CN209767411U

CN209767411U - Current transformation circuit

Info

Publication number: CN209767411U
Application number: CN201920784935.1U
Authority: CN
Inventors: 刘斌; 李伦全; 江弋横
Original assignee: Nanchang Mawdudi Electronic Technology Co Ltd
Current assignee: Nanchang Mawdudi Electronic Technology Co Ltd
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2019-12-10
Anticipated expiration: 2029-05-28

Abstract

The utility model discloses a converter circuit, it includes three-phase voltage source circuit unit, three-phase rectifier circuit unit, inverter circuit unit. Compared with the traditional three-phase three-line PFC/APF/SVG and the like, the converter circuit of the utility model can only adopt one inductor, can also design the inductor into an equivalent form of two inductors connected in series in a loop according to specific requirements, and has less switching actions, thereby reducing the system cost, only three switching tubes act in a switching period, and the switching loss is small; the current transformation circuit can adopt simple PWM carrier modulation, the control method is simple, and the system efficiency is higher.

Description

Current transformation circuit

Technical Field

The utility model belongs to the technical field of power electronics, concretely relates to converter circuit of low switching loss is applicable to three-phase application.

Background

Inverter circuits are widely used. Among the existing various power supplies, storage batteries, dry batteries, solar batteries and the like are all direct current power supplies, and when the power supplies are required to exchange energy with a public power grid or supply power to an alternating current load, an inverter circuit is required; in addition, power electronic devices such as an active power filter, an inverter for adjusting the speed of an ac motor, an uninterruptible power supply, and an induction heating power supply are widely used, and the core part of the circuit is an inverter circuit.

The traditional bridge type inverter circuit has the advantages of low cost and simple structure, but the problem of dead zones between an upper bridge arm and a lower bridge arm is solved, and the traditional bridge type inverter circuit controller is complex in design and high in system debugging difficulty. The switch voltage resistance is the total input voltage, so that the switch voltage resistance level is high, and the problems limit the switching frequency of the inverter circuit and cause high switching loss. Meanwhile, the harmonic content of the output voltage is rich, so that the volume and the loss of the output filter inductor are large.

Disclosure of Invention

An object of the utility model is to provide a converter circuit, this circuit structure is simple, can effectively reduce power device's switching loss and conduction loss, is favorable to improving circuit efficiency.

The utility model provides a pair of converter circuit, including voltage source circuit unit, rectifier circuit unit, inverter circuit unit. The voltage source circuit unit consists of three sinusoidal voltage sources with three phases of Ua, Ub and Uc forming an angle of 120 degrees with each other, and one ends of the Ua, Ub and Uc power sources are connected together; the rectifier circuit unit consists of a first switch module, a second switch module and a third switch module, each switch module is provided with ports 1, 2 and 3, the port 1 of the first switch module is connected with the other end of Ua, the port 1 of the second switch module is connected with the other end of Ub, and the port 1 of the third switch module is connected with the other end of Uc; the 2 ports of the first switch module, the second switch module and the third switch module are connected together and then connected with one end of an inductor L1, and the 3 ports of the first switch module, the second switch module and the third switch module are connected together and then connected with one end of an inductor L2; the inverter circuit unit is composed of a fourth switch module, the fourth switch module is provided with ports 1 and 2, wherein the port 1 is connected with the other end of the inductor L1, and the port 2 is connected with the other end of the inductor L2.

Preferably, the switch module may be formed by a plurality of power switching tubes and diodes in different combinations.

Preferably, the inverter circuit unit or the first switch module, the second switch module, and the third switch module inside the inverter circuit unit are formed by connecting a plurality of power switches including a reverse diode in different manners. A typical method of attachment is shown in figure 1.

Preferably, the switches used in the switch modules in the circuit are formed by power switch tubes with anti-parallel diodes, and these power switch tubes are connected as shown in fig. 1, which is commonly referred to as a pair-tube connection method.

Preferably, the power switch tube is a combination of a MOSFET, an IGBT or a diode.

Preferably, on the premise of implementing the inductive current control, the reasonable distribution of the current among the three voltage sources is realized through the first switch module, the second switch module and the third switch module.

Preferably, the switching module corresponding to the largest absolute value of the three-phase current is switched at a low frequency by controlling the three-phase rectification circuit unit, and the switching modules corresponding to the other two phases are switched at a high frequency, so that the switching loss is reduced.

