阅读说明：本技术 一种中点有源箝位三电平逆变器、控制方法及控制装置 (Neutral point active clamping three-level inverter, control method and control device ) 是由 苑红 邓福伟 罗劼 李爱刚 于 2020-06-28 设计创作，主要内容包括：本发明适用于逆变器技术领域,提供了一种中点有源箝位三电平逆变器、控制方法及控制装置,中点有源箝位三电平逆变器包括：桥臂单元、与桥臂单元连接的箝位单元、以及与桥臂单元连接的桥臂输出端；桥臂单元包括第一开关管、第二开关管、第三开关管、第四开关管、第一开关管、第二开关管、第三开关管、第四开关管反并联的第一二极管、第二二极管、第三二极管以及第四二极管；箝位单元包括第五开关管、第六开关管、第五开关管以及第六开关管反并联的第五二极管以及第六二极管；第五二极管以及第六二极管为碳化硅二极管。本发明能够减少各个开关管发热不均、提高电能变换效率以及稳定性。(The invention is suitable for the technical field of inverters, and provides a midpoint active clamping three-level inverter, a control method and a control device, wherein the midpoint active clamping three-level inverter comprises the following components: the bridge arm output end is connected with the bridge arm unit; the bridge arm unit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, wherein the first diode, the second diode, the third diode and the fourth diode are connected in anti-parallel; the clamping unit comprises a fifth switching tube, a sixth switching tube, a fifth diode and a sixth diode which are connected with the fifth switching tube and the sixth switching tube in an anti-parallel mode; the fifth diode and the sixth diode are silicon carbide diodes. The invention can reduce the uneven heating of each switching tube and improve the electric energy conversion efficiency and stability.)

1. A midpoint active clamped three level inverter comprising: the bridge arm comprises a bridge arm unit, a clamping unit connected with the bridge arm unit and a bridge arm output end connected with the bridge arm unit;

the bridge arm unit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which are sequentially connected in series, and a first diode, a second diode, a third diode and a fourth diode which are in inverse parallel connection with the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in a one-to-one correspondence manner;

the clamping unit comprises a fifth switching tube, a sixth switching tube, a fifth diode and a sixth diode, wherein the fifth switching tube and the sixth switching tube are sequentially connected in series, the fifth diode and the sixth diode are connected in anti-parallel with the fifth switching tube and the sixth switching tube in a one-to-one correspondence mode, one end, far away from the sixth switching tube, of the fifth switching tube is arranged on a connecting line between the first switching tube and the second switching tube, and one end, far away from the fifth switching tube, of the sixth switching tube is arranged on a connecting line between the third switching tube and the fourth switching tube;

the bridge arm output end is arranged on a connecting line between the second switching tube and the third switching tube;

the fifth switch tube or the fifth diode and the second switch tube or the second diode form a first freewheeling circuit, the sixth switch tube or the sixth diode and the third switch tube or the third diode form a second freewheeling circuit, and the first freewheeling circuit and the second freewheeling circuit form a dual freewheeling circuit for changing a freewheeling path;

the fifth diode and the sixth diode are silicon carbide diodes.

2. The midpoint active clamp three-level inverter of claim 1, further comprising: the voltage division unit is respectively connected with the bridge arm unit and the clamping unit and comprises a first voltage division capacitor and a second voltage division capacitor which are sequentially connected in series, one end, far away from the second voltage division capacitor, of the first voltage division capacitor is connected with one end, far away from the second switch tube, of the first switch tube, and one end, far away from the first voltage division capacitor, of the second voltage division capacitor is connected with one end, far away from the third switch tube, of the fourth switch tube.

3. The midpoint active clamp three-level inverter according to claim 2, wherein an input terminal of the first switch tube is connected to a terminal of the first voltage-dividing capacitor far from the second voltage-dividing capacitor, an output terminal of the first switch tube is connected to an input terminal of the second switch tube and an input terminal of a fifth switch tube, an output terminal of the second switch tube is connected to an input terminal of the third switch tube and an output terminal of the bridge arm, an output terminal of the third switch tube is connected to an input terminal of the fourth switch tube and an output terminal of the sixth switch tube, and an output terminal of the fourth switch tube is connected to a terminal of the second voltage-dividing capacitor far from the first voltage-dividing capacitor.

4. The midpoint active clamp three level inverter of claims 1-3, wherein the first diode, the second diode, the third diode, and the fourth diode comprise a first silicon diode, a second silicon diode, a third silicon diode, and a fourth silicon diode in a one-to-one correspondence.

