Photovoltaic power supply circuit and photovoltaic power supply control method

Abstract

The application discloses a photovoltaic power supply circuit and a photovoltaic power supply control method. The photovoltaic power supply control method determines the charging stage of a battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, finds the target charging parameter corresponding to the charging stage according to a mapping relationship, generates a control signal based on the target power supply mode and the target charging parameter, and generates a driving signal for driving an input bridge arm and an output bridge arm based on the control signal. The photovoltaic power supply control method can consider the efficient conversion of photovoltaic power and the safe charging of the battery by only collecting the single data, i.e. the positive electrode voltage of the battery, so that a better dynamic balance between the energy capture efficiency and the safe service life of the battery can be achieved by collecting less data.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic charging, in particular to a photovoltaic power supply circuit and a photovoltaic power supply control method. BACKGROUND

[0002] Photovoltaic charging often regards Maximum Power Point Tracking (MPPT) and battery charging management as two relatively independent problems. MPPT algorithms aim to obtain maximum power from photovoltaic panels, while charging management focuses on protecting the battery. There is a lack of coordination between the two, which may cause the system to impact the battery when pursuing maximum power (such as applying excessive current when the battery voltage is too low), or sacrifice the efficiency of photovoltaic energy capture when protecting the battery.

[0003] Therefore, photovoltaic charging schemes are difficult to achieve a better dynamic balance between energy capture efficiency and battery safety life. SUMMARY

[0004] The present application provides a photovoltaic power supply circuit and a photovoltaic power supply control method to alleviate the above technical problems.

[0005] In a first aspect, the present application provides a photovoltaic power supply control method applied to a photovoltaic power supply circuit, the photovoltaic power supply circuit comprising an input bridge arm, a first inductor, and an output bridge arm, the input bridge arm being connected between a positive electrode of a photovoltaic module and a ground terminal, the first inductor being connected between a midpoint of the input bridge arm and a midpoint of the output bridge arm, the output bridge arm being connected between a positive electrode of a battery and a ground terminal, the photovoltaic power supply control method comprising: determining a charging stage of the battery and a target power supply mode of the photovoltaic power supply circuit based on a positive electrode voltage of the battery; finding a target charging parameter corresponding to the charging stage according to a mapping relationship; generating a control signal based on the target power supply mode and the target charging parameter; and generating a driving signal for driving the input bridge arm and the output bridge arm based on the control signal.

[0006] In a second aspect, the present application provides a photovoltaic power supply circuit for executing the above photovoltaic power supply control method.

[0007] The photovoltaic power supply circuit and the photovoltaic power supply control method provided by the present application can achieve a better dynamic balance between energy capture efficiency and battery safety life with less collected data by determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, finding the target charging parameter corresponding to the charging stage according to the mapping relationship, generating the control signal based on the target power supply mode and the target charging parameter, and generating the driving signal for driving the input bridge arm and the output bridge arm based on the control signal. Attached Figure Description

[0008] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 The first circuit diagram of the photovoltaic power supply circuit provided in the embodiments of this application is shown.

[0010] Figure 2 This is a second circuit diagram of a photovoltaic power supply circuit provided in an embodiment of this application.

[0011] Figure 3 This is a flowchart illustrating the photovoltaic power supply control method provided in an embodiment of this application. Detailed Implementation

[0012] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0013] 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. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0014] like Figure 1 As shown, this embodiment provides a photovoltaic power supply circuit 100, which includes an input bridge arm 10, a first inductor L1, and an output bridge arm 20. The input bridge arm 10 is connected between the positive terminal PV+ of the photovoltaic module and the ground terminal GND. The first inductor L1 is connected between the midpoint of the input bridge arm 10 and the midpoint of the output bridge arm 20. The output bridge arm 20 is connected between the positive terminal BAT+ of the battery and the ground terminal GND. The negative terminal PV- of the photovoltaic module is connected to the ground terminal GND through a first resistor R1.

[0015] It should be noted that in this embodiment, different voltage relationships are constructed on the first inductor L1 through the input bridge arm 10 and the output bridge arm 20, so that the output voltage of the photovoltaic module can be boosted and bucked. This can make full use of the all-weather photovoltaic power generation resources from the weak light (low voltage) at dawn to the strong light (high voltage) at noon, greatly expanding the operating voltage window of the system and avoiding energy waste caused by voltage mismatch.

[0016] In some embodiments, such as Figure 1 As shown, input bridge arm 10 includes a first transistor Q1 and a second transistor Q2. The first transistor Q1 is connected between the positive terminal PV+ of the photovoltaic module and the midpoint of input bridge arm 10, and its gate is connected to a first control signal. The second transistor Q2 is connected between the midpoint of input bridge arm 10 and ground GND, and its gate is connected to a second control signal. Output bridge arm 20 includes a third transistor Q3 and a fourth transistor Q4. The third transistor Q3 is connected between the positive terminal BAT+ of the battery and the midpoint of output bridge arm 20, and its gate is connected to a third control signal. The fourth transistor Q4 is connected between the midpoint of output bridge arm 20 and ground GND, and its gate is connected to a fourth control signal.

[0017] It should be noted that the gate has parasitic capacitance, which, together with the parasitic inductance in the drive circuit, may create LC oscillations. Each transistor's gate can also be connected in series with a resistor, which can effectively dampen this high-frequency oscillation and prevent damage to the gate oxide layer due to overshoot voltage. The resistor value affects the charging and discharging speed of the gate capacitance. Choosing an appropriate resistor value can adjust the turn-on and turn-off times of the switching transistor, helping to achieve a balance between switching losses and electromagnetic interference (EMI).

[0018] Another resistor can be connected between the gate and source of each transistor to ensure that the gate charge can be quickly released when the driver output is in a high-impedance state, enabling the switch to be reliably turned off and preventing false turn-on. Providing a defined bias to the gate improves noise immunity, especially in static or standby states, preventing accidental turn-on of the switch due to external interference.

[0019] This embodiment independently controls the level and timing of four signals (first to fourth control signals), and can precisely construct three energy transmission paths—Buck, Boost, and Buck-Boost—through the first to fourth transistors Q4, laying the hardware foundation for subsequent wide-range voltage adaptation.

