阅读说明：本技术 逆变器控制装置、逆变设备及控制方法 (Inverter control device, inverter equipment and control method ) 是由 林镇煌 洪培在 胡斌 于 2021-07-08 设计创作，主要内容包括：本发明适用于逆变器技术领域,提供了逆变器控制装置、逆变设备及控制方法,其中,逆变器控制装置包括变压器模块、整流桥模块和控制模块；变压器模块受控于控制模块；变压器模块连接在电网与整流桥模块之间,用于向整流桥模块供电；整流桥模块,与有源飞跨电容型逆变器的直流母线和有源飞跨电容型逆变器的第一飞跨电容连接；控制模块用于在有源飞跨电容型逆变器启动时,控制变压器模块工作,并在检测到第一飞跨电容两端的电压不小于第一电压时,控制有源飞跨电容型逆变器的第一逆变桥开始工作。本发明可以实现有源飞跨电容型逆变器的缓启动,降低选型成本。(The invention is suitable for the technical field of inverters and provides an inverter control device, an inverter device and a control method, wherein the inverter control device comprises a transformer module, a rectifier bridge module and a control module; the transformer module is controlled by the control module; the transformer module is connected between the power grid and the rectifier bridge module and used for supplying power to the rectifier bridge module; the rectifier bridge module is connected with a direct-current bus of the active flying capacitor type inverter and a first flying capacitor of the active flying capacitor type inverter; the control module is used for controlling the transformer module to work when the active flying capacitor type inverter is started, and controlling a first inverter bridge of the active flying capacitor type inverter to start working when the voltage at two ends of the first flying capacitor is not less than a first voltage. The invention can realize the slow start of the active flying capacitor type inverter and reduce the model selection cost.)

1. The inverter control device is used for controlling an active flying capacitor type inverter to work and comprises a transformer module, a rectifier bridge module and a control module; the transformer module is controlled by the control module;

the transformer module is connected between a power grid and the rectifier bridge module and used for receiving power supplied by the power grid and supplying power to the rectifier bridge module when the active flying capacitor type inverter is started;

in the rectifier bridge module, a bus power supply end is used for being connected with a direct-current bus of the active flying capacitor type inverter, the bus power supply end is used for supplying power to the direct-current bus, a first power supply end is used for being connected with a first flying capacitor of the active flying capacitor type inverter, and the first power supply end is used for supplying power to the first flying capacitor; the control module is used for controlling the transformer module to work when the active flying capacitor type inverter is started, and controlling a first inverter bridge of the active flying capacitor type inverter to start working when the voltage at two ends of the first flying capacitor is not less than a first voltage;

after the transformer module works, the rectifier bridge module provides a second voltage to the direct-current bus through the bus power supply end, and provides the first voltage to the first flying capacitor through the first power supply end.

2. The inverter control device of claim 1, wherein the rectifier bridge module comprises a supply rectifier bridge and a first rectifier bridge;

the input end of the power supply rectifier bridge is connected with the bus output winding of the transformer module, and the output end of the power supply rectifier bridge is connected with the bus power supply end of the rectifier bridge module;

the input end of the first rectifier bridge is connected with the first output winding of the transformer module, and the output end of the first rectifier bridge is connected with the first power supply end of the rectifier bridge module.

3. The inverter control apparatus according to claim 1,

the transformer module comprises a slow-start switch unit and a transformer;

the first end of the slow-start switch unit is connected with the first input end of the transformer module, the second end of the slow-start switch unit is connected with the first end of the input winding of the transformer, and the slow-start switch unit is controlled by the control module;

the second end of the input winding of the transformer is connected with the second input end of the transformer module, the first output winding is connected with the bus output winding of the transformer module, and the second output winding is connected with the single-phase output winding of the transformer module;

the first input end of the transformer module and the second input end of the transformer module are used for getting power from phase voltage or line voltage of the power grid;

the control module is further used for controlling the slow start switch unit to be switched from a disconnection state to a conduction state when the active flying capacitor type inverter is started.

4. The inverter control apparatus according to claim 1, comprising:

a second power supply end of the rectifier bridge module is used for being connected with a second flying capacitor of the active flying capacitor type inverter, the second power supply end is used for supplying power to the second flying capacitor, a third power supply end is used for being connected with a third flying capacitor of the active flying capacitor type inverter, and the third power supply end is used for supplying power to the third flying capacitor;

the control module is further configured to control the second inverter bridge of the active flying capacitor type inverter and the third inverter bridge of the active flying capacitor type inverter to start working when it is detected that the voltages at the two ends of the second flying capacitor and the two ends of the third flying capacitor are not less than the first voltage;

after the transformer module works, the rectifier bridge module provides the first voltage to the second flying capacitor through the second power supply terminal, and provides the first voltage to the third flying capacitor through the third power supply terminal.

