Photovoltaic air conditioning system, control method, electronic device and storage medium

Abstract

The application relates to a photovoltaic air conditioning system, a control method, electronic equipment and a storage medium, belongs to power conversion and application of solar photovoltaic power generation, and belongs to the solar industry of the new energy industry. The photovoltaic air conditioning system comprises two power paths of a direct path and an injection path, the direct path bears most of the power and does not pass through any high-frequency switching conversion, and the injection path is a path for supplementing a power gap when photovoltaic array power generation is insufficient. The injection path only bears a small part of the power when the photovoltaic array power generation is insufficient. Since the positive electrode of the photovoltaic array is directly electrically connected to the positive electrode of the direct current bus through any switching converter, the power transmission of the photovoltaic array is transmitted in the form of direct current through the direct path, and there is no conversion loss. Only part of the power when the photovoltaic array power generation is insufficient is transmitted through the series injection converter, most of the power does not pass through power conversion, the loss generated in the power conversion link is reduced, and the system efficiency can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic air conditioning technology, and in particular to a photovoltaic air conditioning system, control method, electronic device and storage medium. Background Technology

[0002] Photovoltaic direct-drive air conditioning systems are one of the key technological pathways to achieve building-integrated photovoltaic (PV) and energy storage (BIPV) systems with flexible operation. In traditional PV self-consumption schemes, PV and grid power are connected to the DC bus via independent power converters, and then the air conditioner compressor is driven by an inverter. However, regardless of whether the PV array can meet the load demand, all the power generated needs to be processed by the DC / DC converter, resulting in power conversion losses and affecting system efficiency. Summary of the Invention

[0003] This application provides a photovoltaic air conditioning system, control method, electronic device, and storage medium to solve the technical problem of how to reduce the losses generated in the power conversion process.

[0004] In a first aspect, this application provides a photovoltaic air conditioning system, which includes: a photovoltaic array, a series injection converter, a grid-side PFC unit, an inverter unit, an air conditioner, and a control unit; The positive terminal of the photovoltaic array is connected to the positive terminal of the DC bus, the negative terminal of the photovoltaic array is connected to the secondary side of the series injection converter, and the primary side of the series injection converter is connected to the positive and negative terminals of the DC bus respectively. The AC input terminal of the grid-side PFC unit is connected to the mains power, and the DC output terminal of the grid-side PFC unit is connected to the DC bus. The DC input terminal of the inverter unit is connected to the DC bus, and the AC output terminal of the inverter unit is connected to the air conditioner. The control unit is used to obtain the power generation of the photovoltaic array and the load power of the air conditioner; calculate the power difference between the load power and the power generation; when the power difference is greater than zero, start the grid-side PFC unit to compensate for the power difference; when the power difference is less than or equal to zero, limit the output power of the photovoltaic array through the series injection converter.

[0005] Optionally, the photovoltaic air conditioning system further includes a first capacitor and a second capacitor; The first terminal of the first capacitor is connected to the positive terminal of the photovoltaic array, the first terminal of the primary side of the series injection converter, and the positive terminal of the DC bus; the second terminal of the first capacitor is connected to the second terminal of the primary side of the series injection converter and the negative terminal of the DC bus. The first terminal of the second capacitor is connected to the negative terminal of the photovoltaic array and the first terminal of the secondary side of the series injection converter, and the second terminal of the second capacitor is connected to the second terminal of the secondary side of the series injection converter.

[0006] Optionally, the grid-side PFC unit includes a two-phase interleaved Boost-PFC circuit; The output terminals of the two-phase interleaved Boost-PFC circuit are respectively connected to the positive and negative terminals of the DC bus; the input terminal of the two-phase interleaved Boost-PFC circuit is connected to the mains power.

[0007] Optionally, the two-phase interleaved Boost-PFC circuit includes a first diode, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, a first switching transistor, a second switching transistor, a fifth diode, a sixth diode, and a third capacitor; The anode of the first diode is connected to the cathode of the second diode and the first terminal of the mains power supply, and the cathode of the first diode is connected to the cathode of the third diode, the first terminal of the first inductor, and the first terminal of the second inductor. The positive terminal of the second diode is connected to the positive terminal of the fourth diode, the second terminal of the first switching transistor, the second terminal of the second switching transistor, the second terminal of the third capacitor, and the negative terminal of the DC bus. The positive terminal of the third diode is connected to the negative terminal of the fourth diode and the second terminal of the mains power supply; The second end of the first inductor is connected to the first end of the first switching transistor and the positive terminal of the fifth diode; the second end of the second inductor is connected to the first end of the second switching transistor and the positive terminal of the sixth diode. The negative terminal of the fifth diode is connected to the negative terminal of the sixth diode, the first terminal of the third capacitor, and the positive terminal of the DC bus. The control terminal of the first switching transistor is connected to the first output terminal of the control unit, and the control terminal of the second switching transistor is connected to the second output terminal of the control unit.

