On / off-grid switching control method, power conversion system, and switch device

Abstract

An on / off-grid switching control method. During on / off-grid switching control, when detecting a mains power outage, a power conversion system sends a turn-off control signal to a switching device to control the switching device to disconnect a connection between the mains power and a load, and switches to an off-grid operation mode only when receiving a turn-off completion signal sent by the switching device. The turn-off completion signal and the turn-off control signal for on / off-grid switching control are level signals having different voltage amplitudes, or each comprises at least one of a pulse signal and an edge signal.

Description

[0001]Cross-Reference to Related Applications Regarding Control Methods, Power Conversion Devices, and Switching Devices for Off-Grid / Grid Switching This application claims priority to Chinese Patent Application No. 20241 1857254.5, filed on December 16, 2024, entitled "Control Methods, Power Conversion Devices, and Switching Devices for Off-Grid / Grid Switching," the entire contents of which are incorporated herein by reference. Technical Field This application belongs to the field of power electronics technology, and particularly relates to a control method, power conversion device, and switching device for off-grid / grid switching. Background Art The statements herein are provided only as background information in connection with this application and do not necessarily constitute exemplary technology. Currently, residential energy storage systems are developing rapidly. The power conversion system (PCS) of energy storage systems can be connected to the grid via switching devices such as distribution boxes, meter disconnect switches, or manual / main switching switches, or operate off-grid when the grid is without power, directly driving the load. It is not necessary to simultaneously possess the switching devices such as distribution boxes, meter disconnect switches, or manual / main switching switches. Traditional on-grid / off-grid switching methods, if the switching equipment fails to switch or fails to receive the feedback signal, will cause the PCS operating mode to deviate from the actual operation, potentially leading to power outages or even damage to the PCS. The present invention, according to various embodiments, provides a control method, power conversion device, and switching equipment for on-grid / off-grid switching. One embodiment of the present application provides a control method for on-grid / off-grid switching, applied to a power conversion device. The control method includes: when a mains power failure is detected, sending a shutdown control signal to the switching equipment; the switching equipment is connected between the mains power and the power conversion device, used to control the connection between the mains power and the power conversion device; the shutdown control signal is used to control the switching equipment to disconnect the connection between the mains power and the power conversion device; in response to a shutdown completion signal sent by the switching equipment, controlling the power conversion device to switch to off-grid operation mode; the shutdown completion signal and the shutdown control signal are both level signals with different voltage amplitudes, or the shutdown control signal includes at least one of pulse signals and edge signals. One embodiment of this application also provides a power conversion device, including a power conversion circuit, a memory, a processor, and a computer program stored in the memory and executable on the processor. The mains side of the power conversion device is connected to the mains power through a switching device. The switching device is used to control the on / off switching between the mains power and the power conversion device. When the processor executes the computer program, it implements the steps of the on / off grid switching control method described above.One embodiment of this application also provides a control method for grid-connected / off-grid switching, applied to a switching device. The control method includes: receiving a shutdown control signal sent by the power conversion device; the switching device is connected between the mains power supply and the power conversion device, and is used to control the on / off connection between the mains power supply and the power conversion device; controlling the switching device to disconnect the connection between the mains power supply and the power conversion device according to the shutdown control signal; after disconnecting the connection between the mains power supply and the conversion device, sending a shutdown completion signal to the power conversion device; the shutdown completion signal is used to indicate that the power conversion device switches to off-grid operation mode; the shutdown completion signal and the shutdown control signal are level signals with different voltage amplitudes, or the shutdown control signal and the shutdown completion signal include at least one of pulse signals and edge signals. Another embodiment of this application also provides a switching device, including a disconnection device, a memory, a processor, and a computer program stored in the memory and executable on the processor. The disconnection device is used to control the on / off connection between the mains power supply and the power conversion device; when the processor executes the computer program, it implements the steps of the grid-connected / off-grid switching control method as described in the third aspect. The accompanying drawings are provided to more clearly illustrate the technical solutions in the embodiments or exemplary technologies of this application. The drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort. Figure 1 is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application. Figure 