Method for generating a control signal for pulse width modulation, converter and computer program product

Abstract

A method is disclosed comprising receiving a voltage request (102), generating a first signal (112), generating a second signal (114), selecting one of the first signal (112) and the second signal (114) as a selected signal (121), and generating a control signal (132) for pulse width modulation based on the voltage request (102) and the selected signal (121). A converter and a computer program product are also disclosed.

Description

Technical Field

[0001] This disclosure relates to the field of pulse width modulation. Background Technology

[0002] The article “A High-Performance Generalized Discontinuous PWM Algorithm” in IEEE Transactions on Industry Applications, Vol. 34, No. 5, pp. 1059-1071 describes a discontinuous pulse width modulation method. Summary of the Invention

[0003] In view of the above, a technology may be needed that allows for a method for generating control signals for pulse width modulation, and a corresponding converter, with improved characteristics.

[0004] This need can be met through the independent claims. Some advantageous embodiments are indicated in the dependent claims.

[0005] Based on the first aspect of the subject matter disclosed in this article, a method is provided.

[0006] According to an embodiment of the first aspect, a method is provided, the method comprising: receiving a voltage request; generating a first signal; generating a second signal; selecting one of the first signal and the second signal as a selected signal; and generating a control signal for pulse width modulation based on the voltage request and the selected signal.

[0007] According to the second aspect of the subject matter disclosed herein, a converter is provided.

[0008] According to a second aspect of the embodiment, a converter is provided, the converter including a control device, wherein the control device is configured to receive a voltage request; wherein the control device is configured to generate a first signal and generate a second signal; wherein the control device is configured to select one of the first signal and the second signal as a selected signal; and wherein the control device is configured to generate a control signal for pulse width modulation based on the voltage request and the selected signal.

[0009] According to a third aspect of the subject matter disclosed herein, a computer program product is provided.

[0010] According to an embodiment of the third aspect, a computer program product is provided, the computer program product including a program unit configured to control the method according to the first aspect when executed on a processor device.

[0011] Although certain disadvantages of the prior art have been mentioned herein, the claimed subject matter is not limited to implementations that address some or all of the aforementioned disadvantages of the prior art. Furthermore, even if certain advantages of the subject matter disclosed herein are mentioned or implied in this disclosure, the claimed subject matter is not limited to implementations having some or all of these advantages.

[0012] In the following, exemplary embodiments of the subject matter disclosed herein will be described, including, for example, reference methods, converters, and computer program products. It should be emphasized that, of course, any combination of features from different aspects, embodiments, and examples is possible. In particular, some embodiments relating to methods are described, while others relate to computer program products. Again, other embodiments are described in relation to devices (particularly converters), while others are described in relation to control means for interacting with elements of the device. However, those skilled in the art will realize from the above and below description, the claims, and the drawings that, unless otherwise stated, features from different aspects, embodiments, and examples are combinable, and such combinations of features are considered to be disclosed herein. For example, a feature related to a method can itself be combined with a feature related to a device, and vice versa.

[0013] Exemplary implementations of the subject matter disclosed herein include, in particular, one or more of the embodiments described herein and combinations thereof.

[0014] According to one embodiment, the method of the first aspect is a method for generating a control signal for pulse width modulation. According to one embodiment, the method includes receiving a voltage request (also called a voltage command), for example, a voltage request determined by a current regulator. According to another embodiment, the method includes generating a first signal and a second signal. For example, the first signal is a first injection signal, and the second signal is a second injection signal. According to one embodiment, as described herein, the injection signal is configured to be directed to another signal.

[0015] According to another embodiment, the method includes selecting one signal from a first signal and a second signal as the selected signal. According to one embodiment, the selection is performed using a selection criterion. In other words, according to one embodiment, the method is configured to select either the first signal or the second signal as the selected signal when using a selection criterion. According to another embodiment, the method includes generating a control signal for pulse width modulation, for example based on a voltage request and the selected signal, when using the selected signal.

[0016] According to the second aspect, the converter, in one embodiment, is a converter with a control device. In one embodiment, the control device is configured to receive a voltage request. In another embodiment, the control device is configured to generate a first signal and a second signal. In another embodiment, the control device is configured to select one signal from the first and second signals as the selected signal when using a selection criterion. In yet another embodiment, the control device is configured to generate a control signal for pulse width modulation, for example, based on the voltage request and the selected signal, when using the selected signal.

[0017] The computer program product according to the third aspect is configured, according to one embodiment, to control the method disclosed herein, particularly the method according to at least one embodiment of the first aspect.

[0018] At least some aspects and embodiments of the subject matter disclosed herein are based on the idea that a method for generating control signals for pulse width modulation (PWM) can be provided with improved characteristics by generating control signals for PWM based on voltage requests and on a selected signal chosen from two different signals using a selection criterion. Specifically, according to one embodiment, the selection criterion can be configured to provide a large time window for current measurement within one PWM cycle. The size of the time window available for current measurement can be optimized by adjusting the selection criterion (e.g., by setting a threshold in one embodiment). For example, according to one embodiment, a time window for current measurement can be provided even at high modulation indices because embodiments of the subject matter disclosed herein avoid switching conflicts of inverters operating with PWM. In other words, embodiments of the subject matter disclosed herein avoid the disadvantages of conventional PWM methods, particularly the shrinking of the available time window for current measurement as the modulation indices increase (or as voltage requests increase). Embodiments of the method disclosed herein allow this disadvantage to be completely overcome.

