Power output circuit, power equipment and power supply system

Abstract

The utility model relates to a power supply output circuit, power supply equipment and a power supply system, the power supply output circuit comprises a first DC / DC unit, a second DC / DC unit, an EMC filtering unit and an output port, the first DC / DC unit is connected with the second DC / DC unit in series and outputs a first DC voltage through the output port, or the first DC / DC unit is connected with the second DC / DC unit in parallel and outputs a second DC voltage through the EMC filtering unit. And the EMC filtering unit is electrically connected with the output port, and the EMC filtering unit is used for filtering the first direct-current voltage or the second direct-current voltage. Therefore, the power output circuit adopts the EMC filtering unit to filter the first direct current voltage or the second direct current voltage and reduce high-frequency noise, and compared with a scheme adopting two EMC filtering units, the power output circuit adopts one EMC filtering unit to filter, the EMC filtering effect is improved, and the cost is lower.

Description

Technical Field

[0001] The utility model relates to the field of power output, in particular to a power output circuit, a power supply device and a power supply system. Background Art

[0002] The power output circuit includes a DC / DC unit. The DC / DC unit boosts or buck-converts electric energy to provide a suitable supply voltage for a load. By connecting the DC / DC units in series or in parallel, different DC voltages can be output compatibly. Since the DC / DC unit generates electromagnetic interference (EMI) during operation, in order to reduce EMI, an EMC filter circuit can be used to eliminate the interference signals input on the signal line and various induced interferences.

[0003] In a traditional power output circuit, each DC / DC unit corresponds to an EMC filter circuit. The DC voltage output by the DC / DC unit is filtered by each EMC filter circuit to filter out the common-mode noise signals. However, the wiring and distributed parameters of each EMC filter circuit may be different, resulting in differences in electromagnetic noise, power ripple, etc., and circuit imbalance. In addition, each EMC filter circuit is placed in parallel and side by side, and the magnetic flux of the common-mode inductor is coupled, resulting in poor filtering effect. The common-mode noise signal may also only pass through one EMC filter circuit, causing the inductance of the common-mode inductor to be halved compared to the expected inductance, resulting in poor filtering effect. Summary of the Utility Model

[0004] Embodiments of the utility model aim to provide a power output circuit, a power supply device and a power supply system, which can improve the EMC filtering effect and reduce the cost.

[0005] To solve the above technical problems, the embodiments of the utility model provide the following technical solutions:

[0006] In a first aspect, an embodiment of the utility model provides a power output circuit, including: a first DC / DC unit, a second DC / DC unit, an EMC filter unit and an output port;

[0007] The first DC / DC unit is connected in series with the second DC / DC unit and outputs a first DC voltage through the output port. Alternatively, the first DC / DC unit is connected in parallel with the second DC / DC unit and outputs a second DC voltage through the output port;

[0008] The EMC filter unit is electrically connected to the output port and is used for filtering the first DC voltage or the second DC voltage.

[0009] In some embodiments, the positive output terminal of the first DC / DC unit is electrically connected to the first input terminal of the EMC filtering unit, the negative output terminal of the first DC / DC unit is electrically connected to the second input terminal of the EMC filtering unit, the positive output terminal of the second DC / DC unit is electrically connected to the third input terminal of the EMC filtering unit, the negative output terminal of the second DC / DC unit is electrically connected to the fourth input terminal of the EMC filtering unit, the first output terminal of the EMC filtering unit is electrically connected to the first positive input terminal of the output port, the second output terminal of the EMC filtering unit is electrically connected to the first negative input terminal of the output port, the third output terminal of the EMC filtering unit is electrically connected to the second positive input terminal of the output port, the fourth output terminal of the EMC filtering unit is electrically connected to the second negative input terminal of the output port, and the output terminal of the output port is used to output the first DC voltage or the second DC voltage.

[0010] In some embodiments, the EMC filtering unit includes a first winding, a second winding, a third winding, and a fourth winding, and the first winding, the second winding, the third winding, and the fourth winding are wound around the same iron core;

[0011] The positive output terminal of the first DC / DC unit is electrically connected to the first positive input terminal of the output port through the first winding;

[0012] The negative output terminal of the first DC / DC unit is electrically connected to the first negative input terminal of the output port through the second winding;

[0013] The positive output terminal of the second DC / DC unit is electrically connected to the second positive input terminal of the output port through the third winding;

[0014] The negative output terminal of the second DC / DC unit is electrically connected to the second negative input terminal of the output port through the fourth winding.

