Surge protection circuit with anti-backflow function and energy storage system

Abstract

The utility model relates to the technical field of photovoltaic energy storage, and provides a surge protection circuit with an anti-backflow function and an energy storage system, comprising a main controller, and a surge current suppression module, an anti-backflow module, an input detection module and an output detection module which are electrically connected with the main controller. According to the utility model, the surge current suppression module is arranged between the inverter interface and the photovoltaic input end, and the surge current suppression module charges the input capacitor of the inverter circuit at the earlier stage that the current is unstable after the circuit is switched on, so that the purpose of suppressing the surge current is achieved, and the stability of equipment is improved; and meanwhile, the anti-backflow module is connected in series between the photovoltaic input end and the inversion interface, so that current backflow is avoided when the photovoltaic end is mistakenly connected to the inversion interface, and the safety of electronic components in the product is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to photovoltaic energy storage technical field especially, relates to a kind of surge protection circuit and energy storage system with anti backflow function. BACKGROUND

[0002] With the development of family photovoltaic energy storage, it is more and more widely used in family application. In the family photovoltaic energy storage system, micro-inversion will be connected, and there are a large number of capacitors as filter energy storage devices in micro-inversion. The internal charge of these capacitors will be slowly consumed after a long time of standing, and it will reach a condition close to no voltage. At this time, when photovoltaic is connected, because the voltage of the capacitor cannot change suddenly, a large charging current will be generated, and a surge current will be generated between the photovoltaic connection control circuit and the micro-inversion. The surge current may burn the MOS tube in the connection control circuit.

[0003] The traditional method uses large inductance or on-line resistance to suppress the current, but the large inductance will increase the volume and weight of the system, and the series resistance has the problem of low conversion efficiency.

[0004] In addition, in actual application, users may mistakenly connect photovoltaic to the micro-inversion interface. When the voltage exceeds the maximum voltage that the parts in the product can withstand, the product will be damaged. This greatly affects the reliability of the photovoltaic energy storage system. INVENTION CONTENTS

[0005] The utility model provides a kind of surge protection circuit and energy storage system with anti backflow function, solve the technical problems that the product stability is poor, safety is low caused by the large surge current in the existing inverter circuit, lack of port misconnection protection.

[0006] To solve the above technical problems, the utility model provides a kind of surge protection circuit with anti backflow function, including main controller and with the main controller electrical connection's surge current suppression module, anti backflow module, input detection module and output detection module;The anti backflow module is connected between photovoltaic input end and inverter interface, and its input end is connected with the input detection module connected with photovoltaic input end, and its output end is connected with the output detection module connected with inverter circuit;The surge current suppression module is connected with the anti backflow module in parallel.

[0007] The basic scheme sets surge current suppression module between inverter interface (for example, micro inverter) and photovoltaic input end. After the circuit is turned on, the input capacitor of inverter circuit is charged by surge current suppression module in the early stage of unstable current, to suppress surge current, to improve equipment stability. At the same time, anti backflow module is connected in series between photovoltaic input end and inverter interface. When photovoltaic end is misconnected to inverter interface, current backflow is avoided, and the safety of internal electronic components of the product is effectively guaranteed.

[0008] In a further embodiment, the surge current suppression module comprises a current limiting protection component and a switch component, the current limiting protection component comprises a current limiting resistor R1, a diode D1 and a diode D2; the positive electrode of the diode D1 is connected with the photovoltaic input end, and the negative electrode is connected with the input end of the switch component through the current limiting resistor R1; the positive electrode of the diode D2 is connected with the output end of the switch component, and the negative electrode is connected with the inverter interface; the control end of the switch component is connected with the main controller.

[0009] The scheme limits the pre-charging current in a very small range by using a current limiting resistor, which can effectively limit the current and protect the components in the circuit.

[0010] In a further embodiment, the switch component comprises a first switch tube Q1, a second switch tube Q2, a diode ZD1 and resistors R2-R6; the control electrode of the first switch tube Q1 is connected with the main controller through the resistor R2, the first end is connected with the control electrode of the second switch tube Q2 through the resistor R4 and the resistor R5 in sequence, and the second end is grounded; the two ends of the resistor R3 are connected with the control electrode and the second end of the first switch tube Q1 respectively; the first end of the second switch tube Q2 is connected with the positive electrode of the diode D2, and the second end is connected with the current limiting resistor R1; the positive electrode of the diode ZD1 is connected with the control electrode of the second switch tube Q2, and the negative electrode is connected with the second end of the second switch tube Q2; the resistor R6 is connected with the diode ZD1 in parallel.

