Photovoltaic module bypass control device
By using a combination of MCU-controlled main shutdown MOSFETs, NMOS transistors, and charge pumps in the photovoltaic module bypass device, the problems of high current heat generation and processor power failure in the prior art are solved, achieving stable bypass with low heat generation and improving the safety and stability of photovoltaic modules.
Patent Information
- Application Number
- CN202422977030.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-12-04
AI Technical Summary
Existing photovoltaic module bypass devices generate a lot of heat under high current conditions and cannot function properly when the processor loses power, affecting safety and stability.
The system employs a main shutdown MOSFET controlled by an MCU, a parallel NMOS transistor, and a charge pump. By leveraging the bridging effect of the NMOS transistor and the setting of the charge pump, it ensures that the photovoltaic module and the fast shutdown module can be stably bypassed regardless of whether the MCU is working properly. Furthermore, it utilizes a reverse detector and logic control circuitry to optimize the conduction state of the MOSFET.
It achieves stable bypass with low heat generation under high current conditions, improving the safety and stability of photovoltaic modules and ensuring normal operation over a long period of time.
Smart Images
Figure CN223528035U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to photovoltaic power generation field, especially a kind of photovoltaic module bypass control device. BACKGROUND
[0002] At present, in photovoltaic system, multiple photovoltaic modules are connected in series to form photovoltaic string, photovoltaic string generates direct current, and then converts into alternating current by inverter and transmits to power grid, in order to improve the safety of photovoltaic system, relevant industry standard requires that photovoltaic module can be self-off. According to the above requirements, in the prior art, a fast shutdown device is arranged behind each photovoltaic module, and the voltage on the cable is ensured to meet the safety requirements through the fast shutdown device. When a certain photovoltaic module is affected by shading or self-aging, characteristic attenuation or output matching error occurs, the photovoltaic module will be bypassed; synchronously, the fast shutdown device connected with it will also be bypassed, and then a new path needs to be built to ensure that other photovoltaic modules on the photovoltaic string are in normal on state.
[0003] The existing bypass function is usually realized by bypass diode (usually Schottky diode), and the bypass function stability and tolerance of the entire circuit device are subjected to great test during bypass processing. For example, the bypass diode is connected in parallel with the load end, so that the current flowing into the adjacent photovoltaic module of the bypassed photovoltaic module flows to the other adjacent photovoltaic module through the bypass diode to realize bypass. However, the current generated by the photovoltaic module is large, and the superposition of series current will cause the current passing through the bypass diode to reach dozens of amperes, and the technical personnel usually uses multiple bypass diodes in parallel to improve the current carrying capacity of the entire device. However, in the above scheme, even if multiple bypass diodes are used in parallel, the total heat generated by the bypass diode group is still large, so there is a risk of overheating during long-time bypass operation.
[0004] In order to solve the problem of heating, the prior art also uses MOS tube instead of diode to play the bypass function, but its opening or shutdown is basically controlled by the processor, if the photovoltaic module fails and the processor loses power and cannot work, the above bypass function will be invalid, which affects normal use. UTILITY MODEL CONTENTS
[0005] The utility model aims at providing a kind of photovoltaic module bypass control device, the device can supply larger bypass load current, and have excellent heat generation control ability, ensure the safety and stability of the entire device when photovoltaic module and fast shutdown device are bypassed for a long time;In addition, it can ensure that MOS tube can normally work to realize bypass function whether it receives opening voltage signal or not.
[0006] In order to realize the above purpose, the specific technical scheme adopted by the utility model is as follows:
[0007] A bypass control device for photovoltaic module, comprising a photovoltaic voltage input end, a load end in parallel with the photovoltaic voltage input end, and a fast shutdown component; the fast shutdown component comprises an MCU and a main shutdown MOS tube connected between the photovoltaic voltage input end and the load end and controlled by the MCU, characterized in that the bypass control device for photovoltaic module fast shutdown component further comprises an NMOS tube in parallel with the load end and a charge pump; the gate of the NMOS tube is connected to the output of the charge pump and the MCU.
[0008] Thus, the photovoltaic voltage input end is one end of a single photovoltaic module outputting photovoltaic power to a rear-end load or power grid, the output photovoltaic power is transmitted to the load end through the photovoltaic voltage input end, the photovoltaic voltage input end is in parallel with the load end, and in a photovoltaic module string, each photovoltaic module is connected in series with each other.
