A photovoltaic power generation control circuit

Abstract

The application discloses a kind of photovoltaic power generation control circuit, it is related to photovoltaic power supply field, the photovoltaic power generation control circuit includes: main frame work module, for converting solar cell output voltage into 400V direct current and inputting to 400V direct current bus, 400V direct current is converted into 220V alternating current and is powered to electric load;When solar cell output power exceeds the demand power of electric load, the beneficial effects of the application are: the application monitors the charge-discharge state of energy storage battery in real time by overcharge and overdischarge detection module, judges whether overcharge or overdischarge occurs, and feeds back corresponding signal to signal detection control module.Signal detection control module dynamically controls the conduction relationship between main frame work module and electric load, mains power supply module according to the feedback, so as to effectively prevent overcharge and overdischarge of energy storage battery, fully utilize the power generation capacity of solar cell, and guarantee the continuous and reliable power supply of electric load.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power supply, specifically a photovoltaic power generation control circuit. Background Technology

[0002] In a photovoltaic energy storage system, the energy storage battery is responsible for balancing the power difference between power generation and power consumption: when the load demand is lower than the photovoltaic power generation, the surplus energy is stored in the energy storage battery; when the photovoltaic power supply is insufficient, the energy storage battery supplements the power supply; during periods of no photovoltaic output, such as at night or during continuous cloudy or rainy weather, the energy storage battery independently maintains the operation of the load.

[0003] However, if the system control strategy fails, it may lead to overcharging or over-discharging risks. Overcharging often occurs in scenarios where photovoltaic power generation is continuously excessive, the battery is fully loaded, and the load demand is extremely low. If excess energy continues to be input into the battery, it will cause the voltage to exceed the safe limit. Over-discharging is common when the battery charge is already low, but the system still forces it to continue discharging to meet the load demand, causing the voltage to drop below the protection threshold, resulting in deep discharge. Both of these abnormal operating conditions will seriously damage battery life and may pose safety hazards, requiring improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a photovoltaic power generation control circuit to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A photovoltaic power generation control circuit, comprising: The main frame working module is used to convert the output voltage of the solar cell into 400V DC power and input it to the 400V DC bus. Then, the 400V DC power is converted into 220V AC power to supply power to the electrical load. When the output power of the solar cell exceeds the power demand of the electrical load, the 400V DC power is stepped down to charge the energy storage battery. When the output power of the solar cell is lower than the power demand of the electrical load, the energy storage battery is stepped up to output 400V DC power to the 400V DC bus. The overcharge and over-discharge detection module is used to detect whether the energy storage battery is overcharged. If so, it feeds back a first voltage signal to the signal detection and control module. It also detects whether the energy storage battery is over-discharged. If so, it feeds back a second voltage signal to the signal detection and control module. The signal detection and control module is used to monitor voltage changes on the 400V DC bus and determine the current power demand changes of the electrical load (real-time monitoring of minute changes in the 400V DC bus voltage, automatically adjusting the working mode and power of the bidirectional DC-DC converter, i.e., boost or buck), to adjust the charging and discharging of the energy storage battery; when it receives the first voltage signal from the overcharge and over-discharge detection module, it connects the output 220V AC power to the mains power supply module; when it receives the second voltage signal from the overcharge and over-discharge detection module, it disconnects the power supply circuit between the main frame working module and the electrical load, and establishes a power supply circuit between the mains power supply module and the electrical load; The first output of the main frame working module is connected to the input of the overcharge and over-discharge detection module (at the fourth and fifth resistors). The second output of the main frame working module is connected to the first input of the signal detection and control module (at the 400V DC bus). The output of the overcharge and over-discharge detection module is connected to the second input of the signal detection and control module (at the IO2 and IO3 interfaces of the microcontroller). The output of the signal detection and control module is connected to the input of the main frame working module (the microcontroller controls the switch via a relay).

[0006] As a further embodiment of the present invention: the main frame working module includes a solar cell, a first diode, a first switch, a second switch, a third switch, a fourth resistor, a fifth resistor, an energy storage battery, a third diode, a fourth diode, a fifth diode, and a sixth diode. The negative terminal of the solar cell is grounded, the positive terminal of the solar cell is connected to the positive terminal of the first diode, the negative terminal of the first diode is connected to the first terminal of the DC-DC boost converter, the second terminal of the DC-DC boost converter is connected to the 400V DC bus, the 400V DC bus is connected to the first terminal of the DC-AC inverter, the first terminal of the bidirectional DC-DC converter, and the first input terminal of the signal detection and control module, the second terminal of the DC-AC inverter is connected to the electrical load through the second switch, the third terminal of the DC-AC inverter is connected to the mains power supply module through the first switch, and the mains power supply module is connected to the electrical load through the third switch. The second terminal of the bidirectional DC-DC converter is connected to the positive terminal of the sixth diode, the third terminal of the bidirectional DC-DC converter is connected to the negative terminal of the fourth diode, the negative terminal of the sixth diode is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the positive terminal of the fifth diode, the negative terminal of the fifth diode is connected to the positive terminal of the energy storage battery and the positive terminal of the third diode, the negative terminal of the energy storage battery is grounded, the negative terminal of the third diode is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the positive terminal of the fourth diode, the two ends of the fourth resistor are connected to the input terminal of the overcharge and over-discharge detection module, and the two ends of the fifth resistor are connected to the input terminal of the overcharge and over-discharge detection module.

