A non-isolated high-voltage-gain single-switch DC-DC converter and its control method

Abstract

A non-isolated high-voltage-gain single-switch DC-DC converter includes a DC voltage source, a coupling inductor, a switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a resistor. It achieves the desired voltage gain by appropriately selecting the turns ratio of the coupling inductor, uses a passive clamping circuit composed of capacitors and diodes to reduce voltage stress on the switching transistor, and utilizes the clamping capacitor to recover energy from the leakage inductance to avoid large voltage spikes. While reducing the stress on the switching transistor, this invention allows for the selection of a switching transistor with a small on-state resistance to reduce conduction losses and improve efficiency.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to a non-isolated high-voltage gain single-switch DC-DC converter and its control method. Background Technology

[0002] Traditional energy sources have drawbacks such as environmental pollution and high resource consumption. In order to alleviate the shortage of traditional energy resources and reduce environmental pollution, new energy sources have emerged.

[0003] Clean energy sources such as solar and wind power produce less pollution, but their output voltage is relatively low, typically between 15-40V. To achieve a higher DC bus voltage, high-gain DC-DC converters are necessary. Existing technologies, such as increasing the duty cycle to obtain high voltage output, result in high conduction losses. Similarly, isolated boost converters achieve high gain voltage by setting a high turns ratio, but this generates large voltage spikes, and the energy in the leakage inductance is difficult to transfer and utilize. Switched-capacitor converters suffer from low efficiency, difficulty in setting up capacitor charging paths, and large size. When the semiconductor switch is turned on, a large pulse current flows through the diodes and switching transistors, increasing current stress and conduction losses. Therefore, a new type of high-gain DC-DC converter is needed to address these issues. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a non-isolated high-voltage gain single-switch DC-DC converter and control method, addressing the problems of high conduction loss, difficulty in transferring and utilizing leakage inductance energy, voltage spikes, low efficiency, large size, and large pulse current in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A non-isolated high-voltage gain single-switch DC-DC converter includes a DC voltage source, a coupling inductor, a switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a resistor.

[0007] The primary side of the coupling inductor with the opposite-named terminal is connected to the positive terminal of the DC voltage source, and the same-named terminal is connected to the drain of the switching transistor and the positive terminal of the first diode.

[0008] The same-named terminal of the secondary side of the coupling inductor is connected to the positive terminal of the second capacitor and the positive terminal of the fourth diode, and the opposite-named terminal is connected to the negative terminal of the third capacitor and the negative terminal of the third diode.

[0009] The positive terminal of the first capacitor is connected to the negative terminal of the first diode and the positive terminal of the second diode, respectively; the negative terminal of the first capacitor is connected to the source of the switching transistor, the negative terminal of the second capacitor is connected to the negative terminal of the second diode and the positive terminal of the third diode, and the positive terminal of the third capacitor is connected to the negative terminal of the fourth diode and the positive terminal of the fifth diode, respectively.

[0010] The positive terminal of the fourth capacitor is connected to the negative terminal of the fifth diode and one end of the resistor, respectively, and the negative terminal of the fourth capacitor is connected to the source of the switching transistor.

[0011] The negative terminal of the DC voltage source, the source terminal of the switching transistor, and the other end of the resistor are all grounded.

[0012] The DC voltage source has a voltage range of 18-20V.

[0013] The primary side of the coupled inductor is connected in parallel with the magnetizing inductor and in series with the leakage inductance of the primary side of the coupled inductor.

[0014] The aforementioned switch is an N-channel power MOSFET with the model number IRF200P223.

[0015] The turns ratio of the coupled inductor is used to adjust the voltage gain.

[0016] The first, second, and third capacitors are all 20μF, and the fourth capacitor is 440μF.

[0017] The first diode, second diode, third diode, fourth diode, and fifth diode are all MUR1560GF type diodes.

[0018] A control method for a non-isolated high-voltage-gain single-switch DC-DC converter includes the following steps:

[0019] Step 1: The switching transistor is turned on, and the third and fourth diodes are in the conducting state; energy from the DC voltage source is transferred to the magnetizing inductance of the coupled inductor and the leakage inductance of the primary side of the coupled inductor; the magnetizing inductance of the coupled inductor transfers energy to the secondary side of the coupled inductor, and then charges the second and third capacitors from the secondary side of the coupled inductor; the fourth capacitor charges the resistor; when the current flowing through the magnetizing inductance of the coupled inductor... With the current flowing through the leakage inductance of the coupled inductor This phase ends when they are equal.

