A method for power optimization control and photovoltaic power optimizer with monitoring function

Abstract

The present invention relates to the field of solar energy application technology, and specifically to a method for power optimization control and a photovoltaic power optimizer with monitoring function. The method comprises the following steps: a power conversion unit obtains the input power of a photovoltaic module according to a maximum power point tracking algorithm and converts it into output power; an ADC input / output monitoring unit monitors the input / output voltage and current in real time, and respectively calculates the input power and output power of the power conversion unit; the input power and output power are judged, and if the input power is greater than the output power, the duty cycle of a DPWM modulation unit is adjusted by a control unit according to the maximum power point tracking algorithm to perform maximum power point tracking; otherwise, the output power is adjusted so that the output power is less than the input power; and the control unit controls the DPWM duty cycle through a fast shutdown unit. The above-mentioned setting enables the optimizer to have an excellent power regulation function while realizing a fast shutdown function, and also significantly improves the quality of carrier signal transmission.

Description

Technical Field

[0001] The invention relates to the technical field of solar energy application, and in particular to a power optimization control method and a photovoltaic power optimizer with monitoring function. Background Art

[0002] Due to the renewable and clean nature of solar energy, photovoltaic grid-connected power generation technology has developed rapidly. At present, the photovoltaic system is composed of multiple photovoltaic modules connected in series to form a photovoltaic string, which is then converted into AC power by an inverter and transmitted to the power grid. Once a photovoltaic module is blocked, the output current of this module will drop instantly, thereby reducing the current of the entire string. At this time, although other photovoltaic modules are still outputting at maximum power, the current of the entire string is reduced, causing the output power of the entire string to drop instantly, affecting the power generation efficiency of the photovoltaic system. Photovoltaic power optimizers are used to solve this kind of power loss problem. Adding a power optimizer behind each photovoltaic module can adjust the output voltage and increase the current when the current of a single module drops, so that the current of the entire string does not drop significantly, reducing the power loss of the entire string and improving the power generation efficiency of the entire photovoltaic power station.

[0003] In order to monitor whether the power output of the photovoltaic module occurs, the photovoltaic power optimizer needs to use the current and voltage monitoring units to track the above parameters of the photovoltaic module in real time. The traditional voltage and current monitoring units are generally set on the positive line of the photovoltaic module, and the current and voltage output by the photovoltaic module are converted by the ADC monitoring unit and output to the control unit. However, since there is no voltage divider resistor in the current monitoring unit, the high-voltage power on the positive line is synchronously transmitted to the ADC monitoring unit, so the ADC monitoring unit is required to be able to withstand high voltages, otherwise it will be damaged, resulting in an increase in design costs.

[0004] In addition, in traditional photovoltaic power optimizers, carrier signals are often extracted from the two sections of the inductor set on the negative line to communicate with controllers such as MCU. However, when various noise signals such as electromagnetic fluctuations, high voltage, and surges on the power line are transmitted to the MCU, the MCU's own protection ability is weak and it is easily affected by these interferences, resulting in abnormal communication or direct damage to the chip. Moreover, in traditional power optimizers, power regulation is achieved by controlling the buck-boost of MOS through the DPWM unit, but when the component encounters a fault and the optimizer needs to be shut down, it cannot be shut down quickly, so that the photovoltaic component cannot cut off the output in time when an abnormality occurs, which increases the safety risk of the subsequent string. Summary of the invention

[0005] In view of the above technical problem, the first aspect of the present application provides a method for power optimization control, which comprises the following steps:

[0006] The power conversion unit obtains the input power of the photovoltaic module according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic module into the output power of the power conversion unit;

[0007] An ADC input monitoring unit disposed at the input end of the power conversion unit monitors the input voltage and input current of the power conversion unit in real time, and an ADC output monitoring unit disposed at the output end of the power conversion unit monitors the output voltage and output current of the power conversion unit in real time, and respectively calculates the input power and output power of the power conversion unit;

[0008] Determine the magnitude of the input power and the output power. If the input power is greater than the output power, adjust the duty cycle of the DPWM modulation unit through the control unit according to the maximum power point tracking algorithm to perform maximum power point tracking; if the input power is less than or equal to the output power, adjust the output power so that the output power is less than the input power;

[0009] The control unit controls the duty cycle of the DPWM modulation unit through a fast shut-down unit.

[0010] As a preferred technical solution of the present invention, the power conversion unit includes a buck module, a boost module and an energy storage module; the buck module is connected to the boost module through the energy storage module; the buck module and the boost module respectively include at least one MOS tube; the G pole of the MOS tube is connected to the DPWM modulation module through a switching resistor and a diode connected in parallel.

[0011] As a preferred technical solution of the present invention, the step-down module includes a step-down upper MOS tube and a step-down lower MOS tube; the boost module includes a boost upper MOS tube and a boost lower MOS tube; the S pole of the step-down upper MOS tube is connected to the D pole of the step-down lower MOS tube, and the D pole of the step-down lower MOS tube is connected to one end of the energy storage module; the S pole of the boost upper MOS tube is connected to the D pole of the boost lower MOS tube, and the D pole of the boost lower MOS tube is connected to the other end of the energy storage module.

[0012] As a preferred technical solution of the present invention, the ADC input monitoring unit includes an input voltage monitoring unit and an input current monitoring unit; the input current monitoring unit is arranged on the negative pole line of the photovoltaic module.

[0013] As a preferred technical solution of the present invention, the fast shutdown unit includes at least one MOS tube, the gate of the MOS tube is connected to the GPIO interface of the control unit, and the drain is connected to the DPWM modulation unit through a voltage divider resistor.

[0014] As a preferred technical solution of the present invention, the fast shutdown unit includes a first MOS tube and a second MOS tube, the gate of the first MOS tube is connected to the GPIO interface of the control unit, and the drain of the first MOS tube is connected to the power supply unit through a first pull-up resistor; the power supply unit is connected to the DPWM modulation unit through a first voltage-dividing resistor; the drain of the first MOS tube is connected to the gate of the second MOS tube through a second pull-up resistor, and the drain of the second MOS tube is connected to the DPWM modulation unit through one end of the first voltage-dividing resistor.

