CN102012714A - Tracking method and circuit of maximum power of solar panel - Google Patents

Abstract

The invention relates to tracking method and circuit of the maximum power of a solar panel. The tracking method comprises the following steps of: executing the load increasing and decreasing operation of the solar panel through a preset current difference value; and judging that the solar panel is operated in an A area or a B area through the change of the output voltage of the solar panel before and after the load increasing and decreasing operation so as to decide a next round of load increasing and decreasing operation. Thus the output power of the solar panel is estimated without using a multiplier in a maximum power tracking calculation process so as to simplify the tracking circuit of the maximum power of the solar panel, therefore the purpose of forming an integrated circuit chip which has a maximum power tracking function by combining with the traditional pulse width modulation circuit can be realized.

Description

Solar panels maximum power tracing method and circuit

Technical field

The present invention relates to the application of a kind of solar panels (photo-voltaic array), and be particularly related to a kind of solar panels maximum power tracing method and circuit.

Background technology

Exhaustion along with fossil energy, exploitation as renewable sources of energy such as sun power, become the megatrend of pursuing green energy resource now, therefore, solar power system also has been widely used in the power-supply unit of household appliances equipment, communication system, traffic sign and illuminator etc.

Please refer to shown in Figure 1ly, in the application of solar power system, with solar panels 11 sun power is converted to electric energy usually, supply power to load 13 through converter (Converter) 12 or transverter (Inverter) again.Wherein, in order to improve the effective utilization of solar panels 11, and comprise the maximum power tracing circuit 15 of maximum power tracing unit 151, current control unit 152, pulse wave width modulation unit 153 and drive element of the grid 154 among the use figure, control solar panels 11 are operated on the maximum power point (Maximum Power Point is called for short MPP).

Please refer to shown in Figure 2ly, it is the photoelectric characteristic curve of known a kind of solar panels.By among the figure as can be known, under the situation of different sun power illumination, the output power P of solar panels _PV, along with the increase of sun power output illumination and increase, and under the situation of identical sun power illumination, the output power P of solar panels then _PV, will be according to the maximum power point P among the figure _MAXDivide into A district and B district.When solar panels operate in the A district, the output power P of solar panels _PVCan be along with the output voltage V of solar panels _PVIncrease and increase, and when solar panels operate in the B district, the output power P of solar panels _PVThen along with the output voltage V of solar panels _PVIncrease and descend.

Therefore, known is often to use a kind of disturbance and observation, comes sun-tracing energy peak power, and the operation chart of its tracking as shown in Figure 3.Among the figure, solid line is represented the photoelectric characteristic curve of solar panels under same illumination; Power operation curve when the dotted line of solid line top is represented increment of load; Power operation curve when the dotted line of solid line below is represented load shedding.

As shown in the figure, when solar panels operate in the B district, suppose bearing power by the D1 increment of load to C11, this moment since bearing power should equate with the output power of solar panels, so the real work of solar panels point is will past solid line direction parallel mobile and operate in the D2 point.In like manner, when moving toward C12 when bearing power continuation increment of load and by D2, the working point of solar panels also will be moved toward the D3 point is parallel by C12.The rest may be inferred, when bearing power continues increment of load to C1 (m-1) point, also will equal bearing power because of the output power of solar panels, makes solar panels operate on the maximum power point Dm.

At this moment, as increment of load is to the C1m point once more, the operation of solar panels will enter the A district, and because of load is provided by solar panels, so when load increment of load during to the C1m point, its actual operating voltage should be identical with the output voltage of solar panels, or load terminal voltage should with the solar panels output voltage V _PVK is arranged _VValue proportionate relationship (K _VValue is the transfer function of converter output to input voltage), according to load terminal voltage and solar panels output voltage V _PVTransformational relation, also can find C1m corresponding to the some Dm+1 on the solar panels photoelectric characteristic curve.Among the figure, suppose K _VValue equals 1, then load terminal voltage and solar panels output voltage V _PVEquate, so the point of the real work on the solar panels will operate in the Dm+1 point toward solid line direction vertical moving.In like manner, when load continuation increase, the real work point of solar panels also will be moved toward Dn by Dm gradually, can move to the O point at last.

Otherwise, when bearing power is reduced to C2 (n-1) by the Dn point on the solar panels photoelectric characteristic curve, suppose K _VValue equals 1, then load terminal voltage and solar panels output voltage V _PVEquate, so the point of the real work on the solar panels will operate on the Dn-1 toward solid line direction vertical moving.If the rest may be inferred, and the working point of solar panels will reduce and moves toward maximum power point Dm along with bearing power, and when continuing to reduce load, and the working point of solar panels will be moved by the direction that Dm continue past D1.

The old friend, the disturbance and the observation of the maximum power tracing unit 151 applied sun-tracings energy plate peak powers of Fig. 1 are the output power P that increases the solar panels of load shedding operation front and back with detection _PVWith output voltage V _PVVariation, judge that solar panels are operated in A or B district, determine next step should carry out increment of load or load shedding operation more according to this, make the working point of solar panels, maximum power point Dm on the photoelectric characteristic curve moved in the past, near and then operate on the maximum power point Dm, or disturbance maximum power point Dm.

