High-frequency DC / DC converter circuit, converter module and railway vehicle

Abstract

The utility model provides a high-frequency DC / DC converter circuit, a converter module and a railway vehicle. A high-frequency DC / DC converter circuit for converting power from the upstream and outputting the converted power to the downstream, the high-frequency DC / DC converter circuit comprising: an inverter circuit unit which includes a half-bridge inverter circuit and inverts direct current from the upstream into alternating current; a transformation circuit unit which includes a plurality of high-frequency transformers and which transforms the alternating current from the inverter circuit unit, the primary windings of the plurality of high-frequency transformers being connected in series to the half-bridge inverter circuit via a resonant inductor; and a rectifying circuit unit including a rectifying circuit connected to the secondary winding of each of the plurality of high-frequency transformers of the transformer circuit unit, the secondary windings of the plurality of high-frequency transformers being connected to the rectifying circuit so as to be connected in parallel with each other. A rectifying circuit is used for rectifying alternating current from a plurality of high-frequency transformers into direct current, and the direct current is superposed and output to the downstream.

Description

Technical Field

[0001] The utility model relates to a high-frequency DC / DC current conversion circuit, and further relates to a high-frequency DC / DC current conversion module for railway vehicles applying the high-frequency DC / DC current conversion circuit and a railway vehicle using the high-frequency DC / DC current conversion module for railway vehicles. Background Art

[0002] For railway vehicles such as electric locomotives that use electricity from the power supply grid to operate, the power system includes a traction power supply system and an auxiliary power supply system. Among them, the traction power supply system supplies power from the power supply grid to the traction motor to drive the railway vehicle. In addition, the auxiliary power supply system is used to convert the power from the power supply grid into power that can be used by on-board electrical equipment such as fans, water pumps, lighting, air conditioners, refrigerators, etc., so that these on-board electrical equipment can operate.

[0003] The voltage of the railway power supply network is usually very high, and after conversion by, for example, the intermediate DC link, it is also very high (for example, in my country, it is usually 1800V to 3600V). The on-board electrical equipment connected downstream of the auxiliary power supply system are all low-voltage loads, and they need to be isolated from the high-voltage side main circuit, such as the intermediate DC link.

[0004] Currently, there is a technology that uses high-frequency transformers for isolation. Specifically, Figure 6 As shown, the representative circuit structure of this isolation scheme mainly includes an upstream full-bridge inverter circuit InC', a midstream high-frequency transformer circuit TrC' and a downstream rectifier circuit ReC'. The high-frequency transformer circuit TrC' is connected to the full-bridge inverter circuit InC' via a resonant inductor Lr' to form an LLC resonant circuit. The high-frequency transformer circuit TrC' is used to isolate the low-voltage load from the high-voltage side main circuit.

[0005] In the above circuit structure, the purchase cost of the semiconductor switch (MOSFET, IGBT, etc.) used in the inverter circuit accounts for a large proportion of the total cost of the device using the circuit structure. In addition, generally speaking, the service life of the semiconductor switch is shorter than the service life of the high-frequency transformer. During the life cycle of the device, the semiconductor switch may need to be replaced, which will also incur a lot of costs.

[0006] Therefore, from the perspective of cost saving, for the inverter circuit in the above circuit structure, the half-bridge inverter circuit is more advantageous than the existing full-bridge inverter circuit.

[0007] However, in the case of a half-bridge inverter circuit, the equivalent input voltage applied to the primary winding of the transformer is only half of that of a full-bridge inverter circuit, causing the current flowing in the high-frequency transformer to increase to twice that of a full-bridge inverter circuit. According to Joule's law, Q = I2 Rt, the heat generated by the high-frequency transformer will increase significantly compared with the full-bridge inverter circuit, making the heat dissipation of the high-frequency transformer very difficult to design. It is for this reason that there is no precedent in the prior art for using the half-bridge inverter circuit in a low-voltage, high-power (typically, high-power above 100kW) high-frequency DC / DC converter circuit, and there is still room for improvement in terms of cost saving. Utility Model Content

[0008] The utility model is proposed in view of the above-mentioned actual situation, and its purpose is to provide a high-frequency DC / DC conversion circuit, a high-frequency DC / DC conversion module for railway vehicles, and a railway vehicle using the high-frequency DC / DC conversion module for railway vehicles, which can reduce the overall cost.

[0009] To this end, the utility model provides a high-frequency DC / DC conversion circuit for converting electric power from upstream and then outputting it downstream, comprising: an inverter circuit portion, including a half-bridge inverter circuit, inverting the direct current from upstream into alternating current; a transformer circuit portion, including a plurality of high-frequency transformers, transforming the alternating current from the inverter circuit portion, the primary windings of the plurality of high-frequency transformers being connected in series with each other via a resonant inductor to the half-bridge inverter circuit; and a rectifier circuit portion, including a rectifier circuit connected to the secondary windings of the plurality of high-frequency transformers of the transformer circuit portion, the secondary windings of the plurality of high-frequency transformers being connected in parallel with the rectifier circuit, and the rectifier circuit is used to rectify the alternating current from the plurality of high-frequency transformers into direct current and output the direct current in a superimposed manner downstream.

