Two-degree-of-freedom fundamental frequency modulation method and device for multi-level current source converter

Abstract

The invention provides a two-degree-of-freedom fundamental frequency modulation method and device of a multi-level current source converter. And triggering each bridge arm in the multi-level current source converter by adopting a fundamental frequency modulation mode according to a preset first degree of freedom and a preset second degree of freedom under the condition that the terminal voltage of the U-phase filter capacitor has a zero crossing point moment. On the basis of the first degree of freedom and the second degree of freedom, the switching speed of a semiconductor device on a bridge arm in the multi-level current source converter can be reduced by adopting a fundamental frequency modulation mode, and the harmonic quality of the multi-level current source converter is greatly improved, so that the operation loss of the multi-level current source converter is reduced, and the service life of the multi-level current source converter is prolonged. And the sampling cost and the control cost of the sensor are reduced. The multi-level current source converter can realize decoupling of voltage and power, so that the operation of the multi-level current source converter is more flexible and efficient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and in particular to a double-freedom fundamental frequency modulation method and device for a multilevel current source converter. BACKGROUND

[0002] A converter can include a voltage source converter (VSC) and a current source converter (CSC). Compared with a voltage source converter, a current source converter has advantages such as AC side voltage boosting, short circuit resistance, and direct current control. Therefore, a current source converter has been studied and applied to a certain extent in motor speed regulation, photovoltaic power generation, wind power generation, and the like.

[0003] A multilevel current source converter (MCSC) has advantages such as small switching stress of semiconductor devices, large output capacity, and small harmonic content of output waveform, and is particularly suitable for low-voltage and large-current scenarios. In a large-scale renewable energy collection and networking scenario, since the collection voltage is low and the collection capacity is large, a multilevel current source converter is more suitable for application.

[0004] Related technologies usually implement modulation of a multilevel current source converter in a carrier phase-shifted pulse width modulation (i.e., PWM modulation) manner. Specifically, a plurality of high-frequency carriers and a modulation wave are compared to generate a corresponding high-frequency modulation signal, and then the high-frequency modulation signal is used to control the action of semiconductor devices in the multilevel current source converter. However, the modulation method provided by related technologies has a high requirement for the switching speed of semiconductor devices, resulting in high operating loss of the multilevel current source converter and high cost of sampling and control of sensors. SUMMARY

[0005] To solve the problems of high operating loss and high sampling and control cost in the prior art, the present application provides a double-freedom fundamental frequency modulation method for a multilevel current source converter, which can include:

[0006] Dividing an output period of the multilevel current source converter into a plurality of working periods.

[0007] Collecting an end voltage of a U-phase filter capacitor in the multilevel current source converter.

[0008] In a case where the end voltage of the U-phase filter capacitor appears a zero-crossing point, triggering each bridge arm in the multilevel current source converter according to a preset first freedom and a preset second freedom and using a fundamental frequency modulation manner.

[0009] The first degree of freedom is used to indicate an electrical angle between a starting moment of an output period and a moment when the terminal voltage of the U-phase filter capacitor crosses zero, and the second degree of freedom is used to indicate half of a shoot-through time corresponding to a shoot-through state, and the shoot-through state is used to indicate that the output currents of the U-phase, the V-phase and the W-phase of the multi-level current source converter are all 0.

[0010] In some possible implementation manners, in the case that the terminal voltage of the U-phase filter capacitor crosses zero, each bridge arm in the multi-level current source converter is triggered according to the preset first degree of freedom and the preset second degree of freedom and by using a fundamental frequency modulation mode, including:

[0011] In the case that the terminal voltage of the U-phase filter capacitor crosses zero from a negative voltage to a positive voltage, a first working period in the plurality of working periods is delayed by the first degree of freedom, and each bridge arm is triggered according to the second degree of freedom and by using the fundamental frequency modulation mode.

[0012] Exemplarily, the multi-level current source converter includes a power electronic converter and a filter.

[0013] The power electronic converter includes a three-phase current source converter. The filter includes a U-phase filter capacitor, a V-phase filter capacitor and a W-phase filter capacitor.

[0014] The first ends of the three-phase current source converters are connected in parallel to form a first direct current end of the power electronic converter. The second ends of the three-phase current source converters are connected in parallel to form a second direct current end of the power electronic converter. The first direct current end and the second direct current end form a direct current side of the multi-level current source converter. An alternating current side of the power electronic converter is connected to the first ends of the U-phase filter capacitor, the V-phase filter capacitor and the W-phase filter capacitor, and the second ends of the U-phase filter capacitor, the V-phase filter capacitor and the W-phase filter capacitor form the alternating current side of the multi-level current source converter.

[0015] Optionally, each phase current source converter in the three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm and a sixth bridge arm.

[0016] The first bridge arm and the fourth bridge arm are connected in series to form a first branch. The fifth bridge arm and the second bridge arm are connected in series to form a second branch. The third bridge arm and the sixth bridge arm are connected in series to form a third branch. The first branch, the second branch and the third branch are connected in parallel.

[0017] Exemplarily, triggering each bridge arm according to the second degree of freedom includes:

[0018] The second bridge arm and the third bridge arm of each three-phase current source converter are triggered to be turned on and to last for a working period, so that U = 0, I V = -I dc , I W= I dc . Wherein, I U represents the output current of U phase, I V represents the output current of V phase, I W represents the output current of W phase, I dc represents the DC side current of multi-level current source converter.

[0019] The first bridge arm of the A phase current source converter in the three-phase current source converter, the second bridge arm of the three-phase current source converter, and the third bridge arm of the B phase current source converter and the C phase current source converter in the three-phase current source converter are triggered to be turned on and last for one working period, so that I U = I dc / 3, I V =-I dc , I W =2I dc / 3; and the other bridge arms in the three-phase current source converter can also be triggered to be turned off.

[0020] The second bridge arm and the fifth bridge arm of the three-phase current source converter are triggered to be turned on and last for a through time, so that I U =0, I V =0, I W =0; and the other bridge arms in the three-phase current source converter can also be triggered to be turned off.

