Quadratic ultrahigh-gain DC-DC converter based on coupling inductor

Abstract

The invention provides a secondary ultrahigh-gain DC-DC converter based on a coupling inductor. The DC-DC converter comprises capacitors Co, C1, C2, C3 and C4, diodes Do, D1, D2, D3 and D4, power switch tubes S1 and S2, an input inductor L1, and a three-winding coupling inductor formed by equivalently forming an excitation inductor Lm, a leakage inductor Lk, a primary winding N1, a secondary winding N2 and a secondary winding N3. According to the converter, the three-winding coupling inductor and voltage-multiplying unit technology is fused, the secondary booster circuit is embedded, compared with an existing high-gain converter, the converter can obtain high voltage gain under the low turn ratio condition, the problems of high winding equivalent series resistance and large leakage inductance caused by the high turn ratio are solved, and the reliability of the converter is improved. Meanwhile, a relatively large duty ratio is avoided; due to the continuity of the input current and the common-ground characteristic between the input power supply and the load, the converter is suitable for renewable energy source application; in addition, the converter realizes high voltage gain, and meanwhile, the voltage stress on the power device is low.

Description

Technical Field

[0001] The invention relates to the field of renewable energy power generation, in particular to a quadratic ultra-high gain DC-DC converter based on coupled inductors. Background Art

[0002] With the rapid development of society, environmental pollution and energy shortages on the earth have become increasingly prominent, and these problems have become key factors restricting social progress. Therefore, it is particularly urgent to develop and utilize new energy sources with the characteristics of sustainability, low pollution, and large reserves. Among them, clean energy such as solar energy and fuel cells have received widespread attention.

[0003] The output voltage range of photovoltaic panels and fuel cells is 18-56V DC voltage. The voltage level cannot meet the requirements of grid connection, and a DC-DC boost module needs to be connected at the later stage to increase the voltage level. Traditional Boost converters are widely used in many applications such as photovoltaic systems due to their simplicity and economy. However, when trying to achieve higher voltage gain, they are restricted by parasitic parameters. Even if the duty cycle is set to the maximum value, it is difficult to achieve the required high gain effect. In view of the performance limitations of traditional DC converters, the development of DC-DC converters with high voltage gain, high efficiency and low voltage stress characteristics has become a hot topic in current research. In addition, for DC-DC converters used in renewable energy power generation systems, continuous low ripple input current is essential to achieve maximum power point tracking (MPPT) and extend the service life of renewable energy components. Summary of the invention

[0004] The purpose of the present invention is to propose a quadratic ultra-high gain DC-DC converter based on coupled inductors, which integrates three-winding coupled inductors and voltage doubling unit technology and embeds a quadratic boost circuit, and performs parameter design so that the converter can obtain high voltage gain under low turns ratio conditions, avoiding the problems of high equivalent series resistance of the winding and large leakage inductance caused by high turns ratio, and at the same time avoiding a large duty cycle.

[0005] To achieve the above object, the technical solution of the present invention is: a quadratic ultra-high gain DC-DC converter based on coupled inductance, the DC-DC converter includes a capacitor C o , C 1 , C 2 , C 3 , C 4 , diode D o , D 1 , D 2 , D 3 , D 4 , power switch tube S1 and S 2 , input inductance L 1 , and the excitation inductance L m , leakage inductance L k , primary winding N 1 , secondary winding N 2 and the secondary winding N 3 The equivalent three-winding coupled inductor;

[0006] The DC-DC converters are respectively connected to a DC input voltage source V g and load R; where the DC input voltage source V g The positive terminal is connected to the input inductor L 1 One end, DC input voltage source V g The negative terminal is connected to the capacitor C 1 Negative pole, power switch tube S 2 Source, diode D 2 Cathode and capacitor C o Negative pole; both ends of the load R are connected to the capacitor C o The positive and negative poles;