[0010] According to this technical solution, on the one hand, since the inverter circuit part uses a half-bridge inverter circuit, compared with the case of using an inverter circuit with a full-bridge structure, the number of semiconductor switches (MOSFET, IGBT, etc.) can be reduced, and the number of control circuits supporting the semiconductor switches can be reduced accordingly. Therefore, the purchase cost of the semiconductor switch part and the maintenance cost that may occur in the later stage can be reduced, thereby reducing the overall cost of the high-frequency DC / DC conversion circuit.

[0011] On the other hand, since multiple high-frequency transformers are used, the total power of the circuit can be shared by multiple high-frequency transformers, and the increased heat generated by the use of the half-bridge inverter circuit can be shared among multiple high-frequency transformers. Moreover, since the primary windings of multiple high-frequency transformers are connected in series, the equivalent excitation inductance and resonant inductance required by the circuit are shared by the multiple high-frequency transformers, and the power density is also reduced, which is conducive to suppressing the increase in the heat generated by the high-frequency transformer. Therefore, the increase in the heat generated by the high-frequency transformer monomer can be suppressed within a relatively small range that can be controlled by commonly used heat dissipation technology (for example, the heat dissipation technology of attaching a water cooling plate to the bottom surface of each high-frequency transformer), thereby ensuring that the cost reduced by reducing the semiconductor switches of the inverter circuit unit is greater than the cost increased by increasing the number of high-frequency transformers and strengthening the heat dissipation of the high-frequency transformers.

[0012] In this way, the overall cost of the high-frequency DC / DC converter circuit can be reduced.

[0013] In addition, according to the above technical solution, the following beneficial effects can also be achieved:

[0014] 1) Since multiple high-frequency transformers are arranged in a manner that the primary windings are connected in series, the magnitude of the current flowing in the primary windings of the multiple high-frequency transformers is always the same, which can avoid the problem of power imbalance between the multiple high-frequency transformers.

[0015] 2) By connecting the primary windings of a plurality of high-frequency transformers in series, when the rectifying circuit unit includes a plurality of rectifying circuits corresponding to the plurality of high-frequency transformers, it is also possible to solve the problem of power imbalance that may occur in the plurality of rectifying circuits.

[0016] In addition, preferably, the switch tube of the half-bridge inverter circuit is a silicon carbide field effect transistor.

[0017] According to this technical solution, it is easier to achieve soft switching under high-frequency conditions, greatly reducing device losses, which is beneficial to reducing the core volume and number of turns of the winding coils of each high-frequency transformer in the transformer circuit unit, thereby achieving lightweight and miniaturization of each high-frequency transformer and then the transformer circuit unit as a whole.

[0018] In addition, in the present invention, optionally, a plurality of rectifier circuits are provided, the plurality of rectifier circuits are respectively connected to the secondary winding of the corresponding high-frequency transformer, and the plurality of rectifier circuits are connected to each other in parallel, and the rectifier circuit unit utilizes the plurality of rectifier circuits to rectify the alternating current from the plurality of high-frequency transformers into direct current respectively and output it in a superimposed manner to the downstream.

[0019] According to this technical solution, the rectifier circuit can be easily realized.

[0020] In addition, preferably, two high-frequency transformers are provided.

[0021] According to this technical solution, the overall cost of the high-frequency DC / DC converter circuit can be reduced while miniaturizing the high-frequency DC / DC converter circuit.

[0022] In addition, the utility model also provides a high-frequency DC / DC conversion module for railway vehicles, which is used to convert the power from the upstream and output it to the downstream in the auxiliary power supply system, and comprises: an inverter unit, including a half-bridge inverter circuit, which inverts the DC power from the upstream into AC power; a transformer unit, including multiple high-frequency transformers, which transforms the AC power from the inverter unit, and the primary windings of the multiple high-frequency transformers are connected to the half-bridge inverter circuit in series via a resonant inductor; and a rectifier unit, including a rectifier circuit connected to the secondary windings of the multiple high-frequency transformers of the transformer unit, and the secondary windings of the multiple high-frequency transformers are connected to the rectifier circuit in parallel with each other, and the rectifier circuit is used to rectify the AC power from the multiple high-frequency transformers into DC power and output the DC power in a superimposed manner downstream.

[0023] According to this technical solution, on the one hand, since the inverter unit uses a half-bridge inverter circuit, compared with the case of using an inverter circuit with a full-bridge structure, the number of semiconductor switches (MOSFET, IGBT, etc.) can be reduced, and the number of control circuits supporting the semiconductor switches can be reduced accordingly. Therefore, the purchase cost of the semiconductor switch part and the maintenance cost that may occur in the later stage can be reduced, thereby reducing the overall cost of the high-frequency DC / DC converter module.

[0024] On the other hand, since multiple high-frequency transformers are used, the total power of the circuit can be shared by multiple high-frequency transformers, and the increased heat generated by the use of the half-bridge inverter circuit can be shared among multiple high-frequency transformers. Moreover, since the primary windings of multiple high-frequency transformers are connected in series, the equivalent excitation inductance and resonant inductance required by the circuit are shared by the multiple high-frequency transformers, and the power density is also reduced, which is conducive to suppressing the increase in the heat generated by the high-frequency transformer. Therefore, the increase in the heat generated by the high-frequency transformer monomer can be suppressed within a relatively small range that can be controlled by commonly used heat dissipation technology (for example, the heat dissipation technology of fitting a water cooling plate on the bottom surface of each high-frequency transformer), thereby ensuring that the cost reduced by reducing the semiconductor switch of the inverter unit is greater than the cost increased by increasing the number of high-frequency transformers and strengthening the heat dissipation of the high-frequency transformer.

