A dc-dc converter, inverter and photovoltaic system
By using a circuit structure consisting of an input inductor, a transformer, and a unidirectional conductive unit, the problems of low voltage gain and current ripple limitation in existing DC-DC converters are solved, achieving high-gain and low-ripple power transmission and reducing system cost and losses.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 无锡天青元储智能科技有限公司
- Filing Date
- 2023-12-13
- Publication Date
- 2026-06-30
AI Technical Summary
Existing DC-DC converters have low voltage gain, and input current ripple limits output power. They can only output three-level voltage by adding windings, which increases cost and size.
The circuit structure consists of an input inductor, transformer, switching transistor, and unidirectional conductive unit. The voltage gain is adjusted by controlling the duty cycle of the switching transistor. A boost, zero input current ripple, and clamping structure is formed using capacitors and diodes to achieve high gain and three-level output. At the same time, the capacitor is shared to reduce the number of components.
It achieves high-gain voltage output, reduces input current ripple, reduces the number of capacitors, reduces system losses and costs, and improves power transmission efficiency.
Smart Images
Figure CN117713537B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photovoltaic power generation technology, specifically to a DC converter, inverter, and photovoltaic system. Background Technology
[0002] Solar energy, a green, sustainable, and renewable energy source, can reduce the use of fossil fuels and carbon dioxide emissions. In the use of solar energy, it is mostly converted into voltage input to the power grid through photovoltaic systems. The specific conversion process is as follows: first, solar energy is converted into DC voltage by photovoltaic panels; then, a DC-DC converter is used to boost the DC voltage; finally, the boosted voltage is inverted to obtain AC voltage that can be input to the power grid.
[0003] Existing DC-DC converters have low voltage gain, and a single DC-DC converter cannot boost the DC voltage to grid specifications. Cascading multiple DC-DC converters increases application costs and reduces reliability. Furthermore, photovoltaic panels are typically equivalent to current sources, resulting in large current ripple input to the DC-DC converter, which limits the output power of the photovoltaic system. Finally, existing DC-DC converters can only output three-level voltages by adding secondary windings to the transformer, requiring more than three windings. This increases the cost and size of the transformer and introduces a large steady-state voltage difference, which is detrimental to practical applications.
[0004] For existing DC-DC converters, although there are circuit structures that can reduce input current ripple, these circuit structures can only reduce current ripple and cannot reuse components with the boost circuits in the DC-DC converter, thus increasing the number of components in the entire DC-DC converter. Summary of the Invention
[0005] In view of the shortcomings of the prior art, the present invention provides a DC converter, inverter and photovoltaic system. The technical problem to be solved is that the existing DC converter has low gain, the input current ripple limits the output power, and the three-level voltage can only be output by adding windings.
[0006] To solve the above technical problems, in a first aspect, the present invention provides the following technical solution: a DC-DC converter, comprising an input inductor L0, a transformer, a switching transistor S, a first unidirectional conductive unit, a second unidirectional conductive unit, a third unidirectional conductive unit, a fourth unidirectional conductive unit, a fifth unidirectional conductive unit, a sixth unidirectional conductive unit, a seventh unidirectional conductive unit, an output capacitor C0, an output capacitor C6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C7;
[0007] One end of the input inductor L0 is used to be electrically connected to the positive terminal of the external power supply, and the other end of the input inductor L0 is electrically connected to one end of the primary side of the transformer. The other end of the primary side of the transformer is electrically connected to the input terminal of the first unidirectional conductive unit.
[0008] The output terminal of the first unidirectional conductive unit is connected in series with the second unidirectional conductive unit, the third unidirectional conductive unit, the fourth unidirectional conductive unit, the fifth unidirectional conductive unit, the sixth unidirectional conductive unit, and the seventh unidirectional conductive unit in sequence;
[0009] The output terminal of the sixth unidirectional conductive unit is electrically connected to one end of the output capacitor C0, and the other end of the output capacitor C0 is electrically connected to one end of the output capacitor C6. The other end of the output capacitor C6 is used to be electrically connected to the negative terminal of the external power supply.
