A zero-switching-loss non-isolated DC boost topology circuit and its control method

Abstract

The present invention discloses a zero-switching-loss non-isolated DC boost topology circuit and its control method. The topological structure is as follows: The positive input terminal (101) is connected to the positive electrode of the input-side voltage stabilizing capacitor (105) and the positive electrode of the input-side diode (201). The negative electrode of the input-side voltage stabilizing capacitor (105) is connected to the negative input terminal (102), the negative electrode of the main switch (206), the negative electrode of the output-side voltage stabilizing capacitor (106), and the negative output terminal (104). The negative electrode of the input-side diode (201) is connected to the negative electrode of the resonant switch (204) and the positive electrode of the energy storage inductor (202). The positive electrode of the resonant switch (204) is connected to one end of the resonant capacitor (203). The other end of the resonant capacitor (203) is connected to the negative electrode of the energy storage inductor (202), the positive electrode of the output-side diode (205), and the positive electrode of the main switch (206). The negative electrode of the output-side diode (205) is connected to the positive electrode of the output-side voltage stabilizing capacitor (106) and the positive output terminal (103). This topological structure is simple and the control is convenient.

Description

Technical Field

[0001] The present invention belongs to the field of power supplies, and relates to a unidirectional, grid-connected zero-switching-loss non-isolated DC boost topology circuit and a control method therefor. Background Art

[0002] At present, devices such as photovoltaic optimizers are all hard-switching boost circuits, which affect efficiency. After the large-scale popularization and application of optimizers, the boost technology using hard-switching topologies will significantly increase the losses of photovoltaic power generation systems. The existing soft-switching topologies have more devices and higher costs. Therefore, there is an urgent need for a low-cost soft-switching boost circuit. Summary of the Invention

[0003] Object of the Invention: The present invention proposes a zero-switching-loss non-isolated DC boost topology circuit for replacing the existing hard-switching boost topology optimizer in a photovoltaic system, which can significantly reduce losses and improve the efficiency of the photovoltaic system.

[0004] The present invention also provides a control method for the above non-isolated DC boost topology circuit.

[0005] Technical Solution: A zero-switching-loss non-isolated DC boost topology circuit includes an input positive terminal, an input negative terminal, an output positive terminal, an output negative terminal, an input-side voltage-stabilizing capacitor, an output-side voltage-stabilizing capacitor, an input-side diode, a storage inductor, a resonant capacitor, a resonant switch, an output-side diode, and a main switch. The input positive terminal is connected to the positive electrode of the input-side voltage-stabilizing capacitor and the positive electrode of the input-side diode. The negative electrode of the input-side voltage-stabilizing capacitor is connected to the input negative terminal, the negative electrode of the main switch, the negative electrode of the output-side voltage-stabilizing capacitor, and the output negative terminal. The negative electrode of the input-side diode is connected to the negative electrode of the resonant switch and the positive electrode of the storage inductor. The positive electrode of the resonant switch is connected to one end of the resonant capacitor. The other end of the resonant capacitor is connected to the negative electrode of the storage inductor, the positive electrode of the output-side diode, and the positive electrode of the main switch. The negative electrode of the output-side diode is connected to the positive electrode of the output-side voltage-stabilizing capacitor and the output positive terminal;

[0006] The zero-switching-loss operating states of the non-isolated DC boost topology circuit include:

[0007] State 1, startup: Turn on the resonant switch and the main switch. When the resonant capacitor and the storage inductor are charged to a certain amount of electricity, turn off the main switch to make the storage inductor resonate with the resonant capacitor. After the storage inductor finishes charging the resonant capacitor in the reverse direction, turn off the resonant switch, and let the resonant capacitor and the storage inductor continue to resonate until the storage inductor charges the resonant capacitor in the forward direction until the current of the storage inductor is zero. The startup state is ready, and it is ready to enter State 2;

[0008] State 2, energy storage inductor charging: Turn on the main switch to charge the energy storage inductor. The current of the energy storage inductor starts charging from 0, and the main switch conducts at quasi-zero current. When the current of the energy storage inductor reaches the target value, the charging state of the energy storage inductor ends, and it is ready to enter State 3;

[0009] State 3, zero-current turn-off of the main switch: Turn on the resonant switch to transfer the current of the energy storage inductor through the resonant capacitor, so that the current flowing through the main switch in the forward direction is 0, turn off the main switch, and achieve zero-current turn-off. The zero-current turn-off state of the main switch ends, and it automatically enters State 4;