[0009] Between the photovoltaic voltage input end and the load end, the fast shutdown component is connected in series, which mainly functions as a fast shutdown device and is composed of an MCU and a main shutdown MOS tube controlled by the MCU; specifically, the source and the drain of the main shutdown MOS tube are connected in series between the photovoltaic voltage input end and the load end, and the gate is connected to the MCU. When the MCU determines that the current photovoltaic module needs to be shut down, it will stop sending a continuous opening voltage signal to the main shutdown MOS tube through the gate, so that the main shutdown MOS tube is shut down, cutting off the connection between the photovoltaic module and the load end. However, when the above method is executed in a photovoltaic string, it will cut off the current passing through the entire string, so that other photovoltaic modules also lose output, and therefore a bypass is needed to isolate the fast shutdown component from the entire string.
[0010] Therefore, the NMOS tube and the charge pump in parallel with the load end are specially set, and the NMOS tube has excellent large-current passing performance. When the bypass action is performed, the NMOS tube will serve as a new string current path to ensure the normal output of other photovoltaic modules in the string.
[0011] A body diode is arranged between the source and the drain of the NMOS tube, and the body diode points from the source to the drain. In addition, a charge pump is connected in parallel between the load end and the photovoltaic voltage input end, which can output a preset voltage signal by judging the voltage drop between the two parallel input ends.
[0012] Firstly, when the photovoltaic module is working normally, the current flows from the PV+ of the photovoltaic voltage input end to the OUT+ of the load end, then to the OUT- of the load end corresponding to an adjacent photovoltaic module, then to the PV- of the photovoltaic voltage input end of the photovoltaic module and performs the next cycle. At this time, the MCU continuously sends an opening voltage to the gate of the main shutdown MOS tube, i.e. the fast shutdown component is in an idle state; and the MCU controls the NMOS tube not to be opened.
[0013] When the photovoltaic module has normal power supply, the MCU is in working state, and the quick turn-off component needs to be actively activated, the MCU sends the opening voltage to the gate of the NMOS tube, controls the NMOS tube to be turned on, at this time, the current flows from the source to the drain of the NMOS tube, that is, the current flowing into the OUT- of the photovoltaic module flows to the OUT+ of the load end through the NMOS tube, and then flows to the OUT- of the load end corresponding to the adjacent photovoltaic module, so the bridging effect of the NMOS tube ensures the normal current passing through the adjacent photovoltaic modules.
[0014] When the photovoltaic module has no normal power supply, the MCU is in a non-working state, the MCU stops sending the opening voltage to the main turn-off MOS tube, the main turn-off MOS tube changes to the off state, and the current flowing to the photovoltaic module is cut off. At this time, the current flows to the next adjacent photovoltaic unit through the body diode part of the NMOS tube, but this process is short, because the current carrying capacity of the body diode is limited, and there is a certain voltage drop between the two ends. Since the charge pump is connected in parallel with the body diode, the voltage drop is connected to the charge pump, and the charge pump sends the opening voltage to the gate of the NMOS tube through the output end according to the preset value, at this time, the source and the drain of the NMOS tube are turned on, the current passes, and the current does not pass through the body diode.
[0015] In summary, through the bridging effect of the NMOS tube and the setting of the charge pump, it is ensured that the photovoltaic module and the quick turn-off component can be stably bypassed regardless of whether the photovoltaic module can be normally powered or whether the MCU can work. And since the MOS tube used for bypassing is an NMOS tube, the overcurrent capacity is strong, the heat generation is low, and the safety of long-time bypassing can be improved.
[0016] As a preferred embodiment of the utility model, the photovoltaic module quick turn-off bypass control device further comprises a reverse detector, two input ends of the reverse detector are connected in parallel to the source and the drain of the NMOS tube, and the output end of the reverse detector is connected to the MCU.