[0010] The other end of the primary side of the transformer is electrically connected to the other end of the output capacitor C6 through the switching transistor S;
[0011] The output terminal of the first unidirectional conductive unit is electrically connected to the other end of the inductor L0 through the capacitor C7, and electrically connected to one end of the secondary side of the transformer through the capacitor C4; the other end of the secondary side of the transformer is electrically connected to the output terminal of the second unidirectional conductive unit through the capacitor C5, electrically connected to the output terminal of the fourth unidirectional conductive unit through the capacitor C3, and electrically connected to the output terminal of the sixth unidirectional conductive unit through the capacitor C2; the input terminal of the sixth unidirectional conductive unit is electrically connected to the input terminal of the fourth unidirectional conductive unit through the capacitor C1.
[0012] In one embodiment of the first aspect, the switching transistor S is an NMOS transistor, the other end of the primary side of the transformer is electrically connected to the drain of the NMOS transistor, the source of the NMOS transistor is electrically connected to the other end of the capacitor C6, and the gate of the NMOS transistor is used to input a drive signal.
[0013] In one embodiment of the first aspect, the first unidirectional conductive unit includes a diode D6, the anode of the diode D6 being the input terminal of the first unidirectional conductive unit, and the cathode of the diode D6 being the output terminal of the first unidirectional conductive unit.
[0014] In one embodiment of the first aspect, the second unidirectional conductive unit includes a diode D4, the anode of the diode D4 being the input terminal of the second unidirectional conductive unit, and the cathode of the diode D4 being the output terminal of the second unidirectional conductive unit.
[0015] The third unidirectional conductive unit includes a diode D5, with the anode of the diode D5 being the input terminal of the third unidirectional conductive unit and the cathode of the diode D5 being the output terminal of the third unidirectional conductive unit.
[0016] In one embodiment of the first aspect, the fourth unidirectional guiding unit includes a diode D3, the anode of which is the input terminal of the fourth unidirectional guiding unit, and the cathode of which is the output terminal of the fourth unidirectional guiding unit.
[0017] In one embodiment of the first aspect, the fifth unidirectional conductive unit includes a diode D1, the anode of which is the input terminal of the fifth unidirectional conductive unit, and the cathode of which is the output terminal of the fifth unidirectional conductive unit.
[0018] In one embodiment of the first aspect, the sixth unidirectional conductive unit includes a diode D2, the anode of which is the input terminal of the sixth unidirectional conductive unit, and the cathode of which is the output terminal of the sixth unidirectional conductive unit.
[0019] In one embodiment of the first aspect, the seventh unidirectional conductive unit includes a diode D0, the anode of which is the input terminal of the seventh unidirectional conductive unit, and the cathode of which is the output terminal of the seventh unidirectional conductive unit.
[0020] Secondly, the present invention provides an inverter that includes the aforementioned DC-DC converter.
[0021] Thirdly, the present invention provides a photovoltaic system including the inverter described above.
[0022] The beneficial effects of this invention compared with the prior art are as follows: For the DC converter of this invention, capacitors C1-C5 and the second unidirectional conduction unit-sixth unidirectional conduction unit form a boost structure. By controlling the conduction duty cycle of the switching transistor in one cycle, the positive voltage gain of the DC converter can be adjusted, thus achieving high gain.
[0023] The output capacitors C0 and C6 form a three-level output structure, which allows three-level output to be achieved without adding windings.
[0024] The input inductor L0, the primary side of the transformer, capacitors C4 and C5, output capacitors C6 and C7 form a zero-input current ripple structure, which can reduce input current ripple. Furthermore, the output capacitor C6 is shared, which can reduce the number of capacitors in the circuit.
[0025] In addition, the first unidirectional conductive unit, capacitor C4, and output capacitor C6 form a clamping structure. The clamping structure can transfer the leakage inductance to capacitor C6 when the switch S is turned off, thereby suppressing voltage and current spikes. Moreover, it shares the output capacitor C6 with the three-level structure, reducing the number of capacitors. Attached Figure Description
[0026] Figure 1This is a schematic diagram showing the connection between the DC converter of the present invention and the load R in the embodiment;
[0027] Figure 2 This is a schematic diagram showing the connection between the DC converter circuit and the load R in an embodiment of the present invention. Detailed Implementation
[0028] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.
[0029] Example 1
[0030] like Figure 1 As shown, a DC-DC converter includes an input inductor L0, a transformer, a switching transistor S, a first unidirectional conductive unit 1, a second unidirectional conductive unit 2, a third unidirectional conductive unit 3, a fourth unidirectional conductive unit 4, a fifth unidirectional conductive unit 5, a sixth unidirectional conductive unit 6, a seventh unidirectional conductive unit 7, an output capacitor C0, an output capacitor C6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C7.
