Time-sharing switching modulation method for DPWM and CPWM of converter

Abstract

The embodiment of the invention provides a time-sharing switching modulation method for DPWM and CPWM of a converter. According to the method, the phase value of the first reference voltage of the converter is monitored in real time, the target modulation mode corresponding to the phase value is determined, whether the current modulation mode of the converter is consistent with the target modulation mode or not is judged, if not, the current modulation mode is switched to the target modulation mode, and the current modulation mode is switched to the target modulation mode. The target modulation mode is adopted to modulate the three-phase reference voltage of the converter to obtain a three-phase modulation voltage, and the three-phase modulation voltage is used for being compared with a triangular carrier wave of the converter to obtain a three-phase switching signal of the converter. According to the method, the modulation mode of the converter is controlled to be switched between the CPWM modulation mode and the DPWM modulation mode through the phase value, and the technical effects that the switching loss of the converter is reduced, less harmonic distortion is generated, the use performance of the converter is improved, and the service life of the converter is prolonged are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of converters, and in particular to a time-sharing switching modulation method of DPWM and CPWM of a converter. Background Art

[0002] As a vital power electronic device, the converter has been widely used in many fields such as power electronics, communications, and transportation. In order to ensure the high conversion efficiency and power output of the converter in different application scenarios, the three-phase voltage of the converter needs to be modulated to control the on-off state of the switch tube inside the converter, thereby optimizing the conversion process between DC and AC of the converter.

[0003] Commonly used pulse width modulation strategies for converters include continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM). Among them, the CPWM modulation strategy can achieve smaller harmonic distortion by regulating performance parameters such as the pulse width, waveform symmetry and modulation depth of the output waveform, but the switching signal generated by the CPWM modulation strategy has a high switching frequency and large switching loss. In addition, although the DPWM modulation strategy can reduce switching losses, the harmonic distortion rate of the DPWM modulation strategy is high, thereby reducing the service life of the converter DC capacitor.

[0004] Therefore, the existing technology cannot take into account both reducing switching losses and reducing harmonic distortion, resulting in the converter being unable to generate less harmonic distortion while reducing switching losses, affecting the performance and life of the converter. Summary of the invention

[0005] The embodiment of the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which is used to reduce the switching loss of the converter and the harmonic distortion of the converter, thereby improving the performance and life of the converter.

[0006] In a first aspect, an embodiment of the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which is applied to the converter, and the method includes:

[0007] monitoring a phase value of a first reference voltage in real time, and determining a target modulation mode corresponding to the phase value, wherein the first reference voltage is determined from a three-phase reference voltage of a converter;

[0008] Determine whether the current modulation mode is consistent with the above target modulation mode;

[0009] When the current modulation mode is inconsistent with the target modulation mode, the current modulation mode is switched to the target modulation mode, and the three-phase reference voltage is pulse-width modulated using the target modulation mode to obtain a three-phase modulated voltage;

[0010] The three-phase modulation voltages are modulated respectively based on the triangular carrier pair of the converter to obtain corresponding three-phase switching signals.

[0011] In a second aspect, an embodiment of the present application provides a pulse width modulation device, comprising:

[0012] A monitoring module, used for monitoring a phase value of a first reference voltage in real time, wherein the first reference voltage is determined from a three-phase reference voltage of a converter;

[0013] A determination module, used to determine a target modulation mode corresponding to the above phase value;

[0014] A judgment module is used to judge whether the current modulation mode is consistent with the target modulation mode;

[0015] A switching module, used for switching the current modulation mode to the target modulation mode when the current modulation mode is inconsistent with the target modulation mode;

[0016] A modulation module, used for performing pulse width modulation on a three-phase reference voltage using a target modulation mode to obtain a three-phase modulated voltage;

[0017] The modulation module is further used to modulate the three-phase modulation voltages respectively based on the triangular carrier pair of the converter to obtain corresponding three-phase switching signals.

[0018] In a third aspect, an embodiment of the present application provides a pulse width modulation system, which is applied to a converter. The pulse width modulation system includes:

[0019] A monitoring unit, configured to monitor in real time a phase value of a first reference voltage, wherein the first reference voltage is determined from a three-phase reference voltage of a converter;

[0020] A modulation mode determination unit, configured to receive a phase value sent by a phase-locked loop of the converter, and determine a target modulation mode corresponding to the three-phase reference voltage according to the phase value;

[0021] A modulation mode switching unit, used to determine whether the current modulation mode is consistent with the target modulation mode, and if the current modulation mode is inconsistent with the target modulation mode, switch the current modulation mode to the target modulation mode;

[0022] The modulation unit is used to perform pulse width modulation on the three-phase reference voltage using a target modulation mode to obtain a three-phase modulated voltage, and compare the three-phase modulated voltage with the triangular carrier of the converter to obtain a corresponding three-phase switching signal.

