A micro-inverter circuit based on active disturbance rejection control

Abstract

The present invention discloses a micro-inverter circuit based on active disturbance rejection control, which is characterized by comprising at least two photovoltaic modules, boost modules corresponding to the number of photovoltaic modules, a DC-AC conversion module, a first active disturbance rejection control module and a second active disturbance rejection control module. The boost modules are connected in series with each other to form a series-connected boost module group. The positive output terminal of the first boost module in the boost module group is connected to the positive input terminal of the DC-AC conversion module, and the negative output terminal of the last boost module in the boost module group is connected to the negative input terminal of the DC-AC conversion module. The first output terminal and the second output terminal of the DC-AC conversion module are connected in parallel with an external power grid. The advantages are that at least two boost modules of the micro-inverter are first connected in series and then incorporated into the subsequent DC-AC conversion module, and the turns ratio of the high-frequency transformer is relatively low; the DC-AC conversion module operates with double-phase-shift control, resulting in less switching process loss and fast response.

Description

Technical Field

[0001] The present invention relates to the technical field of inverters, and in particular to a micro-inverter circuit based on active disturbance rejection control. Background Art

[0002] With the rapid development of society, people's demand for electricity is gradually increasing, which makes the solar photovoltaic power generation technology enter a rapid development stage under this situation. Photovoltaic grid-connected power generation has become the main way for people to utilize solar energy. With the rapid development of balcony solar photovoltaic systems, the demand for micro-inverters is increasing day by day.

[0003] The photovoltaic micro-inverter that can connect multiple photovoltaic cell modules at the same time can ensure that each photovoltaic module independently realizes the maximum power point tracking function, and then converts the energy of all photovoltaic cell modules into alternating current through an inverter and accesses the power grid. Compared with the micro-inverter that can only connect a single photovoltaic cell module, it has the advantages of higher conversion efficiency, lower cost, smaller volume, and larger power density. The commonly used micro-inverters currently use PID control. During the operation of the control system, due to problems such as environmental changes, grid fluctuations, and model parameter uncertainties, the disturbance during the grid connection process is also relatively large. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a micro-inverter circuit based on active disturbance rejection control that can reduce the loss of the inverter during the grid connection switching process, improve the anti-interference ability and rapidity.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: A micro-inverter circuit based on active disturbance rejection control includes at least two photovoltaic modules, boost modules corresponding in number to the photovoltaic modules, a DC-AC conversion module, a first active disturbance rejection control module, and a second active disturbance rejection control module. The positive input terminal of each boost module is connected to the positive output terminal of a corresponding one of the photovoltaic modules, and the negative input terminal of each boost module is connected to the negative output terminal of a corresponding one of the photovoltaic modules. The boost modules are connected in series with each other to form a series-connected boost module group. The positive output terminal of the first boost module in the boost module group is connected to the positive input terminal of the DC-AC conversion module, and the negative output terminal of the last boost module in the boost module group is connected to the negative input terminal of the DC-AC conversion module. The first output terminal and the second output terminal of the DC-AC conversion module are connected in parallel with an external power grid. The first active disturbance rejection control module is configured to collect the voltage at the output terminal of each boost module, compare it with a set reference voltage to generate a switching control signal, and send the switching control signal to the control signal receiving terminal of the boost module. The boost module generates direct current according to the switching control signal. The second active disturbance rejection control module is configured to obtain the input voltage, input current, output voltage, and output current of the DC-AC conversion module, obtain the internal phase shift angle and the external phase shift angle of the DC-AC conversion module through an active disturbance rejection control algorithm, and then control the DC-AC conversion module to convert the direct current input by the boost module group into industrial frequency alternating current according to the internal phase shift angle and the external phase shift angle.

[0006] The first active disturbance rejection control module includes a first voltage acquisition module, a first-order linear active disturbance rejection controller, and a PWM generator. The boost module includes a first inductor, a first fully-controlled switch, a first diode, and a first capacitor. One end of the first inductor is connected to the positive output terminal of the photovoltaic module. The other end of the first inductor, the drain of the first fully-controlled switch, and the positive electrode of the first diode are connected. The negative electrode of the first diode is connected to one end of the first capacitor and serves as the positive output terminal of the boost module. The negative output terminal of the photovoltaic module, the source of the first fully-controlled switch, and the other end of the first capacitor are connected and serve as the negative output terminal of the boost module. The negative output terminal of the previous adjacent boost module is connected to the positive output terminal of the next boost module. The first voltage acquisition module is used to collect the voltage between the positive and negative output terminals of the boost module and send it to the first-order linear active disturbance rejection controller. The first-order linear active disturbance rejection controller obtains the duty cycle control quantity through the active disturbance rejection control algorithm based on the received voltage and sends it to the PWM generator. The PWM generator sends the corresponding switch control signal to the control terminal of the first fully-controlled switch according to the received duty cycle control quantity.

