A non-isolated AC / DC power supply system

Abstract

The present invention provides a non-isolated AC / DC power supply system, comprising: an AC system, a grounding device, a converter system, a common-mode voltage elimination circuit, and a DC system. The three-phase AC lines of the AC system are respectively connected to the three-phase AC lines of the converter system and to the first, second, and third ends of the grounding device; the fourth end of the grounding device is connected to the neutral line of the AC system and to ground; the converter system is also connected to the first end of the common-mode voltage elimination circuit; the DC side of the converter system is correspondingly connected to the second and third ends of the common-mode voltage elimination circuit via two DC busbars, and the output end of the common-mode voltage elimination circuit is connected to the DC system via two common DC busbars. By implementing the present invention, common-mode voltage is eliminated, the quality of the power supply voltage is improved, and thus the reliability of the power supply is improved.

Description

Technical Field

[0001] The present invention relates to the field of AC / DC power supply systems, and in particular to a non-isolated AC / DC power supply system. Background Art

[0002] AC / DC power supply systems (or devices) are core components of AC / DC distribution networks, playing a crucial role in power conversion (including voltage level conversion, frequency conversion, and AC / DC power supply mode conversion) and supply. Their core technology is power electronics. In practical application designs, to increase power density, reduce manufacturing costs, or address other design considerations, high-power, three-phase, three-wire, non-isolated AC / DC converters (AC / DC) are typically used on the AC side of the device to power AC loads, while high-power, non-isolated DC / DC converters (DC / DC) are used on the DC side of the device to power DC loads.

[0003] Since the power supply system uses a large number of converter devices, the AC and DC busbars will generate excessively high common-mode voltage due to the PWM (pulse width modulation) technology used by the converters, damaging the AC and DC loads and thus affecting the normal operation of the AC and DC power supply system. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that an excessively high common-mode voltage is generated on the AC / DC bus due to the converter using PWM (pulse width modulation) technology, thereby providing a non-isolated AC / DC power supply system.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An embodiment of the present invention provides a non-isolated AC / DC power supply system, comprising: an AC system, a grounding device, a converter system, a common-mode voltage elimination circuit and a DC system, wherein the three-phase AC lines of the AC system are respectively connected to the three-phase AC lines of the converter system, and are connected to the first end, the second end and the third end of the grounding device; the fourth end of the grounding device is connected to the neutral line of the AC system and is grounded; the converter system is also connected to the first end of the common-mode voltage elimination circuit; the DC side of the converter system is correspondingly connected to the second end and the third end of the common-mode voltage elimination circuit through two DC buses, and the output end of the common-mode voltage elimination circuit is connected to the DC system through two common DC buses; the common-mode voltage elimination circuit is used to suppress the common-mode voltage between the AC and DC sides of the converter system, and convert this common-mode voltage into a reverse induced voltage of corresponding proportion, and connect it in series into the two common DC bus-to-ground loops to offset the common-mode voltage remaining after suppression.

[0007] Optionally, the DC system includes: multiple DC / DC devices, the input end of each DC / DC device is respectively connected to two common DC buses, and the output end of each DC / DC device is connected to an external load, for providing a corresponding level of voltage to the connected external load.

[0008] Optionally, the common-mode voltage elimination circuit includes: a common-mode voltage suppression circuit and a residual common-mode voltage elimination circuit, wherein the first end of the common-mode voltage suppression circuit is connected to the converter system, the second end and the third end are respectively connected to the two DC buses on the DC side of the converter system, the fourth end and the fifth end constitute the output end of the common-mode voltage elimination circuit, and the sixth end is coupled to the third end of the residual common-mode voltage elimination circuit; the first end and the second end of the residual common-mode voltage elimination circuit are respectively connected to the fourth end and the fifth end of the common-mode voltage suppression circuit, and the fourth end is grounded.