[0019] According to one embodiment, a first signal and / or a second signal are generated from a voltage request. For example, according to one embodiment, the first signal and / or the second signal are derived from a modulation index generated by the voltage request.

[0020] According to one embodiment, a first signal or a second signal is selected as the selected signal when a voltage request is used. In other words, the selection criterion uses a voltage request. For example, according to one embodiment, the first signal or the second signal is selected as the selected signal when at least one derived quantity derived from the voltage request is used. According to one embodiment, the first signal or the second signal is selected based on the difference between the first signal and the second signal.

[0021] According to another embodiment, a first signal or a second signal is selected as the selected signal when a threshold is used.

[0022] In a combination of the above embodiments, according to one embodiment, the selection criteria use a quantity and threshold derived from the voltage request.

[0023] According to one implementation, the voltage request is periodic and a period duration is defined. For example, the voltage request is a sinusoidal signal, which in one implementation is generated by a current regulator.

[0024] According to another embodiment, a first signal is selected during a first portion of the cycle duration, and a second signal is selected during a second portion of the cycle duration. In other words, during a single cycle of the voltage request, a control signal is generated partly using the first signal and partly using the second signal. For example, according to one embodiment, during a single cycle of the voltage request, the selected signal is changed from the first signal to the second signal at least once, and / or vice versa.

[0025] According to one embodiment, the first signal is the third harmonic of the voltage request and / or the second signal is the third harmonic of the voltage request. In other words, the frequencies of the first signal and / or the second signal are three times higher than the frequency of the voltage request.

[0026] According to one embodiment, the method or converter is configured for a multiphase system. According to one embodiment, the voltage request includes a component for each phase of the multiphase system. According to another embodiment, the control signal includes a component for each phase of the multiphase system. For example, the multiphase system is a three-phase system. According to yet another embodiment, a selected signal is used for each phase of the multiphase system. In other words, (e.g., at any given time) the control signal for each phase is generated using the same selected signal.

[0027] According to one embodiment, the first signal and / or the second signal are derived from the components of the voltage-requested phase.

[0028] According to one implementation, the minimum and maximum values ​​of the quantity derived from the voltage request are determined based on the components of the voltage request. For example, according to one implementation, the minimum and maximum values ​​of the quantity derived from the voltage request are determined based on all components of the voltage request. The quantity derived from the voltage request may be, for example, a modulation index. In other words, in one implementation, the minimum and maximum modulation indices are determined based on the (i.e., all) components of the voltage request (e.g., in the modulation indices of a phase).

[0029] In one implementation, the minimum value is a first signal and the maximum value is a second signal. In another implementation, the first signal or the second signal is selected as the chosen signal based on (e.g., based on, among other things) the first signal and the second signal. For example, the first signal or the second signal is selected based on the difference between the first signal and the second signal and based on a threshold.

[0030] For example, according to one embodiment, the first signal is selected as the chosen signal when the difference between the maximum and minimum values ​​(or the difference between the first and second signals) is greater than or equal to a threshold, and the second signal is selected as the chosen signal when the difference between the maximum and minimum values ​​is less than the threshold. According to one embodiment, the threshold is located in the range between 0.08 and 0.095 when compared to the difference between the threshold and the modulation index (i.e., a value between 0 and 1 or between 0% and 100%). According to one embodiment, the threshold is 0.09 (i.e., 9%). According to one embodiment, the control signal (e.g., a pulse width modulation mode) generated according to the embodiments of the subject matter disclosed herein ensures that no switching occurs near the current measurement point (the time point of current measurement). The inventors found through simulation that, surprisingly, the 9% threshold provides a wide current measurement time window (current measurement window). In one embodiment, the 9% threshold provides the widest current measurement window. Whenever the width of the current measurement window is mentioned herein, it refers to the width on the time axis; that is, a wide current measurement window provides a longer duration for current measurement. According to one embodiment, 9% of the pulse width modulation period (which corresponds to the period duration of the voltage request) is always free of switching operations, and therefore conflict-free current measurements (e.g., in a three-phase system, between two of the three phases) can be performed independently of the modulation index. During this period, the current measurement window is open for at least two of the three phases (in a three-phase system), and current measurements can be performed. Compared to conventional methods, limiting the modulation index to enable current measurements is not necessary in the method according to the embodiments of the subject matter disclosed herein.

[0031] According to other implementations, values ​​other than 9% (i.e., greater than 9% or less than 9%) can be used, but in one implementation this results in a smaller current measurement window.

