CN116247957A - Micro inverter and start-up control method - Google Patents

Micro inverter and start-up control method Download PDF

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Publication number
CN116247957A
CN116247957A CN202310239157.9A CN202310239157A CN116247957A CN 116247957 A CN116247957 A CN 116247957A CN 202310239157 A CN202310239157 A CN 202310239157A CN 116247957 A CN116247957 A CN 116247957A
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CN
China
Prior art keywords
primary side
bridge circuit
phase angle
primary
voltage
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CN202310239157.9A
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Chinese (zh)
Inventor
汪子晨
谷雨
陈巧地
王宝基
豆冲
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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Priority to CN202310239157.9A priority Critical patent/CN116247957A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
    • H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
    • H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The application discloses a micro inverter and a start-up control method, comprising the following steps: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding; the output end of the primary side H-bridge circuit is connected with a corresponding primary side winding; the secondary side bridge arm circuit is connected with the secondary side winding; the output end of the secondary side bridge arm circuit is connected with a load or a power grid through a switch; the secondary side bridge arm circuit comprises a secondary side capacitor; and the controller is used for obtaining reactive compensation current according to the power grid voltage and the secondary side capacitor before the switch is closed, controlling an inward shift phase angle and an outward shift phase angle corresponding to the primary side H bridge circuit according to the reactive compensation current, enabling the primary side H bridge circuit to output reactive current, charging the secondary side capacitor, enabling the voltage of the secondary side capacitor to be presynchronized with the power grid voltage, avoiding larger current impact when the switch is closed, causing overlarge impact to the switch, and avoiding damaging the switch or triggering the micro inverter for protection.

Description

Micro inverter and start-up control method
Technical Field
The application relates to the technical field of inverters, in particular to a micro-inverter and a start-up control method.
Background
With the continuous maturity of photovoltaic power generation, photovoltaic power generation is increasingly applied to families, namely household photovoltaic. With the development of the photovoltaic system for the household, the current household inverter is smaller and smaller, and a micro inverter is formed.
Currently, a micro-inverter may include at least one primary winding, each primary winding for connecting a corresponding photovoltaic panel. Wherein each primary winding is connected with a corresponding primary H-bridge circuit.
The micro inverter can realize grid connection of the micro inverter by controlling the internal and external phase shifting angles of the primary side H-bridge circuit and the secondary side bridge arm circuit. The internal phase shift angle refers to the phase shift angle of a switching tube in the primary side H bridge circuit, and the external phase shift angle refers to the phase shift angle between the switching tubes of the primary side H bridge circuit and the secondary side bridge arm circuit.
Because the alternating current side of the micro inverter is connected with the power grid through the relay, the relay is in an open state in the shutdown state of the micro inverter, when the photovoltaic panel voltage is detected to be started, if the relay is directly closed, larger impact current can be generated on the secondary side capacitor, and the secondary side capacitor is triggered to be protected or damaged.
Disclosure of Invention
In view of this, the present application provides a micro inverter and a startup control method, which can avoid the secondary capacitor from generating a larger impact current when the micro inverter is started, so as to ensure the normal startup grid-connected operation.
The application provides a micro inverter, including: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
the output end of the primary side H-bridge circuit is connected with a corresponding primary side winding; the secondary side bridge arm circuit is connected with the secondary side winding; the output end of the secondary side bridge arm circuit is connected with a load or a power grid through a switch; the secondary side bridge arm circuit comprises a secondary side capacitor;
and the controller is used for obtaining reactive compensation current according to the power grid voltage and the secondary side capacitor before the switch is closed, controlling an inward shift phase angle and an outward shift phase angle corresponding to the primary side H-bridge circuit according to the reactive compensation current, enabling the primary side H-bridge circuit to output reactive current, and enabling the voltage of the secondary side capacitor to be presynchronized with the power grid voltage.
Preferably, the primary winding and the primary H-bridge circuit are multiple and correspond to each other one by one; the following at least two primary side H-bridge circuits are connected with a direct current power supply: a first primary H-bridge circuit and a second primary H-bridge circuit;
the controller is specifically configured to distribute reactive compensation current according to a first power of a direct current power supply connected to the first primary side H-bridge circuit and a second power of a direct current power supply connected to the second primary side H-bridge circuit, obtain a first reactive compensation current and a second reactive compensation current, control an internal shift angle and an external shift angle corresponding to the first primary side H-bridge circuit according to the first reactive compensation current, and control an internal shift angle and an external shift angle corresponding to the second primary side H-bridge circuit according to the second reactive compensation current.
Preferably, the controller is further configured to obtain a reactive power regulation current through the regulator according to a voltage difference between the grid voltage and the secondary capacitor, obtain a corresponding internal phase angle regulation amount and an external phase angle regulation amount according to the reactive power regulation current, and correct the internal phase angle and the external phase angle respectively by using the internal phase angle regulation amount and the external phase angle regulation amount.
Preferably, the controller is specifically configured to distribute the reactive power adjustment current according to the first power and the second power, obtain a first reactive power adjustment current and a second reactive power adjustment current, correct an internal phase angle and an external phase angle corresponding to the first primary side H-bridge circuit according to the first reactive power adjustment current, and correct an internal phase angle and an external phase angle corresponding to the second primary side H-bridge circuit according to the second reactive power adjustment current.
Preferably, the controller is further configured to obtain a forward charging current from the primary side to the secondary side according to a difference value between the voltage of the secondary side capacitor and a preset voltage of the secondary side before the voltage of the secondary side capacitor is pre-synchronized with the power grid voltage, and control an internal shift phase angle and an external shift phase angle corresponding to the primary side H-bridge circuit according to the forward charging current.
Preferably, the controller is specifically configured to distribute the forward charging current according to the first power and the second power, obtain a first forward charging current and a second forward charging current, and control an internal shift phase angle and an external shift phase angle corresponding to the first primary side H-bridge circuit according to the first forward charging current; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the second primary side H bridge circuit according to the second forward charging current.