[0023] In a fourth aspect, an embodiment of the present application provides a converter, comprising: a phase-locked loop, a comparator, and a pulse width modulation system;

[0024] The pulse width modulation system is connected to the phase-locked loop and the comparator respectively, and the pulse width modulation system is the pulse width modulation system shown in the third aspect above;

[0025] The phase-locked loop is used to phase-lock a first reference voltage of the converter to obtain a phase value of the first reference voltage at the current moment, the first reference voltage being determined from the three-phase reference voltage of the converter;

[0026] The comparator is used to receive the three-phase modulation voltage sent by the pulse width modulation system, and compare the three-phase modulation voltage with the triangular carrier to obtain the three-phase switching signal of the converter.

[0027] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementations of the first aspect.

[0028] In a sixth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0029] The embodiment of the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which monitors the phase value of the first reference voltage of the converter in real time, determines the target modulation mode corresponding to the phase value, and judges whether the current modulation mode of the converter is consistent with the target modulation mode. If not, the current modulation mode is switched to the above-mentioned target modulation mode, and then the three-phase reference voltage of the converter is modulated by the target modulation mode to obtain a three-phase modulation voltage, which is used to compare with the triangular carrier of the converter to obtain a three-phase switching signal of the converter. The first reference voltage in the method is one of the three-phase reference voltages of the converter. The method controls the modulation mode of the converter to switch between the CPWM modulation mode and the DPWM modulation mode through the phase value of the above-mentioned first reference voltage, so that the converter switches to the DPWM modulation mode in the interval of high voltage value and switches to the CPWM modulation mode in the interval of low voltage value, so as to reduce the switching loss of the converter while generating less harmonic distortion, thereby improving the performance and life of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0031] Figure 1 A schematic diagram of a CPWM modulation mode provided in this application;

[0032] Figure 2 A flow chart of a time-sharing switching modulation method of a converter DPWM and CPWM provided in the present application Figure 1 ;

[0033] Figure 3 A schematic diagram of a time-sharing switching modulation method for a converter DPWM and CPWM provided in this application Figure 2 ;

[0034] Figure 4 A schematic diagram of phase discrimination through a phase-locked loop provided in the present application;

[0035] Figure 5 A schematic diagram of a DPWM modulation process provided by the present application;

[0036] Figure 6 A schematic diagram of a modulation mode according to phase switching provided by the present application;

[0037] Figure 7 A schematic diagram of the structure of a time-sharing switching modulation device for DPWM and CPWM of a converter provided in the present application.

[0038] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0039] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0040] Converters usually use pulse width modulation strategies to compare the voltage reference wave with the triangular carrier to generate power electronic switching signals. Existing pulse width modulation strategies include CPWM and DPWM. Figure 1This is a schematic diagram of a CPWM modulation mode provided in an embodiment of the present application. Taking the three-phase level of the converter as an example, the CPWM modulation mode compares the triangular carrier with each phase level to obtain a switching signal corresponding to each phase level. The three-phase levels of the converter are all sinusoidal waves. Taking the a-phase level of the converter as an example, the a-phase level is compared with the triangular carrier to obtain a switching signal S 1 S 2 S 3 S 4 ,like Figure 1 As shown, the upper carrier wave is compared with the sine wave to generate a switching signal S 1 and S 3 , the download wave and the sine wave are compared to generate the switching signal S 2 and S 4 , when the phase of the a-phase level is in interval m, the sine wave is greater than the triangular carrier, then the switching signal S 1 S 2 S 3 S 4 The switch state is 1100, where "1" corresponds to the on state and "0" corresponds to the off state. Figure 1 Medium S 1 S 2 S 3 S 4 It can be seen from the signal diagram that the switching frequency of the switching signal obtained by SPWM is higher, and a higher switching frequency increases the switching loss of the converter.

[0041] Therefore, in order to reduce the switching loss of the converter, a DPWM modulation strategy is usually adopted to superimpose a zero-sequence voltage on each phase voltage of the converter to reduce the switching frequency of the converter. However, due to the discontinuity of the switching action generated by the DPWM modulation strategy, the ripple of the DC capacitor of the converter will increase, thereby reducing the service life of the DC capacitor of the converter, that is, reducing the service life of the converter.

[0042] Therefore, the existing technology cannot take into account both reducing switching losses and reducing harmonic distortion of the converter, resulting in the converter being unable to generate less harmonic distortion while reducing switching losses, affecting the performance and life of the converter.

[0043] Based on the above technical problems, the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which determines the modulation mode corresponding to the phase value through the phase value of a reference voltage in the three-phase reference voltage of the converter, and judges whether the current modulation mode is the modulation mode corresponding to the above phase value. If the current modulation mode is not the modulation mode corresponding to the above phase value, the above current modulation mode is switched to the modulation mode corresponding to the above phase value. The modulation modes in this method include CPWM modulation mode and DPWM modulation mode. This method controls the switching of the modulation mode through the phase value of a reference voltage in the three-phase reference voltage. The method is in DPWM modulation mode at the peak of each phase voltage to reduce switching loss. At the same time, when the voltage amplitude is low, the CPWM modulation mode is switched to reduce the DC capacitor ripple current, thereby increasing the life of the converter DC capacitor and thus increasing the service life of the converter.

