Boost conversion device with passive lossless snubber

Abstract

A boost converter with passive lossless snubber, comprising a boost converter and a passive lossless snubber, the passive lossless snubber comprising an input unidirectional conducting element, a resonant inductor, a resonant capacitor and an output unidirectional conducting element. The present application can solve the problem of poor energy conversion efficiency of hard switching boost converter and complex structure of soft switching boost converter.

Description

TECHNICAL FIELD

[0001] The present application relates to a boost converter with a passive lossless snubber. BACKGROUND

[0002] A hard-switching boost converter in the prior art produces a significant overlapping area of voltage and current on a voltage and current waveform when a switch is switched, and the overlapping area of voltage and current is a switching loss of the switch, which reduces the energy conversion efficiency and increases the temperature of the components.

[0003] Later, a soft-switching boost converter in the prior art is proposed to reduce the above-mentioned overlapping area of voltage and current, thereby reducing the energy loss; the soft-switching boost converter in the prior art reduces the switching loss by slowing down the rising slope or falling slope of the switch voltage or the switch current; however, the soft-switching boost converter in the prior art has the disadvantages of too many components and a complex structure.

[0004] In summary, the energy conversion efficiency of the hard-switching boost converter in the prior art is poor, and the structure of the soft-switching boost converter in the prior art is complex. SUMMARY

[0005] To solve the above-mentioned problems, the present application aims to provide a boost converter with a passive lossless snubber.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solution: a boost converter with a passive lossless snubber comprises:

[0007] a boost converter; and

[0008] a passive lossless snubber, which is electrically connected to the boost converter,

[0009] wherein the passive lossless snubber comprises:

[0010] an input unidirectional conduction component, which is electrically connected to the boost converter;

[0011] a resonant inductor, which is electrically connected to the input unidirectional conduction component;

[0012] a resonant capacitor, which is electrically connected to the boost converter and the resonant inductor; and

[0013] an output unidirectional conduction component, which is electrically connected to the boost converter, the resonant inductor and the resonant capacitor.

[0014] As preferred, the boost converter comprises:

[0015] a first inductor electrically connected to the input unidirectional conducting element and the resonant capacitor;

[0016] a first transistor switch electrically connected to the first inductor and the resonant capacitor;

[0017] a switch controller electrically connected to the first transistor switch; and

[0018] a first diode electrically connected to the first transistor switch, the first inductor, the resonant capacitor and the output unidirectional conducting element.

[0019] As preferred, when the boost converter with passive lossless snubber enters a first operation stage, the switch controller is configured to turn on the first transistor switch, and the first inductor is configured to be excited by the input voltage to store electrical energy in the form of magnetic field, and a first inductor current flowing through the first inductor gradually increases, and the resonant inductor and the resonant capacitor are configured to be charged by the input voltage and resonate, and then the boost converter with passive lossless snubber is configured to enter a second operation stage.

[0020] As preferred, when the boost converter with passive lossless snubber enters the second operation stage, the switch controller is configured to keep the first transistor switch on, and the first inductor is configured to continue to be excited by the input voltage to store the electrical energy in the form of the magnetic field, and the first inductor current flowing through the first inductor continues to increase, and the resonant inductor and the resonant capacitor are configured to continue to be charged by the input voltage and resonate, and the input unidirectional conducting element is configured to make the resonant inductor and the resonant capacitor stop resonating every half cycle of resonance, so that the resonant capacitor voltage is twice the input voltage, and the resonant inductor current flowing through the resonant inductor is zero, and then the boost converter with passive lossless snubber is configured to enter a third operation stage.