5. The inverter control device according to claim 4, wherein the inverter control device

The rectifier bridge module comprises a power supply rectifier bridge, a first rectifier bridge, a second rectifier bridge and a third rectifier bridge;

the input end of the power supply rectifier bridge is connected with the bus output winding of the transformer module, and the output end of the power supply rectifier bridge is connected with the bus power supply end of the rectifier bridge module;

the input end of the first rectifier bridge is connected with the first output winding of the transformer module, and the output end of the first rectifier bridge is connected with the first power supply end of the rectifier bridge module;

the input end of the second rectifier bridge is connected with the second output winding of the transformer module, and the output end of the second rectifier bridge is connected with the second power supply end of the rectifier bridge module;

and the input end of the third rectifier bridge is connected with the third output winding of the transformer module, and the output end of the third rectifier bridge is connected with the third power supply end of the rectifier bridge module.

6. The inverter control apparatus of claim 4, wherein the transformer module comprises a soft start switching unit and a transformer;

the first end of the slow-start switch unit is connected with the first input end of the transformer module, the second end of the slow-start switch unit is connected with the first end of the input winding of the transformer, and the slow-start switch unit is controlled by the control module;

the second end of the input winding of the transformer is connected with the second input end of the transformer module, the first output winding is connected with the bus output winding of the transformer module, the second output winding is connected with the first output winding of the transformer module, the third output winding is connected with the second output winding of the transformer module, and the fourth output winding is connected with the third output winding of the transformer module;

the first input end of the transformer module and the second input end of the transformer module are used for getting power from phase voltage or line voltage of the power grid;

the control module is further used for controlling the slow start switch unit to be switched from a disconnection state to a conduction state when the active flying capacitor type inverter is started.

7. The inverter control device according to claim 3 or 6, wherein the soft start switching unit includes a first branch and a second branch; the first branch and the second branch are controlled by the control module;

the first branch comprises a current limiter and a first switch which are sequentially connected, the first end of the first branch is respectively connected with the first end of the second branch and the first end of the slow start switch unit, and the second end of the first branch is respectively connected with the second end of the second branch and the second end of the slow start switch unit;

the second branch comprises a second switch;

the control module is further configured to control the first branch circuit to switch from an off state to an on state when the active flying capacitor-type inverter is started, and,

and after the inverter bridge of the active flying capacitor type inverter starts to work, controlling the second branch circuit to be switched from the off state to the on state, and controlling the first branch circuit to be switched from the on state to the off state.

8. An inverter device comprising the inverter control apparatus according to any one of claims 1 to 7, the inverter device further comprising a first output terminal and an active flying capacitor-type inverter; the active flying capacitor type inverter comprises a direct current bus, a first inverter bridge and a first flying capacitor; the first output end is used for outputting first phase electricity;

the first end of the direct current bus is connected with the input anode of the first inverter bridge, the second end of the direct current bus is connected with the input cathode of the first inverter bridge, the midpoint of the direct current bus is connected with the midpoint of an input bridge arm of the first inverter bridge, and the midpoint of the direct current bus is used for providing zero potential; the first inverter bridge is controlled by a control module through a controlled end;

the first flying capacitor is connected to two ends of an output bridge arm of the first inverter bridge; the output end of the first inverter bridge is respectively connected with the first output end and the midpoint of the output bridge arm of the first inverter bridge.

9. The inverter device of claim 8, wherein the inverter device further comprises a second output terminal and a third output terminal; the active flying capacitor type inverter further comprises a second inverter bridge, a third inverter bridge, a second flying capacitor and a third flying capacitor; wherein the second output is configured to output second phase electricity; the third output end is used for outputting third phase power;

the first end of the direct current bus is also respectively connected with the input anode of the second inverter bridge and the input anode of the third inverter bridge, the second end of the direct current bus is also respectively connected with the input cathode of the second inverter bridge and the input cathode of the third inverter bridge, the middle point of the direct current bus is also respectively connected with the middle point of the input bridge arm of the second inverter bridge and the middle point of the input bridge arm of the third inverter bridge, and the middle point of the direct current bus is used for providing zero potential; the first inverter bridge, the second inverter bridge and the third inverter bridge are controlled by a control module through controlled ends;

the first flying capacitor is connected to two ends of an output bridge arm of the first inverter bridge; the output end of the first inverter bridge is respectively connected with the first output end and the midpoint of an output bridge arm of the first inverter bridge;

the second flying capacitor is connected to two ends of an output bridge arm of the second inverter bridge; the output end of the second inverter bridge is respectively connected with the second output end and the midpoint of an output bridge arm of the second inverter bridge;

the third flying capacitor is connected to two ends of an output bridge arm of the third inverter bridge; and the output end of the third inverter bridge is respectively connected with the third output end and the midpoint of the output bridge arm of the third inverter bridge.