[0008] Optionally, the inverter unit includes: a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a fourth capacitor; The first end of the third switch is connected to the first end of the fifth switch, the first end of the seventh switch, the first end of the fourth capacitor, and the positive terminal of the DC bus; the second end of the third switch is connected to the first end of the fourth switch and the first power supply terminal of the air conditioner. The second end of the fifth switch is connected to the first end of the sixth switch and the second power supply terminal of the air conditioner; the second end of the seventh switch is connected to the first end of the eighth switch and the third power supply terminal of the air conditioner. The second terminal of the fourth switch is connected to the second terminal of the sixth switch, the second terminal of the eighth switch, the second terminal of the fourth capacitor, and the negative terminal of the DC bus. The control terminal of the third switch is connected to the third output terminal of the control unit; the control terminal of the fourth switch is connected to the fourth output terminal of the control unit; the control terminal of the fifth switch is connected to the fifth output terminal of the control unit; the control terminal of the sixth switch is connected to the sixth output terminal of the control unit; the control terminal of the seventh switch is connected to the seventh output terminal of the control unit; and the control terminal of the eighth switch is connected to the eighth output terminal of the control unit.

[0009] Secondly, this application provides a photovoltaic air conditioning system control method, applied to any photovoltaic air conditioning system according to the first aspect, the method comprising: Obtain the power generation of the photovoltaic array and the load power of the air conditioner; Calculate the power difference between the load power and the generated power; When the power difference is greater than zero, the grid-side PFC unit is activated to compensate for the power difference; When the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by a series injection converter.

[0010] Optionally, when the power difference is greater than zero, the grid-side PFC unit is activated to compensate for the power difference, including: When the power difference is greater than zero, the grid-side PFC unit is started. The series injection converter is controlled to perform maximum power point tracking on the photovoltaic array; The current reference value is calculated based on the power difference and the effective value of the AC input voltage of the grid-side PFC unit, so as to compensate the DC bus according to the current reference value by the grid-side PFC unit.

[0011] Optionally, when the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by a series injection converter, including: When the power difference is less than or equal to zero, power limiting control is performed through the series injection converter to make the actual output power of the photovoltaic array less than the maximum output power of the photovoltaic array.

[0012] Thirdly, this application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes the program stored in the memory, it implements the photovoltaic air conditioning system control method described in any embodiment of the second aspect.

[0013] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the photovoltaic air conditioning system control method as described in any embodiment of the first aspect.

[0014] Compared with the prior art, the above-mentioned technical solution provided in this application embodiment has the following advantages: The photovoltaic air conditioning system provided in this application embodiment includes: a photovoltaic array, a series injection converter, a grid-side PFC unit, an inverter unit, an air conditioner, and a control unit; the positive terminal of the photovoltaic array is connected to the positive terminal of the DC bus, the negative terminal of the photovoltaic array is connected to the secondary side of the series injection converter, and the primary side of the series injection converter is connected to the positive and negative terminals of the DC bus respectively; the AC input terminal of the grid-side PFC unit is connected to the mains power, and the DC output terminal of the grid-side PFC unit is connected to the DC bus; the DC input terminal of the inverter unit is connected to the DC bus, and the AC output terminal of the inverter unit is connected to the air conditioner; the control unit is used to obtain the power generation of the photovoltaic array and the load power of the air conditioner; calculate the power difference between the load power and the power generation; when the power difference is greater than zero, start the grid-side PFC unit to compensate for the power difference; when the power difference is less than or equal to zero, limit the output power of the photovoltaic array through the series injection converter. This photovoltaic air conditioning system includes two power paths: a direct path and an injection path. The direct path connects the positive terminal of the photovoltaic array to the positive terminal of the DC bus, then to the air conditioner, the negative terminal of the DC bus, the series injection converter, and back to the negative terminal of the photovoltaic array. This direct path carries most of the power without any high-frequency switching. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through the grid-side PFC unit and the DC bus, and outputs a series injection voltage through the secondary side of the series injection converter. This injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Since the positive terminal of the photovoltaic array is directly connected to the DC bus without any switching converter, this path is used to supplement the power. In this direct path, the power of the photovoltaic array is transmitted in DC form without conversion loss. Only a portion of the power generated by the photovoltaic array is transmitted through the series injection converter when the photovoltaic array's power generation is insufficient. This means that most of the power does not undergo power conversion, reducing the losses generated in the power conversion stage and effectively improving system efficiency. Furthermore, the control unit can control the output current of the grid-side PFC unit or control the series injection converter to limit the output power of the photovoltaic array based on the power difference between the load power and the generated power. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 A system architecture diagram of a photovoltaic air conditioning system provided in one embodiment of this application; Figure 2 A circuit diagram of a photovoltaic air conditioning system provided in one embodiment of this application; Figure 3 This is a flowchart illustrating a photovoltaic air conditioning system control method according to one embodiment of this application. Figure 4 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0019] The attached icons are numbered as follows: C1 - First capacitor; C2 - Second capacitor; C3 - Third capacitor; C4 - Fourth capacitor; D1 - First diode; D2 - Second diode; D3 - Third diode; D4 - Fourth diode; D5 - Fifth diode; D6 - Sixth diode; L1 - First inductor; L2 - Second inductor; S1 - First switch; S2 - Second switch; S3 - Third switch; S4 - Fourth switch; S5 - Fifth switch; S6 - Sixth switch; S7 - Seventh switch; S8 - Eighth switch. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0022] To address the technical problem of reducing losses in power conversion stages in existing technologies, this application provides a photovoltaic air conditioning system, control method, electronic equipment, and storage medium. It designs two power paths: a direct path and an injection path. The direct path connects the positive terminal of the photovoltaic array to the positive terminal of the DC bus, the air conditioner, the negative terminal of the DC bus, the series injection converter, and back to the negative terminal of the photovoltaic array. The direct path carries most of the power without any high-frequency switching. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through a grid-side power factor correction (PFC) unit and the DC bus, and outputs a series injection voltage through the secondary side of the series injection converter. The injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Because the positive terminal of the photovoltaic array is directly connected to the positive terminal of the DC bus without any switching converter, the power transmission of the photovoltaic array is carried out in DC form through this direct path, without conversion loss. Only a portion of the power generated by the photovoltaic array is transmitted through the series injection converter when the photovoltaic array is underpowered. This means that most of the power does not go through power conversion, reducing the losses generated in the power conversion stage and effectively improving system efficiency. Furthermore, the control unit can control the output current of the grid-side PFC unit or control the series injection converter to limit the output power of the photovoltaic array based on the power difference between the load power and the generated power. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability.