[0021] As preferred, when the boost converter with passive lossless snubber enters the third operation stage, the switch controller is configured to turn off the first transistor switch, and a parasitic capacitance of the first transistor switch is configured to be charged by the first inductor current from zero volt, so that a drain-source voltage of the first transistor switch is gradually increased, and the resonant capacitor is configured to discharge, so that the output unidirectional conduction element is configured to be forward biased on, and the resonant capacitor voltage is discharged from twice the input voltage to zero volt, and the drain-source voltage of the first transistor switch plus the resonant capacitor voltage of the resonant capacitor equals an output voltage of an output terminal, and when the resonant capacitor voltage of the resonant capacitor is discharged to zero volt, the first diode is configured to be forward biased on by the first inductor current, and then the boost converter with passive lossless snubber is configured to enter a fourth operation stage.

[0022] As preferred, when the boost converter with passive lossless snubber enters the fourth operation stage, the switch controller is configured to keep turning off the first transistor switch, and the first diode is configured to continue to be forward biased on by the first inductor current, and an input unidirectional conduction current flowing through the input unidirectional conduction element is zero, and the resonant inductor current flowing through the resonant inductor is zero, and a resonant capacitor current flowing through the resonant capacitor is zero, and an output unidirectional conduction current flowing through the output unidirectional conduction element is zero, and the electrical energy stored in the magnetic field form of the first inductor is transferred to the output terminal in the form of current, and the first inductor current flowing through the first inductor is gradually reduced.

[0023] As preferred, the boost converter further comprises:

[0024] an input capacitor electrically connected to the input unidirectional conduction element and the first inductor.

[0025] As preferred, the boost converter further comprises:

[0026] an output capacitor electrically connected to the output unidirectional conduction element and the first diode.

[0027] As preferred, the input unidirectional conduction element is a diode; the output unidirectional conduction element is a diode.

[0028] As preferred, the first transistor switch is a metal oxide semiconductor field effect transistor; the switch controller is a pulse width modulation signal controller.

[0029] The present application has the effect of reducing the switching loss of a boost converter and reducing electromagnetic interference by using a buffer with a simple structure. The present application can absorb a spike after the switch of a boost converter is turned off and slow the rising slope of the switch cross voltage to reduce the electromagnetic interference emission strength caused by the high voltage slope, thereby reducing the switching loss (i.e., the overlapping area of the switch voltage and the switch current on the voltage and current waveform chart) when the switch is turned off. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A block diagram of an embodiment of a boost conversion device with a passive lossless buffer of the present application.

[0031] Figure 2 A block diagram of a first action stage of a boost conversion device with a passive lossless buffer of the present application.

[0032] Figure 3 A block diagram of a second action stage of a boost conversion device with a passive lossless buffer of the present application.

[0033] Figure 4 A block diagram of a third action stage of a boost conversion device with a passive lossless buffer of the present application.

[0034] Figure 5 A block diagram of a fourth action stage of a boost conversion device with a passive lossless buffer of the present application.

[0035] Figure 6 A waveform diagram of a first action stage to a fourth action stage of a boost conversion device with a passive lossless buffer of the present application.

[0036] Figure 7 A block diagram of another embodiment of a boost conversion device with a passive lossless buffer of the present application.

[0037] Figure: 10 boost converter with passive lossless snubber, 102 boost converter, 104 passive lossless snubber, 106 switch controller, 108 output, 110 input, C1 input capacitor, C2 resonant capacitor, C3 output capacitor, Coss1 parasitic capacitance, D1 first diode, D2 output unidirectional element, D3 input unidirectional element, iC2 resonant capacitor current, iD1 first diode current, iD2 output unidirectional current, iD3 input unidirectional current, ids1 drain-source current, iL1 first inductor current, iL1_pk first inductor peak current, iL1_vly first inductor valley current, iL2 resonant inductor current, L1 first inductor, L2 resonant inductor, Q1 first transistor switch, t0 zero time point, t1 first time point, t2 second time point, t3 third time point, vC2 resonant capacitor voltage, vds1 drain-source voltage, vgs1 gate-source voltage, Vin input voltage, vL1 first inductor voltage, vL2 resonant inductor voltage, Vo output voltage, XC2 resonant capacitor reactance, XL2 resonant inductor reactance DETAILED DESCRIPTION

[0038] In this embodiment, many specific details are provided to provide a thorough understanding of the embodiments of the present application; however, one skilled in the relevant art will recognize that the application can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures and functions have not been shown or described in order to avoid obscuring the application. Reference will now be made to the drawings to describe the detailed composition, and specific details, of the application.