10. A control method applied to a control module in the inverter control apparatus according to any one of claims 1 to 7 and a control module in the inverter device according to claim 8 or 9, the control method comprising:

at the start of the active flying capacitor type inverter:

if the voltage at two ends of a first flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, controlling the transformer module to be switched from a disconnection state to a conduction state;

and when the voltage at two ends of the first flying capacitor is not less than the first voltage, controlling an inverter bridge of the active flying capacitor type inverter to start working.

Technical Field

The invention belongs to the technical field of inverters, and particularly relates to an inverter control device, inverter equipment and a control method.

Background

The active inverter may convert the dc power to 50Hz or 60Hz ac power and feed into the utility grid. For an active flying capacitor type inverter, generally, alternating current can be taken from a public power grid, and direct current is output through rectification, and the direct current can be used as a direct current power supply of the active flying capacitor type inverter.

However, when the active flying capacitor type inverter starts to work, part of switching devices of the inverter bridge can bear the whole voltage of the power supply, so that the problems of difficult type selection and high cost exist when the part of switching devices are selected.

Disclosure of Invention

In view of this, embodiments of the present invention provide an inverter control device, an inverter device, and a control method, so as to solve the problems in the prior art that when an active flying capacitor type inverter is started to operate, part of switching devices of an inverter bridge may bear all voltages of a power supply, so that when the part of switching devices is selected, the selection of the switching devices is difficult and the cost is high.

The first aspect of the embodiments of the present invention provides an inverter control device, configured to control an active flying capacitor-type inverter to operate, where the inverter control device includes a transformer module, a rectifier bridge module, and a control module; the transformer module is controlled by the control module;

the transformer module is connected between a power grid and the rectifier bridge module and used for receiving power supplied by the power grid and supplying power to the rectifier bridge module when the active flying capacitor type inverter is started;

the rectifier bridge module is used for connecting a bus power supply end with a direct-current bus of the active flying capacitor type inverter, the bus power supply end is used for supplying power to the direct-current bus, a first power supply end is used for being connected with a first flying capacitor of the active flying capacitor type inverter, and the first power supply end is used for supplying power to the first flying capacitor; the control module is used for controlling the transformer module to work when the active flying capacitor type inverter is started, and controlling a first inverter bridge of the active flying capacitor type inverter to start working when the voltage at two ends of a first flying capacitor is detected to be not less than a first voltage;

after the transformer module works, the rectifier bridge module provides a second voltage to the direct-current bus through the bus power supply end, and provides a first voltage to the first flying capacitor through the first power supply end.

A second aspect of embodiments of the present invention provides an inverter apparatus, including the inverter control device according to the first aspect, the inverter apparatus further including a first output terminal and an active flying capacitor-type inverter; the active flying capacitor type inverter comprises a direct current bus, a first inverter bridge and a first flying capacitor; the first output end is used for outputting first phase electricity;

the first end of the direct current bus is connected with the input anode of the first inverter bridge, the second end of the direct current bus is connected with the input cathode of the first inverter bridge, the midpoint of the direct current bus is connected with the midpoint of an input bridge arm of the first inverter bridge, and the midpoint of the direct current bus is used for providing zero potential; the first inverter bridge is controlled by the control module through the controlled end;

the first flying capacitor is connected to two ends of an output bridge arm of the first inverter bridge; the output end of the first inverter bridge is respectively connected with the first output end and the midpoint of the output bridge arm of the first inverter bridge.

A third aspect of embodiments of the present invention provides a control method applied to a control module in the inverter control apparatus according to the first aspect above and a control module in the inverter device according to the second aspect above, the control method including:

at the start of the active flying capacitor type inverter:

if the voltage at two ends of a first flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, controlling the transformer module to be switched from a disconnection state to a conduction state;

and when the voltage at two ends of the first flying capacitor is not less than the first voltage, controlling an inverter bridge of the active flying capacitor type inverter to start working.

Compared with the prior art, the embodiment of the invention has the following beneficial effects:

the inverter control device comprises a transformer module, a rectifier bridge module and a control module; the transformer module is controlled by the control module; the transformer module is connected between the power grid and the rectifier bridge module and used for supplying power to the rectifier bridge module; the rectifier bridge module is connected with a direct-current bus of the active flying capacitor type inverter and a first flying capacitor of the active flying capacitor type inverter; the control module is used for controlling the transformer module to work when the active flying capacitor type inverter is started, and controlling a first inverter bridge of the active flying capacitor type inverter to start working when the voltage at two ends of the first flying capacitor is not less than a first voltage. The control module can control the transformer module to work, start charging to the first flying capacitor, and after the first flying capacitor is charged, control the inverter bridge of the active flying capacitor type inverter to work, so as to realize the slow start of the active flying capacitor type inverter.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

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

fig. 2 is a schematic structural diagram of another inverter control device provided in the embodiment of the present invention;

fig. 3 is a schematic circuit diagram of an inverter control device according to an embodiment of the present invention;

fig. 4 is a schematic circuit structure diagram of an inverter device according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