[0007] As a further aspect of the present invention: the overcharge and over-discharge detection module includes: The overcharge detection unit is used to detect whether continuous charging has reached a set first threshold (sufficient to turn on the seventh diode) when the voltage of the energy storage battery reaches a set upper limit threshold. When the threshold is reached, the first voltage signal is fed back to the signal detection and control module. The over-discharge detection unit is used to detect whether continuous discharge has reached a set second threshold (sufficient to turn on the eighth diode) when the voltage of the energy storage battery is lower than the set lower threshold. When the threshold is reached, the second voltage signal is fed back to the signal detection and control module. The input terminal of the overcharge detection unit is connected to the first output terminal of the main frame working module, and the output terminal of the overcharge detection unit is connected to the second input terminal of the signal detection and control module; the input terminal of the over-discharge detection unit is connected to the first output terminal of the main frame working module, and the output terminal of the over-discharge detection unit is connected to the second input terminal of the signal detection and control module.

[0008] As a further aspect of the present invention: the overcharge detection unit includes: The first differential amplifier circuit is used to obtain a first differential voltage signal and output it to the first detection trigger circuit when the energy storage battery is being charged. The first detection trigger circuit is used to feed back a first voltage signal to the signal detection and control module when the voltage of the energy storage battery reaches the upper limit threshold and a first differential voltage signal is input to charge the first capacitor. The input terminal of the first differential amplifier circuit is connected to the first output terminal of the main frame working module, the output terminal of the first differential amplifier circuit is connected to the input terminal of the first detection trigger circuit, and the output terminal of the first detection trigger circuit is connected to the second input terminal of the signal detection control module. The over-discharge detection unit includes: The second differential amplifier circuit is used to obtain a second differential voltage signal and output it to the second detection trigger circuit when the energy storage battery is discharging. The second detection trigger circuit is used to feed back the second voltage signal to the signal detection and control module when the voltage of the energy storage battery reaches the lower threshold and a second differential voltage signal is input to charge the second capacitor. The input terminal of the second differential amplifier circuit is connected to the first output terminal of the main frame working module, the output terminal of the second differential amplifier circuit is connected to the input terminal of the second detection trigger circuit, and the output terminal of the second detection trigger circuit is connected to the second input terminal of the signal detection control module. The first differential amplifier circuit and the second differential amplifier circuit have the same structure, as do the first detection trigger circuit and the second detection trigger circuit (although the structures are the same, the specific connections are different).

[0009] As a further embodiment of the present invention: the first differential amplifier circuit includes a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourth amplifier. One end of the tenth resistor is connected to the first output terminal of the main frame working module, one end of the eleventh resistor is connected to the first output terminal of the main frame working module, the other end of the tenth resistor is connected to one end of the thirteenth resistor and the inverting input of the fourth amplifier, the other end of the eleventh resistor is connected to one end of the twelfth resistor and the non-inverting input of the fourth amplifier, the other end of the twelfth resistor is grounded, and the output terminal of the fourth amplifier is connected to the other end of the thirteenth resistor and the input terminal of the first detection trigger circuit.

[0010] As a further embodiment of the present invention: the first detection trigger circuit includes a fifth amplifier, a third MOSFET, a fourteenth resistor, a first potentiometer, a first capacitor, a seventh diode, a sixteenth resistor, and a ninth diode. The non-inverting input of the fifth amplifier obtains the voltage of the energy storage battery, the inverting input of the fifth amplifier is connected to a first reference voltage, the output of the fifth amplifier is connected to the gate (G) of the third MOSFET, the drain (D) of the third MOSFET is connected to the output of the first differential amplifier circuit, the source (S) of the third MOSFET is connected to one end of the fourteenth resistor, the other end of the fourteenth resistor is connected to one end of the first potentiometer, the other end of the first potentiometer is connected to one end of the first capacitor and the cathode of the seventh diode, the other end of the first capacitor is grounded, the anode of the seventh diode is connected to one end of the sixteenth resistor, the other end of the sixteenth resistor is connected to the cathode of the ninth diode and the second input terminal of the signal detection and control module, and the anode of the ninth diode is grounded.

