Bipolar multi-output DC-DC converter for CLC filtering and control method thereof

Abstract

The invention relates to a bipolar multi-output DC-DC converter based on CLC filtering and a control method. The converter comprises an input unit, a switch unit, a filtering and energy transfer unit, an output unit and a control unit. The input unit is used for providing direct-current input voltage; the switch unit is used for controlling on and off of a plurality of switches through a driving signal; the filtering and energy transfer unit is used for realizing energy distribution, stabilizing the output voltage and adjusting the polarity of an output port; the output unit comprises a plurality of output ports and is used for providing common-ground multi-output voltage; and the control unit is used for collecting voltage signals of the output ports and generating driving signals to control the switch state so as to realize closed-loop control. According to the invention, soft switching can be realized, the efficiency of the DC-DC converter is improved, highly symmetrical and common-ground positive and negative outputs and single-path negative output can be obtained, the topology is simple and reliable, and the cost is relatively low.

Description

Technical Field

[0001] The present invention relates to the technical field of power supplies, and in particular to a CLC filtered bipolar multi-output DC-DC converter and a control method thereof. Background Art

[0002] With the rapid advancement of power electronics technology, switching power supplies have been widely used in various electrical devices. Currently, many application scenarios require high power density and symmetrical positive and negative voltage outputs from switching power supplies, such as inverters, Class-D audio amplifiers, ultrasonic medical imaging systems, and auxiliary power supplies for dual power supplies.

[0003] Currently, positive and negative voltage outputs are typically achieved through forward or flyback topologies. This approach relies on a multi-winding isolation transformer design, using a shared magnetic core to achieve isolated positive and negative voltage outputs. However, this solution has obvious drawbacks: the transformer design is complex, and cross-winding adjustments significantly impact performance. Furthermore, copper and iron losses introduced by the transformer reduce efficiency. Furthermore, the forward and flyback topologies require additional circuitry to eliminate voltage spikes from the switching devices, further increasing system complexity and sacrificing efficiency.

[0004] To simplify the structure, some applications use two non-isolated switching converters to provide positive and negative voltage outputs, respectively. This solution eliminates mutual interference between the outputs, improves efficiency, and eliminates the need for a transformer. However, its disadvantage is the need for two control systems and main power circuits, which increases the number of components and system costs.

[0005] Therefore, in order to solve the above-mentioned shortcomings, it is urgent to realize a new type of DC-DC converter. Summary of the Invention

[0006] The object of the present invention is to provide a CLC filtered bipolar multi-output DC-DC converter and a control method thereof, which can solve the deficiencies in the prior art and has the characteristics of a small number of components and low cost.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A bipolar multi-output DC-DC converter based on CLC filtering comprises an input unit, a switch unit, a filtering and energy transfer unit, an output unit and a control unit.

[0009] The input unit, serving as the input port of the entire DC-DC converter, is used to provide a DC input voltage; the switch unit is used to control the on and off of multiple switches through a drive signal; the filtering and energy transfer unit is used to achieve energy distribution between the input port and the output port with the help of inductors and capacitors according to the on and off states of each switch in the switch unit; at the same time, the CLC filter structure is used to suppress ripple to stabilize the output voltage, and the polarity of the output port is adjusted based on the unidirectional conductivity of the diode and the freewheeling effect of the inductor; the output unit includes multiple output ports, which are used to provide multiple output voltages with a common ground; the control unit is used to collect the voltage signals of each output port, generate a drive signal to control the switch state, and realize closed-loop control.

[0010] Furthermore, the input unit includes a first port.

[0011] Furthermore, the switch unit includes a first switch S1 and a second switch S2.

[0012] Furthermore, the filtering and energy transfer unit includes an inductor L1, an inductor L2, an inductor L3, an inductor L4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a diode D1 and a diode D2.

