High-gain DC / DC converter based on coupling inductor

Abstract

The invention provides a high-gain DC / DC converter based on a coupling inductor. The high-gain DC / DC converter can convert input low-voltage direct-current voltage into high-voltage direct-current voltage of another grade to be output. The invention discloses a high-gain DC / DC converter based on a coupling inductor. The high-gain DC / DC converter comprises a DC input power supply Vin, a switching tube S, a coupling inductor unit, a clamping capacitor C1, a first energy storage capacitor C2, a second energy storage capacitor C3, a first diode D1, a second diode D2, a third diode D3, an output diode Do and a load unit. High output voltage gain of the converter is realized through the characteristics of parallel charging and series discharging of a different-stage CLC coupling inductor voltage-multiplying unit composed of a coupling inductor unit and energy storage capacitors C2 and C3, and meanwhile, a passive clamping circuit is arranged through a clamping capacitor C1 to absorb energy released by primary side leakage inductance of a coupling inductor at the moment of switching-off of a switching tube. And the voltage stress of the switching tube is reduced. According to the scheme provided by the invention, the different-stage CLC coupling inductor voltage-multiplying unit and the passive clamping circuit clamped to the ground are combined into a whole, the freewheeling diode is additionally arranged in one branch of the different-stage CLC coupling inductor voltage-multiplying unit, the freewheeling loop is arranged for the clamping capacitor, energy released by the primary side leakage inductance of the coupling inductor is recycled, and the energy utilization rate is improved. While the voltage stress of the switching tube is relieved, the output voltage gain of the converter is further improved. The high-gain DC / DC converter based on the coupling inductor has higher output voltage gain, the output voltage can be further improved by changing the turn ratio of the coupling inductor, and the high-gain DC / DC converter based on the coupling inductor has the potential that the high-gain DC / DC converter based on the coupling inductor can meet the requirement for higher output voltage.

Description

Technical Field

[0001] The invention relates to the field of non-isolated high-gain DC / DC converters, and in particular to a high-gain DC / DC converter based on coupled inductors. Background Art

[0002] Theoretically, the gain of a traditional Boost converter can be infinite when its duty cycle approaches 1. However, in actual engineering applications, when the duty cycle approaches 1, the reverse recovery problem of the diode and the parasitic parameters of the inductor, capacitor and switch will have a serious impact on the working performance of the converter, such as causing large input current ripple and large component current stress. Its voltage gain is very limited, so it is usually used in various low-power boost occasions.

[0003] At present, the main development directions of non-isolated high-gain DC / DC converters include: cascade type, multi-level type, switched inductor capacitor type and coupled inductor type. Due to the step-by-step boost characteristics of cascade high-gain DC converters, the voltage stress of the subsequent circuit of this type of converter is relatively large, and it is not easy to work under high frequency conditions; multi-level boost high-gain DC converters have high flexibility and scalability, but with this comes an increase in the number of devices, increased losses, and a more complex control circuit, which is not conducive to improving the stability of the converter; the switched inductor capacitor type high-gain DC converter achieves gain improvement by adding a switched capacitor voltage doubling unit, so its output voltage cannot be continuously adjusted, and can only be an integer multiple of the switched capacitor voltage doubling unit, which is difficult to promote in actual engineering applications.

[0004] In comparison, the output voltage gain of the coupled inductor high-gain DC converter is controlled not only by the turns ratio but also by the duty cycle of the switch tube, which can achieve continuous output voltage regulation and has a transformer-like boost potential. It can also be combined with boost technologies such as switching inductors to achieve higher voltage gain. However, the coupled inductor high-gain DC converter also has problems such as high voltage stress of the switching device and voltage spikes.

[0005] Therefore, it is necessary to further improve the circuit topology of the high-gain DC / DC converter to achieve a higher output voltage gain while alleviating the voltage stress of the switching device. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a high-gain DC / DC converter based on coupled inductors, wherein the high-gain DC / DC converter based on coupled inductors has higher voltage gain and lower switch tube voltage stress, and comprises: a DC input power supply V in, switch tube S, coupled inductor unit, clamping capacitor C1, first energy storage capacitor C2, second energy storage capacitor C3, first diode D1, second diode D2, third diode D3, output diode D o , and a load unit. The coupled inductor unit includes a primary magnetizing inductor L m and a secondary inductor L2, the heterogeneous CLC coupled inductor voltage multiplier unit includes a secondary inductor L2, a first energy storage capacitor C2, a second energy storage capacitor C3, a second diode D2 and a third diode D3, the passive clamping circuit includes a first diode D1 and a clamping capacitor C1, and the load unit includes an output voltage stabilizing capacitor C o and resistor R.

