Inverter topology and pre-charging method

Abstract

The present invention provides a frequency converter topology structure, characterized in that it includes: a power supply unit, a first filtering unit, a rectifier circuit, a first switch group, a first soft switch, a second soft switch, a first capacitor, a second capacitor, a first pre-charging circuit, a second pre-charging circuit, a second switch group, an inverter unit and a second filtering unit, the first soft switch is connected to the first end of the first capacitor, the second soft switch is connected to the first end of the second capacitor, the power supply unit is connected to the first filtering unit, the first filtering unit is connected to the rectifier circuit, the rectifier circuit is connected to the first soft switch and the second soft switch and the first pre-charging circuit and the second pre-charging circuit. In the present invention, adding the first pre-charging circuit and the second pre-charging circuit can eliminate the influence of the parasitic capacitance generated by the PCB board on the first soft switch and the second soft switch, reduce the loss of the first soft switch and the second soft switch, and realize zero voltage conduction of the first soft switch and the second soft switch.

Description

Technical Field

[0001] The invention relates to the technical field of frequency conversion, and in particular to a frequency converter topology structure and a precharging method. Background Art

[0002] The three-level topology with soft switch has the advantages of small current harmonics, low switching stress and voltage change rate, so it is widely used in the medium voltage and high power field. Insulated gate bipolar transistor (IGBT) and fast recovery diode are the main components in the three-level inverter. However, in the prior art, due to the parasitic capacitance of the PCB circuit board itself, the parasitic capacitance has a certain influence on the opening of the soft switch, which will increase the loss of the soft switch. Summary of the invention

[0003] The object of the present invention is to provide a frequency converter topology structure and a precharging method, so as to reduce the influence of the parasitic capacitance of the PCB board itself on the first soft switch and the second soft switch, thereby reducing the loss of the soft switch opening and realizing the zero voltage conduction of the first soft switch and the second soft switch.

[0004] In order to achieve the above-mentioned object, the present invention provides a frequency converter topology structure, comprising: a power supply unit, a first filtering unit, a rectifier circuit, a first switch group, a first soft switch, a second soft switch, a first capacitor, a second capacitor, a first pre-charging circuit, a second pre-charging circuit, a second switch group, an inverter unit and a second filtering unit, wherein the first soft switch is connected to the first end of the first capacitor, the second soft switch is connected to the first end of the second capacitor, the power supply unit is connected to the input end of the first filtering unit, the output end of the first filtering unit is connected to the input end of the rectifier circuit, the output end of the rectifier circuit is connected to the input ends of the first soft switch and the second soft switch and the input ends of the first pre-charging circuit and the second pre-charging circuit, the output end of the first filtering unit is also connected to the input end of the first switch group, the output end of the first switch group is also connected to the second end of the first capacitor and the second end of the second capacitor and the input end of the second switch group, the output end of the second switch group is connected to the input end of the second filtering unit, the output end of the rectifier circuit is also connected to the input end of the inverter unit, and the output end of the inverter unit is also connected to the input end of the second filtering unit.

[0005] Optionally, in the inverter topology structure, the first soft switch and the second soft switch each include an insulated gate bipolar transistor and a diode connected in parallel with the insulated gate bipolar transistor.

[0006] Optionally, in the inverter topology, the rectifier circuit is composed of six diodes.

[0007] Optionally, in the inverter topology structure, the first filtering unit includes an LCL filtering circuit.

[0008] Optionally, in the inverter topology structure, the second filtering unit includes an LC filtering circuit and an impedance.

[0009] Optionally, in the inverter topology, the first switch group includes a third soft switch, a fourth soft switch, a fifth soft switch, a sixth soft switch, a seventh soft switch and an eighth soft switch, the third soft switch and the fourth soft switch are connected in series, the fifth soft switch and the sixth soft switch are connected in series, the seventh soft switch and the eighth soft switch are connected in series, and the third soft switch and the fourth soft switch in series, the fifth soft switch and the sixth soft switch in series, and the seventh soft switch and the eighth soft switch in series are then connected in parallel respectively.

[0010] Optionally, in the inverter topology, the second switch group includes a ninth soft switch, a tenth soft switch, an eleventh soft switch, a twelfth soft switch, a thirteenth soft switch and a fourteenth soft switch, the ninth soft switch and the tenth soft switch are connected in series, the eleventh soft switch and the twelfth soft switch are connected in series, the thirteenth soft switch and the fourteenth soft switch are connected in series, and the ninth soft switch and the tenth soft switch in series, the eleventh soft switch and the twelfth soft switch in series, and the thirteenth soft switch and the fourteenth soft switch in series are then connected in parallel respectively.