[0044] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0045] Figure 2 A schematic diagram of a time-sharing switching modulation method for a converter DPWM and CPWM provided in this application Figure 1 , this method is applied to converters, such as Figure 2 As shown, the method includes:

[0046] S201 . Monitor the phase value of a first reference voltage in real time, and determine a target modulation mode corresponding to the phase value.

[0047] The first reference voltage is determined from the three-phase reference voltage of the converter. The three-phase reference voltage may be, for example, three sinusoidal signals with a phase difference of 120° and the same amplitude.

[0048] The target modulation mode includes a DPWM modulation mode and a CPWM modulation mode, wherein the DPWM modulation mode and the CPWM modulation mode correspond to different phase value ranges. For example, the phase value range of the DPWM modulation mode can be set to a phase value range corresponding to a region where the voltage amplitude is higher than a preset amplitude, and the phase value range of the CPWM modulation mode can be set to a phase value range corresponding to a region where the voltage amplitude is lower than a preset amplitude. Specifically, the phase value of the first reference voltage is monitored in real time, and the target modulation mode corresponding to the phase value is determined according to the phase value range in which the phase value of the first reference voltage is located.

[0049] The method determines the target modulation mode corresponding to the voltage amplitude higher than the preset amplitude region as the DPWM modulation mode, and determines the target modulation mode corresponding to the voltage amplitude lower than the preset amplitude region as the CPWM modulation mode through the phase value of a certain reference voltage of the converter, that is, reduces the switching loss corresponding to the high voltage amplitude region, and avoids using only the DPWM modulation mode in the entire pulse width modulation process, which makes the switching tube of the converter charge and discharge discontinuously in the clamping interval, resulting in a larger ripple voltage on the DC capacitor, thereby reducing the service life of the DC capacitor.

[0050] It should be noted that the first reference voltage may be any one-phase voltage determined from the three-phase reference voltage of the converter, or may be set according to actual needs, and the present application does not impose any limitation on this.

[0051] S202: Determine whether the current modulation mode is consistent with the target modulation mode.

[0052] Specifically, after determining the target modulation mode of the converter, it is determined whether the current modulation mode of the converter is consistent with the above target modulation mode. Optionally, if they are consistent, the switching operation of the adjustment mode is not performed, and the three-phase reference voltage of the converter is continuously modulated using the current modulation mode. If they are inconsistent, the current modulation mode can be switched to the above target modulation mode by using the method of step S203 described below. For example, if the target modulation mode is the DPWM modulation mode, and it is detected that the current modulation mode is the CPWM modulation mode, it is determined whether the current modulation mode is consistent with the above target modulation mode, and if the current modulation mode is inconsistent with the target modulation mode, the CPWM modulation mode is switched to the DPWM modulation mode.

[0053] S203. When the current modulation mode is inconsistent with the target modulation mode, the current modulation mode is switched to the target modulation mode, and the target modulation mode is used to perform pulse width modulation on the three-phase reference voltage to obtain a three-phase modulated voltage.

[0054] Specifically, when the current modulation mode is inconsistent with the target modulation mode, the current modulation mode is switched to the target modulation mode, and then the three-phase reference voltage is pulse-width modulated using the target modulation mode to output a three-phase modulation voltage, which is output to a comparator, and the three-phase switching signal of the converter is obtained by comparing the modulation voltage of each phase with the triangular carrier of the converter, and the three-phase switching signal is used to control the on-off state of multiple switch tubes of the converter. Among them, switching the current mode to the target modulation mode includes: switching the modulation parameters of the converter to the modulation parameters corresponding to the target modulation mode, and switching the currently used modulation algorithm to the target modulation algorithm corresponding to the target modulation mode. It can be understood that the above-mentioned modulation parameters include: the identification, carrier frequency, modulation degree, duty cycle and other parameters corresponding to the target modulation mode, and the present application does not limit this.

[0055] It should be noted that after the current modulation mode is switched to the target modulation mode, the waveform parameters and operating state of the three-phase modulation voltage of the converter can also be monitored, and it is determined whether the waveform parameters meet the preset range, and whether the current operating state of the converter is a normal operating state. If the above waveform parameters do not meet the preset range, and / or the current operating state of the converter is not a normal operating state, an alarm message is generated, and corresponding measures are taken in time to adjust and optimize the current modulation strategy. For example, the modulation parameters corresponding to the target modulation mode are adjusted.

[0056] S204 , performing pulse width modulation on the three-phase modulation voltages based on the triangular carrier pair of the converter to obtain corresponding three-phase switching signals.