Preferably, at least one of the primary side H-bridge circuits is not connected to a dc power supply; the input end of the primary side H bridge circuit is connected with a primary side capacitor;
the controller is also used for obtaining reverse charging current from the secondary side to the primary side according to the difference value between the voltage of the primary side capacitor and the primary side preset voltage after the voltage of the secondary side voltage is charged to the secondary side preset voltage; and controlling the internal shift phase angle of the primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
Preferably, the primary side H-bridge circuit includes at least two primary side H-bridge circuits that are not connected to a dc power supply: a third primary H-bridge circuit and a fourth primary H-bridge circuit;
the controller is specifically configured to obtain a first reverse charging current from the secondary side to the primary side according to a first difference value between a voltage of a primary side capacitor of the third primary side H-bridge circuit and a preset voltage of the primary side; controlling an inward shift phase angle and an outward shift phase angle corresponding to the third primary side H bridge circuit according to the first reverse charging current, so that the voltage of a primary side capacitor of the third primary side H bridge circuit is charged to a primary side preset voltage; obtaining a second reverse charging current from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and a preset primary side voltage; and controlling an inward shift phase angle and an outward shift phase angle corresponding to the fourth primary side H bridge circuit according to the second reverse charging current, so that the voltage of the primary side capacitor of the fourth primary side H bridge circuit is charged to the primary side preset voltage.
Preferably, the number of the transformers is multiple, each transformer comprises a primary winding and a secondary winding, and the primary windings are in one-to-one correspondence with the primary H-bridge circuits; the two ends of the secondary winding of all the transformers are connected in parallel and connected with the input end of the secondary bridge arm circuit.
Preferably, the transformer is one, and the transformer comprises a plurality of primary windings and a secondary winding, and the primary H-bridge circuit corresponds to the primary windings one by one.
Preferably, the direct current power supply is a photovoltaic panel.
The application also provides a start-up control method of the micro inverter, the micro inverter comprises: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
the method comprises the following steps:
before the switch is closed, reactive compensation current is obtained according to the power grid voltage and the secondary side capacitance;
and controlling the corresponding internal shift phase angle and external shift phase angle of the primary side H-bridge circuit according to the reactive compensation current, so that the primary side H-bridge circuit outputs reactive current, and the voltage of the secondary side capacitor is presynchronized with the power grid voltage.
Preferably, at least two of the following primary side H-bridge circuits are connected to a dc power supply: a first primary H-bridge circuit and a second primary H-bridge circuit;
the method comprises the steps of controlling an inner shift phase angle and an outer shift phase angle corresponding to a primary side H bridge circuit according to reactive compensation current, and specifically comprising the following steps:
The reactive compensation current is distributed according to the first power of the direct current power supply connected with the first primary side H bridge circuit and the second power of the direct current power supply connected with the second primary side H bridge circuit, so that a first reactive compensation current and a second reactive compensation current are obtained;
and controlling the internal shift phase angle and the external shift phase angle corresponding to the first primary side H bridge circuit according to the first reactive compensation current, and controlling the internal shift phase angle and the external shift phase angle corresponding to the second primary side H bridge circuit according to the second reactive compensation current.
Preferably, the method further comprises:
obtaining reactive power regulation current through a regulator according to the voltage difference between the power grid voltage and the secondary side capacitor;
obtaining corresponding internal phase shift angle adjustment quantity and external phase shift angle adjustment quantity according to reactive power adjustment current;
and respectively correcting the inner shift phase angle and the outer shift phase angle by using the inner shift phase angle adjustment quantity and the outer shift phase angle adjustment quantity.
Preferably, corresponding internal phase shift angle adjustment quantity and external phase shift angle adjustment quantity are obtained according to reactive power adjustment current; respectively correcting the inner shift angle and the outer shift angle by using the inner shift angle adjustment quantity and the outer shift angle adjustment quantity, and specifically comprises the following steps:
distributing reactive power regulating current according to the first power and the second power to obtain a first reactive power regulating current and a second reactive power regulating current;
And correcting the internal shift phase angle and the external shift phase angle corresponding to the first primary side H bridge circuit according to the first reactive power regulating current, and correcting the internal shift phase angle and the external shift phase angle corresponding to the second primary side H bridge circuit according to the second reactive power regulating current.
Preferably, the method further comprises:
before the voltage of the secondary side capacitor is presynchronized with the power grid voltage, the forward charging current from the primary side to the secondary side is obtained according to the difference value between the voltage of the secondary side capacitor and the preset voltage of the secondary side;
and controlling the inner shift phase angle and the outer shift phase angle corresponding to the primary side H bridge circuit according to the forward charging current.
Preferably, the forward charging current from the primary side to the secondary side is obtained according to the difference value between the voltage of the secondary side capacitor and the preset voltage of the secondary side; according to the interior shift angle and the exterior shift angle that the primary side H bridge circuit of charging current control corresponds, specifically include:
distributing forward charging current according to the first power and the second power to obtain a first forward charging current and a second forward charging current;
controlling an inner shift phase angle and an outer shift phase angle corresponding to the first primary side H bridge circuit according to the first forward charging current; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the second primary side H bridge circuit according to the second forward charging current.
Preferably, at least one of the primary side H-bridge circuits is not connected to a dc power supply; the input end of the primary side H bridge circuit is connected with a primary side capacitor;
Further comprises:
after the voltage of the secondary side voltage is charged to the secondary side preset voltage, the reverse charging current from the secondary side to the primary side is obtained according to the difference value between the voltage of the primary side capacitor and the primary side preset voltage;
and controlling the internal shift phase angle of the primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
Preferably, the method includes controlling an internal phase angle of a primary side H-bridge circuit, which is not connected to a dc power supply, according to a reverse charging current, so that a voltage of a primary side capacitor is charged to a primary side preset voltage, specifically including:
obtaining a first reverse charging current from the secondary side to the primary side according to a first difference value between the voltage of a primary side capacitor of a third primary side H bridge circuit and a primary side preset voltage; controlling the internal shift phase angle of the third primary side H bridge circuit according to the first reverse charging current, so that the voltage of the primary side capacitor of the third primary side H bridge circuit is charged to the primary side preset voltage;
obtaining a second reverse charging current from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and a preset primary side voltage; and controlling the internal shift phase angle of the fourth primary side H-bridge circuit according to the second reverse charging current, so that the voltage of the primary side capacitor of the fourth primary side H-bridge circuit is charged to the primary side preset voltage.
