CN117856634A

CN117856634A - Rectifier and control method thereof

Info

Publication number: CN117856634A
Application number: CN202311698580.1A
Authority: CN
Inventors: 郑凯通; 刘文威; 刘博伟; 陈伟球; 冒杰; 石蒙; 林浩灿; 邹宇; 黄晓俊; 周忠健
Original assignee: Guangdong Power Grid Co Ltd; Huizhou Power Supply Bureau of Guangdong Power Grid Co Ltd
Current assignee: Guangdong Power Grid Co Ltd; Huizhou Power Supply Bureau of Guangdong Power Grid Co Ltd
Priority date: 2023-12-12
Filing date: 2023-12-12
Publication date: 2024-04-09

Abstract

The invention discloses a rectifier and a control method thereof, comprising the following steps: the device comprises a rectification module, a four-port embedded module and a direct current output module; the four-port embedded module comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube; the first pole of the first switching tube is used as the first end of the four-port embedded module, the second pole of the first switching tube is connected with the first pole of the fourth switching tube, and the second pole of the fourth switching tube is connected with the first end of the third capacitor; the first pole of the second switching tube is used as the second end of the four-port embedded module, and the second pole of the first switching tube and the third switch. The invention can realize the multidirectional circulation of energy, can realize the multi-level state switching by only four controllable switching devices, has simple circuit structure, is easy to realize the control of the switching devices, and outputs stable direct current voltage.

Description

Rectifier and control method thereof

Technical Field

The invention relates to the technical field of electronic power, in particular to a rectifier and a control method thereof.

Background

In the technical field of electric power conversion, the multilevel converter has the characteristics of low voltage withstand value, low switching working frequency, high unit power factor and small size of a filter device, is widely applied to industrial occasions such as household appliances, automobile military industry, aerospace and the like, related scholars have conducted intensive and extensive research on the topological structure of the multilevel converter, the topological structure of the converter is continuously and iteratively updated to derive a large number of novel topological structures, such as a modularized multilevel converter, a hybrid clamping seven-level converter and the like, can realize conversion between alternating current and direct current voltage, and meets the standardized requirements on the input and output characteristics of voltage and current.

Compared with the traditional two-level rectifier, the two-level rectifier has the advantages that more topological structures of the two-level rectifier are provided, more switching devices are adopted, the cost is relatively increased, the redundancy of the working mode is increased, the capacity of balancing and equalizing the voltage is limited, and more additional hardware control circuits are needed. In addition, a part of novel multilevel topological structures with multilevel cascade connection are also proposed, and the purposes of improving the output level number, increasing the integration level and realizing capacitor self-equalizing voltage are to increase the volume of a rectifier device and the use of a switching device, and the cost and the control difficulty of the rectifier system are increased to a certain extent, so that the efficient stable topological structure which has simple circuits, simple control method, few switching devices and can realize multilevel rectification is explored, and the application requirements of future industrial production can be met.

Disclosure of Invention

The invention provides a rectifier and a control method thereof, which can realize the multidirectional circulation of power, can realize the multi-level state switching by only four controllable switching devices, have simple circuit structure, are easy to realize the control of the switching devices, and output direct-current voltage is stable.

In a first aspect, the present invention provides a rectifier comprising: the device comprises a rectification module, a four-port embedded module and a direct current output module; the rectification module comprises a first input end, a second input end, a first output end and a second output end, an alternating current power supply is connected between the first input end and the second input end, the first output end is respectively connected with the first end of the direct current output module and the first end of the four-port embedded module, the second output end is respectively connected with the second end of the direct current output module and the second end of the four-port embedded module, and the rectification module is used for converting alternating current of the first input end and the second input end into direct current and outputting the direct current; the direct current output module comprises a first capacitor, a second capacitor and a third capacitor; the first end of the first capacitor is used as the first end of the direct current output module, the second end of the first capacitor is connected with the first end of the second capacitor, the second end of the second capacitor is connected with the first end of the third capacitor, and the second end of the third capacitor is used as the second end of the direct current output module; the four-port embedded module comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube; the first pole of the first switching tube is used as the first end of the four-port embedded module, the second pole of the first switching tube is connected with the first pole of the fourth switching tube, and the second pole of the fourth switching tube is connected with the first end of the third capacitor; the first pole of the second switching tube is used as the second end of the four-port embedded module, the second pole of the second switching tube is connected with the first pole of the third switching tube, and the second pole of the third switching tube is connected with the first end of the second capacitor.

