A thirteen-segment carrier pulse width modulation method, system and related components

Abstract

The present application discloses a thirteen-segment carrier pulse width modulation method, system and related components, which relate to the field of carrier pulse width modulation and are applied to three-level converters. The method includes: sorting the three instantaneous voltage values ​​of the three-phase sine wave; determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the middle voltage value and the minimum voltage value; determining the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase; comparing the upper modulation wave, the lower modulation wave and the triangular carrier of each phase to generate the drive signal of the corresponding phase. The drive signal output by the modulation method can ensure that the phase voltage pulse width in the low-profile system area is greater than the minimum switching time of the device, thereby effectively eliminating narrow pulses, accurately outputting the target voltage, and having the effect of reducing current harmonic distortion and improving the self-balancing of the midpoint voltage of the three-level converter. In addition, the present application only requires amplitude calculation, and has the advantages of simple calculation and easy implementation.

Description

Technical Field

[0001] The present invention relates to the field of carrier pulse width modulation, and in particular to a thirteen-segment carrier pulse width modulation method, system and related components. Background Art

[0002] Due to the advantages of low voltage stress of power devices, good output power quality, relatively simple structure and control, three-level neutral point clamped (NPC) converter, referred to as three-level converter, has been widely used in power grid reactive power compensation, rail transit, wind power generation, metallurgy and mining and other fields. Figure 1 It is the main circuit topology of the three-level converter.

[0003] The control core of the three-level converter is to control the switching state of each power device. When each power device is switched according to the set driving signal, the three-level converter can output the set voltage vector and then accurately output the target voltage. When the power devices are not driven normally, the output voltage of the three-level converter will be distorted, and even the converter operation will be uncontrollable.

[0004] The document "An IPWM Algorithm Considering Dead Zone and Minimum Pulse Width Limitation" (Huang Zhaobin [J]. Transactions of the Chinese Society of Electrotechnical Engineering, 2014, 29 (12): 11-18.) points out that in order to correctly drive the power device, the pulse width of each phase voltage output by the three-level converter must be greater than the minimum switching time of the power device. Therefore, the pulse width of the phase voltage and the minimum switching time of the device are the key factors that determine whether the power device can be driven correctly.

[0005] Regarding the phase voltage pulse width, the document "Research on Optimized Carrier Pulse Width Modulation and Fault Tolerance Technology for High-Power Three-Level Converters" (Gao Zhan [D]. Beijing: University of Chinese Academy of Sciences, 2021) points out that in the low-index modulation region, the phase voltage pulse width under the traditional carrier pulse width modulation method and the space vector modulation method is inversely proportional to the modulation index. Therefore, the lower the modulation index, the more likely the phase voltage will have narrow pulses with a short duration. In addition, the document "A novel multilevel carrier-based PWM-control method for GTO inverter in low index modulation region" (L. Ben-Brahim [J]. IEEE Transactions on Industry Applications, 2006, 42 (1): 121-127.) points out that the lower the modulation index, the more significant the adverse effect of voltage amplitude distortion caused by narrow pulses.

[0006] Regarding the minimum switching time of the device, the paper "Research on Pulse Width Modulation and Field Oriented Control of High-Power Three-Level Converters" (Yin Zhenggang [D]. Beijing: University of Chinese Academy of Sciences, 2012) points out that compared with small-power devices, in order to fully release the capacitive energy of the buffer circuit, the minimum switching time of high-power devices is longer.

[0007] Combining the above two factors, in order to correctly drive high-power devices, the pulse width modulation method of high-power three-level converters in the low-profile region should be able to ensure the pulse width of the phase voltage. However, in the low-profile region, the phase voltage pulse width of the existing carrier pulse width modulation method and space vector modulation method are both narrow, and the phase voltage pulse width cannot be greater than the minimum switching time of the device, resulting in output voltage amplitude distortion and current harmonic performance degradation.

[0008] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve. Summary of the invention

[0009] In view of this, the purpose of the present invention is to provide a thirteen-segment carrier pulse width modulation method, system and related components to ensure that the phase voltage pulse width of a high-power three-level converter in a low-profile region is greater than the minimum switching time of the device. The specific scheme is as follows:

[0010] A thirteen-segment carrier pulse width modulation method, applied to a three-level converter, comprising:

[0011] The three instantaneous voltage values ​​of the three-phase sine wave are sorted and determined as the maximum voltage value, the middle voltage value and the minimum voltage value;

[0012] Determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value;

[0013] According to the dual modulation wave parameters of each phase, determining the upper modulation wave and the lower modulation wave of the corresponding phase;

[0014] The upper modulation wave, the lower modulation wave and the triangular carrier of each phase are compared to generate a driving signal of the corresponding phase to drive the power device of the corresponding phase.

