Dual charge pump driving circuit with under voltage protection, photovoltaic fast-off device and control method

Abstract

The application belongs to the technical field of photovoltaic control, and discloses a double charge pump driving circuit with under-voltage protection, a photovoltaic fast breaker and a control method thereof. The double charge pump driving circuit comprises a Boost circuit, a first charge pump circuit and a second charge pump circuit. The first charge pump circuit and the second charge pump circuit are connected in parallel. The first charge pump circuit utilizes capacitors C2 and C3, diodes D2 and D3 and a DC / DC chip with an input of VIN and an output of VOUT to obtain a stable VIN+VOUT to supply a NMOS driving circuit. The second charge pump circuit performs voltage bootstrap through an MCU sending a PWM signal. The Boost circuit realizes controllable voltage boosting of the second charge pump circuit under the action of the PWM signal. The design of the double charge pump makes the output of the driving voltage complementary to each other and mutually supporting, so that the driving generation circuit works more stably, and the stability of the photovoltaic fast breaker is ensured, and the safety of the photovoltaic module is improved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic control technology, and particularly relates to a dual charge pump drive circuit with undervoltage protection, a photovoltaic fast-break device, and a control method. Background Technology

[0002] The rapid development of society is inseparable from the support of energy. With the increasing demand for energy and the decreasing reserves of traditional energy sources, the growth trend of photovoltaic power generation is attracting more and more attention, and the industry is developing faster and faster. Photovoltaic power generation refers to a power generation technology that outputs high-voltage direct current by connecting multiple photovoltaic panels in series, then connecting them to an inverter, and finally converting the direct current into alternating current for grid connection.

[0003] In recent years, for safety reasons, relevant electrical codes in various countries have gradually incorporated mandatory regulations for photovoltaic (PV) power generation. For example, the US safety code NEC 2017 / 2020 not only requires PV systems to have a fast shutdown function, but also stipulates that the maximum voltage after shutdown must not exceed 80V. Since PV power generation systems are high-voltage DC systems, a fault in such systems can easily cause a fire, and rescue work under energized conditions is extremely dangerous. Therefore, installing reliable fast-shutdown devices on PV power generation systems is essential. These devices can automatically disconnect the PV modules without human intervention, ensuring the safety of personnel.

[0004] In existing technologies, the mainstream solution for controlling the on / off switching of photovoltaic fast-acting devices is NMOS positive electrode control, which requires a charge pump to boost the positive electrode voltage to drive the NMOS to conduct. Its main drawbacks and shortcomings are as follows:

[0005] (1) The driving circuit has high voltage loss, complex structure, low efficiency, and low reliability. The driving circuit of the photovoltaic fast-break device in the prior art generally uses an external integrated IC such as a 555 timer to generate a PWM signal for bootstrap voltage boosting. The circuit is complex, has low reliability, high cost, and high voltage loss. Moreover, it uses a Zener diode for voltage regulation through a single charge pump boosting scheme, which has low efficiency and poor applicability to input voltage. When the operation is abnormal, the pumped voltage is insufficient to drive the NMOS, the internal resistance of the NMOS increases, the heat generation increases, and eventually damages it. Therefore, its reliability is low.

[0006] (2) The drive circuit does not have a pump-up voltage monitoring function, nor does it have a monitoring function for loop current and NMOS temperature. It cannot monitor and adjust the current state in a closed loop. For example, under the undervoltage state, the pump-up voltage will be low, which will lead to an increase in the internal resistance of NMOS or a large loop current. This will cause NMOS to heat up more, which can easily damage the device. It cannot meet the requirements for safe, stable and reliable operation of photovoltaic modules under the current development trend.

[0007] In summary, the drive circuit of the existing photovoltaic fast-break device needs to be improved to ensure that the photovoltaic fast-break device can operate stably and reliably under various adverse conditions that may occur in the photovoltaic power generation system. Summary of the Invention

[0008] The present invention addresses the aforementioned inconveniences and defects of existing photovoltaic fast-break drive circuits. The technical problem to be solved is to provide a dual charge pump drive circuit for photovoltaic fast-break devices, aiming to improve the reliability and stability of the drive by utilizing the dual charge pump structure, so as to achieve stable and reliable operation of photovoltaic fast-break devices under various harsh conditions.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a dual charge pump drive circuit with undervoltage protection, including a Boost circuit, a first charge pump circuit and a second charge pump circuit;

