WO2020119332A1 - Circuit d'alimentation électrique et système de production d'énergie photovoltaïque comprenant ce dernier - Google Patents

Circuit d'alimentation électrique et système de production d'énergie photovoltaïque comprenant ce dernier Download PDF

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Publication number
WO2020119332A1
WO2020119332A1 PCT/CN2019/115684 CN2019115684W WO2020119332A1 WO 2020119332 A1 WO2020119332 A1 WO 2020119332A1 CN 2019115684 W CN2019115684 W CN 2019115684W WO 2020119332 A1 WO2020119332 A1 WO 2020119332A1
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Prior art keywords
circuit
power supply
output
ccfl
photovoltaic
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PCT/CN2019/115684
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English (en)
Chinese (zh)
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王保均
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广州金升阳科技有限公司
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02J3/383—
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/338—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement
    • H02M3/3382—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement in a push-pull circuit arrangement
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the invention relates to a power supply circuit used in a photovoltaic power generation system, in particular to a power supply circuit that activates an aging photovoltaic string.
  • the modules work at high voltage for a long time, between the cover glass, the packaging material, and the frame There is a leakage current, and a large amount of charge accumulates on the surface of the battery chip, which deteriorates the passivation effect on the surface of the battery chip, resulting in a reduction in fill factor (FF), short circuit current (Isc), and open circuit voltage (Voc), making the performance of the component lower than the design standard.
  • FF fill factor
  • Isc short circuit current
  • Voc open circuit voltage
  • PID refers to the fact that when a solar module and ground form a high-intensity negative voltage, the resulting potential difference will not only cause damage to the solar cell or module, but also cause the problem of power generation efficiency attenuation.
  • PID can affect the power generation capacity and total output power of the entire system. In serious cases, it will directly reduce the return on investment of photovoltaic power plants. In recent years, it has become one of the pain points for international buyers to complain about the quality of domestic components.
  • SunPower proposes that the components of the N-type front surface solar cell adopt positive grounding and the components of the P-type front surface battery adopt negative grounding.
  • packaging materials with better stability can be used, no metal frame is used, the body resistance of the battery is increased, the thickness and characteristics of the passivation film are improved, and a barrier layer is added to the device.
  • the Chinese invention patent application with publication number CN107086601A discloses a photovoltaic power generation system and a voltage compensation method.
  • the patent application uses the pulse voltage output by the voltage compensation device to perform voltage compensation on the photovoltaic string to restore the PID effect.
  • Adverse effects but because the voltage compensation device does not have a specific implementation, it is only proposed that its function is to output pulse voltage.
  • the pulse voltage given in the specific implementation includes three forms of square wave, triangular wave and trapezoidal wave. The essence of is the same as its figure 5C. This is because in its figure 5A, t1 and t2 are the rising edge and the falling edge, respectively, and it is impossible to be idealized.
  • the technical problem to be solved by the present invention is to provide a power supply circuit and a photovoltaic power generation system including the power supply circuit, the change in the output voltage of the power supply circuit ⁇ U/ ⁇ t is small, so that the photovoltaic power generation system using the power supply circuit is environmentally friendly The pollution is small.
  • a power circuit applied to a photovoltaic power generation system is characterized by including a BUCK circuit and a CCFL conversion circuit; the positive input terminal of the BUCK circuit is the positive input terminal of the power circuit, and the negative input terminal of the BUCK circuit is the negative input terminal of the power circuit ;
  • the positive output of the BUCK circuit is connected to the positive input of the CCFL conversion circuit, and the negative output of the BUCK circuit is connected to the negative input of the CCFL conversion circuit;
  • the first output of the CCFL conversion circuit is the first output of the power supply circuit, CCFL conversion
  • the second output terminal of the circuit is the second output terminal of the power supply circuit, and the voltage output between the positive output terminal and the negative output terminal of the BUCK circuit includes at least one drop during operation.
