solar cell array current voltage (Vpv) by comparing the solar cell array current power (Ppv) with the solar cell array maximum output power (Pm) (S920)
Maximum power point tracking device, characterized in that performing.
The method according to claim 4, The maximum power point follower (1025),
Then, the solar cell array reference voltage (Vpv_ref) is converted to a predetermined voltage (

), and determining whether the solar cell array reference voltage (Vpv_ref) is higher than the tracking end voltage (Vend) ends the tracking of the maximum power point, and the power variation (

) is less than or equal to 0.1, maintaining the solar cell array reference voltage (Vpv_ref) as the solar cell array tracking maximum output voltage (Vm), and the solar cell array reference voltage (Vpv_ref) is lower than the tracking end voltage (Vend) , further performing a third step of determining whether the solar cell array output current Ipv is a section dividing point (SDP),
The power variation (

) is a value obtained by dividing the difference between the solar cell array current power (Ppv) and the solar cell array tracking maximum output power (Pm) by the solar cell array tracking maximum output power (Pm).
The method according to claim 5, The maximum power point follower (1025),
When the solar cell array output current Ipv is a section division time, a next short circuit current I _{sc( j+1} ) is stored as the solar cell array output current I _pv , and the next short circuit voltage P _m / A fourth step of storing a predetermined voltage as a solar cell array reference voltage (V _{pv_ref} ) by comparing whether I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod )} ;
The solar cell array reference voltage (V _{pv_ref} ) is compared with the tracking termination voltage (Vend), and when the solar cell array reference voltage (V _{pv_ref} ) is less than or equal to the tracking termination voltage (Vend), the solar cell array output current (I) _{a fifth step of comparing whether pv} ) is greater than the maximum power point current (0.85I _scj ) and whether a value obtained by dividing the power variation (dp) by the voltage variation (dv) is larger than 0; and
If the solar cell array output current (I _pv ) is greater than the maximum power point current (0.85I _scj ), and the value obtained by dividing the power variation (dp) by the voltage variation (dv) is greater than 0, return to the second step 6th step to
Maximum power point tracking device, characterized in that it further performs.
delete The method according to claim 6, The second step,
If the solar cell array current power (Ppv) is greater than the solar cell array maximum output power (Pm), then the solar cell array current power (Ppv) is the solar cell array maximum output power (Pm), and the solar cell array current voltage (Vpv) is Updating to a solar array tracking maximum output voltage (Vm); and
If the solar cell array maximum output power (Pm) is greater than the solar cell array current power (Ppv), maintaining the solar cell array maximum output power (Pm) and the solar cell array tracking maximum output voltage (Vm);
A maximum power point tracking device comprising a.
delete 9. The method of claim 8,
In the fourth step, when the next short circuit voltage (P _m /I _sc(j+1) ) is higher than the next module open-circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the solar cell array next short circuit store the voltage (P _m /I _sc(j+1) ) as the solar cell array reference voltage (V _{pv_ref ),}
If the next short circuit voltage (P _m /I _sc(j+1) ) is lower than the next module open circuit voltage (((j+1)-0.4)*V _{oc_mod} ), the next module open circuit voltage (((j+) 1)-0.4)*V _{oc_mod} ) as the solar cell array reference voltage (V _{pv_ref} ), the maximum power point tracking device.
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