[0020] In some embodiments, such as Figure 2As shown, the photovoltaic power supply circuit 100 further comprises a control module 70, an RC absorption module 30, a first RC controllable absorption module 40, and a second RC controllable absorption module 50. The control module 70 is configured to generate a first switch signal and a second switch signal according to a target power supply mode. Each RC absorption module 30 is connected in parallel between the drain and the source of each transistor in the input bridge arm 10 and the output bridge arm 20. The first RC controllable absorption module 40 is connected between the positive pole PV+ of the photovoltaic module and the midpoint of the input bridge arm 10, and is controlled by the first switch signal. The second RC controllable absorption module 50 is connected between the positive pole BAT+ of the battery and the midpoint of the output bridge arm 20, and is controlled by the second switch signal.

[0021] It should be noted that the control module 70 is configured to generate a control signal according to the voltage of the positive pole BAT+ of the battery. In some embodiments, the control module 70 can further generate a driving signal for driving the input bridge arm 10 and the output bridge arm 20 directly according to the control signal. In other embodiments, the photovoltaic power supply circuit 100 can further comprise a driver configured to generate a driving signal for driving the input bridge arm 10 and the output bridge arm 20 according to the control signal.

[0022] In some embodiments, as shown in FIG. 2, the RC absorption module 30 comprises a first capacitor C1 and a second resistor R2 connected in series. Figure 2

[0023] In some embodiments, the first RC controllable absorption module 40 and the second RC controllable absorption module 50 can each be formed by connecting a MOS tube in series with the RC absorption module 30. In the first RC controllable absorption module 40, the gate of the MOS tube is connected to the first switch signal. In the second RC controllable absorption module 50, the gate of the MOS tube is connected to the second switch signal.

[0024] It should be noted that, in order to solve the problem of constant power loss caused by traditional fixed RC absorption, the present embodiment makes the RC absorption controllable according to the actual power supply mode, so as to intelligently enhance or weaken the absorption effect, thereby achieving a dynamic balance between suppressing voltage spikes and reducing switching loss.

[0025] The RC absorption module 30 provides basic and continuous voltage spike absorption for each switch tube. No matter what mode the photovoltaic power supply circuit 100 works in, these basic absorption networks are always working, ensuring basic switching safety.

[0026] ​In the buck mode, the first transistor Q1 is the main switch tube and bears a large voltage stress. At this time, the first switch signal sent by the control module 70 can control the MOS tube in the first RC controllable absorption module 40 to be turned on, so as to access the first RC controllable absorption module 40, which can work with the basic absorption network of the first transistor Q1 itself and significantly enhance the suppression capability of the voltage spike when the first transistor Q1 is turned off.

[0027] In the boost mode, the third transistor Q3 is the main switch tube and bears a large stress. At this time, the second switch signal sent by the control module 70 can control the MOS tube in the second RC controllable absorption module 50 to be turned on, so as to access the second RC controllable absorption module 50, which can significantly enhance the suppression capability of the voltage spike when the third transistor Q3 is turned off. In other modes, the two controllable absorption modules can be turned off to avoid unnecessary loss.

[0028] The embodiment changes the traditional fixed absorption circuit "one-size-fits-all" mode, can strengthen the protection according to the switch tube (such as the first transistor Q1 in the buck mode and the third transistor Q3 in the boost mode) bearing the maximum voltage stress in actual operation, and improves the reliability of the system in extreme working conditions.

[0029] In the working condition without the need for strengthened absorption (for example, light load or when a certain switch tube is not the main stress tube), by turning off the corresponding controllable absorption module, the additional conduction loss on the resistor is avoided, thereby improving the overall energy conversion efficiency of the system.

[0030] In some embodiments, as shown in Figure 2 The photovoltaic power supply circuit 100 further includes a switching unit 60 which is turned on or turned off under the control of a bias voltage VB. It should be noted that the bias voltage VB can be externally provided or generated by the switching unit 60 itself.

[0031] In some embodiments, as shown in Figure 2 The switching unit 60 includes a first transistor, a second transistor, a fifth transistor Q5, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a second capacitor C2. The source of the fifth transistor Q5 is connected with the drain of the third transistor Q3, the emitter of the first transistor, and the first end of the second capacitor C2. The second end of the second capacitor C2 is connected with the first end of the fifth resistor R5 and the first end of the third resistor R3. The second end of the third resistor R3 is connected with the base of the first transistor, the base of the second transistor, and the emitter of the second transistor. The collector of the second transistor is connected with the drain of the fifth transistor Q5 and the anode of the battery. The second end of the fifth resistor R5 is connected with the first end of the fourth resistor R4 and the collector of the first transistor. The second end of the fourth resistor R4 is connected with the gate of the fifth transistor Q5.

[0032] It should be noted that the first transistor and the second transistor are both NPN type BJTs, and the two can be integrated into a dual-transistor chip, i.e., U1.

[0033] Initial state and bias establishment: when the photovoltaic module has no output or insufficient voltage, the gate of the fifth transistor Q5 has no driving voltage and is in an off state, and the entire charging circuit is cut off. When the light is sufficient, the photovoltaic module starts to generate electricity, and the voltage starts to establish a bias voltage VB through the drain of the third transistor Q3 and the second capacitor C2 and other paths.

[0034] When the bias voltage VB is high enough to make the circuit composed of the first transistor and the second transistor conduct, a current path is formed. The current flows through the fifth resistor R5 and the fourth resistor R4, and a voltage drop is generated on the fourth resistor R4, which is directly applied to the gate of the fifth transistor Q5 to drive the fifth transistor Q5 to conduct. After the fifth transistor Q5 is turned on, the main circuit of the battery charging is formally connected, and the system starts to work normally.

[0035] Shutdown and protection process (insufficient voltage or abnormality): when the light weakens or an abnormality occurs, causing the bias voltage VB to be insufficient, the first transistor and the second transistor cannot maintain conduction, the driving current to the gate of the fifth transistor Q5 disappears, and the fifth transistor Q5 is turned off, thereby cutting off the charging circuit.

[0036] Hardware self-start and voltage loss shutdown are achieved: the system does not need software intervention, and only the voltage generated by the photovoltaic can automatically establish the working condition and connect the main circuit, realizing the intelligent function of “self-starting with light and self-stopping without light”, simplifying the control logic and improving the reliability.

