Isolated single-phase converter
By using an isolated single-phase converter topology with coupled differential-mode inductors and LLC resonant units, the problems of high conduction losses and large size of existing single-phase converters are solved, realizing a low-loss, high-efficiency energy conversion and miniaturized isolated converter design.
Patent Information
- Application Number
- CN202520208132.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2035-02-10
AI Technical Summary
Existing single-phase converters suffer from low AC side voltage, high conduction losses, and limited lifespan. In particular, single-stage and two-stage topologies have a large number of semiconductor switching transistors, resulting in higher conduction losses and larger size.
An isolated single-phase converter topology using coupled differential-mode inductors and LLC resonant units is adopted. Through voltage inner loop and current outer loop control, natural current sharing and soft switching are achieved, reducing the number of switching transistors and reducing conduction losses.
It achieves low conduction loss, saves system cost and volume, improves power density and reliability, and supports bidirectional energy flow.
Smart Images
Figure CN223885115U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of power supply, in particular to an isolated single-phase converter. BACKGROUND
[0002] The single-phase converter is a power converter for converting alternating current into direct current. The alternating current is usually taken from an alternating current grid. Therefore, the single-phase converter is required to have the function of power factor correction. In addition, in order to meet the functional safety requirements, the single-phase converter also needs to have the function of electrical isolation, so the isolated single-phase converter is widely used.
[0003] The mainstream single-phase converter currently has a single-stage topology and a two-stage topology. Please refer to the schematic diagram of the traditional single-stage single-phase converter circuit shown in Figure 1 The primary side switching unit includes a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4 connected in series to form a first switch bridge arm, wherein the first switch tube S1 and the second switch tube S2 constitute an upper tube, and the third switch tube S3 and the fourth switch tube S4 constitute a lower tube; a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7 and an eighth switch tube S8 connected in series to form a second switch bridge arm, wherein the fifth switch tube S5 and the sixth switch tube S6 constitute an upper tube, and the seventh switch tube S7 and the eighth switch tube S8 constitute a lower tube, and the first switch bridge arm and the second switch bridge arm are connected in parallel. However, the single-stage single-phase converter has low alternating current side voltage, and when working, there are four semiconductor switch tubes in the current path of the primary side switching unit, so the conduction loss is large.
[0004] Please refer to the schematic diagram of the traditional two-stage single-phase converter circuit shown in Figure 2 The primary side includes a PFC switching unit and a primary side switching unit, the PFC switching unit includes a first switch tube S1 and a second switch tube S2 connected in series to form a first switch bridge arm, a third switch tube S3 and a fourth switch tube S4 connected in series to form a second switch bridge arm, and the first switch bridge arm and the second switch bridge arm are connected in parallel; the primary side switching unit includes a fifth switch tube S5 and a sixth switch tube S6 connected in series to form a third switch bridge arm, a seventh switch tube S7 and an eighth switch tube S8 connected in series to form a fourth switch bridge arm, and the third switch bridge arm and the fourth switch bridge arm are connected in parallel. The two-stage single-phase converter needs a decoupling capacitor, which affects the service life of the single-phase converter, reduces the power density of the single-phase converter, and when working, there are four semiconductor switch tubes in the current path of the primary side, so the conduction loss is large. CONTENT OF THE INVENTION
[0005] The application provides an isolated single-phase converter, comprising: a first switch bridge arm formed by first and second switch tubes connected in series; a second switch bridge arm formed by third and fourth switch tubes connected in series; a third switch bridge arm formed by fifth and sixth switch tubes connected in series, the first switch bridge arm, the second switch bridge arm, the third switch bridge arm and a first capacitor being connected in parallel;
[0006] a first inductor connected between a first end of an alternating current source and a common node of the first switch bridge arm, a second inductor connected between the first end of the alternating current source and a common node of the second switch bridge arm, the first inductor and the second inductor forming a coupled differential mode inductor, a second end of the alternating current source being connected to the common node of the third switch bridge arm;
[0007] a transformer module, a first end of the transformer module being connected to the common node of the first switch bridge arm and the common node of the second switch bridge arm, a second end of the transformer module being connected to a direct current chopper circuit;
[0008] The isolated single-phase converter is controlled by a control loop of an inner voltage loop and an outer current loop.
[0009] Further, the inner voltage loop is used to control the voltage on the first capacitor.
[0010] Further, the outer current loop is used to control the current at the alternating current source end.
[0011] Further, the first, second, third and fourth switch tubes are high-frequency switch tubes, and the fifth and sixth switch tubes are power-frequency switch tubes.
[0012] Further, the first, second, third and fourth switch tubes work at a fixed duty cycle of 50%.
[0013] Further, the transformer module comprises a transformer and a resonant cavity.
