Bidirectional AC-DC conversion circuit and power supply system
By optimizing the structure through a MOSFET three-phase full-bridge rectifier circuit and an interleaved synchronous BUCK/BOOST circuit, the problems of low efficiency and poor reliability of traditional bidirectional AC/DC converter circuits are solved, achieving high-efficiency power conversion and precise motor control, while reducing costs and failure rates.
Patent Information
- Application Number
- CN202520555610.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2035-03-27
AI Technical Summary
Traditional bidirectional AC/DC converters have low conversion efficiency and poor reliability, making it difficult to achieve precise control. Furthermore, their complex circuit structure cannot meet the needs of motors in field weakening control and load driving.
The system employs a three-phase full-bridge rectifier circuit with MOSFETs, combined with a π-type filter circuit and an interleaved synchronous BUCK/BOOST circuit. This optimizes the two-stage topology, enabling efficient AC/DC and DC/DC conversion. Furthermore, it precisely adjusts the voltage through field weakening control and FOC control algorithms.
It improves conversion efficiency and energy utilization, enables precise control of the motor, reduces manufacturing costs and failure rate, and extends the service life of the power supply system.
Smart Images
Figure CN223957467U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of power electronics, more particularly, it relates to a bidirectional AC-DC conversion circuit and power system. BACKGROUND
[0002] In the field of power electronics, with the development of new energy technology and the wide application of various electrical equipment, the demand for bidirectional AC-DC conversion is increasing.
[0003] In the gasoline generator system, the traditional bidirectional AC-DC conversion circuit has many shortcomings. On the one hand, its conversion efficiency is low, and a large amount of energy is lost in the AC-DC or DC-AC conversion process, reducing energy utilization. On the other hand, the control strategy is relatively simple, and it is difficult to achieve accurate control of the motor and other loads. For example, in the case of weak magnetic control of the motor to expand the speed range or flexible voltage adjustment when starting and driving the load, the traditional converter often cannot meet the requirements. In addition, the circuit structure of the traditional bidirectional AC-DC conversion circuit is complex, resulting in poor reliability and limiting the application in the conversion process. SUMMARY
[0004] The utility model aims at providing a bidirectional AC-DC conversion circuit and power system, which solves the problem of insufficient conversion efficiency and reliability of the current bidirectional AC-DC conversion circuit.
[0005] The above technical purpose of the utility model is realized by the following technical scheme:
[0006] In a first aspect, the utility model provides a bidirectional AC-DC conversion circuit, which comprises a π-type filter circuit connected in parallel to a DC power supply, two half-bridge circuits connected in parallel to the π-type filter circuit, a bus connected in parallel to the half-bridge circuits, and a three-phase full-bridge rectifier circuit connected in parallel to the bus; wherein the three-phase full-bridge rectifier circuit is composed of MOS tubes.
[0007] When the bidirectional AC-DC conversion circuit is in a forward working state, the two half-bridge circuits act as interleaved synchronous BUCK circuits to realize conversion from high voltage to low voltage.
[0008] When the bidirectional AC-DC conversion circuit is in a reverse working state, the two half-bridge circuits act as interleaved synchronous BOOST circuits to realize conversion from low voltage to high voltage.
[0009] In an implementation scheme, the π-type filter circuit comprises a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, and a third inductor.
[0010] The sixth capacitor and the seventh capacitor are connected in parallel on the direct current power supply, one end of the sixth capacitor connected with the positive pole of the direct current power supply is connected with one end of the third inductor, and the other end of the third inductor is connected with one end of the fifth capacitor.
[0011] The fourth capacitor and the fifth capacitor are connected in parallel on the direct current power supply.
[0012] In an implementation scheme, the fourth capacitor and the sixth capacitor are electrolytic capacitors, and the fifth capacitor and the seventh capacitor are ceramic capacitors.
[0013] In an implementation scheme, the two half-bridge circuits include a first half-bridge circuit and a second half-bridge circuit.
[0014] The first half-bridge circuit includes a seventh MOS tube, a ninth MOS tube and a first inductor, the source of the seventh MOS tube and the drain of the ninth MOS tube are respectively connected with one end of the first inductor.
[0015] The second half-bridge circuit includes an eighth MOS tube, a tenth MOS tube and a second inductor, the source of the eighth MOS tube and the drain of the tenth MOS tube are respectively connected with one end of the second inductor.
[0016] The other end of the first inductor and the second inductor is connected with one end of the fourth capacitor.
[0017] In an implementation scheme, the first inductor and the second inductor are used as power inductors as energy storage elements.
[0018] In an implementation scheme, the bus includes a third capacitor, a second capacitor and a first capacitor connected in parallel in sequence on the half-bridge circuit.
