Ac / dc converter stage for a converter system with input series structure with improved common mode performance

Abstract

The invention relates to an AC / DC converter stage (1) for a converter system (3) having an input series structure. The AC / DC converter stage (1) comprises two input terminals (IN1, IN2) for inputting an AC input voltage (Vin) to the AC / DC converter stage (1), at least one first branch (CB1) having at least two switches (S1, S2) electrically connected in series at a first connection point (N1), wherein a first input terminal (IN1) of the two input terminals (IN1, IN2) is electrically connected to the first connection point (N1) of the first branch (CB1). The AC / DC converter stage (1) further comprises at least one first energy storage (C1) for providing a DC output voltage, the first energy storage (C1) being electrically connected in parallel to the first branch (CB1), at least one controllable bidirectional switch (BS0) electrically connected between the two input terminals (IN1, IN2). The AC / DC converter stage has improved common mode performance.

Description

Technical Field

[0001] This invention relates to an AC / DC converter stage for a converter system including an input series configuration, wherein the AC / DC converter stage has improved common-mode performance. The invention also relates to a converter system having an input series configuration including at least one such AC / DC converter stage. Specifically, the converter system includes at least two converter units electrically connected in series at the input of the converter system, wherein at least one of the at least two converter units includes such an AC / DC converter stage as a first converter stage. The AC / DC converter stage may include a half-bridge configuration or a full-bridge configuration. Background Technology

[0002] For example, in short-path converter systems, power conversion systems are used to convert medium-voltage AC (e.g., AC voltage above 1000 volts, AC frequency of 50 Hz or 60 Hz (depending on the region)) to lower voltages, particularly lower DC voltages, to power multiple electrical loads. Examples of such electrical loads include data center applications and electric vehicle (EV) charging stations. In the case of solar photovoltaics (PV), DC power generated through PV panels is converted to medium-voltage AC using such converter systems.

[0003] To convert an AC input voltage to a DC output voltage, especially a lower DC voltage, a converter system with an input series configuration can be used. This converter system includes at least two converter units connected in series at the input of the system. Such converter units may include an AC / DC converter stage as a first converter stage, and may also include an electrically isolated DC / DC converter stage as a second converter stage, wherein the isolated DC / DC converter provides electrical isolation between the AC input voltage and the DC output voltage. Summary of the Invention

[0004] The embodiments of the present invention are also based on the following considerations made by the inventors:

[0005] In a converter system with a series input configuration, each of the converter units connected in series at the input of the converter system can be encapsulated in a housing, which is maintained at ground potential for safety. High power density requirements necessitate that these encapsulated converter units be arranged very tightly within the converter system. Specifically, for insulation purposes, a solid insulating material is provided between the encapsulated converter units and thus between the high potential of the converter units and the ground potential of the housing. Since the housing can be made of metal, providing this solid insulating material can create parasitic capacitances between the components of the converter units, particularly between the AC / DC converter stage and the electrically isolated DC / DC converter stage, and between the metal housing maintained at ground potential.

[0006] When an AC input voltage is supplied to the converter system with a series input structure, the converter system generates high common-mode voltages on both the input and grid sides. These high common-mode voltages generate high common-mode currents and leakage currents through the parasitic capacitances. These common-mode currents can cause several problems in the converter system (especially the AC / DC converter stage), such as noise-related problems, electromagnetic compatibility (EMC) (especially electromagnetic interference (EMI)) related problems, and additional power losses due to the common-mode currents. In the case where the AC / DC converter stage includes IGBTs, gate driver misfires may occur due to noise, ground potential shift, and EMI / EMC caused by the common-mode currents.

[0007] Combination Figure 1 (a) and (b) exemplarily describe the above-mentioned issue regarding the common-mode voltage of the AC / DC converter stage. Figure 1 (a) and (b) show examples of AC / DC converter stages that include a full-bridge structure in different switching states. Figure 1The AC / DC converter stage shown includes four switches in the form of insulated-gate bipolar transistors (IGBTs) (Q01, Q02, Q03, Q04), which are electrically connected to form a full-bridge structure. In other words, two IGBTs (Q01, Q02) are connected in series at a first connection point N01, where the first input terminal A of the two input terminals (A, B) is connected to the first connection point N01 via an inductor L1. Two IGBTs (Q03, Q04) are connected in series at a second connection point N02, where the second input terminal B of the two input terminals (A, B) is connected to the second connection point N02 via an inductor L1. The series connection of the two IGBTs (Q03, Q04) is connected in parallel to the series connection of the two IGBTs (Q01, Q02). Furthermore, two capacitors C01, connected in series at the midpoint M, are connected in parallel to the two series connections of the two IGBTs.

[0008] A diode is connected in parallel to each IGBT, wherein the anode of the diode is connected to the emitter terminal of the corresponding IGBT, and the cathode of the diode is connected to the collector terminal of the corresponding IGBT. The four IGBTs (Q01, Q02, Q03, Q04) can be controlled by a control unit to convert the AC input voltage at the two input terminals (A, B) into two voltages V across the two capacitors C01. C The resulting DC output voltage. In other words, the four IGBTs (Q01, Q02, Q03, Q04) are used by the control unit to enable AC-to-DC conversion.

[0009] Figure 1 (a) shows Figure 1 The switching states of the four IGBTs (Q01, Q02, Q03, Q04) in the AC / DC converter stage are shown. In this switching state, IGBT Q02 is in the ON state (…). Figure 1 (a) shows IGBT Q02 drawn with a solid line, and IGBT Q04 is turned on to the conducting state. Figure 1 (a) shows IGBT Q04 drawn with a dashed line, while IGBT Q01 and IGBT Q03 are in a non-conducting state. Figure 1 (a) shows IGBT Q01 and IGBT Q03 drawn with dotted lines. Therefore, the current I... A Current flows from input terminal A to input terminal B via the diode of IGBT Q04 and IGBT Q02. No current flows through the two capacitors C01. The common-mode voltage (V) of the AC / DC converter stage...CM It can be calculated using the following formula:

[0010]

[0011] Voltage V AM Corresponding to the voltage drop between the first connection point N01 and the midpoint M, the voltage V BM This corresponds to the pressure drop between the second connection point N02 and the midpoint M.

[0012] Therefore, in Figure 1 In the switching state shown in (a), the common-mode voltage V CM This corresponds to a negative voltage (-V) across a capacitor C01. C ), because the voltage V AM and V BM Each voltage in the equation corresponds to a negative voltage (-V) across capacitor C01. C Therefore, the common-mode voltage V CM It is a non-zero value and generates a common-mode current, which is the leakage current through the parasitic capacitance to the ground potential.

[0013] Figure 1 (b) shows Figure 1 This illustrates another switching state for the four IGBTs (Q01, Q02, Q03, Q04) in the AC / DC converter stage. In this switching state, IGBT Q01 is in the ON state (…). Figure 1 (b) shows IGBT Q01 drawn with a solid line, and IGBT Q03 is turned on to the conducting state. Figure 1 (b) shows IGBT Q03 drawn with a dashed line, while IGBT Q02 and IGBT Q04 are in a non-conducting state. Figure 1 (b) shows IGBT Q02 and IGBT Q04 drawn with dotted lines. Therefore, the current I... A Current flows from input terminal B to input terminal A via the diodes of IGBT Q03 and IGBT Q01. No current flows through the two capacitors C01.

[0014] Therefore, in Figure 1 (b) In the switching state shown, the common-mode voltage V CM Corresponding to a positive voltage (+V) across a capacitor C01 C ), because the voltage V AM and V BM Each voltage in the equation corresponds to a positive voltage (+V) across capacitor C01. C Therefore, the common-mode voltage V CMIt is a non-zero value and generates a common-mode current, which is the leakage current through the parasitic capacitance to the ground potential.

[0015] As mentioned above, in Figure 1 In the switching states shown in (a) and (b), no current flows through the two capacitors C01. The current I... A Current flows from one input terminal (A or B) to the corresponding other input terminal (B or A), without flowing through the capacitor C01. In this switching state, no current flows through the storage device (capacitor C01) used to provide the DC output voltage of the AC / DC converter stage; this switching state can be called the "zero state". Figure 1 In the AC / DC converter stage shown, Figure 1 Each of the switching states (zero state) shown in (a) and (b) generates a non-zero common-mode voltage V. CM (i.e., -V) C Or +V C Therefore, in these switching states, the common-mode voltage V CM This generates a current (i.e., common-mode current) through the parasitic capacitance to the ground potential. This causes the aforementioned disadvantages and problems in the zero state of the AC / DC converter stage.

[0016] exist Figure 1 The AC / DC converter stage shown is used for other switching states to perform AC-to-DC conversion. Figure 1 In (a) and (b) (not shown), current flows between the two input terminals (A, B) via the two capacitors C01. Therefore, the voltage V AM and V BM Opposite (i.e., V) AM =+V C V BM =-V C Or, V AM =-V C V BM =+V C ), and therefore the common-mode voltage V CM It is zero.

[0017] In view of the above-mentioned problems and disadvantages, embodiments of the present invention aim to improve the common-mode performance of converter systems with series input structures, particularly the common-mode performance of AC / DC converter stages for converter systems with series input structures. An object of the present invention is to provide an AC / DC converter stage with improved common-mode performance for converter systems with series input structures. Another object of the present invention is to provide a converter system with an input series structure and improved common-mode performance.

[0018] The objective is achieved by the embodiments of the invention described in the appended independent claims. Advantageous implementations of the embodiments of the invention are further defined in the dependent claims.

[0019] A first aspect of the present invention provides an AC / DC converter stage for a converter system having an input series structure, the AC / DC converter stage comprising:

[0020] - Two input terminals for inputting AC input voltage to the AC / DC converter stage;

[0021] - At least one first branch has at least two switches, the at least two switches being electrically connected in series at a first connection point, wherein the first input terminal of the two input terminals is electrically connected to the first connection point of the first branch;

[0022] - At least one first storage device for providing DC output voltage, the first storage device being connected in parallel to the first branch;

[0023] - At least one controllable bidirectional switch is electrically connected between the two input terminals.

[0024] The AC / DC converter stage according to the first aspect causes current to flow between the two input terminals, with no current flowing through the at least one first storage device used to provide the DC output voltage, and no current flowing through the at least one branch of the AC / DC converter stage. Since no current flows through the at least one branch when no current flows through the at least one first storage device used to provide the DC output voltage, the common-mode voltage is zero. Therefore, the AC / DC converter stage according to the first aspect can achieve a zero-state, in which the common-mode voltage is zero. Thus, the AC / DC converter stage according to the first aspect overcomes the aforementioned disadvantages and problems and has improved common-mode performance. The AC / DC converter stage is advantageous because common-mode performance can be improved in a cost-effective manner, namely by providing the at least one controllable bidirectional switch.

[0025] The at least one first energy storage device may include or correspond to at least one output capacitor. The term "energy storage device" may be used as a synonym for the term "energy storage device".

[0026] Specifically, the at least one controllable bidirectional switch is configured to be controlled by a control unit. In this invention, examples of the control unit include a processor, microprocessor, controller, microcontroller, application-specific integrated circuit (ASIC), or any combination thereof.

[0027] Specifically, the AC / DC converter stage includes at least a half-bridge structure having at least one first branch.

[0028] The term "node" can be used as a synonym for the term "connection point." Therefore, the first connection point can also be called the first node. The term "electrical connection" can also be referred to simply by the term "connection."

[0029] In this invention, the terms "current flowing through an electrical component" and "current passing through an electrical component" can be understood as synonyms. In other words, for example, the current flowing through the at least one first storage device corresponds to the current passing through the at least one first storage device. Correspondingly, in this invention, the terms "current flowing through a circuit portion of the AC / DC converter stage" and "current passing through a circuit portion of the AC / DC converter stage" can be understood as synonyms. In other words, for example, the current flowing through the at least one first branch corresponds to the current passing through the at least one first branch.

[0030] In one implementation of the first aspect, the at least one controllable bidirectional switch is used to achieve the zero state of the AC / DC converter stage by providing a low-impedance current path between the two input terminals in its on state.

[0031] This allows for a zero-state operation of the AC / DC converter stage, where no current flows through at least one branch (the first branch) of the AC / DC converter stage, and thus the common-mode voltage is zero. Therefore, the AC / DC converter stage exhibits improved common-mode performance. This AC / DC converter stage is advantageous because its common-mode performance can be improved in a cost-effective manner by providing at least one controllable bidirectional switch.

[0032] As described above, the zero state of the AC / DC converter stage corresponds to the state in which current now flows through the at least one first storage device used to provide the DC output voltage of the AC / DC converter stage. In other words, in the zero state of the AC / DC converter stage, when there is an input voltage at the two input terminals, no current flows through the at least one first storage device between the two input terminals.

[0033] In one implementation of the first aspect, the AC / DC converter stage is a bipolar boost converter, including a second energy storage device; one of the two input terminals is electrically connected to the at least one controllable bidirectional switch via the second energy storage device.

