An isolated AC-DC converter, charging equipment and power system

Abstract

This application discloses an isolated AC-DC converter, charging device, and power supply system, comprising: an input terminal of a PFC filter connected to AC power; an input terminal of a PFC circuit connected to the output terminal of the PFC filter; and an output terminal of the PFC circuit connected to the input terminal of a DC-DC circuit. The DC-DC circuit includes a transformer, which comprises a primary winding, a secondary winding, and a first shielding layer. The first shielding layer is disposed between the primary and secondary windings and is connected to the PFC filter, blocking interference signals from being transmitted to the secondary winding. This avoids interference sources from being transmitted to the secondary winding through the primary winding of the transformer. The interference signal from the primary winding is transmitted back to the PFC filter through the first shielding layer, forming a common-mode loop, thus blocking interference signals from being transmitted to the secondary winding. This solution does not require an additional EMC filter; adding a shielding layer is easy to implement, and the size and volume do not increase significantly.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to an isolated AC-DC converter, charging equipment, and power supply system. Background Technology

[0002] Currently, isolated ACDC converters adopt a two-stage architecture, with the front stage being a PFC circuit with rectification function and the back stage being an isolated DCDC circuit, which includes a transformer.

[0003] In practical applications, the primary and secondary windings of a transformer may be connected in parallel with capacitors, or there may be coupling capacitors between the primary and secondary windings. Interference sources generated by the PFC circuit can be transmitted to the secondary winding of the transformer through the capacitors, thereby forming a large common-mode loop channel, which leads to a decrease in the EMC performance of the isolated AC-DC converter.

[0004] To improve EMC performance, an AC EMC filter is added before the PFC circuit to increase common-mode impedance. However, to meet EMC standards, the added filter impedance in the PFC circuit is very high; in applications where the output needs to pass EMC standards, a high-impedance filter unit is also required for the DC output, such as... Figure 2 The proposed solution illustrates this. High-impedance EMC filter units inevitably lead to drawbacks such as increased cost, size, and weight. Summary of the Invention

[0005] To address the above technical issues, this application provides an isolated AC-DC converter, charging device, and power system that can improve EMC performance without increasing the size and weight of the converter.

[0006] This application provides an isolated AC-DC converter, including: a PFC filter, a PFC circuit, and a DC-DC circuit;

[0007] The input terminal of the PFC filter is used to connect to AC power;

[0008] The input terminal of the PFC circuit is connected to the output terminal of the PFC filter;

[0009] The output of the PFC circuit is connected to the input of the DC-DC circuit.

[0010] A DC-DC circuit includes a transformer, which includes a primary winding, a secondary winding, and a first shielding layer.

[0011] The first shielding layer is placed between the primary winding and the secondary winding. The first shielding layer is connected to the PFC filter to form a common-mode circuit, blocking interference signals from being transmitted to the secondary winding.

[0012] Preferably, the PFC filter includes a filter capacitor and a filter inductor;

[0013] The input terminal of the PFC circuit is connected to the first terminal of the filter inductor, the second terminal of the filter inductor is connected to the first terminal of the filter capacitor, and the second terminal of the filter capacitor is connected to the first shielding layer.

[0014] Preferably, the PFC filter includes a filter capacitor and a filter inductor;

[0015] The input terminal of the PFC circuit is connected to the first terminal of the filter inductor, the second terminal of the filter inductor is connected to the first terminal of the filter capacitor, and the second terminal of the filter inductor is connected to the first shielding layer.

[0016] Preferably, it further includes: a second shielding layer;

[0017] The second shielding layer is disposed between the primary winding and the first shielding layer. The second shielding layer is connected to the DC bus of the DC-DC circuit and is used to suppress interference signals from the switching transistors of the primary winding of the DC-DC circuit.

[0018] Preferably, it further includes: a third shielding layer;

[0019] The third shielding layer is located between the secondary winding and the first shielding layer, and is connected to one end of the output capacitor of the DC-DC circuit.

[0020] Preferably, the first shielding layer is a copper foil located between the primary winding and the secondary winding, and one end of the copper foil is connected to the PFC filter through an electrical connection line.

