Method for controlling a power converter and power converter system

Abstract

Embodiments of the present disclosure provide a method for controlling a converter and a converter system. The method comprises: obtaining voltage signals representing three-phase phase voltages of an AC side of the converter; determining carrier signals of three-phase switching branches of the converter based on the voltage signals, wherein phases of the carrier signals of two phases among the three phases are identical to each other and different from a phase of the carrier signal of the remaining one phase among the three phases, and a magnitude of the phase voltage of the remaining one phase is between the phase voltages of the two phases; and generating control signals of the three-phase switching branches based on the determined carrier signals and modulation wave signals of the three-phase switching branches. The scheme of the present disclosure can effectively reduce common-mode voltage and common-mode noise of the converter, thereby improving reliability of the system.

Description

Technical Field

[0001] Embodiments of this disclosure relate to the field of power electronics technology, and more specifically to methods for controlling converters and converter systems. Background Technology

[0002] Converters transform electrical power into a suitable form for grid or user use. For example, a converter can act as a rectifier to convert AC power to DC power, and as an inverter to convert DC power to AC power. Some converters can also switch between rectifier and inverter modes as needed to achieve energy transfer in both directions. Due to these characteristics, converters are widely used in many fields for various power conversion applications, such as motor drives, grid-connected power converters, and renewable energy power converters.

[0003] During the operation of a converter, common-mode (CM) noise may be generated. This common-mode noise not only causes serious electromagnetic interference (EMI) problems, but may also break down the insulation and damage the converter, and even cause electric shock to people, which seriously affects the reliability and safety of converter operation. Summary of the Invention

[0004] Based on the above-mentioned problems, and according to the exemplary embodiments of the present disclosure, a control method for a converter and a converter system are provided.

[0005] In a first aspect of this disclosure, a method for controlling a converter is provided, the method comprising: acquiring a voltage signal representing a three-phase phase voltage on the AC side of the converter; determining a carrier signal for a three-phase switching branch of the converter based on the voltage signal, wherein the phases of the carrier signals of two of the three phases are the same as each other and are different from the phase of the carrier signal of the remaining phase of the three phases, and the magnitude of the phase voltage of the remaining phase is between the phase voltages of the two phases; and generating a control signal for the three-phase switching branch based on the determined carrier signal and a modulation wave signal of the three-phase switching branch.

[0006] In some embodiments of this disclosure, the phase difference between the carrier signals of two of the three phases and the phase of the carrier signal of the remaining phase is in the range of 150 degrees to 210 degrees.

[0007] In some embodiments of this disclosure, the phase difference between the carrier signals of two of the three phases and the phase of the carrier signal of the remaining phase is 180 degrees.

[0008] In some embodiments of this disclosure, determining the carrier signal of a three-phase switching branch of a converter based on a voltage signal includes: comparing the three-phase phase voltages based on the voltage signal; and for a first-phase switching branch, determining a first carrier signal as the carrier signal of the first-phase switching branch in response to a second-phase phase voltage being greater than a third-phase phase voltage, or determining a second carrier signal as the carrier signal of the first-phase switching branch in response to a second-phase phase voltage not being greater than a third-phase phase voltage, wherein the second carrier signal and the first carrier signal have different phases; for a second-phase switching branch, determining the first carrier signal as the carrier signal of the second-phase switching branch in response to a third-phase phase voltage being greater than a first-phase phase voltage, or determining a second carrier signal as the carrier signal of the second-phase switching branch in response to a third-phase phase voltage not being greater than a first-phase phase voltage; for a third-phase switching branch, determining the first carrier signal as the carrier signal of the third-phase switching branch in response to a first-phase phase voltage being greater than a second-phase phase voltage, or determining a second carrier signal as the carrier signal of the third-phase switching branch in response to a first-phase phase voltage not being greater than a second-phase phase voltage.

[0009] In some embodiments of this disclosure, determining the carrier signal of a three-phase switching branch of the converter based on a voltage signal includes: for each phase switching branch, determining a first carrier signal as the carrier signal of that phase switching branch in response to a decreasing phase voltage in the three-phase phase voltages corresponding to that phase switching branch, or determining a second carrier signal as the carrier signal of that phase switching branch in response to a non-decreasing phase voltage in the three-phase phase voltages corresponding to that phase switching branch, wherein the second carrier signal has a different phase from the first carrier signal.

[0010] In some embodiments of this disclosure, acquiring a voltage signal representing the three-phase phase voltage on the AC side of the converter includes: acquiring a modulation wave signal of the three-phase switch branch as a voltage signal representing the three-phase phase voltage.

[0011] In some embodiments of this disclosure, acquiring a voltage signal representing the three-phase voltage on the AC side of the converter includes: acquiring a sensing signal of the AC side power supply voltage of the converter as a voltage signal representing the three-phase voltage.

[0012] In some embodiments of this disclosure, the converter is a rectifier, and the modulated wave signal is determined based on the DC-side voltage, AC-side power supply voltage, and AC-side inductor current of the rectifier.

[0013] In some embodiments of this disclosure, generating a control signal for the three-phase switch branch based on a determined carrier signal and a modulation wave signal of the three-phase switch branch includes: generating a pulse width modulation signal as a control signal for the three-phase switch branch based on a comparison of the determined carrier signal and the modulation wave signal.

[0014] According to a second aspect of this disclosure, a converter system is provided, the converter system comprising: a converter; and a control device for controlling the converter, the control device being configured to perform the method according to the first aspect.

[0015] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0016] The above and other features, advantages, and aspects of the various embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0017] Figure 1 A first scenario in which embodiments of this disclosure may be implemented is shown.

[0018] Figure 2 A second scenario in which embodiments of this disclosure can be implemented is shown.