[0021] The first bridge arm of the A phase current source converter and the B phase current source converter, the second bridge arm of the three-phase current source converter, and the third bridge arm of the C phase current source converter are triggered to be turned on and last for one working period, so that I U =2I dc / 3, I V =-I dc , I W =I dc / 3; and the other bridge arms in the three-phase current source converter can also be triggered to be turned off.

[0022] The first bridge arm and the second bridge arm of the three-phase current source converter are triggered to be turned on and last for one working period, so that I U =I dc , I V =-I dc , I W =0; and the other bridge arms in the three-phase current source converter can also be triggered to be turned off.

[0023] The first bridge arm of the A phase current source converter and the B phase current source converter, the second bridge arm of the A phase current source converter and the B phase current source converter, and the first bridge arm and the sixth bridge arm of the C phase current source converter are triggered to be turned on and last for one working period, so that I U =I dc , IV =-2I dc / 3, I W =-I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0024] Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0025] This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc / 3, I W =-2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0026] This triggers the first and sixth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =0, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0027] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0028] Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0029] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0030] This triggers the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =I dc I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0031] This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0032] The fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter are triggered to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0033] This triggers the fourth and fifth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0034] This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0035] This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0036] This triggers the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =-I dc I V =0, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0037] This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0038] This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0039] Optionally, the through time is used to indicate the time range between the start and end times of the through state of the bridge arm. Where the start time is t. maxh -θ, ending at time t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W; θ represents the second degree of freedom.

[0040] As can be seen, this application achieves fundamental frequency modulation of the multilevel current source converter through the first and second degrees of freedom, which reduces the switching speed of semiconductor devices on the bridge arm of the multilevel current source converter, thereby reducing the operating loss of the converter and reducing the cost of sensor sampling and control.

[0041] On the other hand, this application provides a two-degree-of-freedom fundamental frequency modulation device for a multi-level current source converter, which may include:

[0042] The partitioning module is used to divide the output cycle of a multilevel current source converter into multiple operating cycles.

[0043] The acquisition module is used to acquire the terminal voltage of the U-phase filter capacitor in the multi-level current source converter.

[0044] The trigger module is used to trigger each bridge arm in the multi-level current source converter according to the preset first degree of freedom and the preset second degree of freedom when the terminal voltage of the U-phase filter capacitor crosses zero.

[0045] The first degree of freedom indicates the electrical angle difference between the start of the output cycle and the zero-crossing point of the voltage across the U-phase filter capacitor. The second degree of freedom indicates half the shoot-through time corresponding to the bridge arm shoot-through state. The bridge arm shoot-through state indicates that the output currents of the U-phase, V-phase, and W-phase of the multi-level current source converter are all zero.

[0046] Optionally, the multilevel current source converter includes a power electronic converter and filters. The power electronic converter includes a three-phase current source converter. The filters include U-phase filter capacitors, V-phase filter capacitors, and W-phase filter capacitors.

[0047] The first terminals of each of the three-phase current source converters are connected in parallel to form the first DC terminal of the power electronic converter. The second terminals of each of the three-phase current source converters are connected in parallel to form the second DC terminal of the power electronic converter. The first and second DC terminals constitute the DC side of the multilevel current source converter. The AC side of the power electronic converter is connected to the first terminals of the U-phase filter capacitor, V-phase filter capacitor, and W-phase filter capacitor, respectively. The second terminals of the U-phase filter capacitor, V-phase filter capacitor, and W-phase filter capacitor constitute the AC side of the multilevel current source converter.

[0048] For example, each phase current source converter in a three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm.

[0049] The first bridge arm and the fourth bridge arm are connected in series to form the first branch. The fifth bridge arm and the second bridge arm are connected in series to form the second branch. The third bridge arm and the sixth bridge arm are connected in series to form the third branch. The first, second, and third branches are connected in parallel.

[0050] In one possible implementation, the trigger module is used to:

[0051] When the terminal voltage of the U-phase filter capacitor reaches the zero-crossing point from negative to positive, the first working cycle of multiple working cycles is delayed by the first degree of freedom, and each bridge arm is triggered according to the second degree of freedom.

[0052] Furthermore, the trigger module is specifically used for:

[0053] This triggers the second and third bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =0, I V =-I dc I W =I dc Among them, I U I represents the output current of phase U. V I represents the output current of phase V. W I represents the output current of phase W. dc This represents the DC-side current of a multilevel current source converter.

[0054] The first bridge arm of phase A current source converter, the second bridge arm of each of the three phase current source converters, and the third bridge arm of each of the phase B and phase C current source converters in the three-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc / 3, I V =-I dc I W =2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0055] Trigger the second and fifth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0056] This triggers the first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =-I dc I W =I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0057] This triggers the first and second bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =-I dc I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0058] The first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the A-phase and B-phase current source converters, and the first and sixth bridge arms of the C-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc I V =-2I dc / 3, I W =-I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0059] Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0060] This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc / 3, I W =-2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0061] This triggers the first and sixth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =Idc I V =0, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0062] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0063] Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0064] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0065] This triggers the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =I dc I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0066] This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0067] The fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter are triggered to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0068] This triggers the fourth and fifth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc I W =0; it can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0069] This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0070] This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3; It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0071] This triggers the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =-I dc I V =0, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0072] This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0073] This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0074] Optionally, the through time is used to indicate the time range between the start and end times of the through state of the bridge arm. Where the start time is t. maxh -θ, ending at time t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W; θ represents the second degree of freedom.

[0075] In another aspect, this application also provides a computer device, including: one or more processors.

[0076] A processor is used to execute one or more programs.

[0077] When one or more programs are executed by one or more processors, the modulation method described above is implemented.

[0078] Furthermore, this application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, it implements the modulation method described above.