[0032] In one embodiment, a control signal controls pulse width modulation in the inverter. In another embodiment, the inverter draws energy from a DC circuit. In one embodiment, the modulation index is defined as the quotient of the voltage request divided by the measured DC voltage of the DC circuit.

[0033] According to one embodiment, an intermediate signal is generated from a voltage request, and a selected signal is injected into the intermediate signal to generate a control signal. For example, according to one embodiment, the control signal is the sum of the selected signal and a derived amount derived from the voltage request. For example, according to one embodiment, the control signal is the sum of the modulation index and the selected signal. For example, in a multiphase system, the control signal in one phase is the sum of the modulation index of that phase and the selected signal.

[0034] In one embodiment, the program unit is a non-transient program unit. In another embodiment, the computer program product is a non-transient computer program product.

[0035] As used herein, references to a computer program product having program units are considered equivalent to references to a computer program having program units and / or a computer-readable medium having program units. According to one embodiment, a program unit includes instructions for controlling a processing device (having one or more microprocessors, such as a computer system) to cause and / or coordinate the execution of at least one method described herein. The (non-transient) program unit may be implemented as computer-readable instruction code using any suitable programming language (such as C, C++, or assembly language, etc.) and may be stored on a computer-readable medium (removable disk, volatile or non-volatile memory, embedded memory / processor, etc.). According to one embodiment, the instruction code is executable to program a computer or any other programmable processing device to perform a intended function. The computer program may be available on a network (e.g., the World Wide Web) from which it may be downloaded.

[0036] The subject matter disclosed herein can be implemented through a computer program product (program unit) or software. However, the subject matter disclosed herein can also be implemented through one or more specific electronic circuits (or hardware). Furthermore, the subject matter disclosed herein can also be implemented in a hybrid form, i.e., in a combination of software modules and hardware modules.

[0037] According to one embodiment, one or more control devices and regulators disclosed herein may have processing means configured to execute the program units disclosed herein.

[0038] According to an embodiment of the first aspect, the method is configured to implement one or more embodiments disclosed herein to provide functionality of one or more embodiments disclosed herein, to provide functionality necessary for one or more embodiments disclosed herein, and / or to provide functionality required by one or more embodiments disclosed herein (particularly embodiments of the first, second, and / or third aspects).

[0039] According to an embodiment of the second aspect, the converter is configured to implement one or more embodiments disclosed herein, provide the functionality of one or more embodiments disclosed herein, provide functionality necessary for one or more embodiments disclosed herein, and / or provide functionality required by one or more embodiments disclosed herein (particularly embodiments of the first, second, and / or third aspects).

[0040] According to the third aspect of the implementation, the computer program product is configured to implement one or more embodiments disclosed herein to provide the functionality of one or more embodiments disclosed herein, to provide functionality necessary for one or more embodiments disclosed herein, and / or to provide functionality required by one or more embodiments disclosed herein (particularly embodiments of the first, second, and / or third aspects).

[0041] It should be noted that references to aspects of the subject matter disclosed herein naturally include references to one or more embodiments of that aspect. For example, a description of a program unit controlling a method according to the first aspect includes an embodiment of a program unit configured to control a method according to one or more embodiments of the first aspect. Therefore, a description of a method according to the first aspect includes an embodiment constructed according to the method according to one or more embodiments of the first aspect (and / or the second and / or the third aspect).

[0042] Unless otherwise stated, numerical values ​​should be understood to include a ±5% window, i.e., a threshold of 0.09, according to one embodiment, is included within the range of (0.09 ± 0.09 5%) = [0.0855; 0.0945], and a 9% percentage, according to one embodiment, is included within the range of 9% ± 9% 5% = [8.55%; 9.45%]. According to another embodiment, numerical values ​​and / or percentages should be understood to include a ±10% window.

[0043] According to one embodiment, the methods disclosed herein can define the functionality of the disclosed device, rather than being limited to device-specific features. Therefore, each function of the disclosed device implicitly discloses a corresponding method defined solely by the disclosed function. Conversely, according to one embodiment, the methods disclosed herein can be performed using any suitable known device (which may have a single element or multiple cooperating elements). Therefore, each method disclosed herein implicitly discloses a corresponding device configured to perform the method.

[0044] General references to embodiments (e.g., methods) are made, for example by stating “according to at least one embodiment,” “according to one or more embodiments,” or “according to some embodiments,” and particularly include combinations of features of the respective independent claims, without further limitation (e.g., the method according to claim 1).

[0045] Unless otherwise explicitly stated, the listing of features or process steps according to one embodiment does not limit the order in which the features or process steps are listed. According to another embodiment, the listing of features or process steps limits the order of the features or process steps as shown in the listing.

[0046] In some embodiments, a feature is referred to with an indefinite article when it first appears, as is the case, for example, when describing embodiments of the first aspect and embodiments of the second aspect. However, it should be understood that the use of indefinite or definite articles in this invention is not limiting, and features mentioned in different embodiments, whether indicated with a qualifying article or an indefinite article, refer to the same feature at least in one embodiment. Therefore, in combinations of different embodiments, the feature can be referred to with an indefinite article when it first appears and with a definite article when it subsequently appears. Furthermore, according to one embodiment, features mentioned with a definite article can be constructed independently of the previously described embodiments. Additionally, in one embodiment, the first and second aspects are two different aspects of the same basic idea.