[0057] Specifically, the triangular carrier of the converter is compared with each phase modulation voltage to obtain a corresponding three-phase switch signal. Optionally, for the first phase modulation voltage in the three-phase modulation voltage, the first phase modulation voltage is compared with the above triangular carrier. When the amplitude of the above first phase modulation voltage is higher than the triangular carrier, the obtained switch signal is a high level, and when the amplitude of the above first phase modulation voltage is lower than the triangular carrier, the obtained switch signal is a low level. The high level can be used to control the switch corresponding to the first phase modulation voltage to be in the on state, and the low level can be used to control the switch corresponding to the first phase modulation voltage to be in the off state.

[0058] The embodiment of the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which monitors the phase value of the first reference voltage of the converter in real time, determines the target modulation mode corresponding to the phase value, judges whether the current modulation mode of the converter is consistent with the target modulation mode, and if not, switches the current modulation mode to the target modulation mode, and then uses the target modulation mode to modulate the three-phase reference voltage of the converter to obtain a three-phase modulation voltage, which is used to compare with the triangular carrier of the converter to obtain a three-phase switching signal of the converter. The first reference voltage in the method is one of the three-phase reference voltages of the converter, and the method controls the modulation mode of the converter to switch between the CPWM modulation mode and the DPWM modulation mode through the phase value of the first reference voltage, so that the converter switches to the DPWM modulation mode in the high voltage value interval and switches to the CPWM modulation mode in the low voltage value interval, so as to reduce the switching loss of the converter while generating less harmonic distortion, thereby improving the performance and life of the converter.

[0059] Figure 3 A schematic diagram of a time-sharing switching modulation method for a converter DPWM and CPWM provided in this application Figure 2 ,like Figure 3 As shown, in this embodiment Figure 2 Based on the embodiment, a possible time-sharing switching modulation method of the converter DPWM and CPWM is described in detail, and the method includes:

[0060] S301 . Monitor the phase value of the first reference voltage in real time to determine whether the phase value is within a phase value range corresponding to a DPWM modulation mode.

[0061] The target modulation mode includes: a CPWM modulation mode and a DPWM modulation mode, and the CPWM modulation mode and the DPWM modulation mode correspond to different phase value ranges.

[0062] Specifically, the phase value of the first reference voltage is monitored in real time, and it is determined whether the phase value corresponding to the current moment is in the phase value range corresponding to the DPWM modulation mode, so as to determine whether the target modulation mode corresponding to the current phase value is the DPWM modulation mode. The phase value range is determined by the amplitude variation law of the first reference voltage. For example, the phase value range corresponding to the region where the amplitude is greater than or equal to the preset amplitude is determined as the phase value range corresponding to the above-mentioned DPWM modulation mode, so as to reduce the switching loss of each phase reference voltage at the high voltage amplitude, thereby reducing the power loss of the converter at the high voltage amplitude. In addition, the phase value range corresponding to the region where the amplitude is less than the preset amplitude is determined as the phase value range corresponding to the above-mentioned CPWM modulation mode, which reduces the ripple current of the converter DC capacitor and increases the service life of the DC capacitor, thereby increasing the service life of the converter.

[0063] Optionally, the phase value of the first reference voltage is determined by a phase-locked loop. Here, a possible method for determining the phase value of the first reference voltage by a phase-locked loop is provided, the method comprising: setting a phase-locked loop in the converter, and performing phase locking on the first reference voltage by the phase-locked loop to obtain the phase value of the first reference voltage at the current moment. Exemplary, Figure 4 A schematic diagram of phase discrimination by a phase-locked loop is provided in an embodiment of the present application, such as Figure 4 As shown, the first area 401, the second area 402, the third area 403, the fourth area 404, the fifth area 405 and the sixth area 406 are the phase value ranges corresponding to the DPWM modulation mode, and the second phase value ranges corresponding to the remaining areas are the phase value ranges corresponding to the CPWM modulation mode. is the phase value of the phase-locked loop output, and , that is, as t increases, the above phase value It changes counterclockwise between 0° and 360°, switching between the phase value range corresponding to the DPWM modulation mode and the phase value range corresponding to the CPWM modulation mode in turn.

[0064] Optionally, for Figure 4 The phase value range corresponding to the DPWM modulation mode shown is determined by the following formula:

[0065]

[0066] in, is the phase value of the first reference voltage, is an integer, is the preset parameter corresponding to the DPWM modulation mode, The range is .

[0067] It should be noted that It can be set according to actual needs. In addition, The ratio can be recorded as 0% DP to 100% DP, which represents the duty cycle of the DPWM modulation mode. Figure 6 A schematic diagram of a modulation mode according to phase switching provided in an embodiment of the present application, such as Figure 6 As shown in the figure, taking 50% DP as an example, the converter target modulation mode is switched between the DPWM modulation mode and the CPWM modulation mode according to the phase value output by the PLL (phase-locked loop), where "1" represents the DPWM modulation mode and "0" represents the CPWM modulation mode.

