Detection Circuit Applied to a Photovoltaic System with a Fast Shutdown Mechanism

Abstract

The present invention provides a detection circuit applied to a photovoltaic system with a fast shutdown mechanism. The detection circuit includes: a voltage generator coupled to a solar panel in the photovoltaic system, and generating a first output voltage and a second output voltage according to a first control signal, a second control signal, and a voltage source output by the solar panel, and the voltage difference between the first output voltage and the second output voltage is less than or equal to the voltage source; wherein, the first control signal and the second control signal control the voltage generator to determine the first output voltage and the second output voltage of the voltage generator. This application can use the fewest circuit components to generate an output voltage for detection of 0.6V to 1V for output to test the solar panel, that is, it can simply determine whether the installed photovoltaic system is correct by measuring a lower output voltage than the prior art.

Description

Technical Field

[0001] The present invention relates to a detection circuit, and more particularly to a detection circuit applied to a photovoltaic system with a fast shutdown mechanism. Background Art

[0002] In current photovoltaic systems, no detection circuit is installed. After installing solar panels, the inspection is carried out after connecting multiple solar panels in series. Under normal shutdown conditions, the installation can be simply judged correct by measuring the output voltage. When the output voltage of each solar panel is between 10V and 80V, the output voltage for testing after connecting multiple solar panels in series may be between 100V and 800V. Summary of the Invention

[0003] To facilitate the detection after installing solar panels, an output voltage of 0.6V to 1.0V is sent out at the positive and negative terminals of the output. That is, the present invention uses the fewest circuit elements to generate a detection output voltage of 0.6V to 1V for output. That is, after connecting multiple solar panels in series, under shutdown conditions, the installation of the photovoltaic system can be simply judged correct by measuring an output voltage lower than that in the prior art.

[0004] The present invention provides a detection circuit, which can shorten the inspection time of the photovoltaic system and improve safety.

[0005] The present invention provides a detection circuit applied to a photovoltaic system with a fast shutdown mechanism. The detection circuit includes: a voltage generator, coupled to a solar panel in the photovoltaic system, and generating a first output voltage and a second output voltage according to a first control signal, a second control signal, and a voltage source output by the solar panel, and the voltage difference between the first output voltage and the second output voltage is less than or equal to the voltage source; wherein, the first control signal and the second control signal control the voltage generator to determine the first output voltage and the second output voltage of the voltage generator. Brief Description of the Drawings

[0006] Figure 1 Schematic diagram showing an embodiment of the present invention.

[0007] Figure 2 Practical schematic diagram showing an embodiment of the present invention.

[0008] Figure 3 Schematic diagram showing an embodiment of the present invention.

[0009] [Symbol Description]

[0010] 100, 300: Detection circuit

[0011] 101: Voltage generator

[0012] 102: High-voltage rectifier

[0013] 103: Level shifter

[0014] SW1 to SW3: Switches

[0015] PV: Solar panel

[0016] PV+, PV-: Voltage sources

[0017] OV1, OV2: Output voltages

[0018] C1, C2: Control signals

[0019] D1, D2: Regulated voltages

[0020] dio1, dio2: Diodes

[0021] R1 to R5: Resistors Detailed implementation manners

[0022] Please refer to Figure 1 , Figure 1 , which shows a schematic diagram of an embodiment of the present invention. The present invention provides a detection circuit 100 applied to a photovoltaic system with a fast shutdown mechanism. The detection circuit 100 includes: a voltage generator 101, a high-voltage rectifier 102, and a level shifter 103.

[0023] The voltage generator 101 is coupled to a solar panel PV in the photovoltaic system, and generates a first output voltage OV1 and a second output voltage OV2 according to a first control signal C1, a second control signal C2, and a voltage source PV+ output by the solar panel, and the voltage difference between the first output voltage OV1 and the second output voltage OV2 is less than or equal to the voltage source PV+; the high-voltage rectifier 102 is coupled to the solar panel PV and provides a first regulated voltage D1 according to the voltage source PV+; wherein, the first control signal C1 and the second control signal C2 control the voltage generator 101 to determine the first output voltage OV1 and the second output voltage OV2 of the voltage generator 101.

[0024] The level shifter 103 is coupled to the high-voltage rectifier 101. The level shifter 103 performs a boost conversion according to the first regulated voltage D1 and the second control signal C2 and outputs a second regulated voltage D2.

[0025] In an embodiment, the high-voltage rectifier 102 includes: a first resistor R1 and a second resistor R2, and the first regulated voltage D1 is the voltage division of the voltage source PV+ according to the series connection of the first resistor R1 and the second resistor R2.