[0007] The DC-AC conversion module includes an H-bridge module, a resonant module, a high-frequency transformer, a cycloconverter, and a filter. The positive input terminal of the H-bridge module is connected to the positive output terminal of the first boost module in the boost module group. The negative input terminal of the H-bridge module is connected to the negative output terminal of the last boost module in the boost module group. The first output terminal of the H-bridge module is connected to the input terminal of the resonant module. The output terminal of the resonant module is connected to one end of the primary side of the high-frequency transformer. The second output terminal of the H-bridge module is connected to the other end of the primary side of the high-frequency transformer. One end of the secondary side of the high-frequency transformer is connected to the first input terminal of the cycloconverter. The other end of the secondary side of the high-frequency transformer is connected to the second input terminal of the cycloconverter. The first output terminal of the cycloconverter is connected to the first input terminal of the filter. The second output terminal of the cycloconverter is connected to the second input terminal of the filter. The first output terminal and the second output terminal of the filter are respectively connected in parallel to both ends of the external power grid. Among them, the filter can be common filter structures such as an L filter, an LC filter, an LCL filter, an EMI filter, etc., and the resonant module can be common resonant circuit structures such as LLC, LC, etc.

[0008] The second active disturbance rejection control module includes a second voltage acquisition module, a third voltage acquisition module, a fourth voltage acquisition module, a first current acquisition module, a second current acquisition module, a first phase-shift angle calculation module, a second phase-shift angle calculation module, a first drive signal generation module, and a second drive signal generation module. The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module and send it to the first phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module and send it to the first phase-shift angle calculation module. The fourth voltage acquisition module is used to acquire the grid-side voltage output to the external power grid and send it to the first phase-shift angle calculation module. The first phase-shift angle calculation module obtains the phase-shift angle θ between the first output terminal and the second output terminal of the H-bridge module through an active disturbance rejection control algorithm and sends it to the first drive signal generation module. The first drive signal generation module controls the operation of the H-bridge module according to the phase-shift angle θ;

[0009] The first current acquisition module is used to acquire the primary input current at the positive input terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The second current acquisition module is used to acquire the grid-side current output from the filter to the external power grid and send it to the second phase-shift angle calculation module. The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The second phase-shift angle calculation module obtains the phase-shift angle between the first output terminal of the H-bridge module and the first input terminal of the cycloconverter through an active disturbance rejection control algorithm and sends it to the second drive signal generation module. The second drive signal generation module controls the operation of the cycloconverter according to the phase-shift angle

[0010] The first phase-shift angle calculation module includes a first active disturbance rejection controller with a first tracking differentiator and a first extended state observer. The second voltage acquisition module is used to acquire the voltage between the first input terminal and the second input terminal of the H-bridge module and send it to the first tracking differentiator as a reference voltage. The fourth voltage acquisition module is used to acquire the grid-side voltage V out output from the filter to the external power grid. The first active disturbance rejection controller uses the grid-side voltage V out ​The product of the peak value and the reciprocal of the turns ratio of the high-frequency transformer is used as the voltage controlled quantity and input into the first extended state observer. The first auto-disturbance rejection controller obtains the phase-shifting angle θ through the internal auto-disturbance rejection control algorithm. The expression of the phase-shifting angle θ is: Where, V fb is the voltage between the first output terminal and the second output terminal of the H-bridge module, and V DC is the voltage between the positive input terminal and the negative input terminal of the H-bridge module, and ω s is the switching angular frequency of the fully controlled switch tubes included in the H-bridge module;

[0011] The second phase-shifting angle calculation module includes a second auto-disturbance rejection controller with a second tracking differentiator and a second extended state observer. The first current acquisition module is used to acquire the primary input current I DC at the positive input terminal of the H-bridge module. The second auto-disturbance rejection controller uses the product of the primary input current I DC and the reciprocal of the turns ratio of the high-frequency transformer as the current controlled quantity and inputs it into the second tracking differentiator. The second current acquisition module is used to acquire the grid-side current i o output from the filter to the external power grid. The second auto-disturbance rejection controller uses the peak value of the grid-side current i o as the reference current and inputs it into the second extended state observer. The second auto-disturbance rejection controller obtains the phase-shifting angle The expression of the phase-shifting angle is: Where, P avg(pu) is the per-unit value, M is the instantaneous voltage gain of the high-frequency inverter, n is the turns ratio of the high-frequency transformer, and X r is the equivalent impedance, f is the switching frequency of the fully controlled switch tubes in the cycloconverter, Q is the quality factor, L is the inductance value of the filter, C’ represents the equivalent capacitance value common to the cycloconverter and the filter, and R x is the equivalent resistance common to the cycloconverter and the filter.