5. The midpoint active clamp three-level inverter of claims 1-3, wherein the first, second, third, fourth, fifth, and sixth switching transistors comprise a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, and a sixth MOS transistor, or a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, and a sixth transistor, in a one-to-one correspondence.

6. A method of controlling a midpoint active clamped three-level inverter, for use in the midpoint active clamped three-level inverter of any one of claims 1-5, the method comprising:

acquiring a first driving signal, a second driving signal, a third driving signal, a fourth driving signal, a fifth driving signal and a sixth driving signal corresponding to the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube;

and controlling the on-off states of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube based on a preset power switching mode according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal and the sixth driving signal to form a double-follow current loop so as to realize a current conversion path and electric energy conversion.

7. The method of controlling a midpoint active clamp three-level inverter of claim 6, wherein the predetermined power switching modes include a forward power switching mode and a reverse power switching mode.

8. The method of controlling a midpoint active clamped three level inverter of claim 7,

the forward power switching modalities include:

the first mode is as follows: controlling the first switch tube and the second switch tube to be switched on;

mode two: on the basis of the mode one, controlling the first switching tube, the second switching tube and the sixth switching tube to be switched on;

mode three: on the basis of the mode two, the first switching tube is controlled to be turned off, and the fifth diode, the second switching tube, the sixth switching tube and the third diode are controlled to be turned on;

and, modality four: and on the basis of the mode III, the sixth switching tube is controlled to be switched off, and the fifth diode and the second switching tube are controlled to be switched on.

9. The method as claimed in claim 8, wherein the step of controlling the on/off states of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube based on a preset power switching mode according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal to form a dual-freewheel loop to realize a commutation path and an electric energy conversion comprises:

switching the output level of the output end of the bridge arm from a first preset level to a second preset level on the basis of a mode one, a mode two and a mode three in sequence according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal;

and/or switching the output level of the output end of the bridge arm from a second preset level to a first preset level sequentially through the mode three, the mode four and the mode one according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal.

10. The method of controlling a midpoint active clamped three level inverter of claim 8, wherein said reverse power switching modes comprise:

a fifth mode: controlling the third switching tube and the fifth switching tube to be turned off, and controlling the first diode and the second diode to be turned on;

a sixth mode: on the basis of the mode five, controlling the fifth switching tube and the second diode to be switched on;

and, modality seven: and on the basis of the mode six, controlling the fifth switching tube, the second diode, the sixth diode and the third switching tube to be switched on.

11. The method as claimed in claim 10, wherein the step of controlling the on/off states of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube based on a preset power switching mode according to the first drive signal, the second drive signal, the third drive signal, the fourth drive signal, the fifth drive signal and the sixth drive signal to form a dual-freewheel loop to realize a commutation path and an electric energy conversion comprises:

switching the output level of the output end of the bridge arm from a first preset level to a second preset level on the basis of a mode five, a mode six and a mode seven in sequence according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal;

and/or switching the output level of the output end of the bridge arm from a second preset level to a first preset level sequentially through the mode seven, the mode six and the mode five according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal.

12. A control apparatus of a midpoint active clamp three-level inverter, for use in the midpoint active clamp three-level inverter of any one of claims 1-5, the apparatus comprising:

the acquisition unit is used for acquiring a first driving signal, a second driving signal, a third driving signal, a fourth driving signal, a fifth driving signal and a sixth driving signal corresponding to the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube;

and the control unit is used for controlling the on-off states of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube based on a preset power switching mode according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal and the sixth driving signal to form a double-follow current loop so as to realize a commutation path and electric energy conversion.

13. The apparatus of claim 12 wherein the predetermined power switching modes include a forward power switching mode and a reverse power switching mode.

14. The control apparatus for a midpoint active clamped three level inverter of claim 13,

the forward power switching modalities include:

the first mode is as follows: controlling the first switch tube and the second switch tube to be switched on;

mode two: on the basis of the mode one, controlling the first switching tube, the second switching tube and the sixth switching tube to be switched on;

mode three: on the basis of the mode two, the first switching tube is controlled to be turned off, and the fifth diode, the second switching tube, the sixth switching tube and the third diode are controlled to be turned on;

and, modality four: and on the basis of the mode III, the sixth switching tube is controlled to be switched off, and the fifth diode and the second switching tube are controlled to be switched on.

