A two-phase dc / dc converter with low-voltage side active filtering

Abstract

The application provides a two-phase DC / DC converter with low-voltage side active filtering, and belongs to the technical field of power electronics and high-voltage direct current transmission. In the first phase unit, the anode of diode valve group one is connected with the anode of thyristor valve group one, the cathodes of diode valve group one and diode valve group two are connected with the high-voltage side port, the cathodes of thyristor valve group one and thyristor valve group two are grounded, and active bridge arms S1 are respectively connected with the midpoints of diode valve group one and thyristor valve group one; in the second phase unit, the anode of diode valve group two is connected with the anode of thyristor valve group two, and active bridge arms S2 are respectively connected with the midpoints of diode valve group two and thyristor valve group two; the anodes of diode valve group one, diode valve group two and one end of active bridge arm S0 are connected with the low-voltage side port, and the other end of active bridge arm S0 is grounded. The application has the advantages of low cost, small volume, high reliability, low loss, high control force of current by the active bridge arm, smooth current on the DC side, and no need of DC filter.

Description

Technical Field

[0001] This invention relates to a two-phase DC / DC converter with active filtering on the low-voltage side, belonging to the fields of power electronics and high-voltage direct current transmission technology. Background Technology

[0002] Large-scale renewable energy generation, particularly in desert, Gobi, and arid regions, as well as deep-sea areas, is being rapidly deployed, driving the transformation of the power system structure towards a new type of power system dominated by renewable energy. This shift has brought DC grid technology, which can efficiently integrate distributed energy resources, into the spotlight.

[0003] In DC power grids, DC / DC converters capable of interconnecting DC systems of different voltage levels are key equipment. Developing low-cost DC / DC converters that combine high voltage and high capacity has become an urgent need for promoting DC power grid construction and the integration of new energy sources.

[0004] The invention patent with patent application number CN202311033380.4 discloses a high-current DC / DC converter with parallel low-voltage side bridge arms. It uses four-phase full-bridge arms and semiconductor valve groups to realize the distribution of high current on the low-voltage side among multiple bridge arms, thereby improving the current transmission capability of the DC / DC converter. However, the number of semiconductor valve groups and IGBTs used is still relatively large, and the cost of the converter is high.

[0005] The invention patent with patent application number CN201711453648.4 discloses a two-phase DC / DC converter with high-voltage side filtering based on interleaved parallel BOOST. However, during its operation, there is a mode in which the DC current on the high-voltage side is supported only by the filter bridge arm, which leads to a large energy storage requirement for the filter bridge arm and a large overall size of the converter. At the same time, because the active filter bridge arm is placed on the high-voltage side, the filter bridge arm requires a large number of sub-modules, and the overall converter requires a large number of sub-modules, thus making the converter cost high.

[0006] In summary, DC transformers in DC power grids need to meet the characteristics of large capacity, few components, high efficiency, and low cost. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and to provide a two-phase DC / DC converter with active filtering on the low-voltage side. This two-phase DC / DC converter with active filtering on the low-voltage side has the characteristics of fewer sub-modules, fewer semiconductor devices, high efficiency, low cost, and large capacity.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A two-phase DC / DC converter with low-voltage side active filtering includes: a first phase unit, a second phase unit, and an active bridge arm S0; both the first phase unit and the second phase unit include: an active bridge arm, a diode valve group, and a thyristor valve group;

[0010] In the first phase unit, the anode of diode valve group one is connected to the anode of thyristor valve group one, the cathode of diode valve group one is connected to the high-voltage side port, the cathode of thyristor valve group one is grounded, and thyristor valve group one and diode valve group one are each equally divided into two series units. The connection point of the two series units is the midpoint of the valve group. The active bridge arm S1 is connected to the midpoint of diode valve group one and the midpoint of thyristor valve group one, respectively.

[0011] In the second phase unit, the anode of diode valve group two is connected to the anode of thyristor valve group two, the cathode of diode valve group two is connected to the high-voltage side port, and the cathode of thyristor valve group two is grounded. Both thyristor valve group two and diode valve group two are equally divided into two series units, and the connection point of the two series units is the midpoint of the valve group. The active bridge arm S2 is connected to the midpoint of diode valve group two and the midpoint of thyristor valve group two, respectively.

[0012] The anodes of diode valve group one and diode valve group two, as well as one end of the active bridge arm S0, are all connected to the low-voltage side port, and the other end of the active bridge arm S0 is grounded.