[0025] In this way, the overall cost of the high-frequency DC / DC converter module can be reduced.

[0026] In addition, according to the above technical solution, the following beneficial effects can also be achieved:

[0027] 1) Since multiple high-frequency transformers are arranged in a manner that the primary windings are connected in series, the magnitude of the current flowing in the primary windings of the multiple high-frequency transformers is always the same, which can avoid the problem of power imbalance between the multiple high-frequency transformers.

[0028] 2) By connecting the primary windings of multiple high-frequency transformers in series, when the rectifying unit includes multiple rectifying circuits corresponding to the multiple high-frequency transformers, the problem of power imbalance that may occur in the multiple rectifying circuits can also be solved.

[0029] In addition, preferably, the switch tube of the half-bridge inverter circuit is a silicon carbide field effect transistor.

[0030] According to this technical solution, it is easier to achieve soft switching under high-frequency conditions, greatly reducing device losses, which is beneficial to reducing the core volume and number of turns of each high-frequency transformer of the transformer unit, thereby achieving lightweight and miniaturization of each high-frequency transformer and then the transformer unit as a whole.

[0031] In addition, preferably, the resonant inductor is a leakage inductance respectively integrated in the winding of each high-frequency transformer, and the leakage inductances integrated in the winding of each high-frequency transformer are the same.

[0032] According to this technical solution, by integrating the resonant inductor as a leakage inductor into the winding of the high-frequency transformer, a compact design of the high-frequency transformer itself and the high-frequency DC / DC converter module as a whole can be achieved, compared with the case where the resonant inductor is formed using an external wire.

[0033] In addition, in the present invention, optionally, a plurality of rectifier circuits are provided, and the plurality of rectifier circuits are respectively connected to the secondary winding of the corresponding high-frequency transformer, and the plurality of rectifier circuits are connected to each other in parallel. The rectifier unit utilizes the plurality of rectifier circuits to rectify the alternating current from the plurality of high-frequency transformers into direct current respectively and output it in a superimposed manner to the downstream.

[0034] According to this technical solution, the rectifier circuit can be easily realized.

[0035] In addition, preferably, two high-frequency transformers are provided.

[0036] According to the technical solution, the overall cost of the high-frequency DC / DC converter module can be reduced while miniaturizing the high-frequency DC / DC converter module.

[0037] In addition, the utility model also provides a railway vehicle, which comprises: a converter cabinet; and a high-frequency DC / DC converter module for railway vehicles in any of the above schemes, which is accommodated in the converter cabinet and converts the power from the upstream and outputs it to the downstream load.

[0038] According to this technical solution, the same technical effect as the high-frequency DC / DC converter module for railway vehicles in any of the above solutions can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram showing a high-frequency DC / DC converter circuit in the first embodiment.

[0040] Figure 2 This is a schematic diagram showing an example of currents flowing through primary windings of a plurality of high-frequency transformers included in the high-frequency DC / DC converter circuit in the first embodiment.

[0041] Figure 3 1 is a schematic diagram showing the overall structure of a high-frequency DC / DC converter module for railway vehicles in the second embodiment.

[0042] Figure 4 This is a schematic diagram showing a high-frequency DC / DC converter circuit in a modified form.

[0043] Figure 5 This is a schematic diagram showing a high-frequency DC / DC converter circuit in a modified form.

[0044] Figure 6 It is a schematic diagram showing a high-frequency DC / DC converter circuit in the prior art. DETAILED DESCRIPTION

[0045] The following embodiments of the present invention are described. Note that the following embodiments are listed to facilitate understanding of the present invention and are not intended to limit the present invention.

[0046] In addition, in this specification, ordinal expressions such as "first", "second", and "third" are sometimes used, but these ordinal expressions are only for distinguishing different things and do not represent a fixed order of appearance of things or their superiority or inferiority.

[0047] In addition, the term “connected” means electrically connected unless otherwise specified.

[0048] <1> First embodiment

[0049] [1-1] Overall structure

[0050] Hereinafter, the overall configuration of a high-frequency DC / DC converter circuit in a first embodiment will be described with reference to the drawings.

[0051] The high-frequency DC / DC converter circuit in the first embodiment is used to convert the electric power (direct current) from the upstream and output it to the downstream (for example, an electric load).

[0052] Figure 1 It is a schematic diagram showing a high-frequency DC / DC converter circuit in the first embodiment.

[0053] like Figure 1 As shown, the high-frequency DC / DC converter circuit in the first embodiment mainly includes an inverter circuit portion InC, a transformer circuit portion TrC, and a rectifier circuit portion ReC.

[0054] The inverter circuit unit InC is used to invert direct current power input from an upstream direct current source via the positive input terminal Pi and the negative input terminal Ni into alternating current power.