[0010] The first charge pump circuit includes a DC / DC chip, capacitors C2 and C3, and diodes D2 and D3. The VIN pin of the DC / DC chip is connected to the input voltage VIN, which is the output voltage of the photovoltaic module. One end of capacitor C3 is connected to the VIN pin of the DC / DC chip, and the other end is connected to the cathode of diode D3. The anode of diode D3 is connected to the SW pin of the DC / DC chip via capacitor C2. The cathode of diode D2 is connected to the anode of diode D3. The anode of diode D2 is connected to the output terminal VOUT of the DC / DC chip. The cathode of diode D3 is used to output a drive voltage to drive the NMOS transistor in the switching circuit.

[0011] The second charge pump circuit includes resistors R1, R2, R3, and R4, transistors V1, V2, and V3, diodes D4 and D5, and capacitors C4 and C5. One end of resistor R1 is connected to the PWM signal output terminal, and the other end is connected to the base of transistor V1. The base of transistor V1 is grounded through resistor R2, and its emitter is grounded. The collector of transistor V3 is connected to the output terminal of the Boost circuit through resistor R3. The collector of transistor V3 is connected to the output terminal of the Boost circuit, and its base is connected to the base of transistor V2. The emitter of transistor V3 is connected to one end of capacitor C4 and the emitter of transistor V2. The collector of transistor V2 is grounded, and its base is connected to the collector of transistor V1 through resistor R4. The other end of capacitor C4 is connected to the cathode of diode D4 and the anode of diode D5. The anode of diode D4 is connected to the input voltage VIN, and the anode of diode D5 is grounded through capacitor C5. Its anode is used to output the drive voltage to drive the NMOS transistor in the switching circuit.

[0012] The Boost circuit includes an NMOS transistor V4, an inductor L2, a diode D6, and a capacitor C6. One end of the inductor L2 is connected to the output VOUT of the DC-DC chip, and the other end is connected to the anode of the diode D6. The cathode of the diode D6 serves as the output terminal of the Boost circuit. The gate of the MOS transistor V4 is connected to the PWM signal, the source is grounded, and the drain is connected to the other end of the inductor L2. One end of the capacitor C6 is grounded, and the other end is connected to the cathode of the diode D6.

[0013] The first charge pump circuit also includes an inductor L1, a capacitor C1, and a diode D1. One end of the inductor L1 is connected to the SW pin of the DC / DC chip, and the other end serves as the output terminal VOUT of the DC / DC chip. The cathode of the diode D1 is connected to the SW pin of the DC / DC chip, and the anode is grounded. One end of the capacitor C1 is connected to the output terminal VOUT of the DC / DC chip, and the other end is grounded.

[0014] The anode of diode D5 and the cathode of diode D3 are connected to the gate (G) of the NMOS transistor. The drain (D) of the NMOS transistor is connected to the output of the photovoltaic module, and the source (S) of the NMOS transistor serves as the output of the switching circuit.

[0015] In addition, the present invention also provides a photovoltaic fast-break device, including a power supply circuit, a microcontroller, a switching circuit and an information acquisition circuit, wherein the power supply circuit includes the aforementioned dual charge pump drive circuit;

[0016] The information acquisition circuit is used to acquire the output information of the photovoltaic device and the driving voltage information output by the dual charge pump drive circuit; the microcontroller is used to generate a PWM signal based on the output information of the photovoltaic device and send it to the dual charge pump drive circuit.

[0017] The photovoltaic fast shutdown device further includes: a communication circuit, which is used to connect to a host computer;

[0018] The power supply circuit also includes an LDO power chip, and the DC / DC chip is used to supply power to the LDO power chip. The LDO power chip is used to supply power to the microcontroller, communication circuit, and information acquisition circuit.

[0019] The communication circuit is a carrier communication circuit.

[0020] The information acquisition circuit includes an output voltage and current acquisition circuit, a temperature acquisition circuit, and a drive voltage acquisition circuit.

[0021] The output voltage and current acquisition circuit is used to acquire the output voltage and output current of the photovoltaic module, the temperature acquisition circuit is used to acquire the temperature of the NMOS transistor, and the drive voltage acquisition circuit is used to acquire the drive voltage output by the dual charge pump drive circuit.