[0019] In an implementation scheme, the first capacitor and the third capacitor are metal thin film capacitors, and the second capacitor is a bus capacitor.
[0020] In an implementation scheme, the three-phase full-bridge rectifier circuit includes a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube.
[0021] The source of the first MOS tube and the drain of the fourth MOS tube are connected to constitute a first bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the first bridge arm is connected with a first wiring terminal of the three-phase motor.
[0022] The source of the second MOS tube and the drain of the fifth MOS tube are connected to constitute a second bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the second bridge arm is connected with the first wiring terminal of the three-phase motor.
[0023] The third MOS tube source is connected with the sixth MOS tube drain to form a third bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the third bridge arm is connected with the third wiring terminal of the three-phase motor.
[0024] The third bridge arm, the second bridge arm and the first bridge arm are connected in parallel on the bus in sequence.
[0025] In an implementation scheme, the node after the drain of the first MOS tube, the second MOS tube and the third MOS tube is connected with one end of the first capacitor, and the node after the source of the fourth MOS tube, the fifth MOS tube and the sixth MOS tube is connected with the other end of the first capacitor.
[0026] In a second aspect, the utility model provides a power supply system, including three-phase motor, like the utility model's first aspect provides a kind of bidirectional AC / DC conversion circuit and direct current power supply connected in sequence.
[0027] Compared with prior art, the utility model has the following beneficial effects:
[0028] 1, the utility model provides a kind of bidirectional AC / DC conversion circuit by adopting MOS tube three-phase full-bridge rectification and the mode of input directly accessing three-phase bridge arm, combines optimized two-stage topology structure, greatly reduces the conduction loss in AC / DC conversion process, improves rectification efficiency;In DC / DC stage, synchronous BUCK and reverse BOOST function can accurately adjust output voltage according to the actual demand of motor, realizes efficient bidirectional electric energy conversion, effectively improves energy utilization.
[0029] 2, the utility model provides a kind of bidirectional AC / DC conversion circuit has simple circuit structure, efficiently utilizes power device, reduces manufacturing cost.Meanwhile, high reliability reduces failure and maintenance cost.
[0030] 3, the utility model provides a kind of bidirectional AC / DC conversion circuit perfect protection circuit and stable filter circuit, effectively improves the operation reliability under the weak magnetic working condition and drag working condition of three-phase motor, prolongs the service life of power supply system, guarantees the stable operation of power supply system. BRIEF DESCRIPTION OF DRAWINGS
[0031] The drawings described herein are used to provide further understanding of the embodiments of the utility model, constitute a part of this application, and do not constitute the limitation to the embodiments of the utility model.In the drawings:
[0032] Figure 1 The structure diagram of bidirectional AC / DC conversion circuit provided by the embodiments of the utility model is shown;
[0033] Figure 2 The principle block diagram of power supply system provided by the embodiments of the utility model is shown.
[0034] Reference signs and the description of the drawings:
[0035] L1, first inductance; L2, second inductance; L3, third inductance; C1, first capacitance; C2, second capacitance; C3, third capacitance; C4, fourth capacitance; C5, fifth capacitance; C6, sixth capacitance; C7, seventh capacitance; Q1, first MOS tube; Q2, second MOS tube; Q3, third MOS tube; Q4, fourth MOS tube; Q5, fifth MOS tube; Q6, sixth MOS tube; Q7, seventh MOS tube; Q8, eighth MOS tube; Q9, ninth MOS tube; Q10, tenth MOS tube. DETAILED DESCRIPTION
[0036] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will be further described in detail in combination with the embodiments and drawings. The schematic embodiments and the description thereof are only used to explain the utility model, and should not be regarded as a limitation of the utility model.
[0037] It should be noted that the term "include" or "may include" used in various embodiments of the present application indicates the existence of the claimed function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their synonyms only mean to indicate a specific feature, number, step, operation, element, component or combination of the foregoing, and should not be understood as first excluding the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing.
[0038] It should be understood that terms such as "first", "second" are only used for description purposes, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, the meaning of "multiple" is two or more than two, unless otherwise specifically limited.
[0039] Please refer to Figure 1 , Figure 1 The structure diagram of the bidirectional AC-DC conversion circuit provided by the embodiment of the utility model is as follows: Figure 1As shown, the bidirectional AC / DC converter circuit includes a π-type filter circuit connected in parallel to the DC power supply, two half-bridge circuits connected in parallel to the π-type filter circuit, a bus connected in parallel to the half-bridge circuit, and a three-phase full-bridge rectifier circuit connected in parallel to the bus; wherein, the three-phase full-bridge rectifier circuit is composed of MOSFETs.
