A control device for locomotive fireless return of domestic power

Abstract

The application provides a control device for locomotive fireless return of domestic power supply, comprising a storage battery, a bidirectional DC converter, a traction inverter, a single-phase inverter and a controller. The storage battery is boosted by a first bidirectional DC converter to establish a first DC bus, and a second bidirectional DC converter boosts the first DC bus to a second DC bus; the traction inverter is connected with a locomotive motor stator to control motor excitation to generate electricity, converting mechanical energy into electrical energy, and the single-phase inverter inverts the first DC bus into single-phase AC power output. The controller coordinates each module to realize speed threshold value judgment, power generation mode switching and closed-loop voltage stabilization control. The application solves the technical problem of poor adaptability caused by the need to install transmission equipment and customize a support in the existing permanent magnet generator scheme.

Description

Technical Field

[0001] This invention relates to the field of motor drive technology, and more specifically to a control device for the non-fired return of domestic electricity from locomotives. Background Technology

[0002] Starting April 1, 2015, China Railway Corporation restructured its Harmony-type locomotives, establishing six maintenance levels: C1, C2, C3, C4, C5, and C6. C1-C4 maintenance is at the section level, while C5 and C6 are higher-level maintenance. Within the section level, some locomotive depots in China lack the capability for C4 maintenance, requiring the assigned locomotives to be transported to depots with C4 maintenance capabilities via a fireless return process. C5 and C6 maintenance are completed at locomotive factories or repair bases, as these cannot be completed within railway bureaus or sections, and also require fireless return transport to locomotive factories or repair bases for repair. As time goes on, more and more locomotives will face high-level maintenance procedures such as C4, C5, and C6. When locomotives are returned to service without power, the pantograph is lowered and there is no electricity, resulting in poor working conditions for the accompanying drivers and crew. As a result, violations of operating procedures and safety accidents have become commonplace. Improving the working conditions for drivers and crew during locomotive return without power is a difficult problem that locomotive users need to solve under the background of safe production.

[0003] Current solutions include using the locomotive's rotating axle head to add a permanent magnet generator and a rectifier-inverter to provide power. However, the method of adding a permanent magnet motor and a rectifier-inverter requires adding transmission equipment and fixing the permanent magnet motor on the locomotive bogie. Different locomotive models have significant structural differences, so custom mounting brackets are required, resulting in poor adaptability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a control device for the non-fired power supply of locomotives to domestic use, thereby solving the technical problem of poor power supply adaptability in existing technologies that rely on adding permanent magnet generators and rectifier inverters.

[0005] The technical solution adopted in this invention is a control device for the non-fired return of domestic electricity from a locomotive, comprising a battery, a first bidirectional DC-DC converter, a second bidirectional DC-DC converter, a traction inverter, a single-phase inverter, and a controller.

[0006] The output terminal of the battery is connected to one end of the first bidirectional DC-DC converter.

[0007] The other end of the first DC converter is connected to the input terminal of the single-phase inverter and one end of the second bidirectional DC converter via the first DC bus.

[0008] The output terminal of the single-phase inverter is used for single-phase AC power output.

[0009] The other end of the second bidirectional DC-DC converter is connected to one end of the traction inverter via the second DC bus.

[0010] The other end of the traction inverter is connected to the locomotive motor via a traction wiring modification.

[0011] The controller is used to coordinate and control the battery, the first bidirectional DC-DC converter, the second bidirectional DC-DC converter, the traction inverter, and the single-phase inverter.

[0012] Furthermore, the first bidirectional DC-DC converter includes: a first full-bridge circuit connected between the positive and negative terminals of the power supply side DC circuit, wherein a first capacitor is connected in parallel between the positive and negative terminals of the power supply side DC circuit; The second full-bridge circuit is connected between the positive and negative terminals of the first DC bus, and a second capacitor is connected in parallel between the positive and negative terminals of the first DC bus. The first high-frequency isolation transformer has its primary winding connected to the first full-bridge circuit via a resonant branch, and its secondary winding connected to the second full-bridge circuit via a resonant branch. The resonant branch includes a first resonant inductor, a first resonant capacitor, a second resonant inductor, and a second resonant capacitor; The first resonant inductor and the first resonant capacitor are connected in series across the two ends of the primary winding of the transformer; The second resonant inductor and the second resonant capacitor are connected in series at both ends of the secondary winding of the transformer.