[0055] Specifically, the inverter circuit unit InC has a half-bridge inverter circuit including a first bridge arm provided with a support capacitor FC1, a second bridge arm provided with two resonant capacitors RC1 and RC2, and a third bridge arm provided with two semiconductor switch modules SW1 and SW2.

[0056] The support capacitor FC1 can eliminate the ripple in the input DC and stabilize the DC input voltage.

[0057] The resonant capacitors RC1 and RC2 constitute an LLC resonant circuit together with the magnetizing inductance Lm1 and the resonant inductance Lr1 of the high-frequency transformer Tr1 and the magnetizing inductance Lm2 and the resonant inductance Lr2 of the high-frequency transformer Tr2 included in the transformer circuit portion TrC described later.

[0058] The two semiconductor switch modules SW1 and SW2 operate at a predetermined switching frequency and duty ratio under the control of a control circuit (not shown) to maintain the stability of the output voltage.

[0059] The semiconductor switch module SW1 can be composed of a metal oxide semiconductor field effect transistor (MOSFET) and a diode connected in parallel with each other, wherein the drain of the metal oxide semiconductor field effect transistor is connected to the cathode of the diode, and the source of the metal oxide semiconductor field effect transistor is connected to the anode of the diode. The metal oxide semiconductor field effect transistor is used to realize the switching function, and the diode is used to prevent the metal oxide semiconductor field effect transistor from reverse breakdown.

[0060] In addition, the drain of the metal oxide semiconductor field effect transistor constituting the semiconductor switch module SW1 and the cathode of the diode constituting the semiconductor switch module SW1 are commonly connected to the positive input terminal Pi, and the source of the metal oxide semiconductor field effect transistor constituting the semiconductor switch module SW1 and the anode of the diode constituting the semiconductor switch module SW1 are commonly connected to the drain of the metal oxide semiconductor field effect transistor constituting the semiconductor switch module SW2 described later and the cathode of the diode constituting the semiconductor switch module SW2.

[0061] In addition, as the metal oxide semiconductor field effect transistor constituting the semiconductor switch module SW1, a silicon carbide field effect transistor (SiC-MOSFET) can be used. In this way, it is easier to achieve soft switching under high frequency conditions, which is beneficial to the reduction of the core volume and the number of turns of the winding coil of the high-frequency transformer Tr1 and Tr2 of the transformer circuit part TrC described later, and realizes the lightweight and miniaturization of the transformer.

[0062] Similarly, the semiconductor switch module SW2 can be composed of a metal oxide semiconductor field effect transistor and a diode connected in parallel with each other, wherein the drain of the metal oxide semiconductor field effect transistor is connected to the cathode of the diode, and the source of the metal oxide semiconductor field effect transistor is connected to the anode of the diode. The metal oxide semiconductor field effect transistor is used to realize the switching function, and the diode is used to prevent the metal oxide semiconductor field effect transistor from reverse breakdown.

[0063] In addition, the source of the metal oxide semiconductor field effect transistor and the anode of the diode in the semiconductor switch module SW2 are commonly connected to the negative input terminal Ni.

[0064] In addition, as the metal oxide semiconductor field effect transistor constituting the semiconductor switch module SW2, a silicon carbide field effect transistor can also be used. In this way, it is easier to achieve soft switching under high frequency conditions, which is beneficial to reducing the core volume and the number of turns of the winding coil of the high-frequency transformer Tr1 and Tr2 of the transformer circuit part TrC described later, and realizing the lightweight and miniaturization of the transformer.

[0065] The transformer circuit section TrC forms an LLC resonant circuit with the inverter circuit section InC and transforms the AC power from the inverter circuit section InC. The transformer circuit section TrC also serves to isolate the high voltage upstream side from the low voltage downstream side.

[0066] The transformer circuit section TrC includes two high-frequency transformers Tr1 and Tr2.

[0067] One terminal of the primary winding of the high-frequency transformer Tr1 is connected to the midpoint of the two semiconductor switch modules SW1 and SW2 on the third bridge arm of the inverter circuit part InC via the resonant inductor Lr1, and the other terminal of the primary winding of the high-frequency transformer Tr1 is connected to one terminal of the primary winding of the high-frequency transformer Tr2 via the resonant inductor Lr2. The other terminal of the primary winding of the high-frequency transformer Tr2 is connected to the midpoint of the two resonant capacitors RC1 and RC2 on the second bridge arm of the inverter circuit part InC.

[0068] In other words, the primary winding of the high-frequency transformer Tr1 and the primary winding of the high-frequency transformer Tr2 are connected in series, and the primary windings of the two high-frequency transformers Tr1 and Tr2 are connected to the half-bridge inverter circuit of the inverter circuit part InC via the resonant inductors Lr1 and Lr2.

[0069] In addition, Figure 1 In the figure, reference symbol “ Lm1 ” represents the magnetizing inductance of the high-frequency transformer Tr1 , and reference symbol “ Lm2 ” represents the magnetizing inductance of the high-frequency transformer Tr2 .

[0070] In addition, the secondary winding of the high-frequency transformer Tr1 and the secondary winding of the high-frequency transformer Tr2 are provided in parallel with each other, which will be described later.

