HAVING H5 TOPOLOGICAL STRUCTURE

Technical Field

The present invention relates to an inverter technique, in particular to a control processing method for an inverter device having an H5 topological structure.

Background

As a core device for converting direct-current power provided by a solar module into alternating-current power for civil or industrial use, photovoltaic inverters take an

increasingly important place in the field of new energy. In recent years, transformer-less photovoltaic inverters develop fast and are widely applied in the market. However, most inverters in the market at present only have a single function such as a grid-connected or off-grid function. Even though they have integrated functions such as grid-connected, off-grid and energy storage functions, the operation and control methods of most inverters are single, and the overall efficiency and safety friendliness of the system are deficient. With the sharp increase of the demands of the photovoltaic market, photovoltaic inverters having integrated function of grid-connected, off-grid and emergency SPS become increasingly popular with people.

Summary of the Invention

The present invention provides a control processing method for an inverter device having an H5 topological structure, so as to solve the problem of the prior art.

In order to achieve the purpose of the present invention, the present invention provides a control processing method for an inverter device having an H5 topological structure, and the inverter device has an H5 topological inverter bridge structure and grid-connected, off-grid and emergency SPS integrated functions. The control processing method includes: when a power grid supplies power normally, using a first control mode to operate the inverter device, wherein in the first control mode, a unipolar H5 PWM modulation mode is used to enable the inverter device to work in a grid-connected power generation mode; when the power grid supplies power abnormally or the power grid is in outage for a short time, using a second control mode to operate the inverter device, wherein in the second control mode, a unipolar H5 PWM constant- voltage modulation mode is used to enable the inverter device to work in an off-grid power generation mode; and when the power grid is in outage for a long time, using a third control mode to operate the inverter device, wherein in the third control mode, an H5-1 PWM constant- voltage modulation mode is used to enable the inverter device to work in an emergency SPS power generation mode.

Further, the inverter device includes a switch unit, a first load, a second load, a conversion unit, a PV unit and a capacitive energy storage unit; in the first control mode, the switch unit is switched to a first working mode to enable an alternating-current power source to drive the first load to work and enable the alternating-current power source to be connected after passing though the conversion unit, the PV unit and the capacitive energy storage unit, and the capacitive energy storage unit is in an energy storage state; in the second control mode, the switch unit is switched to a second working mode to cut off the alternating-current power source and enable the capacitive energy storage unit to be connected with the first load after passing through the PV unit and the conversion module, to make the capacitive energy storage unit discharge to drive the first load to work; and in the third control mode, the switch unit is switched to a third working mode to cut off the alternating-current power source and enable the capacitive energy storage unit to be connected with the second load after passing through the PV unit and the conversion module, to make the capacitive energy storage unit discharge to drive the second load to work.

Further, the second load includes the first load.

Further, the conversion unit in the inverter device is a DC-AC conversion unit or a DC-DC conversion unit.

Further, the switch unit includes a first switch, a second switch, a third switch and a fourth switch, wherein the first switch, the second switch and the third switch are connected in series and then are connected between the conversion unit and the alternating-current power source, the first switch is connected with the conversion unit and the third switch is connected with the alternating-current power source; two ends of the first load are respectively connected with a live line and a null line, and the first load is connected between the second switch and the third switch; and the second load and the fourth switch are connected in series and then are used as an integral body, two ends of the integral body are respectively connected with the live line and the null line, and the integral body is connected between the first switch and the second switch.

Further, when the switch unit is switched to the first working mode, the first switch, the second switch and the third switch are closed, and the fourth switch is opened; when the switch unit is switched to the second working mode, the first switch and the second switch are closed, and the third switch and the fourth switch are opened; and when the switch unit is switched to the third working mode, the first switch and the fourth switch are closed, and the second switch and the third switch are opened.

Further, in the off-grid power generation mode, an input end voltage of the first load is automatically adjusted according to a first change rate kl within a first preset range based on a load condition, the input end voltage of the first load is increased when the load is heavy, and the input end voltage of the first load is decreased when the load is light.

Further, the inverter device includes a fifth switch tube, a working mode of an inverter module is automatically controlled according to illumination intensity prediction in the emergency SPS power generation mode, the fifth switch tube works in an SPWM mode when the illumination intensity is strong, and the fifth switch tube works in a direct mode when the illumination intensity is weak.