[0047] It should be noted that, unless otherwise explicitly stated, numerals (first, second, third, etc.) are used only to identify different elements (e.g., signals), and numerals do not imply the order of steps, nor do they require or imply the presence of another different element. For example, merely mentioning the second signal does not require that the first signal occurred before the second signal. Furthermore, mentioning the second signal itself does not require that the first signal already exists or is expected.

[0048] Further advantages and features of the invention will emerge from the following exemplary description of presently preferred embodiments, but the claimed subject matter is not limited thereto. The various figures in this document should be considered illustrative and non-to-scale only. Attached Figure Description

[0049] Figure 1 A block diagram of the algorithm of the method according to the subject matter disclosed herein is shown.

[0050] Figure 2 Figures 6 to 6 illustrate embodiments of the subject matter disclosed herein. Figure 1 The description relates to the time-varying curves of the signal and its value.

[0051] Figure 7 illustrates an inverter according to an embodiment of the subject matter disclosed herein. Detailed Implementation

[0052] It should be noted that similar or identical elements or components in different figures are labeled with the same reference numerals, or with reference numerals that differ only in their leading numerals or suffixes. For such features or components that are identical or at least functionally identical to their corresponding features or components in another figure, they will be described in detail only upon their first appearance, and will not be described again when the feature or component (or its corresponding reference numeral) appears subsequently. If an element appears multiple times in a figure, for clarity, in some cases it may not be necessary to label all of the element with a reference numeral. Of course, the corresponding description also applies to elements without reference numerals.

[0053] It is understood that, unless otherwise stated, exemplary embodiments of the elements described below and labeled with reference numerals are presented in the associated drawings and configured in accordance with the description given in the drawings.

[0054] Figure 1 A block diagram 100 illustrating an algorithm for a method according to an embodiment of the subject matter disclosed herein is shown.

[0055] Block diagram 100 can be implemented, for example, in the control device of a converter. According to one embodiment, the method includes receiving a voltage request 102. According to one embodiment (in the case of a three-phase system), the voltage request 102 has three components 104, 204, and 304, which... Figure 1 It is also known as V U V V and V W Each component represents a voltage request for a given phase U, V, or W of the three-phase system. According to one embodiment, the time-varying curve of each of the three components 104, 204, and 304 of the voltage request 102 is sinusoidal. These three components 104, 204, and 304 (V...) U V V and V W This is also referred to in this document as the voltage request of “related phases U, V, W”.

[0056] Furthermore, according to one embodiment, the method includes receiving a DC voltage 106 from a DC circuit, such as a DC circuit from which a converter draws electrical energy to provide output power. The DC voltage 106 is... Figure 1 It is also known as V DC .

[0057] According to one embodiment, modulation indices 108, 208, and 308 are calculated from each component 104, 204, and 304 of the voltage request 102, which correspond to the corresponding phases U, V, and W. Figure 1 It is also known as M U M V and M W According to one implementation, for each of the three phases, the modulation index M... U M V M W Defined as the quotient of the voltage requests 104, 204, and 304 for the relevant phases U, V, and W divided by the DC voltage 106 of the DC circuit:

[0058] M U =V U / V DC

[0059] M V =V V / V DC

[0060] M W =V W / V DC

[0061] Therefore, the modulation index is a quantity derived from voltage request 102.

[0062] According to one implementation, the modulation indices 108, 208, and 308 are calculated in the modulation index calculation block 110.

[0063] According to one implementation, a minimum value of 112 and a maximum value of 114 are determined from all three modulation indices 108, 208, and 308.

[0064] According to one implementation, the minimum value is 112—which is in Figure 1 It is also known as M min — Defined as

[0065] M min =0-min(M) U M V M W ),

[0066] Where the function min(M) U M V M W The minimum of the three modulation indices is provided as a function value.

[0067] Since in one embodiment one of the three components of voltage request 102 is always negative, therefore in this embodiment M minOverall, it is positive, and in one embodiment, it represents the minimum modulation index among the three modulation indices 108, 208, and 308 of the three phases U, V, and W, and the minimum possible voltage requirement (V). DC The distance between 0% and 0%. According to one embodiment, intuitively, in the relevant phase providing the minimum of the three modulation indices, the time variation curve of the minimum value 112 relative to the voltage request 102 is mirrored on an axis parallel to the time axis. According to one embodiment, the minimum value 112 is provided by a calculation block 113, for example, as... Figure 1 As shown.

[0068] According to another implementation, the maximum value is 114—which is in Figure 1 It is also known as M max — Defined as

[0069] M max =1-max(M) U M V M W ),

[0070] The function max(M) U M V M W The maximum of the three modulation indices is provided as the function value.