[0011] As a further embodiment of the present invention: the signal detection and control module includes a first resistor, a second resistor, a first amplifier, a third resistor, a microcontroller, a first transistor, a second transistor, a first relay, a second relay, a second diode, and an eleventh diode. One end of the first resistor is connected to the second output terminal of the main frame working module, and the other end of the first resistor is connected to one end of the second resistor and the non-inverting input of the first amplifier. The other end of the second resistor is grounded. The output terminal of the first amplifier is connected to the inverting input of the first amplifier, one end of the third resistor, and the IO1 interface of the microcontroller. The other end of the third resistor is grounded. The microcontroller's IO2 and IO3 interfaces are connected to the output terminals of the overcharge and over-discharge detection module. The microcontroller's IO4 interface is connected to the base of the first transistor. The emitter of the first transistor is grounded. The collector of the first transistor is connected to one end of the first relay and the anode of the eleventh diode. The other end of the first relay is connected to the cathode of the eleventh diode and the power supply voltage. The microcontroller's IO5 interface is connected to the base of the second transistor. The emitter of the second transistor is grounded. The collector of the second transistor is connected to one end of the second relay and the anode of the second diode. The other end of the second relay is connected to the cathode of the second diode and the power supply voltage.

[0012] Compared with existing technologies, the advantages of this invention are as follows: This invention monitors the charging and discharging state of the energy storage battery in real time through an overcharge and over-discharge detection module, determines whether overcharging or over-discharging has occurred, and feeds back the corresponding signals to the signal detection and control module. Based on this feedback, the signal detection and control module dynamically adjusts the conduction relationship between the main frame working module, the electrical load, and the mains power supply module, thereby effectively preventing overcharging and over-discharging of the energy storage battery, fully utilizing the power generation capacity of the solar cells, and ensuring a continuous and reliable power supply to the electrical load. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a photovoltaic power generation control circuit.

[0014] Figure 2 This is a circuit diagram of the main frame working module, the overcharge and over-discharge detection module, and the first part of the signal detection and control module.

[0015] Figure 3 This is the circuit diagram for the second part, the signal detection and control module. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1 A photovoltaic power generation control circuit, comprising: The main frame working module 1 is used to convert the output voltage of solar cell E1 into 400V DC power and input it to the 400V DC bus, and then convert the 400V DC power into 220V AC power to power the load. When the output power of solar cell E1 exceeds the power demand of the load, the 400V DC power is stepped down to charge the energy storage battery E2. When the output power of solar cell E1 is lower than the power demand of the load, the energy storage battery E2 is stepped up to output 400V DC power to the 400V DC bus. The overcharge and over-discharge detection module 2 is used to detect whether the energy storage battery E2 is overcharged. If it is, it feeds back a first voltage signal to the signal detection and control module 3. It also detects whether the energy storage battery E2 is over-discharged. If it is, it feeds back a second voltage signal to the signal detection and control module 3. The signal detection and control module 3 is used to monitor the voltage change on the 400V DC bus and determine the current power demand change of the electrical load (real-time monitoring of minute changes in the 400V DC bus voltage, automatically adjusting the working mode and power of the bidirectional DC-DC converter, i.e., boost or buck), to adjust the charging and discharging of the energy storage battery E2; when it receives the first voltage signal from the overcharge and over-discharge detection module 2, it connects the output 220V AC power to the mains power supply module; when it receives the second voltage signal from the overcharge and over-discharge detection module 2, it disconnects the power supply circuit between the main frame working module 1 and the electrical load, and establishes the power supply circuit between the mains power supply module and the electrical load; The first output terminal of the main frame working module 1 is connected to the input terminal of the overcharge and over-discharge detection module 2 (at the fourth resistor R4 and the fifth resistor R5). The second output terminal of the main frame working module 1 is connected to the first input terminal of the signal detection and control module 3 (at the 400V DC bus). The output terminal of the overcharge and over-discharge detection module 2 is connected to the second input terminal of the signal detection and control module 3 (at the IO2 and IO3 interfaces of the microcontroller U2). The output terminal of the signal detection and control module 3 is connected to the input terminal of the main frame working module 1 (the microcontroller U2 controls the switch through a relay).

