Tap inductor-based high step-up ratio conversion circuit and control method thereof

Abstract

The invention relates to a high step-up ratio conversion circuit based on a tap inductor and a control method thereof. The circuit comprises an input voltage source Vin, a load RL, a switching tube S1, a tap inductor n1n2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4. 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 tapped 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 tapped inductor with lower system complexity and cost to address the above technical issues, including:

[0005] Input voltage source Vin, load RL, switch tube S1, tap inductor n1n2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first diode D1, second diode D2, third diode D3 and fourth diode D4;

[0006] The tapped inductor n1n2 is composed of a coil continuously wound on the same magnetic core, the coil having an input end, an output end and a tap end, wherein the number of turns of the coil between the input end and the tap end is n1, the number of turns of the coil between the tap end and the output end is n2, and the turns ratio n2 / n1=n.

[0007] The input end of the tapped inductor n1n2 and the negative electrode of the first capacitor C1 are simultaneously connected to the positive end of the input voltage source Vin; the tap end of the tapped inductor n1n2 is connected to the first end of the switch tube S1 and the anode of the first diode D1; the second end of the switch tube S1 is connected to the negative end of the input voltage source Vin; the cathode of the first diode D1 is connected to the anode of the second diode D2 and the positive electrode of the second capacitor C2; the cathode of the second diode D2 is connected to the anode of the third diode D3 and the positive electrode of the first capacitor C1; the cathode of the third diode D3 is connected to the anode of the fourth diode D4 and the positive electrode of the third capacitor C3; the negative electrodes of the second capacitor C2 and the third capacitor C3 are simultaneously connected to the output end of the tapped inductor n1n2; the cathode of the fourth diode D4 is connected to the positive electrode of the fourth capacitor C4 and serves as the output positive electrode; the negative electrode of the fourth capacitor C4 is connected to the negative end of the input voltage source Vin and serves as the output negative electrode; the control end of the switch tube S1 serves as the control input end of the conversion circuit and is connected to the PWM controller.

[0008] Furthermore, the input voltage source Vin is a DC low voltage power supply;

[0009] Furthermore, the switch tube S1 is a fully controlled switch tube.

[0010] Furthermore, it also includes a fifth capacitor C5, a sixth capacitor C6, a fifth diode D5 and a sixth diode D6.

[0011] Furthermore, the negative electrode of the fifth capacitor C5 is connected to the anode of the third diode D3, and the positive electrode of the fifth capacitor C5 is simultaneously connected to the cathode of the fifth diode D5 and the anode of the sixth diode D6; the anode of the fifth diode D5 is simultaneously connected to the cathode of the third diode D3 and the negative electrode of the sixth capacitor C6; the cathode of the sixth diode D6 is simultaneously connected to the anode of the fourth diode D4 and the positive electrode of the sixth capacitor C6.

[0012] In addition, the present invention further provides a method for controlling a high-voltage-boosting-ratio conversion circuit based on a tapped inductor according to claim 1, characterized in that it includes:

[0013] 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;

[0014] When the switch tube S1 is turned on, the circuit is in the first working state;

[0015] When the switch tube S1 is disconnected, the circuit is in the second working state;

[0016] 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.

[0017] Furthermore, the first working state is: when the switch tube S1 is turned on, the input voltage source Vin is directly applied to the two ends of the coil winding n1 of the tapped inductor n1n2, and a voltage n×Vin is induced at the two ends of the coil winding n2 and the second capacitor C2 is charged through the first diode D1, and the voltage of the second capacitor C2 is Vc2=n×Vin; all the coil windings of the tapped inductor n1n2 are connected in series with the first capacitor C1 and then charged to the capacitor C3 through the third diode D3, and the voltage of the third capacitor C3 is Vc3=Vc1+(1+n)×Vin, where Vc1 is the voltage of the first capacitor C1. In this state, the load RL is powered by the fourth capacitor C4.

