Weak light detection circuit and power equipment

Abstract

The utility model is suitable for the technical field of electronic circuits, and provides a weak light detection circuit and a power device, a control module of the weak light detection circuit controls a switch module to be switched on so as to connect a load to an output end of a photovoltaic power supply, and detects whether an output electrical parameter (such as output power) of the photovoltaic power supply is greater than a preset threshold; in other words, the control module judges whether the output of the photovoltaic power supply is pulled down or not, if the output of the photovoltaic power supply is not pulled down, the control module outputs a charging indication signal allowing the photovoltaic power supply to supply power to a connected electric circuit, and therefore photovoltaic weak light detection is completed. In the process, the protection module configures the switch module to be turned off after being turned on for a certain period of time, so that the weak light detection circuit is accurately controlled, and the problems that the weak light detection circuit is prone to failure, a circuit board in the power equipment is burnt, and even smoke and fire are caused are solved.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic circuits, and in particular, relates to a weak light detection circuit and a power device. Background Art

[0002] The maximum power point tracking (MPPT) circuit of the power device is used to track the power of the connected photovoltaic panels (PV). When the PV panel is in a weak light state, if the power device repeatedly wakes up the connected battery pack and charges the battery pack, there is a problem of draining the battery pack to the point of crashing. Therefore, a weak light detection circuit is required to detect the PV output power to prevent the battery pack from being drained to the point of crashing in weak light. However, traditional weak light detection circuits have failure problems, which can cause the circuit boards in the power device to burn out, or even cause smoke and fire. Utility Model Content

[0003] The embodiments of the present application provide a weak-light detection circuit and a power device, which can solve the problem that traditional weak-light detection circuits are prone to failure.

[0004] In a first aspect, an embodiment of the present application provides a weak light detection circuit for performing weak light detection on a photovoltaic power source; the weak light detection circuit comprises:

[0005] Load module;

[0006] A switch module, wherein the switch module and the load module are connected in series between the output positive electrode and the output negative electrode of the photovoltaic power source;

[0007] A detection module, connected to the output positive electrode and the output negative electrode of the photovoltaic power source, and used to detect the output electrical parameters of the photovoltaic power source;

[0008] A protection module, connected to the control end of the switch module, and used for driving the switch module to turn on for a first preset time and then turn off according to a driving signal;

[0009] A control module is connected to the protection module and the detection module respectively. The control module is used to provide the drive signal and output a charging indication signal when the switch module is turned on and the output electrical parameter is greater than a preset threshold; the charging indication signal is used to allow the photovoltaic power supply to supply power to the connected power circuit.

[0010] In one embodiment, the switch module includes a first switch tube, the first switch tube is connected in series with the load module, and a control end of the first switch tube is connected to the protection module.

[0011] In one embodiment, the protection module includes a first capacitor, a discharge resistor and a first bias resistor, the first end of the first capacitor is connected to the control module, the second end of the first capacitor is connected to the control end of the first switch tube, the discharge resistor is connected to the first capacitor in parallel, the first end of the first bias resistor is connected to the control end of the first switch tube, the second end of the first bias resistor is grounded, and the first capacitor and the first bias resistor are used to configure the first preset time length.

[0012] In one embodiment, the protection module further includes a first current limiting resistor, and the first current limiting resistor and the first capacitor are connected in series between the control module and the control end of the first switch tube.

[0013] In one embodiment, the switch module further includes a second switch tube, which is connected in series with the first switch tube, and a control end of the second switch tube is connected to the control module, and the second switch tube is used to be turned on when receiving the driving signal.

[0014] In one embodiment, the protection module further includes an anti-backflow diode, an anode of the anti-backflow diode is connected to the control module, and a cathode of the anti-backflow diode is connected to the control end of the second switch tube.

[0015] In one embodiment, the protection module also includes a second current limiting resistor and a second bias resistor, the second current limiting resistor and the anti-backflow diode are connected in series between the control module and the control end of the second switch tube, one end of the second bias resistor is connected to the control end of the second switch tube, and the second end of the second bias resistor is connected to the series node of the second switch tube and the first switch tube.

[0016] In one embodiment, the output electrical parameter includes a voltage value.

