Full-bridge sub-module loss equalization modulation method and full-bridge sub-module loss equalization modulation device

Abstract

The invention provides a full-bridge sub-module loss equalization modulation method and device. And determining the number of full-bridge sub-modules needing to be input by the bridge arm according to the modulation voltage of the bridge arm. The modulation period is divided into a plurality of modulation periods according to the modulation voltage. And according to the number of the full-bridge sub-modules needing to be input by the bridge arm, carrying out balanced modulation on the loss of the full-bridge sub-modules in each modulation time period in the plurality of modulation time periods. According to the method and the device, the loss of the full-bridge sub-module is subjected to balanced modulation in each modulation time period by dividing the modulation time periods, so that the loss balance of the power electronic device in the full-bridge sub-module can be realized. The service life of the power electronic device can be greatly prolonged, faults caused by local overheating and excessive loss of the power electronic device are effectively reduced, the operation stability of the full-bridge sub-module can be improved, and the transmission power and the output electric energy quality of the full-bridge sub-module are further improved.

Description

Technical Field

[0001] The present application relates to the technical field of direct current (DC) power grids, and in particular to a full-bridge submodule loss balancing modulation method and device. Background Art

[0002] Currently, flexible DC transmission technology plays a key role in grid construction and energy interconnection due to its unique advantages, including its ability to achieve large-capacity, long-distance power transmission, flexible control of power flow, and low dependence on AC systems. As the core component of flexible DC transmission systems, the performance of modular multilevel converters (MMCs) directly affects the stability and efficiency of the entire system.

[0003] The full-bridge module, the basic unit of the MMC, consists of power electronic devices and capacitors. Full-bridge modules are primarily used in fault handling scenarios in flexible DC transmission. During normal operation, the negative input state is rarely activated. The full-bridge module is only placed in this state when a fault occurs to maintain system stability. Consequently, during the design and operation of the full-bridge module, little attention was paid to the losses of the power electronic devices during this negative input state. However, with the development of power systems, especially in scenarios such as DC transformers where the full-bridge module frequently switches between positive and negative voltages, the shortcomings of the full-bridge module in terms of loss balancing have become increasingly apparent. In these alternating positive and negative voltage scenarios, improper selection of the on and off states of the power electronic devices leads to uneven loss distribution across the components, further increasing junction temperature. This not only shortens the life of the power electronic devices but also reduces the transmission power of the full-bridge module. Summary of the Invention

[0004] In order to solve the problem in the prior art that power electronic devices in a full-bridge sub-module have a short service life and the transmission power of the full-bridge sub-module is low, the present application provides a full-bridge sub-module loss balancing modulation method and device.

[0005] In a first aspect, the present application provides a full-bridge sub-module loss balancing modulation method, which may include:

[0006] The number of full-bridge sub-modules required for the bridge arm is determined based on the modulation voltage of the bridge arm.

[0007] The modulation period is divided into a plurality of modulation periods according to the modulation voltage.

[0008] According to the number of full-bridge sub-modules required to be put into the bridge arm, the losses of the full-bridge sub-modules are balanced modulated in each modulation period of the plurality of modulation periods.

[0009] In some possible implementations, the number of full-bridge sub-modules required for the bridge arm is determined based on the modulation voltage of the bridge arm, including:

[0010] Obtain the modulation voltage. Use the nearest level approximation modulation method to round the modulation voltage and take its absolute value to obtain the number of full-bridge sub-modules required for the bridge arm.

[0011] Optionally, the multiple modulation time periods include a first modulation time period, a second modulation time period, a third modulation time period and a fourth modulation time period.

[0012] The first modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from a positive voltage peak to zero.

[0013] The second modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from 0 to a negative voltage peak.

[0014] The third modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from a negative voltage peak to zero.

[0015] The fourth modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from 0 to a positive voltage peak.

[0016] Exemplarily, the full-bridge submodule includes a first power tube, a second power tube, a third power tube, and a fourth power tube.

[0017] The first pole of the first power tube is connected to the first pole of the third power tube, the second pole of the first power tube is connected to the first pole of the second power tube, serving as the first end of the full-bridge sub-module, the second pole of the third power tube is connected to the first pole of the fourth power tube, serving as the second end of the full-bridge sub-module, and the second pole of the second power tube is connected to the second pole of the fourth power tube.

