Buck-boost conversion circuit, PFC circuit and automobile

Abstract

The utility model discloses a buck-boost conversion circuit, a PFC circuit and an automobile. The buck-boost conversion circuit comprises a first switch tube, a third switch tube, a first inductor and a first capacitor. The first end of the first switch tube is connected with the first input end, the second end of the first switch tube is connected with the first output end through the first inductor, and the second end of the first switch tube is connected with the second output end; the first end of the third switching tube is connected with the first inductor and the first output end, and the second end of the third switching tube is connected with the second input end and the second output end; two ends of the first capacitor are connected with the first output end and the second output end; the first input end and the second input end are used for connecting a DC power supply, and the first output end and the second output end are used for connecting a post-stage circuit. The buck-boost conversion circuit not only can realize a boost function, but also can realize a buck function, and is simple in circuit structure and relatively low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of voltage conversion, in particular to a step-up / step-down conversion circuit, a PFC circuit and a car. Background Art

[0002] PFC (Power Factor Correction) circuits are primarily used to measure the energy efficiency of electronic products. PFC circuits typically incorporate a voltage conversion circuit to convert the power supply's input voltage and provide an output voltage to subsequent circuits. Existing PFC circuits typically incorporate a boost converter circuit, resulting in a narrow adjustable range for the output voltage, severely limiting the gain adjustment capabilities of subsequent circuits. Utility Model Content

[0003] The embodiments of the present invention provide a buck-boost conversion circuit, a PFC circuit and an automobile to solve the problem that the output voltage adjustable range of the existing voltage conversion circuit is narrow.

[0004] A buck-boost conversion circuit includes a first switch tube, a third switch tube, a first inductor, and a first capacitor;

[0005] The first end of the first switch tube is connected to the first input end, the second end of the first switch tube is connected to the first output end via the first inductor, and the second end of the first switch tube is connected to the second output end;

[0006] The first end of the third switch tube is connected to the first inductor and the first output end, and the second end of the third switch tube is connected to the second input end and the second output end;

[0007] Two ends of the first capacitor are connected to the first output end and the second output end;

[0008] The first input end and the second input end are used to connect to a DC power supply, and the first output end and the second output end are used to connect to a subsequent circuit based on the conduction or disconnection of the first switching tube and the third switching tube to form a boost conversion circuit or a buck conversion circuit.

[0009] Preferably, the first switch tube is controlled to be in a conducting state, and the third switch tube is controlled to be turned off or on in an alternating manner to form the boost conversion circuit;

[0010] Alternatively, the third switch tube is controlled to be in an off state, and the first switch tube is controlled to be on or off in an alternating manner to form the buck conversion circuit.

[0011] Preferably, the buck-boost conversion circuit further includes a first anti-backlash unit, a third anti-backlash unit and a fourth anti-backlash unit;

[0012] A first end of the first anti-reverse unit is connected to the first inductor, and a second end of the first anti-reverse unit is connected to the first output end;

[0013] The first end of the third anti-reverse unit is connected to the second output end and the second end of the third switch tube, and the second end of the third anti-reverse unit is connected to the second input end;

[0014] A first end of the fourth anti-backward unit is connected to the second output end, and a second end of the fourth anti-backward unit is connected to the first switch tube and the first inductor.

[0015] Preferably, the first anti-reverse unit, the third anti-reverse unit and the fourth anti-reverse unit are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

[0016] Preferably, the first switching tube is a MOS tube provided with a parasitic diode or an IGBT tube provided with a freewheeling diode; the third switching tube is a MOS tube, an IGBT tube or a triode.

[0017] A buck-boost conversion circuit includes a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first inductor, a second inductor, and a first capacitor;

[0018] The first end of the first switch tube is connected to the first input end, the second end of the first switch tube is connected to the first output end via the first inductor, and the second end of the first switch tube is connected to the second output end;

[0019] The first end of the second switch tube is connected to the second input end, the second end of the second switch tube is connected to the first output end via the second inductor, and the second end of the second switch tube is connected to the second output end;

[0020] The first end of the third switch tube is connected to the first inductor and the first output end, and the second end of the third switch tube is connected to the second input end and the second output end;

[0021] The first end of the fourth switch tube is connected to the second inductor and the first output end, and the second end of the fourth switch tube is connected to the first input end and the second output end;

[0022] Two ends of the first capacitor are connected to the first output end and the second output end;

[0023] The first input end and the second input end are used to connect to an AC power supply, and the first output end and the second output end are used to connect to a subsequent circuit; based on the conduction or disconnection of the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube, a boost conversion circuit or a buck conversion circuit is formed.

[0024] Preferably, the first switch tube and the second switch tube are controlled to be in an on state, one of the third switch tube and the fourth switch tube is controlled to be in an off state, and the other of the third switch tube and the fourth switch tube is controlled to be turned off or on alternately to form a boost conversion circuit;

[0025] Alternatively, the third switch tube and the fourth switch tube are controlled to be in an off state, and the first switch tube and the second switch tube are alternately controlled to be turned on or off at the same time, so as to form a step-down conversion circuit.

[0026] Preferably, the buck-boost conversion circuit further includes a first anti-backward unit, a second anti-backward unit, a third anti-backward unit and a fourth anti-backward unit;

[0027] A first end of the first anti-reverse unit is connected to the first inductor, and a second end of the first anti-reverse unit is connected to the first output end;

[0028] A first end of the second anti-reverse unit is connected to the second inductor, and a second end of the second anti-reverse unit is connected to the first output end;

[0029] A first end of the third anti-reverse unit is connected to the second output end, and a second end of the third anti-reverse unit is connected to the second switch tube and the second inductor;

[0030] A first end of the fourth anti-backward unit is connected to the second output end, and a second end of the fourth anti-backward unit is connected to the first switch tube and the first inductor.

[0031] Preferably, the first anti-reverse unit, the second anti-reverse unit, the third anti-reverse unit and the fourth anti-reverse unit are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

[0032] Preferably, the first switching tube and the second switching tube are MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes; the third switching tube and the fourth switching tube are MOS tubes, IGBT tubes or triodes.

[0033] A PFC circuit includes the above-mentioned buck-boost conversion circuit.

[0034] An automobile comprises the above-mentioned PFC circuit.

[0035] The aforementioned buck-boost converter circuit, PFC circuit, and automobile achieve both boost and buck functions by controlling the on / off switching of a switch in the buck-boost converter circuit. This results in a simple circuit structure and low cost. When the buck-boost converter circuit is applied to a PFC circuit, the PFC voltage can be controlled to rise or fall according to actual conditions, significantly widening the adjustable range of the PFC circuit and providing sufficient margin for gain adjustment in subsequent circuits, thereby ensuring the gain adjustment capability of the subsequent circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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 of the present invention. 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 labor.