[0068] S302: If yes, determine that the target modulation mode is the DPWM modulation mode.

[0069] Specifically, if the judgment result of the above step S301 is that the phase value of the first reference voltage is within the phase value range corresponding to the DPWM modulation mode, the target modulation mode of the converter is determined to be the DPWM modulation mode. The DPWM modulation mode includes modulation strategies such as DPWM0, DPWM1, DPWM2, DPWM3, DPWMA and DPWMB. The modulation strategy corresponding to the above DPWM modulation mode can be set according to actual needs, and this application does not limit this.

[0070] Optionally, the modulation strategy corresponding to the DPWM modulation mode is DPWM1. When, according to the formula shown in the above step S301, it is determined that the phase value of the first reference voltage is within the range defined by the above formula, the target modulation mode is determined to be the DPWM modulation mode, that is, the adopted waist strategy is DPWM1.

[0071] S303: If not, determine that the target modulation mode is the CPWM modulation mode.

[0072] Specifically, if the judgment result of the above step S301 is that the phase value of the first reference voltage is not within the phase value range corresponding to the DPWM modulation mode, the target modulation mode of the converter is determined to be the CPWM modulation mode, and then according to the parameters, algorithms and other settings corresponding to the CPWM modulation mode, the modulation parameters and modulation algorithms corresponding to the pulse width modulation system of the converter are adjusted so that the pulse width modulation system adopts the CPWM modulation mode to modulate the three-phase reference voltage of the converter.

[0073] S304: Determine whether the current modulation mode is consistent with the target modulation mode. If the current modulation mode is inconsistent with the target modulation mode, switch the current modulation mode to the target modulation mode.

[0074] The explanation of step S304 can be combined with the contents of steps S202 and S203 above, and will not be repeated here.

[0075] S305 . When the target modulation mode is the DPWM modulation mode, determine a first zero-sequence voltage corresponding to the three-phase reference voltage of the converter.

[0076] Specifically, the corresponding first zero-sequence voltage is determined according to the three-phase reference voltage of the converter. Figure 5 A schematic diagram of a DPWM modulation mode flow chart provided in an embodiment of the present application, such as Figure 5 As shown, the three-phase reference voltage of the converter is input into the zero-sequence voltage generating device, and the corresponding first zero-sequence voltage is calculated based on the above three reference voltages, the preset parameters corresponding to the DPWM modulation mode, and the coefficients of the modulation strategy corresponding to the DPWM modulation mode. .

[0077] It can be understood that the DPWM modulation mode corresponds to a variety of modulation strategies, and the coefficients corresponding to each modulation strategy are the same, and the methods for calculating the corresponding first zero-sequence voltage are also different. Taking DPWM1 as an example, a possible method for determining the above-mentioned first zero-sequence voltage includes: determining the maximum and minimum values ​​of the above-mentioned three-phase reference voltage, and determining the calculation method of the above-mentioned first zero-sequence voltage according to the modulation degree corresponding to DPWM1, as well as the above-mentioned maximum and minimum values, and then calculating the above-mentioned first zero-sequence voltage according to the calculation method. Exemplarily, the maximum and minimum values ​​of the three-phase reference voltage are determined by the following formula:

[0078]

[0079] in, is the maximum value of the above three-phase reference voltage, The minimum value of the above three-phase reference voltage, for Phase reference voltage, for Phase reference voltage, for Phase reference voltage.

[0080] In addition, based on the modulation index corresponding to DPWM1, and the maximum value and the minimum value, the first zero-sequence voltage is determined. In the case of, the first zero-sequence voltage is determined by the following formula:

[0081]

[0082] in, is the first zero-sequence voltage mentioned above, is the maximum value of the above three-phase reference voltage, The minimum value of the above three-phase reference voltage;

[0083] In the above modulation system In the case of, the first zero-sequence voltage is determined by the following formula:

[0084]

[0085] in, is the first zero-sequence voltage mentioned above, is the maximum value of the above three-phase reference voltage, The minimum value of the above three-phase reference voltage.

[0086] Optionally, when the modulation strategy corresponding to the DPWM modulation mode is DPWMA, a possible method for determining the first zero-sequence voltage corresponding to the three-phase reference voltage of the converter includes: for each reference voltage in the three-phase reference voltage, determining the first distance and the second distance of each reference voltage from the first upper limit and the first lower limit respectively; determining the minimum distance from the first distance and the second distance of the three-phase reference voltage, and determining the minimum distance as the first zero-sequence voltage. For the first zero-sequence voltage, a first upper limit and a first lower limit are preset, for example, the first upper limit is "1" and the first lower limit is "0".