[0013] Preferably, both diode valve group one and diode valve group two are composed of several diodes connected in series, and the number of diodes constituting diode valve group one and diode valve group two is the same.

[0014] Preferably, both the first thyristor valve group and the second thyristor valve group are composed of several thyristors connected in series, and the number of thyristors constituting the first thyristor valve group and the second thyristor valve group is the same.

[0015] Preferably, the two series-connected units of the diode valve group are diode D1 and diode D2, and the two series-connected units of the thyristor valve group are thyristor T1 and thyristor T2.

[0016] The anode of diode D1 is connected to the cathode of diode D2, and the anode of diode D2 is connected to the anode of thyristor T1; the cathode of thyristor T1 is connected to the anode of thyristor T2; the cathode of diode D1 is connected to the high-voltage side port, and the cathode of thyristor T2 is grounded; one end of the active bridge arm S1 is connected to the anode of diode D1, and the other end is connected to the cathode of thyristor T1.

[0017] Preferably, the two series-connected units of the diode valve group two are diode D3 and diode D4, and the two series-connected units of the thyristor valve group two are thyristor T3 and thyristor T4;

[0018] The anode of diode D3 is connected to the cathode of diode D4, and the anode of diode D4 is connected to the anode of thyristor T3; the cathode of thyristor T3 is connected to the anode of thyristor T4; the cathode of diode D3 is connected to the high-voltage side port, and the cathode of thyristor T4 is grounded; one end of the active bridge arm S2 is connected to the anode of diode D3, and the other end is connected to the cathode of thyristor T3.

[0019] Preferably, diodes D1, D2, D3 and D4 are each composed of several diodes connected in series, and the number of diodes constituting diodes D1, D2, D3 and D4 is the same. Similarly, thyristors T1, T2, T3 and T4 are each composed of several thyristors connected in series, and the number of thyristors constituting thyristors T1, T2, T3 and T4 is the same.

[0020] Preferably, the number of diodes constituting diodes D1, D2, D3, and D4 is [number missing]. ,in, , These are the high-voltage side and low-voltage side voltages, respectively. This refers to the withstand voltage of a single diode. This is the series derating factor.

[0021] Preferably, the number of thyristors constituting thyristors T1, T2, T3, and T4 is [number missing]. ,in, This is the low-voltage side voltage. This is the blocking voltage for a single thyristor. This is the series derating factor.

[0022] Preferably, the active bridge arms S0, S1 and S2 are each composed of several half-bridge sub-modules connected in series with a bridge arm inductor.

[0023] Preferably, the voltage and current waveforms of the active bridge arm S1 and the active bridge arm S2 are out of phase in time. .

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention places a half-bridge active bridge arm on the low-voltage side for DC-side filtering, under the same capacitor voltage... The number of submodules used in this invention is only [number missing]. ,in, , The voltages are respectively high-voltage and low-voltage, requiring fewer modules, resulting in lower cost and smaller size; furthermore, the two-phase DC / DC converter with active filtering on the low-voltage side only uses two bridge arms for high-voltage side commutation, which can reduce the number of bridge arms used.

[0026] 2. This invention only requires an active bridge arm composed of half-bridge sub-modules, which greatly reduces the number of semiconductors used.

[0027] 3. This invention utilizes the switching of semiconductor valve groups to change the active bridge arm mode in order to maintain the energy balance of the bridge arm. The semiconductor valve group includes a diode valve group and a thyristor valve group, which has the characteristics of low cost, high reliability and low loss.

[0028] 4. This invention ensures that the thyristor can be reliably turned off by utilizing the wide voltage output range of the active bridge arm.

[0029] 5. This invention ensures smooth DC-side current through the high control of current by the active bridge arm, thus eliminating the need for a DC filter. Attached Figure Description

[0030] Figure 1 This is a topology diagram of a two-phase DC / DC converter with low-voltage side active filtering according to the present invention.

[0031] Figure 2 The diagram shows the operating waveforms of a two-phase DC / DC converter with low-voltage side active filtering according to the present invention.

[0032] Figure 3 This is a schematic diagram of the steady-state simulation results of the two-phase DC / DC converter with low-voltage side active filtering according to the present invention; wherein:

[0033] Figure 3 (a) is a schematic diagram of the DC voltage on the high and low voltage sides;

[0034] Figure 3 (b) is a schematic diagram of the DC current on the high and low voltage sides;

[0035] Figure 3 (c) is a schematic diagram of the voltage of active bridge arms S1 and S2;

[0036] Figure 3 (d) is a schematic diagram of the current in the active bridge arms S1 and S2;

[0037] Figure 3 (e) is a schematic diagram of the voltage of the active bridge arm S0;

[0038] Figure 3 (f) is a schematic diagram of the active bridge arm S0;

[0039] Figure 3(g) is a schematic diagram of the capacitor voltage of the active bridge arm S1, S2, and S0 submodules.