[0015] As a preferred technical solution of the present invention, the control unit controls the duty cycle of the DPWM modulation unit by turning on and off the fast shutdown unit according to feedback from a communication unit arranged at the power output side of the power conversion unit.

[0016] As a preferred technical solution of the present invention, the feedback of the communication unit includes the absence of a heartbeat signal and / or a shutdown instruction.

[0017] The second aspect of the present invention provides a photovoltaic power optimizer with a monitoring function, which is applied to the power optimization of photovoltaic components, and includes an ADC input monitoring unit, an ADC output monitoring unit, a power conversion unit, a DPWM modulation unit, a control unit, and a communication unit; the power conversion unit obtains the input power of the photovoltaic component according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic component into the output power of the power conversion unit; the ADC input monitoring unit is arranged at the input end of the power conversion unit, and monitors the input current and input voltage of the power conversion unit in real time; the ADC output monitoring unit is arranged at the output end of the power conversion unit, and monitors the output voltage and output current of the power conversion unit in real time; the DPWM modulation unit is connected to the power conversion unit, and the DPWM modulation unit is used to adjust the output voltage and output current of the power conversion unit; the control unit is connected to the DPWM modulation unit, and the control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit.

[0018] As a preferred technical solution of the present invention, the communication unit includes a carrier processor, an isolation transformer and an inductor, and the carrier processor is connected to the control unit.

[0019] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0020] In the photovoltaic power optimizer of the present invention, a fast shutdown unit is set between the control unit and the DPWM modulation unit, that is, a function of fast shutdown is added on the basis of power optimization, and the DPWM modulation control is realized on and off through the GPIO of the digital controller MCU, so that when the photovoltaic component encounters a fault or abnormal condition, the component output can be turned off in time, thereby protecting the safety of the entire string power supply. In addition, through the clever design of the fast shutdown unit circuit, and the design and resistance optimization of the voltage divider resistor circuit, while ensuring a small current loss, the high and low levels provided by the logic control unit are cleverly reversed multiple times to ensure the stable conduction and cutoff of the MOS switch, so that when the GPIO interface of the logic control unit outputs a high level, the MOS switch set on the negative line of the photovoltaic component is turned on, and the power of the component is output to the subsequent component; when the GPIO interface of the logic control unit outputs a low level, the MOS switch set on the negative line of the photovoltaic component is cut off, blocking the power output.

[0021] In addition, the present invention sets the ADC input and output current monitoring module on the negative line of the photovoltaic module, and reduces the requirements for the ADC chip without affecting the accuracy of current monitoring by optimizing the resistance value of the series resistor and the corresponding resistor, avoiding the high voltage that the ADC chip may bear, and can still operate normally when using a conventional ADC chip, effectively reducing the overall design cost. Moreover, in the present invention, an isolation transformer is set between the carrier signal extracted from the power line and the transmission MCU to isolate the clutter signal, reduce the impact of the respective interference on the power line on the communication quality, and protect the MCU from damage caused by the respective interference, while also enhancing the transmission quality of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of a circuit framework of a photovoltaic power optimizer with a monitoring function provided by the present invention.

[0024] Figure 2 A schematic diagram of a circuit framework of a fast shutdown unit in a photovoltaic power optimizer with a monitoring function provided by the present invention.

[0025] Figure 3 A schematic flow chart of a method for power optimization control provided by the present invention.

[0026] Figure 4 A schematic diagram of the internal principle of an MPPT in a method for power optimization control provided by the present invention.

[0027] Figure 5 A schematic diagram of a power supply unit in a photovoltaic power optimizer with a monitoring function provided by the present invention. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0029] In the following introduction, the terms "first" and "second" are only used for descriptive purposes and are not to be understood as indicating or implying relative importance. The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements described without departing from the scope of the present application. Various processes or components may be appropriately omitted, substituted or added to each example. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, the features described in some examples may be combined in other examples.

[0030] In view of the above technical problem, the first aspect of the present application provides a method for power optimization control, which comprises the following steps:

[0031] The power conversion unit obtains the input power of the photovoltaic module according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic module into the output power of the power conversion unit;

[0032] An ADC input monitoring unit disposed at the input end of the power conversion unit monitors the input voltage and input current of the power conversion unit in real time, and an ADC output monitoring unit disposed at the output end of the power conversion unit monitors the output voltage and output current of the power conversion unit in real time, and respectively calculates the input power and output power of the power conversion unit;

[0033] Determine the magnitude of the input power and the output power. If the input power is greater than the output power, adjust the duty cycle of the DPWM modulation unit through the control unit according to the maximum power point tracking algorithm to perform maximum power point tracking; if the input power is less than or equal to the output power, adjust the output power so that the output power is less than the input power;

[0034] The control unit controls the duty cycle of the DPWM modulation unit through a fast shut-down unit.

[0035] The term “ADC” in this application refers to an analog-to-digital converter well known to those skilled in the art; the term “DPWM” refers to a digital pulse width modulator well known to those skilled in the art.

[0036] See attached Figure 3 When the power optimizer is powered on and started, the input voltage and input current of the power conversion unit are monitored through the ADC input monitoring unit, and the monitoring results are transmitted to the control unit, and the control unit obtains the input power Pin of the power conversion unit by calculating (the product of the input voltage and the input current); and the output voltage and output current output from the power conversion unit are monitored in real time through the ADC output monitoring unit, and the monitoring results are also transmitted to the control unit, and the output power Pout is calculated in the same way. The power conversion unit is a unit used to convert the input power into output power by boosting or bucking, and the corresponding boost conversion module and buck conversion module (i.e., boost module and buck module) are arranged inside it, which will output a specific voltage and current according to the initial setting value, that is, output a specific power. In the initial state of power-on, the initial setting of the power conversion unit can be a buck output mode, that is, the input power is bucked, and the processed power is output as the output power Pout of the power conversion unit (i.e., low voltage, high current power); in the initial state, the power conversion unit can also be initially set to a boost output mode, that is, the input power is boosted, and the boosted power is output as the output power Pout of the power conversion unit (i.e., high voltage, low current power). In the above-mentioned boost mode or buck mode, since only the voltage or current of the input power is increased or decreased, it will not have an essential impact on the product of current and voltage. However, due to the consumption of the output power of the photovoltaic module (i.e., the output power of the power conversion unit) by the power conversion unit and other modules in the power optimizer, the output power Pout of the power conversion unit is reduced to Pout<Pin. This state is a normal operating state. At this time, MPPT tracking is started. According to the maximum power point tracking algorithm, the control unit adjusts the duty cycle of the DPWM modulation unit to perform maximum power point tracking to ensure that the output power of the power conversion unit is maximized.