[0020] Step 2: The second, third, fourth, and fifth diodes all enter the conducting state, while the first diode remains in the cut-off state; the second and third capacitors charge the fourth capacitor and the resistor; during this operating phase, the energy flow direction on the secondary side of the coupled inductor is opposite to the charge flow from the second and third capacitors, and some energy on the secondary side of the coupled inductor is transferred to the first capacitor; this phase ends when the switching transistor drive signal disappears.

[0021] Step 3: The switching transistor is turned off, the first, second, and fifth diodes are turned on, and the third and fourth diodes are turned off; the DC voltage source directly supplies power to the resistor through the first, second, and fifth diodes, and the primary and secondary sides of the coupled inductor; the residual energy in the first capacitor is transferred to the resistor; the voltage stress on the switching transistor is reduced due to the presence of the first capacitor and the first diode; the energy in the leakage inductance of the secondary side of the coupled inductor flows to the fourth capacitor, charging it; simultaneously, the leakage inductance of the primary side of the coupled inductor releases energy; when the leakage current flows through the primary side of the coupled inductor... This phase ends when the value is zero.

[0022] Step 4: The third and fourth diodes are in the conducting state, while the first, second, and fifth diodes are in the cut-off state; the energy generated by the magnetizing inductance of the coupled inductor is discharged into the second and third capacitors, and the magnetizing inductance current flowing through the coupled inductor... The voltage gradually decreases; the fourth capacitor charges the resistor; this stage ends when the drive signal for the next cycle's switching transistor arrives.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] This invention discloses a non-isolated high-voltage-gain single-switch DC-DC converter, comprising a DC voltage source, a coupling inductor, a switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a resistor. It achieves the desired voltage gain by appropriately selecting the turns ratio of the coupling inductor, and uses a passive clamping circuit composed of capacitors and diodes to reduce voltage stress on the switching transistor. The clamping capacitors recover energy from the leakage inductance to avoid large voltage spikes. Furthermore, while reducing the stress on the switching transistor, this invention allows for the selection of a low-resistance on-state resistor to reduce conduction losses and improve efficiency. It has significant advantages compared to traditional boost converters, which suffer from high conduction losses, voltage spikes, low efficiency, high cost, and large size. Attached Figure Description

[0025] Figure 1 This is a topology diagram of a non-isolated high-voltage gain single-switch DC-DC converter circuit in a specific embodiment of the present invention.

[0026] Figure 2 The above is an equivalent circuit diagram for a specific embodiment of the present invention.

[0027] Figure 3 This is a waveform diagram of the voltage and current of the main components during one switching cycle in a specific embodiment of the present invention.

[0028] Figure 4 This is the first-stage modal diagram in a specific implementation example of the present invention.

[0029] Figure 5 This is the second-stage modal diagram in a specific embodiment of the present invention.

[0030] Figure 6 This is the modal diagram of the third stage in a specific implementation example of the present invention.

[0031] Figure 7 This is the modal diagram of the fourth stage in a specific implementation example of the present invention. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] This invention discloses a non-isolated high-voltage-gain single-switch DC-DC converter, such as... Figure 1 and Figure 2 As shown, it includes a DC voltage source V inThe following components are connected: coupling inductor L, switching transistor S, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first diode D1, second diode D2, third diode D3, fourth diode D4, fifth diode D5, and resistor R.

[0036] The primary side L of the coupled inductor N1 The opposite terminal is connected to a DC voltage source V. in The positive terminal is connected to the drain of the switching transistor S and the positive terminal of the first diode D1.

[0037] The secondary side L of the coupled inductor N2 The same-name terminal is connected to the positive terminal of the second capacitor C2 and the positive terminal of the fourth diode D4, and the opposite-name terminal is connected to the negative terminal of the third capacitor C3 and the negative terminal of the third diode D3.

[0038] The positive terminal of the first capacitor C1 is connected to the negative terminal of the first diode D1 and the positive terminal of the second diode D2 respectively; the negative terminal of the first capacitor C1 is connected to the source of the switching transistor S; the negative terminal of the second capacitor C2 is connected to the negative terminal of the second diode D2 and the positive terminal of the third diode D3 respectively; the positive terminal of the third capacitor C3 is connected to the negative terminal of the fourth diode D4 and the positive terminal of the fifth diode D5 respectively.