[0018] In some other possible implementations, based on the number of full-bridge sub-modules required in the bridge arm, the losses of the full-bridge sub-modules are balanced modulated in each of the multiple modulation periods, including:

[0019] In the first modulation period, the first power tube and the third power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the second power tube and the fourth power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0020] In the second modulation period, the second and third power tubes are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the first and fourth power tubes are controlled to be turned off to put the full-bridge sub-modules into operation.

[0021] In the third modulation period, the second power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the first power tube and the third power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0022] In the fourth modulation period, the first power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the second power tube and the third power tube are controlled to be turned off to put the full-bridge sub-modules into operation.

[0023] In one example, in a first modulation period, controlling the first power tube and the third power tube to be turned on and controlling the second power tube and the fourth power tube to be turned off according to the number of full-bridge sub-modules required to be put into operation in the bridge arm to remove the full-bridge sub-modules includes:

[0024] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0025] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0026] Furthermore, when the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are removed, including:

[0027] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, whose sub-module capacitor voltages are sorted from large to small, are cut off.

[0028] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0029] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0030] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0031] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0032] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0033] The full-bridge submodule in the first cut-off state is used to indicate the full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0034] In another example, in the second modulation period, according to the number of full-bridge sub-modules that need to be put into operation in the bridge arm, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-modules are put into operation, including:

[0035] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0036] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0037] Furthermore, when the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, H full-bridge sub-modules are put into use, including:

[0038] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0039] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0040] The full-bridge submodule in the first cut-off state is used to indicate the full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0041] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0042] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0043] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0044] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0045] In another example, in the third modulation period, the second power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into the bridge arm, and the first power tube and the third power tube are controlled to be turned off, thereby removing the full-bridge sub-modules, including:

[0046] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0047] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0048] Furthermore, when the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are removed, including:

[0049] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0050] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted from large to small in terms of sub-module capacitor voltage, are cut off.

[0051] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0052] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0053] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0054] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0055] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0056] In another example, in the fourth modulation period, according to the number of full-bridge sub-modules that need to be put into the bridge arm, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-modules are put into use, including:

[0057] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0058] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0059] Furthermore, when the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, H full-bridge sub-modules are put into use, including:

[0060] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0061] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0062] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0063] Optionally, when the number of full-bridge sub-modules put into operation is equal to the number of full-bridge sub-modules that the bridge arm needs to put into operation at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting another full-bridge sub-module into operation includes:

[0064] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0065] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0066] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0067] In a second aspect, the present application provides a full-bridge sub-module loss balancing modulation device, which may include:

[0068] The determination module is used to determine the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm.

[0069] The division module is used to divide the modulation period into multiple modulation time periods according to the modulation voltage.

[0070] The modulation module is used to balance the loss of the full-bridge sub-modules in each modulation period of multiple modulation periods according to the number of full-bridge sub-modules required to be invested in the bridge arm.

[0071] In some possible implementations, the determination module is specifically configured to:

[0072] Obtain the modulation voltage. Use the nearest level approximation modulation method to round the modulation voltage and take its absolute value to obtain the number of full-bridge sub-modules required for the bridge arm.

[0073] Optionally, the multiple modulation time periods include a first modulation time period, a second modulation time period, a third modulation time period and a fourth modulation time period.

[0074] The first modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from a positive voltage peak to zero.

[0075] The second modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from 0 to a negative voltage peak.

[0076] The third modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from a negative voltage peak to zero.

[0077] The fourth modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from 0 to a positive voltage peak.

[0078] Exemplarily, the full-bridge submodule includes a first power tube, a second power tube, a third power tube, and a fourth power tube.

[0079] The first pole of the first power tube is connected to the first pole of the third power tube, the second pole of the first power tube is connected to the first pole of the second power tube, serving as the first end of the full-bridge sub-module, the second pole of the third power tube is connected to the first pole of the fourth power tube, serving as the second end of the full-bridge sub-module, the first pole of the second power tube is connected to the second pole of the fourth power tube.

[0080] In some other possible implementations, the modulation module is specifically configured to:

[0081] In the first modulation period, the first power tube and the third power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the second power tube and the fourth power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0082] In the second modulation period, the second and third power tubes are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the first and fourth power tubes are controlled to be turned off to put the full-bridge sub-modules into operation.

[0083] In the third modulation period, the second power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the first power tube and the third power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0084] In the fourth modulation period, the first power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the second power tube and the third power tube are controlled to be turned off to put the full-bridge sub-modules into operation.