[0011] The scheme sets a current switch control mechanism with a switch tube as the core, suppresses the surge current generated when the photovoltaic power supply is connected, and turns on the second switch tube Q2 of the main loop when the voltage difference between the output end and the input voltage is less than the preset difference (for example, 2V), so that the household photovoltaic energy storage system enters normal work, and the damage of the product caused by the external voltage is solved; thereby the reliability and stability of the circuit are improved, and the circuit failure and damage caused by the surge current are reduced.

[0012] In a further embodiment, the anti-inrush module comprises a third switch tube Q3, a fourth switch tube Q4 and resistors R7-R10; the control electrode of the third switch tube Q3 is connected with the main controller through the resistor R7, the first end is connected with the photovoltaic input end, and the second end is connected with the second end of the photovoltaic input end; the two ends of the resistor R8 are connected with the control electrode and the second end of the third switch tube Q3 respectively; the control electrode of the fourth switch tube Q4 is connected with the main controller through the resistor R9, and the first end is connected with the inverter interface; the two ends of the resistor R10 are connected with the control electrode and the second end of the fourth switch tube Q4 respectively.

[0013] The scheme is connected with the back-to-back MOS tube of the positive electrode of the main loop, when the user inserts the photovoltaic end into the inverter interface by mistake, no current flows into the circuit because the fourth switch tube Q4 is not turned on, so that the equipment and circuit are protected from the damage of reverse current.

[0014] In a further embodiment, the input detection module comprises a capacitor C1, a resistor R11, a resistor R12 and a resistor R13; one end of the resistor R12 is connected between the photovoltaic input end and the input end of the reverse flow prevention module through the resistor R11, and the other end is grounded through the resistor R13; the other end of the resistor R12 is connected with the main controller; and the capacitor C1 is connected with the resistor R13 in parallel.

[0015] In a further embodiment, the output detection module comprises a load voltage detection component and a load current detection component, the load voltage detection component is connected with the main controller, and the load current detection component is connected with the inverter interface.

[0016] The load voltage detection component comprises a capacitor C2, a resistor R14, a resistor R15, a resistor R16, a diode D3 and a diode D4; one end of the resistor R15 is connected between one end of the inverter interface and the reverse flow prevention module through the resistor R14, and the other end is grounded through the resistor R16; the capacitor C2 is connected with the resistor R16 in parallel; the positive electrode of the diode D3 is connected with the other end of the resistor R15, and the negative electrode is connected with the power supply end; the positive electrode of the diode D3 and the negative electrode of the diode D4 are connected with the main controller.

[0017] The input detection module and the input detection module are arranged on the input end (the photovoltaic input end) and the output end (the inverter interface) of the surge protection circuit, the voltage of the output end is monitored in real time whether it rises to the difference value less than the preset difference value (for example, 2V) from the input voltage, and then the normal work of the home photovoltaic energy storage system is ensured, and the damage of the surge current to the components is avoided.

[0018] In a further embodiment, the load current detection component comprises a resistor R17 and a resistor R18, one end of the resistor R17 is connected with the inverter interface, and the other end is grounded; the main controller is connected with both ends of the resistor R17; and the resistor R18 is connected with the resistor R17 in parallel.

[0019] The utility model also provides a kind of energy storage system, including a kind of surge protection circuit with reverse flow prevention function as described above, it further includes inverter circuit, and the inverter interface of the inverter circuit is connected with photovoltaic input end by surge protection circuit. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1The utility model embodiment provides a system block diagram of surge protection circuit with anti reverse flow function.

[0021] Figure 2 The utility model embodiment provides Figure 1 Partial hardware circuit diagram;

[0022] Among them: main control unit 1, surge current suppression module 2, anti reverse flow module 3, input detection module 4, output detection module 5, photovoltaic 6, inverter circuit 7. Specific implementation

[0023] The embodiment of the utility model is specifically illustrated below in combination with the drawings, and the embodiment is only for the purpose of illustration and can not be understood as the limitation of the utility model, including the drawing is only for reference and illustration, and does not constitute the limitation of the utility model patent protection range, because on the basis of not departing from the spirit and scope of the utility model, many changes can be made to the utility model.