Optionally, the rectifying module includes an inductor, a first diode, a second diode, a third diode, and a fourth diode; the first end of the inductor is used as a second input end of the rectifying module, and the second end of the inductor is connected with the anode of the third diode; the cathode of the first diode is used as a first output end of the rectifying module, the anode of the first diode is connected with the cathode of the second diode, and the anode of the second diode is used as a second output end of the rectifying module; the cathode of the third diode is connected with the cathode of the first diode, and the anode of the third diode is connected with the cathode of the fourth diode.

Optionally, the first diode, the second diode, the third diode, and the fourth diode are all fast recovery diodes.

Optionally, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are field effect tubes or insulated gate bipolar transistors.

Optionally, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are all reversely connected in parallel with the body diode.

Optionally, the first capacitor, the second capacitor and the third capacitor are electrolytic capacitors.

Optionally, the capacitance values of the first capacitor, the second capacitor and the third capacitor are equal, and the voltage across the first capacitor, the voltage across the second capacitor and the voltage across the third capacitor are equal.

Optionally, the rectifier further comprises a first voltage clamping diode and a second voltage clamping diode; the anode of the first voltage clamping diode is connected with the first output end of the rectifying module, and the cathode of the first voltage clamping diode is connected with the first end of the direct current output module; the anode of the second voltage clamping diode is connected with the second end of the direct current output module, and the cathode of the second voltage clamping diode is connected with the second output end of the rectifying module.

Optionally, the first voltage clamping diode and the second voltage clamping diode are common unidirectional conducting diodes.

In a second aspect, the present invention provides a control method of a rectifier, applied to the rectifier of any one of the first aspects, the control method of the rectifier comprising: when the alternating current power supply works in a positive half period, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are controlled to be turned off; the first switching tube is controlled to be conducted, and the second switching tube, the third switching tube and the fourth switching tube are all turned off; the first switching tube and the fourth switching tube are controlled to be conducted, and the second switching tube and the third switching tube are both turned off; the first switching tube and the second switching tube are controlled to be conducted, and the third switching tube and the fourth switching tube are both turned off; when the alternating current power supply works in a negative half period, the first switching tube and the second switching tube are controlled to be conducted, and the third switching tube and the fourth switching tube are both turned off; the second switching tube and the third switching tube are controlled to be conducted, and the first switching tube and the fourth switching tube are both turned off; the second switching tube is controlled to be conducted, and the first switching tube, the third switching tube and the fourth switching tube are all turned off; and controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off.

According to the rectifier provided by the embodiment of the invention, the four-port embedded module adopts a switch cross combination structure, the four-port embedded module is used as the four-port embedded into the upper and lower direct current bus sides of the rectifier, seven level state conversion can be realized by adopting four controllable switching devices, and the energy multi-directional circulation is completed; the four switching devices work complementarily and symmetrically in positive and negative half periods, the working frequency is low, the reliability is high, and the characteristics of the four switching devices have the functional characteristics of being popularized to the application of more level rectifiers (such as a buck type multi-level rectifier). The boost conversion of the alternating current-direct current electric energy is realized through seven-level conversion, the power factor is high, and the output electric energy quality is high; three capacitors used by the rectifier bear 1/3 of the direct current output voltage, four switching devices are used for bearing 2/3 of the direct current output voltage, and the voltage resistance of the switching devices is reduced. In the same type of rectifier, the rectifier has the advantages of small number of switching devices, easy modulation control and low cost.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a rectifier according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of another rectifier according to an embodiment of the present invention;

fig. 3 is a switching flowchart of eight operation modes of the rectifier according to the embodiment of the present invention;