Referring to fig. 1, which shows a schematic structural diagram of an inverter control device according to an embodiment of the present invention, as shown in fig. 1, an inverter control device 10 is used for controlling an active flying capacitor type inverter 20 to operate, and includes a transformer module 101, a rectifier bridge module 102, and a control module 103; the transformer module 101 is controlled by the control module 103;

the transformer module 101 is connected between the power grid and the rectifier bridge module 102, and is used for receiving power supplied by the power grid and supplying power to the rectifier bridge module 102 when the active flying capacitor type inverter 20 is started;

a rectifier bridge module 102, a bus power supply end is used for connecting with a direct current bus 201 of the active flying capacitor type inverter 20, the bus power supply end is used for supplying power to the direct current bus 201, a first power supply end is used for connecting with a first flying capacitor 202 of the active flying capacitor type inverter 20, and the first power supply end is used for supplying power to the first flying capacitor 202; the control module 103 is configured to control the transformer module 101 to operate when the active flying capacitor type inverter 20 is started, and control the first inverter bridge 203 of the active flying capacitor type inverter 20 to start operating when it is detected that the voltage across the first flying capacitor 202 is not less than the first voltage;

after the transformer module 101 is operated, the rectifier bridge module 103 provides the second voltage to the dc bus 201 through the bus power supply terminal, and provides the first voltage to the first flying capacitor 202 through the first power supply terminal.

Optionally, the control module 103 may be a micro control unit (mcu). The transformer module 101 and the rectifier bridge module 102 may also be replaced by dc power supply modules. The dc power supply module has multiple output ports, and can provide various voltages to enable the active flying capacitor inverter 20 to start and operate normally.

Optionally, the first voltage is generally lower than the second voltage, and the first voltage may be half of the second voltage. The first voltage and the second voltage may be set according to practice.

The embodiment of the invention is suitable for normally starting a Voltage Sag Generator (VSG) or a Static Var Generator (SVG) under the condition of lack of direct current input when the VSG or the SVG works at night, so that the VSG or the SVG works normally.

Specifically, at night, when lacking photovoltaic DC power supply, can get the electricity from the electric wire netting through transformer module 101 to provide DC power supply to VSG or SVG through rectifier bridge module 102, make VSG or SVG normally start work. In daytime, the flying capacitor in the VSG or the SVG can be charged through the transformer module 101 and the rectifier bridge module, and when the flying capacitor is charged to half bus voltage, the flying capacitor is started to work. The VSG or the SVG can work normally all day long, and the reliability is high.

The inverter control device comprises a transformer module, a rectifier bridge module and a control module; the transformer module is controlled by the control module; the transformer module is connected between the power grid and the rectifier bridge module and used for supplying power to the rectifier bridge module; the rectifier bridge module is connected with a direct-current bus of the active flying capacitor type inverter and a first flying capacitor of the active flying capacitor type inverter; the control module is used for controlling the transformer module to work when the active flying capacitor type inverter is started, and controlling a first inverter bridge of the active flying capacitor type inverter to start working when the voltage at two ends of the first flying capacitor is not less than a first voltage. The control module can control the transformer module to work, start charging to the first flying capacitor, and after the first flying capacitor is charged, control the inverter bridge of the active flying capacitor type inverter to work, so as to realize the slow start of the active flying capacitor type inverter.

Referring to fig. 2, fig. 2 is a schematic structural diagram of another inverter control device according to an embodiment of the present invention. As shown in fig. 2, in some embodiments of the present invention, the rectifier bridge module 102 includes a supply rectifier bridge 1021 and a first rectifier bridge 1022;

the input end of the power supply rectifier bridge 1021 is connected with the bus output winding of the transformer module 101, and the output end of the power supply rectifier bridge 1021 is connected with the bus power supply end of the rectifier bridge module 102;

the input end of the first rectifier bridge 1022 is connected to the first output winding of the transformer module 101, and the output end thereof is connected to the first power supply end of the rectifier bridge module 102.

Optionally, different voltages can be output for supplying power by designing the turn ratio of the output secondary side of the transformer module 101, for example, the secondary side ratio of the transformer module 101 is 2:1, that is, assuming that the transformer module 101 provides two paths of power for the rectifier bridge module 102, if the second voltage output by the bus power supply end is 400V, the voltage output by the first power supply end is 200V. The output secondary side turn ratio of the transformer module 101 can be designed according to actual needs, and the requirements of outputting different voltage values are met.

Referring to fig. 2, in some embodiments of the invention, the transformer module 101 includes a soft-start switching unit 1011 and a transformer 1012;

a slow-start switch unit 1011, a first end of which is connected to a first input end of the transformer module 1012, and a second end of which is connected to a first end of an input winding of the transformer 1012, and is controlled by the control module 103;

a transformer 1012, a second end of the input winding is connected with a second input end of the transformer module 101, a first output winding is connected with a bus output winding of the transformer module 101, and a second output winding is connected with a single-phase output winding of the transformer module 101;

the first input end of the transformer module 101 and the second input end of the transformer module 101 are used for getting power from phase voltage or line voltage of a power grid;

the control module 103 is further configured to control the soft start switch unit 1011 to switch from the off state to the on state when the active flying capacitor type inverter 20 is started.

