An Intermittent Mode DCDC Resonant Converter Based on Fixed Pulse Width

Abstract

The present invention discloses an intermittent-mode DCDC resonant converter based on a fixed pulse width, which relates to the field of switching power supplies and solves the problem of low conversion efficiency of existing resonant converters when used as switching power supplies. The specific solution includes: a control module, a first square-wave module, a transformer module, a resonant module, a second square-wave module, and a rectification module; the control module controls the first square-wave unit and the second square-wave unit of the first square-wave module to alternately operate to generate a square-wave signal; the alternating operation is that when the first square-wave unit conducts for a first preset duration, the first square-wave unit cuts off for a second preset duration, and at the same time the second square-wave unit conducts for the first preset duration, and when the second square-wave unit conducts for the first preset duration, the second square-wave unit cuts off for the second preset duration; the control module also controls the second square-wave module to conduct for a third preset duration when the second square-wave unit conducts for the first preset duration; the third preset duration is the difference between the second preset duration and the first preset duration.

Description

Technical Field

[0001] The present invention relates to the field of switching power supplies, and particularly to an intermittent mode DCDC resonant converter based on a fixed pulse width. Background Art

[0002] With the development of power electronics technology and the rapid improvement of computer technology, resonant converters are increasingly used as core switching power supplies or power operation power supplies.

[0003] Currently, the existing resonant converter is composed of parts such as a switching network, a resonant tank circuit, a rectifying circuit, and a low-pass filtering circuit connected in sequence. Among them, the switching network converts the input DC signal into an AC signal, and the output voltage of the switching network is a square wave power signal; the resonant tank circuit is a linear network with a band-pass characteristic, which is used to process the square wave power signal; the rectifying circuit is a rectifier bridge; the low-pass filtering circuit is an LC low-pass filter. And according to the type of the resonant tank circuit, the resonant converter can be divided into a series resonant converter, a parallel resonant converter, and a series-parallel resonant converter.

[0004] When the existing resonant converter is used as a switching power supply, there are problems of high hard-switching loss and large heat generation, resulting in low conversion efficiency of the switching power supply. Summary of the Invention

[0005] The present invention provides an intermittent mode DCDC resonant converter based on a fixed pulse width, which solves the problem of low conversion efficiency when the existing resonant converter is used as a switching power supply.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides an intermittent mode DCDC resonant converter based on a fixed pulse width, including: a control module, a first square wave module, a transformer module, a resonant module, a second square wave module, and a rectifying module;

[0008] The transformer module includes a primary and a secondary;

[0009] The first square wave module is connected in parallel with the primary; the first square wave module includes a first square wave unit and a second square wave unit;

[0010] The control module is connected to the first square wave unit and the second square wave unit, and is used to control the first square wave unit and the second square wave unit to alternately operate to generate a square wave signal; the alternate operation is that the first square wave unit conducts for a first preset duration and then stops for a second preset duration, and the second square wave unit conducts for the first preset duration after the first square wave unit conducts for the first preset duration, and then stops for the second preset duration;

[0011] The resonant module is connected in series with the secondary, and the resonant period of the resonant module is equal to the first preset duration, which is used to filter out the high-order harmonic current in the output current of the secondary;

[0012] The second square-wave module is connected in parallel with the secondary, and the second square-wave module is connected to the control module;

[0013] The control module is further configured to control the second square-wave module to conduct for a third preset duration when the second square-wave unit conducts for the first preset duration; the third preset duration is the difference between the second preset duration and the first preset duration, and the third preset duration is greater than zero;

[0014] The rectification module is connected in series with the resonant module.

[0015] In a possible implementation manner, a preset voltage is set in the control module;

[0016] The control module is further configured to obtain the output voltage of the rectification module, and adjust the value of the third preset duration according to the magnitude relationship between the output voltage and the preset voltage.

[0017] In a possible implementation manner, the adjusting the value of the third preset duration according to the magnitude relationship between the output voltage and the preset voltage is specifically:

[0018] Obtain the difference between the output voltage and the preset voltage. If the difference is greater than zero, extend the third preset duration until the difference is zero;

[0019] If the difference is less than zero, shorten the third preset duration until the difference is zero.

[0020] In a possible implementation manner, the first square-wave module is any one of a push-pull circuit, a half-bridge circuit or a full-bridge circuit.