[0019] Figure 3 A schematic diagram of a converter and related circuitry in a first scenario according to an embodiment of this disclosure is shown.

[0020] Figure 4 A schematic block diagram of a control device for a converter system according to an embodiment of the present disclosure is shown.

[0021] Figure 5 A schematic block diagram of a modulation wave generation module in a control device according to an embodiment of the present disclosure is shown.

[0022] Figure 6 The waveforms of the modulated wave and carrier wave in a conventional pulse width modulation scheme are shown.

[0023] Figure 7A The diagram shows magnified waveforms of the modulated wave and carrier wave in a local time period for a conventional pulse width modulation scheme.

[0024] Figure 7B The waveform of the drive signal for a conventional pulse width modulation scheme is shown.

[0025] Figure 8 The waveform of the common-mode voltage for a conventional pulse width modulation scheme is shown.

[0026] Figure 9 A schematic flowchart of a control method for a converter according to an embodiment of the present disclosure is shown.

[0027] Figure 10AWaveform diagrams of the modulation wave and carrier wave of the control method according to embodiments of the present disclosure are shown.

[0028] Figure 10B A waveform diagram of the three-phase drive signal of the control method according to an embodiment of the present disclosure is shown.

[0029] Figure 11 A waveform diagram of the common-mode voltage of the control method according to an embodiment of the present disclosure is shown.

[0030] Figure 12 A schematic block diagram of one implementation of a carrier generation module of a control device according to an embodiment of the present disclosure is shown.

[0031] Figure 13 A waveform diagram of a carrier generated by a carrier generation module according to an embodiment of the present disclosure is shown.

[0032] Figure 14 A schematic block diagram is shown illustrating another implementation of the carrier generation module of a control device according to an embodiment of the present disclosure.

[0033] Figure 15A , Figure 15B and Figure 15C A schematic flowchart illustrating an example process for generating a carrier signal according to an embodiment of the present disclosure is shown.

[0034] Figure 16 A schematic flowchart illustrating an example process for generating a carrier signal according to an embodiment of the present disclosure is shown.

[0035] Figure 17 A schematic block diagram of an example device that can be used to implement embodiments of the present disclosure is shown. Detailed Implementation

[0036] The embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0037] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment / implementation" or "this embodiment / implementation" should be understood as "at least one embodiment / implementation". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0038] As mentioned above, common-mode noise is generated during converter operation, which can lead to EMI problems and reduce converter reliability. This disclosure proposes an improved control scheme for converters. By controlling the carrier phase of a specific phase in the three-phase system, the common-mode voltage during converter operation can be significantly reduced, thereby reducing common-mode noise and improving system reliability.

[0039] Figure 1 A first scenario in which embodiments of the present disclosure can be implemented is shown. In this first scenario, the converter system 1000 can receive AC power from the three-phase AC power supply 300 via the filter 500 and convert the AC power into DC power to supply the DC load section 400. In other words, the converter system 1000 can perform rectification in this first scenario.

[0040] The converter system 1000 includes a converter 100. The converter 100 includes a first-phase switching branch (also referred to as the A-phase switching branch) composed of switching devices S1 and S2, a second-phase switching branch (also referred to as the B-phase switching branch) composed of switching devices S3 and S4, and a third-phase switching branch (also referred to as the C-phase switching branch) composed of switching devices S5 and S6. Switching devices S1 to S6 may each be equipped with freewheeling diodes D1 to D6 connected in reverse parallel with them. The switching devices S1 to S6 include, but are not limited to, insulated-gate bipolar transistors (IGBTs), junction field-effect transistors (JFETs), bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), gate-turn-off thyristors (GTOs), MOS-controlled thyristors (MCTs), integrated gate-commutated thyristors (IGCTs), silicon carbide (SiC) switching devices, or gallium nitride (GaN) switching devices, etc. The freewheeling diodes D1 to D6 can be inherent body diodes of the switching devices or diodes separately positioned relative to the switching devices. Furthermore, the converter 100 also includes inductors L1 to L3 on the AC side and capacitors Co1 and Co2 on the DC side. Inductors L1, L2, and L3 are respectively installed on the first, second, and third phases of the AC side, and capacitors Co1 and Co2 are connected across the DC side bus. During the operation of converter 100, inductors L1, L2, and L3, as well as capacitors Co1 and Co2, can perform functions such as voltage regulation, filtering, and energy storage.

[0041] The converter system 1000 also includes a control device 200. The control device 200 can be implemented in various ways. For example, it can be implemented as a controller with computing and processing capabilities, as an analog circuit and / or a digital circuit, or as a combination of the above. The control device 200 can receive sensing signals, such as voltage and current sensing signals, from the converter 100, the three-phase AC power supply 300, the DC load unit 400, and the filter 500 as needed, and generate control signals or drive signals based on the received sensing signals to control the switching devices S1 to S6 of the converter 100 to turn the switching devices S1 to S6 on and off, thereby converting the AC power of the three-phase AC power supply 300 into the DC power required by the DC load unit 400.

[0042] In the first scenario, the three-phase AC power supply 300 can be a public power grid or other suitable type of three-phase power supply, and may include, for example, a first phase power supply e with phase offset. a Second phase power supply e b and the third phase power supply e c The DC load section 400 includes a load R. L Furthermore, filter 500 can be used to prevent harmonics generated by converter 100 from flowing into the public power grid or affecting the three-phase AC power supply 300. For example, filter 500 may include capacitors Cx1 to Cx3, wherein capacitor Cx1 is disposed on the first phase, capacitor Cx2 is disposed on the second phase, and capacitor Cx3 is disposed on the third phase.