[0013] Furthermore, both the first full-bridge circuit and the second full-bridge circuit are composed of two symmetrically arranged bridge arm units.

[0014] Each of the bridge arm units includes two bridge arm switch units arranged in series.

[0015] The upper and lower ends of the bridge arm unit are respectively connected to the positive and negative terminals of the DC circuit on the power supply side or the positive and negative terminals of the first DC bus.

[0016] The connection ends of the two bridge arm switching units serve as the midpoints of the bridge arms, and are used to connect to both ends of the primary winding and the secondary winding of the high-frequency isolation transformer, respectively.

[0017] Furthermore, the second bidirectional DC-DC converter includes a bridge arm unit with a first inductor and a third capacitor.

[0018] The upper and lower bridge arm ends of the bridge arm unit are respectively connected to the positive and negative terminals of the second DC bus, and the third capacitor is connected in parallel between the positive and negative terminals of the second DC bus.

[0019] Each of the bridge arm units includes two bridge arm switch units arranged in series.

[0020] The connection point of the two bridge arm switching units serves as the midpoint of the bridge arm and is used to connect to one end of the first inductor.

[0021] The other end of the first inductor is connected to the positive terminal of the first DC bus, and the negative terminal of the first DC bus is connected to the lower bridge arm end of the bridge arm unit.

[0022] Preferably, the traction inverter includes three bridge arm units arranged in parallel between the positive and negative poles of the second DC bus.

[0023] Each of the bridge arm units includes two bridge arm switch units arranged in series.

[0024] The connection point of the two bridge arm switch units serves as the midpoint of the bridge arm and is used as one of the three three-phase output terminals.

[0025] The three-phase output terminal is connected to the locomotive motor via a circuit breaker assembly and a modified traction wiring connection. Furthermore, the upper bridge arm switching unit and the lower bridge arm switching unit include one of IGBT and MOSFET.

[0026] Furthermore, the isolated single-phase inverter includes a front-end full-bridge circuit, a second high-frequency isolation transformer, a rear-end full-bridge circuit, a second inductor, and a fifth capacitor.

[0027] The front-end full-bridge circuit is connected between the positive and negative terminals of the first DC bus.

[0028] The AC output terminals of the subsequent full-bridge circuit are connected to the live wire and the neutral wire, respectively.

[0029] The fifth capacitor is connected in parallel between the live wire and the neutral wire at the AC output terminal.

[0030] The second inductor is connected in series between the AC output terminal and the live wire of the subsequent full-bridge circuit.

[0031] The second high-frequency isolation transformer has its primary winding connected to the preceding full-bridge circuit via a resonant branch, and its secondary winding connected to the following full-bridge circuit via a resonant branch.

[0032] The resonant branch includes a third resonant inductor, a third resonant capacitor, a fourth resonant inductor, and a fourth resonant capacitor.

[0033] The third resonant inductor and the third resonant capacitor are connected in series at both ends of the primary winding of the transformer.

[0034] The fourth resonant inductor and the fourth resonant capacitor are connected in series at both ends of the secondary winding of the transformer.

[0035] Furthermore, the front-end full-bridge circuit includes two bridge arm units arranged in parallel between the positive and negative terminals of the first DC bus.

[0036] Each of the bridge arm units includes two bridge arm switch units connected in series, with the upper and lower bridge arm ends of the bridge arm unit respectively connected to the positive and negative terminals of the first DC bus.

[0037] The connection ends of the two bridge arm switching units serve as the midpoints of the bridge arms, and are used to connect the two ends of the primary winding side of the second high-frequency isolation transformer, respectively.

[0038] Furthermore, the rear full-bridge circuit includes four bridge arm units arranged in parallel between the positive and negative terminals of the first DC bus, and a fourth capacitor is connected in parallel between the upper and lower bridge arm ends of each bridge arm unit.

[0039] Each of the bridge arm units includes two bridge arm switch units connected in series, with the connection end of the bridge arm switch units serving as the midpoint of the bridge arm.

[0040] The two midpoints of the bridge arms are respectively used to connect the two ends of the secondary winding side of the second high-frequency isolation transformer.

[0041] The midpoints of the two bridge arms are used as AC output terminals to connect the live wire and the neutral wire, respectively.

[0042] Preferably, the bridge arm switching unit includes an N-type MOSFET.