[0040] Figure 4 This is a schematic diagram of the dynamic simulation results of the two-phase DC / DC converter with low-voltage side active filtering according to the present invention; wherein:

[0041] Figure 4 (a) is a schematic diagram of the DC voltage on the high and low voltage sides;

[0042] Figure 4 (b) is a schematic diagram of the DC current on the high and low voltage sides;

[0043] Figure 4 (c) is a schematic diagram of the voltage of active bridge arms S1 and S2;

[0044] Figure 4 (d) is a schematic diagram of the current in the active bridge arms S1 and S2;

[0045] Figure 4 (e) is a schematic diagram of the voltage of the active bridge arm S0;

[0046] Figure 4 (f) is a schematic diagram of the active bridge arm S0;

[0047] Figure 4 (g) is a schematic diagram of the capacitor voltage of the active bridge arm S1, S2, and S0 submodules. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to the accompanying drawings: This embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation methods are given, but the protection scope of the present invention is not limited to the following embodiments.

[0049] like Figure 1 As shown, this embodiment involves a two-phase DC / DC converter with active filtering on the low-voltage side, comprising three active bridge arms composed of several half-bridge sub-modules, their bridge arm inductors, thyristor valve groups, and diode valve groups. It includes: a first phase unit, a second phase unit, and an active bridge arm S0 connected in parallel on the low-voltage side; each phase unit has the same structure and is independent of the others; both the first phase unit and the second phase unit include: an active bridge arm, a diode valve group, and a thyristor valve group.

[0050] In the first phase unit, the anode of diode valve group one is connected to the anode of thyristor valve group one, the cathode of diode valve group one is connected to the high-voltage side port, the cathode of thyristor valve group one is grounded, and thyristor valve group one and diode valve group one are each equally divided into two series units. The connection point of the two series units is the midpoint of the valve group. The active bridge arm S1 is connected to the midpoint of diode valve group one and the midpoint of thyristor valve group one, respectively.

[0051] In the second phase unit, the anode of diode valve group two is connected to the anode of thyristor valve group two, the cathode of diode valve group two is connected to the high-voltage side port, and the cathode of thyristor valve group two is grounded. Both thyristor valve group two and diode valve group two are equally divided into two series units, and the connection point of the two series units is the midpoint of the valve group. The active bridge arm S2 is connected to the midpoint of diode valve group two and the midpoint of thyristor valve group two, respectively.

[0052] The anodes of diode valve group one and diode valve group two, as well as one end of the active bridge arm S0, are all connected to the low-voltage side port, and the other end of the active bridge arm S0 is grounded.

[0053] Both diode valve group one and diode valve group two are composed of several diodes connected in series, and the number of diodes constituting diode valve group one and diode valve group two is the same.

[0054] Both the first thyristor valve group and the second thyristor valve group are composed of several thyristors connected in series, and the number of thyristors constituting the first thyristor valve group and the second thyristor valve group is the same.

[0055] The two series-connected units of the diode valve group are diode D1 and diode D2, and the two series-connected units of the thyristor valve group are thyristor T1 and thyristor T2. The anode of diode D1 is connected to the cathode of diode D2, and the anode of diode D2 is connected to the anode of thyristor T1. The cathode of thyristor T1 is connected to the anode of thyristor T2. The cathode of diode D1 is connected to the high-voltage side port, and the cathode of thyristor T2 is grounded. One end of the active bridge arm S1 is connected to the anode of diode D1, and the other end is connected to the cathode of thyristor T1.

[0056] The two series-connected units of the diode valve group two are diode D3 and diode D4, and the two series-connected units of the thyristor valve group two are thyristor T3 and thyristor T4; the anode of diode D3 is connected to the cathode of diode D4, and the anode of diode D4 is connected to the anode of thyristor T3; the cathode of thyristor T3 is connected to the anode of thyristor T4; the cathode of diode D3 is connected to the high-voltage side port, and the cathode of thyristor T4 is grounded; one end of the active bridge arm S2 is connected to the anode of diode D3, and the other end is connected to the cathode of thyristor T3.