[0010] State 4, reverse charging of the resonant capacitor: The energy storage inductor continues to conduct to charge the resonant capacitor in the reverse direction until the absolute value of the voltage of the resonant capacitor reaches the target voltage. The diode on the output side conducts and transfers the current flowing from the energy storage inductor to the resonant capacitor. The forward current of the resonant switch is 0, and the resonant switch is turned off to achieve zero-current turn-off of the resonant switch. The reverse charging state of the resonant capacitor ends, and it automatically enters State 5;

[0011] State 5, freewheeling boost: The energy storage inductor continues to conduct and charge the output-side voltage stabilizing capacitor through the output-side diode until the current of the energy storage inductor is 0, and the reverse voltage of the output-side diode recovers, completing the freewheeling boost state, and automatically entering State 6;

[0012] State 6, forward charging of the resonant capacitor: The energy storage inductor resonates with the resonant capacitor until the energy storage inductor charges the resonant capacitor in the forward direction until the voltage recovers to the target voltage. The forward charging state of the resonant capacitor ends, and it waits for an instruction to re-enter State 2.

[0013] Preferably, the main switch is any one of IGBT, IGCT, or MosFET.

[0014] Preferably, the resonant switch is any one of MosFET, IGBT, or IGCT.

[0015] Preferably, the input-side voltage stabilizing capacitor and the output-side voltage stabilizing capacitor are any one of polarized electrolytic capacitors, thin-film capacitors, or supercapacitors.

[0016] Preferably, the resonant capacitor is a non-polar capacitor.

[0017] Preferably, the positive input terminal and the negative input terminal are respectively connected to the positive and negative electrodes of the photovoltaic module or the cascaded photovoltaic modules. The positive output terminal and the negative output terminal are respectively connected to the DC grid, or are connected to the DC grid after being cascaded with other non-isolated DC boost topology circuits, or are connected to a single-pole AC / DC inverter, or are connected to a single-pole AC / DC inverter after being cascaded with other non-isolated DC boost topology circuits.

[0018] Preferably, the target voltage transformation of the resonant capacitor is the difference between the input voltage and the output voltage. The input voltage is the voltage between the input positive terminal and the input negative terminal, and the output voltage is the voltage between the output positive terminal and the output negative terminal.

[0019] The control method of the above non-isolated DC boost topology circuit is as follows: when the output voltage is greater than twice the input voltage, a soft-switching control method is adopted; when the output voltage is not higher than twice the input voltage, a hard-switching control method is adopted. At this time, the resonant switch and the resonant capacitor do not work, and the boost is realized by the on and off of the main switch.

[0020] The present invention has the following beneficial effects:

[0021] 1. The topology structure is simple. The energy storage inductor in the non-isolated DC boost main circuit is reused to construct a resonant cavity. Only one switch device and one resonant capacitor are added to the H-type topology widely used in current photovoltaic optimizers, greatly reducing the cost of the soft-switching topology.

[0022] 2. The soft-switching control method is simple and efficient. The resonant capacitor is used to reverse charge and transfer the current of the main circuit switch device, and the main circuit switch device is turned off at zero current, realizing zero-current switching of the main circuit switch device, and significantly improving the efficiency of the topology power conversion. At the same time, by utilizing the difference between the input and output voltages, natural commutation of the anti-parallel diode of the resonant switch device is used to realize zero-current turn-off of the switch device in the resonant circuit, significantly reducing the operating loss of the resonant circuit.

[0023] 3. The proposed control method is based on the proposed topology. Resonant soft-switching control is adopted when the voltage transformation ratio is greater than 2, and hard-switching control is still adopted when the voltage transformation ratio is not higher than 2, realizing the optimal efficiency in the full range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the structural diagram of the zero-switching-loss non-isolated DC boost topology circuit of the present invention;

[0025] Figure 2 is the schematic diagram of the voltage and current during the quasi-zero-current turn-off process of the main switch;

[0026] Figure 3 is the schematic diagram of the voltage and current during the zero-current conduction process of the main switch;

[0027] Figure 4 is the schematic diagram of the voltage and current during the zero-current turn-off process of the resonant switch. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solution of the present invention will be further described below in conjunction with the drawings and specific embodiments.

