A quasi-resonant control method, device and medium for photovoltaic micro-inverter

Abstract

The present application discloses a quasi-resonant control method, device and medium for a photovoltaic micro-inverter; it relates to the field of inverters, solves the problem of adding an additional soft switch point detection circuit to achieve quasi-resonant control, optimizes the on-time and switching frequency by dynamically adjusting the number of resonant cycles, and achieves quasi-resonant control under different working conditions, which not only reduces the dependence on hardware detection circuits, but also improves the flexibility and response speed of the system through software control. The additional voltage detection circuit is eliminated, reducing hardware costs. The operating efficiency of the inverter is improved by accurately controlling the on-time and switching frequency. The soft switching technology reduces the electromagnetic interference generated by the switching operation and improves the electromagnetic compatibility of the system. The number of resonant cycles is dynamically adjusted to ensure that the system can operate stably under various working conditions. By adjusting the on-time and switching frequency, the power output can be more accurately controlled to meet different power requirements.

Description

Technical Field

[0001] The present application relates to the field of inverters, and in particular to a quasi-resonant control method, device and medium for a photovoltaic micro-inverter. Background Art

[0002] As a new type of photovoltaic grid-connected device, the flyback photovoltaic micro-inverter has broad development prospects. The flyback photovoltaic micro-inverter mainly includes three parts: the flyback circuit, the industrial frequency H-bridge inverter circuit and the drive circuit. Quasi-resonant (QR) operation is often used in flyback switching power supplies. Generally, the power supply working mode is detected by the voltage detection circuit or the power management chip through the demagnetization circuit, and then the signal event is detected to turn on the switch tube under the minimum drain-source voltage waveform to ensure that the turn-on loss and electromagnetic interference (EMI) noise are reduced.

[0003] Figure 1 A schematic diagram of the basic structure of a flyback photovoltaic micro inverter is shown in FIG. Figure 1 As shown, by adding a demagnetization detection circuit, the switch tubes (such as Figure 1 The drain-source voltage of Q1-A and Q1-B is detected. When the drain-source voltage resonates to the valley after the switch tube is turned off, the signal is sent to the programmable logic device (Field Programmable Gate Array, FPGA). The FPGA outputs a control signal to the switch tube, turns on the switch tube, and makes the flyback transformer work in the quasi-resonance mode; the switch tube conduction time is iteratively calculated inside the FPGA, so that the output power is proportional to the square of the sine wave, and the output current waveform is close to the half-cycle sine wave, which controls the switch tube to turn off and completes the energy transfer process of the flyback transformer; the switch time of the switch tube in each cycle is adjusted in real time to achieve variable frequency control. However, this solution requires the addition of an additional demagnetization detection circuit, which increases the production cost.

[0004] It can be seen that how to solve the problem of adding an additional demagnetization detection circuit to achieve quasi-resonance control is a technical problem that needs to be solved urgently by people in this field. Summary of the invention

[0005] The purpose of the present application is to provide a quasi-resonant control method, device and medium for a photovoltaic micro-inverter, so as to solve the problem of needing to add an additional soft switching point detection circuit to achieve quasi-resonant control.

[0006] In order to solve the above technical problems, the present application provides a quasi-resonant control method of a photovoltaic micro-inverter, comprising:

[0007] Obtain the photovoltaic side voltage, grid side voltage and transformer primary inductance;

[0008] Determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0009] Determining whether the on-time satisfies a preset on-time threshold;

[0010] If the preset on-time threshold is not met, adjusting the resonance period until the on-time meets the preset on-time threshold;

[0011] If the preset on-time threshold is met, obtaining the switching frequency according to the on-time and determining whether the switching frequency meets the preset frequency threshold;

[0012] If the preset frequency threshold is not met, adjusting the resonance period until the switching frequency meets the preset frequency threshold;

[0013] Determine an updated on-time according to the adjusted resonance period;

[0014] The switching frequency and the duty cycle are determined according to the updated on-time to perform soft switching control in a quasi-resonant state.

[0015] As an optional solution, in the quasi-resonant control method of the photovoltaic micro-inverter, the adjusting the resonance period until the on-time meets the preset on-time threshold includes:

[0016] When the on-time exceeds the preset on-time upper limit, the set output power is kept unchanged and the resonance period is reduced until the on-time is less than the preset on-time upper limit;

[0017] When the on-time is lower than the preset on-time lower limit, the set output power is kept unchanged, and the resonance period is increased until the on-time is higher than the preset on-time lower limit.

[0018] As an optional solution, in the quasi-resonant control method of the photovoltaic micro-inverter, adjusting the resonance period until the switching frequency meets the preset frequency threshold includes:

[0019] If the switching frequency is greater than the preset maximum switching frequency, the resonance period is increased, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold;

[0020] If the switching frequency is less than the preset minimum switching frequency, the resonance period is reduced, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold;

[0021] If the switching frequency is greater than the preset minimum switching frequency and less than the preset maximum switching frequency, the step of determining the switching frequency and the duty cycle according to the updated on-time to perform soft switching control in a quasi-resonant state is entered.