From this, this application has following beneficial effect:
because the secondary side bridge arm circuit is not connected with the power grid before the micro inverter is started, the energy of the secondary side capacitor is required to be provided by the primary side, namely the primary side charges the secondary side. According to the technical scheme, reactive compensation current is obtained according to the power grid voltage and the size of the secondary side capacitor, and then the reactive compensation current corresponding to the output of the primary side H-bridge circuit is controlled to charge the secondary side capacitor, specifically, the controller needs to obtain an internal phase angle and an external phase angle according to the reactive compensation current output as required, and then the primary side H-bridge circuit and the secondary side bridge arm circuit are controlled according to the internal phase angle and the external phase angle, when the voltage of the secondary side capacitor is synchronous with the power grid voltage, the switch is closed, so that overlarge impact on the switch can be avoided, and damage to the switch or the protection of the micro inverter is avoided.
Drawings
Fig. 1 is a schematic diagram of a micro inverter according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of another micro inverter according to an embodiment of the present disclosure;
fig. 3 is a control schematic diagram of a micro inverter according to an embodiment of the present disclosure;
fig. 4 is a control schematic diagram of another micro inverter according to an embodiment of the present disclosure;
Fig. 5 is a schematic diagram of yet another micro inverter according to an embodiment of the present disclosure;
FIG. 6 is a schematic diagram illustrating control of primary capacitor precharge according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of precharge control of a primary capacitor of a third primary H-bridge according to an embodiment of the present disclosure;
fig. 8 is a schematic diagram of precharge control of a primary capacitor of a fourth primary H-bridge according to an embodiment of the present disclosure;
fig. 9 is a flowchart of a method for controlling start-up of a micro inverter according to an embodiment of the present application.
Detailed Description
In order to enable those skilled in the art to better understand and implement the technical solutions provided in the embodiments of the present application, the topology of the micro inverter is first described below with reference to the accompanying drawings.
Referring to fig. 1, a schematic diagram of a micro inverter according to an embodiment of the present application is shown.
The micro inverter provided by the embodiment of the application can be connected with at least one input, and comprises a primary side H-bridge circuit, a transformer and a secondary side bridge arm circuit; in fig. 1, four-way input is taken as an example, and four transformers are taken as an example, wherein each transformer comprises a primary winding and a secondary winding; the primary windings are in one-to-one correspondence with the primary H bridge circuits, each primary winding is connected with one primary H bridge circuit, each primary H bridge circuit is connected with a direct current power supply, and the direct current power supply can be a photovoltaic panel, a battery or both the photovoltaic panel and the battery. In this embodiment, a photovoltaic panel is taken as an example for the direct current power supply.
In addition, for some scenarios, the input of the primary H-bridge circuit may be connected to the photovoltaic panel, while the input of the primary H-bridge circuit may not be connected to the photovoltaic panel, e.g., the photovoltaic panel may be removed for maintenance, or may be blocked, without energy output, etc.
The first to fourth primary H-bridge circuits H1 to H4 each include four switching transistors S1 to S4.
The input end of the first primary side H bridge circuit H1 is connected with a first direct current power supply PV1, and the input end of the first primary side H bridge circuit H1 is connected with a primary side capacitor C1. The input end of the second primary side H bridge circuit H2 is connected with a second direct current power supply PV2, and the input end of the second primary side H bridge circuit H2 is connected with a primary side capacitor C2. The input end of the third primary side H bridge circuit H3 is connected with a third direct current power supply PV3, and the input end of the third primary side H bridge circuit H3 is connected with a primary side capacitor C3. The input end of the fourth primary side H bridge circuit H4 is connected with a fourth direct current power supply PV4, and the input end of the fourth primary side H bridge circuit H4 is connected with a primary side capacitor C4.
The secondary side bridge arm circuit comprises a bidirectional switch bridge arm and a capacitor bridge arm, an upper bridge arm of the bidirectional switch bridge arm comprises bidirectional switches S5 and S6, and a lower bridge arm of the bidirectional switch bridge arm comprises bidirectional switches S7 and S8. The upper bridge arm of the capacitor bridge arm comprises a secondary side capacitor Cg1, and the lower bridge arm comprises a secondary side capacitor Cg2.
The secondary bridge arm circuit is connected with a load or a power grid through the EMI circuit and a switch S, wherein the switch S can be a relay or other types of switches, and the embodiment of the application is not particularly limited.
Referring to fig. 2, a schematic diagram of another micro inverter according to an embodiment of the present application is shown.
Fig. 2 differs from fig. 1 in that only one transformer is included in fig. 2, but the transformer includes a plurality of primary windings and one secondary winding. The primary side H-bridge circuits are in one-to-one correspondence with the primary side windings.
In the micro inverter shown in fig. 1 or fig. 2, when the power is started, a voltage on the secondary side capacitor is not synchronous with a power grid voltage, so that a large impact current exists when the switch S is closed, and the secondary side capacitor may be triggered to be protected or damaged.
The micro inverter provided by the embodiment of the application can firstly synchronize the voltage of the secondary side capacitor with the power grid voltage when the micro inverter is started, and then the switch is closed, so that the switch is prevented from being subjected to larger impact when being closed, and the switch and the micro inverter are protected.
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with the present application are described in further detail below.
Referring to fig. 3, a control schematic diagram of a micro inverter according to an embodiment of the present application is shown.
The micro inverter provided in the embodiment of the application includes: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
the output end of the primary side H-bridge circuit is connected with a corresponding primary side winding; the secondary side bridge arm circuit is connected with the secondary side winding; the output end of the secondary side bridge arm circuit is connected with a load or a power grid through a switch; the secondary bridge arm circuit includes a secondary capacitor.
It should be understood that the number of transformers may be plural or one, and specific hardware circuits may be referred to in fig. 1 and fig. 2, which are not described herein.