[0031] Among them Figure 1 In this example, the primary side of the transformer is equivalent to inductance L1, and the secondary side of the transformer is equivalent to inductance L2.
[0032] exist Figure 1 In the process, one end of the input inductor L0 is electrically connected to the positive terminal of the external power supply Vin, the other end of the input inductor L0 is electrically connected to one end of the primary side of the transformer, and the other end of the primary side of the transformer is electrically connected to the input terminal of the first unidirectional conductive unit 1.
[0033] The output terminal of the first unidirectional conductive unit 1 is connected in series with the second unidirectional conductive unit 2, the third unidirectional conductive unit 3, the fourth unidirectional conductive unit 4, the fifth unidirectional conductive unit 5, the sixth unidirectional conductive unit 6 and the seventh unidirectional conductive unit 7.
[0034] The output terminal of the sixth unidirectional conductive unit 6 is electrically connected to one end of the output capacitor C0, and the other end of the output capacitor C0 is electrically connected to one end of the output capacitor C6. The other end of the output capacitor C6 is used to be electrically connected to the negative terminal of the external power supply Vin.
[0035] The other end of the primary side of the transformer is electrically connected to the other end of the output capacitor C6 through the switching transistor S;
[0036] The output terminal of the first unidirectional conductive unit 1 is electrically connected to the other end of the inductor L0 through capacitor C7, and electrically connected to one end of the secondary side of the transformer through capacitor C4; the other end of the secondary side of the transformer is electrically connected to the output terminal of the second unidirectional conductive unit 2 through capacitor C5, electrically connected to the output terminal of the fourth unidirectional conductive unit 4 through capacitor C3, and electrically connected to the output terminal of the sixth unidirectional conductive unit 6 through capacitor C2; the input terminal of the sixth unidirectional conductive unit 6 is electrically connected to the input terminal of the fourth unidirectional conductive unit 4 through capacitor C1.
[0037] For the first unidirectional conductive unit 1 to the seventh unidirectional conductive unit 7 in this embodiment, the unidirectional conductive unit is turned on when the voltage difference between the input terminal of the unidirectional conductive unit and the output terminal of the unidirectional conductive unit is greater than the threshold voltage.
[0038] exist Figure 1 In this embodiment, the switching transistor S is an NMOS transistor. The other end of the primary side of the transformer is electrically connected to the drain of the NMOS transistor, and the source of the NMOS transistor is electrically connected to the other end of the capacitor C6. The gate of the NMOS transistor is used to input the drive signal. In this embodiment, the drive signal is a PWM signal. By controlling the duty cycle of the PWM signal, the on and off times of the NMOS transistor in one cycle can be controlled.
[0039] In this embodiment, a circuit diagram of the DC-DC converter is shown below. Figure 2 As shown, from Figure 2 It can be obtained from this.
[0040] The first unidirectional conductive unit 1 includes a diode D6, the anode of which is the input terminal of the first unidirectional conductive unit 1, and the cathode of which is the output terminal of the first unidirectional conductive unit 1.
[0041] The second unidirectional conductive unit 2 includes a diode D4, the anode of which is the input terminal of the second unidirectional conductive unit 2, and the cathode of which is the output terminal of the second unidirectional conductive unit 2.
[0042] The third unidirectional conductive unit 3 includes a diode D5, the anode of which is the input terminal of the third unidirectional conductive unit 3, and the cathode of which is the output terminal of the third unidirectional conductive unit 3.
[0043] The fourth unidirectional guiding unit 4 includes a diode D3, the anode of which is the input terminal of the fourth unidirectional guiding unit 4, and the cathode of which is the output terminal of the fourth unidirectional guiding unit 4.
[0044] The fifth unidirectional conductive unit 5 includes a diode D1, the anode of which is the input terminal of the fifth unidirectional conductive unit 5, and the cathode of which is the output terminal of the fifth unidirectional conductive unit 5.
[0045] The sixth unidirectional conductive unit 6 includes a diode D2, the anode of which is the input terminal of the sixth unidirectional conductive unit 6, and the cathode of which is the output terminal of the sixth unidirectional conductive unit 6.
[0046] The seventh unidirectional conductive unit 7 includes a diode D0, the anode of which is the input terminal of the seventh unidirectional conductive unit 7, and the cathode of which is the output terminal of the seventh unidirectional conductive unit 7.
