Ac / ac converter

Abstract

Provided in the present application is an AC / AC converter. The AC / AC converter comprises a first conversion unit, a matching unit and a second conversion unit which are sequentially connected in series, wherein the first conversion unit is used for generating a first half-wave voltage, and performing polarity inversion on the first half-wave voltage, so as to generate a first alternating-current voltage having alternating positive and negative polarities; the second conversion unit is used for generating a second half-wave voltage, and performing polarity inversion on the second half-wave voltage, so as to generate a second alternating-current voltage having alternating positive and negative polarities; and the matching unit is used for generating a first matching voltage, with the first matching voltage being the difference between the first half-wave voltage and the second half-wave voltage.

Description

An AC / AC converter

[0001] Cross-reference to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411189637.X, filed on August 28, 2024, entitled "An AC / AC Converter", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to, but is not limited to, the field of power transmission technology, and specifically to an AC / AC converter. Background Technology

[0004] Vigorously developing new energy sources and accelerating the decarbonization of the power sector are essential for promoting a clean energy transition. However, with the increasing proportion of new energy installed capacity, the lack of grid regulation capacity has become prominent, and the power frequency AC transmission system is unable to meet its wide-area networking and long-distance transmission needs. Flexible low-frequency AC transmission technology, by utilizing power electronics technology to flexibly select frequencies from 0-50Hz, can improve the grid's transmission capacity and flexible regulation capabilities while retaining the characteristics of AC transmission, such as electromagnetic induction transformation and zero-crossing current interruption. It is a new type of efficient AC transmission technology.

[0005] AC (Alternating Current) / AC converters are core equipment in flexible low-frequency AC transmission systems. While changing the frequency, they enable flexible control of the power grid, such as power flow regulation and voltage regulation. Related technologies utilize a modular multilevel matrix converter (M3C) topology. The M3C has nine arms, each of which must withstand power frequency / low-frequency peak voltages. The large number of submodules results in a complex AC / AC converter structure and high cost. Summary of the Invention

[0006] To address the issues of complex structure and high cost in existing technologies, this disclosure provides an AC / AC converter, comprising a first conversion unit, a matching unit, and a second conversion unit connected in series.

[0007] The first conversion unit is configured to generate a first half-wave voltage and reverse the polarity of the first half-wave voltage to generate a first alternating positive and negative AC voltage.

[0008] The second conversion unit is configured to generate a second half-wave voltage and reverse the polarity of the second half-wave voltage to generate a second AC voltage with alternating positive and negative values.

[0009] The matching unit is configured to generate a first matching voltage. The first matching voltage is the difference between the sum of the first half-wave voltage and the second half-wave voltage.

[0010] In some implementations, the first transformation unit includes a first transformation sub-unit and a first inversion unit connected in parallel.

[0011] The first transformation subunit is configured to generate a first half-wave voltage based on one or more cascaded submodules. The submodules are either half-bridge or full-bridge submodules.

[0012] The first inversion unit is configured to: reverse the polarity of the first half-wave voltage according to a first preset frequency and a first preset phase angle, based on one or more series-connected semiconductor switches, to generate a first AC voltage.

[0013] In some implementations, the second transformation unit includes a second transformation sub-unit and a second inversion unit connected in parallel.

[0014] The second conversion subunit is configured to generate a second half-wave voltage based on one or more cascaded submodules. The submodules can be either half-bridge or full-bridge submodules.

[0015] The second inversion unit is configured to: reverse the polarity of the second half-wave voltage according to a second preset frequency and a second preset phase angle, based on one or more series-connected semiconductor switches, to generate a second AC voltage.

[0016] In some implementations, a first AC voltage is used as the input voltage of the AC / AC converter and a second AC voltage is used as the output voltage of the AC / AC converter. Alternatively, the first AC voltage is used as the output voltage of the AC / AC converter and the second AC voltage is used as the input voltage of the AC / AC converter.

[0017] In some implementations, the AC / AC converter also includes a third conversion unit and a fourth conversion unit.

[0018] The third transformation unit, the first transformation unit, the matching unit, the second transformation unit, and the fourth transformation unit are connected in series.

[0019] In some implementations, the third conversion unit is configured to generate a third half-wave voltage and reverse the polarity of the third half-wave voltage to generate a third AC voltage with alternating positive and negative values.

[0020] The fourth conversion unit is configured to generate a fourth half-wave voltage and reverse the polarity of the fourth half-wave voltage to generate a fourth alternating positive and negative AC voltage.