[0037] When a photovoltaic module suddenly fails or is blocked during operation, the output current of the photovoltaic module will suddenly drop, causing the input power Pin of the power conversion unit to drop. The output power Pout of the power conversion unit is calculated by the ADC output monitoring unit based on the output voltage and output current at the previous moment. Therefore, Pout at the same moment will not change significantly. At this time, Pout≥Pin is instantaneously caused, and it is judged as an abnormal operation. The MPPT tracking is suspended, and the buck module in the power conversion unit is called to reduce the output voltage of the power conversion unit and increase the output current, so that Pout<Pin. Since the condition of Pout<Pin is met, the MPPT tracking mode is started again to track the highest power.

[0038] Among them, the maximum power point tracking mode is executed using the MPPT algorithm. The MPPT algorithm is not specifically limited in this application and can be executed according to various algorithms familiar to technical personnel in this field, including but not limited to the perturbation observation method, the conductance increment method, and improved algorithms of these two algorithms.

[0039] In the present application, when a photovoltaic module fails or is blocked or other abnormal phenomena occur, the control unit confirms the abnormal situation through the input voltage and input current detected in real time by the ADC input monitoring unit, and adjusts the duty cycle of the DPWM modulation unit to enable the built-in boost module, buck module, etc., and adjust the output current and voltage to make it work on the MPP.

[0040] When a photovoltaic component in a photovoltaic system has a serious fault, and the simple adjustment of current and voltage still cannot eliminate the impact of the component on photovoltaic strings, photovoltaic arrays, etc., it is necessary to shut down the photovoltaic component from the string and isolate it from other components. Since transistors or switches such as MOS tubes are required to perform boost or buck operations in the power conversion unit, and their shutdown and conduction need to receive corresponding shutdown and conduction instructions, and also need to meet corresponding voltage strength and other requirements, the DPWM modulation unit cannot quickly control the shutdown and conduction of related modules. In this application, the control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit. The control unit is connected to the DPWM modulation unit through the fast shutdown unit. When a photovoltaic component fails and needs to be shut down, the corresponding control unit uses the fast shutdown unit to quickly control the DPWM modulation unit to shut down the corresponding MOS tube, etc., thereby preventing the power output of the corresponding photovoltaic component.

[0041] In some embodiments of the present invention, the power conversion unit includes a buck module, a boost module and an energy storage module; the buck module is connected to the boost module through the energy storage module; the buck module and the boost module each include at least one MOS tube; the G pole of the MOS tube is connected to the DPWM modulation module through a switching resistor and a diode connected in parallel. Further, the buck module includes a buck upper MOS tube and a buck lower MOS tube; the boost module includes a boost upper MOS tube and a boost lower MOS tube; the S pole of the buck upper MOS tube is connected to the D pole of the buck lower MOS tube, and the D pole of the buck lower MOS tube is connected to one end of the energy storage module; the S pole of the boost upper MOS tube is connected to the D pole of the boost lower MOS tube, and the D pole of the boost lower MOS tube is connected to the other end of the energy storage module.

[0042] See attached Figure 1 The DPWM modulation unit controls the output voltage and output current by adjusting the duty cycle of the buck upper MOS tube and the boost upper and lower MOS tubes. Among them, the MOS tube Q1 is the buck upper MOS tube, Q2 is the buck lower MOS tube, Q3 is the boost lower MOS tube, and Q4 is the boost upper MOS tube. The G poles of the above MOS tubes are connected to the DPWM modulation unit through a switching resistor and a diode connected in parallel, and the anode of the diode is connected to the G pole of the MOS tube, and its cathode is connected to the DPWM modulation unit through one end of the switching resistor. Through the switching resistor and diode connected in parallel, the MOS tubes in the buck module and the boost module can achieve faster level switching when turning on and off, avoiding the long time of the turning on and off process, causing the MOS tube to lose too much and fail.

[0043] Furthermore, the MOS tubes Q (1-4) in the buck module and the boost module are connected to the DPWM modulation unit via an enhanced PWM signal. The DPWM modulation unit is responsible for controlling the on and off time of the four MOS tubes in real time. In this way, the output and input duty ratios of the power conversion unit are kept in a relatively stable state, and the output voltage jump will not be caused.

[0044] Furthermore, the energy storage module may use electrical devices or circuit elements that can store electrical energy, which may include but are not limited to inductors. When the upper MOS tube (such as MOS tube 1 or Q3) in the buck module or the boost module is turned on, the energy storage module is used to store electrical energy, and when the lower MOS tube (such as MOS tube Q2 or Q4) in the buck module and the boost module is turned on, the energy storage module uses the stored electrical energy to power the load. By frequently switching the on and off of the MOS tube through PWM, the power output from the photovoltaic module can always be passed through the energy storage module (such as inductor L1) to the subsequent stage, so that the output will not be interrupted.

[0045] Furthermore, the MOS tubes in the boost module and the buck module can be MOS tubes with the same specification parameters or MOS tubes with different specification parameters. If the specification parameters of the MOS tubes are different, it is necessary to eliminate the difference in the shutdown and startup time of the MOS tubes caused by the difference in the MOS tubes through modulation control by the DPWM modulation unit. Preferably, the present invention uses MOS tubes with the same specification parameters, and uniformly controls them through DPWM modulation, effectively avoiding output instability caused by the difference in the startup and shutdown time of the MOS tubes.