[0015] Preferably, the process of determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value includes:

[0016] According to the first formula, determining the dual modulation wave parameter of the phase corresponding to the maximum voltage value;

[0017] Determine the dual modulation wave parameter of the corresponding phase of the intermediate voltage value according to the second formula;

[0018] According to the third formula, determining the dual modulation wave parameter of the phase corresponding to the minimum voltage value;

[0019] The dual modulation wave parameters include a first parameter and a second parameter, and the first formula is:

[0020]

[0021] The second formula is:

[0022]

[0023] The third formula is:

[0024]

[0025] Among them, V max 、V mid and V min are the maximum voltage value, the intermediate voltage value and the minimum voltage value respectively, P max and N max are the first parameter and the second parameter of the phase corresponding to the maximum voltage value, P mid and N mid are the first parameter and the second parameter of the phase corresponding to the intermediate voltage value, P min and N min The first parameter and the second parameter of the phase corresponding to the minimum voltage value.

[0026] Preferably, the process of determining the upper modulation wave and the lower modulation wave of any phase according to the dual modulation wave parameters of the phase includes:

[0027] According to the dual modulation wave parameters of any phase, the amplitude of the upper modulation wave of the phase is determined to be the first parameter, and the amplitude of the lower modulation wave of the phase is determined to be the sum of the second parameter and a voltage reference value.

[0028] Preferably, the power device of each phase includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube arranged from top to bottom on the bridge arm of the phase, and the process of comparing the upper modulation wave, the lower modulation wave and the triangular carrier of any phase to generate a drive signal of the corresponding phase to drive the power device of the corresponding phase includes:

[0029] If the current triangular carrier wave is smaller than the upper modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 1, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 0;

[0030] If the current triangular carrier is greater than the down-modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 0, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 1;

[0031] When the current triangular carrier is between the upper modulation wave and the lower modulation wave of the phase, the driving signals of the second switch tube and the third switch tube of the phase are set to 1, and the driving signals of the first switch tube and the fourth switch tube of the phase are set to 0.

[0032] Preferably, before the three instantaneous voltage values ​​of the three-phase sine wave are sorted by magnitude to determine the maximum voltage value, the middle voltage value and the minimum voltage value, the method further includes:

[0033] Determine whether the current operating condition is a low-profile system condition;

[0034] If so, the action of sorting the three instantaneous voltage values ​​of the three-phase sine wave to determine the maximum voltage value, the middle voltage value and the minimum voltage value is performed.

[0035] Preferably, the process of determining whether the current operating condition is a low-profile operating condition includes:

[0036] Calculate the current modulation degree according to the current operating conditions;

[0037] Determine whether the current modulation index is lower than the preset modulation index. If so, determine that the current operating condition is a low-modulation condition.

[0038] Preferably, the process of determining whether the current operating condition is a low-profile operating condition includes:

[0039] Determine whether the current operating conditions meet the low-profile system operating conditions;

[0040] The low-profile operating condition includes: the current output line voltage fundamental amplitude is on an upward trend and is less than a first preset percentage of the current DC side voltage value, or the current output line voltage fundamental amplitude is on a downward trend and is less than a second preset percentage of the current DC side voltage value.

[0041] Correspondingly, the present application also discloses a thirteen-segment carrier pulse width modulation system, which is applied to a three-level converter, comprising:

[0042] A sorting module is used to sort the three instantaneous voltage values ​​of the three-phase sine wave into a maximum voltage value, an intermediate voltage value and a minimum voltage value;

[0043] A first determination module, configured to determine a dual modulation wave parameter of a corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value;

[0044] A second determination module, used to determine the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase;

[0045] The driving signal module is used to compare the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, and generate a driving signal of the corresponding phase to drive the power device of the corresponding phase.

[0046] Correspondingly, the present application also discloses a thirteen-segment carrier pulse width modulation device, comprising:

[0047] Memory for storing computer programs;

[0048] A processor is used to implement the steps of the thirteen-segment carrier pulse width modulation method as described in any one of the above items when executing the computer program.

[0049] Correspondingly, the present application also discloses a readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the thirteen-segment carrier pulse width modulation method as described in any one of the above items are implemented.