[0011] Optionally, in the inverter topology, the inverter unit is composed of six soft switches, and the six soft switches are a fifteenth soft switch, a sixteenth soft switch, a seventeenth soft switch, an eighteenth soft switch, a nineteenth soft switch and a twentieth soft switch.

[0012] Optionally, in the inverter topology, the first pre-charging circuit includes a twenty-first soft switch, an input end of the twenty-first soft switch is connected to the output end of the rectifier circuit, a first diode is connected to the output end of the twenty-first soft switch, a first inductor and a second diode are connected to the first diode, the first inductor and the second diode are connected in parallel, and after being connected in parallel, they are connected to the second end of the first capacitor; the second pre-charging circuit includes a twenty-second soft switch, an input end of the twenty-second soft switch is connected to the output end of the rectifier circuit, a third diode is connected to the output end of the twenty-second soft switch, a second inductor and a fourth diode are connected to the third diode, the second inductor and the fourth diode are connected in parallel, and after being connected in parallel, they are connected to the second end of the second capacitor.

[0013] The present invention also provides a pre-charging method, comprising:

[0014] turning on the first soft switch;

[0015] Turning off the inverter unit;

[0016] The first pre-charging circuit and the second pre-charging circuit are connected;

[0017] The first capacitor and the second capacitor are charged.

[0018] In the inverter topology structure and pre-charging method provided by the present invention, adding a first pre-charging circuit and a second pre-charging circuit can eliminate the influence of the parasitic capacitance generated by the PCB board on the first soft switch and the second soft switch, reduce the loss of the first soft switch and the second soft switch, and achieve zero voltage conduction of the first soft switch and the second soft switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the structure of the inverter topology structure of an embodiment of the present invention;

[0020] In the figure: 110-power supply unit, 120-first filtering unit, 130-rectifier circuit, 140-first switch group, 150-first pre-charging circuit, 160-second pre-charging circuit, 170-second switch group, 180-inverter unit, 190-second filtering circuit, S1-first soft switch, S2-second soft switch, S3-third soft switch, S4-fourth soft switch, S5-fifth soft switch, S6-sixth soft switch, S7-seventh soft switch, S8-eighth soft switch, S9-ninth soft switch, S10-tenth soft switch, S11-eleventh soft switch soft switch, S12-twelfth soft switch, S13-thirteenth soft switch, S14-fourteenth soft switch, S15-fifteenth soft switch, S16-sixteenth soft switch, S17-seventeenth soft switch, S18-eighteenth soft switch, S19-nineteenth soft switch, S20-twentieth soft switch, S21-twenty-first soft switch, S22-twenty-second soft switch, C1-first capacitor, C2-second capacitor, D1-first diode, D2-second diode, D3-third diode, D4-fourth diode, L1-first inductor, L2-second inductor. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0022] Hereinafter, the terms "first", "second", etc. are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It is to be understood that these terms used in this manner are interchangeable where appropriate. Similarly, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0023] Reference Figure 1 , there is parasitic capacitance on the PCB board, and the parasitic capacitance has a certain influence on the conduction of the first soft switch S1 and the second soft switch S2. The present invention provides a frequency converter topology structure, including: a power supply unit 110, a first filtering unit 120, a rectifier circuit 130, a first switch group 140, a first soft switch S1, a second soft switch S2, a first capacitor C1, a second capacitor C2, a first pre-charging circuit 150, a second pre-charging circuit 160, a second switch group 170, an inverter unit 180 and a second filtering unit 190, the first soft switch S1 is connected to the first end of the first capacitor C1, the second soft switch S2 is connected to the first end of the second capacitor C2, the power supply unit 110 is connected to the input end of the first filtering unit 120, and the output end of the first filtering unit 120 is connected The input end of the rectifier circuit 130 and the output end of the rectifier circuit 130 are connected to the input ends of the first soft switch S1 and the second soft switch S2 and the input ends of the first pre-charging circuit 150 and the second pre-charging circuit 160. The output end of the first filtering unit 120 is also connected to the input end of the first switch group 140. The output end of the first switch group 140 is connected to the second end of the first capacitor C1, the second end of the second capacitor C2 and the input end of the second switch group 170. The output end of the second switch group 170 is connected to the input end of the second filtering unit 190. The output end of the rectifier circuit 130 is also connected to the input end of the inverter unit 180. The output end of the inverter unit 180 is also connected to the input end of the second filtering unit 190.