[0023] The first embodiment of this application provides a photovoltaic air conditioning system, such as... Figure 1 The photovoltaic air conditioning system includes: a photovoltaic array, a series injection converter, a grid-side PFC unit, an inverter unit, an air conditioner, and a control unit.

[0024] The positive terminal of the photovoltaic array is connected to the positive terminal of the DC bus (DC Bus+), and the negative terminal of the photovoltaic array is connected to the secondary side of the series injection converter. The primary side of the series injection converter is connected to the positive terminal and the negative terminal of the DC bus (DC Bus-) respectively. The AC input terminal of the grid-side PFC unit is connected to the mains power, and the DC output terminal of the grid-side PFC unit is connected to the DC bus. The DC input terminal of the inverter unit is connected to the DC bus, and the AC output terminal of the inverter unit is connected to the air conditioner. The control unit is used to obtain the power generation of the photovoltaic array and the load power of the air conditioner; calculate the power difference between the load power and the power generation; when the power difference is greater than zero, the grid-side PFC unit is activated to compensate for the power difference; when the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by the series injection converter.

[0025] This photovoltaic air conditioning system includes two power paths: a direct path and an injection path. The direct path connects the positive terminal of the photovoltaic array to the positive terminal of the DC bus, then to the air conditioner, the negative terminal of the DC bus, the series injection converter, and back to the negative terminal of the photovoltaic array. This direct path carries most of the power without any high-frequency switching. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through the grid-side PFC unit and the DC bus, and outputs a series injection voltage through the secondary side of the series injection converter. This injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Since the positive terminal of the photovoltaic array is directly connected to the DC bus without any switching converter, this path is used to supplement the power. In this direct path, the power of the photovoltaic array is transmitted in DC form without conversion loss. Only a portion of the power generated by the photovoltaic array is transmitted through the series injection converter when the photovoltaic array's power generation is insufficient. This means that most of the power does not undergo power conversion, reducing the losses generated in the power conversion stage and effectively improving system efficiency. Furthermore, the control unit can control the output current of the grid-side PFC unit or control the series injection converter to limit the output power of the photovoltaic array based on the power difference between the load power and the generated power. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability.

[0026] In one embodiment, the series injection converter can also be called a DC / DC converter. It can be an isolated or non-isolated bidirectional DC / DC converter. The primary side of the series injection converter is connected to the positive and negative terminals of the DC bus, respectively. The secondary side of the series injection converter is connected in series between the negative terminal of the photovoltaic array and the negative terminal of the DC bus. This allows the direct path to bypass any high-frequency switching conversion. Most of the photovoltaic power in the system is transmitted along the direct path. Only the part where the grid-side PFC unit compensates for the power difference passes through the series injection converter via the injection path. This reduces the losses generated in the power conversion stage and can effectively improve the system efficiency.

[0027] In one embodiment, the circuit diagram of the photovoltaic air conditioning system is as follows: Figure 2 The photovoltaic air conditioning system also includes a first capacitor C1 and a second capacitor C2.

[0028] The first terminal of the first capacitor C1 is connected to the positive terminal of the photovoltaic array, the first terminal of the primary side of the series injection converter, and the positive terminal of the DC bus. The second terminal of the first capacitor C1 is connected to the second terminal of the primary side of the series injection converter and the negative terminal of the DC bus. The first terminal of the second capacitor C2 is connected to the negative terminal of the photovoltaic array and the first terminal of the secondary side of the series injection converter. The second terminal of the second capacitor C2 is connected to the second terminal of the secondary side of the series injection converter.

