High step-up ratio conversion circuit based on three-winding coupling inductor and control method thereof

Abstract

The invention relates to a high step-up ratio conversion circuit based on a three-winding coupling inductor and a control method thereof. The circuit comprises a switching tube S1, a coupling inductor L with three windings n1, n2 and n3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first diode D1, a second diode D2 and a third diode D3, and is used for converting the voltage of a direct-current power supply Vin into another direct-current voltage Vo and providing the direct-current voltage Vo to a load RL. The circuit structure provided by the invention has a higher step-up ratio under the same switch conduction duty ratio, only one full-control switch device is needed in the whole circuit, the structure is simple, and the cost is low.

Description

Technical Field

[0001] The present application relates to the technical field of high-step-up ratio DC converters, and in particular to a high-step-up ratio conversion circuit based on a three-winding coupled 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 practical applications, due to device voltage and current pressures and losses, the duty cycle of a boost converter is typically limited to 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, these power converters typically require the use of multiple fully controlled switching devices, which undoubtedly increases system complexity and cost.

[0003] The prior art discloses a dual-switch high-step-up ratio DC converter. It includes a DC input power supply, a first switching tube, a second switching tube, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, and a load. Compared to a conventional single-switch boost converter, the dual-switch DC converter of the present invention has a higher step-up ratio at the same duty cycle, and has low voltage stress on the switching tube, making it easy to control and very suitable for non-isolated renewable energy power generation systems. However, this method still requires the use of two fully controlled switching devices, which increases system complexity and cost. Summary of the Invention

[0004] Based on this, it is necessary to provide a high step-up ratio conversion circuit based on a three-winding coupled inductor with lower system complexity and cost to address the above technical issues, including:

[0005] The switch tube S1, the coupled inductor L having three windings n1, n2, and n3, the first capacitor C1, the second capacitor C2, the third capacitor C3, and the first diode D1, the second diode D2, and the third diode D3 are used to convert the voltage of the DC power supply Vin into another DC voltage Vo and provide it to the load RL;

[0006] The three windings n1, n2, and n3 of the coupled inductor L each have a first end and a second end, wherein the first end is a same-name end; the first end of winding n1 and the second end of winding n3 are simultaneously connected to the positive end of the input power supply Vin; the second end of winding n1 and the first end of winding n2 are simultaneously connected to the first end of switch tube S1; the second end of switch tube S1 is connected to the negative end of the input power supply; the first end of winding n3 is connected to the negative electrode of first capacitor C1; the positive electrode of first C1 is simultaneously connected to the cathode of first diode D1 and the anode of second diode D2; the cathode of second diode D2 is simultaneously connected to the anode of third diode D3 and the positive electrode of second capacitor C2; the negative electrode of second capacitor C2 is simultaneously connected to the second end of winding n2 and the anode of first diode D1; the cathode of third diode D3 is connected to the positive electrode of third capacitor C3 and serves as the positive output electrode; the negative electrode of third capacitor C3 is connected to the negative end of the input power supply and serves as the negative output electrode; the control end of switch tube S1 serves as the control input end of the conversion circuit and is connected to the PWM controller.

[0007] Furthermore, the input power supply Vin is a DC low-voltage power supply.

[0008] Furthermore, the switch tube S1 is a fully controlled switch tube.

[0009] Furthermore, it also includes a fourth capacitor C4, a fifth capacitor C5, and a fourth diode D4 and a fifth diode D5.

[0010] Furthermore, the negative electrode of the fourth capacitor C4 is connected to the anode of the second diode D2, and the positive electrode of the fourth capacitor C4 is simultaneously connected to the cathode of the fourth diode D4 and the anode of the fifth diode D5; the anode of the fourth diode D4 is simultaneously connected to the cathode of the second diode D2, the negative electrode of the fifth capacitor C5 and the positive electrode of the second capacitor C2; the cathode of the fifth diode D5 is simultaneously connected to the anode of the third diode D3 and the positive electrode of the fifth capacitor C5.

[0011] In addition, the present invention also provides a control method for a high-step-up ratio conversion circuit based on a three-winding coupled inductor, comprising:

[0012] When the circuit is working, the switch tube S1 operates in a mode where the switching frequency is fixed and the conduction duty cycle is adjustable;

[0013] When the switch tube S1 is turned on, the circuit is in the first working state;

[0014] When the switch tube S1 is disconnected, the circuit is in the second working state;

[0015] When the switch tube S1 is alternately in the on and off state at high frequency, the circuit operates alternately in the first working state and the second working state at high frequency, thereby achieving the voltage gain of the circuit.