[0007] Input inductance L 1 The other end is connected to the diode D 1 Anode, capacitor C 2 Positive electrode and power switch tube S 2 Drain; diode D 1 The cathode is connected to the capacitor C 1 Positive pole and primary winding N 1 First end: primary winding N 1 The second end is connected to the power switch tube S 1 Drain and secondary winding N 2 First end: power switch tube S 1 The source is connected to the capacitor C 2 Negative electrode, capacitor C 3 The cathode and diode D 2 Anode; capacitor C 3 The anode is connected to the diode D 3 Cathode and diode D 4 Anode; diode D 3 The anode is connected to the secondary winding N 2 The second terminal and the secondary winding N 3 First end; Secondary winding N 3 The second end is connected to the capacitor C 4 Negative electrode; capacitor C 4 The anode is connected to the diode D 4 Cathode and diode D o Anode; diode D o The cathode is connected to the capacitor Co positive electrode.

[0008] Preferably, the primary winding N 1 The first end, the secondary winding N 2 The first terminal and the secondary winding N 3 The first end is the end with the same name.

[0009] Preferably, the DC-DC converter has three main operating modes in the continuous current mode (CCM), wherein modes 1 and 3 are the main modes;

[0010] Mode 1: When the switch trigger pulse signal is at the rising edge, mode 1 starts; in the current mode, the power switch tube S 1 and S 2 Conducting, diode D 4 Conducting, diode D o , D 1 , D 2 , D 3 Turn off; when the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero, mode 1 ends;

[0011] Mode 2: When the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero, mode 2 begins; in this mode, the diode D 4 Turn off; when the switch trigger pulse signal is at the falling edge, mode 2 ends;

[0012] Mode 3: When the switch trigger pulse signal is at the falling edge, mode 3 starts; in the current mode, the power switch tube S 1 and S 2 Turn off, diode D o , D 1 , D 2 , D 3 Conducting, diode D 4 Turn off; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends.

[0013] Preferably, the operation mode of the mode 1 is specifically as follows:

[0014] When the switch trigger pulse signal is at the rising edge, mode 1 starts; the switch trigger pulse signal is in a high level state, making the power switch tube S 1 and S 2 At the same time, the DC input voltage source V g Through the power switch tube S 2 To the input inductor L1 Charging, input inductor current i Lin Linear rise; capacitor C 1 and C 2 Discharge, transfer energy to the excitation inductor L m And the primary winding N 1 , the magnetizing inductor current i Lm Linear rise, primary winding N 1 The energy is transferred to the secondary winding N through coupling 2 and the secondary winding N 3 , capacitor C 3 , secondary winding N 2 and the secondary winding N 3 Through the diode D 4 To capacitor C 4 Charging, leakage current i Lk Drop; capacitor C o Release energy to charge the load R; when it flows through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero, mode 1 ends;

[0015] The equivalent circuit KVL equation of mode 1 is:

[0016]

[0017] Where: V L1_ON 、V N1_ON 、V N2_ON 、V N3_ON Respectively represent the input inductance L 1 And the three windings N of the coupled inductor 1 、N 2 and N 3 Voltage in mode 1; V g is the DC input voltage source voltage, V C1 、V C2 、V C3 、V C4 is the capacitor C 1 , C 2 , C 3 , C 4 Voltage, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1 =N 2 / N 1 , n 2 =N 3 / N 1 .

[0018] Preferably, the operation mode of the mode 2 is specifically as follows:

[0019] When the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current of diode D drops to zero, mode 2 begins; 4 Turn off, capacitor C 1 and C 2 Series discharge continues to transfer energy to the excitation inductor L m , the magnetizing inductor current i Lm and leakage inductance current i Lk Linearly rising together; DC input voltage source V g Continue through the power switch tube S 2 To the input inductor L 1 Charging, input inductor current i Lin Linear rise; when the switch trigger pulse signal is at the falling edge, mode 2 ends.

