Relay driving circuit and power supply system

Abstract

Disclosed in the present disclosure are a relay driving circuit and a power supply system. The circuit (100) comprises: a master driving circuit (10); a slave driving circuit (20); a detection circuit (30) used for detecting the state of a main contact of a relay to obtain a state detection signal; a master controller (40) used for controlling, when it is determined that the state detection signal is abnormal, a direct current circuit (200) to stop working, and controlling, after a delay of a first preset time, the master driving circuit (10) to drive the main contact of the relay to be disconnected; and a slave controller (50) used for controlling, when a first relay disconnection instruction output when the master controller (40) is abnormal is received or when it is determined that the state detection signal is abnormal, the direct current circuit (200) to stop working, and controlling, after the delay of the first preset time, the slave driving circuit (20) to drive the main contact of the relay to be disconnected.

Description

Relay drive circuit and power supply system

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese patent application No. 2024106842401, filed on May 29, 2024, entitled “Relay Drive Circuit and Power Supply System”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of power supply system technology, and in particular to a relay drive circuit and a power supply system. Background Technology

[0004] In an energy storage system, if the voltage of the battery in the system is higher than the bus voltage, a large inrush current will be generated in the battery circuit when the battery voltage is connected to the battery side port of the photovoltaic energy storage inverter of the energy storage system, which is not conducive to operational safety.

[0005] In related technologies, a technical solution involves connecting a cement resistor or thermistor in series with the battery circuit and a relay in parallel across the cement resistor or thermistor circuit. This improves operational safety by controlling the closing and opening of the relay's main contacts. However, the relays used in this solution lack arc-extinguishing capabilities. When the relay's main contacts interrupt a large load current, it may damage or destroy the cement resistor or thermistor, or even the relay itself.

[0006] Public content

[0007] This disclosure aims to at least partially address one of the technical problems in the related art. Therefore, the first objective of this disclosure is to provide a relay drive circuit.

[0008] The second objective of this disclosure is to propose a power supply system.

[0009] To achieve the above objectives, a first aspect of this disclosure provides a relay driving circuit applied to a power supply system. The power supply system includes a DC circuit, and the main contacts of the relay are connected in series in the DC circuit. The relay driving circuit includes: a main driving circuit connected to one end of the relay coil for driving the relay; a slave driving circuit connected to one end of the relay coil for driving the relay; a detection circuit for detecting the state of the relay's main contacts to obtain a state detection signal; a main controller connected to both the main driving circuit and the detection circuit, for controlling the DC circuit to stop working when the state detection signal is abnormal, and controlling the main driving circuit to drive the relay's main contacts to open after a first preset time delay; and a slave controller connected to both the slave driving circuit and the detection circuit, and communicating with the main controller, for receiving a first relay disconnect command output by the main controller when it is abnormal, or controlling the DC circuit to stop working when the state detection signal is abnormal, and controlling the slave driving circuit to drive the relay's main contacts to open after a first preset time delay.

[0010] In addition, the relay drive circuit according to the above embodiments of this disclosure may also have the following additional technical features:

[0011] According to one embodiment of this disclosure, the main controller is further configured to respond to a stop operation command of the DC circuit, control the DC circuit to stop operating, and after a first preset time delay, control the main drive circuit to drive the main contacts of the relay to open, and send a second relay disconnect command to the slave controller, so that the slave controller controls the slave drive circuit to drive the main contacts of the relay to open based on the second relay disconnect command.

[0012] According to one embodiment of this disclosure, the main controller is further configured to respond to the operating command of the DC circuit, and when the status detection signal is normal, send a relay closing command to the slave controller; the slave controller is further configured to control the slave drive circuit to drive the main contacts of the relay to close based on the relay closing command, and acquire the status detection signal after a second preset time delay, and send a status normal feedback signal to the main controller when the status detection signal is normal; the main controller is further configured to control the main drive circuit to drive the main contacts of the relay to close based on the status normal feedback signal, acquire the status detection signal after a second preset time delay, and control the DC circuit to operate when the status detection signal is normal.

[0013] According to one embodiment of this disclosure, the master controller and the slave controller are further configured to respond to a self-test command before the DC circuit operates, respectively control the corresponding drive circuit to drive the main contacts of the relay to close first and then open, and acquire the status detection signals when closing and opening, and determine whether the corresponding drive circuit, detection circuit and relay are normal based on the status detection signals when closing and opening; wherein, the slave controller is further configured to send the determination result to the master controller.

[0014] According to one embodiment of this disclosure, the master controller and slave controller are further configured to, in response to a self-test command before the DC circuit operates, simultaneously control the corresponding drive circuit to drive the main contacts of the relay to close, and after a second preset time delay, one of the master controller and slave controller controls the corresponding drive circuit to drive the main contacts of the relay to open, while the other controller acquires a status detection signal and determines whether the corresponding drive circuit, detection circuit, and relay are normal based on the status detection signal; if the corresponding drive circuit, detection circuit, and relay are all normal, then simultaneously control the corresponding drive circuit to drive the main contacts of the relay to close, and after a second preset time delay, the other controller controls the corresponding drive circuit to drive the main contacts of the relay to open, while one controller acquires a status detection signal and determines whether the corresponding drive circuit, detection circuit, and relay are normal based on the status detection signal.

[0015] According to one embodiment of this disclosure, the driving circuit further includes: a first power supply circuit, which is connected to the first power supply and the other end of the relay coil, respectively, for providing a first voltage to the other end of the relay coil; and a second power supply circuit, which is connected to the first power supply and the other end of the relay coil, respectively, for providing the first voltage to the other end of the relay coil.

[0016] According to one embodiment of this disclosure, the first power supply circuit and the second power supply circuit have the same circuit structure. The first power supply circuit includes: a first diode, the anode of which is connected to a first power supply; a second diode, the anode of which is connected to the cathode of the first diode, and the cathode of the second diode is connected to the other end of the coil of a relay; and a first capacitor, which is connected in series between the anode of the second diode and a first ground terminal.

[0017] According to one embodiment of this disclosure, the detection circuit includes: a state detection circuit for detecting the state of an auxiliary contact of a relay, wherein the state of the auxiliary contact is used to characterize the state of the main contact; and / or a voltage detection circuit for detecting a first voltage at one end of the main contact of the relay and a second voltage at the other end of the main contact of the relay, wherein the voltage difference between the first voltage and the second voltage is used to characterize the closed or open state of the main contact of the relay.

[0018] According to one embodiment of this disclosure, when the detection circuit includes a state detection circuit, if the state of the auxiliary contact is consistent with the control signal of the relay, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal. When the detection circuit includes a voltage detection circuit, if the voltage difference is consistent with the control signal of the relay, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal. When the detection circuit includes both a state detection circuit and a voltage detection circuit, if both the state of the auxiliary contact and the voltage difference are consistent with the control signal of the relay, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal.

[0019] According to one embodiment of this disclosure, the state detection circuit includes: a first resistor and a second resistor, one end of the first resistor being connected to one end of an auxiliary contact of a relay, and the other end of the first resistor being connected to a master controller and a slave controller respectively, and the second resistor being connected in series between the other end of the first resistor and a second ground terminal, wherein the other end of the auxiliary contact of the relay is connected to a second power supply; or, a third resistor, a fourth resistor, and a second capacitor, one end of the third resistor being connected to one end of an auxiliary contact of a relay, and the other end of the third resistor being connected to a third power supply, one end of the fourth resistor being connected to one end of the third resistor, and the other end of the fourth resistor being connected to a master controller and a slave controller respectively, and the second capacitor being connected in series between the other end of the fourth resistor and a third ground terminal, wherein the other end of the auxiliary contact of the relay is connected to a fourth ground terminal.