[0015] In some embodiments, the magnetic field directions generated by the common-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the first winding, the second winding, the third winding, and the fourth winding are the same;

[0016] The magnetic field directions generated by the differential-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the first winding, the second winding, the third winding, and the fourth winding are opposite.

[0017] In some embodiments, the third input terminal of the EMC filtering unit is connected to the first positive output terminal of the output port, the fourth input terminal of the EMC filtering unit is connected to the first negative output terminal of the output port, and the output terminal of the EMC filtering unit is configured to output the first DC voltage or the second DC voltage.

[0018] In some embodiments, the EMC filtering unit includes a fifth winding and a sixth winding, and the fifth winding and the sixth winding are wound around the same iron core;

[0019] The positive output terminal of the output port is electrically connected to one end of the fifth winding, the negative output terminal of the output port is electrically connected to one end of the sixth winding, and the other ends of the fifth winding and the sixth winding are both configured to output the first DC voltage or the second DC voltage.

[0020] In some embodiments, the magnetic field directions generated by the common-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the fifth winding and the sixth winding are the same;

[0021] The magnetic field directions generated by the differential-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the fifth winding and the sixth winding are opposite.

[0022] In some embodiments, the shape of the iron core includes one of a ring shape, a U shape, and an E shape.

[0023] In a second aspect, an embodiment of the present invention provides a power supply device, including an external power supply and the power output circuit as described above, wherein the external power supply is electrically connected to the first DC / DC unit and the second DC / DC unit respectively.

[0024] In a third aspect, an embodiment of the present invention provides a power supply system, including a load and the power supply device as described above, wherein the first DC voltage or the second DC voltage is used to supply power to the load.

[0025] In various embodiments of the present utility model, the power output circuit includes a first DC / DC unit, a second DC / DC unit, an EMC filtering unit, and an output port. Among them, the first DC / DC unit and the second DC / DC unit are connected in series and output a first DC voltage through the output port, or the first DC / DC unit and the second DC / DC unit are connected in parallel and output a second DC voltage through the output port. The EMC filtering unit is electrically connected to the output port, and the EMC filtering unit filters the first DC voltage or the second DC voltage. Therefore, the power output circuit uses the EMC filtering unit to filter the first DC voltage or the second DC voltage, reducing high-frequency noise. And compared with the solution of using two EMC filtering units, the power output circuit uses one EMC filtering unit for filtering, improving the EMC filtering effect and having a lower cost. Description of the Drawings

[0026] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0027] Figure 1 is a schematic structural diagram of one of the power supply systems provided by an embodiment of the present utility model;

[0028] Figure 2 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0029] Figure 3 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0030] Figure 4 is a schematic structural diagram of one of the power output circuits in the related art;

[0031] Figure 5 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0032] Figure 6 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0033] Figure 7 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0034] Figure 8 is a schematic structural diagram of one of the power output circuits provided by an embodiment of the present utility model;

[0035] Figure 9aIt is a schematic diagram of the EMC test results of the related technology;

[0036] Figure 9b It is a schematic diagram of the EMC test results of the power output circuit provided by the embodiment of the present application. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0038] Please refer to Figure 1 , Figure 1 It is a power supply system provided by the embodiment of the present utility model. As Figure 1 shown, the power supply system includes a power supply device 100 and a load 200. Among them, the power supply device 100 includes an external power supply 20 and a power output circuit 10.

[0039] The power output circuit 10 is electrically connected to the external power supply 20 and the load 200 respectively. The power output circuit 10 converts the electric energy output by the external power supply 20 and supplies the converted electric energy to the load 200. If the external power supply 20 provides AC electric energy, the power output circuit 10 converts the AC electric energy into DC electric energy, and boosts or buck-boosts the DC electric energy, and supplies the boosted or buck-boosted DC electric energy to the load 200. If the external power supply 20 provides DC electric energy, the power output circuit 10 boosts or buck-boosts the DC electric energy, and supplies the boosted or buck-boosted DC electric energy to the load 200.