[0034] Therefore, the AC / DC converter stage with the second energy storage device is used for bipolar boost operation.

[0035] Specifically, the second energy storage device includes or corresponds to at least one inductor or choke.

[0036] In one implementation of the first aspect, the at least one controllable bidirectional switch is used to achieve the zero state of the AC / DC converter stage by providing a current path between the two input terminals via the second energy storage device in its on state.

[0037] This allows for a zero-state operation of the AC / DC converter stage corresponding to the bipolar boost converter, with no current flowing through the at least one branch (first branch) of the AC / DC converter stage, and thus achieving a zero-state operation where the common-mode voltage is zero. Therefore, the AC / DC converter stage corresponding to the bipolar boost converter exhibits improved common-mode performance. This AC / DC converter stage is advantageous because common-mode performance can be improved in a cost-effective manner, namely by providing the at least one controllable bidirectional switch.

[0038] Specifically, the controllable bidirectional switch is used to: switch to the ON state to achieve the zero state, thereby increasing the current of the second energy storage device. Therefore, in the zero state of the AC / DC converter stage, electrical energy is stored in the second energy storage device, thereby enabling the boost operation of the AC / DC converter stage.

[0039] In one implementation of the first aspect, the first input terminal of the two input terminals is electrically connected to the first connection point of the first branch via the second energy storage device.

[0040] As described above, the second energy storage device is capable of performing the boost operation of the AC / DC converter stage.

[0041] In one implementation of the first aspect, the AC / DC converter stage further includes: a second branch having at least two switches connected in series at a second connection point, wherein the second branch is connected in parallel to the first branch and the first energy storage device; wherein the second input terminal of the two input terminals is connected to the second connection point of the second branch.

[0042] Therefore, the AC / DC converter stage may include at least a full-bridge structure having the first branch and the second branch.

[0043] Specifically, the second input terminal of the two input terminals is electrically connected to the second connection point of the second branch via the second energy storage device. The second energy storage device enables the boost operation of the AC / DC converter stage.

[0044] In one implementation of the first aspect, the first energy storage device includes or corresponds to at least two first energy storage elements, which are connected in series at a third connection point.

[0045] This can provide different DC output voltages, namely the output voltage on each of the at least two first energy storage elements and the output voltage on the series connection of the energy storage elements.

[0046] Specifically, the at least two first energy storage elements correspond to at least two output capacitors.

[0047] In one implementation of the first aspect, where the AC / DC converter stage includes only the first branch, the second input terminal of the two input terminals is electrically connected to the third connection point.

[0048] Specifically, when the AC / DC converter stage includes only the first branch, the second input terminal of the two input terminals is electrically connected to the third connection point via the second energy storage device. The second energy storage device enables the boost operation of the AC / DC converter stage.

[0049] In one implementation of the first aspect, where the AC / DC converter stage includes only the first branch: where the first branch includes two or more switches connected in series, particularly four switches, the third connection point is electrically connected via a switch to at least one connection point between two switches in the first branch that is different from the first connection point.

[0050] Since the first branch includes two or more switches, switches with lower power requirements and therefore lower cost and smaller size can be used for the same AC input voltage, because the AC input voltage is distributed among the corresponding switches in the first branch. This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the first branch, and allows for a reduction in the size of the AC / DC converter stage.

[0051] As described above, the switch can electrically connect the third connection point (located between the energy storage elements of the at least one first energy storage device) to at least one connection point between two switches in the first branch that is different from the first connection point. This switch ensures that the voltage drop between the corresponding switches in the first branch is equal, thereby ensuring that the switches in the first branch experience equal stress.

[0052] In one implementation of the first aspect, where the AC / DC converter stage includes a first branch and a second branch: If the first branch includes two or more switches connected in series, particularly four switches, the third connection point is electrically connected via a switch to at least one connection point between two switches in the first branch that is different from the first connection point. Furthermore, if the second branch includes two or more switches connected in series, particularly four switches, the third connection point is electrically connected via a switch to at least one connection point between two switches in the second branch that is different from the second connection point.

[0053] Since each of the first and second branches includes more than two switches, switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage, because the AC input voltage is distributed among the corresponding switches in the first and second branches. This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the first and second branches, and allows for a reduction in the size of the AC / DC converter stage.

[0054] As described above, the switch can electrically connect the third connection point (located between the energy storage elements of the at least one first energy storage device) to at least one connection point between two switches in the first branch, which is different from the first connection point. Additionally, the switch can electrically connect the third connection point (located between the energy storage elements of the at least one first energy storage device) to at least one connection point between two switches in the second branch, which is different from the second connection point. These switches ensure that the voltage drop between the corresponding switches in the first branch and the corresponding switches in the second branch is equal, such that the stress experienced by the switches in the first branch and the switches in the second branch is equal.

[0055] In one implementation of the first aspect, the switch includes at least one of the following:

[0056] - At least one uncontrollable unidirectional semiconductor switch, such as at least one diode;

[0057] - At least one controllable semiconductor switch;

[0058] - At least one insulated gate bipolar transistor (IGBT).

[0059] Examples of controllable semiconductor switches are transistors, such as field-effect transistors (FETs), metal-oxide field-effect transistors (MOSFETs), bipolar transistors, insulated-gate bipolar transistors (IGBTs), etc.

[0060] IGBTs are an example of controllable unidirectional semiconductor switches. The switches may include other types of controllable unidirectional semiconductor switches.

[0061] Specifically, when the switch includes or corresponds to an IGBT, a diode is connected in parallel to the IGBT, wherein the anode of the diode is connected to the emitter terminal of the IGBT, and the cathode of the diode is connected to the collector terminal of the IGBT.

[0062] Specifically, the switches of the one or more branches, such as the switches of at least one first branch or each of the switches of the at least one first branch and the second branch, include or correspond to the same switch type. For example, the switches of the one or more branches may include or correspond to uncontrolled unidirectional semiconductor switches (e.g., diodes) or controlled semiconductor switches (e.g., IGBTs). In this case, at least one of the switches of the one or more branches may include or correspond to different switch types. For example, the switches of the one or more branches may include or correspond to diodes, and at least one of these switches may include or correspond to IGBTs.

[0063] When the switches of one or more branches in the AC / DC converter stage include or correspond to controllable semiconductor switches, the control unit can control the switches of the one or more branches, causing the AC / DC converter stage to perform AC-to-DC conversion. In such cases, the controllable semiconductor switch may be an IGBT.

[0064] The switches in one or more branches of the AC / DC converter stage include or correspond to uncontrolled unidirectional semiconductor switches (e.g., diodes) that can perform the AC-to-DC conversion because different current paths are formed via the uncontrolled unidirectional semiconductor switches due to changes in the AC input voltage.

[0065] In both cases, when the controllable bidirectional switch is in the ON state, the control unit can control the controllable bidirectional switch to achieve the zero state of the AC / DC converter stage.

[0066] The aforementioned one or more switches can electrically connect one or more connection points between switches in branches different from the first connection point / second connection point to the third connection point, and may include or correspond to one or more uncontrolled unidirectional semiconductor switches (e.g., diodes). Alternatively, the one or more switches may include or correspond to one or more controllable semiconductor switches (e.g., IGBTs).

[0067] The one or more switches may include or correspond to the same switch type. Specifically, at least one of the one or more switches may correspond to a different switch type. Specifically, compared to the switches of the one or more branches of the AC / DC converter stage, the one or more switches may include or correspond to the same switch type or different switch types. For example, if the switches of the one or more branches include or correspond to an IGBT, the one or more switches may include or correspond to an IGBT or a diode. For example, if the switches of the one or more branches include or correspond to a diode, the one or more switches may include or correspond to an IGBT or a diode.

[0068] In one implementation of the first aspect, the at least one controllable bidirectional switch includes at least one controllable semiconductor switch, particularly at least two IGBTs.

[0069] In other words, the at least one controllable bidirectional switch may include or correspond to one or more controllable semiconductor switches. Specifically, the at least one controllable bidirectional switch may include two or more IGBTs.

[0070] In one implementation of the first aspect, the AC / DC converter stage includes two controllable bidirectional switches connected in series at a fourth connection point and used to provide a current path between the two input terminals when in the on state.

[0071] Because the AC / DC converter stage includes two controllable bidirectional switches, controllable bidirectional switches that are used for lower power and are therefore less expensive and smaller in size can be used for the same AC input voltage, as the AC input voltage is distributed between the two controllable bidirectional switches. This is advantageous because using less expensive and smaller switches reduces the cost of implementing the AC / DC converter stage, especially the two controllable bidirectional switches, and allows for a reduction in the size of the AC / DC converter stage.

[0072] Furthermore, increasing the number of controllable bidirectional switches from 1 to 2 increases the AC input voltage input to the AC / DC converter stage because the AC input voltage is distributed between the two controllable bidirectional switches. This is advantageous because, when the AC / DC converter stage is used as the first converter stage in the converter unit of the converter system, where the converter units are connected in series at the input of the converter system, fewer converter units are needed for the same AC input voltage. That is, each converter unit can handle a higher input voltage due to the two controllable bidirectional switches.

[0073] Specifically, the two controllable bidirectional switches are used to achieve the zero state of the AC / DC converter stage by providing a low-impedance current path between the two input terminals of the AC / DC converter stage when they are in the on state.

[0074] Furthermore, the control unit can control the two controllable bidirectional switches.

[0075] Specifically, the two controllable bidirectional switches are used to achieve the zero state of the AC / DC converter stage by providing a low-impedance current path between the two input terminals via the second energy storage device when they are in their on state. The second energy storage device enables the boost operation of the AC / DC converter stage.

[0076] In one implementation of the first aspect, where the AC / DC converter stage includes the first branch and the second branch, and where the first energy storage device includes at least two first energy storage elements connected in series at the third connection point: the third connection point is electrically connected to the fourth connection point.

[0077] This ensures that, in the case that the AC / DC converter stage includes two controllable bidirectional switches connected in series at the fourth connection point, the AC input voltage is evenly distributed between the two controllable bidirectional switches.

[0078] In one implementation of the first aspect, where the AC / DC converter stage includes only the first branch, each switch of the first branch includes:

[0079] - Two uncontrollable unidirectional semiconductor switches, such as two diodes, are connected in series at a fifth connection point; or

[0080] - Two controllable semiconductor switches, particularly two IGBTs, which are connected in series at a fifth connection point.

[0081] Since each switch in the first branch comprises either two uncontrolled unidirectional semiconductor switches or two controlled semiconductor switches, switches that are used for lower power and are therefore less expensive and smaller in size can be used for the same AC input voltage, as the voltage on each switch is distributed between the two semiconductor switches. This is advantageous because using less expensive and smaller switches reduces the cost of implementing the AC / DC converter stage, particularly the two switches in the first branch, and allows for a reduction in the size of the AC / DC converter stage.

[0082] In one implementation of the first aspect, where the AC / DC converter stage includes the first branch and the second branch: each switch of the first branch and the second branch includes:

[0083] - Two uncontrollable unidirectional semiconductor switches, such as two diodes, are connected in series at a fifth connection point; or

[0084] - Two controllable semiconductor switches, particularly two IGBTs, which are connected in series at a fifth connection point.

[0085] Since each switch in the first and second branches comprises either two uncontrolled unidirectional semiconductor switches or two controlled semiconductor switches, switches that are used for lower power and are therefore less expensive and smaller in size can be used for the same AC input voltage, as the voltage on each switch is distributed between the two semiconductor switches. This is advantageous because using less expensive and smaller switches reduces the cost of implementing the AC / DC converter stage, especially the switches in the first and second branches, and allows for a reduction in the size of the AC / DC converter stage.

[0086] In one implementation of the first aspect, where the first storage device includes at least two first storage device elements connected in series at the third connection point:

[0087] - Each switch includes a slow recovery diode and a fast recovery diode, which are connected in series at the fifth connection point. For each switch, a low-current diode for providing recovery charge is connected between the fifth connection point and the third connection point; or

[0088] - Each switch includes two controllable semiconductor switches connected in series at the fifth connection point, wherein for each switch, a low-current diode for ensuring equal voltage drops at the two controllable semiconductor switches is electrically connected between the fifth connection point and the third connection point.

[0089] For each switch in one or more branches of the AC / DC converter stage, using a slow recovery diode and a fast recovery diode can reduce costs because the slow recovery diode is less expensive than the fast recovery diode.

[0090] In cases where each switch comprises two IGBTs, a slow recovery diode can be connected in parallel to one of the two IGBTs, and a fast recovery diode can be connected in parallel to the other of the two IGBTs. This reduces costs because slow recovery diodes are less expensive than fast recovery diodes.

[0091] To implement the AC / DC converter stage according to the first aspect of the present invention, some or all of the implementation methods and optional features described in the first aspect above may be combined with each other.

