High step-up ratio conversion circuit based on switched capacitor and switched inductor and control method of high step-up ratio conversion circuit

Abstract

The invention relates to the field of power electronic power conversion, and discloses a high step-up ratio conversion circuit based on a switched capacitor inductor and a control method thereof.The high step-up ratio conversion circuit based on the switched capacitor inductor comprises a first switched capacitor inductor unit and an output filtering and voltage stabilizing unit; the first switched capacitor and inductor unit is composed of a switching tube S1, a switching tube S2, a capacitor C1, a capacitor C2, an inductor L1, an inductor L2, a diode D1 and a diode D2; the output filtering voltage stabilizing unit is composed of an output diode Do and an output capacitor Co. The invention solves the problem that the prior art depends on a high-frequency transformer to realize a high step-up ratio, and has the characteristics of simple circuit and flexible structure.

Description

Technical Field

[0001] The present invention relates to the field of power electronic power conversion, and more specifically, to a high-step-up ratio conversion circuit based on a switched capacitor and inductor and a control method thereof. Background Art

[0002] With the development and popularization of distributed power generation systems such as photovoltaics and fuel cells, high-step-up ratio DC converters are gaining increasing attention. Theoretically, a sufficiently large duty cycle of a boost converter can achieve very high voltage gain. However, in practice, due to device voltage and current pressures and losses, the duty cycle of a boost converter typically does not exceed 0.8. Alternatively, high step-up ratios can be achieved using power conversion circuits containing high-turns-ratio high-frequency transformers, such as flyback, forward, and LLC resonant converters. However, for applications that do not require electrical isolation, the use of high-frequency transformers undoubtedly increases the difficulty and cost of system design.

[0003] The prior art provides a control method for a single-phase AC input adjustable DC regulated power supply, comprising a single-phase PWM rectifier circuit, a single-phase Buck-Boost inverter circuit, a single-phase bridge uncontrolled rectifier circuit, and a π-type RLC combination filter circuit connected in series. The control method calculates the inductor reference voltage uL_ref using a proportional complex integral control algorithm based on the inductor's reference current and actual inductor current. The method then calculates the duty cycle d of the corresponding power switch in the inverter circuit based on the inductor reference voltage uL_ref, the rectifier circuit's output DC voltage uDC, and the capacitor's actual voltage uC. The power switch is then controlled based on the duty cycle to ensure that the actual output voltage of the DC regulated power supply remains consistent with its reference output voltage.

[0004] However, the existing technology has the problem of relying on high-frequency transformers to achieve a high step-up ratio. Therefore, how to invent a high-gain boost converter with small size and low cost is a technical problem that urgently needs to be solved in this technical field. Summary of the Invention

[0005] In order to solve the problem of relying on high-frequency transformers to achieve high step-up ratio in the prior art, the present invention provides a high step-up ratio conversion circuit based on switched capacitors and inductors and a control method thereof, which has the characteristics of simple circuit and flexible structure.

[0006] In order to achieve the above-mentioned purpose of the present invention, the technical solutions adopted are as follows: A high voltage step-up ratio conversion circuit based on switched capacitor and inductor, comprising a first switched capacitor and inductor unit and an output filter and voltage stabilization unit; The first switched capacitor inductor unit is composed of a switch tube S1, a switch tube S2, a capacitor C1, a capacitor C2, an inductor L1, an inductor L2, a diode D1 and a diode D2; The output filter voltage stabilization unit is composed of an output diode Do and an output capacitor Co; The first end of the switch tube S1, the first end of the inductor L1 and the anode of the diode D1 are electrically connected to serve as the positive input end of the first switched capacitor-inductor unit; the cathode of the diode D1 is electrically connected to the positive electrode of the capacitor C1, serving as the positive output end of the first switched capacitor-inductor unit; the second end of the switch tube S1, the negative electrode of the capacitor C1 and the first end of the inductor L2 are electrically connected; the first end of the switch tube S2, the positive electrode of the capacitor C2 and the second end of the inductor L1 are electrically connected; the second end of the switch tube S2, the second end of the inductor L2 and the cathode of the diode D2 are electrically connected The anode of the diode D2 is electrically connected to the negative electrode of the capacitor C2, serving as the negative output terminal of the first switched capacitor inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the switched capacitor inductor unit, and its cathode is electrically connected to the positive electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the switched capacitor inductor unit; the positive input terminal and the negative input terminal of the switched capacitor inductor unit are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