[0022] The method for generating PWM signals by the microcontroller is as follows:

[0023] S101, Obtain input voltage U in (t), driving voltage U out (t) and the given target voltage U aim (t);

[0024] S102, Calculate the control deviation;

[0025] S103. Input the control deviation into the PID module, and use the output of the PID module as the duty cycle of the PWM signal;

[0026] S104. Limit the duty cycle to obtain the PWM signal.

[0027] Furthermore, the present invention also provides a control method for the aforementioned photovoltaic fast-break device, comprising the following steps:

[0028] S1. Collect the temperature of the NMOS transistor;

[0029] S2. Determine if the temperature is higher than the temperature threshold. If yes, cut off the photovoltaic module and send a warning signal to the host computer. If no, collect the loop current and proceed to the next step.

[0030] S3. Determine whether the loop current is lower than the threshold. If yes, cut off the photovoltaic module and send a warning signal to the host. If no, collect the driving voltage output by the dual charge pump drive circuit and proceed to the next step.

[0031] S4. Determine whether the driving voltage is higher than the driving voltage threshold. If it is higher than the driving voltage threshold, cut off the photovoltaic module and send a warning signal to the host. If it is lower than the threshold, return to step S1 to repeatedly collect the temperature of the NMOS tube.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. This invention utilizes the inherent operating characteristics of DC / DC chips, combined with several diodes, capacitors, and other components, to output a driving voltage. This scheme is designed based on the characteristics of the power chip itself, resulting in a simple structure and reliable operation. Furthermore, due to the fewer components in the driving voltage generation circuit, voltage loss is low, leading to a higher final output driving voltage, which is more conducive to the stable operation of the fast-break device. On the other hand, by directly generating PWM control signals using an MCU, the design of external oscillation circuits, such as a 555 timer, is eliminated, resulting in fewer components and a simpler design structure. In addition, the dual charge pump design allows the driving voltage outputs to complement and support each other, making the driving generation circuit more stable. Even if one side malfunctions, the other can continue to operate stably, such as under undervoltage conditions, ensuring the stability of the circuit operation.

[0034] 2. This invention achieves adjustable and controllable output voltage of the charge pump. Under undervoltage operation of photovoltaic modules, the magnitude of the boost drive voltage of the dual charge pump structure is also affected. To minimize the impact of undervoltage on the charge pump boost drive voltage, this invention integrates a Boost converter circuit into the charge pump circuit, solving the problem of uncontrollable boost voltage driven by the charge pump circuit. By combining a PID algorithm, the boost voltage of the charge pump circuit is used as input, and the PWM duty cycle is used as output, thus forming a closed-loop control circuit to achieve adjustable boost drive voltage, solving the problem of adjustable boost voltage and further enhancing the stability and reliability of the circuit operation.

[0035] 3. The instantaneous tripping device of the present invention incorporates abnormal handling logic to monitor the NMOS temperature, pump-up voltage, and loop current in real time. In actual working scenarios, the occurrence of abnormal states is unavoidable. Therefore, in the control method of the present invention, the temperature rise of the NMOS transistor is used as the basis for judging whether the circuit is working normally. In addition, the loop current and drive voltage flowing through the NMOS transistor are also monitored, which improves the sensitivity and reliability of abnormal handling. Attached Figure Description

[0036] Figure 1 The circuit diagram of the first charge pump circuit in the undervoltage protection dual charge pump drive circuit provided in Embodiment 1 of the present invention;

[0037] Figure 2 The circuit diagram of the second charge pump circuit in the undervoltage protection dual charge pump drive circuit provided in Embodiment 1 of the present invention is shown.

[0038] Figure 3 The circuit diagram of the Boost circuit in the undervoltage protection dual charge pump drive circuit provided in Embodiment 1 of the present invention;

[0039] Figure 4This is a structural block diagram of a photovoltaic fast-break device provided in Embodiment 2 of the present invention;

[0040] Figure 5 This is a schematic diagram of the PWM signal generation in Embodiment 2 of the present invention;