[0043] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows: The traction inverter connects to the locomotive motor only through wiring modifications, and can perform power generation control without modifying the locomotive software or adding a permanent magnet generator. This eliminates the need for a permanent magnet motor and transmission mechanism, thus improving the adaptability of the device. Attached Figure Description

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0045] Figure 1 This is a schematic diagram of the device in Embodiment 2 of the present invention; Figure 2 This is the overall topology diagram of the device in Embodiment 2 of the present invention; Figure label: 1-Battery; 2-First bidirectional DC-DC converter; 3-Second bidirectional DC-DC converter; 4-Traction inverter; 5-Isolation single-phase inverter; 6-Controller. Detailed Implementation

[0046] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0047] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0048] This embodiment provides a control device for the non-fired return of domestic power in locomotives. The working principle of Embodiment 1 is described in detail below: The schematic diagram of the device in this embodiment is as follows: Figure 1 As shown, the corresponding overall device topology diagram is as follows: Figure 2 As shown, it includes: a storage battery 1, a first bidirectional DC-DC converter 2, a second bidirectional DC-DC converter 3, a traction inverter 4, an isolated single-phase inverter 5, and a controller 6.

[0049] The output terminal of the storage battery 1 is connected to one end of the first bidirectional DC-DC converter 2 to output a DC battery voltage of 40V-57.6V.

[0050] The other end of the first DC converter 2 is connected to the input terminal of the isolated single-phase inverter 5 and one end of the second bidirectional DC converter 3 via the first DC bus, in order to boost the battery voltage to establish a 400V first DC bus.

[0051] The second bidirectional DC-DC converter 3 is used to bidirectionally convert the 400V first DC bus at one end of the first bidirectional DC-DC converter to the 600V second DC bus at one end of the traction converter 4.

[0052] The output of the isolated single-phase inverter 5 is used for single-phase AC power output.

[0053] The other end of the second bidirectional DC-DC converter 3 is connected to one end of the traction inverter 4 via the second DC bus.

[0054] The other end of the traction inverter 4 is connected to the locomotive motor via a modified traction wiring connection. It is used to excite and control the locomotive motor with direct voltage, and to build up voltage on the second DC bus when starting regenerative braking.

[0055] The controller 6 is used to coordinate the control of the battery 1, the first bidirectional DC-DC converter 2, the second bidirectional DC-DC converter 3, the traction inverter 4 and the isolated single-phase inverter 5 based on the bus direct voltage control, locomotive motor stator voltage reconstruction, speed estimation and excitation control strategies.

[0056] In this embodiment, the first bidirectional DC-DC converter 2 further includes: A first full-bridge circuit is connected between the positive and negative terminals of the DC circuit on the power supply side, and a first capacitor is connected in parallel between the positive and negative terminals of the DC circuit on the power supply side. A second full-bridge circuit is connected between the positive and negative terminals of the first DC bus, and a second capacitor is connected in parallel between the positive and negative terminals of the first DC bus. A first high-frequency isolation transformer has its primary winding connected to the first full-bridge circuit via a resonant branch, and its secondary winding connected to the second full-bridge circuit via a resonant branch. The resonant branch includes a first resonant inductor, a first resonant capacitor, a second resonant inductor, and a second resonant capacitor. The first resonant inductor and the first resonant capacitor are connected in series across the primary winding of the transformer. The second resonant inductor and the second resonant capacitor are connected in series across the secondary winding of the transformer.

[0057] The resonant branch and the high-frequency isolation transformer form an LLC resonant network, which is used to achieve soft switching and reduce switching losses.

[0058] Both the first and second full-bridge circuits are composed of two symmetrically arranged bridge arm units. Each of the bridge arm units includes two N-type MOSFETs connected in series. The drain of the N-type MOSFET serving as the upper bridge arm switching unit is connected to the positive terminal of the battery at the upper bridge arm end, and the source of the N-type MOSFET serving as the lower bridge arm switching unit is connected to the negative terminal of the battery at the upper bridge arm end.

[0059] The drain and source of two N-type MOSFETs are connected together as the midpoint of the bridge arm, which is used to connect to the two ends of the primary winding and the two ends of the secondary winding of the high-frequency isolation transformer, respectively.

[0060] Both the first and second full-bridge circuits achieve bidirectional energy transfer through the switching of N-type MOSFETs, enabling bidirectional conversion of electrical energy between the first DC bus and the battery.