[0013] Specifically, the positive electrode of the first port is connected to the first end of the inductor L1, and the negative electrode of the first port is grounded; the second end of the inductor L1 is connected to the first end of the capacitor C1, the second end of the capacitor C1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the first end of the capacitor C2, and the second end of the capacitor C2 is grounded; the first end of the capacitor C3 is connected to the node between the inductor L1 and the capacitor C1, the second end of the capacitor C3 is connected to the first end of the inductor L3, the second end of the inductor L3 is connected to the first end of the capacitor C5, and the second end of the capacitor C5 is connected to the first end of the inductor L1. The first end of the capacitor C5, the first end of the capacitor C6, the cathode of the diode D1, and the first end of the inductor L4 are connected to the second end of the capacitor C4 and the anode of the diode D2, respectively. The first end of the capacitor C4 is connected to the first end of the capacitor C3. The cathode of the diode D2 is connected to the second end of the capacitor C6. The second end of the capacitor C5, the first end of the capacitor C6, the cathode of the diode D1, and the first end of the inductor L4 are all grounded.

[0014] Furthermore, the output unit includes a second port, a third port and a fourth port.

[0015] The positive electrode of the second port is respectively connected to the second end of the inductor L3 and the first end of the capacitor C5; the negative electrode of the second port, the negative electrode of the third port, and the negative electrode of the fourth port are all grounded; the positive electrode of the third port is respectively connected to the negative electrode of the diode D2 and the second end of the capacitor C6; the positive electrode of the fourth port is respectively connected to the second end of the inductor L2 and the first end of the capacitor C2.

[0016] Furthermore, the control unit includes a controller; the input end of the controller is respectively connected to the positive pole of the second port, the positive pole of the third port, and the positive pole of the fourth port; the output end of the controller is respectively connected to the control end of the first switch S1 and the control end of the second switch S2.

[0017] Furthermore, both the first switch S1 and the second switch S2 are active switch tubes.

[0018] Furthermore, the active switch tube is a wide bandgap semiconductor device, a field effect tube or a transistor.

[0019] When the active switch tube is a wide bandgap semiconductor device or a field effect tube, the connection mode of each pole of the first switch S1 and the second switch S2 with other components is as follows: the source of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the drain of the first switch S1 is grounded, and the base of the first switch S1 is connected to the output end of the controller (105); the source of the second switch S2 is grounded, the drain of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base of the second switch S2 is connected to the output end of the controller (105).

[0020] When the active switch tube is a transistor, the connection mode of each pole of the first switch S1 and the second switch S2 with other components is as follows: the collector of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the emitter of the first switch S1 is grounded, and the base of the first switch S1 is connected to the output end of the controller (105); the collector of the second switch S2 is grounded, the emitter of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base of the second switch S2 is connected to the output end of the controller (105).

[0021] Furthermore, the driving signal of the first switch S1 and the driving signal of the second switch S2 are complementary while ignoring the dead zone.

[0022] The present invention also includes a control method for the above-mentioned bipolar multi-output DC-DC converter based on CLC filtering, the method comprising the following steps:

[0023] (1) Drive signal generation and switch control

[0024] The controller generates drive signals for the first switch S1 and the second switch S2. Ignoring the dead zone, the drive signals of the two switches are complementary. The drive signals are used to control the first switch S1 and the second switch S2 to alternately turn on and off, thereby achieving time-sharing energy transfer.

[0025] (2) Soft switching control

[0026] A dead time is set, where the dead time is the interval between the first switch S1 and the second switch S2 being in the off state when switching, and the dead time is matched to the parameters of the inductors L1 to L4. During the dead time when the second switch S2 is off and the first switch S1 is not yet turned on, the current freewheeling characteristics of the inductors L1 and L2 are utilized to turn on the equivalent diode of the second switch S2, thereby achieving zero voltage turn-on of S2. During the dead time when the first switch S1 is off and the second switch S2 is not yet turned on, the current freewheeling characteristics of the inductors L3 and L4 are utilized to turn on the equivalent diode of the first switch S1, thereby achieving zero voltage turn-on of the first switch S1.