2 is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application. Figure 3 is a flowchart of a control method for off-grid / parallel switching provided in an embodiment of this application. Figure 4 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 5 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 6 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 7 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 8 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 9 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 10 is a control circuit diagram for off-grid / parallel switching provided in an embodiment of this application. Figure 11 is a schematic diagram of the modules of a control device for off-grid / parallel switching provided in an embodiment of this application. Figure 12 is a schematic diagram of the power conversion device provided in an embodiment of this application. Figure 13 is a flowchart of the control method for grid-connected / off-grid switching provided in an embodiment of this application.Figure 14 is a schematic diagram of the structure of a switching device provided in an embodiment of this application. Detailed Description To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on or indirectly on that other element. When an element is referred to as "connected to" another element, it can be directly connected to or indirectly connected to that other element. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. Residential energy storage systems are now developing rapidly. The power conversion equipment of an energy storage system can be connected to the power grid via switching devices such as distribution boxes, meter disconnect switches, manual transfer switches, or automatic transfer switches, or operate offline when the grid is down. The distribution box contains a main relay, which controls the connection between the mains power and the load. The distribution box has an incoming mains power line and multiple load branches, distributing mains power to the loads on different branches. Meter disconnect switches typically have a structure that adapts to the meter socket and the meter. The meter disconnect switch connects the meter socket and the meter and can also be called a meter adapter. The meter disconnect switch contains a relay to control the connection between the mains power and the load. Automatic and manual transfer switches function similarly to distribution boxes, representing simplified versions of distribution boxes, and also contain transfer switches to control the connection between the mains power and the load. Therefore, the control of switching devices discussed later mainly refers to controlling the relays and other disconnecting devices within the switching devices used to control the connection between the mains power and the load. Referring to Figures 1 and 2, switching devices such as distribution boxes, meter disconnect switches, manual transfer switches, or automatic transfer switches do not need to be present simultaneously. When the energy storage system switches from grid-connected to off-grid operation, the power conversion equipment needs to send control signals to the switching equipment. Upon receiving the signal, the switching equipment immediately disconnects the corresponding internal relays to break the connection between the mains power and the load. The power conversion equipment can directly supply power to the load through the switching equipment, or directly to the load connected to itself.Power conversion equipment can also directly supply power to power distribution equipment, thereby enabling power supply to the load connected to the power distribution equipment. In traditional on-grid / off-grid switching methods, the on-grid / off-grid switching control signal and the feedback signal of the main relay switching completion are transmitted through a communication module. If the main relay switching fails, or the feedback signal reception fails, the operating mode of the power converter will not match the actual situation, which may cause a power outage to the load, or even damage to the PCS (Power Conversion System). In this regard, this application provides a reliable on-grid / off-grid switching control method. Referring to Figure 3, and combining Figures 1 and 2, the on-grid / off-grid switching control method can be applied to power conversion equipment. The control method includes: Step S110, when a mains power failure is detected, a shutdown control signal is sent to the switching equipment. The switching equipment is connected between the mains power and the load and is used to control the connection between the mains power and the load; the shutdown control signal is used to control the switching equipment to disconnect the connection between the mains power and the load. For example, the switching device can be a distribution box (see Figure 1) or a meter disconnect switch (see Figure 2). The switching device includes a disconnection device connected to the mains power and the load, which can be a relay or a disconnect switch. The power conversion device is an electrical device including a power conversion circuit. The power conversion device detects the mains power status and, when a mains power failure is detected, sends a shutdown control signal to the switching device, causing the switching device to control the disconnection device to disconnect the connection between the mains power and the load. In step S120, in response to the shutdown completion signal sent by the switching device, the power conversion device is controlled to switch to off-grid operation mode; the shutdown completion signal and the shutdown control signal are level signals with different voltage amplitudes, or the shutdown control signal and the shutdown completion signal contain at least one of pulse signals and edge signals. In this embodiment, after receiving the shutdown control signal and