[0012] The described H-bridge module includes a second capacitor, a second fully-controlled switch, a third fully-controlled switch, a fourth fully-controlled switch, and a fifth fully-controlled switch. One end of the second capacitor, the drain of the second fully-controlled switch, and the drain of the fourth fully-controlled switch are connected and serve as the first input terminal of the H-bridge module. The source of the second fully-controlled switch is connected to the drain of the third fully-controlled switch and serves as the first output terminal of the H-bridge module. The other end of the second capacitor, the source of the third fully-controlled switch, and the source of the fifth fully-controlled switch are connected and serve as the second input terminal of the H-bridge module. The source of the fourth fully-controlled switch is connected to the drain of the fifth fully-controlled switch and serves as the second output terminal of the H-bridge module. The pulse signal levels received by the second fully-controlled switch and the third fully-controlled switch are opposite, and the pulse signal levels received by the fourth fully-controlled switch and the fifth fully-controlled switch are opposite.

[0013] The described cycloconverter includes a sixth fully-controlled switch, a seventh fully-controlled switch, an eighth fully-controlled switch, and a ninth fully-controlled switch. The source of the sixth fully-controlled switch is connected to the source of the seventh fully-controlled switch and serves as the first input terminal of the cycloconverter. The drain of the sixth fully-controlled switch serves as the first output terminal of the cycloconverter. The drain of the seventh fully-controlled switch is connected to the drain of the eighth fully-controlled switch. The source of the eighth fully-controlled switch is connected to the source of the ninth fully-controlled switch and serves as the second input terminal of the cycloconverter. The drain of the ninth fully-controlled switch serves as the second output terminal of the cycloconverter. The pulse signal levels received by the sixth fully-controlled switch and the seventh fully-controlled switch are opposite, and the pulse signal levels received by the eighth fully-controlled switch and the ninth fully-controlled switch are opposite.

[0014] Compared with the prior art, the advantages of the present invention are as follows: the voltage of the photovoltaic module is boosted by the boost module, and a stable DC voltage is obtained through the control of the boost module by the first active disturbance rejection control module. The H-bridge module of the DC-AC conversion module converts the direct current into high-frequency alternating current, then the high-frequency alternating current is stepped down by the high-frequency transformer, and then the high-frequency electricity is converted into industrial-frequency electricity and incorporated into the external power grid through the cycloconverter. At least two boost modules of the micro-inverter are first connected in series and then incorporated into the subsequent DC-AC conversion module. The voltage after series connection is higher, so that the turns ratio of the high-frequency transformer in the subsequent DC-AC conversion module for boosting is lower, and the circuit design is friendly, and higher efficiency can be achieved; the DC-AC conversion module operates with double-phase-shift control, which can achieve zero-voltage turn-on, reduce the switching process loss of the inverter, and also has a faster response speed;

[0015] The first active disturbance rejection controller and the second active disturbance rejection controller used in the DC-AC conversion module are of existing conventional structures. By obtaining the internal and external phase-shifting angles through the first active disturbance rejection controller and the second active disturbance rejection controller, the control of the H-bridge module and the cycloconverter in the DC-AC conversion module is realized, which better solves the problem of large turns ratio of the high-frequency transformer and the inherent contradiction between the overshoot and rapidity of the controller. The seamless switching of the grid-connected system can be more stable, and the power supply quality and efficiency are also improved. The active disturbance rejection control based on the extended state observer is a non-linear robust control technology and a method to reduce the overall error based on the process error, and has extremely strong anti-interference ability and control quality for non-linear disturbances. Brief Description of the Drawings

[0016] Figure 1 It is the system structure block diagram of the present invention;

[0017] Figure 2 It is the overall circuit structure diagram of the present invention. Detailed Embodiment

[0018] The present invention will be further described in detail below in conjunction with the embodiments of the drawings.