[0007] Preferably, the device further comprises a second switched capacitor inductor unit, wherein the second switched capacitor inductor unit comprises a switch tube S3, a switch tube S4, a capacitor C3, a capacitor C4, an inductor L3, an inductor L4, a diode D3 and a diode D4; The first end of the switch tube S3, the first end of the inductor L3 and the anode of the diode D3 are electrically connected to serve as the positive input end of the second switched capacitor-inductor unit; the cathode of the diode D3 and the positive electrode of the capacitor C3 are electrically connected to serve as the positive output end of the second switched capacitor-inductor unit; the second end of the switch tube S3, the negative electrode of the capacitor C3 and the first end of the inductor L4 are electrically connected; the first end of the switch tube S4, the positive electrode of the capacitor C4 and the second end of the inductor L3 are electrically connected; the second end of the switch tube S4, the second end of the inductor L4 and the cathode of the diode D4 are electrically connected to serve as the negative input end of the second switched capacitor-inductor unit; The anode of the diode D4 is electrically connected to the negative electrode of the capacitor C4, serving as the negative output terminal of the second switched capacitor-inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the second switched capacitor-inductor unit, and the cathode thereof is electrically connected to the positive electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the second switched capacitor-inductor unit; the positive input terminal and the negative input terminal of the second switched capacitor-inductor unit are electrically connected to the positive output terminal and the negative output terminal of the first switched capacitor-inductor unit, respectively; the first positive input terminal and the negative input terminal are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

[0008] Furthermore, the switch tubes S1, S2, S3, and S4 are either MOSFET or IGBT fully controlled switches.

[0009] Furthermore, the switches S1 , S2 , S3 , and S4 are all controlled to be turned on and off simultaneously with a duty cycle d, and the circuit is configured to provide a relationship between the output voltage Vo and the input voltage Vin that is related to the duty cycle d.

[0010] A control method for a high-voltage step-up ratio conversion circuit based on a switched capacitor-inductor circuit comprises the following steps: The circuit switches between on and off phases through the switch tubes S1 and S2; By setting the switching frequency, the on and off states can be alternately operated; By setting the switch on-duty cycle d, the set voltage gain is achieved.

[0011] Preferably, the conduction duty cycle d of the switching tubes S1, S2, S3 and S4 varies between 0 and 1.

[0012] Furthermore, if the high step-up ratio conversion circuit only includes the first switched capacitor-inductor unit, when the switches S1 and S2 are turned on at the same time, the input power supply voltage Vin is simultaneously applied to both ends of the inductors L1 and L2, and is connected in series with the capacitors C1 and C2, and then charges the capacitor Co through the diode Do. The output voltage is Vo=Vin+Vc1+Vc2, where Vc1 and Vc2 are the voltages of the capacitors C1 and C2 respectively; when the switches S1 and S2 are turned off at the same time, the input power supply Vin and the inductor L1 charge the capacitor C2, and the input power supply Vin and the inductor L2 charge the capacitor C1.

[0013] Furthermore, the relationship between the voltage gain G of the circuit and the on-duty cycle d of the switches S1 and S2 is G=Vo / Vin=(3-d) / (1-d).