[0040] Among them, the two half-bridge circuits, when the bidirectional AC-DC converter circuit is in the positive working state, serve as interleaved synchronous BUCK circuits to realize the conversion from high voltage to low voltage.
[0041] When the bidirectional AC / DC converter is in reverse operation, the two half-bridge circuits act as interleaved synchronous BOOST circuits to achieve the conversion from low voltage to high voltage.
[0042] Specifically, the front-end topology of this embodiment adopts a conventional three-phase full-bridge topology, namely a three-phase full-bridge rectifier circuit, and the rear-end adopts two half-bridge circuits connected in parallel, which are used as the topology for interleaved synchronous BUCK circuit and BOOST circuit.
[0043] When the circuit is in the forward operating state, the motor generates a three-phase AC voltage, which is controlled by a three-phase full-bridge for field weakening, thus accurately controlling the bus voltage. The subsequent stage is an interleaved synchronous BUCK circuit, which realizes the conversion of DC high voltage to low voltage and can output DC voltage according to user needs.
[0044] When the circuit is in reverse operation, the DC power supply is boosted. The bus voltage can be selected according to the characteristics of the three-phase motor, effectively utilizing energy. The boosted bus then performs sensorless FOC control, precisely controlling the starting and speed of the three-phase motor.
[0045] like Figure 1 As shown, the π-type filter circuit includes a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, and a third inductor L3; the sixth capacitor C6 and the seventh capacitor C7 are connected in parallel to the DC power supply, one end of the sixth capacitor C6 connected to the positive terminal of the DC power supply is connected to one end of the third inductor L3, and the other end of the third inductor L3 is connected to one end of the fifth capacitor C5; the fourth capacitor C4 and the fifth capacitor C5 are connected in parallel to the DC power supply.
[0046] The fourth capacitor C4 and the sixth capacitor C6 are electrolytic capacitors, and the fifth capacitor C5 and the seventh capacitor C7 are ceramic capacitors.
[0047] The two half-bridge circuits include a first half-bridge circuit and a second half-bridge circuit;
[0048] The first half-bridge circuit comprises a seventh MOS tube Q7, a ninth MOS tube Q9 and a first inductor L1, the source of the seventh MOS tube Q7 and the drain of the ninth MOS tube Q9 are connected with one end of the first inductor L1 respectively;
[0049] The second half-bridge circuit comprises an eighth MOS tube Q8, a tenth MOS tube Q10 and a second inductor L2, the source of the eighth MOS tube Q8 and the drain of the tenth MOS tube Q10 are connected with one end of the second inductor L2 respectively;
[0050] The other end of the first inductor L1 and the second inductor L2 is connected with one end of the fourth capacitor C4.
[0051] The first inductor L1 and the second inductor L2 are used as power inductors for energy storage elements.
[0052] The bus comprises a third capacitor C3, a second capacitor C2 and a first capacitor C1 connected in parallel in sequence on the half-bridge circuit.
[0053] The first capacitor C1 and the third capacitor C3 are metal thin film capacitors, and the second capacitor C2 is a bus capacitor.
[0054] The three-phase full-bridge rectifier circuit comprises a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3, a fourth MOS tube Q4, a fifth MOS tube Q5 and a sixth MOS tube Q6;
[0055] The source of the first MOS tube Q1 and the drain of the fourth MOS tube Q4 are connected to constitute a first bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the first bridge arm is connected with a first wiring terminal of the three-phase motor;
[0056] The source of the second MOS tube Q2 and the drain of the fifth MOS tube Q5 are connected to constitute a second bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the second bridge arm is connected with the first wiring terminal of the three-phase motor;
[0057] The source of the third MOS tube Q3 and the drain of the sixth MOS tube Q6 are connected to constitute a third bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the third bridge arm is connected with a third wiring terminal of the three-phase motor;
[0058] The third bridge arm, the second bridge arm and the first bridge arm are connected in parallel in sequence on the bus.
[0059] The node after the drain of the first MOS tube Q1, the second MOS tube Q2 and the third MOS tube Q3 is connected with one end of the first capacitor C1, and the node after the source of the fourth MOS tube Q4, the fifth MOS tube Q5 and the sixth MOS tube Q6 is connected with the other end of the first capacitor C1.