[0020] According to one embodiment of this disclosure, the voltage detection circuit includes: a first differential circuit, the input terminals of which are respectively connected to one end of the main contact of a relay and one end of a DC power supply in a DC circuit, and the output terminals of which are respectively connected to a master controller and a slave controller, for detecting a first voltage; and a second differential circuit, the input terminals of which are respectively connected to the other end of the main contact of a relay and one end of a DC power supply, and the output terminals of which are respectively connected to the master controller and the slave controller, for detecting a second voltage; wherein the other end of the DC power supply is connected to one end of the main contact of the relay.

[0021] According to one embodiment of this disclosure, the main drive circuit and the slave drive circuit have the same circuit structure. The main drive circuit includes: a first drive buffer connected to the main controller for amplifying the control signal of the main controller; a first switch transistor, the first end of which is connected to the first drive buffer, the second end of which is connected to one end of the coil of a relay, and the third end of which is connected to a fifth ground terminal.

[0022] To achieve the above objectives, a second aspect of this disclosure provides a power supply system including the relay drive circuit described above.

[0023] In addition, the relay drive circuit according to the above embodiments of this disclosure may also have the following additional technical features:

[0024] According to one embodiment of this disclosure, the power supply system is a photovoltaic-storage inverter.

[0025] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0026] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein:

[0027] Figure 1 is a connection diagram of a relay drive circuit according to an embodiment of the present disclosure;

[0028] Figure 2 is a circuit diagram of a DC circuit according to a specific embodiment of the present disclosure;

[0029] Figure 3 is a connection diagram of a relay drive circuit according to an embodiment of the present disclosure;

[0030] Figure 4 is a circuit diagram of a first power supply circuit according to a specific embodiment of the present disclosure;

[0031] Figure 5 is a circuit diagram of a state detection circuit according to a specific embodiment of the present disclosure;

[0032] Figure 6 is a circuit diagram of a state detection circuit according to another specific embodiment of the present disclosure;

[0033] Figure 7 is a circuit diagram of a voltage detection circuit according to a specific embodiment of the present disclosure;

[0034] Figure 8 is a circuit diagram of a master drive circuit and a slave drive circuit according to a specific embodiment of the present disclosure;

[0035] Figure 9 is a block diagram of a power supply system according to an embodiment of the present disclosure. Detailed Implementation

[0036] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0037] The relay drive circuit and power supply system proposed in the embodiments of this disclosure are described below with reference to the accompanying drawings.

[0038] In a photovoltaic energy storage system, based on a photovoltaic energy storage inverter, photovoltaics and the grid can charge the batteries in the photovoltaic energy storage system, and the batteries in the photovoltaic energy storage system can also discharge to the load or the grid.

[0039] When the battery voltage is higher than the DC bus voltage, the relevant technologies adopt a technical solution of inserting a cement resistor or thermistor in series in the battery circuit and connecting a relay in parallel across the resistor, or inserting a cement resistor or thermistor in series in the battery circuit, adding a thermal fuse in series in the cement resistor or thermistor circuit, and connecting a relay in parallel across the resistor.

[0040] In the above technical solution, when the battery voltage is connected to the battery side port of the photovoltaic energy storage inverter, the battery pre-charges the DC bus capacitor through a resistor. Due to the current-limiting effect of the resistor, a large inrush current will not be generated in the battery circuit, ensuring the safety of the DC bus capacitor and semiconductor devices in the battery circuit. When the DC bus capacitor voltage equals the battery port voltage, the main contacts of the relay are closed to bypass the cement or thermistor, reducing the loss and heat generation of the cement or thermistor during battery discharge or charging.

[0041] However, some existing photovoltaic energy storage inverter products use relays in the battery-side circuit that do not have the ability to cut off DC current, i.e., they do not have arc-extinguishing capability. Therefore, when a single fault occurs in the relay drive circuit (a single fault refers to a fault in only one part of the circuit, either hardware or software, according to safety certification standards), the relay's main contacts will accidentally open. At this time, the load current in the battery circuit is large. The relay's main contacts cutting off the large load current will cause the cement or thermistor to flow with a large load current, which will lead to damage or failure of the cement, thermistor, or thermal fuse. The relay may also be damaged or failed.

[0042] To address the aforementioned technical problems, this application proposes a relay driving circuit. This circuit includes a main driving circuit and a slave driving circuit connected to one end of the relay coil, both capable of driving the relay. Simultaneously, a detection circuit detects the state of the relay's main contacts to obtain a state detection signal. During DC circuit operation, when the main controller determines an abnormal state detection signal, it first stops the DC circuit and, after a first preset time delay, controls the main driving circuit to open the relay's main contacts. Similarly, when the slave controller receives a first relay disconnect command from the main controller or determines an abnormal state detection signal, it stops the DC circuit and, after a first preset time delay, controls the slave driving circuit to open the relay's main contacts. Therefore, this circuit, based on a redundant drive design, prevents the relay's main contacts from immediately disconnecting when one of the drive circuits or the detection circuit experiences a hardware or software failure. Instead, the main driving circuit opens the relay's main contacts only after the DC circuit has stopped operating for a first preset time. This ensures that there is no large load current in the DC circuit when the relay's main contacts disconnect, preventing additional component damage and improving operational safety.

[0043] Figure 1 is a schematic diagram of the connection of a relay drive circuit according to an embodiment of the present disclosure.

[0044] As shown in Figure 1, the relay drive circuit 100 is applied to the power supply system, which includes a DC circuit 200. The main contacts of the relay K1 are connected in series in the DC circuit 200.

[0045] The relay drive circuit 100 of this embodiment may include: a main drive circuit 10, a slave drive circuit 20, a detection circuit 30, a main controller 40, and a slave controller 50.

[0046] The main drive circuit 10 is connected to one end of the coil of the relay K1 to drive the relay K1. The slave drive circuit 20 is connected to one end of the coil of the relay K1 to drive the relay K1. The detection circuit 30 is used to detect the state of the main contacts of the relay K1 to obtain a state detection signal. The main controller 40 is connected to both the main drive circuit 10 and the detection circuit 30. When the state detection signal is abnormal, it controls the DC circuit 200 to stop working and, after a first preset time t1, controls the main drive circuit 10 to drive the main contacts of the relay K1 to open. The slave controller 50 is connected to both the slave drive circuit 20 and the detection circuit 30 and communicates with the main controller 40. When it receives a first relay disconnect command output by the main controller 40 when it is abnormal, or when it determines that the state detection signal is abnormal, it controls the DC circuit to stop working and, after a first preset time t1, controls the slave drive circuit 20 to drive the main contacts of the relay K1 to open.

[0047] For example, the power supply system can be a photovoltaic energy storage system, and there is no specific limitation. The DC circuit 200 is used to convert the power in the battery BAT1 into output, or to charge the battery BAT.

[0048] Taking the DC circuit 200 shown in Figure 2 as an example, the DC circuit 200 consists of a battery BT1, a resistor R21, a diode D201, capacitors C201 and C202, an inductor L1, and switching transistors Q3 and Q4. The main contacts of relay K1 are connected in parallel with resistor R201 and diode D201. Taking the discharge of battery BT1 as an example, capacitor C201, inductor L1, and switching transistors Q3 and Q4 form a BUCK circuit. Upon receiving a discharge command, the main contacts of relay K1 are first opened. Battery BT1 pre-charges the bus capacitor C202 through resistor R201. Under the current-limiting effect of resistor R201, a large inrush current is prevented in the battery circuit, thus ensuring the safety of bus capacitor C202 and the semiconductor devices in the battery circuit. When the voltage of bus capacitor C202 equals the battery terminal voltage, the main contacts of relay K1 are closed, bypassing resistor R201 and diode D201 to reduce resistor losses and heat generation.