FIG. 4 is a diagram of a "0" level synthesis scheme provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of the current path of the rectifier of the present invention in mode one;

FIG. 6 is a schematic diagram of a current path for mode two rectifier operation of the present invention;

FIG. 7 is a schematic diagram of the current path for mode three rectifier operation of the present invention;

FIG. 8 is a schematic diagram of the current path for mode four of the rectifier operation of the present invention;

FIG. 9 is a schematic diagram of the current path for mode five rectifier operation of the present invention;

FIG. 10 is a schematic diagram of the current path for mode six rectifier operation of the present invention;

FIG. 11 is a schematic diagram of the current path of the rectifier of the present invention in mode seven;

FIG. 12 is a schematic diagram of the current path for rectifier mode eight of the present invention;

fig. 13 is a waveform diagram of the ac input voltage Ug, ac input current ig of the rectifier of the present invention;

fig. 14 is a waveform diagram of the rectifier output dc voltage Ud of the present invention;

fig. 15 is a waveform diagram of the voltage Uab between rectifier legs (first node a and second node b) of the present invention;

fig. 16 is a flowchart of a control method of a rectifier according to an embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

Fig. 1 is a schematic structural diagram of a rectifier according to an embodiment of the present invention, as shown in fig. 1, the rectifier includes: the rectifier module 10, the four-port embedded module 20 and the direct current output module 30.

The rectifying module 10 includes a first input terminal IN1, a second input terminal IN2, a first output terminal OUT1 and a second output terminal OUT2, an AC power source AC is connected between the first input terminal IN1 and the second input terminal IN2, the first output terminal OUT1 of the rectifying module 10 is connected with a first end of the dc output module 30 and a first end of the four-port embedded module 20, and the second output terminal OUT2 is connected with a second end of the dc output module 30 and a second end of the four-port embedded module 20, respectively, and the rectifying module 10 is configured to convert the AC power of the first input terminal IN1 and the second input terminal IN2 into dc power.

The direct current output module 30 includes a first capacitor C1, a second capacitor C2, and a third capacitor C3; the first end of the first capacitor C1 is used as the first end of the dc output module 30, the second end of the first capacitor C1 is connected to the first end of the second capacitor C2, the second end of the second capacitor C2 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is used as the second end of the dc output module 30.

The four-port embedded module 20 comprises a first switching tube S1, a second switching tube S2, a third switching tube S3 and a fourth switching tube S4; the first pole of the first switching tube S1 is used as the first end of the four-port embedded module 20, the second pole of the first switching tube S1 is connected with the first pole of the fourth switching tube S4, and the second pole of the fourth switching tube S4 is connected with the first end of the third capacitor C3; the first pole of the second switching tube S2 is used as the second end of the four-port embedded module 20, the second pole of the second switching tube S2 is connected with the first pole of the third switching tube S3, and the second pole of the third switching tube S3 is connected with the first end of the second capacitor C2.

The rectifying module 10 may be various modules having a function of converting alternating current into direct current.

Optionally, the first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are field effect transistors or insulated gate bipolar transistors. The first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are all reversely connected in parallel with the body diode.

Taking the circuit structure shown in fig. 1 as an example, the rectifier includes eight operation modes in total:

(1) The alternating current power supply AC operates in positive half cycles (alternating current input voltage Ug > 0):

operation mode one: and controlling the first switching tube S1, the second switching tube S2, the third switching tube S3 and the second switching tube S2 to be turned off. The current starts from the positive half cycle of the alternating current power supply AC, flows through the first output end OUT1 of the rectifying module, the first capacitor C1, the second capacitor C2 and the third capacitor C3 in sequence, and then returns to the alternating current power supply AC. Bridge arm voltage uab=u1+u2+u3= +ud. Wherein U1 represents the voltage across the first capacitor C1, U2 represents the voltage across the second capacitor C2, U3 represents the voltage across the third capacitor C3, and Ud represents the voltage across the load resistor R.