[0014] Furthermore, if the high step-up ratio conversion circuit includes a first and a second switched capacitor-inductor unit, when switches S1, S2, S3, and S4 are turned on, the capacitors of the two switched capacitor-inductor units are connected in series with the input power supply and then charge capacitor Co through diode Do. All output voltages are the sum of the voltages of the capacitors in the switched capacitor-inductor units under the input power supply Vin, that is, Vo = Vin + Vc1 + Vc2 + Vc3 + Vc4, where Vc1 to Vc4 are the voltages of capacitors C1 to C4, respectively. The input power supply voltage Vin is simultaneously applied to both ends of inductors L1 and L2 of the first switched capacitor-inductor unit, and inductors L3 and L4 of the second switched capacitor-inductor unit are both charged by the total voltage of the capacitors C1 and C2 in the first switched capacitor-inductor unit connected in series with the input power supply. When all switching tubes are turned off, in the capacitor-inductor unit, the inductor L1 is connected in series with the input power supply Vin to charge the capacitor C2 together, and the inductor L2 is connected in series with the input power supply Vin to charge the capacitor C1 together; the inductor L3 is connected in series with the input power supply Vin to charge the capacitor C4 together, and the inductor L4 is connected in series with the input power supply Vin to charge the capacitor C3 together.

[0015] Furthermore, the switches S1, S2, S3, and S4 are all controlled to be turned on and off simultaneously with a duty cycle d, and the circuit is configured to provide an output voltage Vo and an input voltage Vin having a relationship of: Vo=Vin+Vc1+Vc2+Vc3+Vc4=Vin×[1+4 / (1-d) 2 ] Where, Vc1=Vc2=Vin / (1-d), Vc3=Vc4=Vin×(1+d) / (1-d) 2 ; The voltage gain of the circuit is G=Vo / Vin=1+4 / (1-d) 2 .

[0016] The beneficial effects of the present invention are as follows: The present invention discloses a high step-up ratio conversion circuit based on switched capacitors and inductors. Through a unique circuit design, a higher step-up ratio is achieved under the same switch conduction duty cycle, and a transformer is saved. The circuit is simple and the structure is flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a schematic diagram of a high voltage step-up ratio conversion circuit based on switched capacitors and inductors according to the first embodiment of the present invention.

[0018] Figure 2 1 is a schematic diagram of a switch-on state of a high voltage step-up ratio conversion circuit based on a switched capacitor and inductor according to the first embodiment of the present invention.

[0019] Figure 3 1 is a schematic diagram of a switch-off state of a high voltage step-up ratio conversion circuit based on a switched capacitor and inductor according to the first embodiment of the present invention.

[0020] Figure 4 1 is a schematic diagram of a high voltage step-up ratio conversion circuit based on switched capacitors and inductors according to the second embodiment of the present invention.

[0021] Figure 5 1 is a schematic diagram of the switch conduction state of a high voltage step-up ratio conversion circuit based on switched capacitors and inductors according to the second embodiment of the present invention.

[0022] Figure 61 is a schematic diagram of a switch-off state of a high voltage step-up ratio conversion circuit based on a switched capacitor and inductor according to a second embodiment of the present invention.

[0023] Figure 7 It is a flow chart of a control method of a high voltage step-up ratio conversion circuit based on switched capacitors and inductors according to the present invention.

[0024] Figure 8 The present invention is a schematic diagram showing the relationship between the boost ratio G and the switch conduction duty cycle d during operation of a control method for a high boost ratio conversion circuit based on a switched capacitor and inductor. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1 like Figure 1 As shown, a high step-up ratio conversion circuit based on switched capacitor and inductor includes a first switched capacitor and inductor unit and an output filter and voltage stabilization unit; The first switched capacitor inductor unit is composed of a switch tube S1, a switch tube S2, a capacitor C1, a capacitor C2, an inductor L1, an inductor L2, a diode D1 and a diode D2; The output filter voltage stabilization unit is composed of an output diode Do and an output capacitor Co; The first end of the switch tube S1, the first end of the inductor L1 and the anode of the diode D1 are electrically connected to serve as the positive input end of the first switched capacitor-inductor unit; the cathode of the diode D1 is electrically connected to the positive electrode of the capacitor C1, serving as the positive output end of the first switched capacitor-inductor unit; the second end of the switch tube S1, the negative electrode of the capacitor C1 and the first end of the inductor L2 are electrically connected; the first end of the switch tube S2, the positive electrode of the capacitor C2 and the second end of the inductor L1 are electrically connected; the second end of the switch tube S2, the second end of the inductor L2 and the cathode of the diode D2 are electrically connected to serve as the first switched capacitor-inductor unit. The anode of the diode D2 is electrically connected to the negative electrode of the capacitor C2, serving as the negative output terminal of the first switched capacitor inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the switched capacitor inductor unit, and its cathode is electrically connected to the positive electrode of the output capacitor Co, and the negative output terminal of the switched capacitor inductor unit is electrically connected to the negative electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the switched capacitor inductor unit; the positive input terminal and the negative input terminal of the switched capacitor inductor unit are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