[0016] Furthermore, the first working state is as follows: the switch tube S1 is turned on, the input power supply Vin is directly applied to both ends of the winding n1 of the coupled inductor L, and voltages k2×Vin and k3×Vin are induced at both ends of the windings n2 and n3, respectively, where k2=n2 / n1 and k3=n3 / n1 are the turns ratios of the windings n2 and n3 relative to the winding n1, respectively; at this time, the three windings of the coupled inductor L are connected in series with the first capacitor C1 and charge the second capacitor C2 through the second diode D2, and the voltage of the second capacitor C2 is Vc2=Vc1+(1+k2+k3)×Vin, where Vc1 is the voltage of the first capacitor C1; in this state, the load RL is powered by the third capacitor C3.

[0017] Furthermore, the second working state is: when the switch tube S1 is disconnected, the three windings of the coupled inductor L discharge to the first capacitor C1 through the first diode D1, and the sum of the voltages of the three windings is Vc1; at the same time, the input power supply Vin is connected in series with the windings n1, n2, and the second capacitor C2, and then charges the third capacitor C3 and the load RL simultaneously through the third diode D3, and the voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc1 × (1 + k2) / (1 + k2 + k3).

[0018] Furthermore, when the switch S1 operates alternately between the on and off states at high frequency, the voltage across the winding n1 switches between Vin and Vc1 / (1+k2+k3) at high frequency. When the switching frequency is fixed and the on-duty cycle is d, the voltage across the first capacitor C1 is obtained by the volt-second balance principle as Vc1=(1+k2+k3)×Vin×d / (1-d). The voltages of the second and third capacitors C2 and C3 are further expressed as:

[0019] Vc2=Vc1+(1+k2+k3)×Vin=Vin×(1+k2+k3) / (1-d)

[0020] Vc3=Vin+Vc2+Vc1×(1+k2) / (1+k2+k3)=Vin×[2+k3+k2×(1+d)] / (1-d)

[0021] The voltage across the third capacitor C3 is the output voltage of the conversion circuit, and the voltage gain of the circuit is G=Vo / Vin=Vc3 / Vin=[2+k3+k2×(1+d)] / (1-d).

[0022] Furthermore, when the switch tube S1 is turned on, the fifth capacitor C5 is connected in parallel with the fourth diode C4 through the second diode D2 and the fifth diode D5, and the voltages of the fifth capacitor C5 and the fourth capacitor C4 are the same, that is, Vc5=Vc4; when the switch tube S1 is turned off, the fourth capacitor C4 is connected in parallel with the second capacitor C2 through the first diode D1 and the fourth diode D4, so the voltages of the fifth capacitor C5, the fourth capacitor C4 and the second capacitor C2 are the same, that is,

[0023] Vc5=Vc4=Vc2=Vin×(1+k2+k3) / (1-d)

[0024] At the same time, the input power supply Vin is connected in series with the windings n1 and n2, and the second and fifth capacitors C2 and C5, and then charges the third capacitor C3 and the load RL simultaneously through the third diode D3. The voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc5 + Vc1 × (1 + k2) / (1 + k2 + k3) = Vin × [3 + 2k3 + k2 × (2 + d)] / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc3 / Vin = [3 + 2k3 + k2 × (2 + d)] / (1 - d).

[0025] The circuit structure provided by the present invention has a higher boost ratio under the same switch conduction duty cycle, and only one fully-controlled switch device is required in the entire circuit, which has a simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A high voltage step-up ratio conversion circuit diagram based on a three-winding coupled inductor in one embodiment is shown;

[0027] Figure 2 An improved circuit diagram of a high-voltage step-up ratio conversion based on a tapped inductor in one embodiment is provided;

[0028] Figure 3 1 is a flow chart of a method for controlling a high-voltage step-up ratio conversion circuit based on a three-winding coupled inductor according to an embodiment;

[0029] Figure 4 This is a first operating state diagram of a high step-up ratio conversion circuit based on a three-winding coupled inductor in one embodiment;

[0030] Figure 5 FIG2 is a second operating state diagram of a high step-up ratio conversion circuit based on a three-winding coupled inductor in one embodiment; DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0032] Example 1:

[0033] This embodiment provides Figure 1 A high step-up ratio conversion circuit based on a three-winding coupled inductor is shown, comprising:

[0034] The switch tube S1, the coupled inductor L having three windings n1, n2, and n3, the first capacitor C1, the second capacitor C2, the third capacitor C3, and the first diode D1, the second diode D2, and the third diode D3 are used to convert the voltage of the DC power supply Vin into another DC voltage Vo and provide it to the load RL;