[0049] This application controls relay K1 based on the relay drive circuit 100 shown in Figures 1 and 2 to meet charging and discharging requirements. In this embodiment, both the main drive circuit 10 and the slave drive circuit 20 are connected to one end of the coil of relay K1 to drive the main contacts of relay K1 to close and open. During the operation of DC circuit 200, the main controller 40 obtains the status detection signal of the main contacts of relay K1 through the detection circuit 30. When the status detection signal is found to be abnormal, the main controller first controls the DC circuit to stop working, that is, controls the switching transistors Q3 and Q4 to stop operating. After a first preset time t1, the current in DC circuit 200 drops to a safe range, such as below a preset voltage. Then, the main controller controls the main drive circuit 10 to drive the main contacts of relay K1 to open. This avoids the large load current in DC circuit 200 when the main contacts of relay K1 are open, which would cause excessive load current to flow through resistor R201 and diode D201, resulting in damage or failure of resistor R201, diode D201, or even relay K1, thus improving operational safety.

[0050] Meanwhile, during the operation of the DC circuit 200, the slave controller 50 can control the DC circuit 200 to stop working (i.e., control the switching transistors Q3 and Q4 to stop operating) when it receives a first relay disconnect command sent by the master controller 40 in the event of an anomaly, or based on the received status detection signal and determining that the status detection signal is abnormal. After a first preset time t1, the current in the DC circuit 200 is allowed to drop to a safe range, such as below a preset voltage. Then, the slave drive circuit 20 drives the main contacts of relay K1 to disconnect, thereby preventing damage to resistor R201, diode D201, or even relay K1 due to excessive load current still existing in the DC circuit 200 when the main contacts of relay K1 disconnect. This improves operational safety. The anomaly of the master controller 40 can be caused by the master controller 40 generating the first relay disconnect command when its program crashes; the specific cause is not limited.

[0051] It should be noted that an abnormal status detection signal during operation refers to a discrepancy between the status of relay K1 determined based on the status detection signal and the control signal. In this case, the status detection signal is considered abnormal. For example, if the controller outputs a closing control signal to drive the main contacts of relay K1 to close, and the acquired status detection signal indicates that the main contacts of relay K1 are in a closed state, then the status detection signal is considered normal; otherwise, the status detection signal is considered abnormal.

[0052] It is understandable that an abnormal status detection signal could be caused by one or more factors, such as a faulty relay K1, a faulty detection circuit 30, a faulty drive circuit, or a controller fault, such as a program crash. For example, if relay K1 is normal but detection circuit 30 is abnormal, the status detection signal of detection circuit 30 indicating the main contact state of relay K1 will be inconsistent with the relay's control signal, thus the status detection signal is considered abnormal. If relay K1 is abnormal but detection circuit 30 is normal, the detection circuit result fed back by detection circuit 30 will be inconsistent with the relay's control signal, thus the status detection signal is considered abnormal. Only when the status detection signal of detection circuit 30 indicating the main contact state of relay K1 is consistent with the relay's control signal is relay K1, detection circuit 30, and the corresponding drive circuit considered normal. Therefore, the status detection signal can be used to identify whether relay K1, detection circuit, etc., are normal or abnormal.

[0053] When an anomaly is detected, this application first controls the DC circuit 200 to stop working, that is, controls the switching transistors Q3 and Q4 to operate, so that the current in the DC circuit 200 gradually decreases. After a delay of a first preset time t1, the application controls the drive circuit to drive the main contacts of the relay K1 to open, so that when the main contacts of the relay K1 open, there is no large load current in the DC circuit 200. Therefore, even if a fault occurs during operation, no additional device damage will occur. At the same time, the circuit provides two redundant drives. When one drive fails in hardware or software, the other drive can still control the relay K1, so that the main contacts of the relay K1 will not open immediately, further improving the safety of operation.

[0054] In one embodiment of this disclosure, the main controller 40 is further configured to control the DC circuit 200 to stop working in response to a stop working command of the DC circuit, and after a delay of a first preset time t1, control the main drive circuit 10 to drive the main contacts of the relay K1 to open, and send a second relay disconnect command to the slave controller 50, so that the slave controller 50 controls the slave drive circuit 20 to drive the main contacts of the relay K1 to open based on the second relay disconnect command.

[0055] For example, continuing with Figure 2, the main controller 40 is connected to the BMS (Battery Management System) of the battery BT1 via an external controller to obtain the working instructions of the DC circuit 200 based on external communication, such as charging and discharging instructions, start working instructions, stop working instructions, etc.

[0056] When the main controller 40 receives a stop command from the DC circuit, it controls the main contacts of relay K1 to open normally. The specific control process is as follows:

[0057] First, based on the received stop-work command from the DC circuit, the main controller 40 stops sending the PWM (Pulse Width Modulation) wave of the battery section, which is the control pulse signal used to drive the switching transistors Q3 and Q4, to control the DC circuit 200 to stop working. Then, after a first preset time t1, when the load current in the DC circuit 200 drops to a safe range, the main controller 40 controls the main drive circuit 10 to drive the main contacts of relay K1 to open, so as to avoid the main contacts of relay K1 cutting off a large load current. At the same time, the main controller 40 sends a command to the slave controller 50 to disconnect relay K1, i.e., a second relay disconnect command. After receiving the second relay disconnect command, the slave controller 50 controls the slave drive circuit 20 to drive the main contacts of relay K1 to open according to the second relay disconnect command.

[0058] Alternatively, the main controller 40 can first control the main drive circuit 10 to drive the main contacts of relay K1 to open, and then send a second relay disconnect command to the slave controller 50. The slave controller 50 controls the slave drive circuit 20 to drive the main contacts of relay K1 to open according to the second relay disconnect command. The specific timing is not limited.

[0059] In this embodiment, during the normal disconnection control process of the main contacts of relay K1, based on the stop working command of the DC circuit, the DC circuit 200 is first controlled to stop working, and then the main contacts of relay K1 are controlled to disconnect after a first preset time t1, so as to avoid a large load current in the DC circuit 200 when the main contacts of relay K1 are disconnected.

[0060] In one embodiment of this disclosure, the main controller 40 is further configured to respond to the operating command of the DC circuit, and, if the status detection signal is normal, send a relay closing command to the slave controller 50; the slave controller 50 is further configured to control the slave drive circuit 20 to drive the main contacts of the relay K1 to close based on the relay closing command, and acquire the status detection signal after a second preset time t2, and, if the status detection signal is normal, send a status normal feedback signal to the main controller 40; the main controller 40 is further configured to control the main drive circuit 10 to drive the main contacts of the relay K1 to close based on the status normal feedback signal, and acquire the status detection signal after a second preset time t2, and, if the status detection signal is normal, control the DC circuit to operate.

[0061] The second preset time t2 can be set according to the actual situation. It should be greater than or equal to the time interval required between the controller issuing the control command and the main contact of the control relay K1 completing the action, so as to ensure the accuracy of the status detection.

[0062] For example, the main contacts of relay K1 are normally open. When the main controller 40 receives the working command from the DC circuit, it first determines whether the relay's drive circuit and detection circuit are working normally based on the status detection signal fed back by the detection circuit 30. For instance, if the status detection signal fed back by the detection circuit 30 indicates that the main contacts of relay K1 are open, then the status detection signal is determined to be normal, meaning that the relay's drive circuit and detection circuit are working normally; otherwise, the status detection signal is determined to be abnormal, meaning that the relay's drive circuit and detection circuit are not working normally.