[0057] Diodes D1, D2, D3, and D4 are each composed of several diodes connected in series, and the number of diodes constituting diodes D1, D2, D3, and D4 is the same. Similarly, thyristors T1, T2, T3, and T4 are each composed of several thyristors connected in series, and the number of thyristors constituting thyristors T1, T2, T3, and T4 is the same. The number of diodes constituting diodes D1, D2, D3, and D4 is... ,in, , These are the high-voltage side and low-voltage side voltages, respectively. This refers to the withstand voltage of a single diode. This is the series derating factor. The number of thyristors constituting thyristors T1, T2, T3, and T4 is... ,in, This is the blocking voltage for a single thyristor. This is the series derating factor.

[0058] The active bridge arms S0, S1, and S2 are each composed of several half-bridge sub-modules connected in series with a bridge arm inductor. The voltage and current waveforms of the active bridge arms S1 and S2 are out of phase by T / 2 in time.

[0059] like Figure 1 As shown, where, , , and These represent the voltages and currents of the active bridge arms S0, S1, and S2, respectively. , These are the high-voltage side and low-voltage side voltages, respectively. , These are the currents on the high-voltage side and the low-voltage side, respectively.

[0060] like Figure 2 As shown, this invention discloses a two-phase DC / DC converter with active filtering on the low-voltage side. It uses two-phase bridge arms to control the high-voltage side current to remain constant and performs commutation on the high-voltage side. Within one cycle, it experiences 14 operating states and two commutation stages, as detailed below:

[0061] During this period, diodes D1 and D3, as well as thyristors T1 and T3, are turned on, and bridge arms S1 and S2 commutate on the high-voltage side. The two bridge arms are connected in series between the high and low voltage sides. The output voltage of bridge arm S1 is... ,Voltage Inductance applied to bridge arm This causes the current borne by bridge arm S1 to decrease linearly from 0 to... Bridge arm S2 output voltage ,Voltage Inductance applied to bridge arm This causes the current carried by bridge arm S2 to shift from... As the current linearly rises to 0, the rates of change of bridge arms S1 and S2 are the same, marking the completion of one commutation cycle for bridge arms S1 and S2. Bridge arm S0 is connected in parallel on the low-voltage side for low-voltage filtering, and the output voltage... , bear current ;

[0062] During this period, diode D1 and thyristor T1 are turned on, bridge arm S1 is connected in series between the high and low voltage sides, and bridge arm S2 is open-circuited to the DC side. Bridge arm S1 output voltage... The current it carries is The output voltage of bridge arm S2 is from linearly decreasing to To prepare for the conduction of diode D4 and thyristor T4, bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... , bear current ;

[0063] During this period, thyristor T4 is triggered and turned on, bridge arm S1 is connected in series between the high and low voltage sides, and bridge arm S2 is connected in parallel with the low voltage side. The output voltage of bridge arm S1 is... The current it carries is Bridge arm S2 output voltage ,Voltage Inductance applied to bridge arm This causes the current in bridge arm S2 to rise linearly from 0 to... The bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... ,Voltage Inductance applied to bridge arm The current in bridge arm S0 is caused to flow from... linearly decreasing to ;

[0064] During this period, bridge arm S1 is connected in series between the high and low voltage sides, while bridge arm S2 is connected in parallel with the low voltage side. The output voltage of bridge arm S1... The current it carries is Bridge arm S2 output voltage The current it carries is The bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... The current it carries is ;

[0065] During this period, bridge arm S1 is connected in series between the high and low voltage sides, and bridge arm S2 is connected in parallel with the low voltage side. The output voltage of bridge arm S1 is... The current it carries is Bridge arm S2 output voltage ,Voltage Inductance applied to bridge arm This causes the current in bridge arm S2 to flow from... The voltage drops linearly to 0, and bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, resulting in an output voltage... ,Voltage Inductance applied to bridge arm The current in bridge arm S0 is caused to flow from... linearly rising to ;

[0066] During this period, bridge arm S1 is connected in series between the high and low voltage sides, while bridge arm S2 is in an open circuit state with respect to the DC side. The output voltage of bridge arm S1... The current it carries is The output voltage of bridge arm S2 is from linearly rising to During this period, thyristor T2 is constantly subjected to reverse voltage, thus reliably turning off. Bridge arm S0 is connected in parallel on the low-voltage side for low-voltage filtering, and the output voltage... , bear current ;