[0021] Preferably, the isolated AC-CDC converter is a three-phase converter or a single-phase converter.

[0022] Preferably, the input terminal of the PFC circuit is used to connect to a three-phase AC power supply, and the PFC circuit includes a three-level circuit or a two-level circuit;

[0023] The DC-DC circuit includes a DC-AC inverter bridge, a transformer, and an AC-DC rectifier bridge. The input of the DC-AC inverter bridge is connected to the output of the PFC circuit, the primary winding of the transformer is connected to the output of the DC-AC inverter bridge, and the secondary winding of the transformer is connected to the input of the AC-DC rectifier bridge.

[0024] This application also provides a charging device, including the isolated AC-DC converter described above; and further including: a controller;

[0025] The controller is used to control the output of the isolated AC-DC converter to charge the electrical equipment.

[0026] This application also provides a power supply system, including the isolated AC-DC converter described above; and further including: a controller; the controller being used to control the output of the isolated AC-DC converter to supply power to electrical equipment.

[0027] Therefore, this application has the following beneficial effects:

[0028] The isolated AC-DC converter provided in this application includes: a PFC filter, a PFC circuit, and a DC-DC circuit; the input terminal of the PFC filter is used to connect to AC power; the input terminal of the PFC circuit is connected to the output terminal of the PFC filter; the output terminal of the PFC circuit is connected to the input terminal of the DC-DC circuit; the DC-DC circuit includes a transformer, which includes: a primary winding, a secondary winding, and a first shielding layer; the first shielding layer is disposed between the primary winding and the secondary winding, and is connected to the PFC filter to form a common-mode loop, reducing the common-mode current in the PFC circuit caused by the coupling capacitance between the primary and secondary windings of the transformer, and preventing interference signals from being transmitted to the secondary winding. This application does not specifically limit the specific location where the first shielding layer is connected to the PFC filter; for example, it can be connected to one end of the filter capacitor in the PFC filter, or it can be directly connected to a phase line of the AC input. Since the PFC filter generates interference, this application aims to prevent the interference source from being transmitted from the primary winding of the transformer to the secondary winding. Instead, the interference signal from the primary winding of the transformer is transmitted back to the PFC filter through the first shielding layer, thereby forming a common-mode loop and blocking the transmission of the interference signal to the secondary winding. This solution does not require an additional EMC filter, only an additional shielding layer, which is easy to implement and does not significantly increase the size or volume. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an isolated AC-DC converter;

[0030] Figure 2 A schematic diagram of an isolated AC-DC converter with an EMC filter;

[0031] Figure 3 A schematic diagram of an isolated AC-DC converter provided in an embodiment of this application;

[0032] Figure 4 for Figure 3 A circuit diagram of a specific isolated AC-CDC converter;

[0033] Figure 5 An equivalent circuit diagram provided for an embodiment of this application;

[0034] Figure 6 A schematic diagram of another isolated AC-DC converter provided in the embodiments of this application;

[0035] Figure 7 A schematic diagram of another isolated AC-DC converter provided in the embodiments of this application;

[0036] Figure 8A schematic diagram of yet another isolated AC-DC converter provided in the embodiments of this application;

[0037] Figure 9 A schematic diagram of another isolated AC-DC converter provided in the embodiments of this application;

[0038] Figure 10 A schematic diagram of a PFC circuit provided in an embodiment of this application;

[0039] Figure 11 A schematic diagram of yet another PFC circuit provided in an embodiment of this application;

[0040] Figure 12 A schematic diagram of another PFC circuit provided in an embodiment of this application;

[0041] Figure 13 This is a schematic diagram of a charging device provided in an embodiment of this application;

[0042] Figure 14 This is a schematic diagram of a power supply system provided in an embodiment of this application. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions provided in this application, specific application scenarios will be introduced below.

[0044] The isolated AC-CDC converter provided in this application can be applied in many situations, such as communication power supplies, specifically for powering computer rooms; it can also be applied to on-board chargers and charging piles. This application does not specifically limit the load type corresponding to this isolated AC-CDC converter.