[0021] In a possible implementation manner, the first square-wave module is a push-pull circuit;

[0022] The first square-wave unit includes a first push-pull power tube, and the second square-wave unit includes a second push-pull power tube;

[0023] Both the first push-pull power tube and the second push-pull power tube are N-channel field effect transistors;

[0024] The gate of the first push-pull power tube and the gate of the second push-pull power tube are connected to the control module, the source of the first push-pull power tube and the source of the second push-pull power tube are connected, and the drain of the first push-pull power tube and the drain of the second push-pull power tube are respectively connected to both ends of the primary.

[0025] In a possible implementation, the second square-wave module includes a first field-effect transistor and a second field-effect transistor;

[0026] Both the first field-effect transistor and the second field-effect transistor are N-channel field-effect transistors;

[0027] The gate of the first field-effect transistor is connected to the gate of the second field-effect transistor, the source of the first field-effect transistor is connected to the source of the second field-effect transistor, and the drains of the first field-effect transistor and the second field-effect transistor are respectively connected to both ends of the secondary;

[0028] The gates of the first field-effect transistor and the second field-effect transistor are connected to the control module.

[0029] In a possible implementation, the resonant module includes a resonant inductor and a resonant capacitor;

[0030] One end of the resonant inductor is connected to the drain of the first field-effect transistor and one end of the secondary, the other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to the rectification module.

[0031] In a possible implementation, the rectification module includes a rectifier bridge, a freewheeling inductor, and a filter capacitor;

[0032] The rectifier bridge includes a first AC input terminal, a second AC input terminal, a DC output positive terminal, and a DC output negative terminal;

[0033] The first AC input terminal is connected to the resonant capacitor, the second AC input terminal is connected to the drain of the second field-effect transistor and one end of the secondary, the DC output positive terminal is connected to one end of the freewheeling inductor, the other end of the freewheeling inductor is connected to the positive electrode of the filter capacitor, and the negative electrode of the filter capacitor is connected to the DC output negative terminal.

[0034] When the intermittent-mode DCDC resonant converter based on a fixed pulse width provided by an embodiment of the present invention is used as a switching power supply, three pulse-width signals are output by a control module. The first signal controls a first square-wave unit, the second signal controls a second square-wave unit, and the third signal controls a second square-wave module. The first square-wave unit is controlled by the first signal to conduct for a first preset duration and then cut off for a second preset duration. The second square-wave unit is controlled by the second signal to conduct for a first preset duration after the first square-wave unit conducts for the first preset duration, and then cut off for the second preset duration. The second square-wave module is controlled by the third signal to conduct for a third preset duration after the second square-wave unit conducts for the first preset duration, where the third preset duration is the difference between the second preset duration and the first preset duration, and the third preset duration is greater than zero. The common cut-off time of the first square-wave unit and the second square-wave unit is the difference between the second preset duration and the first preset duration, and this difference is greater than zero. Since the first square-wave unit and the second square-wave unit of the resonant converter of the present invention are turned on with a fixed pulse width, the first square-wave module at the primary of the transformer module achieves zero-current switching. Since the resonant period of the resonant module is equal to the first preset duration, the resonant module at the secondary of the transformer module achieves zero-current switching. Since both the first square-wave module and the resonant module achieve zero-current switching, the conversion efficiency of the resonant converter is effectively improved.

[0035] The control module of the intermittent-mode DCDC resonant converter based on a fixed pulse width of the present invention can also adjust the value of the third preset duration according to the magnitude of the output voltage of the rectification module and a preset voltage, so as to stabilize the voltage of the resonant converter. Description of the Drawings

[0036] Figure 1 is a circuit diagram of an intermittent-mode DCDC resonant converter based on a fixed pulse width provided by an embodiment of the present invention;

[0037] Figure 2 is a driving waveform diagram of a first square-wave unit, a second square-wave unit, and a second square-wave module of an intermittent-mode DCDC resonant converter based on a fixed pulse width provided by an embodiment of the present invention, the current waveform of a resonant inductor, and the voltage waveform at the output end of a rectifier bridge.

[0038] Description of Components and Reference Numerals:

[0039] 1. Control module; 2. First square-wave module; 3. Transformer module; 4. Resonant module; 5. Second square-wave module; 6. Rectification module. Detailed Embodiments

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0041] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise stated, the meaning of "a plurality" is two or more. Additionally, the use of "based on" or "according to" is meant to be open and inclusive because a process, step, calculation, or other action "based on" or "according to" one or more conditions or values may in practice be based on additional conditions or values beyond those stated.

[0042] To solve the problem of low conversion efficiency when the existing resonant converter is used as a switching power supply, an embodiment of the present invention provides a discontinuous mode DCDC resonant converter based on a fixed pulse width.