[0050] The present application discloses a thirteen-segment carrier pulse width modulation method, which is applied to a three-level converter, including: sorting the three instantaneous voltage values ​​of the three-phase sine wave, and determining them as the maximum voltage value, the middle voltage value and the minimum voltage value; determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the middle voltage value and the minimum voltage value; determining the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase; comparing the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, and generating a driving signal of the corresponding phase to drive the power device of the corresponding phase. The driving signal output by the modulation method can ensure that the phase voltage pulse width of the high-power three-level converter in the low-profile system area is greater than the minimum switching time of the device, so that the narrow pulse can be effectively eliminated, the target voltage can be accurately output, and the effect of reducing the current harmonic distortion and improving the self-balancing of the midpoint voltage of the three-level converter can be achieved. In addition, the present application can obtain the driving signal of each power device only by amplitude calculation, which has the advantages of simple calculation and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0052] Figure 1 This is a typical three-level converter structure distribution diagram;

[0053] Figure 2 A flowchart of a thirteen-segment carrier pulse width modulation method according to an embodiment of the present invention;

[0054] Figure 3a and Figure 3b This is the simulation result diagram of traditional space vector pulse width modulation;

[0055] Figure 4a and Figure 4b 1 is a simulation result diagram of a 13-segment carrier pulse width modulation method in this embodiment;

[0056] Figure 5 is a comparison diagram of the fundamental amplitude of the output line voltage of space vector pulse width modulation and this embodiment;

[0057] Figure 6a and Figure 6b is a comparison diagram of the output power quality of space vector pulse width modulation and this embodiment;

[0058] Figure 7a and Figure 7b is a comparison diagram of the end point voltage fluctuation of space vector pulse width modulation and this embodiment;

[0059] Figure 8a and Figure 8b A driving schematic diagram of a thirteen-segment carrier pulse width modulation method of this embodiment;

[0060] Fig. 9 This is a structural distribution diagram of a thirteen-segment carrier pulse width modulation system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Combining the above two factors, in order to correctly drive high-power devices, the pulse width modulation method of high-power three-level converters in the low-profile region should be able to ensure the pulse width of the phase voltage. However, in the low-profile region, the phase voltage pulse width of the existing carrier pulse width modulation method and space vector modulation method are both narrow, and the phase voltage pulse width cannot be greater than the minimum switching time of the device, resulting in output voltage amplitude distortion and current harmonic performance degradation.

[0063] The drive signal output by the present application can ensure that the phase voltage pulse width of the high-power three-level converter in the low-profile region is greater than the minimum switching time of the device, thereby effectively eliminating narrow pulses and accurately outputting the target voltage, and has the effect of reducing current harmonic distortion and improving the self-balancing effect of the midpoint voltage of the three-level converter. In addition, the present application can obtain the drive signal of each power device only by amplitude calculation, which has the advantages of simple calculation and easy implementation.

[0064] The embodiment of the present invention discloses a thirteen-segment carrier pulse width modulation method, which is applied to a three-level converter, see Figure 2 As shown, the method includes:

[0065] S1: Sort the three instantaneous voltage values ​​of the three-phase sine wave into a maximum voltage value, a middle voltage value and a minimum voltage value;

[0066] Specifically, the three-phase sine wave refers to the three-phase three-phase sine wave at the output end of the three-level converter. The three instantaneous voltage values ​​of the three-phase sine wave are V A 、V B and V C The maximum voltage value, the middle voltage value, and the minimum voltage value are V max 、V mid and V min The judgment results are as follows:

[0067] When V A >V B >V C , V max =V A , V mid =V B , V min =V C ;

[0068] When V A >V C >V B , V max =V A , V mid =V C , V min =V B ;

[0069] When V B >V A >V C , V max =V B , V mid =V A , V min =V C ;

[0070] When V B >V C >V A , V max =V B , V mid =V C , V min =V A ;

[0071] When V C >V A >V B , V max =V C , V mid =V A , V min =V B ;

[0072] When V C >V B >V A , V max =V C , V mid =V B , V min =V A .

[0073] S2: Determine the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the middle voltage value and the minimum voltage value;

[0074] Specifically, step S2 is a process of determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the middle voltage value and the minimum voltage value, including:

[0075] According to the first formula, determining the dual modulation wave parameter of the phase corresponding to the maximum voltage value;

[0076] According to the second formula, determining the dual modulation wave parameter of the corresponding phase of the intermediate voltage value;

[0077] According to the third formula, determining the dual modulation wave parameter of the phase corresponding to the minimum voltage value;

[0078] The dual modulation wave parameters include a first parameter and a second parameter, and the first formula is:

[0079]

[0080] The second formula is:

[0081]

[0082] The third formula is:

[0083]

[0084] Among them, V max 、V mid and V min are the maximum voltage value, the middle voltage value and the minimum voltage value respectively, P max and N max are the first and second parameters of the phase corresponding to the maximum voltage value, P mid and N mid are the first and second parameters of the phase corresponding to the intermediate voltage value, P min and N min are the first parameter and the second parameter of the phase corresponding to the minimum voltage value.

