Heating system adopting photovoltaic direct drive and mains supply coupled double-source heating technology

Abstract

The invention relates to the technical field of heating systems, and particularly discloses a heating system adopting a photovoltaic direct drive and mains supply coupled double-source heating technology, comprising a photovoltaic direct drive module which is composed of a photovoltaic array and a high-frequency isolation type direct drive converter, the direct drive converter adopts a three-level ANPC topological structure, and a deep learning-based MPPT algorithm is built in the direct drive converter; the commercial power coupling module is used for connecting commercial power with photovoltaic direct drive output in parallel through a bidirectional coupler based on a magnetic integration technology; the intelligent energy management unit comprises a sensor group and a coupling controller, and the sensor group collects photovoltaic array output power, mains supply voltage, heating load requirements and environment temperature signals in real time; and the waste energy recovery module is connected with the photovoltaic direct drive module and the heating terminal in parallel, comprises an excess electric energy recovery unit and is composed of a DC-DC converter and a phase change heat storage device, photovoltaic power generation, mains supply complementation and energy recovery technologies are combined, and efficient and intelligent clean energy heating is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of heating systems, and specifically discloses a heating system that uses a dual-source heating technology that couples photovoltaic direct drive with mains electricity. Background Art

[0002] Traditional heating systems mainly rely on gas or mains electricity, which has problems such as high carbon emissions, low energy utilization, and high operating costs. Although photovoltaic direct drive technology is gradually being applied in the heating field, it still faces the following technical bottlenecks:

[0003] Photovoltaic power generation is subject to significant volatility: Photovoltaic power generation is greatly affected by the weather. The conversion efficiency on sunny, cloudy and overcast days is 18%, 14.5% and 12% respectively, resulting in insufficient heating stability and the need for frequent switching to mains power supplementation.

[0004] Low inverter efficiency: Traditional inverters require multi-stage DC-AC-DC conversion, resulting in a 5% to 10% energy loss during each conversion. The overall system efficiency is less than 90%, and the multi-level topology is complex, resulting in high maintenance costs.

[0005] Serious energy waste: Existing systems fail to effectively recover waste heat and excess electricity. For example, when a typical air-source heat pump relies entirely on mains electricity, a 120-square-meter household consumes an average of 60 kWh of electricity per day. However, excess electricity generated by photovoltaic power generation is not stored but directly fed back to the grid, resulting in waste.

[0006] Prominent safety hazards: When AC power and photovoltaic power are connected in parallel, circulation and islanding effects are likely to occur. Traditional anti-islanding technology has a high switching delay (>100ms), and the DC high voltage (600-1000V) cannot be quickly shut down in the event of a fault, posing a risk of electric shock and fire.

[0007] Therefore, in view of this, the inventors provide a heating system using a dual-source heating technology that couples photovoltaic direct drive with mains electricity in order to solve the above problems. Summary of the Invention

[0008] The present invention provides a dual-source heating system coupled with photovoltaic direct drive and mains electricity, which solves the problems of photovoltaic volatility, energy waste and switching reliability through a three-level ANPC topology, a magnetically integrated bidirectional coupler and intelligent energy management technology.

[0009] To achieve the above objectives, the basic solution of the present invention provides a heating system using a dual-source heating technology that couples photovoltaic direct drive with mains electricity. The photovoltaic direct drive module consists of a photovoltaic array and a high-frequency isolated direct drive converter. The direct drive converter adopts a three-level ANPC topology and has a built-in MPPT algorithm based on deep learning. The direct power output by the photovoltaic array is directly converted to an adaptive voltage by the direct drive converter to drive the heating terminal.

[0010] Mains coupling module: The mains and PV direct drive output are connected in parallel via a bidirectional coupler based on magnetic integration technology. The bidirectional coupler integrates a fast synchronous switching relay and an active clamping anti-circulation current circuit.

[0011] Intelligent Energy Management Unit: This unit includes a sensor group and a coupling controller. The sensor group collects real-time signals of photovoltaic array output power, mains voltage, heating load demand, and ambient temperature. The coupling controller controls the operating states of the direct-drive converter and bidirectional coupler according to a preset strategy to achieve dynamic distribution of dual-source energy.