[0029] The present invention proposes a low-cost unidirectional grid-connected non-isolated DC boost topology circuit, such asFigure 1 As shown, it includes an input positive terminal 101, an input negative terminal 102, an output positive terminal 103, an output negative terminal 104, an input-side voltage stabilizing capacitor 105, an output-side voltage stabilizing capacitor 106, an input-side diode 201, a storage inductor 202, a resonant capacitor 203, a resonant switch 204, an output-side diode 205, and a main switch 206.

[0030] When the main switch 206 is turned on, current can flow from the positive pole to the negative pole of the main switch 206. When the main switch 206 is turned off, current cannot flow from the positive pole to the negative pole of the main switch 206. When the main switch 206 is turned on and off, current can flow from the negative pole to the positive pole of the main switch 206. The main switch 206 can preferably be any one of an IGBT, an IGCT, or a MosFET.

[0031] When the resonant switch 204 is turned on, current can flow from the positive pole to the negative pole of the resonant switch 204. When the resonant switch 204 is turned off, current cannot flow from the positive pole to the negative pole of the resonant switch 204. When the resonant switch 204 is turned on and off, current can flow from the negative pole to the positive pole of the resonant switch 204. The resonant switch 204 can preferably be any one of a MosFET, an IGBT, or an IGCT.

[0032] The input-side voltage stabilizing capacitor 105 and the output-side voltage stabilizing capacitor 106 are preferably polar electrolytic capacitors, or thin-film capacitors, or supercapacitors. The resonant capacitor 203 is a non-polar capacitor. For the convenience of description, in the present invention, the end of the resonant capacitor 203 connected to the storage inductor 202 is defined as the positive pole, and the other end is the negative pole.

[0033] The input positive terminal 101 is connected to the positive pole of the input-side voltage stabilizing capacitor 105 and the positive pole of the input-side diode 201. The negative pole of the input-side voltage stabilizing capacitor 105 is connected to the input negative terminal 102, the negative pole of the main switch 206, the negative pole of the output-side voltage stabilizing capacitor 106, and the output negative terminal 104. The negative pole of the input-side diode 201 is connected to the negative pole of the resonant switch 204 and the positive pole of the storage inductor. The positive pole of the resonant switch 204 is connected to the positive pole of the resonant capacitor 203. The negative pole of the resonant capacitor 203 is connected to the negative pole of the storage inductor 202, the positive pole of the output-side diode 205, and the positive pole of the main switch 206. The negative pole of the output-side diode 205 is connected to the positive pole of the output-side voltage stabilizing capacitor 106 and the output positive terminal 103.

[0034] The positive input terminal 101 and the negative input terminal 102 are respectively connected to the positive and negative electrodes of a photovoltaic module or a cascaded photovoltaic module. The positive output terminal 103 and the negative output terminal 104 are respectively connected to a DC power grid, or are cascaded with other non-isolated DC boost topology circuits and then connected to the DC power grid, or are connected to a single-pole AC / DC inverter, or are cascaded with other non-isolated DC boost topology circuits and then connected to a single-pole AC / DC inverter.

[0035] The open-circuit voltage of the photovoltaic module connected between the positive input terminal 101 and the negative input terminal 102 is U0, the target voltage between the positive input terminal 101 and the negative input terminal 102 is U1, the voltage between the positive output terminal 103 and the negative output terminal 104 is U2, and the capacitance of the input-side voltage-stabilizing capacitor 105 should satisfy that the charge of the input-side voltage-stabilizing capacitor 105 at U0 is greater than the charge of the resonant capacitor 203 at U3, where U3 = U2 - U1.

[0036] The control method of this non-isolated DC boost topology circuit is as follows: When U2 is greater than twice U1, that is, when U3 is greater than U1, the circuit should adopt a soft-switching control method, and the specific control process is described below; when U2 is not higher than twice U1, that is, when U3 is not higher than U1, the circuit should adopt a hard-switching control method, that is, the resonant switch 204 and the resonant capacitor 203 do not work, and the topology degenerates into a conventional H-type boost circuit, and the boost is achieved by the conduction and cut-off of the main switch 206.