[0009] Optionally, the common-mode voltage suppression circuit includes: a first winding of a common-mode inductor, a second winding of a common-mode inductor, a first capacitor, a second capacitor and a third capacitor, wherein the first end of the first winding and the first end of the second winding are respectively connected to the two DC buses on the DC side of the converter system, and the second end of the first winding and the second end of the second winding constitute the output end of the common-mode voltage suppression circuit; the first end of the first capacitor and the second end of the first winding are both connected to the first common DC bus, the first end of the second capacitor and the second end of the second winding are both connected to the second common DC bus, the midpoint between the second end of the first capacitor and the second end of the second capacitor is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the converter system.

[0010] Optionally, the residual common-mode voltage elimination circuit includes: a third winding of the common-mode inductor, a fourth capacitor and a fifth capacitor, wherein the first end of the fourth capacitor is connected to the first common DC bus, the first end of the fifth capacitor is connected to the second common DC bus, the second end of the fourth capacitor is connected to the first end of the third winding, the second end of the fifth capacitor is connected to the second end of the third winding, and the middle tap of the third winding is grounded.

[0011] Optionally, the power conversion system includes: a filter circuit, a converter and a capacitor support circuit, wherein the first end, the second end and the third end of the filter circuit are correspondingly connected to the three-phase AC line of the converter, the fourth end is connected to the first end of the common-mode voltage suppression circuit, and the fifth end, the sixth end and the seventh end are connected to the output end of the AC system; the capacitor support circuit is connected between the two DC busbars on the DC side of the converter; the two DC busbars on the DC side of the converter are respectively connected to the first end of the first winding and the first end of the second winding.

[0012] Optionally, the filtering circuit includes: an LC filtering circuit or an LCL filtering circuit, wherein the LC filter and the LCL filtering circuit are both composed of multiple inductors and multiple capacitors, and the capacitors are star-connected; the other end of the third capacitor is connected to the neutral point of each capacitor connected in star.

[0013] Optionally, the converter is a two-level AC / DC converter or a three-level AC / DC converter or a multi-level AC / DC converter; when the converter is a two-level AC / DC converter, the two ends of the capacitor support circuit are correspondingly connected to the two DC bus bars on the DC side of the converter; when the converter is a three-level AC / DC converter, the capacitor support circuit is composed of a plurality of capacitors connected in series, and the two ends of the series connection circuit are correspondingly connected to the two DC bus bars on the DC side of the converter, and the connection point of every two capacitors is connected to each bridge arm of the converter; when the converter is a multi-level AC / DC converter, the capacitor support circuit is composed of a plurality of capacitors connected in series, and the two ends of the series connection circuit are correspondingly connected to the two DC bus bars on the DC side of the converter, and the connection point of every two capacitors is connected to each bridge arm of the converter.

[0014] Optionally, when the AC system is a low-voltage AC system, the non-isolated AC / DC power supply system further includes: a power electronic transformer and a low-voltage DC interface circuit, wherein the first end and the second end of the power electronic transformer are respectively connected to the output end of the common-mode voltage elimination circuit, the low-voltage DC interface circuit is connected between the first end and the second end of the power electronic transformer, and the third end and the fourth end of the power electronic transformer are respectively connected to the high-voltage AC system and the high-voltage DC system.

[0015] The technical solution of the present invention has the following advantages:

[0016] The non-isolated AC / DC power supply system provided by the present invention includes: a converter system, an AC system, a common-mode voltage elimination circuit, a grounding device, and a DC system, wherein the three-phase AC lines of the AC system are respectively connected to the three-phase AC lines of the converter system and to the first, second, and third ends of the grounding device; the fourth end of the grounding device is connected to the neutral line of the AC system and is grounded; the converter system is also connected to the first end of the common-mode voltage elimination circuit; the DC side of the converter system is correspondingly connected to the second and third ends of the common-mode voltage elimination circuit through two DC buses, and the output end of the common-mode voltage elimination circuit is connected to the DC system through two common DC buses; the common-mode voltage elimination circuit is used to suppress the common-mode voltage between the AC and DC sides of the converter system, and convert this common-mode voltage into a corresponding proportion of reverse induced voltage, and connect it in series to the two common DC bus-to-ground loops to offset the common-mode voltage remaining after suppression. By setting the common-mode voltage elimination circuit and cooperating with the converter system, the common-mode voltage between the AC and DC sides and the remaining common-mode voltage on the DC side to the ground are eliminated, thereby eliminating the common-mode voltage, improving the power supply voltage quality, and further improving the power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a composition diagram of a specific example of a non-isolated AC / DC power supply system according to an embodiment of the present invention;