[0085] In one example, the modulation module is specifically configured to:

[0086] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0087] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0088] Furthermore, the modulation module is specifically used to:

[0089] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, whose sub-module capacitor voltages are sorted from large to small, are cut off.

[0090] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0091] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0092] Exemplarily, the modulation module is specifically configured to:

[0093] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0094] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, and the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0095] The full-bridge submodule in the positive input state is used to indicate that the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off. The full-bridge submodule in the first cut-off state is used to indicate that the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0096] In another example, the modulation module is specifically configured to:

[0097] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0098] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0099] Furthermore, the modulation module is specifically used to:

[0100] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0101] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0102] The full-bridge submodule in the first cut-off state is used to indicate the full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0103] Optionally, the modulation module is specifically used for:

[0104] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0105] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0106] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0107] In yet another example, the modulation module is specifically configured to:

[0108] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0109] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0110] Furthermore, the modulation module is specifically used to:

[0111] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0112] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted from large to small in terms of sub-module capacitor voltage, are cut off.

[0113] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0114] Optionally, the modulation module is specifically used for:

[0115] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0116] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0117] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0118] In another example, when the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0119] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0120] Furthermore, the modulation module is specifically used to:

[0121] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0122] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0123] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0124] Optionally, the modulation module is specifically used for:

[0125] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0126] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0127] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0128] On the other hand, the present application also provides a computer device, including: one or more processors.

[0129] A processor is used to execute one or more programs.

[0130] When one or more programs are executed by one or more processors, the modulation method described above is implemented.

[0131] In another aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the above-mentioned modulation method.

[0132] Compared with the prior art, the present invention has the following advantages:

[0133] In the full-bridge sub-module loss balancing modulation method provided by the present application, the number of full-bridge sub-modules that need to be put into the bridge arm is determined according to the modulation voltage of the bridge arm. The modulation cycle is divided into multiple modulation time periods according to the modulation voltage. According to the number of full-bridge sub-modules that need to be put into the bridge arm, the loss of the full-bridge sub-module is balanced modulated in each modulation time period of the multiple modulation time periods. The present application can achieve loss balancing of power electronic devices in the full-bridge sub-module by dividing the power electronic devices into multiple modulation time periods and performing balanced modulation on the loss of the full-bridge sub-module in each modulation time period. It can not only greatly extend the service life of the power electronic devices, effectively reduce the failure of the power electronic devices due to local overheating and excessive loss, but also improve the operating stability of the full-bridge sub-module, thereby improving the transmission power and output power quality of the full-bridge sub-module.

[0134] The technical solution provided in this application not only effectively improves the reliability and stability of the DC transformer, but also reduces the replacement and maintenance frequency of the full-bridge submodule, minimizing losses from unplanned power outages caused by full-bridge submodule failures and ensuring the continuity of power supply. It also reduces material and other investment in equipment maintenance and replacement, lowering the operational and maintenance costs of the DC converter where the full-bridge submodule resides.

[0135] The technical solution provided in this application helps DC transformers to be widely used in more complex working conditions and provides strong support for the development of the power transmission field. BRIEF DESCRIPTION OF THE DRAWINGS

[0136] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0137] Figure 1 This is a schematic structural diagram of a full-bridge submodule in an embodiment of the present application;

[0138] Figure 2 This is a schematic flow chart of a full-bridge sub-module loss balancing modulation method in an embodiment of the present application;

[0139] Figure 3 Schematic diagram of the division of the modulation period in the embodiment of the present application;

[0140] Figure 4 This is a schematic structural diagram of the full-bridge sub-module loss balancing modulation device in an embodiment of the present application. DETAILED DESCRIPTION

[0141] The technical solution in this application will be described below with reference to the accompanying drawings.

[0142] The terms "first," "second," and the like in the description, embodiments, claims, and drawings of this application are used solely for descriptive purposes and are not to be construed as indicating or implying relative importance or order. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions, such as, for example, inclusion of a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0143] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0144] Example 1:

[0145] The embodiment of the present application provides a full-bridge submodule loss balancing modulation method. Figure 1 As shown, the full-bridge submodule SM may include a first power transistor S1, a second power transistor S2, a third power transistor S3 and a fourth power transistor S4. The first power transistor S1, the second power transistor S2, the third power transistor S3 and the fourth power transistor S4 may all be IGBTs with anti-parallel diodes.