[0021] The matching unit is also configured to generate a second matching voltage. The second matching voltage is the difference between the first pooling voltage and the second pooling voltage. The first pooling voltage is configured to indicate the sum of the first half-wave voltage and the third half-wave voltage, and the second pooling voltage is configured to indicate the sum of the second half-wave voltage and the fourth half-wave voltage.

[0022] In some implementations, the third transformation unit includes a third transformation sub-unit and a third inversion unit connected in parallel.

[0023] The third transformation subunit is configured to generate a third half-wave voltage based on one or more cascaded submodules. The submodules are either half-bridge or full-bridge submodules.

[0024] The third inversion unit is configured to: reverse the polarity of the third half-wave voltage according to a third preset frequency and a third preset phase angle, based on one or more series-connected semiconductor switches, to generate a third AC voltage.

[0025] In some implementations, the fourth transformation unit includes a fourth transformation sub-unit and a fourth inversion unit connected in parallel.

[0026] The fourth transformation subunit is configured to generate a fourth half-wave voltage based on one or more cascaded submodules. These submodules can be either half-bridge or full-bridge submodules.

[0027] The fourth inversion unit is configured to: reverse the polarity of the fourth half-wave voltage according to a fourth preset frequency and a fourth preset phase angle, based on one or more series-connected semiconductor switches, to generate a fourth AC voltage.

[0028] In some implementations, the AC / AC converter also includes a first transformer and a second transformer.

[0029] The first winding of the first transformer is configured to output a third AC voltage, and the second winding of the first transformer is connected to a third conversion unit. The first winding of the second transformer is configured to output a fourth AC voltage, and the second winding of the first transformer is connected to a fourth conversion unit.

[0030] The first transformer is configured to: convert the voltage level of the third AC voltage and output it, and to isolate the third conversion unit from the first conversion unit.

[0031] The second transformer is configured to: convert the fourth AC voltage to a different voltage level and output it, and to isolate the fourth conversion unit from the second conversion unit.

[0032] In some implementations, the first and third AC voltages are used as the input voltages of the AC / AC converter, and the second and fourth AC voltages are used as the output voltages of the AC / AC converter. Alternatively, the first and third AC voltages are used as the output voltages of the AC / AC converter, and the second and fourth AC voltages are used as the input voltages of the AC / AC converter.

[0033] In some implementations, the AC / AC converter also includes a fifth conversion unit and a sixth conversion unit.

[0034] The fifth transformation unit, the third transformation unit, the first transformation unit, the matching unit, the second transformation unit, the fourth transformation unit, and the sixth transformation unit are connected in series.

[0035] In some implementations, the fifth conversion unit is configured to generate a fifth half-wave voltage and reverse the polarity of the fifth half-wave voltage to generate a fifth alternating positive and negative AC voltage.

[0036] The sixth conversion unit is configured to generate a sixth half-wave voltage and reverse the polarity of the sixth half-wave voltage to generate a sixth alternating positive and negative AC voltage.

[0037] The matching unit is also configured to generate a third matching voltage. The third matching voltage is the difference between the third pooling voltage and the fourth pooling voltage. The third pooling voltage is configured to indicate the sum of the first half-wave voltage, the third half-wave voltage, and the fifth half-wave voltage, and the fourth pooling voltage is configured to indicate the sum of the second half-wave voltage, the fourth half-wave voltage, and the sixth half-wave voltage.

[0038] The fifth transformation unit includes a fifth transformation sub-unit and a fifth inversion unit connected in parallel.

[0039] The fifth transformation subunit is configured to generate a fifth half-wave voltage based on one or more cascaded submodules. These submodules can be either half-bridge or full-bridge submodules.

[0040] The fifth inversion unit is configured to: reverse the polarity of the fifth half-wave voltage according to a fifth preset frequency and a fifth preset phase angle, based on one or more series-connected semiconductor switches, to generate a fifth AC voltage.

[0041] The sixth transformation unit includes a sixth transformation sub-unit and a sixth inversion unit connected in parallel.

[0042] The sixth transformation subunit is configured to generate a sixth half-wave voltage based on one or more cascaded submodules. These submodules can be either half-bridge or full-bridge submodules.

[0043] The sixth inversion unit is configured to: reverse the polarity of the sixth half-wave voltage according to a sixth preset frequency and a sixth preset phase angle, based on one or more series-connected semiconductor switches, to generate a sixth AC voltage.

[0044] In some implementations, the AC / AC converter also includes a third transformer and a fourth transformer.

[0045] The first winding of the third transformer is configured to output the fifth AC voltage, and the second winding of the third transformer is connected to the fifth conversion unit.

[0046] The first winding of the fourth transformer is configured to output the sixth AC voltage, and the second winding of the fourth transformer is connected to the sixth conversion unit.