[0017] In one of the embodiments, a temperature protection module is further included. The temperature protection module, the load module and the switch module are connected in series between the output positive electrode and the output negative electrode of the photovoltaic power source.

[0018] A second aspect of an embodiment of the present application provides a power device, including a photovoltaic interface for connecting a photovoltaic panel, an MPPT circuit connected to the photovoltaic interface, and a weak light detection circuit as described above, connected to the output positive pole and output negative pole of the MPPT circuit.

[0019] Compared with the conventional technology, the embodiments of the present invention have the following beneficial effects:

[0020] In the above scheme, the control module controls the switch module to conduct to connect the load to the output end of the photovoltaic power supply, and detects whether the output electrical parameters (such as output power) of the photovoltaic power supply are greater than the preset threshold value, that is, the control module determines whether the output of the photovoltaic power supply is pulled down. If the output of the photovoltaic power supply is not pulled down, the control module outputs a charging indication signal that allows the photovoltaic power supply to supply power to the connected power circuit, thereby completing the photovoltaic weak light detection. In this process, the protection module configures the switch module to conduct for a certain period of time and then turn it off, so that the weak light detection circuit is accurately controlled to improve the problem that the weak light detection circuit is easy to fail, resulting in burning of the circuit board in the power device, or even smoke and fire. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a schematic diagram of a module of a power device provided in an embodiment of the present application;

[0023] Figure 2 It is a module schematic diagram of a weak light detection circuit provided in an embodiment of the present application;

[0024] Figure 3 Schematic diagram of a weak light detection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0026] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0027] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0029] In addition, in the description of the present application specification and the appended claims, the terms "fifth", "sixth", "seventh", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0030] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0031] See also Figure 1 Generally, a photovoltaic power source includes a PV panel and an MPPT circuit, and a weak light detection circuit is connected to the output side of the MPPT circuit. The MPPT circuit is controlled by a controller, and the power circuit is powered based on the power provided by the PV panel, such as a battery or other load. In addition, the controller needs to be powered by an auxiliary power supply, and the power of the auxiliary power supply can come from the PV panel.

[0032] Among them, the weak light detection circuit is used to perform weak light detection on the photovoltaic power source (for example, the output power or output voltage of the MPPT circuit) to prevent the photovoltaic power source from repeatedly starting and waking up the power-consuming circuit due to insufficient output voltage / power of the photovoltaic power source when the light is weak, causing damage to the power-consuming circuit. The power-consuming circuit is, for example, a battery, and repeatedly waking up the battery will eventually exhaust the battery. At the same time, the weak light detection circuit also has software control failure or short circuit failure, and the weak light detection circuit cannot be shut down in time during the detection process, causing the load module 110 in the weak light detection circuit to discharge and heat for a long time, resulting in the defect of burning the circuit board.

[0033] See also Figure 2In view of the above defects, the present application improves the weak light detection circuit. In one embodiment, the weak light detection circuit includes a load module 110, a switch module 120, a detection module 130, a protection module 140 and a control module 150.

[0034] The switch module 120 and the load module 110 are connected in series between the output positive electrode PACK+ and the output negative electrode PACK- of the photovoltaic power supply. The detection module 130 is connected to the output positive electrode PACK+ and the output negative electrode PACK- of the photovoltaic power supply, and is used to detect the output electrical parameters of the photovoltaic power supply. The protection module 140 is connected to the control end of the switch module 120, and is used to drive the switch module 120 to turn on and then turn off after a first preset time according to the drive signal. The control module 150 is connected to the protection module 140 and the detection module 130 respectively, and the control module 150 is used to provide a drive signal, and is also used to output a charging indication signal G1 when the switch module 120 is turned on and the output electrical parameter is greater than a preset threshold. The charging indication signal G1 is used to allow the photovoltaic power supply to supply power to the connected power circuit.

[0035] It is understandable that when the detection module 130 detects the output electrical parameters of the photovoltaic power source, it will output an electrical signal representing the magnitude of the output electrical parameters to the control module 150, and the control module 150 can obtain the magnitude of the output electrical parameters based on the electrical signal. Among them, the output electrical parameters include output voltage and / or output current, and the control module 150 can determine the output power of the photovoltaic power source based on the output voltage and / or output current. In the embodiment of the present application, the control module 150 can implement related functions through an MCU (Microcontroller Unit).