[0037] When there is no voltage or extremely low voltage on the photovoltaic side, the switching unit 60 can ensure that current cannot flow from the battery into the circuit system in the reverse direction, effectively preventing the battery power from being consumed in the reverse direction through the circuit (anti-rebound), and at the same time, physical isolation is achieved under different working conditions.

[0038] The switching unit 60 is a separate hardware protection unit, and its action does not depend on the main control chip. Even if the control system has a software failure, the basic safety can be guaranteed at the hardware level, and another reliable protection barrier is added to the entire power supply circuit.

[0039] In some embodiments, as shown in FIG. 6A, the switching unit 60 further includes a Zener diode ZD1 connected between the gate and the source of the fifth transistor Q5. Figure 2

[0040] It should be noted that the Zener diode ZD1 is connected between the gate and the source of the fifth transistor Q5, and plays a voltage clamping role to prevent the gate voltage from overshooting and damaging the fifth transistor Q5, which is an important protection element.​

[0041] In some embodiments, as shown in FIG. 1, the photovoltaic power supply circuit 100 further comprises a third capacitor C3 and a fourth capacitor C4, both of which are connected between the drain of the third transistor Q3 and the ground terminal GND. Figure 2

[0042] It should be noted that the third capacitor C3 can be a small-capacitance capacitor (such as a ceramic capacitor), which has very small equivalent series inductance (ESL) and equivalent series resistance (ESR) and can provide a low-impedance path for high-frequency noise current. The fourth capacitor C4 can be a large-capacitance capacitor (such as an electrolytic capacitor or a solid-state capacitor), which mainly functions to store energy and smooth large-amplitude voltage ripples caused by switching actions.

[0043] The comprehensive impedance-frequency characteristics of the third capacitor C3 and the fourth capacitor C4 in parallel remain at a low level in a wide frequency range. The fourth capacitor C4 is responsible for the medium and low frequency bands, and the third capacitor C3 is responsible for the high frequency band. The two complement each other to form an efficient wideband filter. In this way, various interferences from switching noise to power ripples can be effectively suppressed, and the stability and reliability of the system are comprehensively improved.

[0044] As shown in FIG. 2, the photovoltaic power supply control method comprises the following steps: Figure 3

[0045] Step S10: determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery.

[0046] Step S20: finding the target charging parameter corresponding to the charging stage according to the mapping relationship.

[0047] Step S30: generating a control signal based on the target power supply mode and the target charging parameter.

[0048] Step S40: generating a driving signal for driving the input bridge arm and the output bridge arm based on the control signal.

[0049] It can be understood that the photovoltaic power supply control method provided by the embodiment can determine the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, find the target charging parameter corresponding to the charging stage according to the mapping relationship, generate a control signal based on the target power supply mode and the target charging parameter, and generate a driving signal for driving the input bridge arm and the output bridge arm based on the control signal. The photovoltaic power supply control method can take into account the efficient conversion of photovoltaic power and the safe charging of the battery only by collecting the single data of the positive electrode voltage of the battery, so as to achieve a better dynamic balance between energy capture efficiency and battery safety life with less collected data.

[0050] ​​In some embodiments, the photovoltaic power supply control method further comprises: determining a charging stage of the battery according to a comparison result of the positive electrode voltage of the battery and a preset voltage threshold; determining an initial power supply mode of the photovoltaic power supply circuit according to the level data of the control signal; calculating an output voltage of the photovoltaic module according to the initial power supply mode and the positive electrode voltage of the battery; and determining a target power supply mode according to a comparison result of the output voltage of the photovoltaic module and the positive electrode voltage of the battery.

[0051] It should be noted that the control signal is generated by the control module, and therefore, the level data of the control signal can be stored in the control module for use in determining the initial power supply mode. The level data of the control signal can be a duty cycle and / or a phase, or a combination of high and low levels of a plurality of control signals in a time period.

[0052] The embodiment dynamically adjusts the charging stage and the power supply mode according to the positive electrode voltage of the battery, maximizes the utilization efficiency of photovoltaic energy under the premise of ensuring the safety of the battery, realizes intelligent energy management by relying only on the battery voltage and the level data of the control signal to adapt to changes in illumination and fluctuations in the state of the battery, reduces the need for voltage / current sampling of the photovoltaic module, reduces the system complexity and cost, and ensures accuracy through algorithm compensation.

[0053] In some embodiments, the charging stage comprises a trickle charging sub-stage, a constant current charging sub-stage and a constant voltage charging sub-stage, the preset voltage threshold comprises a first voltage threshold and a second voltage threshold that increase in turn, and the photovoltaic power supply control method further comprises: when the voltage of the battery is lower than the first voltage threshold, determining that the charging stage is the trickle charging sub-stage, and determining that the target charging parameter corresponding to the trickle charging sub-stage is a first target current value based on a mapping relationship; when the voltage of the battery is greater than or equal to the first voltage threshold and less than the second voltage threshold, determining that the charging stage is the constant current charging sub-stage, and determining that the target charging parameter corresponding to the constant current charging sub-stage is a second target current value based on the mapping relationship, the second target current value being greater than the first target current value; and when the voltage of the battery is greater than or equal to the second voltage threshold, determining that the charging stage is the constant voltage charging sub-stage, and determining that the target charging parameter corresponding to the constant voltage charging sub-stage is a first target voltage value based on the mapping relationship.

[0054] It should be noted that the first voltage threshold and the second voltage threshold (V_cc) can be preset based on the chemical properties of the battery (such as a lead-acid battery or a lithium battery) to distinguish the scales of the state of charge (SOC) and the state of health of the battery.

[0055] Trickle charging phase (repair charging): The system determines that the battery is in a deep discharge state, and if a large current is applied, it will cause damage to the battery. Therefore, the system enters the trickle charging phase and sets the target charging parameter to a small first target current value (e.g. 0.05C). This phase aims to safely wake up and repair the battery with a small current, so that the voltage slowly rises.

[0056] wherein "C" is a "C-rate" unit used to represent the charging and discharging rate of the battery. The definition of 1C: 1C current value is equal to the rated capacity of the battery. For example, a battery with a rated capacity of 2000 milliampere-hour (mAh), 1C for this battery is equivalent to 2000 milliampere (mA), or 2 ampere (A) current.