[0045] The isolated AC-CDC converter provided in this application embodiment can be three-phase or single-phase. The following description takes the isolated AC-CDC converter as a three-phase converter as an example.

[0046] See Figure 1 The figure shows a schematic diagram of an isolated AC-DC converter.

[0047] The isolated AC-DC converter provided in this application includes two stages: the first stage is a PFC circuit 100, and the second stage is a DC-DC circuit 200. The DC-DC circuit 200 is isolated, that is, it includes a transformer T. The primary winding of the transformer T is connected to a switching transistor to form a DC-AC inverter bridge, and the secondary winding of the transformer T is connected to a switching transistor to form an AC-DC rectifier bridge.

[0048] Because interference generated by the PFC circuit can be transmitted to the secondary winding of transformer T through the capacitance or coupling capacitor of transformer T, causing common-mode interference, the EMC performance of the entire isolated AC-DC converter degrades. Generally, to improve EMC performance, such as... Figure 2 The isolated AC-DC converter shown typically adds an AC EMC filter 400 at the input of the PFC filter 300 before the PFC circuit 100. Sometimes, a DC EMC filter 500 is also added at the output of the DC-DC circuit 200. Since EMC filters generally include inductors, this results in a larger overall circuit size, increased weight, and higher cost. The PFC filter 300 is a differential-mode filter, primarily used to filter out differential-mode interference.

[0049] The isolated AC-DC converter provided in this application does not add an EMC filter. Instead, a shielding layer is added between the primary and secondary windings of the transformer to shield the interference source of the PFC circuit and prevent interference signals from being transmitted through the transformer to the secondary winding of the transformer and the circuit of the secondary winding, thereby affecting the load.

[0050] The isolated AC-DC converter provided in the embodiments of this application is described in detail below with reference to the accompanying drawings.

[0051] See Figure 3 The figure is a schematic diagram of an isolated AC-DC converter provided in an embodiment of this application.

[0052] The isolated ACDC converter provided in this embodiment includes: a PFC filter 300, a PFC circuit 100, and a DC-DC circuit 200;

[0053] The input terminal of the PFC filter 300 is used to connect to AC power;

[0054] The input terminal of PFC circuit 100 is connected to the output terminal of PFC filter 300;

[0055] The output of PFC circuit 100 is connected to the input of DC-DC circuit 200;

[0056] The DC-DC circuit 200 includes a transformer T, which includes a primary winding, a secondary winding, and a first shielding layer 10.

[0057] This application does not specifically limit the specific implementation of the rectifier circuit and inverter circuit inside the DC-DC circuit 200; it can be a full-bridge circuit or a half-bridge circuit, etc. This embodiment specifically uses the DC-DC circuit 200, which includes a DCAC inverter 201 and an AC-DC rectifier 202, as an example for description.

[0058] The first shielding layer 10 is disposed between the primary winding and the secondary winding. The first shielding layer 10 is connected to the PFC filter 300 to form a common-mode circuit, blocking interference signals from being transmitted to the secondary winding.

[0059] The embodiments of this application do not specifically limit the specific material of the first shielding layer 10, but may be materials with conductive properties such as copper foil.

[0060] This application does not specifically limit the exact location where the first shielding layer 10 connects to the PFC filter 300. For example, it can be connected to one end of the filter capacitor in the PFC filter 300. Since the PFC filter 300 generates interference, to prevent the interference from being transmitted from the primary winding of the transformer T to the secondary winding, this application transmits the interference signal from the primary winding of the transformer T back to the PFC filter 300 through the first shielding layer 10, thereby forming a common-mode loop and blocking the transmission of the interference signal to the secondary winding. This application does not specifically limit the exact location where the first shielding layer connects to the PFC filter. For example, it can be connected to one end of the filter capacitor in the PFC filter, or it can be directly connected to a phase line of the AC input. This solution does not require an additional EMC filter; only one shielding layer is added, making it easy to implement, and the size and volume do not increase significantly.