  • the BUCK circuit and the CCFL conversion circuit it is characterized by:
  • the BUCK circuit includes at least a diode D1, an inductor L1 and a capacitor C1; one end of the inductor L1 is electrically connected to the positive input terminal of the power supply circuit, one end of the inductor L1 is also connected to the cathode of the diode D1, and the other end of the inductor L1 is connected to the positive output terminal of the BUCK circuit ,
  • the anode of the diode D1 is electrically connected to the negative input of the power supply circuit, the anode of the diode D1 is also connected to the negative output of the BUCK circuit, and the capacitor C1 is connected in parallel between the positive output and the negative output of the BUCK circuit;
  • the CCFL conversion circuit includes at least a starting circuit, an inductor L2, a capacitor C3, a transistor TR1, a transistor TR2, a transformer B, primary windings N P1 and N P2 , feedback windings N B1 and N B2 , and a secondary winding N S1 , and the starting circuit is at least Including two terminals, start input end and start output end; start input end is connected to the positive output end of the BUCK circuit or the positive input end of the power supply circuit, and the start output end is connected to the center taps of the feedback windings N B1 and N B2 ; transistors TR1 and TR2
  • the emitter is connected to the negative output of the BUCK circuit, the collector is connected to the two ends of the primary windings N P1 and N P2 respectively, the collector is also connected to both ends of the capacitor C3, and the base is connected to the feedback winding N B1 And N B2 ; the center taps of the primary windings N P1 and N P2 are connected to the positive
  • the start-up circuit includes a current supply device, and the current supply device is a resistor or a constant current source device.
  • the starting circuit further includes a capacitor C2, which is connected in parallel with the current supply device, or the capacitor C2 is connected between the starting output terminal and the negative output terminal of the BUCK circuit.
  • the CCFL conversion circuit is driven by it.
  • a photovoltaic power generation system including a photovoltaic string, further comprising: the power circuit described in any one of the above, the hot end of the photovoltaic string is electrically connected to the first output end of the power circuit, and the ground end of the photovoltaic string is electrically Connected to the second output terminal of the power circuit, when the photovoltaic string is activated, the voltage output between the positive output terminal and the negative output terminal of the BUCK circuit drops with time.
  • the above photovoltaic power generation system it is characterized in that it further includes a DC power supply, and the DC power supply is connected in series with the power supply circuit, and the series connection method is one of the following two:
  • the negative pole of the DC power supply is electrically connected to the second output end of the power supply circuit, the first output end of the power supply circuit is electrically connected to the positive pole of the photovoltaic string, and the negative electrode of the photovoltaic string is electrically connected to the positive pole of the DC power supply;
  • the negative pole of the DC power supply is electrically connected to the positive pole of the photovoltaic string
  • the negative pole of the photovoltaic string is electrically connected to the second output end of the power supply circuit
  • the first output end of the power supply circuit is electrically connected to the positive pole of the DC power supply.
  • the peak value of the high-frequency alternating current output by the CCFL conversion circuit is not greater than the open circuit voltage of the activated photovoltaic string.
  • the working frequency of the CCFL conversion circuit in the power supply circuit is less than or equal to 1 MHz.
  • the hot end of the photovoltaic string because the preferences of different manufacturers are not good, some ground the positive pole of the photovoltaic string, and some ground the negative pole of the photovoltaic string, the hot end refers to the end that is not grounded, because there is no ground, It is easy to cause electric shock to the human body, so it is called the hot end, which is usually the end that the solar panel needs to be activated, which may be the positive or negative electrode of the photovoltaic string;
  • the grounding end of the photovoltaic string and the grounding metal frame of the photovoltaic string may be the negative pole of the photovoltaic string, or it may be the positive pole;
  • CCFL inverter Collector resonance type Royer circuit
  • CCFL inverter Cold cathode lamp inverter
  • CCFL converter CCFL conversion circuit for short.
  • CCFL is the abbreviation of "Cold cathode fluorescent lamps”, which originally refers to cold cathode fluorescent lamps. Before white LEDs did not appear, they were mostly used for LCD backlights. Since the previous LCDs were mostly used in notebook computers, the backlights were DC. Power supply, then a variant of the Royer circuit came out, turning DC into pure AC, driving cold cathode fluorescent lamps.
  • the classic Royer circuit oscillates using the saturation characteristics of the magnetic core, and the output is a square wave.
  • the characteristics of the CCFL conversion circuit are: an inductor is connected in series from the middle tap of the primary winding of the push-pull transformer to the power supply end in the Royer circuit.
  • This inductor is generally called the damping inductor L LC in the industry (corresponding to the inductor L2 in FIG. 1 of this application).
  • the amount is generally more than ten times the inductance of the primary winding.