[0027] In a specific embodiment, the switches S1 and S2 are controlled to be turned on and off simultaneously with a duty cycle d, thereby achieving alternating operation in an on and off state.

[0028] In a specific embodiment, Figure 2 As shown in the figure, when the switches S1 and S2 are turned on, the input power supply voltage Vin is applied to both ends of the inductors L1 and L2 at the same time, and is connected in series with the capacitors C1 and C2, and then charges the capacitor Co through the diode Do. The output voltage is Vo=Vin+Vc1+Vc2, where Vc1 and Vc2 are the voltages of the capacitors C1 and C2 respectively; like Figure 3 As shown, when the switches S1 and S2 are turned off, the input power supply Vin and the inductor L1 charge the capacitor C2; at the same time, the input power supply Vin and the inductor L2 charge the capacitor C1.

[0029] In a specific embodiment, the switches S1 and S2 are both controlled to be turned on and off simultaneously with a duty cycle d, and the circuit is configured to provide an output voltage Vo having a relationship with the input voltage Vin of Vo = Vin × (3 - d) / (1 - d).

[0030] Example 2 More specifically, Figure 4 As shown, it also includes a second switched capacitor inductor unit, and the second switched capacitor inductor unit includes a switch tube S3, a switch tube S4, a capacitor C3, a capacitor C4, an inductor L3, an inductor L4, a diode D3 and a diode D4; The first end of the switch tube S3, the first end of the inductor L3 and the anode of the diode D3 are electrically connected to serve as the positive input end of the second switched capacitor-inductor unit; the cathode of the diode D3 and the positive electrode of the capacitor C3 are electrically connected to serve as the positive output end of the second switched capacitor-inductor unit; the second end of the switch tube S3, the negative electrode of the capacitor C3 and the first end of the inductor L4 are electrically connected; the first end of the switch tube S4, the positive electrode of the capacitor C4 and the second end of the inductor L3 are electrically connected; the second end of the switch tube S4, the second end of the inductor L4 and the cathode of the diode D4 are electrically connected to serve as the negative input end of the second switched capacitor-inductor unit; The anode of the diode D4 is electrically connected to the negative electrode of the capacitor C4, serving as the negative output terminal of the second switched capacitor-inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the second switched capacitor-inductor unit, and the cathode thereof is electrically connected to the positive electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the second switched capacitor-inductor unit; the positive input terminal and the negative input terminal of the second switched capacitor-inductor unit are electrically connected to the positive output terminal and the negative output terminal of the first switched capacitor-inductor unit, respectively; the first positive input terminal and the negative input terminal are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

[0031] In a specific embodiment, the switch tubes S1, S2, S3, and S4 are fully controlled switches such as MOSFET or IGBT.

[0032] In a specific embodiment, Figure 5 As shown, when the switches S1, S2, S3, and S4 are turned on, the capacitors of the two switched capacitor-inductor units are connected in series with the input power supply and then charge the capacitor Co through the diode Do. All output voltages are the sum of the voltages of the capacitors in the switched capacitor-inductor units under the input power supply Vin, that is, Vo=Vin+Vc1+Vc2+Vc3+Vc4, where Vc1 to Vc4 are the voltages of capacitors C1 to C4 respectively. The input power supply voltage Vin is simultaneously applied to the inductors L1 and L2 of the first switched capacitor-inductor unit, and the inductors L3 and L4 of the second switched capacitor-inductor unit are both charged by the total voltage of the capacitors C1 and C2 in the first switched capacitor-inductor unit connected in series with the input power supply. like Figure 6 As shown, when all the switch tubes are turned off, in the capacitor-inductor unit, the inductor L1 is connected in series with the input power supply Vin to charge the capacitor C2 together, and the inductor L2 is connected in series with the input power supply Vin to charge the capacitor C1 together; the inductor L3 is connected in series with the input power supply Vin to charge the capacitor C4 together, and the inductor L4 is connected in series with the input power supply Vin to charge the capacitor C3 together.