[0043] Figure 1 The circuit diagram of a discontinuous mode DCDC resonant converter based on a fixed pulse width provided by an embodiment of the present invention.

[0044] As Figure 1 shown, the discontinuous mode DCDC resonant converter based on a fixed pulse width includes a control module 1, a first square wave module 2, a transformer module 3, a resonant module 4, a second square wave module 5, and a rectification module 6.

[0045] The transformer module 3 includes a primary and a secondary.

[0046] In this embodiment, the transformer module 3 is a transformer T1. The primary of the transformer T1 has a center tap, and its center tap is connected to the power supply.

[0047] The first square wave module 2 is connected in parallel across the primary of the transformer T1; the first square wave module 2 includes a first square wave unit and a second square wave unit.

[0048] Among them, the first square wave module 2 can be any one of a push - pull circuit, a half - bridge circuit, or a full - bridge circuit.

[0049] In this embodiment, the first square wave module 2 is a push - pull circuit.

[0050] Specifically, the first square wave unit includes a first push - pull power transistor Q1, and the second square wave unit includes a second push - pull power transistor Q2.

[0051] Among them, the first push-pull power transistor Q1 and the second push-pull power transistor Q2 are both N-channel field effect transistors;

[0052] The gate of the first push-pull power transistor Q1 and the gate of the second push-pull power transistor Q2 are both connected to the control module 1. The source of the first push-pull power transistor Q1 and the source of the second push-pull power transistor Q2 are connected. The drain of the first push-pull power transistor Q1 and the drain of the second push-pull power transistor Q2 are respectively connected to both ends of the primary of the transformer T1.

[0053] Such as Figure 1 shown, the second square wave module 5 is connected in parallel across both ends of the secondary of the transformer T1, and the second square wave module 5 is connected to the control module 1.

[0054] In this embodiment, the second square wave module 5 includes a first field effect transistor Q3 and a second field effect transistor Q4.

[0055] Among them, the first field effect transistor Q3 and the second field effect transistor Q4 are both N-channel field effect transistors.

[0056] Specifically, the first field effect transistor Q3 and the second field effect transistor Q4 can be selected as metal-oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs).

[0057] The gate of the first field effect transistor Q3 is connected to the gate of the second field effect transistor Q4. The source of the first field effect transistor Q3 is connected to the source of the second field effect transistor Q4. The drain of the first field effect transistor Q3 and the drain of the second field effect transistor Q4 are respectively connected across both ends of the secondary of the transformer T1;

[0058] The gate of the first field effect transistor Q3 and the gate of the second field effect transistor Q4 are connected to the control module 1.

[0059] Such as Figure 1 shown, the control module 1 is connected to the first square wave unit and the second square wave unit, and is used to control the first square wave unit and the second square wave unit to alternately work to generate a square wave signal; the alternating work is that after the first square wave unit conducts for a first preset duration, it is cut off for a second preset duration, and the second square wave unit conducts for a first preset duration after the first square wave unit conducts for a first preset duration, and then is cut off for a second preset duration.

[0060] Among them, the control module 1 is a micro control unit (MCU).

[0061] In this embodiment, the control module 1 includes a first output terminal, a second output terminal, and a third output terminal for outputting three pulse width signals. The first output terminal is connected to the gate of the first push-pull power transistor Q1, the second output terminal is connected to the gate of the second push-pull power transistor Q2, and the third output terminal is connected to the second square wave module 5.

[0062] The control module 1 further includes a power connection terminal and a ground terminal, and a third capacitor C3 is connected in series between the power connection terminal and the ground terminal for filtering the electrical signal input to the control module 1.

[0063] The control module 1 is further configured to control the second square-wave module 5 to conduct for a third preset duration when the second square-wave unit conducts for a first preset duration; the third preset duration is the difference between the second preset duration and the first preset duration, and the third preset duration is greater than zero.

[0064] Further, a preset voltage is set in the control module 1;

[0065] The control module 1 is further configured to obtain the output voltage of the rectification module 6 and adjust the value of the third preset duration according to the magnitude relationship between the output voltage and the preset voltage.

[0066] Among them, adjusting the value of the third preset duration according to the magnitude relationship between the output voltage and the preset voltage is specifically:

[0067] Obtain the difference between the output voltage and the preset voltage. If the difference is greater than zero, extend the third preset duration until the difference is zero;

[0068] If the difference is less than zero, shorten the third preset duration until the difference is zero.

[0069] As Figure 1 shown, the resonance module 4 is connected in series with the secondary. The resonance period of the resonance module 4 is equal to the first preset duration, and is used to filter out the high-order harmonic current in the output current of the secondary.