Please refer to shown in Figure 4ly, it is the operational flowchart that known a kind of solar panels use disturbance and observation tracking peak power.In step 41, maximum power tracing unit 151 can detect the output voltage V of solar panels _PV(V _n) and output current I _PV(I _n), and calculate its output power P according to this _PV(P _n), enter step 411 then, increase the output power P of the forward and backward solar panels of load shedding operation with judgement _b, P _nVariation, and when the output power of solar panels becomes big after increasing load shedding operation, enter step 412 increases the forward and backward solar panels of load shedding operation with judgement output voltage V _b, V _nVariation, as increase when the output voltage of solar panels also becomes big after the load shedding operation, represent solar panels to operate in the A district, answer execution in step 413, thereby increase load shedding operation order D=1 to set, carry out load shedding operation, and as increase when the output voltage of solar panels diminishes after the load shedding operation, represent solar panels to operate in the B district, answer execution in step 414, thereby increase load shedding operation order D=0 to set, carry out the increment of load operation.

Otherwise, when step 411 judges that solar panels output power after increasing load shedding operation does not become big, enter in the step 421, increase that solar panels output power after the load shedding operation diminishes or constant with decision.As when diminishing, enter step 422 increases the forward and backward solar panels of load shedding operation with judgement output voltage V again _b, V _nVariation, as increase when the output voltage of solar panels also diminishes after the load shedding operation, represent solar panels to operate in the A district, answer execution in step 424, thereby increase load shedding operation order D=1 to set, carry out load shedding operation, and as increase when the output voltage of solar panels becomes big after the load shedding operation, represent solar panels to operate in the B district, answer execution in step 423, thereby increase load shedding operation order D=0 to set, carry out the increment of load operation.

When judging that in step 421 the solar panels output power increase after the load shedding operation does not change, then should enter step 431, increase the output voltage V of the forward and backward solar panels of load shedding operation with judgement _b, V _nVariation, and as when not changing, represent solar panels to operate on the maximum power point, and need not carry out the operation of increment of load or load shedding., more respectively enter step 45, will increase the output power P of the solar panels after the load shedding operation thereafter _nWith output voltage V _n, be updated to the output power P that increases the preceding solar panels of load shedding operation _bWith output voltage V _bValue is for manipulating of second leg.

Among Fig. 1, increase load shedding operation order and load 13 voltage V when what current control unit 152 received maximum power tracing unit 151 _OFor fixedly the time, can be according to the load current I that is detected _OWith increase load shedding predetermined current difference DELTA I, calculate the targeted loads electric current I that increases load shedding operation _REFThereby, the cycle period signal T of the pulse-width modulation of adjustment output _CWith responsibility cycle signal D _C, make pulse wave width modulation unit 153 be produced required pulse wave width modulation signal GD ₁～GD _n, and then produce the gate drive signal G that is enough to drive converter 12 by drive element of the grid 154 ₁～G _n, with the control load electric current I _OProgressively rise or reduce to the targeted loads electric current I as illustrated in fig. 5 _REF

By in the above stated specification as can be known, use known maximum power tracing circuit 15, control when solar panels 11 are operated in maximum power point,, estimate sun power output power P because maximum power tracing unit 151 must use multiplyings or adopt the totalizers of accumulating operation _PV, and need to adopt the voltage and the power of temporary memory stores previous state, so its circuit complexity not only in the hardware realization more is difficult to combine with general pulse wave width modulation unit 153 circuit, and forms an integrated circuit (IC) chip with maximum power tracing function.

Summary of the invention

In view of this, the purpose of this invention is to provide a kind of solar panels maximum power tracing method and circuit, it can be by the difference calculation flow process of maximum power tracing, simplify solar panels maximum power tracing circuit, allow to realize combining, and form a purpose with integrated circuit (IC) chip of maximum power tracing function with existing pulse width modulation circuit.

For reaching above-mentioned and other purpose, the invention provides a kind of solar panels maximum power tracing method, supply power to the power of load applicable to sun-tracing energy plate.The method comprises the following steps: at first, detects the preceding output voltage of the operation that increases the preceding solar panels of load shedding operation; Then, carry out the load shedding operation that increases of solar panels according to the predetermined current difference; Detect output voltage after the operation increase the solar panels after the load shedding operation again; When the aforesaid load shedding operation that increases is an increment of load, and output voltage after the operation that in Preset Time, is detected, when output voltage minimizing amplitude was not less than the predeterminated voltage difference before the operation, the load shedding operation of setting next time that increases was an increment of load; When increasing load shedding operation is increment of load, and output voltage after the operation that in Preset Time, is detected, output voltage does not reduce before the operation, or Preset Time arrives, and when the minimizing amplitude of output voltage did not reach its predeterminated voltage difference yet after the operation that is detected, the load shedding operation of setting next time that increases was a load shedding; When the aforesaid load shedding operation that increases is a load shedding, and output voltage after the operation that in Preset Time, is detected, when the output voltage increasing degree was not less than the predeterminated voltage difference before the operation, the load shedding operation of setting next time that increases was a load shedding; And when to increase load shedding operation be load shedding, and output voltage after the operation that in Preset Time, is detected, output voltage does not increase before the operation, or Preset Time arrives, and when the increasing degree of output voltage did not reach the predeterminated voltage difference yet after the operation that is detected, the load shedding operation of setting next time that increases was an increment of load.