[0022] As an optional solution, in the quasi-resonant control method of the photovoltaic micro-inverter, before judging whether the on-time satisfies the preset on-time threshold, the method further includes:

[0023] Determine whether the set output power is greater than the preset power value;

[0024] If it is greater than the preset power value, both flyback circuits are controlled to be turned on, and the double-on power coefficient of the flyback circuit is adjusted;

[0025] The single-channel output power is obtained according to the product of the set output power and the double-open power coefficient of the flyback circuit;

[0026] If it is not greater than the preset power value, the set output power is used as the single-channel output power of the main flyback circuit.

[0027] As an optional solution, in the above quasi-resonant control method of the photovoltaic micro-inverter, before increasing the resonance period, the method further includes:

[0028] Determine whether the current resonance period is less than a preset maximum resonance period;

[0029] If so, increasing the resonance period;

[0030] Correspondingly, before reducing the resonance period, it also includes:

[0031] Determine whether the current resonance period is greater than zero;

[0032] If so, the resonance period is reduced.

[0033] As an optional solution, in the above quasi-resonant control method of the photovoltaic micro-inverter, if the resonance period is not greater than zero, it also includes:

[0034] According to the maximum on-time at the peak of the grid voltage, the maximum output power when only the main flyback circuit is turned on is determined;

[0035] Determine the maximum power of the single-channel flyback circuit according to the grid voltage phase angle at the grid voltage peak moment;

[0036] When the set output power is less than the maximum power of the single-channel flyback circuit, only the main flyback circuit is turned on;

[0037] When the set output power is greater than the maximum power of the single-channel flyback circuit, the main flyback circuit is turned on, and the auxiliary flyback circuit turn-on time is determined according to the grid voltage phase angle;

[0038] Return to the step of determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer.

[0039] As an optional solution, in the above-mentioned quasi-resonant control method of the photovoltaic micro-inverter, when the resonance period is not less than the preset maximum value of the resonance period, it also includes:

[0040] Determine whether both flyback circuits are currently turned on;

[0041] If so, only the main flyback circuit is turned on, and the flyback circuit double-on power coefficient is adjusted;

[0042] If not, the loop ends.

[0043] In order to solve the above technical problems, the present application also provides a quasi-resonant control device for a photovoltaic micro-inverter, comprising:

[0044] An acquisition module is used to obtain the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0045] A determination module, used to determine the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0046] A conduction time judgment module, used to judge whether the conduction time meets a preset conduction time threshold; if it does not meet the preset conduction time threshold, the first adjustment module is triggered; if it meets the preset conduction time threshold, the switching frequency judgment module is triggered;

[0047] The first adjustment module is used to adjust the resonance period until the on-time meets a preset on-time threshold;

[0048] The switching frequency determination module is used to obtain the switching frequency according to the conduction time and determine whether the switching frequency meets a preset frequency threshold; if the preset frequency threshold is not met, the second adjustment module is triggered;

[0049] The second adjustment module is used to adjust the resonance period until the switching frequency meets a preset frequency threshold;

[0050] An updating module, used for determining an updated on-time according to the adjusted resonance period;

[0051] The soft switch control module is used to determine the switching frequency and the duty cycle according to the updated on-time to perform soft switch control in a quasi-resonant state.

[0052] In order to solve the above technical problems, the present application also provides a quasi-resonant control device for a photovoltaic micro-inverter, comprising:

[0053] Memory for storing computer programs;

[0054] A processor is used to implement the steps of the above-mentioned quasi-resonant control method of the photovoltaic micro-inverter when executing the computer program.

[0055] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned quasi-resonant control method of the photovoltaic micro-inverter are implemented.

[0056] The quasi-resonant control method of the photovoltaic micro inverter provided in the present application includes: obtaining the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; judging whether the conduction time meets the preset conduction time threshold; if the preset conduction time threshold is not met, adjusting the resonance period until the conduction time meets the preset conduction time threshold; if the preset conduction time threshold is met, obtaining the switching frequency according to the conduction time and judging whether the switching frequency meets the preset frequency threshold; if the preset frequency threshold is not met, adjusting the resonance period until the switching frequency meets the preset frequency threshold; determining the updated conduction time according to the adjusted resonance period; determining the switching frequency and duty cycle according to the updated conduction time to perform soft switching control in the quasi-resonant state. This scheme optimizes the conduction time and switching frequency by dynamically adjusting the number of resonance cycles, and realizes quasi-resonant control under different working conditions. This method not only reduces the dependence on the hardware detection circuit, but also improves the flexibility and response speed of the system through software control. The additional voltage detection circuit is eliminated, reducing the hardware cost. The operation efficiency of the inverter is improved by accurately controlling the conduction time and switching frequency. Soft switching technology reduces the electromagnetic interference generated by switching operations and improves the electromagnetic compatibility of the system. Dynamically adjust the number of resonant cycles to ensure that the system can operate stably under various working conditions. By adjusting the on-time and switching frequency, the power output can be controlled more accurately to meet different power requirements.