[0063] When the master controller 40 determines that the status detection signal is normal, it sends a relay closing command to the slave controller 50. Based on the relay closing command, the slave controller 50 controls the slave drive circuit 20 to drive the main contacts of relay K1 to close. After issuing the closing control signal based on the relay closing command, the slave controller 50 starts timing and determines that the main contacts of relay K1 have successfully closed when the timing reaches the second preset time t2. Then, it acquires the status detection signal through the detection circuit 30. If the status detection signal determines that the main contacts of relay K1 are in the closed state, it determines that the status detection signal is normal, that is, the slave drive circuit 20 is in normal state, and sends a status normal feedback signal to the master controller 40; otherwise, it determines that the status detection signal is abnormal and can send a corresponding status abnormal feedback signal to the master controller 40 to perform corresponding processing.

[0064] When the main controller 40 receives a normal status feedback signal, it outputs a closing control command to the main drive circuit 10. After a second preset time t2, it obtains a status detection signal through the detection circuit 30. When the status detection signal determines that the main contact of the relay K1 is in the closed state, it determines that the status detection signal is normal. The main control unit 40 sends the PWM wave of the battery section to control the DC circuit 200 to work.

[0065] It should be noted that, in addition to the above implementation, after the slave controller 50 sends a normal status feedback signal to the master controller 40, the slave controller 50 can also stop outputting the closing control signal to restore the main contacts of relay K1 to the open state. Then, the master controller 40 outputs a closing control command to the master drive circuit 10. After a second preset time t2, the detection circuit 30 acquires the status detection signal. When the status detection signal determines that the main contacts of relay K1 are in the closed state, it is determined that the status detection signal is normal and the master drive circuit 10 is normal. Thus, when it is determined that both drive circuits are normal, the master controller 40 continues to output the closing control command and simultaneously controls the slave controller 50 to synchronously output the closing control command. Then, the master control unit 40 sends the PWM wave of the battery section to control the DC circuit 200 to work.

[0066] In one embodiment of this disclosure, the master controller 40 and the slave controller 50 are further configured to respond to a self-test command before the DC circuit 200 operates, respectively control the corresponding drive circuit to drive the main contacts of the relay K1 to close first and then open, and acquire the status detection signals when closing and opening, and determine whether the corresponding drive circuit, detection circuit 30 and relay K1 are normal based on the status detection signals when closing and opening; wherein, the slave controller 50 is further configured to send the determination result to the master controller 40.

[0067] For example, after the main controller 40 receives a power scheduling command (such as a working command, a charging command, or a discharging command), before issuing the PWM wave of the battery section to control the DC circuit 200 to work, it first performs a power-on self-test on the drive circuit, the detection circuit 30, and the relay K1. The self-test process is as follows:

[0068] First, determine whether the drive circuit and detection circuit 30 corresponding to controller 50 are working properly, as follows:

[0069] In response to a self-test command, the controller 50 controls the drive circuit 20 to close the main contacts of the relay K1. After a second preset time t2, it acquires a status detection signal. If the status detection signal indicates that the main contacts of the relay K1 are in a closed state, it is determined that the status detection signal is normal. If the status detection signal indicates other states, it is determined that the circuit driving the relay in the controller 50 has failed, and the corresponding result is sent to the main controller 40.

[0070] After the controller 50 determines that the status detection signal is normal, it controls the drive circuit 20 to open the main contacts of the relay K1. After a second preset time t2, it acquires the status detection signal again. If the acquired status detection signal indicates that the main contacts of the relay K1 are in the open state, it determines that the status detection signal is normal, and that the drive circuit 20, the detection circuit 30, and the relay K1 are all normal. It then sends the self-test result information to the main controller 40. If the acquired status detection signal indicates other states, it determines that the circuit driving the relay in this path of the controller 50 has failed.

[0071] Then, it is determined whether the drive circuit and detection circuit 30 corresponding to the main controller 40 are working properly, as follows:

[0072] In response to the self-test command, the main controller 40 controls the main drive circuit 10 to drive the main contacts of the relay K1 to close, and acquires the status detection signal after a second preset time t2. If the status detection signal indicates that the main contacts of the relay K1 are in the closed state, it is determined that the status detection signal is normal; if the status detection signal indicates other states, it is determined that the circuit of the main controller 40 driving the relay has failed.

[0073] When the main controller 40 determines that the status detection signal is normal, it controls the main drive circuit 10 to drive the main contacts of relay K1 to open. After a second preset time t2, it acquires the status detection signal again. If the acquired status detection signal indicates that the main contacts of relay K1 are in the open state, it determines that the status detection signal is normal, and that the main drive circuit 10, the detection circuit 30, and relay K1 are all normal. If the acquired status detection signal indicates other states, it determines that the circuit of the main controller 40 that drives the relay has failed.

[0074] In one embodiment of this disclosure, the master controller 40 and the slave controller 50 are further configured to respond to a self-test command before the DC circuit operates, first simultaneously controlling the corresponding drive circuit to drive the main contacts of relay K1 to close, and after a second preset time t2, one of the master controller 40 and the slave controller 50 controls the corresponding drive circuit to drive the main contacts of relay K1 to open, and the other controller acquires a status detection signal and determines whether the corresponding drive circuit, detection circuit 30 and relay K1 are normal based on the status detection signal; if the corresponding drive circuit, detection circuit and relay are all normal, then simultaneously controlling the corresponding drive circuit to drive the main contacts of relay K1 to close, and after a second preset time t2, the other controller controls the corresponding drive circuit to drive the main contacts of relay K1 to open, and the other controller acquires a status detection signal and determines whether the corresponding drive circuit, detection circuit 30 and relay K1 are normal based on the status detection signal.

[0075] For example, the main controller 40 and the slave controller 50 can simultaneously output a closing control command based on a self-test command to drive the main contacts of relay K1 to close. After a second preset time t2, the main controller 40 controls the main drive circuit 10 to drive the main contacts of relay K1 to open. The slave controller 50 obtains a status detection signal. When the status detection signal indicates that the main contacts of relay K1 are in a closed state, it determines that the slave drive circuit 20, the detection circuit 30, and the relay K1 are normal; otherwise, it considers that the drive circuit corresponding to the slave controller 50 is abnormal.

[0076] If the drive circuit 20, detection circuit 30, and relay K1 are all functioning normally, the main controller 40 and the slave controller 50 simultaneously output a closing control command to drive the main contacts of relay K1 to close. After a second preset time t2, the slave controller 50 controls the slave drive circuit 20 to drive the main contacts of relay K1 to open. The main controller 40 makes a judgment based on the acquired state detection signal. If the state detection signal indicates that the main contacts of relay K1 are in a closed state, it determines that the main drive circuit 10, detection circuit 30, and relay K1 are functioning normally; otherwise, the corresponding drive circuit of the main controller 40 is not functioning normally.

[0077] As shown in Figure 3, in one embodiment of this disclosure, the relay drive circuit 100 further includes: a first power supply circuit 60, which is connected to the first power supply VCC1 and the other end of the coil of relay K1, respectively, for providing a first voltage VC1 to the other end of the coil of relay K1; and a second power supply circuit 70, which is connected to the first power supply VCC1 and the other end of the coil of relay K1, respectively, for providing a first voltage VC1 to the other end of the coil of relay K1.

[0078] In other words, the coil of relay K1 is powered by two power supply circuits, the first power supply circuit 60 and the second power supply circuit 70, to achieve power supply redundancy design. If a single fault occurs in one power supply circuit, the other power supply circuit can still ensure the normal operation of relay K1. It is ensured that the main contacts of relay K1 will not open until the DC circuit stops working for a first preset time t1, thus avoiding the large current cutoff of the main contacts of relay K1.