[0079] Compared with the prior art, the beneficial effects of this application are as follows:

[0080] The dual-degree-of-freedom fundamental frequency modulation method for multilevel current source converters provided in this application divides the output cycle of the multilevel current source converter into multiple operating cycles. The terminal voltage of the U-phase filter capacitor in the multilevel current source converter is acquired. When the terminal voltage of the U-phase filter capacitor crosses zero, each bridge arm in the multilevel current source converter is triggered using fundamental frequency modulation based on a preset first degree of freedom and a preset second degree of freedom. Based on the first and second degrees of freedom, the fundamental frequency modulation method in this application can reduce the switching speed of semiconductor devices on the bridge arms of the multilevel current source converter, significantly improving the harmonic quality of the multilevel current source converter, thereby reducing the operating losses of the multilevel current source converter and lowering the sampling and control costs of the sensors.

[0081] The dual-degree-of-freedom fundamental frequency modulation method provided in this application does not have a synchronous triggering problem, does not require additional circulating current suppression control, and reduces the control cost of multi-level current source converters.

[0082] In the dual-degree-of-freedom fundamental frequency modulation method provided in this application, the terminal voltage of the U-phase filter capacitor and the output current waveform of the U-phase can both be stepped waves, which can realize decoupled control of voltage and power, making the operation of the multi-level current source converter more flexible and efficient. Attached Figure Description

[0083] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0084] Figure 1 This is a schematic structural diagram of a multilevel current source converter in an embodiment of this application;

[0085] Figure 2 This is a schematic flowchart of a dual-degree-of-freedom fundamental frequency modulation method for a multi-level current source converter in this application embodiment;

[0086] Figure 3 This is a schematic diagram of the duty cycle of a multilevel current source converter in an embodiment of this application;

[0087] Figure 4 The waveforms of the terminal voltage of the U-phase filter capacitor and the U-phase output current in the embodiments of this application are shown.

[0088] Figure 5 This is a schematic diagram of the trigger signal for bridge arm A1 in an embodiment of this application;

[0089] Figure 6This is a schematic structural diagram of a dual-degree-of-freedom fundamental frequency modulation device for a multi-level current source converter in an embodiment of this application. Detailed Implementation

[0090] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0091] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including 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 these processes, methods, products, or apparatuses.

[0092] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0093] Example 1:

[0094] This application provides a two-degree-of-freedom fundamental frequency modulation method for a multi-level current source converter. For example... Figure 1 As shown, the multilevel current source converter 100 may include a power electronic converter 10 and a filter 20.

[0095] Optionally, the power electronic converter 10 includes a three-phase current source converter. The three-phase current source converter may include an A-phase current source converter 1, a B-phase current source converter 2, and a C-phase current source converter 3. The filter 20 includes a U-phase filter capacitor C. U V-phase filter capacitor C V and W-phase filter capacitor C W Of course, for reference Figure 1 The filter 20 may also include a U-phase filter inductor L. U V-phase filter inductor L Vand W-phase filter inductor L W .

[0096] The first terminals of each of the three-phase current source converters are connected in parallel to form the first DC terminal DC1 of the power electronic converter 10. The second terminals of each of the three-phase current source converters are connected in parallel to form the second DC terminal DC2 of the power electronic converter 10. The first DC terminal DC1 and the second DC terminal DC2 constitute the DC side of the multi-level current source converter 100. The AC side of the power electronic converter 10 is connected to the U-phase filter capacitor C. U V-phase filter capacitor C V and W-phase filter capacitor C W Their respective first terminals are connected, U-phase filter capacitor C U V-phase filter capacitor C V and W-phase filter capacitor C W Each of their second terminals constitutes the AC side of the multilevel current source converter 100.

[0097] Optionally, each phase current source converter in the three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm. The first bridge arm and the fourth bridge arm are connected in series to form the first branch. The fifth bridge arm and the second bridge arm are connected in series to form the second branch. The third bridge arm and the sixth bridge arm are connected in series to form the third branch. The first branch, the second branch, and the third branch are connected in parallel.

[0098] refer to Figure 1 The A-phase current source converter 1 may include bridge arms A1 (i.e., the first bridge arm), A2 (i.e., the second bridge arm), A3 (i.e., the third bridge arm), A4 (i.e., the fourth bridge arm), A5 (i.e., the fifth bridge arm), and A6 (i.e., the sixth bridge arm). Bridge arms A1 and A4 are connected in series to form the first branch of the A-phase current source converter 1. Bridge arms A5 and A2 are connected in series to form the second branch of the A-phase current source converter 1. Bridge arms A3 and A6 are connected in series to form the third branch of the A-phase current source converter 1. The first branch, the second branch, and the third branch of the A-phase current source converter 1 are connected in parallel. Of course, the A-phase current source converter 1 may also include an inductor L. A1 and inductor L A2 Inductor L A1 It can be connected between the first DC terminal DC1 and node E1. Inductor L A2 It can be connected between the second DC terminal DC2 and node E2.

[0099] The B-phase current source converter 2 may include bridge arms B1 (first bridge arm), B2 (second bridge arm), B3 (third bridge arm), B4 (fourth bridge arm), B5 (fifth bridge arm), and B6 (sixth bridge arm). Bridge arms B1 and B4 are connected in series, forming the first branch of the B-phase current source converter 2. Bridge arms B5 and B2 are connected in series, forming the second branch of the B-phase current source converter 2. Bridge arms B3 and B6 are connected in series, forming the third branch of the B-phase current source converter 2. The first, second, and third branches of the B-phase current source converter 2 are connected in parallel. Of course, the B-phase current source converter 2 may also include an inductor L. B1 and inductor L B2 Inductor L B1 It can be connected between the first DC terminal DC1 and node F1. Inductor L B2 It can be connected between the second DC terminal DC2 and node F2.

[0100] The C-phase current source converter 3 may include bridge arms C1 (first bridge arm), C2 (second bridge arm), C3 (third bridge arm), C4 (fourth bridge arm), C5 (fifth bridge arm), and C6 (sixth bridge arm). Bridge arms C1 and C4 are connected in series, forming the first branch of the C-phase current source converter 3. Bridge arms C5 and C2 are connected in series, forming the second branch of the C-phase current source converter 3. Bridge arms C3 and C6 are connected in series, forming the third branch of the C-phase current source converter 3. The first, second, and third branches of the C-phase current source converter 3 are connected in parallel. Of course, the C-phase current source converter 3 may also include an inductor L. C1 and inductor L C2 Inductor L C1 It can be connected between the first DC terminal DC1 and node G1. Inductor L C2 It can be connected between the second DC terminal DC2 and node G2.

