Rectifier transformer magnetizing circuit of ship electric propulsion system

Abstract

The invention discloses a rectifier transformer magnetizing circuit of a ship electric propulsion system. The system is composed of a rectifier transformer, a propulsion frequency converter, a propulsion motor, a propulsion motor branch contactor, a magnetizing branch contactor, a secondary side voltage transformer, a current transformer, an anti-countercurrent diode, a fuse, a direct current power supply, a direct current boosting device, a direct current circuit breaker, a frequency conversion controller and an upper computer. A special rectifier transformer magnetizing mode is added on the basis of an existing ship propulsion frequency converter, and before the rectifier transformer is put into use, the inverter unit of the ship frequency converter inverts a direct current power supply into a three-phase alternating current power supply and then magnetizes the rectifier transformer. Compared with an existing ship electric propulsion system rectifier transformer magnetizing circuit, equipment such as an existing propulsion frequency converter in a propulsion system is fully utilized, magnetizing inrush current generated when the rectifier transformer is input is completely eliminated, and the ship electric propulsion system rectifier transformer magnetizing circuit has the advantages of being low in cost, saving cabin space and the like.

Description

Technical Field

[0001] The invention belongs to the field of ship electric propulsion systems, and in particular relates to a rectifier transformer magnetizing circuit of a ship electric propulsion system. Background Art

[0002] The ship electric propulsion system is mainly composed of the ship AC power grid, rectifier transformer, propulsion inverter and propulsion motor. When the rectifier transformer is running stably at no load, the excitation current of the transformer is small, usually only about 1% to 3% of the rated current. However, when the rectifier transformer is put into operation, the rectifier transformer power switch is closed. Since the internal magnetic flux of the transformer cannot change suddenly, a DC bias magnetic component will be generated in the transformer core at the moment of closing. Its size depends on the phase of the power supply voltage at the moment of closing, that is, the closing angle θ. In some cases, after the AC excitation magnetic flux is superimposed with the DC bias magnetic component and the residual magnetism of the core, the transformer core magnetic flux is saturated, the transformer excitation circuit impedance drops significantly, and the maximum instantaneous value of the excitation inrush current flowing through the transformer power switch and line can reach 6 to 8 times the rated working current of the transformer. The excitation inrush current has a great impact on the ship power grid, causing the voltage of the ship AC power grid to drop instantly, and the overcurrent quick-break protection and undervoltage protection to malfunction. Therefore, for the ship electric propulsion system, it is necessary to suppress the excitation inrush current of the transformer by certain means.

[0003] The main methods of suppressing transformer excitation inrush current include: 1. According to the relationship between the excitation inrush current and the closing angle θ of the power switch, the controller accurately controls the three-phase circuit breaker to close at the appropriate time. This method requires accurate control of the closing time of the three-phase circuit breaker. Due to the difficulty of accurately identifying the amplitude and direction of the magnetic flux inside the transformer core under current technical conditions and the difficulty in improving the control accuracy of the three-phase circuit breaker closing, it is not suitable for internal application in ships.

[0004] 2. Connect resistance in series in the circuit. The resistance in this method will generate heat and burn out during the repeated startup and magnetization of the transformer.

[0005] 3. The transformer uses a variable magnetic saturation point core and adds a flux compensation coil to prevent the transformer magnetic circuit from saturating at the moment of closing. This method requires a special customized design of the winding and magnetic circuit structure of the rectifier transformer, which is costly.

[0006] 4. Before the power switch is closed, the magnetizing transformer is used to magnetize the rectifier transformer. Therefore, under the existing technical conditions, the power supply of the ship's electric propulsion system is rectified by the rectifier transformer 1-2 and then output to the inverter 1-4, and the inverter 1-4 drives the propulsion motor 1-5. Figure 1As shown, before the rectifier transformer power supply switch 1-1 is closed, the magnetizing circuit contactor 1-6 is closed first, and the rectifier transformer 1-2 is magnetized through the pre-magnetizing transformer 1-3. After the magnetization is completed, the rectifier transformer power supply switch 1-1 is closed, and the magnetizing circuit contactor 1-6 is disconnected.