[0037] Figure 1 This is a circuit diagram of a buck-boost converter circuit for connecting a DC power supply in one embodiment of the present invention;

[0038] Figure 2 for Figure 1 The first timing diagram of the step-up / down conversion circuit in the embodiment of the present invention realizes the step-up function;

[0039] Figure 3 for Figure 1 The second timing diagram of the step-up / down conversion circuit in the embodiment of the present invention realizes the step-up function;

[0040] Figure 4 for Figure 1 The first timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the buck function;

[0041] Figure 5 for Figure 1 The second timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the buck function;

[0042] Figure 6 This is a circuit diagram of a buck-boost converter circuit for connecting to an AC power supply in one embodiment of the present invention;

[0043] Figure 7 for Figure 6 The first timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the boost function based on the forward voltage of the AC power supply;

[0044] Figure 8 for Figure 6 The second timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the boost function based on the forward voltage of the AC power supply;

[0045] Figure 9 for Figure 6 The first timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the buck function based on the forward voltage of the AC power supply;

[0046] Figure 10 for Figure 6 The second timing diagram of the buck-boost converter circuit in FIG. 1 is a diagram showing a buck function based on the forward voltage of the AC power supply.

[0047] Figure 11 for Figure 6 The first timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the boost function based on the reverse voltage of the AC power supply;

[0048] Figure 12 for Figure 6 The second timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the boost function based on the reverse voltage of the AC power supply;

[0049] Figure 13 for Figure 6 The first timing diagram of the buck-boost converter circuit in the embodiment of the present invention realizes the buck function based on the reverse voltage of the AC power supply;

[0050] Figure 14 for Figure 6 The second timing diagram of the buck-boost converter circuit in FIG. 1 shows a second timing diagram of the buck function based on the reverse voltage of the AC power supply. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] It should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0053] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part.

[0054] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the drawings is flipped, then the elements or features described as "under" or "beneath" or "beneath" the other elements will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" may include both the upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0055] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0056] In order to fully understand the present invention, the following description will provide detailed structures and steps to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0057] The present invention provides a step-up / step-down conversion circuit. Figure 1 As shown, the buck-boost converter circuit includes a first switch tube Q1, a third switch tube Q3, a first inductor L1, and a first capacitor C1; a first end of the first switch tube Q1 is connected to the first input end Vin1, a second end of the first switch tube Q1 is connected to the first output end Vout1 via the first inductor L1, and a second end of the first switch tube Q1 is connected to the second output end Vout2; a first end of the third switch tube Q3 is connected to the first inductor L1 and the first output end Vout1, and a second end of the third switch tube Q3 is connected to the second input end Vin2 and the second output end Vout2; two ends of the first capacitor C1 are connected to the first output end Vout1 and the second output end Vout2; the first input end Vin1 and the second input end Vin2 are used to connect to a DC power supply 1, and the first output end Vout1 and the second output end Vout2 are used to connect to a subsequent circuit; based on the conduction or disconnection of the first switch tube Q1 and the third switch tube Q3, a boost converter circuit or a buck converter circuit is formed.

[0058] The subsequent circuit is a circuit provided after the buck-boost converter circuit, and may be, but is not limited to, an LLC circuit.

[0059] As an example, the buck-boost conversion circuit is arranged between the DC power supply 1 and the subsequent circuit. Specifically, the first input terminal Vin1 of the buck-boost conversion circuit is connected to the positive electrode of the DC power supply 1, and the second input terminal Vin2 of the buck-boost conversion circuit is connected to the negative electrode of the DC power supply 1; the first output terminal Vout1 of the buck-boost conversion circuit is connected to the positive connection terminal of the subsequent circuit, and the second output terminal Vout2 of the buck-boost conversion circuit is connected to the negative connection terminal of the subsequent circuit. According to actual needs, the conduction and disconnection of the first switch tube Q1 and the third switch tube Q3 can be controlled so that the voltage of the two output terminals is greater than or less than the voltage of the two input terminals, so as to realize buck-boost control of the input voltage of the DC power supply 1.

[0060] As an example, the first switch tube Q1 and the first inductor L1 are arranged in series between the first input terminal Vin1 and the first output terminal Vout1; the first end of the third switch tube Q3 is connected to the first inductor L1 and the first output terminal Vout1, and the second end of the third switch tube Q3 is connected to the second input terminal Vin2 and the second output terminal Vout2; the two ends of the first capacitor C1 are connected to the first output terminal Vout1 and the second output terminal Vout2. In this design, a boost conversion circuit or a buck conversion circuit can be formed by turning on or off the first switch tube Q1 and the third switch tube Q3; the DC power supply 1 can be controlled to first turn on the DC power supply 1 to turn on the DC power supply 2 to turn on the DC power supply 3 to turn on the DC power supply 4 to turn on the DC power supply 5; the DC power supply 1 can be controlled to turn on the DC power supply 2 to turn on the DC power supply 5 to turn on the DC power supply 5; the DC power supply 1 can be controlled to turn on the DC power supply 1 to turn on the DC power supply 5 to turn on the DC power supply 5. An inductor L1 and a first capacitor C1 are charged, so that the first inductor L1 and the first capacitor C1 store electricity; then the first inductor L1 is controlled to discharge the first capacitor C1, so that the voltage across the first capacitor C1 increases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 increases, thereby realizing the boost function of the boost converter circuit; alternatively, the first capacitor C1 is controlled to discharge the first inductor L1, so that the voltage across the first capacitor C1 decreases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 decreases, thereby realizing the buck function of the buck converter circuit.

[0061] In this embodiment, by controlling the on and off of the first switch tube Q1 and the third switch tube Q3, the buck-boost converter circuit connected to the DC power supply 1 can achieve both a boost function and a buck function, resulting in a simple circuit structure and low cost.

[0062] In one embodiment, the first switch tube Q1 is controlled to be in the on state, and the third switch tube Q3 is controlled to be turned off or on in an alternating manner to form a boost converter circuit; alternatively, the third switch tube Q3 is controlled to be in the off state, and the first switch tube Q1 is controlled to be turned on or off in an alternating manner to form a buck converter circuit.

[0063] For example, when the buck-boost converter circuit is applied to a PFC circuit, the buck-boost converter circuit is connected to a DC power supply 1, the input voltages of the two input terminals are Vi, and the output voltages of the two output terminals are Vpfc. When the DC power supply 1 inputs a voltage of 220V, the first switch tube Q1 is controlled to be in an on state, so that the first switch tube Q1 is equivalent to a wire. By controlling the on or off of the third switch tube Q3, the buck-boost converter circuit is made into a Boost circuit (i.e., a boost converter circuit) to realize a boost function. The input-output relationship is Vpfc=Vi / (1-D), where D is the duty cycle. The specific control process is as follows: (A1) Figure 2 As shown, the third switch Q3 is controlled to be off, and the output voltage of the DC power supply 1 passes through the first inductor L1 and the subsequent circuit in sequence to form a charging loop. During this process, the DC power supply 1 charges the first inductor L1 and the first capacitor C1, so that the first inductor L1 and the first capacitor C1 store electricity. (A2) Figure 3 As shown, the third switch tube Q3 is controlled to be turned on. Since the current of the first inductor L1 cannot change suddenly, a discharge loop is formed between the first inductor L1, the third switch tube Q3, and the DC power supply 1. Since the third switch tube Q3 and the first capacitor C1 are arranged in parallel between the first output terminal Vout1 and the second output terminal Vout2, the discharge loop formed by the first inductor L1 charges the first capacitor C1, so that the voltage across the first capacitor C1 increases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 increases, thereby achieving a boost function.