[0101] like Figure 2 As shown, modulation method 200 may include the following steps:

[0102] Step S1: Divide the output cycle of the multi-level current source converter 100 into multiple working cycles.

[0103] Step S2: Acquire the terminal voltage of the U-phase filter capacitor in the multi-level current source converter 100 (using u... CU express).

[0104] Step S3: The terminal voltage u of the U-phase filter capacitor CUIn the event of a zero point, each bridge arm of the multi-level current source converter 100 is triggered according to the preset first degree of freedom α and the preset second degree of freedom θ, and using the base frequency modulation method.

[0105] The first degree of freedom, α, indicates the electrical angle difference between the start of the output cycle and the zero-crossing point of the terminal voltage of the U-phase filter capacitor. The second degree of freedom, θ, indicates half the shoot-through time corresponding to the bridge arm shoot-through state, which indicates that the output currents of the U-phase, V-phase, and W-phase of the multi-level current source converter are all zero, i.e., I... U =0, I V =0, I W =0. I U I represents the output current of phase U. V I represents the output current of phase V. W This indicates the output current of phase W.

[0106] Optionally, in step S1, the output cycle (360 electrical degrees) of the multi-level current source converter 100 can be divided into 36 operating cycles, each operating cycle being 10 electrical degrees, such as... Figure 3 As shown. Figure 3 In this context, t represents time, ω represents angular frequency, and I represents... dc This represents the DC-side current of a multilevel current source converter.

[0107] In some embodiments, in step S2, the terminal voltage u of the U-phase filter capacitor... CU and U-phase output current I U The waveform diagram is as follows Figure 4 As shown. Figure 4 In this context, t represents time, and ω represents angular frequency.

[0108] In other embodiments, in step S3 above, the terminal voltage u of the U-phase filter capacitor... CU In the event of a zero-point occurrence, each bridge arm of the multi-level current source converter 100 is triggered according to a preset first degree of freedom α and a preset second degree of freedom θ, using a fundamental frequency modulation method. Specifically, this may include:

[0109] The terminal voltage u of the U-phase filter capacitor CU When a zero-crossing moment occurs, from negative voltage to positive voltage, the first working cycle of multiple working cycles is delayed by the first degree of freedom α, and each bridge arm is triggered according to the second degree of freedom θ and using the fundamental frequency modulation method.

[0110] Optionally, each bridge arm is triggered based on the second degree of freedom θ, including:

[0111] This triggers the second and third bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I...U =0, I V =-I dc I W =I dc Among them, I U I represents the output current of phase U. V I represents the output current of phase V. W I represents the output current of phase W. dc This represents the DC-side current of the multi-level current source converter. In other words, it can trigger bridge arms A3, A2, B3, B2, C2, and C3 to conduct and remain on for one duty cycle, causing I... U =0, I V =-I dc I W =I dc This triggers the shutdown of other bridge arms in the three-phase current source converter.

[0112] The first bridge arm of phase A current source converter, the second bridge arm of each of the three phase current source converters, and the third bridge arm of each of the phase B and phase C current source converters in the three-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc / 3, I V =-I dc I W =2I dc / 3. That is, it can trigger bridge arms A1, A2, B3, C2, and C3 to conduct and remain so for one working cycle, making I... U =I dc / 3, I V =-I dc I W =2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0113] Trigger the second and fifth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0. That is, it can trigger bridge arms A5, A2, B5, B2, C2, and C5 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0114] This triggers the first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =-I dc I W =I dc / 3. That is, it can trigger bridge arms A1, A2, B1, B2, C2, and C3 to conduct and remain so for one working cycle, making I... U =2I dc / 3, I V =-I dc I W =I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0115] This triggers the first and second bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =-I dc I W =0. That is, it can trigger bridge arms A1, A2, B1, B2, C2, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-I dc I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0116] The first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the A-phase and B-phase current source converters, and the first and sixth bridge arms of the C-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc I V =-2I dc / 3, I W =-I dc / 3. That is, it can trigger bridge arms A1, A2, B1, B2, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-2I dc / 3, I W =-I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0117] Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0. That is, it can trigger bridge arms A1, A4, B1, B4, C4, and C1 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0118] This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc / 3, I W =-2I dc / 3. That is, it can trigger bridge arms A1, A6, B1, B2, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-I dc / 3, I W =-2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0119] This triggers the first and sixth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =0, I W =-I dc In other words, it can trigger bridge arms A1, A6, B1, B6, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =0, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0120] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2Idc / 3, I V =I dc / 3, I W =-I dc In other words, it can trigger bridge arms A1, A6, B5, B6, C6, and C1, turning them on and maintaining them for one working cycle, thus enabling I... U =2I dc / 3, I V =I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0121] Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0. That is, it can trigger bridge arms A3, A6, B3, B6, C6, and C3 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0122] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc In other words, it can trigger bridge arms A1, A6, B5, B6, C6, and C5 to conduct and remain so for one working cycle, making I... U =I dc / 3, I V =2I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0123] This triggers the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =I dc I W =-I dcIn other words, it can trigger bridge arms A5, A6, B5, B6, C6, and C5 to conduct and remain so for one working cycle, enabling I... U =0, I V =I dc I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0124] This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3. That is, it can trigger bridge arms A5, A4, B5, B6, C6, and C5 to conduct and remain so for one working cycle, making I... U =-I dc / 3, I V =I dc I W =-2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0125] The fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter are triggered to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3. That is, it can trigger bridge arms A5, A4, B5, C6, and C5 to conduct and remain so for one working cycle, making I... U =-2I dc / 3, I V =I dc I W =-I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0126] This triggers the fourth and fifth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc IW =0. That is, it can trigger A5A4-B5B4-C4C5 to conduct and remain so for one working cycle, making I... U =-I dc I V =I dc I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0127] This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3. In other words, it can trigger A5A4-B5B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =2I dc / 3, I W =I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0128] This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3. In other words, it can trigger A3A4-B5B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =I dc / 3, I W =2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0129] This triggers the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =-I dc I V =0, I W =I dcIn other words, it can trigger A3A4-B3B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =0, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0130] This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc In other words, it can trigger A3A4-B3B2-C4C3 to conduct and remain so for one working cycle, making I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0131] This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc In other words, it can trigger A3A4-B3B2-C2C3 to conduct and remain so for one working cycle, making I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0132] Optionally, the through time is used to indicate the time range between the start and end times of the through state of the bridge arm. Where the start time is t. maxh -θ, ending at time t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W, and θ represents the second degree of freedom.