[0057] Constant current charging phase (fast charging): The system determines that the battery has left the deep discharge state and can accept fast charging. The system enters the constant current charging phase and sets the target charging parameter to a larger second target current value (e.g. 0.1C-0.2C), which is larger than the first target current value. In this phase, the system will maintain this constant current, and the battery voltage will rise rapidly.

[0058] Constant voltage charging phase (saturation charging): The system determines that the battery voltage has approached the full voltage. To prevent overcharging, the system enters the constant voltage charging phase and sets the target charging parameter to a first target voltage value (e.g. 14.4V). In this phase, the system will maintain the charging voltage constant, while the charging current will naturally decay as the battery gradually fills up. When the current decays to a set value (e.g. 0.02C), it is generally considered that the charging is complete.

[0059] This embodiment accurately identifies the under-voltage (over-discharge) and full state of the battery through voltage threshold, and automatically switches to the corresponding safe charging mode. Trickle charging avoids permanent damage to deeply discharged batteries due to large current impact; constant voltage charging effectively prevents battery water loss, heating and bulging caused by overcharging. This fundamentally extends the service life of the battery.

[0060] The constant current charging phase allows the system to charge at the maximum safe current within the acceptable range of the battery, significantly shortening the overall charging time and improving energy supplement efficiency.

[0061] The system can automatically complete complex charging management decisions relying only on one key battery voltage sampling signal, reducing the dependence on other sensors and reducing system complexity and hardware cost.

[0062] The criterion based on the battery voltage makes the switching between the charging phases continuous and natural. The rise of the battery voltage is a direct consequence of the charging process, and the switching point of the phases is exactly the point where the battery state changes qualitatively. This avoids the abruptness of the phase switching and guarantees a smooth transition of the charging process.

[0063] In some embodiments, the control signals include a first control signal, a second control signal, a third control signal, and a fourth control signal, and the photovoltaic power supply control method further includes: determining that the initial power supply mode is an initial step-down mode when the first control signal has high and low levels in a first time period and the third control signal is continuously high in the first time period; determining that the initial power supply mode is an initial step-up mode when the first control signal is continuously high in a second time period and the third control signal has high and low levels in the second time period; and determining that the initial power supply mode is an initial step-up / down mode when the first control signal and the third control signal both have high and low levels in a third time period.

[0064] It should be noted that the first time period, the second time period, and the third time period are not in time sequence, and each can be at least one switching period. The level state of the control signal directly determines the switching behavior of the transistor, and then affects the working mode of the circuit. For example, the high level of the control signal represents the conduction of the corresponding transistor, and the low level of the control signal represents the turn-off of the corresponding transistor. In other embodiments, the low level of the control signal can represent the conduction of the corresponding transistor, and the high level of the control signal can represent the turn-off of the corresponding transistor.

[0065] When the first control signal has high and low levels (i.e., presents a PWM waveform) in a first time period, and the third control signal is continuously high (constant conduction) in the same time period. This indicates that the first transistor is performing switching action (PWM), and the third transistor is continuously conducting (as a synchronous rectifier). At the same time, the second transistor is complementary to the first transistor (the second control signal is complementary PWM), and the fourth transistor is continuously turned off (the fourth control signal is low). The system can quickly identify that the initial power supply mode is the initial step-down mode.

[0066] When the first control signal is continuously high (constant conduction) in a second time period, and the third control signal has high and low levels (i.e., presents a PWM waveform) in the second time period. This indicates that the first transistor is continuously conducting (as a pass-through switch), and the third transistor is performing switching action (PWM). At the same time, the second transistor is continuously turned off (the second control signal is low), and the fourth transistor is complementary to the third transistor (the fourth control signal is complementary PWM). The system can quickly identify that the initial power supply mode is the initial step-up mode.

[0067] When the first control signal and the third control signal both have high and low levels in the third time period (i.e., both present PWM waveforms). This indicates that all four transistors are involved in PWM control (the first transistor and the second transistor are complementary, and the third transistor and the fourth transistor are complementary), but the phases of the PWM signals can be different (for example, the phase of the third transistor / fourth transistor is offset relative to the first transistor / second transistor). The system can quickly identify that the initial power supply mode is the initial buck-boost mode.

[0068] This mechanism of determining the initial power supply mode based on the level analysis of the control signals can avoid the need to rely on complex voltage sampling calculations and can infer the initial power supply mode in real time through only the timing analysis of the control signals, thereby avoiding the need for additional sensors (such as a photovoltaic voltage sensor) and reducing hardware complexity and cost.

[0069] In some embodiments, the photovoltaic power supply control method further includes: determining a duty cycle corresponding to the initial power supply mode and a calculation formula of an output voltage according to the initial power supply mode; obtaining the output voltage according to the duty cycle and the calculation formula; and determining the target power supply mode as the target buck mode when the output voltage is greater than the positive electrode voltage of the battery, determining the target power supply mode as the target boost mode when the output voltage is less than the positive electrode voltage of the battery, and determining the target power supply mode as the target buck-boost mode when the output voltage is approximately equal to the positive electrode voltage of the battery.

[0070] It should be noted that the duty cycle corresponding to the initial power supply mode can be obtained according to the level data of the control signal accessed by the corresponding transistor in different initial power supply modes.

[0071] In the initial buck mode, the duty cycle corresponding to the initial power supply mode is the duty cycle D1 of the first control signal accessed by the first transistor, the positive electrode voltage of the battery is denoted as VOUT, and the calculation formula of the output voltage V1 of the photovoltaic assembly is V1 = VOUT / D1.

[0072] In the initial boost mode, the duty cycle corresponding to the initial power supply mode is the duty cycle D3 of the third control signal accessed by the third transistor, the positive electrode voltage of the battery is denoted as VOUT, and the calculation formula of the output voltage V2 of the photovoltaic assembly is V2 = VOUT / (1-D3).

[0073] In the initial buck-boost mode, the duty cycle corresponding to the initial power supply mode is the duty cycle of the first control signal to which the first transistor is connected, i.e. D1, and the duty cycle of the third control signal to which the third transistor is connected, i.e. D3. In order to quickly determine the target power supply mode, it is assumed that D1=D3 and the phase difference between them, i.e. φ, is fixed. The positive electrode voltage of the battery is denoted as VOUT, and the calculation formula of the output voltage of the photovoltaic module, i.e. V3, is V3=VOUT / (1-D1). This multi-variable (D1, D3, φ) control strategy gives the system strong dynamic optimization capability, enabling it to maintain high efficiency and stable operation within a wide input voltage range, and to achieve smooth transition between different power supply modes.