[0047] The third transformer is configured to: convert the fifth AC voltage to a different voltage level and output it, and to isolate the fifth conversion unit from the first conversion unit.

[0048] The fourth transformer is configured to: convert the sixth AC voltage to a different voltage level and output it, and to isolate the sixth conversion unit from the second conversion unit.

[0049] In some implementations, the first, third, and fifth AC voltages are used as the input voltages of the AC / AC converter, and the second, fourth, and sixth AC voltages are used as the output voltages of the AC / AC converter. Alternatively, the first, third, and fifth AC voltages are used as the output voltages of the AC / AC converter, and the second, fourth, and sixth AC voltages are used as the input voltages of the AC / AC converter.

[0050] In some implementations, AC / AC converters also include arm inductors.

[0051] The bridge arm inductor is located between the first conversion unit and the matching unit, or the bridge arm inductor is located between the second conversion unit and the matching unit.

[0052] In some implementations, the AC / AC converter also includes a fifth transformer and a sixth transformer.

[0053] The first winding of the fifth transformer is configured to output the first AC voltage, and the second winding of the fifth transformer is connected to the first conversion unit.

[0054] The first winding of the sixth transformer is configured to output a second AC voltage, and the second winding of the sixth transformer is connected to the second conversion unit.

[0055] The fifth transformer is configured to perform voltage level transformation on the first AC voltage and output it.

[0056] The sixth transformer is configured to perform voltage level transformation on the second AC voltage and output it.

[0057] Compared with the prior art, the embodiments of this disclosure can achieve at least the following technical effects:

[0058] The AC / AC converter disclosed herein includes a first conversion unit, a matching unit, and a second conversion unit connected in series. The first conversion unit generates a first half-wave voltage and reverses its polarity to generate an alternating positive and negative first AC voltage. The second conversion unit generates a second half-wave voltage and reverses its polarity to generate an alternating positive and negative second AC voltage. The matching unit generates a first matching voltage. The first matching voltage is the difference between the sum of the first and second half-wave voltages. In this disclosure, the first and second conversion units only need to handle the voltage of a maximum of one voltage peak. Compared to M3C, the AC / AC converter provided herein reduces the number of sub-modules, resulting in a simpler structure and significantly lower costs.

[0059] In this disclosure, the reversing unit uses one or more series-connected semiconductor switches to reverse the polarity of the half-wave voltage. Compared with the sub-modules used in related technologies, the reversing unit does not require a supporting capacitor. The multiple series-connected semiconductor switches only operate when the voltage crosses zero, resulting in low losses in the semiconductor switches and thus reducing the losses of the reversing unit.

[0060] The AC / AC converter topology disclosed herein is symmetrical, with the collected voltage primarily being DC voltage. Power is mainly transferred via DC current, and the frequency coupling effect between the input and output terminals is relatively small.

[0061] In this disclosure, the third matching voltage generated by the matching unit is the difference between the third and fourth pooling voltages. The third pooling voltage indicates the sum of the first, third, and fifth half-wave voltages, while the fourth pooling voltage indicates the sum of the second, fourth, and sixth half-wave voltages. Because the third and fourth pooling voltages are relatively high, the current flowing through the matching unit in the AC / AC converter provided in this disclosure is smaller for the same power output, allowing the matching unit to employ semiconductor switches with small current amplitudes. Furthermore, the difference between the third and fourth pooling voltages borne by the matching unit is much smaller than a voltage peak, reducing the number of sub-modules in the matching unit, thereby lowering the cost of the AC / AC converter and simplifying its topology.

[0062] The transformer in this disclosure can isolate series-connected conversion units, preventing the supporting capacitor of a submodule in one conversion unit from forming a closed loop with the conducting power transistor in another conversion unit, thereby preventing the supporting capacitor from burning out. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 is a schematic structural diagram of an AC / AC converter in an embodiment of this disclosure;

[0065] Figure 2 is another schematic structural diagram of the AC / AC converter in an embodiment of this disclosure;

[0066] Figure 3 is another schematic structural diagram of the AC / AC converter in an embodiment of this disclosure;

[0067] Figure 4a is a schematic structural diagram of a half-bridge submodule in an embodiment of this disclosure;

[0068] Figure 4b is a schematic structural diagram of a full-bridge submodule in an embodiment of this disclosure;

[0069] Figure 5 is a schematic structural diagram of an AC / AC converter in an embodiment of this disclosure. Detailed Implementation

[0070] The technical solutions in this disclosure will now be described with reference to the accompanying drawings.