[0007] However, this method still has the following shortcomings: 1. To prevent the magnetizing transformer from having too large an excitation surge current when it is switched on without load, the capacity of the magnetizing transformer should not be too large. It is usually selected to be about 5% of the rated capacity of the magnetizing transformer. However, according to the short-circuit impedance calculation formula , the voltage of the same impedance The short-circuit impedance of a small-capacity transformer is relatively large, which limits the magnetizing current of the rectifier transformer. Therefore, after being magnetized by the magnetizing transformer, a certain amount of excitation surge current will still appear in the rectifier transformer at the moment the power switch is closed.

[0008] 2. The magnetizing transformer is large in size and has high procurement cost. For example, a medium-voltage marine dry-type magnetizing transformer cabinet with a capacity of 20kVA is about 2000mm×1800mm×800mm in size and costs about hundreds of thousands of yuan, which greatly occupies the precious ship's cabin space and procurement funds. Summary of the invention

[0009] In order to solve the problems existing in the existing method for suppressing the excitation inrush current of the rectifier transformer of the ship electric propulsion system, the object of the present invention is to provide a low-cost and reliable magnetizing circuit for the rectifier transformer of the ship electric propulsion system.

[0010] The technical solution adopted by the present invention to solve its technical problems is: a rectifier transformer magnetizing circuit of a ship electric propulsion system, including an AC busbar connected to the primary winding of the rectifier transformer through a rectifier transformer power supply switch arranged on an AC distribution board, and a propulsion inverter connected to the secondary winding of the rectifier transformer, the AC busbar is connected to the ship AC power supply through an incoming circuit breaker, the AC distribution board is also provided with an incoming circuit breaker and a primary side voltage transformer, the AC distribution board is used to supply power to the rectifier transformer, the propulsion inverter also includes an output filter unit and a rectifier unit and an inverter unit connected through positive and negative DC busbars, the rectifier unit is connected to the secondary winding of the rectifier transformer, the inverter unit is connected to the upper computer through a frequency conversion controller, the rectifier unit is connected to the positive and negative DC busbars of the propulsion inverter through a DC circuit breaker, the AC input is converted into a DC output, the DC circuit breaker is connected to the DC power supply through a DC boost device, and the DC power supply is used to rectify the DC power supply. When the transformer is magnetized, it provides magnetizing power to the propulsion inverter. The input side of the rectifier unit is connected to the current transformer. The output filter unit of the inverter unit is connected to the propulsion motor through the propulsion motor branch contactor to convert the DC input into an AC output with adjustable voltage. The output filter unit is connected to the fuse, the magnetizing branch contactor, the anti-reverse current diode and the current transformer in sequence and then connected to the secondary winding of the rectifier transformer. The fuse is used to perform short-circuit protection on the magnetizing circuit. The fuse, the magnetizing branch contactor, the anti-reverse current diode and the current transformer are connected in series to form a magnetizing circuit. The anti-reverse current diode is used to prevent the voltage on the secondary side of the transformer from being higher than the output voltage of the inverter unit in certain circumstances, causing the inverter unit to be damaged due to reverse work. The propulsion inverter drives the propulsion motor or provides power to the magnetizing branch. The frequency converter is connected to the secondary winding of the rectifier transformer through the secondary side voltage transformer, and the primary side voltage transformer and the current transformer are connected to the frequency converter.

[0011] The described ship electric propulsion system rectifier transformer magnetizing circuit, its frequency conversion controller includes a processor unit, an input filtering module, a phase difference sampling module, an amplitude sampling module, a peak sampling module and a signal input port connected to a host computer, a primary side voltage transformer, a secondary side voltage transformer and a current transformer, and a signal output port connected to a magnetizing branch contactor, a DC circuit breaker, a propulsion motor branch contactor, an inverter unit and a rectifier transformer power supply switch.

[0012] In the magnetizing circuit of the rectifier transformer of the ship electric propulsion system, the frequency conversion controller obtains the primary and secondary voltages and the voltage phase difference of the rectifier transformer in the following manner: the frequency conversion controller receives the primary voltage signal of the rectifier transformer outputted by the primary voltage transformer. The secondary voltage signal of the rectifier transformer output by the secondary voltage transformer , after being filtered by the input filter module, they are input to the phase difference sampling module and the amplitude sampling module respectively; the phase difference sampling module and the amplitude sampling module respectively output the primary side voltage signal and the secondary side voltage signal Phase difference And the amplitude and to the processor unit.