[0085] It can be understood that the so-called dual modulation wave parameters of the corresponding phase here refer to the dual modulation wave parameters of one phase among the three phases. For example, V A >V B >V C For example, V max =V A , V mid =V B , V min =V C , at this time P A =P max , N A =N max , P B =P mid , N B =N mid , P C =P min , N C =N min , and so on for other situations.

[0086] S3: determining the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase;

[0087] Specifically, step S3 is a process of determining the upper modulation wave and the lower modulation wave of any phase according to the dual modulation wave parameters of the phase, including:

[0088] According to the dual modulation wave parameters of any phase, the amplitude of the upper modulation wave of the phase is determined as the first parameter, and the amplitude of the lower modulation wave of the phase is determined as the sum of the second parameter and a voltage reference value.

[0089] It can be understood that all calculations in this embodiment can be performed in per-unit values, where a voltage reference value is 1, and the amplitude of the down-modulation wave is the second parameter+1.

[0090] S4: Compare the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, generate a driving signal of the corresponding phase, and drive the power device of the corresponding phase.

[0091] Further, such as Figure 1 In the three-level converter shown in the figure, the power device of each phase includes a first switch tube Px1, a second switch tube Px2, a third switch tube Px3 and a fourth switch tube Px4 arranged from top to bottom on the bridge arm of the phase, where x=a / b / c. The process of comparing the upper modulation wave, the lower modulation wave and the triangular carrier of any phase to generate a driving signal of the corresponding phase to drive the power device of the corresponding phase includes:

[0092] If the current triangular carrier wave is smaller than the upper modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 1, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 0;

[0093] If the current triangular carrier wave is greater than the down-modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 0, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 1;

[0094] When the current triangular carrier is between the upper modulation wave and the lower modulation wave of the phase, the driving signals of the second switch tube and the third switch tube of the phase are set to 1, and the driving signals of the first switch tube and the fourth switch tube of the phase are set to 0.

[0095] It can be understood that, in this embodiment, the driving signal is embodied as thirteen segments, so this method is named as the thirteen-segment carrier pulse width modulation method.

[0096] The present application discloses a thirteen-segment carrier pulse width modulation method, which is applied to a three-level converter, including: sorting the three instantaneous voltage values ​​of the three-phase sine wave, and determining them as the maximum voltage value, the middle voltage value and the minimum voltage value; determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the middle voltage value and the minimum voltage value; determining the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase; comparing the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, and generating a driving signal of the corresponding phase to drive the power device of the corresponding phase. The driving signal output by the modulation method can ensure that the phase voltage pulse width of the high-power three-level converter in the low-profile system area is greater than the minimum switching time of the device, so that the narrow pulse can be effectively eliminated, the target voltage can be accurately output, and the effect of reducing the current harmonic distortion and improving the self-balancing of the midpoint voltage of the three-level converter can be achieved. In addition, the present application can obtain the driving signal of each power device only by amplitude calculation, which has the advantages of simple calculation and easy implementation.

[0097] Further, the carrier pulse width modulation method in the embodiment of the present application is generally used to solve the problem under low-voltage system conditions. Before the three instantaneous voltage values ​​of the three-phase sine wave are sorted and determined as the maximum voltage value, the middle voltage value and the minimum voltage value, it also includes:

[0098] Determine whether the current operating condition is a low-profile system condition;

[0099] If so, the three instantaneous voltage values ​​of the three-phase sine wave are sorted in order to determine the maximum voltage value, the middle voltage value and the minimum voltage value.

[0100] Specifically, the process of determining whether the current operating condition is a low-profile system condition includes:

[0101] Calculate the current modulation degree according to the current operating conditions;

[0102] Determine whether the current modulation index is lower than the preset modulation index. If so, determine that the current operating condition is a low-modulation condition.

[0103] Alternatively, the process of determining whether the current operating condition is a low-profile system condition includes:

[0104] Determine whether the current operating conditions meet the low-profile system operating conditions;

[0105] The low-profile operating conditions include: the current output line voltage fundamental amplitude is on an upward trend and is less than a first preset percentage of the current DC side voltage value, or the current output line voltage fundamental amplitude is on a downward trend and is less than a second preset percentage of the current DC side voltage value.

[0106] It can be understood that the preset modulation degree, the first preset percentage and the second preset percentage mentioned here are all set according to the actual working conditions, where the preset modulation degree can be selected as 0.5, the first preset percentage can be selected as 33%, and the second preset percentage can be selected as 25%. Other values ​​can also be selected to configure the above parameters.