[0026] In another embodiment, the second resistor R2 can be implemented by a Zener diode to stabilize the voltage value of the first regulated voltage D1.

[0027] In one embodiment, the voltage generator 101 includes: a first switch SW1, a second switch SW2, and a third switch SW3. A first switch SW1 is coupled to the solar panel, and a first diode dio1 and a third resistor R3 are serially coupled between the first switch SW1 and the solar panel. Moreover, a fourth resistor R4 is connected in parallel with the first diode dio1. The first switch SW1 determines whether to short-circuit according to the first control signal C1.

[0028] The second switch SW2 is coupled to the first diode dio1 and the third resistor R3. The second switch SW2 determines whether to open or short-circuit according to the voltage division among the first diode dio1, the third resistor R3, and the fourth resistor R4. When the first switch SW1 is short-circuited, the voltage source PV+ generates a voltage division according to the first diode dio1, the third resistor R3, and the fourth resistor R4 to make the second switch SW2 short-circuited.

[0029] In addition, a second diode dio2 is connected in series with the second switch SW2. When the second switch SW2 is short-circuited, a current flows through the second diode dio2 from the first output voltage OV1, and the second output voltage OV2 is determined according to the voltage division after the second switch SW2 is connected in series with a fifth resistor R5.

[0030] The third switch SW3 is coupled to the level converter 103, and the third switch SW3 is connected in parallel with the fifth resistor R5. When the third switch SW3 is short-circuited, since another voltage source PV- is grounded, the voltage difference between the first output voltage OV1 and the second output voltage OV2 is equal to the voltage source PV+. In one embodiment, the third switch SW3 determines whether to short-circuit according to the second control signal C2. In other words, the level converter 103 outputs a second regulated voltage D2 according to the second control signal C2 and the first regulated voltage D1 to determine the short-circuit of the third switch SW3.

[0031] In one embodiment, the first switch SW1 and the third switch SW3 are not short-circuited simultaneously. In another embodiment, the first switch SW1 and the third switch SW3 are implemented by an N-type metal oxide semiconductor field effect transistor (NMOSFET), and the second switch SW2 is implemented by a P-type metal oxide semiconductor field effect transistor (PMOSFET).

[0032] The operation behavior of the detection circuit 100 is described as follows:

[0033] First state (the solar panel PV is just installed and ready to supply power): The low-voltage first control signal C1 is zero (opening the first switch SW1), and the low-voltage second control signal C2 is zero (opening the third switch SW3). At this time, the solar panel PV is just installed, which is the initial state.

[0034] Second state (detection mode): The low-voltage first control signal C1 is one (shorting the first switch SW1), and the low-voltage second control signal C2 is zero (opening the third switch SW3). At this time, the voltage difference between the two ends of the first output voltage OV1 and the second output voltage OV2 is about 0.6V to 1V.

[0035] Third state (transition state): The low-voltage first control signal C1 is zero (opening the first switch SW1), and the low-voltage second control signal C2 is zero (opening the third switch SW3).

[0036] Fourth state (normal power generation mode): The low-voltage first control signal C1 is zero (opening the first switch SW1), and the low-voltage second control signal C2 is one (shorting the third switch SW3). At this time, the voltage difference between the two ends of the first output voltage OV1 and the second output voltage OV2 is the voltage source PV+.

[0037] Please also refer to Figure 2 , Figure 2 which shows the implementation schematic diagram of an embodiment of the present invention.

[0038] In this embodiment, the voltage sources PV+ and PV- generated by the solar panel are approximately in the range of 10V to 80V. In order to provide a stable high voltage, in this embodiment, the first resistor R1 in the high-voltage rectifier 102 is 100 kΩ, and the second resistor R2 is implemented by a Zener diode of 8.2V. Therefore, the high-voltage rectifier 102 will generate a voltage of 8.2V to supply the level converter 103, thereby controlling the third switch SW3. In addition, a capacitor with a capacitance value of 10 μF is coupled to both ends of the second resistor R2 to be used for stabilizing the voltage value of the first regulated voltage D1.

[0039] When entering the second state (detection mode), the first switch SW1 is shorted. The third resistor R3 of 1MΩ and the fourth resistor R4 of 10MΩ are in parallel with the second diode dio2 after voltage division. The second diode dio2 is implemented by a Zener diode of 7.5V. In this case, the second switch SW2 is turned on accordingly.

