Ultra-high voltage gain DC / AC converter based on synchronous PWM control

Abstract

The present invention discloses an ultra-high voltage gain DC / AC converter based on synchronous PWM control, including a synchronous PWM control module and a three-port half-bridge inverter unit, wherein the three-port half-bridge inverter unit includes a dual three-port boost unit; the synchronous PWM control module controls the output voltage by adjusting the duty cycle of two switch tubes; the dual three-port boost unit is used to achieve ultra-high voltage gain; the three-port half-bridge inverter converts direct current into alternating current to connect to the power grid. Ultra-high voltage gain is achieved by staggered charging and discharging between capacitors. The converter includes two sets of coupled inductors, and the input current ripples of the two branches are complementary, so that low ripple continuous input current can be achieved. The converter is an isolated converter, and can output positive and negative equal or unequal bipolar voltages, which can effectively reduce the leakage current caused by the parasitic capacitance of the input side photovoltaic panel, so that it can be used in the field of photovoltaic power generation and grid connection.

Description

Technical Field

[0001] The present invention relates to the technical field of DC / AC converters, and in particular to an ultra-high voltage gain DC / AC converter based on synchronous PWM control. Background Art

[0002] Due to the large parasitic capacitance of the photovoltaic panels, significant leakage current will be generated. These leakage currents will eventually flow back to the ground from the positive pole of the photovoltaic panels through the inverter, causing considerable energy loss and causing voltage and current distortion, thereby reducing the power quality of the power grid. Traditional high-gain converters cannot effectively control these leakage currents.

[0003] Current DC converters usually have low voltage gain, which makes them unable to be cascaded with half-bridge inverters. In addition, the input current ripple of these DC converters is large. Since photovoltaic panels are usually regarded as current sources, large current ripple will reduce the output power of photovoltaic panels. In short, the parasitic capacitance problem of photovoltaic panels leads to increased leakage current and energy loss, and also affects the power quality of the power grid. The performance of existing DC / AC converters in this regard is not ideal. Their low voltage gain and high current ripple characteristics also limit their application in photovoltaic systems. Summary of the invention

[0004] To solve the above problems, the present invention provides an ultra-high voltage gain DC / AC converter based on synchronous PWM control, which can provide a large gain.

[0005] The present invention provides an ultra-high voltage gain DC / AC converter based on synchronous PWM control, comprising:

[0006] A synchronous PWM control module and a three-port half-bridge inverter unit, wherein the three-port half-bridge inverter unit includes a dual three-port boost unit;

[0007] The synchronous PWM control module adjusts the switch tube , switch tube The duty cycle of the dual three-port boost unit is used to regulate the output voltage of the dual three-port boost unit, which includes a switch tube , switch tube , primary inductance , primary inductance ,diode and capacitor The primary inductance The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second end is connected to the negative pole of the power supply; the primary inductor The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second terminal is connected to the capacitor First terminal, capacitor The second end is connected to the primary inductor The second end; the diode Positive connection switch tube The second end, the negative pole is connected to the negative pole of the power supply;

[0008] The dual three-port boost unit is used to achieve high voltage gain, and includes capacitors ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,diode ,diode ,diode ,diode ,diode ,diode ,diode , Secondary inductance , Secondary inductance The capacitor The first terminal and the diode The positive poles are connected to the primary inductor The second terminal, capacitor The second end is connected to the diode Cathode and diode Anode, diode Negative connection diode Positive electrode and capacitor First terminal, diode Negative connection capacitor First terminal, capacitor The second terminal and capacitor The second end is connected to the secondary inductor First terminal, secondary inductor The second end is connected to the negative pole of the power supply; the capacitor The first end is connected to the negative pole of the power supply, and the second end is connected to the diode Anode and diode Negative pole, diode Negative connection secondary inductor First terminal, diode Anode connected to diode Negative electrode and capacitor First terminal, capacitor The second end is connected to the secondary inductor The first terminal and the diode Negative pole, diode Positive connection capacitor The first and secondary inductors The second terminal, diode Positive electrode and capacitor The second terminal is connected to the capacitor First terminal, capacitor The second terminal is connected to the capacitor The second end;

[0009] The three-port half-bridge inverter unit also includes a switch tube , switch tube and filter inductor , the switch tube The first terminal is connected to the capacitor The first end, the switch tube The first terminal is connected to the capacitor The first end, the switch tube The second end is connected to the switch tube The second end, the filter inductor The first end is connected to the switch tube The second end, filter inductor The second terminal and capacitor The second end serves as an output port of the three-port half-bridge inverter unit;

[0010] The switch tube , switch tube Open at the same time, and close at the same time;

[0011] The primary inductance With secondary inductance Mutual coupling, primary inductance With secondary inductance Mutually coupled.