The controller is used for obtaining reactive compensation current according to the power grid voltage and the secondary side capacitor before the switch is closed, specifically, the phase-locked loop can be utilized to lock the power grid voltage Vg, and the phase angle and the amplitude of the power grid voltage Vg are obtained; and calculating to obtain reactive compensation current I_com according to the phase angle and amplitude of the grid voltage Vg and the capacitance value of the secondary side capacitor.
And the controller controls the internal shift phase angle D1 and the external shift phase angle D2 corresponding to the primary side H-bridge circuit according to the reactive compensation current I_com, so that the primary side H-bridge circuit outputs reactive current, and when the voltage of the secondary side capacitor is synchronous with the voltage of the power grid, the switch is controlled to be closed, thus the start-up is completed, and the micro inverter starts grid-connected operation.
The internal phase shift angle refers to the phase shift angle of a switching tube between two bridge arms in the primary side H-bridge circuit, and the external phase shift angle refers to the phase shift angle of the switching tube between the primary side H-bridge circuit and the secondary side bridge arm circuit.
It should be understood that synchronizing the voltage of the secondary side capacitor with the grid voltage means that the phase angle of the voltage of the secondary side capacitor is the same as the phase angle of the grid voltage, and the amplitude of the voltage of the secondary side capacitor is the same as the amplitude of the grid voltage.
In the embodiment of the application, the controller can calculate the reactive compensation current by utilizing the feedforward link to obtain the feedforward internal shift angle and the feedforward external shift angle.
Because the secondary side bridge arm circuit is not connected with the power grid before the micro inverter is started, the energy of the secondary side capacitor is required to be provided by the primary side, namely the primary side charges the secondary side. According to the technical scheme, reactive compensation current is obtained according to the power grid voltage and the size of the secondary side capacitor, and then the reactive compensation current corresponding to the output of the primary side H-bridge circuit is controlled to charge the secondary side capacitor, specifically, the controller needs to obtain an internal phase angle and an external phase angle according to the reactive compensation current output as required, and then the primary side H-bridge circuit and the secondary side bridge arm circuit are controlled according to the internal phase angle and the external phase angle, when the voltage of the secondary side capacitor is synchronous with the power grid voltage, the switch is closed, so that overlarge impact on the switch can be avoided, and damage to the switch or the protection of the micro inverter is avoided.
The micro-inverter shown in fig. 1 and fig. 2 each include a secondary side bridge arm circuit, and in specific control, the phase shift angle of each primary side H bridge circuit can be controlled by taking the angle of the switching tube of the secondary side bridge arm circuit as a reference, so as to control the phase shift angle.
The following description will be made by taking an example in which the input ends of a part of the primary side H-bridge circuits in the micro inverter are connected to a dc power supply and the input ends of a part of the primary side H-bridge circuits are not connected to the dc power supply.
Referring to fig. 4, a control schematic diagram of another micro inverter according to an embodiment of the present application is shown.
In this embodiment, two primary side H-bridge circuits in fig. 1 or fig. 2 are connected to a dc power supply, for example, a first primary side H-bridge circuit is connected to PV1, a second primary side H-bridge circuit is connected to PV2, and neither the third primary side H-bridge circuit nor the fourth primary side H-bridge circuit is connected to a dc power supply.
The primary winding and the primary H-bridge circuit are multiple and correspond to each other one by one; the following at least two primary side H-bridge circuits are connected with a direct current power supply: a first primary H-bridge circuit and a second primary H-bridge circuit;
as can be seen by comparing fig. 3 and fig. 4, the controller is specifically configured to distribute the reactive compensation current i_com according to the first power of the dc power supply connected to the first primary H-bridge circuit and the second power of the dc power supply connected to the second primary H-bridge circuit, so as to obtain a first reactive compensation current i_com1 and a second reactive compensation current i_com2.
It will be appreciated that the distribution of reactive compensation current is based on the power of the respective primary side H-bridge circuit, for example, following the principle of a large power output. For example, if the first power corresponding to the first primary side H-bridge is high, the reactive compensation current output by the first primary side H-bridge can be high. Alternatively, the force may be applied by one of the primary side H-bridge circuits, for example if the first primary side H-bridge circuit is capable of providing all reactive compensation current, or by the first primary side H-bridge circuit and the second primary side H-bridge circuit. The embodiment of the application is not particularly limited to an implementation manner of reactive compensation current distribution among a plurality of primary side H-bridge circuits, and only needs to distribute according to the power.
The controller controls the internal shift angle D11 and the external shift angle D12 corresponding to the first primary side H-bridge circuit according to the first reactive compensation current I_com1, and controls the internal shift angle D21 and the external shift angle D22 corresponding to the second primary side H-bridge circuit according to the second reactive compensation current I_com2.
Specifically, each primary side H-bridge circuit corresponds to a respective feedforward link, and the first passive compensation current i_com1 is fed into the feedforward 1 to calculate, so as to obtain D11 and D12. Similarly, the second reactive compensation current i_com2 is fed into the feedforward 2 for calculation, and D21 and D22 are obtained.
It should be understood that the control of the feedforward link is open loop control, so that the control is more accurate and faster, and the scheme provided by the embodiment of the application also provides a closed loop control link, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 5, a schematic diagram of still another micro inverter according to an embodiment of the present application is shown.
The micro inverter provided by the embodiment compensates the internal shift phase angle and the external shift phase angle according to the difference value of the voltage of the secondary side capacitor and the power grid voltage, and performs closed-loop adjustment.
Specifically, the controller is further configured to obtain a reactive power adjustment current Icom through the regulator according to a voltage difference between the grid voltage and the secondary capacitor, obtain a corresponding internal shift angle adjustment amount and an external shift angle adjustment amount according to the reactive power adjustment current Icom, and correct the internal shift angle and the external shift angle respectively by using the internal shift angle adjustment amount and the external shift angle adjustment amount to obtain a corrected internal shift angle and a corrected external shift angle. And finally, controlling the primary side H bridge arm circuit and the secondary side bridge arm circuit by utilizing the corrected internal shift phase angle and the corrected external shift phase angle.