[0061] The secondary winding of transformer T is connected to ACCDC rectifier 202, and the secondary winding of ACCDC rectifier bridge 202 outputs DC power to supply power to the load.

[0062] Figure 4 The isolated AC-DC converter shown is Figure 3 One specific implementation method,

[0063] Figure 4 The following introduction uses a three-phase isolated AC-CDC converter as an example. It should be understood that an isolated AC-CDC converter can also be single-phase.

[0064] Figure 4 The filtering circuit in the circuit includes three filter capacitors C and three filter inductors L.

[0065] The input terminal of the PFC circuit is connected to the first terminal of the filter inductor L, the second terminal of the filter inductor L is connected to the first terminal of the filter capacitor C, and the second terminal of the filter capacitor C is connected to the first shielding layer 10.

[0066] The following is combined with Figure 5 The working principle of the isolated AC-DC converter provided in the embodiments of this application is introduced.

[0067] See Figure 5 This figure is an equivalent circuit diagram provided in an embodiment of this application.

[0068] The first capacitor C1 is the coupling capacitance between the primary winding of the transformer and the first shielding layer, typically in the tens of pF range. The second capacitor C2 is the coupling capacitance between the first shielding layer and the secondary winding of the transformer. Ld is the equivalent inductance of the PFC filter, while Cd is the equivalent capacitance of the PFC filter, typically in the microsecond (µF) range. The PFC filter primarily filters out differential-mode signals; therefore, Ld can be called the differential-mode inductance, and Cd can be called the differential-mode capacitance.

[0069] Vd is the interference source generated by the PFC circuit. According to the voltage divider principle, the voltage drop across points A and B from the interference source Vd is very low. If Ld is not considered, the difference between the uF-level Cd and the tens of pF-level C1 is five orders of magnitude. Therefore, the voltage component of the interference source leaking from the isolated AC-DC converter is only one ten-thousandth of the original interference source, reducing the interference from the interference source to the transformer secondary side. Simultaneously, because C1 is a pF-level capacitor, the interference current generated by Vd in the circuit is suppressed, mitigating the risk caused by excessive interference current.

[0070] Figure 4 The second end of the first shielding layer 10 is connected to the capacitor of the PFC filter. Alternatively, the first shielding layer can also be directly connected to the phase line of one phase of the AC input.

[0071] See Figure 6 This figure is a schematic diagram of another isolated AC-DC converter provided in an embodiment of this application.

[0072] Figure 6 and Figure 4 The difference is that the second end of the first shielding layer 10 is connected at a different position.

[0073] A PFC filter includes a filter capacitor C and a filter inductor L;

[0074] The input terminal of the PFC circuit is connected to the first terminal of the filter inductor L, the second terminal of the filter inductor L is connected to the first terminal of the filter capacitor C, and the second terminal of the filter inductor L is connected to the first shielding layer 10.

[0075] The above embodiments describe Figure 4 and Figure 6 The first shielding layer in all transformers can reduce interference from sources to the secondary circuit. The second end of the first shielding layer can be connected to a static point, thus diverting the interference source back to the static point, reducing the current in the interference loop and protecting the circuit components. This can be achieved simply by connecting one end of the first shielding layer to a PFC filter or its input terminal.

[0076] In addition, in order to suppress the interference caused by the primary-side switching transistor of the DC-DC circuit, a second shielding layer can be added to the transformer in this embodiment of the application. The following is a detailed description in conjunction with the accompanying drawings.

[0077] See Figure 7 This figure is a schematic diagram of another isolated AC-DC converter provided in an embodiment of this application.

[0078] The isolated AC-DC converter provided in this embodiment further includes: a second shielding layer 20;

[0079] The second shielding layer 20 is disposed between the primary winding and the first shielding layer 10. The second shielding layer 20 is connected to the DC bus of the DC-DC circuit and is used to suppress interference signals from the primary switching transistor of the DC-DC circuit.

[0080] The embodiments of this application do not specifically limit the material of the second shielding layer 20, for example, it can be the same as the material of the first shielding layer.