And a second working mode: the first switching tube S1 is controlled to be conducted, and the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are all turned off. The current starts from a positive half shaft of the alternating current power supply AC, sequentially flows through a first output end OUT1, a first switching tube S1, a body diode of a third switching tube S3, a second capacitor C2 and a third capacitor C3 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab=u2+u3= +2/3Ud.

And a third working mode: the first switching tube S1 and the fourth switching tube S4 are controlled to be conducted, and the second switching tube S2 and the third switching tube S3 are controlled to be turned off. The current starts from the positive half cycle of the alternating current power supply AC, sequentially flows through a first output end OUT1, a first switching tube S1, a fourth switching tube S4 and a third capacitor C3 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= +u3= +1/3Ud.

And a fourth working mode: the first switching tube S1 and the second switching tube S2 are controlled to be conducted, and the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. The current starts from the positive half cycle of the alternating current power supply AC, flows through a first output end OUT1, a first switching tube S1 and a second switching tube S2 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= +0.

(2) The alternating current power supply AC operates in negative half cycles (alternating current input voltage Ug < 0):

working mode five: the first switching tube S1 and the second switching tube S2 are controlled to be conducted, and the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. The current starts from the negative half cycle of the alternating current power supply AC, flows through a first output end OUT1, a first switching tube S1 and a second switching tube S2 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= -0.

Working mode six: the second switching tube S2 and the third switching tube S3 are controlled to be conducted, and the first switching tube S1 and the fourth switching tube S4 are both turned off. The current starts from the negative half cycle of the alternating current power supply AC, sequentially flows through a first output end OUT1, a third switching tube S3 and a second switching tube S2 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= -u1= -1/3Ud.

Working mode seven: the second switching tube S2 is controlled to be conducted, and the first switching tube S1, the third switching tube S3 and the fourth switching tube S4 are all turned off. The current starts from the negative half cycle of the alternating current power supply AC, sequentially flows through a first output end OUT1, a first capacitor C1, a second capacitor C2, a body diode of a fourth switching tube S4 and a second switching tube S2 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= -U1-U2= -2/3Ud.

Working mode eight: the first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. The current starts from the negative half cycle of the alternating current power supply AC, sequentially flows through a first output end OUT1, a first capacitor C1, a second capacitor C2 and a third capacitor C3 of the rectifying module, and then returns to the alternating current power supply AC; bridge arm voltage uab= -U1-U2-U3= -Ud.

Fig. 2 is a schematic structural diagram of another rectifier according to an embodiment of the present invention, as shown in fig. 2, optionally, the rectifying module 10 includes an inductor L, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4.

The first end of the inductor L is used as a second input end IN2 of the rectifying module, and the second end of the inductor L is connected with the anode of the third diode D3; the cathode of the first diode D1 is used as a first output end OUT1 of the rectifying module, the anode of the first diode D1 is connected with the cathode of the second diode D2, and the anode of the second diode D2 is used as a second output end OUT2 of the rectifying module; the cathode of the third diode D3 is connected to the cathode of the first diode D1, and the anode of the third diode D3 is connected to the cathode of the fourth diode D4.

Optionally, the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are all fast recovery diodes.

Optionally, the rectifier further comprises a first voltage clamping diode D5 and a second voltage clamping diode D6; the anode of the first voltage clamping diode D5 is connected with the first output end OUT1 of the rectifying module, and the cathode of the first voltage clamping diode D5 is connected with the first end of the direct current output module 30; an anode of the second voltage clamping diode D6 is connected to the second end of the dc output module 30, and a cathode of the second voltage clamping diode D6 is connected to the second output end OUT2 of the rectifying module.