[0041] Figure 6 This is a flowchart illustrating a control method for a photovoltaic fast-break device provided in Embodiment 3 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] Embodiment 1 of the present invention provides an undervoltage protection dual charge pump drive circuit, including a Boost circuit, a first charge pump circuit, and a second charge pump circuit. The first and second charge pump circuits are connected in parallel. The first charge pump circuit includes a DC / DC chip, which uses capacitors C2 and C3 and diodes D2 and D3 to boost the output voltage VOUT of the DC / DC chip to VIN+VOUT and maintain it stable, supplying the NMOS drive circuit. VIN is the input voltage. The second charge pump circuit performs voltage bootstrapping by sending a PWM signal from the MCU. Under the action of the PWM signal, the Boost circuit changes the output voltage VOUT of the DC / DC chip in the first charge pump circuit to VOUT_BOOST to perform voltage bootstrapping for the second charge pump circuit, thus achieving controllable voltage boosting in the second charge pump circuit.

[0045] Specifically, such as Figure 1 As shown, the first charge pump circuit includes a DC-DC chip, capacitors C2 and C3, and diodes D2 and D3; the VIN pin of the DC / DC chip is connected to the input voltage VIN; the input voltage VIN is the output voltage of the photovoltaic module; one end of capacitor C3 is connected to the VIN pin of the DC / DC chip, and the other end is connected to the cathode of diode D3; the anode of diode D3 is connected to the SW pin of the DC / DC chip via capacitor C2; the cathode of diode D2 is connected to the anode of diode D3; the anode of diode D2 is connected to the output terminal VOUT of the DC / DC chip; and the cathode of diode D3 is used to output the driving voltage to drive the NMOS transistor in the switching circuit.

[0046] Among them, the DC / DC chip is a DCDC-BUCK power chip, which controls the output voltage VOUT by adjusting the duty cycle of the PWM signal in the switching cycle. Inside the DCDC chip, the switching of VIN and SW is defined as S1.

[0047] When switch S1 is on, VIN and SW are connected, diode D1 is off, and inductor L1 and capacitor C1 are charged and stored. The lower potential of capacitor C2 is equal to VIN. When switch S1 is off, the inductor releases the stored magnetic energy and freewheels. At this time, diode D1 is turned on, and the lower potential of capacitor C2 is -0.7V. The upper potential of capacitor C2 is charged to VOUT by the output voltage, and the voltage difference across capacitor C2 is VOUT. In the next cycle, switch S1 is turned on again, and the lower potential of capacitor C2 is equal to VIN. At this time, the voltage of the upper end of capacitor C2 relative to GND is pumped up to VIN+VOUT. Diode D3 is turned on at this time. Capacitor C3 is a filter capacitor, and its right-hand voltage rises to VIN+VOUT and remains stable, supplying the NMOS drive circuit. Since this voltage boosting circuit shares the same output with another path, the function of diode D3 is to prevent reverse current from the other voltage output. The boosted voltage VIN+VOUT is used as the drive voltage for the drive circuit in the switching circuit, driving the gate of the NMOS transistor in the switching circuit.

[0048] Specifically, such as Figure 2 As shown, the second charge pump circuit includes resistors R1, R2, R3, and R4, transistors V1, V2, and V3, diodes D4 and D5, and capacitors C4 and C5. One end of resistor R1 is connected to the PWM signal output terminal, and the other end is connected to the base of transistor V1. The base of transistor V1 is grounded through resistor R2, and its emitter is grounded. The collector of transistor V3 is connected to the output terminal of the Boost circuit through resistor R3. The collector of transistor V3 is connected to the output terminal of the Boost circuit, and its base is connected to the base of transistor V2. The emitter of transistor V3 is connected to one end of capacitor C4 and the emitter of transistor V2. The collector of transistor V2 is grounded, and its base is connected to the collector of transistor V1 through resistor R4. The other end of capacitor C4 is connected to the cathode of diode D4 and the anode of diode D5. The anode of diode D4 is connected to the input voltage VIN, and the anode of diode D5 is grounded through capacitor C5. Its anode is used to drive the NMOS transistor in the switching circuit with the output drive voltage.

[0049] Specifically, such as Figure 3As shown, the Boost circuit includes an NMOS transistor V4, an inductor L2, a diode D6, and a capacitor C6. One end of the inductor L2 is connected to the output VOUT of the DC / DC chip, and the other end is connected to the anode of the diode D6. The cathode of the diode D6 serves as the output terminal of the Boost circuit. The gate of the MOS transistor V4 is connected to the PWM signal, the source is grounded, and the drain is connected to the other end of the inductor L2. One end of the capacitor C6 is grounded, and the other end is connected to the cathode of the diode D6.