[0017] Thus, the reverse detector can be implemented by using a reverse comparator. Two input pins of the reverse comparator are connected in parallel between the source and the drain of the NMOS tube, and are also connected in parallel to OUT+ and OUT- of the load end. In addition, the output end of the reverse comparator is connected to the MCU, so that the comparison result of the reverse comparator is sent to the MCU as an output result. When the fast shutdown assembly is normally working and the photovoltaic assembly is normally outputting, the main shutdown MOS tube is turned on, and the NMOS tube responsible for the bypass is in the off state, at this time, the voltage of OUT+ is higher than that of OUT-, the reverse comparator outputs GPIO-IN as a high level, and the MCU executes a control command according to the signal received by the above-mentioned GPIO-IN, so as to ensure that the NMOS tube is turned off. When the fast shutdown assembly is normally working, but the photovoltaic assembly is in an abnormal output state due to, for example, being shaded, the voltage of OUT+ is lower than that of OUT-, at this time, the reverse comparator outputs GPIO-IN as a low level, and the MCU executes a control command according to the signal received by the above-mentioned GPIO-IN, so as to turn on the NMOS tube, and then make the bypass function work, so that the photovoltaic assembly in the abnormal output state and the fast shutdown assembly are bypassed.
[0018] As a preferred embodiment of the present application, a logic control circuit is further arranged between the NMOS tube and the MCU, and the logic control circuit comprises a first control MOS tube and a second control MOS tube. The gate of the first control MOS tube is connected to the control signal output end of the MCU. The drain of the first control MOS tube is connected to the gate of the second control MOS tube and a positive voltage end. The sources of the first control MOS tube and the second control MOS tube are grounded. The drain of the second control MOS tube is connected to the gate of the NMOS tube and the positive voltage end.
[0019] Thus, when the reverse detector outputs GPIO-IN as a high level, according to the built-in control algorithm of the MCU, the output end of the GPIO-1 of the MCU outputs a low level, and then the first control MOS tube is not turned on. At this time, the second control MOS tube is turned on under the opening voltage provided by the positive voltage end, so that the NMOS tube is not turned on, and then the main shutdown MOS tube is not bypassed. When the reverse detector outputs GPIO-IN as a low level, according to the built-in control algorithm of the MCU, the output end of the GPIO-1 of the MCU outputs a high level, and then the first control MOS tube is turned on. At this time, the second control MOS tube is not turned on, and the NMOS tube is turned on under the opening voltage provided by the positive voltage end, and then the main shutdown MOS tube is bypassed.
[0020] As a preferred embodiment of the present application, a first resistor is connected in parallel between the gate and the source of the first control MOS tube.
[0021] Therefore, the first control MOS tube has the first resistance connected in parallel between the gate and the source, so that the stable operation of the first control MOS tube is ensured.
[0022] As a preferred embodiment of the present application, the second control MOS tube has the second resistance connected in parallel between the gate and the source.
[0023] Therefore, the second resistance R1-17 can fix the gate potential of the second control MOS tube at a lower state, so as to avoid mis-triggering and ensure reliable on-off operation.
[0024] As a preferred embodiment of the present application, the NMOS tube has the third resistance connected in parallel between the gate and the source.
[0025] As a preferred embodiment of the present application, the NMOS tube has the third resistance connected in parallel between the gate and the source.
[0026] In summary, the present application has the following advantages:
[0027] Through the bridging effect of the NMOS tube and the setting of the charge pump, it is ensured that the photovoltaic module and the fast shutdown component can be stably bypassed regardless of whether the photovoltaic module can be normally powered and whether the MCU can work. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 Fig. 1 is a schematic diagram of the photovoltaic module bypass control device according to the present application;
[0029] Figure 2 Fig. 3 is a circuit schematic diagram of the photovoltaic module bypass control device according to the present application;
[0030] Figure 3 Fig. 5 is a schematic diagram of a plurality of photovoltaic module bypass control devices connected in series according to the present application;
[0031] Figure 4 Fig. 7 is a schematic diagram of a reverse detector according to the present application. DETAILED DESCRIPTION
[0032] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Anyone can implement the present disclosure in various forms without being limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present disclosure more thorough and complete, and to convey the scope of the present disclosure to those skilled in the art.
[0033] Thus, the photovoltaic voltage input end is one end of a single photovoltaic module to output photovoltaic power to a rear-end load or a power grid, and the output photovoltaic power is transmitted to the load end through the photovoltaic voltage input end, the photovoltaic voltage input end is connected in parallel with the load end, and in one photovoltaic string, each photovoltaic module is connected in series with each other, and each load end is connected in series with each other to form an overall load end, as shown in Figure 3 The series connection diagram of a plurality of photovoltaic modules and a photovoltaic module bypass control device is shown.