[0014] Further, the direct current chopper circuit is a rectifier circuit.
[0015] Further, the rectifier circuit is a full-bridge rectifier circuit, a half-bridge rectifier circuit, a current-doubler rectifier circuit, a voltage-doubler rectifier circuit or a full-wave rectifier.
[0016] Further, the voltage waveform of the first capacitor is a steamed bun waveform.
[0017] Further, the current loop receives an alternating current sampling signal and an alternating current reference signal, and obtains a voltage reference signal of the voltage loop through an operation unit and a regulator; the voltage loop further receives a voltage signal on the first capacitor, and obtains a control signal through the operation unit and the regulator; a PWM controller generates a switching control signal for controlling the first to sixth switch tubes according to the control signal.
[0018] The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that those that can be better understood to the following detailed description. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. Those skilled in the art will appreciate that the conception, and specific embodiments disclosed can be readily utilized as a basis for the designing or modifying other structures or processes for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure in its broadest form. BRIEF DESCRIPTION OF DRAWINGS
[0019] For a more complete understanding of the present disclosure, and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:
[0020] Figure 1 A schematic diagram of a conventional single-stage single-phase converter circuit is shown;
[0021] Figure 2 A schematic diagram of a conventional two-stage single-phase converter circuit is shown;
[0022] Figure 3 A schematic diagram of an isolated single-phase converter according to an embodiment of the present application is shown;
[0023] Figure 4 A schematic diagram of an isolated single-phase converter and its control loop according to an embodiment of the present application is shown;
[0024] Figure 5 A schematic diagram of an isolated single-phase converter according to a specific embodiment of the present application is shown.
[0025] Corresponding and similar elements throughout the figures are designated with corresponding reference numerals. These figures are drawn with the intention of clarifying the relevant aspects of the various embodiments, and are not necessarily drawn to scale. DETAILED DESCRIPTION
[0026] The technical solutions in the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.
[0027] An isolated single-phase converter according to an embodiment of the present application is provided, please refer to Figure 3 and Figure 4 , Figure 3 A schematic diagram of an isolated single-phase converter according to an embodiment of the present application is shown; Figure 4 A schematic diagram of an isolated single-phase converter and its control loop according to an embodiment of the present application is shown. The isolated single-phase converter comprises:
[0028] The first switch arm is formed by the series connection of the first switch Q1 and the second switch Q2; the second switch arm is formed by the series connection of the third switch Q3 and the fourth switch Q4; the third switch arm is formed by the series connection of the fifth switch Q5 and the sixth switch Q6; the first switch arm, the second switch arm, the third switch arm, and the first capacitor C are also present. BUS Parallel connection;
[0029] Connected to AC source u g The first inductance L between the first terminal and the common node A of the first switch bridge arm A Connected to AC source u g The second inductor L between the first terminal and the common node B of the second switch bridge arm B First inductor L A With the second inductor L B Forming a coupled differential-mode inductor, AC source u g The second end is connected to the common node C of the third switch bridge arm;
[0030] The transformer module 110 has its first end connected to the common node A of the first switch bridge arm and the common node B of the second switch bridge arm, and its second end connected to the DC chopper circuit 120.
[0031] The isolated single-phase converter is controlled by the control loop 200, which is the inner voltage loop and the outer current loop.
[0032] In actual operation, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are high-frequency switches, while the fifth switch Q5 and the sixth switch Q6 are power frequency switches. Thus, the first switch arm, the second switch arm, and the third switch arm are connected to the first inductor L. A With the second inductor L B Together, they form a totem-pole PFC. Simultaneously, the first, second, and third switch arms, transformer module 110, and DC chopper circuit 120 together form a DC-DC converter. That is, the first, second, and third switch arms share the power factor correction and DC-DC conversion functions. This isolated single-phase converter can be considered a single-stage topology. It uses fewer components and has a smaller size.
[0033] In actual operation, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 switch at a fixed 50% duty cycle during high-frequency switching. Thus, the duty cycle of the switches in the totem-pole PFC is not adjustable, which can easily cause current imbalance and affect the reliability of the isolated single-phase converter. This application uses a first inductor L... A With the second inductor L B The resulting coupled differential-mode inductor can achieve natural current sharing through differential-mode coupling.
[0034] In actual work, the transformer module 110 includes a transformer and a resonant cavity, the transformer realizes the functions of isolation and high transformation ratio, and the resonant cavity forms an isolated resonant DC / DC converter with the first, second and third switch bridge arms and the DC chopper circuit. Of course, the transformer module can also only include a transformer that realizes the functions of isolation and high transformation ratio. Then the side where the first, second and third switch bridge arms are located can be referred to as the primary side, and the side where the DC chopper circuit 120 is located can be referred to as the secondary side.