[0071] Since one of the three components of voltage request 102 is always positive and less than or equal to 1 (V DC (100%), therefore the maximum value is 114M max It is always positive, and in one implementation, it represents the maximum modulation index among the modulation indices 108, 208, and 308 of the three phases U, V, and W, and the maximum possible voltage demand (V). DC The distance between (100%). According to one embodiment, intuitively, in the relevant phase providing the maximum value among the three modulation indices, the time variation curve of the maximum value 114 relative to the voltage request 102 is mirrored on an axis parallel to the time axis. According to one embodiment, the maximum value 114 is provided by calculation block 115, for example, as... Figure 1 As shown.

[0072] Since the other two phases also have a maximum peak value within one cycle of phases U, V, and W, there are three maximum peak values ​​within one cycle of the three phases. Therefore, the maximum value M... max The frequency of the time-varying curve of 114 is three times the frequency of the time-varying curves of each component of voltage request 102, namely 104, 204, and 304. Similarly, the minimum value M... minThe frequency of the time variation curve of 112 is also three times the frequency of the time variation curves of each component of voltage request 102, namely 104, 204, and 304.

[0073] According to one implementation, the minimum value M min 112 is also referred to here as the first signal, and the maximum value M max 114 is also referred to here as the second signal.

[0074] According to one embodiment, a minimum value 112 or a maximum value 114 is selected as the selected signal 121 based on a minimum value, a maximum value, and a threshold. For example, the minimum value 112 or the maximum value 114 is selected as the selected signal based on a threshold and a difference 116 between the minimum value 112 and the maximum value 114. According to one embodiment, the difference 116 is formed by a subtractor (difference former or subtraction block) 117, and... Figure 1 M is also used in the middle. diff In one embodiment, the minimum value 112 and the maximum value 114 are the input values ​​of the subtractor 117. In one embodiment, the subtractor 117 is configured to subtract the minimum value 112 from the maximum value 114, for example... Figure 1 As shown. According to one implementation, if the difference 116 is greater than or equal to a threshold, the minimum value 112 is selected (and thus the selected signal is formed). According to another implementation, if the difference 116 is less than a threshold, the maximum value 114 is selected (and thus the selected signal is formed). In other words, according to one implementation, if question 118 "Is the difference 116 less than the threshold?" is answered "no" (in... Figure 1 (As indicated at point 120), then select the minimum value 112, and if question 118 "Is the difference 116 less than the threshold?" is answered "yes" (in...) Figure 1 If the value is indicated at point 122, then the maximum value 114 is selected. According to one embodiment, based on the answer to question 118, either the minimum value 112 or the maximum value 114 is injected into the modulation indices 108, 208, and 308 of each phase. According to one embodiment, the selective injection of the selected signal (i.e., in the implementation of minimum value 112 or maximum value 114) into the modulation indices 108, 208, and 308 is achieved by adding the selected signal 121 to the modulation indices 108, 208, and 308 of each of the three phases U, V, and W.

[0075] According to one embodiment, a minimum value 112 is selected by closing switch 126, which couples the output of calculation block 113 to adder (summer) 128. This adder adds the selected signal 121 (here, the minimum value 112) to each of the modulation indices 108, 208, and 308 of each phase U, V, and W, thereby providing components 130, 230, and 330 of control signal 132 for pulse width modulation for each phase U, V, and W. The components 130, 230, and 330 of control signal 132 are... Figure 1 M is also used in the middle. Uinj M Vinj and M Winj This indicates that the injected signal 121 is also represented by M. inj express.

[0076] According to one embodiment, a maximum value 114 is selected by closing a switch 134, which couples the output of calculation block 115 to an adder (e.g., adder 128) that adds the selected signal 121, i.e., the injection signal (here, the maximum value 114), to each of the modulation indices 108, 208, 308 of each phase U, V, W, so as to thereby provide components 130, 230, 330 of the control signal 132 for pulse width modulation for each phase U, V, W.

[0077] According to one embodiment, the question 118, "whether the difference 116 is less than a threshold," is addressed in decision block 119. For example, in one embodiment, decision block 119 provides a switching signal 136 to switch switch 126 if the difference 116 is greater than or equal to the threshold, thereby injecting the minimum value 112 into modulation indices 108, 208, and 308. According to another embodiment, decision block 119 provides a switching signal 138 to switch switch 134 if the difference 116 is less than the threshold, thereby injecting the maximum value 114 into modulation indices 108, 208, and 308.

[0078] As explained, block diagram 100 can be implemented, for example, in the control device of the converter. According to one embodiment, portions of block diagram 100, such as individual blocks 110, 113, 115, 117, 119, 128, can be implemented, for example, in software or hardware.

[0079] Figure 2 Figures 6 to 6 illustrate embodiments of the subject matter disclosed herein. Figure 1 The description of the signal and the time-varying curve of its value.

[0080] Here, Figure 2 The modulation indices 108, 208, and 308 with respect to time t are shown for a complete cycle with a duration of 141.