[0024] Embodiment 1

[0025] The utility model embodiment provides a kind of surge protection circuit with anti reverse flow function, as shown in Figure 1 、 Figure 2 In the embodiment, including main control unit 1 and the surge current suppression module 2, anti reverse flow module 3, input detection module 4 and output detection module 5 of the electric connection with the main control unit 1;The anti reverse flow module 3 is connected between photovoltaic input end and inverter interface (such as Figure 2 MC1, MC2 in), its input end is connected with the input detection module 4 connected with photovoltaic input end, its output end is connected with the output detection module 5 connected with inverter circuit 7;The surge current suppression module 2 is parallelly connected with the anti reverse flow module 3.

[0026] Including filter capacitor C3, one end of filter capacitor C3 is connected with photovoltaic input end, and the other end is grounded.

[0027] In the embodiment, the surge current suppression module 2 includes current-limiting protection component and switch component, and the current-limiting protection component includes current-limiting resistor R1, diode D1 and diode D2;The anode of diode D1 is connected with photovoltaic input end, and the cathode is connected with the input end of the switch component by current-limiting resistor R1;The anode of diode D2 is connected with the output end of the switch component, and the cathode is connected with inverter interface;The control end of the switch component is connected with the main control unit 1.

[0028] The embodiment utilizes current-limiting resistor to limit pre-charge current in a very small range, which can effectively limit current and protect components in the circuit.

[0029] In the embodiment, the switch assembly comprises a first switch tube Q1, a second switch tube Q2, a diode ZD1 and resistors R2-R6; a control electrode of the first switch tube Q1 is connected with the main controller 1 (such as START in Figure 2 , a first end is connected with a control electrode of the second switch tube Q2 in sequence through resistors R4 and R5, and a second end is grounded; two ends of the resistor R3 are connected with the control electrode and the second end of the first switch tube Q1 respectively; a first end of the second switch tube Q2 is connected with a positive electrode of the diode D2, and a second end is connected with the current-limiting resistor R1; a positive electrode of the diode ZD1 is connected with the control electrode of the second switch tube Q2, and a negative electrode is connected with the second end of the second switch tube Q2; the resistor R6 is connected with the diode ZD1 in parallel.

[0030] Among them, the first switch tube Q1 can be selected as an NPN triode or a PNP triode according to requirements; the second switch tube Q2 can be selected as a P-channel MOS tube or an N-channel MOS tube according to requirements.

[0031] The diode ZD1 is preferably a voltage stabilizing diode.

[0032] The current switch control mechanism with the switch tube as the core is set in the embodiment, the inrush current generated when the photovoltaic power supply is connected is suppressed, the second switch tube Q2 of the main circuit is turned on again when the voltage at the output end rises to a difference value less than a preset difference value (for example, 2V) from the input voltage, the household photovoltaic energy storage system then enters normal work, and damage of the product caused by the external voltage is solved; thereby the reliability and stability of the circuit are improved, and circuit failure and damage caused by the inrush current are reduced.

[0033] In the embodiment, the anti-inrush module 3 comprises a third switch tube Q3, a fourth switch tube Q4 and resistors R7-R10; a control electrode of the third switch tube Q3 is connected with the main controller 1 (such as INV ON / OFF in Figure 2 ), a first end is connected with the photovoltaic input end, and a second end is connected with the second end connected with the photovoltaic input end; two ends of the resistor R8 are connected with the control electrode and the second end of the third switch tube Q3 respectively; a control electrode of the fourth switch tube Q4 is connected with the main controller 1 (such as MC ON / OFF in Figure 2 ), and a first end is connected with the inverter interface; two ends of the resistor R10 are connected with the control electrode and the second end of the fourth switch tube Q4 respectively.

[0034] Among them, the third switch tube Q3 and the fourth switch tube Q4 can be selected as a P-channel MOS tube or an N-channel MOS tube according to requirements.

[0035] The embodiment is back-to-back MOS tube connected to the positive electrode of the main circuit. When the user mistakenly inserts the photovoltaic end into the inverter interface, the fourth switch tube Q4 is not turned on, so no current flows into the circuit, thereby protecting the equipment and circuit from reverse current damage. This not only prevents equipment damage, but also prolongs its service life.