[0057] In addition, the present application also provides a device and a medium, which correspond to the quasi-resonant control method of the above-mentioned photovoltaic micro-inverter and have the same effect as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 any creative work.

[0059] Figure 1 A schematic diagram of the basic structure of a flyback photovoltaic microinverter;

[0060] Figure 2 A flow chart of a quasi-resonant control method of a photovoltaic micro-inverter is provided for an embodiment of the present application;

[0061] Figure 3 A specific control flow chart of a quasi-resonant control method for a photovoltaic micro-inverter provided in an embodiment of the present application;

[0062] Figure 4 A structural diagram of a quasi-resonant control device for a photovoltaic micro-inverter provided in an embodiment of the present application;

[0063] Figure 5 A structural diagram of another quasi-resonant control device for a photovoltaic micro-inverter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0065] The core of this application is to provide a quasi-resonant control method, device and medium for a photovoltaic micro-inverter.

[0066] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0067] Quasi-resonant (QR), in the most common flyback switching power supply, quasi-resonance means turning on the metal-oxide-semiconductor field-effect transistor (MOS tube) at the minimum drain-source voltage (Vds). That is, quasi-resonant operation or work. The general power management chip detects the power supply working mode through the demagnetization circuit, and then turns on the switch tube at the minimum drain-source voltage waveform by detecting the signal event to ensure the reduction of turn-on loss and electromagnetic interference noise. For the QR working mode, the switching cycle consists of three parts: the conduction time ( t on ), turn-off time( t off ) and half-resonance period ( t s ). Figure 1In the figure, the diode D1-A, the diode D2-A, the MOS tube Q1-A and the transformer D3-A form a main flyback circuit; the diode D1-B, the diode D2-B, the MOS tube Q1-B and the transformer D3-B form an auxiliary flyback circuit.

[0068] To solve the above problems, this embodiment provides a quasi-resonant control method for a photovoltaic micro-inverter, such as Figure 2 As shown, including:

[0069] S11: Obtaining the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0070] S12: determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0071] S13: Determine whether the on-time meets a preset on-time threshold;

[0072] S14: If the preset on-time threshold is not met, adjusting the resonance period until the on-time meets the preset on-time threshold;

[0073] S15: If the preset on-time threshold is met, the switching frequency is obtained according to the on-time and it is determined whether the switching frequency meets the preset frequency threshold;

[0074] S16: If the preset frequency threshold is not met, adjusting the resonance period until the switching frequency meets the preset frequency threshold;

[0075] S17: Determine and update the on-time according to the adjusted resonance period;

[0076] S18: Determine the switching frequency and duty cycle according to the updated on-time to perform soft switching control in the quasi-resonant state.

[0077] Obtaining the PV side voltage, grid side voltage and transformer primary inductance: These parameters are the basic inputs of the control method and are obtained in real time through the monitoring circuit. The PV side voltage and grid side voltage reflect the output of the PV cell assembly and the input conditions of the grid, respectively, while the transformer primary inductance is an inherent parameter of the system hardware.

[0078] The present invention adopts a discontinuous control mode and divides a switching cycle into a conduction phase, a fall phase and a resonance phase.

[0079] In the conduction phase, the flyback switch is turned on (one or both channels are turned on), and the duration of this phase is set as the conduction time. t on , the transformer primary current rises linearly from zero, then the peak current i pk It can be expressed as:

[0080] ;

[0081] In the formula, V pv The output voltage of the photovoltaic cell module, that is, the photovoltaic side voltage; L P is the primary inductance of the transformer.

[0082] According to the volt-second balance principle, the conduction time can be obtained t on Secondary current fall time t off The relationship is:

[0083] ;

[0084] In the formula, v out is the instantaneous value of the grid voltage, n is the ratio of the primary and secondary turns of the transformer.

[0085] The fall time t off The conduction time t on It is expressed as:

[0086] ;

[0087] In the formula, V out is the effective value of the grid voltage, that is, the grid side voltage; is the grid voltage phase angle.

[0088] After the secondary current drops to zero, it will enter the resonance stage, so the switch off time is the time taken for the secondary diode current to drop to zero. t off and resonance time t r Therefore, the entire switching cycle t s The total duration is:

[0089] ;

[0090] in, m is the number of quasi-resonant oscillation cycles, i.e. the resonant period, T q is the resonant half cycle time.

[0091] In a switching cycle t s The average value of the primary current i p,avg for:

[0092] ;

[0093] In each switching cycle, if the circuit power loss is ignored, the average photovoltaic input power in a single switching cycle is equal to the instantaneous output power on the grid side: , let the inverter operating power factor be 1, we can get:

[0094] ;

[0095] In the formula, p out To output active power, that is, to set the output power, the conduction time can be calculated using the above formula t on .