[0064] For another example, when the buck-boost converter circuit is applied to a PFC circuit, the buck-boost converter circuit is connected to a DC power supply 1, the input voltages of the two input terminals are Vi, and the output voltages of the two output terminals are Vpfc. When the DC power supply 1 inputs a voltage of 220V, the third switch tube Q3 is controlled to be in an off state, so that the circuit where the third switch tube Q3 is located is open. By controlling the conduction or disconnection of the first switch tube Q1, the buck-boost converter circuit is made into a buck circuit (i.e., a step-down converter circuit) to implement a step-down function. The input-output relationship is Vpfc=Vi*D, where D is the duty cycle. The specific control process is as follows: (A3) Figure 4 As shown, the first switch Q1 is controlled to be turned on, and the output voltage of the DC power supply 1 passes through the first inductor L1 and the subsequent circuit in sequence to form a charging loop. During this process, the DC power supply 1 charges the first inductor L1 and the first capacitor C1, so that the first inductor L1 and the first capacitor C1 store electricity. (A4) Figure 5 As shown, the first switch tube Q1 is controlled to be disconnected, and a discharge loop is formed between the first inductor L1 and the first capacitor C1. The first capacitor C1 discharges the first inductor L1, so that the voltage across the first capacitor C1 is reduced, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 is reduced, thereby realizing the step-down function.

[0065] In this embodiment, the first switch Q1 is controlled to be in an on state, and the third switch Q3 is controlled to be turned off and on in an alternating manner, so that the buck-boost conversion circuit can achieve a boost function; the third switch Q3 is controlled to be in an off state, and the first switch Q1 is controlled to be turned on and off in an alternating manner, so that the buck-boost conversion circuit can achieve a buck function. In other words, by controlling the on and off of the first and third switches Q1 and Q3, the buck-boost conversion circuit connected to the DC power supply 1 can achieve both a boost function and a buck function, resulting in a simple circuit structure and low cost.

[0066] In one embodiment, if Figure 1As shown, the buck-boost converter circuit further includes a first anti-backlash unit 3, a third anti-backlash unit 5, and a fourth anti-backlash unit 6; a first end of the first anti-backlash unit 3 is connected to the first inductor L1, and a second end of the first anti-backlash unit 3 is connected to the first output end Vout1; a first end of the third anti-backlash unit 5 is connected to the second output end Vout2 and the second end of the third switch tube Q3, and a second end of the third anti-backlash unit 5 is connected to the second input end Vin2; a first end of the fourth anti-backlash unit 6 is connected to the second output end Vout2, and a second end of the fourth anti-backlash unit 6 is connected to the first switch tube Q1 and the first inductor L1.

[0067] As an example, when it is necessary to control the buck-boost converter circuit to achieve the boost function, the first anti-reverse unit 3 and the third anti-reverse unit 5 cooperate to prevent current reverse flow, specifically controlling the first switch tube Q1 to be in the on state, and performing the following operations alternately: (A1) Figure 1 and Figure 2 As shown, the third switch Q3 is controlled to be disconnected, and the current output from the positive electrode of the DC power supply 1 passes through the first inductor L1, the first anti-reverse unit 3-the subsequent circuit-the third anti-reverse unit 5-the negative electrode of the DC power supply 1 in sequence, forming a charging loop; (A2) Figure 1 and Figure 3 As shown, the third switch tube Q3 is controlled to be turned on, the positive electrode of the DC power supply 1-the first inductor L1-the third anti-reverse unit 5-the negative electrode of the DC power supply 1 forms a discharge loop, the first inductor L1 discharges the first capacitor C1 to achieve a boost function, and the first anti-reverse unit 3 is arranged between the first inductor L1 and the first output terminal Vout1 to prevent the current from flowing in the opposite direction and prevent the first capacitor C1 from discharging to the ground, so that the buck-boost conversion circuit achieves a boost function.

[0068] As an example, when it is necessary to control the buck-boost converter circuit to achieve the buck function, the first anti-reverse unit 3, the third anti-reverse unit 5 and the fourth anti-reverse unit 6 cooperate to prevent current reverse flow, specifically controlling the third switch tube Q3 to be in the off state, and staggeredly performing the following steps: (A3) Figure 1 and Figure 4 As shown, the first switch Q1 is controlled to be turned on, and the current output from the positive electrode of the DC power supply 1 passes through the first inductor L1, the first anti-reverse unit 3, the first capacitor C1 / the subsequent circuit-the third anti-reverse unit 5-the negative electrode of the DC power supply 1 in sequence, forming a charging loop; (A4) Figure 1 and Figure 5 As shown, the first switch tube Q1 is controlled to be disconnected, and a discharge loop is formed between the first inductor L1, the first anti-backlash unit 3, the first capacitor C1 / the subsequent circuit and the fourth anti-backlash unit 6. The first capacitor C1 discharges the first inductor L1 to achieve a voltage reduction function. The cooperation of the first anti-backlash unit 3 and the fourth anti-backlash unit 6 ensures the current flow direction of the discharge loop.

[0069] In one embodiment, if Figure 1 As shown, the first anti-reverse unit 3, the third anti-reverse unit 5 and the fourth anti-reverse unit 6 are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

[0070] As an example, the first anti-reverse unit 3 can be a first diode D1, the anode of the first diode D1 is connected to the first inductor L1, and the cathode of the first diode D1 is connected to the first output terminal Vout1 to ensure that the current flows from the first input terminal Vin1 / first inductor L1 to the first output terminal Vout1 to prevent the current from flowing in the opposite direction.

[0071] As an example, the third anti-reverse unit 5 can be a third diode D3, the anode of the third diode D3 is connected to the second output terminal Vout2, and the cathode of the third diode D3 is connected to the second input terminal Vin2, so that the current flowing back from the second output terminal Vout2 can be input to the second input terminal Vin2, so that a loop is formed; since the second end of the third switch tube Q3 is connected to the second output terminal Vout2, the current flowing back from the third switch tube Q3 can also be input to the second input terminal Vin2, so that a loop is formed.