[0019] Figure 2 is a composition diagram of another specific example of a non-isolated AC / DC power supply system according to an embodiment of the present invention;

[0020] Figure 3 is a composition diagram of another specific example of a non-isolated AC / DC power supply system according to an embodiment of the present invention;

[0021] Figure 4 is a composition diagram of another specific example of a non-isolated AC / DC power supply system according to an embodiment of the present invention;

[0022] Figure 5(a) to Figure 5(d) Each of them is a composition diagram of a specific example of a current conversion system provided by an embodiment of the present invention;

[0023] Figure 6(a) to Figure 6(b) Each of them is a composition diagram of another specific example of the power conversion system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components; wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The embodiment of the present invention provides a non-isolated AC / DC power supply system, which is applied to situations where common mode voltage needs to be eliminated, such as Figure 1As shown, the above-mentioned non-isolated AC / DC power supply system includes: a converter system 1, an AC system 2, a common-mode voltage elimination circuit 3, a grounding device 4 and a DC system 5, wherein the three-phase AC line (phase A, phase B, phase C) of the converter system 1 is respectively connected to the three-phase AC line (phase A, phase B, phase C) of the AC system 2, and is connected to the first end, the second end, and the third end of the grounding device 4, and the fourth end of the grounding device 4 is connected to the neutral line (N line) of the AC system 2 and is grounded; the converter system 1 is also connected to the first end of the common-mode voltage elimination circuit 3; the converter system 1 The DC side of the converter is connected to the second and third terminals of the common-mode voltage elimination circuit 3 via two DC buses (DC bus #1 and DC bus #2), and the output terminal of the common-mode voltage elimination circuit 3 is connected to the DC system via two common DC buses (common DC bus #1 and common DC bus #2). The common-mode voltage elimination circuit 3 is used to suppress the common-mode voltage between the AC and DC sides of the converter system, convert this common-mode voltage into a corresponding proportional reverse induced voltage, and connect it in series to the ground loop of the two common DC buses to offset the common-mode voltage remaining after suppression.

[0029] In a specific embodiment, in a non-isolated AC / DC power supply system, the AC voltage on the low-voltage AC side is converted to a DC voltage by a converter system 1 and then supplied to the DC load. In this embodiment of the present invention, the converter system 1 employs an AC / DC converter (AC / DC). Since the power supply system utilizes a large number of converter devices, excessive common-mode voltage may be generated on its AC / DC busbars due to the converter's use of PWM (pulse width modulation) technology, damaging the AC / DC loads and thus affecting the normal operation of the non-isolated AC / DC power supply system. To address this issue, this embodiment of the present invention provides a common-mode voltage elimination circuit 3, which is used in conjunction with the converter system 1 to eliminate the common-mode voltage between the AC and DC sides of the converter system 1 and the ground.

[0030] Specifically, if Figure 2 As shown, the common-mode voltage elimination circuit 3 includes: a common-mode voltage suppression circuit 31 and a residual common-mode voltage elimination circuit 32, wherein the first end of the common-mode voltage suppression circuit 31 is connected to the converter system 1, the second end and the third end are respectively connected to the two DC buses (DC bus #1 and DC bus #2) on the DC side of the converter system 1, the fourth end and the fifth end constitute the output end of the common-mode voltage elimination circuit 3, and the sixth end is coupled to the third end of the residual common-mode voltage elimination circuit 32; the first end and the second end of the residual common-mode voltage elimination circuit 32 are respectively connected to the fourth end and the fifth end of the common-mode voltage suppression circuit 31, and the fourth end is grounded.