[0096] Specifically, step S11 includes: obtaining the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer, the grid voltage phase angle, the resonance half-cycle time, and setting the output power.

[0097] Determine the on-time based on the PV side voltage, grid side voltage and transformer primary inductance: The on-time is calculated by a formula based on the input voltage and system parameters. Specific means may include using the volt-second balance principle to ensure that the switch tube is turned on at the appropriate point of the voltage waveform to achieve soft switching.

[0098] Step S13 determines whether the on-time meets the preset on-time threshold: by comparing the calculated on-time with the preset safety or efficiency threshold, it is determined whether the system parameters need to be adjusted. This may involve setting the upper and lower limits of the on-time to ensure that the switch tube is not damaged due to overheating or premature conduction.

[0099] If the preset on-time threshold is not met, the resonant period is adjusted: by adjusting the number of resonant periods m , you can change the on-time and switching frequency. If the on-time is too long, you can reduce m To increase the switching frequency, otherwise increase m Until the on-time meets the preset on-time threshold, this is an iterative process. m Until the on-time reaches the optimal value, ensuring that the system meets the design requirements in terms of safety and efficiency.

[0100] If the preset on-time threshold is met, the switching frequency is obtained based on the on-time. Once the on-time is determined, the switching frequency can be calculated based on the total length of the switching cycle, which will directly affect the performance and efficiency of the inverter. To determine whether the switching frequency meets the preset frequency threshold, the switching frequency also needs to meet a specific threshold to ensure the stability and efficiency of the system. If the frequency does not meet the requirements, it also needs to be adjusted. m value.

[0101] According to the adjusted resonant period, the updated on-time is determined and adjusted. m After that, the on-time needs to be recalculated to adapt to the new m value to ensure the continuity and accuracy of the control method.

[0102] The switching frequency and duty cycle are determined according to the updated on-time to implement soft switching control in the quasi-resonant state, reduce switching losses and improve system efficiency.

[0103] The quasi-resonant control method of the photovoltaic micro-inverter provided by the present embodiment includes: obtaining the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; judging whether the conduction time meets the preset conduction time threshold; if the preset conduction time threshold is not met, adjusting the resonance period until the conduction time meets the preset conduction time threshold; if the preset conduction time threshold is met, obtaining the switching frequency according to the conduction time and judging whether the switching frequency meets the preset frequency threshold; if the preset frequency threshold is not met, adjusting the resonance period until the switching frequency meets the preset frequency threshold; determining the updated conduction time according to the adjusted resonance period; determining the switching frequency and duty cycle according to the updated conduction time to perform soft switching control in the quasi-resonant state. This scheme optimizes the conduction time and switching frequency by dynamically adjusting the number of resonance cycles, and realizes quasi-resonant control under different working conditions. This method not only reduces the dependence on the hardware detection circuit, but also improves the flexibility and response speed of the system through software control. The additional voltage detection circuit is eliminated, reducing the hardware cost. The operation efficiency of the inverter is improved by accurately controlling the conduction time and switching frequency. Soft switching technology reduces the electromagnetic interference generated by switching operations and improves the electromagnetic compatibility of the system. Dynamically adjust the number of resonant cycles to ensure that the system can operate stably under various working conditions. By adjusting the on-time and switching frequency, the power output can be controlled more accurately to meet different power requirements.

[0104] According to the above embodiment, in a specific implementation scheme, the quasi-resonant control method of the photovoltaic micro-inverter adjusts the resonance period until the on-time meets the preset on-time threshold, including:

[0105] When the on-time exceeds the preset on-time upper limit, the set output power is kept unchanged and the resonance period is reduced until the on-time is less than the preset on-time upper limit;

[0106] When the on-time is lower than the preset on-time lower limit, the set output power is kept unchanged, and the resonance period is increased until the on-time is higher than the preset on-time lower limit.

[0107] The preliminarily calculated on-time is compared with a preset on-time upper limit and a preset on-time lower limit.

[0108] When the on-time limit is exceeded, the resonant period needs to be reduced to reduce the on-time. Since the output power needs to remain constant, by reducing m , the switching frequency can be increased, thereby reducing the on-time in each switching cycle until the on-time is less than the preset on-time upper limit.

[0109] For regulation below the on-time lower limit, in order to increase the on-time, the resonant period needs to be increased. This will reduce the switching frequency and increase the on-time in each switching cycle until the on-time is higher than the preset on-time lower limit.

[0110] After adjusting the resonant period, continuously monitor the on-time to ensure it is stable within the preset threshold. If the on-time changes, adjust it again.

[0111] Once the on-time is adjusted to meet the threshold, the switching frequency and duty cycle are calculated according to the new on-time and switching period to achieve soft switching control in the quasi-resonant state.

[0112] According to the formula in the above embodiment, the power control target p out And other state variables, calculate the switching frequency and on-duty ratio. Resonance period m It will affect the switching frequency, on-time and duty cycle. The main considerations include whether the primary current peak will cause overcurrent, whether the minimum on-time meets the technical requirements of the switching tube, whether the switching frequency is within an appropriate range, etc.

