Photovoltaic hysteresis control circuit

Abstract

The utility model discloses a photovoltaic hysteresis control circuit. The photovoltaic hysteresis control circuit comprises a voltage reference unit, a solar voltage sampling unit, a hysteresis voltage setting unit and a voltage judgment output unit, and the voltage reference unit, the solar voltage sampling unit and the voltage judgment output unit are all connected with the hysteresis voltage setting unit. The system has the advantages that photovoltaic solar power supply is very stable, and the problem of system MCU crash is effectively solved.

Description

Technical Field

[0001] This application relates to the technical field of photovoltaic control circuits, and particularly to a photovoltaic hysteresis control circuit. Background Art

[0002] When a photovoltaic solar panel is under normal illumination, it can output a voltage of 18V - 24V. After passing through a Stepdown DC / DC working power supply, this 18V - 24V voltage will output a 5V voltage. The 5V voltage output by the Stepdown DC / DC working power supply is used as the working voltage of the MCU. The normal working voltage range of the MCU requires 5V ± 10%. However, the output voltage of the photovoltaic solar panel is affected by the weather. Especially under extreme conditions (such as when the battery is discharged + weak light or on a cloudy day), the output voltage will be very unstable. When the battery of the MPPT device is discharged, it can only rely on the input voltage of the photovoltaic solar panel to start the MCU. In traditional related technical solutions, after the MCU enters the working state, it will control the charging drive chip to charge the battery of the MPPT device with the charging main power supply Stepdown DC / DC. Due to the very unstable photovoltaic power supply, the output voltage jitters greatly, resulting in the MCU starting under non-standard voltage and the problem of system MCU crashing. Summary of the Invention

[0003] To optimize traditional related solutions, this application provides a photovoltaic hysteresis control circuit.

[0004] The photovoltaic hysteresis control circuit provided by this application may include:

[0005] A voltage reference unit, a solar voltage sampling unit, a hysteresis voltage setting unit, and a voltage judgment output unit; the voltage reference unit, the solar voltage sampling unit, and the voltage judgment output unit are all connected to the hysteresis voltage setting unit.

[0006] The solution of this application may be further configured in a preferred example as:

[0007] The hysteresis voltage setting unit may include: a comparator U, a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. The first pin of the comparator is connected to the voltage reference unit, the second pin of the comparator is grounded, the third pin of the comparator is connected to one end of the second resistor R2, the fourth pin of the comparator is connected to the other end of the second resistor R2, the fifth pin of the comparator is connected to the first power supply terminal, the fifth pin of the comparator is also connected to one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, one end of the first resistor R1 is connected to the first power supply terminal, the other end of the first resistor R1 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is grounded.

[0008] In a preferred example, the solution of the present application can be further configured as follows:

[0009] The third pin of the comparator is connected to the solar voltage sampling unit.

[0010] In a preferred example, the solution of the present application can be further configured as follows:

[0011] The fourth pin of the comparator is connected to the voltage judgment output unit.

[0012] In a preferred example, the solution of the present application can be further configured as follows:

[0013] The voltage reference unit may include: a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a third resistor R3, and a three-terminal voltage regulator Z. One end of the third capacitor C3 is connected to the first power supply terminal, the other end of the third capacitor C3 is grounded, one end of the fourth capacitor C4 is connected to the first power supply terminal, the other end of the fourth capacitor C4 is grounded, one end of the third resistor R3 is connected to the first power supply terminal, the other end of the third resistor R3 is connected to the second pin of the three-terminal voltage regulator Z, the second pin of the three-terminal voltage regulator Z is connected to the first pin of the three-terminal voltage regulator Z, the third pin of the three-terminal voltage regulator Z is grounded, one end of the fifth capacitor C5 is connected to the first pin of the three-terminal voltage regulator Z, one end of the fifth capacitor C5 is also connected to the reference voltage, and the other end of the fifth capacitor C5 is grounded.

[0014] In a preferred example, the solution of the present application can be further configured as follows:

[0015] The solar voltage sampling unit may include: a fourth resistor R4, a fifth resistor R5, and a sixth capacitor C6. One end of the fourth resistor R4 is connected to the first power supply terminal, the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5, one end of the fifth resistor R5 is also connected to one end of the sixth capacitor C6, and the other ends of the fifth resistor R5 and the sixth capacitor C6 are both grounded.

[0016] In a preferred example, the solution of the present application can be further configured as follows:

[0017] The voltage judgment output unit may include: a zener diode D, a MOS transistor Q, and a sixth resistor R6. The drain of the MOS transistor Q is connected to the second power supply terminal, the source of the MOS transistor Q is grounded, one end of the sixth resistor R6 and one end of the zener diode D are both connected to the gate of the MOS transistor Q, the other end of the zener diode D is grounded, and the other end of the sixth resistor R6 is connected to the hysteresis voltage setting unit.