Specifically, the reactive power regulation current Icom may be implemented by using one or more of a proportional resonance PR regulator, a proportional regulator, an integral regulator, or a compensator, which is not limited in particular, for example, the PR regulator may be used, and the PR regulator may eliminate errors of each subharmonic, so that the phase shift angle result is more accurate.
The following description will proceed with reference to the first primary H-bridge circuit and the second primary H-bridge circuit as examples.
The controller is specifically configured to distribute reactive power adjustment current according to the first power and the second power to obtain a first reactive power adjustment current Icom1 and a second reactive power adjustment current Icom2, calculate a closed loop 1 according to the first reactive power adjustment current Icom1 to obtain an internal phase angle D11 and an external phase angle D12 corresponding to the corrected first primary side H-bridge circuit, and calculate a closed loop 2 according to the second reactive power adjustment current Icom2 to obtain an internal phase angle D21 and an external phase angle D22 corresponding to the corrected second primary side H-bridge circuit.
As shown in fig. 5, specifically, for the first primary H-bridge circuit: and inputting the first passive regulation current Icom1 into the closed loop 1 for calculation to obtain an inner shift angle regulation quantity D_11 and an outer shift angle regulation quantity D_12 of the first primary side H bridge circuit, correcting the D11 by using the inner shift angle regulation quantity D_11 to obtain a corrected inner shift angle D1-1, correcting the D12 by using the outer shift angle regulation quantity D_12 to obtain a corrected outer shift angle D2-1.
As shown in fig. 5, specifically, for the second primary H-bridge circuit: and inputting the second reactive power regulating current Icom2 into the closed loop 2 for calculation to obtain an inner shift angle regulating quantity D_21 and an outer shift angle regulating quantity D_22 of the second primary side H bridge circuit, correcting the D21 by using the inner shift angle regulating quantity D_21 to obtain a corrected inner shift angle D1-2, correcting the D22 by using the outer shift angle regulating quantity D_22, and obtaining a corrected outer shift angle D2-2.
It should be understood that if the primary side H-bridge circuit in the micro-inverter is not connected to a dc power supply, for example, when the micro-inverter is not connected to a photovoltaic panel, since the secondary side winding of the transformer is one or a plurality of secondary side windings are connected in parallel, if the primary side H-bridge circuit which is not connected to the dc power supply does not generate waves during the presynchronization process of the voltage of the secondary side capacitor and the grid voltage, the switching tube of the secondary side bridge arm circuit acts, and the body diode of the primary side switch tube is damaged due to uncontrolled rectification of the primary side capacitor by the body diode of the switching tube of the primary side H-bridge circuit. Therefore, the start-up control of the micro-inverter in the case that one or more primary side H-bridge circuits exist in the micro-inverter and the photovoltaic panel is not connected is described below.
The micro inverter includes two primary side H-bridge circuits, for example, the input ends of the third primary side H-bridge circuit H3 and the fourth primary side H-bridge circuit H4 in fig. 1 and 2 are not connected to a dc power supply.
Referring to fig. 6, a schematic diagram of control of primary capacitor precharge is provided in an embodiment of the present application.
The micro inverter provided in this embodiment, the controller is further configured to obtain, before the voltage of the secondary side capacitor is pre-synchronized with the power grid voltage, a forward charging current i_source from the primary side to the secondary side according to a difference between the voltage of the secondary side capacitor and a preset voltage of the secondary side, and specifically may obtain, by using the PI regulator, the i_source according to a difference between the voltage of the secondary side capacitor and the preset voltage of the secondary side, and control, according to the forward charging current i_source, an internal phase angle and an external phase angle corresponding to the primary side H bridge circuit.
In the following description, the first primary side H-bridge circuit and the second primary side H-bridge circuit are both connected to a dc power supply, and only the primary side H-bridge circuit connected to the dc power supply can charge the secondary side capacitor.
The controller is specifically configured to allocate a forward charging current i_source according to the first power and the second power, obtain a first forward charging current i_source1 and a second forward charging current i_source2, input the i_source1 into a feed-forward 1 link, and calculate the feed-forward 1 link according to the i_source1 to obtain an internal phase angle D111 and an external phase angle D112 corresponding to the first primary H-bridge circuit; and inputting the I_Source2 into a feedforward 2 link, and calculating to obtain an internal shift angle D221 and an external shift angle D222 corresponding to the second primary side H bridge circuit according to the I_Source2 in the feedforward 2 link.
It should be appreciated that the allocation of the forward charging current i_source according to the first power and the second power may be referred to the above allocation principle and specific examples of the reactive compensation current, and will not be described herein.
It should be understood that before the voltage of the secondary capacitor is pre-synchronized with the grid voltage, the primary side needs to be charged for the secondary side, the secondary side needs to be charged for the primary side not connected to the dc power supply, and the pre-synchronization is started after the voltage of the secondary capacitor and the voltage of the primary capacitor are stabilized, that is, the control logic shown in fig. 6 is performed before fig. 3-5.
At least one primary side H bridge circuit is not connected with a direct current power supply; the input end of the primary side H bridge circuit is connected with a primary side capacitor; the controller is also used for obtaining reverse charging current from the secondary side to the primary side according to the difference value between the voltage of the primary side capacitor and the primary side preset voltage after the voltage of the secondary side voltage is charged to the secondary side preset voltage; and controlling the internal shift phase angle of the primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
The secondary side charges the primary side capacitor as described below in connection with fig. 7, and if seen from the primary side to the secondary side, the current is negative, i.e. reverse charged.
Referring to fig. 7, a schematic diagram of precharge control of a primary capacitor of a third primary H-bridge according to an embodiment of the present application is shown.
The micro inverter provided in this embodiment includes at least two primary H-bridge circuits including: a third primary H-bridge circuit and a fourth primary H-bridge circuit;
the controller is specifically configured to obtain a first reverse charging current i_drain3 from the secondary side to the primary side according to a first difference value between a voltage of a primary side capacitor of the third primary side H-bridge circuit and a preset voltage of the primary side; for example, the first difference is input to a PI regulator to obtain i_drain3. And controlling the internal shift phase angle and the external shift phase angle corresponding to the third primary side H bridge circuit according to the first reverse charging current I_drain3, so that the voltage of the primary side capacitor of the third primary side H bridge circuit is charged to the primary side preset voltage.