[0043] Figure 2 A second scenario in which embodiments of the present disclosure can be implemented is illustrated. In this second scenario, the converter system 1000 can convert DC power from the DC power supply 600 into AC power and provide the AC power to the AC load unit 700. In other words, the converter system 1000 can perform an inverter function in this second scenario. During the inverter operation, the control device 200 in the converter system 1000 can receive sensing signals, such as voltage and current sensing signals, from the converter 100, the DC power supply 600, and the AC load unit 700 as needed, and generate control signals or drive signals for controlling the switching devices S1 to S6 of the converter 100 to turn the switching devices S1 to S6 on and off, thereby converting the DC power of the DC power supply 600 into the AC power required by the AC load unit 700. Figure 2 The other configurations of the converter system 1000 are similar to those in the example. Figure 1 Therefore, I will not go into details.

[0044] The following will be based on Figure 1The first scenario is used as an example to describe the control process of the converter system 1000. However, it is understood that the control process of the converter system 1000 can also be applied after adaptive adjustments. Figure 2 The second scene in the story.

[0045] Figure 3 A schematic diagram of a converter 100 and related circuitry in a first scenario according to an embodiment of the present disclosure is shown. Figure 4 A schematic block diagram of a control device 200 for a converter system 1000 according to an embodiment of the present disclosure is shown. Figure 3 and Figure 4 As shown, the control device 200 can receive sensing signals from sensing devices 110, 310, and 510. The sensing signal V from sensing device 110... Bus The DC-side bus voltage of the indicator converter 100 is obtained from the sensing signal V from the sensing device 310. a V b and V c The three phase voltages (phase A, phase B, and phase C) output by the three-phase AC power supply 300 to the converter system 1000, respectively, and the sensing signal I from the sensing device 510, are respectively indicated. L1 I L2 and I L3 These respectively indicate the inductor currents flowing through inductors L1, L2, and L3. The control device 200 can generate a drive signal V based on the received sensing signals. S1 To V S6 Drive signal V S1 and V S2 The drive signal V is provided to the gates of switching devices S1 and S2 in the first phase switching branch, respectively, to control the on and off states of switching devices S1 and S2. S3 and V S4 The signal is supplied to the gates of switching devices S3 and S4 in the second phase switching branch, respectively, to control the on and off states of switching devices S3 and S4. Drive signal V S5 and V S6 The gates of switching devices S5 and S6 in the third phase switching branch are respectively provided to control the switching devices S5 and S6 to turn on and off. The control device 200 may include a modulation wave generation module 210A for the first phase (i.e., phase A), a modulation wave generation module 210B for the second phase (i.e., phase B), and a modulation wave generation module 210C for the third phase (i.e., phase C).

[0046] Figure 5 A schematic block diagram of a modulation wave generation module 210A in a control device 200 according to an embodiment of the present disclosure is shown. Figure 5As shown, module 210A includes a difference unit 211A, a proportional-integral (PI) unit 212A, a product unit 213A, a difference unit 214A, and a PI unit 215A.

[0047] Specifically, the sensing signal V from sensing device 110 Bus After digital-to-analog conversion (A / D conversion), the input is fed into the difference unit 211A of module 210A, and compared with the reference voltage V of the DC bus. Bus_ref The difference operation is performed at the difference unit 211A, where the reference voltage V Bus_ref This represents the desired bus voltage output to the DC load on the DC side of converter 100. Then, the difference unit 211A provides the difference to the PI unit 212A. Through the difference unit 211A and the PI unit 212A, a closed-loop control for the DC bus voltage can be formed to ensure that the DC voltage output by converter 100 can track or reach the desired reference voltage V. Bus_ref Furthermore, the signal processed by the PI unit 212A is provided to the product unit 213A, and is then compared with the sensing signal V after A / D conversion at the product unit 213A. a Perform a multiplication operation. The product unit 213A will output I after the multiplication operation. a_ref Provided to the difference unit 214A. At the difference unit 214A, output I. a_ref With the sensing signal I after A / D conversion L1 The difference is calculated. The difference output by the difference unit 214A is provided to the PI unit 215A to generate the modulated wave signal Ma. Through the product unit 213A, the difference unit 214A, and the PI unit 215A, a modulated wave signal Ma can be generated from the sensed signal I. L1 Closed-loop control of the indicated inductor current ensures that the inductor current can track or reach the same phase as the AC power supply voltage, thereby reducing or eliminating the phase difference between the voltage and current output by the AC power supply and thus achieving power factor correction.

[0048] Modules 210B and 210C are similar to module 210A, and therefore will not be described in detail. However, since the sum of the three-phase voltages is zero and the modulation wave of the remaining phase can be directly calculated using the modulation waves of two phases, in some embodiments, one of modules 210A, 210B, and 210C can be omitted. That is, only the two-phase modulation wave generation module can be provided, and the modulation wave of the remaining phase can be derived using the two-phase modulation waves generated by the two-phase modulation wave generation module. In this case, Figure 3 The sensing devices 310 and 510 in the middle can sense and provide only two-phase voltage and two-phase current.

[0049] Return to Figure 4 The signal Ma output by module 210A is output as a modulated wave signal to comparator module 230A. In comparator module 230A, the modulated wave signal Ma is compared with the carrier signal, and drive signals are output to the upper bridge arm switching device S1 and the lower bridge arm switching device S2 of the first phase switching branch, respectively. Similarly, modules 210B and 210C also compare the corresponding modulated wave signals Mb and Mc with the carrier signal, and generate drive signals to the switching devices S3 and S4 of the second phase switching branch and drive signals to the third phase switching branch S5 and S6. Thus, the converter 100 can be controlled in the manner of pulse-width modulation (PWM).

[0050] To facilitate a clear explanation of the objectives of the embodiments disclosed herein, conventional PWM modulation methods will be described first.