Further, in the emergency SPS power generation mode, an input end voltage of the second load is automatically adjusted according to a second change rate k2 within a second preset range based on a load condition, the input end voltage of the second load is increased when the load is heavy, and the input end voltage of the second load is decreased when the load is light.

Further, in the emergency SPS power generation mode, an input end voltage of the second load is automatically adjusted within a third preset range based on Vmppt voltage; an AC output end voltage is 0.5*Urate2 when Vmppt<(r*Urate2+20V); and an AC output end voltage is (Vmppt-20V)/r when Vmppt>(rUrate2+20V), where Urate 1 is the input end voltage of the first load and Urate2 is the input end voltage of the second load.

As compared with the prior art, the control processing method for the inverter device having the H5 topological structure provided by the present invention can guarantee that the inverter device under an integrated working environment of grid-connected, off-grid and emergency SPS can have higher safety, reliability, efficiency and intelligence friendliness.

Further, when the power grid supplies power normally, the inverter device is in a grid-connected state, at this moment the switches SI, S2 and S3 are in a closed state and the switch S4 is in an opened state; for the H5 inverter bridge which uses the unipolar H5 PWM modulation mode, the common-mode voltage of the system can be effectively guaranteed, the leakage current of the system is effectively reduced and the safety of the system is guaranteed; and as compared with topologies such as HERIC, the efficiency is higher and better profits are created for users.

Further, when the power grid supplies power abnormally or the power grid is in outage for a short time, the inverter device works in an off-grid state, at this moment the switches S 1 and S2 are in a closed state, and the switches S3 and S4 are in an opened state; and for the H5 inverter bridge which uses the unipolar H5 PWM constant- voltage modulation mode, the stability and the reliability of the user power supply system are guaranteed. In this working state, the inverter device can automatically adjust the output voltage Urate 1 according to the change rate kl within 100%-75% of rated voltage based on the load condition. When the load is heavy, the output voltage is increased to decrease the output current and to decrease the loss of the system, and the efficiency of the system can be effectively improved.

Further, when the power grid is in outage for a long time, the power of the photovoltaic system seems particularly precious, the use of the power for important loads is preferentially satisfied, and the maximum utilization of the system efficiency is guaranteed. At this moment, the inverter device works in an emergency SPS state, at this moment the switches SI and S4 are in a closed state, and the switches S2 and S3 are in an opened state; for the H5 inverter, the unipolar H5-1 PWM constant-voltage modulation mode is used. In case of sufficient illumination intensity in this modulation mode, the switch tube T5 is in an SPWM working mode, like the normal H5 PWM constant- voltage modulation working mode, at this moment the inverter system has a better common-mode feature and can guarantee the normal working of the load. When the illumination intensity is weak, the switch tube T5 is in a direct working mode, the H5 inverter bridge module works in an H4 PWM constant- voltage modulation mode. At this moment, since there is no switch loss of the switch tube T5 and the device output voltage is automatically adjusted according to the load condition and the Vmppt voltage of the photovoltaic inverter device, the inverter device system is enabled to always work under the maximum efficiency. Herein, when the load is heavy, Urate2 is increased; and when the load is light, Urate2 is decreased. Thus the output voltage is automatically adjusted according to the change rate k2 within 100%-50% based on the load condition; AC output end voltage is 0.5*Urate2 when Vmppt<(r*Urate2+20V); and AC output end voltage is

(Vmppt-20V)/r when Vmppt>(rUrate2+20V).

Other features and advantages of the present invention will be described below in the description, and will partially become apparent from the description or can be understood by implementing the present invention. The purposes and other advantages of the present invention can be realized and achieved through structures particularly pointed out in the description, claims and drawings.

Brief Description of Drawings

The drawings are used for providing further understanding about the technical solution of the present invention, constitute a part of the description, are used together with embodiments of the present invention for explaining the technical solution of the present invention, and do not constitute limitations to the technical solution of the present invention.

FIG. 1 illustrates a flowchart of a control processing method for an inverter device having an H5 topological structure according to the present invention.

FIG. 2 illustrates a structural schematic diagram of an inverter device having an H5 topological structure.

FIG. 3 illustrates a structural diagram of an example of an H5 topological inverter device.

Specific Embodiments of the Invention

In order to make the purposes, the technical solutions and advantages of the present invention more clear, embodiments of the present invention will be described below in detail with reference to the drawings. It needs to be stated that embodiments in the present application and the features in the embodiments may be mutually and freely combined under a situation of no conflict.