[0146] The first pole (which may be a collector) of the first power tube S1 is connected to the first pole (which may be a collector) of the third power tube S3, and the second pole (which may be an emitter) of the first power tube S1 is connected to the first pole (which may be a collector) of the second power tube S2. As the first end of the full-bridge sub-module SM, the second pole (which may be an emitter) of the third power tube S3 is connected to the first pole (which may be a collector) of the fourth power tube S4. As the second end of the full-bridge sub-module SM, the second pole (which may be an emitter) of the second power tube S2 is connected to the second pole (which may be an emitter) of the fourth power tube S4.

[0147] Of course, if Figure 1The full-bridge submodule SM may further include a resistor R and a capacitor C. The first ends of the resistor R and the capacitor C are each connected to the first electrode of the first power transistor S1, and the second ends of the resistor R and the capacitor C are each connected to the second electrode of the second power transistor S2. The full-bridge submodule SM may also include a bypass switch K.

[0148] like Figure 2 As shown, the modulation method 100 includes the following steps:

[0149] Step S101: determining the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm.

[0150] Step S102: dividing the modulation period into a plurality of modulation time periods according to the modulation voltage.

[0151] Step S103: performing balanced modulation on the losses of the full-bridge sub-modules in each of the plurality of modulation time periods according to the number of full-bridge sub-modules required to be put into the bridge arm.

[0152] In some possible implementations, determining the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm in step S101 includes:

[0153] Obtain the modulation voltage. Use the nearest level approximation modulation method to round the modulation voltage and take its absolute value to obtain the number of full-bridge sub-modules required for the bridge arm.

[0154] Optionally, the plurality of modulation periods include a first modulation period T1, a second modulation period T2, a third modulation period T3 and a fourth modulation period T4. Figure 3 shown. Figure 3 In the figure, the horizontal axis represents the modulation time in seconds, and the vertical axis represents the modulation voltage of the bridge arm.

[0155] The first modulation period T1 is used to indicate a modulation period corresponding to when the modulation voltage decreases from a positive voltage peak to zero.

[0156] The second modulation period T2 is used to indicate the modulation period corresponding to when the modulation voltage decreases from 0 to a negative voltage peak.

[0157] The third modulation period T3 is used to indicate the modulation period corresponding to the modulation voltage increasing from the negative voltage peak to 0.

[0158] The fourth modulation period T4 is used to indicate a modulation period corresponding to when the modulation voltage increases from 0 to a positive voltage peak.

[0159] In some other possible implementations, in step S103, based on the number of full-bridge sub-modules required to be put into the bridge arm, the losses of the full-bridge sub-modules are balanced modulated in each modulation period of the plurality of modulation periods, including:

[0160] In the first modulation period T1, the first and third power tubes are controlled to be turned on, and the second and fourth power tubes are controlled to be turned off, according to the number of full-bridge sub-modules required in the bridge arm, to remove the full-bridge sub-modules.

[0161] In the second modulation period T2, the second and third power tubes are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the first and fourth power tubes are controlled to be turned off to put the full-bridge sub-modules into operation.

[0162] In the third modulation period T3, the second power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the first power tube and the third power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0163] In the fourth modulation period T4, the first power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the second power tube and the third power tube are controlled to be turned off to put the full-bridge sub-modules into operation.

[0164] In one example, in the first modulation period T1, the first power tube S1 and the third power tube S3 are controlled to be turned on, and the second power tube S2 and the fourth power tube S4 are controlled to be turned off, according to the number of full-bridge sub-modules required to be put into the bridge arm, so as to remove the full-bridge sub-modules, including:

[0165] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0166] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0167] Furthermore, when the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are removed, including:

[0168] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, whose sub-module capacitor voltages are sorted from large to small, are cut off.

[0169] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0170] The full-bridge submodule in the positive input state is used to indicate that the first power tube S1 and the fourth power tube S4 are both turned on and the second power tube S2 and the third power tube S3 are both turned off.

[0171] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0172] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube S1 and the fourth power tube S4 are controlled to be turned on, and the second power tube S2 and the third power tube S3 are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0173] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube S1 and the fourth power tube S4 are controlled to be turned on, and the second power tube S2 and the third power tube S3 are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0174] The full-bridge submodule in the first cut-off state is used to indicate a full-bridge submodule in which the first power tube S1 and the third power tube S3 are both turned on and the second power tube S2 and the fourth power tube S4 are both turned off.