Optionally, the control module 103 controls the state (on state or off state) of the slow-start switch unit 1011 to further control whether the transformer module 101 supplies power to the rectifier bridge module 102.

For example, refer to fig. 3, which shows a schematic circuit structure diagram of the inverter control device provided by the embodiment of the invention in fig. 3. As shown in fig. 3, the transformer module 101 may include a slow-start switch unit controlled by the control module 103 and a three-winding transformer, and the slow-start switch unit has a single input and a double output. The bridge rectifier module 102 may include a power supply bridge rectifier for supplying U +/U-to both ends of the dc bus 201, and a first bridge rectifier for supplying UA +/UA-to both ends of the first flying capacitor 202. The first inverter bridge 203 may include switching transistors Q1-Q8, which are all controlled by the control module 103.

In some embodiments of the present invention, the rectifier bridge module 102 has a second power supply terminal for connecting with the second flying capacitor 204 of the active flying capacitor type inverter 20, a second power supply terminal for supplying power to the second flying capacitor 204, a third power supply terminal for connecting with the third flying capacitor 206 of the active flying capacitor type inverter 20, and a third power supply terminal for supplying power to the third flying capacitor 206;

the control module 103 is further configured to control the second inverter bridge 205 of the active flying capacitor inverter 20 and the third inverter bridge 207 of the active flying capacitor inverter to start working when it is detected that the voltages at the two ends of the second flying capacitor 204 and the two ends of the third flying capacitor 206 are not less than the first voltage;

after the transformer module 101 operates, the rectifier bridge module 102 provides the first voltage to the second flying capacitor 204 through the second power supply terminal, and provides the first voltage to the third flying capacitor 207 through the third power supply terminal.

Referring to fig. 2, in some embodiments of the present invention, the rectifier bridge module 102 includes a supply rectifier bridge 1021, a first rectifier bridge 1022, a second rectifier bridge 1023, and a third rectifier bridge 1024;

the input end of the power supply rectifier bridge 1021 is connected with the bus output winding of the transformer module 101, and the output end of the power supply rectifier bridge 1021 is connected with the bus power supply end of the rectifier bridge module 102;

a first rectifier bridge 1022, an input end of which is connected to the first output winding of the transformer module 101, and an output end of which is connected to the first power supply end of the rectifier bridge module 102;

the input end of the second rectifier bridge 1023 is connected with the second output winding of the transformer module 101, and the output end of the second rectifier bridge 1023 is connected with the second power supply end of the rectifier bridge module 102;

and an input end of the third rectifier bridge 1024 is connected to the third output winding of the transformer module 101, and an output end of the third rectifier bridge is connected to a third power supply end of the rectifier bridge module 102.

Optionally, the bridge rectifier module 102 may further include a second rectifier bridge 1023 and a third rectifier bridge 1024. Wherein the second rectifier bridge 1025 is configured to supply power to the second flying capacitor 204 and the third rectifier bridge 1024 is configured to supply power to the third flying capacitor 206.

Optionally, different voltages can be output for supplying power by designing the turn ratio of the output secondary side of the transformer module 101, for example, the secondary side ratio of the transformer module 101 is 2:1:1:1, that is, assuming that the transformer module 101 provides four paths of power for the rectifier bridge module 102, if the second voltage output by the bus power supply end is 400V, the output voltages of the first power supply end, the second power supply end, and the third power supply end are all 200V. The output secondary side turn ratio of the transformer module 101 can be designed according to actual needs, and the requirements of outputting different voltage values are met.

Referring to fig. 2, in some embodiments of the invention, the transformer module 101 includes a soft-start switching unit 1011 and a transformer 1012;

a slow-start switch unit 1011, a first end of which is connected to the first input end of the transformer module 101, and a second end of which is connected to the first end of the input winding of the transformer 1012, and is controlled by the control module 103;

a transformer 1012, a second end of the input winding is connected with a second input end of the transformer module 101, the first output winding is connected with a bus output winding of the transformer module 101, the second output winding is connected with the first output winding of the transformer module 101, the third output winding is connected with the second output winding of the transformer module 101, and the fourth output winding is connected with the third output winding of the transformer module 101;

the first input end of the transformer module 101 and the second input end of the transformer module 101 are used for getting power from phase voltage or line voltage of a power grid;

the control module 103 is further configured to control the soft start switch unit 1011 to switch from the off state to the on state when the active flying capacitor type inverter 20 is started.