[0012] Furthermore, the diode ,capacitance , the power supply constitutes the primary inductance The clamping structure; the capacitor ,capacitance ,diode , Secondary inductance ,capacitance ,diode , power supply constitutes primary inductance Clamping structure.

[0013] Furthermore, the switch , switch tube The control method of industrial frequency complementation is adopted, when one is turned on, the other is turned off.

[0014] Furthermore, the ultra-high voltage gain DC / AC converter based on synchronous PWM control has four modes in one working cycle:

[0015] The first mode: switch tube And switch tube Apply trigger pulse, switch tube And switch tube In this mode, the capacitor The induced voltage is positive, the capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, the secondary inductor With capacitor ,capacitance Give the capacitor together charging; in this mode, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging; when the capacitor The discharge ends, the mode ends, and the diode The current reaches zero under low reverse recovery conditions;

[0016] Second mode: In this mode, the switch tube And switch tube Still in the on state, the diode Stop conduction; capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging; when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Providing energy to the grid;

[0017] The third mode: In this mode, stop applying the trigger pulse and the switch tube And switch tube Off, diode In this state, the primary inductance Give the capacitor together with the power supply Charging, primary inductance , Secondary inductance , power supply to capacitor Charging, secondary inductor Capacitance Charging, secondary inductor Capacitance and capacitor Charging; when the capacitor When filled, the mode ends;

[0018] The fourth mode: In this mode, the switch tube And switch tube In the off state, the primary inductor Give the capacitor together with the power supply Charging, secondary inductor Capacitance Charging, secondary inductor Capacitance and capacitor Charging; primary inductance , Secondary inductance ,capacitance Connect the capacitor in series with the power supply Charge;

[0019] The excitation inductance and leakage inductance The primary inductance is With secondary inductance The excitation inductance and leakage inductance between and leakage inductance The primary inductance is With secondary inductance The magnetizing inductance and leakage inductance between them.

[0020] Beneficial effects of the present invention:

[0021] 1. Control switch tube , switch tube The conduction and shutdown raise the voltage of the two sets of primary and secondary coupling inductors, and finally make the capacitor ,capacitance The voltage is raised, that is, the output voltage of the dual three-port boost unit is raised, achieving an ultra-high voltage gain.

[0022] 2. Capacitor By the primary inductance , Secondary inductance ,capacitance Connected to the power supply in series, the capacitor is charged By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging, i.e. capacitor The voltage is only related to the primary inductance , Secondary inductance Regarding capacitance The voltage is related to all four inductors, forming an asymmetric charging circuit.

[0023] 3. Diode ,capacitance , the primary inductance of the power supply The clamping structure, capacitor ,capacitance ,diode , Secondary inductance ,capacitance ,diode , the primary inductance of the power supply Clamping structure. Primary inductance , primary inductance The voltage is clamped, that is, the voltage of the two sets of primary inductors is stable, because the capacitor If the voltage of the power supply is stable, the switch tube , switch tube is also clamped, effectively reducing the voltage stress of components.

[0024] 4. In mode 1 and mode 2, the switch tube , switch tube The voltage difference between the negative pole of the power supply and the input neutral point of the three-port half-bridge inverter unit is , Indicates the primary inductance , Secondary inductance The turns ratio, , Respectively, in the switch tube , switch tube Magnetizing inductance during turn-on and turn-off The voltage across the two ends. In the state of mode three and mode four, the switch tube , switch tube When the inverter is turned off, the voltage difference between the negative pole of the input power supply and the neutral point of the three-port half-bridge inverter unit input is .when When it is small, the voltage change between the power supply and the input neutral point of the three-port half-bridge inverter unit is small, which can suppress the leakage current. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a circuit of an ultra-high voltage gain DC / AC converter based on synchronous PWM control provided by an embodiment of the present invention;