[0071] The rectifier circuit unit ReC is used to rectify the AC power from the two high-frequency transformers Tr1 and Tr2 of the transformer circuit unit TrC into DC power and output the DC power in a superimposed manner downstream.

[0072] The rectifying circuit unit ReC includes a rectifying circuit, and the rectification described above is realized by the rectifying circuit.

[0073] In the present embodiment, the rectifier circuit portion ReC includes two rectifier circuits corresponding to the two high-frequency transformers Tr1 and Tr2 provided in the transformer circuit portion TrC.

[0074] like Figure 1 As shown, the two rectifier circuits respectively include a fourth bridge arm provided with two diode switches RD1 and RD3 and a fifth bridge arm provided with two diode switches RD2 and RD4, forming a full-bridge rectifier circuit. In the fourth bridge arm, the cathode of the diode switch RD1 is connected to the positive output terminal Po, the anode of the diode switch RD1 is connected to the cathode of the diode switch RD3, and the anode of the diode switch RD3 is connected to the negative output terminal No. In the fifth bridge arm, the cathode of the diode switch RD2 is connected to the positive output terminal Po, the anode of the diode switch RD2 is connected to the cathode of the diode switch RD4, and the anode of the diode switch RD4 is connected to the negative output terminal No.

[0075] In addition, the two rectifier circuits are connected in parallel to each other and share the filter capacitor FC2.

[0076] Furthermore, in the rectifier circuit, a fast recovery diode can be used as a diode switch.

[0077] One connector of the secondary winding of the high-frequency transformer Tr1 of the transformer circuit part TrC is connected to the midpoint of the two diode switches RD1 and RD3 on the fourth bridge arm of the rectifier circuit on the upper side of the figure of the rectifier circuit part ReC, and the other connector of the secondary winding of the high-frequency transformer Tr1 is connected to the midpoint of the two diode switches RD2 and RD4 on the fifth bridge arm of the rectifier circuit.

[0078] One connector of the secondary winding of the high-frequency transformer Tr2 of the transformer circuit part TrC is connected to the midpoint of the two diode switches RD1 and RD3 on the fourth bridge arm of the rectifier circuit on the lower side of the figure of the rectifier circuit part ReC, and the other connector of the secondary winding of the high-frequency transformer Tr2 is connected to the midpoint of the two diode switches RD2 and RD4 on the fifth bridge arm of the rectifier circuit.

[0079] In this way, the high-frequency transformers Tr1 and Tr2 of the transformer circuit portion TrC are connected to the corresponding rectifier circuits of the rectifier circuit portion ReC in parallel with each other on the secondary side.

[0080] Thus, the rectifying circuit unit ReC rectifies the alternating currents from the two high-frequency transformers Tr1 and Tr2 into direct currents using two rectifying circuits, and outputs the DC power in a superimposed manner to the downstream.

[0081] In addition, the positive input terminal Pi and the negative input terminal Ni are used to connect to an upstream DC source, and the positive output terminal Po and the negative output terminal No can be connected to a downstream electrical load.

[0082] In this manner, the high-frequency DC / DC converter circuit in this embodiment is configured.

[0083] [1-2]Working process

[0084] The working process of the above high-frequency DC / DC converter circuit is:

[0085] The DC power from the upstream is input from the positive input terminal Pi and the negative input terminal Ni, and is inverted into AC power by the half-bridge inverter circuit of the inverter circuit part InC.

[0086] Then, the AC power obtained by the inverter circuit part InC is transformed into AC power of the required voltage by the two high-frequency transformers Tr1 and Tr2 of the transformer circuit part TrC;

[0087] Finally, the alternating current transformed by the transformer circuit unit TrC is input from the two high-frequency transformers Tr1 and Tr2 to the two rectifier circuits of the rectifier circuit unit ReC, rectified into direct current and output from the positive output terminal Po and the negative output terminal No in a superimposed manner.

[0088] [1-3] Technical Effects

[0089] The main technical effects of the high-frequency DC / DC converter circuit are described below.

[0090] According to the above-mentioned high-frequency DC / DC conversion circuit, on the one hand, since the inverter circuit part InC uses a half-bridge inverter circuit, the number of semiconductor switches can be reduced compared with the case of using an inverter circuit with a full-bridge structure, and the number of control circuits and the like supporting the semiconductor switches can be reduced accordingly, thereby reducing the purchase cost of the semiconductor switch part and the maintenance cost that may occur later, thereby reducing the overall cost of the high-frequency DC / DC conversion circuit.

[0091] On the other hand, since the transformer circuit part TrC uses two high-frequency transformers Tr1 and Tr2, the total power of the circuit can be shared by the two high-frequency transformers Tr1 and Tr2, and the heat generated due to the use of the half-bridge inverter circuit in the inverter circuit part InC can be shared between the two high-frequency transformers Tr1 and Tr2. Moreover, since the primary windings of the two high-frequency transformers Tr1 and Tr2 are connected in series, the equivalent excitation inductance and resonant inductance required by the circuit are shared by the two high-frequency transformers Tr1 and Tr2, and the power density is also reduced, which is conducive to suppressing the increase in the heat generation of the high-frequency transformer. Therefore, the increase in the heat generation of the high-frequency transformer monomer can be suppressed within a small range that can be controlled by commonly used heat dissipation technology (for example, the heat dissipation technology of attaching a water cooling plate to the bottom surface of the high-frequency transformer Tr1 and Tr2), so that the cost reduced by reducing the semiconductor switches of the inverter circuit part is greater than the cost increased by increasing the number of high-frequency transformers and strengthening the heat dissipation of the high-frequency transformer.