[0079] Referring to Figure 4, in one embodiment of this disclosure, the first power supply circuit 60 and the second power supply circuit 70 have the same circuit structure. The first power supply circuit 60 includes: a first diode D1, the anode of which is connected to a first power supply VCC1; a second diode D2, the anode of which is connected to the cathode of the first diode D1, and the cathode of which is connected to the other end of the coil of the relay K1; and a first capacitor C1, which is connected in series between the anode of the second diode D2 and the first ground terminal EP1.

[0080] In other words, both the first power supply circuit 60 and the second power supply circuit 70 convert the voltage provided by the first power supply VCC1 into the power supply voltage VC1 of the relay K1 through diodes D1 and D2 and capacitor C1. This allows the relay coil to continue to be powered by the other power supply circuit when a single power circuit fails. This also allows the DC circuit 200 to stop working for a certain period of time before controlling the main contacts of the relay K1 to open.

[0081] Referring to Figures 5-7, in one embodiment of this disclosure, the detection circuit 30 includes: a state detection circuit 31 for detecting the state of the auxiliary contact of the relay K1, wherein the state of the auxiliary contact is used to characterize the state of the main contact; and / or, a voltage detection circuit 32 for detecting a first voltage V1 at one end of the main contact of the relay K1 and a second voltage V2 at the other end of the main contact of the relay K1, wherein the voltage difference between the first voltage V1 and the second voltage V2 is used to characterize the closed or open state of the main contact of the relay K1.

[0082] For example, for a relay K1 with auxiliary contacts, the state of the auxiliary contacts is detected by a state detection circuit 31. Under normal circumstances, the auxiliary contacts of relay K1 are linked to the main contacts. For instance, the auxiliary contacts can operate synchronously with the main contacts, i.e., when the main contacts are closed, the auxiliary contacts are closed; when the main contacts are open, the auxiliary contacts are open. Conversely, the auxiliary contacts can also operate in the opposite direction to the main contacts, i.e., when the main contacts are closed, the auxiliary contacts are open; when the main contacts are open, the auxiliary contacts are closed. Therefore, the state of the main contacts can be characterized by the state of the auxiliary contacts.

[0083] The voltage detection circuit 32 detects the voltage difference across the main contacts of relay K1 to determine the closed state of the main contacts. It is understood that when the main contacts of relay K1 are closed, the voltage difference across them is small; when the main contacts are open, the current flows through the resistor, resulting in a larger voltage difference. This can be determined by setting a threshold value. For example, if the voltage difference across the main contacts of relay K1 is less than 12V, the main contacts are determined to be open; if the voltage difference is greater than or equal to 12V, the main contacts are determined to be closed. Therefore, the state of the main contacts of relay K1 can be determined based on the voltage difference between the first voltage V1 and the second voltage V2.

[0084] For a relay K1 with auxiliary contacts, the detection circuit 30 may include a state detection circuit 31 and a voltage detection circuit 32. In this case, the state of the main contacts of the relay K1 is determined based on the state of the auxiliary contacts and the voltage difference between the first voltage V1 and the second voltage V2. For a relay K1 with auxiliary contacts, the detection circuit 30 may only include a state detection circuit 31 to determine the state of the main contacts of the relay K1 based on the state of the auxiliary contacts; or it may only include a voltage detection circuit 32 to determine the state of the main contacts of the relay K1 based on the voltage difference between the first voltage V1 and the second voltage V2. For a relay K1 without auxiliary contacts, the detection circuit 30 only includes a voltage detection circuit 32 to determine the state of the main contacts of the relay K1 based on the voltage difference between the first voltage V1 and the second voltage V2.

[0085] In one embodiment of this disclosure, when the detection circuit 30 includes a state detection circuit 31, if the state of the auxiliary contact is consistent with the control signal of the relay K1, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal. When the detection circuit 30 includes a voltage detection circuit 32, if the voltage difference is consistent with the control signal of the relay K1, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal. When the detection circuit 30 includes both the state detection circuit 31 and the voltage detection circuit 32, if both the state of the auxiliary contact and the voltage difference are consistent with the control signal of the relay K1, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal.

[0086] For example, when the detection circuit 30 includes a state detection circuit 31, the state detection circuit 31 sends the acquired state of the auxiliary contact to the main controller 40 and the slave controller 50. The main controller 40 and the slave controller 50 compare the state of the auxiliary contact with the control signal of the relay K1. If the states of the main contacts of the relay K1 determined by the two are consistent, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal.

[0087] When the detection circuit 30 includes a voltage detection circuit 32, the voltage detection circuit 32 sends the acquired voltage difference to the main controller 40 and the slave controller 50. The main controller 40 and the slave controller 50 compare the voltage difference with the control signal of the relay K1. If the states of the main contacts of the relay K1 determined by the two are consistent, the state detection signal is determined to be normal; otherwise, the state detection signal is determined to be abnormal.

[0088] The auxiliary contact status acquired by the status detection circuit 31 and the voltage difference determined by the voltage detection circuit 32 are both sent to the main controller 40 and the slave controller 50. The main controller 40 and the slave controller 50 compare the auxiliary contact status and the voltage difference with the control signal of the relay K1. If the status of the main contact of the relay K1 determined by the three circuits is consistent, the status detection signal is determined to be normal; otherwise, the status detection signal is determined to be abnormal. This detection circuit 30 simultaneously detects the auxiliary contact status and the voltage difference, which can rule out the possibility that the auxiliary contact status is correct but the main contact of the relay K1 is not actually engaged, thus improving the detection accuracy.

[0089] In one embodiment of this disclosure, the state detection circuit 31 includes: a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to one end of the auxiliary contact of the relay K1, and the other end of the first resistor R1 is connected to the main controller 40 and the slave controller 50 respectively. The second resistor R2 is connected in series between the other end of the first resistor R1 and the second ground terminal EP2, wherein the other end of the auxiliary contact of the relay K1 is connected to the second power supply VCC2. Alternatively, a third resistor R3, a fourth resistor R4, and a second capacitor C2 are included. One end of the third resistor R3 is connected to one end of the auxiliary contact of the relay K1, and the other end of the third resistor R3 is connected to the third power supply VCC3. One end of the fourth resistor R4 is connected to one end of the third resistor R3, and the other end of the fourth resistor R4 is connected to the main controller 40 and the slave controller 50 respectively. The second capacitor C2 is connected in series between the other end of the fourth resistor R4 and the third ground terminal EP3, wherein the other end of the auxiliary contact of the relay K1 is connected to the fourth ground terminal EP4.

[0090] For example, taking the relay K1 shown in Figure 2 as an example, the auxiliary contact of the relay K1 operates in the opposite way to the main contact, that is, the main contact is normally open and the auxiliary contact is normally closed. When the main contact is closed, the auxiliary contact is open, and when the main contact is open, the auxiliary contact is closed.

[0091] In the state detection circuit 31 shown in Figure 5, when the main contact of relay K1 is open, the auxiliary contact is closed, and the state detection signal output by the state detection circuit 31 is high level; when the main contact of relay K1 is closed, the auxiliary contact is open, and the state detection signal output by the state detection circuit 31 is low level.

[0092] In the state detection circuit 31 shown in Figure 6, the third resistor R3 and the first capacitor C1 constitute a filter circuit. When the main contact of relay K1 is open, the auxiliary contact is closed, and the state detection signal output by the state detection circuit 31 is low level; when the main contact of relay K1 is closed, the auxiliary contact is open, and the state detection signal output by the state detection circuit 31 is high level.