[0018] In this embodiment: Please refer to Figure 2 The main frame working module 1 includes a solar cell E1, a first diode D1, a first switch S1, a second switch S2, a third switch S3, a fourth resistor R4, a fifth resistor R5, an energy storage battery E2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6. The negative terminal of the solar cell E1 is grounded, and the positive terminal of the solar cell E1 is connected to the positive terminal of the first diode D1. The negative terminal of the first diode D1 is connected to the first terminal of the DC-DC boost converter. The second terminal of the DC-DC boost converter is connected to the 400V DC bus. The 400V DC bus is connected to the first terminal of the DC-AC inverter, the first terminal of the bidirectional DC-DC converter, and the first input terminal of the signal detection and control module 3. The second terminal of the DC-AC inverter is connected to the electrical load through the second switch S2. The third terminal of the DC-AC inverter is connected to the mains power supply module through the first switch S1. The mains power supply module is connected to the electrical load through the third switch S3. The second terminal of the bidirectional DC-DC converter is connected to the positive terminal of the sixth diode D6. The third terminal of the bidirectional DC-DC converter is connected to the negative terminal of the fourth diode D4. The negative terminal of the sixth diode D6 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the positive terminal of the fifth diode D5. The negative terminal of the fifth diode D5 is connected to the positive terminal of the energy storage battery E2 and the positive terminal of the third diode D3. The negative terminal of the energy storage battery E2 is grounded. The negative terminal of the third diode D3 is connected to one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to the positive terminal of the fourth diode D4. The two ends of the fourth resistor R4 are connected to the input terminal of the overcharge and over-discharge detection module 2. The two ends of the fifth resistor R5 are connected to the input terminal of the overcharge and over-discharge detection module 2.

[0019] When solar cell E1 provides sufficient power, its output voltage is converted into 400V DC by a DC-DC boost converter and then output to the electrical load via a DC-AC inverter. Since the electrical load is insufficient to consume the output power of solar cell E1, the bidirectional DC-DC converter operates to convert the 400V DC into low-voltage DC, which charges the energy storage battery E2 through the sixth diode D6, the fifth resistor R5, and the fifth diode D5. When the power supply from solar cell E1 is insufficient, the output voltage of solar cell E1 is converted into 400V DC through a DC-DC boost converter. The bidirectional DC-DC converter then converts the voltage output from energy storage battery E2 into 400V DC. The 400V DC is then output as 200V AC through a DC-AC inverter to the electrical load.

[0020] In another embodiment: multiple solar cells E1 and energy storage batteries E2 may be provided.

[0021] In this embodiment: Please refer to Figure 2 and Figure 3 The overcharge and over-discharge detection module 2 includes: The overcharge detection unit is used to detect whether continuous charging has reached a set first threshold (sufficient to turn on the seventh diode D7) when the voltage of the energy storage battery E2 reaches the set upper limit threshold. When the threshold is reached, the first voltage signal is fed back to the signal detection and control module 3. The over-discharge detection unit is used to detect whether continuous discharge has reached the set second threshold (sufficient to turn on the eighth diode D8) when the voltage of the energy storage battery E2 is lower than the set lower threshold. When the threshold is reached, the second voltage signal is fed back to the signal detection and control module 3. The input terminal of the overcharge detection unit is connected to the first output terminal of the main frame working module 1, and the output terminal of the overcharge detection unit is connected to the second input terminal of the signal detection and control module 3; the input terminal of the over-discharge detection unit is connected to the first output terminal of the main frame working module 1, and the output terminal of the over-discharge detection unit is connected to the second input terminal of the signal detection and control module 3.

[0022] In this embodiment: Please refer to Figure 2 and Figure 3 The overcharge detection unit includes: The first differential amplifier circuit is used to obtain a first differential voltage signal and output it to the first detection trigger circuit when the energy storage battery E2 is being charged. The first detection trigger circuit is used to feed back a first voltage signal to the signal detection and control module 3 when the voltage of the energy storage battery E2 reaches the upper limit threshold and a first differential voltage signal is input to charge the first capacitor C1. The input terminal of the first differential amplifier circuit is connected to the first output terminal of the main frame working module 1, the output terminal of the first differential amplifier circuit is connected to the input terminal of the first detection trigger circuit, and the output terminal of the first detection trigger circuit is connected to the second input terminal of the signal detection control module 3. The over-discharge detection unit includes: The second differential amplifier circuit is used to obtain a second differential voltage signal and output it to the second detection trigger circuit when the energy storage battery E2 is discharging. The second detection trigger circuit is used to feed back the second voltage signal to the signal detection and control module 3 when the voltage of the energy storage battery E2 reaches the lower threshold and a second differential voltage signal is input to charge the second capacitor C2. The input terminal of the second differential amplifier circuit is connected to the first output terminal of the main frame working module 1, the output terminal of the second differential amplifier circuit is connected to the input terminal of the second detection trigger circuit, and the output terminal of the second detection trigger circuit is connected to the second input terminal of the signal detection control module 3. The first differential amplifier circuit and the second differential amplifier circuit have the same structure, as do the first detection trigger circuit and the second detection trigger circuit (although the structures are the same, the specific connections are different).

[0023] In this embodiment: Please refer to Figure 2 and Figure 3The first differential amplifier circuit includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a fourth amplifier U4. One end of the tenth resistor R10 is connected to the first output terminal of the main frame working module 1, one end of the eleventh resistor R11 is connected to the first output terminal of the main frame working module 1, the other end of the tenth resistor R10 is connected to one end of the thirteenth resistor R13 and the inverting input of the fourth amplifier U4, the other end of the eleventh resistor R11 is connected to one end of the twelfth resistor R12 and the non-inverting input of the fourth amplifier U4, the other end of the twelfth resistor R12 is grounded, and the output terminal of the fourth amplifier U4 is connected to the other end of the thirteenth resistor R13 and the input terminal of the first detection trigger circuit.