[0051] Figure 6 The waveforms of the modulated wave and carrier wave in a conventional PWM modulation scheme are shown. (For example...) Figure 6 As shown, the A-phase modulated wave, B-phase modulated wave, and C-phase modulated wave are compared with the same triangular carrier wave to generate a PMW signal to turn the switching devices of the three-phase switching branch on and off. It should be noted that... Figure 6 The carrier frequency shown in the diagram is merely illustrative, and the carrier frequency of PWM is typically as high as several kilohertz to hundreds of kilohertz, which is much higher than the frequency of the modulating wave (e.g., 50 Hz or 60 Hz). Therefore, hundreds to tens of thousands of carrier cycles can be experienced within a single modulating wave cycle.

[0052] Figure 7A It shows Figure 6 The magnified waveforms of the modulated wave and carrier wave in a local time period, and Figure 7B It shows the relationship with Figure 7A The corresponding waveform diagram of the driving signal. Figure 7A and Figure 7B The time periods shown can, for example, correspond to Figure 6During the T-period, taking phase A as an example, the phase A modulation wave is compared with the triangular carrier wave. When the phase A modulation wave is greater than the carrier wave, a high-level phase A drive signal is generated, and when the phase A modulation wave is less than the carrier wave, a low-level phase A drive signal is generated. The high-level drive signal turns on the switching device, and the low-level drive signal turns off the switching device. The generated phase A drive signal is provided to the gate of the upper arm switching device S1 of the phase A switching branch to turn the switching device S1 on or off, while the inverted phase A drive signal is provided to the gate of the lower arm switching device S2 of the phase A switching branch to turn the switching device S2 on or off. The drive signals for phases B and C are generated in a similar manner and are provided to the gates of the switching devices S3 and S4 of the phase B switching branch and the gates of the switching devices S5 and S6 of the phase C switching branch, respectively, to control the on and off of these switching devices. In this way, the converter can be controlled to achieve rectification or inversion operation.

[0053] However, common-mode noise is generated during converter operation, which reduces the converter's reliability and safety. Common-mode noise can typically be reduced and suppressed using common-mode filters with common-mode chokes and capacitors. However, the size and weight of the common-mode filter are largely dependent on the magnetic saturation of the choke core, which in turn is significantly affected by the common-mode voltage.

[0054] In a three-phase converter, the common-mode voltage is defined as the instantaneous average voltage value of the three phases, and... Figure 1 and Figure 2 In the scenario shown, the common-mode voltage V cm It can be defined according to the following equation:

[0055]

[0056] Where V aM It is the instantaneous voltage between point a in the A-phase switch branch and the midpoint M of the DC capacitor branch, V. bM It is the instantaneous voltage between point b of the B-phase switch branch and the midpoint M of the DC capacitor branch, and V cM It is the instantaneous voltage between point c of the C-phase switch branch and the midpoint M of the DC capacitor branch.

[0057] The table below shows the common-mode voltage of the converter under different switching states. In the upper arm switching device states (S1, S3, S5), 1 and 0 indicate that the corresponding switching device is on or off, respectively. For example, (0,0,0) indicates that S1, S3, and S5 are all off, and (1,0,0) indicates that S1 is on and S3 and S5 are both off. Furthermore, since the states of the lower arm switching devices are complementary to those of the upper arm switching devices, the states of all switching devices S1 to S6 can be characterized by the upper arm switching device states (S1, S3, S5).

[0058] Table 1

[0059]

[0060] In the table above, when (S1,S3,S5) is (0,0,0), the common-mode voltage reaches -U. bus / 2, and when (S1,S3,S5) is (1,1,1), the common-mode voltage reaches U. bus / 2. In other words, when all three upper bridge arm switching devices S1, S3, and S5 are either off or all are on, the absolute value of the common-mode voltage reaches its maximum, i.e., U... bus / 2.

[0061] Figure 8 It shows the relationship with Figure 7A and Figure 7B The corresponding common-mode voltage waveform. For example... Figure 8 As shown, during the periods when the drive signals of phases A, B, and C are all high or all low (i.e., when (S1, S3, S5) are (0, 0, 0) or (1, 1, 1), ±U appears. bus / 2 is the maximum common-mode voltage, while at other times, the common-mode voltage is only ±U bus / 6. It is evident that the presence of switching states of (0,0,0) or (1,1,1) significantly increases the common-mode voltage. Excessive common-mode voltage leads to severe common-mode noise, which can cause EMI problems and may also lead to insulation breakdown, thus reducing converter reliability. Furthermore, excessively high common-mode voltage amplitude necessitates larger and heavier common-mode filters and higher insulation requirements for related components, increasing system cost.

[0062] To address these issues, embodiments of this disclosure provide an improved control scheme for converters. In this improved scheme, the carrier wave of a specific phase of the three-phase circuit can be phase-shifted. This eliminates or reduces periods during converter operation where all upper or lower bridge arm switching devices are either fully on or fully off, thereby significantly reducing the common-mode voltage during converter operation. This improves system reliability and safety, and reduces the insulation requirements of related components and the size of the common-mode filter.

[0063] Figure 9 A schematic flowchart of a control method 900 for a converter 100 according to an embodiment of the present disclosure is shown. Method 900 can be performed in... Figures 1 to 2 This is implemented in the scenario and executed by the control device 200 of the converter system 1000. It can be understood that the above regarding... Figures 1 to 5 The aspects described can be applied to method 900. For the purposes of discussion, they will be combined. Figures 1 to 5 To describe method 900.

[0064] At box 901, control device 200 acquires a voltage signal representing the three-phase phase voltage on the AC side of converter 100.

[0065] As an example, control device 200 may include carrier generation module 220 (see...) Figure 4 ), and indicates that the voltage signal of the three-phase phase voltage on the AC side can be input to the carrier generation module 220 of the control device 200.