[0039] Reference will now be made to the drawings to describe the detailed composition, and specific details, of the application. Figure 1 The boost converter 10 includes a boost converter 102 and a passive lossless snubber 104. The boost converter 102 includes a first inductor L1, a first transistor switch Q1, a switch controller 106, a first diode D1, an input capacitor C1, and an output capacitor C3. The passive lossless snubber 104 includes an input unidirectional element D3, a resonant inductor L2, a resonant capacitor C2, and an output unidirectional element D2. The elements are electrically connected to each other. The first transistor switch Q1 can be, for example, but is not limited to, a metal oxide semiconductor field effect transistor. The switch controller 106 can be, for example, but is not limited to, a pulse width modulation signal controller. The input unidirectional element D3 can be, for example, but is not limited to, a diode. The output unidirectional element D2 can be, for example, but is not limited to, a diode.

[0040] The boost converter 10 includes four operation stages, which are described as follows.

[0041] Referring to Figure 2 wherein the dotted arrow is the current direction; and referring to Figure 1 When the boost converter with passive lossless snubber 10 enters the first operation stage, the switch controller 106 is configured to turn on the first transistor switch Q1, and the first inductor L1 is configured to be magnetized by an input voltage Vin to store energy in the form of a magnetic field, and a first inductor current iL1 flowing through the first inductor L1 gradually increases, and the resonant inductor L2 and the resonant capacitor C2 are configured to be charged by the input voltage Vin and resonate, and then the boost converter with passive lossless snubber 10 is configured to enter the second operation stage.

[0042] Referring to Figure 3 wherein the dotted arrow is the current direction; and referring to Figure 1 When the boost converter with passive lossless snubber 10 enters the second operation stage, the switch controller 106 is configured to keep the first transistor switch Q1 on, and the first inductor L1 is configured to continue to be magnetized by the input voltage Vin to store energy in the form of the magnetic field, and the first inductor current iL1 flowing through the first inductor L1 continues to increase, and the resonant inductor L2 and the resonant capacitor C2 are configured to continue to be charged by the input voltage Vin and resonate, and the input unidirectional conduction element D3 is configured to make the resonant inductor L2 and the resonant capacitor C2 stop resonating every half cycle of resonance, so that the resonant capacitor voltage vC2 of the resonant capacitor C2 is twice the input voltage Vin, and the resonant inductor current iL2 flowing through the resonant inductor L2 is zero, and then the boost converter with passive lossless snubber 10 is configured to enter the third operation stage.

[0043] Referring to Figure 4 wherein the dotted arrow is the current direction; and referring to Figure 1When the boost converter with passive lossless snubber 10 enters the third operational phase, the switch controller 106 is configured to turn off the first transistor switch Ql, and a parasitic capacitance Cossl of the first transistor switch Ql is configured to be charged from zero volts by the first inductor current iLl, so that a drain-source voltage vds l of the first transistor switch Ql gradually increases, and the resonant capacitor C2 is configured to discharge, so that the output unidirectional conduction element D2 is configured to be forward biased on, and a resonant capacitor voltage vC2 of the resonant capacitor C2 discharges from twice the input voltage Vin to zero volts, and the drain-source voltage vds l of the first transistor switch Ql plus the resonant capacitor voltage vC2 of the resonant capacitor C2 equals an output voltage Vo of an output 108, and when the resonant capacitor voltage vC2 of the resonant capacitor C2 discharges to zero volts, the first diode Dl is configured to be forward biased on by the first inductor current iLl, and then the boost converter with passive lossless snubber 10 is configured to enter a fourth operational phase.