[0092] In this way, the overall cost of the high-frequency DC / DC converter circuit can be reduced.

[0093] In addition, by connecting the primary windings of the two high-frequency transformers Tr1 and Tr2 of the transformer circuit portion TrC in series, as shown in FIG. Figure 2 As shown, the current i1 flowing in the primary winding of the high-frequency transformer Tr1 is always the same as the current i2 flowing in the primary winding of the high-frequency transformer Tr2, which can avoid the power imbalance problem between the two high-frequency transformers Tr1 and Tr2, thereby solving the heat imbalance problem between the two high-frequency transformers Tr1 and Tr2.

[0094] Furthermore, the primary windings of the two high-frequency transformers Tr1 and Tr2 are connected in series, which can also solve the problem of power imbalance that may occur in the two rectifier circuits of the rectifier circuit part ReC.

[0095] In addition, by providing two high-frequency transformers instead of more, the overall cost can be reduced while miniaturizing the high-frequency DC / DC converter circuit.

[0096] <2> Second embodiment

[0097] [2-1] Overall structure

[0098] Hereinafter, the overall structure of a high-frequency DC / DC converter module for railway vehicles according to a second embodiment will be described with reference to the drawings.

[0099] The high-frequency DC / DC converter module for railway vehicles in the second embodiment is used in the auxiliary power supply system of the railway vehicle, and is used to convert the power supplied from the upstream power supply network into power that can be used by downstream electrical loads (such as lighting, air conditioning, refrigerators and other on-board electrical equipment), and output the converted power to these electrical loads.

[0100] Figure 3 1 is a schematic diagram showing the overall structure of a high-frequency DC / DC converter module for railway vehicles in the second embodiment.

[0101] like Figure 3 As shown, the high-frequency DC / DC converter module for railway vehicles in this embodiment mainly includes an inverter unit InU, a transformer unit TrU and a rectifier unit ReU.

[0102] The inverter unit InU corresponds to the inverter circuit part InC of the high-frequency DC / DC converter circuit in the first embodiment, and is used to invert the DC power input from the upstream DC source via the positive input terminal Pi and the negative input terminal Ni into AC power.

[0103] Since the inverter unit InU has the same circuit structure as the inverter circuit portion InC described above, the circuit structure of the inverter unit InU will not be described here.

[0104] The transformer unit TrU corresponds to the transformer circuit part TrC of the high-frequency DC / DC conversion circuit in the first embodiment. On the one hand, it forms an LLC resonant circuit with the inverter unit InU, and on the other hand, it is used to transform the alternating current from the inverter unit InU. In addition, the transformer unit TrU also serves to isolate the upstream side of the high voltage from the downstream side of the low voltage.

[0105] The transformer unit TrU has substantially the same circuit configuration as that of the transformer circuit portion TrC.

[0106] The transformer unit TrU is different from the transformer circuit unit TrC in that: in the transformer unit TrU, the resonant inductor Lr1 is a leakage inductance integrated in the winding of the high-frequency transformer Tr1, and the resonant inductor Lr2 is also a leakage inductance integrated in the winding of the high-frequency transformer Tr2, and the leakage inductance value of the leakage inductance integrated in the winding of the high-frequency transformer Tr1 (i.e., the resonant inductor Lr1) and the leakage inductance value of the leakage inductance integrated in the winding of the high-frequency transformer Tr2 (i.e., the resonant inductor Lr2) are the same as each other.

[0107] Since the other structures of the transformer unit TrU are the same as those of the transformer circuit portion TrC, the description thereof will be omitted here.

[0108] The rectifier unit ReU corresponds to the rectifier circuit portion ReC of the high-frequency DC / DC converter circuit in the first embodiment, and is used to rectify the AC power from the two high-frequency transformers of the transformation unit TrU into DC power and output the DC power in a superimposed manner downstream.

[0109] Since the rectifying unit ReU has the same circuit structure as the rectifying circuit portion ReC described above, the circuit structure of the rectifying unit ReU will not be described here.

[0110] In addition, in terms of mechanical structure, the inverter unit InU and the rectifier unit ReU can be arranged together to form an integral inverter rectifier unit. The inverter rectifier unit can be installed on a liquid cooling plate using a liquid cooling medium (such as water), so that the liquid cooling plate is used to cool the components constituting the inverter unit InU and the components constituting the rectifier unit ReU. In addition, the transformer unit TrU can also use liquid cooling, that is, its two high-frequency transformers are installed on a liquid cooling plate, so that the liquid cooling plate is used to cool the two high-frequency transformers. Moreover, the inverter unit InU and the rectifier unit ReU in the inverter rectifier unit and the two high-frequency transformers in the transformer unit TrU can be installed together in a terminal direct connection manner, rather than being connected using wires.