[0033] In a specific embodiment, the switches S1, S2, S3, and S4 are all controlled to be turned on and off simultaneously with a duty cycle d. The circuit is configured to provide an output voltage Vo and an input voltage Vin having a relationship of: Vo=Vin+Vc1+Vc2+Vc3+Vc4=Vin×[1+4 / (1-d) 2 ] Where, Vc1=Vc2=Vin / (1-d), Vc3=Vc4=Vin×(1+d) / (1-d) 2 .

[0034] Example 3 Figure 7 As shown, a control method for a high step-up ratio conversion circuit based on a switched capacitor-inductor circuit includes the following steps: The circuit switches between on and off phases through the switch tubes S1 and S2; In the on-phase, the second terminal of the switch S1 and the first terminal of the switch S2 are turned on, and the input power supply voltage Vin is applied to both ends of the inductors L1 and L2 at the same time, and is connected in series with the capacitors C1 and C2, and then charges the capacitor Co through the diode Do; In the off phase, the first terminal of the switch tube S1 and the second terminal of the switch tube S2 are turned on, and the input power supply Vin and the inductor L1 charge the capacitor C2. At the same time, the input power supply Vin and the inductor L2 charge the capacitor C1. By setting the switch on-duty cycle d, the on-state and off-state are alternately operated to achieve the set voltage gain.

[0035] In a specific embodiment, when setting the control circuit, the positive input terminal and the negative input terminal are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is set in parallel with Co.

[0036] In a specific embodiment, the switches S1 and S2 are controlled to be turned on and off simultaneously with a duty cycle d, thereby achieving alternating operation in an on and off state.

[0037] In a specific embodiment, if the high-step-up ratio converter circuit includes only the first switched capacitor-inductor unit, when switches S1 and S2 are simultaneously turned on, the input power supply voltage Vin is simultaneously applied to both ends of inductors L1 and L2, and then connected in series with capacitors C1 and C2, and then charges capacitor Co through diode Do. The output voltage is Vo=Vin+Vc1+Vc2, where Vc1 and Vc2 are the voltages of capacitors C1 and C2, respectively. When the switches S1 and S2 are turned off, the input power supply Vin and the inductor L1 charge the capacitor C2; at the same time, the input power supply Vin and the inductor L2 charge the capacitor C1.

[0038] The voltage gain of the circuit is G=Vo / Vin=(3-d) / (1-d).

[0039] In a specific embodiment, if the high step-up ratio conversion circuit includes first and second switched capacitor-inductor units, when switches S1, S2, S3, and S4 are turned on, the capacitors of the two switched capacitor-inductor units are connected in series with the input power supply and then charge capacitor Co through diode Do. All output voltages are the sum of the voltages of the capacitors in the switched capacitor-inductor units under the input power supply Vin, that is, Vo=Vin+Vc1+Vc2+Vc3+Vc4, where Vc1-Vc4 are the voltages of capacitors C1-C4, respectively. The input power supply voltage Vin is simultaneously applied to the inductors L1 and L2 of the first switched capacitor-inductor unit, and the inductors L3 and L4 of the second switched capacitor-inductor unit are both charged by the total voltage of the capacitors C1 and C2 in the first switched capacitor-inductor unit connected in series with the input power supply. When all switching tubes are turned off, in the capacitor-inductor unit, the inductor L1 is connected in series with the input power supply Vin to charge the capacitor C2 together, and the inductor L2 is connected in series with the input power supply Vin to charge the capacitor C1 together; the inductor L3 is connected in series with the input power supply Vin to charge the capacitor C4 together, and the inductor L4 is connected in series with the input power supply Vin to charge the capacitor C3 together.