Illustratively, in the embodiment of the present invention, the flying capacitor of the active flying capacitor type inverter is precharged, so that the active flying capacitor type inverter 20 can be started slowly, and the specific process is as follows:

when the active flying capacitor type inverter 20 needs to be started, the control module 103 controls the transformer module 101 to work, and at this time, four power supply lines exist for the active flying capacitor type inverter 20 to be started and charged slowly, which are respectively:

power supply line 1: the power grid-transformer module 101-a power supply rectifier bridge 1021-a direct current bus 201;

power supply line 2: grid-transformer module 101-first rectifier bridge 1022-first flying capacitor 202;

power supply line 3: grid-transformer module 101-second rectifier bridge 1023-second flying capacitor 204;

power supply line 4: grid-transformer module 101-third rectifier bridge 1024-third flying capacitor 206;

the control module 103 detects voltage values at two ends of each flying capacitor in real time, when it is detected that the voltage value at two ends of the first flying capacitor 202, the voltage value at two ends of the second flying capacitor 204 and the voltage value at two ends of the third flying capacitor 206 are not less than the second voltage, that is, when the voltage value is detected, it represents that the active flying capacitor type inverter 20 is started up slowly, the control module 103 controls inverter bridges (such as the first inverter bridge 203, the second inverter bridge 205 and the third inverter bridge 207) of the active flying capacitor type inverter 20 to start working, and each inverter bridge is respectively powered by the dc bus 201 and outputs each phase voltage correspondingly. In this case, the active flying capacitor inverter 20 has three output lines, which are:

output line 1: a direct current bus 201-a first inverter bridge 202-a first phase current A;

output line 2: the direct current bus 201, the second inverter bridge 203 and the second phase B;

output line 3: the direct current bus 201, the third inverter bridge 204 and the third phase C.

As can be seen from the above description, when the active flying capacitor inverter 20 needs to be started, each flying capacitor is precharged first, and when the voltage across each flying capacitor satisfies a certain condition, the active flying capacitor inverter 20 is started again, and the voltage borne by each flying capacitor during the starting of the switching tube of each inverter bridge in the active flying capacitor inverter 20 can be effectively reduced through the precharging. By the aid of the slow start design, working reliability of the active flying capacitor type inverter 20 is guaranteed, meanwhile, withstand voltage conditions of the switching tube devices are reduced, the problem that the switching tube devices are difficult to select is solved, and cost is reduced.

In some embodiments of the present invention, the soft start switch unit 1011 includes a first branch and a second branch; the first branch and the second branch are controlled by the control module;

the first branch comprises a current limiter and a first switch which are sequentially connected, the first end of the first branch is respectively connected with the first end of the second branch and the first end of the slow start switch unit, and the second end of the first branch is respectively connected with the second end of the second branch and the second end of the slow start switch unit;

the second branch comprises a second switch;

the control module is further configured to control the first branch to switch from the off state to the on state when the active flying capacitor-type inverter is started, and,

after an inverter bridge of the active flying capacitor type inverter starts to work, the second branch circuit is controlled to be switched from the off state to the on state, and the first branch circuit is controlled to be switched from the on state to the off state.

Optionally, the first switch and the second switch may be both electrically controlled switches, such as relays.

When the active flying capacitor type inverter is started, the slow starting switch unit 1011 is switched to a conducting state from a disconnecting state, and the power grid power supply can generate impact on the slow starting switch unit 1011, so that a first branch and a second branch are arranged, when the power grid power supply is needed, the slow starting of the slow starting switch unit is realized by controlling the conduction of the first branch, and the first branch is provided with a current limiter, so that the current impact can be effectively avoided. After an inverter bridge of the active flying capacitor type inverter starts to work, the second branch circuit needs to be controlled to be closed and the first branch circuit needs to be opened at the moment because the current limiter can damage a line. Through setting up first branch road and second branch road, can reduce the loss of whole circuit under the circumstances of guaranteeing relay control circuit normal operation.

Optionally, the slow-start switch unit 1101 may further include only a third switch, and the third switch needs to meet a requirement of being able to withstand the grid impact.

Referring to fig. 4, a schematic circuit diagram of an inverter device according to an embodiment of the present invention is shown. As shown in fig. 4, an inverter device includes the inverter control apparatus 10 provided in the above embodiment, and further includes a first output terminal and an active flying capacitor-type inverter 20; the active flying capacitor type inverter comprises a direct current bus 201, a first inverter bridge 203 and a first flying capacitor 202; the first output end is used for outputting a first phase current A;

a first end of the direct current bus 201 is connected with an input anode UA + of the first inverter bridge 203, a second end of the direct current bus 201 is connected with an input cathode UA-of the first inverter bridge 203, a midpoint of the direct current bus 201 is connected with a midpoint of an input bridge arm of the first inverter bridge, and the midpoint of the direct current bus 201 is used for providing zero potential; wherein, the first inverter bridge 203 is controlled by the control module 103 through a controlled end;

the first flying capacitor 202 is connected to two ends of an output bridge arm of the first inverter bridge 203; the output end of the first inverter bridge 203 is connected to the first output end and the midpoint of the output bridge arm of the first inverter bridge 203.