[0012] Waste energy recovery module: connected in parallel with the photovoltaic direct drive module and the heating terminal, including a DC-DC converter and a phase change heat storage device. The phase change heat storage device is provided with a micro heat pipe array, and a thermal-electric coupling integrated design is realized with the heating terminal through the micro heat pipe array; it also includes a waste heat recovery unit, which includes a heat conduction pipe network and a heat exchanger. The heat conduction pipe network covers the heating area of the heating terminal, and the waste heat generated during the heating process is transferred to the indoor circulating air or water supply system through the heat exchanger.

[0013] Furthermore, the intelligent energy management unit is equipped with an edge computing controller, which establishes a photovoltaic-load-mains power three-source prediction model based on the LSTM neural network, which can predict the light intensity, user thermal load and mains electricity price fluctuations in advance and generate the optimal energy scheduling strategy.

[0014] Furthermore, the direct-drive converter includes a multi-stage conversion circuit, which includes at least a front-stage DC-DC boost / buck circuit and a rear-stage DC-AC inverter circuit. The DC-DC boost / buck circuit integrates a maximum power point tracking MPPT algorithm module, and the rear-stage DC-AC inverter circuit outputs alternating current with a frequency of 50Hz±10% or direct current in the range of 36-400V.

[0015] Furthermore, the bidirectional coupler comprises:

[0016] Main relay group: includes PV-side relay (K1) and mains-side relay (K2), used to switch between three power supply modes: PV direct drive, mains supplement and dual-source parallel connection;

[0017] Synchronous rectification unit: uses IGBT or MOSFET power devices to achieve synchronous control of dual source currents;

[0018] Anti-islanding detection module: Prevents islanding effect when mains power is disconnected through active frequency offset method or passive voltage phase detection method.

[0019] Furthermore, the bidirectional coupler ensures priority utilization of photovoltaic energy through a dynamic current sharing algorithm (formula: I_{\text{PV}}=k\cdotI_{\text{AC}},k\in[0.8,1]) when dual-source power is used, thereby improving energy efficiency while meeting indoor temperature control accuracy.

[0020] Furthermore, the coupling controller may perform the following operations:

[0021] (1) When the output power of the photovoltaic array is greater than or equal to the heating load demand, the bidirectional coupler is controlled to disconnect the mains power supply, and only the photovoltaic direct drive module is used for independent power supply;

[0022] (2) When the output power of the photovoltaic array is less than the heating load demand, the bidirectional coupler is controlled to connect to the mains power, and the mains power supplements the insufficient power output of the photovoltaic array, and gives priority to ensuring the full utilization of the photovoltaic energy;

[0023] (3) When it is detected that the photovoltaic array stops working or the system fails, it automatically switches to the mains independent power supply mode.

[0024] Furthermore, the sensor group includes:

[0025] Photovoltaic side voltage / current sensor), accuracy level ≥ 0.5;

[0026] Mains side voltage / frequency sensor, supporting 0-400V voltage acquisition and 45-65Hz frequency monitoring;

[0027] The load end temperature sensor (4013) uses an NTC thermistor or thermocouple with a temperature measurement range of -40℃ to 120℃.

[0028] Furthermore, the coupling controller has a built-in communication module (4021) that supports RS485, Wi-Fi or 4G communication protocols, and is used to upload system operation data to a cloud platform and receive remote control instructions.

[0029] Furthermore, it also includes a heating airflow cleaning structure, which includes a self-cleaning nano-photocatalytic filter that can autonomously degrade pollutants attached to the surface of the filter under ultraviolet irradiation. It also includes an airflow equalization device, which uses a bionic fishtail-shaped guide blade, and the guide blade can be adjusted in angle by a motor.

[0030] The principles and effects of this basic solution are:

[0031] 1. Improved photovoltaic utilization rate

[0032] It uses a high-frequency three-level ANPC direct-drive converter to directly achieve power conversion through DC-DC boost / buck. The system efficiency is ≥98.5%, which is more than 10% higher than traditional inverters.

[0033] The PV-load-mains power forecasting model based on the LSTM neural network predicts sunlight and load demand 24 hours in advance, dynamically optimizes energy distribution, and increases the proportion of PV power generation covering the heating load to 70%-95% (on sunny days)25.