In some embodiments, the first capacitor C1, the second capacitor C2, and the third capacitor C3 are electrolytic capacitors.

In some embodiments, the capacitance values of the first capacitor C1, the second capacitor C2, and the third capacitor C3 are equal, and the voltage U1 across the first capacitor, the voltage U2 across the second capacitor, and the voltage U3 across the third capacitor are equal. That is to say the capacitance voltage u1=u2=u3=1/3 Ud.

Table 1 shows eight operating mode tables for the rectifier of the present invention, when the AC input voltage Ug >0, the circuit operates in the positive half-cycle, with four operating modes; when the ac input voltage Ug <0, the circuit operates in the negative half cycle, four modes of operation. On and off of the switching tube: "1" means that the switching tube is on, and "0" means that the switching tube is off. The charging and discharging of each capacitor and the bridge arm voltage Uab between the first node a and the second node b have strict one-to-one correspondence under eight working modes.

Table 1 eight operating mode table for rectifiers

In a power frequency period of a power supply, the rectifier has eight working modes (mode one to mode eight), corresponding to eight different bridge arm voltages Uab and capacitor charge and discharge states, and the capacitor voltage values in the eight working modes have the following relations: u1=u2=u3=1/3 Ud; in the positive and negative half periods, the first switching tube S1 and the third switching tube S3 are symmetrically and complementarily operated, the second switching tube S2 and the fourth switching tube S4 are complementarily operated, and at most two switches are operated in each operating mode.

Fig. 3 is a switching flowchart of eight working modes of the rectifier provided by the embodiment of the invention, fig. 4 is a diagram of a mode of synthesizing a "0" level provided by the embodiment of the invention, and in combination with fig. 3 and fig. 4, in a mode (4) and a mode (5) working mode, the third switching tube S3 and the fourth switching tube S4 are turned off simultaneously, and are in a "0" level state at the moment, and can be overlapped into a "AND" logic, that is, synthesized into the same "0" level state for control output, so that the modulation process is simplified, and the difficulty of modulation control design of a switching device is reduced.

Taking the circuit structure shown in fig. 2 as an example, the specific working principle of the rectifier provided in this embodiment is as follows:

when the rectifier works in a power frequency period (frequency f=50hz), seven level states are generated between the first node a and the second node b of the bridge arm: 0. the 1/3Ud, 2/3Ud and Ud, since the "0" level state is a superimposed state of +0, can be regarded as a level state, the rectifier includes eight modes of operation in total. To distinguish the eight operating mode characteristics, the positive and negative half cycles of the AC power supply AC are divided into an AC input voltage Ug >0 and an AC input voltage Ug <0, i.e. the AC input voltage Ug has four operating modes respectively (the solid lines in fig. 5-12 indicate that the rectifier operates in positive or negative half cycles, and the dashed lines indicate the current path direction). According to the invention, seven levels are realized between the first node a and the second node b, so that the sine degree of input current is improved, and the harmonic content of network side current can be further reduced.

fig. 5 is a schematic diagram of a current path of the rectifier according to the first embodiment of the present invention, as shown in fig. 5, the first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. Starting from the positive half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: an inductor L, a third diode D3, a fifth diode D5, a first capacitor C1, a second capacitor C2, a second capacitor C3, a sixth diode D6, and a second diode D2, and then returns to the AC power supply AC; in this process, the inductor L charges the first capacitor C1, the second capacitor C2 and the third capacitor C3 together with the AC power source AC, the charging current is ig-id (where ig represents the output current of the AC power source AC), and the load current id is supplied to the load, the inductance current decreases linearly, and the bridge arm voltage uab=u1+u2+u3= +ud.