[0074] When the output voltage of the photovoltaic module is significantly higher than the positive electrode voltage of the battery, the efficiency of the buck topology is the highest at this time, the system switches to the target buck mode, and in the target buck mode, the target charging parameters are realized through the precise control of adjusting the PWM duty cycle of the first transistor and / or the second transistor.

[0075] When the output voltage of the photovoltaic module is lower than the positive electrode voltage of the battery, it needs to be boosted to charge, the system switches to the target boost mode in time, and in the target boost mode, the energy transmission is realized by adjusting the PWM duty cycle of the third transistor and / or the fourth transistor.

[0076] When the voltages of the two are close (allowing a certain error range), in order to avoid frequent mode switching, the system switches to the target buck-boost mode in time, and the voltage is smoothly adapted through the coordinated control of the four transistors.

[0077] In this way, it can be ensured that the system always selects the topology mode that best matches the voltage relationship, maximizes the energy conversion efficiency, and avoids oscillation at the critical voltage point through the "approximately equal to" judgment, thereby improving the stability of the system.

[0078] In some embodiments, the photovoltaic power supply control method further comprises: when the target power supply mode is the target buck mode, configuring the first control signal as a first pulse width modulation signal, the second control signal as a second pulse width modulation signal complementary to the first pulse width modulation signal, the third control signal as a constant high level signal, the fourth control signal as a constant low level signal, and controlling the electrical parameter output by the photovoltaic power supply circuit to reach the target charging parameter by adjusting at least one of the first control signal and the first control signal; when the target power supply mode is the target buck mode, configuring the first control signal as a constant high level signal, the second control signal as a constant low level signal, the third control signal as a third pulse width modulation signal, the fourth control signal as a fourth pulse width modulation signal complementary to the third pulse width modulation signal, and controlling the electrical parameter output by the photovoltaic power supply circuit to reach the target charging parameter by adjusting at least one of the third control signal and the fourth control signal; when the target power supply mode is the target buck-boost mode, configuring the first control signal, the second control signal, the third control signal and the fourth control signal as a first pulse width modulation signal, a second pulse width modulation signal, a third pulse width modulation signal and a fourth pulse width modulation signal in turn, respectively, the first pulse width modulation signal and the second pulse width modulation signal being complementary, the third pulse width modulation signal and the fourth pulse width modulation signal being complementary, and the phase of the third pulse width modulation signal being different from at least one of the phase of the first pulse width modulation signal and the phase of the second pulse width modulation signal.

[0079] It should be noted that in the target buck mode (Buck mode), the buck function is realized by the alternating switching of the first transistor and the second transistor, the third transistor is used as a synchronous rectifier to maintain a constant on state, and the fourth transistor is kept off to avoid forming a short circuit path.

[0080] In the target boost mode, the first transistor maintains a constant on state to establish a direct current path, the second transistor maintains an off state to prevent current backflow, the boost function is realized by the alternating switching of the third transistor and the fourth transistor, and the boost amplitude is controlled by adjusting the duty cycle of the third control signal.

[0081] In the target buck-boost mode, all four switching tubes participate in high-frequency switching operation, the buck-boost function is realized by accurately controlling the phase difference, the adaptability of the system to voltage fluctuations is improved, and the efficiency performance of the system under different working conditions is optimized.

[0082] The implementation realizes flexible switching of three basic working modes by precisely controlling the conduction state of four switch tubes. Each mode is optimized for a specific input-output voltage relationship, ensuring that the photovoltaic power supply system remains efficient and stable under different working conditions. This control strategy fully considers various working condition changes in practical applications, providing reliable technical support for photovoltaic charging systems.

[0083] In Buck mode, the average current flowing through the first inductor, IL, is approximately equal to the output current, Iout (i.e., the real-time charging current) (ignoring losses). The system does not directly sample IL, but controls indirectly through the voltage-current relationship: according to the target charging parameters (such as a constant first target current value or a second target current value, denoted as Itarget), the system uses the battery voltage and load characteristics to back-calculate the required output voltage of the photovoltaic module, Vout (because the battery behaves as an approximately constant current load in the constant current stage, Vout needs to satisfy Iout = Itarget), and adjusts the duty cycle of the first control signal to change Vout, thereby indirectly adjusting Iout to approach the target value. For example, if the actual current is lower than the target, increase the duty cycle of the first control signal to increase Vout, thereby increasing Iout.

[0084] In this way, without current sampling, current stability is achieved through voltage feedback, simplifying the hardware. Combined with charging stage management, it ensures that the current is within a safe range (such as small current in the trickle stage and large current in the constant current stage).

[0085] In Boost mode, IL is related to the input current, but Iout is affected by the duty cycle and voltage relationship. The system controls indirectly as follows: according to Itarget, the system uses the input-output relationship of the Boost circuit (Iout ≈ Iin × (1-D), where Iin is related to the photovoltaic characteristics), combined with the calculated photovoltaic voltage Vin, to back-calculate the required duty cycle D. Adjust the duty cycle of the third control signal to change Vout, thereby indirectly adjusting Iout. For example, if the current is insufficient, increase D to increase Vout to increase the current.

[0086] It can still efficiently boost voltage and current under low-voltage input conditions, adapting to weak light environments. Voltage feedback is used to maintain current stability and prevent battery overcurrent.

[0087] In resistive load or battery charging, there is a deterministic relationship between current and voltage (I = V / R or battery charging curve). The system adjusts the PWM in real time to make the battery voltage change along the pre-set charging curve (constant current or constant voltage), thereby naturally maintaining the target current.

[0088] Only battery voltage sampling is needed, avoiding current sensor, reducing cost and complexity. Indirect current control by PWM duty cycle adjustment, combined with charging phase and power supply mode switching, achieves safe and efficient charging in the whole working range. Voltage mode control reduces sampling points, improving system anti-interference ability.

[0089] In other embodiments, the circuit topology in buck-down mode is equivalent to a synchronous Buck converter. By adjusting the duty cycle (D1) of the first PWM signal of the first transistor, the average value of the output voltage is controlled, and in turn the output current is controlled.