[0040] In some embodiments, as Figure 2 shown, the power output circuit 10 further includes a first DC / DC unit 11, a second DC / DC unit 12 and an output port 13. The first DC / DC unit 11 is connected in series with the second DC / DC unit 12 and outputs a first DC voltage through the output port 13. Or, as Figure 3 shown, the first DC / DC unit 11 is connected in parallel with the second DC / DC unit 12 and outputs a second DC voltage through the output port 13. The output port 13 is electrically connected to the load 200, so that the first DC voltage or the second DC voltage supplies power to the load 200.

[0041] The power output circuit 10 is a circuit that is compatible with outputting two DC voltages. When it is necessary to output the first DC voltage, the first DC / DC unit 11 is connected in series with the second DC / DC unit 12. When it is necessary to output the second DC voltage, the first DC / DC unit 11 is connected in parallel with the second DC / DC unit 12.

[0042] The output port 13 includes four terminals, two positive and two negative, to achieve series and parallel connection of the first DC / DC unit 11 and the second DC / DC unit 12. Specifically, the output port 13 includes a first positive input terminal, a first negative input terminal, a second positive input terminal, and a second negative input terminal. The positive output terminal of the first DC / DC unit 11 is electrically connected to the first positive input terminal of the output port 13, the negative output terminal of the first DC / DC unit 11 is electrically connected to the first negative input terminal of the output port 13, the positive output terminal of the second DC / DC unit 12 is electrically connected to the second positive input terminal of the output port 13, and the negative output terminal of the second DC / DC unit 12 is electrically connected to the second negative input terminal of the output port 13.

[0043] As Figure 2 shown, when it is necessary to output the first DC voltage, connect the first negative input terminal of the output port 13 to its second positive input terminal, so that the first DC / DC unit 11 and the second DC / DC unit 12 are connected in series, and the output port 13 outputs the first DC voltage externally. As Figure 3 shown, when it is necessary to output the second DC voltage, connect the first positive input terminal of the output port 13 to its second positive input terminal, and connect the first negative input terminal of the output port 13 to its second negative input terminal, so that the first DC / DC unit 11 and the second DC / DC unit 12 are connected in parallel, and the output port 13 outputs the second DC voltage externally.

[0044] Moreover, since the first DC / DC unit 11 and the second DC / DC unit 12 will generate electromagnetic interference (EMI) during operation, in order to reduce EMI, an EMC filter circuit can be used to eliminate the interference signals input on the signal line and various induced interferences. On the one hand, the EMC filter circuit needs to filter out the common-mode electromagnetic interference on the signal line, and on the other hand, it also needs to suppress itself from emitting electromagnetic interference outward to avoid affecting the normal operation of other electronic devices in the same electromagnetic environment.

[0045] The main component of the EMC filter circuit is the common-mode inductor, which includes two common-mode inductor coils wound on the same iron core with the same number of turns and the same phase. Therefore, when the normal current in the circuit flows through the common-mode inductor, the normal current generates reverse magnetic fields in the inductor coils wound in the same phase and cancels each other out. At this time, the normal current is mainly affected by the resistance of the inductor coil (and a small amount of damping caused by leakage inductance). When a common-mode current flows through the inductor coil, due to the co-directionality of the common-mode current, a co-directional magnetic field will be generated in the inductor coil, increasing the inductive reactance of the inductor coil, making the inductor coil exhibit a high impedance and generating a strong damping effect to attenuate the common-mode current and achieve the purpose of filtering. When a differential-mode current flows through the inductor coil, due to the co-directionality of the differential-mode current, reverse magnetic fields will be generated in the inductor coil and cancel each other out.

[0046] Therefore, the use of an EMC filter circuit can reduce EMI, enabling the EMC performance of the power output circuit 10 and the power supply device 100 to meet the standard requirements before finalizing the design and entering the market.