[0066] In some embodiments of this disclosure, the control device 200 acquires the modulation wave signals Ma, Mb, and Mc of the three-phase switch branch as voltage signals representing the three-phase phase voltages on the AC side of the converter 100. Specifically, the modulation wave signals Ma, Mb, and Mc actually indicate the three-phase phase voltages that the converter 100 will obtain on its AC side, and therefore the modulation wave signals Ma, Mb, and Mc can be used as voltage signals representing the three-phase phase voltages on the AC side of the converter 100.

[0067] In some embodiments of this disclosure, the control device 200 acquires a sensing signal V of the AC side power supply voltage of the converter 100. a V b and V c As a voltage signal representing the three-phase phase voltage. Specifically, in Figures 3 to 5 As shown in the control process, due to the closed-loop control of the inductor current by the control device 200, the three-phase voltage on the AC side of the converter 100 (i.e., the voltage at points a, b, and c of the three-phase switch branch) is related to the AC power supply e of the converter 100. a e b and e cThe output voltages have the same phase. Therefore, the sensing signal V of the AC power supply voltage can be used directly. a V b and V c It is used as a signal to represent the three-phase voltage on the AC side.

[0068] At block 902, control device 200 determines the carrier signal of the three-phase switching branch of converter 100 based on the acquired voltage signal, wherein the phase of the carrier signal of two of the three phases is the same as that of each other and is different from the phase of the carrier signal of the remaining phase of the three phases, and the magnitude of the phase voltage of the remaining phase is between the phase voltages of the two phases.

[0069] As an example, the carrier generation module 220 of the control device 200 can determine the phase voltage magnitudes of phases A, B, and C based on the acquired voltage signals representing the three-phase phase voltages, and assign carrier signals based on their phase voltage magnitudes. For example, if the current value of the phase voltage of phase B (e.g., the current value of the modulation wave of phase B or the current value of the power supply voltage of phase B) is less than the current value of the phase voltage of phase A and greater than the current value of the phase voltage of phase C, then phases A and C can be assigned the same carrier or a carrier with the same phase, while phase B can be assigned another carrier with a different phase relative to the carriers of phases A and C. Since the phase voltages of phases A, B, and C are alternating and their relative magnitudes are constantly changing, the carriers assigned to each phase should also be continuously adjusted so that the phase assigned to the phase with the middle voltage magnitude always has a different phase than the carriers of the other two phases. Due to the change in carrier phase, the drive signal for the remaining phase will also be changed accordingly, thereby reducing or eliminating periods where the drive signals for the upper arm switching devices (or lower arm switching devices) are all high or all low, thus avoiding or reducing the occurrence of U... bus / 2 is the period of high common-mode voltage.

[0070] In some embodiments of this disclosure, the phase difference between the carrier signals of two phases of the three-phase circuit and the phase of the carrier signal of the remaining phase is in the range of 150 to 210 degrees. Studies have shown that by shifting the carrier phase of the phase with the middle phase voltage by an angle in the range of 150 to 210 degrees, the switching state of all upper bridge arm switching devices (or all lower bridge arm switching devices) of the three-phase switching branch being turned on or off can be completely eliminated, thereby effectively reducing the amplitude of the common-mode voltage.

[0071] In some embodiments of this disclosure, the phase difference between the carrier signals of two of the three phases and the phase of the carrier signal of the remaining phase is 180 degrees. Specifically, the phases of the two carriers can be opposite to each other, thereby allowing the other carrier to be obtained directly by inverting one carrier. This simplifies the carrier generation process and effectively simplifies control.

[0072] At block 903, control device 200 generates control signals for the three-phase switch branch based on the determined carrier signal and the modulation wave signal of the three-phase switch branch. As an example, comparison module 230A of control device 200 compares the modulation wave Ma generated by modulation wave generation module 210A with the carrier wave Ca generated by carrier generation module 220, and generates a drive signal V. S1 and V S2 The comparison module 230B compares the modulated wave Mb generated by the modulation wave generation module 210B with the carrier wave Cb generated by the carrier generation module 220, and generates a drive signal V. S3 and V S4 The comparison module 230C compares the modulated wave Mc generated by the modulation wave generation module 210C with the carrier wave Cc generated by the carrier generation module 220, and generates a drive signal V. S5 and V S6 Drive signal V S1 To V S6 The switching devices S1 to S6 of the three-phase switching branch of the converter 100 are provided to realize the control of the converter 100.

[0073] Figure 10A Waveform diagrams of the modulated wave signal and the carrier signal of the control method 900 according to an embodiment of the present disclosure are shown, as well as Figure 10B A waveform diagram of the three-phase drive signal of a control method 900 according to an embodiment of the present disclosure is shown. Figure 10A and Figure 10B As shown, during this time period, the current value of the modulated wave of phase B lies between the current values ​​of the modulated waves of phases A and C. Therefore, phases A and C are assigned a first carrier, such as a positive triangular carrier, while phase B is assigned a second carrier with a different phase from the first carrier, such as a negative triangular carrier out of phase with respect to the positive triangular carrier. By comparing the modulated waves of phases A, B, and C with their corresponding carriers, drive signals for phases A, B, and C are generated respectively. Figure 10B It can be seen that there are no periods in the three-phase drive signals obtained by control method 900 where all three phases are simultaneously at a high level or simultaneously at a low level. In other words, by appropriately allocating the carrier waves of the three phases, the periods when the states (S1, S3, S5) of the upper bridge arm switching devices are (0,0,0) and (1,1,1) have been completely eliminated.