[0034] As shown in Figure 1 Between the photovoltaic voltage input end and the load end, a fast shutdown module is connected in series, which mainly functions as a fast shutdown device and is composed of an MCU and a main shutdown MOS tube Q2 controlled by the MCU. Specifically, the source S and the drain D of the main shutdown MOS tube Q2 are connected in series between the photovoltaic voltage input end and the load end, and the gate G is connected to the MCU. When the MCU determines that the current photovoltaic module needs to be shut down, it will stop sending a continuous opening voltage signal to the main shutdown MOS tube Q2 through the gate G, so that the main shutdown MOS tube Q2 is shut down, cutting off the connection between the photovoltaic module and the load end. However, the above method will cut off the current passing through the entire string when it is executed in a photovoltaic string, so that other photovoltaic modules also lose output, and therefore a bypass is needed to isolate the fast shutdown module from the entire string.
[0035] In the present scheme, an NMOS tube Q1 and a charge pump CHARGE PUMP are connected in parallel with the load end, and the NMOS tube Q1 has excellent large-current passing performance. When the bypass action is performed, the NMOS tube Q1 will serve as a new string current path to ensure the normal output of other photovoltaic modules in the string.
[0036] First, a body diode is arranged between the source S and the drain D of the NMOS tube Q1, and the body diode points from the source S to the drain D. In addition, a charge pump CHARGE PUMP is connected in parallel between the load end and the photovoltaic voltage input end, which can output a preset voltage signal by judging the voltage drop between the two parallel input ends.
[0037] Secondly, as Figure 2As shown, the photovoltaic module fast shutdown bypass control device further comprises a reverse detector and a logic control circuit, wherein the reverse detector can be implemented using a reverse comparator U10, two input pins of the reverse comparator U10 are connected in parallel between the source S and the drain D of the NMOS tube Q1, and are also connected in parallel to the OUT+ and OUT- of the load end. In addition, the output end of the reverse comparator U10 is connected to the MCU, so that the comparison result of the reverse comparator U10 will be sent to the MCU as an output result. The logic control circuit comprises a first control MOS tube Q1-14 and a second control MOS tube Q1-13; the gate G of the first control MOS tube Q1-14 is connected to the control signal output end of the MCU; the drain D of the first control MOS tube Q1-14 is connected to the gate G of the second control MOS tube Q1-13 and the positive voltage end; the source S of the first control MOS tube Q1-14 and the second control MOS tube Q1-13 is grounded; and the drain D of the second control MOS tube Q1-13 is connected to the gate G of the NMOS tube Q1 and the positive voltage end.
[0038] In the first case, i.e. when the photovoltaic module is working normally, the current flows from the PV+ of the photovoltaic voltage input end to the OUT+ of the load end, then flows to the OUT- of the load end corresponding to an adjacent photovoltaic module, then flows to the PV- of the photovoltaic voltage input end of the photovoltaic module and performs the next cycle. At this time, the MCU continuously sends an opening voltage to the gate G of the main shutdown MOS tube Q2, i.e. the fast shutdown module is in an inactive state; and the MCU controls the NMOS tube Q1 not to be opened.
[0039] Specifically, as shown in Figure 2 and Figure 4 When the photovoltaic module is normally powered and the MCU is in a working state, the main shutdown MOS tube Q2 is turned on, and the NMOS tube Q1 responsible for bypassing is in a shutdown state. At this time, the voltage of OUT+ is higher than that of OUT-, the reverse comparator U10 outputs GPIO-IN as a high level, the MCU executes a control command according to the signal received by the above-mentioned GPIO-IN, and according to the built-in control algorithm of the MCU, the output end of the GPIO-1 of the MCU outputs a low level, so that the first control MOS tube Q1-14 is not turned on. At this time, the second control MOS tube Q1-13 is turned on under the opening voltage provided by the 10V positive voltage end, so that the NMOS tube Q1 is not turned on, and the main shutdown MOS tube Q2 is not bypassed.
[0040] In the second case, when the quick shutdown component is working normally, but the photovoltaic component is shaded, for example, resulting in a change in the normal output state, the voltage of OUT+ is lower than that of OUT-. At this time, the reverse comparator U10 outputs GPIO-IN as low level, and the MCU executes the control command according to the signal received by GPIO-IN. According to the control algorithm built in the MCU, the output end of GPIO-1 of the MCU outputs high level, and the first control MOS Q1-14 is turned on. At this time, the second control MOS Q1-13 is not turned on, and the NMOS Q1 is turned on under the opening voltage provided by the 10V positive voltage end, and the main shutdown MOS Q2 is bypassed.