Wherein, predetermined current difference that sets and predeterminated voltage difference meet following relational expression:

$\frac{V_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">PV</figure-callout>}1}+\mathrm{\&Delta;V}}{{\mathrm{<figure-callout\; id="1"\; label="I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{PV}}}<\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{{\mathrm{<figure-callout\; id="1"\; label="I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{PV}}+\mathrm{\&Delta;I}}$

In the formula, V _PV1Represent the output voltage of solar panels, I _PV1Represent the output current of solar panels, the predeterminated voltage difference that Δ V representative sets, the predetermined current difference that Δ I representative sets.

Wherein, Preset Time is set according to the size of predetermined current difference and the reaction sensitivity of solar panels.That is to say that Preset Time needs when increasing load shedding operation at least, solar panels can immediately react and export the time that has the output current of predetermined current difference with former output current.

Wherein, carry out the step that increases load shedding operation and comprise:, calculate the cycle period of pulse wave width modulation with reference to predetermined current difference and the classification that increases load shedding operation; Detect the output current of solar panels then; And, set the responsibility cycle of pulse wave width modulation with the variation of output current between null value and predetermined current peak value of solar panels.

Wherein, calculate the step of the cycle period of pulse wave width modulation,, calculate the increase and decrease mistiming, to upgrade cycle period with reference to increasing load shedding operation preceding cycle period and predetermined current difference.The mistiming of being calculated is after execution increases load shedding operation, the time of the aforementioned predetermined current difference of the proper changeable of the average output current of solar panels.

The present invention provides a kind of solar panels maximum power tracing circuit in addition, applicable to the signal that produces pulse wave width modulation, drives converter in order to the control drive element of the grid, supplies power to the power of load with sun-tracing energy plate.This solar panels maximum power tracing circuit comprises: maximum power tracing unit, current control unit and pulse wave width modulation unit.

Wherein, the maximum power tracing unit is in order to carry out to detect output voltage before the operation that increases the solar panels before the load shedding operation, send and carry out the order that increases load shedding operation, detection increases output voltage after the operation of the solar panels after the load shedding operation, when increasing load shedding operation is increment of load, and output voltage after the operation that in Preset Time, is detected, when output voltage minimizing amplitude is not less than the predeterminated voltage difference before the operation, the load shedding operation of setting next time that increases is an increment of load, when increasing load shedding operation is increment of load, and output voltage after the operation that in Preset Time, is detected, output voltage does not reduce before the operation, or Preset Time arrives, and when the minimizing amplitude of output voltage does not reach the predeterminated voltage difference yet after the operation that is detected, the load shedding operation of setting next time that increases is a load shedding, when increasing load shedding operation is load shedding, and output voltage after the operation that in Preset Time, is detected, when the output voltage increasing degree is not less than the predeterminated voltage difference before the operation, the load shedding operation of setting next time that increases is a load shedding, and when to increase load shedding operation be load shedding, and output voltage after the operation that in Preset Time, is detected, output voltage does not increase before the operation, or Preset Time arrives, and when the increasing degree of output voltage does not reach the predeterminated voltage difference yet after the operation that is detected, set the function that load shedding operation is an increment of load etc. that increases next time.

Current control unit couples the maximum power tracing unit, in order to output current, the predetermined current difference of foundation solar panels and increase the order of load shedding operation, produces cycle period signal and responsibility cycle signal.The pulse wave width modulation unit couples current control unit, and cycle period signal and responsibility cycle signal in order to the output of foundation current control unit produce aforesaid signal.

In an embodiment, the predetermined current difference of this solar panels maximum power tracing circuit and the setting of predeterminated voltage difference meet following relational expression:

$\frac{V_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">PV</figure-callout>}1}+\mathrm{\&Delta;V}}{{\mathrm{<figure-callout\; id="1"\; label="I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{PV}}}<\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{{\mathrm{<figure-callout\; id="1"\; label="I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{PV}}+\mathrm{\&Delta;I}}$

In the formula, V _PV1Represent the output voltage of solar panels, I _PV1Represent the output current of solar panels, Δ V represents the predeterminated voltage difference, and Δ I represents the predetermined current difference.

In an embodiment, the Preset Time of this solar panels maximum power tracing circuit is set according to the size of predetermined current difference and the reaction sensitivity of solar panels.That is to say that Preset Time needs when increasing load shedding operation at least, solar panels can immediately react and export the time that has the output current of predetermined current difference with former output current.

In an embodiment, the current control unit of this solar panels maximum power tracing circuit, can calculate the cycle period of the signal that produces with reference to predetermined current difference and the classification that increases load shedding operation, produce the cycle period signal according to the cycle period that is calculated again, and with the variation of output current between null value and predetermined current peak value of solar panels, set the responsibility cycle of signal, to produce required responsibility cycle signal.

In an embodiment, the current control unit of this solar panels maximum power tracing circuit with reference to increasing load shedding operation preceding cycle period and predetermined current difference, calculates the increase and decrease mistiming, to upgrade cycle period.The mistiming of being calculated is after execution increases load shedding operation, the time of the aforementioned predetermined current difference of the proper changeable of the average output current of solar panels.

In sum, because known disturbance and observation are followed the trail of the method for peak power, must use multiplier to calculate the power of solar panels, method of the present invention does not then need multiplier, the function that need only the complies with design constraints condition can reach maximum power tracing, this not only can reduce the cost of multiplier, also can increase the time of processing.In addition, when making comparisons, also because the gain conductance method must be calculated G and Δ G, because of G=i/v, Δ G=di/dv must use divider with known gain conductance method, method of the present invention does not then need any multiplier and divider, can reduce cost and increases the processing time.