[0133] It can be understood that the turn-off of the other arm can specifically be a blocking trigger signal to keep the other arm turned off or switch it to the turn-off state.

[0134] In the case where the output period (360 electrical degrees) is evenly divided into 36 working cycles, within each output period, the output current I of phase U U and the output current I of phase V V and the output current I of phase W W and the conduction condition of the arm can be as shown in Table 1:

[0135] Table 1

[0136]

[0137]

[0138]

[0139] In Table 1, V_direct represents the direct-conduction continuous electrical angle of phase V (i.e., the fifth arm and the second arm of each of the A-phase current source converter, B-phase current source converter, and C-phase current source converter). U_direct represents the direct-conduction continuous electrical angle of phase U (i.e., the first arm and the fourth arm of each of the A-phase current source converter, B-phase current source converter, and C-phase current source converter). W_direct represents the direct-conduction continuous electrical angle of phase W (i.e., the third arm and the sixth arm of each of the A-phase current source converter, B-phase current source converter, and C-phase current source converter). The direct-conduction continuous electrical angle can be 2θ.

[0140] In the embodiment of the present application, within one output period, the trigger signal of arm A1 generated according to Table 1 can be referred to Figure 5 . Figure 5 In, G A1 represents the trigger signal of arm A1.

[0141] Embodiment 2:

[0142] Based on the same inventive concept, the embodiment of the present application further provides a two-degree-of-freedom fundamental frequency modulation device for a multilevel current source converter as shown in Figure 6 . The modulation device 300 can include:

[0143] The dividing module 301 is used to divide the output period of the multilevel current source converter into multiple working cycles.

[0144] [[ID=四十八]] [[ID=四十九]]

[0145] The acquisition module 302 is used to acquire the terminal voltage of the filter capacitor of phase U in the multilevel current source converter.Trigger module 303 is used to trigger each bridge arm in the multi-level current source converter according to a preset first degree of freedom and a preset second degree of freedom when the terminal voltage of the U-phase filter capacitor crosses zero.

[0146] The first degree of freedom indicates the electrical angle difference between the start of the output cycle and the zero-crossing point of the terminal voltage of the U-phase filter capacitor. The second degree of freedom indicates half of the shoot-through time corresponding to the bridge arm shoot-through state. The bridge arm shoot-through state indicates that the output current of each of the U-phase, V-phase, and W-phase of the multi-level current source converter 100 is 0.

[0147] refer to Figure 1 The multilevel current source converter 100 may include a power electronic converter 10 and a filter 20.

[0148] Optionally, the power electronic converter 10 includes a three-phase current source converter. The three-phase current source converter may include an A-phase current source converter 1, a B-phase current source converter 2, and a C-phase current source converter 3. The filter 20 includes a U-phase filter capacitor C. U V-phase filter capacitor C V and W-phase filter capacitor C W Of course, for reference Figure 1 The filter 20 may also include a U-phase filter inductor L. U V-phase filter inductor L V and W-phase filter inductor L W .

[0149] The first terminals of each of the three-phase current source converters are connected in parallel to form the first DC terminal DC1 of the power electronic converter 10. The second terminals of each of the three-phase current source converters are connected in parallel to form the second DC terminal DC2 of the power electronic converter 10. The first DC terminal DC1 and the second DC terminal DC2 constitute the DC side of the multi-level current source converter 100. The AC side of the power electronic converter 10 is connected to the U-phase filter capacitor C. U V-phase filter capacitor C V and W-phase filter capacitor C W Their respective first terminals are connected, U-phase filter capacitor C U V-phase filter capacitor C V and W-phase filter capacitor C W Each of their second terminals constitutes the AC side of the multilevel current source converter 100.

[0150] Optionally, each phase current source converter in the three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm. The first bridge arm and the fourth bridge arm are connected in series to form the first branch. The fifth bridge arm and the second bridge arm are connected in series to form the second branch. The third bridge arm and the sixth bridge arm are connected in series to form the third branch. The first branch, the second branch, and the third branch are connected in parallel.

[0151] refer to Figure 1 The A-phase current source converter 1 may include bridge arms A1 (i.e., the first bridge arm), A2 (i.e., the second bridge arm), A3 (i.e., the third bridge arm), A4 (i.e., the fourth bridge arm), A5 (i.e., the fifth bridge arm), and A6 (i.e., the sixth bridge arm). Bridge arms A1 and A4 are connected in series to form the first branch of the A-phase current source converter 1. Bridge arms A5 and A2 are connected in series to form the second branch of the A-phase current source converter 1. Bridge arms A3 and A6 are connected in series to form the third branch of the A-phase current source converter 1. The first branch, the second branch, and the third branch of the A-phase current source converter 1 are connected in parallel. Of course, the A-phase current source converter 1 may also include an inductor L. A1 and inductor L A2 Inductor L A1 It can be connected between the first DC terminal DC1 and node E1. Inductor L A2 It can be connected between the second DC terminal DC2 and node E2.

[0152] The B-phase current source converter 2 may include bridge arms B1 (first bridge arm), B2 (second bridge arm), B3 (third bridge arm), B4 (fourth bridge arm), B5 (fifth bridge arm), and B6 (sixth bridge arm). Bridge arms B1 and B4 are connected in series, forming the first branch of the B-phase current source converter 2. Bridge arms B5 and B2 are connected in series, forming the second branch of the B-phase current source converter 2. Bridge arms B3 and B6 are connected in series, forming the third branch of the B-phase current source converter 2. The first, second, and third branches of the B-phase current source converter 2 are connected in parallel. Of course, the B-phase current source converter 2 may also include an inductor L. B1 and inductor L B2 Inductor L B1 It can be connected between the first DC terminal DC1 and node F1. Inductor L B2 It can be connected between the second DC terminal DC2 and node F2.