[0018] Furthermore, the second working state is: when the switch tube S1 is disconnected, all the coil windings of the tapped inductor n1n2 are connected in series with the second capacitor C2 and then discharge to the first capacitor C1 through the diode D2. The total voltage of the tapped inductor is Vc1-Vc2, and the voltage on the coil winding n1 of the tapped inductor n1n2 is (Vc1-Vc2) / (1+n)=(Vc1-n×Vin) / (1+n); at the same time, the input voltage source Vin is connected in series with all the coil windings of the tapped inductor n1n2 and the third capacitor C3 and then charges the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4=Vin+Vc3+(Vc1-Vc2).

[0019] Furthermore, when the switch tube S1 operates alternately between the on and off states at high frequency, the voltage across the winding n1 switches between Vin and (Vc1-n×Vin) / (1+n) at high frequency. When the switching frequency is fixed and the on-duty cycle is d, using the volt-second balance principle, the voltage across the first capacitor C1 is Vc1=Vin×(d+n) / (1-d). The voltages across the third capacitor C3 and the fourth capacitor C4 are expressed as

[0020] Vc3=Vc1+(1+n)×Vin=Vin×(1+2n-nd) / (1-d)

[0021] Vc4=Vin+Vc3+(Vc1-Vc2)=Vin×2×(1+n) / (1-d)

[0022] The voltage across the fourth capacitor C4 is the output voltage, and the voltage gain is G=Vo / Vin=Vc4 / Vin=2×(1+n) / (1−d).

[0023] In addition, the present invention also provides a high-step-up ratio conversion circuit control method based on a tapped inductor, which is characterized in that:

[0024] When the switch tube S1 is turned on, the sixth capacitor C6 is connected in parallel with the fifth diode C5 through the third diode D3 and the sixth diode D6, so Vc5=Vc6; when the switch tube S1 is turned off, the first capacitor C1 and all the windings of the tapped inductor and the third capacitor C3 are connected in series and then charge the fifth capacitor C5 through the fifth diode D5. The voltage of the fifth capacitor C5 and the sixth capacitor C6 is

[0025] Vc5=Vc6=Vc3-Vc2=Vin×(1+n) / (1-d)

[0026] At the same time, the input voltage source Vin, the third capacitor C3, and the sixth capacitor C6 are connected in series and charge the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4 = Vin + Vc3 + Vc6 + (Vc1 - Vc2) = Vin × 3 × (1 + n) / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc4 / Vin = 3 × (1 + n) / (1 - d).

[0027] 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

[0028] Figure 1 A high-voltage step-up ratio conversion circuit diagram based on a tapped inductor in one embodiment;

[0029] Figure 2 An improved circuit diagram of a high-voltage step-up ratio conversion based on a tapped inductor in one embodiment is provided;

[0030] Figure 3 1 is a flow chart of a method for controlling a high-step-up ratio conversion circuit based on a tapped inductor in one embodiment;

[0031] Figure 4 FIG1 is a first operating state diagram of a high voltage step-up ratio conversion circuit based on a tapped inductor in one embodiment;

[0032] Figure 5 FIG2 is a second operating state diagram of a high voltage step-up ratio conversion circuit based on a tapped inductor in one embodiment; DETAILED DESCRIPTION

[0033] 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.

[0034] Example 1:

[0035] This embodiment provides Figure 1 A high step-up ratio conversion circuit based on a tapped inductor is shown, comprising:

[0036] Input voltage source Vin, load RL, switch tube S1, tap inductor n1n2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first diode D1, second diode D2, third diode D3 and fourth diode D4;

[0037] The tapped inductor n1n2 is composed of a coil continuously wound on the same magnetic core, the coil having an input end, an output end and a tap end, wherein the number of turns of the coil between the input end and the tap end is n1, the number of turns of the coil between the tap end and the output end is n2, and the turns ratio n2 / n1=n.