The utility model has the advantages that: compared with the traditional three-phase three-line PFC/APF/SVG and the like, only one inductor is adopted (according to the related common sense of circuit theory, the inductors connected in series with L1 and L2 are directly considered to be equivalent to one inductor), and less switching actions are provided, so that the system cost is reduced, only three switching tubes act in a switching period, and the switching loss is small; the current transformation circuit can adopt simple PWM carrier modulation, the control method is simple, and the system efficiency is higher.

Drawings

Fig. 1 is a schematic structural diagram of a converter circuit according to embodiment 1 of the present invention.

Fig. 2(1) and fig. 2(2) are block diagrams of inductive current waveform control according to embodiment 1 of the present invention.

Fig. 3(1) ~ fig. 3(8) are typical switch modules of the three-phase rectifier circuit unit of the present invention.

Fig. 4(1) ~ fig. 4(6) are typical switch modules of the converter circuit unit of the present invention.

Fig. 5(1) ~ fig. 5(10) are circuit diagrams of several exemplary implementations of the present invention.

Fig. 6 is a schematic diagram of a three-phase current waveform and a section definition diagram according to embodiment 1 of the present invention.

Fig. 7 is a schematic view of the interval 1 current loop of embodiment 1 of the present invention.

Fig. 8 is a schematic view of the interval 1 current loop of embodiment 1 of the present invention.

Fig. 9 is a schematic view of the interval 1 current loop of embodiment 1 of the present invention.

Fig. 10 is a schematic view of the interval 1 current loop of embodiment 1 of the present invention.

Fig. 11 is a schematic diagram of the current loop in interval 1 of the derivative topology of fig. 5(1) of the present invention.

Fig. 12 is a schematic structural diagram of a converter circuit according to the present invention.

Detailed Description

to describe the present invention more specifically, the following detailed description will be given with reference to the accompanying drawings and the embodiments. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.

Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein like reference numerals refer to like parts, unless otherwise specified.

Example 1:

As shown in fig. 1, the present embodiment provides a converter circuit, which includes a voltage source circuit unit (1), a rectifier circuit unit (2), and an inverter circuit unit (3). The voltage source circuit (1) is composed of three mutually symmetrical voltage sources of Ua, Ub and Uc, one ends of the power sources of Ua, Ub and Uc are connected together, and the other ends of the power sources of Ua, Ub and Uc are respectively connected with the port 1 of the rectifying circuit (2); the rectifier circuit unit (2) consists of a first switch module (201), a second switch module (202) and a third switch module (203), each switch module is provided with ports 1, 2 and 3, the port 1 of the first switch module (201) is connected with the other end of Ua, the port 1 of the second switch module (202) is connected with the other end of Ub, and the port 1 of the third switch module (203) is connected with the other end of Uc; after the 2 ports of the first switch module (201), the second switch module (202) and the third switch module (203) are connected together, the 2 ports are connected with one end of an inductor L1, and after the 3 ports of the first switch module (201), the second switch module (202) and the third switch module (203) are connected together, the 3 ports are connected with one end of an inductor L2; the inverter circuit unit (3) is composed of S13, S14, S15, S16 and a capacitor C1, wherein a collector of S13 and a collector of S14 are connected with the anode of the capacitor C1, an emitter of S13 and a collector of S15 are connected with the other end of the inductor L1, an emitter of S14 and a collector of S16 are connected with the other end of the inductor L2, and an emitter of S15 and an emitter of S16 are connected with the cathode of the capacitor C1.

As shown in fig. 1, the switch module in the rectifier circuit unit (2) of the present embodiment is: the 2 port is connected to the collector of the switch S1, the emitter of the switch S1 is connected to the collector of the switch S2, the emitter of the switch S2 and the collector of the switch S3 are connected to the 1 port, the emitter of the switch S3 is connected to the collector of the switch S4, and the emitter of the switch S4 is connected to the 3 port.

As shown in fig. 1, the switches in the rectifier circuit unit (2) or the inverter circuit unit in the present embodiment are combined by power switch tubes with inverse diodes. The power switch tube may be a MOS tube or an IGBT tube, and those skilled in the art should understand that the present invention is not limited to the above two semiconductor power switch tubes, but may also be other power elements capable of performing switching operation.