[0081] Specifically, in one possible implementation, the second end of the second shielding layer 20 can be connected to the negative terminal of the DC bus of the DCDC circuit, that is, when the interference signal generated by the switching transistor in the DCDC circuit is diverted back to the DC bus at the input terminal of the DCDC circuit. It should be understood that the first shielding layer 10 can also isolate the interference of the primary winding of the DCDC circuit to the secondary winding to a certain extent, that is, suppress the interference signal of the primary winding of the DCDC circuit within the primary winding loop. However, the second shielding layer 20 added in this embodiment can better reduce the interference signal generated by the primary switching transistor of the DCDC circuit, reduce the number of devices affected by the interference signal and the area enclosed, and further reduce the interference signal of the isolated ACDC converter.

[0082] In addition, in order to suppress the influence of the secondary switching transistor of the isolated DC-DC circuit on the primary winding of the transformer, a third shielding layer can be added in the embodiments of this application. The third shielding layer is connected to a certain point of the output capacitor of the secondary winding of the transformer, and the third shielding layer is located between the secondary winding and the first shielding layer.

[0083] See Figure 8 This figure is a schematic diagram of another isolated AC-DC converter provided in the embodiments of this application.

[0084] The isolated AC-DC converter provided in this embodiment also includes: a third shielding layer 30;

[0085] The third shielding layer 30 is disposed between the secondary winding and the first shielding layer 10. The third shielding layer 30 is connected to one end of the output capacitor of the DC-DC circuit, that is, to the output terminal of the rectifier connected to the secondary winding of the transformer in the DC-DC circuit. Figure 8Taking the negative output terminal of the rectifier as an example, since the output capacitor is connected to the output terminal of the rectifier, the second end of the third shielding layer 30 is also connected to one end of the output capacitor. The negative output terminal of the rectifier is also a static point. Introducing the interference signal into the static point can effectively reduce the influence of the rectifier tube in the rectifier on the primary winding of the transformer.

[0086] Figure 8 The diagram only illustrates the use of the first shielding layer 10 and the third shielding layer 30 together. It should be understood that all three shielding layers can be used together. See [link / reference]. Figure 9 This figure is a schematic diagram of another isolated AC-DC converter provided in an embodiment of this application.

[0087] Figure 9 The diagram shows the combined use of the first shielding layer 10, the second shielding layer 20, and the third shielding layer 30, which can shield against interference from the PFC filter, as well as interference from the primary-side switching transistors and the secondary-side switching transistors of the DC-DC circuit.

[0088] The above embodiments of this application are described using a PFC circuit as a half-bridge circuit. In addition, the PFC circuit can also be other types of circuits, and is not limited to a two-level circuit or a three-level circuit.

[0089] See Figure 10 The figure shows a three-level PFC circuit. Figure 10 The four switching transistors Q1-Q4 in the circuit are all controllable switching transistors. It should be understood that Q1 and Q4 can also be diodes. Figure 10 The circuit shown is a type I circuit; it can also be a type T three-level circuit, see [link / reference]. Figure 11 , Figure 11 It includes four controllable switching transistors; it should be understood that Q1 and Q2 can be replaced with diodes. Additionally, the PFC circuit can also provide... Figure 12 The circuit shown is an example of this.

[0090] Based on the isolated AC-DC converter provided in the above embodiments, this application also provides a charging device, which will be described in detail below with reference to the accompanying drawings.

[0091] See Figure 13 This figure is a schematic diagram of a charging device provided in an embodiment of this application.

[0092] The charging device 1000 provided in this embodiment includes any of the isolated AC-DC converters 2000 described in the above embodiments; it also includes a controller 3000.

[0093] The controller 3000 is used to control the output of the isolated AC-DC converter to charge the electrical equipment.

[0094] Because the charging device provided in this application embodiment can better shield interference signals, it can provide higher quality power to the load.

[0095] For example, the charging device can be a charging station or an on-board charger. When the charging device is a charging station, the input is AC and the output is DC, used to charge electric vehicles.

[0096] When the charging device is an on-board charger, it can charge the car while it is in motion, such as on buses and trolleybuses.