[0038] The input end of the tapped inductor n1n2 and the negative electrode of the first capacitor C1 are simultaneously connected to the positive end of the input voltage source Vin; the tap end of the tapped inductor n1n2 is connected to the first end of the switch tube S1 and the anode of the first diode D1; the second end of the switch tube S1 is connected to the negative end of the input voltage source Vin; the cathode of the first diode D1 is connected to the anode of the second diode D2 and the positive electrode of the second capacitor C2; the cathode of the second diode D2 is connected to the anode of the third diode D3 and the positive electrode of the first capacitor C1; the cathode of the third diode D3 is connected to the anode of the fourth diode D4 and the positive electrode of the third capacitor C3; the negative electrodes of the second capacitor C2 and the third capacitor C3 are simultaneously connected to the output end of the tapped inductor n1n2; the cathode of the fourth diode D4 is connected to the positive electrode of the fourth capacitor C4 and serves as the output positive electrode; the negative electrode of the fourth capacitor C4 is connected to the negative end of the input voltage source Vin and serves as the output negative electrode; the control end of the switch tube S1 serves as the control input end of the conversion circuit and is connected to the PWM controller.

[0039] 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.

[0040] Example 2:

[0041] This embodiment further discloses the following on the basis of the first embodiment:

[0042] Furthermore, the input voltage source Vin is a DC low-voltage power supply, and the switch tube S1 is a fully controlled switch tube.

[0043] Furthermore, the tapped inductor n1n2 is composed of a coil continuously wound on the same magnetic core, the coil having an input end, an output end and a tap end, wherein the number of turns of the coil between the input end and the tap end is n1, the number of turns of the coil between the tap end and the output end is n2, and the turns ratio n2 / n1=n.

[0044] Furthermore, it also includes a fifth capacitor C5, a sixth capacitor C6, a fifth diode D5 and a sixth diode D6.

[0045] Furthermore, if Figure 2 The cathode of the fifth capacitor C5 is connected to the anode of the third diode D3, and the anode of the fifth capacitor C5 is connected to the cathode of the fifth diode D5 and the anode of the sixth diode D6; the anode of the fifth diode D5 is connected to the cathode of the third diode D3 and the cathode of the sixth capacitor C6; the cathode of the sixth diode D6 is connected to the anode of the fourth diode D4 and the positive electrode of the sixth capacitor C6.

[0046] 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.

[0047] Example 3

[0048] This embodiment provides Figure 3 The control method of the high-step-up ratio conversion circuit based on the tapped inductor shown includes:

[0049] 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;

[0050] When the switch S1 is turned on, the circuit is in the state Figure 4 The first working state shown;

[0051] When the switch tube S1 is disconnected, the circuit is in the state of Figure 5 The second working state shown;

[0052] 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.

[0053] Furthermore, when the switch tube S1 is turned on, the input voltage source Vin is directly applied to both ends of the coil winding n1 of the tapped inductor n1n2, and a voltage n×Vin is induced across the coil winding n2 and charges the second capacitor C2 through the first diode D1, and the voltage of the second capacitor C2 is Vc2=n×Vin; all the coil windings of the tapped inductor n1n2 are connected in series with the first capacitor C1 and then charge the capacitor C3 through the third diode D3, and the voltage of the third capacitor C3 is Vc3=Vc1+(1+n)×Vin, where Vc1 is the voltage of the first capacitor C1. In this state, the load RL is powered by the fourth capacitor C4.

[0054] Furthermore, the first working state is: when the switch tube S1 is disconnected, all the coil windings of the tapped inductor n1n2 are connected in series with the second capacitor C2 and then discharge to the first capacitor C1 through the diode D2. The total voltage of the tapped inductor is Vc1-Vc2, and the voltage on the coil winding n1 of the tapped inductor n1n2 is (Vc1-Vc2) / (1+n)=(Vc1-n×Vin) / (1+n); at the same time, the input voltage source Vin is connected in series with all the coil windings of the tapped inductor n1n2 and the third capacitor C3 and then charges the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4=Vin+Vc3+(Vc1-Vc2).