The old friend, because a kind of solar panels maximum power tracing method provided by the present invention and circuit, it follows the trail of the calculation flow process of peak power, need not use multiplier to estimate the output power P of solar panels _PV, therefore can simplify solar panels maximum power tracing circuit, and can realize combining, and form a purpose with integrated circuit (IC) chip of maximum power tracing function with existing pulse width modulation circuit.

For above-mentioned and other purposes of the present invention, feature and advantage can be become apparent, hereinafter special with preferred embodiment, and conjunction with figs., be described in detail below.

Description of drawings

Fig. 1 shows the block schematic diagram of known a kind of solar power system.

Fig. 2 shows the photoelectric characteristic curve of known a kind of solar panels.

Fig. 3 shows the disturbance of known a kind of sun-tracing energy peak power and the operation chart of observation.

Fig. 4 shows that known a kind of solar panels use disturbance and observation to follow the trail of the operational flowchart of peak power.

The time sequential routine synoptic diagram of the known solar power system of Fig. 5 displayed map 1.

Fig. 6 shows a kind of block schematic diagram of solar power system according to the preferred embodiment of the invention.

The trace flow synoptic diagram of the maximum power tracing unit of Fig. 7 displayed map 6.

The input end current waveform synoptic diagram of the current control unit control boost converter increment of load of Fig. 8 A displayed map 6.

The input end current waveform synoptic diagram of the current control unit control boost converter load shedding of Fig. 8 B displayed map 6.

The current control unit of Fig. 9 displayed map 6 increase the load shedding schematic flow sheet.

The input end current waveform synoptic diagram of the current control unit control step-down controller increment of load of Figure 10 A displayed map 6.

The input end current waveform synoptic diagram of the current control unit control step-down controller load shedding of Figure 10 B displayed map 6.

The output end current waveform synoptic diagram of the current control unit control boost converter increment of load of Figure 11 A displayed map 6.

The output end current waveform synoptic diagram of the current control unit control boost converter load shedding of Figure 11 B displayed map 6.

Embodiment

Please refer to shown in Figure 6ly, it is a kind of block schematic diagram of solar power system according to the preferred embodiment of the invention.Among the figure, this system produces the signal GD of pulse wave width modulation to comprise the solar panels maximum power tracing circuit 65 of maximum power tracing unit 651, current control unit 652 and pulse wave width modulation unit 653 ₁～GD _n, produce the gate drive signal G that is enough to drive converter 62 in order to control drive element of the grid 64 ₁～G _n, can plate 61 supply power to the power of load 63 with sun-tracing.

Wherein, the calculation flow process of peak power is followed the trail of in maximum power tracing unit 651, no longer needs to use multiplier to estimate the output power P of solar panels _PV, and cooperate current control unit 652 to carry out when increasing load shedding operation, the predetermined current difference DELTA I that sets, and system carries out the output voltage V that increases the forward and backward solar panels that detect 61 of load shedding operation _PV1With V _PV2Voltage difference, whether the predeterminated voltage of reaching difference DELTA V is arranged, judge that solar panels 61 operate in A district or B district, determine next step should carry out increment of load or load shedding operation more according to this, make the working point of solar panels 61, be able to as Fig. 3 the maximum power point Dm on the photoelectric characteristic curve move near and then disturbance operation maximum power point Dm.

In order suitably to determine predeterminated voltage difference DELTA V and predetermined current difference DELTA I, make solar panels 61 no matter in arbitrary working point of the photoelectric characteristic curve of Fig. 3, when moving toward maximum power point Dm, all carried out have a predetermined current difference DELTA I increase load shedding operation process, the output voltage V of its forward and backward solar panels that detect 61 _PV1With V _PV2Voltage difference, whether reach predeterminated voltage difference DELTA V, judge that solar panels 61 operate in A district or B district, determine next step should carry out increment of load or load shedding operation more according to this, predeterminated voltage difference DELTA V and predetermined current difference DELTA I preferably are set under the condition of following explanation.

As shown in Figure 3, when solar panels 61 operate in the A district,, the working point of solar panels 61 is moved toward Dm by Dn as reducing load, and the output voltage V of solar panels 61 _PVAlso will be along with output power P _PVIncrease and increase.The output current of supposing the forward and backward solar panels 61 of load shedding operation is I _PV1And I _PV2, and output voltage and power are respectively V _PV1, V _PV2And P _PV1, P _PV2Wherein, because of the output voltage V of load shedding operation and solar panels 61 _PVFor increasing, so the output current I of solar panels 61 _PV1And I _PV2, output voltage V _PV1And V _PV2Will as shown in the formula:

I _PV2＝I _PV1-ΔI .........(1)

V _PV2＝V _PV1+ΔV .........(2)

P _PV2＝V _PV2·I _PV2＝(V _PV1+ΔV)·(I _PV1-ΔI)

＝V _PV1·I _PV1+ΔV·I _PV1-ΔI·V _PV1-ΔVΔI

＝P _PV1+ΔV·I _PV1-ΔI·V _PV1-ΔVΔI .........(3)

Owing to operate in the A district, P during load shedding _PV2＞P _PV1, so formula (3) can be write as again:

P _PV2-P _PV1＝ΔV·I _PV1-ΔI·V _PV1-ΔVΔI＞0 .........(4)

As follows by the inequality that can draw Δ V/ Δ I in the formula (4):

$\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}>\frac{{\mathrm{<figure-callout\; id="1"\; label="V\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PV}}+\mathrm{\&Delta;<figure-callout\; id="1"\; label="V\; I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">V</figure-callout>}}{I_{\mathrm{PV}}}...\left(5\right)$

By learning in the formula (5), when A district load shedding operation, as long as Δ V/ Δ I is set greater than (V _PV1+ Δ V)/I _PV1, the working point of solar panels 61 is moved toward maximum power point Dm.But when adjusted continued load shedding again to maximum power point, the working point of solar panels 61 will enter the B district, and this moment is because of P _PV2＜P _PV1, make predeterminated voltage difference DELTA V and predetermined current difference DELTA I will not be inconsistent the condition of work of box-like (5), and should change the increment of load operation into.