[0071] The terms "first," "second," etc., used in the embodiments, claims, and drawings of this disclosure are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0072] It should be understood that in this disclosure, "at least one item" means one or more, and "more than one" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0073] This disclosure provides an AC / AC converter, as shown in Figure 1. The AC / AC converter 100 includes a first conversion unit 1, a matching unit 7, and a second conversion unit 2 connected in series.

[0074] The first conversion unit 1 is configured to generate a first half-wave voltage and reverse the polarity of the first half-wave voltage to generate a first alternating positive and negative AC voltage Ua.

[0075] The second conversion unit 2 is configured to generate a second half-wave voltage and reverse the polarity of the second half-wave voltage to generate a second AC voltage Uu with alternating positive and negative values.

[0076] Matching unit 7 is configured to generate a first matching voltage. The first matching voltage is the difference between the sum of the first half-wave voltage and the second half-wave voltage.

[0077] In some implementations, the first half-wave voltage and the second half-wave voltage have the same polarity and can be positive voltages with a specific amplitude and frequency, which are composed of the positive half-cycles of a sine wave with that specific amplitude and frequency.

[0078] In some embodiments, a first AC voltage Ua is used as the input voltage of the AC / AC converter 100 and a second AC voltage Uu is used as the output voltage of the AC / AC converter 100. Alternatively, the first AC voltage Ua is used as the output voltage of the AC / AC converter 100 and the second AC voltage Uu is used as the input voltage of the AC / AC converter 100. It can be seen that the AC / AC converter 100 can be a single-phase converter.

[0079] In one possible implementation, referring to FIG1, the first transformation unit 1 includes a first transformation subunit 11 and a first inversion unit 12 connected in parallel.

[0080] The first transformation subunit 11 is configured to generate a first half-wave voltage based on one or more cascaded submodules.

[0081] The first inversion unit 12 is configured to: reverse the polarity of the first half-wave voltage according to a first preset frequency and a first preset phase angle, based on one or more series-connected semiconductor switches, to generate a first AC voltage Ua.

[0082] In another possible implementation, referring to FIG1, the second transformation unit 2 includes a second transformation subunit 21 and a second inversion unit 22 connected in parallel.

[0083] The second transformation subunit 21 is configured to generate a second half-wave voltage based on one or more cascaded submodules.

[0084] The second inversion unit 22 is configured to: reverse the polarity of the second half-wave voltage according to a second preset frequency and a second preset phase angle, based on one or more series-connected semiconductor switches, to generate a second AC voltage Uu.

[0085] In some embodiments, as shown in FIG2, the AC / AC converter 100 further includes a third conversion unit 3 and a fourth conversion unit 4.

[0086] The third transformation unit 3, the first transformation unit 1, the matching unit 7, the second transformation unit 2, and the fourth transformation unit 4 are connected in series.

[0087] In some implementations, the third conversion unit 3 is configured to generate a third half-wave voltage and reverse the polarity of the third half-wave voltage to generate a third alternating positive and negative AC voltage Ub.

[0088] The fourth conversion unit 4 is configured to generate a fourth half-wave voltage and reverse the polarity of the fourth half-wave voltage to generate a fourth AC voltage Uv with alternating positive and negative values.

[0089] Matching unit 7 is further configured to generate a second matching voltage. The second matching voltage is the difference between the first pooling voltage and the second pooling voltage. The first pooling voltage is configured to indicate the sum of the first half-wave voltage and the third half-wave voltage, and the second pooling voltage is configured to indicate the sum of the second half-wave voltage and the fourth half-wave voltage.

[0090] In some embodiments, the first AC voltage Ua and the third AC voltage Ub are used as the input voltages of the AC / AC converter 100, and the second AC voltage Uu and the fourth AC voltage Uv are used as the output voltages of the AC / AC converter 100. Alternatively, the first AC voltage Ua and the third AC voltage Ub are used as the output voltages of the AC / AC converter 100, and the second AC voltage Uu and the fourth AC voltage Uv are used as the input voltages of the AC / AC converter 100. It can be seen that the AC / AC converter 100 can be a two-phase converter.

[0091] In one possible implementation, as shown in Figure 2, the third transformation unit 3 includes a third transformation subunit 31 and a third inversion unit 32 connected in parallel.

[0092] The third transformation subunit 31 is configured to generate a third half-wave voltage based on one or more cascaded submodules.

[0093] The third inversion unit 32 is configured to: reverse the polarity of the third half-wave voltage according to a third preset frequency and a third preset phase angle, based on one or more series-connected semiconductor switches, to generate a third AC voltage Ub.

[0094] In another possible implementation, as shown in Figure 2, the fourth transformation unit 4 includes a fourth transformation subunit 41 and a fourth inversion unit 42 connected in parallel.