[0047] However, since there are two DC / DC units connected in series or parallel, generally two EMC filter circuits are required to filter the voltages output by the DC / DC units respectively to reduce the common-mode noise in the voltages output by the DC / DC units. Specifically, as Figure 4 shown, taking the parallel connection of the first DC / DC unit 11 and the second DC / DC unit 12 as an example, the power output circuit 10 includes an EMC filter circuit 14. Among them, the EMC filter circuit 14 includes a first EMC filter circuit 141 and a second EMC filter circuit 142. The first DC / DC unit 11 is connected to the first positive input terminal and the first negative input terminal of the output port 13 through the first EMC filter circuit 141, and the second DC / DC unit 12 is connected to the second positive input terminal and the second negative input terminal of the output port 13 through the second EMC filter circuit 142. The first EMC filter circuit 141 filters the DC voltage output by the first DC / DC unit 11, and the second EMC filter circuit 142 filters the DC voltage output by the second DC / DC unit 12 to eliminate the common-mode noise signal and reduce the EMI of the circuit.

[0048] However, due to the possible differences in the wiring and distributed parameters of the two EMC filter circuits, there are differences in electromagnetic noise, power supply ripple, etc., resulting in circuit imbalance. Moreover, the two EMC filter circuits are placed in parallel and side by side, and there is coupling of the common-mode inductor magnetic flux, resulting in poor filtering effect. The common-mode noise signal may also only pass through one EMC filter circuit, making the inductance of the common-mode inductor half of the expected value, resulting in poor filtering effect.

[0049] For the above reasons, an embodiment of the present utility model provides a power output circuit. The power output circuit 10 includes a first DC / DC unit 11, a second DC / DC unit 12, and an output port 13, and further includes an EMC filtering unit 15. Among them, the EMC filtering unit 15 is electrically connected to the output port 13.

[0050] The EMC filtering unit 15 can be electrically connected to the input end of the output port 13. Specifically, as Figure 5 shown and Figure 6 shown, the positive output end of the first DC / DC unit 11 is electrically connected to the first input end of the EMC filtering unit 15, the negative output end of the first DC / DC unit 11 is electrically connected to the second input end of the EMC filtering unit 15, the positive output end of the second DC / DC unit 12 is electrically connected to the third input end of the EMC filtering unit 15, the negative output end of the second DC / DC unit 12 is electrically connected to the fourth input end of the EMC filtering unit 15, the first output end of the EMC filtering unit 15 is electrically connected to the first positive input end of the output port 13, the second output end of the EMC filtering unit 15 is electrically connected to the first negative input end of the output port 13, the third output end of the EMC filtering unit 15 is electrically connected to the second positive input end of the output port 13, and the fourth output end of the EMC filtering unit 15 is electrically connected to the second negative input end of the output port 13.

[0051] In some embodiments, the EMC filtering unit 15 includes a first winding, a second winding, a third winding, and a fourth winding. The first winding, the second winding, the third winding, and the fourth winding are wound around the same iron core.

[0052] Then the positive output end of the first DC / DC unit 11 is electrically connected to the first positive input end of the output port 13 through the first winding, the negative output end of the first DC / DC unit 11 is electrically connected to the first negative input end of the output port 13 through the second winding, the positive output end of the second DC / DC unit 12 is electrically connected to the second positive input end of the output port 13 through the third winding, and the negative output end of the second DC / DC unit 12 is electrically connected to the second negative input end of the output port 13 through the fourth winding.

[0053] The number of turns of the first winding, the second winding, the third winding, and the fourth winding is the same, and the winding directions are the same. The shape of the iron core includes one of a ring shape, a U shape, and an E shape, and the ring shape is shown as an example in the figure.

[0054] When series connection is required, such as Figure 5As shown, the first negative input terminal of the output port 13 is connected to its second positive input terminal. The first DC / DC unit 11 outputs a first electrical energy signal, and the second DC / DC unit 12 outputs a second electrical energy signal. The common-mode interference currents in the first electrical energy signal and the second electrical energy signal flow through the first winding, the second winding, the third winding, and the fourth winding, generating magnetic fields in the same direction. As a result, the inductive reactance is increased, causing the coil to exhibit a high impedance and producing a strong damping effect to attenuate the common-mode interference current, thereby achieving the purpose of filtering out the common-mode noise signal. The differential-mode interference currents in the first electrical energy signal and the second electrical energy signal flow through the first winding, the second winding, the third winding, and the fourth winding, generating magnetic fields in opposite directions, and thus canceling each other out. The output port 13 outputs the first DC voltage after filtering out the common-mode noise signal.