[0092] A second aspect of the invention provides a converter system having an input series configuration. The converter system includes at least two converter units connected in series at the input of the converter system, wherein at least one of the at least two converter units includes an AC / DC converter stage according to the first aspect or any implementation thereof.

[0093] Each of the at least two converter units can provide an output voltage, particularly a DC output voltage, without needing to be electrically connected to each other at the output of the converter system. Alternatively, the at least two converter units may be electrically connected in series or in parallel at the output of the converter system. In other words, the converter system may include an input series output series (ISOS) configuration, where the at least two converter units are electrically connected in series at the output of the converter system. Alternatively, the converter system may include an input series output parallel (ISOP) configuration, where the at least two converter units are electrically connected in parallel at the output of the converter system.

[0094] The at least two converter units of the converter system can be controlled by a control unit. The control unit can be part of the converter system.

[0095] In one implementation of the second aspect, one of the at least two converter units includes an AC / DC converter stage with a second battery as described in the first aspect or any implementation thereof. Additionally, the other of the at least two converter units includes an AC / DC converter stage without the second battery as described in the first aspect or any implementation thereof.

[0096] Therefore, one of the at least two converter units may include an AC / DC converter stage as a bipolar boost converter. Specifically, at least one converter unit of the converter system may include an AC / DC converter stage, wherein the AC / DC converter stage is a bipolar boost converter.

[0097] This is advantageous because, since at least one converter unit of the converter system includes an AC / DC converter stage (wherein the AC / DC converter stage is a bipolar boost converter), the converter system is used to perform the boost operation caused by the series connection of the converter unit at the input of the converter system. This reduces the number of electronic components (especially the second battery) required for the converter system to perform the boost operation, and thus reduces costs.

[0098] In one implementation of the second aspect, each of the at least two converter units includes an AC / DC converter stage according to the first aspect or any implementation thereof.

[0099] Therefore, each converter unit may include an AC / DC converter stage as the first converter stage.

[0100] In one implementation of the second aspect, at least one of the at least two converter units includes an electrically isolated DC / DC converter stage as a second converter stage; the corresponding AC / DC converter stage is used to provide a DC input voltage to the electrically isolated DC / DC converter stage.

[0101] This provides electrical isolation between the input side and the grid side and the output side of the converter system, respectively.

[0102] The electrically isolated DC / DC converter stage may include a solid-state transformer (SST) that provides the electrical isolation.

[0103] Specifically, each of the at least two converter units includes an electrically isolated DC / DC converter stage as a second converter stage; the corresponding AC / DC converter stage is used to provide a DC input voltage to the isolated DC / DC converter stage.

[0104] In one implementation of the second aspect, at least one of the at least two converter units is encapsulated in a housing.

[0105] Specifically, each of the at least two converter units is encapsulated in a housing. Insulating material, particularly a solid insulating material, may be provided between the encapsulated converter units of the converter system.

[0106] Specifically, the outer casing is a metal casing electrically connected to ground potential.

[0107] In one implementation of the second aspect, the converter system includes at least one phase unit for an AC input voltage; each phase unit includes the at least two converter units connected in series at the input terminal of the converter system.

[0108] Specifically, the converter system includes two or more phase units for an AC input voltage having two or more phases; each phase unit includes the at least two converter units, which are connected in series at the input terminal of the converter system.

[0109] Specifically, when the converter system includes an input series output parallel (ISOP) structure, the at least two converter units of each phase unit are electrically connected in parallel at the output terminal of the converter system. Alternatively, when the converter system includes an input series output series (ISOS) structure, the at least two converter units of each phase unit are electrically connected in series at the output terminal of the converter system. Alternatively, the at least two converter units of each phase unit can provide an output voltage, particularly a DC output voltage, without needing to be electrically connected to each other at the output terminal of the converter system.

[0110] The converter system according to the second aspect and its implementation can achieve the same advantages as the AC / DC converter stage according to the first aspect and its corresponding implementation.

[0111] To implement the converter system according to the second aspect of the present invention, some or all of the implementations and optional features described in the second aspect above may be combined with each other.

[0112] It should be noted that all devices, elements, units, and modules described in this application can be implemented in software or hardware elements or any combination thereof. All steps performed by the various entities described in this application, and the functions described as being performed by the various entities, are intended to indicate that the respective entities are suitable for or used to perform the corresponding steps and functions. Although in the following description of specific embodiments, a particular function or step performed by an external entity is not reflected in the detailed description of the specific element of the entity performing that particular step or function, it should be apparent to those skilled in the art that these methods and functions can be implemented in the corresponding hardware or software elements or any combination thereof. Attached Figure Description

[0113] The following description of specific embodiments, in conjunction with the accompanying drawings, will illustrate the above aspects and their implementation, wherein:

[0114] Figure 1 (a) and (b) show examples of AC / DC converter stages, which include a full-bridge structure in different switching states;

[0115] Figure 2 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a half-bridge structure;

[0116] Figure 3 (a) and (b) show Figure 2 Two exemplary implementations of the AC / DC converter stage are shown;

[0117] Figure 4 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a half-bridge structure;

[0118] Figure 5 (a) and (b) show Figure 4 Two exemplary implementations of the AC / DC converter stage are shown;

[0119] Figure 6 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a half-bridge structure;

[0120] Figure 7 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a full-bridge structure;

[0121] Figure 8 (a) and (b) show Figure 7 Two exemplary implementations of the AC / DC converter stage are shown;

[0122] Figure 9An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a full-bridge structure;

[0123] Figure 10 (a) and (b) show Figure 9 Two exemplary implementations of the AC / DC converter stage are shown;

[0124] Figure 11 (a) and (b) respectively illustrate an AC / DC converter stage provided by an embodiment of the present invention, the AC / DC converter stage including a full-bridge structure;

[0125] Figure 12 (a) and (b) respectively illustrate an AC / DC converter stage provided by an embodiment of the present invention, the AC / DC converter stage including a full-bridge structure;

[0126] Figure 13 The present invention illustrates a converter system provided in an embodiment of the present invention;

[0127] Figure 14 (a) through (c) each illustrate a converter system provided by an embodiment of the present invention;

[0128] Figure 15 A converter system provided by an embodiment of the present invention is shown. Detailed Implementation

[0129] exist Figures 2 to 15 In the figures, the corresponding components are marked with the same reference numerals.

[0130] Figure 2 An AC / DC converter stage provided by an embodiment of the present invention is shown, wherein the AC / DC converter stage includes a half-bridge structure.

[0131] The above description of the AC / DC converter stage according to the first aspect and its implementation is accordingly applicable to... Figure 2 The AC / DC converter stage 1 is shown.

[0132] Figure 2 The AC / DC converter stage 1 shown includes: two input terminals (IN1, IN2) for inputting AC input voltage into the AC / DC converter stage; a branch CB1 (first branch); a first storage device C1 for providing DC output voltage; and a controllable bidirectional switch BS0.

[0133] The branch CB1 includes two switches (S1, S2), which are connected in series at connection point N1 (first connection point). The first storage device C1 includes two first storage elements in the form of two output capacitors (C1a, C1b), which are connected in series at connection point N3 (third connection point). The first storage device C1 is connected in parallel to the branch CB1. The first input terminal IN1 of the two input terminals is connected to connection point N1 (first connection point); the second input terminal IN2 of the two input terminals is connected to connection point N3 (third connection point). The controllable bidirectional switch BS0 is connected between the two input terminals (IN1, IN2). Specifically, the controllable bidirectional switch BS0 is connected between connection point N1 of the branch CB1 and connection point N3 of the first storage device C1.

[0134] According to one embodiment, the AC / DC converter stage having the half-bridge structure can be a dual-stage boost converter, the dual-stage boost converter including a second energy storage device, wherein the first input terminal IN1 or the second input terminal IN2 is electrically connected via the second energy storage device to the at least one controllable bidirectional switch BSO. Figure 2 (Not shown in the image). Alternatively, each of the first input terminal IN1 and the second input terminal IN2 may be electrically connected to the controllable bidirectional switch BS0 via a second energy storage device. The second energy storage device may include or correspond to at least one inductor or choke.

[0135] The controllable bidirectional switch BS0 is used to achieve the zero state of the AC / DC converter stage 1 by providing a current path, particularly a low-impedance current path, between the two input terminals (IN1, IN2) of the AC / DC converter stage 1 in its on state. Therefore, in the zero state, i.e., when no current flows through the first energy storage C1 used to provide the DC output voltage, no current flows through the branch CB1, particularly through the two switches (S1, S2) of the first branch CB1.

[0136] Therefore, in Figure 2 In the zero-state of the AC / DC converter stage 1 shown, the common-mode voltage is zero. Therefore, Figure 2 The AC / DC converter stage 1 shown has improved common-mode performance.

[0137] Figure 3 (a) and (b) show Figure 2 The above describes two exemplary implementations of the AC / DC converter stage. Figure 2 The description of the AC / DC converter stage shown is accordingly applicable Figure 3 The two exemplary implementations shown in (a) and (b) are as follows.

[0138] according to Figure 3 (a) The AC / DC converter stage 1 includes two controllable semiconductor switches (Q1, Q2) in the form of insulated-gate bipolar transistors (IGBTs) as two switches (S1, S2) for branch CB1, wherein diodes are connected in parallel to each IGBT. The anode of the diode is connected to the emitter terminal of the corresponding IGBT; the cathode of the diode is connected to the collector terminal of the corresponding IGBT. The emitter terminal of IGBT Q1 and the collector terminal of IGBT Q2 are electrically connected at connection point N1.

[0139] therefore, Figure 3 (a) shows an AC / DC converter stage 1 corresponding to an active switching AC / DC converter stage with a half-bridge structure, wherein AC to DC conversion is achieved by controlling the two IGBTs (Q1, Q2).

[0140] according to Figure 3 In the embodiment shown in (a), the first input terminal IN1 is electrically connected to the controllable bidirectional switch BS0 via a second energy storage device in the form of an inductor / choke L1. As described above, the second input terminal IN2, instead of the first input terminal IN1, can be electrically connected to the controllable bidirectional switch BS0 via the second energy storage device. Due to the second energy storage device L1, the AC / DC converter stage 1 is used to perform boost operation and thus corresponds to a bipolar boost converter.

[0141] like Figure 3 As shown in (a), the controllable bidirectional switch BS0 can be implemented by two IGBTs (Qa, Qb), which are connected in series at their emitter terminals. The collector terminal of IGBT Qa is electrically connected to the connection point N1; the collector terminal of IGBT Qb is electrically connected to the connection point N3. A diode is connected to each of the IGBTs (Qa, Qb) such that the anode of the diode is connected to the corresponding emitter terminal, and the cathode of the diode is connected to the corresponding collector terminal.

[0142] Regarding the implementation of the two switches (S1, S2) in the branch CB1, Figure 3 (b) shows an AC / DC converter stage that is different from... Figure 3 The AC / DC converter stage is shown in (a). That is, according to... Figure 3(b) The AC / DC converter stage 1 includes two uncontrolled unidirectional semiconductor switches (D1, D2) in the form of two diodes as the two switches (S1, S2) of the branch CB1. The anode of the diode D1 and the cathode of the diode D2 are electrically connected to the connection point N1.

[0143] Due to the change in the AC input voltage input to the two input terminals (IN1, IN2), Figure 3 (b) The switches (D1, D2) of the AC / DC converter stage 1 shown switch between an on state and a non-on state, thereby realizing the AC-to-DC conversion from the AC input voltage to the DC output voltage. In other words, the AC-to-DC conversion can be achieved because different current paths are formed via the diodes (D1, D2) due to the change in the AC input voltage.

[0144] exist Figure 3 In both embodiments, the controllable bidirectional switch BS0 can be controlled / switched by a control unit to achieve improved common-mode performance, as described above.

[0145] according to Figure 3 In (a) and (b), the switches (S1, S2) are of the same type. According to one embodiment, the switches (S1, S2) can be of different types, as described above. Figure 3 (Not shown in the image).

[0146] Figure 4 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a half-bridge structure.

[0147] The above is about Figure 2 The description of the AC / DC converter stage shown is accordingly applicable Figure 4 The AC / DC converter stage 1 is shown.

[0148] Figure 4 The AC / DC converter stage 1 shown is... Figure 2 The difference shown in the AC / DC converter stage is that, Figure 4 The branch CB1 of the AC / DC converter stage 1 shown includes more than two switches. Therefore, the following mainly describes... Figure 2 The AC / DC converter stage shown is Figure 4 The differences between the AC / DC converter stages shown.

[0149] according to Figure 4The branch (first branch) CB1 of the AC / DC converter stage 1 includes four switches (S11, S12, S13, S14) connected in series. Switches (S12, S13) are electrically connected at connection point N1 (first connection point), and the first input terminal IN1 is connected to connection point N1. Switches (S11, S12) are electrically connected at connection point N11; switches (S13, S14) are electrically connected at connection point N12.