successfully disconnecting the connection between the mains power and the load, the switching device returns a shutdown completion signal. The power conversion device switches to off-grid operation mode only after receiving the shutdown completion signal from the switching device. This ensures that the operating mode of the power conversion device matches the actual situation, preventing power outages to the load or even damage to the power conversion device. In one embodiment, the shutdown completion signal and the shutdown control signal are voltage level signals with different amplitudes. For example, the shutdown completion signal is a 0V level signal, and the shutdown control signal is a 12V level signal, or vice versa. It is understood that the specific voltage amplitudes of the shutdown completion signal and the shutdown control signal can be selected as needed and are not limited to the examples above. Examples are also provided in later embodiments.In one embodiment, the shutdown control signal and the shutdown completion signal include at least one of pulse signals and edge signals. For example, both the shutdown control signal and the shutdown completion signal are pulse signals, or both are edge signals. Alternatively, the shutdown control signal and the shutdown completion signal may simultaneously contain pulse information and edge signals. Using level signals with different voltage amplitudes for the shutdown completion signal and the shutdown control signal, or having the shutdown control signal and the shutdown completion signal include at least one of pulse signals and edge signals, allows the system to identify the difference between the shutdown completion signal and the shutdown control signal, improving the reliability of grid-connected switching control. Transmitting the shutdown completion signal and the shutdown control signal through level signals and / or edge signals offers higher signal transmission reliability compared to signal transmission through a communication module, thereby avoiding grid-connected switching failures due to signal transmission failures, which could lead to load power loss or even damage to the power conversion equipment. In some embodiments, step S120, controlling the power conversion device to switch to off-grid operation mode, includes: controlling the power conversion device to switch from current source mode to voltage source mode. When connected to the grid, the power grid typically provides a stable voltage, and the power conversion device needs to match the grid voltage for safe grid connection. The power conversion device adjusts the current to adapt to voltage fluctuations in the grid, ensuring smooth power input or output; that is, it needs to operate in current source mode. In off-grid mode, the power conversion device provides a stable voltage to the load (such as household appliances or independent loads) to ensure normal power supply. Therefore, the output voltage of the power conversion device needs to remain stable, while the current is adjusted according to load demand; that is, it needs to operate in voltage source mode. Referring to Figures 4 and 5, in some embodiments, the power conversion device and the switching device are connected via a first power line to provide a first operating voltage to the switching device. The first operating voltage serves as the operating voltage of the switching device to ensure its normal operation. For example, the power conversion device is wiredly connected to the second interface J2 of the switching device via a first interface J1. The first interface J1 and the second interface J2 are equipped with terminals for a 12V power line, a ground line GND, a first communication line GANH, and a second communication line GANL. The first power line is a 12V power line. The control method for off-grid / parallel switching further includes: sending a shutdown control signal to the switching equipment via the first power line, and receiving a shutdown completion signal via the first power line. That is, in this embodiment, the control signal used for off-grid / parallel switching is multiplexed and transmitted via the power line, which has the advantages of simple implementation and low cost.Furthermore, communication for grid-connected switching is achieved via hard-wired power lines, resulting in faster communication speeds and effectively improving the switching speed. The power conversion device only performs the final grid-connected switching upon receiving a shutdown completion signal from the switching equipment, ensuring accurate switching. Please refer to Figure 4, which shows one possible circuit diagram for implementing the above scheme. The voltage output circuit 110 of the power conversion device includes two anti-reverse diodes D1 and D2, a BOOST circuit 120, a MOSFET Q1, and an amplifier U1 for voltage detection. The voltage input circuit 210 of the switching equipment includes an input protection diode D3, an anti-reverse diode D4, a MOSFET Q2, and an amplifier U2 for voltage detection. During normal communication between the power conversion device and the switching equipment, the MOSFET Q1 is in the off state. The 12V power supply is output to the switching equipment via the anti-reverse diode D1. The 12V power supply is detected by the amplifier U2 in the voltage detection circuit within the switching equipment. When the switching equipment detects a 12V signal, it will not perform grid disconnection / off operation. At this time, MOSFET Q2 is in the off state. When the power conversion equipment needs to disconnect from the grid, the first controller of the power conversion equipment controls the switching frequency of MOSFET Q1, thereby using the BOOST circuit 120 to generate an 18V pulse signal (i.e., a turn-off control signal) on the first power line, which is then superimposed on the 12V power supply and output to the switching equipment. After the amplifier U2 of