  • a capacitor CL (corresponding to the capacitor C3 in FIG.
  • Push-pull transistor two transistors that realize the self-excited oscillation and stable operation of the Royer circuit and the CCFL conversion circuit, generally two transistors, also known as pair transistors, also known as push-pull transistors, usually bipolar semiconductors , Of course, can also be a unipolar field effect tube;
  • Start-up circuit a circuit that provides start-up current or voltage for the push-pull transistor or field-effect tube in the CCFL conversion circuit, and realizes a fast start or soft start of the CCFL conversion circuit.
  • the voltage waveform ⁇ U/ ⁇ t output from the power supply circuit is small, so that the life of the photovoltaic string in the photovoltaic power generation system using the power supply circuit is extended, and the radiation to the environment is small.
  • FIG. 1 is a schematic diagram of a power supply circuit according to a first embodiment of the invention
  • FIG. 3-1 is one of the voltage waveforms output by the BUCK circuit and the CCFL conversion circuit in the first embodiment of the present invention
  • 3-2 is the second waveform diagram of the voltage output from the BUCK circuit in the first embodiment of the present invention.
  • 3-3 is the third waveform diagram of the voltage output from the BUCK circuit in the first embodiment of the present invention.
  • FIG. 3-4 is the fourth waveform diagram of the voltage output from the BUCK circuit in the first embodiment of the present invention.
  • FIG. 4 is a schematic diagram of an improved power circuit applied to a photovoltaic power generation system according to a second embodiment of the present invention.
  • FIG. 5 is a schematic diagram of a power supply circuit according to a third embodiment of the invention.
  • the work of the photovoltaic power generation system is mainly during the daytime when there is good sunlight.
  • the local sun height angle reaches the maximum, it is recorded as 12 o'clock local time.
  • the photovoltaic power generation system can effectively output electrical energy.
  • the generated power is reduced and has no practical value.
  • the output characteristics of photovoltaic strings are not constant voltage sources, but most of them are similar to the characteristics of constant current sources. In order to obtain greater output power, the principle of maximum power output is generally used as far as possible, so that the output terminal voltage is to ensure system efficiency On the premise of being as high as possible.
  • the output voltage curve of the two ends of the photovoltaic string rises relatively quickly in the morning because the load is almost empty.
  • the grid When the grid is connected to the power generation, it first drops due to load, reaches the maximum value when the light is strongest at noon, and then slowly decreases.
  • the voltage When the network is disconnected at about 14:00 local time, the voltage will increase again to the open circuit voltage under the corresponding illuminance due to the lightening of the load, and then decrease with time, and it will be close to zero at night. If it is a rainy day, the photovoltaic string The voltage is in a low voltage state close to zero throughout the day, and the power circuit of the present application is mainly suitable for activating the photovoltaic string when the voltage across the string is low.
  • the concept of the present invention is to provide a two-stage topology power supply circuit.
  • the first stage is a BUCK circuit, which processes the input high-voltage DC power into a DC voltage whose output voltage decreases with time
  • the second stage is a CCFL conversion circuit, which converts the input with time.
  • the reduced DC voltage is converted to a sinusoidal AC output. Since the CCFL conversion circuit is open-loop, the peak-to-peak value of the sinusoidal AC output is proportional to the working voltage of the CCFL conversion circuit. This voltage decreases with time, that is, the sine output by the CCFL conversion circuit The peak-to-peak value of the alternating current also decreases with time.
  • the effective value of the sinusoidal alternating current also decreases with time, obtaining a decaying sinusoidal alternating current voltage.
  • the voltage waveform ⁇ U/ ⁇ t output from the power circuit is small. Since the sine wave is a single frequency, there are few harmonic components, and there is little air radiation, which is very friendly to the environment, which makes the power supply applied.
  • the life of the photovoltaic strings in the photovoltaic power generation system of the circuit is extended, and the radiation to the environment is small, and the power circuit of the present invention is simple to implement and low in cost.
  • FIG. 1 is a schematic diagram of a power circuit according to a first embodiment of the present invention.