[0035] The three windings n1, n2, and n3 of the coupled inductor L each have a first end and a second end, wherein the first end is a same-name end; the first end of winding n1 and the second end of winding n3 are simultaneously connected to the positive end of the input power supply Vin; the second end of winding n1 and the first end of winding n2 are simultaneously connected to the first end of switch tube S1; the second end of switch tube S1 is connected to the negative end of the input power supply; the first end of winding n3 is connected to the negative electrode of first capacitor C1; the positive electrode of first C1 is simultaneously connected to the cathode of first diode D1 and the anode of second diode D2; the cathode of second diode D2 is simultaneously connected to the anode of third diode D3 and the positive electrode of second capacitor C2; the negative electrode of second capacitor C2 is simultaneously connected to the second end of winding n2 and the anode of first diode D1; the cathode of third diode D3 is connected to the positive electrode of third capacitor C3 and serves as the positive output electrode; the negative electrode of third capacitor C3 is connected to the negative end of the input power supply and serves as the negative output electrode; the control end of switch tube S1 serves as the control input end of the conversion circuit and is connected to the PWM controller.

[0036] The circuit structure provided in this embodiment has a higher boost ratio under the same switch conduction duty cycle, and only one fully-controlled switch device is required in the entire circuit, which has a simple structure and low cost.

[0037] Example 2:

[0038] This embodiment further discloses the following on the basis of the first embodiment:

[0039] Furthermore, the input power supply Vin is a DC low-voltage power supply.

[0040] Furthermore, the switch tube S1 is a fully controlled switch tube.

[0041] Furthermore, it also includes a fourth capacitor C4, a fifth capacitor C5, and a fourth diode D4 and a fifth diode D5.

[0042] Furthermore, the negative electrode of the fourth capacitor C4 is connected to the anode of the second diode D2, and the positive electrode of the fourth capacitor C4 is simultaneously connected to the cathode of the fourth diode D4 and the anode of the fifth diode D5; the anode of the fourth diode D4 is simultaneously connected to the cathode of the second diode D2, the negative electrode of the fifth capacitor C5 and the positive electrode of the second capacitor C2; the cathode of the fifth diode D5 is simultaneously connected to the anode of the third diode D3 and the positive electrode of the fifth capacitor C5.

[0043] The circuit structure provided in this embodiment has a higher boost ratio under the same switch conduction duty cycle, and only one fully-controlled switch device is required in the entire circuit, which has a simple structure and low cost.

[0044] Example 3

[0045] This embodiment provides Figure 3 The control method of the high step-up ratio conversion circuit based on three-winding coupled inductors shown in the figure includes:

[0046] When the circuit is working, the switch tube S1 operates in a mode where the switching frequency is fixed and the conduction duty cycle is adjustable;

[0047] When the switch S1 is turned on, the circuit is in the state Figure 4 The first working state shown;

[0048] When the switch tube S1 is disconnected, the circuit is in the state of Figure 5 The second working state shown;

[0049] When the switch tube S1 is alternately in the on and off state at high frequency, the circuit operates alternately in the first working state and the second working state at high frequency, thereby achieving the voltage gain of the circuit.

[0050] Furthermore, the first working state is as follows: the switch tube S1 is turned on, the input power supply Vin is directly applied to both ends of the winding n1 of the coupled inductor L, and voltages k2×Vin and k3×Vin are induced at both ends of the windings n2 and n3, respectively, where k2=n2 / n1 and k3=n3 / n1 are the turns ratios of the windings n2 and n3 relative to the winding n1, respectively; at this time, the three windings of the coupled inductor L are connected in series with the first capacitor C1 and charge the second capacitor C2 through the second diode D2, and the voltage of the second capacitor C2 is Vc2=Vc1+(1+k2+k3)×Vin, where Vc1 is the voltage of the first capacitor C1; in this state, the load RL is powered by the third capacitor C3.

[0051] Furthermore, the second working state is: when the switch tube S1 is disconnected, the three windings of the coupled inductor L discharge to the first capacitor C1 through the first diode D1, and the sum of the voltages of the three windings is Vc1; at the same time, the input power supply Vin is connected in series with the windings n1, n2, and the second capacitor C2, and then charges the third capacitor C3 and the load RL simultaneously through the third diode D3, and the voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc1 × (1 + k2) / (1 + k2 + k3).