[0024] Furthermore, each of the first soft switch S1 and the second soft switch S2 includes an insulated gate bipolar transistor and a diode connected in parallel with the insulated gate bipolar transistor.

[0025] In this embodiment, the first switch group 140 and the second switch group 170 each include six soft switches, and every two of the six soft switches are connected in series and then connected in parallel with the remaining two groups.

[0026] In this embodiment, the rectifier circuit 130 is composed of six diodes. The rectifier circuit 130 and the first switch group 140 form a Vienna three-level topology structure.

[0027] In this embodiment, the first filtering unit 120 includes an LCL filtering circuit.

[0028] In this embodiment, the second filter unit 180 includes an LC filter circuit and an impedance. The impedance serves as a load. The second filter unit 180 and the second switch group 170 form a T-type three-level topology structure.

[0029] In this embodiment, the first switch group 140 includes a third soft switch S3, a fourth soft switch S4, a fifth soft switch S5, a sixth soft switch S6, a seventh soft switch S7 and an eighth soft switch S8. The third soft switch S3 and the fourth soft switch S4 are connected in series, the fifth soft switch S5 and the sixth soft switch S6 are connected in series, the seventh soft switch S7 and the eighth soft switch S8 are connected in series, and the third soft switch S3 and the fourth soft switch S4 connected in series, the fifth soft switch S5 and the sixth soft switch S6 connected in series, and the seventh soft switch S7 and the eighth soft switch S8 connected in series are then connected in parallel respectively.

[0030] In this embodiment, the second switch group 170 includes a ninth soft switch S9, a tenth soft switch S10, an eleventh soft switch S11, a twelfth soft switch S12, a thirteenth soft switch S13 and a fourteenth soft switch S14, the ninth soft switch S9 and the tenth soft switch S10 are connected in series, the eleventh soft switch S11 and the twelfth soft switch S12 are connected in series, the thirteenth soft switch S13 and the fourteenth soft switch S14 are connected in series, and the ninth soft switch S9 and the tenth soft switch S10, the eleventh soft switch S11 and the twelfth soft switch S12, and the thirteenth soft switch S13 and the fourteenth soft switch S14 connected in series are connected in parallel respectively.

[0031] In this embodiment, the inverter unit 180 is composed of six soft switches, which are a fifteenth soft switch S15, a sixteenth soft switch S16, a seventeenth soft switch S17, an eighteenth soft switch S18, a nineteenth soft switch S19 and a twentieth soft switch S20.

[0032] In this embodiment, the first pre-charging circuit 150 includes a twenty-first soft switch S21, the input end of the twenty-first soft switch S21 is connected to the output end of the rectifier circuit 130, the output end of the twenty-first soft switch S21 is connected to the first diode D1, the first inductor L1 and the second diode D2 are connected to the first diode D1, the first inductor L1 and the second diode D2 are connected in parallel, and are connected to the second end of the first capacitor C1 after being connected in parallel; the second pre-charging circuit 160 includes a twenty-second soft switch S22, the input end of the twenty-second soft switch S22 is connected to the output end of the rectifier circuit 130, the output end of the twenty-second soft switch S22 is connected to the third diode D3, the second inductor L2 and the fourth diode D4 are connected to the third diode D3, the second inductor L2 and the fourth diode D4 are connected in parallel, and are connected to the second end of the second capacitor C2 after being connected in parallel.

[0033] The present invention also provides a precharging method based on a frequency converter topology structure, comprising:

[0034] turning on the first soft switch;

[0035] Turning off the inverter unit;

[0036] The first pre-charging circuit and the second pre-charging circuit are connected;

[0037] The first capacitor and the second capacitor are charged.

[0038] Specifically, the first soft switch S1 is turned on first, and then the fifteenth soft switch S15, the sixteenth soft switch S16 and the seventeenth soft switch S17 are turned off, and then the twenty-first soft switch S21 is turned on, and the first capacitor C1 is pre-charged through the first capacitor C1, the first inductor L1, the first diode D1, the fifteenth soft switch S15, the sixteenth soft switch S16 and the seventeenth soft switch S17, so that the voltage of the first capacitor C1 and the second capacitor C2 increases from 0 to the rated voltage, and finally the first soft switch S1 and the second soft switch S2 are turned on at zero voltage.