Among Fig. 3, when solar panels 61 operate in the B district,, the working point of solar panels 61 is moved toward Dm by D1 as increasing load, and the output voltage V of solar panels 61 _PVAlso will be along with output power P _PVIncrease and reduce.Suppose that it is I that increment of load is operated the output current of forward and backward solar panels 61 _PV1And I _PV2, and output voltage and power are respectively V _PV1, V _PV2And P _PV1, P _PV2Wherein, because of the output voltage V of increment of load operation and solar panels 61 _PVFor reducing, so the output current I of solar panels 61 _PV1And I _PV2, output voltage V _PV1And V _PV2Will as shown in the formula:

I _PV2＝I _PV1+ΔI .........(6)

V _PV2＝V _PV1-ΔV .........(7)

P _PV2＝V _PV2·I _PV2＝(V _PV1-ΔV)·(I _PV1+ΔI)

＝V _PV1·I _PV1-ΔV·I _PV1+ΔI·V _PV1-ΔVΔI

＝P _PV1-ΔV·I _PV1+ΔI·V _PV1-ΔVΔI .........(8)

Owing to operate in the B district, P during increment of load _PV2＞P _PV1, so formula (8) can be write as again:

P _PV2-P _PV1＝ΔI·V _PV1-ΔV·I _PV1-ΔVΔI＞0 .........(9)

As follows by the inequality that can draw Δ V/ Δ I in the formula (9):

$\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{I_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">PV</figure-callout>}1}+\mathrm{\&Delta;I}}...\left(10\right)$

The old friend, when B district increment of load was operated, the setting of Δ V/ Δ I will meet the inequality of formula (10).In the same manner, when continuing increment of load as adjusted again to maximum power point Dm, the working point of solar panels 61 will enter the A district, makes P _PV2＜P _PV1, predeterminated voltage difference DELTA V and predetermined current difference DELTA I will not be inconsistent the condition of work of box-like (10) yet, and should change load shedding operation into.

When operating in the A district because of solar panels 61, predeterminated voltage difference DELTA V and predetermined current difference DELTA I will meet formula (5), and when operating in the B district, meet the inequality of formula (10), the setting of old friend's predeterminated voltage difference DELTA V and predetermined current difference DELTA I meets following relational expression:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="V\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PV}}+\mathrm{\&Delta;<figure-callout\; id="1"\; label="V\; I\; PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">V</figure-callout>}}{I_{\mathrm{PV}}}<\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{I_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="H200910173027XE0000021.png,H200910173027XE0000031.png"\; state="\{\{state\}\}">PV</figure-callout>}1}+\mathrm{\&Delta;I}}...\left(11\right)$

After having determined predeterminated voltage difference DELTA V and predetermined current difference DELTA I, maximum power tracing unit 651 can be after increasing load shedding operation, only according to the output voltage V of solar panels 61 _PVVariation, judge that solar panels 61 operate in A district or B district, and then determine that next step operation is to want increment of load or load shedding, and need not use multiplier to estimate the output power P of solar panels 61 _PV

Please refer to shown in Figure 7ly, at first in step 71, maximum power tracing unit 651 can read predeterminated voltage difference DELTA V, and detects the output voltage V of solar panels 61 _PV2In step 72, will increase load shedding operation flag C be made as 1, and suppose that solar panels 61 operate in the B district, be made as 0, to carry out the increment of load operation and will increase load shedding operation order D thereafter.Then in step 73, with the output voltage V of solar panels 61 _PV1Be made as and equal V _PV2, increase output voltage values before the load shedding operation with reservation.

Do you in step 74, judge that it is 0 that preceding bout increases load shedding operation order D? as be that bout is the increment of load operation before 0 representative, so solar panels 61 operate in the B district, flow process is to enter step 751, to make timer T ₂Again count.Set timer T ₂Purpose be that when solar panels 61 adjusted continued increment of load again to maximum power point Dm, the working point of solar panels 61 will enter the A district, and can't obtain qualified predeterminated voltage difference DELTA V, thereby must be at timer T ₂Arrive preset time t _dAfter, the working point of judging solar panels 61 has entered the A district and the order of sending load shedding operation.

At timer T ₂Again after the counting, flow process enters step 752, to detect the output voltage V of solar panels 61 _PV2, in step 753, judge the output voltage V of solar panels 61 then _PV2Little whether as expectedly than previous state? as not, represent solar panels 61 may be because of the variation of illumination enters the A district, and should enter in the step 767, sending the order of load shedding operation, and setting increases load shedding operation flag C.Otherwise, then enter step 754, with the variation of the output voltage that calculates solar panels 61, and in step 755, judge that it changes to be not less than predeterminated voltage difference DELTA V?