[0013] The rectifier transformer magnetizing circuit of the ship electric propulsion system is characterized in that the propulsion frequency converter is an AC-DC-AC voltage source frequency converter; the rectifier unit adopts a three-phase uncontrolled rectifier bridge composed of diodes, and the inverter circuit of the inverter unit adopts a three-phase bridge inverter composed of IGBTs.

[0014] The rectifier transformer magnetizing circuit of the ship electric propulsion system has a rectifier transformer power supply switch, a propulsion motor branch contactor, a DC circuit breaker, and a magnetizing branch contactor, all of which have the function of remote control operation and are controlled by a frequency conversion controller.

[0015] Compared with the existing rectifier transformer excitation inrush current suppression circuit, the present invention has the following beneficial effects: 1. The propulsion inverter in the ship's electric propulsion system is used as a magnetizing device. Only the magnetizing circuit from the propulsion inverter to the rectifier transformer is added, which has a simple structure, low cost and high reliability. 2. No need to add special magnetizing equipment such as magnetizing transformers, which greatly saves cabin space and reduces equipment procurement costs; 3. It can completely eliminate the excitation inrush current when the rectifier transformer is put into use, and the excitation inrush current suppression effect is good; 4. The overcurrent quick-break protection of the rectifier transformer power supply switch does not need to avoid the excitation surge current during setting. Therefore, a smaller value can be used for the protection action current during setting, thereby improving the sensitivity of the protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A rectifier transformer magnetizing circuit based on a magnetizing transformer for an existing ship electric propulsion system; Figure 2 A rectifier transformer magnetizing circuit of the present invention; Figure 3 It is a structural diagram of the frequency conversion controller of the present invention; Figure 4 This is a flow chart of the magnetizing method of the rectifier transformer magnetizing circuit of the present invention.

[0017] The reference numerals of the figures are as follows: 1-1—rectifier transformer power supply switch, 1-2—rectifier transformer, 1-3—pre-magnetizing transformer, 1-4—frequency converter, 1-5—propulsion motor, 1-6—magnetizing circuit contactor, 2-1—incoming circuit breaker, 2-2—AC distribution board, 2-3—primary side voltage transformer, 2-4—DC power supply, 2-5—DC boost device, 2-6—host computer, 2-7—frequency converter, 2-8—secondary side voltage transformer, 2- 9—DC circuit breaker, 2-10—rectifier transformer, 2-11—output filter unit, 2-12—propulsion motor branch contactor, 2-13—propulsion motor, 2-14—AC bus, 2-15—rectifier transformer power supply switch, 2-16—current transformer, 2-17—rectifier unit, 2-18—inverter unit, 2-19—anti-reverse current diode, 2-20—magnetization branch contactor, 2-21—fuse, 2-22—propulsion inverter. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0019] It is understandable that the technical terms, English abbreviations, etc. that appear in the following text are all prior art, and those skilled in the art can understand their meanings based on the context, and will not be explained in detail in this article due to space constraints.

[0020] In the description of the present application, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] Considering that the propulsion frequency converter in the ship power system usually adopts AC-DC-AC topology, has a fully functional inverter unit and frequency converter, and the propulsion frequency converter is in a non-working state when the rectifier transformer is magnetized. Therefore, the present invention designs a magnetizing circuit from the propulsion frequency converter to the rectifier transformer, and at the same time adds a special magnetizing working mode method to the frequency converter. The ship electric propulsion system can completely eliminate the excitation inrush current of the rectifier transformer without adding special equipment such as the above-mentioned magnetizing transformer, thereby realizing safe startup of the rectifier transformer.

[0023] The present invention discloses a magnetizing circuit for a rectifier transformer of a ship electric propulsion system, as shown in the attached Figure 2 The shown includes an AC distribution board 2-2, a rectifier transformer 2-10, a propulsion inverter 2-22, a propulsion motor 2-13, a propulsion motor branch contactor 2-12, a magnetizing branch contactor 2-20, a secondary side voltage transformer 2-8, a magnetizing branch current transformer 2-16, an anti-reverse current diode 2-19, a fuse 2-21, a DC power supply 2-4, a DC boost device 2-5, a DC circuit breaker 2-9, a frequency conversion controller 2-7 and a host computer 2-6.