[0036] Exemplarily, the control module 150 outputs the charging indication signal G1 only when the output voltage or output power of the photovoltaic power source is greater than the charging voltage or charging power of the battery Bat (i.e., the preset threshold value). The embodiment of the present application avoids the situation where the control module 150 instructs the battery Bat to turn on its internal charge and discharge switch when the output voltage or output power of the photovoltaic power source is lower than the voltage or power required to charge the battery Bat, repeatedly consuming the power of the battery Bat and eventually exhausting the power of the battery Bat. Exemplarily, the battery management system (BMS) inside the battery Bat will close the charging switch S1 under the control of the charging indication signal G1, and use the photovoltaic power source to charge the battery Bat.

[0037] The load module 110 may be a resistor or other resistive device, and the load module 110 is used to consume the output of the photovoltaic power source. Figure 3For example, the load module 110 includes a plurality of power resistors R11 to R14, and the resistance value is determined by the above-mentioned preset threshold and the power consumption calculation of each power resistor. The control module 150 outputs a driving signal to drive the switch module 120 to turn on, so that the load module 110 replaces the power circuit to consume the output of the photovoltaic power source to verify whether the output power of the photovoltaic power source is pulled below the preset threshold, thereby avoiding repeated startup of the power circuit. The detection module 130 can adopt a conventional voltage / current detection circuit. In particular, the protection module 140 drives the switch module 120 to turn on for the first preset time according to the driving signal and then turns it off, so that the load module 110 can be disconnected after completing the weak light detection of the photovoltaic power source, which solves the problem of software control failure or short circuit failure of the switch module 120, resulting in the inability to turn off the weak light detection circuit in time after the weak light detection, and causing the load module 110 in the weak light detection circuit to discharge and heat for a long time, resulting in the defect of burning the circuit board.

[0038] See also Figure 3 In one embodiment, the switch module 120 includes a first switch tube Q1 , the first switch tube Q1 is connected in series with the load module 110 , and a control end of the first switch tube Q1 is connected to the protection module 140 .

[0039] The first switch tube Q1 is, for example, a MOS tube or an IGBT tube, and the protection module 140 is connected between the control end of the first switch tube Q1 and the control module 150, and is used to drive the first switch tube Q1 to turn on for a first preset time and then turn it off according to the drive signal of the control module 150. Specifically, the protection module 140 is connected to the control end of the first switch tube Q1, so as to adjust the gate voltage of the first switch tube Q1 according to the drive signal to control the on or off state, or to prevent the gate of the first switch tube Q1 from being subjected to overvoltage shock.

[0040] In one embodiment, the protection module 140 includes a first capacitor C1, a first bias resistor R1 and a discharge resistor R2. The first end of the first capacitor C1 is connected to the control module 150, and the second end of the first capacitor C1 is connected to the control end of the first switch tube Q1. The discharge resistor R2 is connected in parallel with the first capacitor C1. The first end of the first bias resistor R1 is connected to the control end of the first switch tube Q1. The second end of the first bias resistor R1 is grounded, and the first capacitor C1 and the first bias resistor R1 are used to configure the first preset duration.

[0041] In this embodiment, the first switch tube Q1 takes a MOS tube as an example, and the protection module 140 is a circuit that sets a hardware driving time (i.e., a first preset duration) at the gate of the MOS tube to prevent the software that generates the driving signal from failing (e.g., continuously sending a high level for a long time), causing the load module 110 in the weak light detection circuit to discharge for a long time and generate heat, burning the circuit board. In this embodiment, the hardware driving time can be determined according to the charging time constant formed by the first capacitor C1 and the first bias resistor R1 and the threshold voltage for the MOS tube to be turned on. In the specific implementation process, the corresponding charging time constant can be set according to the time (i.e., the hardware driving time) that the first switch tube Q1 needs to be turned on. The function of the discharge resistor R2 is to discharge the first capacitor C1 when the MOS tube is turned off. The protection module 140 is implemented as follows: when the control module 150 sends a high-level driving signal to the first switch tube Q1, the first capacitor C1 is charged using the high-level driving signal. During the charging process of the first capacitor C1, the control end of the first switch tube Q1 is at a high level, and the first switch Q1 is turned on. After the first capacitor C1 is fully charged, the control terminal of the first switch tube Q1 becomes a low level, and the first switch tube Q1 is turned off.