[0019] Embodiment 1: A micro-inverter circuit based on active disturbance rejection control includes two photovoltaic modules PVn, boost modules 1 corresponding in number to the photovoltaic modules PVn, a DC-AC conversion module 2, a first active disturbance rejection control module 3, and a second active disturbance rejection control module 4. The positive input terminal of each boost module 1 is connected to the positive output terminal of a corresponding photovoltaic module PVn, and the negative input terminal of each boost module 1 is connected to the negative output terminal of a corresponding photovoltaic module PVn. The boost modules 1 are connected in series with each other to form a series-connected group of boost modules 1. The positive output terminal of the first boost module 1 in the group of boost modules 1 is connected to the positive input terminal of the DC-AC conversion module 2, and the negative output terminal of the last boost module 1 in the group of boost modules 1 is connected to the negative input terminal of the DC-AC conversion module 2. The first output terminal and the second output terminal of the DC-AC conversion module 2 are connected in parallel with an external power grid 5. The first active disturbance rejection control module 3 is configured to collect the voltage at the output terminal of each boost module 1, compare it with a set reference voltage to generate a switching control signal, and send the switching control signal to the control signal receiving terminal of the boost module 1. The boost module 1 generates direct current according to the switching control signal. The second active disturbance rejection control module 4 is configured to obtain the input voltage, input current, output voltage, and output current of the DC-AC conversion module 2, obtain the internal phase shift angle and external phase shift angle of the DC-AC conversion module 2 through the active disturbance rejection control algorithm, and then control the DC-AC conversion module 2 to convert the direct current input from the group of boost modules 1 into industrial frequency alternating current according to the internal phase shift angle and external phase shift angle. The first active disturbance rejection control module 3 includes a first voltage acquisition module (not shown in the figure), a first-order linear active disturbance rejection controller U1, and a PWM generator P1. The boost module 1 includes a first inductor L1, a first fully controlled switch tube S1, a first diode D1, and a first capacitor C1. One end of the first inductor L1 is connected to the positive output terminal of the photovoltaic module PVn, and the other end of the first inductor L1, the drain of the first fully controlled switch tube S1, and the positive electrode of the first diode D1 are connected. The negative electrode of the first diode D1 is connected to one end of the first capacitor C1 and serves as the positive output terminal of the boost module 1. The negative output terminal of the photovoltaic module PVn, the source of the first fully controlled switch tube S1, and the other end of the first capacitor C1 are connected and serve as the negative output terminal of the boost module 1. The negative output terminal of the previous adjacent boost module 1 is connected to the positive output terminal of the next boost module 1. The first voltage acquisition module is configured to collect the voltage between the positive output terminal and the negative output terminal of the boost module 1 and send it to the first-order linear active disturbance rejection controller U1. The first-order linear active disturbance rejection controller U1 obtains a duty cycle control amount through the active disturbance rejection control algorithm according to the received voltage and sends it to the PWM generator P1. The PWM generator P1 sends a corresponding switching control signal to the control terminal of the first fully controlled switch tube S1 according to the received duty cycle control amount;

[0020] The DC-AC conversion module 2 includes an H-bridge module U2, a resonance module U3, a high-frequency transformer U4, a cycloconverter U5, and a filter U6. The resonance module U3 is an LC resonance circuit structure. The positive input terminal of the H-bridge module U2 is connected to the positive output terminal of the first boost module 1 in the boost module group 1, and the negative input terminal of the H-bridge module U2 is connected to the negative output terminal of the last boost module 1 in the boost module group 1. The first output terminal of the H-bridge module U2 is connected to the input terminal of the resonance module U3, the output terminal of the resonance module U3 is connected to one end of the primary side of the high-frequency transformer U4, the second output terminal of the H-bridge module U2 is connected to the other end of the primary side of the high-frequency transformer U4, one end of the secondary side of the high-frequency transformer U4 is connected to the first input terminal of the cycloconverter U5, the other end of the secondary side of the high-frequency transformer U4 is connected to the second input terminal of the cycloconverter U5, the first output terminal of the cycloconverter U5 is connected to the first input terminal of the filter U6, the second output terminal of the cycloconverter U5 is connected to the second output terminal of the filter U6, and the first output terminal and the second output terminal of the filter U6 are respectively connected in parallel to both ends of the external power grid 5. Among them, the filter U6 can be a common filter structure such as an L filter, an LC filter, an LCL filter, an EMI filter, etc. The resonance module U3 can also be an LLC resonance circuit, and the resonance module U3 can also be located on the secondary side of the high-frequency transformer U4;