[0087] S306 , respectively superimpose the three-phase reference voltage and the first zero-sequence voltage to obtain a three-phase modulated voltage.

[0088] Among them, one phase voltage of the three-phase modulated voltage is clamped to a fixed voltage value at any time.

[0089] Specifically, after obtaining the first zero-sequence voltage corresponding to the three-phase reference voltage, the first zero-sequence voltage is superimposed on the three-phase reference voltage to obtain the three-phase modulation voltage. Figure 5 As shown, according to the three-phase reference voltage U sin ref a , U sin ref b and U sin ref c Get the first zero-sequence voltage u zsv After that, u zsv Superimposed on U sin ref a , U sin ref b and U sin ref c , get the three-phase modulation voltage U ref a , U ref b and U ref c .

[0090] It can be understood that after the first zero-sequence voltage is superimposed on the above-mentioned three-phase reference voltages, the obtained three-phase modulated voltage has one phase voltage clamped to a fixed voltage value at any time. For example, the three-phase modulated voltage has one phase voltage clamped to a position of "0", "1" or "-1" at any time. Since the three-phase modulated voltage obtained by this method has one phase voltage clamped to a position of "0", "1" or "-1" at any time, and the switch state corresponding to the clamping interval remains unchanged, this method effectively reduces the number of switching times of the switch tube, thereby reducing the switching loss of the converter.

[0091] S307. When the target modulation mode is the CPWM modulation mode, determine a second zero-sequence voltage corresponding to the three-phase reference voltage of the converter; and superimpose the three-phase reference voltage and the second zero-sequence voltage respectively to obtain a three-phase modulation voltage.

[0092] Specifically, when the target modulation mode is the CPWM modulation mode, the corresponding second zero-sequence voltage is determined according to the three-phase reference voltage, and the second zero-sequence voltage is respectively superimposed on the three-phase reference voltage to obtain the corresponding three-phase modulation voltage. The second zero-sequence voltage may be, for example, a zero-sequence third harmonic voltage component. The waveform of the obtained three-phase modulation voltage is a saddle shape when the zero-sequence third harmonic voltage component is superimposed on the reference voltage of each phase, which is conducive to improving the utilization rate of the DC voltage.

[0093] Optionally, the second zero-sequence voltage corresponding to the three-phase reference voltage of the converter is determined by the following formula:

[0094]

[0095] in, for Phase reference voltage, for Phase reference voltage, for Phase reference voltage, is the maximum value of the above three-phase reference voltage, The minimum value of the above three-phase reference voltage, is the second zero-sequence voltage corresponding to the above three-phase reference voltage. The method can eliminate and suppress high-order harmonics, reduce harmonic distortion, and improve the utilization rate of DC voltage.

[0096] The embodiment of the present application provides a time-sharing switching modulation method of DPWM and CPWM of a converter, which monitors the phase value of a first reference voltage in real time to determine whether the phase value is within the phase value range corresponding to the DPWM modulation mode. If so, the target modulation mode is determined to be the DPWM modulation mode, and when the current modulation mode is not the above-mentioned DPWM modulation mode, the above-mentioned current modulation mode is switched to the DPWM modulation mode, and then the first zero-sequence voltage corresponding to the three-phase reference voltage of the converter is determined, and the first zero-sequence voltage is respectively superimposed on the above-mentioned three-phase reference voltage to obtain the corresponding three-phase modulation voltage. In addition, when the above-mentioned phase value is not within the phase value range corresponding to the DPWM modulation mode, the target modulation mode is determined to be the CPWM modulation mode, and when the current modulation mode is not the above-mentioned CPWM modulation mode, the above-mentioned current modulation mode is switched to the CPWM modulation mode, and then according to the three-phase reference voltage of the converter, the corresponding second zero-sequence voltage is determined, and the second zero-sequence voltage is superimposed on the above-mentioned three-phase reference voltage to obtain the three-phase modulation voltage. Among them, the three-phase modulation voltage is used to compare with the triangular carrier of the converter to obtain the three-phase switching signal of the converter. The method determines the target modulation mode in the high voltage region as the DPWM modulation mode and the target modulation mode in the low voltage region as the CPWM modulation mode through the phase value, thereby reducing the switching loss and the harmonic distortion of the DC capacitor, thereby increasing the service life of the converter. In addition, in the CPWM modulation mode, the method is conducive to improving the utilization rate of the DC voltage by injecting the second zero-sequence voltage into the reference voltage of each phase.