[0107] The embodiment of the present invention discloses a specific thirteen-segment carrier pulse width modulation method. Compared with the previous embodiment, this embodiment further illustrates and optimizes the technical solution. Specifically:

[0108] This embodiment uses PSIM software to build a three-level converter model, and uses simulation to verify the effectiveness of a thirteen-segment carrier pulse width modulation method of this embodiment. The simulation conditions include: the simulation step size is set to 2us, the DC side voltage is 540V, the triangular carrier frequency is 2000Hz, the sampling frequency is 4000Hz, and the minimum switching time of the power device is 20us.

[0109] See also Figure 3a , Figure 3bAs shown, the simulation results of traditional space vector pulse width modulation in the low-profile regime are as follows: Figure 3a The phase voltage and line voltage under the modulation index of 0.04, fundamental frequency of 2Hz, and space vector pulse width modulation are shown in Figure 1. Figure 3b The phase voltage and line voltage are the modulation index of 0.1, the fundamental frequency of 5Hz, and the space vector pulse width modulation. It is known that the starting and low-speed state of the output motor are the typical operating conditions of the three-level converter in the low-frequency region. The modulation index of 0.04 and the fundamental frequency of 2Hz correspond to the output motor being in the starting state, such as Figure 3a At this time, the phase voltage under the action of space vector pulse width modulation has a pulse with a duration of only 3.5us, the modulation index is 0.1, and the fundamental frequency is 5Hz, which corresponds to the output motor being in a low speed state. Figure 3b , at this time, the phase voltage under the action of space vector pulse width modulation has a pulse with a duration of only 12us. When the minimum switching time of the power device is 20us, the driving signal with a duration of less than 20us cannot correctly control the switching state of the power device. In the low-profile system area, there is a situation where the pulse width of the phase voltage under the action of space vector pulse width modulation does not meet the minimum switching time of the device, which has an adverse effect on the precise control and safe operation of the three-level converter.

[0110] See also Figure 4a , Figure 4b As shown, the simulation results of this application method in the low-profile regime area are as follows: Figure 4a The modulation index is 0.04, the fundamental frequency is 2Hz, and the phase voltage and line voltage under the action of the method of this application are: Figure 4b The phase voltage and line voltage under the action of the method of this application are shown in the figure with a modulation index of 0.1 and a fundamental frequency of 5 Hz. Figure 4a and Figure 4b When the output motor is started and in low speed state, the duration of each phase voltage pulse under the action of the method of the present application is more than 160us, which can ensure that the drive signal can correctly control the switching state of each power device. Figure 3a , Figure 3b and Figure 4a , Figure 4b Compared with the traditional space vector pulse width modulation method, the method of the present application can effectively eliminate narrow pulses in the low-profile regime area, which improves the control performance of the three-level converter and ensures the safe operation of the device.

[0111] See also Figure 5As shown, when the fundamental frequency in the simulation environment is 10Hz, the modulation index gradually increases from 0.02 to 0.3. The comparison of the fundamental amplitude of the output line voltage of the traditional space vector pulse width modulation and the method of the present application shows that in the area where the modulation index is lower than 0.1, due to the presence of narrow pulses with a duration less than the minimum switching time of the device, the power devices under the action of the traditional space vector pulse width modulation cannot be turned on and off according to the pre-designed timing, resulting in distortion of the fundamental amplitude of the output line voltage. However, the method of the present application can correctly drive each power device in the low-frequency system area, and the fundamental amplitude of the output line voltage under its action is basically consistent with the theoretical value. Therefore, the method of the present application can output the target voltage more accurately.

[0112] See also Figure 6a , Figure 6b As shown, when the fundamental frequency in the simulation environment is 10Hz and the modulation index gradually increases from 0.02 to 0.3, the output power quality comparison between the space vector pulse width modulation and the method of the present application is as follows: Figure 6a The comparison between the space vector pulse width modulation and the line voltage WTHD (Weighted Total Harmonic Distortion) of the method of the present application is shown in FIG. Figure 6b The figure is a comparison of the current THD (Total Harmonic Distortion) of the space vector pulse width modulation and the method of the present application. Figure 6a and Figure 6b It is known that in the area where the modulation index is lower than 0.3, compared with the traditional space vector pulse width modulation, under the action of the method of the present application, the three-level converter has a lower line voltage WTHD and a lower current THD. Therefore, the method of the present application can effectively reduce the current harmonic distortion and improve the output power quality.