[0055] Furthermore, the second working state is: when the switch tube S1 operates alternately between the on and off states at high frequency, the voltage across the winding n1 switches between Vin and (Vc1-n×Vin) / (1+n) at high frequency; when the switching frequency is fixed and the on-duty cycle is d, using the volt-second balance principle, the voltage across the first capacitor C1 is Vc1=Vin×(d+n) / (1-d); the voltages of the third capacitor C3 and the fourth capacitor C4 are expressed as

[0056] Vc3=Vc1+(1+n)×Vin=Vin×(1+2n-nd) / (1-d)

[0057] Vc4=Vin+Vc3+(Vc1-Vc2)=Vin×2×(1+n) / (1-d)

[0058] The voltage across the fourth capacitor C4 is the output voltage, and the voltage gain is G=Vo / Vin=Vc4 / Vin=2×(1+n) / (1−d).

[0059] Example 4:

[0060] This embodiment provides a control method for a high-step-up ratio converter circuit based on a tapped inductor, including: when the switch tube S1 is turned on, the sixth capacitor C6 is connected in parallel with the fifth diode C5 through the third diode D3 and the sixth diode D6, so that Vc5=Vc6; when the switch tube S1 is turned off, the first capacitor C1, all windings of the tapped inductor, and the third capacitor C3 are connected in series, and then the fifth capacitor C5 is charged through the fifth diode D5. The voltage of the fifth capacitor C5 and the sixth capacitor C6 is

[0061] Vc5=Vc6=Vc3-Vc2=Vin×(1+n) / (1-d)

[0062] At the same time, the input voltage source Vin, the third capacitor C3, and the sixth capacitor C6 are connected in series and charge the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4 = Vin + Vc3 + Vc6 + (Vc1 - Vc2) = Vin × 3 × (1 + n) / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc4 / Vin = 3 × (1 + n) / (1 - d).

[0063] 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 tapped inductor, characterized in that: include: Input voltage source Vin, load RL, switch tube S1, tap inductor n1n2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first diode D1, second diode D2, third diode D3 and fourth diode D4; The tapped inductor n1n2 is composed of a coil continuously wound on the same magnetic core, the coil having an input end, an output end, and a tapped end, wherein the number of turns of the coil between the input end and the tapped end is n1, the number of turns of the coil between the tapped end and the output end is n2, and the turns ratio n2 / n1=n; The input end of the tapped inductor n1n2 and the negative electrode of the first capacitor C1 are simultaneously connected to the positive end of the input voltage source Vin; the tap end of the tapped inductor n1n2 is connected to the first end of the switch tube S1 and the anode of the first diode D1; the second end of the switch tube S1 is connected to the negative end of the input voltage source Vin; the cathode of the first diode D1 is connected to the anode of the second diode D2 and the positive electrode of the second capacitor C2; the cathode of the second diode D2 is connected to the anode of the third diode D3 and the positive electrode of the first capacitor C1; the cathode of the third diode D3 is connected to the anode of the fourth diode D4 and the positive electrode of the third capacitor C3; the negative electrodes of the second capacitor C2 and the third capacitor C3 are simultaneously connected to the output end of the tapped inductor n1n2; the cathode of the fourth diode D4 is connected to the positive electrode of the fourth capacitor C4 and serves as the output positive electrode; the negative electrode of the fourth capacitor C4 is connected to the negative end of the input voltage source Vin and serves as the output negative electrode; the control end of the 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 tapped inductor according to claim 1, characterized in that: The input voltage source Vin is a DC low voltage power supply.

3. The high step-up ratio conversion circuit based on tapped inductor 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 tapped inductor according to claim 1, characterized in that: The system further includes a fifth capacitor C5, a sixth capacitor C6, a fifth diode D5 and a sixth diode D6.