[0150] Figure 4 The AC / DC converter stage 1 shown is relative to Figure 2 The illustrated AC / DC converter stage is advantageous. That is, since the branch CB1 includes more than two switches (four switches (S11, S12, S13, S14)), switches with lower power requirements and therefore lower cost and smaller size can be used for the same AC input voltage. In other words, when the AC input voltage exists between the two input terminals (IN1, IN2), the AC input voltage is distributed among the corresponding switches in the branch CB1, i.e., distributed between switches (S11, S12) and between switches (S13, S14). This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage 1, especially the branch CB1, and allows for a smaller size of the AC / DC converter stage 1.

[0151] Furthermore, according to Figure 4 The connection point N3 (third connection point) between the two first energy storage elements (output capacitors) (C1a, C1b) is electrically connected to the connection point N11 via switch S15, and electrically connected to the connection point N12 via switch S16.

[0152] Switch S15 ensures that the voltage drops between the switches (S11, S12) in branch CB1 are equal, thus ensuring that the stresses experienced by the switches (S11, S12) in branch CB1 are equal. Switch S16 ensures that the voltage drops between the switches (S13, S14) in branch CB1 are equal, thus ensuring that the stresses experienced by the switches (S13, S14) in branch CB1 are equal. In other words, switches (S15, S16) ensure that the voltage drops between the corresponding switches in branch CB1 are equal, thus ensuring that the stresses experienced by the switches (S11, S12, S13, S14) in branch CB1 are equal.

[0153] According to one embodiment, the number of switches in branch CB1 may be different from (especially greater than) the number of switches in branch CB1. Figure 4The number of switches shown is four switches (S11, S12, S13, S14). Correspondingly, the number of switches used to ensure equal voltage drops between the corresponding switches in branch CB1 can be different (especially greater than) Figure 4 The number of switches shown is two (S15, S16).

[0154] Figure 5 (a) and (b) show Figure 4 The above describes two exemplary implementations of the AC / DC converter stage. Figure 4 The description of the AC / DC converter stage shown is accordingly applicable Figure 5 The two exemplary implementations shown in (a) and (b) are as follows.

[0155] according to Figure 5 (a) The AC / DC converter stage 1 includes four controllable semiconductor switches (Q11, Q12, Q13, Q14) in the form of four IGBTs as four switches (S11, S12, S13, S14) for branch CB1, wherein diodes are connected in parallel to each IGBT. The anode of the diode is connected to the emitter terminal of the corresponding IGBT; the cathode of the diode is connected to the collector terminal of the corresponding IGBT. The emitter terminal of IGBT Q11 and the collector terminal of IGBT Q12 are electrically connected at connection point N11. The emitter terminal of IGBT Q12 and the collector terminal of IGBT Q13 are electrically connected at connection point N1. The emitter terminal of IGBT Q13 and the collector terminal of IGBT Q14 are electrically connected at connection point N12.

[0156] therefore, Figure 5 (a) shows AC / DC converter stage 1, which corresponds to an active switching AC / DC converter stage, wherein AC-to-DC conversion is achieved by controlling the four IGBTs (Q11, Q12, Q13, Q14). The control unit can control the four IGBTs (Q11, Q12, Q13, Q14).

[0157] Figure 5 The implementation of the controllable bidirectional switch BS0 in the AC / DC converter stage shown in (a) is as follows: Figure 3 (a) describes the controllable bidirectional switch BS0 of the AC / DC converter stage.

[0158] according to Figure 5(a) The switches (S15, S16) of the AC / DC converter stage 1 are respectively implemented as controllable semiconductor switches (Q15, Q16) in the form of IGBTs, wherein diodes are connected in parallel to each IGBT. The anode of the diode is connected to the emitter terminal of the corresponding IGBT; the cathode of the diode is connected to the collector terminal of the corresponding IGBT. The collector terminal of IGBT Q15 is connected to the connection point N11; the emitter terminal of IGBT Q15 is connected to the connection point N3 (the third connection point). The emitter terminal of IGBT Q16 is connected to the connection point N12; the collector terminal of IGBT Q16 is connected to the connection point N3 (the third connection point).

[0159] The IGBTs (Q15, Q16) can be controlled to ensure that the voltage drops among the IGBTs (Q11, Q12, Q13, Q14) in the branch CB1 are equal, so that the stress on the IGBTs (Q11, Q12, Q13, Q14) is equal.

[0160] Regarding the implementation of the two switches (S15, S16), Figure 5 (b) shows an AC / DC converter stage that is different from... Figure 5 The AC / DC converter stage is shown in (a). That is, according to... Figure 5 (b) The AC / DC converter stage 1 includes two uncontrolled unidirectional semiconductor switches (D15, D16) in the form of two diodes as the two switches (S15, S16). The cathode of diode D15 is connected to the connection point N11; the anode of diode D15 is connected to the connection point N3. The anode of diode D16 is connected to the connection point N12; the cathode of diode D16 is connected to the connection point N3.

[0161] exist Figure 5 In both embodiments, the controllable bidirectional switch BS0 can be controlled / switched by a control unit to achieve improved common-mode performance, as described above.

[0162] according to Figure 5 In (a) and (b), the switches (S11, S12, S13, S14) of branch CB1 are of the same type. According to one embodiment, at least one switch of branch CB1 may be of a different type, as described above. Figure 5 (Not shown in the image). According to another embodiment, the switches (S11, S12, S13, S14) of the branch CB1 may be different from those in the image. Figure 5 (a) and Figure 5(b) shows the switch types. For example, they can be different types of controllable semiconductor switches, or they can be uncontrollable unidirectional switches (e.g., diodes). According to... Figure 5 In (a) and (b), the switches (S15, S16) are of the same type. According to one embodiment, one of the switches (S15 or S16) may be of a different type, as described above. Figure 5 (Not shown in the image).

[0163] Figure 6 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a half-bridge structure.

[0164] The above is about Figure 2 The description of the AC / DC converter stage shown is accordingly applicable Figure 6 The AC / DC converter stage 1 is shown.

[0165] Figure 6 The AC / DC converter stage 1 shown is... Figure 2 The difference shown in the AC / DC converter stage is that, Figure 6 Each of the two switches (S1, S2) in branch CB1 of the AC / DC converter stage 1 shown includes two switches connected in series, and Figure 6 The AC / DC converter stage shown includes two controllable bidirectional switches (BS1, BS2). Therefore, the following mainly describes... Figure 2 The AC / DC converter stage shown is Figure 6 The differences between the AC / DC converter stages shown.

[0166] like Figure 6 As shown, switch S1 includes two switches (S1a, S1b), which are electrically connected at connection point N51; switch S2 includes two switches (S2a, S2b), which are electrically connected at connection point N52. In other words, each switch S1 / S2 in branch CB1 includes two switches (S1a, S1b; S2a, S2b), which are connected in series at connection points N51 / N52 (the fifth connection point).

[0167] The two switches (S1a, S1b; S2a, S2b) of each switch S1 / S2 in the branch CB1 can be two uncontrollable unidirectional switches (e.g., two diodes) or two controllable semiconductor switches (e.g., two IGBTs).

[0168] Since each switch in the first branch CB1 comprises two switches, switches with lower power requirements, and therefore lower cost and smaller size, can be used for the same AC input voltage. That is, the voltage on switch S1 is distributed between the corresponding two switches (S1a, S1b); the voltage on switch S2 is distributed between the corresponding switches (S2a, S2b). This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the two switches (S1, S2) in branch CB1, and allows for a reduction in the size of the AC / DC converter stage.

[0169] In addition, according to Figure 6 In the illustrated embodiment, the AC / DC converter stage 1 includes two controllable bidirectional switches (BS1, BS2) connected in series at connection point N4 (fourth connection point). The two controllable bidirectional switches (BS1, BS2) are used to provide a current path, particularly a low-impedance current path, between the two input terminals (IN1, IN2) when in their on state.

[0170] Specifically, the two controllable bidirectional switches (BS1, BS2) are used to achieve the zero state of the AC / DC converter stage 1 by providing a current path, particularly a low-impedance current path, between the two input terminals (IN1, IN2) of the AC / DC converter stage 1 in their on state. Therefore, in the zero state, i.e., when no current flows through the first storage device C1 used to provide the DC output voltage, no current flows through the branch CB1, particularly through the two switches (S1, S2) of the first branch CB1.

[0171] Therefore, in Figure 6 In the zero-state of the AC / DC converter stage 1 shown, the common-mode voltage is zero. Therefore, Figure 6 The AC / DC converter stage 1 shown has improved common-mode performance.

[0172] according to Figure 6 The controllable bidirectional switch BS1 is connected between connection point N1 (first connection point) and connection point N4, and the controllable bidirectional switch BS2 is connected between connection point N4 and connection point N3 (third connection point).

[0173] Since the AC / DC converter stage 1 includes two controllable bidirectional switches (BS1, BS2), controllable bidirectional switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage, because the AC input voltage is distributed between the two controllable bidirectional switches (BS1, BS2). This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the two controllable bidirectional switches (BS1, BS2), and allows for a reduction in the size of the AC / DC converter stage.

[0174] Furthermore, the number of the controllable bidirectional switches is increased from one controllable bidirectional switch BS0 (e.g. Figure 2 The AC / DC converter stage shown is added to two controllable bidirectional switches (BS1, BS2) (as shown). Figure 6 The situation shown can increase the AC input voltage input to the AC / DC converter stage 1. That is, the AC input voltage is distributed between the two controllable bidirectional switches (BS1, BS2). This is advantageous because when the AC / DC converter stage 1 is used as the first converter stage in the converter unit of the converter system, wherein the converter unit is connected in series at the input of the converter system (…). Figure 6 Not shown in the image, but Figures 13 to 15 As shown in the diagram, fewer converter units are needed for the same AC input voltage. That is, each converter unit can handle higher input voltages due to the two controllable bidirectional switches (BS1, BS2).

[0175] The two controllable bidirectional switches (BS1, BS2) are used to achieve the zero state of AC / DC converter stage 1 by providing a current path, especially a low-impedance current path, between the two input terminals (IN1, IN2) of the AC / DC converter stage in their on state.

[0176] according to Figure 6 A low-current diode D1c is electrically connected between connection point N51 and connection point N3 (the third connection point) located between the two output capacitors (C1a, C1b), wherein the cathode of diode D1c is connected to connection point N51 and the anode of diode D1c is connected to connection point N3. A low-current diode D2c is electrically connected between connection point N52 and connection point N3 (the third connection point), wherein the anode of diode D2c is connected to connection point N52 and the cathode of diode D2c is connected to connection point N3.

[0177] According to one embodiment, each of the two switches (S1, S2) in branch CB1 may include a slow recovery diode and a fast recovery diode, wherein the low-current diodes (D1c, D2c) are used to provide recovery charge. For example, each of the switches (S1b, S2a) may be implemented as a slow recovery diode; each of the switches (S1a, S2b) may be implemented as a fast recovery diode.

[0178] For each switch (S1, S2) of the branch CB1 of the AC / DC converter stage 1, using a slow recovery diode and a fast recovery diode can reduce costs because the cost of the slow recovery diode is lower than that of the fast recovery diode.

[0179] According to one embodiment, each of the switches (S1, S2) in the branch CB1 may include two controllable semiconductor switches (e.g., two IGBTs), wherein the low-current diodes (D1c, D2c) are used to ensure that the voltage drop at the two controllable semiconductor switches is equal.

[0180] When each switch (S1, S2) includes two IGBTs, a slow recovery diode can be connected in parallel to one of the two IGBTs, and a fast recovery diode can be connected in parallel to the other IGBT. For example, a slow recovery diode can be connected in parallel to the IGBTs (S1b, S2a); a fast recovery diode can be connected in parallel to the other IGBTs (S1a, S2b). This reduces costs because slow recovery diodes are less expensive than fast recovery diodes.

[0181] Figure 7 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a full-bridge structure.

[0182] The above is about Figure 2 The description of the AC / DC converter stage shown is accordingly applicable Figure 7 The AC / DC converter stage 1 is shown.

[0183] Figure 7 The AC / DC converter stage 1 shown is... Figure 2 The difference shown in the AC / DC converter stage is that, Figure 7 The AC / DC converter stage shown includes a full-bridge structure, while Figure 2 The AC / DC converter stage shown includes a half-bridge structure. Therefore, the following mainly describes... Figure 2 The AC / DC converter stage shown is Figure 7 The differences between the AC / DC converter stages shown.

[0184] Figure 7 The AC / DC converter stage 1 shown includes: two input terminals (IN1, IN2) for inputting AC input voltage into the AC / DC converter stage 1; two branches CB1 (first branch) and CB2 (second branch); a first accumulator C1 for providing DC output voltage; and a controllable bidirectional switch BS0.

