CN-120825059-B - Photovoltaic inverter and control circuit and control method thereof

CN120825059BCN 120825059 BCN120825059 BCN 120825059BCN-120825059-B

Abstract

The invention discloses a photovoltaic inverter and a control circuit and a control method thereof, belonging to the technical field of photovoltaic inverters, wherein the photovoltaic inverter comprises a first photovoltaic module, a first direct current contactor and a second photovoltaic module which are sequentially connected in series and then connected into a BUCK-BOOST circuit, and the output end of the first photovoltaic module is also connected into the BUCK-BOOST circuit through the second direct current contactor; the output end of the second photovoltaic module is commonly connected with the input end of the voltage sampling circuit and the input end of the BUCK-BOOST circuit, the output end of the direct current contactor control circuit is respectively connected with the first direct current contactor and the second direct current contactor, the DSP processor is respectively connected with the voltage sampling circuit, the direct current contactor control circuit and the BUCK-BOOST circuit, the output end of the BUCK-BOOST circuit is respectively connected with the load, the input end of the energy storage device and the input end of the inversion device, and the output end of the inversion device is connected with the grid-connected device. The invention provides a photovoltaic inverter control circuit and a photovoltaic inverter control method which are compact in structure and flexible to control, and solves the problem of unstable output voltage caused by illumination change.

Inventors

LIN XIAOYANG
HUANG MENG
HUANG SONGRU
CHEN NINGNING
NI ZIRONG

Assignees

珠海格力电器股份有限公司

Dates

Publication Date: 20260512
Application Date: 20250917

Claims (9)

1. A photovoltaic inverter control circuit, comprising: The photovoltaic power generation system comprises a first photovoltaic module, a second photovoltaic module, a first direct current contactor, a second direct current contactor, a direct current contactor control circuit, a voltage sampling circuit, a processor, a BUCK-BOOST circuit, a load, an energy storage device, an inversion device and a grid-connected device, wherein: The first photovoltaic module, the first direct current contactor and the second photovoltaic module are sequentially connected in series and then connected to the input end of the BUCK-BOOST circuit, and the output end of the first photovoltaic module is also connected to the input end of the BUCK-BOOST circuit through the second direct current contactor; The output end of the second photovoltaic module is respectively connected with the input end of the voltage sampling circuit and the input end of the BUCK-BOOST circuit; The output end of the direct current contactor control circuit is connected with the first direct current contactor and the second direct current contactor respectively; The processor is respectively connected with the output end of the voltage sampling circuit, the input end of the direct current contactor control circuit and the control end of the BUCK-BOOST circuit; the output end of the BUCK-BOOST circuit is also connected with at least one voltage conversion module; The processor is configured to perform: receiving the output voltage of the second photovoltaic module acquired by the voltage sampling circuit; When the output voltage of the second photovoltaic module is lower than the load demand voltage, judging that the illumination is insufficient, and controlling the first direct current contactor to be closed so that the first photovoltaic module and the second photovoltaic module are connected in series for power supply; When the output voltage of the second photovoltaic module is not lower than the load demand voltage, judging that the illumination is sufficient, controlling the first direct current contactor to be disconnected, and independently supplying power by the second photovoltaic module; when the illumination is sufficient but the output voltage of the second photovoltaic module drops abnormally, the second direct current contactor is controlled to be closed, and the first photovoltaic module directly supplies power; The output end of the BUCK-BOOST circuit is respectively connected with the load, the input end of the energy storage device and the input end of the inversion device; and the output end of the inversion device is connected with the grid-connected device.
2. The photovoltaic inverter control circuit of claim 1, wherein: the processor is further configured to execute an electrical energy allocation policy to allocate electrical energy output by the BUCK-BOOST circuit, including: preferentially controlling the electric energy output by the BUCK-BOOST circuit to supply power to the load; secondly, controlling the residual electric energy to charge the energy storage device; and after the energy storage device is full, controlling the redundant electric energy to feed into the power grid through the inversion device and the grid-connected device.
3. The photovoltaic inverter control circuit of claim 1, wherein: the output end of the BUCK-BOOST circuit is also connected with at least one voltage conversion module; The voltage conversion module comprises at least one of a 24V-to-15V module, a 15V-to-12V module, a 12V-to-5V module or a 5V-to-3.3V module.
4. A photovoltaic inverter control method applied to the photovoltaic inverter control circuit of any one of claims 1 to 3, characterized by comprising: Monitoring the output voltage of the second photovoltaic module in real time; comparing and analyzing the output voltage of the second photovoltaic module with the load demand voltage, generating a power supply mode decision signal according to a judgment result, controlling the on-off states of the first direct current contactor and the second direct current contactor based on the power supply mode decision signal, and dynamically switching the power supply modes of the first photovoltaic module and the second photovoltaic module; Monitoring the output voltage of the BUCK-BOOST circuit in real time, and dynamically adjusting the PWM duty ratio output to the BUCK-BOOST circuit by adopting a closed-loop control algorithm according to the difference value between the output voltage and the target voltage; and dispatching and distributing the electric energy output by the BUCK-BOOST circuit according to an electric energy distribution strategy.
5. The method for controlling a photovoltaic inverter according to claim 4, wherein: The power modes include a series boost power mode, an independent power mode, and a pass-through power mode, wherein: the series boost power mode is: When the output voltage of the second photovoltaic module is lower than the load demand voltage, judging that the illumination is insufficient, and controlling the first direct current contactor to be closed so that the first photovoltaic module and the second photovoltaic module are connected in series for power supply; The independent power supply mode is as follows: When the output voltage of the second photovoltaic module is not lower than the load demand voltage, judging that the illumination is sufficient, controlling the first direct current contactor to be disconnected, and independently supplying power by the second photovoltaic module; The through power supply mode is as follows: And when the illumination is sufficient but the output voltage of the second photovoltaic module drops abnormally, controlling the second direct current contactor to be closed, and directly supplying power by the first photovoltaic module.
6. The method for controlling a photovoltaic inverter according to claim 4, wherein: the closed-loop control algorithm is a PID control algorithm, comprising: Calculating a real-time error value of the output voltage of the BUCK-BOOST circuit and the target voltage; Calculating a PWM duty cycle adjustment value based on the real-time error value by combining a preset proportional coefficient, an integral coefficient and a differential coefficient; And generating a PWM control signal output to the BUCK-BOOST circuit based on the PWM duty cycle adjustment value.
7. A photovoltaic inverter comprising a photovoltaic inverter control circuit as claimed in any one of claims 1 to 3.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the computer program when loaded into the processor implements a photovoltaic inverter control method according to any of claims 4-6.
9. A computer readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements a photovoltaic inverter control method according to any one of claims 4-6.