[0027] (3) Closed-loop control of output voltage

[0028] The controller collects the positive voltage signals of the second, third, and fourth ports in real time, compares the collected voltage signals with the target voltage, and adjusts the duty cycle of the drive signals of the first switch S1 and the second switch S2 according to the comparison results, so that the voltage of each output port is stable at the set value;

[0029] (4) Multi-output energy distribution

[0030] The energy flow is controlled according to the on / off state of each switch. When the first switch S1 is on and the second switch S2 is off, the input port is controlled to transfer energy to the inductor L1, while the inductor L2 transfers energy to the capacitor C1, the inductor L3 transfers energy to the capacitor C3, and the inductor L4 transfers energy to the capacitor C4. When the second switch S2 is on and the first switch S1 is off, the first port is controlled to charge the inductor L1 and the capacitor C1, while energy is transferred to the third port through the capacitor C4 and the diode D2, charging the capacitor C3, and transferring energy to the inductor L2, so that each output port obtains the corresponding energy.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] During operation, the CLC-filtered bipolar multi-output DC-DC converter of the present invention can achieve soft switching between its first switch S1 and second switch S2 from no-load to full-load, thereby improving the efficiency of the DC-DC converter. Furthermore, the converter can also achieve highly symmetrical and common-ground positive and negative dual outputs and a single negative output, with a simple and reliable topology and low cost. The switching device used in the present invention is easy to achieve soft switching, simple to drive, and easy to control in a closed loop. It can be widely used in fields such as inverters, Class-D audio amplifiers, ultrasonic medical imaging systems, and positive and negative power auxiliary power supplies. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a circuit topology diagram of a bipolar multi-output DC-DC converter with CLC filtering in the present invention;

[0034] Figure 2 Schematic diagram of the corresponding relationship between the first driving signal and the second driving signal;

[0035] Figure 3 is a waveform diagram of the drain-source voltage of the second switch S2 and the current flowing into the drain;

[0036] Figure 4 is a waveform diagram of the drain-source voltage of the first switch S1 and the current flowing into the drain;

[0037] Figure 5 : driving waveforms of the first switch S1 and the second switch S2 and waveforms of the inductors L1-L4;

[0038] Figure 6 This is a voltage waveform diagram of the positive and negative 6.5V voltage output by the CLC filtered bipolar multi-output DC-DC converter of the present invention;

[0039] Figure 7 is the ZVS conduction mode diagram of the first switch S1;

[0040] Figure 8 is the ZVS conduction mode diagram of the second switch S2.

[0041] in:

[0042] 101. First port, 102. Second port, 103. Third port, 104. Fourth port, 105. Controller. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings:

[0044] like Figure 1The illustrated bipolar multi-output DC-DC converter with CLC filtering includes an input unit, a switch unit, a filtering and energy transfer unit, an output unit, and a control unit. The input unit, serving as the input port of the entire DC-DC converter, is used to provide a DC input voltage as input for power conversion. The switch unit is used to control the on and off states of multiple switches via a drive signal. Controlled by the control unit, this achieves closed-loop control and maintains voltage output stability. The filtering and energy transfer unit distributes energy between the input and output ports using inductors and capacitors based on the on / off states of each switch in the switch unit. The CLC filtering structure is used to suppress ripple to stabilize the output voltage. The polarity of the output port is adjusted based on the unidirectional conductivity of the diode and the freewheeling effect of the inductor, achieving soft switching of the switch unit. The output unit includes multiple output ports for providing multiple output voltages with a common ground. The control unit is used to collect voltage signals from each output port and generate a drive signal based on the voltage signal and a reference voltage to control the switch state, achieving closed-loop control.

[0045] Furthermore, the input unit includes a first port 101. The switch unit includes a first switch S1 and a second switch S2. The filtering and energy transfer unit includes a diode D1, a diode D2, an inductor L1, an inductor L2, an inductor L3, an inductor L4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C6. The output unit includes a second port 102, a third port 103, and a fourth port 104. The control unit includes a controller 105.