[0034] 2. Energy waste is significantly reduced

[0035] Excess electrical energy is recovered through a phase change heat storage device (micro heat pipe array), which increases the energy storage density and improves the thermal energy utilization rate.

[0036] The waste heat recovery unit (heat transfer pipe network + heat exchanger) transfers the waste heat from the heating terminal surface to the air circulation system, reducing operating costs.

[0037] 3. Enhanced security and reliability

[0038] The magnetically integrated bidirectional coupler integrates active frequency shift anti-islanding detection, which accelerates switching time and suppresses circulating current through active clamping circuits. The system meets grid-connected safety standards.

[0039] 4. Significant economic and environmental benefits

[0040] The photovoltaic direct drive mode saves a lot of city electricity. Combined with the peak-valley electricity price policy, users' average annual heating costs are greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 The overall schematic diagram of the heating system using the dual-source heating technology of photovoltaic direct drive coupled with mains power proposed in the embodiment of the present application is shown;

[0043] Figure 2 A schematic diagram of a direct-drive converter of a heating system using a dual-source heating technology of photovoltaic direct drive coupled with mains power, as proposed in an embodiment of the present application, is shown;

[0044] Figure 3 A schematic diagram of a bidirectional coupler of a heating system using a dual-source heating technology of photovoltaic direct drive coupled with mains power, as proposed in an embodiment of the present application, is shown;

[0045] Figure 4 A schematic diagram of a sensor group of a heating system using a dual-source heating technology of photovoltaic direct drive coupled with mains power, as proposed in an embodiment of the present application, is shown;

[0046] Figure 5 Schematic diagram showing the control principle of the coupling controller of the heating system using the dual-source heating technology of photovoltaic direct drive and mains coupling proposed in the embodiment of the present application

[0047] Figure 6 A schematic diagram of a waste energy recovery module of a heating system using a dual-source heating technology of photovoltaic direct drive coupled with mains electricity, as proposed in an embodiment of the present application, is shown. DETAILED DESCRIPTION

[0048] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0049] A heating system using dual-source heating technology, which combines photovoltaic direct drive with mains electricity, can be implemented, for example Figure 1-6 Shown: Includes:

[0050] The PV direct-drive module consists of a PV array and a high-frequency, isolated direct-drive converter. The converter utilizes a three-level ANPC topology, which improves efficiency by 1.2% compared to traditional full-bridge inverters and achieves THD of less than 3%. This reduces component stress issues associated with high-voltage inputs. A built-in MPPT algorithm based on deep learning overcomes the tracking lag inherent in traditional perturbation-and-observe methods under complex lighting conditions. Through direct-drive control, the DC power output from the PV array is directly converted to an appropriate voltage to drive the heating terminal, eliminating the need for batteries or intermediate energy storage. The converter comprises a multi-stage conversion circuit, consisting of at least a front-stage DC-DC boost / buck circuit and a back-stage DC-AC inverter circuit. The DC-DC boost / buck circuit integrates a maximum power point tracking (MPPT) algorithm. The back-stage DC-AC inverter circuit outputs AC power at a frequency of 50 Hz ± 10% or DC power in the 36-400 V range.

[0051] It also includes a mains coupling module: the mains and photovoltaic direct-drive outputs are connected in parallel through a bidirectional coupler based on magnetic integration technology. Magnetic integration technology reduces the inductor volume by 40% through optimized magnetic core structure, and the switching speed is three times faster than that of traditional relays, achieving "seamless connection" of dual-source power supply. The bidirectional coupler integrates fast synchronous switching relays and active clamping anti-circulation circuits. When dual-source power is supplied, the bidirectional coupler ensures the priority utilization of photovoltaic energy through a dynamic current sharing algorithm (formula: I_{\text{PV}}=k\cdotI_{\text{mains}},k\in[0.8,1]), thereby improving energy efficiency while meeting indoor temperature control accuracy and achieving circulation-free switching between photovoltaic direct-drive power supply and mains supplementary power supply.