[0029] In this embodiment, the first capacitor C1 is connected in parallel between the positive and negative terminals of the DC bus. It can stabilize the DC bus voltage, buffer voltage fluctuations at the output of the PFC unit on the grid side, and suppress voltage spikes on the DC bus caused by sudden changes in air conditioner load. The second capacitor C2 is connected in parallel between the first and second terminals of the secondary side of the series injection converter. It can clamp and protect the voltage across the secondary winding, suppress voltage spikes caused by leakage inductance on the secondary side of the series injection converter, and protect the secondary side from overvoltage.

[0030] The grid-side PFC unit can be a power factor correction circuit of various forms, such as a totem pole bridgeless PFC circuit, a single-channel Boost PFC circuit, a two-phase interleaved Boost-PFC circuit, or a dual-Boost bridgeless PFC circuit.

[0031] In one embodiment, a grid-side PFC unit is used as an example of a two-phase interleaved Boost-PFC circuit. The output terminals of the two-phase interleaved Boost-PFC circuit are connected to the positive and negative terminals of the DC bus, respectively; the input terminals of the two-phase interleaved Boost-PFC circuit are connected to the mains power.

[0032] Specifically, the two-phase interleaved Boost-PFC circuit includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a fifth diode D5, a sixth diode D6, and a third capacitor C3.

[0033] The connection relationships are as follows: The positive terminal of the first diode D1 is connected to the negative terminal of the second diode D2 and the first terminal of the mains power supply. The negative terminal of the first diode D1 is connected to the negative terminal of the third diode D3, the first terminal of the first inductor L1, and the first terminal of the second inductor L2. The positive terminal of the second diode D2 is connected to the positive terminal of the fourth diode D4, the second terminal of the first switch S1, the second terminal of the second switch S2, the second terminal of the third capacitor C3, and the negative terminal of the DC bus. The positive terminal of the third diode D3 is connected to the negative terminal of the fourth diode D4 and the second terminal of the mains power supply; The second terminal of the first inductor L1 is connected to the first terminal of the first switch S1 and the positive terminal of the fifth diode D5; the second terminal of the second inductor L2 is connected to the first terminal of the second switch S2 and the positive terminal of the sixth diode D6. The cathode of the fifth diode D5 is connected to the cathode of the sixth diode D6, the first terminal of the third capacitor C3, and the positive terminal of the DC bus. The control terminal of the first switch S1 is connected to the first output terminal of the control unit, and the control terminal of the second switch S2 is connected to the second output terminal of the control unit.

[0034] In this embodiment, a two-phase interleaved Boost-PFC circuit is formed by first diode D1, second diode D2, third diode D3, fourth diode D4, first inductor L1, second inductor L2, first switch S1, second switch S2, fifth diode D5, sixth diode D6, and third capacitor C3. When the two-phase interleaved Boost-PFC circuit needs to compensate for the power difference, the output of the two-phase interleaved Boost-PFC circuit is realized by controlling the on and off of the first and second switches through the control unit.

[0035] Specifically, the control unit first obtains the load power of the air conditioner and the power generated by the photovoltaic array, calculates the power difference, and when the control unit determines that the power difference is greater than zero, it starts the two-phase interleaved Boost-PFC circuit to compensate the DC bus for power, collects the effective value of the mains input voltage, calculates the reference effective value of the AC input current based on the power difference and the effective value of the mains voltage, and generates the instantaneous current reference signal by combining the instantaneous mains voltage waveform.

[0036] The total instantaneous current reference is evenly divided and used as the inductor current reference for the two branches of the two-phase interleaved Boost-PFC circuit. The control unit samples the actual inductor currents of the first and second inductors and generates the PWM duty cycles of the first and second switching transistors respectively through a current PI regulator. The first and second output terminals of the control unit output PWM drive signals with phases staggered by 180° to drive the first and second switching transistors respectively. The two branches operate in an interleaved manner. After the inductors store energy, they output compensation power to the DC bus through freewheeling diodes, thereby supplementing the DC bus with the differential power. At the same time, the mains input current follows the phase of the grid voltage to achieve a high power factor.

[0037] During the operation of the two-phase interleaved Boost-PFC circuit, the control unit simultaneously controls the series injection converter to perform maximum power point tracking (MPPT) control, so that the photovoltaic array outputs the maximum possible power generation. When the power difference is less than or equal to zero, the control unit stops outputting PWM drive, the first and second switches are turned off, and the two-phase interleaved Boost-PFC circuit stops power compensation.

[0038] In one embodiment, the inverter unit includes: a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, and a fourth capacitor C4.