[0113] The relationship between the on-time and the primary peak current is:

[0114] ;

[0115] therefore, t on The upper limit is determined by the primary current protection value:

[0116] ;

[0117] In the formula, is the maximum value of the primary peak current; the preset conduction time upper limit is determined according to the maximum value of the peak current, the photovoltaic side voltage, and the primary inductance of the transformer.

[0118] t on The lower limit of is limited by the minimum on-time of the switch tube, that is: ; The lower limit of the preset on-time can be set by yourself.

[0119] When calculated t on If it is too small and exceeds the lower limit, increase m value, the switching period can be increased (i.e., the switching frequency can be reduced) while keeping the output power unchanged, thereby increasing the on-time and preventing it from being lower than the minimum on-time of the switch tube.

[0120] When calculated t on When it is too large and exceeds the upper limit, m By adjusting the switching frequency, the switching period can be reduced (i.e., the switching frequency can be increased) while keeping the output power unchanged, thereby reducing the on-time and avoiding overcurrent on the primary side.

[0121] Specifically, the photovoltaic side voltage and grid side voltage are obtained by using a real-time monitoring system. A digital signal processor (DSP) or microcontroller (MCU) is used to perform the calculation and control logic of the on-time. The switching frequency and duty cycle are adjusted through a hardware PWM (pulse width modulation) module.

[0122] By adjusting the resonant period in real time, the system can respond quickly to voltage changes and maintain efficient operation. Keep the set output power unchanged and adjust the on-time to ensure that the inverter operates in the best state. By maintaining the on-time within the safety threshold, the potential damage caused by too long or too short on-time is reduced. By replacing some hardware functions with software control, the system reduces the dependence on complex hardware, reduces costs and improves flexibility. By accurately controlling the on-time, the inverter can be operated efficiently and stably under different working conditions, effectively reducing hardware costs and improving the overall performance of the system.

[0123] According to the above embodiment, in a specific implementation scheme, the quasi-resonant control method of the photovoltaic micro-inverter adjusts the resonance period until the switching frequency meets the preset frequency threshold, including:

[0124] If the switching frequency is greater than the preset maximum switching frequency, the resonance period is increased, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold;

[0125] If the switching frequency is less than the preset minimum switching frequency, the resonance period is reduced, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold;

[0126] If the switching frequency is greater than the preset minimum switching frequency and less than the preset maximum switching frequency, the step of determining the switching frequency and the duty cycle according to the updated on-time to perform soft switching control in the quasi-resonant state is entered.

[0127] According to the current resonant period and on-time, the current switching frequency is obtained. F s . Determine whether the switching frequency exceeds the maximum threshold: compare the calculated switching frequency with the preset maximum switching frequency F s,max If the switching frequency is greater than the preset maximum switching frequency, in order to reduce the switching frequency, by adjusting m After adjusting the resonance period, re-judge whether the on-time meets the preset on-time threshold. If the switching frequency is less than the preset minimum switching frequency, in order to increase the switching frequency, adjust m The resonant period is reduced by the value. It is re-determined whether the adjusted on-time meets the preset threshold and further adjustments are made as needed.

[0128] If the switching frequency is greater than the preset minimum switching frequency and less than the preset maximum switching frequency, it is considered that the switching frequency has met the requirements. Enter the soft switching control step, recalculate and determine the switching frequency and duty cycle according to the current on time, and enter the soft switching control stage under the quasi-resonant state.

[0129] This embodiment reduces switching losses and improves overall efficiency by ensuring that the switching frequency is within the optimal range. Appropriate switching frequency avoids unstable operation of the system at too high or too low frequency. Dynamic adjustment of the resonant period provides a flexible control strategy to adapt to different operating conditions. It avoids hardware damage caused by excessive frequency and extends the life of the equipment. By providing stable and efficient inverter operation, it enhances user satisfaction with system performance.

[0130] According to the above embodiment, in a specific implementation scheme, the quasi-resonant control method of the photovoltaic micro-inverter, before determining whether the on-time meets the preset on-time threshold, further includes:

[0131] Determine whether the set output power is greater than the preset power value;

[0132] If it is greater than the preset power value, both flyback circuits are controlled to be turned on, and the double-on power coefficient of the flyback circuit is adjusted;

[0133] The single-channel output power is obtained by multiplying the set output power by the double-open power coefficient of the flyback circuit;

[0134] If it is not greater than the preset power value, the set output power will be used as the single-channel output power of the main flyback circuit.

[0135] Set the output power p out The power is compared with a preset power threshold (set according to actual needs, such as 200W). When the power is greater than the preset power value, both flyback circuits are controlled to be turned on to achieve more efficient power conversion capability.

[0136] When the power value is not greater than the preset power value, there is no need to start the two flyback circuits, and the set output power is directly used as the single-channel output power to control the main flyback circuit.

