An auxiliary source start-up control circuit for an inverter

Abstract

The utility model belongs to control circuit technical field discloses an auxiliary source starting control circuit suitable for inverter, including port MPPT INPUT+ and port HV_AUX, the one end of resistance one and the positive terminal of diode D1 are connected to port MPPT INPUT+, the positive terminal of diode D3 and the positive terminal of diode D2 are connected to port HV_AUX, the one end of resistance R11 is connected to the negative terminal of diode D3, the negative terminal of diode D1 is connected the negative terminal of diode D2, the one end of resistance R1 and the one end of resistance R2, the other end of resistance R1 is connected the cathode of stabilivolt Z1 and the base of triode Q1, the anode of stabilivolt Z1 is connected port AGND, the utility model has the advantages of: having photovoltaic input under voltage back difference protection function, solves photovoltaic under voltage (weak light condition) and leads to auxiliary source repeated restart screen flickering problem.

Description

Technical Field

[0001] This utility model relates to the field of control circuit technology, and in particular to an auxiliary source start-up control circuit suitable for inverters. Background Technology

[0002] Inverters, also known as power conditioners, can be categorized into two types based on their application in photovoltaic (PV) power generation systems: stand-alone power supply inverters and grid-connected inverters. Based on waveform modulation methods, they can be classified as square wave inverters, stepped wave inverters, sine wave inverters, and combined three-phase inverters. For grid-connected systems, inverters can be further classified as transformer-type inverters and transformerless inverters, depending on whether they have a transformer. PV-storage inverters have multiple inputs, resulting in complex operating conditions and consequently complex auxiliary power source start-up and shutdown conditions. The auxiliary power source must be activated when the PV input voltage reaches a set value and shut down when it falls below the set value, with a hysteresis value required. The auxiliary power source must also be activated upon grid connection and activated by the user pressing a switch. Existing auxiliary power source start-up control circuits are complex in structure and unstable in performance, affecting the use of the inverter.

[0003] Therefore, it is necessary to provide an auxiliary power source start-up control circuit suitable for inverters, which has photovoltaic input undervoltage hysteresis protection function to solve the problem of repeated restarts and screen flickering caused by photovoltaic undervoltage (weak light conditions). Utility Model Content

[0004] This utility model discloses an auxiliary power source start-up control circuit suitable for inverters, which relates to power electronics technology, especially the auxiliary power supply start-up control of photovoltaic household energy storage inverters, and can effectively solve the technical problems involved in the background art.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] An auxiliary source start-up control circuit suitable for an inverter includes a port MPPT_INPUT+ and a port HV_AUX. The MPPT_INPUT+ port is connected to one end of a resistor and the positive terminal of diode D1. The HV_AUX port is connected to the positive terminals of diodes D3 and D2. The negative terminal of diode D3 is connected to one end of resistor R11. The negative terminal of diode D1 is connected to the negative terminal of diode D2, one end of resistor R1, and one end of resistor R2. The other end of resistor R1... One end of the resistor R2 is connected to the cathode of the Zener diode Z1 and the base of the transistor Q1. The anode of the Zener diode Z1 is connected to the port AGND. The other end of the resistor R2 is connected to the collector of the transistor Q1. The emitter of the transistor Q1 is connected to one end of the resistor R12, one end of the resistor R13, and the collector of the optocoupler U2. The other end of the resistor R12 is connected to the cathode of the optocoupler U2. The other end of the resistor R13 is connected to the anode of the optocoupler U2. The emitter of the optocoupler U2 is connected to the port UC3843_VCC.

[0007] The other end of resistor 1 is connected to one end of resistor R8 and one end of resistor R6. The other end of resistor R8 is connected to the drain of MOSFET Q2. The gate of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 is connected to the other end of resistor R12 and the cathode of voltage regulator U1. The other end of resistor R6 is connected to one end of resistor R7, one end of capacitor C1, the other end of resistor R11, and the reference stage of voltage regulator U1. The source of MOSFET Q2 is connected to the other end of resistor R10, the other end of resistor R7, the other end of capacitor C1, the anode of voltage regulator U1, and port AGND.