[0039] The positive terminal of the fourth capacitor Co is connected to the negative terminal of the fifth diode D5 and one end of the resistor R, respectively, and the negative terminal of the fourth capacitor C4 is connected to the source of the switching transistor S.

[0040] The DC voltage source V in The negative terminal, the source of the switching transistor S, and the other end of the resistor R are all grounded.

[0041] A preferred embodiment of the present invention is that the DC voltage source V in The voltage range is 18-20V.

[0042] Another preferred embodiment of the present invention is that the primary side L of the coupled inductor N1 Magnetizing inductance L with coupling inductor m In parallel, with the leakage inductance L of the primary side of the coupled inductor. lk1 Series connection.

[0043] Another preferred embodiment of the present invention is that the switching transistor S is an N-channel power MOSFET with model number IRF200P223.

[0044] In another preferred embodiment of the present invention, the turns ratio n of the coupled inductor is used to adjust the voltage gain.

[0045] In another preferred embodiment of the present invention, the first capacitor C1, the second capacitor C2 and the third capacitor C3 are all 20μF, and the fourth capacitor C4 is 440μF.

[0046] In another preferred embodiment of the present invention, the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 are all diodes of model MUR1560G.

[0047] A non-isolated high-voltage-gain single-switch DC-DC conversion method includes the following steps:

[0048] Step 1, as follows Figure 3 During the t0-t1 stage, the converter mode diagram is as follows: Figure 4 As shown. During this operating phase, switch S is turned on, and diodes D3 and D4 are in the conducting state; the voltage source V... in The energy is transferred to the magnetizing inductor L of the coupled inductor. m And the leakage inductance L on the primary side of the coupled inductor lk1 The magnetizing inductance L of the coupled inductor m Energy is transferred to the secondary side L of the coupled inductor. N2 Then, from the secondary side L of the coupled inductor N2 The second capacitor C2 and the third capacitor C3 are charged; the fourth capacitor C4 charges the resistor R; when the magnetizing inductance L flows through the coupling inductor... m current The leakage inductance L of the coupled inductor lk1 current This phase ends when they are equal.

[0049] Step 2, as follows Figure 3 During the t1-t2 phase, the converter modal diagram is as follows: Figure 5 As shown. During this operating phase, the switch S remains on, and the second diode D2, third diode D3, fourth diode D4, and fifth diode D5 are all in the conducting state, while the first diode D1 remains off. The second capacitor C2 and the third capacitor C3 charge the fourth capacitor C4 and the resistor R. During this operating phase, the secondary side L of the coupling inductor... N2 The energy flow direction is opposite to the charge flow from the second capacitor C2 and the third capacitor C3, and the secondary side of the coupled inductor L N2 Some of the energy is transferred to the first capacitor C1;

[0050] Step 3, as follows Figure 3 During the t2-t3 stage, the converter modal diagram is as follows: Figure 6 As shown. During this operating phase, switch S is off, diodes D1, D2, and D5 are on, and diodes D3 and D4 are off; DC voltage source V... inPower is supplied directly to resistor R through diodes D1, D2, and D5, as well as the primary and secondary sides of the coupling inductor; residual energy in capacitor C1 is transferred to resistor R; voltage stress on switch S is reduced due to the presence of capacitor C1 and diode D1; leakage inductance L on the secondary side of the coupling inductor... lk2 The energy in the capacitor flows to the fourth capacitor C4, charging it; simultaneously, the leakage inductance L on the primary side of the coupling inductor... lk1 Energy is released when the leakage current flows through the primary side of the coupled inductor. This phase ends when the value is zero.

[0051] Step 4, as follows Figure 3 During the t3-t4 stage, the converter modal diagram is as follows: Figure 7 As shown. During this operating phase, switch S remains off, diodes D3 and D4 are on, and diodes D1, D2, and D5 are off; the magnetizing inductance L of the coupling inductor... m The generated energy is discharged into the second capacitor C2 and the third capacitor C3, and the magnetizing current flows through the coupling inductor. The current gradually decreases; the fourth capacitor C4 charges the resistor R.