[0007] The DC input power supply V in The positive pole of the coupled inductor unit is connected to the primary magnetizing inductance L m One end of the magnetizing inductor L m The other end of the secondary inductor L2 is connected to one end of the second energy storage capacitor C3 and the cathode of the second diode D2, and the other end of the second energy storage inductor C3 is connected to the cathode of the third diode D3 and the output diode D o The positive pole of the output diode D o The cathode of the first diode D1 is connected to one end of the load unit, the cathode of the first diode D1 is connected to one end of the clamp capacitor C1 and the anode of the second diode D2, and the other end of the load unit is respectively connected to the other end of the clamp capacitor C1, the other end of the switch tube S and the DC input power supply V in negative connection.

[0008] Furthermore, one end of the clamping capacitor C1 is connected to the cathode of the first diode D1 and the anode of the second diode D2 respectively, and the other end is connected to the drain of the switch tube S.

[0009] Furthermore, the source of the switch tube S and the coupling inductor are connected to the magnetic inductor L. m One end of the first energy storage capacitor C2 is connected to the positive electrode of the first diode D1, and the magnetizing inductor L m The other end is connected to the DC input power supply V in positive connection.

[0010] Furthermore, one end of the secondary inductor L2 is respectively connected to one end of the first energy storage capacitor C2 and the anode of the third diode D3, and the other end of the secondary inductor L2 is respectively connected to the cathode of the second diode D2 and one end of the second energy storage capacitor C3.

[0011] Furthermore, one end of the second energy storage capacitor C3 is connected to one end of the secondary inductor L2 and the cathode of the second diode D2, and the other end of the energy storage capacitor C3 is connected to the cathode of the third diode D3 and the output diode D o positive connection.

[0012] Furthermore, one end of the load unit is connected to the output diode D o The negative electrode of the switch is connected to the other end of the clamp capacitor C1, the drain of the switch tube S and the DC input power supply V in negative connection.

[0013] Furthermore, the number of turns of the primary side of the coupled inductor is denoted by n1, and the number of turns of the secondary side is denoted by n2, then the turns ratio of the coupled inductor is n1:n2, which is simplified to 1:n, where n=n2 / n1.

[0014] Furthermore, the output voltage gain is (2+nk) / (1-D)+nk+D(1-k)(n-1) / (1-D), and the output voltage gain of the improved gain DC / DC converter can be adjusted by changing the coupled inductor turns ratio n and the duty cycle D.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] DC input power supply V in The positive pole of the coupled inductor unit is connected to the primary magnetizing inductance L m One end of the magnetizing inductor L m The other end of the secondary inductor L2 is connected to one end of the second energy storage capacitor C3 and the cathode of the second diode D2, and the other end of the second energy storage inductor C3 is connected to the cathode of the third diode D3 and the output diode D o The positive pole of the output diode D o The cathode of the first diode D1 is connected to one end of the load unit, the cathode of the first diode D1 is connected to one end of the clamp capacitor C1 and the anode of the second diode D2, and the other end of the load unit is respectively connected to the other end of the clamp capacitor C1, the other end of the switch tube S and the DC input power supply V inThe high-gain DC / DC converter based on coupled inductance proposed in the present invention can achieve a higher output voltage gain by charging in parallel and discharging in series through the heterogeneous CLC coupled inductance voltage doubling unit composed of the secondary inductor L2, the first energy storage capacitor C2 and the second energy storage capacitor C3; a passive clamping circuit clamped to the ground is provided to weaken the voltage spike and relieve the voltage stress of the switch tube; at the same time, the heterogeneous CLC coupled inductance voltage doubling unit is combined with the passive clamping circuit, and a freewheeling diode is provided to recycle the energy released by the primary leakage inductance of the coupled inductor absorbed in the clamping capacitor, relieve the voltage stress of the switch tube, and further improve the output voltage gain. When the duty cycle D=0.72 and the coupled inductor turns ratio n=1, the voltage gain can reach about 12. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic diagram of a circuit topology structure of a coupled-inductor-based passive clamped heterogeneous CLC high-gain DC / DC converter provided in Embodiment 1 of the present disclosure;

[0019] Figure 2 A schematic diagram of the main working modes of a coupled-inductor-based passive clamped heterogeneous CLC high-gain DC / DC converter in one switching cycle provided in the second embodiment of the present disclosure;