[0113] See also Figure 7a , Figure 7b As shown, when the fundamental frequency is 10 Hz and the modulation index is 0.2 in the simulation environment, the midpoint voltage fluctuation of the space vector pulse width modulation and the method of the present application is compared as follows: Figure 7a is the phase voltage and midpoint voltage fluctuation under space vector pulse width modulation, Figure 7b The phase voltage and midpoint voltage fluctuations under the action of the method of this application. Figure 7a It is shown that when space vector pulse width modulation is used, the midpoint voltage fluctuation frequency of the three-level converter is three times the fundamental frequency; Figure 7b This shows that under the action of the method of the present application, the midpoint voltage fluctuation frequency of the three-level converter is equal to the carrier frequency. Since the carrier frequency is much higher than the fundamental frequency, the midpoint voltage fluctuation frequency of the method of the present application is higher than when using space vector pulse width modulation, so the midpoint voltage balance can be adjusted more quickly. In addition, compared Figure 7a and Figure 7b, under the same modulation index and fundamental frequency, compared with the traditional space vector pulse width modulation, the midpoint voltage fluctuation amplitude under the action of the present application method is lower. The present application method also has a higher midpoint voltage fluctuation frequency and a lower midpoint voltage fluctuation amplitude, so the present application method significantly improves the midpoint voltage self-balancing ability of the three-level converter.

[0114] See also Figure 8a , Figure 8b As shown, Figure 8a The modulation index is 0.04, the fundamental frequency is 2Hz, and the double modulation wave, triangular carrier and three-phase output phase voltage obtained by the method of the present application are used. Figure 8b The modulation index is 0.1, the fundamental frequency is 5Hz, and the double modulation wave, triangular carrier and three-phase output phase voltage obtained by the method of this application are limited by the image resolution. Figure 8a The amplitudes of the dual modulation waves of the three phases ABC are close and the lines overlap. Figure 8b The values ​​of the dual modulation waves of the two phases AC are close and the lines overlap. It is understandable that in actual operation, the amplitudes of the dual modulation waves are not exactly the same. Figure 8a and Figure 8b It is known that the method of the present application directly obtains the switching signal of the three-phase power device based on the comparison result of the dual modulation wave and the triangular carrier. Since the calculation of the dual modulation wave only involves the comparison of the amplitude and the addition and subtraction calculation of the three-phase sine wave, the method of the present application also has the advantages of simple calculation and convenient implementation.

[0115] like Figures 3a to 8b As shown, the results of the simulation comparison verify the effectiveness of the thirteen-segment carrier pulse width modulation method of a three-level converter in the present application. Compared with the traditional space vector pulse width modulation, the method of the present application can ensure that the phase voltage pulse width of the three-level converter in the low-profile system area is greater than the minimum switching time of the device, thereby effectively eliminating narrow pulses and accurately outputting the target voltage, and has the effect of reducing current harmonic distortion and improving the self-balancing ability of the midpoint voltage of the three-level converter. In addition, the method of the present application can obtain the driving signal of each power device only by comparing the amplitude and adding and subtracting the three-phase sine wave, and it also has the advantages of simple calculation and easy implementation.

[0116] Correspondingly, the present application also discloses a thirteen-segment carrier pulse width modulation system, which is applied to a three-level converter, see Fig. 9 As shown, the system includes:

[0117] The sorting module 1 is used to sort the three instantaneous voltage values ​​of the three-phase sine wave into a maximum voltage value, an intermediate voltage value and a minimum voltage value;

[0118] A first determination module 2, used to determine the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value;

[0119] A second determination module 3, used to determine the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase;

[0120] The driving signal module 4 is used to compare the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, and generate a driving signal of the corresponding phase to drive the power device of the corresponding phase.

[0121] The drive signal output by the embodiment of the present application can ensure that the phase voltage pulse width of the high-power three-level converter in the low-profile region is greater than the minimum switching time of the device, thereby effectively eliminating narrow pulses and accurately outputting the target voltage, and has the effect of reducing current harmonic distortion and improving the self-balancing effect of the midpoint voltage of the three-level converter. In addition, the present application can obtain the drive signal of each power device only by amplitude calculation, which has the advantages of simple calculation and easy implementation.

[0122] In some specific embodiments, the process of the first determining module 2 determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value includes:

[0123] According to the first formula, determining the dual modulation wave parameter of the phase corresponding to the maximum voltage value;

[0124] Determine the dual modulation wave parameter of the corresponding phase of the intermediate voltage value according to the second formula;

[0125] According to the third formula, determining the dual modulation wave parameter of the phase corresponding to the minimum voltage value;

[0126] The dual modulation wave parameters include a first parameter and a second parameter, and the first formula is:

[0127]

[0128] The second formula is:

[0129]

[0130] The third formula is:

[0131]

[0132] Among them, V max 、V mid and V min are the maximum voltage value, the intermediate voltage value and the minimum voltage value respectively, P max and N max are the first parameter and the second parameter of the phase corresponding to the maximum voltage value, P mid and N midare the first parameter and the second parameter of the phase corresponding to the intermediate voltage value, P min and N min The first parameter and the second parameter of the phase corresponding to the minimum voltage value.