[0067] During this period, thyristor T3 is triggered and turns on, and bridge arms S1 and S2 are connected in series between the high and low voltage sides. The output voltage of bridge arm S1... ,Voltage Inductance applied to bridge arm This causes the current in its bridge arm to flow from... The voltage of bridge arm S2 rises linearly to 0 from... ,Voltage Inductance applied to bridge arm This causes the bridge arm current to decrease linearly from 0 to The bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... , bear current ;

[0068] During this period, bridge arm S2 is connected in series between the high and low voltage sides, while bridge arm S1 of the entire bridge is in an open circuit state with respect to the DC side. The output voltage of bridge arm S2... The current it carries is The output voltage of bridge arm S1 is from linearly decreasing to To prepare for the thyristor T2 to conduct, bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... , bear current ;

[0069] During this period, thyristor T2 is triggered and turns on, bridge arm S2 is connected in series between the high and low voltage sides, and bridge arm S1 of the full bridge is connected in parallel with the low voltage side. The output voltage of bridge arm S2 is... The current it carries is Bridge arm S1 output voltage ,Voltage Inductance applied to bridge arm This causes the current in bridge arm S1 to rise linearly from 0 to... The bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... ,Voltage Inductance applied to bridge arm The current in bridge arm S0 is caused to flow from... linearly decreasing to ;

[0070] During this period, bridge arm S2 is connected in series between the high and low voltage sides, while bridge arm S1 is connected in parallel with the low voltage side. The output voltage of bridge arm S2 is... The current it carries is Bridge arm S1 output voltage The current it carries is The bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... The current it carries is ;

[0071] During this period, bridge arm S2 is connected in series between the high and low voltage sides, while bridge arm S1 is connected in parallel with the low voltage side. The output voltage of bridge arm S2 is... The current it carries is Bridge arm S1 output voltage ,Voltage Inductance applied to bridge arm This causes the current in bridge arm S1 to flow from... The voltage drops linearly to 0, and bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, resulting in an output voltage... ,Voltage Inductance applied to bridge arm The current in bridge arm S0 is caused to flow from... linearly rising to ;

[0072] During this period, bridge arm S2 is connected in series between the high and low voltage sides, while bridge arm S1 of the entire bridge is in an open circuit state with respect to the DC side. The output voltage of bridge arm S2... The current it carries is Bridge arm S1 output voltage linearly rising to This prepares for the thyristor T1 to conduct. Bridge arm S0 is connected in parallel on the low-voltage side for low-voltage side filtering, and the output voltage... , bear current .

[0073] Example 1

[0074] To verify the functionality of the low-voltage side active filtering two-phase DC / DC converter of this invention, a 300MW rated power high-voltage side active filtering two-phase DC / DC converter model was built in Simulink for simulation verification. The DC grids on the low-voltage and high-voltage sides were simulated using voltage sources, designed to be 100kV and 400kV respectively, with a rated transformer ratio of 4. The rated voltage of the submodule capacitors was 2kV. Specific parameters are shown in Table 1.

[0075] Table 1. Specific simulation parameters and values.

[0076]

[0077] Figure 3 The steady-state simulation results of a two-phase DC / DC converter with active filtering on the low-voltage side are presented. The high-voltage and low-voltage DC currents are smoothed at 750A and 3000A, respectively. The voltages of bridge arms S1 and S2 switch between 300kV and 100kV, controlling the bridge arm currents to be trapezoidal waves with amplitudes of -750A and 2567A. Through the active filtering effect of bridge arm S0 on the low-voltage side, a smooth and continuous output of the low-voltage side current is achieved.

[0078] Figure 4 The dynamic simulation results of a two-phase DC / DC converter with active filtering on the low-voltage side are presented. Within [0.4s, 0.5s], the converter transfers 300MW of rated power from the low-voltage side to the high-voltage side. Within [0.5s, 0.6s], the DC current command on the high-voltage side linearly decreases from 750A to 0A. Within [0.6s, 0.7s], the converter does not transfer power. Within [0.7s, 0.8s], the DC current command on the high-voltage side linearly increases from 0A to 750A. Within [0.8s, 0.9s], the converter transfers 300MW of rated power from the low-voltage side to the high-voltage side. Throughout the entire dynamic process, the DC currents on both the high and low voltage sides remain smooth and continuous, and the DC component of the capacitor voltage of each bridge arm submodule remains stable at the rated value of 2000V.