[0035] Please refer to Figure 5 the specific embodiment of the isolated single-phase converter of an embodiment shown in the figure, the resonant cavity 111 includes a resonant inductor L r r and a resonant capacitor Cr connected in series, and a transformer leakage inductance L m to form an LLC resonant unit together, so that the switching tubes in the first and second switch bridge arms realize soft switching and improve the efficiency of the single-phase converter.
[0036] As shown in the figure, Figure 5 the DC chopper circuit 120 includes a fourth switch bridge arm formed by the seventh switch tube Q7 and the eighth switch tube Q8 connected in series, and a fifth switch bridge arm formed by the ninth switch tube Q9 and the tenth switch tube Q10 connected in series, and the fourth switch bridge arm and the fifth switch bridge arm are connected in parallel, thus forming a full-bridge rectifier circuit. Then as Figure 5 shown, the functions of totem pole PFC and full-bridge LLC resonant circuit are realized by coupling a differential mode inductor, ten switch tubes, a transformer module with a resonant cavity, and a first capacitor C BUS .
[0037] As Figure 5 shown, the resonant cavity takes LLC resonance as an example, and in actual implementation, it can be LC resonance. As Figure 5 shown, the DC chopper circuit 120 takes a full-bridge rectifier circuit as an example, and in actual implementation, it is a rectifier circuit, which can convert alternating current of the secondary winding of the transformer into direct current, and can also be a half-bridge rectifier circuit, a current-doubler rectifier circuit, a voltage-doubler rectifier circuit, or a full-wave rectifier. In this way, totem pole PFC and LLC, LC, PSFB (phase-shifted full-bridge), DAB (dual active bridge) and other topological structures can be formed.
[0038] As Figure 3 and Figure 4 shown, and referring to Figure 5 , during the positive half cycle of the AC source u g , the sixth switch tube Q6 is controlled to be always on, and the first switch tube Q1 and the third switch tube Q3 are alternately turned on with a certain phase shift angle; during the negative half cycle of the AC source u gDuring the negative half-cycle, the control keeps the fifth switch Q5 constantly on, while the second and fourth switches Q2 and Q4 conduct alternately with a certain phase shift angle. Then, the first capacitor C... BUS The above forms as Figure 3 , Figure 4 and Figure 5 The 50Hz wave in the circuit, with the first switch Q1, second switch Q2, third switch Q3, and fourth switch Q4 switching at a fixed 50% duty cycle, achieves a boost conversion on the primary side, with a turns ratio of 2. Therefore, the first capacitor C... BUS The voltage across it varies between 0V and 620V. Therefore, the first capacitor C BUS Capacitors with smaller capacitance values can be selected, such as film capacitors, ceramic capacitors, or polymer capacitors, with a capacitance value in the pF range being sufficient. As for... Figure 1 and Figure 2 The existing isolated single-phase converter shown has a constant high-voltage DC voltage across capacitor C and bus capacitor Cbus. Therefore, capacitor C and bus capacitor Cbus need to be large-capacity electrolytic capacitors with capacitance values in the μF range. Thus, the isolated single-phase converter of this application saves on system cost and size.
[0039] like Figure 3 and Figure 4 As shown, the first terminal of the DC chopper circuit 120 is the AC terminal, connected to the transformer module 110, and the second terminal is the DC terminal V. DCsec When the selected DC chopper circuit 120 can achieve bidirectional energy flow, such as a full-bridge rectifier circuit, then the isolated single-phase converter of this application can achieve bidirectional energy flow, that is, convert the AC source u... g The alternating current is converted to direct current at terminal V. DCsec DC power; or DC terminal V DCsec The DC power is converted to AC power by the source u. g Alternating current.
[0040] Meanwhile, as mentioned above, the first capacitor C BUS If the voltage on the converter is a 50Hz waveform, then one port is formed, thus the isolated single-phase converter of this application becomes a three-port isolated single-phase converter. When the isolated single-phase converter is used to achieve AC-to-DC conversion, the AC source u... g The input port is formed by the first capacitor C. BUS and the DC terminal V of the DC chopper circuit 120 DCsec This forms the output port; in an isolated single-phase converter used to achieve AC-to-DC conversion, the DC terminal V connected to the DC chopper circuit 120 is... DCsec The input port is formed by the first capacitor C. BUS and exchange source u gForming an output port.
[0041] And as known from the above description, in operation, there are two parallel current paths on the primary side, and there are two semiconductor switches in each current path, so the conduction loss is greatly reduced, which is 1 / 4 of the prior art.