[0050] In this embodiment, the second charge pump circuit performs voltage bootstrapping by sending a PWM signal from the MCU. The principle is as follows: The input signal to this circuit is a PWM signal. When the PWM control signal is high, transistor V1 is turned on, which in turn causes the control signals for transistors V2 and V3 in the subsequent circuit to be low. That is, transistor V2 is turned on, transistor V3 is turned off, the left end of capacitor C4 is at 0V, and the input power supply VIN charges capacitor C4 through diode D4, making the right end of capacitor C4 at VIN. When the PWM control signal is low, transistor V1 is turned off, and the base control signals for transistors V2 and V3 are high. When transistor V2 is turned off and transistor V3 is turned on, the reference potential of capacitor C4 changes from GND to VOUT_BOOST, which is equivalent to the voltage being boosted by VOUT_BOOST. The potential at the right end of capacitor C4 rises to VIN+VOUT_BOOST, and this voltage is output through diode D5. Diode D4 protects the power supply VIN from reverse voltage flow. At this time, the low level of the output voltage is a square wave voltage of VIN and the high level is VIN+VOUT_BOOST. By adding capacitor C5, filtering and energy storage are performed to obtain a stable output voltage VIN+VOUT_BOOST.

[0051] In this embodiment, the boost output voltage of the second charge pump circuit is determined by VOUT__BOOST and VIN. If VOUT__BOOST is directly set to the output VOUT of the DC-DC chip, the output of the second charge pump circuit is also fixed at VOUT+VIN. In order to achieve controllable output voltage and perform boost regulation under undervoltage conditions, the Boost circuit of this invention converts VOUT into a VOUT__BOOST voltage whose magnitude can be controlled by the PWM signal through the PWM signal, thereby achieving controllable output of the drive voltage. In this embodiment, the PWM signal of the Boost circuit can be shared with the PWM signal of the second charge pump circuit.

[0052] Specifically, in this embodiment, the first charge pump circuit further includes an inductor L1, a capacitor C1, and a diode D1. One end of the inductor L1 is connected to the SW pin of the DC / DC chip, and the other end serves as the output terminal VOUT of the DC / DC chip. The cathode of the diode D1 is connected to the SW pin of the DC / DC chip, and the anode is grounded. One end of the capacitor C1 is connected to the output terminal VOUT of the DC / DC chip, and the other end is grounded.

[0053] Specifically, the anode of diode D5 and the cathode of diode D3 are connected to the gate (G) of the NMOS transistor, the drain (D) of the NMOS transistor is connected to the output of the photovoltaic module, and the source (S) of the NMOS transistor serves as the output of the switching circuit. In this embodiment, the driving voltage generated by the dual charge pump drive circuit is used to drive the NMOS transistor in the power switching device. The gate (G) of the NMOS transistor is connected to the driving voltage output by the dual charge pump drive circuit, and the drain (D) is connected to the output of the photovoltaic module. By controlling the on / off state of the NMOS transistor, the output voltage of the photovoltaic module is controlled at its source. When the NMOS transistor is on, the voltage difference between its gate (G) and source (S) is the actual pump-up voltage of the charge pump circuit.

[0054] Example 2

[0055] like Figure 4 As shown, Embodiment 2 of the present invention provides a photovoltaic fast-off device, including a power supply circuit, a microcontroller, a switching circuit, and an information acquisition circuit. The power supply circuit includes the dual charge pump drive circuit described in Embodiment 1. The information acquisition circuit is used to acquire the output information of the photovoltaic device and the drive voltage information output by the dual charge pump drive circuit. The microcontroller is used to generate a PWM signal based on the output information of the photovoltaic device and send it to the dual charge pump drive circuit.

[0056] Specifically, in this embodiment, the information acquisition circuit includes an output voltage and current acquisition circuit, a temperature acquisition circuit, and a drive voltage acquisition circuit; the output voltage and current acquisition circuit is used to acquire the output voltage and output current of the photovoltaic module, the temperature acquisition circuit is used to acquire the temperature of the NMOS transistor, and the drive voltage acquisition circuit is used to acquire the drive voltage output by the dual charge pump drive circuit.