[0020] Preferably, the operation mode of the mode 3 is specifically as follows:

[0021] When the switch trigger pulse signal is at the falling edge, mode 3 starts; the power switch tube S 1 and S 2 Turn off, capacitor C 2 The power switch tube S 2 The voltage stress across the capacitor is clamped to C 2 Voltage V C2 ; diode D 1 , D 2 , D 3 and D o In the on state, the diode D 4 Keep off; input inductor L 1 Through the diode D 1 , D 2 The released energy is capacitor C 1 and C 2 Charging; capacitor C 3 Receiving primary winding N 1 , secondary winding N 2 Energy released; DC input voltage source V g , input inductance L 1 , primary winding N 1 , secondary winding N 2 and the secondary winding N 3 、Capacitor C 4 (voltage doubling capacitor) in series, to the load R and capacitor C o (Output capacitor) transfers energy; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends

[0022] The equivalent circuit KVL equation of mode 3 is:

[0023]

[0024] Where: V L1_OFF 、V N1_OFF 、V N2_OFF 、V N3_OFF Respectively represent the input inductance L 1 And the three windings N of the coupled inductor 1 、N 2 and N 3 Voltage in Mode 3; V O is the output voltage of the DC-DC converter.

[0025] Preferably, the DC-DC converter voltage gain G is expressed as:

[0026]

[0027] Where: D is the duty cycle of the switch trigger pulse signal.

[0028] Preferably, the input inductor L 1 The inductance range is:

[0029]

[0030] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, λ L1 The ripple factor of the inductor current, G is the converter voltage gain, f S is the switching frequency of the switch tube.

[0031] Preferably, the excitation inductance L m The inductance range is:

[0032]

[0033] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1 =N 2 / N 1 , n 2 =N 3 / N 1 , G is the converter voltage gain, f S is the switching frequency of the switch tube.

[0034] Preferably, the capacitor C in the DC-DC converter o , C 1 , C 2 , C 3 , C 4The capacitance value satisfies the following relationship:

[0035]

[0036] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1 =N 2 / N 1 , n 2 =N 3 / N 1 , G is the converter voltage gain, f S is the switching frequency of the switch tube, λ C is the capacitor voltage ripple factor.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention combines three-winding coupled inductor and voltage doubling unit technology and embeds a secondary boost circuit. Compared with the existing high-gain converter, the converter can obtain high voltage gain under low turns ratio conditions, avoiding the problems of high equivalent series resistance and large leakage inductance of the winding due to high turns ratio, and avoiding a large duty cycle. The continuity of the input current and the common ground between the input power supply and the load make the converter suitable for renewable energy applications. In addition, the proposed converter achieves high voltage gain while low voltage stress on the power device. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A circuit diagram of a quadratic ultra-high gain DC-DC converter based on coupled inductors according to the present invention;

[0040] Figure 2 The theoretical operation waveform diagram of the converter under the current continuous mode of the present invention;

[0041] Figure 3 The equivalent circuit diagram of the converter mode 1 of the present invention;

[0042] Figure 4 This is the equivalent circuit diagram of the converter mode 3 proposed by the present invention;

[0043] Figure 5 A three-dimensional curve diagram of voltage gain, duty cycle and turns ratio according to an embodiment of the present invention;

[0044] Figure 6 4 is a key simulation waveform diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0046] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0048] like Figure 1 As shown, a high-gain DC converter proposed in the present invention includes a capacitor C o , C 1 , C 2 , C 3 , C 4 , diode D o , D 1 , D 2 , D 3 , D 4 , power switch tube S 1 and S 2 , input inductance L 1 , and the excitation inductance L m , leakage inductance L k , primary winding N 1 , secondary winding N 2 and the secondary winding N 3 The equivalent three-winding coupled inductor;

[0049] The DC-DC converters are respectively connected to a DC input voltage source V g and load R; where the DC input voltage source V g The positive terminal is connected to the input inductor L 1 One end, DC input voltage source V g The negative terminal is connected to the capacitor C 1 Negative pole, power switch tube S 2 Source, diode D 2 Cathode and capacitor C o Negative pole; both ends of the load R are connected to the capacitor C o The positive and negative poles;