[0037] The above zero-switching-loss non-isolated DC boost topology circuit has six working states in a switching cycle, and its specific control method is as follows:

[0038] State 1: Startup

[0039] When the circuit starts up, the resonant capacitor 203 needs to be charged first to enable it to transfer the current of the energy storage inductor 202 and thus reverse-block the main switch 206. First, turn on the resonant switch 204 and the main switch 206. When the resonant capacitor 203 and the energy storage inductor 202 are charged to the charge of the resonant capacitor 203 at U3, turn off the main switch 206 to make the energy storage inductor 202 resonate with the resonant capacitor 203. After the energy storage inductor 202 finishes reverse-charging the resonant capacitor 203, turn off the resonant switch 204, and let the resonant capacitor 203 and the energy storage inductor 202 continue to resonate until the energy storage inductor 202 charges the resonant capacitor 203 forward until the current of the energy storage inductor 202 is zero. At this time, the voltage of the resonant capacitor 203 is about U3. The startup state is ready, and it is ready to enter state 2.

[0040] State 2: Energy storage inductor charging

[0041] Turn on the main switch 206 to charge the energy storage inductor 202. The current of the energy storage inductor 202 starts charging from 0, and the main switch 206 conducts with quasi-zero current. When the current I1 of the energy storage inductor 202 reaches the target value Imax, the state of the energy storage inductor ends. Prepare to enter State 3.

[0042] State 3: Zero-current turn-off of the main switch

[0043] When the current I1 of the energy storage inductor 202 reaches the target value Imax, turn on the resonant switch 204 to transfer the current of the energy storage inductor 202 through the resonant capacitor 203, so that the current flowing through the main switch 206 in the forward direction is 0, and turn off the main switch 206 to achieve zero-current turn-off. The zero-current turn-off state of the main switch ends, and automatically enters State 4.

[0044] State 4: Reverse charging of the resonant capacitor

[0045] The energy storage inductor 202 continues to flow and reverse charges the resonant capacitor 203, reversely charging the voltage of the resonant capacitor 203 from U3 to -U3. The output-side diode 205 conducts and transfers the current flowing from the energy storage inductor 202 to the resonant capacitor 203. The forward current of the resonant switch 204 is 0, and the resonant switch 204 is turned off to achieve zero-current turn-off of the resonant switch. The reverse charging state of the resonant capacitor ends, and automatically enters State 5.

[0046] State 5: Flyback boost

[0047] The energy storage inductor 202 continues to flow and charges the output-side voltage stabilizing capacitor 106 through the output-side diode 205 until the current of the energy storage inductor 202 is 0, and the reverse voltage of the output-side diode 205 recovers. The flyback boost state is completed, and automatically enters State 6.

[0048] State 6: Forward charging of the resonant capacitor

[0049] The energy storage inductor 202 resonates with the resonant capacitor 203 until the energy storage inductor 202 charges the resonant capacitor 203 forward to restore the voltage to U3. The forward charging state of the resonant capacitor ends. Wait for the instruction to re-enter State 2. Stopping here is the only safe place in the whole cycle. If you want to stop the machine, you can send a control instruction at this time to stop the state transformation.

[0050] In an example of the present invention, the photovoltaic string voltage U1 between the input positive terminal 101 and the input negative terminal 102 is 350V, the output positive terminal 103 and the output negative terminal 104 are connected to the DC distribution network voltage U2 of 750V, the target value Imax of the energy storage inductor 202 is set to 100A, the capacitance value of the input-side voltage stabilizing capacitor 105 is 1mF, the capacitance value of the output-side voltage stabilizing capacitor 106 is 0.5mF, the inductance value of the energy storage inductor 202 is 1mH, the capacitance value of the resonant capacitor 203 is 1uF, the input-side diode 201 and the output-side diode 205 are selected as diodes with an average current of 50A and a breakdown voltage of 1200V, the resonant switch 204 is selected as a MosFET with an average current of 14A and a breakdown voltage of 600V, and the main switch 206 is selected as an IGBT with an average current of 50A and a breakdown voltage of 1200V.

[0051] Under this operating condition, the boost ratio U2 / U1 is greater than 2, U3 is 400V, and the main switch 206 is in a soft-switching operation control state.

[0052] State 1: Start

[0053] Turn on the resonant switch 204 and the main switch 206 to charge the resonant capacitor to 350V. When the energy storage inductor 202 is charged to 12A, hard-switch turn off the main switch tube 206 to make the energy storage inductor 202 and the resonant capacitor 203 resonate; after the energy storage inductor 202 finishes reverse-charging the resonant capacitor 203, that is, when the forward conduction current of the resonant switch 204 is 0, turn off the resonant switch 204 with zero current; let the resonant capacitor 203 and the energy storage inductor 202 continue to resonate, and the energy storage inductor 202 charges the resonant capacitor 203 forward until the current of the energy storage inductor 202 is zero. At this time, the voltage of the resonant capacitor 203 is about 400V.