[0133] In some specific embodiments, the process of the second determining module 3 determining the upper modulation wave and the lower modulation wave of any phase according to the dual modulation wave parameters of the phase includes:

[0134] According to the dual modulation wave parameters of any phase, the amplitude of the upper modulation wave of the phase is determined to be the first parameter, and the amplitude of the lower modulation wave of the phase is determined to be the sum of the second parameter and a voltage reference value.

[0135] In some specific embodiments, the power device of each phase includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube arranged from top to bottom on the bridge arm of the phase, and the driving signal module 4 compares the upper modulation wave, the lower modulation wave and the triangular carrier of any phase to generate a driving signal of the corresponding phase to drive the power device of the corresponding phase, including:

[0136] If the current triangular carrier wave is smaller than the upper modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 1, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 0;

[0137] If the current triangular carrier is greater than the down-modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 0, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 1;

[0138] When the current triangular carrier is between the upper modulation wave and the lower modulation wave of the phase, the driving signals of the second switch tube and the third switch tube of the phase are set to 1, and the driving signals of the first switch tube and the fourth switch tube of the phase are set to 0.

[0139] In some specific embodiments, before the sorting module 1 sorts the three instantaneous voltage values ​​of the three-phase sine wave into the maximum voltage value, the middle voltage value and the minimum voltage value, it is further used to:

[0140] Determine whether the current operating condition is a low-profile system condition;

[0141] If so, the action of sorting the three instantaneous voltage values ​​of the three-phase sine wave to determine the maximum voltage value, the middle voltage value and the minimum voltage value is performed.

[0142] In some specific embodiments, the process of the sorting module 1 determining whether the current operating condition is a low-profile operating condition includes:

[0143] Calculate the current modulation degree according to the current operating conditions;

[0144] Determine whether the current modulation index is lower than the preset modulation index. If so, determine that the current operating condition is a low-modulation condition.

[0145] In some specific embodiments, the process of the sorting module 1 determining whether the current operating condition is a low-profile operating condition includes:

[0146] Determine whether the current operating conditions meet the low-profile system operating conditions;

[0147] The low-profile operating condition includes: the current output line voltage fundamental amplitude is on an upward trend and is less than a first preset percentage of the current DC side voltage value, or the current output line voltage fundamental amplitude is on a downward trend and is less than a second preset percentage of the current DC side voltage value.

[0148] Correspondingly, the present application also discloses a thirteen-segment carrier pulse width modulation device, comprising:

[0149] Memory for storing computer programs;

[0150] A processor is used to implement the steps of the thirteen-segment carrier pulse width modulation method as described in any one of the above items when executing the computer program.

[0151] Correspondingly, the present application also discloses a readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the thirteen-segment carrier pulse width modulation method as described in any one of the above items are implemented.

[0152] For details about the thirteen-segment carrier pulse width modulation method, please refer to the relevant description in the above embodiment, which will not be repeated here.

[0153] Among them, the thirteen-segment carrier pulse width modulation device and the readable storage medium in this embodiment have the same technical effects as the thirteen-segment carrier pulse width modulation method in the above embodiment, and will not be repeated here.

[0154] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0155] The thirteen-segment carrier pulse width modulation method, system and related components provided by the present invention are introduced in detail above. The principle and implementation mode of the present invention are explained by using specific examples in this article. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A thirteen-segment carrier pulse width modulation method, characterized in that: Applied to three-level neutral point clamped converter, including: The three instantaneous voltage values ​​of the three-phase sine wave are sorted and determined as the maximum voltage value, the middle voltage value and the minimum voltage value; Determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value; According to the dual modulation wave parameters of each phase, determining the upper modulation wave and the lower modulation wave of the corresponding phase; Comparing the upper modulation wave, the lower modulation wave and the triangular carrier wave of each phase, generating a driving signal of the corresponding phase to drive the power device of the corresponding phase; Correspondingly, the process of determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value includes: According to the first formula, determining the dual modulation wave parameter of the phase corresponding to the maximum voltage value; Determine the dual modulation wave parameter of the corresponding phase of the intermediate voltage value according to the second formula; According to the third formula, determining the dual modulation wave parameter of the phase corresponding to the minimum voltage value; The dual modulation wave parameters include a first parameter and a second parameter, and the first formula is: The second formula is: The third formula is: Among them, V max 、V mid and V min are the maximum voltage value, the intermediate voltage value and the minimum voltage value respectively, P max and N max are the first parameter and the second parameter of the phase corresponding to the maximum voltage value, P mid and N mid are the first parameter and the second parameter of the phase corresponding to the intermediate voltage value, P min and N min The first parameter and the second parameter of the phase corresponding to the minimum voltage value; Correspondingly, the process of determining the upper modulation wave and the lower modulation wave of any phase according to the dual modulation wave parameters of the phase includes: According to the dual modulation wave parameters of any phase, the amplitude of the upper modulation wave of the phase is determined to be the first parameter, and the amplitude of the lower modulation wave of the phase is determined to be the sum of the second parameter and a voltage reference value.