[0095] The fourth transformation subunit 41 is configured to generate a fourth half-wave voltage based on one or more cascaded submodules.

[0096] The fourth inversion unit 42 is configured to: reverse the polarity of the fourth half-wave voltage according to a fourth preset frequency and a fourth preset phase angle, based on one or more series-connected semiconductor switches, to generate a fourth AC voltage Uv.

[0097] In some embodiments, as shown in FIG3, the AC / AC converter 100 further includes a fifth conversion unit 5 and a sixth conversion unit 6.

[0098] The fifth transformation unit 5, the third transformation unit 3, the first transformation unit 1, the matching unit 7, the second transformation unit 2, the fourth transformation unit 4, and the sixth transformation unit 6 are connected in series.

[0099] In some implementations, the fifth conversion unit 5 is configured to generate a fifth half-wave voltage and reverse the polarity of the fifth half-wave voltage to generate a fifth alternating positive and negative AC voltage Uc.

[0100] The sixth conversion unit 6 is configured to generate a sixth half-wave voltage and reverse the polarity of the sixth half-wave voltage to generate a sixth alternating positive and negative AC voltage Uw.

[0101] Matching unit 7 is further configured to generate a third matching voltage. The third matching voltage is the difference between the third pooling voltage and the fourth pooling voltage. The third pooling voltage is configured to indicate the sum of the first half-wave voltage, the third half-wave voltage, and the fifth half-wave voltage, and the fourth pooling voltage is configured to indicate the sum of the second half-wave voltage, the fourth half-wave voltage, and the sixth half-wave voltage.

[0102] In some embodiments, the first AC voltage Ua, the third AC voltage Ub, and the fifth AC voltage Uc are used as the input voltages of the AC / AC converter 100, and the second AC voltage Uu, the fourth AC voltage Uv, and the sixth AC voltage Uw are used as the output voltages of the AC / AC converter 100. Alternatively, the first AC voltage Ua, the third AC voltage Ub, and the fifth AC voltage Uc are used as the output voltages of the AC / AC converter 100, and the second AC voltage Uu, the fourth AC voltage Uv, and the sixth AC voltage Uw are used as the input voltages of the AC / AC converter 100. It can be seen that the AC / AC converter shown in Figure 3 can be a three-phase converter.

[0103] Referring to Figure 3, the fifth transformation unit 5 includes a fifth transformation subunit 51 and a fifth inversion unit 52 connected in parallel.

[0104] The fifth transformation subunit 51 is configured to generate a fifth half-wave voltage based on one or more cascaded submodules.

[0105] The fifth inversion unit 52 is configured to: reverse the polarity of the fifth half-wave voltage according to a fifth preset frequency and a fifth preset phase angle, based on one or more series-connected semiconductor switches, to generate a fifth AC voltage Uc.

[0106] Referring to Figure 3, the sixth transformation unit 6 includes a sixth transformation subunit 61 and a sixth inversion unit 62 connected in parallel.

[0107] The sixth transformation subunit 61 is configured to generate a sixth half-wave voltage Uw based on one or more cascaded submodules.

[0108] The sixth inversion unit 62 is configured to: reverse the polarity of the sixth half-wave voltage according to a sixth preset frequency and a sixth preset phase angle, based on one or more series-connected semiconductor switches, to generate a sixth AC voltage Uw.

[0109] In this embodiment of the disclosure, the first AC voltage Ua, the third AC voltage Ub and the fifth AC voltage Uc can be power frequency voltages (i.e., voltages with a frequency of 50Hz), and the second AC voltage Uu, the fourth AC voltage Uv and the sixth AC voltage Uw can be low frequency voltages (i.e., voltages with a frequency of 20Hz).

[0110] Therefore, the first, third, and fifth preset frequencies can all be 50Hz, and the second, fourth, and sixth preset frequencies can all be 20Hz.

[0111] The phase angle difference between the first preset phase angle and the third preset phase angle is 120°, and the phase angle difference between the third preset phase angle and the fifth preset phase angle is 120°. For example, if the third preset phase angle can be 0°, then the first preset phase angle can be -120°, and the fifth preset phase angle can be +120°.

[0112] Similarly, the phase angle difference between the second preset phase angle and the fourth preset phase angle is 120°, and the phase angle difference between the fourth preset phase angle and the sixth preset phase angle is 120°. For example, if the fourth preset phase angle can be 0°, then the second preset phase angle can be -120°, and the sixth preset phase angle can be +120°.