In step 755, as be judged as and be, then represent solar panels 61 still to operate in the B district, flow process should enter in the step 757, increases the load shedding operation order with what send increment of load, and sets and increase load shedding operation flag C.Otherwise, then enter step 756, to judge timer T ₂Whether arrived preset time t _dAs arriving, represent the operation of solar panels 61, may stride into the A district by the B district, so should enter in the step 767, increase the load shedding operation order, and set and increase load shedding operation flag C with what send load shedding.Otherwise flow process is got back to step 752, to continue to detect the output voltage V of solar panels 61 _PV2Variation, be not less than predeterminated voltage difference DELTA V or timer T up to its variation ₂Arrived preset time t _dTill.

In step 74, judge that it is not that preceding bout increases load shedding operation order D at 0 o'clock, bout is a load shedding operation before the representative, so solar panels 61 operate in the A district, flow process is to enter step 761, to make timer T ₁Again count.Set timer T ₁Purpose be that when solar panels 61 adjusted continued load shedding again to maximum power point Dm, the working point of solar panels 61 will enter the B district, and can't obtain qualified predeterminated voltage difference DELTA V, thereby must be at timer T ₁Arrive preset time t _dAfter, the working point of judging solar panels 61 entered the B district and send increment of load increase the load shedding operation order.

Wherein, timer T ₁Or T ₂Preset time t _d, set according to the size of predetermined current difference DELTA I and the reaction sensitivity of solar panels 61.That is to say preset time t _dAt least need when increasing load shedding operation, solar panels 61 can immediately react and export the time that has the output current of predetermined current difference DELTA I with former output current, to obtain qualified predeterminated voltage difference DELTA V.Certainly, timer T ₁Or T ₂Preset time t _dCan be set at different value respectively.

At timer T ₁Again after the counting, flow process enters step 762, to detect the output voltage V of solar panels 61 _PV2, in step 763, judge the output voltage V of solar panels 61 then _PV2Big whether as expectedly than previous state? as not, represent solar panels 61 may be because of the variation of illumination enters the B district, and should enter in the step 757, increase the load shedding operation order with what send increment of load, and setting increases load shedding operation flag C.Otherwise, then enter step 764, with the variation of the output voltage that calculates solar panels 61, and in step 765, judge that it changes to be not less than predeterminated voltage difference DELTA V?

In step 765, as be judged as and be, then represent solar panels 61 still to operate in the A district, flow process should enter in the step 767, increases the load shedding operation order with what send load shedding, and sets and increase load shedding operation flag C.Otherwise, then enter step 766, to judge timer T ₁Whether arrived preset time t _dAs arriving, represent the operation of solar panels 61, may stride into the B district by the A district, so should enter in the step 757, increase the load shedding operation order, and set and increase load shedding operation flag C with what send increment of load.Otherwise flow process is got back to step 762, to continue to detect the output voltage V of solar panels 61 _PV2Variation, be not less than predeterminated voltage difference DELTA V or timer T up to its variation ₁Arrived preset time t _dTill.

Among Fig. 6, current control unit 652 couples maximum power tracing unit 651, with the output current I of foundation solar panels 61 _PV, predetermined current difference DELTA I with increase the order of load shedding operation, produce cycle period signal T _CWith responsibility cycle signal D _C,, produce signal G according to this to transfer to the pulse wave width modulation unit 653 that couples current control unit 652 ₁～G _nThe Current Control of current control unit 652 increases the practice of load shedding, can be to adopt closed loop pattern that output current feedbacks or as the circuit pattern of opening of Fig. 8 A to 11B.

Please refer to shown in Fig. 8 A and the 8B, respectively the input end current waveform synoptic diagram of the current control unit of displayed map 6 control boost converter increment of load and load shedding.Among the figure, current control unit 652 can and increase the increment of load of load shedding operation or the cycle period T that the load shedding classification is calculated the signal that produces with reference to predetermined current difference DELTA I _CN, again according to the cycle period T that is calculated _CNAnd generation cycle period signal T _C, and with the converter 62 input end electric current I of for example boost converter _i(the output current I of solar panels 61 just _PV) at null value and predetermined current peak delta I _PBetween variation, set signal G ₁～G _nResponsibility cycle, to produce required responsibility cycle signal D _C

Wherein, because of predetermined current peak delta I _PSize for fixing, so increase load shedding operation front and back, converter 62 input end electric current I _iRise to predetermined current peak delta I by null value _PTime Δ T _L, and by predetermined current peak delta I _PDrop to the time Δ T of null value _BAll constant, and increase the required predetermined current difference DELTA I of load shedding operation, then produce cycle period signal T by increase and decrease _CCycle period T _CNReach.For example, converter 62 input end electric current I among Fig. 8 A _iIncrement of load, be with the cycle period T before the increment of load _CNDeduct the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get, and converter 62 input end electric current I among Fig. 8 B _iLoad shedding, be with the cycle period T before the load shedding _CNAdd the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get.The aforementioned mistiming Δ T that calculates is after execution increases load shedding operation, the average output current I of solar panels 61 _PV(converter 62 input end electric current I just _{I (av)}) proper time of changeable predetermined current difference DELTA I, its operating process will illustrate with reference to figure 9.