15. The apparatus for controlling a midpoint active clamped three level inverter of claim 14, wherein said control unit comprises:

the first switching module is used for switching the output level of the output end of the bridge arm from a first preset level to a second preset level on the basis of a mode one, a mode two and a mode three in sequence according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal;

and/or the second switching module is used for sequentially switching the output level of the output end of the bridge arm from the second preset level to the first preset level through the mode three, the mode four and the mode one according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal.

16. The apparatus for controlling a midpoint active clamped three level inverter of claim 14, wherein said reverse power switching modes comprise:

a fifth mode: controlling the third switching tube and the fifth switching tube to be turned off, and controlling the first diode and the second diode to be turned on;

a sixth mode: on the basis of the mode five, controlling the fifth switching tube and the second diode to be switched on;

and, modality seven: and on the basis of the mode six, controlling the fifth switching tube, the second diode, the sixth diode and the third switching tube to be switched on.

17. The apparatus for controlling a midpoint active clamped three level inverter of claim 16, wherein said control unit comprises:

the third switching module is used for switching the output level of the output end of the bridge arm from the first preset level to the second preset level on the basis of the mode five, the mode six and the mode seven in sequence according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal;

and/or the fourth switching module is configured to switch the output level of the bridge arm output end from the second preset level to the first preset level sequentially through the mode seven, the mode six and the mode five according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal.

Technical Field

The invention belongs to the technical field of inverters, and particularly relates to a midpoint active clamping three-level inverter, a control method and a control device.

Background

The inverter is an electric energy conversion device for converting direct current into alternating current, and in practical application, two-level and three-level topologies are more adopted, wherein the three-level topologies are divided into a T-type three-level topology, an I-type three-level topology, a midpoint active clamping three-level topology and the like. The existing expansion and control processing scheme of the inverter is as follows: t-type three-level is suitable for 1000V system due to the limitation of switch tube specification, and I-type three-level can select switch tubes with different specifications to respectively correspond to 1000V system and 1500V system. But the performance of an inner tube and a clamping diode in the I-type three-level middle tube is greatly limited, a clamping switch tube is added to the midpoint active clamping three-level middle tube, and the control is flexible. However, the clamp diode has large direct loss, and the heating of each switching tube is easy to be uneven. And each switch tube has low utilization ratio, so that each switch tube is influenced by the stress between the switch tubes, and the electric energy conversion efficiency of the circuit is low and the stability is poor.

Disclosure of Invention

The embodiment of the invention provides a midpoint active clamping three-level inverter, aiming at solving the problems of uneven heating of each switching tube, low electric energy conversion efficiency and poor stability in a circuit.

In a first aspect, an embodiment of the present invention provides a midpoint active clamped three-level inverter, including: the bridge arm comprises a bridge arm unit, a clamping unit connected with the bridge arm unit and a bridge arm output end connected with the bridge arm unit;

the bridge arm unit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which are sequentially connected in series, and a first diode, a second diode, a third diode and a fourth diode which are in inverse parallel connection with the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in a one-to-one correspondence manner;

the clamping unit comprises a fifth switching tube, a sixth switching tube, a fifth diode and a sixth diode, wherein the fifth switching tube and the sixth switching tube are sequentially connected in series, the fifth diode and the sixth diode are connected in anti-parallel with the fifth switching tube and the sixth switching tube in a one-to-one correspondence mode, one end, far away from the sixth switching tube, of the fifth switching tube is arranged on a connecting line between the first switching tube and the second switching tube, and one end, far away from the fifth switching tube, of the sixth switching tube is arranged on a connecting line between the third switching tube and the fourth switching tube;

the bridge arm output end is arranged on a connecting line between the second switching tube and the third switching tube;

the fifth switch tube or the fifth diode and the second switch tube or the second diode form a first freewheeling circuit, the sixth switch tube or the sixth diode and the third switch tube or the third diode form a second freewheeling circuit, and the first freewheeling circuit and the second freewheeling circuit form a dual freewheeling circuit for changing a freewheeling path;

the fifth diode and the sixth diode are silicon carbide diodes.

In a second aspect, an embodiment of the present invention further provides a control method of a midpoint active clamping three-level inverter, where the control method is used for the midpoint active clamping three-level inverter provided in the above embodiment, and the method includes:

acquiring a first driving signal, a second driving signal, a third driving signal, a fourth driving signal, a fifth driving signal and a sixth driving signal corresponding to the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube;

and controlling the on-off states of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube based on a preset power switching mode according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal and the sixth driving signal to form a double-follow current loop so as to realize a current conversion path and electric energy conversion.