Fig. 6 is a schematic diagram of a current path of a rectifier in a second operation mode of the present invention, as shown in fig. 6, the first switching tube S1 is controlled to be turned on, and the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are all turned off. Starting from the positive half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the inductor L, the body diodes of the first switching tube S1 and the third switching tube S3), the second capacitor C2, the third capacitor C3, the sixth diode D6 and the second diode D2, and then returning to the AC power supply AC; in this process, the inductor L and the AC power supply AC charge the second capacitor C2 and the third capacitor C3 together, the charging current is ig-id, the first capacitor C1 provides the load with the load current id, the inductor current decreases continuously and linearly, and the bridge arm voltage uab=u2+u3= +2/3Ud.

Fig. 7 is a schematic diagram of a current path of the rectifier in the third operation mode of the present invention, as shown in fig. 7, the first switching tube S1 and the fourth switching tube S4 are controlled to be turned on, and the second switching tube S2 and the third switching tube S3 are controlled to be turned off. Starting from the positive half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the inductor L, the first switching tube S1, the fourth switching tube S4, the third capacitor C3, the sixth diode D6 and the second diode D2, and then returns to the alternating current power supply AC; in this process, the inductor L and the AC power supply AC charge the third capacitor C3 together, the charging current is ig-id, the first capacitor C1 and the second capacitor C2 provide the load with the load current id, the inductor current decreases continuously and linearly, and the bridge arm voltage uab= +u3= +1/3Ud.

Fig. 8 is a schematic diagram of a current path of a rectifier in a fourth operation mode of the present invention, as shown in fig. 8, the first switching tube S1 and the second switching tube S2 are controlled to be turned on, and the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. Starting from the positive half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the inductor L, the first switching tube S1, the second switching tube S2 and the second diode D2, and then returns to the alternating current power supply AC; in the process, an alternating current power supply AC charges and stores energy to an inductor L, and the inductance current increases linearly; meanwhile, the first capacitor C1, the second capacitor C2 and the third capacitor C3 simultaneously provide the load current id, the bridge arm voltage uab= +0.

fig. 9 is a schematic diagram of a current path of a rectifier in a fifth mode of operation of the present invention, as shown in fig. 9, the first switching tube S1 and the second switching tube S2 are controlled to be turned on, and the third switching tube S3 and the fourth switching tube S4 are controlled to be turned off. Starting from the negative half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the first diode D1, the first switching tube S1, the second switching tube S2, the fourth diode D4 and the inductor L are connected with the first switching tube S2 and then returned to the alternating current power supply AC; in the process, the alternating current power supply AC continuously charges and stores energy to the inductor L, and the inductor current is continuously increased linearly; meanwhile, the first capacitor C1, the second capacitor C2 and the third capacitor C3 simultaneously continuously provide the load current id to the load, and the bridge arm voltage uab= -0.

Fig. 10 is a schematic diagram of a current path of the rectifier of the present invention in the sixth mode, as shown in fig. 10, in which the second switching tube S2 and the third switching tube S3 are controlled to be turned on, and the first switching tube S1 and the fourth switching tube S4 are controlled to be turned off. Starting from the negative half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the first diode D1, the fifth diode D5, the first capacitor C1, the third switching tube S3, the second switching tube S2, the fourth diode D4 and the inductor L are connected with the first capacitor C1 and the third switching tube S2, and then the first capacitor C1 is returned to the alternating current power supply AC; in this process, the AC power supply AC continuously charges and stores energy into the inductor L, the charging current is ig-id, the second capacitor C2 and the third capacitor C3 provide the load with the load current id, the inductance current decreases linearly, and the bridge arm voltage uab= -u1= -1/3Ud.

Fig. 11 is a schematic diagram of a current path of a rectifier according to a seventh mode of operation of the present invention, as shown in fig. 11, in which the second switching tube S2 is controlled to be turned on, and the first switching tube S1, the third switching tube S3, and the fourth switching tube S4 are controlled to be turned off. Starting from the negative half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: the first diode D1, the fifth diode D5, the first capacitor C1, the second capacitor C2, the body diode of the fourth switching tube S4, the second switching tube S2, the fourth diode D4 and the inductor L are connected in series, and then the alternating current power supply AC is returned; in this process, the inductor L and the AC power supply AC charge the first capacitor C1 and the second capacitor C2 together, the charging current is ig-id, the third capacitor C3 provides the load with the load current id, the inductor current continuously decreases linearly, and the bridge arm voltage uab= -U1-u2= -2/3Ud.