[0039] The first terminal of the third switch S3 is connected to the first terminal of the fifth switch S5, the first terminal of the seventh switch S7, the first terminal of the fourth capacitor C4, and the positive terminal of the DC bus; the second terminal of the third switch S3 is connected to the first terminal of the fourth switch S4 and the first power supply terminal of the air conditioner. The second end of the fifth switch S5 is connected to the first end of the sixth switch S6 and the second power supply terminal of the air conditioner; the second end of the seventh switch S7 is connected to the first end of the eighth switch S8 and the third power supply terminal of the air conditioner. The second terminal of the fourth switch S4 is connected to the second terminal of the sixth switch S6, the second terminal of the eighth switch S8, the second terminal of the fourth capacitor C4, and the negative terminal of the DC bus. The control terminal of the third switch S3 is connected to the third output terminal of the control unit; the control terminal of the fourth switch S4 is connected to the fourth output terminal of the control unit; the control terminal of the fifth switch S5 is connected to the fifth output terminal of the control unit; the control terminal of the sixth switch S6 is connected to the sixth output terminal of the control unit; the control terminal of the seventh switch S7 is connected to the seventh output terminal of the control unit; and the control terminal of the eighth switch S8 is connected to the eighth output terminal of the control unit.

[0040] In this embodiment, the inverter unit is a three-phase full-bridge voltage-source inverter circuit, including three-phase bridge arms and a fourth capacitor C4. The third switch S3 and the fourth switch S4 form phase A, the fifth switch S5 and the sixth switch S6 form phase B, and the seventh switch S7 and the eighth switch S8 form phase C. The first terminals of the upper switches in each phase bridge arm are connected to the positive terminal of the DC bus, and the second terminals of the lower switches in each phase bridge arm are connected to the negative terminal of the DC bus. The midpoint between the upper and lower switches in each phase bridge arm serves as the three-phase AC output terminal, connected to the three-phase power supply terminals of the air conditioner's compressor motor. The fourth capacitor C4 is connected in parallel between the positive and negative terminals of the DC bus, serving as an internal support capacitor for the inverter unit, providing instantaneous current to each switch nearby, and suppressing voltage spikes generated by switching operations.

[0041] The control unit outputs PWM drive signals with dead-time protection at its third to eighth output terminals, controlling the on / off states of the third to eighth switching transistors respectively. Through space vector PWM modulation, the duty cycle of the three-phase bridge arm switching transistors is controlled, converting the DC power on the DC bus into three-phase AC power with adjustable frequency and amplitude to drive the air conditioner compressor motor. The compressor speed is adjusted by regulating the frequency of the output AC power. Drive interlocking and dead-time are set for the upper and lower switching transistors on the same bridge arm to prevent simultaneous conduction of the upper and lower transistors, which could cause a short circuit on the DC bus. The feedback energy generated during compressor operation is buffered and absorbed by the fourth capacitor and the first capacitor.

[0042] In the embodiments described above, the photovoltaic air conditioning system includes two power paths: a direct path and an injection path. The direct path consists of the positive terminal of the photovoltaic array, the positive terminal of the DC bus, the air conditioner, the negative terminal of the DC bus, the series injection converter, and the negative terminal of the photovoltaic array. The direct path carries most of the power and does not pass through any high-frequency switching conversion. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through the grid-side PFC unit and the DC bus, and outputs the series injection voltage through the secondary side of the series injection converter. The injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Since the positive terminal of the photovoltaic array is directly connected to the grid without any switching converter, the direct path is used to supplement the power gap. The photovoltaic array's power is transmitted directly through the positive terminal of the DC bus in DC form, without conversion losses. Only a portion of the power generated by the photovoltaic array is transmitted via the series injection converter when the photovoltaic array's power generation is insufficient. This allows most of the power to bypass power conversion, reducing losses in the power conversion stage and effectively improving system efficiency. Furthermore, the control unit can control the output current of the grid-side PFC unit or control the series injection converter to limit the output power of the photovoltaic array based on the power difference between the load power and the generated power. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability.

[0043] Based on the same technical concept, the second embodiment of this application provides a photovoltaic air conditioning system control method, such as... Figure 3 The method, applied to any one of the photovoltaic air conditioning systems in the first embodiment, includes: Step 301: Obtain the power generation of the photovoltaic array and the load power of the air conditioner.

[0044] Step 302: Calculate the power difference between the load power and the power generation power.

[0045] Step 303: When the power difference is greater than zero, start the grid-side PFC unit to compensate for the power difference.

[0046] Step 304: When the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by a series injection converter.

[0047] In this embodiment, the photovoltaic air conditioning system control method is applied to the photovoltaic air conditioning system of the aforementioned embodiment. This photovoltaic air conditioning system includes two power paths: a direct path and an injection path. The direct path consists of the positive terminal of the photovoltaic array, the positive terminal of the DC bus, the air conditioner, the negative terminal of the DC bus, the series injection converter, and the negative terminal of the photovoltaic array. The direct path carries most of the power and does not pass through any high-frequency switching converter. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through the grid-side PFC unit and the DC bus, and outputs a series injection voltage through the secondary side of the series injection converter. The injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Since the positive terminal of the photovoltaic array does not pass through any switching converter... By directly connecting the photovoltaic array to the positive terminal of the DC bus, the power transmission of the photovoltaic array is carried out in DC form through this direct path, without conversion losses. Only a portion of the power generated by the photovoltaic array is transmitted through the series injection converter when the photovoltaic array's power generation is insufficient. This achieves the goal of eliminating most of the power from power conversion, reducing the losses generated in the power conversion stage, and effectively improving system efficiency. In this control method, the control unit can control the grid-side PFC unit to compensate for the power difference between the load power and the generated power, or control the series injection converter to limit the output power of the photovoltaic array. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability.