[0113] In some implementations, the aforementioned submodule can be a half-bridge submodule as shown in Figure 4a or a full-bridge submodule as shown in Figure 4b. Referring to Figure 4a, the half-bridge submodule includes parallel bridge arms and a supporting capacitor C1. The bridge arm includes power transistors S1 and S2 connected in series. Referring to Figure 4b, the full-bridge submodule includes a first bridge arm, a second bridge arm, and a supporting capacitor C2 connected in parallel. The supporting capacitor C2 is connected in parallel with the two bridge arms. The first bridge arm includes power transistors S1 and S2 connected in series, and the second bridge arm includes power transistors S3 and S4 connected in series. That is, each bridge arm is composed of two power transistors connected in series. The power transistors can be power electronic switching devices such as IGBTs. IGBTs can be anti-parallel diodes.

[0114] It is conceivable that not all submodules are engaged; the amplitude of the half-wave voltage can be determined by controlling the number of engaged submodules. It is also conceivable that the AC / AC converter 100 provided in this embodiment can be a multi-level converter, and the number of submodules is determined by the number of levels. For example, when the number of levels is n, the number of submodules can be (n-1) / 2.

[0115] For example, as shown in Figure 5, the AC / AC converter 100 also includes a first transformer T1 and a second transformer T2.

[0116] The first winding of the first transformer T1 is configured to output a third AC voltage Ub, and the second winding of the first transformer T1 is connected to the third conversion unit 3 (which can be the third reversing unit 31 of the third conversion unit 3). The first winding of the second transformer T2 is configured to output a fourth AC voltage Uv, and the second winding of the second transformer T2 is connected to the fourth conversion unit 4 (which can be the fourth reversing unit 41 of the fourth conversion unit 4).

[0117] The first transformer T1 is configured to: perform voltage level conversion on the third AC voltage Ub and output it, and isolate the third conversion unit 3 and the first conversion unit 1.

[0118] The second transformer T2 is configured to: perform voltage level conversion on the fourth AC voltage Uv and output it, and isolate the fourth conversion unit 4 and the second conversion unit 2.

[0119] In some implementations, as shown in FIG5, the AC / AC converter 100 further includes a third transformer T3 and a fourth transformer T4.

[0120] The first winding of the third transformer T3 is configured to output the fifth AC voltage Uc, and the second winding of the third transformer T3 is connected to the fifth conversion unit 5 (which can be the fifth reversing unit 51 of the fifth conversion unit 5). The first winding of the fourth transformer T4 is configured to output the sixth AC voltage Uw, and the second winding of the fourth transformer T4 is connected to the sixth conversion unit 6 (which can be the sixth reversing unit 61 of the sixth conversion unit 6).

[0121] The third transformer T3 is configured to: transform the voltage level of the fifth AC voltage Uc and output it, and isolate the fifth transformation unit 5 and the first transformation unit 1.

[0122] The fourth transformer T4 is configured to: transform the voltage level of the sixth AC voltage Uw and output it, and isolate the sixth transformation unit 6 and the second transformation unit 2.

[0123] In some possible implementations, as shown in Figure 5, the AC / AC converter 100 also includes a bridge arm inductor L.

[0124] The bridge arm inductor L is located between the first conversion unit 1 and the matching unit 7, or the bridge arm inductor L is located between the second conversion unit 2 and the matching unit 7. In this embodiment of the present disclosure, the bridge arm inductor L is located between the first conversion unit 1 and the matching unit 7.

[0125] In some implementations, referring to FIG5, the AC / AC converter 100 further includes a fifth transformer T5 and a sixth transformer T6.

[0126] The first winding of the fifth transformer T5 is configured to output the first AC voltage Ua, and the second winding of the fifth transformer T5 is connected to the first conversion unit 1 (which can be the first reversing unit 12 of the first conversion unit 1).

[0127] The first winding of the sixth transformer T6 is configured to output a second AC voltage Uu, and the second winding of the sixth transformer T6 is connected to the second conversion unit 2 (which can be the second reversing unit 22 of the second conversion unit 2).

[0128] The fifth transformer T5 is configured to: transform the voltage level of the first AC voltage Ua and output it.

[0129] The sixth transformer T6 is configured to: transform the voltage level of the second AC voltage Uu and output it.

[0130] As shown in Figure 5, each inversion unit can include multiple series-connected semiconductor switches, and each conversion subunit can include multiple cascaded submodules SM (i.e., submodules SM1 to SMN in Figure 5). The matching unit 7 can also include multiple cascaded submodules SM (i.e., submodules SM1 to SMN in Figure 5).

[0131] In Figure 5, A, B, and C constitute the input terminals of the three-phase converter, while U, V, and W constitute the output terminals. Of course, since the three-phase converter is a bidirectional converter, A, B, and C can also serve as the output terminals, and U, V, and W as the input terminals.