the switching equipment detects the 18V pulse signal, the second controller of the switching equipment controls the disconnection device 211 to open, and after the disconnection is completed, controls the on / off state of MOSFET Q2, thereby generating a 24V-30V pulse signal (i.e., a turn-off completion signal) on the first power line where MOSFET Q2 is located, which is superimposed on the 12V signal voltage and transmitted to the power conversion equipment. The first controller of the power conversion device can also perform voltage detection through amplifier U1. After detecting a 24V-30V pulse signal, it confirms and completes the off-grid conversion, then switches from current source mode to voltage source mode, i.e., enters off-grid operation mode. Please refer to Figure 5, which is another circuit diagram for implementing the above scheme. The voltage output circuit 110 of the power conversion device includes a reverse protection diode D5, a MOSFET Q3, and an amplifier U3 used for voltage detection. The voltage input circuit 210 of the switching device includes an input protection diode D6, a switching MOSFET Q4, and an amplifier U4 used for voltage detection. When the power conversion device and the switching device are communicating normally, the MOSFET Q3 is in the off state.The 12V power supply is output to the switching equipment via the anti-reverse diode D5. The 12V power supply is detected by amplifier U4 within the switching equipment. When the switching equipment detects the 12V signal, it will not perform grid disconnection / off-grid operation. At this time, MOSFET Q4 is in the off state. When the power conversion equipment needs to disconnect from the grid, the first controller of the power conversion equipment controls MOSFET Q3 to turn on, thereby briefly pulling the 12V power supply output to 0V, generating a 0V pulse signal (including a falling edge signal), which is the shutdown control signal. After amplifier U4 of the switching equipment detects the 0V pulse signal, the second controller of the switching equipment controls the disconnection device 211 to disconnect, and after the disconnection is completed, controls MOSFET Q4 to briefly turn on, thereby briefly dropping the 12V voltage to 0V, generating a 0V pulse signal (including a falling edge signal), which is the shutdown completion signal, transmitted to the power conversion equipment. The first controller of the power conversion device can also perform voltage detection through amplifier U3. After detecting a 0V pulse signal or falling edge signal, it confirms and completes the off-grid conversion, and then switches from current source mode to voltage source mode, that is, enters off-grid operation mode. Referring to Figures 6 and 7, the power conversion device is connected to the switching device via a first power line to provide the first operating voltage to the switching device. The power conversion device is also connected to the switching device via a first transmit data line and a first receive data line. For example, the power conversion device is wired to the second interface J2 of the switching device via a first interface J1. The first interface J1 and the second interface J2 are provided with terminals for a 12V power supply line, ground line GND, a first communication line GANH, a second communication line GANL, a first transmit data line PIN1, and a first receive data line PIN2. The first power line is a 12V power supply line, and the first transmit data line PIN1 and the first receive data line PIN2 are independently configured lines. The control method for switching between grid-connected and off-grid also includes: sending a shutdown control signal through the first transmit data line PIN1 and receiving a shutdown completion signal through the first receive data line PIN2. Please refer to Figure 6, which is a circuit diagram of one implementation of the above scheme. When there is no trigger signal (i.e., no shutdown control signal and no shutdown completion signal), the first transmit data line PIN1 and the first receive data line PIN2 are at a potential of 0V. Specifically, the voltage output circuit 110 on the power conversion device side includes two anti-reverse diodes D7 and D8, a PMOS transistor Q5, and an amplifier U5 used for voltage detection.The voltage input circuit 210 on the switching equipment side includes an input protection diode D9, a reverse protection diode DIO, a PMOS transistor Q6, and an amplifier U6 for voltage detection. During normal communication between the power conversion device and the switching equipment, the PMOS transistor Q5 is in the off state. When the switching equipment detects a 0V signal, it will not perform grid disconnection / off operation. At this time, the PMOS transistor Q6 is in the off state. When the power conversion device needs to disconnect from the grid, the first controller of the power conversion device controls the short-term opening of the PMOS transistor Q5, thereby generating a 12V pulse signal or rising edge signal (i.e., a turn-off control signal) on the first transmit data line PIN1 and outputting it to the switching equipment. After the second controller of the switching equipment detects a 12V pulse signal or rising edge signal through amplifier U6, it controls the disconnection device 211 to disconnect. After the disconnection device 211 completes disconnection, it controls the switching of PMOS transistor Q6, thereby generating a 12V pulse signal or rising edge signal (i.e., a turn-off completion signal) on the first receive data line PIN2 where PMOS transistor Q6 is located, and transmitting it to the power conversion device. The first controller of the power conversion device can also perform voltage detection through amplifier U5. After detecting a 12V pulse signal or rising edge signal, it confirms and completes the off-grid conversion, and then switches from current source mode to voltage source mode, that is, enters