[0040] In a specific embodiment, the switches S1, S2, S3, and S4 are all controlled to be turned on and off simultaneously with a duty cycle d. The circuit is configured to provide an output voltage Vo and an input voltage Vin having a relationship of: Vo=Vin+Vc1+Vc2+Vc3+Vc4=Vin×[1+4 / (1-d) 2 ] Where, Vc1=Vc2=Vin / (1-d), Vc3=Vc4=Vin×(1+d) / (1-d) 2 ; The voltage gain of the circuit is G=Vo / Vin=1+4 / (1-d) 2 .

[0041] like Figure 8 As shown, regardless of the specific circuit design, the boost ratio G increases with the increase of the switch conduction duty cycle d and also increases with the increase of the number of switch capacitor and inductor units. It can be seen that the conversion circuit proposed by the present invention has a high boost ratio.

[0042] Obviously, the above embodiments of the present invention are merely examples for the purpose of illustrating the present invention, and are not intended to limit the embodiments of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A high step-up ratio conversion circuit based on switched capacitor and inductor, characterized in that: It includes a first switching capacitor inductor unit and an output filter voltage stabilizing unit; The first switched capacitor inductor unit is composed of a switch tube S1, a switch tube S2, a capacitor C1, a capacitor C2, an inductor L1, an inductor L2, a diode D1 and a diode D2; The output filter voltage stabilization unit is composed of an output diode Do and an output capacitor Co; The first end of the switch tube S1, the first end of the inductor L1 and the anode of the diode D1 are electrically connected to serve as the positive input end of the first switched capacitor-inductor unit; the cathode of the diode D1 is electrically connected to the positive electrode of the capacitor C1, serving as the positive output end of the first switched capacitor-inductor unit; the second end of the switch tube S1, the negative electrode of the capacitor C1 and the first end of the inductor L2 are electrically connected; the first end of the switch tube S2, the positive electrode of the capacitor C2 and the second end of the inductor L1 are electrically connected; the second end of the switch tube S2, the second end of the inductor L2 and the cathode of the diode D2 are electrically connected The anode of the diode D2 is electrically connected to the negative electrode of the capacitor C2, serving as the negative output terminal of the first switched capacitor inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the switched capacitor inductor unit, and its cathode is electrically connected to the positive electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the switched capacitor inductor unit; the positive input terminal and the negative input terminal of the switched capacitor inductor unit are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

2. The high step-up ratio conversion circuit based on switched capacitor and inductor according to claim 1, characterized in that: The device further includes a second switched capacitor-inductor unit, wherein the second switched capacitor-inductor unit includes a switch tube S3, a switch tube S4, a capacitor C3, a capacitor C4, an inductor L3, an inductor L4, a diode D3, and a diode D4; The first end of the switch tube S3, the first end of the inductor L3 and the anode of the diode D3 are electrically connected to serve as the positive input end of the second switched capacitor-inductor unit; the cathode of the diode D3 and the positive electrode of the capacitor C3 are electrically connected to serve as the positive output end of the second switched capacitor-inductor unit; the second end of the switch tube S3, the negative electrode of the capacitor C3 and the first end of the inductor L4 are electrically connected; the first end of the switch tube S4, the positive electrode of the capacitor C4 and the second end of the inductor L3 are electrically connected; the second end of the switch tube S4, the second end of the inductor L4 and the cathode of the diode D4 are electrically connected to serve as the negative input end of the second switched capacitor-inductor unit; The anode of the tube D4 is electrically connected to the negative electrode of the capacitor C4, serving as the negative output terminal of the second switched capacitor-inductor unit; the anode of the output diode Do is electrically connected to the positive output terminal of the second switched capacitor-inductor unit, and the cathode thereof is electrically connected to the positive electrode of the output capacitor Co; the negative electrode of the output capacitor Co is electrically connected to the negative output terminal of the second switched capacitor-inductor unit; the positive input terminal and the negative input terminal of the second switched capacitor-inductor unit are electrically connected to the positive output terminal and the negative output terminal of the first switched capacitor-inductor unit, respectively; the first positive input terminal and the negative input terminal are electrically connected to the positive electrode and the negative electrode of the input DC power supply Vin, respectively, and the load Ro is connected in parallel with Co.