[0042] In some embodiments, in order to prevent repeated high-frequency weak light detection, and the first capacitor C1 has not been fully discharged and the next weak light detection is performed, the time for each weak light detection cannot be met. In some embodiments, the control module 150 sets the response time of the weak light detection operation when receiving the weak light detection operation. That is, in the specific implementation process, if the control module 150 detects a weak light detection operation, it is determined whether the response time of this weak light detection operation from the last weak light detection operation is met. If not, it does not respond to this weak light detection operation. This response time is also the time for the load module 110 to cool down, to prevent repeated weak light detection, the load module 110 from heating up seriously, to give the load module 110 cooling time, and to improve the circuit reliability. Therefore, it can be understood that the discharge time of the first capacitor C1 can be configured by setting the capacitance of the first capacitor C1 and / or the resistance of the discharge resistor R2, and then the shortest time interval between two weak light detections can be configured.

[0043] In one embodiment, the protection module 140 further includes a first current limiting resistor R3. The first current limiting resistor R3 and the first capacitor C1 are connected in series between the control module 150 and the control end of the first switch tube Q1. The first current limiting resistor R3 is used to prevent the first switch tube Q1 from being driven too much at the moment of being turned on, thereby damaging the control module 150, such as the IO port of the MCU.

[0044] In one embodiment, the switch module 120 further includes a second switch tube Q2. The second switch tube Q2 is connected in series with the first switch tube Q1. The control end of the second switch tube Q2 is connected to the control module 150. The second switch tube Q2 is used to turn on when receiving a driving signal. The second switch tube Q2 is, for example, a MOS tube or an IGBT tube. The second switch tube Q2 serves as a backup for the first switch tube Q1 to prevent a single switch tube from controlling or short-circuiting, causing the weak light detection circuit to discharge for a long time, causing the load module 110 in the weak light detection circuit to heat up and burn the circuit board.

[0045] In one embodiment, the protection module 140 further includes an anti-backflow diode D1 , an anode of the anti-backflow diode D1 is connected to the control module 150 , and a cathode of the anti-backflow diode D1 is connected to the control end of the second switch tube Q2 .

[0046] The anti-backflow diode D1 is used to prevent the high voltage generated by the junction capacitance of the first switch tube Q1 and the second switch tube Q2 from backflowing to the control module 150 when the first switch tube Q1 and the second switch tube Q2 are turned off, thereby damaging the control module 150, such as the IO port of the MCU.

[0047] In one embodiment, the protection module 140 further includes a second current limiting resistor R4 and a second bias resistor R5. The second current limiting resistor R4 and the anti-backflow diode D1 are connected in series between the control module 150 and the control end of the second switch tube Q2. One end of the second bias resistor R5 is connected to the control end of the second switch tube Q2, and the second end of the second bias resistor R5 is connected to the series node of the second switch tube Q2 and the first switch tube Q1.

[0048] The second current limiting resistor R4 is used to prevent the second switch tube Q2 from driving too much current at the moment of being turned on, thereby damaging the control module 150, such as the IO port of the MCU.

[0049] In one of the embodiments, the weak light detection circuit also includes a temperature protection module 160. The temperature protection module 160, the load module 110 and the switch module 120 are connected in series between the output positive electrode PACK+ and the output negative electrode PACK- of the photovoltaic power supply. The temperature protection module 160 is, for example, a temperature fuse or an overcurrent fuse F1, and the temperature fuse F1 can also be attached to or close to the load module 110 when it is set. When a control failure occurs in the MOS tube or a short circuit failure occurs in the MOS tube, the weak light detection circuit discharges for a long time, the load module 110 heats up and causes the temperature fuse F1 to melt due to the heat, or a large current causes the overcurrent fuse F1 to melt, disconnecting the weak light detection circuit to prevent the weak light detection circuit from discharging for a long time, causing the detection load in the weak light detection circuit to heat up and burn the circuit board.