[0021] The second active disturbance rejection control module 4 includes a second voltage acquisition module (not shown in the figure), a third voltage acquisition module (not shown in the figure), a fourth voltage acquisition module (not shown in the figure), a first current acquisition module (not shown in the figure), a second current acquisition module (not shown in the figure), a first phase-shift angle calculation module, a second phase-shift angle calculation module, a first drive signal generation module (not shown in the figure), and a second drive signal generation module (not shown in the figure). The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module U2 and send it to the first phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module U2 and send it to the first phase-shift angle calculation module. The fourth voltage acquisition module is used to acquire the grid-side voltage output to the external power grid 5 and send it to the first phase-shift angle calculation module. The first phase-shift angle calculation module obtains the phase-shift angle θ between the first output terminal and the second output terminal of the H-bridge module U2 through the active disturbance rejection control algorithm and sends it to the first drive signal generation module. The first drive signal generation module controls the operation of the H-bridge module U2 according to the phase-shift angle θ. The first current acquisition module is used to acquire the primary input current at the positive input terminal of the H-bridge module U2 and send it to the second phase-shift angle calculation module. The second current acquisition module is used to acquire the grid-side current output from the filter U6 to the external power grid 5 and send it to the second phase-shift angle calculation module. The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module U2 and send it to the second phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module U2 and send it to the second phase-shift angle calculation module. The second phase-shift angle calculation module obtains the phase-shift angle between the first output terminal of the H-bridge module U2 and the first input terminal of the circulating converter U5 through the active disturbance rejection control algorithm and sends it to the second drive signal generation module. The second drive signal generation module controls the operation of the circulating converter U5 according to the phase-shift angle ;

[0022] The first phase-shift angle calculation module includes a first active disturbance rejection controller U7 with a first tracking differentiator TD1 and a first extended state observer ESO1. The second voltage acquisition module is used to acquire the voltage between the first input terminal and the second input terminal of the H-bridge module U2 and send it to the first tracking differentiator TD1 as the reference voltage. The fourth voltage acquisition module is used to acquire the grid-side voltage V out output from the filter U6 to the external power grid 5. The first active disturbance rejection controller U7 takes the product of the peak value of the grid-side voltage V out and the reciprocal of the turns ratio of the high-frequency transformer U4 as the voltage controlled quantity and inputs it into the first extended state observer ESO1. The first active disturbance rejection controller U7 obtains the phase-shift angle θ through the internal active disturbance rejection control algorithm. The expression of the phase-shift angle θ is: where V fbis the voltage between the first output terminal and the second output terminal of the H-bridge module U2, V DC is the voltage between the positive input and negative input of the H-bridge module U2, ω s is the switching angular frequency of the fully controlled switch tube included in the H-bridge module U2;

[0023] The second phase-shift angle calculation module includes a second active disturbance rejection controller U8 with a second tracking differentiator TD2 and a second extended state observer ESO2. The first current acquisition module is used to acquire the primary input current I at the positive input end of the H-bridge module U2. DC The second anti-disturbance controller U8 converts the primary input current I DC The product of the inverse of the transformation ratio of the high-frequency transformer U4 is used as the current controlled variable and input into the second tracking differentiator TD2. The second current acquisition module is used to collect the grid-side current i output by the filter U6 to the external grid 5. o The second anti-disturbance controller U8 converts the grid-side current i o The peak value is used as the reference current and input into the second extended state observer ESO2. The second active disturbance rejection controller U8 obtains the phase shift angle through the internal active disturbance rejection control algorithm. Phase shift angle The expression is: Among them, P avg(pu) is the per unit value, M is the instantaneous voltage gain of the high-frequency inverter, n is the transformation ratio of high frequency transformer U4, X r is the equivalent impedance, f is the switching frequency of the fully controlled switch in the cycloconverter U5, Q is the quality factor, L is the inductance of the filter U6, C' represents the equivalent capacitance of the cycloconverter U5 and the filter U6, R x It is the equivalent resistance of the cycloconverter U5 and the filter U6. The first anti-disturbance control unit U7 and the second anti-disturbance control unit U8 used in the DC-AC conversion module 2 are conventional structures. The first anti-disturbance control unit U7 and the second anti-disturbance control unit U8 obtain the internal and external phase shift angles to control the H-bridge module U2 and the cycloconverter U5 in the DC-AC conversion module 2, so as to realize the conversion of direct current into high-frequency alternating current through the H-bridge module U2 as a whole, and then the high-frequency alternating current is stepped down through the high-frequency transformer U4, and then the high-frequency electricity is converted into industrial frequency electricity through the cycloconverter U5 and incorporated into the external power grid 5.