Description

Photovoltaic inverter and control circuit and control method thereof Technical Field The invention belongs to the technical field of photovoltaic inverters, and particularly relates to a photovoltaic inverter, a control circuit and a control method thereof. Background Photovoltaic power generation has been widely used in recent years as an important form of clean energy, but its output characteristics are significantly affected by the intensity of light, and there are problems of high intermittence and fluctuation. Under different weather conditions, the output voltage of the photovoltaic module may change greatly, and if the photovoltaic module is directly connected to a later-stage circuit, the system may work unstably, and even the normal operation of the load is affected. Particularly, in the morning, evening or overcast and rainy days, the photovoltaic module is low in output voltage due to insufficient illumination, and is difficult to meet the voltage requirement of a load, and when the illumination is sufficient, the equipment is possibly impacted due to the fact that the voltage is too high. The traditional photovoltaic inverter generally adopts a single BUCK or BOOST circuit structure, is difficult to realize high-efficiency and stable output in a wide input voltage range, and lacks intelligent scheduling capability for multiple paths of energy sources, so that the energy source utilization rate is low and the system adaptability is poor. The BUCK-BOOST circuit is used as a switching power supply topology capable of achieving a BUCK-BOOST function, has wide voltage input adaptability theoretically, and can alleviate the voltage fluctuation problem in a certain range. However, the control complexity is high, the mode smooth switching and the output voltage stabilization are realized by matching with a precise algorithm, and the technical bottleneck still exists in the aspects of multi-module cooperative control and dynamic response. In addition, the existing photovoltaic system lacks a real-time judging mechanism for the illumination state and the load demand, cannot intelligently select an optimal power supply mode according to the actual working condition, and is difficult to realize reasonable grading utilization of electric energy, so that part of power generation resources are wasted. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a photovoltaic inverter, a control circuit and a control method thereof. The invention adopts the following technical scheme. A first aspect of the present invention provides a photovoltaic inverter control circuit comprising: The photovoltaic power generation system comprises a first photovoltaic module, a second photovoltaic module, a first direct current contactor, a second direct current contactor, a direct current contactor control circuit, a voltage sampling circuit, a processor, a BUCK-BOOST circuit, a load, an energy storage device, an inversion device and a grid-connected device, wherein: The first photovoltaic module, the first direct current contactor and the second photovoltaic module are sequentially connected in series and then connected to the input end of the BUCK-BOOST circuit, and the output end of the first photovoltaic module is also connected to the input end of the BUCK-BOOST circuit through the second direct current contactor; The output end of the second photovoltaic module is respectively connected with the input end of the voltage sampling circuit and the input end of the BUCK-BOOST circuit; The output end of the direct current contactor control circuit is connected with the first direct current contactor and the second direct current contactor respectively; The processor is respectively connected with the output end of the voltage sampling circuit, the input end of the direct current contactor control circuit and the control end of the BUCK-BOOST circuit; The output end of the BUCK-BOOST circuit is respectively connected with the load, the input end of the energy storage device and the input end of the inversion device; and the output end of the inversion device is connected with the grid-connected device. Optionally, the processor is configured to perform: receiving the output voltage of the second photovoltaic module acquired by the voltage sampling circuit; When the output voltage of the second photovoltaic module is lower than the load demand voltage, judging that the illumination is insufficient, and controlling the first direct current contactor to be closed so that the first photovoltaic module and the second photovoltaic module are connected in series for power supply; When the output voltage of the second photovoltaic module is not lower than the load demand voltage, judging that the illumination is sufficient, controlling the first direct current contactor to be disconnected, and independently supplying power by the second photovoltaic module; And when the illumination is sufficient