[0036] In the embodiment, the input detection module 4 includes a capacitor C1, a resistor R11, a resistor R12, and a resistor R13; one end of the resistor R12 is connected between the photovoltaic input end and the input end of the anti-backflow module 3 through the resistor R11, and the other end is grounded through the resistor R13; the other end of the resistor R12 is connected with the main controller 1 (such as VBUS in Figure 2

[0037] In the embodiment, the output detection module 5 includes a load voltage detection component and a load current detection component, the load voltage detection component is connected with the main controller 1, and the load current detection component is connected with the inverter interface.

[0038] The load voltage detection component includes a capacitor C2, a resistor R14, a resistor R15, a resistor R16, a diode D3, and a diode D4; one end of the resistor R15 is connected between one end of the inverter interface and the anti-backflow module 3 through the resistor R14, and the other end is grounded through the resistor R16; the capacitor C2 is connected with the resistor R16 in parallel; the positive electrode of the diode D3 is connected with the other end of the resistor R15, and the negative electrode is connected with the power supply end; the positive electrode of the diode D3 and the negative electrode of the diode D4 are connected with the main controller 1 (such as MC-VOUT in Figure 2

[0039] In the embodiment, the load current detection component includes a resistor R17 and a resistor R18, one end of the resistor R17 is connected with the inverter interface, and the other end is grounded; the main controller 1 is connected with both ends of the resistor R17; and the resistor R18 is connected with the resistor R17 in parallel.

[0040] Referring to

[0041] The main controller 1 samples the current sampling signal through MC4_CS and MC4-, and performs current sampling. Figure 2

[0042] ​​​Taking the main controller 1 as an MCU as an example, the working principle of the embodiment is as follows:

[0043] When the photovoltaic input end PV+ is connected to the photovoltaic 6, the MCU detects whether the VBUS signal voltage meets the requirements in real time through the input detection module 4, and if the requirements are met, the MCU outputs a high level to the B electrode of the first switch tube Q1 through the resistor R2, the first switch tube Q1 is turned on, the G electrode voltage of the second switch tube Q2 is pulled down to half of the original voltage plus the Vce of the first switch tube Q1, at this time, the VGS of the first switch tube Q1 is much higher than the threshold voltage (Vth) of the first switch tube Q1, after the first switch tube Q1 is turned on, the current flows through the diode D1, the resistor R1, the second switch tube Q2, the diode D2 and charges the input capacitor of the inverter circuit 7 (and the micro inverter) through the MC1 interface (inverter interface), and the pre-charging circuit forms a loop, at this time, the surge current in the loop is limited to a very small range by the current limiting resistor R1, and the value of the surge current is proportional to the photovoltaic input voltage.

[0044] When the voltage difference between the voltage of the MCU and the voltage of PV+ (calculated by the MCU according to the VBUS signal voltage feedback) is less than 2V, the MCU controls the GS voltage of the third switch tube Q3 and the fourth switch tube Q4 to be pulled up, and when the VGS voltage of the third switch tube Q3 and the fourth switch tube Q4 meets the condition of being turned on, the loop of the photovoltaic 6, the photovoltaic input end, the inverter interface and the inverter circuit 7 is turned on, and the household photovoltaic energy storage system starts to work normally. In this way, the surge current at the initial conduction can be effectively suppressed, and the long-term reliability of the circuit components can be ensured.

[0045] At the same time, the MCU outputs a low level to turn off the first switch tube Q1 and the second switch tube Q2, and the surge current suppression module 2 stops working.

[0046] The utility model embodiment sets up the surge current suppression module 2 between the inverter interface and the photovoltaic input end, in the early stage of unstable current after connecting the circuit, the input capacitor of the inverter circuit 7 is charged by the surge current suppression module 2, the purpose of suppressing the surge current is reached, the stability of equipment is improved, and at the same time, the anti-backflow module 3 is arranged in series between the photovoltaic input end and the inverter interface, when the photovoltaic end is connected to the inverter interface by mistake, the current backflow is avoided, and the safety of the internal electronic components of the product is effectively ensured.

[0047] Embodiment 2

[0048] The utility model also provides a kind of energy storage system, including a kind of surge protection circuit with anti-backflow function as described above, it also includes inverter circuit 7, and the inverter interface of the inverter circuit 7 is connected with photovoltaic input end by surge protection circuit.

[0049] The above embodiment is the preferred embodiment of the present application, but the embodiment of the present application is not limited by the above embodiment, and any change, modification, replacement, combination, simplification made without departing from the spirit and principle of the present application should be an equivalent replacement mode, and all are included in the protection scope of the present application.