The primary preset voltage may be Vgmax/2n or more, where Vgmax is a peak value of the grid voltage and n is a turn ratio of the transformer.
Specifically, i_drain3 is input into a feedforward 3 link, and an inner shift angle D311 and an outer shift angle D312 of the third primary side H bridge circuit are obtained through calculation.
Referring to fig. 8, a schematic diagram of precharge control of a primary capacitor of a fourth primary H-bridge according to an embodiment of the present application is shown.
The controller obtains a second reverse charging current I_drain4 from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and the primary side preset voltage, for example, the second difference value is input into the PI regulator to obtain I_drain4; and inputting the I_drain4 into a feedforward 4 link, and calculating the feedforward 4 link to obtain an internal shift angle D321 and an external shift angle D322 corresponding to the fourth primary side H bridge circuit, so that the voltage of the primary side capacitor of the fourth primary side H bridge circuit is charged to the primary side preset voltage.
And after the voltage of the secondary side capacitor and the voltage of the primary side capacitor are stable for a period of time, the power grid presynchronization control is performed.
The micro inverter provided by the embodiment of the application can protect the body diode of the primary side switching tube through charging the primary side capacitor.
Based on the micro inverter provided by the above embodiment, the embodiment of the application also provides a start-up control method of the micro inverter, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 9, the flowchart of a method for controlling the start-up of a micro inverter according to an embodiment of the present application is shown.
The method for controlling the start-up of the micro inverter provided in this embodiment includes: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
the method comprises the following steps:
s901: before the switch is closed, reactive compensation current is obtained according to the power grid voltage and the secondary side capacitance;
s902: and controlling the corresponding internal shift phase angle and external shift phase angle of the primary side H-bridge circuit according to the reactive compensation current, so that the primary side H-bridge circuit outputs reactive current, and the voltage of the secondary side capacitor is presynchronized with the power grid voltage.
Because the secondary side bridge arm circuit is not connected with the power grid before the micro inverter is started, the energy of the secondary side capacitor is required to be provided by the primary side, namely the primary side charges the secondary side. According to the technical scheme, reactive compensation current is obtained according to the power grid voltage and the size of the secondary side capacitor, and then the reactive compensation current corresponding to the output of the primary side H-bridge circuit is controlled to charge the secondary side capacitor, specifically, the controller needs to obtain an internal phase angle and an external phase angle according to the reactive compensation current output as required, and then the primary side H-bridge circuit and the secondary side bridge arm circuit are controlled according to the internal phase angle and the external phase angle, when the voltage of the secondary side capacitor is synchronous with the power grid voltage, the switch is closed, so that overlarge impact on the switch can be avoided, and damage to the switch or the protection of the micro inverter is avoided.
The application provides a micro inverter includes a plurality of primary side H bridge circuit, and direct current power supply is connected to two at least primary side H bridge circuit: a first primary H-bridge circuit and a second primary H-bridge circuit;
the method comprises the steps of controlling an inner shift phase angle and an outer shift phase angle corresponding to a primary side H bridge circuit according to reactive compensation current, and specifically comprising the following steps: the reactive compensation current is distributed according to the first power of the direct current power supply connected with the first primary side H bridge circuit and the second power of the direct current power supply connected with the second primary side H bridge circuit, so that a first reactive compensation current and a second reactive compensation current are obtained; and controlling the internal shift phase angle and the external shift phase angle corresponding to the first primary side H bridge circuit according to the first reactive compensation current, and controlling the internal shift phase angle and the external shift phase angle corresponding to the second primary side H bridge circuit according to the second reactive compensation current.
The method provided by the embodiment further comprises the following steps: obtaining reactive power regulation current through a regulator according to the voltage difference between the power grid voltage and the secondary side capacitor; obtaining corresponding internal phase shift angle adjustment quantity and external phase shift angle adjustment quantity according to reactive power adjustment current; and respectively correcting the inner shift phase angle and the outer shift phase angle by using the inner shift phase angle adjustment quantity and the outer shift phase angle adjustment quantity.
Obtaining corresponding internal phase shift angle adjustment quantity and external phase shift angle adjustment quantity according to reactive power adjustment current; respectively correcting the inner shift angle and the outer shift angle by using the inner shift angle adjustment quantity and the outer shift angle adjustment quantity, and specifically comprises the following steps: distributing reactive power regulating current according to the first power and the second power to obtain a first reactive power regulating current and a second reactive power regulating current; and correcting the internal shift phase angle and the external shift phase angle corresponding to the first primary side H bridge circuit according to the first reactive power regulating current, and correcting the internal shift phase angle and the external shift phase angle corresponding to the second primary side H bridge circuit according to the second reactive power regulating current.
The method provided by the embodiment further comprises the following steps: before the voltage of the secondary side capacitor is presynchronized with the power grid voltage, the forward charging current from the primary side to the secondary side is obtained according to the difference value between the voltage of the secondary side capacitor and the preset voltage of the secondary side; and controlling the inner shift phase angle and the outer shift phase angle corresponding to the primary side H bridge circuit according to the charging current.
Obtaining forward charging current from the primary side to the secondary side according to the difference value between the voltage of the secondary side capacitor and the preset voltage of the secondary side; according to the interior shift angle and the exterior shift angle that the primary side H bridge circuit of charging current control corresponds, specifically include: distributing forward charging current according to the first power and the second power to obtain a first forward charging current and a second forward charging current; controlling an inner shift phase angle and an outer shift phase angle corresponding to the first primary side H bridge circuit according to the first forward charging current; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the second primary side H bridge circuit according to the second forward charging current.