[0031] Furthermore, if Figure 3As shown, the common-mode voltage suppression circuit 31 includes: a first winding L1 of a common-mode inductor, a second winding L2 of a common-mode inductor, a first capacitor C1, a second capacitor C2, and a third capacitor C3, wherein the first end of the first winding L1 and the first end of the second winding L2 are respectively connected to the two DC buses on the DC side of the converter system 1, and the second end of the first winding L1 and the second end of the second winding L2 constitute the output end of the common-mode voltage suppression circuit 31; the first end of the first capacitor C1 and the second end of the first winding L1 are both connected to the first common DC bus (common DC bus #1), the first end of the second capacitor C2 and the second end of the second winding L2 are both connected to the second common DC bus (common DC bus #2), and the midpoint O between the second end of the first capacitor C1 and the second end of the second capacitor C2 is connected. y It is connected to one end of the third capacitor C3 , and the other end of the third capacitor C3 is connected to the converter system 1 .

[0032] Furthermore, the residual common-mode voltage elimination circuit 32 includes: a third winding L3 of the common-mode inductor, a fourth capacitor C4, and a fifth capacitor C5, wherein a first end of the fourth capacitor C4 is connected to the first common DC bus (common DC bus #1), a first end of the fifth capacitor C5 is connected to the second common DC bus (common DC bus #2), a second end of the fourth capacitor C4 is connected to the first end of the third winding L3, a second end of the fifth capacitor C5 is connected to the second end of the third winding L3, and a middle tap O of the third winding L3 is connected. n Ground.

[0033] In the embodiment of the present invention, by connecting the common-mode voltage suppression circuit 31 to the converter system 1, a low-impedance loop is established for the common-mode voltage on the AC and DC sides. The common-mode inductor in the common-mode voltage suppression circuit 31 and the reactor in the converter system 1 consume most of the common-mode voltage on the AC and DC sides, thereby achieving attenuation suppression of the common-mode voltage. In addition, the ground common-mode voltage adjustment capacitors C1 and C2 installed on the DC bus are connected in series with the two ends of the third winding L3 of the common-mode inductor, and the center tap O of the third winding L3 is connected to the ground common-mode voltage adjustment capacitor C1 and C2 installed on the DC bus. n Then connected to the ground line, it forms a residual common mode voltage elimination circuit, where L com The L3 winding injects the induced reverse common-mode voltage between the DC bus and the ground line, eliminating the remaining common-mode voltage after suppression. The coordination of common-mode voltage suppression circuit 31, residual common-mode voltage elimination circuit 32, and converter system 1 utilizes common-mode voltage suppression circuit 31 and the reactors in converter system 1 to consume most of the common-mode voltage on the AC and DC sides. Residual common-mode voltage elimination circuit 32 then eliminates the remaining common-mode voltage on the AC and DC sides, thereby eliminating the common-mode voltage and improving the quality and reliability of the power supply voltage.

[0034] The non-isolated AC / DC power supply system provided by the present invention includes: a converter system, an AC system, a common-mode voltage elimination circuit, a grounding device, and a DC system, wherein the three-phase AC lines of the AC system are respectively connected to the three-phase AC lines of the converter system and to the first, second, and third ends of the grounding device; the fourth end of the grounding device is connected to the neutral line of the AC system and is grounded; the converter system is also connected to the first end of the common-mode voltage elimination circuit; the DC side of the converter system is correspondingly connected to the second and third ends of the common-mode voltage elimination circuit through two DC buses, and the output end of the common-mode voltage elimination circuit is connected to the DC system through two common DC buses; the common-mode voltage elimination circuit is used to suppress the common-mode voltage between the AC and DC sides of the converter system, and convert this common-mode voltage into a corresponding proportion of reverse induced voltage, and connect it in series to the two common DC bus-to-ground loops to offset the common-mode voltage remaining after suppression. By setting the common-mode voltage elimination circuit and cooperating with the converter system, the common-mode voltage between the AC and DC sides and the remaining common-mode voltage on the DC side to the ground are eliminated, thereby eliminating the common-mode voltage, improving the power supply voltage quality, and further improving the power supply reliability.