[0090] The system sets a target charging current (I_ref) according to the charging phase (such as the constant current phase). The controller samples the actual output current (I_out) in real time (likely through a sampling resistor in series in the loop). Compare I_out with I_ref to get the error signal Error = I_ref - I_out. The error signal is sent to a PID controller (or other type of controller), which outputs an adjustment based on the size and direction of the error. This adjustment is ultimately translated into a regulation of the duty cycle (D1) of the first PWM signal.

[0091] If I_out < I_ref, the controller will increase D1. The first transistor turns on for a longer time, the voltage applied to the inductor L1 increases, and the inductor current rises faster, so that I_out increases and tends to I_ref.

[0092] If I_out > I_ref, the controller will decrease D1. The first transistor turns on for a shorter time, and the inductor current rises or falls, so that I_out decreases and falls back to I_ref.

[0093] Through closed-loop feedback control, the interference caused by changes in light (resulting in fluctuations in V_pv) or small changes in battery voltage can be offset in real time, achieving high-precision constant-current charging. The third transistor is used as a synchronous rectifier, replacing the freewheeling diode in the traditional Buck circuit, with lower on-state voltage drop, significantly reducing on-state loss.

[0094] In other embodiments, the circuit topology of the boost mode is equivalent to a synchronous Boost converter. By adjusting the duty cycle (D3) of the third PWM signal driving the third transistor, the energy storage and release of the inductor is controlled, and in turn, the input current (which ultimately determines the output current) is controlled. Similarly, the system sets a target charging current (I_ref). The output current (I_out) is sampled in real time. The error is calculated and fed into the PID controller. The controller output adjusts the duty cycle (D3) of the third PWM signal. In the Boost circuit, the output current and the duty cycle are inversely related. To increase the output current, D3 usually needs to be reduced. Because D3 is reduced, the fourth transistor is on for a longer time (1-D3), the inductor stores more energy, and more energy is released to the output in the next cycle, thereby increasing the output current. (Note: The specific control logic depends on the location of the current sampling and the design of the controller algorithm, but the essence is still to use the error to inversely adjust D3). The controller algorithm automatically handles this inverse relationship, ensuring that whether D3 is increased or decreased, its ultimate goal is to accurately track I_ref.

[0095] In this way, even if the voltage of the photovoltaic module is lower than the voltage of the battery, the system can efficiently transfer energy to the battery through the boost mode, extending the effective working time of the system. Through closed-loop control, the stability of the current during the boost process is ensured, avoiding impact on the battery and photovoltaic module.

[0096] Whether in buck mode or boost mode, the core method of achieving the target charging current is consistent: closed-loop negative feedback control based on real-time current sampling. The system continuously compares the target value with the actual value and dynamically adjusts the PWM duty cycle of the key switch tube (the first transistor in the Buck mode or the third transistor in the Boost mode), forming an automatic adjustment system, and ultimately stabilizing the actual charging current at the target value, thereby achieving safe, fast and efficient charging.

[0097] In some embodiments, the photovoltaic power supply control method further comprises: determining temperature data of the battery; obtaining a temperature change rate of the battery based on the temperature data; and adjusting the first target voltage value according to the temperature change rate.

[0098] It should be noted that the system collects battery temperature data in real time through a temperature sensor (such as a thermistor attached to the battery shell). This data not only reflects the current working environment of the battery, but also is a direct indicator of its internal chemical activity.

[0099] The system records the trend of temperature change over time and obtains the temperature change rate by calculating the temperature difference per unit time (such as °C / min). For example, if the battery temperature rises rapidly in a short period of time, the system can identify the potential risk of heat accumulation.

[0100] In the constant-voltage charging phase, the system dynamically corrects the first target voltage value (i.e., the constant-voltage charging voltage) according to temperature data:

[0101] When the battery temperature is high or rises quickly, the internal chemical reaction of the battery is active, and the risk of overcharging increases. The system will actively lower the first target voltage value (for example, for lead-acid batteries, it is compensated by-3 mV / ℃ / cell), to prevent electrolyte decomposition and battery bulging.

[0102] When the battery temperature is low or cools down quickly, the internal resistance of the battery increases, and the charging acceptance ability becomes poor. The system will appropriately increase the first target voltage value to ensure that the battery can be fully charged and avoid capacity decay caused by undercharging.

[0103] By adjusting the charging voltage adaptively according to temperature, the damage to the battery caused by high-temperature overcharging and low-temperature undercharging is effectively avoided. For example, reducing the charging voltage in summer high temperature can reduce battery water loss; increasing the voltage in winter low temperature can ensure the charging efficiency, thereby significantly prolonging the service life of the battery.

[0104] The response to the temperature change rate gives the system predictive protection capability. If a sharp rise in temperature is detected (such as an increase of 1℃ per minute or more), the system can lower the charging voltage in advance or switch to the float charging mode to prevent thermal runaway.

[0105] Photovoltaic systems often face outdoor temperature fluctuations. This mechanism enables the charging strategy to adapt to all-weather conditions from scorching heat to severe cold, ensuring optimal charging efficiency and battery health in different climate conditions.

[0106] The system converts temperature data into voltage compensation through analog circuits or embedded algorithms. For example, a temperature-voltage compensation table can be stored in the controller, which is queried and adjusted in real time to achieve closed-loop control without complex programming. This process is completely based on hardware logic or lookup table method, meeting the requirement of "avoiding the use of programming language".

[0107] The temperature dynamic compensation mechanism converts the battery temperature and its change rate into a regulation signal for charging parameters, making the photovoltaic power supply system more intelligent and reliable while pursuing high-efficiency energy conversion.

[0108] In some embodiments, before determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, the photovoltaic power supply control method further comprises: when the first comparison result indicates that the positive electrode voltage of the photovoltaic module is higher than the negative electrode voltage of the photovoltaic module, and the second comparison result indicates that the negative electrode voltage of the photovoltaic module is higher than the voltage of the ground terminal, performing the "determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery", the first comparison result being a comparison result of the positive electrode voltage of the photovoltaic module and the negative electrode voltage of the photovoltaic module, and the second comparison result being a comparison result of the negative electrode voltage of the photovoltaic module and the voltage of the ground terminal; when the first comparison result indicates that the positive electrode voltage of the photovoltaic module is lower than the negative electrode voltage of the photovoltaic module, and / or, the second comparison result indicates that the negative electrode voltage of the photovoltaic module is lower than the voltage of the ground terminal, controlling all the transistors in the input bridge arm and the output bridge arm to be turned off.