Claims

1. A surge protection circuit with backflow prevention function, characterized in that: The application relates to a photovoltaic inverter, which comprises a main controller and a surge current suppression module, a backflow prevention module, an input detection module and an output detection module which are electrically connected with the main controller; the backflow prevention module is connected in series between a photovoltaic input end and an inverter interface, the input end of the backflow prevention module is connected with the input detection module connected with the photovoltaic input end, the output end of the backflow prevention module is connected with the output detection module connected with the inverter circuit, and the surge current suppression module is connected in parallel with the backflow prevention module.

2. The surge protection circuit with reverse flow prevention function according to claim 1, characterized in that: The surge current suppression module comprises a current-limiting protection component and a switch component; the current-limiting protection component comprises a current-limiting resistor R1, a diode D1 and a diode D2; the positive pole of the diode D1 is connected with the photovoltaic input end, the negative pole is connected with the input end of the switch component through the current-limiting resistor R1; the positive pole of the diode D2 is connected with the output end of the switch component, and the negative pole is connected with the inverter interface; and the control end of the switch component is connected with the main controller.

3. The surge protection circuit with reverse flow prevention function according to claim 2, characterized in that: The switch component comprises a first switch tube Q1, a second switch tube Q2, a diode ZD1 and resistors R2-R6; the control pole of the first switch tube Q1 is connected with the main controller through the resistor R2, the first end is connected with the control pole of the second switch tube Q2 through the resistor R4 and the resistor R5 in sequence, and the second end is grounded; the two ends of the resistor R3 are connected with the control pole and the second end of the first switch tube Q1 respectively; the first end of the second switch tube Q2 is connected with the positive pole of the diode D2, and the second end is connected with the current-limiting resistor R1; the positive pole of the diode ZD1 is connected with the control pole of the second switch tube Q2, and the negative pole is connected with the second end of the second switch tube Q2; and the resistor R6 is connected in parallel with the diode ZD1.

4. The surge protection circuit with reverse flow prevention function according to claim 1, wherein: The backflow prevention module comprises a third switch tube Q3, a fourth switch tube Q4 and resistors R7-R10; the control pole of the third switch tube Q3 is connected with the main controller through the resistor R7, the first end is connected with the photovoltaic input end, and the second end is connected with the second end of the photovoltaic input end; the two ends of the resistor R8 are connected with the control pole and the second end of the third switch tube Q3 respectively; the control pole of the fourth switch tube Q4 is connected with the main controller through the resistor R9, and the first end is connected with the inverter interface; the two ends of the resistor R10 are connected with the control pole and the second end of the fourth switch tube Q4 respectively.

5. The surge protection circuit with reverse flow prevention function according to claim 4, wherein: The input detection module comprises a capacitor C1, resistors R11, R12 and R13; one end of the resistor R12 is connected between the photovoltaic input end and the input end of the backflow prevention module through the resistor R11, the other end is grounded through the resistor R13; the other end of the resistor R12 is connected with the main controller; and the capacitor C1 is connected in parallel with the resistor R13.

6. The surge protection circuit with reverse flow prevention function according to claim 1, wherein: The output detection module comprises a load voltage detection component and a load current detection component; the load voltage detection component is connected with the main controller, and the load current detection component is connected with the inverter interface. The load voltage detection component includes a capacitor C2, a resistor R14, a resistor R15, a resistor R16, a diode D3 and a diode D4; one end of the resistor R15 is connected between one end of the inverter interface and the anti-backflow module through the resistor R14 and grounded through the resistor R16; the capacitor C2 is connected in parallel with the resistor R16; the positive electrode of the diode D3 is connected with the other end of the resistor R15, and the negative electrode is connected with the power supply end; the negative electrode of the diode D4 is connected with the other end of the resistor R15, and the positive electrode is grounded; the main controller is connected between the positive electrode of the diode D3 and the negative electrode of the diode D4.

7. The surge protection circuit with reverse flow prevention function according to claim 6, characterized in that: The load current detection component includes a resistor R17 and a resistor R18, one end of the resistor R17 is connected with the inverter interface, and the other end is grounded; the main controller is connected with both ends of the resistor R17; the resistor R18 is connected in parallel with the resistor R17.

8. An energy storage system characterized by: The surge protection circuit with the anti-backflow function includes the surge protection circuit according to any one of claims 1-7, and further includes an inverter circuit, and the inverter interface of the inverter circuit is connected with the photovoltaic input end through the surge protection circuit.

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