In some embodiments of the present invention, the inverter device further includes a second output terminal and a third output terminal; the active flying capacitor-type inverter 20 further includes a second inverter bridge 205, a third inverter bridge 207, a second flying capacitor 204, and a third flying capacitor 206; the second output end is used for outputting second phase electricity B; the third output end is used for outputting third phase power C;

a first end of the direct current bus 201 is also respectively connected with an input anode UB + of the second inverter bridge 205 and an input anode UC + of the third inverter bridge 207, a second end of the direct current bus is also respectively connected with an input cathode UB-of the second inverter bridge 205 and an input cathode UC-of the third inverter bridge 207, a midpoint of the direct current bus 207 is also respectively connected with a midpoint of an input bridge arm of the second inverter bridge 205 and a midpoint of an input bridge arm of the third inverter bridge 207, and the midpoint of the direct current bus 207 is used for providing a zero potential; the first inverter bridge 203, the second inverter bridge 205 and the third inverter bridge 207 are controlled by the control module 103 through controlled ends;

the first flying capacitor 202 is connected to two ends of an output bridge arm of the first inverter bridge 203; the output end of the first inverter bridge 203 is connected with the first output end and the midpoint of the output bridge arm of the first inverter bridge 203 respectively;

the second flying capacitor 204 is connected to two ends of an output bridge arm of the second inverter bridge 204; the output end of the second inverter bridge 204 is connected with the second output end and the midpoint of the output bridge arm of the second inverter bridge 204;

the third flying capacitor 206 is connected to both ends of an output bridge arm of the third inverter bridge 206; the output end of the third inverter bridge 206 is connected to the third output end and the midpoint of the output bridge arm of the third inverter bridge 206, respectively.

Optionally, the first branch may include a current limiter R1 and a first switch K1, the second branch may include a second switch K2, a power supply rectifier bridge 1021, and an output positive electrode U + and an output negative electrode U-are respectively connected to two ends of the dc bus 201 and supply power to the dc bus 201; the output positive electrode UA + and the output negative electrode UA-of the first rectifier bridge 1022 are connected to two ends of the first flying capacitor 202, respectively, and supply power to the first flying capacitor 202; a second rectifier bridge 1023, an output positive electrode UB + and an output negative electrode UB-are respectively connected with two ends of the second flying capacitor 1204 and supply power to the second flying capacitor 1024; and the output positive pole UC + and the output negative pole UC-of the third rectifier bridge 1024 are respectively connected to two ends of the third flying capacitor 206, and supply power to the third flying capacitor 206.

For example, when the inverter device needs to be started, the control module 103 controls the transformer module 101 to be switched from the off state to the on state, the power supply rectifier bridge 1021 phase dc bus 201 supplies power, the first rectifier bridge 1022 phase first flying capacitor 202 charges, the second rectifier bridge 1023 phase second flying capacitor 204 charges, the third rectifier bridge 1024 phase third flying capacitor 206 charges, after the voltages at the two ends of the first flying capacitor 202, the second flying capacitor 204, and the third flying capacitor 206 all reach the second voltage value, the control module 103 controls the first inverter bridge 203, the second inverter bridge 205, and the third inverter bridge 207 to start to operate (i.e., start the normal operation logic), and the voltage of the dc bus 201 outputs three-phase voltages through the respective inverter bridges.

Specifically, the active flying capacitor inverter 20 may be a flying capacitor five-level inverter, a flying capacitor three-level inverter, or other multi-level flying capacitor inverters.

Referring to fig. 4, in some embodiments of the present invention, the dc bus 201 includes a first support capacitor C1 and a second support capacitor C2 connected in series; the connection end of the first supporting capacitor C1 and the second supporting capacitor C2 is the midpoint of the direct current bus.

Optionally, the first supporting capacitor C1 and the second supporting capacitor C2 are used for storing energy and also for supplying power to each inverter bridge.

Referring to fig. 4, in some embodiments of the present invention, the first inverter bridge 203 includes a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7, and an eighth switching tube Q8:

a first switch tube Q1, a first end of which is connected to the input anode of the first inverter bridge 203, a second end of which is connected to the first end of the second switch tube Q2 and the first end of the third switch tube Q3, respectively, and a control end of which is connected to the controlled end of the first inverter bridge 203;

a first end of a fourth switching tube Q4 is connected to the second end of the third switching tube Q3 and the first end of the output bridge arm of the first inverter bridge 203, a second end of the fourth switching tube Q4 is connected to the first end of the eighth switching tube Q8 and the output end of the first inverter bridge 203, and a control end of the fourth switching tube Q4 is connected to the controlled end of the first inverter bridge 203;

a fifth switching tube Q5, a first end of which is connected to the second end of the second switching tube Q2 and the midpoint of the input bridge arm of the first inverter bridge 203, a second end of which is connected to the first end of the sixth switching tube Q6 and the second end of the seventh switching tube Q7, respectively, and a control end of which is connected to the controlled end of the first inverter bridge 203;

a second end of the eighth switching tube Q8 is connected to the first end of the seventh switching tube Q7 and the second end of the output bridge arm of the first inverter bridge 203, respectively, and a control end is connected to the controlled end of the first inverter bridge 203;

a second end of the sixth switching tube Q6 is connected with the input cathode of the first inverter bridge 203, and a control end is connected with the controlled end of the first inverter bridge 203;

the control end of the second switching tube Q2, the control end of the third switching tube Q3 and the control end of the seventh switching tube Q7 are all connected with the controlled end of the first inverter bridge 203;

the second inverter bridge 205 and the third inverter bridge 207 are both structurally identical to the first inverter bridge 203.