[0052] The bidirectional coupler includes: a relay group: including a photovoltaic side relay (K1) and a mains side relay (K2), which is used to switch between the three power supply modes of photovoltaic direct drive, mains supplement and dual-source parallel according to the instructions of the intelligent energy management unit; a synchronous rectification unit: using IGBT or MOSFET power devices to realize synchronous control of dual-source current, real-time monitoring of dual-source input current, avoiding the circulation effect between photovoltaic and mains, and ensuring the current stability when the dual sources are connected in parallel; an anti-islanding detection module: using active frequency offset method or passive voltage phase detection method to prevent the islanding effect when the mains is disconnected. When the mains is accidentally disconnected, the connection between the photovoltaic direct drive module and the grid is quickly cut off to prevent the islanding effect (i.e., the dangerous state of the photovoltaic system supplying power to the grid alone). The coupling controller receives grid signals (such as peak and valley electricity prices and load scheduling instructions), and gives priority to using mains to charge the phase change heat storage device during the valley electricity price period, reduces the use of mains during the peak electricity price period, reduces the user's energy consumption cost, and supports the grid to shave peaks and fill valleys. A bidirectional coupler connects the mains power input and the output of the PV direct-drive converter in parallel to the heating terminal, forming a dual-source power supply topology with PV direct drive as the primary source and PV power as the secondary source. When PV output power is insufficient (such as on cloudy days or at night), the mains coupling module automatically activates, supplementing the missing PV power with the mains (formula: P_{\text{mains}} = \max(0, P_{\text{load}} - P_{\text{photovoltaic}})), ensuring continuous and stable operation of the heating terminal. Fast-switching relays (switching time <15ms) enable seamless switching, preventing the impact of power outages or voltage fluctuations on the heating terminal.

[0053] The bidirectional coupler features a built-in filter to suppress harmonic interference (THD < 5%) when connected to the mains. Power factor correction (PFC) technology also improves the system's grid-friendliness, achieving a power factor of ≥ 0.95. If the mains voltage is abnormal, the connection is disconnected. The mains coupling module can be independently installed and maintained, and is compatible with PV arrays of varying power levels, making it suitable for distributed heating in various scenarios, including homes, businesses, and industries.

[0054] Intelligent energy management unit: includes a sensor group and a coupling controller. The sensor group includes: photovoltaic side voltage / current sensor) with an accuracy level of ≥0.5; mains side voltage / frequency sensor, supporting 0-400V voltage acquisition and 45-65Hz frequency monitoring; load-end temperature sensor, using NTC thermistor or thermocouple, with a temperature measurement range of -40℃ to 120℃. The sensor group collects real-time data on the output voltage / current of the photovoltaic array (accuracy ≥0.5), mains voltage / frequency (supporting 45-65Hz monitoring), and the remaining capacity of the phase change heat storage device. It can also monitor the real-time power demand of the heating terminal, indoor and outdoor temperature (temperature measurement range of -40℃ to 120℃), and the surface temperature of the electric heating film (to prevent overheating). It can also obtain air quality data (PM2.5, formaldehyde concentration), light intensity, and grid peak and valley time / electricity price signals (via 4G / Wi-Fi communication module).

[0055] The coupling controller controls the working status of the direct-drive converter and the bidirectional coupler according to the preset strategy to realize the dynamic distribution of dual-source energy; the intelligent energy management unit is equipped with an edge computing controller, which establishes a photovoltaic-load-mains power three-source prediction model based on the LSTM neural network. The LSTM neural network prediction method is: based on the historical 7-day light, load, and electricity price data, it predicts energy supply and demand 12 hours in advance and generates the optimal scheduling plan (such as heat storage during valley electricity price periods and energy release during peak periods). It can predict light intensity, user heat load and mains electricity price fluctuations in advance, generate the optimal energy scheduling strategy, and thus adjust the heating terminal power in real time to avoid frequent start-stop losses.

[0056] The intelligent energy management unit can be linked with the hardware module for control. For example, it can dynamically adjust the MPPT operating point of the direct-drive converter to increase power generation by 8% to 12% in cloudy weather; achieve rapid mode-level switching through the relay group of the bidirectional coupler, and cooperate with the anti-islanding detection module to ensure the safety of the power grid; control the charging and discharging timing of the phase change heat storage device, and link the heating airflow cleaning structure to automatically start the high-efficiency purification mode.