[0074] Figure 11 A waveform diagram of the common-mode voltage of a control method 900 according to an embodiment of the present disclosure is shown. Figure 11 As shown, the common-mode voltage amplitude in the converter system 1000 after adopting control method 900 is reduced from ±U in the conventional scheme. bus / 2 decreased to ±Ubus This / 6 ratio significantly reduces the common-mode voltage generated by the converter 100, thereby reducing EMI problems caused by common-mode noise and decreasing the size and weight of the common-mode filter. Furthermore, the reduction in common-mode voltage amplitude also reduces the insulation requirements of the devices, thus lowering system costs.

[0075] Figure 12 A schematic block diagram of one implementation of the carrier generation module 220 of the control device 200 is shown. Figure 12 As shown, the carrier generation module 220 may include comparison units 221A, 221B, and 221C, switching units 222A, 222B, and 222C, as well as a positive triangular carrier generation unit 223 and a negative triangular carrier generation unit 224. Comparison unit 221A and switching unit 222A are used to generate a carrier signal Ca for phase A, comparison unit 221B and switching unit 222B are used to generate a carrier signal Cb for phase B, and comparison unit 221C and switching unit 222C are used to generate a carrier signal Cc for phase C.

[0076] For the A-phase switch branch, the comparison unit 221A compares the B-phase voltage and the C-phase voltage based on the received voltage signal representing the three-phase voltage on the AC side of the converter 100. If the B-phase voltage is greater than the C-phase voltage, the comparison unit 221A controls the switching unit 222A to perform channel switching, so that the switching unit 222A determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Ca of the A-phase switch branch. If the B-phase voltage is less than or equal to the C-phase voltage, the comparison unit 221A controls the switching unit 222A to perform channel switching, so that the switching unit 222A determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Ca of the A-phase switch branch.

[0077] For the B-phase switch branch, the comparison unit 221B compares the C-phase voltage with the A-phase voltage based on the received voltage signal representing the three-phase voltage on the AC side of the converter 100. If the C-phase voltage is greater than the A-phase voltage, the comparison unit 221B controls the switching unit 222B to perform channel switching, so that the switching unit 222B determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Cb of the B-phase switch branch. If the C-phase voltage is less than or equal to the A-phase voltage, the comparison unit 221B controls the switching unit 222B to perform channel switching, so that the switching unit 222B determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Cb of the B-phase switch branch.

[0078] For the C-phase switch branch, the comparison unit 221C compares the A-phase voltage and the B-phase voltage based on the received voltage signal representing the three-phase voltage on the AC side of the converter 100. If the A-phase voltage is greater than the B-phase voltage, the comparison unit 221C controls the switching unit 222C to perform channel switching, so that the switching unit 222C determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Cc of the C-phase switch branch. If the A-phase voltage is less than or equal to the B-phase voltage, the comparison unit 221C controls the switching unit 222C to perform channel switching, so that the switching unit 222C determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Cc of the C-phase switch branch.

[0079] Figure 13 It shows Figure 12 The waveform diagram of the carrier generated by the carrier generation module 220 is shown below. At t0, the phase voltage of phase C changes from being greater than the phase voltage of phase A to being less than the phase voltage of phase A; therefore, the carrier signal Cb of the phase B switch branch changes from a positive triangular carrier to a negative triangular carrier. At t1, the phase voltage of phase B changes from being less than the phase voltage of phase C to being greater than the phase voltage of phase C; therefore, the carrier signal Ca of the phase A switch branch changes from a negative triangular carrier to a positive triangular carrier. At t2, the phase voltage of phase A changes from being greater than the phase voltage of phase B to being less than the phase voltage of phase B; therefore, the carrier signal Cc of the phase C switch branch changes from a positive triangular carrier to a negative triangular carrier. At t3, the phase voltage of phase C changes from being less than the phase voltage of phase A to being greater than the phase voltage of phase A; therefore, the carrier signal Cb of the phase B switch branch changes from a negative triangular carrier to a positive triangular carrier. At t4, the phase voltage of phase B changes from being greater than the phase voltage of phase C to being less than the phase voltage of phase C; therefore, the carrier signal Ca of the phase A switch branch changes from a positive triangular carrier to a negative triangular carrier. At t5, the phase voltage of phase A changes from being less than the phase voltage of phase B to being greater than the phase voltage of phase B. Therefore, the carrier signal Cc of the phase C switch branch changes from a negative triangular carrier to a positive triangular carrier.

[0080] This method ensures that the carrier of the phase with the middle phase voltage is out of phase or has a different phase from the carriers of the other two phases. For example, during the time interval t0 to t1, the phase voltage of phase C is between the phase voltages of phase A and phase B, and the carrier Cc of phase C is a positive triangular carrier, while the carriers Ca of phase A and Cb of phase B are both negative triangular carriers. This ensures that during the time interval t0 to t1, there will not be a situation where all three phase drive signals are either at high voltage or all at low level. Furthermore, this method ensures that only the carrier signal of one phase is changed at each switching moment, which greatly simplifies the control process.

[0081] Figure 14 A schematic block diagram of another implementation of the carrier generation module 220 of the control device 200 is shown. Figure 14As shown, the carrier generation module 220 may include voltage change determination units 225A, 225B, and 225C, switching units 222A, 222B, and 222C, as well as a positive triangular carrier generation unit 223 and a negative triangular carrier generation unit 224. Voltage change determination unit 225A and switching unit 222A are used to generate a carrier signal Ca for phase A, voltage change determination unit 225B and switching unit 222B are used to generate a carrier signal Cb for phase B, and voltage change determination unit 225C and switching unit 222C are used to generate a carrier signal Cc for phase C.