[0048] After the system is powered on, the control unit first performs power-on initialization. During initialization, the control unit completes internal register configuration and self-tests of each peripheral module. All switching transistors in the series injection converter and inverter units remain off to prevent false triggering at the moment of power-on. If a fault is detected during self-test, a fault alarm is output, and the system does not enter normal operating mode. If all self-tests are normal, the system enters standby mode, waiting for the air conditioner operation command. When the user issues the air conditioner start command, the entire unit enters the operating state, and the control unit starts cyclic sampling, continuously collecting system operating parameters according to a preset fixed control cycle.

[0049] The operating parameters collected in real time by the control unit may include the photovoltaic array output voltage V. pv Photovoltaic array output current I pv The output voltage V is obtained through the photovoltaic array. pv Photovoltaic array output current I pv The real-time output power P of the photovoltaic array is calculated in real time. pv Collect the operating status of the air conditioner compressor and read the DC current I flowing into the inverter. load Bus voltage V dc Calculate the real-time load power P of the air conditioner compressor load =V dc ×I load The control unit calculates the power difference ΔP = P. load P pv This power difference represents the gap between the load demand power and the actual output power of the photovoltaic system. It serves as the basis for judging the switching of the overall operating conditions. Based on the magnitude of the power difference, it can be divided into two typical operating conditions: insufficient photovoltaic power supply and surplus photovoltaic power. Under different operating conditions, the series injection converter and the grid-side PFC unit perform corresponding actions.

[0050] The first operating condition is insufficient photovoltaic power supply, i.e., ΔP>0. When the power difference is greater than zero, the grid-side PFC unit is started; the series injection converter is controlled to perform maximum power point tracking on the photovoltaic array; the current reference value is calculated based on the power difference and the effective value of the AC input voltage of the grid-side PFC unit, so as to compensate the DC bus according to the current reference value through the grid-side PFC unit.

[0051] In this embodiment, the load power of the air conditioner compressor exceeds the real-time output power of the photovoltaic array. The photovoltaic power generation is insufficient to support the air conditioner load consumption, necessitating the activation of the grid-side PFC unit to compensate for the power difference to the DC bus. Under this condition, the control unit first enables the grid-side PFC unit, releasing the drive blockade on the first and second switching transistors; simultaneously, it controls the series injection converter to perform maximum power point tracking (MPPT) control, fully utilizing the photovoltaic array's power generation capacity. During MPPT execution, the photovoltaic array operates at its maximum power operating point under the current illumination conditions. The power output from the photovoltaic array is transmitted to the load via a direct path; only the power compensated by the grid-side PFC unit passes through the injection path of the series injection converter. Therefore, most of the power bypasses power conversion, reducing losses in the power conversion stage and effectively improving system efficiency.

[0052] When the grid-side PFC unit is enabled, the current reference value can be calculated based on the power difference and the effective value of the AC input voltage. The current reference value Ipfc_ref=ΔP / Vac_rms; where ΔPV is the power difference and ac_rms is the effective value of the AC input voltage. The series injection converter executes the MPPT algorithm, the photovoltaic provides all available power, and the grid only supplements the difference.

[0053] The grid-side PFC unit can be a two-phase interleaved Boost-PFC circuit. When the control unit determines that the power difference is greater than zero, it activates the two-phase interleaved Boost-PFC circuit to compensate the DC bus for power. It collects the effective value of the mains input voltage and calculates the AC input current reference effective value based on the power difference and the mains voltage effective value. This reference value is then combined with the instantaneous mains voltage waveform to generate an instantaneous current reference signal. The total instantaneous current reference is evenly divided and used as the inductor current reference for the two branches of the two-phase interleaved Boost-PFC circuit. The control unit samples the actual inductor currents of the first and second inductors and generates the PWM duty cycles for the first and second switching transistors respectively through a current PI regulator. The first and second output terminals of the control unit output PWM drive signals with a 180° phase offset, driving the first and second switching transistors respectively. The two branches operate interleaved, and the inductors store energy and output compensated power to the DC bus via freewheeling diodes, thus supplementing the DC bus with the differential power. Simultaneously, the mains input current follows the phase of the grid voltage, achieving a high power factor.

[0054] During the operation of the two-phase interleaved Boost-PFC circuit, the control unit simultaneously controls the series injection converter to perform MPPT control, so that the photovoltaic array outputs the maximum possible power generation. When the power difference is less than or equal to zero, the control unit stops outputting PWM drive, the first switch and the second switch are turned off, and the two-phase interleaved Boost-PFC circuit stops power compensation.

[0055] The second operating condition is the photovoltaic power surplus condition, i.e., ΔP<0. When the power difference is less than or equal to zero, power limiting control is performed through a series injection converter to make the actual output power of the photovoltaic array less than the maximum output power of the photovoltaic array.