[0042] In actual control, by making the phase angle between the working switch on the first switch bridge arm and the working switch on the second switch bridge arm, a square wave voltage with a duty ratio is formed between points A and B. By adjusting the size of the phase angle, the duty ratio of the voltage between points A and B can be adjusted, and the voltage on the first capacitor C BUS is adjusted. The DC voltage transmitted to the DC end V DCsec through the transformer module 110 and the DC chopper circuit 120 is controllable, and the energy flowing to the primary side of the transformer module 110 is controllable, thereby adjusting the AC current i g on the AC source u g .
[0043] Thus, by controlling the phase angle between the working switch on the first switch bridge arm and the working switch on the second switch bridge arm, the DC voltage on the DC end V DCsec and the AC current i g on the AC source u g are controlled, and by using the coupled differential mode inductance formed by the first inductor L A and the second inductor L B , natural current sharing is also achieved. In actual control, the DC voltage on the DC end V DCsec can also be controlled by controlling the phase angle between the working switch in the DC chopper circuit 120 and the working switch on the primary side.
[0044] In specific implementation, as shown in Figure 4 , the control loop 200 is a voltage inner loop and a current outer loop. The current loop 210 receives an AC current sampling signal i g and an AC current reference signal ig_ref, and obtains a voltage signal Uc_ref through an operation unit 211 and a regulator 212 as a voltage reference signal of the voltage loop 220. At the same time, the voltage loop 220 receives a voltage signal u BUS on the first capacitor C bus , and obtains a control signal through an operation unit 221 and a regulator 222. The PWM controller 230 generates a switching control signal for controlling the switches (first switch to sixth switch) on the primary side according to the control signal, so as to realize the control principle described above. Thus, the control loop with a voltage inner loop and a current outer loop is formed, and the voltage inner loop is used to control the first capacitor C BUSThe voltage on the upper arm, the current outer loop implements a control of the current i of the AC source g .
[0045] While embodiments of the present disclosure and the advantages thereof have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.
[0046] Further, the processes, machines, manufacture, compositions of matter, means, methods, and steps described in the specification are not limited to the specific embodiments described herein. As one skilled in the art will appreciate, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized according to the present disclosure. Accordingly, the appended claims are intended to cover all processes, machines, manufacture, compositions of matter, means, methods, or steps, substantially as such.
Claims
1. An isolated single-phase converter, characterized by The application relates to an isolation type single-phase current transformer. The first switch tube and the second switch tube are connected in series to form a first switch bridge arm; the third switch tube and the fourth switch tube are connected in series to form a second switch bridge arm; the fifth switch tube and the sixth switch tube are connected in series to form a third switch bridge arm; the first switch bridge arm, the second switch bridge arm, the third switch bridge arm and a first capacitor are connected in parallel; a first inductor is connected between a first end of an alternating current source and a common node of the first switch bridge arm; a second inductor is connected between the first end of the alternating current source and a common node of the second switch bridge arm; the first inductor and the second inductor form a coupled differential mode inductor; a second end of the alternating current source is connected to a common node of the third switch bridge arm; a transformer module is connected to the common node of the first switch bridge arm and the common node of the second switch bridge arm at a first end and connected to a direct current chopper circuit at a second end. The isolation type single-phase current transformer is controlled by a control loop of a voltage inner loop and a current outer loop. The voltage inner loop is used for controlling the voltage on the first capacitor. The current outer loop is used for controlling the current at the alternating current source end. The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are high-frequency switch tubes; the fifth switch tube and the sixth switch tube are power-frequency switch tubes.
2. The isolated single-phase converter of claim 1, wherein, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube work at a fixed duty ratio of 50%.
3. An isolated single-phase converter according to claim 1 or 2, characterized in that, The transformer module comprises a transformer and a resonance cavity.
4. An isolated single-phase converter according to claim 3, characterized in that, The direct current chopper circuit is a rectifier circuit.
5. An isolated single-phase converter according to claim 4, characterized in that, The rectifier circuit is a full-bridge rectifier circuit, a half-bridge rectifier circuit, a current-doubler rectifier circuit, a voltage-doubler rectifier circuit or a full-wave rectifier.
6. An isolated single-phase converter according to claim 5, characterized in that The voltage waveform of the first capacitor is a steamed bun waveform.
7. An isolated single-phase converter according to claim 6, characterized in that The current loop receives an alternating current sampling signal and an alternating current reference signal, obtains a voltage reference signal of the voltage loop through an operation unit and a regulator, receives a voltage signal on the first capacitor through the voltage loop, obtains a control signal through the operation unit and the regulator, and generates a switching control signal of the first switch tube to the sixth switch tube according to the control signal.
8. An isolated single-phase converter according to claim 7, characterized in that 9. The isolated single-phase converter of claim 1, wherein, 10. The isolated single-phase converter of claim 1, wherein,