[0057] Furthermore, the photovoltaic fast-break device of this embodiment also includes a communication circuit for connecting to a host computer. The power supply circuit further includes a DC-DC-BUCK power chip and an LDO power chip. The DC-DC-BUCK power chip supplies power to the LDO power chip, and the LDO power chip supplies power to the microcontroller, the communication circuit, and the information acquisition circuit. Additionally, in this embodiment, the DC-DC-BUCK power chip can also be the DC / DC chip U1 in a dual charge pump circuit.

[0058] Specifically, the communication circuit is a carrier communication circuit, which includes a carrier signal receiving circuit and a carrier signal transmitting circuit. In this embodiment, the photovoltaic instantaneous circuit breaker is connected in parallel with the photovoltaic module and communicates with the host computer (upper computer) via DC power line carrier communication, which can ensure that the photovoltaic instantaneous circuit breaker can operate stably and reliably under various adverse conditions that may occur in the photovoltaic power generation system. Furthermore, it should be noted that the LDO power chip in this embodiment can be a conventional chip in the art.

[0059] In this embodiment, the method for generating PWM signals by the microcontroller is as follows:

[0060] S101, Obtain input voltage U in (t), driving voltage U out (t) and the given target voltage U aim (t);

[0061] S102, Calculate the control deviation;

[0062] S103. Input the control deviation into the PID module, and use the output of the PID module as the duty cycle of the PWM signal;

[0063] S104. Limit the duty cycle to obtain the PWM signal.

[0064] Specifically, the formula for calculating control deviation is:

[0065] ΔU=Uaim(t)-[Uout(t)-Uin(t)]; (1)

[0066] like Figure 5 As shown, the input voltage Uin(t) refers to the input voltage VIN of the dual charge pump drive circuit, the output voltage Uout(t) refers to the output voltage (VIN+VOUT or VIN+VOUT__BOOST) of the dual charge pump drive circuit, and the given target voltage Uaim(t) refers to the target pump boost voltage of the charge pump.

[0067] First, the output voltage Uout(t) is subtracted from the input voltage Uin(t). This difference is the actual boost voltage of the charge pump circuit and also the actual drive voltage of the NMOS transistor. Then, the target voltage Uaim(t) is subtracted from this difference to obtain the control deviation. The control deviation is sent to the PID module for proportional, derivative, and integral operations. The output value of the PID module is used as the duty cycle value of the control signal PWM. Subsequently, after PWM modulation and duty cycle limiting (defining a reasonable range for the duty cycle to prevent abnormalities), a PWM signal with a certain duty cycle value is obtained. This signal controls the Boost circuit to generate a suitable output voltage (VOUT_BOOST). Finally, it is sent to the second charge pump circuit for voltage boosting and output voltage Uout(t), forming a closed-loop control process.

[0068] In this embodiment, the second charge pump circuit serves as the main working charge pump, and the first charge pump circuit serves as a backup support circuit. The simultaneous operation of the two charge pumps can prevent possible abnormal situations and maximize the reliability of the charge pump circuit operation.

[0069] Example 3

[0070] The photovoltaic fast-break device in Embodiment 2 of this invention solves the charge pump drive voltage problem under photovoltaic under-voltage operation through the design of a dual charge pump drive circuit, greatly ensuring the stability of the drive voltage. However, relevant protective measures are still needed for possible abnormal conditions in the drive circuit. Since the drive circuit ultimately operates for the power switching device, i.e., the drive voltage serves the NMOS transistor, which controls the photovoltaic module to be connected to or disconnected from the circuit, if abnormal conditions such as under-voltage operation or high current cause abnormal temperature rise of the NMOS transistor, the photovoltaic module should be quickly disconnected to protect the fast-break device.

[0071] Therefore, Embodiment 3 of the present invention provides a control method for a photovoltaic fast-break device as described in Embodiment 2, such as... Figure 6 As shown, it includes the following steps:

[0072] S1. Collect the temperature of the NMOS transistor;

[0073] S2. Determine if the temperature is higher than the temperature threshold. If yes, cut off the photovoltaic module and send a warning signal to the host computer. If no, collect the loop current and proceed to the next step. The loop current refers to the output current of the photovoltaic panel.