[0024] The H-bridge module U2 includes a second capacitor C buf , a second fully-controlled switch tube S2, a third fully-controlled switch tube S3, a fourth fully-controlled switch tube S4 and a fifth fully-controlled switch tube S5, a second capacitor C bufOne end, the drain of the second fully controlled switch tube S2, and the drain of the fourth fully controlled switch tube S4 are connected and used as the first input terminal of the H-bridge module U2. The source of the second fully controlled switch tube S2 is connected to the drain of the third fully controlled switch tube S3 and used as the first output terminal of the H-bridge module U2. The other end of the second capacitor C buf The other end, the source of the third fully controlled switch tube S3, and the source of the fifth fully controlled switch tube S5 are connected and used as the second input terminal of the H-bridge module U2. The source of the fourth fully controlled switch tube S4 is connected to the drain of the fifth fully controlled switch tube S5 and used as the second output terminal of the H-bridge module U2. The pulse signal levels received by the second fully controlled switch tube S2 and the third fully controlled switch tube S3 are opposite. The pulse signal levels received by the fourth fully controlled switch tube S4 and the fifth fully controlled switch tube S5 are opposite;

[0025] The cycloconverter U5 includes a sixth fully controlled switch tube S6, a seventh fully controlled switch tube S7, an eighth fully controlled switch tube S8, and a ninth fully controlled switch tube S9. The source of the sixth fully controlled switch tube S6 is connected to the source of the seventh fully controlled switch tube S7 and used as the first input terminal of the cycloconverter U5. The drain of the sixth fully controlled switch tube S6 is used as the first output terminal of the cycloconverter U5. The drain of the seventh fully controlled switch tube S7 is connected to the drain of the eighth fully controlled switch tube S8. The source of the eighth fully controlled switch tube S8 is connected to the source of the ninth fully controlled switch tube S9 and used as the second input terminal of the cycloconverter U5. The drain of the ninth fully controlled switch tube S9 is used as the second output terminal of the cycloconverter U5. The pulse signal levels received by the sixth fully controlled switch tube S6 and the seventh fully controlled switch tube S7 are opposite. The pulse signal levels received by the eighth fully controlled switch tube S8 and the ninth fully controlled switch tube S9 are opposite.

[0026] In the above embodiments, the conduction sequence of each fully controlled switch tube of the cycloconverter U5 is as follows:

[0027] When the grid voltage > 0 and the resonant module current > 0, the sixth fully controlled switch tube S6 and the ninth fully controlled switch tube S9 are turned on, and the seventh fully controlled switch tube S7 and the eighth fully controlled switch tube S8 are turned off;

[0028] When the grid voltage > 0 and the resonant module current < 0, the seventh fully controlled switch tube S7 and the eighth fully controlled switch tube S8 are turned on, and the sixth fully controlled switch tube S6 and the ninth fully controlled switch tube S9 are turned off;

[0029] When the grid voltage < 0 and the resonant module current < 0, the sixth fully controlled switch tube S6 and the ninth fully controlled switch tube S9 are turned on, and the seventh fully controlled switch tube S7 and the eighth fully controlled switch tube S8 are turned off;

[0030] When the grid voltage < 0 and the resonant module current > 0, the seventh fully controlled switch tube S7 and the eighth fully controlled switch tube S8 are turned on, and the sixth fully controlled switch tube S6 and the ninth fully controlled switch tube S9 are turned off.

[0031] Embodiment 2: The rest is the same as Embodiment 1, except that the number of photovoltaic modules PVn is three, and the number of boost modules 1 is three.

[0032] Embodiment 3: The rest is the same as Embodiment 1, except that the number of photovoltaic modules PVn is six, and the number of boost modules 1 is six. The six boost modules are first connected in series and then incorporated into the subsequent DC-AC conversion module. The voltage after series connection is higher, so that the turns ratio of the high-frequency transformer in the subsequent DC-AC conversion module for boosting is lower. The circuit design is user-friendly and can achieve higher efficiency.