[0175] In another example, in the second modulation period T2, the second power tube S2 and the third power tube S3 are controlled to be turned on according to the number of full-bridge sub-modules that need to be put into operation in the bridge arm, and the first power tube S1 and the fourth power tube S4 are controlled to be turned off, and the full-bridge sub-modules are put into operation, including:

[0176] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0177] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0178] Furthermore, when the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, H full-bridge sub-modules are put into use, including:

[0179] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0180] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0181] The full-bridge submodule in the first cut-off state is used to indicate a full-bridge submodule in which the first power tube S1 and the third power tube S3 are both turned on and the second power tube S2 and the fourth power tube S4 are both turned off.

[0182] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0183] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube S2 and the third power tube S3 are controlled to be turned on, and the first power tube S1 and the fourth power tube S4 are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0184] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube S2 and the third power tube S3 are controlled to be turned on, and the first power tube S1 and the fourth power tube S4 are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0185] The full-bridge submodule in the negative input state is used to indicate that the second power tube S2 and the third power tube S3 are both turned on and the first power tube S1 and the fourth power tube S4 are both turned off.

[0186] In another example, in the third modulation period T3, the second power tube S2 and the fourth power tube S4 are controlled to be turned on according to the number of full-bridge sub-modules required to be put into the bridge arm, and the first power tube S1 and the third power tube S3 are controlled to be turned off, thereby removing the full-bridge sub-modules, including:

[0187] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0188] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0189] Furthermore, when the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are removed, including:

[0190] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0191] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted from large to small in terms of sub-module capacitor voltage, are cut off.

[0192] The full-bridge submodule in the negative input state is used to indicate that the second power tube S2 and the third power tube S3 are both turned on and the first power tube S1 and the fourth power tube S4 are both turned off.

[0193] Optionally, when the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module includes:

[0194] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube S2 and the third power tube S3 are controlled to be turned on, and the first power tube S1 and the fourth power tube S4 are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0195] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube S2 and the third power tube S3 are controlled to be turned on, and the first power tube S1 and the fourth power tube S4 are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0196] The full-bridge submodule in the second cut-off state is used to indicate a full-bridge submodule in which the second power tube S2 and the fourth power tube S4 are both turned on and the first power tube S1 and the third power tube S3 are both turned off.

[0197] In another example, in the fourth modulation period T4, the first power tube S1 and the fourth power tube S4 are controlled to be turned on according to the number of full-bridge sub-modules that need to be put into the bridge arm, and the second power tube S2 and the third power tube S3 are controlled to be turned off, and the full-bridge sub-modules are put into use, including:

[0198] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0199] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0200] Furthermore, when the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, H full-bridge sub-modules are put into use, including:

[0201] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0202] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0203] The full-bridge submodule in the second cut-off state is used to indicate a full-bridge submodule in which the second power tube S2 and the fourth power tube S4 are both turned on and the first power tube S1 and the third power tube S3 are both turned off.

[0204] Optionally, when the number of full-bridge sub-modules put into operation is equal to the number of full-bridge sub-modules that the bridge arm needs to put into operation at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting another full-bridge sub-module into operation includes:

[0205] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube S1 and the fourth power tube S4 are controlled to be turned on, and the second power tube S2 and the third power tube S3 are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0206] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube S1 and the fourth power tube S4 are controlled to be turned on, and the second power tube S2 and the third power tube S3 are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0207] The full-bridge submodule in the positive input state is used to indicate that the first power tube S1 and the fourth power tube S4 are both turned on and the second power tube S2 and the third power tube S3 are both turned off.

[0208] Example 2:

[0209] Based on the same inventive concept, the embodiment of the present application also provides a full-bridge sub-module loss balancing modulation device. Figure 4 As shown, the modulation device 200 may include:

[0210] The determination module 201 is used to determine the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm.

[0211] The division module 202 is configured to divide the modulation period into a plurality of modulation time periods according to the modulation voltage.

[0212] The modulation module 203 is configured to perform balanced modulation on the losses of the full-bridge sub-modules in each of a plurality of modulation time periods according to the number of full-bridge sub-modules required to be put into the bridge arm.

[0213] In some possible implementations, the determining module 201 is specifically configured to:

[0214] Obtain the modulation voltage. Use the nearest level approximation modulation method to round the modulation voltage and take its absolute value to obtain the number of full-bridge sub-modules required for the bridge arm.

[0215] Optionally, the multiple modulation time periods include a first modulation time period, a second modulation time period, a third modulation time period and a fourth modulation time period.