[0072] As an example, the fourth anti-reverse unit 6 can be a fourth diode D4, which is connected to the second output terminal Vout2. The cathode of the fourth diode D4 is connected to the first switch tube Q1 and the first inductor L1, so that the current flowing back from the second output terminal Vout2 can be input to the first input terminal Vin1 or the first inductor L1. Since the second end of the third switch tube Q3 is connected to the second output terminal Vout2, the current flowing back from the third switch tube Q3 can also be input to the first input terminal Vin1 or the first inductor L1, so that a loop is formed.

[0073] In this example, a first diode D1, a third diode D3, and a fourth diode D4 are used to prevent reverse current flow, resulting in a simple overall structure and low cost. It is understood that the first diode D1, the third diode D3, and the fourth diode D4 can also be replaced by a MOS transistor with a parasitic diode or an IGBT transistor with a freewheeling diode. In actual operation, the MOS transistor and the IGBT transistor can be controlled to be turned on or off to control the corresponding circuit. When the MOS transistor and the IGBT transistor are in the closed state, the parasitic diode of the MOS transistor and the freewheeling diode of the IGBT transistor can both prevent reverse current flow.

[0074] In one embodiment, the first switch tube Q1 is a MOS tube with a parasitic diode or an IGBT tube with a freewheeling diode; the third switch tube Q3 is a MOS tube, an IGBT tube or a triode.

[0075] As an example, when the buck-boost conversion circuit is applicable to high-frequency scenarios, the first switch tube Q1 can be a MOS tube with a parasitic diode. When the buck-boost conversion circuit is applicable to low-frequency scenarios, the first switch tube Q1 can be a MOS tube with a parasitic diode or an IGBT tube with a freewheeling diode, which can be selected independently according to actual conditions.

[0076] For example, when the first switch Q1 is a first MOS transistor, the drain (first end) of the first MOS transistor is connected to the first input terminal Vin1, and the source (second end) of the first MOS transistor is connected to the first inductor L1 and the second output terminal Vout2. The first MOS transistor can be controlled to be turned on or off based on the signal received by the first MOS transistor, so that it cooperates with the third switch Q3 to achieve a buck-boost function. In this example, a MOS transistor with a parasitic diode or an IGBT with a freewheeling diode is used as the first switch Q1 connected to both ends of the DC power supply 1, so that it can achieve reverse voltage protection and freewheeling functions, which helps to ensure the normal operation of the circuit.

[0077] As an example, the third switch tube Q3 can be a MOS tube, which can be provided with a parasitic diode to achieve overcurrent protection and backflow prevention, or can be provided with no parasitic diode to ensure its responsiveness; alternatively, the third switch tube Q3 can be an IGBT tube, where the IGBT tube can be provided with a freewheeling diode or not; alternatively, the third switch tube Q3 can also be a triode, and the MOS tube, IGBT tube or triode can be selected as the third switch tube Q3 according to actual conditions.

[0078] For example, when the third switch Q3 is a third MOS transistor, the drain (first end) of the third MOS transistor is connected to the first inductor L1 and the first output terminal Vout1, and the source (second end) of the third MOS transistor is connected to the second input terminal Vin2 and the second output terminal Vout2. The third MOS transistor can be controlled to be on or off based on a signal received by the gate of the third MOS transistor to determine whether the current output by the first inductor L1 needs to flow back through the bypass path where the third MOS transistor is located to the DC power supply 1. Alternatively, the third switch Q3 can be a third transistor, the collector (first end) of the third transistor is connected to the first inductor L1 and the first output terminal Vout1, the emitter (second end) of the third transistor is connected to the second input terminal Vin2 and the second output terminal Vout2. The third transistor can be controlled to be on or off based on a signal received by the base of the third transistor to determine whether the current output by the first inductor L1 needs to flow back through the bypass path where the third MOS transistor is located to the DC power supply 1. It can be seen that since the third switch tube Q3 is used to determine whether the current at the position is required to flow from the first end to the second end, when the switch tube is turned on, the current can flow from the first end to the second end, and when the switch tube is turned off, the current cannot flow from the first end to the second end. The main function of the switch tube is to utilize it, and it has nothing to do with whether it is connected in parallel with the diode. Therefore, the MOS tube, IGBT tube, triode or other switch tube can be selected according to the actual situation.

[0079] The present invention provides a step-up / step-down conversion circuit. Figure 6As shown, the buck-boost converter circuit includes a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a first inductor L1, a second inductor L2 and a first capacitor C1; a first end of the first switch tube Q1 is connected to the first input terminal Vin1, a second end of the first switch tube Q1 is connected to the first output terminal Vout1 through the first inductor L1, and a second end of the first switch tube Q1 is connected to the second output terminal Vout2; a first end of the second switch tube Q2 is connected to the second input terminal Vin2, a second end of the second switch tube Q2 is connected to the first output terminal Vout1 through the second inductor L2, and a second end of the second switch tube Q2 is connected to the second output terminal Vout2; a first end of the third switch tube Q3 is connected to the first inductor L1 and the first output terminal Vout t1 is connected, the second end of the third switch tube Q3 is connected to the second input end Vin2 and the second output end Vout2; the first end of the fourth switch tube Q4 is connected to the second inductor L2 and the first output end Vout1, and the second end of the fourth switch tube Q4 is connected to the first input end Vin1 and the second output end Vout2; the two ends of the first capacitor C1 are connected to the first output end Vout1 and the second output end Vout2; the first input end Vin1 and the second input end Vin2 are used to connect to the AC power supply 2, and the first output end Vout1 and the second output end Vout2 are used to connect to the subsequent circuit; based on the conduction or disconnection of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4, a boost conversion circuit or a buck conversion circuit is formed.

[0080] As an example, the buck-boost conversion circuit is arranged between the AC power supply 2 and the subsequent circuit. When the AC power supply 2 provides a 220V forward voltage, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 can be controlled to be turned on or off, so that the voltage at the two output ends is greater than or less than the voltage at the two input ends, thereby realizing the boost function; when the AC power supply 2 provides a reverse 220V voltage, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 can be controlled to be turned on or off according to actual needs, so that the voltage at the two output ends is greater than or less than the voltage at the two input ends, thereby realizing the buck function.

[0081] As an example, the first switch tube Q1 and the first inductor L1 are arranged in series between the first input terminal Vin1 and the first output terminal Vout1; the second switch tube Q2 and the second inductor L2 are arranged in series between the second input terminal Vin2 and the first output terminal Vout1; the first end of the third switch tube Q3 is connected to the first inductor L1 and the first output terminal Vout1, and the second end of the third switch tube Q3 is connected to the second input terminal Vin2 and the second output terminal Vout2; the first end of the fourth switch tube Q4 is connected to the second inductor L2 and the first output terminal Vout1, and the second end of the fourth switch tube Q4 is connected to the first input terminal Vin1 and the second output terminal Vout2; the two ends of the first capacitor C1 are connected to the first output terminal Vout1 and the second output terminal Vout2. In this design, a boost conversion circuit or a buck conversion circuit can be formed by turning on or off the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4. For example, the AC power source 2 can be controlled to charge the first inductor L1 / the second inductor L2 and the first capacitor C1, so that the first inductor L1 / the second inductor L2 and the first capacitor C1 store electricity. The first inductor L1 / the second inductor L2 can then be controlled to discharge the first capacitor C1, so that the voltage across the first capacitor C1 increases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 increases, thereby achieving the boost function of the boost converter circuit. For another example, the AC power source 2 can be controlled to charge the first inductor L1 / the second inductor L2 and the first capacitor C1, so that the first inductor L1 / the second inductor L2 and the first capacitor C1 store electricity. The first capacitor C1 can then be controlled to discharge the first inductor L1 / the second inductor L2, so that the voltage across the first capacitor C1 decreases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 decreases, thereby achieving the buck function of the buck converter circuit.