2. The thirteen-segment carrier pulse width modulation method according to claim 1, characterized in that: The power device of each phase includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube arranged from top to bottom on the bridge arm of the phase, and the process of comparing the upper modulation wave, the lower modulation wave and the triangular carrier of any phase to generate a driving signal of the corresponding phase to drive the power device of the corresponding phase includes: If the current triangular carrier wave is smaller than the upper modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 1, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 0; If the current triangular carrier is greater than the down-modulation wave of the phase, the driving signals of the first switch tube and the second switch tube of the phase are set to 0, and the driving signals of the third switch tube and the fourth switch tube of the phase are set to 1; When the current triangular carrier is between the upper modulation wave and the lower modulation wave of the phase, the driving signals of the second switch tube and the third switch tube of the phase are set to 1, and the driving signals of the first switch tube and the fourth switch tube of the phase are set to 0.

3. The thirteen-segment carrier pulse width modulation method according to claim 1 or 2, characterized in that: Before the three instantaneous voltage values ​​of the three-phase sine wave are sorted and determined as the maximum voltage value, the middle voltage value and the minimum voltage value, the method further includes: Determine whether the current operating condition is a low-profile system condition; If so, the action of sorting the three instantaneous voltage values ​​of the three-phase sine wave to determine the maximum voltage value, the middle voltage value and the minimum voltage value is performed.

4. The thirteen-segment carrier pulse width modulation method according to claim 3, characterized in that: The process of determining whether the current operating condition is a low-profile operating condition includes: Calculate the current modulation degree according to the current operating conditions; Determine whether the current modulation index is lower than the preset modulation index. If so, determine that the current operating condition is a low-modulation condition.

5. The thirteen-segment carrier pulse width modulation method according to claim 3, characterized in that: The process of determining whether the current operating condition is a low-profile operating condition includes: Determine whether the current operating conditions meet the low-profile system operating conditions; The low-profile operating condition includes: the current output line voltage fundamental amplitude is on an upward trend and is less than a first preset percentage of the current DC side voltage value, or the current output line voltage fundamental amplitude is on a downward trend and is less than a second preset percentage of the current DC side voltage value.

6. A thirteen-segment carrier pulse width modulation system, characterized in that: Applicable to three-level converters, including: A sorting module is used to sort the three instantaneous voltage values ​​of the three-phase sine wave into a maximum voltage value, an intermediate voltage value and a minimum voltage value; A first determination module, configured to determine a dual modulation wave parameter of a corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value; A second determination module, used to determine the upper modulation wave and the lower modulation wave of the corresponding phase according to the dual modulation wave parameters of each phase; A driving signal module, used for comparing the upper modulation wave, the lower modulation wave and the triangular carrier of each phase, generating a driving signal of the corresponding phase to drive the power device of the corresponding phase; Correspondingly, the process of determining the dual modulation wave parameters of the corresponding phase according to the maximum voltage value, the intermediate voltage value and the minimum voltage value includes: According to the first formula, determining the dual modulation wave parameter of the phase corresponding to the maximum voltage value; Determine the dual modulation wave parameter of the corresponding phase of the intermediate voltage value according to the second formula; According to the third formula, determining the dual modulation wave parameter of the phase corresponding to the minimum voltage value; The dual modulation wave parameters include a first parameter and a second parameter, and the first formula is: The second formula is: The third formula is: Among them, V max 、V mid and V min are the maximum voltage value, the intermediate voltage value and the minimum voltage value respectively, P max and N max are the first parameter and the second parameter of the phase corresponding to the maximum voltage value, P mid and N mid are the first parameter and the second parameter of the phase corresponding to the intermediate voltage value, P min and N min The first parameter and the second parameter of the phase corresponding to the minimum voltage value; Correspondingly, the process of determining the upper modulation wave and the lower modulation wave of any phase according to the dual modulation wave parameters of the phase includes: According to the dual modulation wave parameters of any phase, the amplitude of the upper modulation wave of the phase is determined to be the first parameter, and the amplitude of the lower modulation wave of the phase is determined to be the sum of the second parameter and a voltage reference value.

7. A thirteen-segment carrier pulse width modulation device, characterized in that: include: Memory for storing computer programs; A processor, used to implement the steps of the thirteen-segment carrier pulse width modulation method as described in any one of claims 1 to 5 when executing the computer program.

8. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the thirteen-segment carrier pulse width modulation method as claimed in any one of claims 1 to 5 are implemented.

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