[0024] When the energy storage battery E2 is charging, current flows through the fifth resistor R5. After passing through the first differential amplifier circuit, it is converted into a voltage signal and output to the first detection trigger circuit.

[0025] Please see Figure 2 The second differential amplifier circuit includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a third amplifier U3. The second differential amplifier circuit has the same structure as the first differential amplifier circuit, the difference being that the non-inverting and inverting inputs of the amplifier are connected in opposite directions (this is because the charging and discharging directions of the energy storage battery E2 are opposite).

[0026] In another embodiment: the power supply for the third amplifier U3 and the fourth amplifier U4 can be provided by the energy storage battery E2.

[0027] In this embodiment: Please refer to Figure 2 and Figure 3 The first detection trigger circuit includes a fifth amplifier U5, a third MOSFET V3, a fourteenth resistor R14, a first potentiometer RP1, a first capacitor C1, a seventh diode D7, a sixteenth resistor R16, and a ninth diode D9. The non-inverting input of the fifth amplifier U5 obtains the voltage of the energy storage battery E2, and the inverting input of the fifth amplifier U5 is connected to the first reference voltage VREF1. The output of the fifth amplifier U5 is connected to the gate (G) of the third MOSFET V3, and the drain (D) of the third MOSFET V3 is connected to the output of the first differential amplifier circuit. The source (S) of the third MOSFET V3 is connected to one end of the fourteenth resistor R14, and the other end of the fourteenth resistor R14 is connected to one end of the first potentiometer RP1. The other end of the first potentiometer RP1 is connected to one end of the first capacitor C1 and the negative terminal of the seventh diode D7. The other end of the first capacitor C1 is grounded. The positive terminal of the seventh diode D7 is connected to one end of the sixteenth resistor R16, and the other end of the sixteenth resistor R16 is connected to the negative terminal of the ninth diode D9 and the second input terminal of the signal detection and control module 3. The positive terminal of the ninth diode D9 is grounded.

[0028] The common point A3 is connected to the positive terminal of the energy storage battery E2, reflecting the voltage of the energy storage battery E2. If the voltage of the energy storage battery E2 is higher than the first reference voltage VREF1 (the set upper limit threshold), it indicates that the energy storage battery E2 is fully charged, and the third MOSFET V3 is turned on. If there is a continuous voltage input at the common point A1 (indicating that the energy storage battery E2 is still being charged), the voltage charges the first capacitor C1 through the third MOSFET V3, the fourteenth resistor R14, and the first potentiometer RP1. If the voltage on the first capacitor C1 is sufficient to turn on the seventh diode D7 (Zen diode), it indicates that the energy storage battery E2 may be overcharged and charging should be stopped immediately. At this time, a signal is fed back to the IO2 interface of the microcontroller U2.

[0029] The second detection trigger circuit includes a sixth amplifier U6, a fourth MOSFET V4, a fifteenth resistor R15, a second potentiometer RP2, a second capacitor C2, an eighth diode D8, a seventeenth resistor R17, and a tenth diode D10. The first and second detection trigger circuits have the same structure, the difference being that the voltages connected to the non-inverting and inverting inputs of the amplifiers are different. When the voltage of the energy storage battery E2 is lower than the second reference voltage VREF2 (the set lower threshold), the second trigger circuit controls the fourth MOSFET V4 to conduct. If the energy storage battery E2 continues to discharge at this time, causing the second capacitor C2 to charge sufficiently to conduct the eighth diode D8 (Zen timer diode), a feedback signal is sent to the IO3 interface of the microcontroller U2.

[0030] In another embodiment: Here, it is determined whether the energy storage battery E2 is overcharged or over-discharged by whether the capacitor is charged enough to turn on the Zener diode. It can also be set to a fixed delay for judgment, but this detection is not accurate enough and cannot judge the charging and discharging current of the energy storage battery E2.