[0020] Figure 3 A topology structure of a rear-stage interleaved parallel passive clamped heterogeneous CLC high-gain DC / DC converter based on coupled inductors is provided in Embodiment 3 of the present disclosure, that is, a schematic diagram of the rear-stage interleaved parallel topology structure of the circuit topology described in Claim 1. DETAILED DESCRIPTION

[0021] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0022] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0023] refer to Figure 1 The first embodiment of the present disclosure provides a coupled inductor-based passive clamped heterogeneous CLC high-gain DC / DC converter, comprising: a DC input power supply V in , switch tube S, coupled inductor unit, clamping capacitor C1, first energy storage capacitor C2, second energy storage capacitor C3, first diode D1, second diode D2, third diode D3, output diode D o , and load cells;

[0024] The coupled inductor unit includes a primary magnetizing inductor L m and a secondary inductor L2, the heterogeneous CLC coupled inductor voltage multiplier unit includes a secondary inductor L2, a first energy storage capacitor C2, a second energy storage capacitor C3, a second diode D2 and a third diode D3, the passive clamping circuit includes a first diode D1 and a clamping capacitor C1, and the load unit includes an output voltage stabilizing capacitor C o and resistor R.

[0025] The DC input power supply V in The positive pole of the coupled inductor unit is connected to the primary magnetizing inductance L m One end of the magnetizing inductor L m The other end of the secondary inductor L2 is connected to one end of the second energy storage capacitor C3 and the cathode of the second diode D2, and the other end of the second energy storage inductor C3 is connected to the cathode of the third diode D3 and the output diode D o The positive pole of the output diode D o The cathode of the first diode D1 is connected to one end of the load unit, the cathode of the first diode D1 is connected to one end of the clamp capacitor C1 and the anode of the second diode D2, and the other end of the load unit is respectively connected to the other end of the clamp capacitor C1, the other end of the switch tube S and the DC input power supply V in negative connection.

[0026] refer to Figure 2 The second embodiment of the present disclosure provides a main working mode of a passive clamped heterogeneous CLC high-gain DC / DC converter based on coupled inductors in one switching cycle, including:

[0027] Mode 1 [t0, t1]: At t = t0, the switch tube S is turned on, the diodes D1, D2 and D3 are reverse biased and turned off, and the diode D o Forward bias conduction. The current flow path is as follows Figure 2 (a) shows. The primary current i of the coupled inductor is Lk Linear increase, secondary current i s Linearly decrease. When the secondary current i s When the diode D o Turn off, and the energy discharge ends. m Start with a DC power supply V in At the same time, diodes D2 and D3 start to conduct, and the secondary side of the coupled inductor starts to charge the dual voltage boost capacitors C2 and C3. When t = t1, the primary current i Lk Equal to i Lm +ni s , this working mode ends.

[0028] Mode 2 [t1, t2]: During this time interval, the switch tube S is turned on, and the diodes D1 and D o The current flow path is as follows: Figure 2 (b) shows. Magnetizing inductance L m Through the DC power supply V in At the same time, the secondary winding N of the coupled inductor s The voltage V s It is connected in series with the clamp capacitor C1 to charge the capacitor C2. s The capacitor C3 is connected in parallel with the capacitor C3 and the dual voltage boost capacitors C2 and C3 are charged at the same time. o Energy is continuously provided to the load R. When t=t2, the switch tube S is turned off, and the working mode ends.

[0029] Mode 3 [t2, t3]: During this time interval, the switch S is turned off, and the diodes D1 and D o The current flow path is as follows: Figure 2 (c) shows the leakage inductance L in the coupled inductor equivalent model. k and magnetizing inductance L m The parasitic capacitance C of the switch tube S ds The dual voltage boost capacitors C2 and C3 are still charged. o Continuously provide energy to the load R. When t = t3, the voltage V on the clamping capacitor C1 C1 Equal to V ds When , diode D1 is turned on and the working mode ends.

[0030] Mode 4 [t3, t4]: At t = t3, the switch tube S is in the off state, the diodes D1 and D3 are turned on, and D2 and D o The current flow path is as follows Figure 2 (d) As shown. The parasitic capacitance of the switch tube C ds The voltage across the two ends is V ds Greater than the voltage V across the clamp capacitor C1 C1 , the charge flows from the parasitic capacitor to the clamping capacitor C1. Intuitively, it can be understood that at this time, the leakage inductance L in the coupled inductor equivalent model k and magnetizing inductance L m When charging the clamp capacitor C1, the energy of the leakage inductance can be recycled through the clamp capacitor C1. Lk Rapidly decreases, the secondary current i s When t = t4, the secondary current i s When the voltage drops to zero, the dual voltage boost capacitors C2 and C3 are fully charged, the diode D3 is turned off, and the diode D o The working mode ends.