Fig. 12 is a schematic diagram of a current path of the rectifier according to the eighth mode of operation of the present invention, and as shown in fig. 12, the first switching tube S1, the second switching tube S2, the third switching tube S3, and the fourth switching tube S4 are controlled to be turned off. Starting from the negative half cycle of the alternating current power supply AC, the current flow paths are as follows in sequence: a first diode D1, a fifth diode D5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a sixth diode D6, a fourth diode D4, and an inductance L, and then returns to the AC power supply AC; in this process, the inductor L and the AC power supply AC charge the first capacitor C1, the second capacitor C2 and the third capacitor C3 together, the charging current is ig-id, and the load current id is supplied to the load, the inductor current continuously decreases linearly, and the bridge arm voltage uab= -U1-U2-U3= -Ud.

To verify the correctness of the proposed design scheme of the rectifier, experimental study is conducted on the rectifier, and specific experimental parameters are shown in the following table 2:

table 2 experimental system parameter settings

Parameter name

Supply voltage

DC side voltage

Inductance

Capacitance device

Switching frequency

Resistor

Parameter value

220V

400V

2.5mH

3300uF

16kHz

50Ω

Fig. 13 is a waveform diagram of the ac input voltage Ug and ac input current ig of the rectifier of the present invention, and it can be seen from the waveform of fig. 13 that the ac input voltage Ug and ac input current ig maintain synchronous sinusoidal waveforms, without distortion, indicating that the unit power factor correction is implemented, and the steady-state operation capability is higher.

Fig. 14 is a waveform diagram of the output dc voltage Ud of the rectifier of the present invention, and as can be seen from the waveform of fig. 14, the output dc voltage Ud can be approximately straight and stabilized at 400V, so as to realize the rectifying function, and verify the feasibility and correctness of the present invention.

Fig. 15 is a waveform diagram of the voltage Uab between rectifier legs (first node a and second node b) of the present invention. From the waveform of fig. 15, it can be seen that the bridge arm voltage Uab presents a sinusoidal step level wave, with seven level states: 0. the invention realizes the functional verification of the topological structure of the rectifier, and has the characteristics of multi-level rectifier and the advantages of the multi-level rectifier.

Optionally, the invention further provides a control method of the rectifier, so as to control the rectifier provided by each embodiment. Fig. 16 is a flowchart of a control method of a rectifier according to an embodiment of the present invention. As shown in fig. 16, the control method of the rectifier includes:

s101, when an alternating current power supply works in a positive half period, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are controlled to be turned off; the first switching tube is controlled to be conducted, and the second switching tube, the third switching tube and the fourth switching tube are all turned off; the first switching tube and the fourth switching tube are controlled to be conducted, and the second switching tube and the third switching tube are both turned off; and controlling the first switching tube and the second switching tube to be conducted, and switching off the third switching tube and the fourth switching tube.

With continued reference to fig. 1, the AC input voltage Ug >0, the AC power supply AC operates in the positive half cycle with four modes of operation:

S102, when the alternating current power supply works in a negative half period, the first switching tube and the second switching tube are controlled to be conducted, and the third switching tube and the fourth switching tube are both turned off; the second switching tube and the third switching tube are controlled to be conducted, and the first switching tube and the fourth switching tube are both turned off; the second switching tube is controlled to be conducted, and the first switching tube, the third switching tube and the fourth switching tube are all turned off; and controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off.