  • the composition and connection of its components are as follows:
  • the power supply circuit shown in Figure 1 includes a BUCK circuit and a CCFL conversion circuit
  • BUCK circuit includes MOS tube K1, diode D1, inductance L1 and capacitor C1;
  • the CCFL conversion circuit includes a start-up circuit composed of a resistor R1 and a capacitor C2, a capacitor C3, an inductor L2, a transistor TR1, a transistor TR2, a transformer B, primary windings N P1 and N P2 , feedback windings N B1 and N B2 , and a secondary side Winding N S1 , the startup circuit includes at least two terminals, one end of the resistor R1 is the startup input terminal, the connection point of the other end of the resistor R2 and the end of the capacitor C2 is the startup output terminal, in this embodiment, two push-pull transistors TR1 and The device that TR2 provides the starting current is the resistor R1;
  • the positive input terminal of the BUCK circuit is the positive input terminal of the power circuit
  • the negative input terminal of the BUCK circuit is the negative input terminal of the power circuit
  • the first output terminal of the CCFL conversion circuit is the first output terminal of the power circuit
  • the first output terminal of the CCFL conversion circuit is the second output terminal of the power circuit
  • One end of the inductor L1 is connected to the cathode of the diode D1, the other end of the inductor L1 is connected to the positive output of the BUCK circuit, the anode of the diode D1 is connected to both the negative input and the negative output of the BUCK circuit, and the capacitor C1 is connected in parallel to the positive output of the BUCK circuit Between the negative output terminal, the drain of the MOS tube K1 is connected to the positive input terminal of the BUCK circuit, and the source is connected to the end of the inductor L1; in FIG.
  • the start input is connected to the positive output of the BUCK circuit, the start output is connected to the center taps of the feedback windings N B1 and N B2 , and the other end of the capacitor C2 is connected to the negative output of the BUCK circuit; the emitters of the transistors TR1 and TR2 are both connected to the BUCK
  • the negative output of the circuit, the collectors of the transistors TR1 and TR2 are connected to the two ends of the primary windings N P1 and N P2 respectively, the collectors of the transistors TR1 and TR2 are also connected to the two terminals of the capacitor C3, and the transistors TR1 and TR2
  • the base of the is connected to the two ends of the feedback windings N B1 and N B2 respectively, the center taps of the primary windings N P1 and N P2 are connected to the positive output of the BUCK circuit through the inductor L2; the end of the secondary winding N S1 is CCFL transformed
  • the output of the CCFL conversion circuit is alternating current, the first output terminal and the second output terminal of the power circuit of the present invention can be exchanged.
  • the first-stage circuit of the power supply circuit of this embodiment uses a BUCK circuit.
  • the BUCK circuit is one of the three topologies of switching power supplies (BUCK, BOOST, BUCK-BOOST).
  • BUCK, BOOST, BUCK-BOOST switching power supplies
  • Various other switching power supply structures are evolved from these three topologies
  • the circuit structure is extremely simple and the cost is low.
  • the formulas for its output voltage Vout, input voltage Vin and duty cycle D are:
  • the duty ratio is the ratio of the turn-on time of the MOS tube K1 to the total time.
  • the voltage applied to the photovoltaic string activation in this application is sinusoidal alternating current, and the acquisition of alternating current is very complicated. If it is directly obtained by using a switching power supply, the waveform edge of the output voltage is very steep, such as The voltage waveform outputted by the push-pull converter is a square wave, and its ⁇ U/ ⁇ t is close to infinity. Therefore, the defects described in the background art also exist. If the digital audio power amplifier is used, the switching power supply plus the output filter, the cost and control circuit are very complicated.
  • the second-stage circuit of this embodiment uses a CCFL conversion circuit, and in view of the fact that the wavelength of 1MHz high-frequency alternating current is 30 meters, the corresponding half-wave dipole antenna length is 1/4 wavelength, which is 7.5 meters, which is the power circuit of the present invention.
  • the output high-frequency alternating current has a frequency below 1MHz, so its radiation is relatively easy to control.
  • the output high-frequency alternating current has a frequency of 100KHz and a quarter wavelength of 75 meters.
  • this embodiment requires the CCFL conversion circuit to operate at a relatively "low frequency" below 1 MHz, which is still referred to herein as high-frequency alternating current, or sinusoidal alternating current.
  • the CCFL conversion circuit is a kind of self-excited push-pull converter.
  • the working principle of the sinusoidal output voltage waveform is analyzed as follows:
  • the circuit on the right side of the capacitor C1 in FIG. 1 is the CCFL conversion circuit.