[0044] Please refer to Figure 5 wherein the dashed arrow is the current direction; and please refer to Figure 1 When the boost converter with passive lossless snubber 10 enters the fourth operational phase, the switch controller 106 is configured to keep the first transistor switch Ql turned off, and the first diode Dl is configured to continue to be forward biased on by the first inductor current iLl, and an input unidirectional conduction current iD3 flowing through the input unidirectional conduction element D3 is zero, and the resonant inductor current iL2 flowing through the resonant inductor L2 is zero, and a resonant capacitor current iC2 flowing through the resonant capacitor C2 is zero, and an output unidirectional conduction current iD2 flowing through the output unidirectional conduction element D2 is zero, and the first inductor Ll transfers the electrical energy stored in the magnetic field form to the output 108 in the current form, and the first inductor current iLl flowing through the first inductor Ll gradually decreases.

[0045] Please refer to Figure 6 and please refer to Figures 1 to 5For ease of illustration, the present application assumes that the above-mentioned elements are ideal, and the forward voltage of the diodes is zero volt. In addition to the above-mentioned element symbols, the first transistor switch Q1 has a gate-source voltage vgs1, the current flowing through the first diode D1 is referred to as the first diode current iD1, the current flowing through the first transistor switch Q1 is referred to as the drain-source current ids1, the first inductor L1 has a first inductor voltage vL1, the resonant inductor L2 has a resonant inductor voltage vL2, the peak current of the first inductor current iL1 is a first inductor peak current iL1_pk, the valley current of the first inductor current iL1 is a first inductor valley current iL1_vly, the resonant inductor L2 has a resonant inductor reactance XL2, the resonant capacitor C2 has a resonant capacitor reactance XC2, the first operation stage is between the zero time point t0 and the first time point t1, the second operation stage is between the first time point t1 and the second time point t2, the third operation stage is between the second time point t2 and the third time point t3, and the fourth operation stage is between the third time point t3 and the zero time point t0.

[0046] Further, the elements shown in Figure 7 , Figure 7 are the same as those shown in Figures 1 to 6 , and their descriptions are not repeated here for brevity. One end of the resonant inductor L2 is directly connected to the input terminal 110, the other end of the resonant inductor L2 is directly connected to the anode of the input terminal unidirectional conduction element D3, and the cathode of the input terminal unidirectional conduction element D3 is directly connected to the output terminal unidirectional conduction element D2 and the resonant capacitor C2.

[0047] The present application reduces the switching loss of the boost converter and reduces electromagnetic interference by using a buffer with a simple structure. The present application can absorb spikes after the switch of the boost converter is turned off and slow down the rising slope of the switch voltage to reduce the electromagnetic interference emission strength caused by the high voltage slope, thereby reducing the switching loss (i.e., the overlapping area of the switch voltage and the switch current on the voltage and current waveform diagram) when the switch is turned off; the input terminal unidirectional conduction element D3, the resonant inductor L2, the resonant capacitor C2, and the output terminal unidirectional conduction element D2 included in the passive lossless buffer 104 do not participate in the processing of the main power and are not in the power transmission path, so the passive lossless buffer 104 only needs very low element rated power, thus the present application can reduce the element size and additional cost. According to experimental data, compared with the traditional RCD buffer, the present application can reduce the switching loss by more than 1% and reduce electromagnetic interference under the same peripheral element parameters and full load efficiency.

[0048] The above-described are only preferred embodiments of the present application, and cannot limit the scope of the present application, i.e. any equivalent changes and modifications made according to the claims of the present application shall still belong to the scope of the present application. The present application can also have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications shall belong to the protection scope of the claims of the present application. In summary, the present application has industrial applicability, novelty and progressiveness, and the structure of the present application has not been seen in similar products and public use, and fully meets the requirements of the patent application, and therefore, the present application is applied according to the Patent Law.