[0046] Furthermore, the input current range of the power optimizer described in the present application is 0~20A, and the input voltage range is 0~80V. Furthermore, the conduction voltage between the D pole and the S pole of the MOS tube used in the boost module and the buck module (i.e., Vds) is higher than 80V, and further 100V; the maximum input current of the D pole (i.e., Id) is greater than 20A, and further, the maximum input current of the D pole is 100A. When the output current of the photovoltaic module is at the highest output current (i.e., the input current of the power optimizer is at the highest input current state), the heat of the MOS tube body will be more serious, and once the MOS tube heats up to 100℃, the Id current bearing capacity will drop to 60~70% at 25℃, and as the heat increases, the Id current bearing capacity will drop more. After a large number of experimental analyses, it is found that when the maximum current of the MOS tube Id used meets 4~5 times the product support current, the stability of the product at the maximum current can be guaranteed.

[0047] Furthermore, the resistance Rds between the D pole and the S pole of the MOS tube used in the boost module and the buck module shall not be too large. After experimental analysis, the applicant found that when the Rds resistance of the MOS tube used is higher than 3.5MΩ, the power consumption of the MOS tube itself in the boost module and the buck module of the power optimizer reaches 1.5W or even higher under the highest input current state, resulting in a lack of time for the internal wafer to dissipate heat to the outer surface of the body, causing the buck module and the boost module to be turned on and off uncontrollably, or the response speed to related instructions becomes slower or even loses response, directly affecting the function of the power optimizer. Therefore, in some preferred embodiments, the Rds resistance of the MOS tube in the boost module and the buck module is lower than 3.5M.

[0048] Further, the G pole of the MOS tube in the buck module and the boost module is connected to the DPWM modulation unit through a switching resistor and a diode connected in parallel, wherein the switching resistor needs to be a resistor with a reasonable resistance value, which, on the one hand, limits the current of the G pole of the MOS tube, and at the same time cannot affect the driving ability of the G pole of the MOS tube. In some preferred embodiments, the switching resistor uses a switching resistor with a resistance of 10Ω. Further, the diode is preferably a Schottky diode. Since when the DPWM drives the MOS to turn on or off, it only relies on the charging and discharging of the switching resistor, and the response speed is not fast enough, the parallel connected Schottky diode allows the on and off response speed of the MOS tube to be improved, effectively improving the stability of the power output.

[0049] In some implementations of the present invention, the ADC input monitoring unit includes an input voltage monitoring unit and an input current monitoring unit; the input current monitoring unit is arranged on the negative pole line of the photovoltaic module.

[0050] The ADC monitoring unit in the present application includes an ADC large input monitoring unit and an ADC output monitoring unit, which are used to determine the difference between the input power and the output power, thereby providing a basis for determining whether to perform MPPT. Furthermore, the ADC input monitoring unit and the ADC output monitoring unit respectively include a voltage monitoring unit and a current monitoring unit, wherein the input voltage and the output voltage are supplied to the ADC port after being divided by corresponding voltage-dividing resistors, and then the ADC calculates the current real-time input and output voltages through a certain conversion company and then transmits them to the control unit; wherein the input and output currents are processed in a differential manner, and the voltage difference between the front and rear ends flowing through the 1 milliohm resistor is transmitted to the ADC, and the ADC then calculates the current real-time input and output currents through a certain conversion method.

[0051] For further information, see Appendix Figure 1, the voltage monitoring unit includes two voltage-dividing resistors R1 and R2 (R10 and R11). Since the highest input voltage reaches 80V, the voltage after voltage division does not exceed a certain range and does not exceed the voltage tolerance range of ADC. Therefore, the resistance value of the voltage-dividing resistor should be optimized and screened; in some preferred embodiments, one end of the voltage-dividing resistor R1 (R10) is connected to the positive input of the photovoltaic module, and the other end is connected to one end of the voltage-dividing resistor R2 (R11), and the other end of the voltage-dividing resistor R2 (R11) is grounded, and the connecting end of the voltage-dividing resistor R2 (R11) and the voltage-dividing resistor R2 (R11) is connected to the control unit. Further, in order to filter out the influence of the noise interference of the input voltage signal on the accuracy of ADC conversion, the voltage monitoring unit also includes a filter capacitor C21 (C22), one end of which is connected to the connecting end of the voltage-dividing resistors R1 and R2, and the other end is grounded through the other end of the voltage-dividing resistor R2. Furthermore, the voltage-dividing resistor R1 (R10) adopts a resistor with a resistance value of 250~350K, and the voltage-dividing resistor R2 (R11) adopts a resistor with a resistance value of 15~25K; further, the voltage-dividing resistor R1 (R10) adopts a resistor with a resistance value of 300K, and the voltage-dividing resistor R2 (R11) adopts a resistor with a resistance value of 20K.

[0052] Furthermore, the current monitoring unit in the present application is arranged on the negative line of the photovoltaic module. Since the power input from the photovoltaic module is input from the positive line and flows back from the negative line to form a closed return path, the current value flowing through the negative line of the photovoltaic module can still be detected, and at the same time, it does not need to withstand the high voltage on the positive line to avoid damaging the ADC. Figure 1 The current monitoring unit includes series resistors R3 (R12), R4 (R13) and R5 (R14), one end of the series resistor R3 (R12) is connected to the negative input end of the photovoltaic module, and the other end is grounded; the negative input end of the photovoltaic module is also connected to one end of the series resistor R4 (R13), the other end of the resistor R4 (R13) is connected to the control unit, one end of the resistor R5 (R13) is grounded through one end of the resistor R3 (R12), and the other end of the resistor R5 (R13) is connected to the control unit.

[0053] Furthermore, in order to minimize the loss of the series resistor R3 (R12) when the current flows through the series resistor R3 (R12) and avoid affecting the detected current value, the resistance of the series resistor R3 (R12) should not be too large. In some preferred embodiments of the present application, the series resistor R3 (R12) uses a resistor with a resistance of 0.001Ω. Furthermore, in order to limit the current of the signal transmitted to the ADC to a certain extent and prevent damage to the ADC components, the resistance of R4 (R13) and R5 (R14) is optimized. In some preferred embodiments of the present application, the series resistor R4 (R13) and R5 (R14) use a resistor with a resistance of 1K.