[0031] Mode 5 [t4, t5]: During this time interval, the switch tube S is in the off state, and the diodes D1 and D o The current flow path is as follows: Figure 2 (e) At t = t4, the leakage inductance L in the coupled inductor equivalent model k and magnetizing inductance L m When charging the clamp capacitor C1, the voltage stress of the switch tube S is well limited. At the same time, the magnetizing inductor L m Part of the energy is released through the secondary side of the coupled inductor, and the diode D o The secondary winding N s The voltage V s With the input DC power supply voltage V in , primary winding N p The voltage V p , dual voltage boost capacitors C2 and C3 voltage V C2 、V C3 in series, and at the same time the output capacitor C o The load R is charged and a higher output voltage gain is achieved through the idea of ​​series discharge. When t = t5, the secondary winding N s The voltage V s Equal to nV p When , the working mode ends.

[0032] Mode 6 [t5, t6]: During this time interval, switch S is in the off state, and diodes D1 and D oThe current flow path is as follows: Figure 2 As shown in (e), the magnetizing inductance L m The energy stored in the input DC power supply V in , capacitors C1, C2, C3 and magnetizing inductor L m At the same time, the output capacitor C o and load R. When t=t6, the switch tube S is turned on again in the next switching cycle, and this working mode ends.

[0033] When the switch tube S is turned on, there is:

[0034]

[0035]

[0036] Among them, v p is the voltage across the primary inductor of the coupled inductor, L k is the leakage inductance value in the coupled inductor equivalent model, L m is the magnetizing inductance value in the coupled inductor equivalent model, k = L m / (L m +L k ) is the coupling coefficient of the coupled inductor, V in is the DC input power supply voltage, V C3 is the voltage of the second energy storage capacitor, v s is the voltage across the secondary inductor of the coupled inductor, and n is the turns ratio of the coupled inductor.

[0037] When the switch tube S is turned off,

[0038]

[0039]

[0040] Among them, v Lk is the voltage across the leakage inductance in the coupled inductor equivalent model, V C1 is the voltage across the clamp capacitor C1, v ds is the voltage across the switch tube S, V C2 is the voltage across the first energy storage capacitor C2, V o is the output voltage.

[0041] Therefore, the voltage gain of the high-gain DC / DC converter based on coupled inductance is:

[0042]

[0043] It can be seen from the above formula that, compared with the traditional Boost converter, the high-gain DC / DC converter based on coupled inductors has a higher output voltage gain, and the output voltage can be further increased by changing the turns ratio of the coupled inductors, which has the potential to meet higher output voltage requirements.

[0044] The above-mentioned Mode 2, Mode 3 and Mode 4 reflect that the coupled inductor high-gain DC / DC converter described in this example combines the heterogeneous CLC coupled inductor voltage doubler unit with the passive clamping circuit clamped to the ground, adds a freewheeling diode in a branch of the heterogeneous CLC coupled inductor voltage doubler unit, sets a freewheeling loop for the clamping capacitor, and recycles the energy released by the primary leakage inductance of the coupled inductor, thereby achieving the effect of weakening the voltage spike problem, alleviating the voltage stress of the switch tube, and further improving the output voltage gain of the converter.

[0045] refer to Figure 3 , a topology structure of a rear-stage interleaved parallel passive clamped heterogeneous CLC high-gain DC / DC converter based on coupled inductors provided in Embodiment 3 of the present disclosure, that is, a schematic diagram of a rear-stage interleaved parallel topology structure of the circuit topology described in Claims 1-9;

[0046] This embodiment is an extended structure of a high-gain DC / DC converter based on coupled inductors according to claims 1-9, that is, a post-stage interleaved parallel structure of the circuit topology according to claims 1-9, characterized in that the converter adopts an interleaved parallel circuit topology structure, including at least two interleaved coupled high-gain DC / DC conversion units, each of which includes the converter structure according to claims 1 and 2. Each high-gain DC / DC conversion unit is connected in an interleaved parallel manner, that is, the primary magnetizing inductance L of the coupled inductor in each unit is m One end is connected to the DC input power supply V in The positive electrodes of the switches S in each unit are connected together, and the drain electrodes of the switches S in each unit are connected to the DC input power supply V in The negative poles of each unit are connected together, and the output diode D o They are all connected to one end of the load unit. By connecting multiple units in parallel and staggered conduction, a higher output voltage gain can be achieved, the voltage stress of the switching devices in each unit can be alleviated, and the heat loss of a single unit can be reduced.

