Quasi-resonant soft switching push-pull converter

Abstract

The utility model provides a quasi-resonant soft switching push-pull converter, comprising a half-bridge push-pull conversion circuit used for converting a low-voltage DC power supply signal into a high-frequency low-voltage pulse power supply signal; the primary side of the high-frequency transformer is connected with the half-bridge push-pull conversion circuit so as to amplify the high-frequency low-voltage pulse power supply signal into a high-frequency high-voltage pulse power supply signal at an equal turn ratio; the LC resonance circuit is connected with one end of the secondary side of the high-frequency transformer; and the rectification filter circuit is connected with the LC resonance circuit and the other end of the secondary side of the high-frequency transformer so as to convert the high-frequency high-voltage pulse power supply signal into a smooth high-voltage direct-current power supply signal. According to the utility model, the current stress is zero when the switching tube is turned on, and the current stress is zero when the switching tube is turned off, so that the switching loss of the switching tube can be reduced to the greatest extent, and the conversion efficiency of a power supply product is improved.

Description

Technical Field

[0001] This utility model relates to the field of push-pull converter technology, and in particular to a quasi-resonant soft-switching push-pull converter and its working method. Background Art

[0002] Inverter power systems powered by low-voltage battery packs, fuel cell stacks, and other power sources typically employ a two-stage series circuit structure. The first stage is a DC-DC isolation boost circuit, which converts the low battery voltage into a constant high-voltage DC bus voltage. The second stage is a DC-AC converter, which converts the high-voltage DC bus voltage into a 220VAC or 110VAC mains voltage. In these systems, the limited battery energy storage capacity places higher demands on system efficiency. Higher conversion efficiency can significantly improve the overall system's battery life.

[0003] Traditional duty-cycle-controlled push-pull converters experience excessive current stress during the on- and off-state transitions of the switch, leading to excessive switching losses within the switch itself and significant heat generation, resulting in low efficiency. Even in low-power applications, the battery current can reach several times the battery voltage. Because circuit losses are primarily in the upstream circuitry, research into improving the conversion efficiency of these upstream circuits is crucial. Utility Model Content

[0004] The utility model provides a quasi-resonant soft-switching push-pull converter and an operating method thereof, which realizes that the current stress is zero when the switch tube is turned on and the current stress is zero when it is turned off, and can minimize the switching loss of the switch tube, thereby improving the conversion efficiency of the power supply product.

[0005] This specification provides an embodiment of a quasi-resonant soft-switching push-pull converter, comprising:

[0006] A half-bridge push-pull converter circuit is used to convert low-voltage DC power supply signals into high-frequency low-voltage pulse power supply signals.

[0007] A high-frequency transformer, the primary side of which is connected to the half-bridge push-pull converter circuit, to amplify the high-frequency low-voltage pulse power signal into a high-frequency high-voltage pulse power signal with an equal turns ratio.

[0008] An LC resonant circuit is connected to one end of the secondary side of the high-frequency transformer;

[0009] A rectifier and filter circuit is connected to the other end of the secondary side of the LC resonant circuit and the high-frequency transformer to convert the high-frequency high-voltage pulse power signal into a smooth high-voltage DC power signal.

[0010] The LC resonant circuit and the rectifier and filter circuit form a resonant loop to convert the circuit current into a sinusoidal resonant current.

[0011] In some embodiments of this specification, the quasi-resonant soft-switching push-pull converter further includes:

[0012] an amplifier connected to the half-bridge push-pull conversion circuit to amplify the current signal of the high-frequency low-voltage pulse power supply to obtain an amplified current sampling signal;

[0013] A sampling and amplifying module, connected to the amplifier, to collect the current sampling signal to obtain a collection signal;

[0014] The processor is connected to the sampling and amplifying module to obtain the acquisition signal. The processor determines whether the current of the current high-frequency low-voltage pulse power supply exceeds the set threshold according to the acquisition signal, thereby limiting excessive current stress.

[0015] In some embodiments of the present specification, the half-bridge push-pull conversion circuit includes a power supply P1, a switch tube S1, a switch tube S2, a capacitor CI and a resistor R1, one end of the resistor R1 is connected to the negative electrode of the power supply P1, the other end of the resistor R1 is connected to one end of the capacitor CI, the output end of the switch tube S1 and the output end of the switch tube S2, the positive electrode of the power supply P1 is connected to the other end of the capacitor CI and the midpoint of the primary side of the high-frequency transformer, the input end of the switch tube S1 is connected to one end on both sides of the midpoint of the primary side of the high-frequency transformer, the input end of the switch tube S2 is connected to the other end on both sides of the midpoint of the primary side of the high-frequency transformer, the control end of the switch tube S1 and the control end of the switch tube S2 are both used to connect to the control chip, and the amplifier is connected in parallel on both sides of the resistor R1 to receive and monitor the current signal of the high-frequency low-voltage pulse power supply.