[0008] As a preferred improvement of this utility model: the resistor includes resistors R3, R4 and R5 connected in series.

[0009] As a preferred improvement of this utility model, the resistance values ​​of resistors R3, R4 and R5 are all 12K.

[0010] As a preferred improvement of this utility model: the voltage regulator U1 is TL431.

[0011] As a preferred improvement of this utility model: the MPPT_INPUT+ port is connected to the photovoltaic, the HV_AUX port is connected to the high-voltage side auxiliary power supply terminal, and the UC3843_VCC port is connected to the VCC pin of the auxiliary power source IC.

[0012] As a preferred improvement of this utility model, the port AGND is grounded.

[0013] As a preferred improvement of this utility model: the auxiliary source start-up control circuit further includes port BAT+, which is connected to one end of switch K1, one end of resistor R16 and the emitter of transistor Q3. The collector of transistor Q3 is connected to the positive terminal of diode D4, and the negative terminal of diode D4 is connected to port UC3843_VCC. The other end of resistor R16 is connected to the base of transistor Q3 and one end of resistor R17. The other end of resistor R17 is connected to the collector of transistor Q4. The other end of switch K1 is connected to one end of capacitor C2. The other end of capacitor C2 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R15 and the base of transistor Q4. The other end of resistor R15 is connected to the emitter of transistor Q4 and port AGND.

[0014] As a preferred improvement of this utility model, the BAT+ port is connected to a storage battery.

[0015] As a preferred improvement of this utility model, the switch K1 is a manual switch.

[0016] The beneficial effects of this utility model are as follows:

[0017] This circuit has a simple structure and stable performance. It mainly uses a combination of TL431 and optocoupler. The auxiliary source can be flexibly turned on / off by adjusting the voltage divider resistor. It also has a photovoltaic input undervoltage hysteresis protection function to solve the problem of repeated restarts of the auxiliary source and screen flickering caused by photovoltaic undervoltage (weak light conditions). Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0019] Figure 1 A schematic diagram of the inverter's architecture;

[0020] Figure 2 This is a schematic diagram of an auxiliary source start-up control circuit for an inverter according to the present invention;

[0021] Figure 3 This utility model Figure 2 Decomposition diagram Figure 1 ;

[0022] Figure 4 This utility model Figure 2 Decomposition diagram Figure 2 . Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] Please see Figures 2-3As shown, this utility model provides an auxiliary source start-up control circuit suitable for inverters, including a port MPPT_INPUT+ and a port HV_AUX. The MPPT_INPUT+ port is connected to one end of a resistor and the positive terminal of diode D1. The HV_AUX port is connected to the positive terminals of diodes D3 and D2. The negative terminal of diode D3 is connected to one end of resistor R11. The negative terminal of diode D1 is connected to the negative terminal of diode D2, one end of resistor R1, and one end of resistor R2. The other end of resistor R1 is connected to the cathode of Zener diode Z1 and the base of transistor Q1. The anode of Zener diode Z1 is connected to port AGND. The other end of resistor R2 is connected to the collector of transistor Q1. The emitter of transistor Q1 is connected to one end of resistor R12, one end of resistor R13, and the collector of optocoupler U2. The other end of resistor R12 is connected to the cathode of optocoupler U2, the other end of resistor R13 is connected to the anode of optocoupler U2, and the emitter of optocoupler U2 is connected to port UC3843_VCC; the other end of resistor R1 is connected to one end of resistor R8 and one end of resistor R6, the other end of resistor R8 is connected to the drain of MOSFET Q2, the gate of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10, the other end of resistor R9 is connected to the other end of resistor R12 and the cathode of voltage regulator U1, the other end of resistor R6 is connected to one end of resistor R7, one end of capacitor C1, the other end of resistor R11 and the reference stage of voltage regulator U1, and the source of MOSFET Q2 is connected to the other end of resistor R10, the other end of resistor R7, the other end of capacitor C1, the anode of voltage regulator U1 and port AGND. In this embodiment, the first resistor includes resistors R3, R4, and R5 connected in series, and the resistance values ​​of resistors R3, R4, and R5 are all 12KΩ. The voltage regulator U1 is a TL431, the MPPT_INPUT+ port is connected to the photovoltaic power supply, the HV_AUX port is connected to the high-voltage auxiliary power supply terminal, the UC3843_VCC port is connected to the VCC pin of the auxiliary power supply IC, and the AGND port is grounded.