[0082] For the A-phase switch branch, if the voltage change determination unit 225A determines that the A-phase voltage among the three-phase voltages is decreasing, then the control switching unit 222A determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Ca of the A-phase switch branch; otherwise, the control switching unit 222A determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Ca of the A-phase switch branch. For the B-phase switch branch, if the voltage change determination unit 225B determines that the B-phase voltage among the three-phase voltages is decreasing, then the control switching unit 222B determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Cb of the B-phase switch branch; otherwise, the control switching unit 222B determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Cb of the B-phase switch branch. For the C-phase switch branch, if the voltage change determination unit 225C determines that the C-phase voltage among the three-phase voltages is decreasing, then the control switching unit 222C determines the positive triangular carrier signal generated by the positive triangular carrier generation unit 223 as the carrier signal Cc of the C-phase switch branch; otherwise, the control switching unit 222C determines the negative triangular carrier signal generated by the negative triangular carrier generation unit 224 as the carrier signal Cc of the C-phase switch branch. In this way, the same functionality can be achieved. Figure 13 The carrier signal combination shown is used to reduce the common-mode voltage of the converter in a simple and efficient control manner.

[0083] Figure 15A , Figure 15B and Figure 15C Schematic flowcharts of example processes 1500A, 1500B, and 1500C for generating carrier signals Ca, Cb, and Cc are shown. Figure 15A , Figure 15B and Figure 15C The process shown can be performed in Figure 9 Implemented at box 902.

[0084] like Figure 15A As shown, process 1500A illustrates an example process for determining the carrier signal Ca of the first phase switch branch.

[0085] At box 1501A, control device 200 compares the three-phase voltages based on the acquired voltage signals representing the three-phase voltages.

[0086] At frame 1502A, control device 200 determines whether the second phase voltage is greater than the third phase voltage.

[0087] At frame 1503A, in response to the second phase voltage being greater than the third phase voltage, the control device 200 determines the first carrier signal as the carrier signal Ca of the first phase switch branch.

[0088] At frame 1504A, in response to the second phase voltage not being greater than the third phase voltage, the control device 200 determines the second carrier signal as the carrier signal Ca of the first phase switch branch, and the second carrier signal and the first carrier signal have different phases.

[0089] like Figure 15B As shown, process 1500B illustrates an example process for determining the carrier signal Cb of the second phase switch branch.

[0090] At box 1501B, control device 200 compares the three-phase voltages based on the acquired voltage signals representing the three-phase voltages.

[0091] At frame 1502B, control device 200 determines whether the third phase voltage is greater than the first phase voltage.

[0092] At frame 1503B, in response to the third phase voltage being greater than the first phase voltage, the control device 200 determines the first carrier signal as the carrier signal Cb of the second phase switch branch.

[0093] At frame 1504B, in response to the third phase voltage not being greater than the first phase voltage, the control device 200 determines the second carrier signal as the carrier signal Cb of the second phase switch branch, and the second carrier signal and the first carrier signal have different phases.

[0094] like Figure 15C As shown, process 1500C illustrates an example process for determining the carrier signal Cc of the third phase switch branch.

[0095] At box 1501C, control device 200 compares the three-phase voltages based on the acquired voltage signals representing the three-phase voltages.

[0096] At frame 1502C, control device 200 determines whether the first phase voltage is greater than the second phase voltage.

[0097] At frame 1503C, in response to the first phase voltage being greater than the second phase voltage, the control device 200 determines the first carrier signal as the carrier signal Cc of the third phase switch branch.

[0098] At frame 1504C, in response to the first phase voltage not being greater than the second phase voltage, the control device 200 determines the second carrier signal as the carrier signal Cc of the third phase switch branch, and the second carrier signal and the first carrier signal have different phases.

[0099] Figure 16 A schematic flowchart of an example process 1600 for generating carrier signals Ca, Cb, and Cc is shown. Figure 16 The process shown can be performed in Figure 9 Implemented at box 902.

[0100] At box 1601, for each phase switch branch, control device 200 determines whether the phase voltage corresponding to that phase switch branch in the three-phase phase voltage is decreasing.

[0101] At frame 1602, in response to a decrease in the phase voltage corresponding to the phase switch branch, the control device 200 determines the first carrier signal as the carrier signal of the phase switch branch.

[0102] At block 1603, in response to the phase voltage corresponding to the phase switch branch not being decreasing, a second carrier signal is determined as the carrier signal of the phase switch branch, the second carrier signal having a different phase from the first carrier signal.

[0103] It is understood that although the embodiments of this disclosure have been described above with reference to a converter system employing rectification mode in the first scenario, the embodiments of this disclosure are equally applicable to converter systems employing inverter mode. Furthermore, the embodiments of this disclosure are also applicable to converter systems employing different modes. Figure 5 Other rectifier systems illustrating the modulation wave generation method. In other words, the solution disclosed herein can be used in any converter system that requires modulation waves and carrier waves to control the converter and may have common-mode voltage.

[0104] Figure 17 A schematic block diagram of an example device 1700 that can be used to implement embodiments of the present disclosure is shown. Device 1700 can be implemented as... Figure 1 , Figure 2 and Figure 4 The control device 200. The control device 200 can be used to implement Figure 9 Method 900.

[0105] As shown in the figure, device 1700 includes a central processing unit (CPU) 1701, which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) 1702 or loaded from storage unit 1708 into random access memory (RAM) 1703. RAM 1703 can also store various programs and data required for the operation of device 1700, such as the measurement data mentioned above. CPU 1701, ROM 1702, and RAM 1703 are interconnected via bus 1704. Input / output (I / O) interface 1705 is also connected to bus 1704.

[0106] Multiple components in device 1700 are connected to I / O interface 1705, including: input unit 1706, output unit 1707, storage unit 1708, and communication unit 1709. Communication unit 1709 allows device 1700 to exchange information / data with other devices via wired or wireless communication links.