[0054] In some preferred implementations of the present application, the ADC end of the ADC input monitoring and the ADC output monitoring communicates with the control unit (such as MCU) via I2C. The I2C protocol itself supports one master and multiple slaves. The control unit, as the master device, communicates with each slave device in turn through different address settings of the slave device. The communication rate can basically meet the ADC data conversion requirements, and the communication delay will basically not affect the processing judgment of the control unit.

[0055] In some embodiments of the present invention, see the attached Figure 2 , the fast shutdown unit includes at least one MOS tube, the gate of the MOS tube is connected to the GPIO interface of the control unit, and the drain is connected to the DPWM modulation unit through a voltage-dividing resistor. Further preferably, the fast shutdown unit includes a first MOS tube and a second MOS tube, the gate of the first MOS tube is connected to the GPIO interface of the control unit, and the drain is connected to the power supply unit through a first pull-up resistor; the power supply unit is connected to the DPWM modulation unit through a first voltage-dividing resistor; the drain of the first MOS tube is connected to the gate of the second MOS tube through a second pull-up resistor, and the drain of the second MOS tube is connected to the DPWM modulation unit through one end of the first voltage-dividing resistor.

[0056] Through the above-mentioned fast shutdown unit setting, the control and switching of the DPWM modulation unit will be realized through the GPIO port of the control unit (such as MCU), so that when the photovoltaic module encounters a fault or abnormal condition, the power output of the photovoltaic module can be quickly shut down, thereby protecting the entire photovoltaic string from being below the safe voltage.

[0057] In some embodiments of the present invention, the control unit controls the duty cycle of the DPWM modulation unit by turning on and off the fast shutdown unit according to the feedback of the communication unit arranged on the power output side of the power conversion unit. The communication unit described in the present application includes a carrier processor (for example, a carrier communication chip), which can modulate the input voltage, input current, output voltage, output current and other information sent from the control unit, modulate it into a corresponding carrier signal and transmit it to the remote unit, so that the remote unit can understand the operation status of the corresponding photovoltaic component in real time. At the same time, the communication unit can also extract the carrier signal such as the shutdown instruction and heartbeat signal sent from the remote unit, demodulate it to form a corresponding digital signal, and transmit the signal to the control unit, so that the control unit takes corresponding control measures according to these signals.

[0058] The control unit in the present invention takes corresponding shut-off and conduction operations according to the feedback of the communication unit. The operation mainly stops the DPWM modulation unit in the working state through the fast shut-off unit, so that the corresponding MOS tubes in the buck module and the boost module of the power conversion unit are disconnected, so as to achieve the purpose of shutting off the power of the corresponding photovoltaic module. In some embodiments, the feedback of the communication unit includes the absence of the heartbeat signal, the signal becomes irregular and / or the shutdown instruction, etc. In some embodiments, the communication unit transmits the periodic heartbeat signal sent by the remote unit to the control unit. If the control unit can normally receive the heartbeat signal, the DPWM modulation unit is kept to normally control the duty cycle of the buck module and the boost module, and the conventional operation mode is performed; if the control unit does not receive the heartbeat signal of the remote unit, or the reception period of the heartbeat signal exceeds a certain threshold range, the control unit turns off the corresponding MOS tubes in the buck module and the boost module through the fast shut-off unit to block the power output of the corresponding photovoltaic module. Correspondingly, when the remote unit sends a shutdown instruction, the power output of the corresponding photovoltaic module can also be blocked in the above manner. The remote unit described in the present application can be a cloud controller, a client, etc.

[0059] The DPWM modulation unit, control unit, ADC input monitoring unit, ADC output monitoring unit and communication unit described in the present invention are provided with corresponding processing chips, and the specific selection of the chips is not particularly limited; further, the chips and fast shutdown units in the above units can be powered by external power to ensure their normal operation, or they can be powered by electricity from photovoltaic components to ensure their normal operation.

[0060] For further information, see Appendix Figure 5, the fast shutdown unit includes a power supply unit, and the power supply unit includes a primary power supply module, a secondary power supply module and a tertiary power supply module. After the primary power supply module obtains power from the photovoltaic component, it performs voltage reduction processing and outputs the power after voltage reduction processing to the corresponding functional module or functional unit and the secondary power supply module. The secondary power supply module further performs voltage reduction processing on the input power and outputs it to the tertiary power supply module and the corresponding functional module or functional unit; further preferably, the output voltage range of the primary power supply module is 7~14V; further preferably, the output voltage of the secondary power supply module is 4.5~5.5V; further preferably, the output voltage of the tertiary power supply module is 3~3.6V; further, the fast shutdown unit, the ADC input monitoring unit and the ADC output monitoring unit are powered by the photovoltaic component, and further, the primary power supply module supplies its power output to the fast shutdown unit, the ADC input monitoring unit and the ADC output monitoring unit. Furthermore, the DPWM modulation unit, the control unit and the communication unit are powered by photovoltaic components. Furthermore, the secondary power supply module supplies its power output to the DPWM modulation unit, and the tertiary power supply module supplies its power output to the control unit and the communication unit.

[0061] In some implementations of the present application, the DPWM modulation unit communicates with the control unit via a UART serial port, and the communication unit communicates with the MCU via a UART serial port. Here, the MCU needs to support multiple UART serial ports. Since the UART communication rate is higher than that of I2C, it can process more data.

[0062] The second aspect of the present invention provides a photovoltaic power optimizer with a monitoring function, which is applied to the power optimization of photovoltaic components, and includes an ADC input monitoring unit, an ADC output monitoring unit, a power conversion unit, a DPWM modulation unit, a control unit, and a communication unit; the power conversion unit obtains the input power of the photovoltaic component according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic component into the output power of the power conversion unit; the ADC input monitoring unit is arranged at the input end of the power conversion unit, and monitors the input current and input voltage of the power conversion unit in real time; the ADC output monitoring unit is arranged at the output end of the power conversion unit, and monitors the output voltage and output current of the power conversion unit in real time; the DPWM modulation unit is connected to the power conversion unit, and the DPWM modulation unit is used to adjust the output voltage and output current of the power conversion unit; the control unit is connected to the DPWM modulation unit, and the control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit.