Without much thought, those skilled in the art can derive various other possible switch modules by introducing diodes instead of part of MOS or IGBT, etc., or by appropriately changing the connection method of these switch tubes, wherein the switch modules in several typical three-phase rectifier circuit units refer to fig. 3(1) ~, fig. 3 (8).

The typical rectifying modules obtained by the combination of the switch modules are shown in fig. 4(1) ~ fig. 4(6), but the actual combination is not limited to these, and cannot be exhausted in this document, as long as it conforms to the essence of the present invention, and it is easily obtained by the person skilled in the relevant art, and it is within the scope of the present invention.

One control idea of a converter circuit is: on the premise that the inductive current is controlled to be stable, the reasonable distribution of the inductive current among three voltage sources is realized through the first switch module (201), the second switch module (202) and the third switch module (203).

As shown in fig. 1, since there may be a jump or a sudden change in polarity of an actually input voltage signal, this embodiment shows that a converter circuit also includes an input filter, where the input filter is disposed at a front end of the rectifier circuit unit, and a rectifier bridge output current enters a power grid after being filtered by the filter; in alternative embodiments other than this embodiment, a filter may be added, which is in accordance with the essence of the present invention.

Since the input is a three-phase three-wire system, the three-phase current satisfies equation (1), and as shown in the positive current direction in fig. 6, there are:

i_a+i_b+i_c=0 （1）

It should be noted that even in a system with distortion in the current such as an active filter, the circuit and control method of the present invention are still applicable as long as the three-phase current satisfies the above equation (1). Without loss of generality, the analysis herein is performed on sinusoidal currents as shown in fig. 6, a for phase a current, B for phase B current, and C for phase C current; for convenience of description, the three-phase voltage difference is set to be 120 degrees, and one cycle is set every 360 degrees; considering that the expression is intuitive and convenient, the interval 1-6 is divided by the change point of the phase with the maximum current absolute value.

Without loss of generality, the system is operated in the interval 1, as shown in fig. 6, the absolute value of the phase B current in the interval is larger than the absolute values of the currents in the other two phases, the phase B current is negative, and the phase A, C current is positive. The circuit can work in two states according to different directions of the inductor current.

If the inductor current is l in fig. 7, S9 is turned on in this interval, and a reverse diode path is formed from S9 through S10, so that the inductor current always flows from the B phase, and S10 may be turned on to perform synchronous rectification. The S1 and the S5 are controlled by PWM waves to form a reverse diode path of S1 through S2 and a reverse diode path of S5 through S6, and the duty ratios of S1 and S5 are respectively obtained by a controller, so that the current of the two channels is distributed according to a preset proportion. In the present interval, the switching tubes S3, S4, S7, S8, S11 and S12 are in an off state; the driving signals of S2, S6, S10 may be off, and the current flows through the anti-parallel diodes of these tubes; it is also possible that the high level facilitates the synchronous rectification when S1, S5, S9 are turned on. The driving signal of S13 depends on the unipolar or dual modulation scheme adopted, and can be selected by an engineer in the field according to the spirit of the present invention. In this embodiment, the schematic diagrams of the current loop in the interval 1 are shown in fig. 7 and 8. Fig. 7 shows a loop in which current flows through A, B for two phases, and fig. 8 shows a loop in which current flows through C, B for two phases.

If the inductor current is l in fig. 9, S4 is turned on in this interval, and a reverse diode path is formed from S4 through S3, so that the inductor current always flows from the B phase, and S3 may be turned on to perform synchronous rectification. The S8 and the S12 are controlled by PWM waves to form a reverse diode path of S8 through S7 and a reverse diode path of S12 through S11, and the duty ratios of S8 and S12 are respectively obtained by a controller, so that the current of the two channels is distributed according to a preset proportion. In the present interval, the switching tubes S1, S2, S5, S6, S9 and S10 are in an off state; the driving signals of S3, S3, S11 may be off, and the current flows through the anti-parallel diodes of these tubes; it is also possible that the high level facilitates the synchronous rectification when S4, S8, S12 are turned on. The driving signal of S13 depends on the unipolar or dual modulation scheme adopted, and can be selected by an engineer in the field according to the spirit of the present invention. At this time, the schematic diagrams of the current loop in the interval 1 are shown in fig. 9 and 10. Fig. 9 shows a loop in which current flows through A, B for two phases, and fig. 10 shows a loop in which current flows through C, B for two phases.