[0185] The first branch CB1 includes two switches (S1, S2), which are connected in series at the first connection point N1. The second branch CB2 includes two switches (S3, S4), which are connected in series at the second connection point N2. The first storage device C1 includes or corresponds to a first storage element in the form of an output capacitor C1. Alternatively, the first storage device C1 may include or correspond to at least two first storage elements in the form of two output capacitors (C1a, C1b), which are connected in series at the third connection point N3. Figure 7 (Not shown in the image) are connected in series. The first branch CB1, the second branch CB2, and the first storage device C1 are connected in parallel. The first input terminal IN1 of the two input terminals is electrically connected to the first connection point N1; the second input terminal IN2 of the two input terminals is electrically connected to the second connection point N2.

[0186] The controllable bidirectional switch BS0 is electrically connected between the two input terminals (IN1, IN2). Specifically, the controllable bidirectional switch is electrically connected between the first connection point N1 of the first branch CB1 and the second connection point N2 of the second branch CB2.

[0187] According to one embodiment, the AC / DC converter stage 1 having the full-bridge structure can be a bipolar boost converter, the bipolar boost converter including a second energy storage device, wherein the first input terminal IN1 or the second input terminal IN2 is electrically connected via the second energy storage device to the at least one controllable bidirectional switch BSO. Figure 7 (Not shown in the image). Alternatively, each of the first input terminal IN1 and the second input terminal IN2 may be electrically connected to the controllable bidirectional switch BS0 via a second energy storage device. The second energy storage device may include or correspond to at least one inductor or choke.

[0188] In the case where the AC / DC converter stage 1 is a bipolar boost converter, wherein the bipolar boost converter includes a second energy storage device in the form of at least one inductor or choke, for example, the second energy storage device is connected to the controllable bidirectional switch BSO at the first input terminal IN1. Figure 7The electrical connection between (not shown in the image) and the boost operation can be briefly described as follows:

[0189] When the controllable bidirectional switch BS0 is turned on to the conducting state, the current of the at least one inductor / choke (the second energy storage device) increases, thereby storing electrical energy in the inductor / choke.

[0190] - After the controllable bidirectional switch BS0 is turned off to the non-conducting state, the input voltage and the voltage on the at least one inductor / choke will drive current through the branch (CB1, CB2) to charge the first storage device C1 (output capacitor).

[0191] The controllable bidirectional switch BS0 is used to achieve a zero state for the AC / DC converter stage 1 by providing a current path, particularly a low-impedance current path, between the two input terminals (IN1, IN2) of the AC / DC converter stage 1 in its on state. Therefore, in the zero state, i.e., when no current flows through the first energy storage C1 used to provide the DC output voltage, no current flows through the first branch CB1 and the second branch CB2. Specifically, in the zero state, no current flows through any one of the switches (S1, S2, S3, S4) of the AC / DC converter stage 1.

[0192] Therefore, in Figure 7 In the zero-state of the AC / DC converter stage 1 shown, the common-mode voltage is zero. Therefore, Figure 7 The AC / DC converter stage 1 shown has improved common-mode performance.

[0193] Figure 8 (a) and (b) show Figure 7 The above describes two exemplary implementations of the AC / DC converter stage. Figure 7 The description of the AC / DC converter stage shown is accordingly applicable Figure 8 The two exemplary implementations shown in (a) and (b) are as follows.

[0194] Figure 8 The AC / DC converter stage 1 shown is... Figure 3 The difference shown in the AC / DC converter stage is that, Figure 8 The AC / DC converter stage shown includes a full-bridge structure, while Figure 3 The AC / DC converter stage shown includes a half-bridge structure. Therefore, the above regarding... Figure 3 The descriptions of the two exemplary implementations of the AC / DC converter stage shown in (a) and (b) are accordingly applicable to Figure 8 (a) and (b) show two exemplary implementations of the AC / DC converter stage.

[0195] according to Figure 8 (a) The AC / DC converter stage 1 includes four controllable semiconductor switches (Q1, Q2, Q3, Q4) in the form of four insulated-gate bipolar transistors (IGBTs) as four switches (S1, S2, S3, S4) for the first branch CB1 and the second branch CB2. Diodes are connected in parallel to each IGBT, wherein the anode of the diode is connected to the emitter terminal of the corresponding IGBT, and the cathode of the diode is connected to the collector terminal of the corresponding IGBT. The emitter terminal of IGBT Q1 and the collector terminal of IGBT Q2 are electrically connected at a first connection point N1. The emitter terminal of IGBT Q3 and the collector terminal of IGBT Q4 are electrically connected at a second connection point N2.

[0196] therefore, Figure 8 (a) shows AC / DC converter stage 1, which corresponds to an active switching AC / DC converter stage with a full-bridge structure, wherein AC / DC conversion is achieved by controlling the four IGBTs (Q1, Q2, Q3, Q4).

[0197] according to Figure 8 In the embodiment shown in (a), the first input terminal IN1 is electrically connected to the controllable bidirectional switch BS0 via a second energy storage device L1 in the form of an inductor / choke. As described above, the second input terminal IN2, instead of the first input terminal IN1, can be electrically connected to the controllable bidirectional switch BS0 via the second energy storage device L1. Due to the second energy storage device L1, the AC / DC converter stage 1 is used to perform boost operation, and thus corresponds to a bipolar boost converter.

[0198] like Figure 8 As shown in (a), the controllable bidirectional switch BS0 can be implemented by two IGBTs (Qa, Qb), which are connected in series at their emitter terminals. The collector terminal of IGBT Qa is electrically connected to the first connection point N1; the collector terminal of IGBT Qb is electrically connected to the second connection point N2. A diode is connected to each of the IGBTs (Qa, Qb) such that the anode of the diode is connected to the corresponding emitter terminal, and the cathode of the diode is connected to the corresponding collector terminal.

[0199] Figure 8 The boost operation of AC / DC converter stage 1 shown in (a) can be briefly described as follows:

[0200] When the two IGBTs (Qa, Qb) of the controllable bidirectional switch BS0 are turned on, the current in the inductor / choke L1 (the second energy storage device) increases, thereby storing electrical energy in the inductor / choke L1.

[0201] - After the two IGBTs (Qa, Qb) are turned off to the non-conducting state, the input voltage and the voltage on the inductor / choke L1 will drive current through the branch (CB1, CB2) to charge the first energy storage C1 (output capacitor), wherein the IGBTs (Q1, Q2, Q3, Q4) are controlled accordingly.

[0202] Regarding the implementation of the two switches (S1, S2) in the first branch CB1 and the two switches (S3, S4) in the second branch CB2, Figure 8 (b) shows an AC / DC converter stage that is different from... Figure 8 The AC / DC converter stage is shown in (a). That is, according to... Figure 8 (b) The AC / DC converter stage 1 includes two uncontrolled unidirectional semiconductor switches (D1, D2) in the form of two diodes as the two switches (S1, S2) of the first branch CB1. The anode of diode D1 and the cathode of diode D2 are electrically connected to the first connection point N1. Further, the AC / DC converter stage 1 includes two uncontrolled unidirectional semiconductor switches (D3, D4) in the form of two diodes as the two switches (S3, S4) of the second branch CB2. The anode of diode D3 and the cathode of diode D4 are electrically connected to the second connection point N2.

[0203] Due to the change in the AC input voltage input to the two input terminals (IN1, IN2), Figure 8 (b) The switches (D1, D2, D3, D4) of the AC / DC converter stage 1 shown switch between an on state and a non-conducting state, thereby realizing the AC-to-DC conversion from the AC input voltage to the DC output voltage. In other words, the AC-to-DC conversion can be achieved because different current paths are formed via the diodes (D1, D2, D3, D4) due to the change in the AC input voltage.

[0204] Figure 8 The boost operation of AC / DC converter stage 1 shown in (b) can be briefly described as follows:

[0205] When the two IGBTs (Qa, Qb) of the controllable bidirectional switch BS0 are turned on, the current in the inductor / choke L1 (the second energy storage device) increases, thereby storing electrical energy in the inductor / choke L1.

[0206] - After the two IGBTs (Qa, Qb) are turned off to the non-conducting state, the input voltage and the voltage on the inductor / choke L1 will drive current through the corresponding diode to charge the first energy storage C1 (output capacitor).

[0207] exist Figure 8 In both embodiments, the controllable bidirectional switch BS0 can be controlled / switched by a control unit to achieve improved common-mode performance, as described above.

[0208] according to Figure 8 In (a) and (b), the switches (S1, S2, S3, S4) are of the same type. According to one embodiment, at least one of the switches (S1, S2, S3, S4) may be of different types, as described above. Figure 8 (Not shown in the image).

[0209] Figure 9 An AC / DC converter stage provided by an embodiment of the present invention is shown, the AC / DC converter stage including a full-bridge structure.

[0210] The above is about Figure 7 The description of the AC / DC converter stage shown is accordingly applicable Figure 9 The AC / DC converter stage 1 is shown.

[0211] Figure 9 The AC / DC converter stage 1 shown is... Figure 7 The difference shown in the AC / DC converter stage is that, Figure 9 Each of the first branch CB1 and the second branch CB2 of the AC / DC converter stage 1 shown includes more than two switches. Therefore, the following mainly describes... Figure 7 The AC / DC converter stage shown is Figure 9 The differences between the AC / DC converter stages shown.

[0212] Figure 9 The AC / DC converter stage 1 shown is... Figure 4 The difference shown in the AC / DC converter stage is that, Figure 9 The AC / DC converter stage shown includes a full-bridge structure, while Figure 4 The AC / DC converter stage shown includes a half-bridge structure. Therefore, the above regarding... Figure 4The description of the AC / DC converter stage shown is accordingly applicable Figure 9 The AC / DC converter stage shown.

[0213] according to Figure 9 The first branch CB1 of the AC / DC converter stage 1 includes four switches (S11, S12, S13, S14) connected in series. Switches (S12, S13) are electrically connected at a first connection point N1, and a first input terminal IN1 is connected to the first connection point N1. Switches (S11, S12) are electrically connected at connection point N11; switches (S13, S14) are electrically connected at connection point N12. The second branch CB2 of the AC / DC converter stage 1 includes four switches (S21, S22, S23, S24) connected in series. Switches (S22, S23) are electrically connected at a second connection point N2, and a second input terminal IN2 is connected to the second connection point N2. Switches (S21, S22) are electrically connected at connection point N21; switches (S23, S24) are electrically connected at connection point N22.

[0214] Figure 9 The AC / DC converter stage 1 shown is relative to Figure 7 The illustrated AC / DC converter stage is advantageous. That is, since each of the branches (CB1, CB2) includes more than two switches (four switches (S11, S12, S13, S14) for CB1; four switches (S21, S22, S23, S24) for CB2), switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage. In other words, when the AC input voltage exists between the two input terminals (IN1, IN2), the AC input voltage is distributed among the corresponding switches in the first branch CB1 and the second branch CB2, i.e., among the switches (S11, S12, S21, S22) and among the switches (S13, S14, S23, S24), respectively. This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the first branch CB1 and the second branch CB2, and allows for a smaller size of the AC / DC converter stage.

[0215] Furthermore, according to Figure 9The first storage device C1 includes or corresponds to two first storage elements in the form of two output capacitors (C1a, C1b), and the two first storage elements are connected in series at a third connection point N3. The third connection point N3 is electrically connected to the connection point N11 via switch S15, to the connection point N12 via switch S16, to the connection point N21 via switch S25, and to the connection point N22 via switch S26.

[0216] Switch S15 ensures that the voltage drops between the switches (S11, S12) in the first branch CB1 are equal, so that the stresses on the switches (S11, S12) in the first branch CB1 are equal. Switch S16 ensures that the voltage drops between the switches (S13, S14) in the first branch CB1 are equal, so that the stresses on the switches (S13, S14) in the first branch CB1 are equal. This also applies to the corresponding switches (S25, S26) and the switches (S21, S22, S23, S24) in the second branch CB2. Therefore, the switches (S15, S16, S25, S26) ensure that the voltage drop between the corresponding switches in the first branch CB1 and the second branch CB2 is equal, so that the stress on the switches (S11, S12, S13, S14) in the first branch CB1 and the switches (S21, S22, S23, S24) in the second branch CB2 is equal.

[0217] According to one embodiment, the number of switches in the first branch CB1 and / or the number of switches in the second branch CB2 may be different from (especially greater than) those in other branches. Figure 9 The number of switches shown is (four switches (S11, S12, S13, S14) for CB1; four switches (S21, S22, S23, S24) for CB2). Correspondingly, the number of switches used to ensure equal voltage drops between corresponding switches in the first branch CB1 and / or the number of switches used to ensure equal voltage drops between corresponding switches in the second branch CB2 can be different from (especially greater than) these numbers. Figure 9 The quantities shown are (two switches (S15, S16) of CB1; two switches (S25, S26) of CB2).

[0218] Figure 10 (a) and (b) show Figure 9 The above describes two exemplary implementations of the AC / DC converter stage. Figure 9 The description of the AC / DC converter stage shown is accordingly applicable Figure 10 The two exemplary implementations shown in (a) and (b) are as follows.