[0070] Among them, the resonance module 4 is an LC resonance circuit.

[0071] In this embodiment, the resonance module 4 includes a resonance inductor L1 and a resonance capacitor C1;

[0072] One end of the resonance inductor L1 is connected to the drain of the first field-effect transistor Q3 and one end of the secondary of the transformer T1. The other end of the resonance inductor L1 is connected to one end of the resonance capacitor C1, and the other end of the resonance capacitor C1 is connected to the rectification module 6.

[0073] The rectification module 6 includes a rectifier bridge BD1, a freewheeling inductor L2, and a filter capacitor C2;

[0074] The rectifier bridge BD1 includes a first AC input terminal, a second AC input terminal, a DC output positive terminal, and a DC output negative terminal;

[0075] The first AC input terminal is connected to the resonant capacitor C1, the second AC input terminal is connected to the drain of the second field-effect transistor Q4 and one end of the secondary side, the positive DC output terminal is connected to one end of the freewheeling inductor L2, the other end of the freewheeling inductor L2 is connected to the positive electrode of the filter capacitor C2, and the negative electrode of the filter capacitor C2 is connected to the negative DC output terminal.

[0076] As Figure 1 shown, the rectification module 6 is connected in series with the resonant module 4, and a load resistor R is connected in series between the two ends of the output terminal of the rectification module 6.

[0077] Figure 2 It is the driving waveform diagram of the first square-wave unit, the second square-wave unit and the second square-wave module 5 of a fixed-pulse-width intermittent-mode DCDC resonant converter provided by an embodiment of the present invention, the current waveform of the resonant inductor L1, and the voltage waveform at the output terminal of the rectifier bridge BD1.

[0078] As shown in FIGS. 1 and Figure 2 shown, Figure 2 G1 in FIG. 1 is the driving waveform of the first square-wave unit, G2 is the driving waveform of the second square-wave unit, G3 is the driving waveform of the second square-wave module 5, IL1 is the current waveform flowing through the resonant inductor L1, and U+ is the voltage waveform at the positive electrode OUT+ of the output terminal of the rectifier bridge BD1.

[0079] When the fixed-pulse-width intermittent-mode DCDC resonant converter provided by the embodiment of the present invention is used as a switching power supply, the control module 1 outputs three pulse-width signals, including the first signal G1, the second signal G2, and the third signal G3. Among them, the first signal G1 controls the driving waveform of the first square-wave unit, the second signal controls the driving waveform of the second square-wave unit, and the third signal controls the driving waveform of the second square-wave module 5.

[0080] Specifically, the first push-pull power transistor Q1 is controlled by the first signal to conduct for a first preset duration, that is, Figure 2 Ton in FIG. 1, and then the first push-pull power transistor Q1 is controlled to be cut off for a second preset duration, that is, Figure 2 Toff in FIG. 1. The second push-pull power transistor Q2 is controlled by the second signal to conduct for a first preset duration after the first push-pull power transistor Q1 conducts for the first preset duration, and then is cut off for a second preset duration. In this way, the common cut-off time of the first push-pull power transistor Q1 and the second push-pull power transistor Q2 is the difference between the second preset duration and the first preset duration, that is, Figure 2 Toff - Ton in FIG. 1, and this difference is greater than or equal to zero, so that the first push-pull power transistor Q1 and the second push-pull power transistor Q2 alternately conduct with a fixed pulse width.

[0081] The third signal is used to control the first field-effect transistor Q3 and the second field-effect transistor Q4 to conduct for a third preset duration after the second push-pull power transistor Q2 conducts for a first preset duration, so that the second square-wave module 5 also conducts with a fixed pulse width.

[0082] The resonance period of the resonance inductor L1 and the resonance capacitor C1 connected in series at the secondary of the transformer T1 is the first preset duration, i.e., Ton, such that the resonance inductor L1, the resonance capacitor C1, and the rectification module 6 are turned on and off with zero current; since the first square-wave module 2, the resonance module 4, and the rectification module 6 all achieve zero-current switching, the conversion efficiency of the resonance converter is effectively improved.

[0083] When the resonance inductor L1 and the resonance capacitor C1 are both cut off, the circuit can continue to conduct current due to the freewheeling inductor L2 connected in series at the output end of the rectifier bridge BD1, thus ensuring the continuous and stable load current of the circuit. When the resonance inductor L1 and the resonance capacitor C1 are both cut off, the secondary of the transformer T1 is short-circuited through the first field-effect transistor Q3 and the second field-effect transistor Q4, resetting the resonance module 4 connected in series at the secondary of the transformer T1 to prepare for the next resonance period of the circuit.