[0137] After the single-channel output power is determined, the control process continues to be executed, including calculating the on-time, determining whether a preset on-time threshold is met, and adjusting the resonance period accordingly.

[0138] By controlling the opening of the two flyback circuits, the system can handle higher output power requirements. Flexible adjustment of single or dual output according to actual power requirements improves the efficiency and adaptability of system operation. By dynamically adjusting the flyback circuit dual opening power factor, the system can better adapt to different power requirements and grid conditions. Under high power demand, the opening of the dual flyback circuit helps maintain system stability and output quality. When full power output is not required, avoid unnecessary opening of the dual circuits to reduce pressure on hardware and potential losses.

[0139] According to the above embodiment, in a specific implementation scheme, the above quasi-resonant control method of the photovoltaic micro-inverter, before increasing the resonance period, further includes:

[0140] Determine whether the current resonance period is less than the preset maximum resonance period;

[0141] If so, increase the resonance period;

[0142] Correspondingly, before reducing the resonance period, it also includes:

[0143] Determine whether the current resonance period is greater than zero;

[0144] If so, reduce the resonant period.

[0145] Before planning to increase the resonance period, determine whether the current resonance period is less than the preset maximum resonance period. m maxWhen the resonant period is less than the maximum value, the resonant period is increased in the hope of increasing the on-time or reducing the switching frequency. Before planning to reduce the resonant period, it is determined whether the current resonant period is greater than zero. When the resonant period is greater than zero, the resonant period is reduced in the hope of reducing the on-time or increasing the switching frequency.

[0146] Based on the determined and adjusted resonant period, the on-time and switching frequency are recalculated to ensure that the preset threshold is met. Using the updated resonant period, the control process is continued, including determining whether the on-time meets the preset threshold and making necessary adjustments.

[0147] By making a pre-judgment, the resonant period is prevented from exceeding its physical or design limit, thus ensuring the safe operation of the system. By precisely controlling the resonant period, unnecessary energy loss is reduced and the efficiency of the inverter is improved. Keeping the resonant period within a reasonable range helps maintain the stability of the system and the quality of the output power.

[0148] If in m =0, the on-time still exceeds the upper limit, then the auxiliary flyback circuit needs to be enabled and the output power needs to be adjusted accordingly. Theoretically, the single-channel output power will be halved, while considering the increase in loss to ensure that the on-time is within a safe range. According to the above embodiment, in a specific implementation scheme, the quasi-resonant control method of the above photovoltaic micro-inverter, if the resonant period is not greater than zero, further includes:

[0149] According to the maximum on-time at the peak of the grid voltage, the maximum output power when only the main flyback circuit is turned on is determined;

[0150] Determine the maximum power of the single-channel flyback circuit according to the grid voltage phase angle at the grid voltage peak moment;

[0151] When the set output power is less than the maximum power of the single-channel flyback circuit, only the main flyback circuit is turned on;

[0152] When the set output power is greater than the maximum power of the single-channel flyback circuit, the main flyback circuit is turned on, and the auxiliary flyback circuit turn-on time is determined according to the grid voltage phase angle;

[0153] Return to the step of determining the on-time according to the PV side voltage, the grid side voltage and the primary inductance of the transformer.

[0154] when m When it is 0, the maximum output power when only the main flyback circuit is turned on can be calculated based on the maximum on-time at the peak of the grid voltage:

[0155] ;

[0156] Therefore, when setting the output power p outLess than the maximum power of a single-channel flyback circuit When p out Greater than When the main flyback circuit is turned on, the auxiliary flyback circuit opening time needs to be calculated according to the angle to turn on the auxiliary flyback circuit, so that the single-channel instantaneous power is always lower than According to the above formula, the maximum rated output power of the interleaved flyback circuit can also be obtained as .

[0157] According to the above embodiment, in a specific implementation scheme, the quasi-resonance control method of the photovoltaic micro-inverter, when the resonance period is not less than the preset maximum value of the resonance period, further includes:

[0158] Determine whether both flyback circuits are currently turned on;

[0159] If so, only the main flyback circuit is turned on, and the flyback circuit double-on power coefficient is adjusted;

[0160] If not, the loop ends.

[0161] When the resonant period reaches the preset maximum value during the adjustment process, an additional judgment process is performed. First, determine whether both flyback circuits are turned on, check the current working status, and confirm whether both flyback circuits (main flyback circuit and auxiliary flyback circuit) are in the on state. If both flyback circuits are turned on, in order to reduce the overall switching frequency, only the main flyback circuit is left on and the auxiliary flyback circuit is turned off.

[0162] According to the current working status of the main and auxiliary flyback circuits, the single-channel output power is calculated. P ref .

[0163] According to the adjusted circuit working state and the new flyback circuit dual-on power coefficient, the on-time and switching frequency are recalculated. If only the main flyback circuit is turned on at present, it means that the maximum power output limit of the system design has been reached. At this time, the cycle ends and the resonant period is no longer adjusted.