[0061] In this embodiment, the second bidirectional DC-DC converter 3 further includes a bridge arm unit with a first inductor and a third capacitor. The upper and lower bridge arm ends of the bridge arm unit are respectively connected to the positive and negative terminals of the second DC bus, and the third capacitor is connected in parallel between the positive and negative terminals of the second DC bus. Each bridge arm unit includes two IGBTs connected in series as a bridge arm switching unit. The emitters and collectors of the two IGBTs are connected together as the midpoint of the bridge arm, which is used to connect to one end of the first inductor. The other end of the first inductor is connected to the positive terminal of the first DC bus, and the negative terminal of the first DC bus is connected to the lower bridge arm end of the bridge arm unit.

[0062] Each switch arm's switch unit operates according to a predetermined pulse sequence, thereby realizing bidirectional power transmission between the first DC bus and the second DC bus and performing closed-loop control of voltage and current.

[0063] In this embodiment, the traction inverter 4 further includes three bridge arm units arranged in parallel between the positive and negative terminals of the second DC bus. Each bridge arm unit includes two bridge arm switching units arranged in series. In this embodiment, the bridge arm switching unit of the traction inverter 4 is an IGBT. The emitters and collectors of the two IGBTs are connected together as the midpoint of the bridge arm, which is used as three three-phase output terminals. The three-phase output terminals are connected to the locomotive motor via a circuit breaker assembly and modified by traction wiring.

[0064] The positive and negative terminals of the DC bus of the traction inverter 4 are connected to the upper and lower bridge arms of each bridge arm unit, respectively, thus forming a three-phase full-bridge inverter circuit structure to realize the mutual conversion of DC power and AC power.

[0065] Here, the traction inverter 4 is a device that converts the electrical energy of the second DC bus into three-phase AC through PWM / space vector modulation to drive the traction motor, and at the same time can feed the regenerative energy of the motor back to the second DC bus.

[0066] In this embodiment, the isolated single-phase inverter 5 further includes a front-stage full-bridge circuit, a second high-frequency isolation transformer, a rear-stage full-bridge circuit, a second inductor, and a fifth capacitor. The front-stage full-bridge circuit is connected between the positive and negative terminals of the first DC bus. The AC output terminals of the rear-stage full-bridge circuit are connected to the live wire and the neutral wire, respectively. The fifth capacitor is connected in parallel between the live wire and the neutral wire at the AC output terminals. The second inductor is connected in series between the AC output terminal of the rear-stage full-bridge circuit and the live wire. The primary winding of the second high-frequency isolation transformer is connected to the front-stage full-bridge circuit via a resonant branch, and the secondary winding is connected to the rear-stage full-bridge circuit via a resonant branch. The resonant branch includes a third resonant inductor, a third resonant capacitor, a fourth resonant inductor, and a fourth resonant capacitor. The third resonant inductor and the third resonant capacitor are connected in series across the two ends of the primary winding of the transformer. The fourth resonant inductor and the fourth resonant capacitor are connected in series across the two ends of the secondary winding of the transformer.

[0067] In this embodiment, the front-end full-bridge circuit further includes two bridge arm units arranged in parallel between the positive and negative terminals of the first DC bus. The rear full-bridge circuit includes four bridge arm units arranged in parallel between the positive and negative terminals of the first DC bus, and a fourth capacitor is connected in parallel between the upper and lower bridge arm ends of each bridge arm unit.

[0068] Each of the bridge arm units includes two bridge arm switching units connected in series. The bridge arm switching units used in the isolated single-phase inverter 5 are N-type MOSFETs. The drain of the N-type MOSFET in the upper bridge arm switching unit serves as the positive terminal of the upper bridge arm end connected to the first DC bus, and the source of the N-type MOSFET in the lower bridge arm switching unit serves as the negative terminal of the upper bridge arm end connected to the first DC bus. The drains and sources of the two N-type MOSFETs are connected together as the bridge arm midpoint. The bridge arm midpoint of the front-stage full-bridge circuit is used to connect to the two ends of the primary winding side of the second high-frequency isolation transformer, respectively. The bridge arm midpoints of the rear full-bridge circuit are used as AC output terminals connected to the live wire and the neutral wire, respectively.