[0081] Figure 3 shows the first signal 112 (minimum value M) with respect to time t. min ) and the second signal 114 (maximum value M) max ).

[0082] Figure 4 illustrates the difference 116 (M) with respect to time t according to an embodiment of the subject matter disclosed herein. diff Together with a threshold 140, which has a value of 0.09, as shown in Figure 4, the intersections 142, 143, 145, and 147 of the time variation curve of the difference 116 with the threshold 140 define the time points at which the switching occurs between the first signal 112 and the second signal 114, symbolized by the dashed line 144 between Figures 3 and 6.

[0083] Figure 5 The injected signal 121 (M) is shown with respect to time t. inj As shown in Figure 3 to... Figure 5 As can be seen from the overview, the first signal 112 is selected during the first portion 146 of the period duration 141, and the second signal 114 is selected during the second portion 148 of the period duration 141. According to one embodiment, the injected signal 121 is a periodic signal. According to another embodiment, the period duration 150 of the injected signal 121 includes two first portions 146, 246 and two second portions 148, 248, for example... Figure 5 As shown. According to one embodiment, the period duration 150 of the injected signal 121 is a modulation index 108, 208, 308 (or a component of voltage request 102 104, 204, 304, see...). Figure 1 The period duration of the injected signal 121 is one-third of 141. In other words, the injected signal 121 is the third harmonic of the modulation index 108, 208, 308 or the voltage request 102.

[0084] Figure 6 illustrates components 130, 230, and 330 of a control signal 132 (also referred to as a pulse width modulation signal) for pulse width modulation according to an embodiment of the subject matter disclosed herein, with respect to time t. According to one embodiment, each component 130, 230, and 330 is formed by adding an injection signal 121 to each of the modulation indices 108, 208, and 308, for example, as... Figure 2 As shown in Figure 6.

[0085] As described in more detail below with reference to Figure 7, an inverter according to some embodiments has a switch by which the phases U, V, and W of the inverter can be set to a high level (e.g., V) of the DC voltage of the DC circuit. DCThe DC voltage of the DC circuit is either set to a low level (e.g., 0). During a cycle duration of 150, the state of the switches in the inverter changes, but for a single phase, only the switch connected to the high level (high-level switch, high-side switch) or the switch connected to the low level (low-level switch, low-side switch) is always on (i.e., "on"), not both, as this would cause a short circuit in the DC circuit. Since the switches are actual switches and the switching time is not zero, according to one implementation, it is necessary to ensure the time interval between the on state of the high-level switch and the on state of the low-level switch, especially to avoid unwanted interference (also known as "cross conduction"). According to one implementation, this is ensured by the first portions 146, 246 of the cycle duration of 150. For example, according to one implementation, components 130, 230 are at least temporarily zero during the first portion 146 of the cycle duration of 150, as shown in Figure 6, for example.

[0086] According to one embodiment, current measurement is performed in one phase while a switch connected to a high level is open and a switch connected to a low level is closed. In one embodiment, this is also referred to as "low-side current measurement," where a current measuring device (e.g., a current measuring resistor, particularly a shunt resistor) is connected between the switch and the low voltage level.

[0087] According to one embodiment, current measurement can only be performed in a phase U, V, W when the relevant component of the control signal 132 is less than 1, i.e., when the duty cycle of the pulse width modulation in that phase is less than 100%. In one embodiment, current measurement can be performed on a component when it has a value of 0.95 (95% duty cycle) or lower. In other words, current measurement cannot be performed in a phase where the component of the control signal 132 is one (i.e., 100%), for example, during the second portion 148, 248 of the period duration in the first cycle of the injected signal 121 for component 330. Figure 5 The value is marked as 150. Conversely, during the second part of the cycle duration, it is... Figure 5 The numbers 148 and 248 indicate that current can be measured.

[0088] In one implementation, the current I in the three phases U, V, W U I V I W The sum is zero, that is

[0089] I U +I V +I W =0

[0090] Therefore, in this embodiment, where the current flows only in three phases, it is sufficient to measure the current in two phases, since the current in the third phase can be calculated from the other two phases.

[0091] Due to the 120-degree phase shift of the three phases U, V, and W, according to one implementation method, the peak values ​​of modulation indices 108, 208, and 308 are... =0.57735, such as Figure 2 As shown.

[0092] Figure 7 illustrates an inverter 160 according to an embodiment of the subject matter disclosed herein.

[0093] According to one embodiment, the inverter 160 has an input terminal connected (or connectable to) a DC circuit 162 and a three-phase output 164, as shown, for example, in FIG7. According to one embodiment, the inverter has a current regulator 166 and a control device 168 that receives a voltage request 102 from the current regulator 166. According to one embodiment, the control device 168 is configured to execute a reference... Figure 1 The method described. Therefore, according to one embodiment, the control device 168 has a processor device 170 and a memory device 172, in which program units of a computer program product are stored. According to one embodiment, the program units are configured to control the method according to the first aspect when executed on the processor device 170, for example, as described in reference... Figure 1 The method described. According to another embodiment, the inverter has a pulse width modulator block 174 for controlling switches 176, 178 of the inverter 160 according to a control signal 132 generated by the control device 168, thereby generating a three-phase output at output 164. According to one embodiment, for each phase U, V, W of the three-phase output 164, it is connectable to a high level 180 of the DC circuit 162 via switch 176 and to a low level 182 of the DC circuit 162 via switch 178. To perform current measurement on the low-level side (low-side current measurement), a current measuring device, schematically and generally labeled 184 in FIG. 7, is arranged between switch 178 and the low level 182.