  • the difference between the CCFL conversion circuit and the self-excited push-pull converter is the addition of the capacitor C3 and the inductance L2; the oscillation principle of the circuit and the self-excited push-pull type
  • the converter is similar, but the CCFL conversion circuit does not use the core saturation characteristic for push-pull oscillation, but uses the total inductance of the capacitor C3 and the windings N P1 and N P2 of the coupling transformer B for LC loop oscillation.
  • the output waveform of the circuit is a sine wave It is no longer a square wave.
  • the role of the inductance L2 is: 1. Provide a large AC input impedance for the transformer. 2.
  • the characteristics of the CCFL conversion circuit are: the use of LC series resonant circuit oscillation, the frequency is relatively stable, the output is a sine wave or approximate sine wave, and the efficiency is low, so it is also necessary to induct L2 in series in the power supply loop to improve efficiency.
  • the present invention requires that the inductance of the inductor L2 is more than 10 times the inductance of the winding NP1 or NP2 . At this time, it is the perfect sine wave that is oscillated by the inductor L2 and the capacitor C2.
  • the terminal voltage of the capacitor C1 is the output voltage of the BUCK circuit.
  • the present invention requires that when the photovoltaic string is activated, this voltage drops with time, and there are many ways to drop it, all by controlling the MOS tube K1 in the BUCK circuit.
  • To achieve the air ratio for example, first rise from a low pressure to a high pressure, and then fall from a high pressure to a stable value, and then rise and fall after a period of stability, but no matter what kind of decline, it should include at least one voltage drop, that is :
  • the output voltage of the BUCK circuit drops for at least one period.
  • the power supply circuit of the present invention is powered off and shut down, the output voltage of the BUCK circuit will also naturally drop due to the power failure.
  • the "at least one period of time is reduced" in the present invention does not include this natural drop .
  • the CCFL conversion circuit Since the working voltage of the CCFL conversion circuit is the terminal voltage of the capacitor C1, the CCFL conversion circuit outputs an envelope formed by connecting the positive half-cycle peaks of the high-frequency alternating current.
  • the shape of the envelope will be similar to the change in the terminal voltage of C1.
  • the envelope formed by connecting the negative half-cycle peaks of the high-frequency alternating current of the CCFL conversion circuit the shape of the envelope after mirroring the X axis in common coordinates will be similar to the change in the terminal voltage of C1.
  • FIG. 3-1 is one of the voltage waveforms output by the BUCK circuit and the CCFL conversion circuit according to the first embodiment of the present invention.
  • the voltage waveforms across the capacitor C1 are as shown by the straight line S1 in FIG. 3-1.
  • the voltage waveform output by the CCFL conversion circuit is shown in curve S2, which is a decayed high-frequency alternating current.
  • the straight line S3 is the envelope of the curve S2 in the positive half cycle
  • the straight line S4 is the envelope of the curve S2 in the negative half cycle
  • the straight line S3 and the straight line S4 Mirror symmetry along the X axis.
  • Fig. 3-2 is the second waveform diagram of the voltage output from the BUCK circuit according to the first embodiment of the present invention.
  • the broken line S5 is first stabilized at a fixed value and then linearly attenuated. This waveform includes a voltage drop;
  • Fig. 3-3 is the present invention
  • the voltage waveform output by the BUCK circuit is the third.
  • the broken line S6 linearly rises from the low voltage to the first high voltage value, stabilizes at the first high voltage value for a period of time, then linearly rises to the second high voltage value, and stabilizes at the The second high voltage value drops linearly to the first high voltage value after a period of time, and then decays linearly.
  • This waveform includes two voltage drops;
  • Figure 3-4 is the fourth waveform diagram of the voltage output by the BUCK circuit according to the first embodiment of the present invention.
  • S7 is first stabilized at a fixed value, and then linearly decayed to the first voltage value, and then stabilized at the first voltage value for a period of time and then linearly decayed.
  • the waveform includes two voltage drops.
  • FIGS. 3-1 to 3-4 are only examples of voltage waveforms output by some BUCK circuits.
  • the purpose of the invention can be achieved, and the way of the drop is not limited to the figure.
  • Linear decay attenuation method can also be other decay attenuation methods such as exponential and logarithmic, and can also achieve the purpose of the invention.
  • the control strategy of the MOS transistor K1 can be adjusted as needed to achieve the output voltage waveform required by the BUCK circuit.