[0018] Compared with the prior art, the present application has at least the following beneficial effects:

[0019] 1. The photovoltaic hysteresis control circuit of the present application can independently increase the conduction voltage value to 8.6V and immediately cut off the power supply when it is lower than a certain value of 6.4V, ensuring the 5V operating voltage of the MCU.

[0020] 2. The overall power consumption of the photovoltaic hysteresis control circuit of the present application is low. The current of the reference part is only 0.1mA, and the current of the voltage sampling part is only 0.1mA. The judgment of the voltage reference and the input voltage both come from the input voltage of the photovoltaic solar panel. The turn-on voltage and the turn-off voltage can be independently set through the feedback resistor and the output pull-up resistor.

[0021] 3. The photovoltaic hysteresis control circuit of the present application has very stable photovoltaic solar power supply, effectively solving the problem of system MCU crashing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the overall block diagram of the photovoltaic hysteresis control circuit of the present application.

[0023] Figure 2 is the schematic diagram of the hysteresis voltage setting unit of the present application.

[0024] Figure 3 is the schematic diagram of the voltage reference unit of the present application.

[0025] Figure 4 is the schematic diagram of the solar voltage sampling unit of the application.

[0026] Figure 5 is the schematic diagram of the voltage judgment output unit of the application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following further describes the present application in detail with reference to the accompanying drawings.

[0028] Embodiment:

[0029] As Figure 1 shown, it is the overall block diagram of the photovoltaic hysteresis control circuit of this embodiment. The photovoltaic hysteresis control circuit may specifically include:

[0030] A voltage reference unit, a solar voltage sampling unit, a hysteresis voltage setting unit, and a voltage judgment output unit; the voltage reference unit, the solar voltage sampling unit, and the voltage judgment output unit are all connected to the hysteresis voltage setting unit.

[0031] As Figure 2As shown, the hysteresis voltage setting unit may specifically include: a comparator U, a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. The first pin of the comparator is connected to the voltage reference unit, the second pin of the comparator is grounded, the third pin of the comparator is connected to one end of the second resistor R2, the fourth pin of the comparator is connected to the other end of the second resistor R2, the fifth pin of the comparator is connected to the first power supply terminal, the fifth pin of the comparator is also connected to one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, one end of the first resistor R1 is connected to the first power supply terminal, the other end of the first resistor R1 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is grounded.

[0032] The third pin of the comparator is connected to the solar voltage sampling unit, the fourth pin of the comparator is connected to the voltage judgment output unit. The comparator U uses LM331CXF. In this figure, a feedback resistor is added to the comparator LM331CXF.

[0033] As Figure 3 shown, the voltage reference unit may specifically include: a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a third resistor R3, and a three-terminal voltage regulator Z. One end of the third capacitor C3 is connected to the first power supply terminal, the other end of the third capacitor C3 is grounded, one end of the fourth capacitor C4 is connected to the first power supply terminal, the other end of the fourth capacitor C4 is grounded, one end of the third resistor R3 is connected to the first power supply terminal, the other end of the third resistor R3 is connected to the second pin of the three-terminal voltage regulator Z, the second pin of the three-terminal voltage regulator Z is connected to the first pin of the three-terminal voltage regulator Z, the third pin of the three-terminal voltage regulator Z is grounded, one end of the fifth capacitor C5 is connected to the first pin of the three-terminal voltage regulator Z, one end of the fifth capacitor C5 is also connected to the reference voltage, and the other end of the fifth capacitor C5 is grounded. In this figure, the reference voltage uses a low-power voltage reference source ATL431LIBQ, the reference voltage is 2.5V, and the minimum operating current is as low as 0.1mA.

[0034] As Figure 4 shown, the solar voltage sampling unit may specifically include: a fourth resistor R4, a fifth resistor R5, and a sixth capacitor C6. One end of the fourth resistor R4 is connected to the first power supply terminal, the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5, one end of the fifth resistor R5 is also connected to one end of the sixth capacitor C6, and the other ends of the fifth resistor R5 and the sixth capacitor C6 are both grounded. The photovoltaic solar voltage sampling uses a resistance ratio of 68K / 100K, and the median voltage Vmd is set without feedback. Vmd = (2.5V / 34K) × 102K = 7.5V.

[0035] As Figure 5As shown in the figure, the pressure judgment output unit may specifically include a zener diode D, a MOS transistor Q, and a sixth resistor R6. The drain of the MOS transistor Q is connected to the second power supply terminal, the source of the MOS transistor Q is grounded, one end of the sixth resistor R6 and one end of the zener diode D are both connected to the gate of the MOS transistor Q, the other end of the zener diode D is grounded, and the other end of the sixth resistor R6 is connected to the hysteresis voltage setting unit.