[0082] In one embodiment, the first switch tube Q1 and the second switch tube Q2 are controlled to be in the on state, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in the off state, and the other switch tube of the third switch tube Q3 and the fourth switch tube Q4 are controlled to be turned off or turned on alternately to form a boost conversion circuit; alternatively, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in the off state, and the first switch tube Q1 and the second switch tube Q2 are controlled to be turned on or off alternately to form a buck conversion circuit.

[0083] For example, when the AC power supply 2 provides a 220V forward voltage, the first switch tube Q1 and the second switch tube Q2 are controlled to be in the on state, so that the first switch tube Q1 and the second switch tube Q2 are equivalent to wires, and the fourth switch tube Q4 is controlled to be in the off state, so that the circuit where the fourth switch tube Q4 is located is open. By controlling the conduction or disconnection of the third switch tube Q3, the buck-boost conversion circuit is made into a boost circuit (i.e., a boost conversion circuit) to achieve a boost function. Its input-output relationship is Vpfc=Vi / (1-D), where D is the duty cycle. The specific control process is as follows: (A1) Figure 7 As shown, the third switch Q3 is controlled to be off, and the output voltage of the AC power supply 2 passes through the first inductor L1 and the subsequent circuit in sequence to form a charging loop. During this process, the AC power supply 2 charges the first inductor L1 and the first capacitor C1, so that the first inductor L1 and the first capacitor C1 store electricity. (A2) Figure 8 As shown, the third switch tube Q3 is controlled to be turned on. Since the current of the first inductor L1 cannot change suddenly, a discharge loop is formed between the first inductor L1, the third switch tube Q3, and the AC power source 2. Since the third switch tube Q3 and the first capacitor C1 are arranged in parallel between the first output terminal Vout1 and the second output terminal Vout2, the discharge loop formed by the first inductor L1 charges the first capacitor C1, so that the voltage across the first capacitor C1 increases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 increases, thereby achieving a boost function.

[0084] For another example, when the AC power supply 2 provides a 220V forward voltage, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in the off state, so that the circuit where the third switch tube Q3 and the fourth switch tube Q4 are located is open. By controlling the conduction or disconnection of the first switch tube Q1 and the second switch tube Q2, the step-up / down converter circuit is made into a buck circuit (i.e., a step-down converter circuit) to achieve a step-down function. Its input-output relationship is Vpfc=Vi*D, where D is the duty cycle. The specific control process is as follows: (A3) Figure 9 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be turned on at the same time, and the output voltage of the AC power supply 2 passes through the first inductor L1 and the subsequent circuit in sequence to form a charging loop. During this process, the AC power supply 2 charges the first inductor L1 and the first capacitor C1, so that the first inductor L1 and the first capacitor C1 store electricity. (A4) Figure 10 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be turned off at the same time, a discharge loop is formed between the first inductor L1 and the first capacitor C1, and the first capacitor C1 discharges the first inductor L1, so that the voltage across the first capacitor C1 is reduced, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 is reduced, thereby realizing the step-down function.

[0085] For example, when the AC power source 2 provides a 220V reverse voltage, the first switch tube Q1 and the second switch tube Q2 are controlled to be in the on state, so that the first switch tube Q1 and the second switch tube Q2 are equivalent to wires, and the third switch tube Q3 is controlled to be in the off state, so that the circuit where the third switch tube Q3 is located is open. By controlling the on or off of the fourth switch tube Q4, the buck-boost conversion circuit is made into a boost circuit (i.e., a boost conversion circuit) to achieve a boost function. Its input-output relationship is Vpfc=Vi / (1-D), where D is the duty cycle. The specific control process is as follows: (B1) Figure 11 As shown, the fourth switch Q4 is controlled to be off, and the output voltage of the AC power supply 2 passes through the second inductor L2 and the subsequent circuit in sequence to form a charging loop. During this process, the AC power supply 2 charges the second inductor L2 and the first capacitor C1, so that the second inductor L2 and the first capacitor C1 store electricity. (B2) Figure 12 As shown, the fourth switch tube Q4 is controlled to be turned on. Since the current of the second inductor L2 cannot change suddenly, a discharge loop is formed between the second inductor L2, the fourth switch tube Q4, and the AC power supply 2. Since the fourth switch tube Q4 and the first capacitor C1 are arranged in parallel between the first output terminal Vout1 and the second output terminal Vout2, the discharge loop formed by the second inductor L2 charges the first capacitor C1, so that the voltage across the first capacitor C1 increases, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 increases, thereby achieving a boost function.

[0086] For another example, when the AC power supply 2 provides a 220V reverse voltage, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in the off state, so that the circuit where the third switch tube Q3 and the fourth switch tube Q4 are located is open. By controlling the conduction or disconnection of the first switch tube Q1 and the second switch tube Q2, the step-up / down converter circuit is made into a buck circuit (i.e., a step-down converter circuit) to achieve a step-down function. Its input-output relationship is Vpfc=Vi*D, where D is the duty cycle. The specific control process is as follows: (B3) Figure 13 As shown, the first switch Q1 and the second switch Q2 are controlled to be turned on simultaneously, and the output voltage of the AC power supply 2 passes through the second inductor L2, the first capacitor C1, and the subsequent circuit in sequence to form a charging loop. During this process, the AC power supply 2 charges the second inductor L2 and the first capacitor C1, so that the second inductor L2 and the first capacitor C1 store electricity. (B4) Figure 14 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be turned off at the same time, a discharge loop is formed between the second inductor L2 and the first capacitor C1, and the first capacitor C1 discharges the second inductor L2, so that the voltage across the first capacitor C1 is reduced, that is, the output voltage Vpfc between the first output terminal Vout1 and the second output terminal Vout2 is reduced, thereby realizing the step-down function.