5. The high step-up ratio conversion circuit based on tapped inductor according to claim 4, characterized in that: The negative electrode of the fifth capacitor C5 is connected to the anode of the third diode D3, and the positive electrode of the fifth capacitor C5 is connected to the cathode of the fifth diode D5 and the anode of the sixth diode D6; the anode of the fifth diode D5 is connected to the cathode of the third diode D3 and the negative electrode of the sixth capacitor C6; the cathode of the sixth diode D6 is connected to the anode of the fourth diode D4 and the positive electrode of the sixth capacitor C6.

6. A control method for a high-step-up ratio conversion circuit based on a tapped 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 tapped inductor according to claim 6, wherein: The first working state is: the switch tube S1 is turned on, the input voltage source Vin is directly applied to the two ends of the coil winding n1 of the tapped inductor n1n2, and a voltage n×Vin is induced at the two ends of the coil winding n2 and the second capacitor C2 is charged through the first diode D1. The voltage of the second capacitor C2 is Vc2=n×Vin; all the coil windings of the tapped inductor n1n2 are connected in series with the first capacitor C1 and then charge the capacitor C3 through the third diode D3. The voltage of the third capacitor C3 is Vc3=Vc1+(1+n)×Vin, where Vc1 is the voltage of the first capacitor C1. In this state, the load RL is powered by the fourth capacitor C4.

8. The method for controlling a high-voltage step-up ratio conversion circuit based on a tapped inductor according to claim 6, wherein: The second working state is as follows: when the switch tube S1 is disconnected, all the coil windings of the tapped inductor n1n2 are connected in series with the second capacitor C2 and then discharge to the first capacitor C1 through the diode D2. The total voltage of the tapped inductor is Vc1-Vc2, and the voltage on the coil winding n1 of the tapped inductor n1n2 is (Vc1-Vc2) / (1+n)=(Vc1-n×Vin) / (1+n); at the same time, the input voltage source Vin is connected in series with all the coil windings of the tapped inductor n1n2 and the third capacitor C3, and then charges the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4=Vin+Vc3+(Vc1-Vc2).

9. The method for controlling a high-voltage step-up ratio conversion circuit based on a tapped 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-n×Vin) / (1+n) at high frequency. When the switching frequency is fixed and the on-duty cycle is d, the voltage across the first capacitor C1 is Vc1=Vin×(d+n) / (1-d) based on the volt-second balance principle. The voltages across the third and fourth capacitors C3 and C4 are expressed as Vc3=Vc1+(1+n)×Vin=Vin×(1+2n-nd) / (1-d) Vc4=Vin+Vc3+(Vc1-Vc2)=Vin×2×(1+n) / (1-d) The voltage across the fourth capacitor C4 is the output voltage, and the voltage gain is G=Vo / Vin=Vc4 / Vin=2×(1+n) / (1−d).

10. The method for controlling a high-step-up ratio conversion circuit based on a tapped inductor according to claim 6, wherein: When the switch tube S1 is turned on, the sixth capacitor C6 is connected in parallel with the fifth diode C5 through the third diode D3 and the sixth diode D6, so Vc5=Vc6; when the switch tube S1 is turned off, the first capacitor C1 and all the windings of the tapped inductor and the third capacitor C3 are connected in series and then charge the fifth capacitor C5 through the fifth diode D5. The voltage of the fifth capacitor C5 and the sixth capacitor C6 is Vc5=Vc6=Vc3-Vc2=Vin×(1+n) / (1-d) At the same time, the input voltage source Vin, the third capacitor C3, and the sixth capacitor C6 are connected in series and charge the fourth capacitor C4 and the load RL through the fourth diode D4. Therefore, the voltage of the fourth capacitor C4 is Vc4 = Vin + Vc3 + Vc6 + (Vc1 - Vc2) = Vin × 3 × (1 + n) / (1 - d). At this time, the voltage gain of the circuit is G = Vo / Vin = Vc4 / Vin = 3 × (1 + n) / (1 - d).

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