Similarly, some other modified circuits of the present invention can also perform the same function, for example, as shown in fig. 5(1), the working circuit thereof is as shown in fig. 11, similar to the working principle described above, and will not be described again here.

The inductance current waveform is controlled by the inverter circuit unit. In this embodiment, the waveform control block diagram of the inductor current is shown in fig. 2(1) and fig. 2 (2). Wherein, fig. 2(1) is a controller, which includes common PID or resonance, repetitive control strategies, etc.; fig. 2(2) is a given description of the controller, and according to the present invention, the current may be given as the upper envelope, the lower envelope, or a mixture of the upper envelope and the lower envelope in fig. 2(2) according to the specific system design requirement, which is characterized in that the absolute value given by the inductor current is the same as the maximum value in the absolute values given by the three-phase symmetric current.

The utility model discloses a gist lies in, inverter circuit unit passes through the cooperation of inductance and rectifier circuit unit (2), wherein inverter circuit no matter be like half-bridge, full-bridge, three level in fig. 4(1) ~ figure 4(6) or not write in the utility model provides a all the other inverter circuits, as long as in fig. 1 with rectifier circuit unit, inductance L1's cooperation, all should fall into within the required protection scope of the utility model.

The circuit topology formed by the rectification unit formed by any switch module in fig. 3(1) ~ (fig. 3) and fig. 8) connected to the power grid and the inversion unit (such as the structure shown in fig. 12) through the inductor is within the protection scope of the present invention.

Those skilled in the art will recognize. Many variations on the above description are possible, so that the examples are only intended to describe one or more particular implementations.

The above description is only for the purpose of describing the preferred exemplary embodiments of the present invention, and is not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. a current transformation circuit, characterized by: the power supply comprises a voltage source circuit unit (1), a rectifying circuit unit (2) and an inverter circuit unit (3), wherein the voltage source circuit unit (1) consists of three voltage sources Ua, Ub and Uc, and one ends of Ua, Ub and Uc power supplies are connected together; the rectifier circuit unit (2) consists of a first switch module (201), a second switch module (202) and a third switch module (203), each switch module is provided with ports 1, 2 and 3, the port 1 of the first switch module (201) is connected with the other end of Ua, the port 1 of the second switch module (202) is connected with the other end of Ub, and the port 1 of the third switch module (203) is connected with the other end of Uc; after the 2 ports of the first switch module (201), the second switch module (202) and the third switch module (203) are connected together, the 2 ports are connected with one end of an inductor L1, and after the 3 ports of the first switch module (201), the second switch module (202) and the third switch module (203) are connected together, the 3 ports are connected with one end of an inductor L2; the inverter circuit unit (3) is composed of a fourth switch module (301), the fourth switch module (301) is provided with ports 1 and 2, wherein the port 1 is connected with the other end of the inductor L1, and the port 2 is connected with the other end of the inductor L2.

2. The current transformer circuit of claim 1, wherein: the first switch module (201) comprises switches S1, S2, S7 and S8 which are connected in series, wherein a port 1 is arranged between the S2 and the S7, one end of the S1 is a port 2, and one end of the S8 is a port 3; the second switch module (202) comprises switches S3, S4, S9 and S10 which are connected in series, wherein a port 1 is arranged between the S4 and the S9, one end of the S3 is a port 2, and one end of the S10 is a port 3; the third switch module (203) comprises switches S5, S6, S11 and S12 which are connected in series, wherein a port 1 is arranged between the S6 and the S11, one end of the S5 is a port 2, and one end of the S12 is a port 3.

3. The variable current circuit as claimed in claim 2, wherein the switch S1 ~ S12 is formed by a power switch tube including a flyback diode.

4. The current transformer circuit of claim 3, wherein: the power switch tube is an MOSFET, an IGBT or a diode.

5. The variable current circuit according to claim 1 ~ 4, further comprising an input filter, wherein said input filter is disposed at the front end of said rectifier circuit unit (2), and the power of the voltage source circuit unit (1) is filtered by the input filter and then connected to said rectifier circuit unit (2).