[0036] Power-on voltage:

[0037] 34K / / 150K = 27.7K,

[0038] Von = (2.5V / 27.7K) × (68k + 27.7k) = 8.6V,

[0039] Power-off voltage:

[0040] 68K / / 250K = 53.5K,

[0041] Voff = (2.5 / 34K) × (53.5 + 34)k = 6.4V;

[0042] In the photovoltaic hysteresis control circuit of this embodiment, when the battery is discharged and only powered by the solar panel, the problem of MCU crashing and not starting caused by unstable power supply that may occur can avoid adding a watchdog circuit.

[0043] The photovoltaic hysteresis control circuit of this embodiment samples the photovoltaic solar power supply, adds a hysteresis control circuit, and uses a MOS transistor that controls the input power supply with the output. The board internal power supply for the working power supply Stepdown DC / DC is turned on only when the solar output voltage is higher than 8.6V and turned off only when it is lower than 6.4V. This method can effectively ensure the normal output of the 5V working voltage required by the MCU and prevent the MCU from crashing due to unstable voltage.

[0044] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0045] The above-described embodiments 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 foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A photovoltaic hysteresis control circuit, characterized in that, Comprising: A voltage reference unit, a solar voltage sampling unit, a hysteresis voltage setting unit, and a voltage judgment output unit; the voltage reference unit, the solar voltage sampling unit, and the voltage judgment output unit are all connected to the hysteresis voltage setting unit.

2. The photovoltaic hysteresis control circuit according to claim 1, wherein The hysteresis voltage setting unit includes: A comparator (U), a first resistor (R1), a second resistor (R2), a first capacitor (C1), and a second capacitor (C2). The first pin of the comparator is connected to the voltage reference unit, the second pin of the comparator is grounded, the third pin of the comparator is connected to one end of the second resistor (R2), the fourth pin of the comparator is connected to the other end of the second resistor (R2), the fifth pin of the comparator is connected to the first power supply terminal, the fifth pin of the comparator is also connected to one end of the first capacitor (C1), the other end of the first capacitor (C1) is grounded, one end of the first resistor (R1) is connected to the first power supply terminal, the other end of the first resistor (R1) is connected to one end of the second capacitor (C2), and the other end of the second capacitor (C2) is grounded.

3. The photovoltaic hysteresis control circuit according to claim 2, wherein, It further includes: The third pin of the comparator is connected to the solar voltage sampling unit.

4. The photovoltaic hysteresis control circuit according to claim 2, wherein It further includes: The fourth pin of the comparator is connected to the voltage judgment output unit.

5. The photovoltaic hysteresis control circuit according to claim 1, wherein The voltage reference unit includes: A third capacitor (C3), a fourth capacitor (C4), a fifth capacitor (C5), a third resistor (R3), and a three-terminal voltage regulator (Z). One end of the third capacitor (C3) is connected to the first power supply terminal, the other end of the third capacitor (C3) is grounded, one end of the fourth capacitor (C4) is connected to the first power supply terminal, the other end of the fourth capacitor (C4) is grounded, one end of the third resistor (R3) is connected to the first power supply terminal, the other end of the third resistor (R3) is connected to the second pin of the three-terminal voltage regulator (Z), the second pin of the three-terminal voltage regulator (Z) is connected to the first pin of the three-terminal voltage regulator (Z), the third pin of the three-terminal voltage regulator (Z) is grounded, one end of the fifth capacitor (C5) is connected to the first pin of the three-terminal voltage regulator (Z), one end of the fifth capacitor (C5) is also connected to the reference voltage, and the other end of the fifth capacitor (C5) is grounded.

6. The photovoltaic hysteresis control circuit according to claim 1, wherein The solar voltage sampling unit includes: A fourth resistor (R4), a fifth resistor (R5), and a sixth capacitor (C6). One end of the fourth resistor (R4) is connected to the first power supply terminal, the other end of the fourth resistor (R4) is connected to one end of the fifth resistor (R5), one end of the fifth resistor (R5) is also connected to one end of the sixth capacitor (C6), and the other ends of the fifth resistor (R5) and the sixth capacitor (C6) are both grounded.

7. The photovoltaic hysteresis control circuit according to claim 1, wherein The voltage judgment output unit includes: A zener diode (D), a MOS transistor (Q), and a sixth resistor (R6). The drain of the MOS transistor (Q) is connected to the second power supply terminal, the source of the MOS transistor (Q) is grounded, one end of the sixth resistor (R6) and one end of the zener diode (D) are both connected to the gate of the MOS transistor (Q), the other end of the zener diode (D) is grounded, and the other end of the sixth resistor (R6) is connected to the hysteresis voltage setting unit.

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