[0107] Processing unit 1701 performs the method or process described above, method 900. For example, in some embodiments, method 900 may be implemented as a computer software program or computer program product tangibly contained in a machine-readable medium, such as a non-transient computer-readable medium, such as storage unit 1708. In some embodiments, part or all of the computer program may be loaded and / or installed on device 1700 via ROM 1702 and / or communication unit 1709. When the computer program is loaded into RAM 1703 and executed by CPU 1701, one or more steps of method 900 described above may be performed. Alternatively, in other embodiments, CPU 1701 may be configured to perform method 900 by any other suitable means (e.g., by means of firmware).

[0108] Those skilled in the art will understand that the various steps of the methods disclosed above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using device-executable program code, which can then be stored in a storage device for execution by the computing device. Alternatively, they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this disclosure is not limited to any particular combination of hardware and software.

[0109] It should be understood that although several devices or sub-devices of the device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more devices described above can be embodied in one device. Conversely, the features and functions of one device described above can be further divided and embodied by multiple devices.

[0110] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for controlling a converter, comprising: Acquire the voltage signal representing the three-phase phase voltage on the AC side of the converter; Based on the comparison of the voltage signals, the carrier signal of the three-phase switching branch of the converter is determined, wherein the phases of the carrier signals of two of the three phases are the same as each other and are different from the phase of the carrier signal of the remaining phase, and the magnitude of the phase voltage of the remaining phase is between the phase voltages of the two phases; and Based on the determined carrier signal and the modulation wave signal of the three-phase switch branch, the control signal of the three-phase switch branch is generated. The carrier signal for determining the three-phase switching branch of the converter based on the voltage signal includes: For each phase switch branch: In response to the phase voltage corresponding to the phase switch branch in the three-phase phase voltage being decreasing, the first carrier signal is determined as the carrier signal of the phase switch branch; or In response to the fact that the phase voltage corresponding to the phase switch branch in the three-phase phase voltage is not decreasing, a second carrier signal is determined as the carrier signal of the phase switch branch, the second carrier signal having a different phase from the first carrier signal.

2. The method according to claim 1, wherein the difference between the phase of the carrier signal of two of the three phases and the phase of the carrier signal of the remaining phase is in the range of 150 degrees to 210 degrees.

3. The method according to claim 2, wherein the phase difference between the carrier signals of two of the three phases and the phase difference between the carrier signal of the remaining phase is 180 degrees.

4. The method according to claim 1, wherein acquiring the voltage signal representing the three-phase phase voltage on the AC side of the converter comprises: The modulation wave signal of the three-phase switch branch is obtained as a voltage signal representing the three-phase phase voltage.

5. The method according to claim 1, wherein acquiring the voltage signal representing the three-phase phase voltage on the AC side of the converter comprises: The sensed signal of the AC side power supply voltage of the converter is obtained as a voltage signal representing the three-phase phase voltage.

6. The method according to claim 1, wherein the converter is a rectifier, and wherein the modulation wave signal is determined based on the DC side voltage, AC side power supply voltage and AC side inductor current of the rectifier.

7. The method according to claim 1, wherein generating the control signal for the three-phase switch branch based on the determined carrier signal and the modulation wave signal of the three-phase switch branch comprises: Based on the comparison between the determined carrier signal and the modulated wave signal, a pulse width modulation signal is generated as the control signal for the three-phase switch branch.

8. A converter system, comprising: Converter; as well as Control device for controlling the converter, the control device being configured to: Acquire voltage signals representing the three-phase phase voltages on the AC side of the converter; Based on the comparison of the voltage signals, the carrier signal of the three-phase switching branch of the converter is determined, wherein the phases of the carrier signals of two of the three phases are the same as each other and are different from the phase of the carrier signal of the remaining phase, and the magnitude of the phase voltage of the remaining phase is between the phase voltages of the two phases; and Based on the determined carrier signal and the modulation wave signal of the three-phase switch branch, the control signal of the three-phase switch branch is generated. The carrier signal for determining the three-phase switching branch of the converter based on the voltage signal includes: For each phase switch branch: In response to the phase voltage corresponding to the phase switch branch in the three-phase phase voltage being decreasing, the first carrier signal is determined as the carrier signal of the phase switch branch; or In response to the fact that the phase voltage corresponding to the phase switch branch in the three-phase phase voltage is not decreasing, a second carrier signal is determined as the carrier signal of the phase switch branch, the second carrier signal having a different phase from the first carrier signal.

9. The converter system according to claim 8, wherein the difference between the phase of the carrier signal of two of the three phases and the phase of the carrier signal of the remaining phase is in the range of 150 degrees to 210 degrees.

10. The converter system according to claim 9, wherein the phase difference between the carrier signal of two of the three phases and the phase difference between the carrier signal of the remaining phase is 180 degrees.

11. The converter system of claim 8, wherein acquiring voltage signals representing the three-phase phase voltages on the AC side of the converter comprises: The modulation wave signal of the three-phase switch branch is obtained as a voltage signal representing the three-phase phase voltage.

12. The converter system of claim 8, wherein acquiring voltage signals representing the three-phase phase voltages on the AC side of the converter comprises: The sensed signal of the AC side power supply voltage of the converter is obtained as a voltage signal representing the three-phase phase voltage.

13. The converter system of claim 8, wherein the converter is a rectifier, and wherein the modulation wave signal is determined based on the DC side voltage, AC side power supply voltage and AC side inductor current of the rectifier.

14. The converter system of claim 8, wherein generating the control signal for the three-phase switching branch based on the determined carrier signal and the modulation wave signal of the three-phase switching branch comprises: Based on the comparison between the determined carrier signal and the modulated wave signal, a pulse width modulation signal is generated as the control signal for the three-phase switch branch.

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