[0097] Figure 7 A schematic diagram of the structure of a pulse width modulation device provided in this application, such as Figure 7 As shown, the pulse width modulation device 70 provided in this embodiment includes:

[0098] A monitoring module 701, configured to monitor in real time a phase value of a first reference voltage, wherein the first reference voltage is determined from a three-phase reference voltage of the converter;

[0099] A determination module 702 is used to determine a target modulation mode corresponding to the phase value;

[0100] A judging module 703 is used to judge whether the current modulation mode is consistent with the target modulation mode;

[0101] A switching module 704, configured to switch the current modulation mode to the target modulation mode when the current modulation mode is inconsistent with the target modulation mode;

[0102] The modulation module 705 is used to perform pulse width modulation on the three-phase reference voltage using the target modulation mode to obtain a three-phase modulated voltage. The three-phase modulated voltage is used to compare and process with the triangular carrier of the converter to obtain a three-phase switching signal of the converter.

[0103] In a possible implementation, the target modulation mode includes: a CPWM modulation mode and a DPWM modulation mode, the CPWM modulation mode and the DPWM modulation mode have different phase value ranges, and the judgment module 703 is further used to judge whether the phase value is within the phase value range corresponding to the DPWM modulation mode;

[0104] The determination module 702 is further configured to determine that the target modulation mode is the DPWM modulation mode;

[0105] The determination module 702 is further configured to, if not, determine that the target modulation mode is the CPWM modulation mode.

[0106] In a possible implementation, the apparatus further includes: a processing module 706;

[0107] The determination module 702 is further configured to determine a zero-sequence voltage corresponding to the three-phase reference voltage of the converter when the target modulation mode is the DPWM modulation mode;

[0108] The processing module 706 is used to perform superposition processing on the three-phase reference voltage and the zero-sequence voltage respectively to obtain the three-phase modulated voltage, wherein at any time, one phase voltage of the three-phase modulated voltage is clamped to a fixed voltage value;

[0109] The determination module 702 is further configured to determine a carrier wave corresponding to the three-phase reference voltage of the converter when the target modulation mode is the CPWM modulation mode;

[0110] The processing module 706 is further configured to respectively superimpose the three-phase reference voltage and the carrier to obtain the three-phase modulation voltage.

[0111] In a possible implementation, the processing module 706 is further configured to determine the phase value range corresponding to the DPWM modulation mode by using the following formula:

[0112]

[0113] in, is the phase value, is an integer, is the preset parameter corresponding to the DPWM modulation mode, The range is .

[0114] In a possible implementation, the monitoring module 701 is specifically configured to perform phase locking on the first reference voltage through the phase-locked loop to obtain a phase value of the first reference voltage at a current moment.

[0115] The pulse width modulation device provided in this embodiment can execute a time-sharing switching modulation method of converter DPWM and CPWM provided in the above method embodiment. Its implementation principle and technical effect are similar, and this embodiment will not be described in detail here.

[0116] The present application also provides a pulse width modulation system, which is applied to an inverter, and the pulse width modulation system includes: a monitoring unit, which is used to monitor the phase value of a first reference voltage in real time, wherein the first reference voltage is determined from the three-phase reference voltage of the inverter; a modulation mode determination unit, which is used to receive the phase value sent by the phase-locked loop of the inverter, and determine the target modulation mode corresponding to the three-phase reference voltage according to the phase value; a modulation mode switching unit, which is used to determine whether the current modulation mode is consistent with the target modulation mode, and if the current modulation mode is inconsistent with the target modulation mode, switch the current modulation mode to the target modulation mode; a modulation unit, which is used to perform pulse width modulation on the three-phase reference voltage using the target modulation mode to obtain a three-phase modulation voltage, and the three-phase modulation voltage is used for comparison processing with the triangular carrier of the inverter to obtain a three-phase switching signal of the inverter.

[0117] It can be understood that the pulse width modulation system provided in the embodiment of the present application is used to execute and implement the above-mentioned time-sharing switching modulation method of the converter DPWM and CPWM, so as to achieve the technical effect of reducing the harmonic distortion of the converter while reducing the switching loss of the converter, thereby improving the performance and life of the converter.

[0118] The present application also provides a converter, which includes: a phase-locked loop, a comparator and a pulse width modulation system, wherein the pulse width modulation system is connected to the phase-locked loop and the comparator respectively, and the pulse width modulation system is the above-mentioned pulse width modulation system; the phase-locked loop is used to phase-lock a first reference voltage of the converter to obtain a phase value of the first reference voltage at a current moment, and the first reference voltage is determined from the three-phase reference voltage of the converter; the comparator is used to receive the three-phase modulation voltage sent by the pulse width modulation system, and compare the three-phase modulation voltage with a triangular carrier to obtain a three-phase switching signal of the converter.

[0119] It can be understood that the converter provided in the embodiment of the present application is used to execute and implement the above-mentioned converter DPWM and CPWM time-sharing switching modulation method to reduce the switching loss of the converter while reducing the harmonic distortion of the converter, thereby improving the performance and life of the converter.

[0120] The present application also provides a computer program product, including a computer program, which implements the above-mentioned time-sharing switching modulation method of DPWM and CPWM of a converter when executed by a processor.

[0121] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above-mentioned time-sharing switching modulation method of the converter DPWM and CPWM is implemented.