[0016] In some embodiments of this specification, the LC resonant circuit includes an inductor Lr and a capacitor Cr, one end of the inductor Lr is connected to one end of the primary side of the high-frequency transformer, the other end of the inductor Lr is connected to one end of the capacitor Cr, and the other end of the capacitor Cr is connected to the rectifier and filter circuit.

[0017] In some embodiments of the present specification, the rectifier and filter circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor CB and a load RL, the anode of the diode D1 is connected to the cathode of the diode D4 and the other end of the capacitor Cr, the anode of the diode D2 is connected to the cathode of the diode D3 and the other end of the secondary side of the high-frequency transformer, the cathode of the diode D1 is connected to the cathode of the diode D2, one end of the capacitor CB and one end of the load RL and then connected to the external voltage terminal VBUS, and the anode of the diode D4 is connected to the anode of the diode D3, the other end of the capacitor CB and the other end of the load RL and then grounded.

[0018] In some embodiments of this specification, the switch tube S1 and the switch tube S2 are triodes (also called bipolar transistors) or MOSFET tubes (also called insulated gate field effect transistors) or IGBT tubes (also called insulated gate bipolar transistors).

[0019] The embodiments described in this specification can achieve at least the following beneficial effects:

[0020] A low-voltage DC power supply signal is converted into a high-frequency, low-voltage pulse power supply signal through a half-bridge push-pull conversion circuit; the high-frequency, low-voltage pulse power supply signal is amplified into a high-frequency, high-voltage pulse power supply signal with equal turns ratio through a high-frequency transformer; the high-frequency, high-voltage pulse power supply signal is converted into a smooth high-voltage DC power supply signal through an LC resonant circuit and a rectifier filter circuit; zero-current shutdown and zero-current start-up of the switch tube are achieved, the switching loss of the switch tube is reduced, and the conversion efficiency of the push-pull converter is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a circuit diagram of the quasi-resonant soft-switching push-pull converter involved in this utility model. DETAILED DESCRIPTION

[0023] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0024] The disclosure below provides many different embodiments or examples for implementing different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the components and settings of specific examples are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. In addition, the embodiments of the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, an embodiment of this specification provides a quasi-resonant soft-switching push-pull converter, including:

[0027] A half-bridge push-pull converter circuit is used to convert a low-voltage DC power signal (output of a power supply system or energy storage system) into a high-frequency low-voltage pulse power signal;

[0028] A high-frequency transformer, the primary side of which is connected to the half-bridge push-pull converter circuit, to amplify the high-frequency low-voltage pulse power signal into a high-frequency high-voltage pulse power signal with an equal turns ratio.

[0029] An LC resonant circuit is connected to one end of the secondary side of the high-frequency transformer;

[0030] A rectifier and filter circuit is connected to the other end of the secondary side of the LC resonant circuit and the high-frequency transformer to convert the high-frequency high-voltage pulse power signal into a smooth high-voltage DC power signal.

[0031] The LC resonant circuit and the rectifier and filter circuit form a resonant loop to convert the circuit current into a sinusoidal resonant current.

[0032] In some embodiments of this specification, the quasi-resonant soft-switching push-pull converter further includes:

[0033] Amplifier U1 D, connected to the half-bridge push-pull conversion circuit, to amplify the current signal of the high-frequency low-voltage pulse power supply to obtain an amplified current sampling signal;

[0034] A sampling and amplifying module, connected to the amplifier, to collect the current sampling signal to obtain a collection signal;

[0035] The processor is connected to the sampling and amplifying module to obtain the acquisition signal. The processor determines whether the current of the current high-frequency low-voltage pulse power supply exceeds the set threshold according to the acquisition signal, thereby limiting excessive current stress.

[0036] In some embodiments of this specification, the half-bridge push-pull converter circuit includes a power supply P1 (power system or energy storage system), switching transistors S1 and S2, a capacitor CI, and a resistor R1. One end of the resistor R1 is connected to the negative terminal of the power supply P1, and the other end of the resistor R1 is connected to one end of the capacitor CI, the output terminal of the switching transistor S1, and the output terminal of the switching transistor S2. The positive terminal of the power supply P1 is connected to the other end of the capacitor CI and the midpoint of the primary side of the high-frequency transformer. The input terminal of the switching transistor S1 is connected to one end of the primary side of the high-frequency transformer, and the input terminal of the switching transistor S2 is connected to the other end of the primary side of the high-frequency transformer. The control terminals of the switching transistors S1 and S2 are both used to connect to a control chip. The amplifier is connected in parallel across the resistor R1 to receive and monitor the current signal of the high-frequency low-voltage pulse power supply.