[0094] It should be noted that, for example, the algorithm diagrams, methods, and control devices described herein are not limited to the specific entities described in some embodiments. Rather, the subject matter disclosed herein can be implemented in various ways while still achieving the specific functions disclosed.

[0095] According to embodiments of the subject matter disclosed herein, any suitable entity (e.g., block, component, unit, device, element, switch, etc.) may be provided at least partially in the form of a corresponding computer program that enables a processor device to provide the functionality of the corresponding entity described herein. According to other embodiments, any suitable entity as described herein may be provided in hardware. According to other hybrid embodiments, some entities may be provided in software, while others may be provided in hardware.

[0096] It should be noted that each entity disclosed herein is not limited to the specific entity described in some embodiments. Furthermore, the subject matter described herein can be implemented in various ways, at different granularities, at the device level or software module level, while still providing the specified functionality. It should also be noted that, according to some embodiments, a separate entity (e.g., a software module, hardware module, or hybrid module) can be configured for each function disclosed herein. According to other embodiments, an entity (e.g., a software module, hardware module, or hybrid module) can be configured to implement two or more functions described herein. According to yet other embodiments, two or more entities (e.g., blocks, components, units and devices, elements, switches, etc.) can be configured collaboratively to jointly implement one function described herein. For example, the literal disclosure regarding switches corresponds both to an embodiment including a single switch and to the literal disclosure itself; furthermore, the literal disclosure regarding switches also includes another embodiment, namely, configuring two or more switches (e.g., connected in parallel), and these switches function as a single switch.

[0097] According to one embodiment, the control device includes a processing means having at least one processor for executing at least one program unit, which may correspond to a corresponding software module.

[0098] It should be noted that the implementation schemes described herein, especially those shown in the accompanying drawings, are only some possible combinations of embodiments of this disclosure. Therefore, the technical features of different implementation schemes can generally be reasonably combined, and for those skilled in the art, in conjunction with the implementation schemes explicitly disclosed herein, all combinations of different implementation schemes should be considered as disclosed. Furthermore, it should be noted that terms such as "a" or "an" do not exclude a plural meaning; terms such as "comprising" or "having" do not exclude the presence of additional technical features or method steps. Accordingly, according to one embodiment, the term "having" or "comprising" should be understood as "at least comprising"; according to another embodiment, the term "having" or "comprising" should be understood as "consisting of". According to one embodiment, the term "designed for" at least includes the meaning of "configured as".

[0099] According to one embodiment, the term "based on" as used herein should be understood as "by means of," and vice versa. For example, "generating a control signal for pulse width modulation based on voltage demand and a selected signal" means "generating the control signal by means of voltage demand and a selected signal." According to one embodiment, the terms "based on" or "by means of" do not exclude other dependencies; for example, the feature specifying "selection based on voltage demand" does not exclude the possibility that the selection is also based on a certain threshold.

[0100] The term “specifically” in this document usually refers to optional technical features.

[0101] The expression "A and / or B" generally includes three scenarios: "A only", "B only", and "A and B". In expressions referencing a list of technical features, "at least one" always encompasses each individual technical feature, as well as any combination of said technical features. For example, the expression "at least one of features A and B" includes three scenarios: "A only", "B only", and "A and B"; similarly, the expression "at least one of features A or B" also includes three scenarios: "A only", "B only", and "A and B"; and the expression "at least one of features A and B" also includes three scenarios: "A only", "B only", and "A and B".

[0102] It should also be noted that the reference numerals in the claims should not be construed as limiting the scope of protection of the claims. Furthermore, it should be noted that the reference numerals in the specification and the references to the drawings in the specification should not be construed as limiting the scope of protection of the specification. Rather, the drawings merely exemplify one implementation of various embodiments of the subject matter disclosed herein through specific combinations, and any other combination of embodiments is equally feasible and should be considered equivalent to the content disclosed in this application.

[0103] In summary, it should be pointed out that:

[0104] A method is disclosed, comprising: receiving a voltage request 102; generating a first signal 112; generating a second signal 114; selecting one signal from the first signal 112 and the second signal 114 as a selected signal 121; and generating a control signal 132 for pulse width modulation based on the voltage request 102 and the selected signal 121. Furthermore, a converter and a computer program product are disclosed.

[0105] List of reference numerals

[0106] 100 Flowchart

[0107] 102 Voltage Request

[0108] Components of 104 and 102 (phase U)

[0109] 106 DC voltage

[0110] 108 Modulation index (phase U)

[0111] 110 Modulation Index Calculation Block

[0112] 112 Minimum value (first signal)

[0113] 113 Computation block for 112

[0114] 114 Maximum value (second signal)

[0115] 115 is the computation block for 114.