Claims

1. A micro-inverter circuit based on active disturbance rejection control, characterized in that It includes at least two photovoltaic modules, boost modules corresponding in number to the photovoltaic modules, a DC-AC conversion module, a first active disturbance rejection control module, and a second active disturbance rejection control module. The positive input terminal of each boost module is connected to the positive output terminal of a corresponding photovoltaic module, and the negative input terminal of each boost module is connected to the negative output terminal of a corresponding photovoltaic module. The boost modules are connected in series with each other to form a series-connected boost module group. The positive output terminal of the first boost module in the boost module group is connected to the positive input terminal of the DC-AC conversion module, and the negative output terminal of the last boost module in the boost module group is connected to the negative input terminal of the DC-AC conversion module. The first output terminal and the second output terminal of the DC-AC conversion module are connected in parallel with the external power grid. The first active disturbance rejection control module is used to collect the voltage at the output terminal of each boost module, compare it with a set reference voltage to generate a switching control signal, and send the switching control signal to the control signal receiving terminal of the boost module. The boost module generates direct current according to the switching control signal. The second active disturbance rejection control module is used to obtain the input voltage, input current, output voltage, and output current of the DC-AC conversion module, obtain the internal phase shift angle and external phase shift angle of the DC-AC conversion module through the active disturbance rejection control algorithm, and then control the DC-AC conversion module to convert the direct current input from the boost module group into industrial frequency alternating current according to the internal phase shift angle and the external phase shift angle.

2. The micro-inverter circuit based on active disturbance rejection control according to claim 1, wherein The first active disturbance rejection control module includes a first voltage acquisition module, a first-order linear active disturbance rejection controller, and a PWM generator. The boost module includes a first inductor, a first fully controlled switch tube, a first diode, and a first capacitor. One end of the first inductor is connected to the positive output terminal of the photovoltaic module, and the other end of the first inductor, the drain of the first fully controlled switch tube, and the positive electrode of the first diode are connected. The negative electrode of the first diode is connected to one end of the first capacitor and serves as the positive output terminal of the boost module. The negative output terminal of the adjacent previous boost module is connected to the positive output terminal of the next boost module. The first voltage acquisition module is used to collect the voltage between the positive output terminal and the negative output terminal of the boost module and send it to the first-order linear active disturbance rejection controller. The first-order linear active disturbance rejection controller obtains the duty cycle control quantity through the active disturbance rejection control algorithm according to the received voltage and sends it to the PWM generator. The PWM generator sends a corresponding switching control signal to the control end of the first fully controlled switch tube according to the received duty cycle control quantity.

3. A micro-inverter circuit based on active disturbance rejection control according to claim 1, characterized in that The described DC-AC conversion module includes an H-bridge module, a resonant module, a high-frequency transformer, a cycloconverter, and a filter. The positive input terminal of the H-bridge module is connected to the positive output terminal of the first boost module in the boost module group. The negative input terminal of the H-bridge module is connected to the negative output terminal of the last boost module in the boost module group. The first output terminal of the H-bridge module is connected to the input terminal of the resonant module. The output terminal of the resonant module is connected to one end of the primary side of the high-frequency transformer. The second output terminal of the H-bridge module is connected to the other end of the primary side of the high-frequency transformer. One end of the secondary side of the high-frequency transformer is connected to the first input terminal of the cycloconverter. The other end of the secondary side of the high-frequency transformer is connected to the second input terminal of the cycloconverter. The first output terminal of the cycloconverter is connected to the first input terminal of the filter. The second output terminal of the cycloconverter is connected to the second output terminal of the filter. The first output terminal and the second output terminal of the filter are respectively connected in parallel to both ends of the external power grid.