[0132] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval. Industrial applicability

[0133] This disclosure provides an AC / AC converter, including a first conversion unit, a matching unit, and a second conversion unit connected in series. The first conversion unit is used to generate a first half-wave voltage and reverse the polarity of the first half-wave voltage to generate an alternating positive and negative first AC voltage. The second conversion unit is used to generate a second half-wave voltage and reverse the polarity of the second half-wave voltage to generate an alternating positive and negative second AC voltage. The matching unit is used to generate a first matching voltage, wherein the first matching voltage is the difference between the sum of the first half-wave voltage and the second half-wave voltage. In the above scheme, the first and second conversion units only need to handle the voltage of a maximum of one voltage peak, the number of sub-modules is small, making the AC / AC converter structure simple and low in cost.

Claims

1. An AC / AC converter, comprising a first conversion unit, a matching unit, and a second conversion unit connected in series; The first conversion unit is configured to generate a first half-wave voltage and reverse the polarity of the first half-wave voltage to generate a first alternating positive and negative AC voltage. The second conversion unit is configured to generate a second half-wave voltage and reverse the polarity of the second half-wave voltage to generate a second alternating positive and negative AC voltage. The matching unit is configured to generate a first matching voltage; wherein... The first matching voltage is the difference between the sum of the first half-wave voltage and the second half-wave voltage.

2. The AC / AC converter according to claim 1, wherein the first conversion unit comprises a first conversion sub-unit and a first inversion unit connected in parallel; The first transformation subunit is configured to generate the first half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The first inversion unit is configured to: reverse the polarity of the first half-wave voltage according to a first preset frequency and a first preset phase angle, based on one or more series-connected semiconductor switches, to generate the first AC voltage.

3. The AC / AC converter according to claim 1, wherein the second conversion unit comprises a second conversion sub-unit and a second inversion unit connected in parallel; The second transformation subunit is configured to generate the second half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The second inversion unit is configured to: reverse the polarity of the second half-wave voltage according to a second preset frequency and a second preset phase angle, based on one or more series-connected semiconductor switches, to generate the second AC voltage.

4. The AC / AC converter according to claim 1, wherein the first AC voltage is used as the input voltage of the AC / AC converter and the second AC voltage is used as the output voltage of the AC / AC converter; or, the first AC voltage is used as the output voltage of the AC / AC converter and the second AC voltage is used as the input voltage of the AC / AC converter.

5. The AC / AC converter according to claim 1, wherein the AC / AC converter further comprises a third conversion unit and a fourth conversion unit; The third transformation unit, the first transformation unit, the matching unit, the second transformation unit, and the fourth transformation unit are connected in series.

6. The AC / AC converter according to claim 5, The third conversion unit is configured to generate a third half-wave voltage and reverse the polarity of the third half-wave voltage to generate a third alternating positive and negative AC voltage. The fourth conversion unit is configured to generate a fourth half-wave voltage and reverse the polarity of the fourth half-wave voltage to generate a fourth alternating positive and negative AC voltage. The matching unit is further configured to generate a second matching voltage; wherein... The second matching voltage is the difference between the first pooling voltage and the second pooling voltage; the first pooling voltage is configured to indicate the sum of the first half-wave voltage and the third half-wave voltage, and the second pooling voltage is configured to indicate the sum of the second half-wave voltage and the fourth half-wave voltage.

7. The AC / AC converter according to claim 6, wherein the third conversion unit comprises a third conversion sub-unit and a third inversion unit connected in parallel; The third transformation subunit is configured to generate the third half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The third inversion unit is configured to: reverse the polarity of the third half-wave voltage according to a third preset frequency and a third preset phase angle, based on one or more series-connected semiconductor switches, to generate the third AC voltage.

8. The AC / AC converter according to claim 6, wherein the fourth conversion unit comprises a fourth conversion sub-unit and a fourth inversion unit connected in parallel; The fourth transformation subunit is configured to generate the fourth half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The fourth inversion unit is configured to: reverse the polarity of the fourth half-wave voltage according to a fourth preset frequency and a fourth preset phase angle, based on one or more series-connected semiconductor switches, to generate the fourth AC voltage.

9. The AC / AC converter according to claim 6, wherein the AC / AC converter further comprises a first transformer and a second transformer; The first winding of the first transformer is configured to output the third AC voltage, and the second winding of the first transformer is connected to the third conversion unit; the first winding of the second transformer is configured to output the fourth AC voltage, and the second winding of the second transformer is connected to the fourth conversion unit. The first transformer is configured to: convert the voltage level of the third AC voltage and output it, and to isolate the third conversion unit from the first conversion unit; The second transformer is configured to: perform voltage level conversion on the fourth AC voltage and output it, and isolate the fourth conversion unit and the second conversion unit.