In a third aspect, an embodiment of the present invention further provides a control apparatus for a midpoint active clamping three-level inverter, where the control apparatus is used for the midpoint active clamping three-level inverter provided in the foregoing embodiment, and the apparatus includes:

the acquisition unit is used for acquiring a first driving signal, a second driving signal, a third driving signal, a fourth driving signal, a fifth driving signal and a sixth driving signal corresponding to the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube;

and the control unit is used for controlling the on-off states of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube based on a preset power switching mode according to the first driving signal, the second driving signal, the third driving signal, the fourth driving signal and the sixth driving signal to form a double-follow current loop so as to realize a commutation path and electric energy conversion.

The silicon carbide diode has the advantages that the fifth diode and the sixth diode are silicon carbide diodes, so that the switching-on loss of the first switching tube and the fourth switching tube is reduced, the conduction of the fifth switching tube and the sixth switching tube is controlled, the direct-connection loss of the fifth diode and the sixth diode can be reduced, and the switching tubes can uniformly heat. And only the fifth diode and the sixth diode are silicon carbide diodes, so that the requirements of the silicon carbide diodes are reduced, and the material cost can be reduced. And a follow current path is changed by adopting a double follow current loop, so that the thermal stress among the switch tubes is dispersed. The sixth switching tube or the fifth switching tube corresponding to the half cycle is closed before the first switching tube and/or the fourth switching tube is switched on, so that the defect that the first switching tube and the fourth switching tube additionally generate switching loss due to the fact that the second diode and the third diode which are reversely connected in parallel are silicon diodes is avoided. The voltage stress of the corresponding switch tube is reduced, the forward through loss of the fifth diode and the sixth diode is reduced, the electric energy conversion efficiency of the circuit is improved, and the stability of the inverter in reliable operation is improved.

Drawings

Fig. 1 is a circuit diagram of a midpoint active clamp three-level inverter according to an embodiment of the present invention;

fig. 2 is a flowchart of a control method of a midpoint active clamped three-level inverter according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a positive and negative half cycle wave generation according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a modality provided by modality one in the embodiment of the present invention;

FIG. 5 is a schematic diagram of one mode provided by mode two in an embodiment of the present invention;

FIG. 6 is a schematic diagram of a mode provided by mode three in an embodiment of the present invention;

FIG. 7 is a schematic diagram of a mode provided by mode four in an embodiment of the invention;

FIG. 8 is a flowchart of a method provided by step 102 in an embodiment of the present invention;

FIG. 9 is a schematic illustration of a modality provided by modality five in an embodiment of the invention;

FIG. 10 is a schematic illustration of a mode provided by mode six in an embodiment of the invention;

FIG. 11 is a schematic diagram of a mode provided by mode seven in an embodiment of the invention;

FIG. 12 is a flow chart of another method provided by step 102 in an embodiment of the present invention;

fig. 13 is a schematic structural diagram of a control device of a midpoint active clamped three-level inverter according to an embodiment of the present invention;

FIG. 14 is a schematic diagram of a structure provided by the control unit in the embodiment of the present invention;

fig. 15 is another schematic structural diagram provided by the control unit in the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

According to the invention, the advantages that the fifth diode and the sixth diode are silicon carbide diodes are adopted, the turn-on loss of the first switching tube and the fourth switching tube is reduced, the turn-on loss of the fifth diode and the sixth diode can be reduced by controlling the turn-on of the fifth switching tube and the sixth switching tube, and the switching tubes can uniformly heat. And only the fifth diode and the sixth diode are silicon carbide diodes, so that the requirements of the silicon carbide diodes are reduced, and the material cost can be reduced. And a follow current path is changed by adopting a double follow current loop, so that the thermal stress among the switch tubes is dispersed. The sixth switching tube or the fifth switching tube corresponding to the half cycle is closed before the first switching tube and/or the fourth switching tube is switched on, so that the defect that the first switching tube and the fourth switching tube additionally generate switching loss due to the fact that the second diode and the third diode which are reversely connected in parallel are silicon diodes is avoided. The voltage stress of the corresponding switch tube is reduced, the forward through loss of the fifth diode and the sixth diode is reduced, the electric energy conversion efficiency of the circuit is improved, and the stability of the inverter in reliable operation is improved.