[0047] In this embodiment, the post-stage interleaved parallel topology structure includes but is not limited to a two-phase circuit, which is realized by at least two high-gain DC / DC conversion units connected in parallel and interleaved.

Claims

1. A high-gain DC / DC converter based on coupled inductors, characterized in that: include: DC input power supply V in , switch tube S, coupled inductor unit, clamping capacitor C1, first energy storage capacitor C2, second energy storage capacitor C3, first diode D1, second diode D2, third diode D3, output diode D o , and load cells; The coupled inductor unit includes a primary magnetizing inductor L m and a secondary inductor L2, the heterogeneous CLC coupled inductor voltage multiplier unit includes a secondary inductor L2, a first energy storage capacitor C2, a second energy storage capacitor C3, a second diode D2 and a third diode D3, the passive clamping circuit includes a first diode D1 and a clamping capacitor C1, and the load unit includes an output voltage stabilizing capacitor C o and resistor R.

2. A high-gain DC / DC converter based on coupled inductors, characterized in that DC input power supply V in The positive pole of the coupled inductor unit is connected to the primary magnetizing inductance L m One end of the magnetizing inductor L m The other end of the secondary inductor L2 is connected to one end of the second energy storage capacitor C3 and the cathode of the second diode D2, and the other end of the second energy storage inductor C3 is connected to the cathode of the third diode D3 and the output diode D o The positive pole of the output diode D o The cathode of the first diode D1 is connected to one end of the load unit, the cathode of the first diode D1 is connected to one end of the clamp capacitor C1 and the anode of the second diode D2, and the other end of the load unit is respectively connected to the other end of the clamp capacitor C1, the other end of the switch tube S and the DC input power supply V in negative connection.

3. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: One end of the clamp capacitor C1 is connected to the cathode of the first diode D1 and the anode of the second diode D2 respectively, and the other end is connected to the drain of the switch tube S.

4. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: The source of the switch tube S and the coupling inductor are connected to the magnetic inductor L m One end of the first energy storage capacitor C2 is connected to the positive electrode of the first diode D1, and the magnetizing inductor L m The other end is connected to the DC input power supply V in positive connection.

5. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: One end of the secondary inductor L2 is respectively connected to one end of the first energy storage capacitor C2 and the anode of the third diode D3, and the other end of the secondary inductor L2 is respectively connected to the cathode of the second diode D2 and one end of the second energy storage capacitor C3.

6. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: One end of the second energy storage capacitor C3 is connected to one end of the secondary inductor L2 and the cathode of the second diode D2, and the other end of the energy storage capacitor C3 is connected to the cathode of the third diode D3 and the output diode D o positive connection.

7. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: One end of the load unit is connected to the output diode D o The negative electrode of the switch is connected to the other end of the clamp capacitor C1, the drain of the switch tube S and the DC input power supply V in negative connection.

8. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: The number of turns of the primary side of the coupled inductor is represented by n1, and the number of turns of the secondary side is represented by n2. Then the turns ratio of the coupled inductor is n1:n2, which is simplified to 1:n, where n=n2 / n1.

9. The high-gain DC / DC converter based on coupled inductors according to claim 1, characterized in that: The output voltage gain is (2+nk) / (1-D)+nk+D(1-k)(n-1) / (1-D). The output voltage gain of the improved gain DC / DC converter can be adjusted by changing the coupled inductor turns ratio n and the duty cycle D.

10. The high-gain DC / DC converter based on coupled inductors according to claim 1 or 2, characterized in that: The switch tube S adopts an N-channel MOS tube, and a unipolar PWM control method is used to control the on or off state of the switch tube S.

11. Another extended structure of the high-gain DC / DC converter based on coupled inductors according to claims 1-9, namely, the rear-stage interleaved parallel structure of the circuit topology according to claims 1-9, characterized in that: The converter adopts an interleaved parallel circuit topology structure, including at least two interleaved coupled high-gain DC / DC conversion units, each of which includes the converter structure described in claims 1 and 2. Each high-gain DC / DC conversion unit is connected in an interleaved parallel manner, that is, the primary magnetizing inductance L of the coupled inductor in each unit is m One end is connected to the DC input power supply V in The positive electrodes of the switches S in each unit are connected together, and the drain electrodes of the switches S in each unit are connected to the DC input power supply V in The negative poles of each unit are connected together, and the output diode D o They are all connected to one end of the load unit. By connecting multiple units in parallel and staggered conduction, a higher output voltage gain can be achieved, the voltage stress of the switching devices in each unit can be alleviated, and the heat loss of a single unit can be reduced.

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