[0084] The pulse widths of the first square-wave module 2 and the second square-wave module 5 of the fixed-pulse-width intermittent-mode DCDC resonance converter of the present invention are fixed; the conduction times of the first square-wave module 2 and the second square-wave module 5 are equal to the resonance period of the resonance module 4, so that the first square-wave module 2 at the primary of the transformer T1, and the second square-wave module 5, the resonance module 4, and the rectification module 6 at the secondary of the transformer T1 all achieve zero-current switching, thus greatly improving the conversion efficiency of the converter.

[0085] The control module 1 of the fixed-pulse-width intermittent-mode DCDC resonance converter of the present invention can also adjust the value of the third preset duration according to the magnitude of the output voltage of the rectification module 6 and a preset voltage, so as to stabilize the voltage of the resonance converter.

[0086] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An intermittent mode DCDC resonant converter based on a fixed pulse width, characterized in that, It includes a control module, a first square-wave module, a transformer module, a resonant module, a second square-wave module, and a rectification module; The transformer module includes a primary and a secondary; The first square-wave module is connected in parallel with the primary; the first square-wave module includes a first square-wave unit and a second square-wave unit; The control module is connected to the first square-wave unit and the second square-wave unit, and is used to control the first square-wave unit and the second square-wave unit to alternately operate to generate a square-wave signal; the alternate operation is that the first square-wave unit conducts for a first preset duration and then cuts off for a second preset duration, and the second square-wave unit conducts for the first preset duration after the first square-wave unit conducts for the first preset duration, and then cuts off for the second preset duration; The resonant module is connected in series with the secondary, and the resonant period of the resonant module is equal to the first preset duration, and is used to filter out high-order harmonic currents in the output current of the secondary; The second square-wave module is connected in parallel with the secondary, and the second square-wave module is connected to the control module; The control module is further used to control the second square-wave module to conduct for a third preset duration when the second square-wave unit conducts for the first preset duration; the third preset duration is the difference between the second preset duration and the first preset duration, and the third preset duration is greater than zero; The rectification module is connected in series with the resonant module; The first square-wave module is a push-pull circuit; The first square-wave unit includes a first push-pull power tube, and the second square-wave unit includes a second push-pull power tube; Both the first push-pull power tube and the second push-pull power tube are N-channel field effect transistors; The gate of the first push-pull power tube and the gate of the second push-pull power tube are connected to the control module, the source of the first push-pull power tube and the source of the second push-pull power tube are connected, and the drain of the first push-pull power tube and the drain of the second push-pull power tube are respectively connected to both ends of the primary; The second square-wave module includes a first field effect transistor and a second field effect transistor; Both the first field effect transistor and the second field effect transistor are N-channel field effect transistors; The gate of the first field effect transistor is connected to the gate of the second field effect transistor, the source of the first field effect transistor is connected to the source of the second field effect transistor, and the drain of the first field effect transistor and the drain of the second field effect transistor are respectively connected to both ends of the secondary; The gate of the first field effect transistor and the gate of the second field effect transistor are connected to the control module.

2. The resonant converter according to claim 1, wherein A preset voltage is set in the control module; The control module is further used to obtain the output voltage of the rectification module, and adjust the value of the third preset duration according to the magnitude of the output voltage and the preset voltage.

3. The resonant converter according to claim 2, wherein, The adjusting the value of the third preset duration according to the magnitude of the output voltage and the preset voltage is specifically: Obtain the difference between the output voltage and the preset voltage. If the difference is greater than zero, then extend the third preset duration until the difference is zero; If the difference is less than zero, then shorten the third preset duration until the difference is zero.

4. The resonant converter according to claim 1, wherein The resonant module includes a resonant inductor and a resonant capacitor; One end of the resonant inductor is connected to the drain of the first field effect transistor and one end of the secondary. The other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to the rectification module.

5. The resonant converter according to claim 4, characterized in that, The rectification module includes a rectifier bridge, a freewheeling inductor, and a filter capacitor; The rectifier bridge includes a first AC input terminal, a second AC input terminal, a DC output positive terminal, and a DC output negative terminal; The first AC input terminal is connected to the resonant capacitor. The second AC input terminal is connected to the drain of the second field effect transistor and one end of the secondary. The DC output positive terminal is connected to one end of the freewheeling inductor. The other end of the freewheeling inductor is connected to the positive electrode of the filter capacitor, and the negative electrode of the filter capacitor is connected to the DC output negative terminal.

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