[0041] In the third case, when the photovoltaic component is normally powered due to failure or other reasons, the MCU is in a non-working state, and the MCU stops sending the opening voltage to the main shutdown MOS Q2. The main shutdown MOS Q2 is turned off, and the current flowing to the photovoltaic component is cut off. At this time, the current flows to the next adjacent photovoltaic unit through the body diode part of the NMOS Q1, but this process is short because the current carrying capacity of the body diode is limited, and there is a certain voltage drop between the two ends. Since the charge pump CHARGE PUMP is connected to the input, the voltage drop is connected to the charge pump CHARGE PUMP, and the charge pump CHARGE PUMP outputs a stable voltage according to the preset value. The output is connected to the gate G of the NMOS Q1 to send the opening voltage. At this time, the source S and the drain D of the NMOS Q1 are turned on, and the current flows, so that the current does not flow through the body diode. Instead, the current flows from the source S to the drain D of the NMOS Q1. The voltage drop and resistance of this path are very low, and the heat accumulation of the long-time path is small, which can meet the long-time bypassing requirement.
[0042] In addition, the first resistor R1-18 is connected in parallel between the gate G and the source S of the first control MOS Q1-14. This connection can prevent the voltage between the source S and the drain D of the first control MOS Q1-14 from causing the first control MOS Q1-14 to be accidentally turned on and damaged due to the floating gate G. At the same time, when there is no opening voltage signal, the first resistor R1-18 can fix the gate G potential of the first control MOS Q1-14 to a lower state, thereby avoiding false triggering and ensuring reliable on-off operation. The second resistor R1-17 is connected in parallel between the gate G and the source S of the second control MOS Q1-13. The second resistor R1-17 can fix the gate G potential of the second control MOS Q1-13 to a lower state, thereby avoiding false triggering and ensuring reliable on-off operation. The third resistor is connected in parallel between the gate G and the source S of the NMOS Q1, and the positive voltage end and the NMOS Q1 are connected in series with the current limiting resistor R1-14.
[0043] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application; in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. The structural member materials, sizes, shapes, etc. mentioned in the embodiments of the present application are all illustrative descriptions, and do not form strict or absolute limitations. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A photovoltaic assembly bypass control device, comprising a photovoltaic voltage input terminal, a load terminal connected in parallel with the photovoltaic voltage input terminal, and a fast shutdown assembly; the fast shutdown assembly comprises an MCU and a main shutdown MOS tube connected between the photovoltaic voltage input terminal and the load terminal and controlled by the MCU, characterized in that, The photovoltaic module bypass control device further comprises an NMOS tube and a charge pump connected in parallel with the load end; a gate of the NMOS tube is connected to an output end of the charge pump and the MCU.
2. A bypass control device for a photovoltaic module according to claim 1, wherein The photovoltaic module bypass control device further comprises a reverse detector, two input ends of the reverse detector are connected in parallel with a source and a drain of the NMOS tube; an output end of the reverse detector is connected to the MCU.
3. A bypass control device for a photovoltaic module according to claim 2, wherein A logic control circuit is further arranged between the NMOS tube and the MCU, the logic control circuit comprises a first control MOS tube and a second control MOS tube; a gate of the first control MOS tube is connected to a control signal output end of the MCU; a drain of the first control MOS tube is connected to a gate of the second control MOS tube and a positive voltage end; sources of the first control MOS tube and the second control MOS tube are grounded; a drain of the second control MOS tube is connected to a gate of the NMOS tube and the positive voltage end.
4. A bypass control device for a photovoltaic module according to claim 3, wherein A first resistor is connected in parallel between the gate and the source of the first control MOS tube.
5. A bypass control device for a photovoltaic module according to claim 3, wherein A second resistor is connected in parallel between the gate and the source of the second control MOS tube.
6. A bypass control device for a photovoltaic module according to claim 1, wherein A third resistor is connected in parallel between the gate and the source of the NMOS tube.
7. A bypass control device for a photovoltaic module according to claim 3, wherein A limited current resistor is connected in series between the positive voltage end and the NMOS tube.