[0039] In summary, in the inverter topology structure and pre-charging method provided in the embodiment of the present invention, adding the first pre-charging circuit and the second pre-charging circuit can eliminate the influence of the parasitic capacitance generated by the PCB board on the first soft switch and the second soft switch, reduce the loss of the first soft switch and the second soft switch, and achieve zero voltage conduction of the first soft switch and the second soft switch.

[0040] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A frequency converter topology structure, characterized in that: include: A power supply unit, a first filtering unit, a rectifier circuit, a first switch group, a first soft switch, a second soft switch, a first capacitor, a second capacitor, a first pre-charging circuit, a second pre-charging circuit, a second switch group, an inverter unit, and a second filtering unit, wherein the output end of the first soft switch is connected to the first end of the first capacitor, the output end of the second soft switch is connected to the first end of the second capacitor, the power supply unit is connected to the input end of the first filtering unit, the output end of the first filtering unit is connected to the input end of the rectifier circuit, the output end of the rectifier circuit is connected to the input ends of the first soft switch and the second soft switch and the input ends of the first pre-charging circuit and the second pre-charging circuit, the output end of the first filtering unit is also connected to the input end of the first switch group, the output end of the first switch group is also connected to the second end of the first capacitor and the second end of the second capacitor and the input end of the second switch group, the output end of the second switch group is connected to the input end of the second filtering unit, the output end of the rectifier circuit is also connected to the input end of the inverter unit, and the output end of the inverter unit is also connected to the input end of the second filtering unit; The first switch group includes a third soft switch, a fourth soft switch, a fifth soft switch, a sixth soft switch, a seventh soft switch and an eighth soft switch, wherein the third soft switch is connected in series with the fourth soft switch, the fifth soft switch is connected in series with the sixth soft switch, the seventh soft switch is connected in series with the eighth soft switch, and the third soft switch and the fourth soft switch, the fifth soft switch and the sixth soft switch connected in series, and the seventh soft switch and the eighth soft switch connected in series are respectively connected in parallel; The second switch group includes a ninth soft switch, a tenth soft switch, an eleventh soft switch, a twelfth soft switch, a thirteenth soft switch and a fourteenth soft switch, wherein the ninth soft switch is connected in series with the tenth soft switch, the eleventh soft switch is connected in series with the twelfth soft switch, and the thirteenth soft switch is connected in series with the fourteenth soft switch, and the ninth soft switch and the tenth soft switch, the eleventh soft switch and the twelfth soft switch connected in series, and the thirteenth soft switch and the fourteenth soft switch connected in series are respectively connected in parallel; The first pre-charging circuit includes a twenty-first soft switch, the input end of the twenty-first soft switch is connected to the output end of the rectifier circuit, the output end of the twenty-first soft switch is connected to the cathode of the first diode, the first end of the first inductor and the anode of the second diode are connected to the anode of the first diode, the first inductor and the second diode are connected in parallel, and the second end of the first inductor is connected to the second end of the first capacitor; the second pre-charging circuit includes a twenty-second soft switch, the input end of the twenty-second soft switch is connected to the output end of the rectifier circuit, the output end of the twenty-second soft switch is connected to the anode of the third diode, the first end of the second inductor and the cathode of the fourth diode are connected to the cathode of the third diode, the second inductor and the fourth diode are connected in parallel, and the second end of the second inductor is connected to the second end of the second capacitor.

2. The inverter topology structure according to claim 1, characterized in that: The first soft switch and the second soft switch each include an insulated gate bipolar transistor and a diode connected in parallel with the insulated gate bipolar transistor.

3. The inverter topology structure according to claim 1, characterized in that: The rectifier circuit is composed of six diodes.

4. The inverter topology structure according to claim 1, characterized in that: The first filtering unit includes an LCL filtering circuit.

5. The inverter topology structure according to claim 1, characterized in that: The second filtering unit includes an LC filtering circuit and an impedance.

6. The inverter topology structure according to claim 1, characterized in that: The inverter unit is composed of six soft switches, which are a fifteenth soft switch, a sixteenth soft switch, a seventeenth soft switch, an eighteenth soft switch, a nineteenth soft switch and a twentieth soft switch.

7. A pre-charging method for a frequency converter topology structure according to any one of claims 1 to 6, characterized in that: include: turning on the first soft switch; Turning off the inverter unit; The first pre-charging circuit and the second pre-charging circuit are connected; The first capacitor and the second capacitor are charged.

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