[0219] Figure 10The AC / DC converter stage 1 shown is... Figure 5 The difference shown in the AC / DC converter stage is that, Figure 10 The AC / DC converter stage shown includes a full-bridge structure, while Figure 5 The AC / DC converter stage shown includes a half-bridge structure. Therefore, the above regarding... Figure 5 The descriptions of the two exemplary implementations of the AC / DC converter stage shown in (a) and (b) are accordingly applicable to Figure 10 (a) and (b) show two exemplary implementations of the AC / DC converter stage.

[0220] according to Figure 10 (a) The AC / DC converter stage 1 includes four controllable semiconductor switches (Q11, Q12, Q13, Q14) in the form of four IGBTs as four switches (S11, S12, S13, S14) for the first branch CB1. Further, the AC / DC converter stage 1 includes four controllable semiconductor switches (Q21, Q22, Q23, Q24) in the form of four IGBTs as four switches (S21, S22, S23, S24) for the second branch CB2. Diodes are connected in parallel to each IGBT, wherein the anode of the diode is connected to the emitter terminal of the corresponding IGBT, and the cathode of the diode is connected to the collector terminal of the corresponding IGBT.

[0221] The emitter terminal of IGBT Q11 and the collector terminal of IGBT Q12 are electrically connected at connection point N11. The emitter terminal of IGBT Q12 and the collector terminal of IGBT Q13 are electrically connected at a first connection point N1. The emitter terminal of IGBT Q13 and the collector terminal of IGBT Q14 are electrically connected at connection point N12. The emitter terminal of IGBT Q21 and the collector terminal of IGBT Q22 are electrically connected at connection point N21. The emitter terminal of IGBT Q22 and the collector terminal of IGBT Q23 are electrically connected at a second connection point N2. The emitter terminal of IGBT Q23 and the collector terminal of IGBT Q24 are electrically connected at connection point N22.

[0222] therefore, Figure 10 (a) shows AC / DC converter stage 1, which corresponds to an actively switching AC / DC converter stage, wherein AC / DC conversion is achieved by controlling the eight IGBTs (Q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24). The eight IGBTs (Q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24) can be controlled by a control unit.

[0223] Figure 10 The implementation of the controllable bidirectional switch BS0 in the AC / DC converter stage shown in (a) is as follows: Figure 8 (a) describes the controllable bidirectional switch BS0 of the AC / DC converter stage.

[0224] according to Figure 10 (a) The switches (S15, S16, S25, S26) of the AC / DC converter stage 1 are respectively implemented as controllable semiconductor switches (Q15, Q16, Q25, Q26) in the form of IGBTs, wherein diodes are connected in parallel to each IGBT. The anode of the diode is connected to the emitter terminal of the corresponding IGBT; the cathode of the diode is connected to the collector terminal of the corresponding IGBT.

[0225] The collector terminal of IGBT Q15 is connected to connection point N11; the emitter terminal of IGBT Q15 is connected to the third connection point N3. The emitter terminal of IGBT Q16 is connected to connection point N12; the collector terminal of IGBT Q16 is connected to the third connection point N3. The collector terminal of IGBT Q25 is connected to connection point N21; the emitter terminal of IGBT Q25 is connected to the third connection point N3. The emitter terminal of IGBT Q26 is connected to connection point N22; the collector terminal of IGBT Q26 is connected to the third connection point N3.

[0226] The IGBTs (Q15, Q16, Q25, Q26) can be controlled to ensure that the voltage drops between the IGBTs (Q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24) in the first branch CB1 and the second branch CB2 are equal, so that the stress on the IGBTs (Q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24) is equal.

[0227] Regarding the implementation of the four switches (S15, S16, S25, S26), Figure 10 (b) shows an AC / DC converter stage that is different from... Figure 10 The AC / DC converter stage is shown in (a). That is, according to... Figure 10 (b) The AC / DC converter stage 1 includes four uncontrolled unidirectional semiconductor switches (D15, D16, D25, D26) in the form of four diodes as the four switches (S15, S16, S25, S26).

[0228] The cathode of diode D15 is connected to connection point N11; the anode of diode D15 is connected to the third connection point N3. The anode of diode D16 is connected to connection point N12; the cathode of diode D16 is connected to the third connection point N3. The cathode of diode D25 is connected to connection point N21; the anode of diode D25 is connected to the third connection point N3. The anode of diode D26 is connected to connection point N22; the cathode of diode D26 is connected to the third connection point N3.

[0229] exist Figure 10 In both embodiments, the controllable bidirectional switch BS0 can be controlled / switched by a control unit to achieve improved common-mode performance, as described above.

[0230] according to Figure 10 In (a) and (b), the switches (S11, S12, S13, S14, S21, S22, S23, S24) of the branches (CB1, CB2) are of the same switch type. According to one embodiment, at least one switch of the branches (CB1, CB2) can be of different switch types, as described above. Figure 10 (Not shown in the image). According to another embodiment, the switches (S11, S12, S13, S14, S21, S22, S23, S24) of the branches (CB1, CB2) may be different from those in the image. Figure 10 (a) and Figure 10 (b) shows the switch types. For example, they can be different types of controllable semiconductor switches, or they can be uncontrollable unidirectional switches (e.g., diodes). According to... Figure 10 In (a) and (b), the switches (S15, S16, S25, S26) are of the same type. According to one embodiment, at least one of the switches (S15, S16, S25, S26) may be of different types, as described above. Figure 10 (Not shown in the image).

[0231] Figure 11 (a) and (b) respectively illustrate an AC / DC converter stage provided by an embodiment of the present invention, the AC / DC converter stage including a full-bridge structure.

[0232] The above is about Figure 7 The description of the AC / DC converter stage shown is accordingly applicable Figure 11 AC / DC converter stage 1 is shown in (a) and (b).

[0233] Figure 11 The AC / DC converter stage 1 shown in (a) and (b) is... Figure 7 The difference shown in the AC / DC converter stage is that, Figure 11 Each of the four switches (S1, S2, S3, S4) in the branch (CB1, CB2) of AC / DC converter stage 1 shown in (a) and (b) comprises two switches connected in series, and Figure 11 The AC / DC converter stages shown in (a) and (b) include two controllable bidirectional switches. Therefore, the following mainly describes... Figure 7 The AC / DC converter stage shown is Figure 11 The differences between the AC / DC converter stages shown in (a) and (b).

[0234] Figure 11 The AC / DC converter stage 1 shown in (a) and (b) is... Figure 6 The difference shown in the AC / DC converter stage is that, Figure 11 The AC / DC converter stages shown in (a) and (b) include a full-bridge structure, while Figure 6 The AC / DC converter stage shown includes a half-bridge structure. Furthermore, Figure 11 The converter stages shown in (a) and (b) include uncontrolled unidirectional semiconductor switches in the form of diodes as switches for the first and second branches. Therefore, the above regarding Figure 6 The description of the AC / DC converter stage shown is accordingly applicable Figure 11 (a) and Figure 11 Example (b) is shown.

[0235] according to Figure 11 In the embodiment shown in (a), the AC / DC converter stage 1 includes two controllable bidirectional switches (BS1, BS2) connected in series at a fourth connection point N4. The two controllable bidirectional switches (BS1, BS2) are used to provide a current path, particularly a low-impedance current path, between the two input terminals (IN1, IN2) when in their on state. Figure 11 (a) The controllable bidirectional switch BS1 is connected between the fourth connection point N4 and the first connection point N1 of the first branch CB1. The controllable bidirectional switch BS2 is connected between the fourth connection point N4 and the second connection point N2 of the second branch CB2.

[0236] The fourth connection point N4 is electrically connected to the third connection point N3 between the two output capacitors (C1a, C1b), which form a first storage device C1 for providing DC output voltage. This ensures that the AC input voltage is evenly distributed between the two controllable bidirectional switches (BS1, BS2).

[0237] Figure 11The implementation of each of the two controllable bidirectional switches (BS1, BS2) in the AC / DC converter stage shown in (a) is as follows: Figure 8 (a) describes the controllable bidirectional switch BS0 of the AC / DC converter stage.

[0238] Since the AC / DC converter stage 1 includes two controllable bidirectional switches (BS1, BS2), controllable bidirectional switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage, because the AC input voltage is distributed between the two controllable bidirectional switches (BS1, BS2). This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the two controllable bidirectional switches (BS1, BS2), and allows for a reduction in the size of the AC / DC converter stage.

[0239] Furthermore, the number of the controllable bidirectional switches is increased from one controllable bidirectional switch BS0 (e.g. Figure 7 The AC / DC converter stage shown is added to two controllable bidirectional switches (BS1, BS2) (as shown). Figure 11 The situation shown can increase the AC input voltage input to the AC / DC converter stage. That is, the AC input voltage is distributed between the two controllable bidirectional switches (BS1, BS2). This is advantageous because when the AC / DC converter stage 1 is used as the first converter stage in the converter unit of the converter system, wherein the converter unit is connected in series at the input of the converter system (…). Figure 11 Not shown in the image, but Figures 13 to 15 As shown in the diagram, fewer converter units are needed for the same AC input voltage. That is, each converter unit can handle higher input voltages due to the two controllable bidirectional switches (BS1, BS2).

[0240] like Figure 11As shown in (a), regarding the first branch CB1, switch S1 comprises two switches (S1a, S1b) in the form of two diodes (D1a, D1b), which are electrically connected at connection point N51; switch S2 comprises two switches (S2a, S2b) in the form of two diodes (D2a, D2b), which are electrically connected at connection point N52. The anode of diode D1a and the cathode of diode D1b are connected to connection point N51, and therefore the anode of diode D1b is connected to the first connection point N1. The cathode of diode D2b and the anode of diode D2a are connected to connection point N52, and therefore the cathode of diode D2a is connected to the first connection point N1.

[0241] Regarding the second branch CB2, switch S3 comprises two switches (S3a, S3b) in the form of two diodes (D3a, D3b), which are electrically connected at connection point N53; switch S4 comprises two switches (S4a, S4b) in the form of two diodes (D4a, D4b), which are electrically connected at connection point N54. The anode of diode D3a and the cathode of diode D3b are connected to connection point N53, and therefore the anode of diode D3b is connected to the first connection point N1. The cathode of diode D4b and the anode of diode D4a are connected to connection point N54, and therefore the cathode of diode D4a is connected to the second connection point N2.

[0242] In other words, each switch S1 / S2 / S3 / S4 of the branch (CB1, CB2) comprises two switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) in the form of two diodes (D1a, D1b; D2a, D2b; D3a, D3b; D4a, D4b), and the two switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) are connected in series at the fifth connection point N51 / N52 / N53 / N54.

[0243] Since each switch in the first branch CB1 and the second branch CB2 comprises two switches, switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage. That is, the voltage on switch S1 is distributed between the corresponding two switches (S1a, S1b); the voltage on switch S2 is distributed between the corresponding switches (S2a, S2b). The same applies to the two switches (S3, S4) of the second branch CB2. This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the switches (S1, S2, S3, S4) of the branches (CB1, CB2), and allows for a reduction in the size of the AC / DC converter stage.

[0244] according to Figure 11 In the embodiment shown in (a), the AC / DC converter stage 1 includes two second capacitors in the form of inductors or chokes (L1a, L1b). A first input terminal IN1 is electrically connected to the two controllable bidirectional switches (BS1, BS2), particularly the controllable bidirectional switch BS1, via the second capacitor L1a. That is, the first input terminal IN1 is electrically connected to the first connection point N1 of the first branch CB1 via the second capacitor L1a. A second input terminal IN2 is electrically connected to the two controllable bidirectional switches (BS1, BS2), particularly the controllable bidirectional switch BS2, via the second capacitor L1b. That is, the second input terminal IN2 is electrically connected to the second connection point N2 of the second branch CB2 via the second capacitor L1b.

[0245] Alternatively, the AC / DC converter stage may include only one second battery, and the first input terminal IN1 or the second input terminal IN2 may be electrically connected via the second battery to the two controllable bidirectional switches (BS1, BS2). Figure 11 (not shown in (a)).

[0246] Figure 11 (b) shows the AC / DC converter stage corresponding to Figure 11 (a) shows the AC / DC converter stage, where... Figure 11 (b) shows an AC / DC converter stage that includes additional electronic components. Therefore, regarding Figure 11 The description of the AC / DC converter stage shown in (a) also applies. Figure 11 (b) shows the AC / DC converter stage. Only the additional electronic components are described below.

[0247] according to Figure 11In the embodiment shown in (b), the AC / DC converter stage 1 includes four low-current diodes (D1c, D2c, D3c, D4c). The cathode of diode D1c is connected to the connection point N51; the anode of diode D1c is connected to the third connection point N3 between the two output capacitors (C1a, C1b). The anode of diode D2c is connected to the connection point N52; the cathode of diode D2c is connected to the third connection point N3. The cathode of diode D3c is connected to the connection point N53; the anode of diode D3c is connected to the third connection point N3. The anode of diode D4c is connected to the connection point N54; the cathode of diode D4c is connected to the third connection point N3.