[0093] It is understandable that when the second power supply VCC2 and the third power supply VCC3 use the power supply levels of the main controller 40 and the slave controller 50, the status detection circuit 31 does not need to add a level conversion circuit; when the second power supply VCC2 and the third power supply VCC3 do not use the power supply levels of the main controller 40 and the slave controller 50, the status detection circuit 31 needs to add a level conversion circuit to reduce the voltage output in order to avoid damage to the controller due to excessive voltage.

[0094] In one embodiment of this disclosure, the voltage detection circuit 32 includes: a first differential circuit 321, the input terminal of which is connected to one end of the main contact of relay K1 and one end of the DC power supply BT1 in DC circuit 200, and the output terminal of which is connected to the main controller 40 and the slave controller 50, respectively, for detecting a first voltage V1; and a second differential circuit 322, the input terminal of which is connected to the other end of the main contact of relay K1 and one end of the DC power supply BT1, and the output terminal of which is connected to the main controller 40 and the slave controller 50, respectively, for detecting a second voltage V2; wherein, the other end of the DC power supply BT1 is connected to one end of the main contact of relay K1.

[0095] For example, as shown in Figures 5 and 7, the two input terminals of the first differential circuit 321 are connected to voltage sample 1+ and voltage sample 1- respectively, so that the voltage between the two sampling points, voltage sample 1+ and voltage sample 1-, is used as the first voltage V1, and the first voltage V1 is detected. The two input terminals of the second differential circuit 322 can be connected to voltage sample 2+ and voltage sample 2- respectively, so that the voltage between the two sampling points, voltage sample 2+ and voltage sample 2-, is used as the second voltage V2, and the second voltage V2 is detected.

[0096] Based on the circuit connection, it can be seen that when the main contacts of relay K1 are closed, short-circuiting resistor R21 and diode D21 results in a smaller voltage across the main contacts of relay K1. When the main contacts of relay K1 are open, current flows through resistor R21 and diode D21, resulting in a larger voltage across the main contacts of relay K1. In one embodiment, the voltage detection circuit 32 can compare and detect the voltage difference before and after the main contacts of relay K1 using the first differential circuit 321 and the second differential circuit 322, and send the voltage difference to the main controller 40 and the slave controller 50. When the voltage difference is less than 12V, the main controller 40 and the slave controller 50 consider the main contacts of relay K1 to be closed; when the voltage difference is greater than or equal to 12V, the main contacts of relay K1 are considered to be open. The circuits of the first differential circuit 321 and the second differential circuit 322 can be arranged based on Figure 7. The circuits are the same and consist of resistors and differential amplifiers. The first differential circuit 321 outputs a signal to the main controller 40 based on a single-stage operational amplifier (differential amplifier UA11) and outputs a signal to the slave controller 50 based on two-stage operational amplifiers (differential amplifier UA11 and differential amplifier U12). The second differential circuit 322 outputs a signal to the main controller 40 based on a single-stage operational amplifier (differential amplifier UA21) and outputs a signal to the slave controller 50 based on two-stage operational amplifiers (differential amplifier UA21 and differential amplifier U22).

[0097] In one embodiment of this disclosure, as shown in FIG8, the main drive circuit 10 and the slave drive circuit 20 have the same circuit structure. The main drive circuit 10 includes: a first drive buffer Buffer1, which is connected to the main controller 40 and is used to amplify the control signal of the main controller 40; a first switch Q1, the first end of which is connected to the first drive buffer Buffer1, the second end of which is connected to one end of the coil of the relay K1, and the third end of which is connected to the fifth ground terminal EP5.

[0098] For example, when the main controller 40 outputs a high-level control signal, the control signal is amplified by the first drive buffer Buffer1 to control the first switch Q1 to turn on. The current passing through the first switch Q1 is amplified by the transistor, making the voltage across the coil of the relay K1 greater than the operating voltage of the relay K1, and the relay K1 closes.

[0099] When the controller 50 outputs a high-level control signal, the control signal is amplified by the second drive buffer Buffer2, which controls the second switch Q2 to turn on. The current passing through the second switch Q2 is amplified by the transistor, making the voltage across the coil of relay K1 greater than the operating voltage of relay K1, and relay K1 closes.

[0100] It should be noted that the first drive buffer (buffer1) and the second drive buffer (buffer2) function as current amplifiers. These can be integrated chips or current amplification circuits composed of two transistors; the specific configuration is not limited. Furthermore, current-limiting resistors can be placed at the input and output ports of the drive buffers. Specifically, current-limiting resistors R11 and R13 are placed at the input and output ports of the first drive buffer (buffer1), and current-limiting resistors R21 and R23 are placed at the input and output ports of the second drive buffer (buffer2). Pull-down resistors can also be placed at the input and output ports of the drive buffers to determine the initial level of the circuit and prevent signal interference. Specifically, pull-down resistors R12, R14, and R16 are placed at the input and output ports of the first drive buffer (buffer1), and pull-down resistors R22, R24, and R26 are placed at the input and output ports of the second drive buffer (buffer2). A diode can also be placed on the drive circuit to limit the current direction. Specifically, a diode D1 is provided on the main drive circuit 10, and a diode D2 is provided on the slave drive circuit 10. Current-limiting resistors and capacitors can also be arranged at the control terminal of the switching transistor Q. Specifically, a current-limiting resistor 15 and a capacitor C1 are connected to the control terminal of the first switching transistor Q1, and a current-limiting resistor 25 and a capacitor C2 are connected to the control terminal of the second switching transistor Q2.

[0101] Taking the drive circuit 20 as an example, when the controller 50 issues a command to close the relay K1, that is, when the IO port of the controller 50 goes high, the output is amplified by the second drive buffer buffer2, and the capacitor C2 starts to charge. When the voltage of the capacitor C2 is higher than the VBE conduction voltage of the second switch Q2, the second switch Q2 is turned on, and the current through the second switch Q2 is amplified by the transistor, making the voltage across the coil of the relay K1 greater than the operating voltage of the relay K1, and the main contacts of the relay K1 are closed.

[0102] As a specific embodiment of this application, the relay drive circuit 100 is shown in Figures 2, 5, 7, and 8. The main controller 40 communicates with the BMS of the battery BT1 to receive control commands from the externally input DC circuit and generate corresponding PWM waveforms. The controller 50 then controls the switching transistors Q3 and Q4. The specific operation of the relay drive circuit 100 is as follows:

[0103] 1. When the main controller 40 receives the power dispatch command, i.e., the charge and discharge control command, the battery circuit in the photovoltaic energy storage inverter prepares for operation. Before the main controller 40 prepares to generate the PWM wave for the battery section, it first performs a power-on self-test. The self-test process is as follows:

[0104] (1) Determine whether the circuit driving the relay from controller 50 is normal, that is, whether the drive circuit 60, detection circuit 30 and relay K1 corresponding to controller 50 are working properly.

[0105] For example, the controller 50 outputs a high-level closing control command based on the self-test instruction. This command is amplified by the second drive buffer 2, and capacitor C2 begins charging. When the voltage across capacitor C2 exceeds the VBE turn-on voltage of the second switch Q2, Q2 turns on. The current flowing through Q2 is amplified by the transistor, causing the voltage across the coil of relay K1 to exceed its operating voltage, thus closing the main contacts of relay K1. After a time t3 following the high-level closing control command output by the controller 50 (after the controller 50 issues the command to close the relay), the main contacts of relay K1 close. The closing of electrical appliance K1 requires time t3, which can be adjusted by adjusting the values ​​of R23, R25, and C2. The controller 50 checks whether the state of the relay's auxiliary contacts is correct and whether the voltage difference between the sampling voltages before and after the relay's main contacts is less than 12V. If the state of the relay's auxiliary contacts is correct and the voltage difference is less than 12V, then the controller 50 sends a message back to the main controller 40: the circuit driving the relay through the controller 50 is working normally; otherwise, the controller 50 sends a message back to the main controller 40: the circuit driving the relay through the controller 50 has failed.