Optionally, in the first inverter bridge 203, a connection point between the second end of the second switching tube Q2 and the first end of the fifth switching tube Q5 is an input bridge arm midpoint of the first inverter bridge 203, and a connection point between the second end of the fourth switching tube Q4 and the first end of the eighth switching tube Q8 is an output bridge arm midpoint of the first inverter bridge 203;

in the second inverter bridge 205, a connection point between the second end of the second switching tube Q2 and the first end of the fifth switching tube Q5 is an input bridge arm midpoint of the second inverter bridge 205, and a connection point between the second end of the fourth switching tube Q4 and the first end of the eighth switching tube Q8 is an output bridge arm midpoint of the second inverter bridge 205;

in the third inverter bridge 207, a connection point between the second end of the second switching tube Q2 and the first end of the fifth switching tube Q5 is an input bridge arm midpoint of the third inverter bridge 207, and a connection point between the second end of the fourth switching tube Q4 and the first end of the eighth switching tube Q8 is an output bridge arm midpoint of the third inverter bridge 207.

Referring to fig. 4, in some embodiments of the present invention, the inverter device further includes a first filtering module 301, a second filtering module 302, and a third filtering module 303; wherein the content of the first and second substances,

a first filtering module 301, a first end of which is connected to the output end of the first inverter bridge 203, a second end of which is connected to the first phase output end a of the inverter device, and a common end of which is connected to the common end of the second filtering module 302 and the common end of the third filtering module 303, respectively, for filtering the output of the first inverter bridge 203;

a second filtering module 302, a first end of which is connected to the output end of the second inverter bridge 205, and a second end of which is connected to the second phase output end B of the inverter device, for filtering the output of the second inverter bridge 205;

a first end of the third filtering module 303 is connected to the output end of the third inverter bridge 207, and a second end of the third filtering module is connected to the third phase output end C of the inverter device, so as to filter the output of the third inverter bridge 207.

Referring to fig. 4, in some embodiments of the present invention, the first filtering module 301 may include a filtering inductor L1 and a filtering capacitor CL 1;

a first end of the filter inductor L1 is connected to the first end of the first filter module 301, and a second end of the filter inductor L1 is connected to the first end of the filter capacitor CL1 and the second end of the first filter module 301, respectively;

a second end of the filter capacitor CL1 is connected to the common end of the first filter module 301;

the second filtering module 302 and the third filtering module 303 are both the same in structure as the first filtering module 301.

In some embodiments of the present invention, the common terminal of the first filtering module 301, the common terminal of the second filtering module 302 and the common terminal of the third filtering module 303 may all be used for grounding.

The embodiment of the present invention further provides a control method, which is suitable for a control module in the inverter control device and a control module in the inverter device in the above embodiments, and the control method includes:

at the start of the active flying capacitor type inverter:

if the voltage at two ends of a first flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, controlling the transformer module to be switched from a disconnection state to a conduction state;

and when the voltage at two ends of the first flying capacitor is not less than the first voltage, controlling an inverter bridge of the active flying capacitor type inverter to start working.

In some embodiments of the invention, the method may comprise:

at the start of the active flying capacitor type inverter:

if the voltage at two ends of a first flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, or the voltage at two ends of a second flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, or the voltage at two ends of a third flying capacitor of the active flying capacitor type inverter is smaller than the first voltage, the transformer module is controlled to be switched from the off state to the on state;

and when the voltage at the two ends of the first flying capacitor is not less than the first voltage, the voltage at the two ends of the second flying capacitor is not less than the first voltage, and the voltage at the two ends of the third flying capacitor is not less than the first voltage, controlling an inverter bridge of the active flying capacitor type inverter to start working.

According to the embodiment of the invention, a five-winding transformer (transformer 1012) is adopted on the alternating current side, and a slow start switch unit (comprising a first branch and a second branch) is added at the same time, so that the direct current charging of the active flying capacitor type inverter is realized, the power conversion can be finally realized, the voltage resistance selection of partial switch tubes of each phase inverter bridge is synchronously realized and is reduced by half compared with the traditional scheme, the cost is reduced, the conversion efficiency of a main loop is not influenced, and the switch tubes with low voltage resistance have better performance, so that the conversion efficiency can be synchronously improved.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.