[0040] When the output of the solar panel is 10V, through the fifth resistor R5 of 800Ω, the second diode dio2 has a voltage drop of 0.8V and a current of about 11.5mA will flow through it, and the fifth resistor R5 will withstand about 0.1W of energy. At this time, the overall maximum load that can be tolerated is about 10.5mA, and a voltage of 0.6V is output.

[0041] When the output of the solar panel is 80V, through the fifth resistor R5 with a resistance of 800Ω, the second diode dio2 has a voltage drop of 1V and a current of about 99mA will flow through it, while the fifth resistor R5 will withstand about 7.8W of energy. At this time, the maximum load that can be tolerated as a whole is about 98mA, and an output voltage of 0.6V is output.

[0042] When entering the normal mode, the first switch is open, and the second switch is also open. Then, the second control signal C2 is at one (short-circuiting the third switch SW3) to turn on the third switch SW3, connecting the second output voltage OV2 to the voltage source PV-. Since the voltage source PV- is in a grounded state, the voltage difference between the first output voltage OV1 and the second output voltage OV2 will be equal to the voltage source PV+.

[0043] Please refer to Figure 3 , Figure 3 shows a schematic diagram of an embodiment of the present invention. In this embodiment, the difference between the detection circuit 300 and 100 is that the detection circuit 300 does not include the high-voltage rectifier 102 and the level converter 103. In this embodiment, the third switch SW3 directly determines whether to short-circuit according to the second control signal C2, and the rest of the principles are the same as those described above, and will not be elaborated here.

[0044] In summary, the present invention provides a detection circuit after the installation of a solar panel. Its output terminal can send out an output voltage of 0.6V to 1.0V in the detection mode. That is, the present invention uses the fewest circuit elements to generate an output voltage of 0.6V to 1V for detection to test the solar panel, and can simply determine whether the installed photovoltaic system is correct by measuring an output voltage lower than that of the prior art.

Claims

1. A detection circuit applied to a photovoltaic system with a fast shutdown mechanism, characterized in that, The detection circuit includes: A voltage generator, coupled to a solar panel in the photovoltaic system, and generating a first output voltage and a second output voltage according to a first control signal, a second control signal, and a voltage source output by the solar panel, and a voltage difference between the first output voltage and the second output voltage is less than or equal to the voltage source; Wherein, the first control signal and the second control signal control the voltage generator to determine the first output voltage and the second output voltage of the voltage generator.

2. The detection circuit according to claim 1, wherein The detection circuit includes: A high-voltage rectifier, coupled to the solar panel, and providing a first regulated voltage according to the voltage source; and A level converter, coupled to the high-voltage rectifier, and performing a boost conversion according to the first regulated voltage and the second control signal and outputting a second regulated voltage.

3. The detection circuit according to claim 2, wherein The high-voltage rectifier includes: a first resistor and a second resistor, and the first regulated voltage is a voltage division of the voltage source according to the series connection of the first resistor and the second resistor.

4. The detection circuit according to claim 3, wherein The voltage generator includes: A first switch, coupled to the solar panel, and in series between the first switch and the voltage source; Coupled to a first diode and a third resistor, and the first diode is in parallel with a fourth resistor, and the first switch determines whether to short-circuit according to the first control signal; A second switch, coupled to the first diode and the third resistor, and the second switch determines whether to open or short-circuit according to the voltage division between the first diode, the third resistor, and the fourth resistor; when the first switch is short-circuited, the voltage source generates a voltage division according to the first diode, the third resistor, and the fourth resistor to make the second switch short-circuited; A second diode, in series with the second switch, when the second switch is short-circuited, a current flows through the second diode from the first output voltage, and the second output voltage is determined according to the voltage division after the series connection of the second switch and a fifth resistor and subtracting the voltage drop of the second diode; A third switch, coupled to the level converter and in parallel with the fifth resistor, when the third switch is short-circuited, the voltage difference between the first output voltage and the second output voltage is equal to the voltage source; Wherein, the first switch and the third switch are not short-circuited at the same time.

5. The detection circuit according to claim 4, wherein When the detection circuit is in the detection mode, the first control signal is one to short-circuit the first switch, and the second control signal is zero to open the third switch. At this time, the voltage difference output at both ends of the first output voltage and the second output voltage is 0.6V to 1V.

6. The detection circuit according to claim 4, wherein When the detection circuit is in a normal power generation mode, the first control signal is zero to open the first switch, and the second control signal is one to short-circuit the third switch. At this time, the voltage difference output at both ends of the first output voltage and the second output voltage is the voltage source.

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