[0054] State 2: Energy storage inductor charging

[0055] Turn on the main switch 206, and the photovoltaic string charges the energy storage inductor 202. The current of the energy storage inductor 202 starts to charge from 0. As Figure 2 shown, the main switch 206 conducts with quasi-zero current.

[0056] State 3: Main switch zero-current turn-off

[0057] When the current of the energy storage inductor 202 rises to 100A, turn on the resonant switch 204 to transfer the current of the energy storage inductor 202 through the resonant capacitor 203, so that the current flowing through the main switch 206 in the forward direction is 0. As Figure 3 shown, turn off the main switch 206 with zero current.

[0058] State 4: Resonant capacitor reverse charging

[0059] The energy storage inductor 202 continues to conduct current to charge the resonant capacitor 203 in reverse, charging the voltage of the resonant capacitor 203 to -400V in reverse, so that the voltage after the photovoltaic module is connected in series with the resonant capacitor 203 is 750V, equal to the voltage of the output-side voltage stabilizing capacitor 106. The output-side diode 205 conducts and transfers the current flowing from the energy storage inductor 202 to the resonant capacitor 203. The forward current of the resonant switch 204 is 0, as Figure 4 shown, the resonant switch 204 is turned off with zero current.

[0060] State 5, freewheeling boost

[0061] The energy storage inductor 202 continues to conduct current through the output-side diode 205 to charge the output-side voltage stabilizing capacitor 106 until the current of the energy storage inductor 202 becomes 0 and the reverse voltage of the output-side diode 205 recovers. The freewheeling boost state is completed and automatically enters state 6.

[0062] State 6, forward charging of the resonant capacitor

[0063] After the energy storage inductor 202 drops to 0, the inductor 202 resonates with the resonant capacitor 203 until the energy storage inductor 202 charges the resonant capacitor 203 forward to a voltage recovery of 400V, and the forward charging state of the resonant capacitor ends. At this time, the topological operating state returns to the end state of startup. At this time, it can be determined whether to enter state 2 according to the superior control instruction, so as to enter the next cycle.

[0064] The present invention multiplexes the energy storage inductor in the main circuit to construct a resonant cavity, and only adds one switching device and one resonant capacitor to the H-type topology widely used in current photovoltaic optimizers, greatly reducing the cost of the soft-switching topology. In soft-switching control, the resonant capacitor is used to charge in reverse to transfer the current of the main circuit switching device, and the main circuit switching device is turned off at zero current, realizing zero-current switching of the main circuit switching device and significantly improving the efficiency of topological power conversion. At the same time, by utilizing the difference between the input and output voltages and the natural commutation of the anti-parallel diode of the resonant switching device, zero-current turn-off of the switching device in the resonant circuit is achieved, significantly reducing the operating loss of the resonant circuit.