Among Fig. 9, flow process at first enters step 91, to read predetermined current difference DELTA I, predetermined current peak delta I _PWith default cycle period T _CNAnd in step 92, read increasing load shedding operation flag C and increasing load shedding operation order D of maximum power tracing unit 651 output, enter step 93 immediately, increase load shedding operation flag C with judgement and whether be set at 1? as be not set at 1 the representative need not increase, load shedding, flow process directly enters step 952, to keep original cycle period T _CNOtherwise flow process enters step 941, with reference predetermined current difference DELTA I and cycle period T _CN, calculate and increase, subtract the required mistiming Δ T of predetermined current difference DELTA I ₁, Δ T ₂, enter then in the step 942, with according to the value that increases load shedding operation order D, judge it is to want increment of load or load shedding? and respectively in step 943 and 944, with reference to the mistiming Δ T that is calculated ₁, Δ T ₂, adjust the cycle period T of load shedding and increment of load _CN, and involution increases load shedding operation flag C in step 951.

In step 952, flow process can start timer T ₃Counting, enter step 953 then, with responsibility cycle signal D _CBe set at 1, enter step 954 again and detect converter 62 input end electric current I _i, and in step 955, judge converter 62 input end electric current I _iWhether reached predetermined current peak delta I _P, until converter 62 input end electric current I _iArrive predetermined current peak delta I _PTill.Afterwards, flow process enters step 956, with responsibility cycle signal D _CBe set at 0, enter step 957 again and judge timer T ₃Counting whether reached cycle period T _CN, until timer T ₃Counting reached cycle period T _CNTill.Wherein, cycle period signal T _CTimer T can started ₃Counting the time together produce.

Please refer to shown in Figure 10 A and the 10B, respectively the input end current waveform synoptic diagram of the current control unit of displayed map 6 control step-down controller increment of load and load shedding.Among the figure, current control unit 652 also is with reference to predetermined current difference DELTA I and increases the increment of load of load shedding operation or the cycle period T that the load shedding classification is calculated the signal that produces _CN, again according to the cycle period T that is calculated _CNAnd generation cycle period signal T _C, and with the converter 62 input end electric current I of for example step-down controller _i(the output current I of solar panels 61 just _PV) at null value and predetermined current peak delta I _PBetween variation, set signal G ₁～G _nResponsibility cycle, to produce required responsibility cycle signal D _C

Wherein, Figure 10 A converter 62 input end electric current I _iIncrement of load, be with the cycle period T before the increment of load _CNDeduct the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get, and converter 62 input end electric current I among Figure 10 B _iLoad shedding, then with the cycle period T before the load shedding _CNAdd the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get.The mistiming Δ T that is calculated is after execution increases load shedding operation, the average output current I of solar panels 61 _PV(converter 62 input end electric current I just _{I (av)}) proper time of changeable predetermined current difference DELTA I, its operating process is also identical with Fig. 9.

Please refer to shown in Figure 11 A and the 11B, respectively the output end current waveform synoptic diagram of the current control unit of displayed map 6 control boost converter increment of load and load shedding.Among the figure, current control unit 652 equally also is with reference to predetermined current difference DELTA I and increases the increment of load of load shedding operation or the cycle period T that the load shedding classification is calculated the signal that produces _CN, again according to the cycle period T that is calculated _CNAnd generation cycle period signal T _C, and with the converter 62 output end current I of for example boost converter _O(the output current I of itself and solar panels 61 _PVK is arranged _iThe value proportionate relationship) at null value and predetermined current peak delta I _PBetween variation, set signal G ₁～G _nResponsibility cycle, to produce required responsibility cycle signal D _C

Wherein, converter 62 output end current I among Figure 11 A _OIncrement of load (the output current I of solar panels 61 just _PVIncrement of load), be with the cycle period T before the increment of load _CNDeduct the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get, and converter 62 output end current I among Figure 11 B _OLoad shedding (the output current I of solar panels 61 just _PVLoad shedding), then be with the cycle period T before the load shedding _CNAdd the mistiming Δ T that is calculated with reference to predetermined current difference DELTA I and get that its operating process is also similar with the principle of Fig. 9.

Though the present invention discloses as above with preferred embodiment, so it is not in order to qualification the present invention, any those skilled in the art, and various modifications and the modification done without departing from the spirit and scope of the present invention also belong to scope of the present invention.Therefore, protection scope of the present invention is as the criterion when looking claims.

Claims (10)

1. a solar panels maximum power tracing method is applicable to that sun-tracing energy plate supplies power to the power of load, comprises the following steps:

Detect the preceding output voltage of operation of described solar panels;

Increase load shedding operation according to the predetermined current difference with execution;

Detect output voltage after the operation of described solar panels;

When the described load shedding operation that increases is an increment of load, and the described operation back output voltage that in Preset Time, is detected, when output voltage minimizing amplitude was not less than the predeterminated voltage difference before the more described operation, the described load shedding operation of setting next time that increases was an increment of load;

When the described load shedding operation that increases is an increment of load, and the described operation back output voltage that in described Preset Time, is detected, output voltage does not reduce before the more described operation, or described Preset Time arrives, and the minimizing amplitude of the described operation back output voltage that is detected is not when reaching described predeterminated voltage difference yet, and the described load shedding operation of setting next time that increases is a load shedding;

When the described load shedding operation that increases is a load shedding, and the described operation back output voltage that is detected in described Preset Time, when the output voltage increasing degree was not less than described predeterminated voltage difference before the more described operation, the described load shedding operation of setting next time that increases was a load shedding; And

When the described load shedding operation that increases is a load shedding, and the described operation back output voltage that in described Preset Time, is detected, output voltage does not increase before the more described operation, or described Preset Time arrives, and the increasing degree of the described operation back output voltage that is detected is not when reaching described predeterminated voltage difference yet, and the described load shedding operation of setting next time that increases is an increment of load.