off-grid operation mode. Please refer to Figure 7, which is a circuit diagram of one of the above schemes. When there is no trigger signal (i.e., no disconnection control signal and turn-off completion signal), the first transmit data line PINK and the first receive data line PIN2 are at a potential of 12V. Specifically, the voltage output circuit 110 on the power conversion device side includes a reverse protection diode D11, a current-limiting resistor R4, an NMOS transistor Q7, and an amplifier U7 used for voltage detection. The voltage input circuit 210 on the switching device side includes an input protection diode D12, a current-limiting resistor R5, an NMOS transistor Q8, and an amplifier U8 used for voltage detection. When the power conversion device and the switching device are communicating normally, the NMOS transistor Q7 is in the off state. When the switching device detects a 12V power supply signal, it will not perform grid disconnection / off operation. At this time, the NMOS transistor Q8 is in the off state. When the power conversion device needs to disconnect from the grid, the first controller of the power conversion device controls the short-term opening of the NMOS transistor Q7, thereby generating a 0V pulse signal or a falling edge signal (i.e., a shutdown control signal) on the first transmit data line PIN1 and outputting it to the switching device.After the second controller of the switching equipment detects a 0V pulse signal or falling edge signal through amplifier U8, it controls the disconnection device 211 to disconnect. Upon completion of the disconnection, it controls the switching on and off of NMOS transistor Q8, thereby generating a 0V pulse signal or falling edge signal (i.e., a turn-off completion signal) on the first receive data line PIN2 where NMOS transistor Q8 is located and transmitting it to the power conversion device. Similarly, the first controller of the power conversion device can perform voltage detection through amplifier U7. Upon detecting a 0V pulse signal or falling edge signal, it confirms and completes the off-grid conversion, then switches from current source mode to voltage source mode, i.e., enters off-grid operation mode. Referring to Figures 8 and 9, the power conversion device is connected to the switching equipment through a first power line to provide a first operating voltage to the switching equipment. The power conversion device is also connected to the switching equipment through a first transmit / receive data line. For example, the power conversion device is wiredly connected to the second interface J2 of the switching equipment through the first interface J1. The first interface J1 and the second interface J2 are equipped with terminals for a 12V power supply line, ground line GND, first communication line GANH, second communication line GANL, and first transceiver data line PIN11. The first power line is a 12V power supply line, and the first transceiver data line PIN11 is an independently configured line. The control method for switching between grid connection and off-grid connection also includes: sending a shutdown control signal through the first transceiver data line PIN11, and receiving a shutdown completion signal through the first transceiver data line PIN11. Please refer to Figure 8, which is a circuit diagram of one implementation of the above scheme. When there is no trigger signal (i.e., no shutdown control signal and shutdown completion signal), the first transceiver data line PIN11 is at a 0V potential. Specifically, the voltage output circuit 110 on the power conversion device side includes two anti-reverse diodes D13 and D24, a PMOS transistor Q9, and an amplifier U9 used for voltage detection. The voltage input circuit 210 on the switching equipment side includes an input protection diode D14, a reverse protection diode D15, a PMOS transistor Q10, and an amplifier U10 for voltage detection. During normal communication between the power conversion device and the switching equipment, the PMOS transistor Q9 is in the off state. When the switching equipment detects a 0V signal, it will not perform grid disconnection / off-grid operation. At this time, the PMOS transistor Q10 is in the off state. When the power conversion device needs to disconnect from the grid, the first controller of the power conversion device controls the short-term opening of the PMOS transistor Q9, thereby generating a 12V pulse signal (including the rising edge signal) on the first transmit / receive data line PIN11, i.e., a shutdown control signal, which is output to the switching equipment.After the second controller of the switching equipment detects a 12V pulse signal or rising edge signal through amplifier U10, it controls the disconnection device 211 to disconnect. After disconnection device 211 completes disconnection, it controls the switching of PMOS transistor Q10, thereby generating a 12V pulse signal (including a rising edge signal) on the first transmit / receive data line PIN11 where PMOS transistor Q10 is located, i.e., a shutdown completion signal, which is transmitted to the power conversion device. The first controller of the power conversion device can also perform voltage detection through amplifier U9. After detecting a 12V pulse signal or rising edge signal, it confirms and completes the off-grid conversion, then switches from current source mode to voltage source mode, i.e., enters off-grid operation mode. Please refer to Figure 9, which is a circuit diagram of one implementation of the above scheme. When there is no trigger signal (i.e., no shutdown control signal and shutdown completion signal), the first transmit / receive data line PIN11 is at a 12V potential. Specifically, the voltage output circuit 110 on the power conversion device side includes a reverse protection diode D16, a current-limiting resistor R6, an NMOS transistor Q11, and an amplifier U11 for voltage detection. The voltage input