Claims

1. A zero-switching-loss non-isolated DC boost topology circuit, characterized in that, It includes an input positive terminal (101), an input negative terminal (102), an output positive terminal (103), an output negative terminal (104), an input-side voltage-stabilizing capacitor (105), an output-side voltage-stabilizing capacitor (106), an input-side diode (201), a storage inductor (202), a resonant capacitor (203), a resonant switch (204), an output-side diode (205), and a main switch (206). The input positive terminal (101) is connected to the positive electrode of the input-side voltage-stabilizing capacitor (105) and the positive electrode of the input-side diode (201). The negative electrode of the input-side voltage-stabilizing capacitor (105) is connected to the input negative terminal (102), the negative electrode of the main switch (206), the negative electrode of the output-side voltage-stabilizing capacitor (106), and the output negative terminal (104). The negative electrode of the input-side diode (201) is connected to the negative electrode of the resonant switch (204) and the positive electrode of the storage inductor (202). The positive electrode of the resonant switch (204) is connected to one end of the resonant capacitor (203). The other end of the resonant capacitor (203) is connected to the negative electrode of the storage inductor (202), the positive electrode of the output-side diode (205), and the positive electrode of the main switch (206). The negative electrode of the output-side diode (205) is connected to the positive electrode of the output-side voltage-stabilizing capacitor (106) and the output positive terminal (103); The zero-switching-loss operating states of the non-isolated DC boost topology circuit include: State 1, startup: Turn on the resonant switch (204) and the main switch (206). When the resonant capacitor (203) and the storage inductor (202) are charged to a certain amount of electricity, turn off the main switch (206) to make the storage inductor (202) resonate with the resonant capacitor (203). After the storage inductor (202) finishes reverse-charging the resonant capacitor (203), turn off the resonant switch, and let the resonant capacitor (203) and the storage inductor (202) continue to resonate until the storage inductor (202) charges the resonant capacitor (203) forward until the current of the storage inductor (202) is zero. The startup state is ready and prepares to enter State 2; State 2, storage inductor charging: Turn on the main switch (206) to charge the storage inductor (202). The current of the storage inductor (202) starts charging from 0, and the main switch (206) conducts with quasi-zero current. When the current of the storage inductor (202) reaches the target value, the storage inductor charging state ends and prepares to enter State 3; State 3, zero-current turn-off of the main switch: Turn on the resonant switch (204), transfer the current of the storage inductor (202) through the resonant capacitor (203) to make the current flowing through the main switch (206) in the forward direction zero, and turn off the main switch (206) to achieve zero-current turn-off. The zero-current turn-off state of the main switch ends and automatically enters State 4; State 4, reverse charging of the resonant capacitor: The energy storage inductor (202) continues to conduct to reverse charge the resonant capacitor (203) until the absolute value of the voltage of the resonant capacitor (203) reaches the target voltage. The output side diode (205) conducts and transfers the current flowing from the energy storage inductor (202) to the resonant capacitor (203). The forward current of the resonant switch (204) becomes 0, and the resonant switch (204) is turned off to achieve zero-current turn-off of the resonant switch. The reverse charging state of the resonant capacitor (203) ends and automatically enters State 5; State 5, continuous current boost: The energy storage inductor (202) continues to conduct and charge the output side voltage stabilizing capacitor (106) through the output side diode (205) until the current of the energy storage inductor (202) becomes 0. The reverse voltage of the output side diode (205) recovers, completing the continuous current boost state and automatically entering State 6; State 6, forward charging of the resonant capacitor: The energy storage inductor (202) resonates with the resonant capacitor (203) until the energy storage inductor (202) charges the resonant capacitor (203) forward to restore the voltage to the target voltage. The forward charging state of the resonant capacitor ends and waits to re-enter State 2.

2. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, wherein The main switch (206) is any one of IGBT, IGCT, or MosFET.

3. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, characterized in that, The resonant switch (204) is any one of MosFET, IGBT, or IGCT.

4. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, characterized in that, The input side voltage stabilizing capacitor (105) and the output side voltage stabilizing capacitor (106) are any one of polarized electrolytic capacitors, thin film capacitors, or supercapacitors.

5. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, characterized in that, The resonant capacitor (203) is a non-polar capacitor.

6. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, characterized in that The input positive terminal (101) and the input negative terminal (102) are respectively connected to the positive and negative electrodes of the photovoltaic module or the cascaded photovoltaic modules. The output positive terminal (103) and the output negative terminal (104) are respectively connected to the DC grid, or are connected to the DC grid after being cascaded with other non-isolated DC boost topology circuits, or are connected to a single-pole AC / DC inverter, or are connected to a single-pole AC / DC inverter after being cascaded with other non-isolated DC boost topology circuits.

7. The zero-switching-loss non-isolated DC boost topology circuit according to claim 1, wherein The target voltage transformation of the resonant capacitor (203) is the difference between the input voltage and the output voltage. The input voltage is the voltage between the input positive terminal (101) and the input negative terminal (102), and the output voltage is the voltage between the output positive terminal (103) and the output negative terminal (104).

8. A control method for a non-isolated DC boost topology circuit, characterized in that, Based on the zero-switching-loss non-isolated DC boost topology circuit according to any one of claims 1-7, the method includes: when the output voltage is greater than twice the input voltage, a soft-switching control method is adopted; when the output voltage is not higher than twice the input voltage, a hard-switching control method is adopted. At this time, the resonant switch (204) and the resonant capacitor (203) do not work, and the boost is achieved through the conduction and turn-off of the main switch (206).

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