[0069] In this embodiment, the aforementioned N-type MOSFET is a SiC MOSFET to improve the high-frequency reliability of the isolated single-phase inverter 5. This device is directly connected to the stator winding of the traction motor of the Harmony-type electric locomotive. When the Harmony-type electric locomotive is running without power, the entire locomotive does not draw power from the overhead contact line; instead, it is pulled by other locomotives, and the locomotive's own motor does not operate.

[0070] The device uses the DC power carried by the storage battery 1, which is boosted to DC400V by the first bidirectional DC converter 2, then boosted to DC600V by the second bidirectional DC converter 3, and then inverted into AC power with adjustable voltage and frequency by the traction inverter 4 to establish an excitation magnetic field for the traction motor.

[0071] While establishing the excitation magnetic field, the rotational speed of the traction motor under the current state is predicted based on the sensorless speed measurement principle. Induced current and alternating magnetic fields are generated within the rotor of the squirrel-cage traction motor. At this time, the excitation frequency of the stator windings is changed, causing the traction motor to enter a braking and generating state.

[0072] The three-phase AC power generated by the traction motor is rectified into DC 600V DC power by the traction inverter 4, then the voltage is reduced to DC 400V by the second bidirectional DC-DC converter 3, and finally output as AC 220V by the isolated single-phase inverter 5 to power electrical equipment. The output single-phase 220V AC power has the same voltage and frequency as the mains electricity and can be used for household electrical appliances such as kettles, air conditioners, and lighting equipment, providing convenience for the passengers.

[0073] When the battery 1 is low on power, the battery module can be charged through the first bidirectional DC-DC converter 2. The equipment can be put into use when the speed of the traction Harmony electric locomotive is greater than 30 km / h, and the equipment can automatically shut down and limit the output power of the inverter when the speed is less than 30 km / h.

[0074] In this embodiment, the traction inverter connects to the locomotive motor only through wiring modifications, enabling power generation control without requiring modifications to the locomotive software or the addition of a permanent magnet generator. This eliminates the need for a permanent magnet motor and transmission mechanism, improving the device's adaptability. By using this external device to achieve a three-stage energy conversion process—battery boost, traction inverter power generation, and single-phase inverter output—the risks of modifying the locomotive software and hardware are completely avoided, improving device compatibility, shortening deployment time, and indirectly improving the driver and passenger environment, thereby reducing accidents caused by improper operation.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A control device for flameless return of domestic electricity, characterized in that, It includes a storage battery, a first bidirectional DC-DC converter, a second bidirectional DC-DC converter, a traction inverter, a single-phase inverter, and a controller; The output terminal of the battery is connected to one end of the first bidirectional DC-DC converter; The other end of the first DC converter is connected to the input terminal of the single-phase inverter and one end of the second bidirectional DC converter via the first DC bus. The output terminal of the single-phase inverter is used for single-phase AC power output. The other end of the second bidirectional DC-DC converter is connected to one end of the traction inverter via the second DC bus; The other end of the traction inverter is connected to the locomotive motor via a traction wiring modification. The controller is used to coordinate and control the battery, the first bidirectional DC-DC converter, the second bidirectional DC-DC converter, the traction inverter, and the single-phase inverter.

2. The control device for non-flame-based return of domestic electricity according to claim 1, characterized in that, The first bidirectional DC-DC converter includes: The first full-bridge circuit is connected between the positive and negative terminals of the DC circuit on the power supply side, and a first capacitor is connected in parallel between the positive and negative terminals of the DC circuit on the power supply side. The second full-bridge circuit is connected between the positive and negative terminals of the first DC bus, and a second capacitor is connected in parallel between the positive and negative terminals of the first DC bus. The first high-frequency isolation transformer has its primary winding connected to the first full-bridge circuit via a resonant branch, and its secondary winding connected to the second full-bridge circuit via a resonant branch. The resonant branch includes a first resonant inductor, a first resonant capacitor, a second resonant inductor, and a second resonant capacitor; The first resonant inductor and the first resonant capacitor are connected in series across the two ends of the primary winding of the transformer; The second resonant inductor and the second resonant capacitor are connected in series at both ends of the secondary winding of the transformer.