circuit 210 on the switching device side includes an input protection diode D17, a current-limiting resistor R7, an NMOS transistor Q12, and an amplifier U12 for voltage detection. When the power conversion device and the switching device are communicating normally, the NMOS transistor Q11 is in the off state. When the switching device detects a 12V signal, it will not perform grid disconnection / off operation. At this time, the NMOS transistor Q12 is in the off state. When the power conversion device needs to disconnect from the grid, the first controller of the power conversion device controls the NMOS transistor Q11 to briefly turn on, thereby generating a 0V pulse signal (including a falling edge signal) on the first transmit / receive data line PIN11, i.e., a shutdown control signal, which is output to the switching device. After detecting a 0V pulse signal via amplifier U12, the second controller of the switching equipment controls the disconnection device 211 to disconnect. After disconnection device 211 completes disconnection, it controls the switching of NMOS transistor Q12, thereby generating a 0V pulse signal (including a falling edge signal) on the first transmit / receive data line PIN11 where NMOS transistor Q12 is located, i.e., a shutdown completion signal, which is transmitted to the power conversion device. The first controller of the power conversion device can also perform voltage detection via amplifier U11. Upon detecting a 0V pulse signal or a falling edge signal, it confirms and completes the off-grid conversion, then switches from current source mode to voltage source mode, i.e., enters off-grid operation mode.Referring to Figure 10, the power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device. The power conversion device is also connected to the switching device via a first transmit / receive data line and a second transmit / receive data line. For example, the power conversion device is wired to the second interface J2 of the switching device via a first interface J1. The first interface J1 and the second interface J2 are provided with terminals for a 12V power supply line, a ground line GND, a first transmit / receive data line PIN11, and a second transmit / receive data line PIN12. The first power line is a 12V power supply line, and the first transmit / receive data line PIN11 and the second transmit / receive data line PIN12 are independently configured lines. The control method for switching between on-grid and off-grid connections also includes: sending a shutdown control signal via the first transceiver data line PIN11 or the second transceiver data line PIN12, and receiving a shutdown completion signal via the first transceiver data line PIN11 or the second transceiver data line PIN12. Figure 10 shows one circuit scheme for implementing the above scheme. The working logic is the same as the schemes in Figures 8 and 9, except that the scheme shown in Figure 10 has one more line prepared compared to the schemes in Figures 8 or 9. The circuit logic is also similar and will not be described in detail here. It can be understood that in the dual-line scheme shown in Figure 10, the two lines can be used alternately, or one can be used first and then switched to the other after a fault. Referring to Figure 11, this application embodiment also provides a control device for switching between on-grid and off-grid connections. The control device includes a transceiver module 1101 and a control module 1102. The transceiver module 1101 is used to send a shutdown control signal to the switching equipment when a mains power failure is detected. The switching equipment is connected between the mains power and the load and is used to control the connection and disconnection between the mains power and the load. The shutdown control signal is used to control the switching equipment to disconnect the connection between the mains power and the load. Control module 1102 is used to control the power conversion equipment to switch to off-grid operation mode in response to a shutdown completion signal sent by the switching equipment. The shutdown completion signal and the shutdown control signal are level signals with different voltage amplitudes, or both the shutdown control signal and the shutdown completion signal include at least one of a pulse signal and an edge signal. In some embodiments, control module 1102 is specifically used to control the power conversion equipment to switch from current source mode to voltage source mode operation. In some embodiments, the power conversion equipment and the switching equipment are connected via a first power line to provide a first operating voltage to the switching equipment via the first power line; transceiver module 1101 is specifically used to send the shutdown control signal to the switching equipment via the first power line and to receive the shutdown completion signal via the first power line.In some embodiments, the power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit data line and a first receive data line; the transceiver module 1101 is specifically used to transmit a shutdown control signal via the first transmit data line and receive a shutdown completion signal via the first receive data line. In some embodiments, the power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit / receive data line; the transceiver module 1101 is specifically used to transmit a shutdown control signal via the first transmit / receive data line and receive a shutdown completion signal via the first transmit / receive data line. In some embodiments, the shutdown control signal is an edge signal; the shutdown completion signal is a pulse signal. In some embodiments, the power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit / receive data line and a second transmit / receive data line respectively; the transceiver module 1101 is specifically used to send a shutdown control signal via the first transmit / receive