[0052] Furthermore, when the switch S1 operates alternately between the on and off states at high frequency, the voltage across the winding n1 switches between Vin and Vc1 / (1+k2+k3) at high frequency. When the switching frequency is fixed and the on-duty cycle is d, the voltage across the first capacitor C1 is obtained by the volt-second balance principle as Vc1=(1+k2+k3)×Vin×d / (1-d). The voltages of the second and third capacitors C2 and C3 are further expressed as:

[0053] Vc2=Vc1+(1+k2+k3)×Vin=Vin×(1+k2+k3) / (1-d)

[0054] Vc3=Vin+Vc2+Vc1×(1+k2) / (1+k2+k3)=Vin×[2+k3+k2×(1+d)] / (1-d)

[0055] The voltage across the third capacitor C3 is the output voltage of the conversion circuit, and the voltage gain of the circuit is G=Vo / Vin=Vc3 / Vin=[2+k3+k2×(1+d)] / (1-d).

[0056] The circuit structure provided in this embodiment has a higher boost ratio under the same switch conduction duty cycle, and only one fully-controlled switch device is required in the entire circuit, which has a simple structure and low cost.

[0057] Example 4:

[0058] This embodiment provides a control method for a high step-up ratio conversion circuit based on a three-winding coupled inductor, including: further, when the switch tube S1 is turned on, the fifth capacitor C5 is connected in parallel with the fourth diode C4 through the second diode D2 and the fifth diode D5, and the voltage of the fifth capacitor C5 and the fourth capacitor C4 are the same, that is, Vc5=Vc4; when the switch tube S1 is turned off, the fourth capacitor C4 is connected in parallel with the second capacitor C2 through the first diode D1 and the fourth diode D4, so that the voltage of the fifth capacitor C5, the fourth capacitor C4 and the second capacitor C2 are the same, that is,

[0059] Vc5=Vc4=Vc2=Vin×(1+k2+k3) / (1-d)

[0060] At the same time, the input power supply Vin is connected in series with the windings n1 and n2, and the second and fifth capacitors C2 and C5, and then charges the third capacitor C3 and the load RL simultaneously through the third diode D3. The voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc5 + Vc1 × (1 + k2) / (1 + k2 + k3) = Vin × [3 + 2k3 + k2 × (2 + d)] / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc3 / Vin = [3 + 2k3 + k2 × (2 + d)] / (1 - d).

[0061] The circuit structure provided in this embodiment has a higher boost ratio under the same switch conduction duty cycle, and only one fully-controlled switch device is required in the entire circuit, which has a simple structure and low cost.

Claims

1. A high step-up ratio conversion circuit based on a three-winding coupled inductor, characterized in that: include: The switch tube S1, the coupled inductor L having three windings n1, n2, and n3, the first capacitor C1, the second capacitor C2, the third capacitor C3, and the first diode D1, the second diode D2, and the third diode D3 are used to convert the voltage of the DC power supply Vin into another DC voltage Vo and provide it to the load RL; The three windings n1, n2, and n3 of the coupled inductor L each have a first end and a second end, wherein the first end is a same-name end; the first end of winding n1 and the second end of winding n3 are simultaneously connected to the positive end of the input power supply Vin; the second end of winding n1 and the first end of winding n2 are simultaneously connected to the first end of switch tube S1; the second end of switch tube S1 is connected to the negative end of the input power supply; the first end of winding n3 is connected to the negative electrode of first capacitor C1; the positive electrode of first C1 is simultaneously connected to the cathode of first diode D1 and the anode of second diode D2; the cathode of second diode D2 is simultaneously connected to the anode of third diode D3 and the positive electrode of second capacitor C2; the negative electrode of second capacitor C2 is simultaneously connected to the second end of winding n2 and the anode of first diode D1; the cathode of third diode D3 is connected to the positive electrode of third capacitor C3 and serves as the positive output electrode; the negative electrode of third capacitor C3 is connected to the negative end of the input power supply and serves as the negative output electrode; the control end of switch tube S1 serves as the control input end of the conversion circuit and is connected to the PWM controller.

2. The high step-up ratio conversion circuit based on three-winding coupled inductors according to claim 1, characterized in that: The input power supply Vin is a DC low voltage power supply.

3. The high step-up ratio conversion circuit based on three-winding coupled inductors according to claim 1, characterized in that: The switch tube S1 is a fully controlled switch tube.

4. The high step-up ratio conversion circuit based on three-winding coupled inductors according to claim 1, characterized in that: The system also includes a fourth capacitor C4, a fifth capacitor C5, a fourth diode D4, and a fifth diode D5.