[0050] A second aspect of an embodiment of the present application provides a power device, including a photovoltaic interface for connecting a photovoltaic panel, an MPPT circuit connected to the photovoltaic interface, and a weak light detection circuit as described in any of the above embodiments, connected to the output positive pole PACK+ and the output negative pole PACK- of the MPPT circuit.

[0051] Among them, power devices can take many forms, such as:

[0052] 1. The power device does not include a battery module (or battery pack). The power device and the battery module are separate and can be connected to each other. The battery module includes a BMS board.

[0053] 2. The power device includes a battery cell module, and the battery module has a built-in BMS board and battery cells.

[0054] 3. The power device includes a battery cell module, but the battery cell module does not have a built-in BMS board. The relevant functions of the BMS are implemented by the circuit of the power device.

[0055] Optionally, the power device also includes a bidirectional AC-DC circuit and a bidirectional DC-DC circuit connected to the MPPT circuit.

[0056] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A weak light detection circuit, characterized in that: Used for weak light detection of photovoltaic power source; the weak light detection circuit comprises: Load module; A switch module, wherein the switch module and the load module are connected in series between the output positive electrode and the output negative electrode of the photovoltaic power source; A detection module, connected to the output positive electrode and the output negative electrode of the photovoltaic power source, and used to detect the output electrical parameters of the photovoltaic power source; A protection module, connected to the control end of the switch module, and used for driving the switch module to turn on for a first preset time and then turn off according to a driving signal; A control module is connected to the protection module and the detection module respectively. The control module is used to provide the drive signal and output a charging indication signal when the switch module is turned on and the output electrical parameter is greater than a preset threshold; the charging indication signal is used to allow the photovoltaic power supply to supply power to the connected power circuit.

2. The weak light detection circuit as claimed in claim 1, characterized in that: The switch module includes a first switch tube, the first switch tube is connected in series with the load module, and a control end of the first switch tube is connected to the protection module.

3. The weak light detection circuit as claimed in claim 2, characterized in that: The protection module includes a first capacitor, a discharge resistor and a first bias resistor, the first end of the first capacitor is connected to the control module, the second end of the first capacitor is connected to the control end of the first switch tube, the discharge resistor is connected to the first capacitor in parallel, the first end of the first bias resistor is connected to the control end of the first switch tube, the second end of the first bias resistor is grounded, and the first capacitor and the first bias resistor are used to configure the first preset duration.

4. The weak light detection circuit as claimed in claim 3, characterized in that: The protection module further includes a first current limiting resistor, and the first current limiting resistor and the first capacitor are connected in series between the control module and the control end of the first switch tube.

5. The weak light detection circuit according to any one of claims 2 to 4, characterized in that: The switch module further includes a second switch tube, which is connected in series with the first switch tube, wherein a control end of the second switch tube is connected to the control module, and the second switch tube is configured to be turned on when receiving the driving signal.

6. The weak light detection circuit as claimed in claim 5, characterized in that: The protection module further includes an anti-backflow diode, an anode of the anti-backflow diode is connected to the control module, and a cathode of the anti-backflow diode is connected to the control end of the second switch tube.

7. The weak light detection circuit as claimed in claim 6, characterized in that: The protection module also includes a second current limiting resistor and a second bias resistor, the second current limiting resistor and the anti-backflow diode are connected in series between the control module and the control end of the second switch tube, one end of the second bias resistor is connected to the control end of the second switch tube, and the second end of the second bias resistor is connected to the series node of the second switch tube and the first switch tube.

8. The weak light detection circuit as claimed in claim 1, characterized in that: The output electrical parameter includes a voltage value.

9. The weak light detection circuit as claimed in claim 1, characterized in that: It also includes a temperature protection module. The temperature protection module, the load module and the switch module are connected in series between the output positive electrode and the output negative electrode of the photovoltaic power source.

10. A power device, characterized in that: It includes a photovoltaic interface for connecting a photovoltaic panel, an MPPT circuit connected to the photovoltaic interface, and a weak light detection circuit as described in any one of claims 1 to 9, which is connected to the output positive electrode and the output negative electrode of the MPPT circuit.

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