[0060] AsFigure 1 As shown, now from left to right as a forward working state, from right to left as reverse working state, reverse working state is DCDC-DCAC. The former stage is a three-phase full-bridge composed of six MOS tubes, the first capacitor C1 and the third capacitor C3 are metal film capacitors, the second capacitor C2 is a bus capacitor, the seventh MOS tube Q7, the eighth MOS tube Q8, the ninth MOS tube Q9 and the tenth MOS tube Q10 are four MOS tubes as the latter stage topology. The first inductor L1 and the second inductor L2 are two inductors as the common of the DC side BUCK circuit and the BOOST circuit, the fourth capacitor C4 and the sixth capacitor C6 are electrolytic capacitors, the fifth capacitor C5 and the seventh capacitor C7 are ceramic capacitors, which and the third inductor L3 form a π-type filter network to reduce the impurities of the DC power output voltage.
[0061] When in the forward working state, the first MOS tube Q1 to the sixth MOS tube Q6 are a total of 6 MOS tubes, two by two mutual conduction, through SVPWM control, using the weak magnetic control algorithm to carry out three-phase full-bridge rectification, according to the demand to maintain the size of the bus voltage. The seventh MOS tube Q7, the ninth MOS tube Q9 and the first inductor L1 form a synchronous BUCK circuit, when the seventh MOS tube Q7 is turned on, the first inductor L1 starts to store energy, at this time the ninth MOS tube Q9 is cut off, the fourth capacitor C4 and the sixth capacitor C6 together provide energy for the load; when the seventh MOS tube Q7 is off, the first inductor L1 releases energy, and the fourth capacitor C4 and the sixth capacitor C6 together supply power to the load, while the ninth MOS tube Q9 is turned on to continue to flow. The eighth MOS tube Q8, the tenth MOS tube Q10 and the second inductor L2 form another synchronous BUCK circuit to work with the same control logic. The two synchronous BUCK circuits work staggered, which can effectively reduce the output current ripple, and the synchronous BUCK has higher conversion efficiency, realizes stable voltage reduction output, and meets the user's demand for lower DC voltage under different working conditions.
[0062] When in the reverse working state, take the seventh MOS tube Q7 as an example, when the seventh MOS tube Q7 is turned on, the first inductor L1 stores energy; when the seventh MOS tube Q7 is off, the first inductor L1 releases energy, which is superimposed with the input voltage, and through the ninth MOS tube Q9 to supply power to the load (three-phase motor), realizing the increase of DC voltage. Similarly, the eighth MOS tube Q8, the seventh MOS tube Q7, the seventh MOS tube Q7, the seventh MOS tube Q7, the tenth MOS tube Q10 and the second inductor L2 also work according to the same control logic, and the first inductor L1 and the second inductor L2 work cooperatively to further improve the boosting effect and output stability. At this time, the first MOS tube Q1 to the sixth MOS tube Q6 are controlled by SVPWM, and the motor is started and speed controlled by using FOC control algorithm.
[0063] It should be noted that the MOS tube described above can be used to realize the functions of each part.
[0064] It can be seen that the bidirectional AC-DC conversion circuit has the following effects:
[0065] 1. High conversion efficiency: by adopting MOS tube three-phase full-bridge rectification and directly connecting the input to the three-phase bridge arm, combined with the optimized two-stage topology structure, the conduction loss is greatly reduced in the AC / DC conversion process, and the rectification efficiency is improved; in the DC / DC stage, the synchronous BUCK and reverse BOOST functions can accurately adjust the output voltage according to the actual demand of the motor, realize efficient bidirectional power conversion, and effectively improve the energy utilization rate.
[0066] 2. Precise control: using the weak magnetic control strategy and motor drag control algorithm, the working state of the converter can be monitored and accurately controlled in real time, realizing precise weak magnetic control of the motor and efficient drag control under different working conditions, meeting the operation demand of the motor under various complex working conditions.
[0067] 3. Cost reduction: simple circuit structure, efficient use of power devices, reduces manufacturing cost. At the same time, high reliability reduces failure and maintenance cost.
[0068] 4. High reliability: perfect protection circuit and stable filter circuit, effectively improve the operation reliability under motor weak magnetic working condition and drag working condition, prolong the service life, and ensure stable operation.
[0069] The embodiment also provides a power supply system, comprising a three-phase motor, a bidirectional AC-DC conversion circuit as described above and a DC power supply connected in sequence.
[0070] It can be seen that the power supply system provided by the utility model has the following effects:
[0071] 1. High conversion efficiency: by adopting MOS tube three-phase full-bridge rectification and directly connecting the input to the three-phase bridge arm, combined with the optimized two-stage topology structure, the conduction loss is greatly reduced in the AC / DC conversion process, and the rectification efficiency is improved; in the DC / DC stage, the synchronous BUCK and reverse BOOST functions can accurately adjust the output voltage according to the actual demand of the motor, realize efficient bidirectional power conversion, and effectively improve the energy utilization rate.