[0111] In addition, the positive input terminal Pi and the negative input terminal Ni are used to connect to an upstream DC source, and the positive output terminal Po and the negative output terminal No can be connected to a downstream electrical load.

[0112] In this manner, the high-frequency DC / DC converter module for railway vehicles in the present embodiment is constructed.

[0113] [2-2]Working process

[0114] The working process of the above-mentioned high-frequency DC / DC converter module for railway vehicles is:

[0115] The DC power from the upstream is input from the positive input terminal Pi and the negative input terminal Ni, and is inverted into AC power through the half-bridge inverter circuit of the inverter unit InU;

[0116] Then, the AC power obtained by the inversion unit InU is transformed into AC power of the required voltage by two high-frequency transformers of the transformation unit TrU;

[0117] Finally, the alternating current transformed by the transformer unit TrU is input from two high-frequency transformers to the corresponding rectifier circuits in the rectifier unit ReU, rectified into direct current by the rectifier circuits and output from the positive output terminal Po and the negative output terminal No in a superimposed manner.

[0118] [2-3] Technical Effects

[0119] According to the high-frequency DC / DC converter module for railway vehicles in this embodiment, it is possible to achieve the same technical effects as those of the high-frequency DC / DC converter circuit described above.

[0120] Furthermore, by integrating the resonant inductor as a leakage inductor into the winding of the high-frequency transformer, the high-frequency transformer itself and the entire high-frequency DC / DC converter module can be more compactly designed, compared to, for example, using external wires to form the resonant inductor.

[0121] <3> Third embodiment

[0122] [3-1] Overall structure

[0123] A third embodiment of the present invention provides a railway vehicle, which is a railway vehicle such as an electric locomotive that operates using electric power from a power supply network.

[0124] The railway vehicle of this embodiment includes an auxiliary converter cabinet (converter cabinet), which has a plurality of cabinet spaces. A high-frequency DC / DC converter module for railway vehicles of the second embodiment is installed inside at least one of the plurality of cabinet spaces. The high-frequency DC / DC converter module for railway vehicles converts the electric power from the upstream and outputs it to the downstream load.

[0125] [3-2] Technical Effects

[0126] According to the railway vehicle of the present embodiment, it is possible to achieve the same technical effects as those of the high-frequency DC / DC converter module for railway vehicles of the second embodiment.

[0127] In addition, since the high-frequency DC / DC converter module for railway vehicles only occupies one cabinet space of the auxiliary converter cabinet, the cabinet space can be saved for other expansion equipment.

[0128] <4> other

[0129] The above describes the various embodiments of the present invention, but these embodiments are proposed for easy understanding of the present invention, and the protection scope of the present invention is not limited to these embodiments. Those skilled in the art can make various modifications to these embodiments without departing from the technical idea of ​​the present invention. Below, these modifications are illustrated.

[0130] (1) In the above-described embodiment, the half-bridge inverter circuit of the inverter circuit portion InC is a symmetrical half-bridge, but the present invention is not limited thereto and an asymmetrical half-bridge may be used.

[0131] Figure 4 1 is a schematic diagram showing a high-frequency DC / DC converter circuit in this modification.

[0132] like Figure 4 As shown, the inverter circuit part InC2 has an asymmetric half-bridge inverter circuit, which includes a first bridge arm provided with a supporting capacitor FC1, a third bridge arm provided with two semiconductor switch modules SW1 and SW2, and a resonant capacitor RC3 whose one end is connected to the source of the metal oxide semiconductor field effect transistor of the semiconductor switch module SW2 and the anode of the diode.

[0133] One connection of the primary winding of the high-frequency transformer Tr1 is connected to the midpoint of the two semiconductor switch modules SW1 and SW2 on the third bridge arm of the inverter circuit part InC2 via the resonant inductor Lr1, and another connection of the primary winding of the high-frequency transformer Tr1 is connected to one connection of the primary winding of the high-frequency transformer Tr2 via the resonant inductor Lr2, and another connection of the primary winding of the high-frequency transformer Tr2 is connected to the other end of the resonant capacitor RC3 of the inverter circuit part InC2.

[0134] The other structures are the same as those of the first embodiment.

[0135] According to this modified embodiment, it is possible to achieve substantially the same technical effects as those of the first embodiment.

[0136] Furthermore, a high-frequency DC / DC converter module for railway vehicles may also use the circuit structure of the high-frequency DC / DC converter circuit in this modified form, and a railway vehicle may also use the high-frequency DC / DC converter module for railway vehicles that has undergone the above modification.

[0137] (2) In the above-mentioned embodiments / variations, in the schematic diagram, N-channel field effect transistors are used as switch tubes of the semiconductor switch modules SW1 and SW2 constituting the inverter circuit unit InC, but this is not limited to this, and P-channel field effect transistors may also be used.

[0138] (3) In the above-mentioned embodiments / variations, the switching tubes of the semiconductor switch modules SW1 and SW2 constituting the inverter circuit unit InC / InC2 are not limited to metal oxide semiconductor field effect transistors, and insulated gate bipolar transistors (IGBTs) may also be used.