[0046] Specifically, the positive electrode of the first port 101 is connected to one end of the inductor L1, and the negative electrode of the first port 101 is connected to one end of the first switch S1, one end of the second switch S2, capacitor C2, the negative electrode of diode D1, one end of capacitor C5, one end of inductor L4, one end of capacitor C6, the negative electrode of the second port 102, the negative electrode of the third port 103, and the negative electrode of the fourth port 104. The other end of the first switch S1 is connected to one end of capacitor C1, the other end of inductor L1, one end of capacitor C3, and one end of capacitor C4. The other end of capacitor C1 is connected to the other end of the second switch S2 and one end of inductor L2. The other end of inductor L2 is connected to the other end of capacitor C2 and the positive electrode of the fourth port 104. The other end of capacitor C3 is connected to the positive electrode of diode D1 and one end of inductor L3. The other end of inductor L3 is connected to the other end of capacitor C5 and the positive electrode of the second port 102. The other end of capacitor C4 is connected to the anode of diode D2 and the other end of inductor L4. The cathode of diode D2 is connected to the other end of sixth capacitor C6 and the anode of third port 103. An input end of controller 105 is connected to the anode of second port 102, the anode of third port 103, and the anode of fourth port 104. An output end of controller 105 is connected to the control end of first switch S1 and the control end of second switch S2.

[0047] Furthermore, both the first switch S1 and the second switch S2 are active switch tubes, and the active switch tubes are wide bandgap semiconductor devices, field effect tubes or transistors.

[0048] When the active switch tube is a wide bandgap semiconductor device (GaN MOSFETs, SiC MOSFETs, etc.) or a field effect transistor (MOSFETs), the connection mode of each pole of the first switch S1 and the second switch S2 with other components is as follows: the source (Drain) of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the drain (Source) of the first switch S1 is grounded, and the base (Gate) of the first switch S1 is connected to the output end of the controller (105); the source (Drain) of the second switch S2 is grounded, the drain (Source) of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base (Gate) of the second switch S2 is connected to the output end of the controller (105).

[0049] When the active switch tube is a transistor, the connection mode of each pole of the first switch S1 and the second switch S2 with other components is as follows: the collector of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the emitter of the first switch S1 is grounded, and the base of the first switch S1 is connected to the output end of the controller (105); the collector of the second switch S2 is grounded, the emitter of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base of the second switch S2 is connected to the output end of the controller (105).

[0050] Furthermore, the driving signal of the first switch S1 and the driving signal of the second switch S2 are complementary while ignoring the dead zone.

[0051] Furthermore, the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5 and the sixth capacitor C6 are all selected to be relatively large capacitors, and the voltages of the six capacitors can all be regarded as constant values. Soft switching is achieved by reasonably setting the dead time and selecting the values ​​of the first inductor L1, the second inductor L2, the third inductor L3 and the fourth inductor L4.

[0052] The working principle of the CLC filtered bipolar multi-output DC-DC converter of the present invention is as follows:

[0053] When the first switch S1 is turned on and the second switch S2 is turned off, the first port 101 transfers energy to the first inductor L1, the second inductor L2 transfers energy to the first capacitor C1, the third inductor L3 transfers energy to the third capacitor C3, and the fourth inductor L4 transfers energy to the fourth capacitor C4. When the second switch S2 is turned off, during the dead time when the first switch S1 is not turned on, the currents in the first inductor L1 and the second inductor L2 flow from the source S to the drain D of the second switch S2, as shown in FIG. Figure 3 As shown, by reasonably setting the dead time t3-t4 and selecting the values ​​of the first inductor L1 and the second inductor L2, the equivalent diode in the second switch S2 is turned on during the dead time, thereby achieving zero voltage turn-on of the second switch S2.

[0054] When the second switch S2 is turned on and the first switch S1 is turned off, the first port 101 charges the first inductor L1 and the first capacitor C1, and at the same time transfers energy to the third port 103 through the fourth capacitor C4 and the second diode D2 and charges the third capacitor C3; the second capacitor C2 transfers energy to the second inductor L2. When the second switch S2 is turned off, during the dead time when the first switch S1 is not turned on, the current in the second inductor L3 flows to the second port 102, and the current in the fourth inductor L4 flows to ground (the currents in the first inductor L3 and the second inductor L4 continue to flow), as shown in FIG. Figure 4As shown, by setting reasonable dead time DT and values ​​of the first inductor L1 and the second inductor L2, the equivalent diode in the first switch S1 is turned on during the dead time, thereby achieving ZVS conduction of the first switch S1.