10. The AC / AC converter according to claim 6, wherein the first AC voltage and the third AC voltage are used as the input voltage of the AC / AC converter and the second AC voltage and the fourth AC voltage are used as the output voltage of the AC / AC converter; or, the first AC voltage and the third AC voltage are used as the output voltage of the AC / AC converter and the second AC voltage and the fourth AC voltage are used as the input voltage of the AC / AC converter.

11. The AC / AC converter according to claim 6, wherein the AC / AC converter further comprises a fifth conversion unit and a sixth conversion unit; The fifth transformation unit, the third transformation unit, the first transformation unit, the matching unit, the second transformation unit, the fourth transformation unit, and the sixth transformation unit are connected in series.

12. The AC / AC converter according to claim 11, The fifth conversion unit is configured to generate a fifth half-wave voltage and reverse the polarity of the fifth half-wave voltage to generate a fifth alternating positive and negative AC voltage. The sixth conversion unit is configured to generate a sixth half-wave voltage and reverse the polarity of the sixth half-wave voltage to generate a sixth alternating positive and negative AC voltage. The matching unit is further configured to generate a third matching voltage; wherein... The third matching voltage is the difference between the third pooling voltage and the fourth pooling voltage; the third pooling voltage is configured to indicate the sum of the first half-wave voltage, the third half-wave voltage, and the fifth half-wave voltage, and the fourth pooling voltage is configured to indicate the sum of the second half-wave voltage, the fourth half-wave voltage, and the sixth half-wave voltage.

13. The AC / AC converter according to claim 12, wherein the fifth conversion unit comprises a fifth conversion sub-unit and a fifth inversion unit connected in parallel; The fifth transformation subunit is configured to generate the fifth half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The fifth inversion unit is configured to: reverse the polarity of the fifth half-wave voltage according to a fifth preset frequency and a fifth preset phase angle, based on one or more series-connected semiconductor switches, to generate the fifth AC voltage.

14. The AC / AC converter according to claim 12, wherein the sixth conversion unit comprises a sixth conversion sub-unit and a sixth inversion unit connected in parallel; The sixth transformation subunit is configured to generate the sixth half-wave voltage based on one or more cascaded submodules; wherein, The submodule is a half-bridge submodule or a full-bridge submodule; The sixth inversion unit is configured to: reverse the polarity of the sixth half-wave voltage according to a sixth preset frequency and a sixth preset phase angle, based on one or more series-connected semiconductor switches, to generate the sixth AC voltage.

15. The AC / AC converter according to claim 12, wherein the AC / AC converter further comprises a third transformer and a fourth transformer; The first winding of the third transformer is configured to output the fifth AC voltage, and the second winding of the third transformer is connected to the fifth conversion unit; The first winding of the fourth transformer is configured to output the sixth AC voltage, and the second winding of the fourth transformer is connected to the sixth conversion unit; The third transformer is configured to: convert the voltage level of the fifth AC voltage and output it, and isolate the fifth conversion unit from the first conversion unit; The fourth transformer is configured to: perform voltage level conversion on the sixth AC voltage and output it, and isolate the sixth conversion unit and the second conversion unit.

16. The AC / AC converter according to claim 12, wherein the first AC voltage, the third AC voltage, and the fifth AC voltage are the input voltages of the AC / AC converter, and the second AC voltage, the fourth AC voltage, and the sixth AC voltage are the output voltages of the AC / AC converter; or, the first AC voltage, the third AC voltage, and the fifth AC voltage are the output voltages of the AC / AC converter, and the second AC voltage, the fourth AC voltage, and the sixth AC voltage are the input voltages of the AC / AC converter.

17. The AC / AC converter according to claim 1, wherein the AC / AC converter further comprises a bridge arm inductor; The bridge arm inductor is located between the first conversion unit and the matching unit, or the bridge arm inductor is located between the second conversion unit and the matching unit.

18. The AC / AC converter according to claim 1, wherein the AC / AC converter further comprises a fifth transformer and a sixth transformer; The first winding of the fifth transformer is configured to output the first AC voltage, and the second winding of the fifth transformer is connected to the first conversion unit; The first winding of the sixth transformer is configured to output the second AC voltage, and the second winding of the sixth transformer is connected to the second conversion unit; The fifth transformer is configured to: perform voltage level transformation on the first AC voltage and output it; The sixth transformer is configured to perform voltage level transformation on the second AC voltage and output it.

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