3. A control device for the non-fired return of domestic power in locomotives according to claim 2, characterized in that, Both the first full-bridge circuit and the second full-bridge circuit are composed of two symmetrically arranged bridge arm units. Each of the bridge arm units includes two bridge arm switch units arranged in series; The upper and lower bridge arm ends of the bridge arm unit are respectively connected to the positive and negative terminals of the DC circuit on the power supply side or the positive and negative terminals of the first DC bus. The connection ends of the two bridge arm switching units serve as the midpoints of the bridge arms, and are used to connect to both ends of the primary winding and the secondary winding of the high-frequency isolation transformer, respectively.

4. A control device for non-fired power supply for domestic use in locomotives according to claim 1, characterized in that, The second bidirectional DC-DC converter includes a bridge arm unit with a first inductor and a third capacitor; The upper and lower bridge arm ends of the bridge arm unit are respectively connected to the positive and negative terminals of the second DC bus, and the third capacitor is connected in parallel between the positive and negative terminals of the second DC bus. Each of the bridge arm units includes two bridge arm switch units arranged in series; The connection point of the two bridge arm switching units serves as the midpoint of the bridge arm and is used to connect to one end of the first inductor. The other end of the first inductor is connected to the positive terminal of the first DC bus, and the negative terminal of the first DC bus is connected to the lower bridge arm end of the bridge arm unit.

5. A control device for the non-fired return of domestic power in locomotives according to claim 1, characterized in that, The traction inverter includes three bridge arm units arranged in parallel between the positive and negative poles of the second DC bus; Each of the bridge arm units includes two bridge arm switch units arranged in series; The connection point of the two bridge arm switch units serves as the midpoint of the bridge arm and is used as three three-phase output terminals respectively. The three-phase output terminals are connected to the locomotive motor via a circuit breaker assembly and a modified traction wiring connection.

6. A control device for non-fired power supply for domestic use in locomotives according to claims 2-5, characterized in that, The upper bridge arm switching unit and the lower bridge arm switching unit include one of IGBT and MOSFET.

7. A control device for non-fired power supply for domestic use in locomotives according to claim 1, characterized in that, The isolated single-phase inverter includes a front-end full-bridge circuit, a second high-frequency isolation transformer, a rear-end full-bridge circuit, a second inductor, and a fifth capacitor. The front-end full-bridge circuit is connected between the positive and negative terminals of the first DC bus; The AC output terminals of the subsequent full-bridge circuit are connected to the live wire and the neutral wire, respectively. The fifth capacitor is connected in parallel between the live wire and the neutral wire at the AC output terminal; The second inductor is connected in series between the AC output terminal and the live wire of the subsequent full-bridge circuit; The second high-frequency isolation transformer has its primary winding connected to the preceding full-bridge circuit via a resonant branch, and its secondary winding connected to the following full-bridge circuit via a resonant branch. The resonant branch includes a third resonant inductor, a third resonant capacitor, a fourth resonant inductor, and a fourth resonant capacitor; The third resonant inductor and the third resonant capacitor are connected in series across the two ends of the primary winding of the transformer. The fourth resonant inductor and the fourth resonant capacitor are connected in series at both ends of the secondary winding of the transformer.

8. A control device for non-fired power supply for domestic use in locomotives according to claim 7, characterized in that, The front-end full-bridge circuit includes two bridge arm units arranged in parallel between the positive and negative terminals of the first DC bus. Each of the bridge arm units includes two bridge arm switch units connected in series, and the upper and lower bridge arm ends of the bridge arm unit are respectively connected to the positive and negative terminals of the first DC bus; The connection ends of the two bridge arm switching units serve as the midpoints of the bridge arms, and are used to connect the two ends of the primary winding side of the second high-frequency isolation transformer, respectively.

9. A control device for the non-fired return of domestic power in locomotives according to claim 7, characterized in that, The rear full-bridge circuit includes four bridge arm units arranged in parallel between the positive and negative poles of the first DC bus, and a fourth capacitor is connected in parallel between the upper bridge arm end and the lower bridge arm end of the bridge arm unit. Each of the bridge arm units includes two bridge arm switch units connected in series, with the connection end of the bridge arm switch units serving as the midpoint of the bridge arm; The two midpoints of the bridge arms are respectively used to connect the two ends of the secondary winding side of the second high-frequency isolation transformer; The midpoints of the two bridge arms are used as AC output terminals to connect the live wire and the neutral wire, respectively.

10. A control device for non-fired power supply for domestic use in locomotives according to claims 7-9, characterized in that, The bridge arm switching unit includes an N-type MOSFET.

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