[0024] In a preferred embodiment, the rectifier transformer 2-10 is a double-winding transformer, and in order to suppress the third harmonic, the wiring form is Dy11. If it is necessary to further improve the rectification effect and reduce the harmonic content in the positive and negative buses in the propulsion inverter 2-22, in another preferred embodiment, the rectifier transformer 2-10 is a three-winding transformer, and the wiring form is Dy11d0, which together with the propulsion inverter 2-22 constitutes a 12-pulse rectifier circuit.

[0025] Furthermore, the AC distribution board 2-2 includes an incoming circuit breaker 2-1, an AC busbar 2-14, a rectifier transformer power switch 2-15, and a primary voltage transformer 2-3. The propulsion inverter 2-22 includes a rectifier unit 2-17, an inverter unit 2-18, and an output filter unit 2-11.

[0026] As attached Figure 2 As shown, in a preferred embodiment, the equipment of the rectifier transformer magnetizing circuit is connected in the following manner: the AC bus 2-14 of the AC distribution board 2-2 is connected to the ship's AC power supply through the incoming line circuit breaker 2-1. Specifically, the ship's AC power supply is a diesel generator or a steam turbine generator of the ship. The primary winding of the rectifier transformer 2-10 is connected to the AC bus 2-14 through the rectifier transformer power switch 2-15, and the secondary winding is connected to the rectifier unit 2-17 of the propulsion inverter 2-22. The rectifier unit 2-17 of the propulsion inverter 2-22 is connected to the inverter unit 2-18 through the positive and negative DC busbars. The inverter unit 2-18 is connected to the propulsion motor 2-13 through the output filter unit 2-11 and the propulsion motor branch contactor 2-12. The DC power supply 2-4 is connected to the positive and negative DC busbars of the propulsion inverter 2-22 through the DC boost device 2-5 and the DC circuit breaker 2-9. The fuse 2-21 is connected to the output filter unit 2-11 of the frequency converter. The current transformer 2-16 is connected to the input side of the rectifier unit 2-17. The fuse 2-21, the magnetizing branch contactor 2-20, the anti-reverse current diode 2-19 and the current transformer 2-16 are connected in series to form a magnetizing circuit.

[0027] The AC distribution board 2-2 is used to supply power to the rectifier transformer 2-10, and the propulsion inverter 2-22 is used to provide power to the magnetization branch or drive the propulsion motor. The rectifier unit 2-17 is used to convert the AC input into a DC output, and the inverter unit 2-18 is used to convert the DC input into an AC output with adjustable voltage. The DC power supply 2-4 is used to provide magnetization power to the propulsion inverter 2-22 when the rectifier transformer 2-10 is magnetized. Furthermore, in a preferred embodiment, the DC boost device 2-5 adopts a DC / DC Boost circuit to output a DC voltage Greater than the rated voltage of the secondary side of the rectifier transformer The fuse 2-21 is used to provide short-circuit protection for the magnetizing circuit. To prevent malfunction, the rated current of the fuse 2-21 is is greater than the maximum current flowing through the magnetizing branch contactor 2-20 during the magnetizing process of the rectifier transformer 2-10. Preferably, the rated current of the fuse 2-21 is >10A. The anti-reverse current diode 2-19 is used to prevent the voltage on the secondary side of the transformer from being higher than the output voltage of the inverter unit 2-18 in some cases, causing the inverter unit 2-18 to be damaged due to reverse work. Since the no-load excitation current of the rectifier transformer is very small, generally only about 2A to 5A, the discharge capacity of the lead-acid or lithium battery pack in the ship's DC system can fully withstand it, so it is preferred that the DC power supply 2-4 is played by the battery pack on the ship.

[0028] Further, in a preferred embodiment, the propulsion inverter 2-22 is an AC-DC-AC voltage source inverter. The inverter circuit of the inverter unit 2-18 adopts a fully controlled device. Preferably, the rectifier unit 2-17 adopts a three-phase uncontrolled rectifier bridge composed of diodes, and the inverter unit 2-18 adopts a three-phase bridge inverter composed of IGBTs.

[0029] Furthermore, in a preferred embodiment, the rectifier transformer power supply switch 2-15, the propulsion motor branch contactor 2-12, the DC circuit breaker 2-9, and the magnetizing branch contactor 2-20 all have the function of remote control operation, and the separation and connection are controlled by the frequency conversion controller 2-7.