[0153] The C-phase current source converter 3 may include bridge arms C1 (first bridge arm), C2 (second bridge arm), C3 (third bridge arm), C4 (fourth bridge arm), C5 (fifth bridge arm), and C6 (sixth bridge arm). Bridge arms C1 and C4 are connected in series, forming the first branch of the C-phase current source converter 3. Bridge arms C5 and C2 are connected in series, forming the second branch of the C-phase current source converter 3. Bridge arms C3 and C6 are connected in series, forming the third branch of the C-phase current source converter 3. The first, second, and third branches of the C-phase current source converter 3 are connected in parallel. Of course, the C-phase current source converter 3 may also include an inductor L. C1 and inductor L C2 Inductor L C1 It can be connected between the first DC terminal DC1 and node G1. Inductor L C2 It can be connected between the second DC terminal DC2 and node G2.

[0154] In one possible implementation, the trigger module 303 can be used to:

[0155] When the terminal voltage of the U-phase filter capacitor reaches the zero-crossing point from negative to positive, the first working cycle of multiple working cycles is delayed by the first degree of freedom, and each bridge arm is triggered according to the second degree of freedom.

[0156] Furthermore, the trigger module 303 is specifically used for:

[0157] This triggers the second and third bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =0, I V =-I dc I W =I dc Among them, I U I represents the output current of phase U. V I represents the output current of phase V. W I represents the output current of phase W. dc This represents the DC-side current of the multi-level current source converter. In other words, it can trigger bridge arms A3, A2, B3, B2, C2, and C3 to conduct and remain on for one duty cycle, causing I... U =0, I V =-I dc I W =I dc This triggers the shutdown of other bridge arms in the three-phase current source converter.

[0158] The first bridge arm of phase A current source converter, the second bridge arm of each of the three phase current source converters, and the third bridge arm of each of the phase B and phase C current source converters in the three-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc / 3, I V =-I dc I W =2I dc / 3. That is, it can trigger bridge arms A1, A2, B3, C2, and C3 to conduct and remain so for one working cycle, making I... U =I dc / 3, I V =-I dc I W =2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0159] Trigger the second and fifth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0. That is, it can trigger bridge arms A5, A2, B5, B2, C2, and C5 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0160] This triggers the first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =-I dc I W =I dc / 3. That is, it can trigger bridge arms A1, A2, B1, B2, C2, and C3 to conduct and remain so for one working cycle, making I... U =2I dc / 3, I V =-I dc I W =I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0161] This triggers the first and second bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =-I dc I W =0. That is, it can trigger bridge arms A1, A2, B1, B2, C2, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-I dc I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0162] The first bridge arm of each of the A-phase and B-phase current source converters, the second bridge arm of each of the A-phase and B-phase current source converters, and the first and sixth bridge arms of the C-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =I dc I V =-2I dc / 3, I W =-I dc / 3. That is, it can trigger bridge arms A1, A2, B1, B2, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-2I dc / 3, I W =-I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0163] Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0. That is, it can trigger bridge arms A1, A4, B1, B4, C4, and C1 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0164] This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc IV =-I dc / 3, I W =-2I dc / 3. That is, it can trigger bridge arms A1, A6, B1, B2, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =-I dc / 3, I W =-2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0165] This triggers the first and sixth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =I dc I V =0, I W =-I dc In other words, it can trigger bridge arms A1, A6, B1, B6, C6, and C1 to conduct and remain so for one working cycle, making I... U =I dc I V =0, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0166] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =I dc / 3, I W =-I dc In other words, it can trigger bridge arms A1, A6, B5, B6, C6, and C1, turning them on and maintaining them for one working cycle, thus enabling I... U =2I dc / 3, I V =I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0167] Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W=0. That is, it can trigger bridge arms A3, A6, B3, B6, C6, and C3 to conduct and maintain the shoot-through time, making I... U =0, I V =0, I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0168] This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc In other words, it can trigger bridge arms A1, A6, B5, B6, C6, and C5 to conduct and remain so for one working cycle, making I... U =I dc / 3, I V =2I dc / 3, I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0169] This triggers the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =I dc I W =-I dc In other words, it can trigger bridge arms A5, A6, B5, B6, C6, and C5 to conduct and remain so for one working cycle, enabling I... U =0, I V =I dc I W =-I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0170] This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3. That is, it can trigger bridge arms A5, A4, B5, B6, C6, and C5 to conduct and remain so for one working cycle, making I... U =-I dc / 3, I V =I dc I W =-2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0171] The fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter are triggered to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3. That is, it can trigger bridge arms A5, A4, B5, C6, and C5 to conduct and remain so for one working cycle, making I... U =-2I dc / 3, I V =I dc I W =-I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0172] This triggers the fourth and fifth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc I W =0. That is, it can trigger A5A4-B5B4-C4C5 to conduct and remain so for one working cycle, making I... U =-I dc I V =I dc I W =0 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0173] This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3. In other words, it can trigger A5A4-B5B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =2I dc / 3, I W =I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0174] This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3. In other words, it can trigger A3A4-B5B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =I dc / 3, I W =2I dc / 3 can also trigger the shutdown of other bridge arms in the three-phase current source converter.

[0175] This triggers the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain so for one operating cycle, causing I... U =-I dc I V =0, I W =I dc In other words, it can trigger A3A4-B3B4-C4C3 to conduct and remain so for one working cycle, making I... U =-I dc I V =0, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0176] This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dcIn other words, it can trigger A3A4-B3B2-C4C3 to conduct and remain so for one working cycle, making I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0177] This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc In other words, it can trigger A3A4-B3B2-C2C3 to conduct and remain so for one working cycle, making I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc It can also trigger the shutdown of other bridge arms in a three-phase current source converter.