[0106] If the circuit driving the relay from controller 50 is confirmed to be working properly, controller 50 outputs a low-level disconnect control signal to open the main contacts of relay K1. After time t4 (it takes time t4 for the main contacts of relay K1 to open after controller 50 sends the disconnect control signal), controller 50 checks whether the state of the relay's auxiliary contacts is correct and whether the voltage difference between the sampled voltages before and after the relay's main contacts is greater than 12V. If the state of the relay's auxiliary contacts is correct and the sampling difference is greater than 12V, controller 50 sends a message back to main controller 40: the circuit driving the relay from controller 50 is working properly; otherwise, controller 50 sends a message back to main controller 40: the circuit driving the relay from controller 50 has failed.

[0107] (2) Determine whether the drive circuit of the main controller 40 is normal, that is, whether the main drive circuit 10, detection circuit 30 and relay K1 corresponding to the main controller 40 are working properly.

[0108] For example, the main controller 40 outputs a high-level closing control command based on the self-test command, and after time t3, the main controller 40 checks whether the state of the auxiliary contact of the relay is correct and whether the voltage difference between the sampled voltages before and after the main contact of the relay is less than 12V. If the state of the auxiliary contact of the relay is correct and the voltage difference is less than 12V, then the circuit of the main controller 40 driving the relay is working normally; if it is any other state, the main controller 40 determines that the circuit of the main controller 40 driving the relay has failed.

[0109] If the main controller 40's relay driving circuit is confirmed to be working normally, the main controller 40 outputs a low-level disconnect control signal to disconnect the main contacts of relay K1. After time t4, the main controller 40 checks whether the state of the relay's auxiliary contacts is correct and whether the voltage difference between the sampled voltages before and after the relay's main contacts is greater than 12V. If the state of the relay's auxiliary contacts is correct and the sampling difference is greater than 12V, the main controller 40 determines that the main controller 40's relay driving circuit is working normally; otherwise, the main controller 40 determines that the main controller 40's relay driving circuit has malfunctioned.

[0110] It should be noted that the control principle of the main drive circuit 10 on the relay K1 is the same as that of the slave drive circuit 10 on the relay K1, and will not be elaborated here.

[0111] 2. Under normal self-test conditions, the main contacts of the normally closed relay K1 are controlled to send a PWM wave, enabling the DC circuit to operate. Details are as follows:

[0112] Before closing the main contacts of relay K1 and sending a PWM wave, the main controller 40 first determines whether the main contacts of relay K1 have closed and whether the drive circuit and detection circuit are working properly. For example, the main controller 40 acquires the voltage difference between before and after the main contacts of relay K1. If the voltage difference is greater than 12V before the main contacts of relay K1 close, the status detection is determined to be normal; otherwise, the drive circuit and detection circuit of the relay are determined to be malfunctioning.

[0113] When the status detection is normal, the main controller 40 communicates with the slave controller 50 to send a closing control command. After t3, the slave controller 50, after detecting that the status of the auxiliary contact of the relay is correct and determining that the voltage difference is less than 12V, sends a normal signal back to the main controller 40. Then, the main controller 40 also sends a closing control command to control the main contact of the relay K1 to close through the main drive circuit 10. When the main controller 40 detects that the voltage difference is less than 12V, it sends a PWM wave of the DC circuit to control the operation of the DC circuit.

[0114] When the main controller 40 sends a PWM wave to the DC circuit to control its operation, the following fault conditions may occur:

[0115] (1) When the controller 50 receives the first disconnection control command from the main controller 40, the controller 50 stops outputting the BAT part or the PV, BAT, AC part PWM wave, and controls the main contact of the disconnection relay K1 after a duration of t1.

[0116] (2) When the state of the auxiliary contact of the relay is detected by the slave controller 50 or the master controller 40 and conflicts with the control command of the relay, if the master controller 40 detects it, the master controller 40 sends a blocking command to the slave controller 50 to control the slave controller 50 to stop outputting the PWM wave, and the master controller 40 disconnects the main contact of the relay K1 after a duration of t1; if the slave controller 50 detects it, the slave controller 50 directly blocks the wave and disconnects the main contact of the relay K1 after a duration of t1. Here, blocking the wave means stopping the output of the BAT part or the PV,BAT,AC part of the PWM wave.

[0117] (3) If the voltage difference between the first voltage and the second voltage detected by the slave controller 50 or the master controller 40 is greater than or equal to 12V, if the master controller 40 detects it, the master controller 40 sends a blocking command to the slave controller 50 to control the slave controller 50 to stop outputting the PWM wave. At the same time, the master controller 40 disconnects the main contact of the relay K1 after a duration of t1. If the slave controller 50 detects it, the slave controller 50 directly blocks the wave and disconnects the main contact of the relay K1 after a duration of t1. Here, blocking the wave means stopping the output of the BAT part or the PV,BAT,AC part of the PWM wave.

[0118] After any of the above three faults occur, the main controller 40 will report the corresponding fault and send it to the battery's BMS.

[0119] The relay drive circuit 100 performs detection before the DC circuit 200 operates and also performs detection while the DC circuit 200 is operating. It can also detect the location of relay failure, making the system safer to operate.

[0120] 3. Control the normal disconnection relay.

[0121] When the main controller 40 receives the stop command from the DC circuit, it controls the PWM wave of the battery section to stop. After time t4, the main controller 40 stops detecting the state of the relay and controls the main drive circuit 10 to drive the main contacts of the relay to open. At the same time, the main controller 40 communicates with the slave controller 50 to send a second relay disconnect command. After receiving the second relay disconnect command, the slave controller 50 stops detecting the state of the main contacts of relay K1. Simultaneously, the slave controller 50 controls the slave drive circuit 20 to drive the main contacts of relay K1 to open based on the second relay disconnect command.

[0122] In summary, the relay driving circuit according to the embodiments of this disclosure is applied to a power supply system, which includes a DC circuit. The main contacts of the relay are connected in series in the DC circuit. In the relay driving circuit, the main driving circuit is connected to one end of the coil of the relay and drives the relay. The slave driving circuit is connected to one end of the coil of the relay and drives the relay. The state detection signal is obtained by detecting the state of the main contacts of the relay through a detection circuit. The main controller is connected to the main driving circuit and the detection circuit respectively. When the state detection signal is abnormal during the operation of the DC circuit, the main controller controls the DC circuit to stop working and controls the main driving circuit to drive the main contacts of the relay to open after a first preset time delay. The slave controller is connected to the slave driving circuit and the detection circuit respectively and communicates with the main controller. When the slave controller receives the first relay disconnect command output by the main controller when there is an abnormality or determines that the state detection signal is abnormal during the operation of the DC circuit, the slave controller controls the DC circuit to stop working and controls the slave driving circuit to drive the main contacts of the relay to open after a first preset time delay. Therefore, when an abnormality is detected during the operation of the DC circuit, the circuit first controls the DC circuit to stop working, and after a first preset time delay, it controls the main drive circuit to drive the main contacts of the relay to open, so that there is no large load current in the DC circuit when the main contacts of the relay are opened, so as to avoid additional device damage. At the same time, combined with the redundancy design of the circuit, the operational safety is further improved.

[0123] Corresponding to the above embodiments, this disclosure also proposes a power supply system.