[0030] Further, in a preferred embodiment, as shown in the attached Figure 3As shown, the frequency conversion controller 2-7 includes a processor unit, an input filter module, a phase difference sampling module, an amplitude sampling module, a peak sampling module and an input and output interface. Specifically, the signal input port and the signal output port include an analog input interface, a switch input interface, an analog output interface and a switch output interface. The signal input port is connected to the host computer 2-6, the primary side voltage transformer 2-3, the secondary side voltage transformer 2-8 and the current transformer 2-16, and the signal output port is connected to the magnetizing branch contactor 2-20, the DC circuit breaker 2-9, the propulsion motor branch contactor 2-12, the inverter unit 2-18 and the rectifier transformer power supply switch 2-15. Preferably, the processor unit of the frequency conversion controller 2-7 adopts the GD32 series MCU chip of GigaDevice Innovation.

[0031] Further, in a preferred embodiment, the rectifier transformer power supply switch 2-15, the propulsion motor branch contactor 2-12, the DC circuit breaker 2-9, and the magnetization branch contactor 2-20 have switch input and output interfaces, which can receive the closing / opening signal from the frequency conversion controller 2-7 and perform corresponding actions, and feed back the closing / opening state to the frequency conversion controller 2-15. The frequency conversion controller 2-7 has control software, and the frequency conversion controller 2-7 has two working modes, namely, the magnetization mode and the propulsion mode.

[0032] Reference Figure 4 As shown, the present invention discloses a method for magnetizing a rectifier transformer by a rectifier transformer magnetizing circuit of a ship electric propulsion system, which comprises the following steps.

[0033] S-1, after the frequency conversion controller 2-7 receives the start-up instruction from the upper computer 2-6, it controls the incoming circuit breaker 2-1 of the AC distribution board 2-2 to close, and the AC bus 2-14 of the AC distribution board 2-2 is energized; the frequency conversion controller 2-7 determines whether the magnetization circuit enters the magnetization mode through the status of the rectifier transformer power supply switch 2-15.

[0034] S-2, the frequency conversion controller 2-7 enters the magnetization mode and obtains the voltage and voltage phase difference.

[0035] The frequency converter 2-7 determines whether to enter the magnetization mode in the following way: if the rectifier transformer power supply switch 2-15 is in the disconnected state, the frequency converter 2-7 enters the magnetization mode; if the rectifier transformer power supply switch 2-15 is in the closed state, the frequency converter 2-7 directly enters the propulsion mode.

[0036] Furthermore, the frequency conversion controller 2-7 obtains the primary and secondary voltages and the voltage phase difference of the rectifier transformer 2-10 in the following manner: the frequency conversion controller 2-7 receives the primary voltage signal of the rectifier transformer 2-10 outputted from the primary voltage transformer 2-3 and the secondary voltage transformer 2-8 and the secondary side voltage signal , after being filtered by the filtering module, are input to the phase difference detection module and the amplitude detection module respectively; the phase difference detection module and the amplitude detection module respectively output the primary side voltage signal and the secondary side voltage signal Phase difference And the amplitude and to the processor.

[0037] S-3, disconnect and close the incoming circuit breaker 2-1, DC circuit breaker 2-9, propulsion motor branch contactor 2-12, and magnetization branch contactor 2-20. Specifically, the frequency conversion controller 2-7 outputs a switch signal to close the DC circuit breaker 2-9 and the magnetization branch contactor 2-20, and disconnect the propulsion motor branch contactor 2-12 at the same time.

[0038] S-4, start the DC boost device 2-5 and the inverter unit 2-18. The DC boost device 2-5 starts to charge the DC bus of the propulsion inverter 2-22. When the frequency conversion controller 2-7 detects that the DC bus voltage of the propulsion inverter 2-22 When it rises to a predetermined value, the frequency conversion controller 2-7 sends a switch signal to the inverter unit 2-18, and the inverter unit 2-18 enters the working state.

[0039] S-5, inverter unit 2-18 output voltage.

[0040] After the inverter unit 2-18 is started, the frequency conversion controller 2-7 sends a voltage instruction to the inverter unit 2-18. The voltage instruction includes two parts: a voltage amplitude instruction and a voltage phase instruction. The inverter unit 2-18 outputs a voltage with a corresponding phase and amplitude according to the voltage instruction of the frequency conversion controller 2-7.