data line or the second transmit / receive data line, and to receive a shutdown completion signal via the first transmit / receive data line or the second transmit / receive data line. For a detailed description of the specific implementation and related beneficial effects of the on-grid / off-grid switching control device, please refer to the description of the specific embodiments of the control method described above, which will not be repeated here. Referring to Figure 12, this application embodiment also provides a power conversion device 100, including a power conversion circuit 111, a memory 112, a processor 113, and a computer program 114 stored in the memory 112 and executable on the processor 113. The mains power side of the power conversion device 100 is connected to the mains power via a switching device 200. The switching device 200 is used to control the on / off connection between the mains power and the power conversion device 100. When processor 113 executes computer program 114, it implements the steps of the on-grid / off-grid switching control method as described in any of the above embodiments. Referring to Figures 12 and 13, this application embodiment also provides an on-grid / off-grid switching control method applied to a switching device 200. The control method includes: Step S210, receiving a shutdown control signal sent by a power conversion device. The switching device 200 is connected between the mains power supply and the power conversion device 100, and is used to control the on / off connection between the mains power supply and the power conversion device 100; The switching device 200 is controlled to disconnect the connection between the mains power supply and the power conversion device 100 according to the shutdown control signal.Step S220: After disconnecting the mains power from the conversion device, a shutdown completion signal is sent to the power conversion device. The shutdown completion signal instructs the power conversion device 100 to switch to off-grid operation mode. The shutdown completion signal and the shutdown control signal have different voltage amplitudes, or the shutdown control signal and the shutdown completion signal include at least one of pulse signals and edge signals. It is understood that the control method for off-grid switching applied to the switchgear 200 in this embodiment can be adapted to the control method for off-grid switching applied to the power conversion device 100 in any of the previous embodiments. In this embodiment, during the off-grid switching process, the switchgear 200 sends a switching success signal to the power conversion device 100 only after confirming successful off-grid switching, ensuring that the operating mode of the power conversion device 100 matches the actual operation and preventing power outages or even damage to the power conversion device. Referring to Figure 14, this application embodiment also provides a switching device 200, including a disconnection device 211, a memory 212, a processor 213, and a computer program 214 stored in the memory 212 and executable on the processor 213. The disconnection device 211 is used to control the connection and disconnection between the mains power and the power conversion device 100. When the processor 213 executes the computer program 214, it implements the steps of the control method for on / off grid switching applied to the switching device 200. This application embodiment also provides a power system including the aforementioned power conversion device 100 and / or the aforementioned switching device 200. It is understood that the aforementioned power conversion device 100 can be a single power device, a battery pack with battery modules, or an energy storage device including multiple battery packs with battery modules. Those skilled in the art will understand that Figure 12 is merely an example of the power conversion device 100 and does not constitute a limitation on the power conversion device 100. It may include more or fewer components than shown, or combine certain components, or different components, such as input / output devices, network access devices, etc.Additionally, processor 113 / 213 can be a central processing unit (CPU), or it can be other general-purpose controllers, 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, discrete hardware components, etc. The general-purpose controller can be a microcontroller or any conventional controller. In some embodiments, memory 112 / 212 can be an internal storage unit of the power conversion device 100 or the switching device 200, such as a hard disk or RAM of the power conversion device 100 or the switching device 200. In other embodiments, memory 112 / 212 may also be an external storage device for the power conversion device 100 or the switching device 200, such as a pluggable hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the power conversion device 100 or the switching device 200. Further, memory 112 / 212 may include both internal storage units of the power conversion device 100 or the switching device 200 and external storage devices. Memory 112 / 212 is used to store operating systems, applications, boot loaders, data, and other programs. Memory 112 / 212 can also be used to temporarily store data that has been output or will be output. Embodiments of this application also provide a computer program product, including computer program 114 / 214, which, when run, causes the aforementioned on / off-grid switching control method to be executed. It should be understood that all or part of the steps of the above embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented in whole or in part as a computer program 114 / 214 product. The computer program 114 / 214 product includes one or more computer instructions. The computer instructions can be stored in the above-described computer-readable storage medium.In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