[0074] S3. Determine whether the loop current is lower than the threshold. If yes, cut off the photovoltaic module and send a warning signal to the host. If no, collect the driving voltage VIN+VOUT_BOOST output by the dual charge pump drive circuit and proceed to the next step.

[0075] S4. Determine whether the driving voltage is higher than the driving voltage threshold. If it is higher than the driving voltage threshold, cut off the photovoltaic module and send a warning signal to the host. If it is not higher than the threshold, return to step S1 to repeat the temperature of the NMOS tube.

[0076] Furthermore, it should be noted that in this embodiment, although the driving voltage output by the dual charge pump drive circuit is VIN+VOUT_BOOST, the voltage actually applied between the gate and source of the NMOS transistor is VOUT_BOOST.

[0077] In summary, this invention provides an undervoltage protection dual charge pump drive circuit, a photovoltaic instantaneous trip device, and a control method, which have the following advantages:

[0078] 1. This invention utilizes the inherent operating characteristics of the DC-DC-BUCK power supply chip, combined with several diodes, capacitors, and other components, to output a driving voltage. This solution is designed based on the characteristics of the power supply chip itself, resulting in a simple structure and reliable operation. Furthermore, due to the fewer components in the driving voltage generation circuit, voltage loss is low, leading to a higher final output driving voltage, which is more conducive to the stable operation of the fast-break device. On the other hand, by directly generating PWM control signals using an MCU, the design of external oscillation circuits, such as a 555 timer, is eliminated, resulting in fewer components and a simpler design structure. In addition, the dual charge pump design allows the driving voltage outputs to complement and support each other, making the driving generation circuit more stable. Even if one side malfunctions, the other can continue to operate stably, such as under undervoltage conditions, ensuring the stability of the circuit operation.

[0079] 2. This invention achieves adjustable and controllable output voltage of the charge pump. Under undervoltage operation of photovoltaic modules, the magnitude of the boost drive voltage of the dual charge pump structure is also affected. To minimize the impact of undervoltage on the charge pump boost drive voltage, this invention integrates a Boost converter circuit into the charge pump circuit, solving the problem of uncontrollable boost voltage driven by the charge pump circuit. By combining a PID algorithm, the boost voltage of the charge pump circuit is used as input, and the PWM duty cycle is used as output, thus forming a closed-loop control circuit to achieve adjustable boost drive voltage, solving the problem of adjustable boost voltage and further enhancing the stability and reliability of the circuit operation.

[0080] 3. The instantaneous tripping device of the present invention incorporates abnormal handling logic to monitor the NMOS temperature, pump-up voltage, and loop current in real time. In actual working scenarios, the occurrence of abnormal states is unavoidable. Therefore, in the control method of the present invention, the temperature rise of the NMOS transistor is used as the basis for judging whether the circuit is working normally. In addition, the loop current and drive voltage flowing through the NMOS transistor are also monitored, which improves the sensitivity and reliability of abnormal handling.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual charge pump drive circuit with undervoltage protection, characterized in that, Includes a Boost circuit, a first charge pump circuit, and a second charge pump circuit; The first charge pump circuit includes a DC / DC chip, capacitors C2 and C3, and diodes D2 and D3. The VIN pin of the DC / DC chip is connected to the input voltage VIN, which is the output voltage of the photovoltaic module. One end of capacitor C3 is connected to the VIN pin of the DC / DC chip, and the other end is connected to the cathode of diode D3. The anode of diode D3 is connected to the SW pin of the DC / DC chip via capacitor C2. The cathode of diode D2 is connected to the anode of diode D3. The anode of diode D2 is connected to the output terminal VOUT of the DC / DC chip. The cathode of diode D3 is used to output a drive voltage to drive the NMOS transistor in the switching circuit. The second charge pump circuit includes resistors R1, R2, R3, and R4, transistors V1, V2, and V3, diodes D4 and D5, and capacitors C4 and C5. One end of resistor R1 is connected to the PWM signal output terminal, and the other end is connected to the base of transistor V1. The base of transistor V1 is grounded through resistor R2, and its emitter is grounded. The collector is connected to the output terminal of the Boost circuit through resistor R3. The collector of transistor V3 is connected to the output terminal of the Boost circuit, and its base is connected to the base of transistor V2. The emitter is connected to one end of capacitor C4 and the emitter of transistor V2. The collector of transistor V2 is grounded, and its base is connected to the collector of transistor V1 through resistor R4. The other end of capacitor C4 is connected to the cathode of diode D4 and the anode of diode D5. The anode of diode D4 is connected to the input voltage VIN, and the cathode of diode D5 is grounded through capacitor C5. Its cathode is used to drive the NMOS transistor in the switching circuit with the output drive voltage. The Boost circuit includes an NMOS transistor V4, an inductor L2, a diode D6, and a capacitor C6. One end of the inductor L2 is connected to the output VOUT of the DC-DC chip, and the other end is connected to the anode of the diode D6. The cathode of the diode D6 serves as the output terminal of the Boost circuit. The gate of the MOS transistor V4 is connected to the PWM signal, the source is grounded, and the drain is connected to the other end of the inductor L2. One end of the capacitor C6 is grounded, and the other end is connected to the cathode of the diode D6.