  • the hot end of the photovoltaic string is electrically connected to the first output end of the power supply circuit, and the ground end of the photovoltaic string is electrically connected to the second output end of the power supply circuit.
  • electrical connection also includes indirect connection (that is, other components can be connected between two electrical connection objects), and includes connection through inductive coupling.
  • the second embodiment of the present application is an indirect connection, and the following situations are also indirect connections:
  • an electrolytic capacitor bank with a stable output voltage is connected in parallel at both ends of the photovoltaic string, in order to prevent the electrolytic capacitor bank from absorbing the high-frequency alternating current output by the power circuit of the present invention, the activation of the photovoltaic string cannot be achieved.
  • An inductance is connected in series between the hot end of the photovoltaic string and the connection point with the electrolytic capacitor bank, so that the high-frequency alternating current applied to both ends of the electrolytic capacitor bank can be applied to both ends of the photovoltaic string due to the isolation effect of the inductance.
  • the hot end of the photovoltaic string is not directly connected to the first output end of the power circuit, but it still falls within the protection scope of the present application.
  • the activation of photovoltaic strings in this application is recommended to be carried out at night.
  • the activation is performed every few days.
  • the time required for activation is related to the aging degree of the photovoltaic strings. The higher the aging degree, the longer the time required. In order to achieve a better Activation effect, the slower the voltage output from the BUCK circuit in the power supply circuit, the better, and the cumulative fall time is greater than or equal to 20 minutes.
  • the power circuit parameter of the present invention is that the operating voltage is 380V, which is directly derived from the DC voltage after the PFC of the commercial power. After the BUCK circuit, the output is 340V, which drops to 60V after 20 minutes. The operating frequency is 12KHz, and the power generation power rises to 1011W the next day. It is activated again for 20 minutes that night. On the third day, the power generation power rises to 1365W. After 11 activations, it rises to 1998W, which is close to the nominal output power. Good results have been achieved.
  • Cumulative fall time For Fig. 3-1, the working time of the power circuit is the cumulative fall time, for Fig. 3-2, the working time of the second stage of the power circuit in the broken line is the cumulative fall time, for Fig. 3-3, the power circuit is in the broken line
  • the sum of the working time of the fifth and seventh stages is the cumulative falling time
  • the sum of the working time of the second and fourth stages of the power circuit in Figure 3-3 is the cumulative falling time.
  • the inside of the photovoltaic string is equivalent to a constant current source, a most basic unit, there is a PN junction diode inside, the diode cannot be turned on when the photovoltaic string is normally activated, otherwise it will burn the CCFL conversion circuit due to current short circuit. Even through clever design and protection through current limiting circuits, electrical energy is wasted.
  • the present invention requires that the peak value of the high-frequency alternating current output by the CCFL conversion circuit should not be greater than the open circuit voltage of the activated photovoltaic string, so as to effectively avoid the conduction of the diode inside the photovoltaic string.
  • the higher the frequency the better the activation effect, but because the photovoltaic strings show a certain capacity, and will consume too much power, so for different power photovoltaic strings, you should choose different high-frequency alternating current frequency
  • the larger the cell area the greater the output power, the higher the junction capacitance, and the lower the frequency should be, even as low as 800Hz.
  • the power supply circuit for activation of the present invention consumes less energy. If the frequency is lowered, the required activation time will be longer, but it will increase the power consumption.
  • this junction capacitance is ultimately equivalent to: in parallel with the capacitor C3, and the CCFL converter is working in the resonance state of a sine wave, and its LC loop can reduce the junction capacitance energy of the photovoltaic string Absorption, so as to achieve low energy consumption, especially CCFL converters give up the use of self-excited push-pull oscillation mode, but use it to drive, so that the transistor TR1 or TR2 only conduct when the sine wave is close to the peak, the conversion efficiency is higher.
  • the CCFL converter uses a self-excited push-pull oscillation mode of operation.
  • the transistor TR1 or TR2 can only be turned on when the sine wave is close to the peak, and the conversion efficiency It is also very high.
  • the upper end of the resistor R1 in the startup circuit that is, the startup input terminal is connected to the positive input terminal of the power circuit, so that the CCFL circuit will not stop vibration.
  • the traditional color TV receiver using a glass kinescope scanned by an electron gun uses attenuated sinusoidal AC to demagnetize the kinescope. Its working principle is very simple.