[0216] The first modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from a positive voltage peak to zero.

[0217] The second modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from 0 to a negative voltage peak.

[0218] The third modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from a negative voltage peak to zero.

[0219] The fourth modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from 0 to a positive voltage peak.

[0220] Exemplarily, the full-bridge submodule includes a first power tube, a second power tube, a third power tube, and a fourth power tube.

[0221] The first pole of the first power tube is connected to the first pole of the third power tube, the second pole of the first power tube is connected to the first pole of the second power tube, serving as the first end of the full-bridge sub-module, the second pole of the third power tube is connected to the first pole of the fourth power tube, serving as the second end of the full-bridge sub-module, the first pole of the second power tube is connected to the second pole of the fourth power tube.

[0222] In some other possible implementations, the modulation module 203 is specifically configured to:

[0223] In the first modulation period, the first power tube and the third power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the second power tube and the fourth power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0224] In the second modulation period, the second and third power tubes are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the first and fourth power tubes are controlled to be turned off to put the full-bridge sub-modules into operation.

[0225] In the third modulation period, the second power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required in the bridge arm, and the first power tube and the third power tube are controlled to be turned off to remove the full-bridge sub-modules.

[0226] In the fourth modulation period, the first power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into operation in the bridge arm, and the second power tube and the third power tube are controlled to be turned off to put the full-bridge sub-modules into operation.

[0227] In one example, the modulation module 203 is specifically configured to:

[0228] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0229] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0230] Furthermore, the modulation module 203 is specifically configured to:

[0231] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, whose sub-module capacitor voltages are sorted from large to small, are cut off.

[0232] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0233] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0234] Exemplarily, the modulation module 203 is specifically configured to:

[0235] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0236] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, and the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0237] The full-bridge submodule in the positive input state is used to indicate that the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off. The full-bridge submodule in the first cut-off state is used to indicate that the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0238] In another example, the modulation module 203 is specifically configured to:

[0239] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0240] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0241] Furthermore, the modulation module 203 is specifically configured to:

[0242] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0243] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0244] The full-bridge submodule in the first cut-off state is used to indicate the full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

[0245] Optionally, the modulation module 203 is specifically configured to:

[0246] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0247] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation.

[0248] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0249] In yet another example, the modulation module 203 is specifically configured to:

[0250] When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed, where H=MN.

[0251] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0252] Furthermore, the modulation module 203 is specifically configured to:

[0253] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted in ascending order of sub-module capacitor voltage, are cut off.

[0254] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted from large to small in terms of sub-module capacitor voltage, are cut off.

[0255] The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

[0256] Optionally, the modulation module 203 is specifically configured to:

[0257] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0258] If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0259] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0260] In another example, when the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are put into operation, where H=NM.

[0261] When the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules that need to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than the preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

[0262] Furthermore, the modulation module 203 is specifically configured to:

[0263] If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation.

[0264] If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation.

[0265] The full-bridge submodule in the second cut-off state is used to indicate the full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

[0266] Optionally, the modulation module 203 is specifically configured to:

[0267] If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0268] If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation.

[0269] The full-bridge submodule in the positive input state is used to indicate the full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

[0270] Example 3:

[0271] Based on the same inventive concept, an embodiment of the present application further provides a computer device, comprising a processor and a memory, the memory being used to store a computer program, the computer program comprising program instructions, and the processor being used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of the modulation method provided in the above embodiment.

[0272] Example 4:

[0273] Based on the same inventive concept, an embodiment of the present application further provides a computer-readable storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device for storing programs and data. It is understandable that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the modulation method provided in the above embodiment.

[0274] Those skilled in the art will appreciate that embodiments of the application may be provided as methods, systems, or computer program products. Thus, the application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0275] The application is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0276] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1The function specified in one or more boxes.

[0277] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0278] The above are merely embodiments of the application and are not intended to limit the application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the application are included in the scope of the claims of the pending application.

Claims

1. A full-bridge submodule loss balancing modulation method, characterized in that: include: Determine the number of full-bridge sub-modules required for the bridge arm based on the modulation voltage of the bridge arm; dividing a modulation period into a plurality of modulation time periods according to the modulation voltage; According to the number of full-bridge sub-modules required to be put into the bridge arm, the losses of the full-bridge sub-modules are balanced modulated in each modulation period of the multiple modulation periods.