[0050] Input inductance L 1 The other end is connected to the diode D 1Anode, capacitor C 2 Positive electrode and power switch tube S 2 Drain; diode D 1 The cathode is connected to the capacitor C 1 Positive pole and primary winding N 1 First end: primary winding N 1 The second end is connected to the power switch tube S 1 Drain and secondary winding N 2 First end: power switch tube S 1 The source is connected to the capacitor C 2 Negative electrode, capacitor C 3 The cathode and diode D 2 Anode; capacitor C 3 The anode is connected to the diode D 3 Cathode and diode D 4 Anode; diode D 3 The anode is connected to the secondary winding N 2 The second terminal and the secondary winding N 3 First end; Secondary winding N 3 The second end is connected to the capacitor C 4 Negative electrode; capacitor C 4 The anode is connected to the diode D 4 Cathode and diode D o Anode; diode D o The cathode is connected to the capacitor C o positive electrode.

[0051] Among them, the diode D 1 , D 2 and capacitor C 1 , C 2 , power switch tube S 1 and S 2 , input inductance L 1 and the primary winding N 1 The diode D constitutes a double-tube secondary type front stage. 3 , D 4 and capacitor C 3 , C 4 And the secondary winding N 3 Form a voltage doubling unit.

[0052] In this embodiment, the primary winding N 1 The first end, the secondary winding N 2 The first terminal and the secondary winding N 3 The first end is the end with the same name.

[0053] In this embodiment, the DC-DC converter has three main operating modes in the continuous current mode (CCM), and the theoretical waveforms of the operation are as follows: Figure 2 As shown, modes 1 and 3 are used as main modes;

[0054] Mode 1: When the switch trigger pulse signal is at the rising edge, mode 1 starts; in the current mode, the power switch tube S 1 and S 2 Conducting, diode D 4 Conducting, diode D o , D 1 , D 2 , D 3 Turn off; when the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero, mode 1 ends;

[0055] Mode 2: When the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero, mode 2 begins; in this mode, the diode D 4 Turn off; when the switch trigger pulse signal is at the falling edge, mode 2 ends;

[0056] Mode 3: When the switch trigger pulse signal is at the falling edge, mode 3 starts; in the current mode, the power switch tube S 1 and S 2 Turn off, diode D o , D 1 , D 2 , D 3 Conducting, diode D 4 Turn off; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends.

[0057] In this embodiment, the specific working conditions of each mode are as follows:

[0058] like Figure 3 As shown, the mode 1(t 0 —t 1 ) is run as follows:

[0059] When the switch trigger pulse signal is at the rising edge (t 0 ), mode 1 starts; the switch trigger pulse signal is in a high level state, making the power switch tube S 1 and S 2 At the same time, the DC input voltage source V g Through the power switch tube S 2 To the input inductor L 1Charging, input inductor current i Lin Linear rise; capacitor C 1 and C 2 Discharge, transfer energy to the excitation inductor L m And the primary winding N 1 , the magnetizing inductor current i Lm Linear rise, primary winding N 1 The energy is transferred to the secondary winding N through coupling 2 and the secondary winding N 3 , capacitor C 3 , secondary winding N 2 and the secondary winding N 3 Through the diode D 4 To capacitor C 4 Charging, leakage current i Lk Drop; capacitor C o (output capacitor) releases energy to charge the load R; when it flows through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero (t 1 ), mode 1 ends

[0060] The mode 2 (t 1 —t 2 ) is run as follows:

[0061] When the current flowing through the secondary winding N 2 and the secondary winding N 3 When the current drops to zero (t 1 ), mode 2 starts; diode D 4 Turn off, capacitor C 1 and C 2 Series discharge continues to transfer energy to the excitation inductor L m , the magnetizing inductor current i Lm and leakage inductance current i Lk Linearly rising together; DC input voltage source V g Continue through the power switch tube S 2 To the input inductor L 1 Charging, input inductor current i Lin Linear rise; when the switch trigger pulse signal is at the falling edge (t 2 ), with the arrival of the switch off signal, mode 2 ends and then turns to the next mode;

[0062] like Figure 4 As shown, the mode 3 (t 2 —t 3 ) is run as follows:

[0063] When the switch trigger pulse signal is at the falling edge (t 2 ), Mode 3 starts; power switch tube S 1 and S 2 Turn off, capacitor C 2 The power switch tube S 2 The voltage stress across the capacitor is clamped to C 2 Voltage V C2 ; diode D 1 , D 2 , D 3 and D o In the on state, the diode D 4 Keep off; input inductor L 1 Through the diode D 1 , D 2 The released energy is capacitor C 1 and C 2 Charging; capacitor C 3 Receiving primary winding N 1 , secondary winding N 2 Energy released; DC input voltage source V g , input inductance L 1 , primary winding N 1 , secondary winding N 2 and the secondary winding N 3 、Capacitor C 4 (voltage doubling capacitor) in series, to the load R and capacitor C o (Output capacitor) delivers energy; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends.

[0064] In this embodiment, a steady-state analysis is performed on the converter to obtain voltage and current stress expressions and voltage gain formulas of all components of the converter.

[0065] Applying Kirchhoff voltage law (KVL) to the loop in the equivalent circuit of mode 1 and writing the KVL equation, we can get:

[0066]

[0067] Where: V L1_ON 、V N1_ON 、V N2_ON 、V N3_ON Respectively represent the input inductance L 1 And the three windings N of the coupled inductor 1 、N 2 and N 3 Voltage in mode 1; V g is the DC input voltage source voltage, V C1 、VC2 、V C3 、V C4 is the capacitor C 1 , C 2 , C 3 , C 4 Voltage, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1 =N 2 / N 1 , n 2 =N 3 / N 1 ;

[0068] Writing the KVL equation for mode 3 gives:

[0069]

[0070] Where: V L1_OFF 、V N1_OFF 、V N2_OFF 、V N3_OFF Respectively represent the input inductance L 1 And the three windings N of the coupled inductor 1 、N 2 and N 3 Voltage in Mode 3; V O is the output voltage of the DC-DC converter;

[0071] The voltage of each winding of the input inductor and coupled inductor in one cycle satisfies the volt-second balance law:

[0072]

[0073] Where D is the duty cycle of the switch trigger pulse signal, T s is the switch trigger pulse signal period;

[0074] By solving the above mentioned DC-DC converter voltage gain G, we can get:

[0075]

[0076] Where: D is the duty cycle of the switch trigger pulse signal;

[0077] Further combination can solve the voltage stress expression of all devices.

[0078] Applying Kirchhoff current law (KCL) to the nodes in the equivalent circuit of mode 1, writing the KCL equation, we can get:

[0079]

[0080] In the formula, I Co_ON ,I C1_ON ,I C2_ON ,I C3_ON ,I C4_ON They represent the capacitance C in mode 1 respectively. o , C 1 , C 2 , C 3 , C 4 The current, I S1 ,I S2 They represent the switch tube S in mode 1 respectively. 1 and S 2 The current, I Lin is the input inductor current, I o is the output current on the load resistor, I D4 Indicates the diode D in mode 1 4 of current.

[0081] Writing the KCL equation for mode 3, we can derive:

[0082]

[0083] In the formula, I Co_OFF ,I C1_OFF ,I C2_OFF ,I C3_OFF ,I C4_OFF Respectively represent the capacitance C in mode 3 o , C 1 , C 2 , C 3 , C 4 The current, I Do ,I D1 ,I D2 ,I D3 Respectively represent the diode D in mode 3 o , D 1 , D 2 , D 3 of current.

[0084] Apply the ampere-second balance rule to each capacitor:

[0085]

[0086] The current stress expressions of all devices can be obtained by simultaneous solution.

[0087] In this embodiment, the parameter design of the converter needs to meet the stability and high efficiency principles of the converter operation, so it is necessary to select appropriate device parameters.