[0116] The difference between 116, 112, and 114

[0117] 117 Subtraction

[0118] Question 118: Is the difference of 116 less than the threshold?

[0119] 119 Decision Block

[0120] 120 No

[0121] 121 Selected signal

[0122] 122 is

[0123] 126 Switch

[0124] 128 Adders

[0125] Components 130 and 132 (phase U)

[0126] 132 Control signals for PWM

[0127] 134 Switch

[0128] 136 Switching signal for 126

[0129] 138 Switching signal for 134

[0130] 140 threshold

[0131] Duration of the period 141 102

[0132] The intersection of 142, 116, and 140

[0133] The intersection of 143, 116, and 140

[0134] 144 Switches between 112 and 114

[0135] The intersection of 145, 116, and 140

[0136] 146. The first part of the cycle duration 141.

[0137] The intersection of 147, 116, and 140

[0138] Part 2 of 148 cycle duration 141

[0139] Duration of the period of injected signal 121 (150)

[0140] 160 inverter

[0141] 162 DC Circuit

[0142] 164 Three-phase output

[0143] 166 Current Regulator

[0144] 168 Control Equipment

[0145] 170 processing unit

[0146] 172 Storage devices

[0147] 174 Pulse Width Modulator Block

[0148] 176 switch, connected to 180

[0149] Switch 178, connected to 182

[0150] 180 162 high level

[0151] 182 162 low level

[0152] 184 Current measuring equipment

[0153] Component 204 102 (phase V)

[0154] 208 Modulation Index (Phase V)

[0155] Components of 230 132 (phase V)

[0156] 246. The first part of the cycle duration 141.

[0157] Part 248, cycle duration 141

[0158] Components of 304 102 (phase W)

[0159] 308 Modulation Index (Phase W)

[0160] Components of 330 132 (phase W)

Claims

1. A method comprising: Receive voltage request (102); Generate the first signal (112); Generate a second signal (114); Select one signal from the first signal (112) and the second signal (114) as the selected signal (121); A control signal (132) for pulse width modulation is generated based on the voltage request (102) and the selected signal (121).

2. The method according to claim 1, The voltage request (102) is periodic and the period duration (141) is defined. The first signal (112) is selected during the first portion of the period duration (141); and The second signal (114) is selected during the second part of the cycle duration (141). Specifically, the first signal (112) or the second signal (114) is selected based on the first signal (112) and the second signal (114), and specifically, the first signal (112) or the second signal (114) is selected based on the difference between the first signal (112) and the second signal (114).

3. The method according to claim 1 or 2, further comprising at least one of the following features: The first signal (112) is generated based on the voltage request (102); The second signal (114) is generated based on the voltage request (102); The first signal (112) is the third harmonic of the voltage request (102); The second signal (114) is the third harmonic of the voltage request (102).

4. The method according to any one of claims 1 to 3, wherein, The voltage request (102) includes components (104, 204, 304) for each phase of the multiphase system. The control signal (132) includes components (130, 230, 330) for each phase of the multiphase system; and The selected signal (121) is used for each phase of the multiphase system. Specifically, the multiphase system is a three-phase system.

5. The method according to claim 4, The minimum and maximum values ​​of the quantities (108, 208, 308) derived from the voltage request (102) are determined based on the components (104, 204, 304) of the voltage request (102); and Wherein the first signal (112) is the minimum value, and the second signal (114) is the maximum value; Specifically, the first signal (112) is selected as the selected signal (121) when the difference between the maximum and minimum values ​​is greater than or equal to the threshold (140), and the second signal (114) is selected as the selected signal (121) when the difference between the maximum and minimum values ​​is less than the threshold (140).

6. The method according to any one of claims 1 to 5, The control signal (132) controls the pulse width modulation in the inverter (160); The inverter (160) described herein absorbs energy from a DC circuit; The modulation index is defined as the quotient of the voltage request (102) divided by the measured DC voltage of the DC circuit; Specifically, the threshold value is 0.

09.

7. The method according to any one of claims 1 to 6, Intermediate signals (108, 208, 308) are generated from the voltage request (102), and the selected signal (121) is injected into the intermediate signals (108, 208, 308) to generate the control signal (132).

8. A converter, including a control device (168). The control device (168) is configured to receive a voltage request (102). The control device (168) is configured to generate a first signal (112) and a second signal (114). The control device (168) is configured to select one signal from the first signal (112) and the second signal (114) as the selected signal (121); and The control device (168) is configured to generate a control signal (132) for pulse width modulation based on the voltage request (102) and the selected signal (121).

9. The converter of claim 7, wherein the control device (168) has a current regulator that determines the voltage request (102); and / or The converter mentioned above is an inverter (160).

10. A computer program product comprising a program unit configured to control the method according to any one of claims 1 to 7 when executed on a processing device (170).

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