[0079] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A two-phase DC / DC converter with low-voltage side active filtering, characterized in that, include: First phase unit, second phase unit and active bridge arm S0; Both the first phase unit and the second phase unit include: an active bridge arm, a diode valve group, and a thyristor valve group; In the first phase unit, the anode of diode valve group one is connected to the anode of thyristor valve group one, the cathode of diode valve group one is connected to the high-voltage side port, the cathode of thyristor valve group one is grounded, and thyristor valve group one and diode valve group one are each equally divided into two series units. The connection point of the two series units is the midpoint of the valve group. The active bridge arm S1 is connected to the midpoint of diode valve group one and the midpoint of thyristor valve group one, respectively. In the second phase unit, the anode of diode valve group two is connected to the anode of thyristor valve group two, the cathode of diode valve group two is connected to the high-voltage side port, and the cathode of thyristor valve group two is grounded. Both thyristor valve group two and diode valve group two are equally divided into two series units, and the connection point of the two series units is the midpoint of the valve group. The active bridge arm S2 is connected to the midpoint of diode valve group two and the midpoint of thyristor valve group two, respectively. The anodes of diode valve group one and diode valve group two, as well as one end of the active bridge arm S0, are all connected to the low-voltage side port, and the other end of the active bridge arm S0 is grounded.

2. A two-phase DC / DC converter with low-voltage side active filtering according to claim 1, characterized in that, Both diode valve group one and diode valve group two are composed of several diodes connected in series, and the number of diodes constituting diode valve group one and diode valve group two is the same.

3. A two-phase DC / DC converter with low-voltage side active filtering according to claim 1, characterized in that, Both the first thyristor valve group and the second thyristor valve group are composed of several thyristors connected in series, and the number of thyristors constituting the first thyristor valve group and the second thyristor valve group is the same.

4. A two-phase DC / DC converter with low-voltage side active filtering according to claim 1, characterized in that, The two series units of the diode valve group one are diode D1 and diode D2, and the two series units of the thyristor valve group one are thyristor T1 and thyristor T2. The anode of diode D1 is connected to the cathode of diode D2, and the anode of diode D2 is connected to the anode of thyristor T1; the cathode of thyristor T1 is connected to the anode of thyristor T2; the cathode of diode D1 is connected to the high-voltage side port, and the cathode of thyristor T2 is grounded; one end of the active bridge arm S1 is connected to the anode of diode D1, and the other end is connected to the cathode of thyristor T1.

5. A two-phase DC / DC converter with low-voltage side active filtering according to claim 4, characterized in that, The two series units of the diode valve group two are diode D3 and diode D4, and the two series units of the thyristor valve group two are thyristor T3 and thyristor T4. The anode of diode D3 is connected to the cathode of diode D4, and the anode of diode D4 is connected to the anode of thyristor T3; the cathode of thyristor T3 is connected to the anode of thyristor T4; the cathode of diode D3 is connected to the high-voltage side port, and the cathode of thyristor T4 is grounded; one end of the active bridge arm S2 is connected to the anode of diode D3, and the other end is connected to the cathode of thyristor T3.

6. A two-phase DC / DC converter with low-voltage side active filtering according to claim 5, characterized in that, The diodes D1, D2, D3, and D4 are each composed of several diodes connected in series, and the number of diodes constituting diodes D1, D2, D3, and D4 is the same. The thyristors T1, T2, T3, and T4 are each composed of several thyristors connected in series, and the number of thyristors constituting thyristors T1, T2, T3, and T4 is the same.

7. A two-phase DC / DC converter with low-voltage side active filtering according to claim 6, characterized in that, The number of diodes constituting diodes D1, D2, D3, and D4 is: ,in, , These are the high-voltage side and low-voltage side voltages, respectively. This refers to the voltage rating of a single diode. This is the series derating factor.

8. A two-phase DC / DC converter with low-voltage side active filtering according to claim 6, characterized in that, The number of thyristors constituting thyristors T1, T2, T3, and T4 is: ,in, This is the low-voltage side voltage. This is the blocking voltage for a single thyristor. This is the series derating factor.

9. A two-phase DC / DC converter with low-voltage side active filtering according to claim 1, characterized in that, The active bridge arms S0, S1 and S2 are each composed of several half-bridge sub-modules connected in series with a bridge arm inductor.

10. A two-phase DC / DC converter with low-voltage side active filtering according to claim 9, characterized in that, The voltage and current waveforms of the active bridge arm S1 and the active bridge arm S2 are out of phase in time. .

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