[0139] (4) In the above embodiment, two high-frequency transformers are provided, but the present invention is not limited thereto. Three or more high-frequency transformers may also be provided. As long as these high-frequency transformers are provided with the primary windings connected in series and the secondary windings connected in parallel as in the above embodiment, they can achieve technical effects substantially the same as the beneficial effects described above.

[0140] (5) In the second embodiment, the resonant inductor is integrated into the winding of the high-frequency transformer, but the present invention is not limited thereto and the resonant inductor may be provided separately. For example, a wire independent of the winding of the high-frequency transformer may be provided to form the resonant inductor.

[0141] (6) In the above embodiment, the number of rectifier circuits provided is equal to the number of high-frequency transformers, that is, two. Figure 5 As shown, a rectifier circuit may also be provided, wherein one connection of the secondary windings of two (or more) high-frequency transformers Tr1 and Tr2 is commonly connected to the midpoint of the two diode switches RD1 and RD3 on the fourth bridge arm of the rectifier circuit of the rectifier circuit part ReC2, and the other connection of the secondary windings of the two high-frequency transformers Tr1 and Tr2 is commonly connected to the midpoint of the two diode switches RD2 and RD4 on the fifth bridge arm of the rectifier circuit part ReC2, and a rectifier circuit is used to rectify the AC power superimposed on the input of the two high-frequency transformers and output it in a superimposed manner.

[0142] (7) In the above embodiments, the leakage inductance / leakage inductance value being the same includes being absolutely the same and being approximately the same within an error range that can be understood by those skilled in the art.

Claims

1. A high-frequency DC / DC converter circuit, used to convert power from upstream and output it to downstream, characterized in that: have: The inverter circuit part includes a half-bridge inverter circuit, which inverts the DC power from the upstream into AC power; a transformer circuit unit, comprising a plurality of high-frequency transformers, for transforming the alternating current from the inverter circuit unit, wherein the primary windings of the plurality of high-frequency transformers are connected in series with the half-bridge inverter circuit via a resonant inductor; and The rectifier circuit unit includes a rectifier circuit connected to the secondary windings of each of the multiple high-frequency transformers of the transformer circuit unit. The secondary windings of the multiple high-frequency transformers are connected to the rectifier circuit in parallel with each other. The rectifier circuit is used to rectify the alternating current from the multiple high-frequency transformers into direct current and output the direct current in a superimposed manner downstream.

2. The high-frequency DC / DC converter circuit according to claim 1, characterized in that: The switch tube of the half-bridge inverter circuit is a silicon carbide field effect transistor.

3. The high-frequency DC / DC converter circuit according to claim 1, characterized in that: The rectifier circuit is provided with a plurality of The plurality of rectifier circuits are respectively connected to the secondary windings of the corresponding high-frequency transformers, and the plurality of rectifier circuits are connected in parallel with each other. The rectifying circuit unit rectifies the alternating currents from the plurality of high-frequency transformers into direct currents using the plurality of rectifying circuits, and outputs the DC currents in a superimposed manner to a downstream.

4. The high-frequency DC / DC converter circuit according to any one of claims 1 to 3, characterized in that: There are two high-frequency transformers.

5. A high-frequency DC / DC converter module for railway vehicles, used to convert the power from upstream and output it to downstream in an auxiliary power supply system, characterized in that: have: The inverter unit includes a half-bridge inverter circuit, which inverts the DC power from the upstream into AC power; a transformer unit, comprising a plurality of high-frequency transformers, for transforming the alternating current from the inverter unit, wherein the primary windings of the plurality of high-frequency transformers are connected in series with the half-bridge inverter circuit via a resonant inductor; and The rectifier unit includes a rectifier circuit connected to the secondary windings of each of the multiple high-frequency transformers of the transformer unit. The secondary windings of the multiple high-frequency transformers are connected to the rectifier circuit in parallel with each other. The rectifier circuit is used to rectify the alternating current from the multiple high-frequency transformers into direct current and output the direct current in a superimposed manner downstream.

6. The high-frequency DC / DC converter module for railway vehicles according to claim 5, characterized in that: The switch tube of the half-bridge inverter circuit is a silicon carbide field effect transistor.

7. The high-frequency DC / DC converter module for railway vehicles according to claim 5, characterized in that: The resonant inductor is a leakage inductance respectively integrated in the winding of each high-frequency transformer, The leakage inductances integrated in the windings of the high-frequency transformers are the same.

8. The high-frequency DC / DC converter module for railway vehicles according to claim 5, characterized in that: The rectifier circuit is provided with a plurality of The plurality of rectifier circuits are respectively connected to the secondary windings of the corresponding high-frequency transformers, and the plurality of rectifier circuits are connected in parallel with each other. The rectifying unit utilizes the plurality of rectifying circuits to rectify the alternating currents from the plurality of high-frequency transformers into direct currents respectively and outputs the direct currents in a superimposed manner to the downstream.

9. The high-frequency DC / DC converter module for railway vehicles according to any one of claims 5 to 8, characterized in that: There are two high-frequency transformers.

10. A railway vehicle, characterized in that: have: Converter cabinet; as well as The high-frequency DC / DC converter module for railway vehicles according to any one of claims 5 to 9 is housed in the converter cabinet, and converts the electric power from the upstream and outputs it to the downstream load.

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