2. The modulation method according to claim 1, characterized in that The determining the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm includes: obtaining the modulation voltage; The modulation voltage is rounded and absolute-valued by adopting a nearest-level approximation modulation method to obtain the number of full-bridge sub-modules required for the bridge arm.

3. The modulation method according to claim 1, characterized in that The plurality of modulation periods include a first modulation period, a second modulation period, a third modulation period and a fourth modulation period; The first modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from a positive voltage peak to 0; The second modulation period is used to indicate a modulation period corresponding to when the modulation voltage decreases from 0 to a negative voltage peak; The third modulation period is used to indicate a modulation period corresponding to when the modulation voltage increases from the negative voltage peak value to 0; The fourth modulation period is used to indicate a modulation period during which the modulation voltage increases from 0 to the positive voltage peak.

4. The modulation method according to claim 3, characterized in that: The full-bridge submodule includes a first power tube, a second power tube, a third power tube and a fourth power tube; The first pole of the first power tube is connected to the first pole of the third power tube, the second pole of the first power tube is connected to the first pole of the second power tube, serving as the first end of the full-bridge sub-module, the second pole of the third power tube is connected to the first pole of the fourth power tube, serving as the second end of the full-bridge sub-module, and the second pole of the second power tube is connected to the second pole of the fourth power tube.

5. The modulation method according to claim 4, characterized in that: The method of performing balanced modulation on the loss of the full-bridge sub-module in each modulation period in the plurality of modulation periods according to the number of full-bridge sub-modules required to be invested in the bridge arm includes: During the first modulation period, the first power tube and the third power tube are controlled to be turned on according to the number of full-bridge sub-modules required for the bridge arm, and the second power tube and the fourth power tube are controlled to be turned off, thereby removing the full-bridge sub-modules; In the second modulation period, the second power tube and the third power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into the bridge arm, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-modules are put into use; In the third modulation period, according to the number of full-bridge sub-modules required to be put into the bridge arm, the second power tube and the fourth power tube are controlled to be turned on, and the first power tube and the third power tube are controlled to be turned off, thereby removing the full-bridge sub-module; In the fourth modulation period, the first power tube and the fourth power tube are controlled to be turned on according to the number of full-bridge sub-modules required to be put into the bridge arm, and the second power tube and the third power tube are controlled to be turned off to put the full-bridge sub-modules into use.

6. The modulation method according to claim 5, characterized in that: The method of controlling the first power tube and the third power tube to be turned on and controlling the second power tube and the fourth power tube to be turned off according to the number of full-bridge sub-modules required to be put into the bridge arm during the first modulation period, thereby removing the full-bridge sub-module, includes: When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed; wherein H=MN; When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

7. The modulation method according to claim 6, characterized in that: When the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, removing H full-bridge sub-modules includes: If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted from large to small in terms of sub-module capacitor voltage; If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the positive input state, which are sorted in ascending order of sub-module capacitor voltages; The full-bridge submodule in the positive input state is used to indicate a full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

8. The modulation method according to claim 7, characterized in that: When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation amount of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module, comprising: If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation; If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitor voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitor voltage among the full-bridge sub-modules in the first cut-off state is put into operation; The full-bridge submodule in the first cut-off state is used to indicate a full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

9. The modulation method according to claim 5, characterized in that: The method of controlling the second power tube and the third power tube to be turned on and the first power tube and the fourth power tube to be turned off according to the number of full-bridge sub-modules required to be put into operation in the bridge arm during the second modulation period, and putting the full-bridge sub-module into operation, comprises: When the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are put into operation; wherein H=NM; When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

10. The modulation method according to claim 9, characterized in that: When the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, putting in H full-bridge sub-modules comprises: If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the first cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation; If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the first cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation; The full-bridge submodule in the first cut-off state is used to indicate a full-bridge submodule in which the first power tube and the third power tube are both turned on and the second power tube and the fourth power tube are both turned off.