[0109] It should be noted that, in the implementation process of the photovoltaic power supply control method, safety diagnosis is the primary step to ensure reliable operation of the system. The pre-check process based on voltage comparison is performed before starting the normal charging control, which is used to verify whether the electrical state of the photovoltaic module is normal.

[0110] The safety diagnosis mechanism relies on two key voltage comparison results, which are realized by hardware comparator circuits and can quickly respond without software intervention.

[0111] For the first comparison result (comparison of the positive electrode voltage and the negative electrode voltage of the photovoltaic module): when the positive electrode voltage of the photovoltaic module is higher than the negative electrode voltage, it indicates that the polarity connection of the photovoltaic array is correct, and the photovoltaic array is in a power generation state (for example, the positive electrode potential is higher than the negative electrode potential when there is light). This is a basic safety signal indicating that the photovoltaic input source is effective.

[0112] If the positive electrode voltage is lower than the negative electrode voltage, it may indicate that the photovoltaic array is reversely connected (polarity error) or in a no-light state (such as night), and the photovoltaic module cannot normally supply power at this time.

[0113] For the second comparison result (comparison of the negative electrode voltage of the photovoltaic module and the voltage of the ground terminal): when the negative electrode voltage of the photovoltaic module is higher than the voltage of the ground terminal, it indicates that the photovoltaic loop is not short-circuited to the ground, and the negative electrode potential is in a normal floating state. This is a key indicator to ensure good electrical isolation of the system. If the negative electrode voltage is lower than or equal to the voltage of the ground terminal, it may indicate that the negative electrode of the photovoltaic module is accidentally grounded or short-circuited to the ground, which may cause safety risks (such as electric shock or equipment damage).

[0114] Based on the above comparisons, only when the first comparison result is that the positive electrode voltage is higher than the negative electrode voltage and the second comparison result is that the negative electrode voltage is higher than the voltage of the ground terminal, the system determines that the state of the photovoltaic array is normal, and allows the subsequent charging stage judgment and power supply mode control to be performed.

[0115] If the first comparison result shows that the positive electrode voltage is lower than the negative electrode voltage (reverse connection / no light), or the second comparison result shows that the negative electrode voltage is lower than or equal to the ground terminal voltage (short circuit to ground), the system immediately enters the safety mode, and all transistors of the input bridge arm and the output bridge arm are turned off, completely cutting off the energy transmission path.

[0116] Real-time voltage monitoring is realized through the comparator circuit, the response speed is extremely fast (microsecond level), the circuit can be cut off at the moment of failure, and damage of abnormal conditions such as reverse connection and short circuit to photovoltaic modules, batteries or power devices is effectively prevented. This hardware priority protection strategy avoids the risks that may be caused by software delay.

[0117] The pre-checking step ensures that the system will start the charging process only when the photovoltaic input source is safe and effective. This avoids equipment failure (such as MOSFET burning) caused by forced operation under polarity error or short circuit conditions, and improves the overall robustness of the system.

[0118] Placing safety diagnosis before charging control allows the subsequent algorithm to focus on optimizing energy conversion without frequent processing of underlying faults. This improves control efficiency and reduces software complexity.

[0119] The mechanism can adapt to changes in light: when there is no light (photovoltaic voltage anomaly), the system is automatically turned off to prevent battery energy from flowing back; when there is light and the connection is correct, it seamlessly enters the working state. This ensures the safe operation of the system in various environments.

[0120] In some embodiments, please refer to Figure 1 , Figure 2 , the embodiment of the present application provides a photovoltaic power supply circuit which executes the photovoltaic power supply control method described above.

[0121] It can be understood that, since the photovoltaic power supply circuit provided by the embodiment executes the photovoltaic power supply control method described above, the charging phase of the battery and the target power supply mode of the photovoltaic power supply circuit can be determined based on the positive electrode voltage of the battery, the target charging parameter corresponding to the charging phase can be found according to the mapping relationship, the control signal can be generated based on the target power supply mode and the target charging parameter, and the driving signal for driving the input bridge arm and the output bridge arm can be generated based on the control signal, so that the efficient conversion of photovoltaic electric energy and the safe charging of the battery can be considered only by collecting the single data, i.e. the positive electrode voltage of the battery, thereby achieving a better dynamic balance between energy capture efficiency and battery safety life with less collected data.

[0122] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0123] The principles and implementation manners of the present application are described herein by using specific examples, and the above descriptions of the examples are only used to help understand the technical solutions of the present application and the core ideas thereof; it should be understood by those skilled in the art that the technical solutions recorded in the foregoing examples can be modified, or some technical features thereof can be replaced by equivalent ones; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the examples of the present application.

Claims

1. A method of controlling a photovoltaic power supply, characterized by, The photovoltaic power supply control method is applied to a photovoltaic power supply circuit, the photovoltaic power supply circuit comprises an input bridge arm, a first inductor and an output bridge arm, the input bridge arm is connected between the positive electrode of a photovoltaic module and a ground terminal, the output bridge arm is connected between the positive electrode of a battery and a ground terminal, the input bridge arm comprises a first transistor and a second transistor, the first transistor is connected between the positive electrode of the photovoltaic module and a midpoint of the input bridge arm, the second transistor is connected between the midpoint of the input bridge arm and the ground terminal, the output bridge arm comprises a third transistor and a fourth transistor, the third transistor is connected between the positive electrode of the battery and a midpoint of the output bridge arm, the fourth transistor is connected between the midpoint of the output bridge arm and the ground terminal, the first inductor is connected between the midpoint of the input bridge arm and the midpoint of the output bridge arm, and the photovoltaic power supply control method comprises: determining a charging stage of the battery and a target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery; looking up a target charging parameter corresponding to the charging stage according to a mapping relationship; generating a control signal based on the target power supply mode and the target charging parameter; generating a driving signal for driving the input bridge arm and the output bridge arm based on the control signal; wherein the photovoltaic power supply control method further comprises: determining the charging stage of the battery according to a comparison result of the positive electrode voltage of the battery and a preset voltage threshold; determining an initial power supply mode of the photovoltaic power supply circuit according to level data of the control signal; calculating an output voltage of the photovoltaic module according to the initial power supply mode and the positive electrode voltage of the battery; determining the target power supply mode according to a comparison result of the output voltage of the photovoltaic module and the positive electrode voltage of the battery; wherein the charging stage comprises a trickle charging sub-stage, a constant current charging sub-stage and a constant voltage charging sub-stage, the preset voltage threshold comprises a first voltage threshold and a second voltage threshold which are sequentially increased, and the photovoltaic power supply control method further comprises: when the voltage of the battery is lower than the first voltage threshold, determining that the charging stage is the trickle charging sub-stage, and determining that a target charging parameter corresponding to the trickle charging sub-stage is a first target current value based on the mapping relationship; when the voltage of the battery is greater than or equal to the first voltage threshold and less than the second voltage threshold, determining that the charging stage is the constant current charging sub-stage, and determining that a target charging parameter corresponding to the constant current charging sub-stage is a second target current value based on the mapping relationship, the second target current value being greater than the first target current value; when the voltage of the battery is greater than or equal to the second voltage threshold, determining that the charging stage is the constant voltage charging sub-stage, and determining that a target charging parameter corresponding to the constant voltage charging sub-stage is a first target voltage value based on the mapping relationship.