[0029] Please see Figure 4As shown, the auxiliary power source start-up control circuit also includes port BAT+. Port BAT+ is connected to one end of switch K1, one end of resistor R16, and the emitter of transistor Q3. The collector of transistor Q3 is connected to the positive terminal of diode D4, and the negative terminal of diode D4 is connected to port UC3843_VCC. The other end of resistor R16 is connected to the base of transistor Q3 and one end of resistor R17. The other end of resistor R17 is connected to the collector of transistor Q4. The other end of switch K1 is connected to one end of capacitor C2. The other end of capacitor C2 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R15 and the base of transistor Q4. The other end of resistor R15 is connected to the emitter of transistor Q4 and port AGND. Port BAT+ is connected to the battery, and switch K1 is a manual switch.

[0030] Specifically, MPPT_INPUT+: positive terminal of photovoltaic input; HV_AUX: input terminal for high-voltage auxiliary power supply to low-voltage auxiliary power supply; BAT+: positive terminal of battery; UC3843_VCC: VCC pin connected to auxiliary power supply IC. U1: TL431, used to detect and determine the auxiliary power supply startup voltage; U2: Optocoupler, used to control the VCC power supply of the auxiliary power supply IC; Z1: 12V Zener diode, which, together with Q1, R1, and R2, forms a 12V line-stabilized circuit; R3, R4, R5, R6, and R7: Photovoltaic input voltage divider startup resistors; R8 and Q2: Photovoltaic input undervoltage hysteresis resistors; Startup voltage calculation: 2.5*((R3+R4+R5+R6+R7) / R7), shutdown voltage calculation: 2.5*((R6+R7) / R7))*((R3+R4+R5+Rx) / Rx), where Rx is the parallel resistance of R8, R6, and R7, i.e., Rx=R8*(R6+R7) / R8+(R6+R7). It should be further noted that any other components used to achieve the above effects should fall within the inventive concept of this utility model and should be protected within the scope of this utility model.

[0031] Working principle:

[0032] 1. Photovoltaic MPPT charging mode: MPPT_INPUT+ generates 12V through a line-stabilized circuit composed of R1, R2, Q1, and Z1.

[0033] When the MPPT input voltage is less than the set value of 20V, the voltage drop across R7 is less than 2.5V, TL431 U1 remains in the off state, optocoupler U2 does not conduct, and UC3843_VCC is not powered and does not work.

[0034] When the MPPT input voltage is greater than the set value of 20V, the voltage drop across R7 is greater than or equal to 2.5V, TL431 U1 conducts, optocoupler U2 conducts, and 12V flows through pins 4-3 of U2 to UC3843, allowing the auxiliary power supply IC to start working normally. Additionally, Q2 conducts, and R8 is connected in parallel, increasing the voltage drop across R7.

[0035] When the MPPT input voltage drops to the undervoltage point of 15V, the voltage divider across R7 still has 2.5V, keeping U2 conducting.

[0036] When the MPPT input voltage drops below the undervoltage point of 15V, the voltage drop across R7 is less than 2.5V, TL431 U1 is cut off, optocoupler U2 is not conducting, the power supply to UC3843_VCC is interrupted, and the auxiliary power source IC stops working.