3. The high voltage step-up ratio conversion circuit based on switched capacitor and inductor according to claim 2, characterized in that: The switch tubes S1, S2, S3 and S4 are either MOSFET or IGBT fully controlled switches.

4. The high voltage step-up ratio conversion circuit based on switched capacitor and inductor according to claim 3, characterized in that: The switch tubes S1, S2, S3, and S4 are all controlled by a pulse width signal with a duty cycle d, so that they are turned on and off at the same time. The circuit is configured to provide a relationship between the output voltage Vo and the input voltage Vin that is related to the duty cycle d of the pulse width signal.

5. A control method for a high-step-up ratio conversion circuit based on a switched capacitor-inductor, characterized in that: The following steps are involved: The circuit switches between on and off phases through the switch tubes S1 and S2; By setting the switching frequency, the on and off states can be alternately operated; By setting the switch on-duty cycle d, the set voltage gain is achieved.

6. The control method according to claim 5, characterized in that: The on-duty ratio d of the switching tubes S1 , S2 , S3 and S4 varies between 0 and 1.

7. The control method according to claim 6, characterized in that: If the high step-up ratio conversion circuit only includes the first switched capacitor-inductor unit, when the switches S1 and S2 are turned on at the same time, the input power supply voltage Vin is applied to both ends of the inductors L1 and L2 at the same time, and is connected in series with the capacitors C1 and C2, and then charges the capacitor Co through the diode Do. The output voltage is Vo=Vin+Vc1+Vc2, where Vc1 and Vc2 are the voltages of the capacitors C1 and C2 respectively; when the switches S1 and S2 are turned off at the same time, the input power supply Vin and the inductor L1 charge the capacitor C2, and the input power supply Vin and the inductor L2 charge the capacitor C1.

8. The control method according to claim 7, characterized in that: The relationship between the voltage gain G of the circuit and the on-duty cycle d of the switches S1 and S2 is G=Vo / Vin=(3-d) / (1-d).

9. The control method according to claim 6, wherein: If a high-step-up ratio converter circuit includes first and second switched capacitor-inductor units, when switches S1, S2, S3, and S4 are simultaneously turned on, the capacitors of the two switched capacitor-inductor units are connected in series with the input power supply and then charge capacitor Co through diode Do. Therefore, the output voltage is the sum of the voltages of the capacitors in the switched capacitor-inductor units under the input power supply Vin, i.e., Vo = Vin + Vc1 + Vc2 + Vc3 + Vc4, where Vc1 to Vc4 are the voltages of capacitors C1 to C4, respectively. The input power supply voltage Vin is simultaneously applied to inductors L1 and L2 of the first switched capacitor-inductor unit, and inductors L3 and L4 of the second switched capacitor-inductor unit are both charged by the total voltage of the capacitors C1 and C2 in the first switched capacitor-inductor unit connected in series with the input power supply. When the switches S1, S2, S3, and S4 are turned off at the same time, in the capacitor-inductor unit, the inductor L1 is connected in series with the input power supply Vin to charge the capacitor C2, and the inductor L2 is connected in series with the input power supply Vin to charge the capacitor C1; the inductor L3 is connected in series with the input power supply Vin to charge the capacitor C4, and the inductor L4 is connected in series with the input power supply Vin to charge the capacitor C3.

10. The control method according to claim 9, characterized in that: The switches S1, S2, S3, and S4 are all controlled to be turned on and off simultaneously with a duty cycle d. The circuit is configured to provide an output voltage Vo and an input voltage Vin having a relationship of: Vo=Vin+Vc1+Vc2+Vc3+Vc4=Vin×[1+4 / (1-d) 2 ] Where, Vc1=Vc2=Vin / (1-d), Vc3=Vc4=Vin×(1+d) / (1-d) 2 ; The voltage gain of the circuit is G=Vo / Vin=1+4 / (1-d) 2 .

Images