[0052] The present invention discloses a non-isolated high-voltage-gain single-switch DC-DC converter, wherein, with a fixed turns ratio, the voltage gain increases with a larger duty cycle; and with a fixed duty cycle, the voltage gain increases with a larger turns ratio of the coupled inductor.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-isolated high-voltage-gain single-switch DC-DC converter, characterized in that, It includes a DC voltage source, a coupling inductor, a switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a resistor; The primary side of the coupling inductor with the opposite-named terminal is connected to the positive terminal of the DC voltage source, and the same-named terminal is connected to the drain of the switching transistor and the positive terminal of the first diode. The same-named terminal of the secondary side of the coupling inductor is connected to the positive terminal of the second capacitor and the positive terminal of the fourth diode, and the opposite-named terminal is connected to the negative terminal of the third capacitor and the negative terminal of the third diode. The positive terminal of the first capacitor is connected to the negative terminal of the first diode and the positive terminal of the second diode, respectively; the negative terminal of the first capacitor is connected to the source of the switching transistor, the negative terminal of the second capacitor is connected to the negative terminal of the second diode and the positive terminal of the third diode, and the positive terminal of the third capacitor is connected to the negative terminal of the fourth diode and the positive terminal of the fifth diode, respectively. The positive terminal of the fourth capacitor is connected to the negative terminal of the fifth diode and one end of the resistor, respectively, and the negative terminal of the fourth capacitor is connected to the source of the switching transistor. The negative terminal of the DC voltage source, the source terminal of the switching transistor, and the other end of the resistor are all grounded.

2. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The DC voltage source has a voltage range of 18-20V.

3. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The primary side of the coupled inductor is connected in parallel with the magnetizing inductor and in series with the leakage inductance of the primary side of the coupled inductor.

4. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The aforementioned switch is an N-channel power MOSFET with the model number IRF200P223.

5. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The turns ratio of the coupled inductor is used to adjust the voltage gain.

6. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The first, second, and third capacitors are all 20μF, and the fourth capacitor is 440μF.

7. The non-isolated high-voltage-gain single-switch DC-DC converter according to claim 1, characterized in that, The first diode, second diode, third diode, fourth diode, and fifth diode are all MUR1560GF type diodes.

8. The control method for a non-isolated high-voltage gain single-switch DC-DC converter according to claim 1, characterized in that, Includes the following steps: Step 1: The switching transistor is turned on, and the third and fourth diodes are in the conducting state; Energy from the DC voltage source is transferred to the magnetizing inductance of the coupled inductor and the leakage inductance of the primary side of the coupled inductor; The magnetizing inductance of the coupled inductor transfers energy to the secondary side of the coupled inductor, and then charges the second and third capacitors from the secondary side; the fourth capacitor charges the resistor; when the current flowing through the magnetizing inductance of the coupled inductor... With the current flowing through the leakage inductance of the coupled inductor This phase ends when they are equal. Step 2: The second, third, fourth, and fifth diodes all enter the conducting state, while the first diode remains in the cut-off state; the second and third capacitors charge the fourth capacitor and the resistor; during this operating phase, the energy flow direction on the secondary side of the coupled inductor is opposite to the charge flow from the second and third capacitors, and some energy on the secondary side of the coupled inductor is transferred to the first capacitor; This stage ends when the switching transistor drive signal disappears. Step 3: The switching transistor is turned off, the first, second, and fifth diodes are turned on, and the third and fourth diodes are turned off; the DC voltage source supplies power directly to the resistor through the first, second, and fifth diodes, the primary and secondary sides of the coupled inductor; the residual energy in the first capacitor is transferred to the resistor; the voltage stress on the switching transistor is reduced due to the presence of the first capacitor and the first diode. Energy flows from the leakage inductance of the secondary side of the coupled inductor to the fourth capacitor, charging it; simultaneously, energy is released from the leakage inductance of the primary side of the coupled inductor; when the leakage current flows through the primary side of the coupled inductor... This phase ends when the value is zero. Step 4: The third and fourth diodes are in the conducting state, while the first, second, and fifth diodes are in the cut-off state; the energy generated by the magnetizing inductance of the coupled inductor is discharged into the second and third capacitors, and the magnetizing inductance current flowing through the coupled inductor... The voltage gradually decreases; the fourth capacitor charges the resistor; this stage ends when the drive signal for the next cycle's switching transistor arrives.

Images