[0041] Furthermore, the voltage amplitude command is automatically given by the frequency conversion controller 2-7 according to a specific boost curve. In some embodiments, the time-voltage correspondence of the boost curve is obtained through multiple tests, which can ensure that the current flowing through the magnetizing branch contactor of the rectifier transformer during the magnetizing process does not exceed a certain threshold. Preferably, the threshold is selected as 10A.

[0042] Furthermore, the voltage phase command adopts a closed-loop control method. Preferably, the control closed loop is based on the primary side voltage signal and the secondary side voltage signal Phase difference As input, the secondary side voltage signal As output, through the closed-loop control algorithm, Tends to 0. Preferably, the closed-loop control algorithm uses voltage closed-loop PI control.

[0043] Furthermore, the frequency of the output voltage of the inverter unit 2-18 is the same as the voltage frequency of the AC bus 2-14. In most domestic embodiments, the frequency of the output voltage of the inverter unit 2-18 and the voltage frequency of the AC bus 2-14 are both the industrial frequency 50 Hz.

[0044] S-6, the frequency conversion controller 2-7 detects whether the amplitude and phase of the primary and secondary voltages of the rectifier transformer 2-10 are less than the threshold value.

[0045] The frequency conversion controller 2-7 detects whether the magnitude of the current flowing through the magnetizing branch contactor 2-20 exceeds the threshold value through the magnetizing branch current transformer 2-16. If the current exceeds the threshold value, the voltage amplitude command of the frequency conversion controller 2-7 will stop increasing and wait until the current drops below the threshold value before continuing to increase the voltage. Furthermore, the frequency conversion controller 2-7 detects the voltage amplitude of the secondary side of the rectifier transformer 2-10. Rising to the primary side voltage , and the phase difference When it approaches 0, the frequency conversion controller 2-7 determines that the magnetization is successful. Preferably, the frequency conversion controller 2-7 determines based on ,and .

[0046] S-7, disconnect and close the incoming circuit breaker 2-1, DC circuit breaker 2-9, propulsion motor branch contactor 2-12, and magnetization branch contactor 2-20, the inverter unit 2-18 stops working, and the magnetization is completed.

[0047] After the frequency conversion controller 2-7 determines that the magnetization is successful, it closes the rectifier transformer power supply switch 2-15 and disconnects the DC circuit breaker 2-9. After a certain delay, for example, a delay of about 3 seconds, the frequency conversion controller 2-7 outputs a switch signal to block the output pulse of the inverter unit 2-18, closes the propulsion motor branch contactor 2-12, and disconnects the magnetization branch contactor 2-20.

[0048] S-8, the frequency conversion controller 2-7 switches to propulsion mode.

[0049] After the frequency conversion controller 2-7 is switched to the propulsion operation mode, in the propulsion control mode, the frequency conversion controller 2-7 controls the output voltage of the inverter unit 2-18 according to the speed command given by the host computer 2-6, and then controls the speed of the propulsion motor 2-13.

[0050] The magnetization method disclosed in the present invention uses a new magnetization circuit and a magnetization mode to make the best use of the existing equipment of the ship's electric propulsion system to complete the magnetization process of the rectifier transformer. Compared with the prior art, the technical solution provided by the present invention, on the one hand, removes the magnetization transformer, simplifies the composition of the equipment, reduces the volume of the entire system, greatly improves the space utilization rate of the ship, and significantly reduces the cost while having higher reliability. On the other hand, it effectively controls the magnetization current during the magnetization process of the rectifier transformer, eliminates the impact of the magnetization surge current on the power switch, thereby greatly reducing the overcurrent setting value of the power switch relay protection device, thereby improving the sensitivity of the relay protection device to short-circuit faults, and further improving the protection efficiency.

[0051] The present invention uses the Xinzheng magnetizing circuit and magnetizing mode to make the best use of the existing equipment of the ship's electric propulsion system to complete the magnetizing process of the rectifier transformer. Compared with the prior art, the technical solution provided by the present invention, on the one hand, removes the magnetizing transformer, simplifies the composition of the equipment, reduces the volume of the entire system, greatly improves the space utilization rate of the ship, and greatly reduces the cost while having higher reliability. On the other hand, it effectively controls the magnetizing current during the magnetizing process of the rectifier transformer, eliminates the impact of the magnetizing surge current on the power switch, thereby greatly reducing the overcurrent setting value of the power switch relay protection device, thereby improving the sensitivity of the relay protection device to short-circuit faults, and further improving the protection efficiency.