  • a PTC thermistor is connected in series to the degaussing coil.
  • the resistance of PTC thermistors has risen from about 10 ohms to more than 220K, and the degaussing current has dropped from more than ten amps to less than 1mA, but this technology cannot be directly used for the activation of photovoltaic strings.
  • photovoltaic strings are capacitive, PTC thermistors cannot be connected in series.
  • the activation time required for photovoltaic strings is long, and PTC thermistors cannot be selected.
  • FIG. 4 is a schematic diagram of the improved power circuit applied to the photovoltaic power generation system according to the second embodiment of the present invention. Since the photovoltaic string internally has a diode in series with it, in order to improve the activation effect, a series is connected at the output end of the power circuit A group of DC power supply E, that is, a group of DC power supply E connected in series with the photovoltaic string, the series connection method is one of the following two:
  • the negative pole of the DC power supply is electrically connected to the second output end of the power supply circuit, the first output end of the power supply circuit is electrically connected to the positive pole of the photovoltaic string, and the negative electrode of the photovoltaic string is electrically connected to the positive pole of the DC power supply;
  • the negative pole of the DC power supply is electrically connected to the positive pole of the photovoltaic string
  • the negative pole of the photovoltaic string is electrically connected to the second output end of the power supply circuit
  • the first output end of the power supply circuit is electrically connected to the positive pole of the DC power supply.
  • electrical connection is also used to describe the connection relationship.
  • electrical connection includes not only direct connection but also indirect connection (that is, other components can be connected between two electrical connection objects), It also includes connection through inductive coupling, which has been described in the first embodiment.
  • the activation voltage obtained between the hot end and the grounding end of the photovoltaic string can be an AC voltage waveform with a positive half cycle and a negative half of the same size.
  • the positive half cycle can ensure that the diode inside the photovoltaic string is not conductive during activation. High negative pressure in half a week can obtain better activation effect.
  • FIG. 5 is a schematic diagram of a power supply circuit according to a third embodiment of the present invention.
  • the third embodiment differs from the first embodiment in that the resistor R1 is replaced with a constant current source, and the current direction is the same, so that the input voltage of the CCFL conversion circuit can be reduced
  • the current provided to the bases of the two push-pull transistors TR1 and TR2 is constant, so that the input voltage of the power supply circuit can be wider, as described above, when the operating voltage drops from 340V At 60V, the CCFL converter will not stop vibration because the base current provided by the constant current source to the transistor TR1 or TR2 is not reduced.
  • the working principle of this embodiment and its application in the photovoltaic power generation system are the same as those in the first embodiment, and are not repeated here.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

La présente invention concerne un circuit d'alimentation électrique et un système de production d'énergie photovoltaïque comprenant ce dernier. Le circuit d'alimentation électrique est un circuit d'alimentation électrique topologique à deux étages ; le premier étage est un circuit abaisseur, et traite un courant continu haute tension d'entrée en une tension continue dont la tension de sortie chute avec le temps ; le second étage est un circuit de conversion CCFL ; étant donné que le circuit de conversion CCFL fonctionne dans un mode à boucle ouverte, une valeur de crête à crête d'un courant alternatif sinusoïdal ainsi produit est proportionnel à une tension fonctionnelle du circuit de conversion CCFL, qui chute avec le temps, c'est-à-dire que la valeur de crête à crête du courant alternatif sinusoïdal produit par le circuit de conversion CCFL chute également avec le temps, et ainsi une valeur efficace du courant alternatif sinusoïdal chute également avec le temps, ce qui permet d'obtenir une tension alternative sinusoïdale atténuée. Le circuit d'alimentation agit sur deux extrémités d'une chaîne de groupes photovoltaïques activés, de telle sorte qu'une forme d'onde de tension ∆U/∆t produite par le circuit d'alimentation soit faible, et par conséquent la durée de vie de la chaîne de groupes photovoltaïques est prolongée et le rayonnement vers l'environnement est faible ; en outre, le circuit d'alimentation électrique de la présente invention est simple à mettre en œuvre et peu coûteux.
PCT/CN2019/115684 2018-12-14 2019-11-05 Circuit d'alimentation électrique et système de production d'énergie photovoltaïque comprenant ce dernier WO2020119332A1 (fr)

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