[0063] In some embodiments of the present invention, the communication unit includes a carrier processor, an isolation transformer and an inductor, and the carrier processor is connected to the control unit. Further, the inductor is arranged on the negative output power line of the photovoltaic module, and the carrier processor extracts the carrier signal from the coupling of the two ends of the inductor, and transmits it to the control unit after demodulation; further, since the carrier signal extracted from the power line will carry its own carrier and interference, an isolation transformer is arranged between the carrier processor and the inductor to process the above interference to avoid damage to the control unit; further, since the power input of the photovoltaic module is relatively high, there can be a higher voltage on the power line. In order to avoid damage to various chips in this power optimizer by high voltage, a safety capacitor is arranged between the inductor and the isolation transformer for protection.

[0064] In some preferred embodiments of the present invention, a bypass diode is provided between the positive output line and the negative output line of the photovoltaic power optimizer with monitoring function. When the photovoltaic module fails and power cannot be input normally, the bypass diode can be turned on to bypass the corresponding single photovoltaic module, and the bypass diode is used to supply power to the subsequent output, so that the entire system is not affected by the failure of a single photovoltaic module and the power supply of the entire string is not affected.

[0065] In some preferred embodiments of the present invention, an input filter capacitor is provided between the positive input line and the negative input line of the photovoltaic power optimizer with monitoring function; further, as a filter capacitor at the input end of the component, it can effectively filter out high-frequency interference and carrier on the power line. Since the photovoltaic optimizer must meet certain life requirements, electrolytic capacitors, tantalum capacitors, etc. cannot be used, which have limited lifespans. Therefore, ceramic capacitors are more suitable. The capacitance of high-voltage ceramic capacitors is relatively small. Multiple small-capacitance capacitors are selected in parallel to make the total capacitance become 33uF, which has the best filtering effect on the PWM control front end. Further, an output filter capacitor is provided between the positive output line and the negative output line of the photovoltaic power optimizer, which is used to filter the power of the PWM control output back end.

[0066] Embodiment: This embodiment provides a photovoltaic power optimizer with monitoring function, which is applied to the power optimization of photovoltaic components, and includes an ADC input monitoring unit, an ADC output monitoring unit, a power conversion unit, a DPWM modulation unit, a control unit, and a communication unit; the power conversion unit obtains the input power of the photovoltaic component according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic component into the output power of the power conversion unit; the ADC input monitoring unit is arranged at the input end of the power conversion unit, and monitors the input current and input voltage of the power conversion unit in real time; the ADC output monitoring unit is arranged at the output end of the power conversion unit, and monitors the output voltage and output current of the power conversion unit in real time; the DPWM modulation unit is connected to the power conversion unit, and the DPWM modulation unit is used to adjust the output voltage and output current of the power conversion unit; the control unit is connected to the DPWM modulation unit, and the control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit, wherein. The DPWM and the control unit (MCU) communicate with each other through a serial port.

[0067] See attached Figure 1The positive line of the photovoltaic module is connected to one end of a voltage-dividing resistor R1 (300K), and the other end thereof is connected to one end of a voltage-dividing resistor R2, and the other end of the voltage-dividing resistor R2 (20K) is grounded; a filter capacitor C21 (10nF) is connected between the two ends of the voltage-dividing resistor R2, and an ADC input monitoring unit (using an ADC of model TMS320F280025) is connected at the connection between the voltage-dividing resistor R1 and the voltage-dividing resistor R2. The ADC input monitoring unit includes an input voltage monitoring module, and the connection between the voltage-dividing resistor R1 and the voltage-dividing resistor R2 is connected to the input voltage monitoring module of the ADC input monitoring unit; the negative line of the photovoltaic module is connected to a series resistor R3 (0.00 1R), whose input end is connected to one end of the series resistor R4 (1K), the other end of the series resistor R4 is connected to the ADC input monitoring unit, the ADC input monitoring unit includes an input current monitoring module, the other end of the series resistor R4 is connected to the input current monitoring module, the output end of the series resistor R3 is connected to one end of the series resistor R5 (1K), the other end of which is connected to the input current monitoring module, the ADC input monitoring unit is connected to the control unit, the control unit is a digital controller MCU (the MCU model can be TMS320F280025); 10 input filter capacitors (C1 ~C10), each with a capacitance of 3.3nF, forming a filter capacitor with a capacitance of 33nF, the negative electrode line of the input filter capacitor C10 is grounded; the connection point on the positive electrode line of the input filter capacitor C10 is connected to the D pole of the MOS tube Q1, and its G pole is connected to the DPWM modulation module (using a modulation chip of model SM72442) through a switching resistor R6 (10K) and a diode D1 connected in parallel, and its S pole is connected to the D pole of the MOS tube Q2 and one end of the inductor L1 (15μH); the G pole of the MOS tube Q2 is connected to the DPWM modulation module through a switching resistor R7 (10K) and a diode D2 connected in parallel, and its D pole is connected to the inductor L1 through the S pole of the MOS tube Q1. One end of the inductor L1, the S pole of the MOS tube Q2 is grounded; the other end of the inductor L1 is connected to the D pole of the MOS tube Q3 and the S pole of the MOS switch Q4; the G pole of the MOS tube Q3 is connected to the DPWM modulation module through the switching resistor R8 (10K) and the diode D3 connected in parallel, and its S pole is grounded; the G pole of the MOS switch Q4 is connected to the DPWM modulation module through the switching resistor R9 (10K) and the diode D4 connected in parallel, and its D pole is connected to the output filter capacitor (C11~C20) composed of 10 pieces of 3.3nF in parallel, and the negative pole line of the output filter capacitor C11 is grounded; the series resistor R12 (0.001R), the two ends of the series resistor R12 are respectively connected to the series resistors R13 (1K) and R14 (1K), the other ends of the series resistors R13 and R14 are connected to the ADC output monitoring unit (using the ADC model TMS320F280025), the ADC output monitoring unit includes a voltage output monitoring module and a current output monitoring module, the other ends of the series resistors R13 and R14 are connected to the current output monitoring module; one end of the voltage divider resistor R10 (300K) is connected in parallel to the positive line connection point of the output filter capacitor C20, and the other end is connected to one end of the voltage divider resistor R11 (20K), and the other end of the voltage divider resistor R11 is grounded; the filter capacitor C22 (10nF) is connected between the two ends of the voltage divider resistor R11, and the connection between the voltage divider resistors R10 and R11 is connected to the voltage output monitoring module; the ADC output monitoring unit is connected to the digital controller MCU. .