[0037] The control chip may be the processor mentioned in the text or other existing chips that can control the operation of the switch tube.

[0038] In some embodiments of this specification, the LC resonant circuit includes an inductor Lr and a capacitor Cr, one end of the inductor Lr is connected to one end of the primary side of the high-frequency transformer, the other end of the inductor Lr is connected to one end of the capacitor Cr, and the other end of the capacitor Cr is connected to the rectifier and filter circuit.

[0039] In some embodiments of the present specification, the rectifier and filter circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor CB and a load RL, the anode of the diode D1 is connected to the cathode of the diode D4 and the other end of the capacitor Cr, the anode of the diode D2 is connected to the cathode of the diode D3 and the other end of the secondary side of the high-frequency transformer, the cathode of the diode D1 is connected to the cathode of the diode D2, one end of the capacitor CB and one end of the load RL and then connected to the external voltage terminal VBUS, and the anode of the diode D4 is connected to the anode of the diode D3, the other end of the capacitor CB and the other end of the load RL and then grounded.

[0040] In some embodiments of this specification, the switching transistors S1 and S2 are bipolar transistors (BJTs), MOSFETs (insulated-gate field-effect transistors), or IGBTs (insulated-gate bipolar transistors). Specifically, when S1 and S2 are BJTs, the control terminal is the base, the input terminal is the collector, and the output terminal is the emitter; when S1 and S2 are MOSFETs, the control terminal is the gate, the input terminal is the drain, and the output terminal is the source; when S1 and S2 are IGBTs, the control terminal is the gate, the input terminal is the collector, and the output terminal is the emitter.

[0041] Another aspect of the embodiments of this specification provides a method for operating a quasi-resonant soft-switching push-pull converter, which is implemented by using any one of the above-described quasi-resonant soft-switching push-pull converters;

[0042] The low-voltage DC power signal is converted into a high-frequency low-voltage pulse power signal through a half-bridge push-pull conversion circuit;

[0043] Amplifying the high-frequency low-voltage pulse power supply signal with equal turns ratio into a high-frequency high-voltage pulse power supply signal through a high-frequency transformer;

[0044] The high-frequency high-voltage pulse power signal is converted into a smooth high-voltage direct current power signal through an LC resonant circuit and a rectifier filter circuit.

[0045] In some embodiments of this specification, by controlling the on / off states of both the switch tubes S1 and S2 , the resonance period of the LC resonant circuit is made shorter than the control period of the push-pull switching power supply of the half-bridge push-pull conversion circuit.

[0046] Among them, through appropriate calculation, the resonant period is made shorter than the PWM switching period of the push-pull switching power supply, the characteristics of the two zero crossing points of the sinusoidal resonant current half cycle are continuously adjusted, the pulse power supply signal output by the high-frequency transformer is naturally rectified, and then filtered to become a smooth high-voltage DC power supply.

[0047] The operating waveforms of switches S1 and S2 when they are alternately and complementary turned on. When switch S1 is turned on, the voltage applied to the primary side L1 of the high-frequency transformer causes switch S2 to withstand twice the input voltage, inducing a voltage n times greater on the secondary side L2 of the high-frequency transformer. When switch S2 is turned on, the voltage applied to the primary side L1 causes switch S1 to withstand twice the input voltage, inducing a voltage n times greater on the secondary side L2.

[0048] After being boosted by the high-frequency transformer, the current flowing through the inductor Lr and capacitor Cr produces a loaded current waveform. Inductor Lr can be replaced by the secondary leakage inductance of the high-frequency transformer. By properly calculating and observing whether the zero-crossing point of the resonant cavity current waveform coincides with the moment the switch turns on or off, the resonant period of the LC resonant circuit is slightly shorter than the PWM control period of the push-pull switching power supply's switch. During the instants of turning on and off switches S1 and S2, the current remains at zero, ultimately achieving zero-current switching (ZCS) and zero-current switching (ZCS) during the discharge process. This reduces switching losses and improves efficiency.

[0049] The above-described embodiments are intended to illustrate the present invention, not to limit the present invention. Therefore, changes in illustrative values ​​or replacement of equivalent components should still fall within the scope of the present invention.

[0050] From the above detailed description, it will be clear to those skilled in the art that the present invention can indeed achieve the aforementioned objectives and is in compliance with the provisions of the Patent Law.

[0051] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0052] It should be noted that the above description of the relevant processes is for illustration and explanation only and does not limit the scope of application of this specification. For those skilled in the art, various modifications and changes can be made to the processes under the guidance of this specification. However, such modifications and changes are still within the scope of this specification.