[0248] according to Figure 11 In the embodiment shown in (b), each switch (S1, S2, S3, S4) of the branch (CB1, CB2) includes a slow recovery diode and a fast recovery diode, wherein the low-current diodes (D1c, D2c, D3c, D4c) are used to provide recovery charge. For example, each of the switches (S1b, S2a, S3b, S4a) can be implemented as a slow recovery diode; each of the switches (S1a, S2b, S3a, S4b) can be implemented as a fast recovery diode.

[0249] For each switch (S1, S2, S3, S4) of the branch (CB1, CB2) of the AC / DC converter stage 1, using a slow recovery diode and a fast recovery diode can reduce costs because the slow recovery diode is less expensive than the fast recovery diode.

[0250] Figure 12 (a) and (b) respectively illustrate an AC / DC converter stage provided by an embodiment of the present invention, the AC / DC converter stage including a full-bridge structure.

[0251] Regarding the switches of the aforementioned branches (CB1, CB2), Figure 12 The AC / DC converter stage 1 shown in (a) and (b) is different from... Figure 11 The AC / DC converter stages shown in (a) and (b) are based on... Figure 11 In the embodiments shown in (a) and (b), the switch of the branch corresponds to a diode, and according to Figure 12 In the embodiments shown in (a) and (b), the switch of the branch corresponds to an IGBT. Therefore, the above regarding Figure 11 The descriptions of the AC / DC converter stages shown in (a) and (b) are accordingly applicable Figure 12 AC / DC converter stage 1 is shown in (a) and (b); the following mainly describes... Figure 11The AC / DC converter stage shown is Figure 12 The differences between the AC / DC converter stages shown.

[0252] like Figure 12 As shown in (a), regarding the first branch CB1, switch S1 comprises two switches (S1a, S1b) in the form of two IGBTs (Q1a, Q1b), which are electrically connected at connection point N51; switch S2 comprises two switches (S2a, S2b) in the form of two IGBTs (Q2a, Q2b), which are electrically connected at connection point N52. The emitter terminal of IGBT Q1a and the collector terminal of IGBT Q1b are connected to connection point N51, and therefore the emitter terminal of IGBT Q1b is connected to the first connection point N1. The collector terminal of IGBT Q2b and the emitter terminal of IGBT Q2a are connected to connection point N52, and therefore the collector terminal of IGBT Q2a is connected to the first connection point N1.

[0253] Regarding the second branch CB2, switch S3 comprises two switches (S3a, S3b) in the form of two IGBTs (Q3a, Q3b), which are electrically connected at connection point N53; switch S4 comprises two switches (S4a, S4b) in the form of two IGBTs (Q4a, Q4b), which are electrically connected at connection point N54. The emitter terminal of IGBT Q3a and the collector terminal of IGBT Q3b are connected to connection point N53, and therefore the emitter terminal of IGBT Q3b is connected to the second connection point N2. The collector terminal of IGBT Q4b and the emitter terminal of IGBT Q4a are connected to connection point N54, and therefore the collector terminal of IGBT Q4a is connected to the second connection point N2.

[0254] A diode is connected in parallel to each IGBT, wherein the anode of the diode is connected to the emitter terminal of the corresponding IGBT, and the cathode of the diode is connected to the collector terminal of the corresponding IGBT.

[0255] In other words, each switch S1 / S2 / S3 / S4 of the branch (CB1, CB2) comprises two switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) in the form of two IGBTs (Q1a, Q1b; Q2a, Q2b; Q3a, Q3b; Q4a, Q4b), and the two switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) are connected in series at the fifth connection point N51 / N52 / N53 / N54.

[0256] Since each switch in the first branch CB1 and the second branch CB2 comprises two switches, switches for lower power, and therefore lower cost and smaller size, can be used for the same AC input voltage. That is, the voltage on switch S1 is distributed between the corresponding two switches (S1a, S1b); the voltage on switch S2 is distributed between the corresponding switches (S2a, S2b). The same applies to the two switches (S3, S4) of the second branch CB2. This is advantageous because using lower cost and smaller size switches reduces the cost of implementing the AC / DC converter stage, especially the switches (S1, S2, S3, S4) of the branches (CB1, CB2), and allows for a reduction in the size of the AC / DC converter stage.

[0257] about Figure 12 (a) The two controllable bidirectional switches (BS1, BS2) and the two second batteries (L1a, L1b) of the AC / DC converter stage 1 shown in (a) are referenced. Figure 11 (a) shows the corresponding description of the AC / DC converter stage.

[0258] According to another embodiment, different types of controllable semiconductor switches can be used instead of IGBTs for the switches (S1a, S1b, S2a, S2b, S3a, S3b, S4a, S4b).

[0259] Figure 12 (b) shows the AC / DC converter stage corresponding to Figure 12 (a) shows the AC / DC converter stage, where... Figure 12 (b) shows an AC / DC converter stage that includes additional electronic components. Therefore, regarding Figure 12 The description of the AC / DC converter stage shown in (a) also applies. Figure 12 (b) shows the AC / DC converter stage. Only the additional electronic components are described below.

[0260] according to Figure 12In the embodiment shown in (b), the AC / DC converter stage 1 includes four low-current diodes (D1c, D2c, D3c, D4c). The cathode of diode D1c is connected to the connection point N51; the anode of diode D1c is connected to the third connection point N3 between the two output capacitors (C1a, C1b). The anode of diode D2c is connected to the connection point N52; the cathode of diode D2c is connected to the third connection point N3. The cathode of diode D3c is connected to the connection point N53; the anode of diode D3c is connected to the third connection point N3. The anode of diode D4c is connected to the connection point N54; the cathode of diode D4c is connected to the third connection point N3.

[0261] The low-current diodes (D1c, D2c, D3c, D4c) are used to ensure that the voltage drops at the IGBTs in the branches (CB1, CB2) are equal. Regarding the first branch CB1, the low-current diode D1c is used to ensure that the voltage drops between the IGBTs (Q1a, Q1b) of the switch S1 are equal; the low-current diode D2c is used to ensure that the voltage drops between the IGBTs (Q2a, Q2b) of the switch S2 are equal. Regarding the second branch CB2, the low-current diode D3c is used to ensure that the voltage drops between the IGBTs (Q3a, Q3b) of the switch S3 are equal; the low-current diode D4c is used to ensure that the voltage drops between the IGBTs (Q4a, Q4b) of the switch S4 are equal.

[0262] According to one embodiment, for each switch (S1, S2, S3, S4) comprising two IGBTs, a slow recovery diode can be connected in parallel to one IGBT of each switch; a fast recovery diode can be connected in parallel to the other IGBT of each switch. For example, a slow recovery diode can be connected in parallel to the IGBTs (Q1b, Q2a, Q3b, Q4a); a fast recovery diode can be connected in parallel to the other IGBTs (Q1a, Q2b, Q3a, Q4b). This can reduce costs because the cost of a slow recovery diode is lower than that of a fast recovery diode.

[0263] Figure 13 A converter system provided by an embodiment of the present invention is shown.

[0264] The above description of the converter system according to the second aspect and its implementation applies accordingly to... Figure 13 The converter system 3 is shown.

[0265] according to Figure 13The converter system 3 includes: an input terminal having two input terminals (IN3, IN4); and two converter units (2a, 2b). The converter system 3 includes an input series connection. In other words, the two converter units (2a, 2b) are connected in series at the input terminal of the converter system 3. According to one embodiment, the converter system 3 may include more than two converter units, wherein the converter units are connected in series at the input terminal of the converter system 3. Figure 13 (Not shown in the image). Regardless of the number of converter units, i.e., whether the converter system includes two converter units (2a, 2b) (as shown in the image). Figure 13 (As shown) or more than two converter units, at least one of the converter units includes an AC / DC converter stage 1 as described in the first aspect and its implementation as described above, as a first converter stage. Specifically, at least one of the converter units of the converter system 3 includes, as described above, at least one of the converter units. Figures 1 to 12 The AC / DC converter stage 1 shown in any of the figures is used as the first converter stage.

[0266] Specifically, each converter unit of the converter system 3 includes an AC / DC converter stage 1 as a first converter stage.

[0267] At least one converter unit of the converter system 3 can be encapsulated in a housing. Figure 13 (Not shown in the image). Specifically, each converter unit of the converter system 3 is encapsulated in a housing. The housing may be a metal housing electrically connected to ground potential. Insulating material, particularly a solid insulating material, may be provided between the encapsulated converter units of the converter system 3.

[0268] The two converter units (2a, 2b) in the converter system 3 can provide an output voltage, especially a DC output voltage, without needing to be electrically connected to each other at the output of the converter system 3. Figure 13 (Not shown in the image). Alternatively, the two converter units (2a, 2b) can be connected in series or in parallel at the output of the converter system 3. Figure 13(Not shown in the image). In other words, the converter system 3 may include an input series output series (ISOS) structure, that is, the two converter units (2a, 2b) are connected in series at the input terminal and in series at the output terminal of the converter system 3. Alternatively, the converter system 3 may include an input series output parallel (ISOP) structure, that is, the two converter units (2a, 2b) are connected in series at the input terminal and in parallel at the output terminal of the converter system 3. The above also applies when the converter system 3 includes more than two converter units. Figure 13 (Not shown in the image).

[0269] The two converter units (2a, 2b) have an AC input voltage input to the converter system 3 at the input terminals (IN3, IN4), and the two converter units (2a, 2b) are connected in series at the input terminals of the converter system 3. Therefore, the input voltage of each converter unit can be corresponding to the input voltage of the converter system divided by the number of converter units in the converter system 3.

[0270] In the case where each converter unit of the converter system 3 includes an AC / DC converter stage 1 as a first converter stage: the higher the AC input voltage configured for the AC / DC converter stage 1, the fewer the number of converter units in the converter system 3.

[0271] The control unit can control the converter unit of the converter system 3. Specifically, the converter system 3 includes the control unit ( Figure 13 (Not shown in the image).

[0272] Figure 14 (a), (b) and (c) each illustrate a converter system provided by an embodiment of the present invention.

[0273] The above is about Figure 13 The description of the converter system shown is accordingly applicable Figure 14 The converter systems shown in (a), (b) and (c) are Figure 14 (a), (b) and (c) show Figure 13 The example implementation of the converter system shown is shown.

[0274] according to Figure 14In the embodiment shown in (a), each of the two converter units (2a, 2b) includes an AC / DC converter stage as a first converter stage. The AC / DC converter stage 1a of converter unit 2a includes a second energy storage device L1 (e.g., an inductor or choke), and thus corresponds to a bipolar boost converter for performing boost operation. The AC / DC converter stage 1b of converter unit 2b does not include such a second energy storage device L1, and therefore is not used by itself for performing boost operation. However, since the two converter units (2a, 2b) are connected in series at the input of the converter system 3, the two converter units (2a, 2b) can be controlled together to perform boost operation using a single second energy storage device L1 of the AC / DC converter stage 1a of converter unit 2a.

[0275] Specifically, Figure 14 The converter system 3 shown in (a) may include two or more converter units. Figure 14 (a) not shown), wherein, in addition to the two converter units (2a, 2b), each other converter unit may include an AC / DC converter stage 1b that does not have a second storage device L1.

[0276] Figure 14 (b) The converter system shown Figure 14 The difference in the converter system shown in (a) is that Figure 14 (b) Each converter unit of the converter system 3 shown includes an AC / DC converter stage 1a with a second energy storage device L1. In other words, according to Figure 4 In the embodiment shown in (b), each converter unit of the converter system 3 includes an AC / DC converter stage 1a, wherein the AC / DC converter stage 1a is a bipolar boost converter. The above relates to... Figure 14 The description of the converter system shown in (a) is accordingly applicable to Figure 14 (b) shows the converter system 3.

[0277] according to Figure 14 (c) In the converter system 3, converter unit 2a of the converter units (2a, 2b) includes at least: an AC / DC converter stage 1 as a first converter stage; and an electrically isolated DC / DC converter stage 4 as a second converter stage, located after the AC / DC converter stage 1. The AC / DC converter stage 1 is used to provide a DC input voltage to the electrically isolated DC / DC converter stage 4.

[0278] The electrically isolated DC / DC converter stage may include a solid-state transformer (SST) that provides the electrical isolation.

[0279] Specifically, according to Figure 4 (c) An optional capacitor C2 may be present between the AC / DC converter stage 1 and the electrically isolated DC / DC converter stage 4 to store the DC output voltage of the AC / DC converter stage 1 and provide the DC input voltage to the electrically isolated DC / DC converter stage 4. The capacitor C2 may correspond to the first storage device of the AC / DC converter stage 1, which is used to provide the DC output voltage of the AC / DC converter stage 1.

[0280] Specifically, each converter unit of the converter system 3 can be implemented as the converter unit 2a.

[0281] Figure 15 A converter system provided by an embodiment of the present invention is shown.