[0087] In this embodiment, the first switch Q1 and the second switch Q2 are controlled to be in an on state. When the fourth switch Q4 is in an off state, the third switch Q3 is controlled to be turned off and on in an alternating manner. Alternatively, when the third switch Q3 is in an off state, the fourth switch Q4 is controlled to be turned off and on in an alternating manner. This allows the buck-boost conversion circuit to achieve a boost function. The third switch Q3 and the fourth switch Q4 are controlled to be in an off state. The first switch Q1 and the second switch Q2 are controlled to be turned on and off in an alternating manner. This allows the buck-boost conversion circuit to achieve a buck function. That is, by controlling the on and off of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4, the buck-boost conversion circuit connected to the AC power source 2 can achieve both a boost function and a buck function. This results in a simple circuit structure and low cost.

[0088] In one embodiment, if Figure 6 As shown, the buck-boost conversion circuit further includes a first anti-backlash unit 3, a second anti-backlash unit 4, a third anti-backlash unit 5 and a fourth anti-backlash unit 6;

[0089] A first end of the first anti-reverse unit 3 is connected to the first inductor L1, and a second end of the first anti-reverse unit 3 is connected to the first output end Vout1;

[0090] A first end of the second anti-reverse unit 4 is connected to the second inductor L2, and a second end of the second anti-reverse unit 4 is connected to the first output end Vout1;

[0091] A first end of the third anti-reverse unit 5 is connected to the second output end Vout2, and a second end of the third anti-reverse unit 5 is connected to the second switch tube Q2 and the second inductor L2;

[0092] A first end of the fourth anti-backward unit 6 is connected to the second output end Vout2 , and a second end of the fourth anti-backward unit 6 is connected to the first switch tube Q1 and the first inductor L1 .

[0093] As an example, when the AC power supply 2 provides a forward 220V voltage and the buck-boost conversion circuit needs to be controlled to achieve a boost function, the first anti-reverse unit 3 and the third anti-reverse unit 5 cooperate to prevent current reverse flow. Specifically, the first switch tube Q1 and the second switch tube Q2 are in the on state, and the fourth switch tube Q4 is controlled to be in the off state, and the following operations are performed alternately: (A1) Figure 6 and Figure 7 As shown, the third switch Q3 is controlled to be disconnected, and the current output by the AC power supply 2 passes through the first inductor L1, the first anti-reverse unit 3, the subsequent circuit and the third anti-reverse unit 5 in sequence, and flows back to the AC power supply 2 to form a charging circuit; (A2) Figure 6 and Figure 8As shown, the third switch tube Q3 is controlled to be turned on, and the output current of the AC power supply 2 passes through the first inductor L1 and the third anti-reverse unit 5 in sequence, and flows back to the AC power supply 2, forming a discharge loop. The first inductor L1 discharges the first capacitor C1 to achieve a boost function. The first anti-reverse unit 3 is arranged between the first inductor L1 and the first output terminal Vout1, and is used to prevent the current from flowing in the opposite direction and prevent the first capacitor C1 from discharging to the ground, so that the buck-boost conversion circuit achieves a boost function.

[0094] Accordingly, when the AC power supply 2 provides a forward 220V voltage and the buck-boost converter circuit needs to be controlled to implement a buck function, the first anti-reverse unit 3, the third anti-reverse unit 5, and the fourth anti-reverse unit 6 cooperate to prevent current reverse flow, specifically controlling the third switch tube Q3 and the fourth switch tube Q4 to be in the off state, and alternately performing the following steps: (A3) Figure 6 and Figure 9 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be turned on at the same time, and the current output by the AC power supply 2 passes through the first inductor L1, the first anti-reverse unit 3, the subsequent circuit and the third anti-reverse unit 5 in sequence, and flows back to the AC power supply 2 to form a charging circuit; (A4) Figure 6 and Figure 10 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be disconnected at the same time, and a discharge loop is formed between the first inductor L1, the first anti-backlash unit 3, the subsequent circuit and the fourth anti-backlash unit 6. The first capacitor C1 discharges the first inductor L1 to achieve a voltage reduction function. The cooperation of the first anti-backlash unit 3 and the fourth anti-backlash unit 6 ensures the current flow direction of the discharge loop.

[0095] As an example, when the AC power supply 2 provides a reverse 220V voltage and it is necessary to control the buck-boost conversion circuit to achieve a boost function, the second anti-reverse unit 4 and the fourth anti-reverse unit 6 cooperate to prevent current reverse flow, specifically controlling the first switch tube Q1 and the second switch tube Q2 to be in the on state, and controlling the third switch tube Q3 to be in the off state, and performing the following operations alternately: (B1) Figure 6 and Figure 11 As shown, the fourth switch tube Q4 is controlled to be turned off, and the current output by the AC power supply 2 passes through the second inductor L2, the second anti-reverse unit 4, the subsequent circuit and the fourth anti-reverse unit 6 in sequence, and flows back to the AC power supply 2 to form a charging circuit; (B2) Figure 6 and Figure 12 As shown, the fourth switch tube Q4 is controlled to be turned on, and the current output by the AC power supply 2 flows back to the AC power supply 2 through the second inductor L2 and the fourth anti-reverse unit 6 in sequence, forming a discharge loop. The second inductor L2 discharges the first capacitor C1 to achieve a boost function. The second anti-reverse unit 4 is arranged between the second inductor L2 and the first output terminal Vout1 to prevent the current from flowing in the opposite direction and prevent the first capacitor C1 from discharging to the ground, so that the buck-boost conversion circuit achieves a boost function.

[0096] Accordingly, when the AC power supply 2 provides a reverse 220V voltage and the buck-boost converter circuit needs to be controlled to implement the buck function, the second anti-reverse unit 4, the fourth anti-reverse unit 6 and the third anti-reverse unit 5 cooperate to prevent current reverse flow, specifically controlling the third switch tube Q3 and the fourth switch tube Q4 to be in the off state, and performing the following steps alternately: (B3) Figure 6 and Figure 13 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be turned on at the same time, and the current output by the AC power supply 2 passes through the second inductor L2, the second anti-reverse unit 4, the first capacitor C1 / the subsequent circuit and the fourth anti-reverse unit 6 in sequence, and flows back to the AC power supply 2 to form a charging circuit; (B4) Figure 6 and Figure 14 As shown, the first switch tube Q1 and the second switch tube Q2 are controlled to be disconnected at the same time, and a discharge loop is formed between the second inductor L2, the second anti-backlash unit 4, the subsequent circuit and the third anti-backlash unit 5. The first capacitor C1 discharges the second inductor L2 to achieve a voltage reduction function. The cooperation of the second anti-backlash unit 4 and the third anti-backlash unit 5 ensures the current flow direction of the discharge loop.