[0026] Figure 2 A circuit schematic diagram of an ultra-high voltage gain DC / AC converter based on synchronous PWM control provided by an embodiment of the present invention operating in a first mode;

[0027] Figure 3 A circuit schematic diagram of an ultra-high voltage gain DC / AC converter based on synchronous PWM control provided by an embodiment of the present invention working in a second mode;

[0028] Figure 4 A circuit schematic diagram of an ultra-high voltage gain DC / AC converter based on synchronous PWM control provided by an embodiment of the present invention operating in a third mode;

[0029] Figure 5 A circuit schematic diagram of an ultra-high voltage gain DC / AC converter based on synchronous PWM control provided by an embodiment of the present invention operating in a fourth mode. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The ultra-high voltage gain DC / AC converter based on synchronous PWM control of the present invention comprises a synchronous PWM control module and a three-port half-bridge inverter unit, wherein the three-port half-bridge inverter unit comprises a dual three-port boost unit. The topology of each unit is described in detail below.

[0034] like Figure 1 As shown, the synchronous PWM control module of the present invention adjusts the switch tube , switch tube The duty cycle of the dual three-port boost unit is used to regulate the output voltage of the dual three-port boost unit, which includes a switch tube , switch tube , primary inductance , primary inductance ,diode and capacitor The primary inductance The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second end is connected to the negative pole of the power supply; the primary inductor The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second terminal is connected to the capacitor First terminal, capacitor The second end is connected to the primary inductor The second end; the diode Positive connection switch tube The second end, the negative pole, is connected to the negative pole of the power supply.

[0035] A dual three-port boost cell is used to achieve high voltage gain, which includes capacitors ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,diode ,diode ,diode ,diode ,diode ,diode ,diode , Secondary inductance , Secondary inductance The capacitor The first terminal and the diode The positive poles are connected to the primary inductor The second terminal, capacitor The second end is connected to the diode Cathode and diode Anode, diode Negative connection diode Positive electrode and capacitor First terminal, diode Negative connection capacitor First terminal, capacitor The second terminal and capacitor The second end is connected to the secondary inductor First terminal, secondary inductor The second end is connected to the negative pole of the power supply; the capacitor The first end is connected to the negative pole of the power supply, and the second end is connected to the diode Anode and diode Negative pole, diode Negative connection secondary inductor First terminal, diode Anode connected to diode Negative electrode and capacitor First terminal, capacitor The second end is connected to the secondary inductor The first terminal and the diode Negative pole, diode Positive connection capacitor The first and secondary inductors The second terminal, diode Positive electrode and capacitor The second terminal is connected to the capacitor First terminal, capacitor The second terminal is connected to the capacitor Second end.

[0036] The three-port half-bridge inverter unit also includes a switch tube , switch tube and filter inductor , the switch tube The first terminal is connected to the capacitor The first end, the switch tube The first terminal is connected to the capacitor The first end, the switch tube The second end is connected to the switch tube The second end, the filter inductor The first end is connected to the switch tube The second end, filter inductor The second terminal and capacitor The second end serves as an output port of the three-port half-bridge inverter unit.

[0037] The switch tube , switch tube Open at the same time, and close at the same time; the primary inductor With secondary inductance Mutual coupling, primary inductance With secondary inductance Mutually coupled. Switching tube , switch tube The control method of industrial frequency complementation is adopted, when one is turned on, the other is turned off. and leakage inductance The primary inductance is With secondary inductance The excitation inductance and leakage inductance between and leakage inductance The primary inductance is With secondary inductance The magnetizing inductance and leakage inductance between them.

[0038] diode ,capacitance The primary inductance is formed with the power supply The clamping structure; the capacitor ,capacitance ,diode , Secondary inductance ,capacitance ,diode , the primary inductance of the power supply Clamping structure.

[0039] The equivalent circuits of each working mode of continuous conduction mode are as follows Figure 2-Figure 5 As shown, there are four working modes in total.