[0164] After the final circuit operating state and parameters are determined, the current adjustment cycle ends and the system is maintained running in the current state.

[0165] When the maximum value of the resonance period is reached, the circuit working state is adjusted in time to avoid system instability caused by excessive frequency. By flexibly controlling the opening and closing of the two flyback circuits, the system's adaptability to different working conditions is improved.

[0166] To better understand this program, Figure 3A specific control flow chart of a quasi-resonant control method for a photovoltaic micro-inverter provided in an embodiment of the present application is as follows: Figure 3 Check whether the real-time power is greater than the maximum operating power of a single channel. If so, both the main and auxiliary flyback circuits need to be turned on at the same time to calculate the output power of a single channel. m value so that the on-time meets the preset range, and further by adjusting m The value is the switching frequency while meeting the preset range.

[0167] In the above embodiments, the quasi-resonant control method of the photovoltaic micro-inverter is described in detail, and the present application also provides an embodiment corresponding to the quasi-resonant control device of the photovoltaic micro-inverter. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is based on the perspective of the functional module, and the other is based on the perspective of the hardware.

[0168] From the perspective of functional modules, Figure 4 A structural diagram of a quasi-resonant control device for a photovoltaic micro-inverter provided in an embodiment of the present application, such as Figure 4 As shown, a quasi-resonant control device for a photovoltaic micro-inverter comprises:

[0169] An acquisition module 21 is used to acquire the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0170] A determination module 22, configured to determine the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer;

[0171] The on-time judging module 23 is used to judge whether the on-time satisfies a preset on-time threshold; if it does not satisfy the preset on-time threshold, the first regulating module is triggered; if it satisfies the preset on-time threshold, the switching frequency judging module is triggered;

[0172] A first adjustment module 24, used for adjusting the resonance period until the on-time satisfies a preset on-time threshold;

[0173] The switching frequency determination module 25 is used to obtain the switching frequency according to the conduction time and determine whether the switching frequency meets a preset frequency threshold; if the preset frequency threshold is not met, the second regulation module is triggered;

[0174] A second adjustment module 26, used for adjusting the resonance period until the switching frequency meets a preset frequency threshold;

[0175] An updating module 27, used to determine an updated on-time according to the adjusted resonance period;

[0176] The soft switch control module 28 is used to determine the switching frequency and the duty cycle according to the updated on-time to perform soft switch control in the quasi-resonance state.

[0177] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0178] Figure 5 A structural diagram of another quasi-resonant control device for a photovoltaic micro-inverter provided in an embodiment of the present application, such as Figure 5 As shown, the quasi-resonant control device of the photovoltaic micro-inverter includes: a memory 30 for storing a computer program;

[0179] The processor 31 is used to implement the steps of the method for obtaining user operation habit information in the above embodiment (quasi-resonant control method for photovoltaic micro-inverter) when executing the computer program.

[0180] The quasi-resonant control device of the photovoltaic micro-inverter provided in this embodiment may include but is not limited to a smart phone, a tablet computer, a laptop computer or a desktop computer.

[0181] Among them, the processor 31 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 31 may be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 31 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 31 may be integrated with a graphics processing unit (GPU), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 31 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0182] The memory 30 may include one or more computer-readable storage media, which may be non-transitory. The memory 30 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 30 is at least used to store the following computer program 301, wherein, after the computer program is loaded and executed by the processor 31, it can implement the relevant steps of the quasi-resonant control method of the photovoltaic micro-inverter disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 30 may also include an operating system 302 and data 303, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 302 may include Windows, Unix, Linux, etc. Data 303 may include but is not limited to data involved in implementing the quasi-resonant control method of the photovoltaic micro-inverter, etc.

[0183] In some embodiments, the quasi-resonant control device for a photovoltaic micro-inverter may further include a display screen 32 , an input / output interface 33 , a communication interface 34 , a power supply 35 , and a communication bus 36 .

[0184] Those skilled in the art will understand that Figure 5 The structure shown in the figure does not constitute a limitation on the quasi-resonant control device of the photovoltaic micro-inverter, and may include more or less components than those shown in the figure.

[0185] The quasi-resonant control device of a photovoltaic micro-inverter provided in an embodiment of the present application includes a memory and a processor. When the processor executes a program stored in the memory, it can implement the following method: a quasi-resonant control method of a photovoltaic micro-inverter.

[0186] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is executed by the processor, the steps recorded in the above-mentioned quasi-resonance control method embodiment of the photovoltaic micro-inverter (which may be a method corresponding to the server side, or a method corresponding to the diagnostic device side, or a method corresponding to both the server side and the diagnostic device side) are implemented.

[0187] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0188] The computer-readable storage medium provided in this embodiment stores a computer program, and when a processor executes the program, the following method can be implemented: a quasi-resonant control method for a photovoltaic micro-inverter.