With continued reference to fig. 1, the AC input voltage Ug <0, the AC power supply AC operates in the negative half cycle, with four modes of operation:

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims

1. A rectifier, comprising: the device comprises a rectification module, a four-port embedded module and a direct current output module;

the rectification module comprises a first input end, a second input end, a first output end and a second output end, an alternating current power supply is connected between the first input end and the second input end, the first output end is respectively connected with the first end of the direct current output module and the first end of the four-port embedded module, the second output end is respectively connected with the second end of the direct current output module and the second end of the four-port embedded module, and the rectification module is used for converting alternating current of the first input end and the second input end into direct current for output;

the direct current output module comprises a first capacitor, a second capacitor and a third capacitor; the first end of the first capacitor is used as the first end of the direct current output module, the second end of the first capacitor is connected with the first end of the second capacitor, the second end of the second capacitor is connected with the first end of the third capacitor, and the second end of the third capacitor is used as the second end of the direct current output module;

the four-port embedded module comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube;

a first pole of the first switching tube is used as a first end of the four-port embedded module, a second pole of the first switching tube is connected with a first pole of the fourth switching tube, and a second pole of the fourth switching tube is connected with a first end of the third capacitor;

the first pole of the second switching tube is used as the second end of the four-port embedded module, the second pole of the second switching tube is connected with the first pole of the third switching tube, and the second pole of the third switching tube is connected with the first end of the second capacitor.

2. The rectifier of claim 1, wherein the rectifying module includes an inductor, a first diode, a second diode, a third diode, and a fourth diode;

the first end of the inductor is used as a second input end of the rectifying module, and the second end of the inductor is connected with the anode of the third diode;

the cathode of the first diode is used as a first output end of the rectifying module, the anode of the first diode is connected with the cathode of the second diode, and the anode of the second diode is used as a second output end of the rectifying module;

the cathode of the third diode is connected with the cathode of the first diode, and the anode of the third diode is connected with the cathode of the fourth diode.

3. The rectifier of claim 2 wherein said first diode, said second diode, said third diode and said fourth diode are all fast recovery diodes.

4. The rectifier of claim 1, wherein the first, second, third, and fourth switching transistors are field effect transistors or insulated gate bipolar transistors.

5. The rectifier of claim 1 wherein said first switching tube, said second switching tube, said third switching tube and said fourth switching tube are all antiparallel with a body diode.

6. The rectifier of claim 1 wherein said first, second and third capacitors are electrolytic capacitors.

7. The rectifier of claim 1 wherein the first, second and third capacitors have equal capacitance values and the first, second and third capacitors have equal voltages across them.

8. The rectifier of claim 1, further comprising a first voltage clamp diode and a second voltage clamp diode;

the anode of the first voltage clamping diode is connected with the first output end of the rectifying module, and the cathode of the first voltage clamping diode is connected with the first end of the direct current output module;

the anode of the second voltage clamping diode is connected with the second end of the direct current output module, and the cathode of the second voltage clamping diode is connected with the second output end of the rectifying module.

9. The rectifier of claim 8 wherein said first voltage clamp diode and said second voltage clamp diode are normally on unidirectional diodes.

10. A control method of a rectifier, characterized by being applied to the rectifier according to any one of claims 1 to 9, the control method of the rectifier comprising:

when the alternating current power supply works in a positive half cycle, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are controlled to be turned off; the first switching tube is controlled to be conducted, and the second switching tube, the third switching tube and the fourth switching tube are all turned off; the first switching tube and the fourth switching tube are controlled to be conducted, and the second switching tube and the third switching tube are both turned off; the first switching tube and the second switching tube are controlled to be conducted, and the third switching tube and the fourth switching tube are both turned off;

when the alternating current power supply works in a negative half period, the first switching tube and the second switching tube are controlled to be conducted, and the third switching tube and the fourth switching tube are both turned off; the second switching tube and the third switching tube are controlled to be conducted, and the first switching tube and the fourth switching tube are both turned off; the second switching tube is controlled to be conducted, and the first switching tube, the third switching tube and the fourth switching tube are all turned off; and controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off.