[0088] When designing the input inductor L 1When the input current is continuous, the main purpose should be to ensure the continuity of the input current and control the input inductor current ripple within an appropriate range; the input inductor current ripple Δi Lin The expression is as follows:

[0089]

[0090] Where V L1_ON The input inductance L during the switch on period 1 Voltage across L 1 is the input inductance value, f S is the switching frequency of the switch tube;

[0091] In order to make the converter have a smaller input current ripple, a specified ripple factor λ is set L1 , the input current ripple should meet:

[0092] Δi Lin ≤λ L1 I Lin ;

[0093] It can be further deduced that the input inductance L 1 The inductance range is:

[0094]

[0095] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, λ L1 The ripple factor of the inductor current, G is the converter voltage gain, f S is the switching frequency of the switch tube.

[0096] When designing the excitation inductance value of the coupled winding, the excitation inductance current i should also be considered. Lm Continuity;

[0097] The calculation formula of the coupled inductor current ripple is the same as that of the input inductor; therefore, in order for the converter to operate in a current continuous state, the excitation inductor current and the input inductor current must meet the following constraints:

[0098]

[0099] It can be further deduced that the excitation inductance L m The inductance range is:

[0100]

[0101] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1=N 2 / N 1 , n 2 =N 3 / N 1 , G is the converter voltage gain, f S is the switching frequency of the switch tube.

[0102] According to the principle of capacitor charge balance, it can be known that the capacitance value is mainly determined by the current I C And the capacitor voltage ripple ΔV C To make a selection. Assume λ C is the ripple factor of the capacitor voltage, then the capacitor voltage ripple ΔV C =λ C V C , therefore, the capacitance value is calculated as:

[0103]

[0104] Among them, when choosing the capacitor voltage ripple coefficient λ C When the voltage ripple level of the capacitor should be reduced as much as possible to ensure the stable operation of the converter, the ripple factor λ is generally set C 2%;

[0105] According to the device voltage and current obtained during the analysis process, the capacitor C in the DC-DC converter can be obtained: o , C 1 , C 2 , C 3 , C 4 The capacitance value satisfies the following relationship:

[0106]

[0107] Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n 1 and n 2 is the turns ratio of the three-winding coupled inductor, n 1 =N 2 / N 1 , n 2 =N 3 / N 1 , G is the converter voltage gain, f S is the switching frequency of the switch tube, λ C is the capacitor voltage ripple factor.

[0108] Figure 5 The voltage gain, duty cycle and turns ratio three-dimensional curve of the present invention shows that the structure of the new converter TWCL enables the converter to obtain ultra-high voltage gain with winding N 2 and N 3It is a boost type. Under the same voltage gain, the total turns ratio of the coupled inductor is smaller than that of the existing high-gain converter, avoiding the increase in the volume and loss of the converter caused by the large total turns ratio. The results show that the voltage gain can be controlled by three degrees of freedom (D, n 2 and n 1 ) can be adjusted flexibly. The proposed converter is in the condition of D = 0.45, n 1 =1,n 2 =0.5, the theoretical voltage gain can reach 22.45 times, which has a strong boost capability.

[0109] like Figure 6 The simulation key waveform of the present invention is shown in FIG. 1 . In this embodiment, the simulation is performed in Saber simulation software, wherein the parameters of the converter are set as follows:

[0110] DC input voltage source V g The voltage is 22V, the resistance of the load R is 800Ω, and the excitation inductance L m The inductance value is set to 272uH, and the input inductance L 1 The inductance is set to 100uH, the capacitor C 1 , C 2 100uF, C 3 10uF, C 4 , C o The inductor is 5.6μF, the switching frequency is 50kHz, the duty cycle D is 0.4, and the turns ratio of the three-winding coupled inductor is n:n 1 :n 2 =1:1:0.5. The simulation result waveform is as follows Figure 6 As shown, Figure 6 The horizontal axis in the middle represents time. There are 6 groups of waveforms from top to bottom. The first group is the driving signal V of the power switch tube. gs The signal waveform diagram of the second and third groups is the power switch tube S with larger voltage stress 1 The current and voltage waveforms of the input current i Lin The waveform shows that the input current is continuous and the input current ripple is small. This is mainly because the input end directly passes through the input inductor L 1 Input energy, in the parameter design stage, the appropriate inductor can be selected according to the calculation formula to make the ripple meet the requirements. This structure is conducive to extending the service life of the power supply and realizing MPPT control. Group 5 and Group 6 are input and output voltages. The output voltage of the converter is 380V, the input voltage is 22V, and the voltage gain G=17.3, which verifies that the converter topology has a strong boost effect and can well meet the requirements of high-gain DC-DC converters.