Steps illustrated by the flowchart in the drawings may be executed in a computer system consisting of a group of computer-executable instructions. In addition, although a logical sequence is illustrated in the flowchart, under certain situations, the illustrated or described steps may be executed according to a sequence different from the sequence here.

The embodiment of the present invention provides a control processing method for an inverter device having an H5 topological structure. The control processing method includes: when a power grid supplies power normally, using a first control mode to operate the inverter device, wherein in the first control mode, a unipolar H5 PWM modulation mode is used to enable the inverter device to work in a grid-connected power generation mode; when the power grid supplies power abnormally or the power grid is in outage for a short time, using a second control mode to operate the inverter device, wherein in the second control mode, a unipolar H5 PWM constant- voltage modulation mode is used to enable the inverter device to work in an off-grid power generation mode; and when the power grid is in outage for a long time, using a third control mode to operate the inverter device, wherein in the third control mode, an H5-1 PWM constant- voltage modulation mode is used to enable the inverter device to work in an emergency SPS power generation mode.

FIG. 1 illustrates a flowchart of a processing example of a control processing method for an inverter device having an H5 topological structure according to the present invention.

As illustrated in FIG. 1, after the process starts, firstly step SI 00, i.e., determining a current state of the power grid, is executed.

When the power grid supplies power normally, step S101 is executed.

In step S101, a first control mode is used to operate the inverter device. In the first control mode, a unipolar H5 PWM modulation mode is used to enable the inverter device to work in a grid-connected power generation mode. In this way, the inverter can be enabled to have higher efficiency and lower leakage current, such that it works in the grid-connected power generation mode safely and efficiently. Herein, the unipolar H5 PWM modulation mode refers to a mode of using a unipolar PWM modulation mode for an H5 topological switch tube. When the power grid supplies power abnormally or the power grid is in outage for a short time, step SI 02 is executed. Herein, the situation that the power grid is in outage for a short time, for example, refers to a situation that the power grid is in outage and the power of the power generation system is greater than the current load power.

In step SI 02, a second control mode is used to operate the inverter device. In the second control mode, a unipolar H5 PWM constant- voltage modulation mode is used to enable the inverter device to work in an off-grid power generation mode. In this way, the inverter device can be enabled to have higher efficiency, lower leakage current and more stable power quality, to make it work in the off-grid power generation mode safely and efficiently. Herein, the unipolar H5 PWM constant-voltage modulation mode refers to a mode of using a unipolar PWM modulation mode for an H5 topological switch tube, controlling an AC output side by using a voltage loop and making the output voltage be a specific real-time set value.

When the power grid is in outage for a long time, step SI 03 is executed. Herein, the situation that the power grid is in outage for a long time, for example, refers to a situation that the power grid is in outage and the power of the power generation system is less than the current load power.

In step SI 03, a third control mode is used to operate the inverter device. In the third control mode, an H5-1 PWM constant- voltage modulation mode is used to enable the inverter device to work in an emergency Solar Power from Space (SPS) power generation mode. In this way, the inverter device can have high-efficiency and high-safety emergency power source function, more stable power quality and higher efficiency, to make it work in the emergency SPS generation mode safely and efficiently. Herein, the H5-1 PWM constant-voltage modulation mode refers to a mode of using direct control for the switch tube T5 in an H5 topology, using a unipolar PWM modulation mode for H-bridge switch tubes T1-T4, controlling an AC output side by using a voltage loop and making the output voltage as a specific real-time set value.

According to one implementation mode, the inverter device may include a switch unit, a first load Loadl, a second load Load2, a conversion unit, a PV unit and a capacitive energy storage unit.

In the first control mode, for example, the switch unit may be switched to a first working mode to enable an alternating-current power source to drive the first load to work and enable the alternating-current power source to be grounded after passing though the conversion unit, the PV unit and the capacitive energy storage unit, and the capacitive energy storage unit is in an energy storage state.

In the second control mode, for example, the switch unit may be switched to a second working mode to cut off the alternating-current power source and enable the capacitive energy storage unit to be connected with the first load after passing through the PV unit and the conversion module, to make the capacitive energy storage unit discharge to drive the first load to work.

In the third control mode, for example, the switch unit may be switched to a third working mode to cut off the alternating-current power source and enable the capacitive energy storage unit to be connected with the second load after passing through the PV unit and the conversion module, to make the capacitive energy storage unit discharge to drive the second load to work.

The second load, for example, may include the first load.