[0124] As shown in FIG9, the power supply system 1000 of this embodiment includes the relay drive circuit 100 described above.

[0125] In one embodiment of this disclosure, the power system 1000 is a photovoltaic-storage inverter.

[0126] According to the power supply system of this disclosure embodiment, based on the above-described relay drive circuit, there is no large load current in the DC circuit when the main contacts of the relay are open, so as to avoid additional device damage. At the same time, combined with the redundancy design of the circuit, the system's operational safety is further improved.

[0127] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0128] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0129] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0130] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A relay drive circuit, applied in a power supply system, the power supply system including a DC circuit, wherein the main contacts of the relay are connected in series in the DC circuit, the drive circuit comprising: The main drive circuit is connected to one end of the coil of the relay and is used to drive the relay; A drive circuit is connected to one end of the coil of the relay to drive the relay; A detection circuit is used to detect the state of the main contacts of the relay to obtain a state detection signal; The main controller is connected to the main drive circuit and the detection circuit respectively. It is used to control the DC circuit to stop working when the state detection signal is abnormal, and to control the main drive circuit to drive the main contacts of the relay to open after a first preset time delay. The slave controller is connected to the slave drive circuit and the detection circuit respectively, and communicates with the master controller. It is used to control the DC circuit to stop working when it receives the first relay disconnect command output by the master controller when it is abnormal or when it is determined that the status detection signal is abnormal, and after a delay of the first preset time, it controls the slave drive circuit to drive the main contacts of the relay to disconnect.

2. The circuit according to claim 1, wherein, The main controller is also configured to respond to the stop operation command of the DC circuit, control the DC circuit to stop working, and after a delay of the first preset time, control the main drive circuit to drive the main contacts of the relay to open, and send a second relay disconnect command to the slave controller, so that the slave controller controls the slave drive circuit to drive the main contacts of the relay to open based on the second relay disconnect command.

3. The circuit according to claim 1 or 2, wherein, The main controller is also configured to respond to the operating instructions of the DC circuit and, if the status detection signal is normal, send a relay closing instruction to the slave controller. The slave controller is also configured to control the slave drive circuit to drive the main contacts of the relay to close based on the relay closing command, and to acquire the status detection signal after a second preset time delay, and to send a status normal feedback signal to the master controller if the status detection signal is normal. The main controller is also used to control the main drive circuit to drive the main contacts of the relay to close based on the normal status feedback signal, and to acquire the status detection signal after a second preset time delay, and to control the DC circuit to work when the status detection signal is normal.

4. The circuit according to claim 3, wherein, The main controller and the slave controller are further configured to respond to a self-test command before the DC circuit operates, control the corresponding drive circuit to drive the main contacts of the relay to close first and then open, acquire the status detection signals when closing and opening, and determine whether the corresponding drive circuit, the detection circuit and the relay are normal based on the status detection signals when closing and opening; wherein, the slave controller is further configured to send the determination result to the main controller.

5. The circuit according to claim 3 or 4, wherein, The main controller and the slave controller are also configured to respond to a self-test command before the DC circuit operates. First, the corresponding drive circuit is simultaneously controlled to drive the main contacts of the relay to close. After a second preset time delay, one of the main controller and the slave controller controls the corresponding drive circuit to drive the main contacts of the relay to open. The other controller acquires the status detection signal and determines whether the corresponding drive circuit, the detection circuit and the relay are normal based on the status detection signal. When the corresponding drive circuit, the detection circuit, and the relay are all functioning normally, the corresponding drive circuit is simultaneously controlled to drive the main contacts of the relay to close. After a second preset time delay, the other controller controls the corresponding drive circuit to drive the main contacts of the relay to open. The controller acquires the status detection signal and determines whether the corresponding drive circuit, the detection circuit, and the relay are functioning normally based on the status detection signal.

6. The circuit according to any one of claims 1-5, wherein, The driving circuit also includes: A first power supply circuit is connected to a first power supply and the other end of the coil of the relay, respectively, and is used to provide a first voltage to the other end of the coil of the relay. The second power supply circuit is connected to the first power supply and the other end of the relay coil, respectively, and is used to provide the first voltage to the other end of the relay coil.

7. The circuit according to claim 6, wherein, The first power supply circuit and the second power supply circuit have the same circuit structure, wherein the first power supply circuit includes: The first diode, wherein the anode of the first diode is connected to the first power supply; The second diode has its anode connected to the cathode of the first diode, and its cathode connected to the other end of the relay coil. The first capacitor is connected in series between the anode of the second diode and the first ground terminal.

8. The circuit according to any one of claims 1-7, wherein, The detection circuit includes: A state detection circuit is used to detect the state of the auxiliary contacts of the relay, wherein the state of the auxiliary contacts is used to characterize the state of the main contacts; and / or, A voltage detection circuit is used to detect a first voltage at one end of the main contact of the relay and a second voltage at the other end of the main contact of the relay, wherein the voltage difference between the first voltage and the second voltage is used to characterize the closed or open state of the main contact of the relay.

9. The circuit according to claim 8, wherein, When the detection circuit includes the status detection circuit, if the status of the auxiliary contact is consistent with the control signal of the relay, the status detection signal is determined to be normal; otherwise, the status detection signal is determined to be abnormal. When the detection circuit includes the voltage detection circuit, if the voltage difference is consistent with the control signal of the relay, the status detection signal is determined to be normal; otherwise, the status detection signal is determined to be abnormal. When the detection circuit includes the status detection circuit and the voltage detection circuit, if the status of the auxiliary contact and the voltage difference are consistent with the control signal of the relay, then the status detection signal is determined to be normal; otherwise, the status detection signal is determined to be abnormal.

10. The circuit according to claim 8 or 9, wherein, The state detection circuit includes: A first resistor and a second resistor are connected. One end of the first resistor is connected to one end of the auxiliary contact of the relay, and the other end of the first resistor is connected to both the main controller and the slave controller. The second resistor is connected in series between the other end of the first resistor and a second ground terminal. The other end of the auxiliary contact of the relay is connected to a second power supply. Alternatively, A third resistor, a fourth resistor, and a second capacitor are connected together. One end of the third resistor is connected to one end of the auxiliary contact of the relay, and the other end of the third resistor is connected to a third power supply. One end of the fourth resistor is connected to one end of the third resistor, and the other end of the fourth resistor is connected to the main controller and the slave controller respectively. The second capacitor is connected in series between the other end of the fourth resistor and the third ground terminal. The other end of the auxiliary contact of the relay is connected to the fourth ground terminal.

11. The circuit according to any one of claims 8-10, wherein, The voltage detection circuit includes: The first differential circuit has its input terminals connected to one end of the main contact of the relay and one end of the DC power supply in the DC circuit, respectively, and its output terminals connected to the main controller and the slave controller, respectively, for detecting the first voltage. The second differential circuit has its input terminals connected to the other end of the main contact of the relay and one end of the DC power supply, respectively, and its output terminals connected to the main controller and the slave controller, respectively, for detecting the second voltage; wherein, the other end of the DC power supply is connected to one end of the main contact of the relay.

12. The circuit according to any one of claims 1-11, wherein, The main drive circuit and the slave drive circuit have the same circuit structure, wherein the main drive circuit includes: The first drive buffer is connected to the main controller and is used to amplify the control signal of the main controller; The first switching transistor has a first end connected to the first drive buffer, a second end connected to one end of the coil of the relay, and a third end connected to the fifth ground terminal.

13. A power supply system comprising a relay drive circuit according to any one of claims 1-12.

14. The power supply system according to claim 13, wherein, The power system is a photovoltaic-storage inverter.

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