[0052] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A rectifier transformer magnetizing circuit for a ship electric propulsion system, characterized in that: The invention comprises an AC busbar (2-14) connected to the primary winding of a rectifier transformer (2-10) via a rectifier transformer power supply switch (2-15) on an AC distribution board (2-2), and a propulsion frequency converter (2-22) connected to the secondary winding of the rectifier transformer (2-10), wherein the AC busbar (2-14) is connected to the ship's AC power supply via an incoming line circuit breaker (2-1), and the AC distribution board (2-2) is also provided with an incoming line circuit breaker (2-1) and a primary side voltage transformer (2-3), and the propulsion frequency converter (2-22) is connected to the secondary winding of the rectifier transformer (2-10). The frequency converter (2-22) further includes an output filter unit (2-11) and a rectifier unit (2-17) and an inverter unit (2-18) connected via positive and negative DC busbars. The inverter unit (2-18) is connected to a host computer (2-6) via a frequency converter controller (2-7). The rectifier unit (2-17) is connected to the positive and negative DC busbars of the propulsion frequency converter (2-22) via a DC circuit breaker (2-9). The DC circuit breaker (2-9) is connected to a DC power supply (2-4) via a DC boost device (2-5). The input side of (2-17) is connected to the current transformer (2-16), the output filter unit (2-11) is connected to the propulsion motor (2-13) through the propulsion motor branch contactor (2-12), converting the DC input into an AC output with adjustable voltage, the output filter unit (2-11) is sequentially connected to the fuse (2-21), the magnetizing branch contactor (2-20), the anti-reverse current diode (2-19) and the current transformer (2-16), and then connected to the secondary winding of the rectifier transformer (2-10), the fuse The magnetizing circuit is formed by connecting a magnetizer (2-21), a magnetizing branch contactor (2-20), a reverse current protection diode (2-19) and a current transformer (2-16) in series, and a propulsion inverter (2-22) drives a propulsion motor (2-13) or provides power to the magnetizing circuit. The frequency converter (2-7) is connected to the secondary winding of the rectifier transformer (2-10) via a secondary voltage transformer (2-8), and the primary voltage transformer (2-3) and the current transformer (2-16) are connected to the frequency converter (2-7).

2. A rectifier transformer magnetizing circuit for a ship electric propulsion system according to claim 1, characterized in that: The frequency conversion controller (2-7) comprises a processor unit, an input filter module, a phase difference sampling module, an amplitude sampling module, a peak sampling module, and a signal input port connected to a host computer (2-6), a primary side voltage transformer (2-3), a secondary side voltage transformer (2-8), and a current transformer (2-16), and a signal output port connected to a magnetizing branch contactor (2-20), a DC circuit breaker (2-9), a propulsion motor branch contactor (2-12), an inverter unit (2-18), and a rectifier transformer power supply switch (2-15).

3. A rectifier transformer magnetizing circuit for a ship electric propulsion system according to claim 2, characterized in that: The frequency conversion controller (2-7) receives the primary side voltage signal of the rectifier transformer (2-10) output from the primary side voltage transformer (2-3) The secondary side voltage signal of the rectifier transformer (2-10) output by the secondary side voltage transformer (2-8) , after being filtered by the input filter module, they are input to the phase difference sampling module and the amplitude sampling module respectively; the phase difference sampling module and the amplitude sampling module respectively output the primary side voltage signal and the secondary side voltage signal Phase difference And the amplitude and to the processor unit.

4. A rectifier transformer magnetizing circuit for a ship electric propulsion system according to claim 1, 2 or 3, characterized in that: The propulsion inverter (2-22) is an AC-DC-AC voltage source inverter; the rectifier unit (2-17) adopts a three-phase uncontrolled rectifier bridge composed of diodes, and the inverter circuit of the inverter unit (2-18) adopts a three-phase bridge inverter composed of IGBTs.

5. A rectifier transformer magnetizing circuit for a ship electric propulsion system according to claim 4, characterized in that: The rectifier transformer power supply switch (2-15), propulsion motor branch contactor (2-12), DC circuit breaker (2-9), and magnetizing branch contactor (2-20) are controlled to be opened and closed by a frequency conversion controller (2-7).

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