[0040] Mode 1, such as Figure 2 As shown: for the switch tube And switch tube Apply trigger pulse, switch tube And switch tube In this mode, the capacitor The induced voltage is positive, the capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, at the same time, the secondary inductor With capacitor ,capacitance Give the capacitor together In this mode, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging. Due to the secondary inductance The effect of leakage inductance, when the capacitor The discharge ends, the mode ends, and the diode The current reaches zero in the case of low reverse recovery. , switch tube Adopting the power frequency complementary control method, when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Provide energy to the grid.

[0041] In this mode, the following equation can be obtained:

[0042] (1)

[0043] (2)

[0044] (3)

[0045] (4)

[0046] Mode 2, such as Figure 3 As shown: In this mode, the switch tube And switch tube Still in the on state, the diode Stop conducting. Same as mode 1, capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging. , switch tube Adopting the power frequency complementary control method, when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Provide energy to the grid.

[0047] Mode three, such as Figure 4 As shown: In this mode, stop applying the trigger pulse and the switch And switch tube Off, diode In this state, the primary inductance Give the capacitor together with the power supply Charging, primary inductance , Secondary inductance , power supply to capacitor Charging, secondary inductor Capacitance Charged and stored in the secondary inductor The energy in the capacitor is transferred to and capacitor , that is, to the capacitor and capacitor When the capacitor When the switch is fully charged, the mode ends. , switch tube Adopting the power frequency complementary control method, when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Provide energy to the grid.

[0048] In this mode, the following equation can be obtained:

[0049] (5)

[0050] (6)

[0051] (7)

[0052] (8)

[0053] Mode 4, such as Figure 5 As shown: In this mode, the switch tube And switch tube Still in the off state, the same as mode 3, the primary inductance Give the capacitor together with the power supply Charging, secondary inductor Capacitance Charged and stored in the secondary inductor The energy in the capacitor is transferred to and capacitor , that is, to the capacitor and capacitor In addition, the primary inductance and secondary inductance ,capacitance Connect the capacitor in series with the power supply Charging. , switch tube Adopting the power frequency complementary control method, when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Provide energy to the grid.

[0054] In this mode, the following voltage equation can be obtained:

[0055] (9)

[0056] From formula (4) and formula (9), we can get:

[0057] (10)

[0058] The diode ,capacitance And switch tube Components such as capacitors can form a Boost circuit. The voltage of is equal to the output voltage of the Boost converter, then we can get:

[0059] (11)

[0060] According to equations (1)-(9), the excitation inductance , Excitation inductance Applying the volt-second balance principle, we can get:

[0061] (12)

[0062] (13)

[0063] (14)

[0064] (15)

[0065] Finally, substituting equations (13), (14), and (15) into equation (10), we can obtain:

[0066] (16)

[0067] From equation (16), we can see that the voltage gain of the dual three-port boost unit can be adjusted , , Three parameters are changed by selecting the appropriate , , value, can achieve ultra-high voltage gain.

[0068] A secondary inductor is also connected between the input power supply and the input neutral point A of the three-port half-bridge inverter unit. , the two do not share the same ground. Figure 1 If point A is at 0 potential, positive and negative voltages can be drawn from points B and C respectively, that is, a bipolar wave can be drawn from the output end of the dual three-port boost unit of the converter. The positive and negative voltages of the bipolar wave may be equal or unequal. Generally, they are unequal. , , satisfy:

[0069] (17)

[0070] The positive and negative voltages of a bipolar wave are equal.

[0071] in, Indicates the power supply voltage, represents the output voltage of the dual three-port boost unit, It represents the effective value of the output AC voltage of the three-port half-bridge inverter unit. represents the voltage gain of the dual three-port boost unit, Indicates the primary inductance , Secondary inductance Turns ratio, Indicates the primary inductance , Secondary inductance Turns ratio, Indicates switch tube And switch tube The duty cycle, - Represent the voltage across the corresponding capacitor, , Respectively represent the excitation inductance In the switch tube , switch tube The voltage across the two ends when turned on and off, , Respectively represent the excitation inductance In the switch tube , switch tube The voltage across the device when it is turned on and off.

[0072] The implementation principle of ultra-high voltage gain is as follows:

[0073] In mode 1 and mode 2, the switch tube , switch tube Conduction, capacitance The input power to the primary inductor Charging, input power to the primary inductor Charging, raising the plateau inductance , primary inductance Voltage. According to the volt-second balance principle, in the state of mode three and mode four, the switch tube , switch tube When turned off, the secondary inductor , Secondary inductance The voltage is also raised.