[0111] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A quadratic ultra-high gain DC-DC converter based on coupled inductors, characterized in that: The DC-DC converter includes a capacitor C o , C1, C2, C3, C4, diode D o , D1, D2, D3, D4, power switch tubes S1 and S2, input inductor L1, and excitation inductor L m , leakage inductance L k , a three-winding coupled inductor formed by the primary winding N1, the secondary winding N2 and the secondary winding N3; The DC-DC converters are respectively connected to a DC input voltage source V g and load R; where the DC input voltage source V g The positive electrode is connected to one end of the input inductor L1, and the DC input voltage source V g The negative electrode is connected to the negative electrode of capacitor C1, the source of power switch tube S2, the cathode of diode D2 and the capacitor C o Negative pole; both ends of the load R are connected to the capacitor C o The positive and negative poles; The other end of the input inductor L1 is connected to the anode of the diode D1, the anode of the capacitor C2 and the drain of the power switch tube S2; the cathode of the diode D1 is connected to the anode of the capacitor C1 and the first end of the primary winding N1; the second end of the primary winding N1 is connected to the drain of the power switch tube S1 and the first end of the secondary winding N2; the source of the power switch tube S1 is connected to the negative electrode of the capacitor C2, the negative electrode of the capacitor C3 and the anode of the diode D2; the positive electrode of the capacitor C3 is connected to the cathode of the diode D3 and the anode of the diode D4; the anode of the diode D3 is connected to the second end of the secondary winding N2 and the first end of the secondary winding N3; the second end of the secondary winding N3 is connected to the negative electrode of the capacitor C4; the positive electrode of the capacitor C4 is connected to the cathode of the diode D4 and the diode D o Anode; diode D o The cathode is connected to the capacitor C o positive electrode.

2. The quadratic ultra-high gain DC-DC converter based on coupled inductors according to claim 1, characterized in that: The first end of the primary winding N1, the first end of the secondary winding N2 and the first end of the secondary winding N3 are terminals of the same name.

3. The quadratic ultra-high gain DC-DC converter based on coupled inductors according to claim 1, characterized in that: The DC-DC converter has three main operating modes in the inductor current continuous mode, of which modes 1 and 3 are the main modes; Mode 1: When the switch trigger pulse signal is at the rising edge, mode 1 starts; in the current mode, power switch tubes S1 and S2 are turned on, diode D4 is turned on, and diode D o , D1, D2, D3 are turned off; When the current flowing through the secondary winding N2 and the secondary winding N3 drops to zero, mode 1 ends; Mode 2: When the current flowing through the secondary winding N2 and the secondary winding N3 drops to zero, mode 2 starts; in the current mode, the diode D4 is turned off; when the switch trigger pulse signal is at the falling edge, mode 2 ends; Mode 3: When the switch trigger pulse signal is at the falling edge, mode 3 starts; in the current mode, the power switch tubes S1 and S2 are turned off, and the diode D o , D1, D2, and D3 are turned on, and diode D4 is turned off; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends.