[0057] The coupling controller can perform the following operations: (1) When the output power of the photovoltaic array is greater than or equal to the heating load demand, the bidirectional coupler is controlled to disconnect the mains power connection, and only the photovoltaic direct drive module is used for independent power supply; (2) When the output power of the photovoltaic array is less than the heating load demand, the bidirectional coupler is controlled to connect to the mains power, and the mains power is used to supplement the insufficient power output of the photovoltaic array, and the full utilization of the photovoltaic energy is prioritized; (3) When it is detected that the photovoltaic array stops working or the system fails, it automatically switches to the mains independent power supply mode. The coupling controller has a built-in communication module that supports RS485, Wi-Fi or 4G communication protocols, which is used to upload system operation data to the cloud platform and receive remote control instructions.

[0058] Waste Energy Recovery Module: Connected in parallel with the PV direct drive module and the heating terminal, it includes an excess energy recovery unit consisting of a DC-DC converter and a phase-change thermal storage device. The phase-change thermal storage device is equipped with a micro-heat pipe array. The phase-change thermal storage device uses graphene aerogel composite thermal storage material. The micro-heat pipe array and the heating terminal achieve a thermal-electrical coupling integrated design. When the PV array output power exceeds the heating load demand and the preset redundant power, the intelligent energy management unit triggers the excess energy recovery unit to operate. The excess photovoltaic power output by the direct drive converter is converted into an appropriate DC voltage by the DC-DC converter, driving the phase-change thermal storage device. Through electrical heating, the thermal storage material undergoes a phase change (e.g., from solid to liquid), converting the electrical energy into stored heat. This process effectively avoids the waste of excess photovoltaic power and achieves efficient utilization of renewable energy. At night or when there is insufficient sunlight, the PV array cannot meet the heating load demand, at which time the phase-change thermal storage device enters the energy release phase. Under the control of the coupling controller, the electric heating element in the device causes the heat storage material that has undergone phase change to undergo a reverse phase change (from liquid to solid), releasing the stored heat. By working in conjunction with the heating terminal, it continuously provides thermal energy to the system. This mechanism reduces the system's dependence on mains electricity, ensures the continuity and stability of heating, and reduces operating costs. Combined with the predictive function of the intelligent energy management unit, the phase change heat storage device can use mains electricity to heat and store energy during periods of low mains electricity prices. During periods of peak electricity prices, the stored energy is released first for heating, achieving "heat storage during low periods and heat use during peak periods." This not only reduces users' electricity costs, but also alleviates the power supply pressure of the power grid, improving the economy and rationality of energy utilization.

[0059] It also includes a waste heat recovery unit, which includes a heat transfer pipe network and a heat exchanger. The heat transfer pipe network covers the heating area of the heating terminal, and the waste heat generated during the heating process is transferred to the indoor circulating air or water supply system through the heat exchanger. The heat exchanger attached to the equipment is used for real-time collection, and the wall / ground temperature gradient difference is converted into recyclable thermal energy. The waste heat recovery unit can also collect the heat generated by the direct drive converter in the photovoltaic direct drive module, the bidirectional coupler in the AC coupling module and other power electronic devices during operation (recovery is started when the device temperature rises ≥40°C), and transfer the heat to the phase change heat storage device or the heating circuit.

[0060] It also includes a heating airflow cleaning structure, which includes a self-cleaning nano-photocatalytic filter that can autonomously degrade pollutants attached to the filter surface under ultraviolet light. It also includes an airflow equalization device, which uses bionic fishtail-shaped guide blades. The guide blades can be adjusted in angle by a motor to make the heating airflow more comfortable and uniform.

[0061] The use process of the present invention is as follows:

[0062] When the photovoltaic power is greater than or equal to the load demand, the mains power is cut off and the photovoltaic power supply is independent;

[0063] When the photovoltaic power is insufficient, the mains electricity will make up the difference, ensuring that the photovoltaic energy is fully utilized first;

[0064] In case of a fault, the system automatically switches to mains power supply and triggers an alarm.

[0065] The present invention combines photovoltaic power generation, mains power complementation and energy recovery technology to achieve efficient and intelligent clean energy heating.