[0072] 2. Precise control: using the weak magnetic control strategy and motor drag control algorithm, the working state of the converter can be monitored and accurately controlled in real time, realizing precise weak magnetic control of the motor and efficient drag control under different working conditions, meeting the operation demand of the motor under various complex working conditions.
[0073] 3. Cost reduction: simple circuit structure, efficient use of power devices, reduces manufacturing cost. At the same time, high reliability reduces failure and maintenance cost.
[0074] 4. High reliability: perfect protection circuit and stable filter circuit, effectively improve the operation reliability under the weak magnetic working condition and the drag working condition of the motor, prolong the service life, and guarantee the stable operation.
[0075] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A bidirectional AC-DC conversion circuit, characterized by comprising: The bidirectional AC-DC conversion circuit comprises a π-type filter circuit connected in parallel to a DC power supply, two half-bridge circuits connected in parallel to the π-type filter circuit, a bus connected in parallel to the half-bridge circuits, and a three-phase full-bridge rectifier connected in parallel to the bus; wherein the three-phase full-bridge rectifier is composed of MOS transistors. The two half-bridge circuits function as interleaved synchronous BUCK circuits to realize conversion from high voltage to low voltage when the bidirectional AC-DC conversion circuit is in a forward working state. The two half-bridge circuits function as interleaved synchronous BOOST circuits to realize conversion from low voltage to high voltage when the bidirectional AC-DC conversion circuit is in a reverse working state.
2. A bidirectional AC-DC converter circuit according to claim 1, characterized in that The π-type filter circuit comprises a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, and a third inductor. The sixth capacitor and the seventh capacitor are connected in parallel to the DC power supply, one end of the sixth capacitor connected to the positive pole of the DC power supply is connected to one end of the third inductor, and the other end of the third inductor is connected to one end of the fifth capacitor. The fourth capacitor and the fifth capacitor are connected in parallel to the DC power supply.
3. A bidirectional AC-DC converter circuit according to claim 2, characterized in that The fourth capacitor and the sixth capacitor are electrolytic capacitors, and the fifth capacitor and the seventh capacitor are ceramic capacitors.
4. A bidirectional AC-DC converter circuit according to claim 2, characterized in that The two half-bridge circuits comprise a first half-bridge circuit and a second half-bridge circuit. The first half-bridge circuit comprises a seventh MOS transistor, a ninth MOS transistor, and a first inductor, the source of the seventh MOS transistor and the drain of the ninth MOS transistor are respectively connected to one end of the first inductor. The second half-bridge circuit comprises an eighth MOS transistor, a tenth MOS transistor, and a second inductor, the source of the eighth MOS transistor and the drain of the tenth MOS transistor are respectively connected to one end of the second inductor. The other ends of the first inductor and the second inductor are connected to one end of the fourth capacitor.
5. A bidirectional AC-DC converter circuit according to claim 4, characterized in that The first inductor and the second inductor function as power inductors for energy storage elements.
6. A bidirectional AC-DC converter circuit according to claim 4, characterized in that The bus comprises a third capacitor, a second capacitor, and a first capacitor connected in parallel to the half-bridge circuits in sequence.
7. A bidirectional AC-DC converter circuit according to claim 6, characterized in that The first capacitor and the third capacitor are metal film capacitors, and the second capacitor is a bus capacitor.
8. A bidirectional AC-DC converter circuit according to claim 6, characterized in that The three-phase full-bridge rectifier comprises a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, and a sixth MOS transistor. The source of the first MOS transistor and the drain of the fourth MOS transistor are connected to constitute a first bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the first bridge arm is connected to a first wiring terminal of a three-phase motor. The source of the second MOS transistor and the drain of the fifth MOS transistor are connected to constitute a second bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the second bridge arm is connected to the first wiring terminal of the three-phase motor. The source of the third MOS transistor and the drain of the sixth MOS transistor are connected to constitute a third bridge arm of the three-phase full-bridge topology circuit, and the midpoint of the third bridge arm is connected to a third wiring terminal of the three-phase motor. The third bridge arm, the second bridge arm, and the first bridge arm are connected in parallel to the bus in sequence.
9. A bidirectional AC-DC converter circuit according to claim 8, characterized in that The node connected after the drain of the first MOS transistor, the second MOS transistor and the third MOS transistor is connected with one end of the first capacitor, and the node connected after the source of the fourth MOS transistor, the fifth MOS transistor and the sixth MOS transistor is connected with the other end of the first capacitor.
10. A power supply system characterized by comprising: The application relates to a three-phase motor, a bidirectional AC-DC conversion circuit and a DC power supply.