[0035] In one embodiment, if Figure 4 As shown, the non-isolated AC / DC power supply system further includes: a grounding device 4, the first end, the second end, and the third end of the grounding device 4 are respectively connected to the three-phase AC line of the AC system, and the fourth end is connected to the neutral line of the AC system and then grounded.

[0036] In a specific embodiment, the converter system 1 is a three-phase three-wire wiring method, while the power supply wiring method required by the AC load is mostly a three-phase four-wire system or a three-phase five-wire system, and the grounding method of the DC load is mostly IT (I = the power supply end is not grounded or grounded through a high impedance; T = the exposed conductive part of the electrical device is directly grounded, and this grounding point is electrically independent of the grounding point of the power supply end). In this case, if the wiring method of the non-isolated AC / DC power supply system is not processed, it will result in the inability to supply power to the AC / DC loads in the form of a common ground on the AC / DC sides. Therefore, if Figure 4 As shown, in an embodiment of the present invention, a three-phase four-wire circuit is formed by connecting the grounding device 4 to the three-phase AC line and the neutral line of the AC system 2; further, the neutral line of the AC system 2 is grounded to form a three-phase five-wire circuit. The above circuit connection relationship meets the wiring method requirements of the AC load (three-phase four-wire or three-phase five-wire), and provides a common grounding point for AC and DC power supply, thereby solving the common ground problem of non-isolated AC and DC power supply systems. In addition, in an embodiment of the present invention, the grounding device 4 is composed of a grounding transformer and a phase voltage filter capacitor connected in parallel, or the grounding device 4 is a filtering device. Specifically, a group of phase voltage filter capacitors can also be connected in parallel to the three-phase input and output ends of the grounding transformer to filter out the induced voltage caused by the grounding transformer input and output coupling leakage inductance.

[0037] In one embodiment, if Figure 4 As shown, the DC system 5 includes: multiple DC / DC devices, the input end of each DC / DC device is respectively connected to two common DC buses (common DC bus #1 and common DC bus #2), and the output end of each DC / DC device is connected to an external load to provide a corresponding level of voltage to the connected external load.

[0038] In one specific embodiment, the input of each DC / DC device is connected to a common DC bus, and the output is connected to an external load, thereby powering loads of different voltage levels. In this embodiment of the present invention, the common DC bus can also be connected to other devices, such as energy storage devices and power electronic transformers.

[0039] In one embodiment, if Figure 4 As shown, the power conversion system 1 includes: a filter circuit 11, a converter 12 and a capacitor support circuit 13, wherein the first end, the second end and the third end of the filter circuit 11 are correspondingly connected to the three-phase AC line of the converter 12, the fourth end is connected to the first end of the common-mode voltage suppression circuit 31, and the fifth end, the sixth end and the seventh end are connected to the output end of the AC system; the capacitor support circuit 13 is connected between the two DC buses on the DC side of the converter 12, and is used to parallel filter the DC side voltage of the converter 12; the two DC buses on the DC side of the converter 12 are respectively connected to the first end of the first winding L1 and the first end of the second winding L2, and are used for energy flow between each DC / DC device and the AC system 2, or energy flow between the energy storage device and the AC system 2.

[0040] In one specific embodiment, the filter circuit includes an LC filter circuit or an LCL filter circuit, wherein each of the LC filter circuit and the LCL filter circuit is composed of multiple inductors and multiple capacitors, and the capacitors are connected in a star configuration; the other end of the third capacitor C3 is connected to the neutral point of the star-connected capacitors. In the embodiments of the present invention, the LC filter circuit and the LCL filter circuit are used as examples for description, but are not limited thereto.