The first load may be a load of a universal photovoltaic power generation system, such as household electrics, lighting or vehicle charging load.

The second load, for example, may be a load that needs to be used or work in a power shortage state, such as a mobile phone charger, an emergency lighting power source load or a firefighting power source load.

Besides, the conversion unit in the inverter device, for example, may be a DC-AC conversion unit or a DC-DC conversion unit.

According to one implementation mode, as illustrated in FIG. 2, the switch unit, for example, may include a first switch SI, a second switch S2, a third switch S3 and a fourth switch S4, wherein the first switch, the second switch and the third switch are connected in series and then are connected between the conversion unit and the alternating-current power source AC, the first switch is connected with the conversion unit and the third switch is connected with the alternating-current power source. Two ends of the first load, for example, are respectively connected with a live line and a null line, and the first load is connected between the second switch and the third switch. The second load and the fourth switch are connected in series and then are used as an integral body, two ends of the integral body are respectively connected with the live line and the null line, and the integral body is connected between the first switch and the second switch.

For example, when the switch unit is switched to the first working mode, the first switch, the second switch and the third switch are closed, and the fourth switch is opened; when the switch unit is switched to the second working mode, the first switch and the second switch are closed, and the third switch and the fourth switch are opened; and when the switch unit is switched to the third working mode, the first switch and the fourth switch are closed, and the second switch and the third switch are opened.

According to one implementation mode, in the off-grid power generation mode, an input end voltage Urate 1 of the first load Loadl is automatically adjusted according to a first change rate kl within a first preset range based on a load condition, the input end voltage of the first load is increased when the load is heavy, and the input end voltage of the first load is decreased when the load is light. Herein, the first preset range, for example, may be

100%-75% but is not limited thereto. Herein, the first change rate kl refers to a charge adjustment rate of the output load end voltage in the off-grid power generation mode and is obtained by detecting the voltage and current of the input end of the load at a current moment (tn) and the voltage and current of the input end of the load at a previous moment (tn-1).

According to one implementation mode, as illustrated in FIG. 3, an H5 topological structure 1 (the part illustrated by a dashed frame) of the inverter device consists of a first switch tube Tl, a second switch tube T2, a third switch tube T3, a fourth switch tube T4 and a fifth switch tube T5. Herein, a capacitor DC-Link is connected between DC+ and DC-, one end of the fifth switch tube T5 is connected with DC+ and the other end is connected with the first switch tube Tl . In the drawing, DC-Link is a BUS capacitor, La and Lb are inverter output inductors, and Loadl and Load2 are the first load and the second load.

The working mode of an inverter module is automatically controlled for example according to illumination intensity prediction in the emergency SPS power generation mode. The fifth switch tube T5 works in an SPWM mode when the illumination intensity is strong, and the fifth switch tube T5 works in a direct mode when the illumination intensity is weak. According to one implementation mode, in the emergency SPS power generation mode, an input end voltage of the second load, for example, may be automatically adjusted according to a second change rate k2 within a second preset range based on a load condition, the input end voltage of the second load is increased when the load is heavy, and the input end voltage of the second load is decreased when the load is light. The second preset range, for example, may be 100%-50% but is not limited thereto. The second change rate k2 refers to a charge adjustment rate of the output load end voltage in the emergency SPS power generation mode and is obtained by detecting the voltage and current of the input end of the load at a current moment (tn) and the voltage and current of the input end of the load at a previous moment (tn-1).

According to one implementation mode, in the emergency SPS power generation mode, the input end voltage of the second load, for example, may be automatically adjusted within a third preset range according to Vmppt voltage. The AC output end voltage is 0.5*Urate2 when Vmppt<(r*Urate2+20V); and the AC output end voltage is (Vmppt-20V)/r when Vmppt>(rUrate2+20 V) .

Urate 1 is the input end voltage of the first load, Urate2 is the input end voltage of the second load, and r is an AC-DC coefficient, for example, may be 1.414, and however is not limited to 1.414. Vmppt is a voltage across two ends of the capacitor DC-Link.

The third preset range, for example, may be 100%-50% but is not limited thereto.

Although the present invention discloses the implementation modes above, the

above-mentioned contents are just implementation modes used for facilitating the

understanding about the present invention instead of limiting the present invention. One skilled in the art may make any modification and variation to the implementation modes and details without departing from the essence and scope disclosed by the present invention. However, the patent protection scope of the present invention shall be still subject to the scope defined by the attached claims.