[0074] In the working condition of mode 1, the secondary inductance With capacitor ,capacitance Give the capacitor together Charging, Capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging.

[0075] In the working condition of mode 2, the capacitor is the same as mode 1. Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging.

[0076] In the working condition of mode 3, the primary inductance Give the capacitor together with the power supply Charging, primary inductance , Secondary inductance , power supply to capacitor Charging, secondary inductor Capacitance Charged and stored in the secondary inductor The energy in the capacitor is transferred to and capacitor , that is, to the capacitor and capacitor Charge.

[0077] In the working condition of mode 4, the primary inductance is the same as that of mode 3. Give the capacitor together with the power supply Charging, secondary inductor Capacitance Charged and stored in the secondary inductor The energy in the capacitor is transferred to and capacitor , that is, to the capacitor and capacitor In addition, the primary inductance and primary inductance ,capacitance Connect the capacitor in series with the power supply Charge.

[0078] Control switch tube , switch tube The conduction and shutdown raise the voltage of the four inductors, and then through the energy conversion between the above modal capacitors, the capacitors are finally ,capacitance The voltage is raised, that is, the output voltage of the dual three-port boost unit is raised, achieving an ultra-high voltage gain.

[0079] capacitance By the primary inductance , Secondary inductance ,capacitance Connected to the power supply in series, the capacitor is charged By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging, i.e. capacitor The voltage is only related to the primary inductance , Secondary inductance Regarding capacitance The voltage of the four inductors is related to each other, forming an asymmetric charging circuit. , switch tube Duty cycle and primary inductance With secondary inductance Turns ratio To control the voltage ,when , , satisfy:

[0080]

[0081] The positive and negative voltages of a bipolar wave are equal.

[0082] The ultra-high voltage gain DC / AC converter based on synchronous PWM control has two main clamping structures, one is the diode ,capacitance , the primary inductance of the power supply The clamping structure and the other is a capacitor ,capacitance ,diode , Secondary inductance ,capacitance ,diode , the primary inductance of the power supply Clamping structure.

[0083] Inductor on the primary side In the clamping structure, the capacitor ,diode The secondary inductor Clamp, forming a nested clamp. Due to the secondary inductance Capacitor ,diode Clamp, secondary inductor The voltage at both ends is stable and can be used as a primary inductor part of the clamping structure.

[0084] Two sets of primary inductors , The voltage is clamped, that is, the two sets of primary inductance , Voltage stability due to capacitor If the voltage of the power supply is stable, the switch tube , switch tube is also clamped, effectively reducing the voltage stress of components.

[0085] A secondary inductor is also connected between the power supply and the input neutral point A of the three-port half-bridge inverter unit. The leakage current is generated because there is a potential difference between the power supply and the input neutral point of the three-port half-bridge inverter unit. In mode 1 and mode 2, the switch tube , switch tube The voltage difference between the negative pole of the power supply and the neutral point of the three-port half-bridge inverter unit input is In mode 3 and mode 4, the switch tube , switch tube Shutdown, the voltage difference between the negative pole of the input power supply and the input neutral point of the three-port half-bridge inverter unit .when When it is small, the voltage change between the power supply and the input neutral point of the three-port half-bridge inverter unit is small, which can suppress the leakage current.