[0068] See attached Figure 1 A bypass diode D5 is arranged between the positive output line and the negative output line of the photovoltaic module. The bypass diode D5 is connected to one end of the inductor L2 (1μH) at the connection on the negative output line, and the other end is connected to the power output end of the power optimizer; the two ends of the inductor L2 are connected to the isolation transformer T1, and a safety capacitor C23 (10nF) is arranged between the No. 5 interface of T1 and the negative line of the photovoltaic module. The No. 3 and No. 4 interfaces of the isolation transformer T1 are connected to the carrier processor of the communication unit (using a chip with model number SLC9203), and the carrier processor is connected to the digital controller MCU; the fast shutdown unit is arranged between the MCU and the DPWM modulation unit.

[0069] See attached Figure 2 The fast shutdown unit includes a MOS tube Q1-1 and a MOS gate Q1-2; the G pole of the MOS tube Q1-1 is connected to the GPIO interface of the MCU, the S pole thereof is grounded, and a resistor R1-1 (10K) is connected between the G pole and the S pole of the MOS tube Q1-1; the D pole of the MOS tube Q1-1 is connected to a primary power supply module through a first pull-up resistor R1-2 (100K), and the primary power supply module is connected to the DPWM modulation unit through a first voltage-dividing resistor R1-3 (10K); the D pole of the MOS tube Q1-1 is connected to the G pole of the MOS gate Q1-2 through a second pull-up resistor R1-4, the S pole thereof is grounded, and a resistor R1-5 (1M) is connected between the S pole and the G pole of the MOS gate Q1-2; the D pole of the MOS gate Q1-2 is connected to the DPWM modulation unit through one end of the first voltage-dividing resistor R1-3, and the D pole of the MOS gate Q1-2 is connected to the primary power supply module through a second voltage-dividing resistor R1-6 (1M).

[0070] See attached Figure 5 , the above-mentioned fast shutdown unit, communication unit, ADC input monitoring unit, MCU, DPWM modulation unit and ADC output monitoring unit are all powered by a power supply unit, and the power supply unit takes power from the photovoltaic module and supplies power to the above-mentioned components. Specifically: the first-level power supply module (i.e., the first-level DC / DC converter) is connected between the positive input line and the negative input line of the photovoltaic module to obtain its input power, and the first-level power supply module performs voltage reduction processing on it and outputs a 7~14V voltage to power the fast shutdown unit and the communication unit (carrier processor), and at the same time, the output voltage after voltage reduction is supplied to the second-level power supply module (i.e., the second-level DC / DC converter), and the second-level power supply module further performs voltage reduction processing on the output of the first-level power supply module and outputs a 4.5~5.5V voltage, which is transmitted to the third-level power supply module and supplies power to the DPWM modulation unit; the second-level power supply module further performs voltage reduction processing on the output of the second-level power supply module and outputs a 3~3.6V voltage, and supplies power to the ADC output monitoring unit, MCU, and ADC output monitoring unit.

[0071] See attached Figure 4 The MPPT algorithm control is realized by a DC / DC conversion circuit composed of four MOS tubes in the boost module and buck module of the power conversion unit. The photovoltaic module is connected to the load through a DC / DC circuit. The maximum power tracking device continuously detects the current and voltage changes of the photovoltaic module and adjusts the PWM drive signal duty cycle of the DC / DC converter according to the changes. Figure 4 , the photovoltaic module can be simplified into a constant voltage source and an internal resistance Ri, and the external circuit can be simplified into a load Ro. For a linear circuit, when the load resistance is equal to the internal resistance of the power supply, the power supply has maximum power output. Although both the photovoltaic module and the DC / DC conversion circuit are strongly nonlinear, they can be considered as linear circuits in a very short time. Therefore, as long as the duty cycle of the DC / DC conversion circuit is adjusted so that the equivalent resistance of the load is always almost equal to the internal resistance of the photovoltaic module battery, the maximum power output of the photovoltaic module can be achieved, and the MPPT maximum power tracking can be achieved.

[0072] See attached Figure 2When a photovoltaic module fails or operates abnormally, and the power output of the photovoltaic module needs to be shut down, this can be achieved through the fast shutdown unit. The MCU controls the entire fast shutdown unit through the GPIO signal. When the power is initially turned on, the MCU's GPIO interface is in a high-impedance state. At this time, the G pole of the MOS tube Q1-1 is connected to the resistor R1-1, so the G pole and the S pole of the device are both at a low level, and the MOS tube Q1-1 is in a cut-off state; the D pole of the MOS tube Q1-1 is connected to the 10V voltage of the primary power supply module through the pull-up resistor R1-2. At this time, the D pole level is 10V, and the D pole is connected to the G pole of the MOS tube Q1-2 through the resistor R1-4. Therefore, at this time, the G pole of the MOS tube Q1-2 is at a high level (10V), and the S pole of the MOS tube is directly connected to the ground. At this time, Vg-Vs>2V is satisfied, and the MOS tube Q1-2 is turned on, and its D pole level is consistent with the S pole level, which is a low level (ground ), which is equivalent to the EN signal (enable signal) output to the DPWM modulation unit at this time being low level, turning off the DPWM modulation control; when the MCU's GPIO interface outputs a high level, the G pole level of the MOS tube Q1-1 becomes high, and Vgs generates a voltage difference. At this time, the MOS tube Q1-1 is turned on, and its D pole level is consistent with the S pole level (ground); and the G pole of the MOS tube Q1-2 is connected to the D pole of the MOS tube Q1-1, so the G pole of the MOS tube Q1-2 is also low level (ground), and the MOS tube Q1-2 is in the cut-off state, and the D pole of the MOS tube Q1-2 is connected to the 10V voltage of the primary power supply module through the resistor R1-6, which is equivalent to the EN signal output to the DPWM modulation unit at this time being high level, turning on the DPWM modulation control. As described above, the DPWM modulation control is turned on and off through the GPIO of the digital controller MCU, so that when the photovoltaic module encounters a fault or abnormal condition, the module output can be turned off in time, thereby protecting the safety of the entire string power supply.