[0189] The quasi-resonant control method, device and medium of the photovoltaic micro-inverter provided by the present application are introduced in detail above. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can refer to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0190] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A quasi-resonant control method for a photovoltaic micro-inverter, characterized in that: Applied to interleaved parallel flyback photovoltaic micro inverters, including: Obtain the photovoltaic side voltage, grid side voltage and transformer primary inductance; Determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; Determining whether the on-time satisfies a preset on-time threshold; If the preset on-time threshold is not met, adjusting the resonance period until the on-time meets the preset on-time threshold; If the preset on-time threshold is met, obtaining the switching frequency according to the on-time and determining whether the switching frequency meets the preset frequency threshold; If the preset frequency threshold is not met, adjusting the resonance period until the switching frequency meets the preset frequency threshold; Determine an updated on-time according to the adjusted resonance period; The switching frequency and the duty cycle are determined according to the updated on-time, and a corresponding control signal is generated to perform control in a quasi-resonant state.

2. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 1, characterized in that: The adjusting the resonance period until the on-time satisfies a preset on-time threshold comprises: When the on-time exceeds the preset on-time upper limit, the set output power is kept unchanged and the resonance period is reduced until the on-time is less than the preset on-time upper limit; When the on-time is lower than the preset on-time lower limit, the set output power is kept unchanged, and the resonance period is increased until the on-time is higher than the preset on-time lower limit.

3. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 2, characterized in that: The adjusting the resonance period until the switching frequency meets a preset frequency threshold comprises: If the switching frequency is greater than the preset maximum switching frequency, the resonance period is increased, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold; If the switching frequency is less than the preset minimum switching frequency, the resonance period is reduced, and the process returns to the step of determining whether the on-time satisfies the preset on-time threshold; If the switching frequency is greater than the preset minimum switching frequency and less than the preset maximum switching frequency, the step of determining the switching frequency and the duty cycle according to the updated on-time to perform soft switching control in a quasi-resonant state is entered.

4. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 3, characterized in that: Before determining whether the on-time satisfies a preset on-time threshold, the method further includes: Determine whether the set output power is greater than the preset power value; If it is greater than the preset power value, both flyback circuits are controlled to be turned on, and the double-on power coefficient of the flyback circuit is adjusted; The single-channel output power is obtained according to the product of the set output power and the double-open power coefficient of the flyback circuit; If it is not greater than the preset power value, the set output power is used as the single-channel output power of the main flyback circuit.

5. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 3, characterized in that: Before increasing the resonant period, it also includes: Determine whether the current resonance period is less than a preset maximum resonance period; If so, increasing the resonance period; Correspondingly, before reducing the resonance period, it also includes: Determine whether the current resonance period is greater than zero; If so, the resonance period is reduced.

6. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 5, characterized in that: If the resonance period is not greater than zero, the method further includes: According to the maximum on-time at the peak of the grid voltage, the maximum output power when only the main flyback circuit is turned on is determined; Determine the maximum power of the single-channel flyback circuit according to the grid voltage phase angle at the grid voltage peak moment; When the set output power is less than the maximum power of the single-channel flyback circuit, only the main flyback circuit is turned on; When the set output power is greater than the maximum power of the single-channel flyback circuit, the main flyback circuit is turned on, and the auxiliary flyback circuit turn-on time is determined according to the grid voltage phase angle; Return to the step of determining the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer.

7. The quasi-resonant control method of a photovoltaic micro-inverter according to claim 5, characterized in that: When the resonance period is not less than the preset maximum value of the resonance period, the method further includes: Determine whether both flyback circuits are currently turned on; If so, only the main flyback circuit is turned on, and the flyback circuit double-on power coefficient is adjusted; If not, the loop ends.

8. A quasi-resonant control device for a photovoltaic micro-inverter, characterized in that: Applied to interleaved parallel flyback photovoltaic micro inverters, including: An acquisition module is used to obtain the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; A determination module, used to determine the conduction time according to the photovoltaic side voltage, the grid side voltage and the primary inductance of the transformer; A conduction time judgment module, used to judge whether the conduction time meets a preset conduction time threshold; if it does not meet the preset conduction time threshold, the first adjustment module is triggered; if it meets the preset conduction time threshold, the switching frequency judgment module is triggered; The first adjustment module is used to adjust the resonance period until the on-time meets a preset on-time threshold; The switching frequency determination module is used to obtain the switching frequency according to the conduction time and determine whether the switching frequency meets a preset frequency threshold; if the preset frequency threshold is not met, the second adjustment module is triggered; The second adjustment module is used to adjust the resonance period until the switching frequency meets a preset frequency threshold; An updating module, used for determining an updated on-time according to the adjusted resonance period; The soft switch control module is used to determine the switching frequency and the duty cycle according to the updated on-time to perform soft switch control in a quasi-resonant state.

9. A quasi-resonant control device for a photovoltaic micro-inverter, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the quasi-resonant control method for a photovoltaic micro-inverter as claimed in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the quasi-resonant control method of the photovoltaic micro-inverter according to any one of claims 1 to 7 are implemented.

Images