[0097] In this embodiment, the first anti-backlash unit 3 is disposed between the first inductor L1 and the first output terminal Vout1 to ensure that current flows from the first inductor L1 to the first output terminal Vout1; the second anti-backlash unit 4 is disposed between the second inductor L2 and the first output terminal Vout1 to ensure that current flows from the second inductor L2 to the first output terminal Vout1; a first end of the third anti-backlash unit 5 is connected to the second output terminal Vout2, and a second end of the third anti-backlash unit 5 is connected to the second switch tube Q2 and the second inductor L2, so that current flowing back from the second output terminal Vout2 can be input to the second input terminal Vin2 or the second inductor L2, thereby forming a loop; a first end of the fourth anti-backlash unit 6 is connected to the second output terminal Vout2, and a second end of the fourth anti-backlash unit 6 is connected to the first switch tube Q1 and the first inductor L1, so that current flowing back from the second output terminal Vout2 can be input to the first input terminal Vin1 or the first inductor L1, thereby forming a loop. It can be understood that the first anti-reverse unit 3, the second anti-reverse unit 4, the third anti-reverse unit 5 and the fourth anti-reverse unit 6 are provided in the buck-boost conversion circuit to ensure that the buck-boost conversion circuit performs the boost or buck normally, and avoids the reverse flow of current, which affects the realization of its buck-boost function.

[0098] In one embodiment, if Figure 6 As shown, the first anti-reverse unit 3, the second anti-reverse unit 4, the third anti-reverse unit 5 and the fourth anti-reverse unit 6 are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

[0099] As an example, the first anti-reverse unit 3 can be a first diode D1, the anode of the first diode D1 is connected to the first inductor L1, and the cathode of the first diode D1 is connected to the first output terminal Vout1 to ensure that the current flows from the first input terminal Vin1 / first inductor L1 to the first output terminal Vout1 to prevent the current from flowing in the opposite direction.

[0100] As an example, the second anti-reverse unit 4 can be a second diode D2, the anode of the second diode D2 is connected to the second inductor L2, and the cathode of the second diode D2 is connected to the first output terminal Vout1 to ensure that the current flows from the second input terminal Vin2 / the second inductor L2 to the first output terminal Vout1 to prevent the current from flowing in the opposite direction.

[0101] As an example, the third anti-reverse unit 5 can be a third diode D3, the anode of the third diode D3 is connected to the second output terminal Vout2, and the cathode of the third diode D3 is connected to the second switch tube Q2 and the second inductor L2, so that the current flowing back from the second output terminal Vout2 can be input to the second input terminal Vin2 or the second inductor L2, so as to form a loop; since the second end of the third switch tube Q3 and the second end of the fourth switch tube Q4 are both connected to the second output terminal Vout2, the current output by the third switch tube Q3 and the fourth switch tube Q4 can be input to the second input terminal Vin2 or the second inductor L2, so as to form a loop.

[0102] As an example, the fourth anti-reverse unit 6 can be a fourth diode D4, which is connected to the second output terminal Vout2. The cathode of the fourth diode D4 is connected to the first switch tube Q1 and the first inductor L1, so that the current output from the second output terminal Vout2 can be input to the first input terminal Vin1 or the first inductor L1. Since the second end of the third switch tube Q3 and the second end of the fourth switch tube Q4 are both connected to the second output terminal Vout2, the current output by the third switch tube Q3 and the fourth switch tube Q4 can also be input to the first input terminal Vin1 or the first inductor L1, forming a loop.

[0103] In this example, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4 are used to prevent reverse current flow, resulting in a simple overall structure and low cost. It is understood that the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 can also be replaced by a MOS transistor with a parasitic diode or an IGBT transistor with a freewheeling diode. In actual operation, the MOS transistor and the IGBT transistor can be controlled to be turned on or off to control the corresponding circuit. When the MOS transistor and the IGBT transistor are in the closed state, the parasitic diode of the MOS transistor and the freewheeling diode of the IGBT transistor can both prevent current from flowing in the reverse direction.

[0104] In one embodiment, the first switch tube Q1 and the second switch tube Q2 are MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes; the third switch tube Q3 and the fourth switch tube Q4 are MOS tubes, IGBT tubes or triodes.

[0105] As an example, when the buck-boost converter circuit is used in high-frequency scenarios, the first switch Q1 and the second switch Q2 can be MOS transistors with parasitic diodes. When the buck-boost converter circuit is used in low-frequency scenarios, the first switch Q1 and the second switch Q2 can be MOS transistors with parasitic diodes or IGBT transistors with freewheeling diodes, and the selection can be made based on actual conditions. For example, when the first switch Q1 and the second switch Q2 are first and second MOS transistors, respectively, the drain (first end) of the first MOS transistor is connected to the first input terminal Vin1, and the source (second end) of the first MOS transistor is connected to the first inductor L1; the second switch Q2 is a second MOS transistor with a parasitic diode, the drain (first end) of the second MOS transistor is connected to the second input terminal Vin2, and the source (second end) of the second MOS transistor is connected to the second inductor L2. When AC power source 2 provides a forward 220V voltage, the current output by AC power source 2 flows through the drain and source of the first switching tube Q1, then flows back to AC power source 2 via the parasitic diode of the second switching tube Q2. When AC power source 2 provides a reverse 220V voltage, the current output by AC power source 2 flows through the drain and source of the second switching tube Q2, then flows back to AC power source 2 via the parasitic diode of the first switching tube Q1. When the two input terminals of the buck-boost converter circuit are connected to AC power source 2, the first switching tube Q1 and the second switching tube Q2 connected to the two input terminals are MOS tubes equipped with parasitic diodes or IGBT tubes equipped with freewheeling diodes. They provide reverse voltage protection and freewheeling functions, helping to ensure normal circuit operation.

[0106] As an example, the third switch tube Q3 and the fourth switch tube Q4 can be MOS tubes, which can be provided with parasitic diodes to achieve overcurrent protection and backflow prevention, or can be provided without parasitic diodes to ensure their responsiveness; alternatively, the third switch tube Q3 and the fourth switch tube Q4 can be IGBT tubes, where the IGBT tubes can be provided with freewheeling diodes or not; alternatively, the third switch tube Q3 and the fourth switch tube Q4 can also be triodes, and MOS tubes, IGBT tubes or triodes can be selected as the third switch tube Q3 and the fourth switch tube Q4 according to actual conditions.

[0107] For example, when the third switching transistor Q3 and the fourth switching transistor Q4 are respectively the third MOS transistor and the fourth MOS transistor, the drain (first end) of the third MOS transistor is connected to the first inductor L1 and the first output end Vout1, and the source (second end) of the third MOS transistor is connected to the second input end Vin2 and the second output end Vout2. The third MOS transistor can be controlled to be on or off based on a signal received by the gate of the third MOS transistor to determine whether the current output by the first inductor L1 needs to flow back to the AC power source 2 through the bypass where the third MOS transistor is located. The fourth switching transistor Q4 can be a fourth MOS transistor equipped with a parasitic diode. The drain (first end) of the fourth MOS transistor is connected to the second inductor L2 and the first output end Vout1, and the source (second end) of the fourth MOS transistor is connected to the first input end Vin1 and the second output end Vout2. The fourth MOS transistor can be controlled to be on or off based on a signal received by the gate of the fourth MOS transistor to determine whether the current output by the second inductor L2 needs to flow back to the AC power source through the fourth MOS transistor. Therefore, it can be seen that since the third switch tube Q3 and the fourth switch tube Q4 are used to determine whether the current at the position is required to flow from the first end to the second end, when the switch tube is turned on, the current can flow from the first end to the second end, and when the switch tube is turned off, the current cannot flow from the first end to the second end. The main function of the switch tube is to utilize it, and it has nothing to do with whether the diode is connected in parallel. Therefore, MOS tubes, IGBT tubes, triodes or other switch tubes can be selected according to actual conditions.