[0178] Optionally, the through time is used to indicate the time range between the start and end times of the through state of the bridge arm. Where the start time is t. maxh -θ, ending at time t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W, and θ represents the second degree of freedom.

[0179] Understandably, the aforementioned other bridge arm shutdown can specifically be a blocking trigger signal, causing other bridge arms to remain shut down or switch to the shut-down state.

[0180] Optionally, the through time is used to indicate the time range between the start and end times of the through state of the bridge arm. Where the start time is t. maxh -θ, ending at time t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W, and θ represents the second degree of freedom.

[0181] With the output cycle (360 electrical degrees) divided into 36 operating cycles, the output current I of phase U in each output cycle... U The output current I of phase V V The output current I of phase WW The continuity of the bridge arm can be referred to Table 1 above, and will not be repeated in the embodiments of this application.

[0182] Example 3:

[0183] Based on the same inventive concept, this application also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the modulation method provided in the above embodiments.

[0184] Example 4:

[0185] Based on the same inventive concept, this application also provides a storage medium, specifically a computer-readable storage medium (Memory). A computer-readable storage medium is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). 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 device. 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 embodiments.

[0186] Those skilled in the art will understand that the embodiments of the application can be provided as a method, system, or computer program product. Therefore, the application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0187] The application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0188] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0189] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0190] The above are merely examples 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 shall be included within the scope of the claims of the pending application.

Claims

1. A two-degree-of-freedom fundamental frequency modulation method for a multi-level current source converter, characterized in that, include: The output cycle of the multilevel current source converter is divided into multiple working cycles; The terminal voltage of the U-phase filter capacitor in the multi-level current source converter is collected; When the terminal voltage of the U-phase filter capacitor crosses zero, each bridge arm of the multi-level current source converter is triggered according to the preset first degree of freedom and the preset second degree of freedom, and using the base frequency modulation method. Wherein, the first degree of freedom is used to indicate the electrical angle difference between the start time of the output cycle and the time when the terminal voltage of the U-phase filter capacitor crosses zero; the second degree of freedom is used to indicate half of the shoot-through time corresponding to the bridge arm shoot-through state; the bridge arm shoot-through state is used to indicate that the output current of each of the U-phase, V-phase and W-phase of the multi-level current source converter is 0.

2. The modulation method according to claim 1, characterized in that, When the terminal voltage of the U-phase filter capacitor crosses zero, each bridge arm of the multi-level current source converter is triggered according to a preset first degree of freedom and a preset second degree of freedom, using a fundamental frequency modulation method, including: When the terminal voltage of the U-phase filter capacitor reaches a zero-crossing point from negative to positive, the first working cycle of the plurality of working cycles is delayed by the first degree of freedom, and each bridge arm is triggered according to the second degree of freedom and using a baseband modulation method.

3. The modulation method according to claim 2, characterized in that, The multilevel current source converter includes a power electronic converter and a filter; The power electronic converter includes a three-phase current source converter; the filter includes a U-phase filter capacitor, a V-phase filter capacitor, and a W-phase filter capacitor. The first terminals of each of the three-phase current source converters are connected in parallel to form the first DC terminal of the power electronic converter; the second terminals of each of the three-phase current source converters are connected in parallel to form the second DC terminal of the power electronic converter; the first DC terminal and the second DC terminal constitute the DC side of the multi-level current source converter; the AC side of the power electronic converter is connected to the first terminals of each of the U-phase filter capacitor, the V-phase filter capacitor, and the W-phase filter capacitor, and the second terminals of each of the U-phase filter capacitor, the V-phase filter capacitor, and the W-phase filter capacitor constitute the AC side of the multi-level current source converter.

4. The modulation method according to claim 3, characterized in that, Each phase current source converter in the three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm. The first bridge arm is connected in series with the fourth bridge arm to form the first branch; the fifth bridge arm is connected in series with the second bridge arm to form the second branch; the third bridge arm is connected in series with the sixth bridge arm to form the third branch; the first branch, the second branch and the third branch are connected in parallel.

5. The modulation method according to claim 4, characterized in that, The step of triggering each bridge arm according to the second degree of freedom and using a fundamental frequency modulation method includes: This triggers the second and third bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =-I dc I W =I dc Among them, I U I represents the output current of phase U. V I represents the output current of phase V. W I represents the output current of phase W. dc This represents the DC-side current of the multilevel current source converter; This triggers the first bridge arm of phase A current source converter, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of each of phase B and phase C current source converters in the three-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =-I dc I W =2I dc / 3; Trigger the second and fifth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; The first bridge arm of each of the A-phase current source converter and the B-phase current source converter, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of the C-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =2I dc / 3, I V =-I dc I W =I dc / 3; Triggering the first and second bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc I W =0; This triggers the first bridge arm of each of the A-phase current source converter and the B-phase current source converter, the second bridge arm of each of the A-phase current source converter and the B-phase current source converter, and the first and sixth bridge arms of the C-phase current source converter to conduct and remain on for one working cycle, causing I... U =I dc I V =-2I dc / 3, I W =-I dc / 3; Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc / 3, I W =-2I dc / 3; The first and sixth bridge arms of each of the three-phase current source converters are triggered to conduct and remain on for one operating cycle, causing I... U =I dc I V =0, I W =-I dc ; This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =I dc / 3, I W =-I dc ; Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc ; Trigger the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I U =0, I V =I dc I W =-I dc ; This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3; This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3; The fourth and fifth bridge arms of each of the three-phase current source converters are triggered to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc I W =0; This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3; This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3; Trigger the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I U =-I dc I V =0, I W =I dc ; This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc ; This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc ; The through time is used to indicate the time range between the start and end times of the through state of the bridge arm; the start time is t. maxh -θ, where the end time is t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W; θ represents the second degree of freedom.