[0056] In this embodiment, the output power of the photovoltaic array exceeds the power consumed by the air conditioner compressor load. Without control, this excess power will continuously charge the bus capacitor, causing a rise in the DC bus voltage and posing an overvoltage risk. In this embodiment, the grid-side PFC unit stops working, and the series injection converter performs photovoltaic-side power limiting control to reduce the actual output power of the photovoltaic array and match the load consumption. The power limiting control logic is as follows: the control unit adjusts the equivalent DC compensation voltage of the series injection converter, changing the operating point of the photovoltaic array. This shifts the photovoltaic array from its maximum power point to a higher voltage, lower output power operating region, reducing the photovoltaic output power to match the air conditioner load power and eliminating power surplus. Under this condition, the photovoltaic array still supplies power to the inverter unit via a direct path, eliminating conversion losses and reducing losses in the power conversion stage. This effectively improves system efficiency. Furthermore, since all system power comes from the photovoltaic array, the grid does not draw power from the system, avoiding reverse power fluctuations. If the control unit detects a continuous increase in light intensity and a continuous increase in surplus power, it can increase the power limiting intensity and further raise the photovoltaic operating voltage to limit the photovoltaic output power. When the control unit detects a rapid decrease in light intensity and a reduction in surplus power, it can gradually reduce the power limiting depth to make the most of photovoltaic power generation.

[0057] In the above embodiments of this application, the photovoltaic air conditioning system includes: a photovoltaic array, a series injection converter, a grid-side PFC unit, an inverter unit, an air conditioner, and a control unit; the positive terminal of the photovoltaic array is connected to the positive terminal of the DC bus, the negative terminal of the photovoltaic array is connected to the secondary side of the series injection converter, and the primary side of the series injection converter is connected to the positive and negative terminals of the DC bus respectively; the AC input terminal of the grid-side PFC unit is connected to the mains power, and the DC output terminal of the grid-side PFC unit is connected to the DC bus; the DC input terminal of the inverter unit is connected to the DC bus, and the AC output terminal of the inverter unit is connected to the air conditioner; the control unit is used to obtain the power generation of the photovoltaic array and the load power of the air conditioner; calculate the power difference between the load power and the power generation; when the power difference is greater than zero, start the grid-side PFC unit to compensate for the power difference; when the power difference is less than or equal to zero, limit the output power of the photovoltaic array through the series injection converter. This photovoltaic air conditioning system includes two power paths: a direct path and an injection path. The direct path connects the positive terminal of the photovoltaic array to the positive terminal of the DC bus, then to the air conditioner, the negative terminal of the DC bus, the series injection converter, and back to the negative terminal of the photovoltaic array. This direct path carries most of the power without any high-frequency switching. The injection path is used to supplement the power gap when the photovoltaic array's power generation is insufficient. It passes through the grid-side PFC unit and the DC bus, and outputs a series injection voltage through the secondary side of the series injection converter. This injection path only carries a small portion of the power when the photovoltaic array's power generation is insufficient. Since the positive terminal of the photovoltaic array is directly connected to the DC bus without any switching converter, this path is used to supplement the power. In this direct path, the power of the photovoltaic array is transmitted in DC form without conversion loss. Only a portion of the power generated by the photovoltaic array is transmitted through the series injection converter when the photovoltaic array's power generation is insufficient. This means that most of the power does not undergo power conversion, reducing the losses generated in the power conversion stage and effectively improving system efficiency. Furthermore, the control unit can control the output current of the grid-side PFC unit or control the series injection converter to limit the output power of the photovoltaic array based on the power difference between the load power and the generated power. This eliminates the oscillation risk caused by the competition for the DC bus between the two voltage sources, the photovoltaic array and the grid-side PFC unit, and improves system stability.

[0058] like Figure 4 As shown in the figure, this application provides an electronic device, including a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114. Memory 113 is used to store computer programs; In one embodiment of this application, the processor 111, when executing the program stored in the memory 113, implements the photovoltaic air conditioning system control method provided in any of the foregoing method embodiments.

[0059] The communication bus mentioned above can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus.

[0060] The communication interface is used for communication between the aforementioned terminal and other devices.

[0061] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0062] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0063] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the photovoltaic air conditioning system control method provided in any of the foregoing method embodiments.

[0064] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0065] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0066] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0067] It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. In the description, suffixes such as "module," "part," or "unit" used to denote elements are used solely for illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0068] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A photovoltaic air conditioning system, characterized in that, The photovoltaic air conditioning system includes: a photovoltaic array, a series injection converter, a grid-side PFC unit, an inverter unit, an air conditioner, and a control unit; The positive terminal of the photovoltaic array is connected to the positive terminal of the DC bus, the negative terminal of the photovoltaic array is connected to the secondary side of the series injection converter, and the primary side of the series injection converter is connected to the positive and negative terminals of the DC bus respectively. The AC input terminal of the grid-side PFC unit is connected to the mains power, and the DC output terminal of the grid-side PFC unit is connected to the DC bus. The DC input terminal of the inverter unit is connected to the DC bus, and the AC output terminal of the inverter unit is connected to the air conditioner. The control unit is used to obtain the power generation of the photovoltaic array and the load power of the air conditioner; calculate the power difference between the load power and the power generation; when the power difference is greater than zero, start the grid-side PFC unit to compensate for the power difference; when the power difference is less than or equal to zero, limit the output power of the photovoltaic array through the series injection converter.