[0053] The basic concepts have been described above. Obviously, for those skilled in the art who have read this application, the above disclosure of the utility model is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore, such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0054] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different positions in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0055] In addition, it will be understood by those skilled in the art that various aspects of the present application can be illustrated and described by a number of patentable categories or situations, including any new and useful combination of processes, machines, products or substances, or any new and useful improvements thereto. Therefore, various aspects of the present application can be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software can all be referred to as "units", "modules" or "systems". In addition, various aspects of the present application can take the form of a computer program product embodied in one or more computer-readable media, wherein computer-readable program code is contained therein.

[0056] In addition, unless expressly stated in the claims, the order of the processing elements and sequences described in this application, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this application. Although the above disclosure discusses some currently useful utility model embodiments through various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this application. For example, although the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a pure software solution, for example, an installation on an existing server or mobile device. Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thereby help understand one or more utility model embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this method of the present application should not be interpreted as reflecting the intention that the claimed object requires more features than those explicitly stated in each claim. On the contrary, the subject of the utility model should have fewer features than the single embodiment described above.

Claims

1. A quasi-resonant soft-switching push-pull converter, characterized in that: include: A half-bridge push-pull conversion circuit is used to convert a low-voltage DC power supply signal into a high-frequency low-voltage pulse power supply signal; A high-frequency transformer, the primary side of which is connected to the half-bridge push-pull conversion circuit, so as to amplify the high-frequency low-voltage pulse power supply signal with equal turns ratio into a high-frequency high-voltage pulse power supply signal; An LC resonant circuit connected to one end of the secondary side of the high-frequency transformer; A rectifier and filter circuit connected to the LC resonant circuit and the other end of the secondary side of the high-frequency transformer to convert the high-frequency high-voltage pulse power signal into a smooth high-voltage DC power signal; The LC resonant circuit and the rectifier and filter circuit form a resonant loop to convert the circuit current into a sinusoidal resonant current.

2. The quasi-resonant soft-switching push-pull converter according to claim 1, characterized in that: Also includes: An amplifier connected to the half-bridge push-pull conversion circuit to amplify the current signal of the high-frequency low-voltage pulse power supply to obtain an amplified current sampling signal; A sampling and amplification module, connected to the amplifier, to collect the current sampling signal to obtain a collection signal; The processor is connected to the sampling and amplifying module to obtain the acquisition signal. The processor determines whether the current of the current high-frequency low-voltage pulse power supply exceeds the set threshold value according to the acquisition signal, so as to limit the excessive current stress.

3. The quasi-resonant soft-switching push-pull converter according to claim 2, characterized in that: The half-bridge push-pull conversion circuit includes a power supply P1, a switch tube S1, a switch tube S2, a capacitor CI and a resistor R1, one end of the resistor R1 is connected to the negative electrode of the power supply P1, the other end of the resistor R1 is connected to one end of the capacitor CI, the output end of the switch tube S1 and the output end of the switch tube S2, the positive electrode of the power supply P1 is connected to the other end of the capacitor CI and the midpoint of the primary side of the high-frequency transformer, the input end of the switch tube S1 is connected to one end on both sides of the midpoint of the primary side of the high-frequency transformer, the input end of the switch tube S2 is connected to the other end on both sides of the midpoint of the primary side of the high-frequency transformer, the control end of the switch tube S1 and the control end of the switch tube S2 are both used to connect to the control chip, and the amplifier is connected in parallel on both sides of the resistor R1 to receive and monitor the current signal of the high-frequency low-voltage pulse power supply.

4. The quasi-resonant soft-switching push-pull converter according to claim 1, characterized in that: The LC resonant circuit includes an inductor Lr and a capacitor Cr, one end of the inductor Lr is connected to one end of the primary side of the high-frequency transformer, the other end of the inductor Lr is connected to one end of the capacitor Cr, and the other end of the capacitor Cr is connected to the rectifier and filter circuit.

5. The quasi-resonant soft-switching push-pull converter according to claim 4, characterized in that: The rectifier and filter circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor CB and a load RL. The anode of the diode D1 is connected to the cathode of the diode D4 and the other end of the capacitor Cr, the anode of the diode D2 is connected to the cathode of the diode D3 and the other end of the secondary side of the high-frequency transformer, the cathode of the diode D1 is connected to the cathode of the diode D2, one end of the capacitor CB and one end of the load RL and then connected to an external voltage terminal VBUS, and the anode of the diode D4 is connected to the cathode of the diode D3, the other end of the capacitor CB and the other end of the load RL and then grounded.

6. The quasi-resonant soft-switching push-pull converter according to claim 3, characterized in that: The switch tube S1 and the switch tube S2 are triodes, MOSFET tubes or IGBT tubes.

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