[0282] Figure 15 The converter system 3 shown includes three phase units (5a, 5b, 5c) for an AC input voltage with three phases. Each phase unit of the converter system 3 can be implemented as described above. Figure 13 as well as Figure 14 The converter systems described in (a), (b), and (c) are therefore... Figure 13 as well as Figure 14 The descriptions of the converter systems shown in (a), (b), and (c) are accordingly applicable to Figure 15 Each phase unit of the converter system 3 shown.

[0283] according to Figure 15 The phase unit 5a includes two or more converter units 2 ( Figure 15 Four converter units 2 are shown, and two or more converter units 2 are connected in series at the input terminal of the converter system 3. According to Figure 15 The output terminal of the converter unit 2 of the phase unit 5a is electrically connected in parallel to the output terminal of the converter system 3. Alternatively, the converter units 2 of the phase unit 5a can be connected in series at the output terminals. According to another alternative, each of the converter units 2 of the phase unit 5a can provide an output voltage, especially a DC output voltage, without needing to be electrically connected to each other at the output terminals.

[0284] like Figure 15As shown, each converter unit 2 of the phase unit 5a includes: an AC / DC converter stage 1, serving as a first converter stage; and an electrically isolated DC / DC converter stage 4, serving as a second converter stage. The AC / DC converter stage 1 provides a DC input voltage to the electrically isolated DC / DC converter stage 4. Furthermore, each converter unit 2 includes an optional capacitor between the AC / DC converter stage 1 and the electrically isolated DC / DC converter stage for storing DC voltage. Specifically, the capacitor may correspond to the first storage device of the AC / DC converter stage 1, which provides the DC output voltage of the AC / DC converter stage 1.

[0285] According to one embodiment, only one converter unit 2 of the phase unit 5a (especially the top converter unit 2) includes a second battery L1 in its AC / DC converter stage 1, and is therefore a bipolar boost converter. However, since the converter units 2 of the phase unit 5a are connected in series at the input of the converter system 3, the two converter units 2 can be controlled together to perform boost operation using a single second battery L1 of the AC / DC converter stage 1 of the one converter unit.

[0286] According to another embodiment, the AC / DC converter stage 1 of the plurality of converter units 2 (in particular each converter unit 2) of the phase unit 5a includes the second energy storage L1, and is therefore a bipolar boost converter.

[0287] exist Figure 15 On the right side, an AC / DC converter stage 1 with a full-bridge structure is shown as an example of the AC / DC converter stage of the converter unit 2 of the phase unit 5a of the converter system 3. This AC / DC converter stage 1 substantially corresponds to Figure 7 The only difference in the AC / DC converter stage 1 shown is that... Figure 15 The AC / DC converter stage 1 shown on the right includes a second battery L1 between the first input terminal IN1 and the first connection point N1, and is therefore a bipolar boost converter. The AC / DC converter stage 1 of the converter unit 2 of the phase unit 5a can be implemented in different ways according to the description of the AC / DC converter stage described in the first aspect and its implementations. Specifically, the AC / DC converter stage 1 of the converter unit 2 of the phase unit 5a can correspond to... Figures 1 to 12 Any of the AC / DC converter stages shown.

[0288] The electrically isolated DC / DC converter stage 4 of the converter unit 2 of the phase unit 5a may include a solid-state transformer (SST) that provides the electrical isolation.

[0289] At least one converter unit 2 of the phase unit 5a of the converter system 3 can be encapsulated in a housing. Figure 15 (Not shown in the image). Specifically, each converter unit 2 of the phase unit 5a is encapsulated in a housing. The housing may be a metal housing electrically connected to ground potential. Insulating material, especially a solid insulating material, may be provided between the encapsulated converter units 2 of the phase unit 5a.

[0290] The above description of the phase unit 5a is accordingly applicable to Figure 15 The other two phase units (5b, 5c) of the converter system 3 shown.

[0291] According to one embodiment, the converter system 3 may include only one phase unit, which, as described above, can be implemented together with the phase unit 5a. According to another embodiment, the converter system 3 may include two phase units, which, as described above, can be implemented together with the phase unit 5a.

[0292] According to another embodiment, the converter system 3 may include three or more phase units, each of which may be implemented together with the phase unit 5a as described above.

[0293] The invention has been described in conjunction with various embodiments and implementations as examples. However, based on a study of the drawings, the invention, and the independent claims, those skilled in the art will be able to understand and implement other variations in implementing the claimed invention. In the claims and the description, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. A single element or other unit may fulfill the function of several entities or items recited in the claims. The mere fact that certain measures are described in mutually different dependent claims does not mean that a combination of these measures cannot be used effectively.

Claims

1. An AC / DC converter stage (1) for a converter system (3) having an input series structure, characterized in that, The converter system (3) includes at least two conversion units connected in series at the input of the converter system (3), and at least one of the at least two conversion units includes the AC / DC converter stage (1). The AC / DC converter stage (1) includes: Two input terminals (IN1, IN2) are used to input the AC input voltage (Vin) to the AC / DC converter stage (1). At least one first branch (CB1) has at least two switches (S1, S2) that are connected in series at a first connection point (N1), wherein the first input terminal (IN1) of the two input terminals (IN1, IN2) is electrically connected to the first connection point (N1) of the first branch (CB1). At least one first energy storage device (C1) is used to provide DC output voltage, and the first energy storage device (C1) is connected in parallel to the first branch (CB1). At least one controllable bidirectional switch (BS0) is electrically connected between the two input terminals (IN1, IN2).

2. The AC / DC converter stage (1) according to claim 1, characterized in that, The at least one controllable bidirectional switch (BS0) is used to achieve the zero state of the AC / DC converter stage (1) by providing a low-impedance current path between the two input terminals (IN1, IN2) in its on state.

3. The AC / DC converter stage (1) according to claim 1, characterized in that, The AC / DC converter stage (1) is a bipolar boost converter, including a second battery (L1). One of the two input terminals (IN1, IN2) is electrically connected to the at least one controllable bidirectional switch (BS0) via the second accumulator (L1).

4. The AC / DC converter stage (1) according to claim 3, characterized in that, The at least one controllable bidirectional switch (BS0) is used to achieve the zero state of the AC / DC converter stage (1) by providing a current path between the two input terminals (IN1, IN2) via the second energy storage device (L1) in its on state.

5. The AC / DC converter stage (1) according to claim 3, characterized in that, The first input terminal (IN1) of the two input terminals (IN1, IN2) is electrically connected to the first connection point (N1) of the first branch (CB1) via the second accumulator (L1).

6. The AC / DC converter stage (1) according to any one of claims 1-5, characterized in that, The AC / DC converter stage (1) further includes: a second branch (CB2) having at least two switches (S3, S4) connected in series at a second connection point (N2), wherein the second branch (CB2) is connected in parallel to the first branch (CB1) and the first storage device (C1). The second input terminal (IN2) of the two input terminals (IN1, IN2) is electrically connected to the second connection point (N2) of the second branch (CB2).

7. The AC / DC converter stage (1) according to any one of claims 1-5, characterized in that, The first energy storage device (C1) includes at least two first energy storage elements (C1a, C1b), which are connected in series at a third connection point (N3).

8. The AC / DC converter stage (1) according to claim 7, characterized in that, In the case where the AC / DC converter stage (1) includes only the first branch (CB1), the second input terminal (IN2) of the two input terminals (IN1, IN2) is electrically connected to the third connection point (N3).

9. The AC / DC converter stage (1) according to claim 7, characterized in that, In the case where the AC / DC converter stage (1) includes the first branch (CB1) and the second branch (CB2): The first branch (CB1) includes two or more switches connected in series, and the third connection point (N3) is electrically connected via switches (S15; S16) to at least one connection point (N11; N12) between two switches (S11, S12; S13, S14) of the first branch (CB1) that are different from the first connection point (N1). The second branch (CB2) includes two or more switches connected in series, and the third connection point (N3) is electrically connected via switches (S25; S26) to at least one connection point (N21; N22) between two switches (S21, S22; S23, S24) of the second branch (CB2) that are different from the second connection point (N2).

10. The AC / DC converter stage (1) according to any one of claims 1-5, characterized in that, Any one of the at least two switches includes at least one of the following: At least one uncontrollable unidirectional semiconductor switch; At least one controllable semiconductor switch, the controllable semiconductor switch including an insulated gate bipolar transistor (IGBT).

11. The AC / DC converter stage (1) according to any one of claims 1-5, characterized in that, The at least one controllable bidirectional switch (BS0) includes at least one controllable semiconductor switch.

12. The AC / DC converter stage (1) according to any one of claims 1-5, characterized in that, The AC / DC converter stage (1) includes two controllable bidirectional switches (BS1, BS2) which are connected in series at a fourth connection point (N4) and are used to provide a current path between the two input terminals (IN1, IN2) when they are in the on state.

13. The AC / DC converter stage (1) according to claim 12, characterized in that, In the case where the AC / DC converter stage (1) includes the first branch (CB1) and the second branch (CB2), and where the first storage device (C1) includes at least two first storage device elements (C1a, C1b) connected in series at the third connection point (N3): The third connection point (N3) and the fourth connection point (N4) are electrically connected to each other.

14. The AC / DC converter stage (1) according to claim 12, characterized in that, In the case where the AC / DC converter stage (1) includes only the first branch (CB1): Each switch (S1, S2) of the first branch (CB1) includes: Two uncontrollable unidirectional semiconductor switches (S1a, S1b; S2a, S2b) are connected in series at the fifth connection point (N51; N52); or Two controllable semiconductor switches (S1a, S1b; S2a, S2b) are connected in series at the fifth connection point (N51; N52); or In the case where the AC / DC converter stage (1) includes the first branch (CB1) and the second branch (CB2): Each switch (S1, S2, S3, S4) of the first branch (CB1) and the second branch (CB2) includes: Two uncontrollable unidirectional semiconductor switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) are connected in series at the fifth connection point (N51; N52; N53; N54); or Two controllable semiconductor switches (S1a, S1b; S2a, S2b; S3a, S3b; S4a, S4b) are connected in series at the fifth connection point (N51; N52; N53; N54).

15. The AC / DC converter stage (1) according to claim 14, characterized in that, In the case where the first storage device (C1) includes at least two first storage device elements (C1a, C1b) connected in series at the third connection point (N3): Each switch (S1; S2; S3; S4) includes a slow recovery diode (D1b; D2a; D3b; D4a) and a fast recovery diode (D1a; D2b; D3a; D4b), wherein the slow recovery diode (D1b; D2a; D3b; D4a) and the fast recovery diode (D1a; D2b; D4a) are... D3a; D4b) are connected in series at the fifth connection point (N51; N52; N53; N54), wherein, for each switch (S1; S2; S3; S4), a low-current diode (D1c; D2c; D3c; D4c) for providing recovery charge is connected between the fifth connection point (N51; N52; N53; N54) and the third connection point (N3); or Each switch (S1; S2; S3; S4) includes two controllable semiconductor switches (Q1a, Q1b; Q2a, Q2b; Q3a, Q3b; Q4a, Q4b), which are connected in series at the fifth connection point (N51; N52; N53; N54). For each switch (S1; S2; S3; S4), a low-current diode (D1c; D2c; D3c; D4c) is used to ensure that the voltage drop at the two controllable semiconductor switches (Q1a, Q1b; Q2a, Q2b; Q3a, Q3b; Q4a, Q4b) is equal, which is electrically connected between the fifth connection point (N51; N52; N53; N54) and the third connection point (N3).

16. A converter system (3) having an input series structure, characterized in that, include: At least two converter units (2a, 2b) are connected in series at the input of the converter system (3); Wherein, at least one of the at least two converter units (2a, 2b) includes an AC / DC converter stage (1) according to any one of claims 1 to 15, as a first converter stage.

17. The converter system (3) according to claim 16, characterized in that, One of the at least two converter units (2a, 2b) includes an AC / DC converter stage (1a) with a second energy storage device (L1), and the other converter unit (2b) includes an AC / DC converter stage (1b) without a second energy storage device; or Each of the at least two converter units (2a, 2b) includes an AC / DC converter stage (1) according to any one of claims 1 to 15, as a first converter stage.

18. The converter system (3) according to claim 16 or 17, characterized in that, At least one of the at least two converter units (2a, 2b) includes an electrically isolated DC / DC converter stage (4) as a second converter stage; The corresponding AC / DC converter stage (1) is used to provide DC input voltage to the isolated DC / DC converter stage (4).

19. The converter system (3) according to claim 16 or 17, characterized in that, At least one of the at least two converter units (2a, 2b) is encapsulated in a housing.

20. The converter system (3) according to claim 16 or 17, characterized in that, The converter system (3) includes at least one phase unit (5a, 5b, 5c) for AC input voltage. Each phase unit (5a, 5b, 5c) includes at least two converter units (2, 2a, 2b), which are connected in series at the input of the converter system (3).

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