[0031] In this embodiment: Please refer to Figure 2The signal detection and control module 3 includes a first resistor R1, a second resistor R2, a first amplifier U1, a third resistor R3, a microcontroller U2, a first transistor V1, a second transistor V2, a first relay J1, a second relay J2, a second diode D2, and an eleventh diode D11. One end of the first resistor R1 is connected to the second output terminal of the main frame working module 1, and the other end of the first resistor R1 is connected to one end of the second resistor R2 and the non-inverting input of the first amplifier U1. The other end of the second resistor R2 is grounded. The output terminal of the first amplifier U1 is connected to the inverting input of the first amplifier U1, one end of the third resistor R3, and the IO1 interface of the microcontroller U2. The other end of the third resistor R3 is grounded. The O2 and IO3 interfaces are connected to the output terminals of the overcharge and over-discharge detection module 2. The IO4 interface of the microcontroller U2 is connected to the base of the first transistor V1. The emitter of the first transistor V1 is grounded. The collector of the first transistor V1 is connected to one end of the first relay J1 and the positive terminal of the eleventh diode D11. The other end of the first relay J1 is connected to the negative terminal of the eleventh diode D11 and the power supply voltage VCC. The IO5 interface of the microcontroller U2 is connected to the base of the second transistor V2. The emitter of the second transistor V2 is grounded. The collector of the second transistor V2 is connected to one end of the second relay J2 and the positive terminal of the second diode D2. The other end of the second relay J2 is connected to the negative terminal of the second diode D2 and the power supply voltage VCC.

[0032] The operating logic of the DC-DC boost converter, bidirectional DC-DC converter, and DC-AC inverter is as follows: Changes in the 400V DC bus voltage are detected through the first resistor R1 and the second resistor R2. This data is then fed back to the microcontroller U2 via the first amplifier U1 (used as a follower). This means the 400V DC bus voltage is sampled in real time. If the voltage deviates from the set value, indicating a power supply-demand imbalance, the microcontroller U2 immediately calculates the power deficit and prioritizes scheduling the bidirectional DC-DC converter: when the voltage drops, it instructs the energy storage battery E2 to boost and discharge, injecting current; when the voltage rises, it steps down to absorb current and charge the energy storage battery E2. Simultaneously, it coordinates with the DC-DC boost converter at the solar cell E1, adjusting the photovoltaic power generation by changing the MPPT operating point. The output of the DC-AC inverter is determined by the electrical load. The microcontroller U2 uses feedback or the bus voltage to infer the load demand. Through the coordinated control of these three components, the total power injected into the 400V DC bus is always equal to the power consumed by the electrical load, thus dynamically stabilizing the DC bus voltage at 400V. Using microcontrollers to control various voltage converters based on signals and to collect the power demand of electrical loads is a common technique, which will not be elaborated here.

[0033] The operating logic for controlling the first switch S1, the second switch S2, and the third switch S3 is as follows: the first switch S1 and the third switch S3 are normally closed, and the second switch S2 is normally open. When a voltage signal is received at the IO2 interface, it indicates that the energy storage battery E2 is overcharged. At this time, the microcontroller U2 controls the IO4 interface to output a high level, the first transistor V1 conducts, the first relay J1 operates, and the first switch S1 is closed. This allows the voltage of the 400V DC bus to supply power to the electrical load through the DC-AC inverter, while the excess electrical energy is transferred to the mains power supply module through the first switch S1, making full use of solar power generation. The energy storage battery E2 stops charging. The closing time of the first switch S1 depends on the power generation of the solar cell E1. When the power supply of the solar cell E1 is insufficient to meet the power demand of the electrical load, the IO4 of the microcontroller U2 stops outputting a high level, the first relay J1 stops working, and the first switch S1 opens. When a voltage signal is received at the IO3 interface, it indicates that the energy storage battery E2 is over-discharged. At this time, the microcontroller U2 controls IO5 to output a high level, which controls the second relay J2 to work, causing the second switch S2 to open and the third switch S3 to close. The mains power supply module (i.e., the mains voltage) supplies power to the load, and the energy storage battery E2 stops discharging. At this time, the second switch S2 opens, and the solar cell E1 charges the energy storage battery E2. When the voltage of the energy storage battery E2 returns to the upper limit threshold, the microcontroller U2 obtains this information through the IO6 interface, controls the IO5 interface to stop outputting a high level, the second relay J2 stops working, the second switch S2 closes, and the third switch S3 opens, restoring the initial state.

[0034] In another embodiment: the relay here can also be replaced with a time relay, which automatically disconnects after a certain period of operation. The disadvantage is that if the energy storage battery E2 is still overcharged or over-discharged after the time relay disconnects, the time relay will immediately start again, resulting in unnecessary switching. If the automatic disconnection time of the time relay is set too long, the power generation of the solar cell E1 will not be fully utilized.