[0047] In addition, Figure 1 In the diagram, capacitors C0 through C7 have positive and negative terminals, where:
[0048] The end of capacitor C0 that is electrically connected to the cathode of diode D0 is the positive terminal, and the other end of capacitor C0 is the negative terminal;
[0049] The end of capacitor C1 that is electrically connected to the cathode of diode D1 is the positive terminal, and the other end of capacitor C1 is the negative terminal.
[0050] The end of capacitor C2 that is electrically connected to diode D2 is the positive terminal, and the other end of capacitor C2 is the negative terminal;
[0051] The end of capacitor C3 that is electrically connected to diode D3 is the positive terminal, and the other end of capacitor C3 is the negative terminal;
[0052] The end of capacitor C4 that is electrically connected to the cathode of diode D6 is the negative terminal, and the other end of capacitor C4 is the positive terminal;
[0053] The end of capacitor C5 that is electrically connected to inductor L2 is the positive terminal, and the other end of capacitor C5 is the negative terminal;
[0054] The end of capacitor C6 that is electrically connected to the negative terminal of the external power supply Vin is the negative terminal, and the other end of capacitor C6 is the positive terminal.
[0055] The end of capacitor C7 that is electrically connected to the input inductor L0 is the negative terminal, and the other end of capacitor C7 is the positive terminal.
[0056] right Figure 2 The circuit shown is analyzed as follows:
[0057] First, output capacitors C0 and C6 form a three-level output structure; capacitors C1-C5 and diodes D1-D5 form a boost structure; inductor L1, input inductor L0, diode D6, capacitors C4 and C5, and output capacitor C6 form a zero-input current ripple structure; diode D6, capacitor C4, and output capacitor C6 form a clamping structure.
[0058] Secondly, for the boost structure, zero-input current ripple structure, and clamping structure, the output capacitor C6, capacitor C4, and diode D6 are shared, realizing device reuse and reducing the number of components in the circuit.
[0059] Finally, regarding the clamping structure, when the switch S is turned on, capacitor C4 and diode D4 form a boost unit; when the switch S is turned off, the leakage inductance transfers energy to the output C6 through diode D6 and capacitor C4, thereby suppressing voltage and current spikes.
[0060] For a zero-input current ripple structure, when the switch S is turned on, the current in inductor L1 is less than the current in inductor L0 and begins to rise. The external power supply Vin, input inductor L0, output capacitor C6, and capacitor C7 form one current loop, and the external power supply Vin, input inductor L0, inductor L1, and switch S form another current loop. The current fluctuations of inductor L1 and capacitor C7 are superimposed, making the current ripple flowing through input inductor L0 equal to zero. When the current in inductor L1 rises to be greater than the current in input inductor L0, inductor L1, switch S, output capacitor C6, and capacitor C7 form a current loop. The current fluctuations of inductor L1 and capacitor C7 are superimposed, making the current ripple flowing through input inductor L0 equal to zero. When the switch S is turned off, the current in inductor L1 begins to decrease. Inductor L1, diode D6, capacitor C4, and capacitor C7 form a current loop. The current fluctuations of inductor L1 and capacitor C7 cancel each other out, thereby eliminating the current ripple of input inductor L0. When the inductor current L1 drops to a negative value, the external power supply Vin, input inductor L0, output capacitor C6, and capacitor C7 form a current loop. The current fluctuations of inductor L1 and capacitor C7 cancel each other out, thereby eliminating the current ripple of input inductor L0.
[0061] For the boost mechanism and three-level output structure, when the switch S is on, inductor L2 charges capacitor C3 through diode D3, and inductor L2 and capacitor C1 charge capacitor C2 together through diode D2. Inductor L2 and capacitor C5 also charge capacitor C4 through diode D4. When the switch S is off, inductor L2 charges capacitor C5 through diode D5, and inductor L2 and capacitor C3 charge capacitor C1 through diode D1. Capacitor C2 charges output capacitor C0 through diode D0. External power supply Vin, inductor L1, and capacitor C4 charge output capacitor C6 through diode D6. When inductor L1 and inductor L2 are equal in magnitude, the voltages of output capacitor C0 and output capacitor C6 are equal, both being 0.5 times the output voltage. This improves power transmission efficiency and reduces system losses.
[0062] In addition, in this embodiment, inductor L1 and inductor L2 form a transformer, with inductor L1 corresponding to the primary side of the transformer and inductor L2 corresponding to the secondary side of the transformer.
[0063] Example 2
[0064] This embodiment provides an inverter, which includes a DC-DC converter as described in Embodiment 1.