[0108] An embodiment of the present utility model provides a PFC circuit, which includes the buck-boost conversion circuit in the above embodiment.

[0109] In this embodiment, by controlling the on / off switching of the switching transistor of the buck-boost converter circuit, the buck-boost converter circuit can achieve both boost and buck functions, resulting in a simple circuit structure and low cost. When applied to a PFC circuit, this buck-boost converter circuit can control the PFC voltage up or down based on actual conditions, significantly widening the adjustable range of the PFC circuit and providing sufficient margin for gain adjustment in subsequent circuits, thereby ensuring the gain adjustment capability of the subsequent circuits.

[0110] An embodiment of the present utility model provides a car, comprising the PFC circuit in the above embodiment.

[0111] In this embodiment, the above-mentioned PFC circuit includes the buck-boost conversion circuit in the above-mentioned embodiment. By controlling the conduction or disconnection of the switch tube in the buck-boost conversion circuit, the buck-boost conversion circuit can realize both the boost function and the buck function. The PFC voltage can be controlled to rise or fall according to actual conditions, which greatly widens the adjustable range of the PFC circuit and provides sufficient margin for the gain adjustment of the subsequent circuit, which helps to ensure the gain adjustment capability of the subsequent circuit. In addition, the overall circuit structure is simple and the cost is low.

[0112] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A step-up / step-down conversion circuit, characterized in that: It includes a first switching tube, a third switching tube, a first inductor and a first capacitor; The first end of the first switch tube is connected to the first input end, the second end of the first switch tube is connected to the first output end via the first inductor, and the second end of the first switch tube is connected to the second output end; The first end of the third switch tube is connected to the first inductor and the first output end, and the second end of the third switch tube is connected to the second input end and the second output end; Two ends of the first capacitor are connected to the first output end and the second output end; The first input terminal and the second input terminal are used to connect to a DC power supply, and the first output terminal and the second output terminal are used to connect to a subsequent circuit; Based on the conduction or disconnection of the first switching tube and the third switching tube, a boost conversion circuit or a buck conversion circuit is formed.

2. The step-up / down conversion circuit according to claim 1, wherein: Controlling the first switch tube to be in an on state, and staggeredly controlling the third switch tube to be off or on, so as to form the boost conversion circuit; Alternatively, the third switch tube is controlled to be in an off state, and the first switch tube is controlled to be on or off in an alternating manner to form the buck conversion circuit.

3. The step-up / down conversion circuit according to claim 1, wherein: The buck-boost conversion circuit further includes a first anti-backlash unit, a third anti-backlash unit and a fourth anti-backlash unit; A first end of the first anti-reverse unit is connected to the first inductor, and a second end of the first anti-reverse unit is connected to the first output end; The first end of the third anti-reverse unit is connected to the second output end and the second end of the third switch tube, and the second end of the third anti-reverse unit is connected to the second input end; A first end of the fourth anti-backward unit is connected to the second output end, and a second end of the fourth anti-backward unit is connected to the first switch tube and the first inductor.

4. The step-up / down conversion circuit according to claim 3, wherein: The first anti-reverse unit, the third anti-reverse unit and the fourth anti-reverse unit are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

5. The step-up / down conversion circuit according to claim 1, wherein: The first switch tube is a MOS tube provided with a parasitic diode or an IGBT tube provided with a freewheeling diode; The third switch tube is a MOS tube, an IGBT tube or a triode.

6. A step-up / step-down conversion circuit, characterized in that: It includes a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first inductor, a second inductor and a first capacitor; The first end of the first switch tube is connected to the first input end, the second end of the first switch tube is connected to the first output end via the first inductor, and the second end of the first switch tube is connected to the second output end; The first end of the second switch tube is connected to the second input end, the second end of the second switch tube is connected to the first output end via the second inductor, and the second end of the second switch tube is connected to the second output end; The first end of the third switch tube is connected to the first inductor and the first output end, and the second end of the third switch tube is connected to the second input end and the second output end; The first end of the fourth switch tube is connected to the second inductor and the first output end, and the second end of the fourth switch tube is connected to the first input end and the second output end; Two ends of the first capacitor are connected to the first output end and the second output end; The first input terminal and the second input terminal are used to connect to an AC power supply, and the first output terminal and the second output terminal are used to connect to a subsequent circuit; Based on the conduction or disconnection of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube, a boost conversion circuit or a buck conversion circuit is formed.

7. The step-up / down conversion circuit according to claim 6, wherein: controlling the first switch tube and the second switch tube to be in an on state, controlling one of the third switch tube and the fourth switch tube to be in an off state, and alternately controlling the other of the third switch tube and the fourth switch tube to be turned on or off to form a boost conversion circuit; Alternatively, the third switch tube and the fourth switch tube are controlled to be in an off state, and the first switch tube and the second switch tube are alternately controlled to be turned on or off at the same time, so as to form a step-down conversion circuit.

8. The step-up / down conversion circuit according to claim 6, wherein: The buck-boost conversion circuit further includes a first anti-backlash unit, a second anti-backlash unit, a third anti-backlash unit and a fourth anti-backlash unit; A first end of the first anti-reverse unit is connected to the first inductor, and a second end of the first anti-reverse unit is connected to the first output end; A first end of the second anti-reverse unit is connected to the second inductor, and a second end of the second anti-reverse unit is connected to the first output end; A first end of the third anti-reverse unit is connected to the second output end, and a second end of the third anti-reverse unit is connected to the second switch tube and the second inductor; A first end of the fourth anti-backward unit is connected to the second output end, and a second end of the fourth anti-backward unit is connected to the first switch tube and the first inductor.

9. The step-up / down conversion circuit according to claim 8, wherein: The first anti-reverse unit, the second anti-reverse unit, the third anti-reverse unit and the fourth anti-reverse unit are diodes, MOS tubes with parasitic diodes or IGBT tubes with freewheeling diodes.

10. The step-up / down conversion circuit according to claim 6, wherein: The first switching tube and the second switching tube are MOS tubes provided with parasitic diodes or IGBT tubes provided with freewheeling diodes; The third switch tube and the fourth switch tube are MOS tubes, IGBT tubes or triodes.

11. A PFC circuit, characterized in that: The invention comprises the step-up / step-down conversion circuit according to any one of claims 1 to 10.

12. An automobile, characterized in that: The PFC circuit according to claim 11 is included.

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