[0066] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A heating system using dual-source heating technology that couples photovoltaic direct drive with mains electricity, characterized by: include: PV direct drive module: This module consists of a PV array and a high-frequency isolated direct drive converter. The direct drive converter adopts a three-level ANPC topology and has a built-in MPPT algorithm based on deep learning. The DC power output by the PV array is directly converted to an adaptive voltage by the direct drive converter to drive the heating terminal. Mains coupling module: The mains and PV direct drive output are connected in parallel via a bidirectional coupler based on magnetic integration technology. The bidirectional coupler integrates a fast synchronous switching relay and an active clamping anti-circulation circuit. Intelligent Energy Management Unit: This unit includes a sensor group and a coupling controller. The sensor group collects real-time signals of photovoltaic array output power, mains voltage, heating load demand, and ambient temperature. The coupling controller controls the operating states of the direct-drive converter and bidirectional coupler according to a preset strategy to achieve dynamic distribution of dual-source energy. Waste energy recovery module: connected in parallel with the photovoltaic direct drive module and the heating terminal, including an excess electric energy recovery unit, the excess electric energy recovery unit is composed of a DC-DC converter and a phase change heat storage device, the phase change heat storage device is provided with a micro heat pipe array, and the micro heat pipe array and the heating terminal are used to realize a thermal-electric coupling integrated design; it also includes a waste heat recovery unit, the waste heat recovery unit includes a heat conduction pipe network and a heat exchanger, the heat conduction pipe network covers the heating area of the heating terminal, and the waste heat generated during the heating process is transferred to the indoor circulating air or water supply system through the heat exchanger.

2. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The intelligent energy management unit is equipped with an edge computing controller, which establishes a photovoltaic-load-mains power three-source prediction model based on the LSTM neural network. It can predict light intensity, user thermal load and mains electricity price fluctuations in advance and generate the optimal energy scheduling strategy.

3. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The direct-drive converter includes a multi-stage conversion circuit, which includes at least a front-stage DC-DC boost / buck circuit and a rear-stage DC-AC inverter circuit. The DC-DC boost / buck circuit integrates a maximum power point tracking (MPPT) algorithm module, and the rear-stage DC-AC inverter circuit outputs alternating current with a frequency of 50 Hz ± 10% or direct current in the range of 36-400 V.

4. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The bidirectional coupler comprises: Main relay group: includes PV-side relay (K1) and mains-side relay (K2), used to switch between three power supply modes: PV direct drive, mains supplement and dual-source parallel connection; Synchronous rectification unit: uses IGBT or MOSFET power devices to achieve synchronous control of dual source currents; Anti-islanding detection module: Prevents islanding effect when mains power is disconnected through active frequency offset method or passive voltage phase detection method.

5. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 4 is characterized in that: The bidirectional coupler ensures priority utilization of photovoltaic energy through a dynamic current sharing algorithm (formula: I_{\text{PV}}=k\cdotI_{\text{AC}},k\in[0.8,1]) when dual-source power is used, thereby improving energy efficiency while meeting indoor temperature control accuracy.

6. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The coupling controller may perform the following operations: (1) When the output power of the photovoltaic array is greater than or equal to the heating load demand, the bidirectional coupler is controlled to disconnect the mains power supply, and only the photovoltaic direct drive module is used for independent power supply; (2) When the output power of the photovoltaic array is less than the heating load demand, the bidirectional coupler is controlled to connect to the mains power, and the mains power supplements the insufficient power output of the photovoltaic array, and gives priority to ensuring the full utilization of the photovoltaic energy; (3) When it is detected that the photovoltaic array stops working or the system fails, it automatically switches to the mains independent power supply mode.

7. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The sensor group includes: Photovoltaic side voltage / current sensor), accuracy level ≥ 0.5; Mains side voltage / frequency sensor, supporting 0-400V voltage acquisition and 45-65Hz frequency monitoring; The load end temperature sensor uses an NTC thermistor or thermocouple with a temperature measurement range of -40℃ to 120℃.

8. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: The coupling controller has a built-in communication module that supports RS485, Wi-Fi or 4G communication protocols, and is used to upload system operation data to the cloud platform and receive remote control instructions.

9. The heating system using dual-source heating technology of photovoltaic direct drive and mains coupling according to claim 1 is characterized in that: It also includes a heating airflow cleaning structure, which includes a self-cleaning nano-photocatalytic filter that can autonomously degrade pollutants attached to the filter surface under ultraviolet irradiation. It also includes an airflow equalizing device, which uses a bionic fishtail-shaped guide blade, and the guide blade can be adjusted in angle by a motor.

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