[0065] Example 3
[0066] This embodiment provides a photovoltaic system, which includes the inverter from Embodiment 2.
[0067] Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A direct current converter, characterized by It includes an input inductor L0, a transformer, a switching transistor S, a first unidirectional conductive unit, a second unidirectional conductive unit, a third unidirectional conductive unit, a fourth unidirectional conductive unit, a fifth unidirectional conductive unit, a sixth unidirectional conductive unit, a seventh unidirectional conductive unit, an output capacitor C0, an output capacitor C6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C7. One end of the input inductor L0 is used to be electrically connected to the positive terminal of the external power supply, and the other end of the input inductor L0 is electrically connected to one end of the primary side of the transformer. The other end of the primary side of the transformer is electrically connected to the input terminal of the first unidirectional conductive unit. The output terminal of the first unidirectional conductive unit is connected in series with the second unidirectional conductive unit, the third unidirectional conductive unit, the fourth unidirectional conductive unit, the fifth unidirectional conductive unit, the sixth unidirectional conductive unit, and the seventh unidirectional conductive unit in sequence; The output terminal of the sixth unidirectional conductive unit is electrically connected to one end of the output capacitor C0, and the other end of the output capacitor C0 is electrically connected to one end of the output capacitor C6. The other end of the output capacitor C6 is used to be electrically connected to the negative terminal of the external power supply. The other end of the primary side of the transformer is electrically connected to the other end of the output capacitor C6 through the switching transistor S; The output terminal of the first unidirectional conductive unit is electrically connected to the other end of the input inductor L0 through capacitor C7, and electrically connected to one end of the secondary side of the transformer through capacitor C4; the other end of the secondary side of the transformer is electrically connected to the output terminal of the second unidirectional conductive unit through capacitor C5, electrically connected to the output terminal of the fourth unidirectional conductive unit through capacitor C3, and electrically connected to the output terminal of the sixth unidirectional conductive unit through capacitor C2; the input terminal of the sixth unidirectional conductive unit is electrically connected to the input terminal of the fourth unidirectional conductive unit through capacitor C1.
2. A dc-dc converter according to claim 1, characterized in that The switching transistor S is an NMOS transistor. The other end of the primary side of the transformer is electrically connected to the drain of the NMOS transistor. The source of the NMOS transistor is electrically connected to the other end of the output capacitor C6. The gate of the NMOS transistor is used to input the drive signal.
3. A dc-dc converter according to claim 1, characterized in that The first unidirectional conductive unit includes a diode D6, the anode of which is the input terminal of the first unidirectional conductive unit, and the cathode of which is the output terminal of the first unidirectional conductive unit.
4. A dc-dc converter according to claim 1, characterized in that The second unidirectional conductive unit includes a diode D4, the anode of which is the input terminal of the second unidirectional conductive unit, and the cathode of which is the output terminal of the second unidirectional conductive unit. The third unidirectional conductive unit includes a diode D5, with the anode of the diode D5 being the input terminal of the third unidirectional conductive unit and the cathode of the diode D5 being the output terminal of the third unidirectional conductive unit.
5. A dc-dc converter according to claim 1, characterized in that The fourth unidirectional guiding unit includes a diode D3. The anode of the diode D3 is the input terminal of the fourth unidirectional guiding unit, and the cathode of the diode D3 is the output terminal of the fourth unidirectional guiding unit.
6. A dc-dc converter according to claim 1, characterized in that The fifth unidirectional conductive unit includes a diode D1, with the anode of the diode D1 being the input terminal of the fifth unidirectional conductive unit and the cathode of the diode D1 being the output terminal of the fifth unidirectional conductive unit.
7. A dc-dc converter according to claim 1, characterized in that The sixth unidirectional conductive unit includes a diode D2, with the anode of the diode D2 being the input terminal of the sixth unidirectional conductive unit and the cathode of the diode D2 being the output terminal of the sixth unidirectional conductive unit.
8. A dc-dc converter according to claim 1, characterized in that The seventh unidirectional conductive unit includes a diode D0, with the anode of the diode D0 being the input terminal of the seventh unidirectional conductive unit and the cathode of the diode D0 being the output terminal of the seventh unidirectional conductive unit.
9. An inverter, characterized by comprising: Includes a DC-DC converter as described in any one of claims 1-7.
10. A photovoltaic system characterized by, Including the inverter described in claim 9.