[0055] When the first port 101 serves as the input port of the DC-DC converter, and the second port 102, the third port 103, and the fourth port 104 serve as the output ports of the DC-DC converter, under light load conditions, the first switch S1 and the second switch S2 can easily achieve ZVS conduction. Under heavy load conditions, it is more difficult for the first switch S1 to achieve ZVS conduction. However, by reasonably designing the parameters of the first inductor L1 and the second inductor L2 and the output power of the DC-DC converter, a DC-DC converter with soft switching from no-load to full-load can be obtained.

[0056] The voltage amplitudes of the second port 102 and the third port 103 are the same, but the polarities are opposite. The second port 102 and the third port 103 are stepped down relative to the first port 101, and the polarities of the first port 101 and the third port 103 are the same. The fourth port 104 has the same polarity as the second port 102 and is stepped down relative to the first port 101, with a voltage amplitude slightly greater than that of the second port 102.

[0057] Figures 5 to 8 The effectiveness of the CLC-filtered bipolar multi-output DC-DC converter has been verified from various perspectives, including the rationality of switch control, the implementation of soft switching, and the stability and symmetry of the output voltage. This demonstrates that the converter topology is simple and reliable, and can meet design requirements. Specific details are as follows:

[0058] from Figure 5 It can be seen that the drive signals of the first switch S1 and the second switch S2 exhibit a complementary relationship, ignoring the dead zone. That is, when the drive signal of S1 is high (on), the drive signal of S2 is low (off), and vice versa. The current waveforms of inductors L1 to L4 change accordingly with the on and off of the switches, reflecting the energy storage and release process in the inductors. When the first switch S1 is on and the second switch S2 is off, energy is input to inductor L1, and the current increases; while inductors L2, L3, and L4 release energy, and the current decreases. When the second switch S2 is on and the first switch S1 is off, inductor L1 is in a charging state, and the current changes show a specific pattern. Inductor L2 also experiences corresponding energy transfer, resulting in current changes. The complementary drive of the two switches realizes time-sharing energy transfer, allowing the inductors to store and release energy as designed, providing a basis for energy distribution across multiple output ports. At the same time, the freewheeling characteristics of the inductor current are one of the key factors in achieving soft switching. The waveform shows that the inductor plays a freewheeling role in the switching process, creating conditions for the subsequent realization of soft switching.

[0059] from Figure 6 It can be seen that the output voltage waveforms of the second port 102 and the third port 103 are highly symmetrical, with voltage values ​​stable at around +6.5V and -6.5V, respectively, and with small ripples. The fourth port 104 also has a stable positive output voltage with the same polarity as the second port 102, and a voltage amplitude slightly greater than 6.5V. The DC-DC converter described in the present invention can achieve highly symmetrical and common-ground positive and negative dual outputs (the second port and the third port) and a single positive output (the fourth port), meeting the requirements of multiple outputs with adjustable polarity. The CLC filter structure effectively suppresses the ripple of the output voltage, making the output voltage stable, verifying the effectiveness of the filtering and energy transfer unit in stabilizing the output voltage.

[0060] from Figure 7 As can be seen in the figure, during the dead time between the off state of first switch S1 and the on-state of second switch S2, the currents in inductors L3 and L4 are in a freewheeling state, causing the equivalent diode of S1 to conduct. At this time, the voltage across S1 is approximately zero, and S1 is then turned on. By properly setting the dead time and matching the parameters of inductors L3 and L4, zero voltage turn-on (ZVS) of the first switch S1 is successfully achieved. The implementation of soft switching can significantly reduce switching losses and improve the efficiency of the DC-DC converter, which also proves the effectiveness of the soft switching control strategy in the control method.