[0097] The embodiments of this application are not specifically limited. The input voltage of the charging device can be selected according to the actual needs of the scenario, and the specific number of phases is not limited. It can be single-phase or three-phase.

[0098] See Figure 14 The figure is a schematic diagram of a power supply system provided in an embodiment of this application.

[0099] This application embodiment also provides a power supply system 1100, including any of the isolated ACDC converters 2000 described in the above embodiments; and also includes: a controller 3000;

[0100] The controller 3000 is used to control the output of the isolated AC-DC converter to supply power to the electrical equipment.

[0101] For example, electrical equipment can be the load in a computer room, such as the air conditioner, servers, or the load in a data center. Electrical equipment can also be communication equipment.

[0102] Because the power system provided in this application embodiment can better shield interference signals, it can provide higher quality power to the load.

[0103] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An isolated AC-DC converter, characterized by, The application relates to an isolated ACDC converter. The PFC filter, the PFC circuit and the DCDC circuit are included. The input end of the PFC filter is used for connecting AC power. The input end of the PFC circuit is connected with the output end of the PFC filter. The output end of the PFC circuit is connected with the input end of the DCDC circuit. The DCDC circuit includes a transformer, and the transformer includes a primary winding, a secondary winding and a first shielding layer. The first shielding layer is arranged between the primary winding and the secondary winding, the first shielding layer is connected with the PFC filter to form a common mode loop, and interference signals, including interference sources generated by the PFC circuit, are blocked from being transmitted to the secondary winding.

2. An isolated ACDC converter according to claim 1, characterized in that The PFC filter includes a filter capacitor and a filter inductor. The input end of the PFC circuit is connected with the first end of the filter inductor, the second end of the filter inductor is connected with the first end of the filter capacitor, and the second end of the filter capacitor is connected with the first shielding layer.

3. The isolated ACDC converter of claim 1, wherein, The PFC filter includes a filter capacitor and a filter inductor. The input end of the PFC circuit is connected with the first end of the filter inductor, the second end of the filter inductor is connected with the first end of the filter capacitor, and the second end of the filter inductor is connected with the first shielding layer.

4. An isolated ACDC converter according to any of claims 1-3, characterized in that Further included are: A second shielding layer. The second shielding layer is arranged between the primary winding and the first shielding layer, the second shielding layer is connected with a DC bus of the DCDC circuit, and the second shielding layer is used for inhibiting interference signals of a switch tube of the primary winding of the DCDC circuit.

5. The isolated ACDC converter of any of claims 1-3, wherein, Further included are: A third shielding layer. The third shielding layer is arranged between the secondary winding and the first shielding layer, and the third shielding layer is connected with one end of an output capacitor of the DCDC circuit.

6. The isolated ACDC converter of any of claims 1-3, wherein, The first shielding layer is a copper foil located between the primary winding and the secondary winding, and one end of the copper foil is connected with the PFC filter through an electric connection line.

7. The isolated ACDC converter of any of claims 1-3, wherein, The isolated ACDC converter is a three-phase converter or a single-phase converter.

8. The isolated ACDC converter of any of claims 1-3, wherein, The input end of the PFC circuit is used for connecting three-phase AC power, and the PFC circuit includes a three-level circuit or a two-level circuit. The DCDC circuit includes a DCAC inverter bridge, a transformer and an ACDC rectifier bridge, the input end of the DCAC inverter bridge is connected with the output end of the PFC circuit, the primary winding of the transformer is connected with the output end of the DCAC inverter bridge, and the secondary winding of the transformer is connected with the input end of the ACDC rectifier bridge.

9. A charging device, characterized by The isolated ACDC converter includes the isolated ACDC converter in any one of claims 1-8, and further includes a controller. The controller is used for controlling the output end of the isolated ACDC converter to charge a power utilization device.

10. A power supply system characterized by comprising: The isolated ACDC converter includes the isolated ACDC converter in any one of claims 1-8, and further includes a controller. The controller is used for controlling the output end of the isolated ACDC converter to supply power to a power utilization device.

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