[0035] The working principle of this invention is as follows: The main frame working module 1 is used to convert the output voltage of the solar cell E1 into 400V DC power and input it to the 400V DC bus, and then convert the 400V DC power into 220V AC power to supply power to the electrical load; when the output power of the solar cell E1 exceeds the power demand of the electrical load, the 400V DC power is stepped down to charge the energy storage battery E2; when the output power of the solar cell E1 is lower than the power demand of the electrical load, the energy storage battery E2 is stepped up to output 400V DC power to the 400V DC bus; the overcharge and over-discharge detection module 2 is used to detect whether the energy storage battery E2 is overcharged. If so, it feeds back a first voltage signal to the signal detection and control module 3; the over-discharge detection module 3 detects whether the energy storage battery E2 is over-discharged. When the overcharge and over-discharge detection module 2 is received, a second voltage signal is fed back to the signal detection and control module 3. The signal detection and control module 3 is used to monitor the voltage change on the 400V DC bus and determine the current power demand change of the electrical load (real-time monitoring of small changes in the 400V DC bus voltage, automatically adjusting the working mode and power of the bidirectional DC-DC converter, i.e., boost or buck), to adjust the charging and discharging of the energy storage battery E2. When the first voltage signal of the overcharge and over-discharge detection module 2 is received, the output 220V AC power is connected to the mains power supply module. When the second voltage signal of the overcharge and over-discharge detection module 2 is received, the power supply circuit between the main frame working module 1 and the electrical load is disconnected, and the power supply circuit between the mains power supply module and the electrical load is constructed.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and not restrictive.

[0037] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A photovoltaic power generation control circuit, characterized in that, The photovoltaic power generation control circuit includes: The main frame working module is used to convert the output voltage of the solar cell into 400V DC power and input it to the 400V DC bus. Then, the 400V DC power is converted into 220V AC power to supply power to the electrical load. When the output power of the solar cell exceeds the power demand of the electrical load, the 400V DC power is stepped down to charge the energy storage battery. When the output power of the solar cell is lower than the power demand of the electrical load, the energy storage battery is stepped up to output 400V DC power to the 400V DC bus. The overcharge and over-discharge detection module is used to detect whether the energy storage battery is overcharged. If so, it feeds back a first voltage signal to the signal detection and control module. It also detects whether the energy storage battery is over-discharged. If so, it feeds back a second voltage signal to the signal detection and control module. The signal detection and control module is used to monitor the voltage changes on the 400V DC bus, determine the changes in the current power demand of the electrical load, and adjust the charging and discharging of the energy storage battery accordingly. When it receives the first voltage signal from the overcharge and over-discharge detection module, it connects the output 220V AC power to the mains power supply module. When it receives the second voltage signal from the overcharge and over-discharge detection module, it disconnects the power supply circuit between the main frame working module and the electrical load, and establishes a power supply circuit between the mains power supply module and the electrical load. The first output terminal of the main frame working module is connected to the input terminal of the overcharge and over-discharge detection module, the second output terminal of the main frame working module is connected to the first input terminal of the signal detection and control module, the output terminal of the overcharge and over-discharge detection module is connected to the second input terminal of the signal detection and control module, and the output terminal of the signal detection and control module is connected to the input terminal of the main frame working module. The overcharge and over-discharge detection module includes: The overcharge detection unit is used to detect whether continuous charging has reached a set first threshold when the voltage of the energy storage battery reaches a set upper limit threshold. When the threshold is reached, the unit feeds back a first voltage signal to the signal detection and control module. The overcharge detection unit includes: The first differential amplifier circuit is used to obtain a first differential voltage signal and output it to the first detection trigger circuit when the energy storage battery is being charged. The first detection trigger circuit is used to feed back a first voltage signal to the signal detection and control module when the voltage of the energy storage battery reaches the upper limit threshold and a first differential voltage signal is input to charge the first capacitor. The input terminal of the first differential amplifier circuit is connected to the first output terminal of the main frame working module, the output terminal of the first differential amplifier circuit is connected to the input terminal of the first detection trigger circuit, and the output terminal of the first detection trigger circuit is connected to the second input terminal of the signal detection control module.

2. The photovoltaic power generation control circuit according to claim 1, characterized in that, The main frame working module includes a solar cell, a first diode, a first switch, a second switch, a third switch, a fourth resistor, a fifth resistor, an energy storage battery, a third diode, a fourth diode, a fifth diode, and a sixth diode. The negative terminal of the solar cell is grounded, the positive terminal of the solar cell is connected to the positive terminal of the first diode, the negative terminal of the first diode is connected to the first terminal of the DC-DC boost converter, the second terminal of the DC-DC boost converter is connected to the 400V DC bus, the 400V DC bus is connected to the first terminal of the DC-AC inverter, the first terminal of the bidirectional DC-DC converter, and the first input terminal of the signal detection and control module, the second terminal of the DC-AC inverter is connected to the electrical load through the second switch, the third terminal of the DC-AC inverter is connected to the mains power supply module through the first switch, and the mains power supply module is connected to the electrical load through the third switch. The second terminal of the bidirectional DC-DC converter is connected to the positive terminal of the sixth diode, the third terminal of the bidirectional DC-DC converter is connected to the negative terminal of the fourth diode, the negative terminal of the sixth diode is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the positive terminal of the fifth diode, the negative terminal of the fifth diode is connected to the positive terminal of the energy storage battery and the positive terminal of the third diode, the negative terminal of the energy storage battery is grounded, the negative terminal of the third diode is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the positive terminal of the fourth diode, the two ends of the fourth resistor are connected to the input terminal of the overcharge and over-discharge detection module, and the two ends of the fifth resistor are connected to the input terminal of the overcharge and over-discharge detection module.