Claims

1. A boost conversion device with passive lossless snubber, characterized by It comprises: a boost converter; and a passive lossless buffer electrically connected to the boost converter, wherein the passive lossless buffer comprises: an input unidirectional conducting element electrically connected to the boost converter; a resonant inductor electrically connected to the input unidirectional conducting element; a resonant capacitor electrically connected to the boost converter and the resonant inductor; and an output unidirectional conducting element electrically connected to the boost converter, the resonant inductor and the resonant capacitor; the boost converter comprises: a first inductor electrically connected to the input unidirectional conducting element and the resonant capacitor; a first transistor switch electrically connected to the first inductor and the resonant capacitor; a switch controller electrically connected to the first transistor switch; and a first diode electrically connected to the first transistor switch, the first inductor, the resonant capacitor and the output unidirectional conducting element; when the boost converter with passive lossless buffer enters a first operation stage, the switch controller is configured to turn on the first transistor switch, and the first inductor is configured to be excited by an input voltage to store electrical energy in the form of a magnetic field, and a first inductor current flowing through the first inductor gradually increases, and the resonant inductor and the resonant capacitor are configured to be charged by the input voltage and resonate, and then the boost converter with passive lossless buffer is configured to enter a second operation stage; when the boost converter with passive lossless buffer enters the second operation stage, the switch controller is configured to keep the first transistor switch on, and the first inductor is configured to continue to be excited by the input voltage to store the electrical energy in the form of the magnetic field, and the first inductor current flowing through the first inductor continues to increase, and the resonant inductor and the resonant capacitor are configured to continue to be charged by the input voltage and resonate, and the input unidirectional conducting element is configured to make the resonant inductor and the resonant capacitor stop resonating every half cycle of resonance, so that a resonant capacitor voltage of the resonant capacitor is twice the input voltage, and a resonant inductor current flowing through the resonant inductor is zero, and then the boost converter with passive lossless buffer is configured to enter a third operation stage. ​ ​ 2. The boost conversion device with passive lossless snubber according to claim 1, wherein: When the boost converter with passive lossless snubber enters the third operational phase, the switch controller is configured to turn off the first transistor switch, and a parasitic capacitance of the first transistor switch is configured to be charged from zero volts by the first inductor current, such that a drain-source voltage of the first transistor switch is gradually increased, and the resonant capacitor is configured to discharge, such that the output unidirectional conduction element is configured to conduct in forward bias, and the resonant capacitor voltage discharges from twice the input voltage to zero volts, and the drain-source voltage of the first transistor switch plus the resonant capacitor voltage of the resonant capacitor equals an output voltage of an output terminal, and when the resonant capacitor voltage of the resonant capacitor discharges to zero volts, the first diode is configured to conduct in forward bias by the first inductor current, and then the boost converter with passive lossless snubber is configured to enter a fourth operational phase.

3. The boost conversion device with passive lossless snubber according to claim 2, wherein: When the boost converter with passive lossless snubber enters the fourth operational phase, the switch controller is configured to keep the first transistor switch turned off, and the first diode is configured to continue to conduct in forward bias by the first inductor current, and an input unidirectional conduction current through the input unidirectional conduction element is zero, and the resonant inductor current through the resonant inductor is zero, and a resonant capacitor current through the resonant capacitor is zero, and an output unidirectional conduction current through the output unidirectional conduction element is zero, and the electrical energy stored in the magnetic field form of the first inductor is transferred to the output in the form of current, and the first inductor current through the first inductor is gradually decreased.

4. The boost conversion device with passive lossless snubber according to claim 3, wherein: The boost converter further comprises: an input capacitor electrically connected to the input unidirectional conduction element and the first inductor.

5. The boost conversion device with passive lossless snubber of claim 3, wherein: The boost converter further comprises: an output capacitor electrically connected to the output unidirectional conduction element and the first diode.

6. The boost conversion device with passive lossless snubber according to claim 5, wherein: The input unidirectional conduction element is a diode; the output unidirectional conduction element is a diode.

7. The boost conversion device with passive lossless snubber according to claim 6, wherein: The first transistor switch is a metal oxide semiconductor field effect transistor; the switch controller is a pulse width modulation signal controller.

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