[0061] from Figure 8 It can be seen that during the dead time between the off-state of second switch S2 and the on-state of first switch S1, the currents in inductors L1 and L2 continue to flow, causing the equivalent diode of S2 to conduct and the voltage across S2 to zero. S2 then turns on. Similarly, by properly setting the dead time and matching the parameters of inductors L1 and L2, zero voltage turn-on (ZVS) of the second switch S2 is achieved. This further verifies that the converter can achieve soft switching, thereby improving efficiency, and that the topology and control method can reliably achieve this function.

[0062] In summary, the present invention proposes a bipolar multi-output DC-DC converter based on CLC filtering, which includes an input unit, a switching unit, a filtering and energy transfer unit, an output unit, and a control unit. The core topology architecture of the converter only requires two switching tubes, two diodes, four inductors, and six capacitors, which reduces the number of components and has the significant advantages of simple topology, high reliability, and low manufacturing cost. A key performance breakthrough of the converter is that its switching unit can fully realize soft switching operation (ZVS) under the entire wide range of load conditions from light load to full load, reducing switching losses and improving the overall conversion efficiency of the converter under a wide range of loads. At the same time, it reduces the thermal stress on the components and power board, which facilitates thermal design. The design of the present invention innovatively realizes highly symmetrical positive and negative dual-channel DC outputs, realizes low ripple and highly symmetrical bipolar common ground output, and the positive and negative output terminals share a common reference ground (common ground), which is crucial for applications requiring symmetrical bipolar power supplies. At the same time, the present invention does not require additional complex isolation or conversion circuits, further enhancing practicality and integration.

[0063] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A bipolar multi-output DC-DC converter based on CLC filtering, characterized in that: The DC-DC converter includes an input unit, a switch unit, a filtering and energy transfer unit, an output unit and a control unit; The input unit serves as an input port of the entire DC-DC converter and is used to provide a DC input voltage; The switch unit is used to control the on and off of multiple switches through a driving signal; The filtering and energy transfer unit is used to achieve energy distribution between the input port and the output port by means of inductors and capacitors according to the on / off states of the switches in the switching unit; at the same time, the CLC filtering structure is used to suppress ripple to stabilize the output voltage, and the polarity of the output port is adjusted based on the unidirectional conductive characteristics of the diode and the freewheeling effect of the inductor; The output unit includes a plurality of output ports for providing multiple output voltages with a common ground; The control unit is used to collect voltage signals from each output port, generate drive signals to control the switch state, and implement closed-loop control.

2. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 1, characterized in that: The input unit includes a first port (101).

3. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 2, characterized in that: The switch unit includes a first switch S1 and a second switch S2.

4. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 3, characterized in that: The filtering and energy transfer unit includes an inductor L1, an inductor L2, an inductor L3, an inductor L4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a diode D1 and a diode D2; The positive electrode of the first port (101) is connected to the first end of the inductor L1, and the negative electrode of the first port (101) is grounded; the second end of the inductor L1 is connected to the first end of the capacitor C1, the second end of the capacitor C1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the first end of the capacitor C2, and the second end of the capacitor C2 is grounded; the first end of the capacitor C3 is connected to the node between the inductor L1 and the capacitor C1, the second end of the capacitor C3 is connected to the first end of the inductor L3, the second end of the inductor L3 is connected to the first end of the capacitor C5, and the second end of the capacitor C5 is grounded. The two ends are respectively connected to the cathode of the diode D1 and the first end of the capacitor C6; the anode of the diode D1 is connected to the node between the capacitor C3 and the inductor L3, the cathode of the diode D1 is connected to the first end of the inductor L4, and the second end of the inductor L4 is respectively connected to the second end of the capacitor C4 and the anode of the diode D2; the first end of the capacitor C4 is connected to the first end of the capacitor C3; the cathode of the diode D2 is connected to the second end of the capacitor C6; the second end of the capacitor C5, the first end of the capacitor C6, the cathode of the diode D1, and the first end of the inductor L4 are all grounded.

5. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 4, characterized in that: The output unit includes a second port (102), a third port (103) and a fourth port (104); The positive electrode of the second port (102) is respectively connected to the second end of the inductor L3 and the first end of the capacitor C5; the negative electrode of the second port (102), the negative electrode of the third port (103), and the negative electrode of the fourth port (104) are all grounded; the positive electrode of the third port (103) is respectively connected to the negative electrode of the diode D2 and the second end of the capacitor C6; and the positive electrode of the fourth port (104) is respectively connected to the second end of the inductor L2 and the first end of the capacitor C2.

6. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 5, characterized in that: The control unit comprises a controller (105); an input end of the controller (105) is respectively connected to the positive electrode of the second port (102), the positive electrode of the third port (103), and the positive electrode of the fourth port (104); and an output end of the controller (105) is respectively connected to the control end of the first switch S1 and the control end of the second switch S2.

7. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 1, characterized in that: The first switch S1 and the second switch S2 are both active switch tubes.

8. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 7, characterized in that: The active switch tube is a wide bandgap semiconductor device, a field effect tube or a transistor; When the active switch tube is a wide bandgap semiconductor device or a field effect tube, the connection mode of each electrode of the first switch S1 and the second switch S2 with other components is as follows: the source electrode of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the drain electrode of the first switch S1 is grounded, and the base electrode of the first switch S1 is connected to the output end of the controller (105); the source electrode of the second switch S2 is grounded, the drain electrode of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base electrode of the second switch S2 is connected to the output end of the controller (105); When the active switch tube is a transistor, the connection mode of each pole of the first switch S1 and the second switch S2 with other components is as follows: the collector of the first switch S1 is connected to the second end of the inductor L1 and the first end of the capacitor C1, the emitter of the first switch S1 is grounded, and the base of the first switch S1 is connected to the output end of the controller (105); the collector of the second switch S2 is grounded, the emitter of the second switch S2 is connected to the second end of the capacitor C1 and the first end of the inductor L2, and the base of the second switch S2 is connected to the output end of the controller (105).

9. The bipolar multi-output DC-DC converter based on CLC filtering according to claim 1, characterized in that: The driving signal of the first switch S1 and the driving signal of the second switch S2 are complementary while ignoring the dead zone.

10. The control method of a bipolar multi-output DC-DC converter based on CLC filtering according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) Drive signal generation and switch control The controller (105) generates driving signals for the first switch S1 and the second switch S2. When the dead zone is ignored, the driving signals of the two switches are complementary. The driving signals are used to control the first switch S1 and the second switch S2 to be alternately turned on and off, thereby realizing time-sharing energy transfer. (2) Soft switching control A dead time is set, where the dead time is the interval between the first switch S1 and the second switch S2 being in the off state when switching, and the dead time is matched to the parameters of the inductors L1 to L4. During the dead time when the second switch S2 is off and the first switch S1 is not yet turned on, the current freewheeling characteristics of the inductors L1 and L2 are utilized to turn on the equivalent diode of the second switch S2, thereby achieving zero voltage turn-on of S2. During the dead time when the first switch S1 is off and the second switch S2 is not yet turned on, the current freewheeling characteristics of the inductors L3 and L4 are utilized to turn on the equivalent diode of the first switch S1, thereby achieving zero voltage turn-on of the first switch S1. (3) Closed-loop control of output voltage The controller (105) collects positive voltage signals of the second port (102), the third port (103), and the fourth port (104) in real time, compares the collected voltage signals with the target voltage, and adjusts the duty cycle of the driving signals of the first switch S1 and the second switch S2 according to the comparison result, so that the voltage of each output port is stabilized at a set value; (4) Multi-output energy distribution The energy flow direction is controlled according to the on-off state of each switch. When the first switch S1 is on and the second switch S2 is off, the first port (101) is controlled to transfer energy to the inductor L1, and at the same time, the inductor L2 is made to transfer energy to the capacitor C1, the inductor L3 is made to transfer energy to the capacitor C3, and the inductor L4 is made to transfer energy to the capacitor C4. When the second switch S2 is on and the first switch S1 is off, the first port (101) is controlled to charge the inductor L1 and the capacitor C1, and at the same time, energy is transferred to the third port (103) through the capacitor C4 and the diode D2, the capacitor C3 is charged, and the capacitor C2 is made to transfer energy to the inductor L2, so that each output port obtains corresponding energy.

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