2. solar panels maximum power tracing method as claimed in claim 1, wherein, the setting of described predetermined current difference and described predeterminated voltage difference meets following relational expression:

$\frac{V_{\mathrm{PV}1}+\mathrm{\&Delta;V}}{I_{\mathrm{PV}1}}<\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{I_{\mathrm{PV}1}+\mathrm{\&Delta;I}}$

In the formula, V _PV1Represent the output voltage of described solar panels, I _PV1Represent the output current of described solar panels, Δ V represents described predeterminated voltage difference, and Δ I represents described predetermined current difference.

3. solar panels maximum power tracing method as claimed in claim 1, wherein, described Preset Time is to set according to the reaction sensitivity of the size of described predetermined current difference and described solar panels.

4. solar panels maximum power tracing method as claimed in claim 1, wherein, carry out the described step that increases load shedding operation and comprise:

With reference to described predetermined current difference and the described classification that increases load shedding operation, calculate the cycle period of pulse wave width modulation;

Detect the output current of described solar panels; And

With the variation of described output current between null value and predetermined current peak value of described solar panels, set the responsibility cycle of pulse wave width modulation.

5. solar panels maximum power tracing method as claimed in claim 4, wherein, the step of calculating described cycle period is with reference to described load shedding operation preceding described cycle period and the described predetermined current difference of increasing, calculate the increase and decrease mistiming, to upgrade described cycle period, the described mistiming for carry out described increase load shedding operation after, the time of the average described predetermined current difference of the proper changeable of described output current.

6. solar panels maximum power tracing circuit is applicable to the signal that produces pulse wave width modulation, and described signal drives converter in order to the control drive element of the grid, so that can sun-tracing can plate supply power to the power of load, comprising:

The maximum power tracing unit, in order to output voltage before the operation of carrying out the described solar panels of detection, send and carry out the order that increases load shedding operation, detect output voltage after the operation of described solar panels, when the described load shedding operation that increases is an increment of load, and the described operation back output voltage that in Preset Time, is detected, when output voltage minimizing amplitude is not less than the predeterminated voltage difference before the more described operation, the described load shedding operation of setting next time that increases is an increment of load, when the described load shedding operation that increases is an increment of load, and the described operation back output voltage that in described Preset Time, is detected, output voltage does not reduce before the more described operation, or described Preset Time arrives, and the minimizing amplitude of the described operation back output voltage that is detected is not when reaching described predeterminated voltage difference yet, the described load shedding operation of setting next time that increases is a load shedding, when the described load shedding operation that increases is a load shedding, and the described operation back output voltage that in described Preset Time, is detected, when the output voltage increasing degree is not less than described predeterminated voltage difference before the more described operation, the described load shedding operation of setting next time that increases is a load shedding, and ought describedly to increase load shedding operation be load shedding, and the described operation back output voltage that in described Preset Time, is detected, output voltage does not increase before the more described operation, or described Preset Time arrives, and the increasing degree of the described operation back output voltage that is detected is not when reaching described predeterminated voltage difference yet, sets next time described and increases the function that load shedding operation is an increment of load;

Current control unit couples described maximum power tracing unit, and output current, predetermined current difference and the described order that increases load shedding operation in order to according to described solar panels produce cycle period signal and responsibility cycle signal; And

The pulse wave width modulation unit couples described current control unit, in order to according to described cycle period signal and described responsibility cycle signal, produces described signal.

7. solar panels maximum power tracing circuit as claimed in claim 6, wherein, the setting of described predetermined current difference and described predeterminated voltage difference meets following relational expression:

$\frac{V_{\mathrm{PV}1}+\mathrm{\&Delta;V}}{I_{\mathrm{PV}1}}<\frac{\mathrm{\&Delta;V}}{\mathrm{\&Delta;I}}<\frac{V_{\mathrm{PV}1}}{I_{\mathrm{PV}1}+\mathrm{\&Delta;I}}$

In the formula, V _PV1Represent the output voltage of described solar panels, I _PV1Represent the output current of described solar panels, Δ V represents described predeterminated voltage difference, and Δ I represents described predetermined current difference.

8. solar panels maximum power tracing circuit as claimed in claim 6, wherein, described Preset Time is to set according to the reaction sensitivity of the size of described predetermined current difference and described solar panels.

9. solar panels maximum power tracing circuit as claimed in claim 6, wherein, the cycle period of described signal is calculated in described current control unit meeting with reference to described predetermined current difference and the described classification that increases load shedding operation, produce described cycle period signal according to the described cycle period that is calculated again, and with the variation of described output current between null value and predetermined current peak value of described solar panels, set the responsibility cycle of described signal, to produce required described responsibility cycle signal.

10. solar panels maximum power tracing circuit as claimed in claim 9, wherein, described current control unit is with reference to described load shedding operation preceding described cycle period and the described predetermined current difference of increasing, calculate the increase and decrease mistiming, to upgrade described cycle period, the described mistiming for carry out described increase load shedding operation after, the time of the average described predetermined current difference of the proper changeable of described output current.

Images