[0037] 2. Grid charging mode: When the grid connection is normal, the high voltage auxiliary source usually outputs one line to the low voltage auxiliary source (HV_AUX), so that the voltage of R7 is ≥2.5V, TL431 U1 is turned on, optocoupler U2 is turned on, and 12V is sent to UC3843 through pins 4-3 of U2, and the auxiliary source IC starts working normally.

[0038] 3. Battery Inverter Mode: When the user presses the start switch K1, Q4 turns on, and then Q3 turns on. The battery BAT+ provides the start voltage to UC3843_VCC through D4, and the auxiliary power IC starts normally.

[0039] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An auxiliary source start-up control circuit suitable for inverters, characterized in that: The circuit includes ports MPPT_INPUT+ and HV_AUX. Port MPPT_INPUT+ is connected to one end of resistor 1 and the positive terminal of diode D1. Port HV_AUX is connected to the positive terminals of diode D3 and diode D2. The negative terminal of diode D3 is connected to one end of resistor R11. The negative terminal of diode D1 is connected to the negative terminal of diode D2, one end of resistor R1, and one end of resistor R2. The other end of resistor R1 is connected to the cathode of Zener diode Z1 and the base of transistor Q1. The anode of Zener diode Z1 is connected to port AGND. The other end of resistor R2 is connected to the collector of transistor Q1. The emitter of transistor Q1 is connected to one end of resistor R12, one end of resistor R13, and the collector of optocoupler U2. The other end of resistor R12 is connected to the cathode of optocoupler U2. The other end of resistor R13 is connected to the anode of optocoupler U2. The emitter of optocoupler U2 is connected to port UC3843_VCC. The other end of resistor 1 is connected to one end of resistor R8 and one end of resistor R6. The other end of resistor R8 is connected to the drain of MOSFET Q2. The gate of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 is connected to the other end of resistor R12 and the cathode of voltage regulator U1. The other end of resistor R6 is connected to one end of resistor R7, one end of capacitor C1, the other end of resistor R11, and the reference stage of voltage regulator U1. The source of MOSFET Q2 is connected to the other end of resistor R10, the other end of resistor R7, the other end of capacitor C1, the anode of voltage regulator U1, and port AGND.

2. The auxiliary source start-up control circuit for an inverter according to claim 1, characterized in that: The first resistor includes resistors R3, R4, and R5 connected in series.

3. The auxiliary source start-up control circuit for an inverter according to claim 2, characterized in that: The resistance values ​​of resistors R3, R4, and R5 are all 12K.

4. The auxiliary source start-up control circuit for an inverter according to claim 1, characterized in that: The voltage regulator U1 is a TL431.

5. The auxiliary source start-up control circuit for an inverter according to claim 1, characterized in that: The MPPT_INPUT+ port is connected to the photovoltaic system, the HV_AUX port is connected to the high-voltage side auxiliary power supply terminal, and the UC3843_VCC port is connected to the VCC pin of the auxiliary power source IC.

6. The auxiliary source start-up control circuit for an inverter according to claim 1, characterized in that: The port AGND is grounded.

7. The auxiliary source start-up control circuit for an inverter according to claim 1, characterized in that: The auxiliary source start-up control circuit also includes port BAT+, which is connected to one end of switch K1, one end of resistor R16, and the emitter of transistor Q3. The collector of transistor Q3 is connected to the positive terminal of diode D4, and the negative terminal of diode D4 is connected to port UC3843_VCC. The other end of resistor R16 is connected to the base of transistor Q3 and one end of resistor R17. The other end of resistor R17 is connected to the collector of transistor Q4. The other end of switch K1 is connected to one end of capacitor C2. The other end of capacitor C2 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R15 and the base of transistor Q4. The other end of resistor R15 is connected to the emitter of transistor Q4 and port AGND.

8. The auxiliary source start-up control circuit for an inverter according to claim 7, characterized in that: The BAT+ port is connected to the battery.

9. The auxiliary source start-up control circuit for an inverter according to claim 7, characterized in that: The switch K1 is a manual switch.

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