2. The undervoltage protected dual charge pump drive circuit according to claim 1, characterized in that, The first charge pump circuit also includes an inductor L1, a capacitor C1, and a diode D1. One end of the inductor L1 is connected to the SW pin of the DC / DC chip, and the other end serves as the output terminal VOUT of the DC / DC chip. The cathode of the diode D1 is connected to the SW pin of the DC / DC chip, and the anode is grounded. One end of the capacitor C1 is connected to the output terminal VOUT of the DC / DC chip, and the other end is grounded.

3. The undervoltage protected dual charge pump drive circuit according to claim 1, characterized in that, The anode of diode D5 and the cathode of diode D3 are connected to the gate (G) of the NMOS transistor. The drain (D) of the NMOS transistor is connected to the output of the photovoltaic module, and the source (S) of the NMOS transistor serves as the output of the switching circuit.

4. A photovoltaic fast-break device, characterized in that, It includes a power supply circuit, a microcontroller, a switching circuit, and an information acquisition circuit, wherein the power supply circuit includes the dual charge pump drive circuit as described in any one of claims 1 to 3; The information acquisition circuit is used to acquire the output information of the photovoltaic device and the driving voltage information output by the dual charge pump drive circuit; The microcontroller is used to generate a PWM signal based on the output information of the photovoltaic device and send it to the dual charge pump drive circuit.

5. A photovoltaic fast-break device according to claim 4, characterized in that, Also includes: The communication circuit is used to connect to the host computer. The power supply circuit also includes an LDO power chip, and the DC / DC chip is used to supply power to the LDO power chip. The LDO power chip is used to supply power to the microcontroller, communication circuit, and information acquisition circuit.

6. A photovoltaic fast-break device according to claim 5, characterized in that, The communication circuit is a carrier communication circuit.

7. A photovoltaic fast-break device according to claim 4, characterized in that, The information acquisition circuit includes an output voltage and current acquisition circuit, a temperature acquisition circuit, and a drive voltage acquisition circuit. The output voltage and current acquisition circuit is used to acquire the output voltage and output current of the photovoltaic module, the temperature acquisition circuit is used to acquire the temperature of the NMOS transistor, and the drive voltage acquisition circuit is used to acquire the drive voltage output by the dual charge pump drive circuit.

8. A photovoltaic fast-break device according to claim 4, characterized in that, The method for generating PWM signals by the microcontroller is as follows: S101, Obtain input voltage U in (t), driving voltage U out (t) and the given target voltage U aim (t); S102, Calculate the control deviation; S103. Input the control deviation into the PID module, and use the output of the PID module as the duty cycle of the PWM signal; S104. Limit the duty cycle to obtain the PWM signal.

9. The control method for a photovoltaic fast-break device according to claim 4, characterized in that, Includes the following steps: S1. Collect the temperature of the NMOS transistor; S2. Determine if the temperature is higher than the temperature threshold. If yes, cut off the photovoltaic module and send a warning signal to the host computer. If no, collect the loop current and proceed to the next step. S3. Determine whether the loop current is lower than the threshold. If yes, cut off the photovoltaic module and send a warning signal to the host. If no, collect the driving voltage output by the dual charge pump drive circuit and proceed to the next step. S4. Determine whether the driving voltage is higher than the driving voltage threshold. If it is higher than the driving voltage threshold, cut off the photovoltaic module and send a warning signal to the host. If it is lower than the threshold, return to step S1 to repeatedly collect the temperature of the NMOS tube.

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