[0122] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0123] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0124] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0125] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0126] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0127] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0128] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0129] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A time-sharing switching modulation method for DPWM and CPWM of a converter, characterized in that: Applied to a converter, the method comprises: Monitor the phase value of a first reference voltage in real time, and determine a target modulation mode corresponding to the phase value, wherein the first reference voltage is determined from a three-phase reference voltage of the converter, and the target modulation mode includes a CPWM modulation mode and a DPWM modulation mode; Determining whether the current modulation mode is consistent with the target modulation mode; In the case where the current modulation mode is inconsistent with the target modulation mode, the current modulation mode is switched to the target modulation mode, and the three-phase reference voltage is pulse-width modulated using the target modulation mode to obtain a three-phase modulated voltage; The three-phase modulation voltages are modulated respectively based on the triangular carrier pair of the converter to obtain corresponding three-phase switching signals.

2. The method according to claim 1, characterized in that The phase value ranges corresponding to the CPWM modulation mode and the DPWM modulation mode are different, and determining the target modulation mode corresponding to the phase value includes: Determining whether the phase value is within the phase value range corresponding to the DPWM modulation mode; If yes, determining that the target modulation mode is the DPWM modulation mode; If not, it is determined that the target modulation mode is the CPWM modulation mode.

3. The method according to claim 2, characterized in that The method of adopting the target modulation mode to perform pulse width modulation on the three-phase reference voltage to obtain a three-phase modulated voltage includes: When the target modulation mode is the DPWM modulation mode, determining a first zero-sequence voltage corresponding to the three-phase reference voltage of the converter; Superimposing the three-phase reference voltage and the first zero-sequence voltage respectively to obtain the three-phase modulated voltage, wherein at any time, one phase voltage of the three-phase modulated voltage is clamped to a fixed voltage value; When the target modulation mode is the CPWM modulation mode, determining a second zero-sequence voltage corresponding to the three-phase reference voltage of the converter; The three-phase reference voltage and the second zero-sequence voltage are respectively superimposed to obtain the three-phase modulation voltage.

4. The method according to claim 2, characterized in that: The phase value range corresponding to the DPWM modulation mode is determined by the following formula: in, is the phase value, is an integer, is the preset parameter corresponding to the DPWM modulation mode, The range is .

5. The method according to claim 1, characterized in that The converter comprises: a phase-locked loop, and the real-time monitoring of the phase value of the first reference voltage comprises: The first reference voltage is phase-locked by the phase-locked loop to obtain a phase value of the first reference voltage at a current moment.

6. A time-sharing switching modulation device for DPWM and CPWM of a converter, characterized in that: include: A monitoring module, configured to monitor in real time a phase value of a first reference voltage, wherein the first reference voltage is determined from a three-phase reference voltage of the converter; A determination module, used to determine a target modulation mode corresponding to the phase value; A judging module, used to judge whether the current modulation mode is consistent with the target modulation mode; A switching module, configured to switch the current modulation mode to the target modulation mode when the current modulation mode is inconsistent with the target modulation mode; A modulation module, used for performing pulse width modulation on the three-phase reference voltage by adopting the target modulation mode to obtain a three-phase modulated voltage; The modulation module is further used to modulate the three-phase modulation voltages respectively based on the triangular carrier pair of the converter to obtain corresponding three-phase switching signals.

7. A pulse width modulation system, characterized in that: Applied to a converter, the pulse width modulation system comprises: A monitoring unit, configured to monitor in real time a phase value of a first reference voltage, wherein the first reference voltage is determined from a three-phase reference voltage of the converter; A modulation mode determination unit, configured to receive a phase value sent by a phase-locked loop of the converter, and determine a target modulation mode corresponding to the three-phase reference voltage according to the phase value; A modulation mode switching unit, configured to determine whether a current modulation mode is consistent with the target modulation mode, and switch the current modulation mode to the target modulation mode if the current modulation mode is inconsistent with the target modulation mode; The modulation unit is used to perform pulse width modulation on the three-phase reference voltage using the target modulation mode to obtain a three-phase modulated voltage, and compare the three-phase modulated voltage with the triangular carrier of the converter to obtain a corresponding three-phase switching signal.

8. A converter, characterized in that: The converter comprises: a phase-locked loop, a comparator and a pulse width modulation system; The pulse width modulation system is connected to the phase-locked loop and the comparator respectively, and the pulse width modulation system is the pulse width modulation system according to claim 7; The phase-locked loop is used to phase-lock a first reference voltage of the converter to obtain a phase value of the first reference voltage at a current moment, wherein the first reference voltage is determined from a three-phase reference voltage of the converter; The comparator is used to receive the three-phase modulation voltage sent by the pulse width modulation system, and compare the three-phase modulation voltage with a triangular carrier to obtain a three-phase switching signal of the converter.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 5 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 5 when being executed by a processor.

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