CN-121984324-A - Single-stage photovoltaic boosting and multi-mode cooperative control method

CN121984324ACN 121984324 ACN121984324 ACN 121984324ACN-121984324-A

Abstract

The application relates to the technical field of power electronics, in particular to a single-stage photovoltaic boosting and multi-mode cooperative control method. The method comprises the steps of executing a time sequence adjustment process in a current switching period, wherein the time sequence adjustment process comprises the steps of determining dead time of a resonant converter based on a current working mode of a photovoltaic system, wherein the current working mode is any one mode of a photovoltaic power supply mode, an energy storage power supply mode, a dual-source cooperative power supply control mode or a grid-connected mode, monitoring actual zero crossing time of primary side resonant current in the dead time, judging whether the actual zero crossing time is located in a zero voltage switching time window, if not, calculating a driving phase adjustment amount according to time deviation between the actual zero crossing time and a central point of the zero voltage switching time window, and adjusting driving time of a switching tube of the resonant converter in the next switching period based on the driving phase adjustment amount. The application improves the stability and efficiency of the photovoltaic system under various working conditions.

Inventors

HUANG XIAOLONG
XIE SHENHENG
QIN XIAODONG

Assignees

安徽大恒新能源技术有限公司

Dates

Publication Date: 20260505
Application Date: 20260409

Claims (10)

1. A single-stage photovoltaic boosting and multi-mode cooperative control method, characterized in that the method comprises: and executing a time sequence adjustment process in the current switching period, wherein the time sequence adjustment process comprises the following steps: Determining dead time of a resonant converter based on a current working mode of a photovoltaic system, wherein the current working mode is any one mode of a photovoltaic power supply mode, an energy storage power supply mode, a double-source cooperative power supply control mode or a grid-connected mode; Monitoring the actual zero crossing time of the primary side resonance current in the dead time, and judging whether the actual zero crossing time is positioned in a zero voltage switching time window; If not, calculating a driving phase adjustment amount according to the time deviation between the actual zero crossing moment and the central point of the zero voltage switching time window; And adjusting the driving time sequence of the resonant converter switching tube pair in the next switching period based on the driving phase adjustment quantity.
2. The method according to claim 1, characterized in that the monitoring of the actual zero crossing instant of the primary resonance current during the dead time comprises in particular: filtering the primary side resonance current through a current filter to obtain a primary side filtering current; and monitoring the actual zero crossing moment of the primary side filtering current in the dead time.
3. The method of claim 1, wherein in the same switching period, defining a first switching tube and a second switching tube of the resonant converter switching tube pair, wherein the first switching tube is turned on, and the second switching tube is turned on, and the determining whether the actual zero crossing time is within a zero voltage switching time window specifically comprises: Judging whether the following three conditions are met at the same time, if yes, judging that the actual zero crossing moment is positioned in a zero voltage switching time window: wherein the three conditions include: (1) The actual zero crossing time falls within the range of the zero voltage switching time window in time; (2) Detecting that the primary side resonance current changes direction in the dead time, and (3) And the current direction of the primary side resonance current is consistent with the conduction direction of the body diode of the second switching tube.
4. The method of claim 1, wherein the method further comprises: And if the actual zero crossing time is positioned in the zero voltage switching time window, maintaining the current driving time sequence of the resonant converter switching tube pair in the current switching period unchanged.
5. The method according to claim 1, wherein said calculating the drive phase adjustment based on the time deviation between the actual zero crossing instant and the center point of the zero voltage switching time window, in particular comprises: determining a reference phase adjustment amount according to a proportional relationship between the time deviation between the actual zero crossing time and the central point of the zero voltage switching time window and the period duration of the current switching period; According to the current working mode, adjusting the reference phase adjustment quantity to obtain a mode phase adjustment quantity; and acquiring a phase safety boundary corresponding to the current working mode, and limiting the mode phase adjustment amount according to the phase safety boundary to obtain a driving phase adjustment amount.
6. The method of claim 5, wherein said adjusting said reference phase adjustment amount according to said current operating mode to obtain a mode phase adjustment amount, comprises: inquiring a preset mode compensation reference value according to the current working mode; dynamically compensating the mode compensation reference value according to the real-time load of the photovoltaic system to obtain a mode compensation coefficient; and multiplying the mode compensation coefficient by the reference phase adjustment amount to obtain a mode phase adjustment amount.
7. The method of claim 5, wherein the phase safety boundary comprises a phase safety lower limit and a phase safety upper limit, and wherein the limiting the mode phase adjustment amount according to the phase safety boundary to obtain the drive phase adjustment amount comprises: comparing the mode phase adjustment amount with the phase safety lower limit and the phase safety upper limit; If the mode phase adjustment amount is smaller than the phase safety lower limit, setting a driving phase adjustment amount as the phase safety lower limit; if the mode phase adjustment amount is greater than the phase safety upper limit, setting a driving phase adjustment amount to the phase safety upper limit; And if the mode phase adjustment amount is within the range of the phase safety boundary, the mode phase adjustment amount is taken as a driving phase adjustment amount.
8. The method of claim 1, wherein performing the trigger condition of the timing adjustment procedure at the current switching cycle comprises: And determining that the photovoltaic system is in a stable running state according to the monitored voltage fluctuation degree of the direct current bus and the load change rate of the photovoltaic system.
9. The method of claim 8, wherein the method further comprises: When the photovoltaic system is determined to be in an unstable operation state, monitoring voltage deviation between the actual voltage of the direct current bus and a target voltage; And when the voltage deviation exceeds a deviation threshold value, the duty ratio of the switching tube of the photovoltaic boosting circuit is adjusted to reduce the voltage deviation.
10. The method of claim 1, wherein after calculating the drive phase adjustment amount from the time offset between the actual zero crossing time and the center point of the zero voltage switch time window, the method further comprises: If the actual zero crossing time exceeds the zero voltage switching time window, according to the deviation direction of the actual zero crossing time and the zero voltage switching time window, the dead time of the resonant converter is adjusted according to a preset step length to obtain adjusted dead time; If the fact that the actual zero crossing time exceeds the zero voltage switching time window is detected based on the adjusted dead time, the switching frequency of the resonant converter is adjusted based on the current working mode; if the fact that the actual zero crossing moment exceeds the zero voltage switching time window is detected based on the adjusted switching frequency, the output power of the photovoltaic system is reduced according to a preset power attenuation rate, and the reduced output power is obtained; If the fact that the actual zero crossing time exceeds the zero voltage switching time window is detected based on the reduced output power, cutting off driving signals of the resonant converter switching tube pair and enabling the resonant converter switching tube pair to be kept in an off state until the photovoltaic system is restarted; The first preset times, the second preset times, the third preset times and the fourth preset times are all positive integers which are larger than 2.