4. The micro-inverter circuit based on active disturbance rejection control according to claim 3, characterized in that The described second active disturbance rejection control module includes a second voltage acquisition module, a third voltage acquisition module, a fourth voltage acquisition module, a first current acquisition module, a second current acquisition module, a first phase-shift angle calculation module, a second phase-shift angle calculation module, a first drive signal generation module, and a second drive signal generation module. The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module and send it to the first phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module and send it to the first phase-shift angle calculation module. The fourth voltage acquisition module is used to acquire the grid-side voltage output to the external power grid and send it to the first phase-shift angle calculation module. The first phase-shift angle calculation module obtains the phase-shift angle θ between the first output terminal and the second output terminal of the H-bridge module through the active disturbance rejection control algorithm and sends it to the first drive signal generation module. The first drive signal generation module controls the operation of the H-bridge module according to the phase-shift angle θ; The first current acquisition module is used to acquire the primary input current at the positive input terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The second current acquisition module is used to acquire the grid-side current output from the filter to the external power grid and send it to the second phase-shift angle calculation module. The second voltage acquisition module is used to acquire the voltage between the positive input terminal and the negative input terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The third voltage acquisition module is used to acquire the voltage between the first output terminal and the second output terminal of the H-bridge module and send it to the second phase-shift angle calculation module. The second phase-shift angle calculation module obtains the phase-shift angle between the first output terminal of the H-bridge module and the first input terminal of the cycloconverter through the active disturbance rejection control algorithm. and sends it to the second drive signal generation module. The second drive signal generation module controls the operation of the cycloconverter according to the phase-shift angle. ​ 5. The micro-inverter circuit based on active disturbance rejection control according to claim 4, wherein The described first phase-shift angle calculation module includes a first active disturbance rejection controller with a first tracking differentiator and a first extended state observer. The described second voltage acquisition module is used to acquire the voltage between the first input terminal and the second input terminal of the H-bridge module and send it as a reference voltage to the first tracking differentiator. The described fourth voltage acquisition module is used to acquire the grid-side voltage V output from the filter to the external power grid out , and the first active disturbance rejection controller takes the product of the peak value of the grid-side voltage V out and the reciprocal of the turns ratio of the high-frequency transformer as the voltage controlled quantity and inputs it into the first extended state observer. The first active disturbance rejection controller obtains the phase-shift angle θ through the internal active disturbance rejection control algorithm. The expression of the phase-shift angle θ is: where V fb is the voltage between the first output terminal and the second output terminal of the H-bridge module, V DC is the voltage between the positive input terminal and the negative input terminal of the H-bridge module, and ω s is the switching angular frequency of the fully controlled switch tubes included in the H-bridge module; The second phase-shift angle calculation module described above includes a second active disturbance rejection controller with a second tracking differentiator and a second extended state observer. The first current acquisition module is used to acquire the primary input current I at the positive input terminal of the H-bridge module. DC , and the second active disturbance rejection controller uses the product of the primary input current I DC and the reciprocal of the turns ratio of the high-frequency transformer as the current controlled quantity and inputs it into the second tracking differentiator. The second current acquisition module is used to acquire the grid-side current i output from the filter to the external power grid. o , and the second active disturbance rejection controller uses the peak value of the grid-side current i o as the reference current and inputs it into the second extended state observer. The second active disturbance rejection controller obtains the phase-shift angle through the internal active disturbance rejection control algorithm. Phase-shift angle The expression of is: where P avg(pu) is the per-unit value, M is the instantaneous voltage gain of the high-frequency inverter, n is the turns ratio of the high-frequency transformer, X r is the equivalent impedance, f is the switching frequency of the fully controlled switch tube in the cycloconverter, Q is the quality factor, L is the inductance value of the filter, C’ represents the equivalent capacitance value common to the cycloconverter and the filter, R x is the equivalent resistance common to the cycloconverter and the filter.

6. The micro-inverter circuit based on active disturbance rejection control according to claim 5, wherein The described H-bridge module includes a second capacitor, a second fully-controlled switch, a third fully-controlled switch, a fourth fully-controlled switch, and a fifth fully-controlled switch. One end of the second capacitor, the drain of the second fully-controlled switch, and the drain of the fourth fully-controlled switch are connected and serve as the first input terminal of the H-bridge module. The source of the second fully-controlled switch is connected to the drain of the third fully-controlled switch and serves as the first output terminal of the H-bridge module. The other end of the second capacitor, the source of the third fully-controlled switch, and the source of the fifth fully-controlled switch are connected and serve as the second input terminal of the H-bridge module. The source of the fourth fully-controlled switch is connected to the drain of the fifth fully-controlled switch and serves as the second output terminal of the H-bridge module. The pulse signal levels received by the second fully-controlled switch and the third fully-controlled switch are opposite, and the pulse signal levels received by the fourth fully-controlled switch and the fifth fully-controlled switch are opposite.

7. A micro-inverter circuit based on active disturbance rejection control according to claim 5, characterized in that The described cycloconverter includes a sixth fully-controlled switch, a seventh fully-controlled switch, an eighth fully-controlled switch, and a ninth fully-controlled switch. The source of the sixth fully-controlled switch is connected to the source of the seventh fully-controlled switch and serves as the first input terminal of the cycloconverter. The drain of the sixth fully-controlled switch serves as the first output terminal of the cycloconverter. The drain of the seventh fully-controlled switch is connected to the drain of the eighth fully-controlled switch. The source of the eighth fully-controlled switch is connected to the source of the ninth fully-controlled switch and serves as the second input terminal of the cycloconverter. The drain of the ninth fully-controlled switch serves as the second output terminal of the cycloconverter. The pulse signal levels received by the sixth fully-controlled switch and the seventh fully-controlled switch are opposite, and the pulse signal levels received by the eighth fully-controlled switch and the ninth fully-controlled switch are opposite.

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