2. The photovoltaic powered control method of claim 1, wherein, The control signals include a first control signal, a second control signal, a third control signal, and a fourth control signal, the gate of the first transistor is connected to the first control signal, the gate of the second transistor is connected to the second control signal, the gate of the third transistor is connected to the third control signal, and the gate of the fourth transistor is connected to the fourth control signal, and the photovoltaic power supply control method further comprises: When the first control signal has high and low levels in a first time period, and the third control signal is continuously high in the first time period, it is determined that the initial power supply mode is an initial step-down mode; When the first control signal is continuously high in a second time period, and the third control signal has high and low levels in the second time period, it is determined that the initial power supply mode is an initial step-up mode; When the first control signal and the third control signal both have high and low levels in a third time period, it is determined that the initial power supply mode is an initial step-up / down mode.

3. The photovoltaic powered control method of claim 2, wherein, The photovoltaic power supply control method further comprises: determining a duty cycle corresponding to the initial power supply mode and a calculation formula of the output voltage according to the initial power supply mode; obtaining the output voltage according to the duty cycle and the calculation formula; When the output voltage is greater than the anode voltage of the battery, it is determined that the target power supply mode is a target step-down mode; when the output voltage is less than the anode voltage of the battery, it is determined that the target power supply mode is a target step-up mode; and when the output voltage is equal to the anode voltage of the battery, it is determined that the target power supply mode is a target step-up / down mode.

4. The photovoltaic powered control method of claim 3, wherein, The photovoltaic power supply control method further comprises: When the target power supply mode is the target step-down mode, the first control signal is configured as a first pulse width modulation signal, the second control signal is configured as a second pulse width modulation signal complementary to the first pulse width modulation signal, the third control signal is configured as a constant high level signal, the fourth control signal is configured as a constant low level signal, and at least one of the first control signal and the first control signal is adjusted to control the electrical parameter output by the photovoltaic power supply circuit to reach the target charging parameter; When the target power supply mode is the target step-down mode, the first control signal is configured as a constant high level signal, the second control signal is configured as a constant low level signal, the third control signal is configured as a third pulse width modulation signal, the fourth control signal is configured as a fourth pulse width modulation signal complementary to the third pulse width modulation signal, and at least one of the third control signal and the fourth control signal is adjusted to control the electrical parameter output by the photovoltaic power supply circuit to reach the target charging parameter; When the target power supply mode is the target step-up / down mode, the first control signal, the second control signal, the third control signal and the fourth control signal are configured to be a first pulse width modulation signal, a second pulse width modulation signal, a third pulse width modulation signal and a fourth pulse width modulation signal in sequence respectively, the first pulse width modulation signal and the second pulse width modulation signal are complementary, the third pulse width modulation signal and the fourth pulse width modulation signal are complementary, and the phase of the third pulse width modulation signal is different from at least one of the phase of the first pulse width modulation signal and the phase of the second pulse width modulation signal.

5. The photovoltaic powered control method of claim 1, wherein, The photovoltaic power supply control method further comprises: determining temperature data of the battery; obtaining a temperature change rate of the battery based on the temperature data; adjusting the first target voltage value according to the temperature change rate.

6. The photovoltaic powered control method according to any of claims 1-5, characterized in that, Before the step of determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, the photovoltaic power supply control method further comprises: when the first comparison result indicates that the positive electrode voltage of the photovoltaic assembly is higher than the negative electrode voltage of the photovoltaic assembly, and the second comparison result indicates that the negative electrode voltage of the photovoltaic assembly is higher than the voltage of the ground end, performing the step of determining the charging stage of the battery and the target power supply mode of the photovoltaic power supply circuit based on the positive electrode voltage of the battery, the first comparison result is a comparison result of the positive electrode voltage of the photovoltaic assembly and the negative electrode voltage of the photovoltaic assembly, and the second comparison result is a comparison result of the negative electrode voltage of the photovoltaic assembly and the voltage of the ground end; when the first comparison result indicates that the positive electrode voltage of the photovoltaic assembly is lower than the negative electrode voltage of the photovoltaic assembly, and / or, the second comparison result indicates that the negative electrode voltage of the photovoltaic assembly is lower than the voltage of the ground end, controlling each transistor in the input bridge arm and the output bridge arm to be turned off.

7. A photovoltaic power supply circuit, characterized by The photovoltaic power supply circuit executes the photovoltaic power supply control method according to any one of claims 1-6.

8. The photovoltaic power supply circuit of claim 7, wherein, The photovoltaic power supply circuit further comprises: a control module configured to generate a corresponding first switch signal and a second switch signal according to the target power supply mode; an RC absorption module, each of the RC absorption modules being connected in parallel between the drain and the source of each transistor in the input bridge arm and the output bridge arm; a first RC controllable absorption module connected between the positive electrode of the photovoltaic assembly and the midpoint of the input bridge arm and controlled by the first switch signal; a second RC controllable absorption module connected between the positive electrode of the battery and the midpoint of the output bridge arm and controlled by the second switch signal.

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