[0041] In one embodiment, the converter 12 is a two-level AC / DC converter, a three-level AC / DC converter, or a multi-level AC / DC converter. When the converter 12 is a two-level AC / DC converter, the capacitor support circuit 13 includes at least one capacitor, such as Figure 5(a) to Figure 5(b) As shown, the capacitor support circuit 13 includes two capacitors as an example for description. Specifically, the two ends of the capacitor support circuit 13 are connected to the two DC buses on the DC side of the converter 12. Figure 5(c) to Figure 5(d) As shown, the capacitor support circuit 13 includes a capacitor as an example for description. Specifically, the two ends of the capacitor support circuit 13 are correspondingly connected to the two DC buses on the DC side of the converter 12.

[0042] When the converter 12 is a three-level AC / DC converter, the capacitor support circuit 13 includes a plurality of capacitors, such as Figure 6(a) to Figure 6(b) As shown, the capacitor support circuit 13 includes two capacitors as an example. Specifically, the two ends of the capacitor support circuit 13 are correspondingly connected to the two DC buses on the DC side of the converter 12, and the connection point of the two capacitors is connected to each bridge arm of the converter 12.

[0043] It should be noted that the converter 12 in the embodiment of the present invention is not limited to a two-level or three-level AC / DC converter, but may also be other converters capable of performing AC / DC conversion. When the converter is a multi-level AC / DC converter, the capacitive support circuit is composed of multiple capacitors connected in series, with the two ends of the series-connected circuit correspondingly connected to the two DC busbars on the DC side of the converter, and the connection point between each two capacitors is connected to each bridge arm of the converter. In the embodiment of the present invention, a multi-level AC / DC converter is a converter having more than three levels.

[0044] In one embodiment, if Figure 4 As shown, when the AC system 2 is a low-voltage AC system, the non-isolated AC / DC power supply system further includes: a power electronic transformer 6 and a low-voltage DC interface circuit 7, wherein the first end and the second end of the power electronic transformer 6 are respectively connected to the output end of the common-mode voltage elimination circuit 3, the low-voltage DC interface circuit 7 is connected between the first end and the second end of the power electronic transformer, and the third end and the fourth end of the power electronic transformer 6 are respectively connected to the high-voltage AC system and the high-voltage DC system.

[0045] It should be noted that Figure 4 The low-voltage DC interface circuit 7 is only used as an example, but is not intended to be limiting.

[0046] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A non-isolated AC / DC power supply system, characterized in that: include: AC system, grounding device, current conversion system, common mode voltage elimination circuit and DC system, among which, The three-phase AC lines of the AC system are respectively connected to the three-phase AC lines of the converter system and to the first end, the second end, and the third end of the grounding device; The fourth end of the grounding device is connected to the neutral line of the AC system and is grounded; The current conversion system is also connected to the first end of the common mode voltage elimination circuit; The DC side of the converter system is connected to the second end and the third end of the common-mode voltage elimination circuit via two DC buses, and the output end of the common-mode voltage elimination circuit is connected to the DC system via two common DC buses. The common-mode voltage elimination circuit is used to suppress the common-mode voltage between the AC and DC sides of the power conversion system, and convert this common-mode voltage into a corresponding proportion of reverse induced voltage, and then connect it in series to the two DC bus-to-ground loops to offset the remaining common-mode voltage after suppression; The common mode voltage elimination circuit includes: a common mode voltage suppression circuit and a residual common mode voltage elimination circuit, wherein: The common-mode voltage suppression circuit includes: a first winding of a common-mode inductor, a second winding of a common-mode inductor, a first capacitor, a second capacitor, and a third capacitor, wherein: The first end of the first winding and the first end of the second winding are respectively connected to the two DC buses on the DC side of the converter system, and the second end of the first winding and the second end of the second winding constitute the output end of the common-mode voltage suppression circuit; The first end of the first capacitor and the second end of the first winding are both connected to the first common DC bus, the first end of the second capacitor and the second end of the second winding are both connected to the second common DC bus, the midpoint between the second end of the first capacitor and the second end of the second capacitor is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the power conversion system; The residual common mode voltage elimination circuit includes: a third winding of the common mode inductor, a fourth capacitor and a fifth capacitor, wherein: a first end of the fourth capacitor is connected to the DC bus, a first end of the fifth capacitor is connected to the DC bus, a second end of the fourth capacitor is connected to the first end of the third winding, a second end of the fifth capacitor is connected to the second end of the third winding, and a center tap of the third winding is grounded; The DC system includes: multiple DC / DC devices, the input end of each DC / DC device is respectively connected to two common DC buses, and the output end of each DC / DC device is connected to an external load to provide a corresponding level of voltage for the connected external load.