[0086] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An ultra-high voltage gain DC / AC converter based on synchronous PWM control, characterized in that: include: A synchronous PWM control module and a three-port half-bridge inverter unit, wherein the three-port half-bridge inverter unit includes a dual three-port boost unit; The synchronous PWM control module adjusts the switch tube , switch tube The duty cycle of the dual three-port boost unit is used to regulate the output voltage of the dual three-port boost unit, which includes a switch tube , switch tube , primary inductance , primary inductance ,diode and capacitor The primary inductance The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second end is connected to the negative pole of the power supply; the primary inductor The first end is connected to the positive pole of the power supply, and the second end is connected to the switch tube The first end, the switch tube The second terminal is connected to the capacitor First terminal, capacitor The second end is connected to the primary inductor The second end; the diode Positive connection switch tube The second end, the negative pole is connected to the negative pole of the power supply; The dual three-port boost unit is used to achieve high voltage gain, and includes capacitors ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,diode ,diode ,diode ,diode ,diode ,diode ,diode , Secondary inductance , Secondary inductance The capacitor The first terminal and the diode The positive poles are connected to the primary inductor The second terminal, capacitor The second end is connected to the diode Cathode and diode Anode, diode Negative connection diode Positive electrode and capacitor First terminal, diode Negative connection capacitor First terminal, capacitor The second terminal and capacitor The second end is connected to the secondary inductor First terminal, secondary inductor The second end is connected to the negative pole of the power supply; the capacitor The first end is connected to the negative pole of the power supply, and the second end is connected to the diode Anode and diode Negative pole, diode Negative connection secondary inductor First terminal, diode Anode connected to diode Negative electrode and capacitor First terminal, capacitor The second end is connected to the secondary inductor The first terminal and the diode Negative pole, diode Positive connection capacitor The first and secondary inductors The second terminal, diode Positive electrode and capacitor The second terminal is connected to the capacitor First terminal, capacitor The second terminal is connected to the capacitor The second end; The three-port half-bridge inverter unit also includes a switch tube , switch tube and filter inductor , the switch tube The first terminal is connected to the capacitor The first end, the switch tube The first terminal is connected to the capacitor The first end, the switch tube The second end is connected to the switch tube The second end, the filter inductor The first end is connected to the switch tube The second end, filter inductor The second terminal and capacitor The second end serves as an output port of the three-port half-bridge inverter unit; The switch tube , switch tube Open at the same time, and close at the same time; The primary inductance With secondary inductance Mutual coupling, primary inductance With secondary inductance Mutually coupled.

2. The ultra-high voltage gain DC / AC converter based on synchronous PWM control according to claim 1, characterized in that: The diode ,capacitance , the power supply constitutes the primary inductance The clamping structure; the capacitor ,capacitance ,diode , Secondary inductance ,capacitance ,diode , power supply constitutes primary inductance Clamping structure.

3. The ultra-high voltage gain DC / AC converter based on synchronous PWM control according to claim 2, characterized in that: Switching tube , switch tube The control method of industrial frequency complementation is adopted, when one is turned on, the other is turned off.

4. The ultra-high voltage gain DC / AC converter based on synchronous PWM control according to claim 3 is characterized in that The ultra-high voltage gain DC / AC converter based on synchronous PWM control has four working modes in one working cycle: The first mode: switch tube And switch tube Apply trigger pulse, switch tube And switch tube In this mode, the capacitor The induced voltage is positive, the capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, the secondary inductor With capacitor ,capacitance Give the capacitor together charging; in this mode, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging; when the capacitor The discharge ends, the mode ends, and the diode The current reaches zero under low reverse recovery conditions; Second mode: In this mode, the switch tube And switch tube Still in the on state, the diode Stop conduction; capacitor Together with the power supply, the excitation inductor Charging, excitation inductance Only charged by the power supply, the capacitor Discharge, Capacitor By the secondary inductor , Secondary inductance ,capacitance ,capacitance ,capacitance Series charging; when the switch tube Conducting, switching tube When turned off, the capacitor Provide energy to the grid. Conducting, switching tube When turned off, the capacitor Providing energy to the grid; The third mode: In this mode, stop applying the trigger pulse and the switch tube And switch tube Off, diode In this state, the primary inductance Give the capacitor together with the power supply Charging, primary inductance , Secondary inductance , power supply to capacitor Charging, secondary inductor Capacitance Charging, secondary inductor Capacitance and capacitor Charging; when the capacitor When filled, the mode ends; The fourth mode: In this mode, the switch tube And switch tube In the off state, the primary inductor Give the capacitor together with the power supply Charging, secondary inductor Capacitance Charging, secondary inductor Capacitance and capacitor Charging; primary inductance , Secondary inductance ,capacitance Connect the capacitor in series with the power supply Charge; The excitation inductance and leakage inductance The primary inductance is With secondary inductance The excitation inductance and leakage inductance between and leakage inductance The primary inductance is With secondary inductance The magnetizing inductance and leakage inductance between them.

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