3. The photovoltaic power generation control circuit according to claim 1, characterized in that, The overcharge and over-discharge detection module also includes: The over-discharge detection unit is used to detect whether continuous discharge has reached a set second threshold when the voltage of the energy storage battery is lower than the set lower threshold. When the threshold is reached, the second voltage signal is fed back to the signal detection and control module. The input terminal of the overcharge detection unit is connected to the first output terminal of the main frame working module, and the output terminal of the overcharge detection unit is connected to the second input terminal of the signal detection and control module; the input terminal of the over-discharge detection unit is connected to the first output terminal of the main frame working module, and the output terminal of the over-discharge detection unit is connected to the second input terminal of the signal detection and control module.

4. The photovoltaic power generation control circuit according to claim 3, characterized in that, The over-discharge detection unit includes: The second differential amplifier circuit is used to obtain a second differential voltage signal and output it to the second detection trigger circuit when the energy storage battery is discharging. The second detection trigger circuit is used to feed back the second voltage signal to the signal detection and control module when the voltage of the energy storage battery reaches the lower threshold and a second differential voltage signal is input to charge the second capacitor. The input terminal of the second differential amplifier circuit is connected to the first output terminal of the main frame working module, the output terminal of the second differential amplifier circuit is connected to the input terminal of the second detection trigger circuit, and the output terminal of the second detection trigger circuit is connected to the second input terminal of the signal detection control module. The first differential amplifier circuit and the second differential amplifier circuit have the same structure, as do the first detection trigger circuit and the second detection trigger circuit.

5. The photovoltaic power generation control circuit according to claim 4, characterized in that, The first differential amplifier circuit includes a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourth amplifier. One end of the tenth resistor is connected to the first output terminal of the main frame working module, one end of the eleventh resistor is connected to the first output terminal of the main frame working module, the other end of the tenth resistor is connected to one end of the thirteenth resistor and the inverting input of the fourth amplifier, the other end of the eleventh resistor is connected to one end of the twelfth resistor and the non-inverting input of the fourth amplifier, the other end of the twelfth resistor is grounded, and the output terminal of the fourth amplifier is connected to the other end of the thirteenth resistor and the input terminal of the first detection trigger circuit.

6. The photovoltaic power generation control circuit according to claim 4, characterized in that, The first detection trigger circuit includes a fifth amplifier, a third MOSFET, a fourteenth resistor, a first potentiometer, a first capacitor, a seventh diode, a sixteenth resistor, and a ninth diode. The non-inverting input of the fifth amplifier obtains the voltage of the energy storage battery, the inverting input of the fifth amplifier is connected to the first reference voltage, the output of the fifth amplifier is connected to the gate (G) of the third MOSFET, the drain (D) of the third MOSFET is connected to the output of the first differential amplifier circuit, the source (S) of the third MOSFET is connected to one end of the fourteenth resistor, the other end of the fourteenth resistor is connected to one end of the first potentiometer, the other end of the first potentiometer is connected to one end of the first capacitor and the cathode of the seventh diode, the other end of the first capacitor is grounded, the anode of the seventh diode is connected to one end of the sixteenth resistor, the other end of the sixteenth resistor is connected to the cathode of the ninth diode and the second input terminal of the signal detection and control module, and the anode of the ninth diode is grounded.

7. The photovoltaic power generation control circuit according to any one of claims 1 to 6, characterized in that, The signal detection and control module includes a first resistor, a second resistor, a first amplifier, a third resistor, a microcontroller, a first transistor, a second transistor, a first relay, a second relay, a second diode, and an eleventh diode. One end of the first resistor is connected to the second output terminal of the main frame working module, and the other end of the first resistor is connected to one end of the second resistor and the non-inverting input of the first amplifier. The other end of the second resistor is grounded. The output terminal of the first amplifier is connected to the inverting input of the first amplifier, one end of the third resistor, and the IO1 interface of the microcontroller. The other end of the third resistor is grounded. The IO2 and IO3 interfaces of the microcontroller are also connected. The O3 interface connects to the output of the overcharge and over-discharge detection module. The microcontroller's IO4 interface connects to the base of the first transistor. The emitter of the first transistor is grounded. The collector of the first transistor connects to one end of the first relay and the anode of the eleventh diode. The other end of the first relay connects to the cathode of the eleventh diode and the power supply voltage. The microcontroller's IO5 interface connects to the base of the second transistor. The emitter of the second transistor is grounded. The collector of the second transistor connects to one end of the second relay and the anode of the second diode. The other end of the second relay connects to the cathode of the second diode and the power supply voltage.

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