Claims 1. A control method for switching between grid-connected and off-grid operation, applied to a power conversion device, the control method comprising: when a mains power failure is detected, sending a shutdown control signal to a switching device; the switching device being connected between the mains power and a load, used to control the connection between the mains power and the load; the shutdown control signal being used to control the switching device to disconnect the connection between the mains power and the load; and, in response to a shutdown completion signal sent by the switching device, controlling the power conversion device to switch to off-grid operation mode; the shutdown completion signal and the shutdown control signal being level signals with different voltage amplitudes, or the shutdown control signal and the shutdown completion signal including at least one of a pulse signal and an edge signal.

2. The control method according to claim 1, wherein The module for controlling the power conversion device to switch to off-grid operation includes: controlling the power conversion device to switch from current source mode to voltage source mode.

3. The control method according to claim 1, wherein, The power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the method further includes: sending the shutdown control signal to the switching device via the first power line, and receiving the shutdown completion signal via the first power line.

4. The control method according to claim 1, wherein The power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit data line and a first receive data line; the method further includes: transmitting the shutdown control signal via the first transmit data line and receiving the shutdown completion signal via the first receive data line.

5. The control method as described in claim 1, wherein, The power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit / receive data line; the method further includes: The shutdown control signal is transmitted through the first transmit / receive data line, and the shutdown completion signal is received through the first transmit / receive data line.

6. The control method as described in claim 5, wherein, The shutdown control signal is an edge signal; the shutdown completion signal is a pulse signal.

7. The control method as described in claim 1, wherein, The power conversion device is connected to the switching device via a first power line to provide a first operating voltage to the switching device via the first power line; the power conversion device is also connected to the switching device via a first transmit / receive data line and a second transmit / receive data line; the method further includes: sending the shutdown control signal via the first transmit / receive data line or the second transmit / receive data line, and receiving the shutdown completion signal via the first transmit / receive data line or the second transmit / receive data line.

8. A power conversion device, comprising a power conversion circuit, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the mains side of the power conversion device is connected to the mains power via a switching device; the switching device is used to control the on / off connection between the mains power and the power conversion device; and the processor, when executing the computer program, implements the steps of the on / off grid switching control method as described in any one of claims 1 to 5.

9. The power conversion device as described in claim 8, wherein, The shutdown control signal is an edge signal; the shutdown completion signal is a pulse signal.

10. A control method for switching between grid-connected and off-grid environments, applied to switchgear, the control method comprising: Receive the shutdown control signal sent by the power conversion device; The switching device is connected between the mains power and the power conversion device, and is used to control the on / off connection between the mains power and the power conversion device; The switching device is controlled to disconnect the connection between the mains power and the power conversion device according to the shutdown control signal; after disconnecting the connection between the mains power and the conversion device, a shutdown completion signal is sent to the power conversion device; The shutdown completion signal is used to indicate that the power conversion device switches to off-grid operation mode; the shutdown completion signal and the shutdown control signal are level signals with different voltage amplitudes, or the shutdown control signal and the shutdown completion signal include at least one of pulse signals and edge signals.

11. The control method as described in claim 10, wherein, The shutdown control signal is an edge signal; the shutdown completion signal is a pulse signal.

12. A switching device, comprising a disconnecting device, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the disconnecting device is used to control the switching between the mains power supply and the power conversion device; and the processor, when executing the computer program, implements the steps of the on / off grid switching control method as described in claim 10 or 11. 17

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