5. The high step-up ratio conversion circuit based on three-winding coupled inductors according to claim 4, characterized in that: The negative electrode of the fourth capacitor C4 is connected to the anode of the second diode D2, and the positive electrode of the fourth capacitor C4 is simultaneously connected to the cathode of the fourth diode D4 and the anode of the fifth diode D5; the anode of the fourth diode D4 is simultaneously connected to the cathode of the second diode D2, the negative electrode of the fifth capacitor C5, and the positive electrode of the second capacitor C2; the cathode of the fifth diode D5 is simultaneously connected to the anode of the third diode D3 and the positive electrode of the fifth capacitor C5.

6. A control method for a high step-up ratio conversion circuit based on a three-winding coupled inductor according to any one of claims 1 to 5, characterized in that: include: When the circuit is working, the switch tube S1 operates in a mode where the switching frequency is fixed and the conduction duty cycle is adjustable; When the switch tube S1 is turned on, the circuit is in the first working state; When the switch tube S1 is disconnected, the circuit is in the second working state; When the switch tube S1 is alternately in the on and off state at high frequency, the circuit operates alternately in the first working state and the second working state at high frequency, thereby achieving the voltage gain of the circuit.

7. The method for controlling a high-voltage-step-up ratio conversion circuit based on a three-winding coupled inductor according to claim 6, wherein: In the first operating state, switch S1 is on, and the input power supply Vin is directly applied to both ends of winding n1 of the coupled inductor L. Voltages k2×Vin and k3×Vin are induced across windings n2 and n3, respectively, where k2=n2 / n1 and k3=n3 / n1 are the turns ratios of windings n2 and n3 relative to winding n1, respectively. At this time, the three windings of the coupled inductor L are connected in series with the first capacitor C1 and collectively charge the second capacitor C2 through the second diode D2. The voltage of the second capacitor C2 is Vc2=Vc1+(1+k2+k3)×Vin, where Vc1 is the voltage of the first capacitor C1. In this state, the load RL is powered by the third capacitor C3.

8. The method for controlling a high-voltage-step-up ratio conversion circuit based on a three-winding coupled inductor according to claim 6, wherein: In the second working state, when the switch S1 is disconnected, the three windings of the coupled inductor L discharge to the first capacitor C1 through the first diode D1, and the sum of the voltages of the three windings is Vc1. At the same time, the input power supply Vin is connected in series with the windings n1, n2, and the second capacitor C2, and then charges the third capacitor C3 and the load RL through the third diode D3. The voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc1 × (1 + k2) / (1 + k2 + k3).

9. The method for controlling a high-voltage-step-up ratio conversion circuit based on a three-winding coupled inductor according to claim 6, wherein: When the switch S1 operates alternately between the on and off states at high frequency, the voltage across the winding n1 switches between Vin and Vc1 / (1+k2+k3). When the switching frequency is fixed and the on-duty cycle is d, the voltage across the first capacitor C1 is Vc1 = (1+k2+k3) × Vin × d / (1-d) using the volt-second balance principle. The voltages across the second and third capacitors C2 and C3 are further expressed as: Vc2=Vc1+(1+k2+k3)×Vin=Vin×(1+k2+k3) / (1-d) Vc3=Vin+Vc2+Vc1×(1+k2) / (1+k2+k3)=Vin×[2+k3+k2×(1+d)] / (1-d) The voltage across the third capacitor C3 is the output voltage of the conversion circuit, and the voltage gain of the circuit is G=Vo / Vin=Vc3 / Vin=[2+k3+k2×(1+d)] / (1-d).

10. The method for controlling a high-voltage-step-up ratio conversion circuit based on a three-winding coupled inductor according to claim 6, wherein: When the switch tube S1 is turned on, the fifth capacitor C5 is connected in parallel with the fourth diode C4 through the second diode D2 and the fifth diode D5. The voltages of the fifth capacitor C5 and the fourth capacitor C4 are the same, that is, Vc5=Vc4; when the switch tube S1 is turned off, the fourth capacitor C4 is connected in parallel with the second capacitor C2 through the first diode D1 and the fourth diode D4. Therefore, the voltages of the fifth capacitor C5, the fourth capacitor C4 and the second capacitor C2 are the same, that is, Vc5=Vc4=Vc2=Vin×(1+k2+k3) / (1-d) At the same time, the input power supply Vin is connected in series with the windings n1 and n2, and the second and fifth capacitors C2 and C5, and then charges the third capacitor C3 and the load RL simultaneously through the third diode D3. The voltage of the third capacitor C3 is Vc3 = Vin + Vc2 + Vc5 + Vc1 × (1 + k2) / (1 + k2 + k3) = Vin × [3 + 2k3 + k2 × (2 + d)] / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc3 / Vin = [3 + 2k3 + k2 × (2 + d)] / (1 - d).

Images