Description

Single-stage photovoltaic boosting and multi-mode cooperative control method Technical Field The application relates to the technical field of power electronics and new energy, in particular to a single-stage photovoltaic boosting and multi-mode cooperative control method. Background Along with the rapid development of new energy power generation technology, a single-stage photovoltaic boosting system is widely applied due to the advantages of simple structure, high efficiency and the like. In a single-stage photovoltaic boost system, the LLC resonant converter is used as a core power conversion link, and the efficiency of the LLC resonant converter directly influences the performance of the whole system. To improve the efficiency of LLC resonant converters, it is important to implement zero voltage switching (Zero Voltage Switching, ZVS) that it can significantly reduce switching losses, reduce electromagnetic interference, and improve system reliability. In the related art, to achieve ZVS, a control strategy based on resonant current or switching node voltage monitoring is generally employed. For example, some schemes adjust the drive signal by detecting zero crossings of the switching node voltage, while others optimize the switching timing by monitoring specific characteristics of the resonant current. These methods can achieve better ZVS effects under laboratory conditions, but face a number of challenges in practical photovoltaic application scenarios. In an actual operation environment, the working state of the resonant converter can be changed continuously due to factors such as large fluctuation of the photovoltaic input voltage, frequent load change, obvious temperature change and the like and the diversity of working modes of a photovoltaic system. The existing control method is difficult to accurately judge whether the ZVS is really realized under various working conditions, so that the control strategy is not accurate enough. Particularly in the case where the system has satisfied ZVS conditions, the prior art lacks an effective judgment mechanism, cannot recognize the state of no adjustment, and thus may perform unnecessary drive timing modification. The inaccuracy of this control strategy results in frequent drive timing adjustments by the system, which not only increases system complexity, but may introduce additional timing jitter, instead destroying the established ZVS state. Therefore, how to accurately determine the ZVS implementation state under various working conditions becomes a key technical challenge to improve the efficiency and reliability of a single-stage photovoltaic boosting system. Disclosure of Invention Based on this, it is necessary to provide a single-stage photovoltaic boosting and multi-mode cooperative control method for accurately judging the ZVS implementation state according to the above technical problems. The application provides a single-stage photovoltaic boosting and multi-mode cooperative control method, which comprises the steps of executing a time sequence adjustment process in a current switching period, wherein the time sequence adjustment process comprises the following steps of: determining dead time of the resonant converter based on a current working mode of the photovoltaic system, wherein the current working mode is any one mode of a photovoltaic power supply mode, an energy storage power supply mode, a dual-source cooperative power supply control mode or a grid-connected mode; Monitoring the actual zero crossing time of the primary side resonance current in the dead time, and judging whether the actual zero crossing time is positioned in a zero voltage switching time window; If not, calculating a driving phase adjustment amount according to the time deviation between the actual zero crossing moment and the central point of the zero voltage switching time window; Based on the drive phase adjustment amount, the drive timing of the resonant converter switching transistor pair in the next switching cycle is adjusted. In one embodiment, monitoring the actual zero crossing time of the primary side resonant current in the dead time specifically includes: filtering the primary side resonance current through a current filter to obtain primary side filtering current; the actual zero crossing of the primary filtered current is monitored during the dead time. In one embodiment, in the same switching period, defining a first switching tube as a first switching tube and a second switching tube as a second switching tube in a switching tube pair of the resonant converter, and judging whether the actual zero crossing time is in a zero voltage switching time window or not, wherein the method specifically comprises the following steps: Judging whether the following three conditions are satisfied at the same time, if yes, judging that the actual zero crossing moment is positioned in a zero voltage switching time window: Wherein, three conditions include: (1) The actu