2. The non-isolated AC / DC power supply system according to claim 1, characterized in that: The common mode voltage elimination circuit includes: a common mode voltage suppression circuit and a residual common mode voltage elimination circuit, wherein: The first end of the common-mode voltage suppression circuit is connected to the converter system, the second end and the third end are respectively connected to the two DC buses on the DC side of the converter system, the fourth end and the fifth end constitute the output end of the common-mode voltage elimination circuit, and the sixth end is coupled to the third end of the residual common-mode voltage elimination circuit; The first terminal and the second terminal of the residual common-mode voltage elimination circuit are respectively connected to the fourth terminal and the fifth terminal of the common-mode voltage suppression circuit, and the fourth terminal is grounded.

3. The non-isolated AC / DC power supply system according to claim 1, characterized in that: The current conversion system includes: a filter circuit, a converter and a capacitor support circuit, wherein: The first, second, and third ends of the filter circuit are connected to the three-phase AC line of the converter, respectively; the fourth end is connected to the first end of the common-mode voltage suppression circuit; and the fifth, sixth, and seventh ends are connected to the output end of the AC system; A capacitor support circuit is connected between two DC buses on the DC side of the converter; The two DC buses on the DC side of the converter are connected to the first end of the first winding and the first end of the second winding respectively.

4. The non-isolated AC / DC power supply system according to claim 3, characterized in that: The filtering circuit includes: an LC filtering circuit or an LCL filtering circuit, wherein: The LC filter circuit and the LCL filter circuit are both composed of multiple inductors and multiple capacitors, and the capacitors are connected in a star shape; The other end of the third capacitor is connected to the neutral point of each capacitor connected in a star configuration.

5. The non-isolated AC / DC power supply system according to claim 3, characterized in that: The converter is a two-level AC / DC converter, a three-level AC / DC converter, or a multi-level AC / DC converter; When the converter is a two-level AC / DC converter, the two ends of the capacitor support circuit are connected to the two DC buses on the DC side of the converter respectively; When the converter is a three-level AC / DC converter, the capacitive support circuit is composed of a plurality of capacitors connected in series, and the two ends of the series connection circuit are connected to the two DC buses on the DC side of the converter respectively, and the connection point of each two capacitors is connected to each bridge arm of the converter; When the converter is a multi-level AC / DC converter, the capacitor support circuit is composed of multiple capacitors connected in series, and the two ends of the series connection circuit are correspondingly connected to the two DC bus bars on the DC side of the converter, and the connection point of every two capacitors is connected to each bridge arm of the converter.

6. The non-isolated AC / DC power supply system according to claim 1, characterized in that: When the AC system is a low-voltage AC system, the non-isolated AC / DC power supply system further includes: a power electronic transformer and a low-voltage DC interface circuit, wherein: The first end and the second end of the power electronic transformer are respectively connected to the output end of the common-mode voltage elimination circuit, the low-voltage DC interface circuit is connected between the first end and the second end of the power electronic transformer, and the third end and the fourth end of the power electronic transformer are respectively connected to the high-voltage AC system and the high-voltage DC system.

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