At least one primary side H bridge circuit is not connected with a direct current power supply; the input end of the primary side H bridge circuit is connected with a primary side capacitor;
the method provided by the embodiment further comprises the following steps: after the voltage of the secondary side voltage is charged to the secondary side preset voltage, the reverse charging current from the secondary side to the primary side is obtained according to the difference value between the voltage of the primary side capacitor and the primary side preset voltage;
And controlling the internal shift phase angle of the primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
According to reverse charging current control not connected DC power supply's former side H bridge circuit's internal shift angle, make the voltage of former side electric capacity be charged to former side default voltage, concretely includes: obtaining a first reverse charging current from the secondary side to the primary side according to a first difference value between the voltage of a primary side capacitor of a third primary side H bridge circuit and a primary side preset voltage; controlling the internal shift phase angle of the third primary side H bridge circuit according to the first reverse charging current, so that the voltage of the primary side capacitor of the third primary side H bridge circuit is charged to the primary side preset voltage; obtaining a second reverse charging current from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and a preset primary side voltage; and controlling the internal shift phase angle of the fourth primary side H-bridge circuit according to the second reverse charging current, so that the voltage of the primary side capacitor of the fourth primary side H-bridge circuit is charged to the primary side preset voltage.
And after the voltage of the secondary side capacitor and the voltage of the primary side capacitor are stable for a period of time, the power grid presynchronization control is performed. The micro inverter provided by the embodiment of the application can protect the body diode of the primary side switching tube through charging the primary side capacitor.
It should be noted that, in the present description, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different manner from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (19)

1. A micro-inverter, comprising: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
The output end of the primary side H-bridge circuit is connected with the corresponding primary side winding; the secondary side bridge arm circuit is connected with a secondary side winding; the output end of the secondary side bridge arm circuit is connected with a load or a power grid through a switch; the secondary side bridge arm circuit comprises a secondary side capacitor;
and the controller is used for obtaining reactive compensation current according to the power grid voltage and the secondary side capacitor before the switch is closed, and controlling an internal shift phase angle and an external shift phase angle corresponding to the primary side H-bridge circuit according to the reactive compensation current so that the primary side H-bridge circuit outputs reactive current and the voltage of the secondary side capacitor is presynchronized with the power grid voltage.
2. The micro-inverter of claim 1, wherein the primary winding and the primary H-bridge circuit are each plural and in one-to-one correspondence; at least two of the following primary side H-bridge circuits are connected with a direct current power supply: a first primary H-bridge circuit and a second primary H-bridge circuit;
the controller is specifically configured to distribute the reactive compensation current according to a first power of the dc power supply connected to the first primary H-bridge circuit and a second power of the dc power supply connected to the second primary H-bridge circuit, obtain a first reactive compensation current and a second reactive compensation current, control an internal phase angle and an external phase angle corresponding to the first primary H-bridge circuit according to the first reactive compensation current, and control an internal phase angle and an external phase angle corresponding to the second primary H-bridge circuit according to the second reactive compensation current.
3. The micro-inverter of claim 2, wherein the controller is further configured to obtain a reactive power regulation current through a regulator according to a voltage difference between a grid voltage and the secondary capacitor, obtain a corresponding internal phase angle regulation amount and an external phase angle regulation amount according to the reactive power regulation current, and correct the internal phase angle and the external phase angle by using the internal phase angle regulation amount and the external phase angle regulation amount, respectively.
4. The micro-inverter of claim 3, wherein the controller is specifically configured to distribute the reactive power adjustment current according to the first power and the second power to obtain a first reactive power adjustment current and a second reactive power adjustment current, correct an inner shift angle and an outer shift angle corresponding to the first primary H-bridge circuit according to the first reactive power adjustment current, and correct an inner shift angle and an outer shift angle corresponding to the second primary H-bridge circuit according to the second reactive power adjustment current.
5. The micro-inverter according to any one of claims 2-4, wherein the controller is further configured to obtain a forward charging current from a primary side to a secondary side according to a difference between the voltage of the secondary side capacitor and a preset secondary side voltage before the voltage of the secondary side capacitor is pre-synchronized with the grid voltage, and control an inner shift phase angle and an outer shift phase angle corresponding to the primary side H-bridge circuit according to the forward charging current.
6. The micro-inverter of claim 5, wherein the controller is specifically configured to distribute the forward charging current according to the first power and the second power to obtain a first forward charging current and a second forward charging current, and control an inner shift phase angle and an outer shift phase angle corresponding to the first primary H-bridge circuit according to the first forward charging current; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the second primary side H-bridge circuit according to the second forward charging current.
7. The micro-inverter of claim 6, wherein at least one of the primary side H-bridge circuits is disconnected from a dc power source; the input end of the primary side H bridge circuit is connected with a primary side capacitor;
the controller is further configured to obtain a reverse charging current from the secondary side to the primary side according to a difference value between the voltage of the primary side capacitor and the primary side preset voltage after the voltage of the secondary side voltage is charged to the secondary side preset voltage; and controlling the internal phase angle of a primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
8. The micro-inverter of claim 7, wherein the primary H-bridge circuit comprises at least two primary H-bridge circuits that are not connected to a dc power supply: a third primary H-bridge circuit and a fourth primary H-bridge circuit;
The controller is specifically configured to obtain a first reverse charging current from the secondary side to the primary side according to a first difference value between a voltage of a primary side capacitor of the third primary side H-bridge circuit and a primary side preset voltage; controlling an inward shift phase angle and an outward shift phase angle corresponding to the third primary side H-bridge circuit according to the first reverse charging current, so that the voltage of a primary side capacitor of the third primary side H-bridge circuit is charged to the primary side preset voltage; obtaining a second reverse charging current from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and a preset primary side voltage; and controlling an internal shift phase angle and an external shift phase angle corresponding to the fourth primary side H-bridge circuit according to the second reverse charging current, so that the voltage of the primary side capacitor of the fourth primary side H-bridge circuit is charged to the primary side preset voltage.
9. The micro-inverter according to any one of claims 1-8, wherein the plurality of transformers each comprise a primary winding and a secondary winding, the primary windings and the primary H-bridge circuit being in one-to-one correspondence; and two ends of the secondary winding of all the transformers are connected in parallel and connected with the input end of the secondary bridge arm circuit.