11. The modulation method according to claim 10, characterized in that: When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation amount of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module, comprising: If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitor voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitor voltage among the full-bridge sub-modules in the first cut-off state is put into operation; If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the first cut-off state is put into operation; The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

12. The modulation method according to claim 5, characterized in that: The method of controlling the second power tube and the fourth power tube to be turned on and controlling the first power tube and the third power tube to be turned off according to the number of full-bridge sub-modules required to be put into the bridge arm during the third modulation period, thereby removing the full-bridge sub-module, includes: When the number N of full-bridge submodules required to be put into operation in the bridge arm at the current moment is less than the number M of full-bridge submodules required to be put into operation in the bridge arm at the previous moment, H full-bridge submodules are removed; wherein H=MN; When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

13. The modulation method according to claim 12, characterized in that: When the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is less than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, removing H full-bridge sub-modules includes: If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted in ascending order of sub-module capacitor voltages; If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-module in the negative input state, which are sorted from large to small in terms of sub-module capacitor voltage; The full-bridge submodule in the negative input state is used to indicate the full-bridge submodule in which the second power tube and the third power tube are both turned on and the first power tube and the fourth power tube are both turned off.

14. The modulation method according to claim 13, characterized in that: When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation amount of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, removing one full-bridge sub-module and putting in another full-bridge sub-module, comprising: If the current of the bridge arm is greater than 0, the full-bridge sub-module with the smallest sub-module capacitor voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitor voltage among the full-bridge sub-modules in the second cut-off state is put into operation; If the current of the bridge arm is less than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the negative input state is cut off, the second power tube and the third power tube are controlled to be turned on, and the first power tube and the fourth power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation; The full-bridge submodule in the second cut-off state is used to indicate a full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

15. The modulation method according to claim 5, characterized in that: In the fourth modulation period, according to the number of full-bridge sub-modules required to be put into the bridge arm, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-modules are put into use, including: When the number N of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment, H full-bridge sub-modules are put into operation; wherein H=NM; When the number of full-bridge sub-modules required to be put into operation in the bridge arm at the current moment is equal to the number of full-bridge sub-modules required to be put into operation in the bridge arm at the previous moment and the voltage fluctuation of the sub-module capacitor in the full-bridge sub-module is greater than a preset fluctuation threshold, one full-bridge sub-module is removed and another full-bridge sub-module is put into operation.

16. The modulation method according to claim 15, characterized in that: When the number N of full-bridge sub-modules required to be put into the bridge arm at the current moment is greater than the number M of full-bridge sub-modules required to be put into the bridge arm at the previous moment, putting in H full-bridge sub-modules comprises: If the current of the bridge arm is greater than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from small to large, are put into operation; If the current of the bridge arm is less than 0, the first H full-bridge sub-modules in the full-bridge sub-modules in the second cut-off state, whose sub-module capacitor voltages are sorted from large to small, are put into operation; The full-bridge submodule in the second cut-off state is used to indicate a full-bridge submodule in which the second power tube and the fourth power tube are both turned on and the first power tube and the third power tube are both turned off.

17. The modulation method according to claim 16, characterized in that: The method of removing a full-bridge submodule and putting in a new full-bridge submodule when the number of the put-in-place full-bridge submodules is equal to the number of full-bridge submodules that the bridge arm needs to put in at the previous moment and the voltage fluctuation of the submodule capacitor in the full-bridge submodule is greater than a preset fluctuation threshold comprises: If the current of the bridge arm is greater than 0, the full-bridge sub-module with the largest sub-module capacitance voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the smallest sub-module capacitance voltage among the full-bridge sub-modules in the second cut-off state is put into operation; If the current of the bridge arm is less than 0, the full-bridge sub-module with the smallest sub-module capacitor voltage among the full-bridge sub-modules in the positive input state is cut off, the first power tube and the fourth power tube are controlled to be turned on, and the second power tube and the third power tube are controlled to be turned off, and the full-bridge sub-module with the largest sub-module capacitor voltage among the full-bridge sub-modules in the second cut-off state is put into operation; The full-bridge submodule in the positive input state is used to indicate a full-bridge submodule in which the first power tube and the fourth power tube are both turned on and the second power tube and the third power tube are both turned off.

18. A full-bridge submodule loss balancing modulation device, characterized in that: include: A determination module is used to determine the number of full-bridge sub-modules required for the bridge arm according to the modulation voltage of the bridge arm; A division module, configured to divide a modulation period into a plurality of modulation time periods according to the modulation voltage; The modulation module is used to balance the loss of the full-bridge sub-modules in each modulation period of the multiple modulation periods according to the number of full-bridge sub-modules required to be invested in the bridge arm.

19. A computer device, characterized in that: include: one or more processors; The processor is configured to store one or more programs; When the one or more programs are executed by the one or more processors, the modulation method according to any one of claims 1 to 17 is implemented.

20. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the modulation method according to any one of claims 1 to 17 is implemented.

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