4. The quadratic ultra-high gain DC-DC converter based on coupled inductance according to claim 3, characterized in that: The operation mode of the mode 1 is specifically as follows: When the switch trigger pulse signal is at the rising edge, mode 1 starts; the switch trigger pulse signal is in a high level state, so that the power switch tubes S1 and S2 are turned on at the same time, and the DC input voltage source V g The input inductor L1 is charged through the power switch tube S2, and the input inductor current i Lin Linear rise; capacitors C1 and C2 discharge and transfer energy to the excitation inductor L m And the primary winding N1, the excitation inductance current i Lm The energy of the primary winding N1 is transferred to the secondary winding N2 and the secondary winding N3 through coupling. The capacitor C3, the secondary winding N2 and the secondary winding N3 charge the capacitor C4 through the diode D4. The leakage inductance current i Lk Drop; capacitor C o Release energy to charge the load R; when the current flowing through the secondary winding N2 and the secondary winding N3 drops to zero, mode 1 ends; The equivalent circuit KVL equation of mode 1 is: Where: V L1_ON 、V N1_ON 、V N2_ON 、V N3_ON Respectively represent the voltages of the input inductor L1 and the three windings N1, N2 and N3 of the coupled inductor in mode 1; V g is the DC input voltage source voltage, V C1 、V C2 、V C3 、V C4 are the voltages of capacitors C1, C2, C3, and C4, n1 and n2 are the turns ratios of the three-winding coupled inductors, n1 = N2 / N1, n2 = N3 / N1.

5. The quadratic ultra-high gain DC-DC converter based on coupled inductance according to claim 3, characterized in that: The operation mode of the mode 2 is specifically as follows: When the current flowing through the secondary winding N2 and the secondary winding N3 drops to zero, mode 2 begins; the diode D4 is turned off, and the capacitors C1 and C2 are discharged in series, continuing to transfer energy to the excitation inductor L m , the magnetizing inductor current i Lm and leakage inductance current i Lk Linearly rising together; DC input voltage source V g The input inductor L1 continues to be charged through the power switch tube S2, and the input inductor current i Lin Linear rise; when the switch trigger pulse signal is at the falling edge, mode 2 ends.

6. The quadratic ultra-high gain DC-DC converter based on coupled inductance according to claim 4, characterized in that: The operation mode of the mode 3 is specifically as follows: When the switch trigger pulse signal is at the falling edge, mode 3 begins; the power switches S1 and S2 are turned off, and capacitor C2 clamps the voltage stress across the power switch S2 to the capacitor C2 voltage V C2 ; diodes D1, D2, D3 and D o In the on state, the diode D4 remains off; the input inductor L1 releases energy through the diodes D1 and D2 to charge the capacitors C1 and C2; the capacitor C3 receives the energy released by the primary winding N1 and the secondary winding N2; the DC input voltage source V g , input inductor L1, primary winding N1, secondary winding N2 and secondary winding N3, capacitor C4 are connected in series to load R and capacitor C o Energy is delivered; when the rising edge of the next switch trigger pulse signal arrives, mode 3 ends The equivalent circuit KVL equation of mode 3 is: Where: V L1_OFF 、V N1_OFF 、V N2_OFF 、V N3_OFF Respectively represent the voltages of the input inductor L1 and the three windings N1, N2 and N3 of the coupled inductor in mode 3; V O is the output voltage of the DC-DC converter.

7. The coupled inductor-based quadratic ultra-high gain DC-DC converter according to claim 6, characterized in that: The DC-DC converter voltage gain G is expressed as: Where: D is the duty cycle of the switch trigger pulse signal.

8. The coupled inductor-based quadratic ultra-high gain DC-DC converter according to claim 1, characterized in that: The inductance value range of the input inductor L1 is: Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, λ L1 The ripple factor of the inductor, G is the voltage gain of the converter, f S is the switching frequency of the switch tube.

9. The quadratic ultra-high gain DC-DC converter based on coupled inductors according to claim 1, characterized in that: The excitation inductance L m The inductance range is: Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n1 and n2 are the turns ratio of the three-winding coupled inductor, n1=N2 / N1, n2=N3 / N1, G is the converter voltage gain, f S is the switching frequency of the switch tube.

10. The quadratic ultra-high gain DC-DC converter based on coupled inductors according to claim 1, characterized in that: The capacitor C in the DC-DC converter o The capacitance values ​​of C1, C2, C3, and C4 satisfy the following relationship: Where: D is the duty cycle of the switch trigger pulse signal, R is the resistance of the load resistor, n1 and n2 are the turns ratio of the three-winding coupled inductor, n1=N2 / N1, n2=N3 / N1, G is the converter voltage gain, f S is the switching frequency of the switch tube, λ C is the capacitor voltage ripple factor.

Images