2. The photovoltaic air conditioning system according to claim 1, characterized in that, The photovoltaic air conditioning system also includes a first capacitor and a second capacitor; The first terminal of the first capacitor is connected to the positive terminal of the photovoltaic array, the first terminal of the primary side of the series injection converter, and the positive terminal of the DC bus; the second terminal of the first capacitor is connected to the second terminal of the primary side of the series injection converter and the negative terminal of the DC bus. The first terminal of the second capacitor is connected to the negative terminal of the photovoltaic array and the first terminal of the secondary side of the series injection converter, and the second terminal of the second capacitor is connected to the second terminal of the secondary side of the series injection converter.

3. The photovoltaic air conditioning system according to claim 1, characterized in that, The grid-side PFC unit includes a two-phase interleaved Boost-PFC circuit; The output terminals of the two-phase interleaved Boost-PFC circuit are respectively connected to the positive and negative terminals of the DC bus; the input terminal of the two-phase interleaved Boost-PFC circuit is connected to the mains power.

4. The photovoltaic air conditioning system according to claim 3, characterized in that, The two-phase interleaved Boost-PFC circuit includes a first diode, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, a first switching transistor, a second switching transistor, a fifth diode, a sixth diode, and a third capacitor; The anode of the first diode is connected to the cathode of the second diode and the first terminal of the mains power supply, and the cathode of the first diode is connected to the cathode of the third diode, the first terminal of the first inductor, and the first terminal of the second inductor. The positive terminal of the second diode is connected to the positive terminal of the fourth diode, the second terminal of the first switching transistor, the second terminal of the second switching transistor, the second terminal of the third capacitor, and the negative terminal of the DC bus. The positive terminal of the third diode is connected to the negative terminal of the fourth diode and the second terminal of the mains power supply; The second end of the first inductor is connected to the first end of the first switching transistor and the positive terminal of the fifth diode; the second end of the second inductor is connected to the first end of the second switching transistor and the positive terminal of the sixth diode. The negative terminal of the fifth diode is connected to the negative terminal of the sixth diode, the first terminal of the third capacitor, and the positive terminal of the DC bus. The control terminal of the first switching transistor is connected to the first output terminal of the control unit, and the control terminal of the second switching transistor is connected to the second output terminal of the control unit.

5. The photovoltaic air conditioning system according to claim 1, characterized in that, The inverter unit includes: a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a fourth capacitor; The first end of the third switch is connected to the first end of the fifth switch, the first end of the seventh switch, the first end of the fourth capacitor, and the positive terminal of the DC bus; the second end of the third switch is connected to the first end of the fourth switch and the first power supply terminal of the air conditioner. The second end of the fifth switch is connected to the first end of the sixth switch and the second power supply terminal of the air conditioner; the second end of the seventh switch is connected to the first end of the eighth switch and the third power supply terminal of the air conditioner. The second terminal of the fourth switch is connected to the second terminal of the sixth switch, the second terminal of the eighth switch, the second terminal of the fourth capacitor, and the negative terminal of the DC bus. The control terminal of the third switch is connected to the third output terminal of the control unit; the control terminal of the fourth switch is connected to the fourth output terminal of the control unit; the control terminal of the fifth switch is connected to the fifth output terminal of the control unit; the control terminal of the sixth switch is connected to the sixth output terminal of the control unit; the control terminal of the seventh switch is connected to the seventh output terminal of the control unit; and the control terminal of the eighth switch is connected to the eighth output terminal of the control unit.

6. A control method for a photovoltaic air conditioning system, characterized in that, The method, applied to the photovoltaic air conditioning system of any one of claims 1-5, comprises: Obtain the power generation of the photovoltaic array and the load power of the air conditioner; Calculate the power difference between the load power and the generated power; When the power difference is greater than zero, the grid-side PFC unit is activated to compensate for the power difference; When the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by a series injection converter.

7. The method according to claim 6, characterized in that, include: When the power difference is greater than zero, the grid-side PFC unit is activated to compensate for the power difference, including: When the power difference is greater than zero, the grid-side PFC unit is started. The series injection converter is controlled to perform maximum power point tracking on the photovoltaic array; The current reference value is calculated based on the power difference and the effective value of the AC input voltage of the grid-side PFC unit, so as to compensate the DC bus according to the current reference value by the grid-side PFC unit.

8. The method according to claim 6, characterized in that, When the power difference is less than or equal to zero, the output power of the photovoltaic array is limited by a series injection converter, including: When the power difference is less than or equal to zero, power limiting control is performed through the series injection converter to make the actual output power of the photovoltaic array less than the maximum output power of the photovoltaic array.

9. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor, when executing a program stored in the memory, implements the photovoltaic air conditioning system control method according to any one of claims 6-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the photovoltaic air conditioning system control method as described in any one of claims 6-8.

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