[0073] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for power optimization control, characterized in that: It includes the following steps: The power conversion unit obtains the input power of the photovoltaic module according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic module into the output power of the power conversion unit; An ADC input monitoring unit disposed at the input end of the power conversion unit monitors the input voltage and input current of the power conversion unit in real time, and an ADC output monitoring unit disposed at the output end of the power conversion unit monitors the output voltage and output current of the power conversion unit in real time, and respectively calculates the input power and output power of the power conversion unit; Determine the magnitude of the input power and the output power. If the input power is greater than the output power, adjust the duty cycle of the DPWM modulation unit through the control unit according to the maximum power point tracking algorithm to perform maximum power point tracking; if the input power is less than or equal to the output power, adjust the output power so that the output power is less than the input power; The control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit; The power conversion unit includes a buck module, a boost module and an energy storage module; the buck module is connected to the boost module through the energy storage module; the buck module and the boost module each include at least one MOS tube; the G pole of the MOS tube is connected to the DPWM modulation module through a switching resistor and a diode connected in parallel, the S pole is grounded, and the D pole is connected to a capacitor; The ADC input monitoring unit includes an input voltage monitoring unit and an input current monitoring unit; the input current monitoring unit is arranged on the negative pole line of the photovoltaic module.

2. The method for power optimization control according to claim 1, characterized in that: The buck module includes a buck upper MOS tube and a buck lower MOS tube; the boost module includes a boost upper MOS tube and a boost lower MOS tube; the S pole of the buck upper MOS tube is connected to the D pole of the buck lower MOS tube, and the D pole of the buck lower MOS tube is connected to one end of the energy storage module, and the D pole of the buck upper MOS tube is connected to the positive pole of the photovoltaic module; the S pole of the buck lower MOS tube is grounded; the S pole of the boost upper MOS tube is connected to the D pole of the boost lower MOS tube, and the D pole of the boost lower MOS tube is connected to the other end of the energy storage module, the D pole of the boost upper MOS tube is connected to the power output end, and the S pole of the boost lower MOS tube is grounded; the G poles of the buck upper MOS tube, the buck lower MOS tube, the boost upper MOS tube and the boost lower MOS tube are all connected to the DPWM modulation unit through a switching resistor and a diode connected in parallel.

3. The method for power optimization control according to claim 1, characterized in that: The fast shutdown unit includes at least one MOS tube, the gate of the MOS tube of the fast shutdown unit is connected to the GPIO interface of the control unit, the drain is connected to the DPWM modulation unit through a voltage divider resistor, and the source of the MOS tube of the fast shutdown unit is grounded.

4. The method for power optimization control according to claim 3, characterized in that: The fast shutdown unit includes a first MOS tube and a second MOS tube, the gate of the first MOS tube is connected to the GPIO interface of the control unit, the drain of the first MOS tube is connected to the power supply unit through a first pull-up resistor, and the source is grounded; the power supply unit is connected to the DPWM modulation unit through a first voltage-dividing resistor; the drain of the first MOS tube is connected to the gate of the second MOS tube through a second pull-up resistor, the drain of the second MOS tube is connected to the DPWM modulation unit through one end of the first voltage-dividing resistor, and the source of the second MOS tube is grounded.

5. The method for power optimization control according to claim 1, characterized in that: The control unit controls the duty cycle of the DPWM modulation unit by turning on and off the fast shut-off unit according to feedback from a communication unit arranged at the power output side of the power conversion unit.

6. The method for power optimization control according to claim 5, characterized in that: The feedback from the communication unit includes absence of a heartbeat signal and / or a shutdown instruction.

7. A photovoltaic power optimizer with monitoring function, applied to power optimization of photovoltaic modules, characterized in that: It includes an ADC input monitoring unit, an ADC output monitoring unit, a power conversion unit, a DPWM modulation unit, a control unit, and a communication unit; the power conversion unit obtains the input power of the photovoltaic component according to the maximum power point tracking algorithm, and converts the input power obtained from the photovoltaic component into the output power of the power conversion unit; the ADC input monitoring unit is arranged at the input end of the power conversion unit, and monitors the input current and input voltage of the power conversion unit in real time; the ADC output monitoring unit is arranged at the output end of the power conversion unit, and monitors the output voltage and output current of the power conversion unit in real time; the DPWM modulation unit is connected to the power conversion unit, and the DPWM modulation unit is used to adjust the output voltage and output current of the power conversion unit; the control unit is connected to the DPWM modulation unit, and the control unit controls the duty cycle of the DPWM modulation unit through a fast shutdown unit; The power conversion unit includes a buck module, a boost module and an energy storage module; the buck module is connected to the boost module through the energy storage module; the buck module and the boost module each include at least one MOS tube; the G pole of the MOS tube is connected to the DPWM modulation module through a switching resistor and a diode connected in parallel, the S pole is grounded, and the D pole is connected to a capacitor; The ADC input monitoring unit includes an input voltage monitoring unit and an input current monitoring unit; the input current monitoring unit is arranged on the negative pole line of the photovoltaic module.

8. The photovoltaic power optimizer with monitoring function according to claim 7, characterized in that: The communication unit includes a carrier processor, an isolation transformer and an inductor. The carrier processor is connected to the control unit, both ends of the inductor are connected to the isolation transformer, and interfaces No. 3 and No. 4 of the isolation transformer are connected to the carrier processor.

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