10. The micro-inverter of any one of claims 1-8, wherein the transformer is one, the transformer comprising a plurality of primary windings and a secondary winding, the primary H-bridge circuit and the primary windings being in one-to-one correspondence.
11. The micro-inverter of any one of claims 1-10, wherein the dc power source is a photovoltaic panel.
12. The start-up control method of the micro inverter is characterized in that the micro inverter comprises the following steps: the secondary side bridge arm circuit is connected with the primary side H-bridge circuit; the transformer comprises a primary winding and a secondary winding;
the method comprises the following steps:
before the switch is closed, reactive compensation current is obtained according to the grid voltage and the secondary side capacitor;
and controlling an inward shift phase angle and an outward shift phase angle corresponding to the primary side H-bridge circuit according to the reactive compensation current, so that the primary side H-bridge circuit outputs reactive current, and the voltage of the secondary side capacitor is presynchronized with the power grid voltage.
13. The method of claim 12, wherein at least two of the primary side H-bridge circuits are connected to a dc power supply: a first primary H-bridge circuit and a second primary H-bridge circuit;
The method for controlling the internal shift phase angle and the external shift phase angle corresponding to the primary side H-bridge circuit according to the reactive compensation current specifically comprises the following steps:
distributing the reactive compensation current according to the first power of the direct current power supply connected with the first primary side H bridge circuit and the second power of the direct current power supply connected with the second primary side H bridge circuit to obtain a first reactive compensation current and a second reactive compensation current;
and controlling the inner shift phase angle and the outer shift phase angle corresponding to the first primary side H-bridge circuit according to the first reactive compensation current, and controlling the inner shift phase angle and the outer shift phase angle corresponding to the second primary side H-bridge circuit according to the second reactive compensation current.
14. The method as recited in claim 13, further comprising:
obtaining reactive power regulation current through a regulator according to the voltage difference between the power grid voltage and the secondary side capacitor;
obtaining corresponding internal phase shift angle adjustment quantity and external phase shift angle adjustment quantity according to the reactive power adjustment current;
and respectively correcting the inner shift phase angle and the outer shift phase angle by using the inner shift phase angle adjustment quantity and the outer shift phase angle adjustment quantity.
15. The method of claim 14, wherein the obtaining corresponding delta phase angle adjustments and delta phase angle adjustments from the reactive regulation current; and respectively correcting the inner shift phase angle and the outer shift phase angle by using the inner shift phase angle adjustment quantity and the outer shift phase angle adjustment quantity, and specifically comprises the following steps:
Distributing the reactive power regulating current according to the first power and the second power to obtain a first reactive power regulating current and a second reactive power regulating current;
and correcting the inner shift phase angle and the outer shift phase angle corresponding to the first primary side H-bridge circuit according to the first reactive power regulating current, and correcting the inner shift phase angle and the outer shift phase angle corresponding to the second primary side H-bridge circuit according to the second reactive power regulating current.
16. The method according to claims 13-15, further comprising:
before the voltage of the secondary side capacitor is presynchronized with the power grid voltage, the forward charging current from the primary side to the secondary side is obtained according to the difference value between the voltage of the secondary side capacitor and the preset secondary side voltage;
and controlling an inner shift phase angle and an outer shift phase angle corresponding to the primary side H bridge circuit according to the forward charging current.
17. The method of claim 16, wherein the forward charging current from the primary side to the secondary side is obtained from a difference between the voltage of the secondary side capacitor and a secondary side preset voltage; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the primary side H bridge circuit according to the charging current, wherein the method specifically comprises the following steps of:
distributing the forward charging current according to the first power and the second power to obtain a first forward charging current and a second forward charging current;
Controlling an inner shift phase angle and an outer shift phase angle corresponding to the first primary side H-bridge circuit according to the first forward charging current; and controlling an inner shift phase angle and an outer shift phase angle corresponding to the second primary side H-bridge circuit according to the second forward charging current.
18. The method of claim 17, wherein at least one of the primary side H-bridge circuits is disconnected from a dc power source; the input end of the primary side H bridge circuit is connected with a primary side capacitor;
further comprises:
after the voltage of the secondary side voltage is charged to the secondary side preset voltage, obtaining the reverse charging current from the secondary side to the primary side according to the difference value between the voltage of the primary side capacitor and the primary side preset voltage;
and controlling the internal phase angle of a primary side H bridge circuit which is not connected with the direct current power supply according to the reverse charging current, so that the voltage of the primary side capacitor is charged to the primary side preset voltage.
19. The method according to claim 18, wherein controlling the phase shift angle of the primary H-bridge circuit, which is not connected to the dc power supply, according to the reverse charging current, causes the voltage of the primary capacitor to be charged to the primary preset voltage, specifically comprises:
obtaining a first reverse charging current from the secondary side to the primary side according to a first difference value between the voltage of a primary side capacitor of a third primary side H bridge circuit and a primary side preset voltage; controlling the internal shift phase angle of the third primary side H bridge circuit according to the first reverse charging current, so that the voltage of the primary side capacitor of the third primary side H bridge circuit is charged to the primary side preset voltage;
Obtaining a second reverse charging current from the secondary side to the primary side according to a second difference value between the voltage of the primary side capacitor of the fourth primary side H bridge circuit and a preset primary side voltage; and controlling the internal shift phase angle of the fourth primary side H-bridge circuit according to the second reverse charging current, so that the voltage of the primary side capacitor of the fourth primary side H-bridge circuit is charged to the primary side preset voltage.
CN202310239157.9A 2023-03-08 2023-03-08 Micro inverter and start-up control method Pending CN116247957A (en)

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CN202310239157.9A CN116247957A (en) 2023-03-08 2023-03-08 Micro inverter and start-up control method

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CN116914773A (en) * 2023-09-13 2023-10-20 锦浪科技股份有限公司 Reactive power control method for micro inverter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116914773A (en) * 2023-09-13 2023-10-20 锦浪科技股份有限公司 Reactive power control method for micro inverter
CN116914773B (en) * 2023-09-13 2023-12-08 锦浪科技股份有限公司 Reactive power control method for micro inverter

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