[0055] When parallel connection is required, as Figure 6 shown, the first positive input terminal of the output port 13 is connected to its second positive input terminal, and the second positive input terminal of the output port 13 is connected to its second negative input terminal. Similar to the above embodiment, the first electrical energy signal output by the first DC / DC unit 11 and the second electrical energy signal output by the second DC / DC unit 12 are filtered by the first winding, the second winding, the third winding, and the fourth winding to filter out the common-mode interference current therein, and the output port 13 outputs the second DC voltage after filtering out the common-mode noise signal.

[0056] Therefore, in this embodiment, the first DC voltage or the second DC voltage is filtered to reduce the common-mode noise signal, and the power output circuit 10 in this embodiment uses a single EMC filtering unit 15 for filtering, improving the EMC filtering effect and having a lower cost.

[0057] In some embodiments, the EMC filtering unit 15 can be electrically connected to the output end of the output port 13. Specifically, as Figure 7 shown in Figure 8 connection with

[0058] shown, the third input terminal of the EMC filtering unit 15 is connected to the positive output terminal of the output port 13, the fourth input terminal of the EMC filtering unit 15 is connected to the negative output terminal of the output port 13, and the output end of the EMC filtering unit 15 is used to output the first DC voltage or the second DC voltage.

[0059] When the first DC / DC unit 11 and the second DC / DC unit 12 need to be connected in series, as Figure 7 shown, the positive output terminal of the first DC / DC unit 11 is connected to the first positive input terminal of the output port 13, the negative output terminal of the first DC / DC unit 11 is connected to the first negative input terminal of the output port 13, the positive output terminal of the second DC / DC unit 12 is connected to the second positive input terminal of the output port 13, and the negative output terminal of the second DC / DC unit 12 is connected to the second negative input terminal of the output port 13.

[0060] The first negative input terminal and the second positive input terminal of the output port 13 are connected, and the positive output terminal and the negative output terminal of the output port 13 output a first DC voltage through the fifth winding and the sixth winding. The magnetic field directions generated by the common-mode interference current flowing through the fifth winding and the sixth winding in the first DC voltage signal are the same, thereby increasing the inductive reactance, making the coil exhibit a high impedance, generating a strong damping effect to attenuate the common-mode interference current, and achieving the purpose of filtering the common-mode noise signal. The magnetic field directions generated by the differential-mode interference current flowing through the fifth winding and the sixth winding in the first DC voltage signal are opposite, and thus cancel each other out. After the common-mode noise signal in the first DC voltage signal is filtered, the load 200 is powered.

[0061] When parallel connection is required, as Figure 8 shown, the first positive input terminal and the second positive input terminal of the output port 13 are connected, the second positive input terminal and the second negative input terminal of the output port 13 are connected, and the positive output terminal and the negative output terminal of the output port 13 output a second DC voltage through the fifth winding and the sixth winding. Similar to the above embodiment, the second DC voltage signal is filtered through the fifth winding and the sixth winding to filter out the common-mode interference current therein. After the common-mode noise signal in the second DC voltage signal is filtered, the load 200 is powered.

[0062] EMC testing is used to test the filtering effect of the embodiments of the present invention. Figure 9a is a schematic diagram of the EMC test results of the prior art. Figure 9b is a schematic diagram of the EMC test results of the embodiments of the present invention. Figure 9a In Figure 9b , the horizontal axis is the frequency and the vertical axis is the amplitude of the noise signal. Among them, the curve L1 is the peak data curve of the EMC test value, the curve L2 is the average value data curve of the EMC test value, the curve L3 is the EMC peak standard limit curve, and the curve L4 is the EMC average value standard limit curve. If the peak data exceeds the curve L3, or the average value data exceeds the curve L4, it indicates that the EMC exceeds the standard. If the peak data is lower than the curve L3 and the average value data is lower than the curve L4, it indicates that the EMC test is qualified.