6. A two-degree-of-freedom fundamental frequency modulation device for a multi-level current source converter, characterized in that, include: The partitioning module is used to divide the output cycle of a multilevel current source converter into multiple working cycles. The acquisition module is used to acquire the terminal voltage of the U-phase filter capacitor in the multi-level current source converter; The trigger module is used to trigger each bridge arm of the multi-level current source converter according to a preset first degree of freedom and a preset second degree of freedom when the terminal voltage of the U-phase filter capacitor crosses zero. Wherein, the first degree of freedom is used to indicate the electrical angle difference between the start time of the output cycle and the time when the terminal voltage of the U-phase filter capacitor crosses zero; the second degree of freedom is used to indicate half of the shoot-through time corresponding to the bridge arm shoot-through state; the bridge arm shoot-through state is used to indicate that the output current of each of the U-phase, V-phase and W-phase of the multi-level current source converter is 0.

7. The modulation apparatus according to claim 6, characterized in that, The triggering module is specifically used for: When the terminal voltage of the U-phase filter capacitor reaches a zero-crossing point from negative to positive, the first working cycle of the plurality of working cycles is delayed by the first degree of freedom, and each bridge arm is triggered according to the second degree of freedom.

8. The modulation apparatus according to claim 7, characterized in that, The multilevel current source converter includes a power electronic converter and a filter; The power electronic converter includes a three-phase current source converter; the filter includes a U-phase filter capacitor, a V-phase filter capacitor, and a W-phase filter capacitor. The first terminals of each of the three-phase current source converters are connected in parallel to form the first DC terminal of the power electronic converter; the second terminals of each of the three-phase current source converters are connected in parallel to form the second DC terminal of the power electronic converter; the first DC terminal and the second DC terminal constitute the DC side of the multi-level current source converter; the AC side of the power electronic converter is connected to the first terminals of each of the U-phase filter capacitor, the V-phase filter capacitor, and the W-phase filter capacitor, and the second terminals of each of the U-phase filter capacitor, the V-phase filter capacitor, and the W-phase filter capacitor constitute the AC side of the multi-level current source converter.

9. The modulation apparatus according to claim 8, characterized in that, Each phase current source converter in the three-phase current source converter includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm. The first bridge arm is connected in series with the fourth bridge arm to form the first branch; the fifth bridge arm is connected in series with the second bridge arm to form the second branch; the third bridge arm is connected in series with the sixth bridge arm to form the third branch; the first branch, the second branch and the third branch are connected in parallel.

10. The modulation apparatus according to claim 9, characterized in that, The triggering module is specifically used for: This triggers the second and third bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =0, I V =-I dc I W =I dc Among them, I U I represents the output current of phase U. V I represents the output current of phase V. W I represents the output current of phase W. dc This represents the DC-side current of the multilevel current source converter; This triggers the first bridge arm of phase A current source converter, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of each of phase B and phase C current source converters in the three-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =-I dc I W =2I dc / 3; Trigger the second and fifth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; The first bridge arm of each of the A-phase current source converter and the B-phase current source converter, the second bridge arm of each of the three-phase current source converters, and the third bridge arm of the C-phase current source converter are triggered to conduct and remain on for one working cycle, causing I... U =2I dc / 3, I V =-I dc I W =I dc / 3; Triggering the first and second bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc I W =0; This triggers the first bridge arm of each of the A-phase current source converter and the B-phase current source converter, the second bridge arm of each of the A-phase current source converter and the B-phase current source converter, and the first and sixth bridge arms of the C-phase current source converter to conduct and remain on for one working cycle, causing I... U =I dc I V =-2I dc / 3, I W =-I dc / 3; Trigger the first and fourth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; This triggers the first bridge arm of each of the three-phase current source converters, the sixth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =I dc I V =-I dc / 3, I W =-2I dc / 3; The first and sixth bridge arms of each of the three-phase current source converters are triggered to conduct and remain on for one operating cycle, causing I... U =I dc I V =0, I W =-I dc ; This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =2I dc / 3, I V =I dc / 3, I W =-I dc ; Trigger the third and sixth bridge arms of each of the three-phase current source converters to conduct and maintain the shoot-through time, so that I U =0, I V =0, I W =0; This triggers the sixth bridge arm of each of the three-phase current source converters, the first bridge arm of the A-phase current source converter, and the fifth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =I dc / 3, I V =2I dc / 3, I W =-I dc ; Trigger the fifth and sixth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I U =0, I V =I dc I W =-I dc ; This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of the A-phase current source converter, and the sixth bridge arm of each of the B-phase and C-phase current source converters to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =I dc I W =-2I dc / 3; This triggers the fifth bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and B-phase current source converters, and the sixth bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =I dc I W =-I dc / 3; The fourth and fifth bridge arms of each of the three-phase current source converters are triggered to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc I W =0; This triggers the fourth bridge arm of each of the three-phase current source converters, the fifth bridge arm of each of the A-phase and B-phase current source converters, and the third bridge arm of the C-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =2I dc / 3, I W =I dc / 3; This triggers the fourth bridge arm of each of the three-phase current source converters, the third bridge arm of each of the A-phase and C-phase current source converters, and the fifth bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc I V =I dc / 3, I W =2I dc / 3; Trigger the third and fourth bridge arms of each of the three-phase current source converters to conduct and remain on for one operating cycle, causing I U =-I dc I V =0, I W =I dc ; This triggers the third bridge arm of each of the three-phase current source converters, the fourth bridge arm of each of the A-phase and C-phase current source converters, and the second bridge arm of the B-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-2I dc / 3, I V =-I dc / 3, I W =I dc ; This triggers the third bridge arm of each of the three-phase current source converters, the second bridge arm of each of the B-phase and C-phase current source converters, and the fourth bridge arm of the A-phase current source converter to conduct and remain on for one operating cycle, causing I... U =-I dc / 3, I V =-2I dc / 3, I W =I dc ; The through time is used to indicate the time range between the start and end times of the through state of the bridge arm; the start time is t. maxh -θ, where the end time is t maxh +θ,t maxh θ represents the midpoint of the peak value of the output current of phase U, phase V, or phase W; θ represents the second degree of freedom.

11. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the modulation method as described in any one of claims 1 to 5 is implemented.

12. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the modulation method as described in any one of claims 1 to 5.

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