[0063] Figure 9a It is characterized in that due to poor filtering effect, the EMC test fails seriously, and the overall test data is above the EMC limit. Figure 9b It is characterized in that the overall EMC test data has decreased by about 20 dB (a 10-fold decrease).

[0064] In summary, the power output circuit uses an EMC filtering unit to filter the first DC voltage or the second DC voltage, reducing high-frequency noise. And compared with the scheme of using two EMC filtering units, the power output circuit uses one EMC filtering unit for filtering, improving the EMC filtering effect and having a lower cost.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power output circuit, characterized in that, Comprising: A first DC / DC unit, a second DC / DC unit, an EMC filtering unit, and an output port; The first DC / DC unit and the second DC / DC unit are connected in series and output a first DC voltage through the output port. Alternatively, the first DC / DC unit and the second DC / DC unit are connected in parallel and output a second DC voltage through the output port; The EMC filtering unit is electrically connected to the output port and is used to filter the first DC voltage or the second DC voltage.

2. The power output circuit according to claim 1, wherein The positive output terminal of the first DC / DC unit is electrically connected to the first input terminal of the EMC filtering unit, The negative output terminal of the first DC / DC unit is electrically connected to the second input terminal of the EMC filtering unit. The positive output terminal of the second DC / DC unit is electrically connected to the third input terminal of the EMC filtering unit. The negative output terminal of the second DC / DC unit is electrically connected to the fourth input terminal of the EMC filtering unit. The first output terminal of the EMC filtering unit is electrically connected to the first positive input terminal of the output port. The second output terminal of the EMC filtering unit is electrically connected to the first negative input terminal of the output port. The third output terminal of the EMC filtering unit is electrically connected to the second positive input terminal of the output port. The fourth output terminal of the EMC filtering unit is electrically connected to the second negative input terminal of the output port, The output terminal of the output port is used to output the first DC voltage or the second DC voltage.

3. The power output circuit according to claim 2, wherein, The EMC filtering unit includes a first winding, a second winding, a third winding, and a fourth winding. The first winding, the second winding, the third winding, and the fourth winding are wound around the same iron core; The positive output terminal of the first DC / DC unit is electrically connected to the first positive input terminal of the output port through the first winding; The negative output terminal of the first DC / DC unit is electrically connected to the first negative input terminal of the output port through the second winding; The positive output terminal of the second DC / DC unit is electrically connected to the second positive input terminal of the output port through the third winding; The negative output terminal of the second DC / DC unit is electrically connected to the second negative input terminal of the output port through the fourth winding.

4. The power output circuit according to claim 3, wherein The magnetic field directions generated by the common-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the first winding, the second winding, the third winding, and the fourth winding are the same; The magnetic field directions generated by the differential-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the first winding, the second winding, the third winding, and the fourth winding are opposite.

5. The power output circuit according to claim 1, wherein The third input terminal of the EMC filtering unit is connected to the first positive output terminal of the output port. The fourth input terminal of the EMC filtering unit is connected to the first negative output terminal of the output port. The output terminal of the EMC filtering unit is used to output the first DC voltage or the second DC voltage.

6. The power output circuit according to claim 5, wherein The EMC filtering unit includes a fifth winding and a sixth winding, and the fifth winding and the sixth winding are wound around the same iron core; The positive output terminal of the output port is electrically connected to one end of the fifth winding, the negative output terminal of the output port is electrically connected to one end of the sixth winding, and the other ends of the fifth winding and the sixth winding are both used to output the first DC voltage or the second DC voltage.

7. The power output circuit according to claim 6, characterized in that The magnetic field directions generated by the common-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the fifth winding and the sixth winding are the same; The magnetic field directions generated by the differential-mode interference current in the first DC voltage signal or the second DC voltage signal flowing through the fifth winding and the sixth winding are opposite.

8. The power output circuit according to claim 3 or 6, characterized in that, The shape of the iron core includes one of a ring shape, a U shape, and an E shape.

9. A power supply device, characterized in that, It includes an external power supply and the power output circuit according to any one of claims 1-8, wherein the external power supply is electrically connected to the first DC / DC unit and the second DC / DC unit respectively.

10. A power supply system, characterized in that, It includes a load and the power supply device according to claim 9, wherein the first DC voltage or the second DC voltage is used to supply power to the load.

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